CONJUGATED LOW COORDINATE ORGANOPHOSPHORUS MATERIALS:
SYNTHESIS, CHARACTERIZATION AND PHOTOCHEMICAL STUDIES
By
VITTAL BABU GUDIMETLA
Submitted in partial fulfillment of the requirements for the degree of
Doctor of Philosophy
Thesis Advisor: Dr. John D. Protasiewicz
Department of Chemistry
CASE WESTERN RESERVE UNIVERSITY
January, 2010
CASE WESTERN RESERVE UNIVERSITY
SCHOOL OF GRADUATE STUDIES
We hereby approve the thesis/dissertation of
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candidate for the ______degree *.
(signed)______(chair of the committee)
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*We also certify that written approval has been obtained for any proprietary material contained therein.
Dedicated to my parents
Table of Contents
List of Tables………………………………………………………………………………i
List of Figures…………………………………………………………………………….iii
List of Charts…………………………………………………………………………….vii
List of Schemes……………………………………………………………………………x
List of Abbreviations…………………………………………………………………….xii
Acknowledgement………………………………………………………………………xiv
Abstract…………………………………………………………………………………xvi
Chapter 1. Introduction
1.1 Conjugated Organic Materials: General Introduction …………….………1
1.2 Mutiple (pπ-pπ ) Bonding in Main Group Elements: Brief Historical
Background………………………………………………………………..3
1.3 Double Bond Rule and σ vs π Bonding in Main Group Elements…….…..5
1.4 Acyclic π-Conjugated Organophosphorus Materials…………..……..…...7
1.5 Cyclic π-Conjugated Organophosphorus Materials…………..…..……...11
1.5.1 Six Membered Cyclic Compounds………………………………12
1.5.2 Five Membered Cyclic Compounds……………………………..12
1.6 Conjugated Organophosphorus Materials: Phosphorus the Carbon
Copy……………………………………………………………………..13
1.7 Recent Developments in Conjugated Organophosphorus Materials…….15
1.7.1 π-Conjugated Organophosphorus Polymers and Materials…...... 16
1.8. Proposed Research Studies………………………………………………18 1.8.1 meta-Terphenyl Phosphaalkenes: Synthesis, Characterization and
Photochemical Studies………………………………………………...... 18
1.8.2 meta-Terphenyl Phosphaalkenes Bearing Electron Donating and
Accepting Groups……..…………………………………………………20
1.8.3 meta-Terphenyl Phosphaalkenes to 2,6-Diarylsubstituted-Benzo-
bis(oxaphospholes)………………………………………….………..….21
1.9 References………………………………………………………...... 22
Chapter 2. Photochemical Isomerization of meta-Terphenyl Protected
Phosphaalkenes…………………………………………………………………..27
2.1. Introduction………………………………………………………………27
2.2 Results and Discussion…………………………………………………..32
2.3 UV-vis Spectral Studies of E and Z Isomers………………………….…40
2.4 Single Crystal Structure Analysis of E and Z Isomers…………………...41
2.5 Variable Temperature 1H NMR Studies…………………………………45
2.6 Conclusions………………………………………………………………49
2.7 Experimental Section…………………………………………………….50
2.8 References………………………………………………………………..54
Chapter 3. meta-Terphenyl Phosphaalkenes Bearing Electron Donating and
Accepting Groups………………………………..………………………………………57
3.1. Introduction………………………………………………………………57
3.2. Results and Discussion…………………………………………………..61
3.2.1. Synthesis of phosphaalkenes and functionalized meta-terphenyls..61
3.2.2. UV-vis Absorption Data…………………………………………..65
3.2.3. X-ray Crystallographic Studies……………………………………67
3.2.4. Electrochemical Studies…………………………………………...72
3.2.5. Nonlinear Optical Studies…………………………………………77
3.3. Conclusions………………………………………………………………77
3.4. Experimental Section…………………………………………………….78
3.5. References………………………………………………………………..91
Chapter 4. Synthesis and Studies of 2,6-Diaryl-Benzo-bis(1,3-oxaphospholes)………...96
4.1 Introduction…………………………………………………………………..96
4.2. meta-Terphenyl Phosphaalkenes to Benzoxaphospholes…………..……….97
4.3. Benzoxaphospholes……………………………………………………...…100
4.4. Results and Discussions……………………………………………………101
4.4.1. Benzoxaphospholes: Synthesis of Key Intermediates…………...104
4.4.2.Synthesis of 2,6-Diaryl-Benzo-bis(1,3-oxaphospholes)…….……107
4.4.3. Spectroscopic Studies……………………………………………111
4.4.4. Electrochemical Studies…………………………………...……..114
4.5. Conclusions………………………………………………………………...117
4.6. Experimental Section………………………………………………………117
4.7. References………………………………………………………………….123
Chapter 5. Summary……………...………………………………………….…………127
5.1. Photochemical Isomerization ………………………………...…..…….127
5.2. Effect of Substituents on meta-Terphenyl Phosphaalkenes…………….129
5.3. Synthesis and Studies of 2,6-Diaryl-Benzo-bis(1,3-oxaphospholes)…. 133 Appendix………………………………………………….....………………………….135
Bibilogrphy……………………………………………………………………..………223
List of Tables
Chapter 1.
Table 1.1. The σ and π bond strengths for selected diatomic molecule……………..……6
Table 1.2. Electronegativities for selected group 14 to group 16 elements…………..…14
Chapter 2.
Table 2.1. meta-Terphenyl phosphaalkenes and synthetic yields……………………….33
Table 2.2. UV-Vis absorption spectral data for 2.5a – 2.8a (CHCl3)……………...……34
1 31 Table 2.3. H and P{H} NMR data for E and Z phosphaalkenes (CDCl3)……………35
Table 2.4. E-Z conversion data in a photochemical reactor upon exposure to 350 nm light source for the compounds 2.5a – 2.8a (CDCl3)……………………………………38
Table 2.5. UV-vis absorption data of 2.8a and 2.8b…………………………………….41
Table 2.6. X-ray crystallography data for the compounds 2.8a and 2.8b……………….43
Table 2.7. Selected bond lengths (Å) and bond angles (°) of 2.8a and 2.8b…...……….44
Table 2.8. Variable temperature NMR data and the rate constant obtained from a two site exchange model in WINDNMR…………………………………………………………48
Chapter 3.
Table 3.1. Synthesized phosphaalkenes and 31P{1H} NMR data………………………..64
Table 3.2. UV-vis absorption data for the synthesized meta-terphenyl phosphaalkenes in
CHCl3………………………………………………………………………………….....66
Table 3.3. Crystallographic data for the compounds 3.8, 3.9, 3.10 and 3.12……………70
Table 3.4. Selected structural data for structures 3.8, 3.9, 3.10 and 3.12…………….…71
Table 3.5. Half wave potentials for the selected phosphaalkenes……………………….76
i
Chapter 4.
Table 4.1. Cyclic voltammogram data of 4.40 and 4.41……………………………….116
ii
List of Figures
Chapter 1.
Figure 1.1. The highest occupied molecular orbitals (HOMO) in a phosphaaethylene…14
Figure 1.2. Effect of phosphorus incorporation into the conjugated –C=C- system……16
Chapter 2.
31 Figure 2.1. P{H} NMR of 2.8a (CDCl3), before exposure to sunlight………………..36
1 Figure 2.2. H NMR of 2.8a (CDCl3) after exposure to sunlight, a mixture of 2.8a and
2.8b can be seen in the NMR……………………………………………….……………36
1 Figure 2.3. {H} NMR of 2.8a (CDCl3), before exposure to sunlight…………..………37
1 Figure 2.4. H NMR of 2.8a (CDCl3) after exposure to sunlight, mixture of 2.8a and 2.8b can be seen in the NMR…………………………………………………………….……37
Figure 2.5. Model pictorial representation of Rayonet UV photochemical reactor…….38
Figure 2.6. Photochemical equilibration of the phosphaalkene 2.8a -2.8b in the photochemical reactor………………………………………..…………………………..39
Figure 2.7. UV-Vis absorption spectra of 2.8a and 2.8b………………………………..40
Figure 2.8. ORTEP diagram of 2.8a (30% probability ellipsoids)……...………………42
Figure 2.9. ORTEP diagram of 2.8b (30% probability ellipsoids)……………………...42
1 Figure 2.10. H NMR (400MHz) of isolated 2.8b in CDCl3……………………………46
Figure 2.11. Variable temperature (experimental) 1H NMR spectra of 2.8b (Z-isomer) in
CDCl3…………………………………………………………………………………….46
Figure 2.12. Variable temperature (simulated by WINDNMR) NMR spectra of 2.8b (Z- isomer) in CDCl3………………………………………..………………………………..47
Figure 2.13. Eyring and Arrhenius plots for calculating the thermodynamic parameters
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for the hindered rotation………………………………………………………………….48
Chapter 3.
Figure 3.1. UV-vis absorption spectra of synthesized meta-terphenyl phosphaalkenes in
CHCl3...... 65
Figure 3.2. Single crystal X-ray crystallographic structure of
E-2,6-Mes2C6H3P=C(H)C6H4-4-NO2 (3.8) shown at the 50% thermal ellipsoid level….67
Figure 3.3. Single crystal X-ray crystallographic structure of
E-2,6-Mes2C6H3P=C(H)C6H4-4-CN (3.9) shown at the 50% thermal ellipsoid level…...68
Figure 3.4. Single crystal X-ray crystallographic structure of
E-4-MeO-2,6-Mes2C6H2P=C(H)C6H4-4-CN (3.10) shown at the 50% thermal ellipsoid level………………………………………………………………………………………68
Figure 3.5. Single crystal X-ray crystallographic structure of
E-4-MeO-2,6-Mes2C6H2P=C(H)C6H5 (3.12) shown at the 50% thermal ellipsoid level..69
Figure 3.6. Substituent effects and the crystal structure of conjugated phosphaalkenes..72
Figure 3.7. Cyclic voltammogram of 3.7,
0.001M E-[2,6-Mes2C6H3P=C(H)C6H5]/0.001M ferrocene in 0.1M [n-Bu4N][BF4] in
THF with 0.1 V/s scan rate………………………………………………………………73
Figure 3.8. Cyclic voltammogram of 3.9,
0.001M E-[2,6-Mes2C6H3P=C(H)C6H4-CN]/0.001M ferrocene in 0.1M [n-Bu4N][BF4] in
THF with 0.1 V/s scan rate, an overlay of the second redox potential shown in dotted lines………………………………………………………………………………………74
Figure 3.9. Cyclic voltammogram of 3.10,
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0.001M E-[4-CH3O-2,6-Mes2C6H2P=C(H)C6H4-CN]/0.001M ferrocene in 0.1M [n-
Bu4N][BF4] in THF with 0.1 V/s scan rate, an overlay of the second redox potential shown in dotted lines……………………………………………………………..……...74
Figure 3.10. Cyclic voltammogram of 3.12,
0.001M/0.001M ferrocene in 0.1M [n-Bu4N][BF4] in THF with 0.1 V/s scan rate……..75
Chapter 4.
Figure 4.1. Molecular structure of (4.3) meta-terphenyl phosphaalkene (θ ≠ 0 or
180) and an analogous (4.4) 2-aryl-1,3-benzoxaphosphole (θ ≈ 0 or 180).……………...98
Figure 4.2. The 31P{1H} NMR (CDCl3) of 4.21 before (a) and after (b) reduction with LiAlH4……………………………………………………………………………..106
Figure 4.3. The fluorescent nature of the compound 4.23 on exposure to UV light
31 1 (365 nm) in CDCl3, and its respective P{ H} NMR in CDCl3………………………108
Figure 4.4. UV-vis absorption spectra of E-BBOP’s (4.40 and 4.41) in CHCl3……….112
Figure 4.5. Fluorescence spectra of 4.40 and 4.41 in CHCl3…………………...….…..113
Figure 4.6 Cyclic voltammogram of 4.40, 0.001M 4.40/0.001M ferrocene in
0.1M [n-Bu4N][BF4] in THF with 0.1 V/s scan rate…………...... ……………………..115
Figure 4.6. Cyclic voltammogram of 4.41, 0.001M 4.41/0.001M ferrocene in
0.1M [n-Bu4N][BF4] in THF with 0.1 V/s scan rate…………………………..………..115
Chapter 5.
Figure 5.1. The 31P{1H} NMR of Dmp diphosphene (DmpP=PDmp) and
(Br-DmpP=CHPh-Br) before and after exposure to 350 nm light…………………..….128
Figure 5.2. NMR (31P, 1H) of the crude dimethylamino and cyano substituted phosphaalkene……………………………………………………………….………….130
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Figure 5.3. 1H and 31P{1H} NMR of methoxy substituted meta-terphenyl diphosphene………………….…...…………………………………………………….131
Figure 5.4. Single crystal structure of methoxy substituted diphosphene……………..132
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List of Charts
Chapter 1.
Chart 1.1. Few selected examples for conjugated materials (1.1.A - 1.1.D)…….....…….1
Chart 1.2. Isolobal analogy of low coordinate organophosphorus compounds with alkenes and alkynes………………………………………………………………….3
Chart 1.3. The first attempted synthesis of phosphobenzene…………………………….4
Chart 1.4. Structures of Salvarasan from As=As based system to cyclic oligomers….….4
Chart 1.5. Iminophosphine, the first reported stable and isolated phosphorus compound with P=N double bond similar to alkenes…………………………………………………7
Chart 1.6. Phosphaalkene, the first reported stable phosphaalkene (P=C)……………….8
Chart 1.7. The first reported double (pπ-pπ) bonding between the heavy main group elements……………………………………...……………………………………………8
Chart 1.8. The first reported phosphorus-carbon heterocyclic compound…………...…11
Chart 1.9. Examples for few classes of organophosphorus heterocyclic compounds…..12
Chart 1.10. First low coordinate phosphorus-carbon heterocyclic compound………….12
Chart 1.11. First five membered phosphorus-carbon heterocyclic compound …………13
Chart 1.12. Examples of π-conjugated materials and their respective π-conjugated organophosphorus compounds………………………..………………………………….15
Chart 1.13. π-conjugated phospha-PPV’s featuring phosphaalkene (P=C) bonds……..17
Chart 1.14. Thioxophospholes used as OLED material……………………………..….17
Chart 1.15. Photochemical isomerization of Mes*-diphosphenes and Mes*-
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phosphaalkenes…………………………………………………………………………..19
Chart 1.16. E-Z isomerization of meta-terphenyl protected diphosphenes and phosphaalkenes………………………………………………..…………………………19
Chart 1.17. Charge polarized meta-terphenyl phosphaalkenes…………………………20
Chart 1.18. Molecular structure of (A) meta-terphenyl phosphaalkene (θ ≠ 0 or 180) and an analogous (B) 2-aryl-1,3-benzoxaphosphole (θ ≈ 0 or 180)………...…………….….21
Chart 1.19. 2,6-diarylsubstituted-benzo-bis(1,3)-oxaphospholes……………..………...22
Chapter 2.
Chart 2.1. Photochemical E-Z isomerization of stilbene and its main group analogues
(imine, phosphaalkene, azo and diphosphene)………………….……………………….28
Chart 2.2. Photochemical isomerization of Mes*-diphosphenes and Mes*- phosphaalkenes…………………………………………………………………………..30
Chart 2.3. Photochemical isomerization of Dmp-diphosphenes and Dmp- phosphaalkenes…………………………………………………….……….……………30
Chart 2.4. “Dmp” protected phosphaalkenes used for photochemical studies………….31
Chapter 3.
Chart 3.1. Resonance structures for phosphaalkene……………………….……………57
Chart 3.2. Effects of substituent groups on the structures and properties………………58
Chart 3.3. Diarylamino substituted diphosphenes………………………………………59
Chart 3.4. A selected example for an inversely polarized phosphaalkenes……………..59
Chart 3.5. Effect of substituents on a distannyne compound…………………………...60
Chart 3.6. Charge polarization in phosphaalkenes……………………………………...60
Chart 3.7. meta-terphenyl protected phosphaalkenes…………………………………...60
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Chapter 4.
Chart 4.1. A few selected examples for aromatic organophosphorus heterocyclic compounds………………………………………………………………………….……96
Chart 4.2. Hausen et.al reported X-ray crystal structure data for
2-arylbenzoxaphosphole…………………………………………………………………97
Chart 4.3. Examples for known bis and mono-benzoxazoles…………………………...98
Chart 4.4. Examples for benzo-bisoxazole and benzo-bisthiazole polymers…………...98
Chart 4.5. New class of 1,3-heterophospholes…………………………..……………...99
Chart 4.6. Synthetic target, trans-bis-benzoxaphospholes (4.10) and known mono-benzoxaphosphole (4.11)………………………………..……………………….100
Chart 4.7. Synthesis of benzoxaphospholes by condensation methods………………..100
Chart 4.8. Synthesis of benzoxaphospholes by dehydrocyclization...…………………101
Chart 4.9. 2-phosphinophenol and 2,5-diphosphinohydroquinone………………...….102
Chart 4.10. Reductive cyclization 2-phenyl-1,3-benzophosphazole……...…………...104
Chart 4.11. Possible molecular orientations of BBOP (4.40 and 4.41) in solution……111
Chapter 5.
Chart 5.1. Synthesis of methoxy substituted meta-terphenyl diphosphene……..……..130
Chart 5.2. Benzo-bis(oxaphosphole) polymer synthesis………………………………132
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List of Schemes
Chapter 1.
Scheme 1.1. First detailed study about the importance of steric protection by kinetic stabilization, when R = a or b the reaction was successful but when R = c the reaction was unsuccessful……………………………………………………..……………………9
Scheme 1.2. First stable and isolated diphosphene (1.8)………………………...………10
Scheme 1.3. The first stable and characterized disilene (1.9)………………...…………10
Chapter 2.
Scheme 2.1. Light driven photochemical transformation……………………………….27
Scheme 2.2. Synthesis of ArPCl2 and Ar'PCl2…………………………………….…….32
Scheme 2.3. Synthesis of bromine substituted meta-terphenyl phosphaalkenes through one-pot phospha-Wittig reaction……………………..…………………………………..33
Scheme 2.4. Photochemical isomerization of meta-terphenyl phosphaalkene……..……34
Chapter 3.
Scheme 3.1. Synthesis of 4-I-2,6-Mes2C6H2Br (3.2)……………………………………61
Scheme 3.2. Synthesis of dimethylamino subsitituted aryldichlorophosphine 3.6a…….62
Scheme 3.3. Synthesis of methoxy substituted aryldichlorophosphine 3.6b……………62
Scheme 3.4. Synthetic scheme followed for making phosphaalkenes with different substituent groups………………………………………………………………………..63
Scheme 3.5. Relieving steric strains by rotating away from the planarity………………64
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Scheme 3.6. Redox process in cyano substituted phosphaalkene……………………….76
Chapter 4.
Scheme 4.1. Synthesis of 2-phosphinophenol 4.16…….………………………………103
Scheme 4.2. Synthesis of 2,5-diphosphinohydroquinone 4.16…………..…………….103
Scheme 4.3. Synthesis of simplest 2-phenyl-1,3-benzoxaphosphole using condensation of 4.12 and N-arylbenzimidoyl chloride 4.20…………...……………….104
Scheme 4.4. Synthetic scheme followed to make N-arylbenzimidoyl chloride………..105
Scheme 4.5. Reductive cyclization to oxaphospholes………………………………….106
Scheme 4.6. Synthetic attempts though arylimidateester………………………………107
Scheme 4.7. Condensation of 4.16 and N-arylimidoylchlorides to synthesize 2,6- diphenyl-benzo-bis(oxaphospholes)……………………………………………………108
Scheme 4.8. Attempts to synthesize para substituted benzo-bisoxaphospholes……….109
Scheme 4.9. Synthesis of mesityl and m-xylyl imidoylchlorides………………………110
Scheme 4.10. Synthesis of 2,6-diaryl-benzo-bis(oxaphospholes) 4.40 and 4.41………111
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List of Abbreviations
Ar aryl n-BuLi n-Butyl lithium
[n-Bu4N][BF4] tetrabutylammonium tetraborofluorate
Dmp 2,6-dimesitylphenyl
E-BBOP E-2,6-diaryl-benzo-bis(1,3-oxaphosphole)
HOMO highest occupied molecular orbitals
HRMS high resolution mass spectrometry
LUMO lowest unoccupied molecular orbitals m multiplet
MeO methoxy
Mes 2,4,6-trimethylphenyl
Mes* 2,4,6-tri-t-butylphenyl mp melting point
MS mass spectroscopy mV millivolts
NLO nonlinear optical
NMR nuclear magnetic resonance spectroscopy
ORTEP Oakridge thermal ellipsoid plot
OLED organic light emitting diodes
SCE saturated calomel electrode
xii
UV-vis Ultraviolet-viscible m-Xylyl 2,6-dimethylphenyl
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Acknowledgements
I am extremely grateful to my advisor Prof. John D. Protasiewicz, for his constant support and for his exceptional guidance to me right from the very beginning of my research program here at Case Western Reserve University. I express my deepest gratitude to him, for being a constant source of motivation and for giving me the boundless freedom to perform exciting chemistry in the lab. I am thankful for all his advices and care, which helped me a lot both personally and professionally. Without all his help, I couldn’t imagine the completion of my work.
I would like to thank all my committee members Prof. Malcolm E. Kenney, Prof.
Thomas Gray, Prof. Alfred Anderson, Prof. Fred L. Urbach, Prof. Kenneth D. Singer and
Prof. M. Cather Simpson for serving in my thesis committee and for their valuable advices. My special thanks to Prof. Malcolm E. Kenney and Prof. Thomas Gray for their invaluable suggestions and help.
I would like to thank all my past and present colleagues in Dr.P’s and Dr. Gray’s group for their help, thoughtful discussions and for their friendship. My special thanks to
Dr. Rhett C. Smith, for his guidance and training during my initial days of the research. I sincerely appreciate my colleagues Dr. Liqing Ma and Jim Updegraff for their assistance in X-ray crystallography, Marlena P. Washington for her help in electrochemical studies,
John L. Payton for sharing his thoughts and for his valuable discussions in computational chemistry. I am grateful to Dr. Dale Ray and Dr. Jim Faulk for their assistance in obtaining NMR, MS and IR spectra.
Thanks to Prof. Kenneth D. Singer (Department of Physics) and his graduate student Yeheng Wu for their help in NLO studies. Also, I thank Prof. Stuart Rowan
xiv
(Macromolecular Science and Engineering) for his valuable suggestions during the oxaphosphole project.
I also thank Prof. G. Ranga Rao, my master’s advisor from IIT Madras, for his valuable suggestions and inspiring me to pursue my graduate studies in chemistry. Also, I am very much thankful to all of my friends and in particular BG Mishra, Aravind and
Venkat from IIT Madras, Anando, Suresh, Nathan, Prasad, Jagan, Ashok and Babho from
CWRU for their invaluable friendship during my stay here at CWRU.
Importantly, I owe a lot and my deepest gratitude to my parents and siblings
Krishna, Janani and Vani for their selfless sacrifices, affection and the moral support they showered on me. Without their support and encouragement, I sincerely feel I may not have reached to this stage of education.
xv
Conjugated Low Coordinate Organophosphorus Materials: Synthesis, Characterization
and Photochemical Studies
Abstract
By
VITTAL BABU GUDIMETLA
Conjugated organic materials offer exciting possibilities in science and technology. Through chemical doping with an external substrate they can exhibit very good conducting properties on par with metals and at the same time can possess the flexibility of plastics. The polymer, poly-phenylenevinylene (PPV) is a well known conjugated organic material. Polymers and small conjugated organic materials resembling such PPV’s are known for their promise in electrooptical devices and as light emitting materials. Mostly, these are the compounds with alternating carbon-carbon (pπ-
pπ) double bonds in a conjugated aromatic network. The properties of these materials can
be tuned by molecular changes through chemical synthesis.
This study details the synthesis and characterization of such small conjugated
organophosphorus compounds having phosphorus-carbon double bonds in conjugated
carbon network. The initial study is focused on synthesis and detailed investigation on the
structural and photochemical properties of meta-terphenyl phosphaalkenes (X-Dmp-
P=C(H)-Ph-X’, Dmp: 2,6-dimesitylphenyl). Through these studies, it was observed that
these meta-terphenyl phosphaalkenes are photochemically active unlike related meta-
terphenyl diphosphene (Dmp-P=P-Dmp), but similar to Mes* diphosphene (Mes*-P=P-
Mes*, Mes*: 2,4,6-tri-tert-butylphenyl) and phosphaalkene (Mes*-P=C(H)-Ph). In
xvi
chapter 3, a detailed investigation on the synthesis and studies related to the effect of
different electron donating and accepting groups on the meta-terphenyl phosphaalkenes
(X-Dmp-P=C(H)-Ph-X’, X: H, MeO, Me2N; X’: H, CN, NO2) were discussed. The
chapter 4, details the synthesis and studies related to new molecules of the type “2,6-
diaryl-benzo-bisoxaphosphole" were reported. These new compounds found to be
relatively more stable than the synthesized meta-terphenyl phosphaalkenes. The complete synthesis and characterization of these compounds were discussed.
xvii
Chapter 1. Introduction
1.1. Conjugated Organic Materials: General Introduction
The synthesis and study of conjugated organic materials is one of the most active
fields of research in materials chemistry.1 A significant feature of these compounds is that
they are predominantly made of carbon atoms having alternating unsaturated π (pπ-pπ) bonds. The rapid growth in this field and the interest on these molecules is largely due to their potential applications as organic electronic materials. Most of these conjugated materials (Chart 1.1) are semi conductors and by doping the conducting properties of some of them can be made rival to the known metallic conductors. Due to their conductivity and excellent mechanical flexibility, these materials have also been referred as synthetic metals. The Noble prize for the year 2000 was awarded to Alan J. Heager,
Hideki Shirakawa and Alan J. MacDiarmid for their pioneering investigations of conjugated organic materials as conducting polymers.2-4
n n n
Polyparaphenylene Polyparaphenylene Polyacetylene vinylene (PPV) (PPP) (PA) 1.1.A 1.1.B 1.1.C
N S H n n
Polyaniline Polythiophene (PANI) (PT)
1.1.D 1.1.D
Chart 1.1. Few selected examples for conjugated materials (1.1.A - 1.1.D)
1
Recently, these materials found greater importance in various technological
applications such as photovoltaics, nonlinear optics, organic light emitting diodes, data
storage and in field effect transistors.2 The advantage of these materials is their unique
electrooptical properties, tunable band gap, commercial viability and easy device
fabrications. Also, the other prime advantage is that their properties can be tuned by
modifications at the molecular level through the synthetic techniques. The common modification methods include changing the molecular conformation and introducing heteroatoms into the conjugated organic backbone. This present work focuses on the synthesis and studies of conjugated organophosphorus materials containing phosphorus- carbon double bonds (pπ-pπ). In these materials, phosphorus has a coordination number of
2, even though its regular coordination number is 3 and 5.
The replacement of carbon atoms in a conjugated chemical backbone with
different heteroatoms can significantly change their physical and chemical properties.
This is an expected consequence, primarily due to their changes in the band gap energy
between the valence and conduction bands. Through which, one can tune the overall
electrooptical properties of a conjugated material. The elements from group 13, group 14
and group 15 are most widely used for these purposes and to develop new conjugated
organic materials. However, the incorporation of a main group element into the
conjugated organic backbone is a challenging synthetic task, due to the high reactivity of
the double bonds involved. Also, another important deciding factor is the ability of the
heteroatom to form low coordinate multiple bonds (π bonds) similar to carbon.
Phosphorus is a group 15 main group element and capable of exhibiting variable
coordination numbers (number of atoms connected) ranging from 1 to 6. Among all
2
possible coordination states, phosphorus has common coordination states of 3 and 5. The
low coordinate organophosphorus compounds are those in which phosphorus shows the
coordination number either 1 or 2, which is lesser than their regular coordination number.
The compounds in these coordination states actually can mimic the unsaturated carbon
chemistry due to their ability to exhibit low coordinate multiple bonds similar to that of
alkenes and alkynes and also due to their isolobal analogy (Chart 1.2).
Coordination number 2: PP PC CC
diphosphene phosphaalkene alkene
Coordination number 1: C P C C
phsophaalkyne alkyne
Chart 1.2. Isolobal analogy of low coordinate organophosphorus compounds
with alkenes and alkynes
Phosphorus being a main group element, recently a greater interest has been focused on
the multiple bonding involving heavy main group elements.
1.2. Mutiple (pπ-pπ ) Bonding in Main Group Elements: Brief Historical Background
The synthesis of multiply bonded main group molecules featuring double (pπ-pπ) bonds remains as the elusive objective. In 1877, Michaelis and K hler reported the
synthesis of the first phosphobenzene 1.2.A, which is an analogue of azobenzene made
by the condensation of phenylphosphine with phenyldichlorophosphine.3 Later it was
3 showed that the synthesized compound was not a phosphobenzene but a mixture of cyclic oligomers i.e. tetramers and pentamers of phenylphosphinidene (Chart 1.3).4,5
P P 1.2.A PH 2 PCl2
P P P P other cyclic P oligomers PP P P
1.2.B 1.2.C Chart 1.3. The first attempted synthesis of phosphobenzene
Also, a similar behavior was observed with arsenic based compound. Salvarasan (Chart
1.4) a chemotherapeutic agent made by Ehrlich in 1912 and it was believed to contain
As=As bond 1.3.A.6,7 X-ray crystallographic studies8,9 and mass spectroscopic results later confirmed that the compound was a mixture of cyclic oligomers of arsenic, as trimers to octamers.10 Even with the silicon, the initially reported (Si=Si)11 double bonded compounds later found to be a mixture of oligomers. R R R As R As As As NH 2 As As As As H2N R R R As R As OH 1.3.B R 1.3.C HO As NH2
1.3.A R= OH
Ehrlich proposed structure Suggested strcutures by X-ray crystallography and mass spectroscopic studies
Chart 1.4. Structures of Salvarasan from As=As based system to cyclic oligomers10
4
Therefore, the formation of π-conjugated system with main group elements remained synthetically elusive due to their high reactivity and their tendency to form cyclic products. This inability by the main group elements not to form multiply bonded compounds often justified by the “double bond rule”,12,13 i.e. the main group elements below the second row of the periodic table cannot form multiple bonds similar to the elements in the second row of the periodic table.
1.3. Double Bond Rule and σ vs π Bonding in Main Group Elements
The results of many unsuccessful attempts to synthesize and to isolate the materials with multiply bonded main group elements led to a mistaken conclusion, that these compounds are nonexistent and cannot be made.14 The theoretical explanations for the multiple bonding in main group elements were refined over time. In 1948, Pitzer, suggested that the weakness of π bonding between the main group elements was due to the repulsion between the valence bonding orbital with the inner shell orbital of the other atoms.12 In 1950’s, a quantitative approach was undertaken by Mulliken, through the calculation of orbital overlap integrals (S) to explain the unstable nature of the multiply bonded main group elements.15 According to this, greater orbital overlap integral should lead to greater bond strength and hence better bonding. However through this study, it was observed that for the heavy main group elements on descending a group, both the pπ-pπ and pσ-pσ orbital overlap integrals found to be increasing. Therefore, in addition to orbital overlap, the increased strengths of σ bonding down the group suggested to be the reason for poor bonding in main group elements.15
5
Kutzelnigg, tabulated the σ and π bond strengths for various elements participating in heteronuclear or homonuclear bonding.16 Norman, used this data to explain the σ and π bond strengths in main group elements.17
C-C N-N O-O σ/π (kJ mol-1) 335/295 (1.14) 160/395 (0.41) 145/350 (0.42) Si-Si P-P S-S σ/π (kJ mol-1) 195/120 (1.63) 200/145 (1.38) 270/155 (1.74) Ge-Ge As-As Se-Se σ/π (kJ mol-1) 165/110 (1.50) 175/120 (1.46) 210/125 (1.68)
Table 1.1. The σ and π bond strengths for selected diatomic molecules16,17
It can be noted from the table 1.1, that for the second row elements the π bond strengths are much higher than for heavier congeners, reflecting that the effect of increase in size resulting in decrease of π bonding in the third and fourth row molecules. This preference for the π bonding is due to the smaller size of these second row elements. This feature diminishes down the group. Among these third row elements (see Table 1.1), Si has the lowest π bond strength but it increases across the row (Si to S), in agreement with decrease in atomic size resulting in increasing π bond strength. The ratio of σ to π bond strengths for carbon (1.14) close to unity and hence the π bond formation for carbon is thermodynamically more favored than other main group elements. Therefore, for the main group elements to exhibit the multiple bonding similar to carbon, they should have closer bonding properties to that of carbon. Hence, there is a growing interest in the chemistry of carbon neighbors in the periodic table, due to their ability to show interesting π bonding and thereby widening the opportunities for new conjugated materials.
6
1.4. Acyclic π-Conjugated Organophosphorus Materials:
The compounds with multiply-bonded low coordinate main group elements were first observed as transient molecules and not as isolated compounds.18,19 Because they are thermodynamically less stable than their oligomerized products. Among the main group elements, phosphorus is one of the well studied elements for its π bonding properties. The resulting rapid growth in this field has contributed well for many new advances in main group chemistry.
In 1973, Niecke et al. reported the synthesis of the first iminophosphine (Chart
1.5), with a stable phosphorus-nitrogen (P=N) π bond. This material was made by the use of trimethylsiliyl (TMS) group as the stabilizing substituent group.20 These compounds similar to carbon the analogues have been found as E and Z isomer and their P=N bond length ~1.52 Å.21,22
TMS PN Niecke et al. 1973 TMS N TMS
1.4
Chart 1.5. Iminophosphine, the first reported stable and isolated phosphorus compound with P=N double bond
In 1976 Becker et al. synthesized and isolated the first stable phosphaalkene featuring a phosphorus-carbon (pπ-pπ) double bond (P=C). The synthesis was achieved using bulky tert-butyl and trimethylsilyl (TMS) substituent groups (Chart 1.6).
7
CMe3 Becker et al. 1976 P tBu OTMS
1.5
Chart 1.6. Phosphaalkene, the first reported stable phosphaalkene (P=C)
23 Incidentally, by using bulky -CH(TMS)2 group, Goldberg et al. synthesized the compounds with multiple bonds between the two heavy main group elements (Chart 1.6).
.
R R E= Sn,Ge EE Goldberg et al. 1976 R=CH(TMS) R R 2 1.6
Chart 1.7. The first reported double (pπ-pπ) bonding between the heavy main group elements.
In 1978, a systematic study was undertaken by Bickelhaupt et al. to understand the effect of steric stabilizing bulky groups. They attempted to synthesize a series of phosphaalkenes with different sequence of steric crowding around the P=C bond.24 It was found that in the absence of any steric crowding, polymerized or oligomerized products were formed, whereas in the presence of steric crowding the phosphaalkenes formed in significant yields (Scheme 1.1). This synthetic result demonstrates that preference of main group elements to form σ bonded polymerized products than π bonded materials.
The presence of steric crowding from the bulky groups prevents the formation of
8 oligomerized product and thereby stabilizing the π-bonded structures in main group compounds. This is one of the initial works which stresses that importance of sterics. This paved the path to explore different bulky protecting groups and thereby to synthesize more interesting compounds featuring the (pπ-pπ) double bonds among main group elements.
Ph LiCH(Ph)2 DBU RPCl2 RPCH(Ph)2 P THF, -20o C R Ph Cl 1.7
R:
(a) (b) (c)
Scheme 1.1. First detailed study about the importance of steric protection leading to kinetic stabilization, when R = a or b the reaction was successful but when R = c the reaction was unsuccessful.
By the early 1980’s, many syntheses of multiply bonded main group elements were reported. In 1981, Yoshifuji and co-workers reported the synthesis of the first stable diphosphene using bulky Mes* (2,4,6-tri-tert-butylphenyl) substituent (Scheme 1.2). The structure was also characterized by X-ray crystallographic studies, the P=P bond length is
2.034(2) Å.25
9
Yoshifuji, 1981
n-BuLi Mg Br PCl2 P PCl3 P
1.8
Scheme 1.2. First stable and isolated diphosphene (1.8).
At the same time, a stable disilene was reported by the West and co-workers, who photolysed 2,2-bis(mesityl) hexamethyltrisilane at 254 nm (Scheme 1.3). The X-ray crystallographic studies showed the Si=Si bond length was 2.160 Å, which is approximately 10 % less than the Si-Si single bond. 26,27
Mes Mes hv, 254 nm (Mes)2-Si-(TMS)2 Si Si West et al. 1981 Mes Mes 1.9
Mes : 2,4,6-tri-methylphenyl
Scheme 1.3. The first stable and characterized disilene (1.9)
Subsequently a number of multiply bonded main group compounds were reported with different steric stabilizing groups and utilized as steric protecting groups to synthesize unstable or reactive compounds.28-32
10
1.5. Cyclic π-Conjugated Organophosphorus Materials
The first phosphorus-carbon heterocycle, reported in 1915 by Grüttner et al. and it was 1-phenylphosphinane 1.10 (Chart 1.8),33 but until 1950’s not so many heterocyclic organophosphorus compounds were reported.34,35
Grüttner et al. 1915 P Ph
1.10 Chart 1.8. The first reported phosphorus-carbon heterocyclic compound
The development of phosphorus (31P) NMR facilitated the characterization of many heterocyclic organophosphorus compounds, mainly due to their large chemical shift window. As a result, many organophosphorus heterocyclic materials can be easily characterized by phosphorus NMR. The recent developments in heterocyclic organophosphorus compounds are well compiled in the book “Phosphorus-carbon heterocyclic chemistry: The rise of a new domain”.36
The following section mainly focuses on the organophosphorus heterocyclic materials (Chart 1.9) and in particular conjugated materials featuring phosphorus-carbon
(P=C) double bonds in their chemical backbone.
11
P P P P E E
1.11 1.12 1.13 1.14
Phosphinine Phosphole Heterophospholes, E=O,N,S
Chart 1.9. Examples for few classes of organophosphorus heterocyclic compounds.
1.5.1. Six Membered Cyclic Compounds
The first known phosphorus-carbon double bonded heterocycle is 2,4,6-triphenyl phosphinine (1.15), synthesized by Märkl et.al. in 1966 (Chart 1.10).37
Ph
Ph P Ph
1.15
Chart 1.10. First low coordinate phosphorus-carbon heterocyclic compound
The structural studies revealed that the phosphinine has a planar structure unlike cyclic phosphines which are non-planar, also it has a delocalized π-system38 similar to benzene.
1.5.2. Five Membered Cyclic Compounds
Phospholes (1.12) and heterophospholes (1.13-1.14) are the five membered cyclic compounds with 6π system. Phosphole is a phosphorus heterocycle with an unsaturated
12 five membered ring. This is class of material first synthesized and reported by Wittig et al. in 1951 as dibenzophosphole (Chart 1.11) .39
P Ph
1.16
Chart 1.11. First five membered phosphorus-carbon heterocyclic compound
In phospholes, phosphorus exhibits a pyramidal geometry and is expected to have less
π-type delocalization than other five membered heterocyclic compounds such as furan, thiphene, pyrrole and selenophene.40
In addition to phosphorus the presence of heteroatoms like N, O, S or Se in the phosphole backbone would lead to another class of compounds known as heterophospholes. These compounds maintain the delocalized π-electron system, similar to phospholes. Based on the position of the phosphorus and the heteroatom they are referred as 1,2-heterophospholes or 1,3-heterophospholes (Chart 1.9)
1.6. Conjugated Organophosphorus Materials: Phosphorus the Carbon Copy
Sections 1.4 and 1.5 illustrate that the phosphorus can engage in π-bonding (pπ-pπ) similar to carbon and these low coordinate phosphorus compounds can be successfully synthesized by using steric protecting groups. Therefore it is evident that the phosphorus in its low coordination state can (coordination number 2) can mimic the chemistry of unsaturated carbon-carbon double bonds. As discussed in earlier sections, this can be explained through their diagonal relationship in the periodic table, closer
13 electronegativity and close σ/π bond energy ratios (σ/π, carbon : 1.14; phosphorus : 1.38)
(Table 1.2).
Group 14 Group 15 Group 16 C(2.5) N(3.0) O(3.5)
Si(1.9) P(2.2) S(2.5)
Ge(2.0) As(2.2) Se(2.6)
Table 1.2. Electronegativities for selected group 14, 15 and 16 elements.
Also, the photoelectron spectroscopic studies of Lacombe and co-workers showed that the highest occupied molecular orbital (HOMO) in a phosphaaethylene (HP=CH2) is the
π (πC=P) orbital similar to ethylene.
H
CP -10.30 eV HOMO
H H E(eV)
H
CP -10.70 eV LUMO
H H
Figure 1.1. The highest occupied molecular orbitals (HOMO) in a phosphaaethylene by photoelectron spectroscopy measurements41
These frontier orbitals control the chemical reactivity and hence the phosphaalkene based materials react more or less similar to alkenes. In the case of carbon nitrogen double bonded imine (C=N), the HOMO is occupied by the lone pair electrons
14 and thus the reactivity is mainly lone pair driven. In summary, these studies indicate that the properties exhibited by phosphorus-carbon (pπ-pπ) double bonded compounds are expected to be similar to those of carbon-carbon (pπ-pπ) double bonded compounds
(Figure 1.1).41 Taking in to account of all these similarities with the carbon, “phosphorus is often referred as a carbon copy”.42 Therefore, to tune the electrooptical properties of the conjugated organic materials, conjugated organophosphorus materials found to be ideal candidates and the present work focuses on the synthesis and studies of such materials.
1.7. Recent Developments in Conjugated Organophosphorus Materials
The conjugated organic materials like poly-phenylenevilnylenes (PPV), poly- acetylenes (PA), poly-anilinies (PA) and many other materials (Chart 1.11)43-45 are well known for their electro-optical properties and applications. The incorporation of phosphorus into these conjugated carbon backbone can change their overall electrooptical properties. N P
aniline phosphane
S P
thiophene phospholes
P
ethylene phosphaalkene
Chart 1.12. Examples of π-conjugated materials and their respective π- conjugated organophosphorus compounds.
15
Thus, phosphorus incorporated π-conjugated materials featuring P=C bonds are interesting materials to study and recently they are finding great opportunity in tuning of well known organic counter parts such as those mentioned in chart 1.12.
1.7.1. π-Conjugated Organophosphorus Polymers and Materials
Incorporation of a phosphaalkene (P=C) bond into a carbon based π-conjugated system will result in the reduction of HOMO-LUMO energy levels. In a macromolecule these energy levels often known as valence band (VB) and conduction band (CB). The difference in the energy between these two bands is known band gap energy, which actually defines the overall electro-optical properties of the materials. Since, the effect of incorporation and the resulting decrease in the band gap (Figure 1.2) will be reflected by a red shift in the UV-vis absorption spectra of the concerned materials Also, because of the smaller energy gap these materials are easily reducible by electrochemical methods.
Therefore, these materials in general will have unique electro-optical properties compared to their organic counterparts and it is possible to tune their properties.46
LUMO VB band gap) E HOMO CB
-C=C- -P=C- macromaterials
Figure 1.2. Effect of phosphorus incorporation into the conjugated –C=C- system
The lower band gap can also facilitate as a good conducting material in electrooptical devices. Hence, the conjugated organophosphorus compounds have very high importance in electrooptical material research.
16
During 2002 to 2004, Smith et al.46-49 and Vincent. et al.50 independently reported the synthesis and studies of phospha-polyphenylenevinylenes (phospha-PPV’s) (Chart 1.13).
Mes HexO Mes
Mes P P P OTMS 1.20 OH ex Mes Mes n P HexO TM S O Mes 1.19 n Mes P 1.21 OHex Mes n
phospha-PPV's
Chart 1.13. π-conjugated phospha-PPV’s featuring phosphaalkene (P=C) bonds.
Interestingly, the polymers 1.20 and 1.21 were mainly E-isomer where as 1.19 was 1:1 of
E:Z mixture. While both the polymers required bulky protecting groups implying the significance of steric stabilization to make conjugated P=C bonded materials. Recently, the π-conjugated phosphole based materials were extensively studied for their electrooptical properties (Chart 1.14).
S P S S Ph
1.22 Chart 1.14. Thioxophosphole used as OLED material.
These molecules have weak delocalization of electrons and lower HOMO-LUMO separation. The molecule 1.22 has been investigated for its OLED (organic light emitting
17 diode) properties. These classes of materials (thioxophospholes) have been used as
OLED materials (Chart 1.14).51
1.8. Proposed Research Studies.
The research was aimed at answering the questions related to synthesis and studies of low coordinate conjugated organophosphorus materials, especially about meta- terphenylphosphaalkenes and 2,6-diarylsubstituted-benzobisoxaphospholes.
1.8.1. meta-Terphenyl phosphaalkenes: Synthesis, Characterization and
Photochemical Studies.
Photochemically promoted E-Z isomerization reactions are a very important class of reactions in many chemical and biological processes. Stilbene type compounds were the best studied materials to understand this particular phenomenon.52,53 These materials have applications that are important in developing materials such as molecular switches, organic light emitting diodes (OLEDs) and nonlinear optics. Analogous photo responsive nitrogen based imines and azo compounds also attracted considerable attention in developing photoreactive materials.54 The extension of E-Z isomerization reactions in compounds featuring heavy main group element multiple bonds are not well known due to the higher reactivity and requirement of steric stabilizing groups. of light, similar to its carbon analogues.55-58
18
E-Isomer Z-Isomer
PP P h P
Mes*
2,4,6-tri-t-butyl- P P h
Chart 1.15. Photochemical isomerization of Mes*-diphosphenes and Mes*- phosphaalkenes
The first reported multiply bonded phosphorus compound Mes*P=PMes* utilized a bulky steric stabilizing Mes* (2,4,6-tri-tert-butyl) group. The diphosphene
Mes*P=PMes* and related phosphaalkene Mes*P=C(H)Ph were shown to undergo E-Z isomerization upon exposure to light (Chart 1.15).
E-Isomer Z-Isomer
hν Dmp P PP P Dmp Dmp Dmp
Dmp
hν Dmp P 2,6-di-mesitylphenyl- ?
Chart 1.16. E-Z isomerization of meta-terphenyl protected diphosphenes and phosphaalkenes.
19
In contrast, meta-terphenyl substituted diphosphene (DmpP=PDmp) showed no signs of
E-Z isomerization upon exposure of light (Chart 1.16). This led us to investigate a detailed study on the structural and photochemical properties of meta-terphenyl protected phosphaalkenes.
1.8.2. meta-Terphenyl phosphaalkenes bearing electron donating and accepting groups.
Phosphaalkenes are relatively non polar compounds in the absence of strongly polarizing groups, owing to the very close electronegativity of carbon ((C) = 2.5) and phosphorus ((P) = 2.1). However, in the presence of different functional groups across the P=C unit can lead charge polarization (Chart 1.17).
X' X' X P X P
Chart 1.17. Charge polarized meta-terphenyl phosphaalkenes
Another area that has captured much attention for alkenes, especially those that are polarized due to the simultaneous presence of both electron donating (ED) groups and electron withdrawing (EW) across a conjugated system. These systems are being examined for they can possess nonlinear optical (NLO) properties.59 In extreme cases, the presence of directly attached electron donating groups can even reverse the slight
20 polarization of the P=C bond to create inversely polarized phosphaalkenes having very different physico chemical properties. Therefore the it was of interest to set out to prepare new meta-terphenyl phosphaalkenes whereby to introduce different substituents across the ArP=C(H)Ar array and to study their structural and chemical properties. The studies of which in future might be helpful in developing new charge polarized nonlinear optical materials.
1.8.3. meta-Terphenyl phosphaalkenes to more planar and conjugated
2,6-diarylsubstituted-benzo-bis(oxaphospholes)
In spite of the successful synthesis of conjugated phosphaalkenes through the use of steric stabilizing meta-terphenyl group, these molecules have some inherent disadvantages. They are i) meta-terphenyl phosphaalkenes posses bulky steric stabilizing groups in order to protect the phosphaalkene (P=C) unit in the conjugated organic backbone. The presence of these bulky groups breaks the π-conjugation and to loses some planarity due to the steric constrains of the molecule (Chart 1.18).
P P
O
A B
Chart 1.18. Molecular structure of (A) meta-terphenyl phosphaalkene (θ ≠ 0 or
180) and an analogous (B) 2-aryl-1,3-benzoxaphosphole (θ ≈ 0 or 180).
21
ii) The second disadvantage is that their synthetic difficulty and their high reactive nature. This makes them more difficult to handle and to purify if necessary. Thus, there is a need to develop more efficient phosphorus-carbon double bonded (pπ-pπ) conjugated systems. To address these issues and to develop materials with P=C conjugated π bonds, an ideal option was to pursue the investigation of the 1,3-heterocyclic organophosphorus conjugated materials, which were structurally similar to the conjugated phosphaalkenes by having a P=C bond in the cyclic system. In this direction, 2,6-diarylsubstituted-benzo- bis(1,3-oxaphospholes) are the materials of interest in the current study (Chart 1.19).
P O Ar Ar O P
. Chart 1.19. 2,6-diarylsubstituted-benzo-bis(1,3-oxaphospholes)
22
1.9. References.
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23
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Chemistry, 1990.
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Chem. Commun. 1976, 261-2.
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1984, 3, 793-800.
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24
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Domain; Elsevier Science Ltd: Oxford, UK, 2001.
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25
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26
Chapter 2. Photochemical Isomerization of meta-Terphenyl Protected
Phosphaalkenes
2.1 Introduction
The exposure of molecules or any materials to an external energy like heat or sunlight can trigger a change in their physical and chemical properties. Among these external energies, visible light has a role in many commonly occurring biological and chemical changes.1-3 The molecular and the structural rearrangements are the common
consequences of such light exposure. One of the major underlying chemical concepts
causing such structural changes is cis-trans isomerization of unsaturated chemical bonds
upon exposure to light. These molecules can change their structures, while the light is on
to a switch on state and off to in the absence of light respectively (Scheme 2.1).
hν1 AB hν2
Scheme 2.1. Light driven photochemical transformation
This phenomenon is engineered to make molecules with interesting applications
such as data storage and molecular electronic devices. Organic and inorganic materials
exhibiting such behavior are often referred as photoactive materials. In recent years, great
interest has focused on making such materials containing conjugated carbon back bone.
The idea is to exploit the photoactivated cis-trans isomerization. Stilbene type
compounds with carbon-carbon double bonds (stilbene), nitrogen-nitrogen double bonds
(azobenzene) and carbon-nitrogen double bonds (imine) are such well exploited materials in this regard (Chart 2.1).4-6
27
Photochemical isomerization of stilbene based materials
hν Stilbene (carbon) system
EZ
(Imine) (Phosphaalkene) N P
(Diphosphene) (Azo) NN PP
Chart 2.1. Photochemical E-Z isomerization of stilbene and its main group analogues (imine, phosphaalkene, azo and diphosphene)
Stilbene based materials has found applications in molecular switches, organic light-emitting diodes (OLEDs), nonlinear optics and in many other technological applications.4,7 Similarly the isomerization reactions of both analogues imines (Ar-C=N-
Ar) and azobenzenes (Ar-N=N-Ar) have attracted considerable attention for various applications as photoresponsive materials.8,9 Analogous isomerization reactions of
28 compounds featuring main group element multiple bonds have less frequently studied because of the higher reactivity compared to their carbon-based analogues and the complications brought in by steric protecting.10 Organophosphorus compounds have
received a great deal of attention as photo active materials because of their parallel
relationship with well-established carbon compounds and their chemistry.11 The
phosphaalkene group-containing materials have shown a great promise as ligands for
transition metal complexes and, in some cases, they were used in a number of important
catalytic reactions.12-15 The orientation of the substituents about the P=C bond dictate the
coordination mode and catalytic efficacy of such ligands. Thus, the chemistry of the P=C
bond is based on the ligand type.
In particular, phosphorus analogues of stilbene, such as the supermesityl-
16-19 phosphaalkene Mes*P=C(H)Ph (Mes* = 2,4,6-t-Bu3C6H2 or 2,4,6-tri-tert-butyl) and the similar Mes* phosphaalkenes with two or more Mes*P=C(H) functional groups displayed similar light-induced isomerization.20,21The first reported multiply bonded
phosphorus compound Mes*P=PMes* 22-26 has also been shown to yield mixtures of E
and Z isomers upon irradiation, similar to its carbon analogues (Chart 2.2), and it formed
an insertion product with suitable light exposure.22
29
E-Isomer Z-Isomer
PP
P hν P
Mes*
P hν 2,4,6-tri-t-butyl- P
Chart 2.2. Photochemical isomerization of Mes*-diphosphenes and Mes*-
phosphaalkenes.12-20
Interestingly, it was noticed that the photoisomerization of meta-terphenyl
` 27,28 diphosphenes ArP=PAr (Ar = 4-Me-2,6-Mes2C6H2, Ar` = Phenyl) and DmpP=PDmp
(Dmp = 2,6-Mes2C6H3) did not occur upon irradiation (Chart 2.3). This apparent lack of
photo activity is in contrast with the rich photochemistry observed for the Mes*P=PMes*
diphosphene.
E-Isomer Z-Isomer
Dmp P hν PP P Dmp Dmp Dmp
Dmp hν Dmp P ? 2,6-di-mesitylphenyl-
Chart 2.3. Photochemical isomerization of Dmp-diphosphenes and Dmp-
phosphaalkenes
30
This observation indicates that differences in the overall shapes of the two types of sterically demanding groups and causing their photochemical properties to different. So far, no photochemical studies have been reported for phosphaalkenes bearing meta- terphenyl groups, and thus it would be of interest to determine if this feature extends to the corresponding meta-terphenyl-protected phosphaalkenes.
In order to understand the photochemical properties of the meta-terphenyl protected phosphaalkenes, a series of phosphaalkenes of the form E-ArP=C(H)Ar' (Ar =
4-X-2,6-Mes2C6H2, Ar' = 4-Y-C6H4, X or Y = Br or H) were made with an objective to
make polymeric materials, where the presence of the X and Y groups would allow the
elimination of XY equivalents via catalytic coupling reactions (Chart 2.4).
X P X, Y = H or Br Y
Chart 2.4. “Dmp” protected phosphaalkenes used for photochemical studies.
This approach facilitates the construction of new materials with nonlinear optical
properties and the synthesis of new conjugated polymers with low-coordinate phosphorus
(phosphaalkene) atoms.29 During these efforts, it was observed that the extended handling of these phosphaalkenes in room light produced the Z isomers. Herein, the results and discussions on photochemical isomerization of a previously reported phosphaalkene and three new bromine-substituted derivatives are presented and discussed.
31
2.2. Results and Discussion
Systematic investigations of the impact of para substituents to phosphaalkene and diphosphene groups have been made. Our desire to develop new phosphaalkenes for remote functionalizaton led us to adopt a key intermediate from the work of Yoshifuji and et al.28 Specifically, we were attracted to the para-bromo-substituted meta-terphenyl
4-Br-2,6-Mes2C6H2I. In their work, it was shown that one can modify the less-hindered
bromine atom position. Subsequent transformations could then introduce phosphorus into the protective pocket occupied by the iodine atom. By contrast, we needed to install low-
coordinate phosphorus into the hindered site first, and then later modify the less-hindered
para position.
Normally, iodine would be expected to undergo metal-halogen exchange faster
than bromine, thus the conventional routes to ArPCl2, involving sequential reaction with
n-BuLi and PCl3, could give the desired material. The steric coverage provided by the
mesityl group, however, might make lithium-bromine exchange more favorable.
Fortunately, the new dichloroarylphosphine Ar'PCl2 2.4 (Scheme 2.2) was successfully
isolated in a 32% yield by standard procedures for preparing these types of hindered
ArPCl2.
n-BuLi, -78 C Y I Y PCl2
PCl3
Y=H =2.1 Y=H =2.3 Y=Br=2.2 Y=Br=2.4
Scheme 2.2. Synthesis of ArPCl2 and Ar'PCl2
32
Synthesis of the three new phosphaalkenes (2.6a-2.8a) and known phosphaalkene
2.5a took advantage of our version of the phospha-Wittig reaction (Scheme 2.3).30-34 The
intermediate phospha-Wittig reagent was not isolated but was trapped in situ, with the
aldehyde in slight excess to give the desired phosphaalkene. Reactions were quantitative,
products confirmed by NMR spectroscopy, and yielded only the E-isomer, each
crystalline material being pale yellow in color.
Zn, xs PMe3 Y PCl Y P Y P 2 X THF PMe3 X CHO
"phospha-Wittig reagent" Xor Y=H,Br
Scheme 2.3. Synthesis of bromine substituted meta-terphenyl phosphaalkenes
through one-pot phospha-Wittig reaction.
Phosphaalkene X Y Yield 2.5a H H 76% 2.6a Br H 50% 2.7a H Br 75% 2.8a Br Br 45%
Table 2.1. meta-Terphenyl phosphaalkenes and synthetic yields.
The compounds (2.5a – 2.8a) were readily characterized by 31P{H} NMR shifts
that were only by a few ppm (parts per million) different from each other, including the
previously reported 2.5a (239.0 - 245.7 ppm). All of these materials display characteristic
doublets around 8.5 - 8.9 ppm in their 1H NMR spectra and having a diagnostic coupling 33 constants (JPH = 25 Hz) for the E (trans) configuration about the phosphorus-carbon
double bond.19,35 Bromine atom substitution onto either or both ends of 2.5a induces a
red shift on the UV-vis spectra. The shifts are additive, and the shift is greater when a
single substitution is present on the less-hindered phenyl unit (Table 2.2). This finding is
consistent with the presumed greater ability of this ring to undergo conjugation with the
phosphaalkene chromophore.
Phosphaalkene λmax(nm) log ε 2.5a 334 4.59 2.6a 342 4.11 2.7a 337 4.22 2.8a 345 4.49
Table 2.2. UV-Vis absorption spectral data for 2.5a – 2.8a (CHCl3).
The synthesized compounds are thermally stable at room temperature, in the
absence of air and water, but the solutions of 2.5a – 2.8a on exposure to room light showed evidence of the slow formation of significant quantities of their corresponding Z
isomers 2.5b -2.8b (Scheme 2.4). Interestingly, this feature has a special distinction from
its diphosphene analogue (DmpP=PDmp), which shows no significant isomerization or any photochemically driven reaction products after the light exposure.36
X
hν P P
X Y Y
E Z
Scheme 2.4. Photochemical isomerization of meta-terphenyl phosphaalkene
34
The E- isomer upon exposure to light, the NMR samples of the E- isomer exhibits an additional upfield signal for their 31P{H} NMR spectra and new doublets near the
1 aromatic region of 7.6 ppm in its H NMR spectra with JPH = 36 Hz, strongly suggests
that partial conversion from E isomer to the Z isomer (Table 2.3).
E-isomer Z-isomer
Phosphaalkenes 1 1 H NMR ppm 31 H NMR ppm 31 P NMR P NMR (JP-H, Hz) (JP-H, Hz)
2.5 8.44(24.8) 214.9 7.57(36.8) 234.9
2.6 8.54(24.8) 245.7 7.66(36.0) 241.4
2.7 8.65(25.2) 239.0 7.90(36.8) 229.8
2.8 8.53(24.8) 240.5 7.66(36.4) 235.4
1 31 Table 2.3. H and P{H} NMR data for E and Z phosphaalkenes (CDCl3)
Therefore, all the phosphaalkenes can be characterized by their characteristic 31P{H} and
1H NMR (Table 2.3) spectra. In addition, from the signal intensity, the percentage
isomerization can also be determined. The photochemical conversion of 2.8a was studied
by exposing to the room light for an extended period of time (3.5 days) and it was
observed to be approximately 90% conversion (Figure 2.1 – Figure 2.4) took place.
35
Before light exposure
31 Figure 2.1. P{H} NMR of 2.8a (CDCl3), before exposure to sunlight.
After light exposure
1 Figure 2.2. H NMR of 2.8a (CDCl3) after exposure to light, a mixture of 2.8a and 2.8b can be seen in the NMR.
36
Before light exposure
1 Figure 2.3. {H} NMR of 2.8a (CDCl3), before exposure to sunlight.
After light exposure
1 Figure 2.4. H NMR of 2.8a (CDCl3) after exposure to light, mixture of 2.8a and
2.8b can be seen in the NMR.
37
All of these phosphaalkenes showed similar trend and the photochemical conversions approached 84-90% using room light over an extended period of time. In order to avoid the external factors, a controlled isomerization study was performed, by placing the samples in a Rayonet UV photochemical reactor (Figure 2.5) with 350 nm UV lamps and the studying the isomerization by 1H and 31P NMR technique.
UV Lamp (350 nm)
Sample
Figure 2.5. Model pictorial representation of Rayonet UV photochemical reactor
In the photochemical reactor over a 6 h period, the compounds (2.5a – 2.8a) undergone conversion to the photostationary (pss) equilibria of 76-81% (by 1H NMR) with the
respective (2.5b - 2.8b) Z-isomers (Table 2.4).
Phosphaalkene % of E to Z conversion (350 nm) 76% 2.5 2.6 79% 2.7 81% 2.8 78%
Table 2.4. E-Z conversion data in a photochemical reactor upon exposure to
350 nm light source for the compounds 2.5a – 2.8a (CDCl3) 38
Conducting the photolysis of 2.8a in a quartz tube did not significantly change the position of the equilibrium and the conversation attained the equilibrium in 30 min
(Figure 2.6). During these studies, to explore the stability of these materials in the solid state, a solid sample of 2.5a was exposed to UV light for 6 h showed partial (30%) conversion to the 2.5b isomer. Thus, it reflects that these materials are photochemically active even in their solid state. It should be noted that in all of these experiments, no appreciable decomposition or loss of phosphaalkenes was noted. By comparison, the photoisomerization of E-Mes*P=C(H)Ph in solution using a medium-pressure mercury lamp yielded a mixture of E and Z phosphaalkenes in a 30:70 ratio
Figure 2.6. Photochemical equilibration of the phosphaalkene 2.8a -2.8b in the photochemical reactor
39
In order to understand more about the structural conformation of the Z-meta-terphenyl protected phosphaalkene, after photolysis of solution of 2.8a, pure 2.8b was isolated in a
60% yield. The prepared Z-isomer 2.8b was used for further structural characterization and photochemical properties.
2.3. UV-Vis Spectral Studies of E and Z isomers.
The UV-vis spectra of 2.8a and 2.8b are shown in figure 2.7 and the spectral data is shown in table 2.3. Upon isomerization to the Z isomer, 2.8a undergoes both a blue shift for its π-π* transition of 15 nm and a drop in intensity by a factor of 3. This is an expected result, as the cis isomer 2.8b might lose some conjugation due to the structural confinement of the cis isomer. Thus, a blue shift in the absorption spectra was observed for 2.8b and as well the decrease in its extinction co-efficient (Figure 2.7 and Table 2.5).
2.8a
2.8b 2.8b 2.8a
Figure 2.7. UV-Vis absorption spectra of 2.8a and 2.8b
40
Phosphaalkene λ (nm) log ε max 2.8a 345 4.49 2.8b 330 4.01
Table 2.5. UV-vis absorption data of 2.8a and 2.8b in CHCl3
Using the absorption data at 350 nm for 2.8a and 2.8b (ε = 30 300 and 6920 M-1 cm-1, respectively), and by using equation 1, to predict the cis/trans ratio produced with the light source in the photochemical reactor.
(2.1)
If one assumes the quantum yields for the photoisomerization reactions in both directions are equal, a cis/trans ratio of 0.23 is obtained, remarkably close to the ratio of 0.22 that is observed. Photolysis of pure 2.8b in the photochemical reactor led to equilibration to a
24:76 ratio of 2.8a/2.8b over a 6 h period. The heating a sample of pure 2.8b in toluene at
80° C for 15 h did not yield any detectable 2.8a. Therefore a high thermal barrier is thus presumed for the E/Z isomerization process for these meta-terphenyl protected phosphaalkenes.
2.4 Single Crystal Structural Analysis of E and Z isomers.
Single crystals of 2.8a and 2.8b were grown from a concentrated solution of diethyl ether at -35° C, the quality of crystals found to be good for single-crystal X-ray analysis. The results of the structural determinations confirmed the E and Z assignments of the prepared materials (Figures 2.8 – Figure 2.9). Key metrical data for these compounds are listed in table 2.6. The selected bond lengths and bond angles presented in
41 table 2.7 for the discussion. The attempts to crystallize the phosphaalkene without any substituents 2.4a found to be difficult and hence emphasis laid on the phosphaalkene
2.8a, which is a potential material for making new polymers and other interesting materials.
Figure 2.8. ORTEP diagram of 2.8a (30% probability ellipsoids)
Figure 2.9. ORTEP diagram of 2.8b (30% probability ellipsoids)
42
Compounds 2.8a 2.8b
Empirical formula C31H29Br2P C31H29Br2P Formula weight (g/mol) 592.33 592.33 Temperature (K) 100(2) 100(2) Wavelength (Å) 0.71073 0.71073 Crystal system Orthorhombic Monoclinic Space group Fdd2 P21/c Unit cell dimensions a = 25.9240(17) Å, a = 17.8482(16) Å b = 32.412(2) Å, b = 9.6996(9) Å c = 14.4521(2) Å c = 16.4619(14) Å α= 90° α= 90° β = 90° β = 111.3850(10)° γ =90° γ = 90° Volume (Å)3 11143.1(13) 2653.7(4) Z 16 4 Density calculated (Mg/m3) 1.412 1.483 Absorption Coefficient (mm-1) 2.984 3.133 F(000) 4800 1200 Crystal size (mm) 0.30 x 0.30 x 0.20 0.25 x 0.20 x 0.15 Crystal color/shape pale yellow block pale yellow block θ-range 1.84-27.50° 1.23-27.53° Limiting indices -28 < h < 33 -23 < h < 22 -41 < k < 29 -12 < k < 12 -15 < l < 16 -20 < l < 21 Reflections collected 12,813 22,059 Independent reflections 5898 (Rint = 0.0324) 6000 (Rint = 0.0452) Refinement method full-matrix full-matrix least-squares on F2 least-squares on F2 Data/restraint/parameters 5384/0/307 4757/0/307 GOF on F2 0.990 1.028 Final R indices R1 = 0.0326 R1 = 0.0395 [ I > 2σ(I)] wR2 = 0.0745 wR2 = 0.1001 R indices (all data) R1 = 0.0366 R1 = 0.0550 wR2 = 0.0758 wR2 = 0.1076
Table 2.6. X-ray crystallography data for the compounds 2.8a and 2.8b
The P=C(H)C6H4Br array in each compound lies between the cleft formed by the two
outer mesityl rings. They are not in optimized orientations for -conjugation with the
central benzene ring of the terphenyl units.
43
Br Br
C1 P P1 C1 P P1 C25 C25 C26 C26
Br Br
2.8a 2.8b Bond Length (Å) P1-C25 1.683(3) 1.666(4) P1-C1 1.842(3) 1.838(3) C25-C26 1.453(4) 1.465(6)
Bond Angles (°) C25-P1-C1 101.6(1) 107.3(1) C26-C25-P1 124.5(2) 136.3(2)
Table 2.7. Selected bond lengths (Å) and bond angles (°) of 2.8a and 2.8b
The P=C bond length shortens by 0.016 Å on going from 2.8a (1.682(3) Å) to
2.8b (1.666(3) Å). Both of these values fall into the normal range of such values for a
P=C bond37,38 and they are slightly longer than the P=C bond length of 1.634(3)Å
reported for another meta-terphenyl phosphaalkene, E-ArP=C(H)Ph (Ar = 2,6-(2,6-
38 Cl2C6H3)2C6H3). A larger C(25)-P(1)-C(1) bond angle (from 101.6(1) to 107.3(1))
appears upon conversion of the E isomer to its Z form. Likewise, the bond angle about
C(25) increases by 11.8 (from 124.5(2) to 136.3(2)). This latter sizable increase may reflect some steric clashes between the bromophenyl ring and the mesityl rings. This notion is reinforced by noting that the Cipso carbons of both mesityl rings lie
approximately 0.21-0.22 Å above the plane of the central benzene ring of the terphenyl
44 unit of 2.8b, while the Cipso atoms of the mesityl rings in 2.8a are in the plane of the
central benzene ring of the terphenyl unit. Structurally characterized E- and Z-
Mes*P=C(H)Ph both display essentially identical P=C bond lengths. In fact, the distances reported for the structures of E-Mes*P=C(H)Ph (1.669-1.674 Å) bracket the value of
1.672 Å determined for the Z isomer. All of the atoms of the P=C(H)Ph unit lie in a single plane that is perpendicular to the Mes* aryl ring. The P=C(H)C6H4Br arrays in
compounds 2.8a and 2.8b however, appear to be less confined and CCP=C torsional angles are about 63°. For both Z-Mes*P=C(H)Ph and 2.8b, the P=C-C bond angles have
opened up by 13.7° and 11.8°, respectively, compared to their E isomers. A smaller
increase in the C-P-C bond angles of 5.3°-5.5° is noted in going from each pair of E to Z
isomers.
2.5. Variable Temperature NMR Studies.
In addition to the single crystal structure data, the evidence of steric clashes and
resultant hindered rotations in the phosphaalkene 2.8b can be observed from its 1H NMR spectrum. A first glimpse of the 1H NMR spectra (Figure 2.10) for the compound 2.8b
reveals that the presence of a dynamic process in the alkyl region. The ortho-methyl
resonances of 2.8a are observed as a singlet, indicating rapid rotation about the P(1)-C(1)
bond on the NMR time scale. The same protons for 2.8b resonate as a broad signal at 2.0
ppm in CDCl3. The para-methyl resonances of 2.8b, however, appear as a sharp
resonance at 2.26 ppm. Variable-temperature 1H NMR studies of 2.8b over the range of
-40° to 55° C reveal temperature-dependent behavior for the ortho-methyl signals (Figure
2.11). At the lowest temperature, two sharp signals are can be discerned, and at the
highest temperature, a single resonance is resolved.
45
Br b
P a
Br
1 Figure 2.10. H NMR (400MHz) of isolated 2.8b in CDCl3
Figure 2.11. Variable temperature (experimental) 1H NMR spectra of 2.8b (Z-isomer) in
CDCl3.( small percentage of 2.8a).
46
Figure 2.12. Variable temperature (simulated by WINDNMR) NMR spectra of
2.8b (Z-isomer) in CDCl3.
These variable temperature data were fit with a two site-exchange models
(WINDNMR) (Figure 2.12). The rate constants thus obtained from the WINDMR were
used in the Eyring equation (Equation 2.2) to calculate the thermodynamic parameters.
kH k S (2.2) ln ln B TRThR
A plot of ln k/T vs 1/T (Table 2.8) (Figure 2.13) gave a straight line from which the H and S were calculated to be 13.8 kcal mol-1K-1 and 1.27 kcal mol-1K-1 respectively.
∆H‡ = 6962.9 x 8.313Jmol-1K-1 = 57.89 kJmol-1K-1 = 13.8 kcalmol-1K-1
∆S‡ = 5.313 Jmol-1K-1 = 1.27 calmol-1K-1
47
Temp (°C) Temp (° K ) Rate (k) 1/T k/T ln k/T -40 233.16 1.3 4.29 x10-03 0.005576 -5.1893 -35 238.16 1.9 4.20 x10-03 0.00798 -4.8313 -25 248.16 5 4.03 x10-03 0.0201 -3.9046 -15 258.16 23.9 3.87 x10-03 0.092578 -2.3797 -5 268.16 57 3.73 x10-03 0.2126 -1.5483 5 278.16 123.5 3.60 x10-03 0.444 -0.8119 15 288.16 287.5 3.47 x10-03 0.9977 -0.0023 25 298.16 841.5 3.35 x10-03 2.8223 1.03755 35 308.16 2121.8 3.25 x10-03 6.8854 1.9294 45 318.16 4847.2 3.14 x10-03 15.2351 2.7236 55 328.16 8313.8 3.05 x10-03 25.3346 3.2322
Table 2.8. Variable temperature NMR data and the rate constant obtained from a
two site exchange model in WINDNMR.39
Figure 2.13. Eyring and Arrhenius plots for calculating the thermodynamic
parameters for the hindered rotation
The activation barrier (Ea) for the hindered rotation is also calculated by using the
Arrhenius equation (Equation 2.3) from a plot of ln k vs 1/T (Figure 2.13) which is found
to be 14.4 kcal mol-1K-1
(2.3) E lnkA ln a RT
48
-1 -1 -1 -1 Activation energy : Ea = 60.17 kJ mol K = 14.4 kcal mol K
A parallel set of coalescence phenomenon were observed for the aromatic CH resonances
of the mesityl groups, but these data were obscured by other overlapping signals and were not fit (but the estimated activation parameters were similar). These observations are all consistent with hindered rotation about the P-CAr bond of 2.8b. As noted above, there are several features of the crystal structure suggesting steric pressures within 2.8b.
No temperature-dependent NMR spectra were reported for the related pair of
phosphaalkenes E- and Z-Mes*P=C(H)Ph. The ortho-tert-butyl groups of the Mes* group
are reported as single resonances.
2.6. Conclusions.
Three new meta-terphenyl-protected phosphaalkenes 2.6-2.8 have been prepared
in addition to a previously reported phosphaalkene 2.5. All of these materials are found to be photochemically active and they have been shown to undergo photoisomerization upon exposure to light from E to Z isomers. The photochemical conversion was observed to occur even in solid state but it is very very minimal compared to that in a solution phase. Both the E and Z isomers of one of these new materials 2.8 have been fully characterized. The Z-isomer of this compound has shown interesting features in the 1H
NMR, due the hindered phosphorus-aryl bond rotation in the meta-terphenyl unit.
Variable-temperature 1H NMR studies performed to calculate and analyze the thermodynamic parameter for the hindered rotation. The E and Z isomers of this
compound were completely characterized by single crystal X-ray crystallography and
UV-vis absorption studies.
49
2.7. Experimental Section.
General Procedures. All manipulations were carried out using modified Schlenk techniques or in a MBraun Labmaster 130 drybox under N2. Solvents were purified by
distillation from sodium-benzophenone ketyl under a N2 atmosphere before use. The
precursors DmpPCl2, 4-Br-2,6-Mes2C6H2I and the compound DmpP=C(H)Ph (2.5a) were
prepared as previously described. The UV-vis absorption spectra were recorded using a
Cary500 spectrophotometer. All photochemical reactions were performed in CDCl3 at
room temperature in a Rayonet photochemical reactor loaded with 350 nm UV source
lamps. Routine NMR data were recorded on a Varian Inova spectrometer operating at
400 MHz and 161.8 MHz for the 1H and 31P spectra, respectively. 31P NMR data are
1 referenced to external 85% H3PO4, while the H NMR data are referenced to residual
proton solvent signals of CDCl3. VT NMR studies were performed using a 600 MHz
Varian Inova NMR instrument.
4-Br-2,6-Mes2C6H2PCl2 (2.4). In a 100 mL dry round-bottom flask, a solution of 2.00 g
of 4-Br-2,6-Mes2C6H2I (3.85 mmol) dissolved in 20 mL of THF was chilled to -78 C;
1.77 mL of 2.5 M solution of n-BuLi in hexanes (4.43 mmol) was added to this solution.
Then the mixture was allowed to stir at -78 C. After 2 h, 1.68 mL of PCl3 (19.3 mmol)
was added rapidly, and the reaction mixture was then allowed to warm to room
temperature. The solvent was removed under vacuum, and the crude product was placed
into a drybox where it was slurried in 30 mL of acetonitrile; then the mixture was filtered, and the product was washed with 5 mL of hexanes. The solid was dried under vacuum and then dissolved in diethyl ether; then the solution was filtered through Celite. The solvent was removed under vacuum, and the solid was then recrystallized from ether at -
50
1 35 °C to yield 0.610 g of 4-Br-2,6-Mes2C6H2PCl2 (32%). H NMR (CDCl3): 7.29 (d, 2H,
31 1 JPH = 2.4 Hz), 6.91 (d, 4H, JHH = 0.8 Hz), 2.32 (s, 6H), 2.03 (s, 12H). P{ H} NMR
13 (CDCl3): 159.0. CNMR (CDCl3): 148.5, 148.2, 138.2, 136.4, 134.7, 133.4, 128.1,
127.8, 21.4, 21.2. mp: 200-202 °C. Anal. Calcd for C24H24PBrCl2: C, 58.53; H, 4.92.
Found: C, 58.36; H, 4.70.
E-[2,6-Mes2C6H3P=C(H)C6H4Br] (2.6a). A mixture of 0.10 g of DmpPCl2 (0.24 mmol),
0.020 g of Zn dust (0.31 mmol), 0.050 g of p-bromobenzaldehyde (0.270 mmol), and
1.44 mL of a 1.00 M solution of PMe3 in toluene (1.44 mmol) in 20 mL of THF was
allowed to stir overnight in a 50 mL round-bottom flask. The reaction mixture was then
filtered, and the solvent was removed under vacuum. The remaining solid was rinsed
with acetonitrile and then extracted into hexanes. The product obtained after removal of
the hexanes under vacuum was recrystallized from a concentrated ether solution at -35 C
1 to yield 0.060 g of yellow 2.6a (50%). H NMR (CDCl3): 8.54 (d, 1H, JPH = 24.8 Hz),
7.46 (t, JHH = 7.6 Hz, 1H), 7.22 (d, JHH = 8.4 Hz, 2H), 7.10 (d, JHH = 7.6 Hz, 2H), 6.97
13 (m, 2H), 6.87 (s, 4H), 2.27(s, 6H), 2.05 (s, 12H). CNMR (CDCl3): 178.2 (d, JPC = 35.1
Hz), 140.6 (d, JPC = 39.0 Hz), 144.8 (d, JPC = 3.0 Hz), 139.0 (d, JPC = 14.5 Hz), 138.2 (s),
137.1 (s), 135.6 (s), 131.4 (s), 129.6 (s), 128.6 (s), 128.2 (s), 127.2 (s), 121.8 (d, JPC = 8.0
31 1 Hz), 21.1 (s), 20.9 (d, JPC = 2.0 Hz) P{ H} NMR (CDCl3): 245.7. UV-vis (CHCl3): λmax
-1 -1 = 342 nm (ε = 12600 M cm ). mp: 132-134 °C. Anal. Calcd for C31H30PBr: C, 72.52;
H, 5.89. Found: C, 72.34; H, 5.82.
E-[4-Br-2,6-Mes2C6H2P=C(H)Ph](2.7a). A mixture of 0.15 g of 4-Br-2,6-
Mes2C6H2PCl2 (0.30 mmol), 0.020 g of Zn dust (0.31 mmol), 0.32 mL of benzaldehyde
(0.32 mmol), and 0.14 mL of neat PMe3 (1.74 mmol) in 20 mL of THF was allowed to
51 stir for 6 h in a 50 mL round-bottom flask. The reaction mixture was then filtered, and the solvent was removed under vacuum. The remaining solid was rinsed with acetonitrile and then extracted into hexanes. The hexanes was removed under vacuum, and the pale yellow product was then recrystallized from a concentrated hexane solution at -35 C to
1 yield 0.12 g of yellow crystalline 2.7a (75%). H NMR (CDCl3): 8.65 (d, JPH = 25.2 Hz,
1H), 7.27 (s, 2H), 7.10 (s, 5H), 6.85 (s, 4H), 2.25 (s, 6H), 2.06 (s, 12H). 13C{1H} NMR
(CDCl3): 180.5 (d, JPC = 35.3 Hz), 146.8 (d, JPC = 9.1 Hz), 140.4 (d, JPC = 41.3 Hz),
139.9 (d, JPC = 15.1 Hz), 137.4 (s), 137.3 (s), 136.6 (d, JPC = 3.0 Hz), 135.4 (s), 132.1 (s),
131.3 (s), 128.3 (s), 125.9 (d, JPC = 21.1 Hz), 123.5 (s), 21.1 (s), 20.9 (d, JPC = 2.0 Hz).
31 1 P{ H} NMR(CDCl3): 239.0. mp: 212-215 °C. UV-vis (CHCl3): λmax = 337 nm (ε = 16
600 M-1cm-1).
E-[4-Br-2,6-Mes2C6H2P=C(H)C6H4Br](2.8a). A mixture of 1.0 g of 4-Br-2,6-
Mes2C6H2PCl2 (2.0 mmol), 0.14 g of Zn (2.1 mmol), 0.39 g of p-bromobenzaldehyde (2.1
mmol), and 12.1 mL of a 1.0 M solution of PMe3 in toluene (12.1 mmol) in 20 mL of
THF was allowed to stir overnight in a 100 mL round-bottom flask. The reaction mixture
was filtered and the solvent was removed under vacuum. The solid was rinsed with
acetonitrile and then extracted in hexanes. The hexanes were removed under vacuum.
The yellow product was recrystallized from a concentrated ether solution at -35 °C to
1 give 0.51 g of yellow crystalline 2.8a (45%). H NMR (CDCl3): 8.53 (d, JPH = 24.8 Hz,
1H), 7.35 (s, 2H), 7.22 (d, JHH = 8.4 Hz, 2H), 6.98-6.95 (m, 2H), 6.86 (s, 4H), 2.26 (s,
31 1 13 1 6H), 2.05 (s, 12H). P{ H} NMR (CDCl3): 240.5. C{ H} NMR (CDCl3): 178.7 (d, JPC
= 35.4 Hz), 146.7 (d, JPC = 8.5 Hz), 140.0 (d, JPC = 39.7 Hz), 138.8 (d, JPC = 14.8 Hz),
137.5 (s), 136.9 (s), 135.4 (s), 131.5 (d, JPC = 2.5 Hz), 131.4 (s), 128.3 (s), 127.2 (d, JPC =
52
21.5 Hz), 123.7 (s), 122.1 (d, JPC = 8.5 Hz), 21.1 (s), 20.9 (d, JPC = 2.1 Hz). mp: 192-
-1 -1 194 °C. UV-vis (CHCl3): λmax = 345 nm (ε = 30,900 M cm ). Anal. Calcd for
C31H29PBr2: C, 62.86; H, 4.93. Found: C, 62.92; H, 4.70.
Z-[4-Br-2,6-Mes2C6H2P=C(H)C6H4Br](2.8b). The isomerization of 2.8a was conducted
using a Rayonet photochemical reactor loaded with 350 nm UV source lamps. In a Pyrex
NMR tube, 0.025 g of 4a was dissolved in 0.7 mL of CDCl3. The sample was exposed to
the UV light for 6 h and then placed into the glovebox. After the solvent was removed
under vacuum, the product was crystallized in a concentrated ethyl ether solution at -35
1 °C to yield 0.016 g of 2.8b (60%). H NMR (CDCl3): 7.66 (d, JPH = 36.4 Hz, 1H), 7.34
(s, 2H), 7.23 (d, JHH = 10 Hz, 2H), 6.84 (m, 2H), 6.82 (m, broad, 4H), 2.26 (s, 6H), 2.02
31 1 3 (s, broad, 12H). P{ H} NMR (CDCl ): 235.4. mp: 176-178 °C. UV-vis (CHCl3): λmax =
330 nm ( ε = 10 200 M-1 cm-1).
Photolysis of 2.5a-2.7a. Photolysis of a 2.5a - 2.7a in CDCl3 led to a mixture of 2.5a -
31 1 2.7a and 2.5b - 2.7b, as described in the text. For 2.5b, P{ H} NMR (CDCl3): 234.9.
1 31 1 partial H NMR (CDCl3): 7.57 (d, JPH = 36.8 Hz, 1H). For 2.6b, P{ H} NMR (CDCl3):
1 31 1 241.4. partial H NMR (CDCl3): 7.66 (d, JPH = 36.0 Hz, 1H). For 2.7b, P{ H} NMR
1 (CDCl3): 229.8. partial H NMR (CDCl3): 7.90 (d, JPH = 36.8 Hz, 1H).
53
2.8. References.
(1) Duerr, H.; Bouas-Laurent, H. Photochromism: Molecules and Systems: Revised
Edition, 2003.
(2) Waldeck, D. H. Chem. Rev. 1991, 91, 415-36.
(3) Momotake, A.; Arai, T. J. Photochem. Photobiol., C. 2004, 5, 1-25.
(4) Meier, H. Angew. Chem., Int. Ed. 1992, 31, 1399-1420.
(5) Tamai, N.; Miyasaka, H. Chem. Rev. 2000, 100, 1875-1890.
(6) Waldeck, D. H. 1991, 91, 415-436.
(7) Feringa, B. L.; van Delden, R. A.; Koumura, N.; Geertsema, E. M. Chem. Rev.
2000, 100, 1789-1816.
(8) Nagele, T.; Hoche, R.; Zinth, W.; Wachtveitl, J. Chem. Phys. Lett. 1997, 272,
489-495.
(9) Ikeda, T.; Tsutsumi, O. Science. 1995, 268, 1873-1875.
(10) Power, P. P. Chem. Rev. 1999, 99, 3463-3503.
(11) Dillon, K. B.; Mathey, F.; Nixon, J. F. Phosphorus: The Carbon Copy: From
Organophosphorus to Phospha-organic Chemistry, 1998.
(12) Gajare, A. S.; Jensen, R. S.; Toyota, K.; Yoshifuji, M.; Ozawa, F. Synlett. 2005,
144-148.
(13) Gajare, A. S.; Toyota, K.; Yoshifuji, M.; Ozawa, F. Chem. Commun. (Cambridge,
U. K.). 2004, 1994-1995.
(14) Boubekeur, L.; Ricard, L.; Le Floch, P.; Mezailles, N. Organometallics. 2005, 24,
3856-3863.
(15) Grobe, J.; Le Van, D. J. Fluorine Chem. 2004, 125, 801-821.
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(16) Yoshifuji, M.; Toyota, K.; Inamoto, N. Tetrahedron Lett. 1985, 26, 1727-30.
(17) Yoshifuji, M.; Toyota, K.; Inamoto, N.; Hirotsu, K.; Higuchi, T. Tetrahedron Lett.
1985, 26, 6443-6.
(18) Yoshifuji, M.; Toyota, K.; Matsuda, I.; Niitsu, T.; Inamoto, N.; Hirotsu, K.;
Higuchi, T. Tetrahedron. 1988, 44, 1363-7.
(19) Appel, R.; Menzel, J.; Knoch, F.; Volz, P. Z. Anorg. Allg. Chem. 1986, 534, 100-
8.
(20) Jouaiti, A.; Geoffroy, M.; Terron, G.; Bernardinelli, G. J. Am. Chem. Soc. 1995,
117, 2251-8.
(21) Kawanami, H.; Toyota, K.; Yoshifuji, M. J. Organomet. Chem. 1997, 535, 1-5.
(22) Yoshifuji, M.; Sato, T.; Inamoto, N. Chem. Lett. 1988, 1735-8.
(23) Yoshifuji, M.; Sato, T.; Inamoto, N. Bull. Chem. Soc. Jpn. 1989, 62, 2394-5.
(24) Jutzi, P.; Meyer, U. J. Organomet. Chem. 1987, 333, C18-C20.
(25) Yoshifuji, M.; Abe, M.; Toyota, K.; Goto, K.; Inamoto, N. Bull. Chem. Soc. Jpn.
1993, 66, 1572-5.
(26) Komen, C. M. D.; de Kanter, F. J. J.; Goede, S. J.; Bickelhaupt, F. J. Chem. Soc.,
Perkin Trans. 2. 1993, 807-12.
(27) Tsuji, K.; Sasaki, S.; Yoshifuji, M. Heteroat. Chem. 1998, 9, 607-613.
(28) Tsuji, K.; Sasaki, S.; Yoshifuji, M. Tetrahedron Lett. 1999, 40, 3203-3206.
(29) Wright, V. A.; Gates, D. P. Angew. Chem., Int. Ed. 2002, 41, 2389-2392.
(30) Shah, S.; Protasiewicz, J. D. Chem. Commun. (Cambridge). 1998, 1585-1586.
(31) Smith, R. C.; Chen, X.; Protasiewicz, J. D. Inorg. Chem. 2003, 42, 5468-5470.
(32) Smith, R. C.; Protasiewicz, J. D. Eur. J. Inorg. Chem. 2004, 998-1006.
55
(33) Smith, R. C.; Protasiewicz, J. D. J. Am. Chem. Soc. 2004, 126, 2268-2269.
(34) Urnezius, E.; Protasiewicz, J. D. Main Group Chem. 1996, 1, 369-372.
(35) Appel, R.; Knoll, F. Adv. Inorg. Chem. 1989, 33, 259-361.
(36) Peng, H.-L., Ph.D Thesis, Case Western Reserve University, 2007.
(37) Smeets, W. J. J.; Spek, A. L.; Van der Does, T.; Bickelhaupt, F. Acta Crystallogr.,
Sect. C: Cryst. Struct. Commun. 1987, C43, 1838-9.
(38) Van der Knaap, T. A.; Klebach, T. C.; Visser, F.; Bickelhaupt, F.; Ros, P.;
Baerends, E. J.; Stam, C. H.; Konijn, M. Tetrahedron. 1984, 40, 765-76.
(39) Reich, H. J. WinDNMR: Dynamic NMR Spectra for Windows J. Chem. Educ.
Software 3D2
56
Chapter 3. meta-Terphenyl Phosphaalkenes Bearing Electron Donating and
Accepting Groups
3.1. Introduction
Phosphaalkenes (RP=CR'2) represent interesting main group analogues of alkenes
1-15 (R2C=CR'2). As such, in many of the areas for which alkenes are either being used or studied for technological applications; parallel opportunities often exist for phosphaalkenes. For example, recently a lot of interest has been focused on the development of conjugated polymers featuring phosphaalkene functionalities along the main chain.5,16-20 Another area that has captured much attention for alkenes, especially those that are polarized due to the simultaneous presence of both electron donating (ED) groups and electron withdrawing (EW) across a conjugated system. These systems are currently being examined for they can possess nonlinear optical (NLO) properties.21-27
Phosphaalkenes are relatively non polar in the absence of strongly polarizing groups, owing to the similar electronegativity of carbon ((C) = 2.5) and phosphorus ((P) =
2.1)).5,28-30 The slight difference, however, could lead to some contributions from
resonance structures 3.1.A and 3.1.C (Chart 3.1).
P P P
3.1.A 3.1.B 3.1.C
Chart 3.1. Resonance structures for phosphaalkene
57
The effect of different functional groups have reported on phosphaalkenes in which one group or the other across the phosphaalkene (P=C) unit. Phosphaalkenes being reactive, they require steric stabilizing bulky groups to prevent from the oligomerization. Various types of bulky groups were known and Bickelhaupt and co-workers performed a systematic analysis of the impact of varying remote para-X'-substituents on the supermesityl (Mes*) substituted phosphaalkene E-Mes*P=C(H)C6H4-4-X' (Mes* = 2,4,6-
t 31 Bu3C6H2, Chart 3.2, 3.2.A).
P X P X 3.2.A 3.2.B
Chart 3.2. Effects of substituent groups on the structures and properties.
From their studies it can be concluded that, the Mes*P=CH group acts as a weak electron
donor on substituted benzene rings, behaving much like a simple alkene. In another
pioneering study, Yoshifuji and colleagues undertook the much greater synthetic
challenge of re-engineering the bulky Mes* so as to allow variation of the para-X-
t 32 substituent on the bulky aryl group (4-X-2,6- BuC6H2, 3.2.B). For a series of
fluorenylidene(aryl)phosphines, the UV-vis spectroscopic data suggested that the X
group has the greatest impact on the energetics of the lone pair on the phosphorus, and
little impact on the energies of the or * orbitals.33 These results can be rationalized by
the fact the very sterically demanding Mes* type ligands and in its chemical cousin as
shown in 3.2.B, the ortho-tert-butyl groups causes this phenyl ring to be nearly 58
orthogonal to the plane best suited for conjugation to the P=C -bond. Thus the impact of remote substituents on the P=C -bonds in systems such as 3.2.B are expected to be diminished compared to those modified as in 3.2.A. Yoshifuji and co-workers have also employed such functionalized ligands to introduce diarylamino groups into remote position of terphenyl ligands for the purpose of preparing multi-redox active diphosphenes (Chart 3.3).
Mes Mes Tip Mes tBu Tip Ar2N P Ar2N P Ar2N P t P NAr2 P Bu P NAr2 Mes Mes Tip Mes tBu Tip
3.3.A 3.3.A 3.3.C
Mes : mesityl, Ar : p-anisole, Tip : 2,4,6-triisopropylphenyl
Chart 3.3. Diarylamino substituted diphosphenes
In some cases, the presence of directly attached electron donating groups can even reverse the slight polarization of the P=C bond to create inversely polarized phosphaalkenes having very different chemistries (Chart 3.4). 34
RP RP NMe NMe2 2
R:Mes,Ph,tBu Chart 3.4. A selected example for an inversely polarized phosphaalkene
It should also be mentioned that Power and coworkers have shown that in distannyne
analogues (Chart 3.5), a change from X = H to X = SiMe3 can have dramatic effects on
59
Sn-Sn bond lengths, C-Sn-Sn bond angles, and even the orientation of the aryl rings with respect to the Ar-Sn-Sn-Ar torsional angles.35
X Sn Sn X'
Chart 3.5. Effect of substituents on a distannyne compound
Therefore, all these studies indicate that the substituents can have a significant role in defining the overall properties of the materials. Hence, the goal of this studies was to prepare a set of meta-terphenyl protected phosphaalkenes with varying degrees of polarization across the central P=C unit (Chart 3.6) and to characterize their properties.
D P D P A A
3.6.A 3.6.B
Chart 3.6. Charge polarization in phosphaalkenes
For the present study, analogues of the bulky 2,6-Mes2C6H3 group (Chart 3.7) have been utilized.
X P X'
Chart 3.7. meta-terphenyl protected phosphaalkenes 60
These terphenyl types of bulky ligands are more readily accommodate nearly coplanar configurations better suited for -conjugation across the whole system than Mes*-type ligands, as they are more open and present less steric pressure on the attached phosphorus atom. It should be noted that the compounds of the type E-2,6-Mes2C6H2P=C(H)C6H4-4-
36 X' (Chart 3.7, X = H; X' = H, Cl, NO2, OMe, NMe2) and as well as E-4-Br-2,6-
37 Mes2C6H2P=C(H)C6H4-4-Br (Chart 3.7, X = X' = Br) are reported earlier. The latter material was isolated in the Z-form of this phosphaalkene as the product of photoisomerization.
3.2. Results and Discussion
3.2.1. Synthesis of phosphaalkenes and functionalized meta-terphenyls
Yoshifuji and coworkers demonstrated the utility of dihalo-substituted 2,6-
38,39 dimesitylphenyls such as 4-I-2,6-Mes2C6H2I and 4-I-2,6-Tip2C6H2I. Our approach to the present terphenyls started with 4-Br-2,6-Mes2C6H2Br (3.1), this can be made by
following few minor modifications from the earlier reported procedure.38 This material
can then be converted to 4-I-2,6-Mes2C6H2Br (3.2) as shown in scheme 3.1.
Br Mes nBuLi, -78°C, THF Mes MesMgBr, Ref lux I Br I Br Br 2 I Br THF, Br2 Br Mes Mes 3.1 3.2
Scheme 3.1. Synthesis of 4-I-2,6-Mes2C6H2Br (3.2)
61
Compound 3.2 thus allowed the synthesis of the terphenyl bearing Me2N (3.5a) and MeO
(3.5b) substituents, as detailed in schemes 3.2 and 3.3. A set of conventional transformations based on related syntheses were used with good success.40-42
Mes O Mes Mes CH3CONH2,CuI HCl, THF H I Br N Br N Br trans-1,2-Diaminocyclohexane H Reflux, 15 hr H Mes Mes K2CO 3, Toluene, Reflux Mes 3.3 3.4 3.2
Mes Mes ° HCHO, NaBH4, n-BuLi, -78 C 3.4 N Br N PCl2 H2SO4,0° C,THF THF, PCI Mes 3 Mes
3.5a 3.6a
Scheme 3.2. Synthesis of dimethylamino subsitituted aryldichlorophosphine 3.6a
Mes CuI, KF-Al2O3 Mes Mes o-Phenanthroline n-BuLi, -78° C I Br O Br O PCl2 CH OH-THF THF, PCI 3 Mes 3 Mes Mes Reflux 3.2 3.5b 3.6b
Scheme 3.3. Synthesis of methoxy substituted aryldichlorophosphine 3.6b
From 3.5a and 3.5b the corresponding dichloroarylphosphines 4-Me2N-2,6-
Mes2C6H2PCl2 (3.6a) and 4-CH3O-2,6-Mes2C6H2PCl2 (3.6b) can be accessed in modest
to good yields (30% and 50% respectively). The reduced yields reflect, in part, the
greater difficulty encountered in the purification of these materials. The 31P NMR shifts
62
for 3.6a and 3.6b located at 163.7 and 160.7 ppm are close to the value of 160.1 ppm
36,43,44 reported for the unsubstituted analogue 2,6-Mes2C6H3PCl2.
While several routes have been reported for the synthesis of
phosphaalkenes5,28,30,32,45-55, we have found that for the synthesis of terphenyl bearing
phosphaalkenes the use of "phospha-Wittig" reagents of the form 2,6-Mes2C6H3P=PMe3 to be particularly convenient.13,37,56-60 These reagents need not be isolated and they can be
easily generated by the reduction of ArPCl2 by Zn dust in the presence of PMe3.
Subsequent addition of aldehydes affords the corresponding phosphaalkenes in good yields. Therefore, as shown in Scheme 3.4, the phosphaalkenes 3.7-3.15 were prepared by using commercially available aldehydes and (E)-4-(4-nitro-styryl)-benzaldehyde.
Zn, PMe3 X' O 3.7 - 3.13 X PCl2 X P X' Toluene -Me3P=O 3.14 - 3.15
Scheme 3.4. Synthetic scheme followed for making phosphaalkenes with different substituent groups.
Examination of the 31P NMR shift data for the compounds 3.8-3.15 shows that the presence of electron withdrawing groups X' (note 3.8-3.9) leads to significant downfield shifts (ca 23-25 ppm) relative to the unsubstituted phosphaalkene 3.7 (Table 3.1). In comparison, the 13C NMR data shows a small change in their chemical shift values for
the phosphaalkene carbon upon changing the substituents.
63
13C NMR(δ) 31P NMR (δ) X X’ Yield (CDCl ) CDCl 3 3 for P=C(H)Ar 3.7 H H 76% 241.9(240.9*) 180.2 (JPC = 35.0) 3.8 H NO2 43% 268.4(265.6*) 176.5 (JPC = 36.4) 3.9 H CN 46% 263.5 177.0 (JPC = 35.8) 3.10 MeO CN 67% 262.6 176.3 (JPC = 35.2) 3.11 MeO NO2 35% 267.0 176.2 (JPC = 36.4) 3.12 MeO H 47% 240.7 180.1 (JPC = 35.2) 3.13 Me2N H 40% 242.5 178.4 (JPC = 35.3) 3.14 H NO2 75% 245.1 178.9 (JPC = 35.6) 3.15 MeO NO 71% 245.7 178.6 (J = 35.6) 2 PC (*C6D6) Table 3.1. Synthesized phosphaalkenes and NMR data (31P and 13C).
Whereas, a much smaller impact for the presence of X groups is noted (note 3.12-3.13)
on 31P NMR shifts (ca 2 ppm) relative to the unsubstituted phosphaalkene 3.7, or on the
compounds that have X' groups. In accord with the discussion in the introduction, these
findings can be rationalized by the tendency of the much larger aryl group to rotate so as to minimize unfavorable steric interactions, as described in Scheme 3.5. Thus, the ability of the remote substituents X to have electronic communication to the P=C functional
group via π-conjugation through the aromatic rings are inhibited, relative to the X' units
on the less hindered aryl ring.
Mes Mes Mes X P X P X P X' Mes X' X' Mes Mes
Scheme 3.5. Relieving steric strains by rotating away from the planarity 64
3.2.2. UV-vis Absorption Data.
The phosphaalkenes 3.7-3.15 vary in color from pale yellow to reddish orange. The
intensity of the color is notably higher for 3.14 and 3.15, likely owing to the effect of extended conjugation compared to the other materials. The UV-vis absorption spectra of the phosphaalkenes 3.7-3.12 afford an opportunity to assess the relative impact of X and
X' substituents on these phosphaalkenes. In the absorption spectra, there are intense
bands for the π to π* transition around 340-370 nm, considering the broad shape of the
absorption spectra there might be some weak n-π* transitions possible. A detailed
computational study may answer this feature.
Figure 3.1. UV-vis absorption spectra of synthesized meta-terphenyl
phosphaalkenes in CHCl3.
65
λmax (shoulder) nm log ε 3.7 331 (340) 4.23 3.8 377 4.21 3.9 352 4.32 3.10 351 4.28 3.11 376 (380) 4.08 3.12 332 (355) 4.27 3.14 402 4.65 3.15 409 4.66
Table 3.2. UV-vis absorption data for the synthesized meta-terphenyl phosphaalkenes in CHCl3 (*insufficient amount of 3.13 available for analysis)
The figure 3.1 shows that the presence of an electron withdrawing groups on the
less hindered phenyl ring possess greater influence on the π to π* energy transition, thus
leading to a greater red shift in the absorption spectra. Whereas, the introduction of an
electron donating methoxy group 3.12 in comparison to 3.7 did not show significant
influence on the π to π* transition. This indicates that the presence of a methoxy (donor)
group attached to the bulky meta-terphenyl unit is not having sufficient influence on the π
to π* electronic transition and this can be due to the weak π-delocalization of π electrons
from this ligand to the rest of the molecule in the phosphaalkene. Since, if it has induced
greater delocalization it is expected to exhibit red shift in the absorption spectra of 3.12.
This is further confirmed when we compare the absorption spectra for the compounds 3.7
(331nm) with 3.12 (332nm) and 3.9 (352nm) with 3.10 (351nm). Similar trend is even
observed in compounds with the extended conjugation 3.14 (402nm) and 3.15 (409 nm).
Whereas, the presence of –NO2 group in 3.8 and –CN group in 3.9 at the less hindered phenyl ring of the phosphaalkenes induced a comparable red shift in the absorption spectra of the phosphaalkene, by ~46 nm with -NO2 and ~21 nm with -CN groups 66
respectively. Interestingly, there is no great shift in the phosphorus NMR for these two
compounds.
3.2.3. X-ray Crystallographic Studies
X-ray quality crystals of 3.8, 3.9, 3.10 and 3.12 were obtained from their respective concentrated solutions of ethyl ether at -35 °C. The ORTEP representations
and results of these structure determinations are shown in figures 3.2-3.5 and the
corresponding crystallographic data were given in tables 3.3 and 3.4 respectively.
Figure 3.2. Single crystal X-ray crystallographic structures of E-2,6-
Mes2C6H3P=C(H)C6H4-4-NO2 (3.8) shown at the 50% thermal ellipsoid level.
67
Figure 3.3. Single crystal X-ray crystallographic structures of E-2,6-
Mes2C6H3P=C(H)C6H4-4-CN (3.9) shown at the 50% thermal ellipsoid level.
Figure 3.4. Single crystal X-ray crystallographic structures of E-4-MeO-2,6-
Mes2C6H2P=C(H)C6H4-4-CN (3.10) shown at the 50% thermal ellipsoid level. 68
Figure 3.5. Single crystal X-ray crystallographic structures of E-4-MeO-2,6-
Mes2C6H2P=C(H)C6H5 (3.12) shown at the 50% thermal ellipsoid level.
69
Compound 3.8 3.9 3.10 3.12
Empirical formula C31H30NO2P C32H30NP C33H32NOP C32H33OP Formula weight (g/mol) 479.53 459.54 489.57 464.55 Temperature (K) 100(2) 273(2) 100(2) 100(2) Wavelength (Å) 0.71073 0.71073 0.71073 0.71073 Crystal system Monoclinic Monoclinic Triclinic Monoclinic Space group P2(1)/c P2(1)/n P-1 P2(1)/c Unit cell dimensions (Å) a 23.2380(6) 8.8864(3) 12.408(4) 13.1255(16) b 8.2716(2) 13.3717(5) 13.525(5) 8.3261(10) c 13.8440(4) 21.7122(7) 19.559(9) 24.814(3) α 90° 90° 100.417(7)° 90° β 101.539(2)° 93.848(2)° 101.084(7)° 101.8120(10)° γ 90° 90° 114.306(4)° 90° Volume(Å3) 2607.25(12) 2574.16(15) 2808.8(18) 2654.3(6) Z 4 4 4 4 Calculated 1.222 1.186 1.158 1.162 density (Mg/m3) Absorption-coeff (mm-1) 0.133 0.127 0.123 0.125 F(000) 1016 976 1040 992 Crystal size (mm) 0.26x0.12x0.07 0.32x0.22x0.22 0.18x0.11x0.10 0.35x0.28x0.20 θ range 0.89-26.00° 1.79-23.14° 1.11-26.00° 1.59-27.50° -28<=h<=28 -9<=h<=9 -15<=h<=15 -17<=h<=17 Limiting indices -10<=k<=9 -14<=k<=14 -16<=k<=16 -10<=k<=10 -15<=l<=17 -23<=l<=23 -24<=l<=24 -32<=l<=32 Reflections-collected 18803 31244 30129 30125 unique 5124 3637 11001 6043
R(int) 0.0504 0.0543 0.1048 0.0252 Completeness to θ 26.00°, 99% 23.14°, 99.9% 26.00°, 99.6% 27.50°, 99.3% Absorption correction Multiscan Multiscan Multisan Multiscan 0.9754 & 0.9575 Max & min transmission 0.991 & 0.981 0.9726 & 0.9605 0.9878 & 0.9783
Full-matrix least Full-matrix least Full-matrix least Full-matrix least Refinement method squares on F2 squares on F2 squares on F2 squares on F2 Data 5124 3637 11001 6043 Restraints 0 0 0 0 Parameters 322 313 663 362 Goodness-of-fit on F2 1.049 1.093 1.093 1.025 Final R indices[I>2σ(I)] R1=0.0768 R1=0.0599 R1=0.0634 R1=0.0427 wR2=0.1449 wR2=0.1317 wR2=0.1048 wR2=0.1136 R indices (all data) R1=0.0504 R1=0.0766 R1=0.1625 R1=0.0491 wR2=0.1234 wR2=0.1442 wR2=0.1434 wR2=0.1196
Table 3.3. Crystallographic data for the compounds 3.8, 3.9, 3.10 and 3.12.
70
P=C Bond Length C-P-C Bond α a α b (Å) Angles (°) 1 2
3.8 1.657(2) 105.5(1) 39.3° 19.3° 3.9 1.604(4) 105.9 (2) 46.5° 9.8° 1.655(4) 104.0(2) 66.3° 11.4° 3.10c 1.649(4) 103.9 (2) 81.2° 3.6° 3.12 1.672(1) 103.3(7) 50.8° 18.3° aangle between the P-phenyl ring and C-P=C-C plane bangle between planes C(H)-phenyl ring and C-P=C-C plane cdata are for 2 unique molecules in the unit cell
Table 3.4. Selected structural data for structures 3.8, 3.9, 3.10 and 3.12.
All four structures are somewhat similar, in that they feature comparable C-P-C bond angles raging from 103.3-105.9. The shorter P=C bond distance for the structure of 3.9 is at this time, however, is suspect, for we recently uncovered a temperature dependent disorder of the phosphorus atoms in related meta-terphenyl diphosphenes, ArP=PAr, that can result in anomalously short PP distances for data sets collected at room temperature.
The other P=C bond lengths vary from 1.649(4) to 1.672(1)Å. The P=C bond lengths vary from 1.649(4) to 1.672(1) Å. If the primary impact on the P=C bond lengths was controlled by resonance contributions as shown in chart 3.6, then one might expect the greatest bond lengths to be observed for compound 3.10 having both electron donating
and withdrawing groups. These resonance structures, however, require that the
participatory phenyl rings and the P=C unit all be coplanar to achieve maximal
conjugation. Examination of the four structures shows that these geometries are clearly
not realized, at least in the solid state. The angles α1 of the plane of the C-P=C-C atoms
to those of each attached phenyl ring can be measured and compared (Table 3.4). For
each molecule, α1 is much greater than α2, owing to the much larger attached phenyl ring.
The greater the α1 angle, the less the substituents can influence the P=C unit through - 71
conjugation. In the solid state, the crystal structure data suggests that the compound 3.10
displays the maximum perturbation from a maximally conjugated conformation (Figure
3.6). In solution, however, these materials face same steric profile about P=C unit, i.e. all
face similar degree of rotation about P-Ar and C(H)-Ar bonds, and thus comparisons are
easier to make for addressing the impact of substituents on the physical properties.
Figure 3.6. Substituent effects and the crystal structure of conjugated phosphaalkenes. 3.2.4. Electrochemical Studies
The UV-vis spectroscopy can provide information on differences between ground
state and excited state energies, electrochemical methods can provide insights to energies
for oxidation and reduction of molecules, and thus yield experimental information on
HOMO and LUMO energies. Phosphorus-carbon double bonds are weaker than carbon-
carbon double bonds, and thus the and * orbitals of the P=C unit lie at higher and
lower energies, respectively, than for corresponding C=C containing materials. This fact
is evidenced by the UV-visible data discussed above. The drop in energy of the *
orbitals of phosphaalkenes makes them susceptible to reduction by either chemical or
electrochemical means. The radical anions that are generated can display varying
degrees of stability, and cyclic voltammetry experiments can show reversible
electrochemistry for these reduction/reoxidation waves. The electrochemical redox 72
properties of phosphaalkenes were first reported by Schoeller et al in 1991,61 in which the phosphaalkene showed an irreversible redox process in the cyclic voltammogram. Later investigations, revealed that redox processes can be quasi reversible, depending on the nature of groups bonded to the phosphorus-carbon double bond.62,63 The present electrochemical investigations can thus be used to shed light onto the impact of remote substituents on the properties of phosphaalkenes.
Four representative phosphaalkenes 3.7, 3.9, 3.10and 3.12 were examined by cyclic voltammetry. The scans are displayed in figures 3.7-3.10, and the specific potential data is summarized in table 3.5. Each experiment was conducted in THF with [n-
Bu4N][BF4] as the electrolyte, and in the presence of ferrocene as a reference (the left- most wave in each scan). Potentials are thus corrected for known potential of ferrocene vs SCE.
Figure 3.7. Cyclic voltammogram of 3.7, 0.001M E-[2,6-
Mes2C6H3P=C(H)C6H5]/0.001M ferrocene in 0.1M [n-Bu4N][BF4] in THF with 0.1 V/s scan rate 73
Figure 3.8. Cyclic voltammogram of 3.9, 0.001M E-[2,6-
Mes2C6H3P=C(H)C6H4-CN]/0.001M ferrocene in 0.1M [n-Bu4N][BF4] in THF with 0.1
V/s scan rate, an overlay of the second redox potential shown in dotted lines.
Figure 3.9. Cyclic voltammogram of 3.10, 0.001M E-[4-CH3O-2,6-
Mes2C6H2P=C(H)C6H4-CN]/0.001M ferrocene in 0.1M [n-Bu4N][BF4] in THF with 0.1
V/s scan rate, an overlay of the second redox potential shown in dotted lines. 74
1.5x10-5
1.0x10-5
5.0x10-6
0.0
-5.0x10-6
-5
Current (A) Current -1.0x10 Fc/Fc+ -1.5x10-5
-2.0x10-5
-2.5x10-5
1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 Potential vs. SCE (V)
Figure 3.10. Cyclic voltammogram of 3.12, 0.001M/0.001M ferrocene in 0.1M
[n-Bu4N][BF4] in THF with 0.1 V/s scan rate.
The compound 3.7, as the parent species was studied and the scan was presented
in figure 3.7. This phosphaalkene as shown exhibited a single reversible redox process
around -1.9 V vs SCE. Also, as anticipated, each phosphaalkene displayed an apparently
reversible reduction process. The CN substituent in 3.9 and 3.10 shifts this potential
positive by about 400 mV from that seen for 3.7. The addition of the MeO group on
going from 3.7 to 3.12 and from 3.9 to 3.10, however, makes the reduction more difficult
by a much smaller amount (80 and 40 mV). These results can be ascribed to the same
geometrical factors already discussed above. Similarly, the diphosphenes investigated
bearing the diarylamino substituted terphenyl ligands did not display significantly shifted
reductions in their cyclic voltammograms.
75
The cyano substituted species 3.9 and 3.10 both show evidence of a second
accessible reductive process around -2.1 V vs SCE. This reduction is definely not
reversible on the timescale of the experiment, and is near the reduction potential for
stilbene.64 One possible sequence for the 2 step reduction of 3.9 and 3.10 is presented in
Scheme 3.6.
Mes Mes Mes e e X P X P X P e e Mes C N Mes C N Mes C N
Scheme 3.6. Redox process in cyano substituted phosphaalkene
Ec Ea E1/2 Ec 3.7 -2.02 -1.74 -1.88 ---
3.9 -1.64 -1.34 -1.49 -2.20 3.10 -1.66 -1.40 -1.53 -2.23 3.12 -2.10 -1.83 -1.96 ---
+ solvent: THF; supporting electrolyte: 0.1M [n-Bu4N][BF4]; reference: Fc/Fc ; scan rate: 0.1 V/s
Table 3.5. Half wave potentials for the selected phosphaalkenes.
The results of these electrochemical investigations reinforce the importance of the X'
groups over of the X groups in modulating the properties of this class of phosphaalkenes.
76
3.2.5. Nonlinear Optical Studies.
Since alkenes that are polarized by the presence of donor and acceptor groups are often studies for nonlinear optical properties, phosphaalkenes 3.7, 3.10, and 3.11 were briefly examined by HRS (hyper Rayleigh scattering) experiments in attempts to measure the “β” component. The HRS method is an alternative technique to the commonly used
EFISH (electric field induced second harmonic generation) technique. This approach has the advantage of measuring the “β” component without exposure to the external field and much simpler than EFISH. The main disadvantage of HRS, is that the scattered signals will be weak in intensity. Samples of phosphaalkenes in chloroform (ca 500 μM) in quartz cuvettes excited with 1064 nm wavelength, however, showed no frequency doubling. Compounds 3.10 and 3.11 may not be polarized sufficiently by the donor and acceptor groups, or be reactive in other ways to the high power laser irradiation.
3.3. Conclusions
meta-terphenylphosphaalkenes with different groups (MeO, CN, NO2) were
made. The prepared materials were completely characterized by UV-vis absorption
spectroscopy, single crystal structures and electrochemical studies. Four of these new
compounds were examined by single crystal X-ray diffraction methods and the solid state
structures were determined. As the polarization across the P=C unit increased by the
presence of electron donating and electron withdrawing substituents, reaching a
maximum with compound 3.12, the overall geometry of the phosphaalkenes were less suited for -conjugation of the directly attached aryl rings to the central P=C unit.
Analysis of the accumulated physical data, in particular of the UV-visible absorption
spectra, show that para-substituents on the less hindered phenyl rings about the P=C 77
group resulted in more pronounced effects on the physical properties of the set of phosphaalkenes. These results were clearly evident from the spectroscopic studies data.
Overall, the additive impact of the two para-substituents X and X' are not as effective as found in related alkenes, hence the use of stilbene-like phosphaalkenes in applications demanding a high degree of polarization, such as NLO materials, seems limited.
However, considering the scarcity of NLO active phosphaalkenes, these studies provided the intial step to investigate the effect of substituents on meta-terphenyl phosphaalkenes.
3.4. EXPERIMENTAL SECTION
General Procedures. All manipulations and synthesis were performed in an MBraun
Labmaster nitrogen glove box or using standard vacuum line techniques. UV-vis absorption data were recorded on a Cary 500 UV-Vis spectrometer. Chloroform was degassed with N2. Tetrahydrofuran, diethyl ether and hexanes were dried by distilling
over metallic sodium and benzophenone. Acetonitrile was dried over calcium hydride
and distilled under nitrogen. Melting points were recorded using a Mel-Temp instrument.
NMR spectra were recorded on a 400 MHz Varian-Inova Instrument using CDCl3 as
31 1 solvent. P{ H} NMR spectra were referenced to 85% H3PO4 as an external standard.
The compounds 2,6-Mes2C6H3I, 2,6-Mes2C6H3PCl2, and 2,6-Mes2C6H3P=C(H)C6H5
(3.7), 2,6-Mes2C6H3P=C(H)C6H4-4-NO2 (3.8) were prepared by reported
procedures.36,37,65 For several new compounds, submission of samples for elemental
analytical data did not return satisfactory detail, despite the fact that such materials
displayed 1H and 31P NMR spectra that suggested >95% purity. This fact, especially for
aryldichlorophosphines (ArPCl2), is likely due to sensitivity to air and water
78
Cyclic voltammetry experiments. Cyclic voltammetry experiments were performed using a CH Instrument (CHI630C) workstation in a glove box under nitrogen atmosphere. The supporting electrolyte, tetrabutylammonium tetrafluoroborate (Fluka) was recrystallized four times using 1:3 concentrated solutions of ethyl acetate and diethyl ether. The electrolyte was then dried thoroughly under vacuum at 100 - 120 °C and stored in the drybox. Ferrocene was purified by sublimation. A glassy carbon working electrode was polished with 0.05 micron alumina and thoroughly cleaned and dried before use. A silver wire was utilized as a quasi-reference electrode and a platinum wire as the counter electrode. All scans were performed at a scan rate of 0.1 V/s with a
potential window of approximately -3 to +1.5 V versus saturated calomel electrode
(SCE).
66 4-Br-2,6-Mes2C6H2Br (3.1). In a 500 mL flask, 9.20 g (378 mmol) of Mg turnings was
taken and it was activated by stirring in hot conditions in the presence of N2 atmosphere
for about 3 h. Later, the heating was stopped and allowed to attain room temperature. To
this activated Mg, 47.4 g (239 mmol) of bromomesitylene (Sigma-Aldrich) in 200 mL of
THF was added slowly through metal cannulae. The reaction was exothermic, so the
excess heat was controlled using a water bath. The resulting Grignard reagent was stirred for 6 h at room temperature. In a separate 3 necked flask, the above Grignard solution
was transferred using metal cannulae in N2 atmosphere and then allowed to reflux. To the
refluxingl Grignard solution, 31.4 g (71.3 mmol) of 2,4,6-tribromoiodobenzene in 150 mL of THF was added through the metal cannulae and allowed to reflux for 15 h. The refluxed solution was brought back to room temperature and in the presence of an ice bath, 26.2 g (164 mmol) bromine was slowly added and allowed to stir at room 79
temperature for another 2 h. The resulting mixture was quenched with 5% aqueous
Na2SO3 (2 x 150 mL) and then extracted with diethyl ether (2 x 200 mL). The organic layer was extracted and dried over Na2SO4. Removal of solvent by rotary evaporation
gave a dark brown slurry, to this n-pentane in small amounts (15 mL) was added and left
overnight at -6 °C. A pale brown solid was settled at the bottom of the flask. This on
filtering under vacuum and followed by washings with 10 mL of n-pentane gave 20.2 g
1 (30.0 %) of 3.1 as a pale brown solid. H NMR (CDCl3): δ 7.28 (s, 2H), 6.95 (s, 4H), 2.34
13 1 (s, 6H), 2.01 (s, 12H). C{ H} NMR (CDCl3): δ 144.9, 137.8, 137.6, 135.7, 132.2,
128.4, 125.5, 121.7, 21.5, 20.4. mp: 205-8 °C. Anal. Calcd for C24H24Br2 (472.26): C,
61.04; H, 5.12. Found: C, 59.84; H, 4.82.
4-I-2,6-Mes2C6H2Br (3.2). To a solution of 2.16 g (4.58 mmol) of 3.1 in 100 mL of
anhydrous THF at -78 °C under nitrogen atmosphere, 2.10 mL (5.57 mmol) of n-BuLi
(2.5M hexanes, Aldrich) was slowly added. The resulting reaction mixture continued to stir at -78 °C for 2 h. To this mixture, 2.30 g (9.16 mmol) of solid iodine was added all at
once and allowed to attain room temperature by stirring under nitrogen atmosphere for
another 1h. Excess iodine was then quenched with 5% aqueous solution of Na2SO3 (3 x
100 mL). The organic layer was extracted into diethyl ether (2 x 100mL) and washed
with (2 x 100 mL) water and brine (saturated) respectively. The organic layer was
separated and dried over anhydrous Na2SO4. Removal of volatiles under vacuum yielded
1 3.2 as a colorless solid (1.62 g, 68.0 %). H NMR (CDCl3): δ 7.46 (s, 2H), 6.94 (s, 4H),
13 1 2.33 (s, 6H), 2.01 (s, 12H). C{ H} NMR (CDCl3): δ 144.9, 137.9, 137.6, 137.2, 135.5,
128.2, 126.5, 92.9, 21.2, 20.2. mp: 216-8 °C.
80
4-CH3O-2,6-Mes2C6H2Br (3.5b). In 100 mL of anhydrous THF, 5.00 g (9.60 mmol) of
3.2, 0.48 g (2.4 mmol) of ortho-phenanthroline, 0.18 g (0.96 mmol) of cuprous iodide,
67 and 7.60 g (48.2 mmol) of KF/Al2O3 (37.0 %) was dissolved. To this stirred solution,
250 mL of methanol was added and the resulting reaction mixture was allowed to reflux
for 48 h. The mixture was cooled to room temperature and extracted into
dichloromethane (2 x 150 mL). The organic layer was separated and washed with water
(2 x 100 mL) and then with saturated brine (2 x 100 mL). The organic layer was
separated and dried over anhydrous Na2SO4. The volatiles were removed under vacuum
to give a solid material; this is purified by column chromatography using neutral silica
gel with hexanes-dichloromethane (95-5) as the eluent. Compound 3.5b was thus
1 isolated as a colorless powder (3.12 g, 70.0 %). H NMR (CDCl3): δ 6.95 (s, 4H), 6.69
13 1 (s, 2H), 3.77 (s, 3H), 2.34 (s, 6H), 2.03 (s, 12H). C{ H} NMR (CDCl3): 151.3, 143.7,
138.8, 137.4, 135.8, 128.4, 116.8, 114.9, 55.7, 21.5, 20.4. mp: 117-120 °C. Anal. Calcd
for C25H27OBr (423.39): C, 70.92; H, 6.43. Found: C, 70.95; H, 6.49.
4-CH3O-2,6-Mes2C6H2PCl2 (3.6b). To a solution of 0.50 g (1.2 mmol) of 3.5b in 50 mL of anhydrous THF at -78 °C under nitrogen atmosphere, 0.70 mL (1.5 mmol) of n-
BuLi (2.5 M, hexanes, Sigma-Aldrich) was slowly added. The reaction mixture was stirred at -78 °C for 2.5 h. To this mixture was then added 0.50 mL (5.9 mmol) of PCl3
(Sigma-Aldrich) all at once, and then the mixture was allowed to attain room temperature. The solvent and excess PCl3 was removed in vacuo from the now orange
colored solution to give a pale orange colored sticky solid. The material was dissolved in
(2 x 10 mL) hexanes, filtered through celite, followed by evaporation of the hexanes gave
a sticky material. The procedure repeated two more times. Dissolution of the material in 81
hexanes, followed by addition of a few drops of acetonitrile, resulted in the precipitation of 3.6b as a white solid, which could be collected by filtering through a glass frit. After
1 drying, 3.6b was isolated as a colorless solid (0.31 g, 50 %). H NMR (CDCl3): δ 6.92 (s,
4H), 6.64 (s, 1H), 6.63 (s, 1H), 3.82 (s, 3H), 2.34 (s, 6H), 2.06 (s, 12H). 13C{1H} NMR
(CDCl3): 163.0, 149.2 (d, JCP = 50.2 Hz), 137.9, 136.7 (d, JCP = 2.8 Hz), 136.3 (d, JCP =
7.6 Hz), 128.2, 126.0 (d, JCP = 70.1 Hz), 116.1 (d, JCP = 2.1 Hz), 55.7, 21.5, 21.4.
31 1 P{ H} NMR (CDCl3): δ 160.7. mp: 122-4°C. Anal. Calcd for C25H27OPCl2 (445.37):
C, 67.42; H, 6.11. Found: C, 68.19; H, 6.59.
4-(CH3CONH)-2,6-Mes2C6H2Br (3.3). To a solution of 5.00 g (9.63 mmol) of 3.2 in
100 mL of THF in a 250 mL round bottom flask, 0.37 g (1.9 mmol) of cuprous iodide,
3.80 mL (3.85 mmol) of trans-1,2-diaminocyclohexane, 0.68 g (12 mmol) of acetamide,
and 2.66 g (19.3 mmol) of K2CO3 was added. The reaction progress was monitored by
NMR spectroscopic analysis of reaction aliquots. The reaction mixture was thus refluxed
for 48 h. The mixture was cooled to room temperature and extracted with hyl ether (2 x
150 mL). The organic layer was washed with water (2 x 100 mL) and finally with brine
(2 x 100 mL). The organic layer was separated and dried over anhydrous Na2SO4.
Removal of the volatiles under vacuum yielded a brown colored material, which on purification by column chromatography using neutral silica gel with hexanes-ethyl acetate (60-40) as eluent gave 2.12 g of 3.3 (49.0 %) as a pale brown powder. 1H NMR
(CDCl3): δ 7.32 (s, 2H), 7.10 (s, 1H), 6.94 (s, 4H), 2.33 (s, 6H), 2.17 (s, 3H), 2.01 (s,
13 1 12H). C{ H} NMR (CDCl3): δ 168.2, 143.3, 138.2, 137.7, 137.2, 135.5, 128.1, 120.5,
120.1, 24.7, 21.2, 20.2. mp: 276-8 °C. Anal. Calcd for C26H28ONBr (450.42): C, 69.33;
H, 6.27; N, 3.11. Found: C, 69.03; H, 6.25; N, 2.90. 82
4-(H2N)-2,6-Mes2C6H2Br (3.4). To a solution of 0.50 g (1.1 mmol) of 3.3 in 50 mL of
THF was added 50mL of 1N HCl solution. The resulting mixture was refluxed for 20 h,
after which time 1H NMR analysis of a reaction aliquot indicated that the disappearance
of the amide protons of 3.3. The reaction mixture was cooled to room temperature, and
2N NaOH was added slowly until the reaction mixture became slightly basic. The product was then extracted using CHCl3 (2 x 100 mL). Removal of volatiles under
1 vacuum gave 0.42 g (92 %) of 3.4 as a pale brown colored solid H NMR (CDCl3): δ 6.93
13 1 (s, 4H), 6.47 (s, 2H), 3.70 (s, 2H), 2.32 (s, 6H), 2.04 (s, 12H). C{ H} NMR (CDCl3): δ
145.9, 143.3, 138.8, 136.9, 135.6, 127.9, 115.9, 114.1, 21.2, 20.1. mp: 214-6°C. Anal.
Calcd for C24H26NBr (408.38): C, 70.59; H, 6.42; N, 3.43. Found: C, 69.22; H, 5.89; N,
3.19.
4-((CH3)2N)-2,6-Mes2C6H2Br (3.5a). In a 100 mL round bottomed flask, 5.00 g (12.2
mmol) of 3.4 and 12.2 g (320 mmol) of NaBH4 was dissolved in 30 mL of THF. This slurry was added to another 100 mL flask containing 30.0 mL (380 mmol) of HCHO (37
% wt/wt, Fischer), 10 mL H2SO4 and 10 mL of THF at 0 °C over a period of 10 minutes.
The reaction mixture was allowed to attain room temperature and was stirred for 5 h.
The reaction mixture was chilled in an ice bath and water was added to quench the
reaction. The reaction mixture was extracted with (2 x 100 mL) CHCl3., and the organic
phase separated. The volatiles were removed under vacuum, and the resulting material was further purified by column chromatography using neutral silica gel with hexanes- ethyl (80-20) acetate as eluent. Compound 3.5a was thus isolated as a pale brown solid
1 (4.50 g, 85.0 %). H NMR (CDCl3): δ 6.95 (s, 4H), 6.47 (s, 2H), 2.91 (s, 6H), 2.34 (s,
13 1 6H), 2.06 (s, 12H). C{ H} NMR (CDCl3): δ 149.9, 142.7, 139.5, 136.9, 135.8, 127.9, 83
113.0, 111.9, 40.6, 21.2, 20.2. mp: 173-5 °C. Anal. Calcd for C26H30NBr (436.43): C,
71.55; H, 6.93; N, 3.21. Found: C, 71.49; H, 7.02; N, 3.17.
4-((CH3)2N)-2,6-Mes2C6H2PCl2 (3.6a). To a solution of 0.50 g (1.2 mmol) of 3.5a in 40 mL of THF at -78 °C was slowly added 0.70 mL (1.7 mmol) of n-BuLi (2.5 M in hexanes, Sigma-Aldrich). The mixture was stirred at -78 °C for 2.5 h. To this mixture
0.30 mL (3.4 mmol) of PCl3 was added at once, and the solution was allowed to attain room temperature. The solvent and excess PCl3 removed in vacuo from the now
yellowish-orange colored solution. The resulting material was then dissolved in hexanes
and the solution was filtered through a bed of celite. Removal of hexanes under vacuum
1 gave 0.16 g (30 %) of 3.6a as a colorless solid. H NMR (CDCl3): δ 6.93 (s, 4H), 6.35 (d,
13 1 JHH = 3.2Hz, 2H), 3.00 (s, 6H), 2.34 (s, 6H), 2.10 (s, 12H). C{ H} NMR (CDCl3): δ
31 1 152.9, 148.4 (d, JPC = 31 Hz), 137.6, 137.3, 136.9, 128.0, 113.1, 40.2, 21.5, 21.4. P{ H}
NMR (CDCl3): δ 163.7. mp: 52-4 °C.
(E)-4-(4-nitrostyryl)-benzaldehyde.68 In a 100 mL flask, 0.57 g (3.1 mmol) of 4-
bromobenzaldehyde (Sigma-Aldrich), 0.46 g (3.1 mmol) 4-nitrostyrene, 0.020 g (0.096
mmol, 3 %) of Pd(OAc)2, 0.27 g (0.64 mmol, 20 %) of tetraphenylphosphoniumbromide
and 1.31 g (16.0 mmol) of sodium acetate was taken. The mixture was kept under
vacuum for 1 h. To this mixture 20 mL of anhydrous DMF was added. The resulting
solution refluxed under nitrogen atmosphere for 24 h. Later, the reaction mixture brought
back to the room temperature and quenched with addition of water (20 mL). The
resulting mixture filtered under vacuum, this gave a crude yellow solid. The crude
material was purified by column chromatography with neutral silica and ethylacetate-
hexanes (35-65) as eluent. This gave 0.41 g (53 %) of pure (E)-4-(4-nitrostyryl)- 84
1 benzaldehyde as yellow solid. H NMR (CDCl3): δ 10.02 (s, 1H), 8.25 (d, JHH = 9.2 Hz,
13 1 2H), 7.91 (d, JHH = 8.8 Hz, 2H), 7.69 (t, JHH = 8.8 Hz, 4H), 7.29 (s, 2H). C{ H} NMR
(CDCl3): δ 191.5, 147.3, 142.9, 142.1, 136.2, 131.8, 130.3, 129.6, 127.5, 127.4, 124.3. mp: 63-5 °C.
36,69,70 E-2,6-Mes2C6H3P=C(H)C6H4-4-NO2 (3.8) To a 50 mL round bottom flask, 0.50 g
(1.2 mmol) of 2,6-Mes2C6H3PCl2, 0.080 g (1.3 mmol) of Zn dust and 7.20 mL (7.20
mmol) of PMe3 (1.00 M in Toluene, Sigma-Aldrich) were added and the resulting
mixture stirred for about 3h. To this mixture 0.18 g (1.2 mmol) of 4-nitrobenzaldehyde
was added and continued to stir for another 2h for completion of the reaction. The solvent
was removed under vacuum, leaving a dark red colored solid. The solid was extracted
into hexanes and filtered through celite. Removal of the hexanes under vacuum left a
yellow colored solid. The yellow solid was dissolved in diethyl ether and recrystallized at
-35°C. Removal of ether gave 0.25 g (43 %) of 3.8 as a pale yellow solid. 1H NMR
(CDCl3): δ 8.55 (d, JHH = 24.8 Hz, 1H), 7.95 (d, JHH = 8.9 Hz), 7.50 (t, JHH = 7.6 Hz, 1H),
7.20 (d, JHH = 8.9 Hz, 2H), 7.13 (d, JHH = 7.6 Hz, 2H), 6.88 (s, 4 H), 2.26 (s, 6H), 2.04 (s,
13 1 12H). C{ H} NMR (CDCl3): δ 176.5 (d, JPC = 36. 4 Hz), 147.0 (s), 146.3 (d, JPC = 15.4
Hz), 144.9 (d, JPC = 8.5 Hz), 138.0 (d, JPC = 3.0 Hz), 137.5 (s), 135.8 (s), 130.3 (s), 129.2
(s), 128.9 (s), 128.5 (s), 126.2 (d, JPC = 21.3 Hz), 124.0 (d, JPC = 1.7 Hz), 21.3 (s), 21.1
31 1 (s). P{ H} NMR (CDCl3): δ 268.5 ppm. λmax = 377 nm , log ε = 4.21. mp: 132-6 °C.
E-2,6-Mes2C6H3P=C(H)C6H4-4-CN (3.9). To a 50 mL round bottom flask, a stir bar,
0.40 g (0.90 mmol) of 2,6-Mes2C6H3PCl2, 0.06 g (0.9 mmol) of Zn dust was added. To
this mixture was added 5.40 mL (5.40 mmol) of PMe3 (1.00 M in toluene) and the mixture stirred for about 3 h. To this mixture 0.12 g (0.90 mmol) of 4- 85
cyanobenzaldehyde was added and allowed to stir for another 2 h for the completion of the reaction. The solvent was removed under vacuum and the product was extracted into hexanes, followed by filteration through celite. Removal of hexanes under vacuum gave the crude product. The product was purified by recrystallising from a concentrated solution of diethyl ether at -35 ˚C. Removal of ether gave 0.44 g (67.0 %) of 3.9 as a pale
1 yellow solid. H NMR (CDCl3): δ 8.55 (d, JPH = 24.8 Hz, 1H), 7.49 (t, JHH = 7.6 Hz, 1H),
7.36 (d, JHH = 8.3 Hz, 2H), 7.16 (d, JHH = 8.3 Hz, 2H), 7.13 (d, JHH = 7.6 Hz, 2H), 6.88
13 1 (s, 4H), 2.27 (s, 6H), 2.05 (s, 12H). C{ H} NMR (CDCl3): δ 177.0 (d, JPC = 35.8 Hz),
144.7 (d, JPC = 8.2 Hz), 144.1 (d, JPC = 15.3 Hz), 140.2 (s), 137.9 (d, JPC = 3.1 Hz), 137.2
(s), 135.5 (s), 132.1 (d, JPC = 2.2 Hz), 130.0 (s), 128.6 (s), 128.2 (s), 126.0 (d, JPC = 21.4
31 1 Hz), 119.0 (d, JPC = 2.6 Hz), 110.7 (d, JPC = 7.4 Hz), 21.1 (s), 20.9 (s). P{ H} NMR
(CDCl3): δ 263.5 ppm. λmax = 352 nm, log ε = 4.32. mp: 98-100 °C.
E-4-(CH3O)-2,6-Mes2C6H2P=C(H)C6H4-4-CN (3.10). To a 50 mL RB flask, a stir bar,
0.40 g (0.90 mmol) of 3.6b, 0.06 g (0.9 mmol) of Zn dust were added. To this mixture
was added 5.40 mL (5.40 mmol) of PMe3 (1.00 M in toluene), and the resulting mixture
stirred for about 3 h. To this mixture 0.12 g (0.90 mmol) of 4-cyanobenzaldehyde was
added, and the reaction was stirred for 2 h for the completion of the reaction. The solvent
was removed under vacuum, and the product extracted into hexanes. The hexanes
solution was filtered through the celite. The solvent was removed under vacuum and the
product was extracted again into hexanes, followed by filteration through celite. Removal of volatiles under vacuum provided 0.44 g (67 %) of 3.10 as a yellow colored solid. 1H
NMR (CDCl3): δ 8.42 (d, JHH = 24.4 Hz, 1H), 7.35 (d, JHH = 8.4 Hz, 1H), 7.13 (d, JHH =
8.4 Hz, 2H), 6.88 (s, 4H), 6.69 (s, 2H), 3.82 (s, 3H), 2.27 (s, 6H), 2.07 (s, 12H). 13C{1H} 86
NMR (CDCl3): δ 176.3 (d, JPC = 35.2 Hz), 160.6 (s), 146.1 (d, JPC = 9.1 Hz), 137.6 (s),
136.9 (s), 135.6 (d, JPC = 6.0 Hz), 135.4 (s), 135.1 (s), 131.6 (s), 127.8 (s), 125.5 (d, JPC =
20.8 Hz), 118.7 (s), 113.9 (s), 110.1 (s), 54.9 (s), 20.7 (s), 20.4 (s). 31P{1H} NMR
(CDCl3): δ 262.6 ppm. λmax = 351 nm, log ε = 4.28. mp:108-110 °C.
E-4-(CH3O)-2,6-Mes2C6H2P=C(H)C6H4-4-NO2 (3.11). To a clean 50 mL RB flask, a
stir bar, 0.50 g (1.1 mmol) of 6b, 0.080 g (1.2 mmol) of Zn dust was added. To this
mixture 6.70 mL (6.70 mmol) of PMe3 (1.00 M in toluene) was added, and the resulting
mixture stirred for about 3 h. To this mixture 0.17 g (1.1 mmol) of 4-nitrobenzaldehyde
was added and the reaction mixture was continued to stir for another 10 minutes. The
reaction mixture was filtered through celite and the solvent was removed under vacuum,
leaving a dark red residue. This solid was extracted with 15 mL of hexanes, and the
solution was filtered through celite. The volatiles were removed under vacuum to provide
1 0.33 g (56 %) of 3.11 as a dark yellow solid. H NMR (CDCl3) : δ 8.43 (d, JPH = 24.4
Hz, 1H), 7.92 (d, JHH = 8.4 Hz, 2H), 7.18 (d, JHH = 8.4 Hz, 2H), 6.88 (s, 4H), 3.83 (s, 3H),
13 1 2.27 (s, 6H), 2.07 (s, 12H). C{ H} NMR (CDCl3): δ 176.2 (d, JPC = 36.4 Hz), 161.3 (s),
146.7 (d, JPC = 9.5 Hz), 137.6 (s), 136.7 (s), 135.8 (s), 128.4 (s), 128.2 (s), 126.1 (d, JPC =
21.3 Hz), 124.0 (s), 114.6 (s), 113.8 (s), 113.2 (s), 55.6 (s), 21.3 (s), 21.1 (s). 31P{1H}
NMR (CDCl3): δ 267.0 ppm. λmax = 376 nm , log ε = 4.08. mp: 86-91 °C.
E-4-(CH3O)-2,6-Mes2C6H2P=C(H)C6H5 (3.12) To a clean 50 mL RB flask, a stir bar,
0.25 g (0.56 mmol) of 3.6b, 0.04 g (0.6 mmol) of Zn dust was taken. To this mixture was added 3.40 mL (3.40 mmol) of PMe3 (1.00 M in toluene) was added, and the resulting mixture stirred for about 3 h. To this mixture 0.060 mL (0.59 mmol) of benzaldehyde was added, and the reaction allowed to stir for another 2 h for the completion of the reaction. 87
The reaction mixture filtered through a glass frit, and the volatiles were removed under vacuum. Compound 3.12 was extracted into hexanes and the solution filtered. The solvent was removed under vacuum, and the product was rinsed with acetonitrile. The solid was dried under vacuum to give 0.15 g (47 %) of 3.12 as a pale yellow colored
1 solid. H NMR (CDCl3): δ 8.59 (d, JPH = 25.2 Hz, 1H), 7.09 (m, 5H), 6.87 (s, 4H), 6.67
13 1 (s, 2H), 3.81 (s, 3H), 2.26 (s, 6H), 2.08 (s, 12H). C{ H} NMR (CDCl3): δ 180.1 (d, JPC
= 35.2 Hz), 160.7 (s), 146.6 (d, JPC = 8.9 Hz), 140.6 (d, JPC = 14.7 Hz), 138.6 (d, JPC =
2.9 Hz), 137.2 (s), 135.7 (s), 132.4 (s), 128.4 (d, JPC = 2.2 Hz), 128.3(s), 128.1 (d, JPC =
31 1 6.9 Hz), 125.9 (d, JPC = 21.1 Hz), 114.3 (s), 55.5 (s), 21.3 (s), 21.1 (s). P{ H} NMR
(CDCl3): δ 240.7 ppm. λmax = 332 nm , log ε = 4.27. mp: 202-4 °C.
E-4-((CH3)2N)-2,6-Mes2C6H2P=C(H)C6H5 (3.13) To a 25 mL RB flask, a stir bar, 0.10
g (0.21 mmol) of 3.6a, 0.020 g (0.25 mmol) of Zn dust was added. To this 1.28 mL (1.28
mmol) of PMe3 (1.00 M in toluene) was added, and the resulting mixture stirred for about
3 h. To this mixture 0.030 mL (0.25 mmol) of benzaldehyde was added, and the reaction was allowed to stir for another 2 h for completion of the reaction. The mixture was filtered, and the volatiles were removed under vacuum. The product was extracted into hexanes, and the solution was filtered. The solvent was removed under vacuum, this
gave the crude product. The crude material was recrystallized from a concentrated solution of diethyl ether at -35 °C, removal of ether gave 0.050 g (40 %) of 3.13 as
1 yellowish orange solid. H NMR (CDCl3) : δ 8.47 (d, JPH = 24.8 Hz, 1H), 7.08 (m, 5H),
6.88 (s, 4H), 6.45 (s, 2H), 2.97 (s, 6H), 2.28 (s,6H), 2.11 (s, 12H). 31P{1H} NMR
(CDCl3): δ 242.5. mp: 116-8 °C.
88
E-2,6-Mes2C6H3P=C(H)C6H4C(H)=C(H)-C6H4-4-NO2 (3.14) mTo a 50 mL dry RB
flask, a stir bar, 0.20 g (0.48 mmol) of 2,6-Mes2C6H3PCl2, 0.040 g (0.51 mmol) of Zn dust, and 2.90 mL (2.90 mmol) of PMe3 (1.00 M in toluene) was added, and the resulting mixture stirred for about 2 h. To this mixture 0.13 g (0.51 mmol) of (E)-4-(4-nitro- styryl)-benzaldehyde was added and the reaction stirred for another 2 h for completion.
The reaction mixture was filtered through celite, the volatiles were removed under vacuum. The remaining solid was extracted into diethyl ether and the solution was filtered through celite. The solvent was removed under vacuum and the resulting solid re-dissolved into hexanes and filtered through celite. The solvent was removed under vacuum and this material was rinsed with small amount of acetonirile. The product was dried under vacuum to give 0.21 g (75 %) of 3.14 as a pale brownish-orange solid. 1H
NMR (CDCl3): δ 8.62 (d, JPH = 24.8 Hz, 1H), 8.19 (d, JHH = 9.0 Hz, 2H), 7.58 (d, JHH =
9.0 Hz, 2H), 7.45 (t, JHH = 7.6 Hz, 1H), 7.29 (d, JHH = 8.0 Hz, 2H), 7.02-7.17 (m, 6H),
13 1 6.88 (s, 4H), 2.27 (s, 6H), 2.07 (s, 12H). C{ H} NMR (CDCl3): δ 178.9 (d, JPC = 35.6
Hz), 146.9 (s), 145.0 (d, JPC = 8.0 Hz), 144.0 (s), 141.1 (d, JPC = 13.2 Hz), 138.5 (s),
137.2 (s), 136.1 (d, JPC = 7.4 Hz), 135.8 (s), 132.9 (d, JPC = 2.6 Hz), 129.8 (s), 128.7 (s),
128.4 (s), 127.2 (s), 127.0 (s), 126.5 (d, JPC = 21.4 Hz), 126.3 (s), 124.4 (s), 100.3 (s),
31 1 21.3 (s), 21.2 (s). P{ H} NMR (CDCl3): δ 245.1. λmax = 402 nm, log ε = 4.65. mp: 220-
2 °C.
E-4-(CH3O)-2,6-Mes2C6H2P=C(H)C6H4C(H)=C(H)-C6H4-4-NO2 (3.15) To a 50 mL
RB flask, a stir bar, 0.20 g (0.45 mmol) of 3.6b, 0.030 g (0.47 mmol) of Zn dust, 2.70 mL
(2.70 mmol) of PMe3 (1.00 M in toluene) was added, and the resulting mixture stirred for about 3 h. To this mixture 0.12 g (0.47 mmol) of (E)-4-(4-nitrostyryl) benzaldehyde was 89
added, and the reaction stirred 2 h for completion of the reaction. The reaction mixture filtered and the volatiles were removed under vacuum. The remaing solid was extracted into hexanes and filtered through celite. Removal of hexanes gave a solid that was further purified by washing with small amounts of acetonitrile. The desired product was dried under vacuum to afford 0.20 g (71 %) of 3.15 as a brownish-orange colored solid. 1H
NMR (CDCl3): δ 8.53 (d, JHH = 24.4 Hz, 1H), 8.19 (d, JHH = 8.8 Hz, 2H), 7.58 (d, JHH =
8.8 Hz, 2H), 7.27 (d, JHH = 8.4 Hz, 2H), 7.00-7.15 (m, 4H), 6.88 (s, 4H), 6.68 (s, 2H),
13 1 3.82 (s, 3H), 2.27 (s, 6H), 2.09 (s, 12 H). C{ H} NMR (CDCl3): δ 178.6 (d, JPC = 35.6
Hz), 160.6 (s), 146.7 (s), 146.4 (s), 143.8 (s), 141.1 (s), 138.3 (s), 137.0 (s), 135.7 (d, JPC
= 6.5 Hz), 135.5 (s), 132.8 (s), 131.7 (s), 128.1 (s), 126.9 (s), 126.7 (s), 126.2 (d, JPC =
21.1 Hz), 125.9 (s), 124.1 (s), 114.2 (s), 55.3 (s), 21.0 (s), 20.9 (s). 31P{1H} NMR
(CDCl3): δ 245.7. λmax = 409 nm, log ε = 4.66. mp: 205-9 °C.
90
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95
Chapter 4. Synthesis and Studies of 2,6-Diaryl-Benzo-bis(oxaphospholes)
4.1. Introduction
Conjugated organic materials are of special interest in organic electronics.1 The investigation of such materials having phosphorus-carbon double bonds (pπ-pπ) was a goal for the efforts described in the earlier chapters and in studying the synthesis and characterization of meta-terphenyl protected phosphaalkenes and related polymeric materials.2-8 In spite of the success in making such synthetically challenging materials,
there are opportunities to develop more advanced materials having phosphorus-carbon
(pπ-pπ) double bonds. The primary disadvantage with the meta-terphenyl phosphaalkene system is that the requirement of bulky steric stabilizing groups in order to protect the phosphaalkene (P=C) unit in the conjugated organic backbone. The presence of these bulky groups, can disrupt planarity of the molecule and thereby loosing conjugation in the molecul.9 Another disadvantage is that they are synthetically difficult due to their high reactive. Also, because of this reactive nature of the phosphaalkene (P=C) bond these materials have issues and difficulties to do any further chemical modifications.10
Thus, there is a need to develop other phosphorus-carbon double bonded (pπ-pπ) conjugated systems.
To address these issues and to develop similar materials with conjugated phosphaalkene (P=C) π bonds, the investigation of the heterocyclic organophosphorus conjugated materials were undertaken (Chart 4.1).
96
P P P P E E
4.1A 4.1B 4.1C 4.1D
Phosphinine Phosphole Heterophospholes, E=O,N,S
Chart 4.1. A few selected examples for heterocyclic organophosphorus compounds.
The heterocyclic molecules are comparatively less reactive than acyclic phosphaalkenes; this is due their aromatic stabilization eg. phopsholes, heterophospholes.
Hence, the synthetic and characterization difficulties involved in the studies of phosphaalkenes can be overcome easily. In addition, the absence of bulky steric stabilizing groups may help the molecules to be more planar than the normal phosphaalkene materials. In this direction, the heterophospholes are the more interesting materials to study and in particular compounds featuring 1,3-Oxaphosphole units.
4.2. meta-Terphenyl Phosphaalkenes to Benzoxaphospholes
Heincke and co-workers, were the first group to report the synthesis and studies of
2-alkyl/aryl-1,3-benzoxaphospholes.11-15 During these studies, in addition to the benzoxaphospholes, it was synthetically demonstrated that other heterophospholes with groups like CH, As and N groups. In 1985, Hausen et. al. reported the X-ray crystal structure for the compound 4.2 (Chart 4.2). 16
97
O Cl Bond length (P=C) 1.712 Å P Torsion angle (P=C-C=C) 177.8° 4.2
Chart 4.2. Hausen et.al. reported X-ray crystal structure data for
2-arylbenzoxaphosphole16
The crystal structure data from Hausen et.al16 indicates that the 1,3-oxaphospholes
exhibit planar conformation and maintains the phosphorus carbon double bond in five membered cyclic ring. Therefore, a thorough understanding and investigations of these classes of molecules can be helpful to develop more planar and conjugated phosphorus carbon double bonded materials.
A model representation for the basic chemical backbones for the meta-terphenyl phosphaalkene 4.3 and a 2-phenyl-1,3-benzoxaphosphole 4.4 was show in figure 4.1.
P P
O
4.3 4.4
Figure 4.1. Molecular structure of (4.3) meta-terphenyl phosphaalkene (θ ≠ 0 or
180) and an analogous (4.4) 2-aryl-1,3-benzoxaphosphole (θ ≈ 0 or 180).
The presence of bulky steric stabilizing meta-terphenyl group results in a shift from the planarity i.e. phosphaalkene (P=C) plane bond and it can be seen from the figure
98
4.1, whereas the 1,3-benzoxaphosphole is a flat molecule and also maintains the planarity unlike sterically protected meta-terphenyl phosphaalkene. It should be noted that the similar benzoxazole (both mono and bis) molecules (Chart 4.3) are well known and extensively studied for their electronic properties.17-22
N O O
O N N
4.5 4.6
Chart 4.3. Examples for known bis and mono-benzoxazoles
The polymers made with the benzoxazole or benzothiazole (sulfur instead of oxygen) units are also well known and these classes of polymers are often referred as rigid rod polymers (chart 4.4).23-29 due to their high stability and highly planar (rod like)
structural properties.
N O N S
O N S N n n
4.7 4.8 Chart 4.4. Examples for benzo-bisoxazole and benzo-bisthiazole polymers
In the view of their very robust and conjugation properties observed in benzo-bisoxazole
and benzo-bisthiazole polymers, the synthesis and studies of similar phosphorus
counterparts are interesting materials. Since, it is known that the conjugated
organophosphorus heterocyclic compounds namely, phospholes based materials are
currently extensively studied for their electrooptical applications.30
99
4.3. Benzoxaphospholes
The idea of replacing nitrogen in the above mentioned compounds with phosphorus can result in a new class of conjugated materials featuring benzo- bisoxaphosphole (BBOP) units. These oxaphospholes are expected to have more stable
P=C (pπ-pπ) double bonds, because of the resonance stabilization through the heterocyclic
ring structure. The present focus is on benzo-bisoxaphosphole system because of their structural similarity with the established compounds such as 4.5, 4.7 and 4.8. The 1,3-
oxaphosphole unit when fused to a benzene ring known as 1,3-benzoxaphospholes and
these are well known but the related chemistry of benzo-bisoxaphospholes are completely
unexplored. The flexibility to change the oxygen atom with other atoms such as sulfur,
selenium or any other atom can lead to plethora of conjugated cyclic heterophospholes
and thereby opening a wide spectrum of new possible organophosphorus materials (Chart
4.5) including their respective geometrical isomers 4.9a and 4.9b.
Hn P E P P E = S, Thiaphosphole (n=0) Ar Ar Ar Ar Se, Selenaphosphole (n=0) E P E E N, Azaphosphole (n=1) H H H n n n Ar = Aromatic substituents "trans" "cis" 4.9a 4.9b
Chart 4.5. New class of 1,3-heterophospholes
Thus, the present work focuses on synthesis and characterization of such benzo-
bisoxaphospholes and presently the focus is on the synthesis and studies of these basic building blocks such as 2,6-diaryl-benzo-bis(1,3-oxaphospholes) (Chart 4.6).
100
P O O Ar Ar Ar Ar = Aromatic substituents O P P
4.10 4.11 Chart 4.6. Synthetic target, 2,6-diaryl-benzo-bis(oxaphospholes) (4.10) and
known mono-benzoxaphosphole (4.11)
4.4. Results and Discussions
4.4.1. Benzoxaphospholes: Synthesis of Key Intermediates
Several routes are known for the synthesis of oxaphospholes, among the known
synthetic routes the condensation reaction between arylhydroxylphosphine and N- arylimidoyl chlorides is more versatile synthetic path. Heinicke and co-workers successfully employed this synthetic technique to synthesize various substituted benzoxaphospholes as shown in chart 4.7. 15,31
OH NAr O R1 PH2 R1 Cl Et2O P
4.12 R1:ArorAlkyl R1: Ar or Alkyl
Chart 4.7. Synthesis of benzoxaphospholes by condensation methods
The dehydrocyclization is another well known synthetic method (Chart 4.8), but its
synthetic success mainly limited to the synthesis of alkyl substituted
benzoxaphospholes.15,31
101
R2 O R2COCl, Et N P O ,AlCl OH 3 O 4 10 3 O R2 PH o 80-100 oC P 2 -10 to -30 C, PH2 Et O 2 R2 =Alkyl
4.12
Chart 4.8. Synthesis of benzoxaphospholes by dehydrocyclization
Therefore, to proceed with the condensation route, the key intermediates are phosphinophenol and the corresponding N-arylimidoyl chlorides. The synthesis of 2- phosphinophenol 4.12 was reported earlier,32,33 but there are few drawbacks with the
reported procedures. Hence, the 4.12 was prepared by slight modification to the earlier reported procedures as shown in scheme 4.1. The modifications include the use of
34 ClP(O)(OEt)2, THF, Et3N instead of HP(O)(OEt)2, CCl4, Et3N. Since, it is a known
reaction (Atherton-Todd reaction), that the HP(O)(OEt)2 in presence of a base reacts with
35 CCl4 to form ClP(O)(OEt)2. Therefore, by considering the expense and hazardous
nature of CCl4, the reaction conditions were modified to use ClP(O)(OEt)2, THF and
Et3N. This change in reaction conditions has not affected in anyway the yield of the final
product. Also in the last step, the reduction was performed by refluxing the phosphonate
33,36 ester (4.15) with LiAlH4 in THF for overnight instead of stirring at room temperature for 4 days.
102
EtO O OEt O P EtO OEt P OH O o PH2 ClP(O)(OEt)2 LDA -78 C LiAlH4 OH THF-Et3N, rt THF, 2h OH THF, reflux, 24 h
4.13 4.14 4.15 4.12
Scheme 4.1. Synthesis of 2-phosphinophenol 4.16.
In a similar fashion, to accomplish the synthesis of benzo-bisoxaphosphole, the 2,5-
diphosphinohydroquinone 4.16 was synthesized successfully by following the same
synthetic procedures as in the case of 4.12, beginning with hydroquinone as the starting
material. The synthetic scheme was shown in scheme 4.2.
O OEt OEt P O OEt OH O OEt P PH 2 OH OH LDA -78 oC LiAlH ClP(O)(OEt)2 4
THF, rt THF, 2h HO THF, reflux, 36 h HO OH 70% O OEt P 62% PH 2 P 60% EtO O OEt OEt O 4.17 4.18 4.19 4.16
Scheme 4.2. Synthesis of 2,5-diphosphinohydroquinone 4.16.
The aryl hydroxyphosphines 4.12 and 4.16 are colorless solids at room temperature and have the characteristic pungent odor of phosphines. The compound 4.1233 was purified by
vacuum distillation as colorless solid, where as 4.16 purified by column chromatography
using a neutral silica gel support and diethylether-hexanes (50-50) solvent system. Thus, the 2-phosphinophenol, 4.12 and 2,5-diphosphinohydroquinone, 4.16 are the key intermediates to make both the mono and benzo-bis(oxaphosphole) were achieved successfully (Chart 4.9).
103
OH H2P OH
PH2 HO PH2
4.12 4.16 Chart 4.9. 2-phosphinophenol and 2,5-diphosphinohydroquinone
The flexibility of the condensation of N-arylimidoylchlorides with hydroxyphosphines seems to be more efficient. The synthetic success of this reaction was tested with the synthesis of the known 2-phenyl-1,3-benzoxaphosphole, 4.4 by using 4.12 and N- phenyl-benzimidoyl chloride 4.20, (Scheme 4.3). Through this synthetic route, the expected final product was successfully synthesized as a pale yellow colored solid
(4.4).15,31
OH N O
PH2 Cl Et2O, 3days P
4.12 4.20 4.4
Scheme 4.3. Synthesis of known 2-phenyl-1,3-benzoxaphosphole using
condensation of 4.12 and N-arylbenzimidoyl chloride 4.20.
The N-arylimidoyl chlorides can be made easily by following conventional chemical transformations as shown in scheme 4.4.37-42
104
Mg + CO2,H3O OH SOCl2 Cl Ar-Br Ar Ar THF, reflux O Reflux, 6h O
Cl Et3N, PhNH2 HN Ph SOCl2 N Ph Ar Ar Ar O EtOAc, rt, 6h O Reflux, 6h Cl
Ar = Aryl Scheme 4.4. Synthetic scheme followed to make N-arylbenzimidoyl chloride
In spite of the success in synthesis of 2-phenyl-1,3-benzoxaphosphole 4.4, other routes
were attempted to find the best possible reaction to make 1,3-benzoxaphsophospholes.
The reductive cyclization reaction was successfully employed by Bansal et. al. in making benzophosphazole. This route found to be very similar to dehydrocyclization method
(Chart 4.8).43
O H H H N O N O PhCOCl, re P P O O O Pyridine, rt O
O
H N O H N P LiAlH4,24hr O O rt P
Chart 4.10. Reductive cyclization 2-phenyl-1,3-benzophosphazole
105
Therefore, by using similar reaction conditions the phosphorus analogue namely 4.15, was used to verify whether such ring closure is possible by performing suitable chemical modifications (Scheme 4.5).
O H O O O O P PhCOCl, O P O O Pyridine, rt O 4.15 4.21 O O O O P LiAlH4,48h O O THF, rt P 4.21 4.4
Scheme 4.5. Reductive cyclization to oxaphospholes
The O-benzoylation of 4.15 with PhCOCl and pyridine gave 4.21 in good yield.
But, the reduction of 4.21 with LiAlH4 based on the reported procedure did not show the
cyclized product 4.4, instead a complete reduction of the phosphonate group to phosphine
(PH2) was observed.
b ( a
31 1 Figure 4.2. The P{ H} NMR (CDCl3) of 4.21 before (a) and after (b) reduction
with LiAlH4
106
To test the other synthetic possibilities, instead of N-arylimidoylchlorides, an
arylimidate (4.22) was utilized for the condensation with 4.16 (Scheme 4.6).
NH Cl O HCl ,MeOH 2 (g) O NH2 4.22
H P P O 2 OH NH2Cl + 2 PH THF, 1 week O P HO 3 O 4.23 4.16 4.22
Scheme 4.6. Synthetic attempts though arylimidateester
The imidate ester 4.22 was made by bubbling the gaseous HCl into a methanolic
solution of benzamide.44-46 The ester later used with 4.16 to carry out cyclocondensation.
The reaction was monitored by 31P{1H} NMR spectroscopy, but the reaction found to be
unsuccessful, which is confirmed by the absence of any peak in 31P{1H} NMR near 70-
90 ppm. Therefore the synthesis of targeted compounds was continued with the
successful and easy condensation route between 2,5-diphosphinohydroquinone and N-
arylimidoylchlorides.
4.4.2. Synthesis of 2,6-diaryl-benzo[1,2-d;5,4-d']bis(1,3-oxaphospholes)
Initial attempts were focused to synthesize the simplest 2,6-diaryl-benzo-
bis(oxaphospholes) with aryl groups being phenyl (4.23) and 4-bromophenyl (4.28). The
condensation of 4.20 with the respective N-arylimidoyl chlorides with 4.21, 4.22 were
carried out in THF under refluxing conditions (scheme 4.7).
107
H2P OH N Cl P O X X THF, reflux, 24h HO PH2 O P
4.16 X X=H(4.20) X=H(4.23) X=Br(4.24) X=Br(4.25)
Scheme 4.7. Condensation of 4.16 and N-arylimidoylchlorides to synthesize 2,6- diphenyl-benzo-bis(oxaphospholes)
The reaction was monitored by 31P{1H} NMR spectra and the product formation was evident by their characteristic signals near 80-90 ppm. But unfortunately, the isolation of pure materials became problematic and difficult to characterize. Also, the other issue being these crude material seems to have low solubility even in solvents such as THF and
CHCl3. Various attempts for the isolation and purification of these materials found to be unsuccessful by aqueous methods,11,15,31 crystallization and chromatography techniques.
The poor solubility of these compounds (4.23 and 4.25) may be due to their planar nature of these specific molecules.
Figure 4.3. The fluorescent nature of the compound 4.23 on exposure to UV light
31 1 (365 nm) in CDCl3, and its respective P{ H} NMR in CDCl3.
108
31 1 Interestingly the materials (pure by P{ H} NMR) after their dissolution into CDCl3 or
THF were found to be highly fluorescent (Figure 4.3). On this positive note, we
attempted to introduce some structural changes to the BBOP’s specifically through the aryl system so that solubility can be increased and also it will be easy for to do further synthesis and characterization.
Instead of a simple phenyl system different variations of the para-substituted
benzoxaphospholes synthesis were attempted (scheme 4.8).
N Cl H2P OH P O R1 R1 THF, reflux, 24h HO PH2 O P
R1 4.12 R1 =MeO(4.26) R1 =MeO(4.29) =HexO(4.27) =HexO(4.30) = t- Bu (4.28) = t- Bu (4.31)
Scheme 4.8. Attempts to synthesize para substituted benzo-bisoxaphospholes
The necessary N-arylimidoylchlorides (4.26-4.28) were made by following the same
procedure as described in the scheme 4.4. All the reactions were monitored by 31P NMR spectra and it was observed that introduction of the para substituted groups has actually helped in terms of their solubility and to monitor by NMR, but the purification and the isolation of these materials remained unsuccessful.
In the next logical sequence, a set of ortho susbsituted benzo-bisoxaphosphole synthesis was attempted. Mesityl and m-xylyl groups were considered for the aryl group.
The N-arylimidoylchlorides for this synthesis were made by following the same scheme
4.4. Starting with mesitylenebromide and 2-bromoxylene (Scheme 4.9) the carboxylic
109 acids and the respective aryl amides were made by following the earlier reported procedures or by slight modifications to the earlier reported procedures.37-42
Br CO H COCl Mg 2 R1 R1 + R R R1 R1 CO2,H3O 1 1 SOCl2
THF, Reflux Reflux, 6h R2 R2 R2
R1 =R2 =Me (4.34) R1 =R2 =Me (4.32) R1 =Me;R2 =H(4.35) R1 =Me;R2 =H(4.33) Ph Cl N COCl CONHPh R R R R R1 R1 1 1 Et3N, PhNH2 1 1 SOCl2
EtOAc, rt, 6h Reflux, 6h
R2 R2 R2
R1 =R2 =Me (4.36) R =R =Me (4.38) R =Me;R =H(4.37) 1 2 1 2 R1 =Me;R2 =H(4.39)
Scheme 4.9. Synthesis of mesityl and m-xylyl imidoylchlorides
The condensation reaction of mesityl (4.38) and m-xylyl (4.39) imidoylchlorides with
2,5-diphosphinohydroquinone (4.16) was carried out under the same refluxing conditions in THF and as well the reaction progress was monitored by 31P{1H} NMR spectra, NMR indicated clean product formation by their characteristic chemical shifts around 90-100 ppm. After the confirming the completion of the reaction by NMR, insoluble part (salt) removed by filtration, followed by removal of solvent (THF) and after final workup pure products were obtained as pale yellow colored compounds (4.40 and 4.41) (Scheme
4.10). These are the first successfully purified 2,6-diaryl-benzo-bisoxaphospholes.
110
R N Cl R1 1 H2P OH P O R R 1 1 R2 R2 THF, reflux, 24h HO PH2 O P R1 R1 R2 4.20 R1 =R2 =Me (4.40) R1 =R2 =Me (4.38) R1 =Me;R2 =H(4.41) R1 =Me;R2 =H(4.39)
Scheme 4.10. Synthesis of 2,6-diaryl-benzo-bis(oxaphospholes) 4.40 and 4.41
The synthesized BBOP’s (4.40 and 4.41) are colorless to pale yellow colored solids, they
found to have high melting points. In terms of solubility and chacterizations purposes
these are far better than the earlier attempted simple phenyl (4.23 and 4.25) aryl systems
(4.29-4.31).
4.4.3. Spectroscopic Studies.
The UV-vis absorption spectra of the previously made meta-
terphenylphosphaalkene 2.5a, (λmax:331 nm (CHCl3)) and the 2-phenyl-1,3-
benzoxaphosphole 4.4 (λmax: 339 nm (CHCl3)) were observed to have close λmax for the
π-π* transition. However, a small red shift of ~ 9 nm is observed in the case of 4.4. This reflects clearly the electronic properties shown by the phosphaalkene should be very close the properties of the benzo-bis(oxaphosphole) system.
111
R1 R1 P O R2 R2 O P
R1 R1
R1 =R2 =Me (4.40) R1 =Me;R2 =H(4.41)
Figure 4.4. UV-vis absorption spectra of BBOP (4.40 and 4.41) in CHCl3 and in
CH2Cl2
The UV-vis absorption spectra for the synthesized benzo-bis(oxaphospholes) 4.40 and
4.41 showed very close absorption maximum (λmax) due to their close structural similarities (Figure 4.3). The absorption spectra did not change much by changing the solvent from CHCl3 to CH2Cl2. Interestingly, the presence of one more oxaphosphole unit and an extra phenyl ring not showed any great shift in the absorption maxima (λmax) of
benzo-bis(oxaphospholes) compared to the simple benzoxaphosphole 4.4.
R1 R1 R1 P O P O R1 R1 P O R1 R2 R2 R2 R1 R1 R1 O P O P O P R1 R1 R1 R1 R1 R1
Chart 4.11. Possible molecular orientations of BBOP (4.40 and 4.41) in solution
112
The possible reason for this may be due to involvement of a rotation of the aryl ring from
the central benzo-bis(oxaphosphole) plane (Chart 4.11), resulting in a decrease in π- conjugation and thereby not influencing the λmax.
R1 R1 P O R2 R2 O P R R 1 1
R1 =R2 =Me (4.40) R =Me;R =H(4.41) 1 2
Figure 4.5. Fluorescence spectra of 4.40 and 4.41 in CHCl3 and CH2Cl2
(λexc : 340 nm)
The synthesized compounds exhibited blue fluoresce. The fluorescence emission spectra
for these prepared compounds 4.40 and 4.41 showed the emission maximum at 434 nm -
436nm in chloroform and dichloromethane solvents respectively. These are the first
reported absorption and fluorescence spectral data for any 2,6-diaryl-benzo-[1,2-d;5,4-
d']bis(1,3-oxaphospholes). The quantum yields for these compounds (4.40, 4.41) found to
be lower both in chloroform and dichloromethane solvents. In chloroform, the quantum
yields are Φ = 0.22 and 0.27 for 4.40 and 4.41 respectively, whereas in dichloromethane
113 the quantum yields for 4.40 and 4.41 are Φ = 0.21 and 0.15 respectively (λexc : 340 nm; standard: anthracene in EtOH). This lower quantum yields probably due to relaxation of the excited state singlet system through other non-radiative path. Another possible reason has to be an intersystem crossing of the excited singlet state to a triplet system and there by relaxation to the ground state through the radiative (phosphorescence) or non-radiative path. The absorption and fluorescence spectra indicate that there is approximately 100 nm
(stokes shift) difference between the λmax of absorption and fluorescence reflecting other
possibilities for decay of the excited state species through phosphorescence. In order to
understand this, the lifetime measurements for these two compounds were calculated.
The lifetimes (τ) are 2.3 ± 0.4 ns for 4.40 and 3.7 ± 0.3 ns for 4.41 respectively. These
predominantly faster lifetimes indicate that the relaxation was mainly through the singlet states and leaving small possibilities for the phosphorescence. However, the poor quantum yields and life time measurements shows that in addition to fluorescence decay path, there are other significant non-radiative processes are taking place and it needs further photophysical investigations.
4.4.4. Electrochemical Studies
The cyclic voltammetry measurements were performed on the compounds 4.40
and 4.41. The experiments were conducted in THF with [n-Bu4N][BF4] as the electrolyte, and in the presence of ferrocene as a reference (the left-most wave in each scan).
Potentials are thus corrected for known potential of ferrocene vs SCE. These materials found to exhibit two quasi reversible redox potentials. But, the 4.40 has a small shoulders to it, whereas, 4.41 has not shown such shoulders in CV and it has clean two electrons
114
redox process. The cyclic voltammogram for the two compounds were shown in figures
4.6 and 4.7.
3.0x10-5
2.0x10-5
1.0x10-5
0.0 Current (A)
-5 -1.0x10 Fc/Fc+
-2.0x10-5
-3.0x10-5 1 0 -1 -2 -3 Potential vs SCE (V)
Figure 4.6. Cyclic voltammogram of 4.40, 0.001M 4.40/0.001M ferrocene in
0.1M [n-Bu4N][BF4] in THF with 0.1 V/s scan rate
3.0x10-5
2.0x10-5
1.0x10-5
0.0 Current (A) Current -5 -1.0x10 Fc/Fc+
-5 -2.0x10
-3.0x10-5
1 0 -1 -2 -3 Potential vs. SCE (V)
Figure 4.6. Cyclic voltammogram of 4.41, 0.001M of 4.41/0.001M ferrocene in
6 0.1M [n-Bu4N][BF4] in THF with 0.1 V/s scan rate
115
Ec(V) Ea(V) E1/2(V) Ec(V) Ea(V) E1/2(V) 4.40 -2.12 -1.89 -2.01 -2.48 -2.23 -2.36 4.41 -2.07 -1.82 -1.95 -2.41 -2.15 -2.28 + solvent: THF; supporting electrolyte: 0.1M [n-Bu4N][BF4]; reference: Fc/Fc ; scan rate: 0.1 V/s
Table 4.1. Cyclic voltammogram data of 4.40 and 4.41
Except for the presence of a p-methyl group, both the compounds 4.40 and 4.41 are structurally similar. Therefore, they are expected to have similar redox properties and hence their redox potentials. In the previous chapters, the simple meta-terphenyl phosphaalkene (compound 3.7), has shown a single redox peak around -1.9 V, in this case of 2,6-diaryl-benzo-bis(oxaphosphole) they have two such reducible P=C bonds. In a previous study related to the redox properties of Dmp substituted diphosphenes, the
t DmpP=PDmp and bis diphosphene DmpP=P-Ar-P=P-Dmp, Ar = 2,3,5,6-( Bu)4C6 has
shown single redox peak for the mono and two peaks in the case of bis system
respectively. This reflects that the first reduced diphosphene (P=P) group has an effect on
the other reducible diphosphene (P=P) group to form respective radical dianions.6 The
similar trend is possible in the case of 4.40 and 4.41 and hence the two quasi reversible
peaks in the case of benzo-bis(oxaphospholes). Also, in the case of BBOP’s the P=C group being part of the aromatic heterocycle it is slightly harder to reduce than the P=C
group in an acyclic system. One can see this difference from the redox properties of the
simple phosphaalkenes (see CV of 3.7).
116
4.5. Conclusions.
A new class of compounds, 2,6-diaryl-benzo-bis(1,3-oxaphospholes) was successfully synthesized and characterized. The synthesis was accomplished through cyclocondensation reaction of 2,5-diphosphinohydroquinone and N- arylimidoylchlorides. These compounds found to have a characteristic chemical shift near
80-90 ppm in 31P NMR spectra, which is similar to the known benzo(1,3-oxaphospholes).
Initial attempts of synthesizing simple phenyl systems lead to issues related to isolation
and charcterization. Therefore, the compounds with para position and ortho positions
were utilized to optimize the synthesis. Finally, the ortho substituted compounds, namely
mesityl and xylyl based compounds were synthesized and isolated as colorless solids.
These 2,6-diaryl-benzo-bis(oxaphospholes) are having high melting points (greater than
200°C) namely mesityl group containing benzo-bis(oxaphosphole) melts around
270 °C. Also, these materials are very much stable outside the nitrogen glove box. The
synthesized materials were characterized by NMR, UV-vis, fluorescence, lifetime
measurements and electrochemical studies. All these properties makes 2,6-diaryl-benzo-
bis(oxaphospholes) interesting candidates for further studies and investigations and
thereby, to develop more advanced conjugated organophosphorus materials.
4.6. Experimental Section
General Procedures. All the reactions and purifications were done using Schlenk line
techniques and or by using an MBraun Labmaster nitrogen glove box. Cary UV-Vis
[Cary 500] instrument was used in recording the UV-Vis absorption data and Cary-
Florimeter was used to do Fluorescence studies. Spectroscopic grade chloroform
(Fischer) was used to perform all optical measurements either for the UV-vis absorption
117 or fluorescence studies, prior to use the chloroform was dried by passing over dry neutral
Al2O3 followed by degassing it with N2 for about 2 h. The melting point for the
compounds was taken using the Mel-Temp instrument. The dry solvents
(Tetrahydrofuran, Diethyl ether and Hexanes) were prepared by refluxing under N2 atmosphere along with metallic sodium and benzophenone to a blue colored end point, later the solvents were collected under nitrogen atmosphere. In case of Hexanes, prior to the distillation a few drops of tetra(ethylene glycol)dimethyl ether was added in addition to sodium and benzophenone. Dry Acetonitrile was made by drying over anhydrous
Calcium hydride and followed by distillation under nitrogen atmosphere. All the materials were characterized by Varian-Inova Instrument (400 MHz 1H, 600 MHz 1H ,
31 13 31 162 MHz P and 100 MHz C NMR’s) using CDCl3 and or CD3OD as solvents. P
NMR referenced to 85% H3PO4 as an external standard. Cyclic voltammetry experiments
were performed using a CH Instrument (CHI630C) workstation in a glove box under
nitrogen atmosphere. The supporting electrolyte, tetrabutylammonium tetrafluoroborate
(Fluka) was recrystallized four times using 1:3 concentrated solutions of ethyl acetate and diethyl ether. The electrolyte was then dried thoroughly under vacuum at 100 - 120 °C and stored in the drybox. Ferrocene was purified by sublimation. A glassy carbon working electrode was polished with 0.05 micron alumina and thoroughly cleaned and dried before use. A silver wire was utilized as a quasi-reference electrode and a platinum wire as the counter electrode. All scans were performed at a scan rate of 0.1 V/s with a potential window of approximately -3 to +1.5 V versus saturated calomel electrode
(SCE).
118
Synthesis of 4.16. In a 1000 mL flask, 5.00 g (13.1 mmol) of 4.19 was dissolved 150 mL of dry THF. To this solution 2.98 g (78.5 mmol) of LiAlH4 in 100 mL of THF was slowly
added. The reaction is exothermic in nature and it turned to grayish green color. The
resulting mixture allowed to reflux under N2 atmosphere for about 36 h. Later it was
allowed to attain room temperature and finally cooled in an ice bath. To this chilled
solution, through metal cannulae in saturated ammonium chloride solution was added dropwise. Once there is no vigorous reaction to the addition of saturated ammonium chloride solution it confirms no more active LiAlH4. To this mixture, 150 mL of CHCl3 was added through the cannulae and stirred well. Allow the organic layer to settling down for few minutes (10 min). The organic part carefully transferred to another clean flask under N2 atmosphere. This procedure was repeated again once more with 150 mL of
CHCl3. Later, the organic part was washed with 100 mL of water and 100 mL of brine.
Finally the organic part dried with anhydrous Na2SO4 and the excess solvent was
removed under vacuum. This gave a colorless crude product. This material was later
purified by column chromatography with neutral silica gel and with diethylether-hexane
(50:50) system. This gave 1.61 g (62.3 %) of pure 4.16 as colorless solid. 1H NMR
31 1 (CD3OD): 6.76 (m, 2H), 3.94 (s, 2H), 3.43 (s, 2H). P{ H} NMR (CDCl3): -143.7.
13 1 C{ H} NMR (CD3OD): 151.5 (d, JCP = 6 Hz), 120.6 (d, JCP = 13 Hz), 116.9 (d, JCP = 10
Hz). mp: 174-178°C. HRMS. Calcd for C6H8O2P2: 174.0000. Found: 174.0002.
Synthesis of 4.21. In a 250 mL flask, 2.00 g (8.69 mmol) of 4.15 was taken in 100 mL of
pyridine. To this solution 1.34 g (9.54 mmol) of benzoylchloride added dropwise. The
resulting mixture stirred at room temperature for 8 h. Later, pyridine was removed by
washings with 100 mL of 1M CuSO4 solution until aqueous phase remains colorless.
119
Then finally the reaction mixture was washed with 100 mL of water. The organic part extracted with DCM. Removal of solvent under vacuum gave 1.30 g (45.0%) of 4.21. 1H
NMR (CDCl3): 7.44 (mt, 1H), 7.38 (mq, 1H), 7.22 (mt, 2H), 6.97 (mt, 1H ), 6.92 (m,
31 1 2H), 6.85 (d, JHH = 12 Hz, 2H), 4.15 (m, 2H), 4.05 ( m, 2H), 1.32 (mt, 6H). P{ H}
NMR (CDCl3): 23.0.
General procedure for the preparation of N-arylimidoyl chlorides: In a 100 mL round bottom flask, 5.00 g of N-arylamide dissolved in excess SOCl2 (10 mL). The
resulting mixture refluxed under N2 atmosphere for about 6 h. Later, excess thionyl
chloride removed by distillation. The final, pure N-arylimidoyl chlorides were obtained
by vacuum distillation under reduced pressure as solid materials.34
Synthesis of 4.38.47-49 In a 100 mL round bottom flask, 5.00 g (20.9 mmol) of N- phenylmesitylamide dissolved in excess SOCl2 (10 mL). The resulting mixture refluxed
under N2 atmosphere for about 6 h. Later, excess thionyl chloride removed by distillation.
The final, pure N-mesitylimidoyl chloride was obtained by vacuum distillation under
reduced pressure as 4.50 g (84.0 %) of yellow solid material. mp: 65-68 °C.
Synthesis of 4.39. In a 100 mL round bottom flask, 5.00 g (22.2 mmol) of N-
50,51 phenylxylylamide dissolved in excess SOCl2 (10 mL). The resulting mixture refluxed
under N2 atmosphere for about 6 h. Later, excess thionyl chloride removed by distillation.
The final, pure N-xylylimidoyl chloride was obtained by vacuum distillation under
1 reduced pressure as 4.10 g (76.0 %) yellow solid material. H NMR (CDCl3): 7.43 (m.
2H), 7.22 (m, 2H), 7.09 (m, 4H), 2.45 (s, 6H). mp: 55-58 °C.
120
General procedure for the cyclocondensation: In a clean dry flask to 1.0 equivalent of
2,5-diphosphinohydroquinone (4.16) was dissolved in dry THF, to this 2.1 equivalents of the respective N-arylimidoyl chloride was added and the reaction mixture was refluxed for overnight (reaction progress monitored by 31P NMR). After completion of the
reaction the insoluble part was filtered out. Removal of solvent from the filtrate gave the
crude material. This is purified by washings with 5 mL of acetonitrile and finally the
product dissolved into ethyl ether and THF (1:1) till all the solid goes into solution. This
after filtration with basic alumina, followed by removal of solvent gave pure
benzoxaphospholes.
Synthesis of 4.40. The compounds 0.50 g (2.07 mmol) of 4.16 was taken into 50 mL of
THF and to this 1.50 g (5.89 mmol) of 4.38 was added and allowed to reflux for 24 h
under nitrogen atmosphere. Reaction mixture was cooled to room temperature. The
insoluble part was filtered out. Removal of solvent from the filtrate gave the crude
material. This is purified by washings with 10 mL of acetonitrile and finally the product
dissolved into ethyl ether-THF (1:1) till all the solid goes into solution. This on filtration
with basic alumina, followed by removal of solvent left pure 0.54 g (40 %) of 4.40 as
1 white solid. H NMR (CDCl3): 8.31 (d, JHH =1.8 Hz, 2H), 6.99 (s, 4H), 2.35 (s, 6H), 2.28
31 1 13 1 (s, 12H). P{ H} NMR (CDCl3): 99.7. C{ H} NMR (CDCl3): 198.9 (d, JCP = 54 Hz),
156.6 (m), 139.6 (s), 137.9(m), 131.1(m), 128.9, 112.1(d, JCP = 21 Hz), 21.5, 21.0. mp:
270-273 °C. HRMS Anal. Calcd for C26H24O2P2: 430.1251 Found: 430.1252
Synthesis of 4.41. The compounds 0.50 g (2.07 mmol) of 4.16 was taken into 50 mL of
THF and to this 1.50 g (6.15 mmol) of 4.39 was added and allowed to reflux for 24 h
under nitrogen atmosphere. The reaction was monitored by phosphorus NMR for
121 completions. After the completion of the reaction, the reaction mixture was cooled to room temperature. The insoluble part was filtered out. Removal of solvent from the filtrate gave the crude material. This is purified by washings with 10 mL of acetonitrile and finally the product dissolved into ethyl ether-THF (1:1) till all the solid goes into solution. This on filtration with basic alumina, followed by removal of solvent left 0.45 g
1 (40 %) of pure 4.41 as pale yellow solid. H NMR (CDCl3): 8.34 (d, JH-H =1.8 Hz, 2H),
31 1 13 1 7.29 (m, 6H), 7.18 (m, 4H), 2.32 (s, 12H). P{ H} NMR (CDCl3): 99.9. C{ H} NMR
(CDCl3): 198.7 (d, JCP = 54 Hz), 156.6 (m), 138.0 (m), 137.5 (m), 133.9 (d, JCP = 13 Hz),
129.6, 128.1, 21.1. mp: 229-232 °C. HRMS. Calcd for C24H20O2P2: 402.0393. Found:
402.0947
122
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(25) Thomas, E. L. Phase transformations, ultrastructure and properties of rigid-rod polymers, Dep. Polym. Sci. Eng.,Univ. Massachusetts,Amherst,MA,USA., 1991.
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Macromolecules. 1998, 31, 5229-5239.
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126
Chapter 5. Summary
The phosphorus-carbon (phosphaalkene) double bonded, conjugated organophosphorus compounds are an important class of materials and found to be interesting for their unique electrooptical properties. But, the high reactivity of these materials remained one of the main issues in the studies related to these conjugated organophosphorus compounds. With the introduction of steric stabilizing groups a large number of compounds featuring phosphorus carbon double bonds have been made and reported extensively. One of the widely used steric stabilizing group is a meta-terphenyl group. The first part of the thesis deals with photochemical isomerization of such meta- terphenyl protected phosphaalkenes and the resulting effect on the structure and properties. The second part of the work deals with studies related to the effect different substituent groups on the structure and properties of meta-terphenyl phosphaalkenes. The final part of the thesis moves on to synthesis and characterization of benzo-bis(1,3- oxaphospholes) which belongs to a new class of conjugated organophosphorus materials.
5.1. Photochemical Isomerization.
meta-terphenyl protected phosphaalkenes and diphosphenes were made and studied earlier. But their photochemical isomerization has not been investigated. During this investigation it is observed that a meta-terphenyl diphosphene (Dmp-P=P-Dmp) did not undergo any photochemical isomerization, but we observed that the related phosphaalkenes (X-Dmp-P=CHPh-X’, X, X’: H, Br)), all of them are undergoing photochemical isomerization (Figure 5.1).
127
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Figure 5.1. The 31P{1H} NMR of Dmp diphosphene (DmpP=PDmp) and (Br-
DmpP=CHPh-Br) Dmp phosphaalkene mixture before and after exposure to 350 nm light. 128
Therefore, a series of meta-terphenyl phosphaalkenes synthesized through the phospha-Wittig reaction route and a detailed photochemical investigation was undertaken. It is observed that all the phosphaalkenes are photochemically active unlike its related diphosphene. The photochemical conversion was observed to occur even in solid state but very minimal compared to that in a solution phase. Both the E and Z isomers of one of these new materials 2.8 have been fully characterized. The Z-isomer of this compound has shown interesting features in the 1H NMR, due the hindered phosphorus-aryl bond rotation in the meta-terphenyl unit. Variable-temperature 1H NMR studies performed to calculate and analyze the thermodynamic parameter for the hindered rotation. The E and Z isomers of this compound were completely characterized by single crystal X-ray crystallography and UV-vis absorption studies.
5.2. Effect of Substituents on meta-Terphenyl Protected Phosphaalkenes
The effect of different substituent groups on carbon-carbon conjugated system has been well studied and materials with this kind of charge polarization are interesting candidates for nonlinear optical properties. In this direction, we studied the effect of different substituent groups on meta-terphenyl phosphaalkene system.
A series of meta-terphenylphosphaalkenes with different groups (X-Dmp-P=CH-
Ph-X’, X = H, MeO, Me2N and X’ = H, CN, NO2) were made. Synthesis of pure phosphaalkenes with strong donor and acceptor groups were found to be synthetically challenging. The prepared materials were completely characterized by UV-vis absorption
129
spectroscopy, single crystal structures and electrochemical studies. The presence of charge polarizing groups on the less hindered side of the meta-terphenyl phosphaalkene’s found to possess a greater influence on the overall physico-chemical properties of the phosphaalkene, than the sterically hindered phosphorus side. The prepared materials were analyzed for NLO properties and the results found to be very weak or no significant NLO properties.
However, the efforts to synthesize and isolating the highly charge polarized phosphaalkenes with dimethylamino donor and NO2 or CN groups remained problematic due to the high reactivity of these molecules. A crude reaction product from the dimethylamino and cyano substituted compound was shown in figure 5.2.
N P CN
Figure 5.2. NMR (31P, 1H) of the crude dimethylamino and cyano substituted phosphaalkene
130
In addition to the phosphaalkenes with different substituents, also a new methoxy substituted meta-terphenyl diphosphene has been made (MeO-Dmp-P=P-Dmp-MeO) by the reduction of MeODmpPCl2 with Mg (chart 5.1).
Mg, Sonication O O O P PCl2 P THF, 10 min
3.6b 5.1 Chart 5.1. Synthesis of methoxy substituted meta-terphenyl diphosphene
Figure 5.3. 1H and 31P{1H} NMR of methoxy substituted meta-terphenyl diphosphene
131
The synthesized diphosphene has been structurally characterized by NMR (figure
5.2) and single crystal X-ray crystallography (figure 5.3). Interestingly, the structural aspects were very much similar to the earlier reported unsubstituted disphosphene, the only difference exist in the torsional angle and that too very minimal.
Bondlength(Å) C1-P1 1.841 (4)
P1-P2 2.033 (4) Bond angle(°) C1-P1-P2 97.62 (8)
C25-P1-P2 109.32(8)
Figure 5.4. Single crystal structure of methoxy substituted diphosphene
Synthesis of 5.1. In a 10 mL flask, 0.100 g (0.23 mmol) of 3.6b and 0.006 g (0.24 mmol) of magnesium metal was taken into 5 mL of dry THF. The resulting solution was sonicated for 10 minutes. A dark orange colored solution was observed and it was taken into the glove box for work up. The solvent from the dark orange colored solution was removed under vacuum leaving an organge colored solid at the bottom. The orange colored material was dissolved into 10 mL of pentanes and filtered through a glass frit using celite bed. Then from the filtrate, the solvent was removed under vacuum leaving
0.053 g (66 %) of the pure product 5.1, as a dark orange colored solid. X-ray quality crystals were grown from a concentrated solution in diethyl ether at -35 °C. 1H NMR
132
31 1 (CDCl3): δ 6.71 (s, 8H), 6.49 (s, 4H), 3.71 (s, 6H), 2.30 (s, 12H), 1.67 (s, 24H). P{ H}
NMR (CDCl3): δ 489.4.
5.3. Synthesis and Studies of 2,6-Diaryl-Benzo-bis(oxaphospholes)
Two new class of compounds, 2,6-diaryl-benzo-bis(oxaphospholes) was
successfully synthesized and characterized. The synthesis was accomplished through
cyclocondensation reaction of 2,5-diphosphinohydroquinone and N-
arylimidoylchlorides. These compounds found to have a characteristic chemical shift near
80-90 ppm in 31P NMR which is similar to mono benzo(1,3-oxaphospholes). Initial
attempts of synthesizing simple phenyl systems lead to issues related to isolation and
charcterization. Therefore, the compounds with para position and ortho positions were
utilized to optimize the reaction. It was observed that the ortho substituted compounds,
namely mesityl and m-xylyl based compounds gave clean products. These benzo-
bis(oxaphospholes) found to be high melting solids. The prepared materials were
characterized by NMR, UV-vis, fluorescence and electrochemical studies.
In addition to the above mentioned compounds, various efforts were also directed
to make benzo-bis(oxaphosphole) polymers of the type shown in chart 5.2.
G G Cl N P O H2P OH n N Cl O P HO PH2 G G
G=H,OHex,OC8H17 Chart 5.2. Benzo-bis(oxaphosphole) polymer synthesis.
133
But unfortunately, the polymer synthesis was unable to accomplish. Since the synthesis was attempted through step wise polymerization route, the resulting products were most of the time are a mixture of small oligomers and had solubility issues. Therefore the polymer synthesis may require a much highly efficient route or further optimization of reactions to form polymers.
Therefore, through these studies, new class of benzo-bisoxaphospholes were synthesized and characterized by NMR, mass spec and UV-vis techniques. With this synthetic advantage new benzo-bis(oxaphosphole) monomers can be synthesized, through which interesting polymers featuring benzo-bis(oxaphospholes) units can be accomplished. Bis- benzoxaphospholes being largely unstudied class of compounds these molecules could be very interesting candidates for further studies and investigations. Thereby, to develop more advanced conjugated organophosphorus materials.
134
Appendix
Selected 1H, 13C{1H} and 31P{1H} NMR data
and
X-ray crystallography data
1 31 1 2.N.1. H NMR and P{ H} NMR of (CDCl3) 2.4
135
1 31 1 2.N.2. H NMR and P{ H} NMR of (CDCl3) 2.6a
136
1 31 1 2.N.3. H NMR and P{ H} NMR of (CDCl3) 2.7a
137
1 31 1 2.N.4. H NMR and P{ H} NMR of (CDCl3) 2.8a
138
1 31 1 2.N.5. H NMR and P{ H} NMR of (CDCl3) 2.8b
139
1 13 1 3.N.1.P HP NMR and P C{P P H}P NMR of (CDClR3R) 3.1
140
1 13 1 3.N.2. P HP NMR and P C{P P H}P NMR of (CDClR3R) 3.2
141
1 13 1 3.N.3.P HP NMR and P C{P P H}P NMR of (CDClR3R) 3.3
142
1 13 1 3.N.4.P HP NMR and P C{P P H}P NMR of (CDClR3R) 3.4
143
1 13 1 3.N.5.P HP NMR and P C{P P H}P NMR of (CDClR3R) 3.5a
144
1 31 1 3.N.6.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.6a
145
1 13 1 3.N.7.P HP NMR and P CP {P H}P NMR of (CDClR3R) 3.5b
146
1 31 1 3.N.8.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.6b
147
1 31 1 3.N.9.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.9
148
1 31 1 3.N.10.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.10 149
1 31 1 3.N.11.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.11
150
1 31 1 3.N.12.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.12
151
1 31 1 3.N.13.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.13
152
1 31 1 3.N.14.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.14
153
1 31 1 3.N.15.P HP NMR and P P{P P H}P NMR of (CDClR3R) 3.15
154
1 31 1 4.N.1. H NMR and P{ H} NMR of (CDCl3) 4.12
155
1 31 1 4.N.2. H NMR and P{ H} NMR of (CD3OD) 4.16
156
1 31 1 4.N.3. H NMR and P{ H} NMR of (CDCl3) 4.21
157
1 31 1 4.N.6. H NMR and P{ H} NMR of (CDCl3) of 4.40
158
1 31 1 4.N.7. H NMR and P{ H} NMR of (CDCl3) of 4.41
159
APPENDIX – Crystal Structure Determination and Data
Table A.1.Crystal data and structure refinement for 2.8a
Br
P
Br
Crystal structure of 2.8a
Compound 2.8a
Empirical formula C31H29Br2P
Formula weight (g/mol) 592.33
Temperature (°K) 100(2)
Wavelength (Å) 0.71073
160
Crystal system Orthorhombic
Space group Fdd2
Unit cell dimensions a = 25.9240(17) Å
b = 32.412(2) Å
c = 14.4521(2) Å
α = 90°
β = 90°
γ =90°
Volume (Å)3 11143.1(13)
Z 16
Density calculated (Mg/m3) 1.412
Absorption Coefficient (mm-1) 2.984
F(000) 4800
Crystal size (mm) 0.30 x 0.30 x 0.20
Crystal color/shape pale yellow block
θ-range 1.84-27.50°
Limiting indices -28 < h < 33
-41 < k < 29
-15 < l < 16
Reflections collected 12,813
Independent reflections 5898 (Rint = 0.0324)
Refinement method full-matrix least-squares on F2
161
Data/restraint/params 5384/0/307
Goodness-of-fit on F2 0.990
Final R indices [ I > 2σ(I)] R1 = 0.0326
wR2 = 0.0745
R indices (all data) R1 = 0.0366
wR2 = 0.0758
Table A.2. Bond lengths [Å] for 2.8a.
C7-C8 1.397(4) Br1-C4 1.895(3) C7-C12 1.412(4) Br2-C29 1.910(3) C8-C9 1.383(4) P1-C1 1.842(3) C8-C13 1.507(4) P1-C25 1.683(3) C9-H9A 0.949(3) C1-C2 1.403(4) C9-C10 1.384(5) C1-C6 1.399(4) C10-C11 1.378(5) C2-C3 1.389(4) C10-C14 1.537(5) C2-C7 1.501(4) C11-H11A 0.951(3) C3-H3A 0.951(3) C11-C12 1.388(5) C3-C4 1.370(4) C12-C15 1.510(5) C4-C5 1.386(4) C13-H13A 0.981(3) C5-H5A 0.950(3) C13-H13B 0.980(3) C5-C6 1.409(4) C13-H13C 0.979(3) C6-C16 1.505(4)
162
C14-H14A 0.981(4) C22-H22C 0.981(3)
C14-H14B 0.981(4) C23-H23A 0.980(4)
C14-H14C 0.981(4) C23-H23B 0.981(4)
C15-H15A 0.980(4) C23-H23C 0.980(4)
C15-H15B 0.980(4) C24-H24A 0.981(4)
C15-H15C 0.978(4) C24-H24B 0.981(4)
C16-C17 1.394(4) C24-H24C 0.980(4)
C16-C21 1.405(4) C25-H25A 0.950(3)
C17-C18 1.402(4) C25-C26 1.453(4)
C17-C22 1.505(4) C26-C27 1.406(4)
C18-H18A 0.949(3) C26-C31 1.395(4)
C18-19 1.391(4) C27-H27A 0.949(3)
C19-C20 1.383(4) C27-C28 1.386(4)
C19-C23 1.506(5) C28-H28A 0.950(3)
C20-H20A 0.951(3) C28-C29 1.374(5)
C20-C21 1.390(4) C29-C30 1.372(4)
C21-C24 1.499(5) C30-H30A 0.949(3)
C22-H22A 0.979(3) C30-C31 1.381(4)
C22-H22B 0.980(3) C31-H31A 0.949(3)
163
Table A.3. Bond angles [°] for 2.8a
C2-C7-C12 120.2(3)
C1-P1-C25 101.6(1) C8-C7-C12 119.4(3)
P1-C1-C2 116.8(2) C7-C8-C9 119.4(3)
P1-C1-C6 123.5(2) C7-C8-C13 120.0(3)
C2-C1-C6 119.6(3) C9-C8-C13 120.5(3)
C1-C2-C3 120.2(3) C8-C9-H9A 119.1(3)
C1-C2-C7 119.9(2) C8-C9-C10 121.7(3)
C3-C2-C7 119.9(2) H9A-C9-C10 119.2(3)
C2-C3-H3A 120.2(3) C9-C10-C11 118.8(3)
C2-C3-C4 119.6(3) C9-C10-C14 120.6(3)
H3A-C3-C4 120.2(3) C11-C10-C14 120.6(3)
Br1-C4-C3 120.1(2) C10-C11-H11A 119.3(3)
Br1-C4-C5 118.0(2) C10-C11-C12 121.5(3)
C3-C4-C5 121.9(3) H11A-C11-C12 119.2(3)
C4-C5-H5A 120.6(3) C7-C12-C11 119.2(3)
C4-C5-C6 118.9(3) C7-C12-C15 120.3(3)
H5A-C5-C6 120.5(3) C11-C12-C15 120.5(3)
C1-C6-C5 119.7(3) C8-C13-H13A 109.5(3)
C1-C6-C16 123.5(2) C8-C13-H13B 109.5(3)
C5-C6-C16 116.7(2) C8-C13-H13C 109.5(3)
C2-C7-C8 120.4(3) H13A-C13-H13B 109.4(3)
164
H13A-C13-H13C 109.4(3) H18A-C18-C19 119.4(3)
H13B-C13-H13C 109.4(3) C18-C19-C20 118.5(3)
C10-C14-H14A 109.4(3) C18-C19-C23 120.4(3)
C10-C14-H14B 109.4(3) C20-C19-C23 121.1(3)
C10-C14-H14C 109.5(3) C19-C20-H20A 118.9(3)
H14A-C14-H14B 109.6(4) C19-C20-C21 122.4(3)
H14A-C14-H14C 109.5(4) H20A-C20-C21 118.8(3)
H14B-C14-H14C 109.4(4) C16-C21-C20 118.3(3)
C12-C15-H15A 109.4(3) C16-C16-C24 122.3(3)
C12-C15-H15B 109.5(3) C20-C21-C24 119.4(3)
C12-C15-H15C 109.5(3) C17-C22-H22A 109.5(3)
H15A-C15-H15B 109.3(3) C17-C22-H22B 109.4(3)
H15A-C15-H15C 109.5(3) C17-C22-H22C 109.4(3)
H15B-C15-H15C 109.6(3) H22A-C22-H22B 109.6(3)
C6-C16-C17 119.2(2) H22A-C22-H22C 109.4(3)
C6-C16-C21 120.0(2) H22B-C22-H22C 109.5(3)
C17-C16-C21 120.6(3) C19-C23-H23A 109.5(3)
C16-C17-C18 119.1(3) C19-C23-H23B 109.5(3)
C16-C17-C22 122.1(3) C19-C23-H23C 109.5(3)
C18-C17-C22 118.8(2) H23A-C23-H23B 109.4(4)
C17-C18-H18A 119.4(3) H23A-C23-H23C 109.4(4)
C17-C18-C19 121.1(3) H23B-C23-H23C 109.4(4)
165
C21-H24-H24A 109.5(3) C29-C30-C31 119.3(3)
C21-C24-H24B 109.5(3) H30A-C30-C31 120.4(3)
C21-C24-H24C 109.4(3) C26-C31-C30 121.2(3)
H24A-C24-H24B 109.3(3) C26-C31-H31A 119.4(3)
H24A-C24-H24C 109.5(3) C30-C31-H31A 119.4(3)
H24B-C24-H24C 109.6(3)
P1-C25-H25A 117.7(2)
P1-C25-C6 124.5(2)
H25A-C25-C26 117.8(3)
C25-C26-C27 119.4(3)
C25-C26-C31 123.1(3)
C27-C26-C31 117.4(3)
C26-C27-H27A 119.2(3)
C26-C27-C28 121.6(3)
H27A-C27-C28 119.2(3)
C27-C28-H28A 120.7(3)
C27-C28-C29 118.3(3)
H28A-C28-C29 120.9(3)
Br2-C29-C28 119.0(2)
Br2-C29-C30 118.9(2)
C28-C29-C30 122.0(3)
C29-C30-H30A 120.3(3)
166
Table A.4. Torsion angles [°] for 2.8a.
C25-P1-C1-C2 -120.4(2) C2-C3-C4-C5 -0.6(4)
C25-P1-C1-C6 63.2(3) H3A-C3-C4-Br1 -1.3(4)
C1-P1-C25-H25A 2.0(3) H3A-C3-C4-C5 179.4(3)
C1-P1-C25-C26 -178.0(2) Br1-C4-C5-H5A 0.3(4)
P1-C1-C2-C3 179.7(2) Br1-C4-C5-C6 -179.7(2)
P1-C1-C2-C7 1.8(3) C3-C4-C5-H5A 179.6(3)
C6-C1-C2-C3 -3.7(4) C3-C4-C5-C6 -0.4(4)
C6-C1-C2-C7 178.3(3) C4-C5-C6-C1 -0.7(4)
P1-C1- C6-C5 179.0(2) C4-C5-C6-C16 177.5(3)
P1-C1- C6-C16 0.9(4) H5A-C5-C6-C1 179.3(3)
C2-C1-C6-C5 2.7(4) H5A-C5-C6-C16 -2.5(4)
C2-C1-C6-C16 -175.4(3) C1-C6-C16-C17 76.4(4)
C1-C2-C3-H3A -177.3(3) C1-C6-C16-C21 -108.8(3)
C1-C2-C3-C4 2.6(4) C5-C6-C16-C17 -101.8(3)
C7-C2-C3-H3A 0.6(4) C5-C6-C16-C21 73.0(4)
C7-C2-C3-C4 -179.4(3) C2-C7-C8-C9 -179.9(3)
C1-C2-C7-C8 88.9(3) C2-C7-C8-C13 -1.6(4)
C1-C2-C7-C12 -91.1(3) C12-C7-C8-C9 0.1(4)
C3-C2-C7-C8 -89.1(3) C12-C7-C8-C13 178.4(3)
C3-C2-C7-C12 90.9(3) C2-C7-C12-C11 179.0(3)
C2-C3-C4-Br1 178.7(2) C2-C7-C12-C15 -0.5(4)
167
C8-C7-C12-C11 -1.0(4) C9-C10-C14-H14C -61.2(5)
C8-C7-C12-C15 179.5(3) C11-C10-C14-H14A -2.4(5)
C7-C8-C9-H9A -179.0(3) C11-C10-C14-H14B -122.5(4)
C7-C8-C9-C10 1.0(5) C11-C10-C14-H14C 117.6(4)
C13-C8-C9-H9A 2.7(5) C10-C11-C12-C7 0.9(5)
C13-C8-C9-C10 -177.3(3) C10-C11-C12-C15 -179.6(3)
C7-C8-C13-H13A 180.0(3) H11A-C11-C12-C7 -179.1(3)
C7-C8-C13-H13B 60.0(4) H11A-C11-C12-C15 0.4(5)
C7-C8-C13-H13C -60.0(4) C7-C12-C15-H15A -1.1(5)
C9-C8-C13-H13A -1.8(4) C7-C12-C15-H15B -120.9(3)
C9-C8-C13-H13B -121.8(3) C7-C12-C15-H15C 118.9(3)
C9-C8-C13-H13C 118.2(3) C11-C12-C15-H15A 179.4(3)
C8-C9-C10-C11 -1.1(5) C11-C12-C15-H15B 59.6(4)
C8-C9-C10-C14 177.8(3) C11-C12-C15-H15C -60.5(4)
H9A-C9-C10-C11 178.9(3) C6-C16-C17-C18 175.4(3)
H9A-C9-C10-C14 -2.2(5) C6-C16-C17-C22 -4.4(4)
C9-C10-C11-H11A -179.9(3) C21-C16-C17-C18 0.6(4)
C9-C10-C11-C12 0.1(5) C21-C16-C17-C22 -179.2(3)
C14-C10-C11-H11A 1.2(5) C6-C16-C21-C20 -176.7(3)
C14-C10-C11-C12 -178.7(3) C6-C16-C21-C24 3.0(4)
C9-C10-C14-H14A 178.7(3) C17-C16-C21-C20 -2.0(4)
C9-C10-C14-H14B 58.6(5) C17-C16-C21-C24 177.8(3)
168
C16-C17-C18-H18A 179.6(3) C20-C19-C23-H23B -121.0(4)
C16-C17-C18-C19 -0.4(4) C20-C19-C23-H23C 119.0(4)
C22-C17-C18-H18A -0.5(4) C19-C20-C21-C16 3.2(4)
C22-C17-C18-C19 179.5(3) C19-C20-C21-C24 -176.5(3)
C16-C17-C22-H22A -179.7(3) H20A-C20-C21-C16 -176.8(3)
C16-C17-C22-H22B 60.2(4) H20A-C20-C21-C24 3.5(5)
C16-C17-C22-H22C -59.8(4) C16-C21-C24-H24A 2.1(5)
C18-C17-C22-H22A 0.5(4) C16-C21-C24-H24B -117.8(3)
C18-C17-C22-H22B -119.6(3) C16-C21-C24-H24C 122.1(3)
C18-C17-C22-H22C 120.4(3) C20-C21-C24-H24A -178.2(3)
C17-C18-C19-C20 1.5(4) C20-C21-C24-H24B 61.9(4)
C17-C18-C19-C23 -179.8(3) C20-C21-C24-H24C -58.2(4)
H18A-C18-C19-C20 -178.5(3) P1-C25-C26-C27 162.2(2)
H18A-C18-C19-C23 0.2(5) P1-C25-C26-C31 -15.3(4)
C18-C19-C20-H20A 177.0(3) H25A-C25-C26-C27 -17.8(4)
C18-C19-C20-C21 -3.0(4) H25A-C25-C26-C31 164.7(3)
C23-C19-C20-H20A -1.6(5) C25-C26-C27-H27A 4.1(5)
C23-C19-C20-C21 178.4(3) C25-C26-C27-C28 -175.9(3)
C18-C19-C23-H23A -179.6(3) C31-C26-C27-H27A -178.3(3)
C18-C19-C23-H23B 60.4(4) C31-C26-C27-C28 1.7(4)
C18-C19-C23-H23C -59.6(4) C25-C26-C31-C30 174.7(3)
C20-C19-C23-H23A -1.0(5) C25-C26-C31-H31A -5.2(5)
169
C27-C26-C31-C30 -2.8(4)
C27-C26-C31-H31A 177.2(3)
C26-C27-C28-H28A -179.5(3)
C26-C27-C28-C29 0.5(5)
H27A-C27-C28-H28A 0.5(5)
H27A-C27-C28-C29 -179.5(3)
C27-C28-C29-Br2 178.0(2)
C27-C28-C29-C30 -1.7(5)
H28A-C28-C29-Br2 -2.1(5)
H28A-C28-C29-C30 178.3(3)
Br2-C29-C30-H30A 1.0(4)
Br2-C29-C30-C31 -179.0(2)
C28-C29-C30-H30A -179.4(3)
C28-C29-C30-C31 0.6(5)
C29-C30-C31-C26 1.7(5)
C29-C30-C31-H31A -178.3(3)
H30A-C30-C31-C26 -178.3(3)
H30A-C30-C31-H31A 1.7(5)
170
Table B.1. Crystal data and structure refinement for 2.8 b
Br
P
Br
Crystal structure of 2.8b
Compound 2.8b
Empirical formula C31H29Br2P
Formula weight (g/mol) 592.33
Temperature (°K) 100(2)
Wavelength (Å) 0.71073
Crystal system Monoclinic
Space group P21/c
171
a = 17.8482(16) Å Unit cell dimensions b = 9.6996(9) Å
c = 16.4619(14) Å
α = 90°
β = 111.3850(10)°
γ = 90°
Volume (Å)3 2653.7(4)
Z 4
Density calculated (Mg/m3) 1.483
Absorption Coefficient (mm-1) 3.133
F(000) 1200
Crystal size (mm) 0.25 x 0.20 x 0.15
Crystal color/shape pale yellow block
θ-range 1.23-27.53°
Limiting indices -23 < h < 22
-12 < k < 12
-20 < l < 21
Reflections collected 22,059
Independent reflections 6000 (Rint = 0.0452)
Refinement method full-matrix least-squares on F2
Data/restraint/params 4757/0/307
Goodness-of-fit on F2 1.028
Final R indices [ I > 2σ(I)] R1 = 0.0395
wR2 = 0.1001
172
R indices (all data) R1 = 0.0550
wR2 = 0.1076
Table B.2. Bond lengths [Å] for 2.8b.
C9-H9A 0.950(3) Br1-C4 1.899(3) C9-C10 1.390(6) Br2-C29 1.904(4) C10-C11 1.382(5) P1-C1 1.838(3) C10-C14 1.510(4) P1-C25 1.666(4) C11-H11A 0.949(4) C1-C2 1.400(4) C11-C12 1.391(4) C1-C6 1.417(4) C12-C15 1.503(5) C2-C3 1.406(4) C13-H13A 0.981(3) C2-C7 1.508(4) C13-H13B 0.980(4) C3-H3A 0.949(3) C13-H13C 0.981(4) C3-C4 1.384(4) C14-H14A 0.981(4) C4-C5 1.385(4) C14-H14B 0.980(4) C5-H5A 0.950(3) C14-H14C 0.980(4) C5-C6 1.397(4) C15-H15A 0.981(4) C6-C16 1.503(4) C15-H15B 0.980(3) C7-C8 1.395(4) C15-H15C 0.980(4) C7-C12 1.406(5) C16-C17 1.407(5) C8-C9 1.388(4) C16-C21 1.409(5) C8-C13 1.515(6)
173
C17-C18 1.392(4) C27-H27A 0.950(3)
C17-C22 1.509(5) C27-C28 1.385(5)
C18-H18A 0.949(3) C28-H28A 0.950(4)
C18-C19 1.393(5) C28-C29 1.375(5)
C19-C20 1.384(5) C29-C30 1.388(4)
C19-C23 1.508(4) C30-H30A 0.949(3)
C20-H20A 0.950(4) C30-C31 1.382(5)
C20-C21 1.396(4) C31-H31A 0.950(3)
C21-C24 1.504(5)
C22-H22A 0.980(3)
C22-H22B 0.980(3)
C22-H22C 0.980(3)
C23-H23A 0.982(4)
C23-H23B 0.979(3)
C23-H23C 0.979(4)
C24-H24A 0.981(3)
C24-H24B 0.980(4)
C24-H24C 0.980(3)
C25-H25A 0.951(3)
C25-C26 1.465(5)
C26-C27 1.396(5)
C26-C31 1.394(4)
174
Table B.3. Bond angles [°] for 2.8b
C1-P1-C25 107.3(1) C8-C7-C12 119.9(3)
P1-C1-C2 116.0(2) C7-C8-C9 119.5(3)
P1-C1-C6 123.7(2) C7-C8-C13 120.8(3)
C2-C1-C6 119.9(3) C9-C8-C13 119.7(3)
C1-C2-C3 120.4(3) C8-C9-H9A 119.3(3)
C1-C2-C7 122.8(3) C8-C9-C10 121.6(3)
C3-C2-C7 116.6(3) H9A-C9-C10 119.1(3)
C2-C3-H3A 120.6(3) C9-C10-C11 118.0(3)
C2-C3-C4 118.7(3) C9-C10-C14 121.1(3)
H3A-C3-C4 120.6(3) C11-C10-C14 120.9(3)
Br1-C4-C3 119.0(2) C10-C11-H11A 118.8(3)
Br1-C4-C5 119.4(2) C10-C11-C12 122.4(3)
C3-C4-C5 121.5(3) H11A-C11-C12 118.7(3)
C4-C5-H5A 119.7(3) C7-C12-C11 118.6(3)
C4-C5-C6 120.7(3) C7-C12-C15 121.9(3)
H5A-C5-C6 119.6(3) C11-C12-C15 119.5(3)
C1-C6-C5 118.5(3) C8-C13-H13A 109.5(3)
C1-C6-C16 123.6(3) C8-C13-H13B 109.5(3)
C5-C6-C16 117.7(3) C8-C13-H13C 109.5(3)
C2-C7-C8 122.4(3) H13A-C13-H13B 109.5(3)
C2-C7-C12 117.5(3) H13A-C13-H13C 109.4(3)
175
H13B-C13-H13C 109.4(3) C18-C19-C20 117.8(3)
C10-C14-H14A 109.5(3) C18-C19-C23 120.3(3)
C10-C14-H14B 109.5(3) C20-C19-C23 121.9(3)
C10-C14-H14C 109.5(3) C19-C20-H20A 118.9(3)
H14A-C14-H14B 109.4(3) C19-C20-C21 122.2(3)
H14A-C14-H14C 109.5(3) H20A-C20-C21 118.9(3)
H14B-C14-H14C 109.4(3) C16-C21-C20 119.2(3)
C12-C15-H15A 109.5(3) C16-C16-C24 123.2(3)
C12-C15-H15B 109.5(3) C20-C21-C24 117.6(3)
C12-C15-H15C 109.5(3) C17-C22-H22A 109.4(3)
H15A-C15-H15B 109.5(3) C17-C22-H22B 109.5(3)
H15A-C15-H15C 109.4(3) C17-C22-H22C 109.5(3)
H15B-C15-H15C 109.5(3) H22A-C22-H22B 109.4(3)
C6-C16-C17 119.8(3) H22A-C22-H22C 109.5(3)
C6-C16-C21 120.8(3) H22B-C22-H22C 109.5(3)
C17-C16-C21 119.3(3) C19-C23-H23A 109.4(3)
C16-C17-C18 119.3(3) C19-C23-H23B 109.5(3)
C16-C17-C22 122.5(3) C19-C23-H23C 109.6(3)
C18-C17-C22 118.0(3) H23A-C23-H23B 109.4(3)
C17-C18-H18A 119.0(3) H23A-C23-H23C 109.4(3)
C17-C18-C19 122.1(3) H23B-C23-H23C 109.5(3)
H18A-C18-C19 118.9(3) C21-H24-H24A 109.4(3)
176
C21-C24-H24B 109.5(3) H27A-C27-C28 119.2(3)
C21-C24-H24C 109.5(3) C27-C28-H28A 120.6(3)
H24A-C24-H24B 109.4(3) C27-C28-C29 118.7(3)
H24A-C24-H24C 109.4(3) H28A-C28-C29 120.7(3)
H24B-C24-H24C 109.5(3) Br2-C29-C28 119.5(2)
P1-C25-H25A 111.8(3) Br2-C29-C30 118.7(2)
P1-C25-C6 136.3(2) C28-C29-C30 121.7(3)
H25A-C25-C26 111.9(3) C29-C30-H30A 120.7(3)
C25-C26-C27 118.9(3) C29-C30-C31 118.6(3)
C25-C26-C31 123.2(3) H30A-C30-C31 120.7(3)
C27-C26-C31 117.8(3) C26-C31-C30 121.6(3)
C26-C27-H27A 119.2(3) C26-C31-H31A 119.2(3)
C26-C27-C28 121.7(3) C30-C31-H31A 119.2(3)
177
Table B.3. Torsion angles [°] for 2.8b.
C25-P1-C1-C2 124.8(2) C2-C3-C4-C5 -1.5(5)
C25-P1-C1-C6 -63.3(3) H3A-C3-C4-Br1 2.3(4)
C1-P1-C25-H25A 175.9(2) H3A-C3-C4-C5 178.6(3)
C1-P1-C25-C26 -4.1(4) Br1-C4-C5-H5A -2.1(4)
P1-C1-C2-C3 178.2(2) Br1-C4-C5-C6 178.0(2)
P1-C1-C2-C7 3.6(4) C3-C4-C5-H5A -178.3(3)
C6-C1-C2-C3 5.9(5) C3-C4-C5-C6 1.7(5)
C6-C1-C2-C7 -168.7(3) C4-C5-C6-C1 1.9(4)
P1-C1- C6-C5 -177.3(2) C4-C5-C6-C16 -172.8(3)
P1-C1- C6-C16 -3.0(4) H5A-C5-C6-C1 -178.1(3)
C2-C1-C6-C5 -5.7(4) H5A-C5-C6-C16 7.2(5)
C2-C1-C6-C16 168.7(3) C1-C6-C16-C17 -62.3(4)
C1-C2-C3-H3A 177.6(3) C1-C6-C16-C21 122.2(3)
C1-C2-C3-C4 -2.3(5) C5-C6-C16-C17 112.1(3)
C7-C2-C3-H3A -7.5(5) C5-C6-C16-C21 -63.4(4)
C7-C2-C3-C4 172.6(3) C2-C7-C8-C9 -173.3(3)
C1-C2-C7-C8 -100.6(4) C2-C7-C8-C13 7.1(5)
C1-C2-C7-C12 85.1(4) C12-C7-C8-C9 0.9(5)
C3-C2-C7-C8 84.6(4) C12-C7-C8-C13 -178.7(3)
C3-C2-C7-C12 -89.8(4) C2-C7-C12-C11 172.9(3)
C2-C3-C4-Br1 -177.8(2) C2-C7-C12-C15 -8.9(5)
178
C8-C7-C12-C11 -1.6(5) C9-C10-C14-H14C -62.6(4)
C8-C7-C12-C15 176.6(3) C11-C10-C14-H14A -4.1(5)
C7-C8-C9-H9A -179.5(3) C11-C10-C14-H14B -124.1(4)
C7-C8-C9-C10 0.5(5) C11-C10-C14-H14C 116.0(4)
C13-C8-C9-H9A 0.2(5) C10-C11-C12-C7 0.9(5)
C13-C8-C9-C10 -179.8(3) C10-C11-C12-C15 -177.4(3)
C7-C8-C13-H13A -0.1(5) H11A-C11-C12-C7 -179.0(3)
C7-C8-C13-H13B -120.1(3) H11A-C11-C12-C15 2.7(5)
C7-C8-C13-H13C 119.9(3) C7-C12-C15-H15A 177.9(3)
C9-C8-C13-H13A -179.7(3) C7-C12-C15-H15B 57.9(4)
C9-C8-C13-H13B 60.3(4) C7-C12-C15-H15C -62.2(4)
C9-C8-C13-H13C -59.8(4) C11-C12-C15-H15A -3.9(5)
C8-C9-C10-C11 -1.3(5) C11-C12-C15-H15B -123.9(3)
C8-C9-C10-C14 177.3(3) C11-C12-C15-H15C 116.0(4)
H9A-C9-C10-C11 178.7(3) C6-C16-C17-C18 -178.6(3)
H9A-C9-C10-C14 -2.7(5) C6-C16-C17-C22 -2.3(4)
C9-C10-C11-H11A -179.5(3) C21-C16-C17-C18 -3.1(4)
C9-C10-C11-C12 0.5(5) C21-C16-C17-C22 173.3(3)
C14-C10-C11-H11A 1.9(5) C6-C16-C21-C20 178.7(3)
C14-C10-C11-C12 -178.0(3) C6-C16-C21-C24 1.2(5)
C9-C10-C14-H14A 177.4(3) C17-C16-C21-C20 3.1(5)
C9-C10-C14-H14B 57.4(4) C17-C16-C21-C24 -174.3(3)
179
C16-C17-C18-H18A -179.3(3) C20-C19-C23-H23B 55.3(4)
C16-C17-C18-C19 0.6(5) C20-C19-C23-H23C -64.9(4)
C22-C17-C18-H18A 4.1(5) C19-C20-C21-C16 -0.8(5)
C22-C17-C18-C19 -175.9(3) C19-C20-C21-C24 176.8(3)
C16-C17-C22-H22A 4.0(4) H20A-C20-C21-C16 179.2(3)
C16-C17-C22-H22B -115.9(3) H20A-C20-C21-C24 -3.3(5)
C16-C17-C22-H22C 124.1(3) C16-C21-C24-H24A 0.5(5)
C18-C17-C22-H22A -179.6(3) C16-C21-C24-H24B -119.5(3)
C18-C17-C22-H22B 60.5(4) C16-C21-C24-H24C 120.5(3)
C18-C17-C22-H22C -59.5(4) C20-C21-C24-H24A -177.0(3)
C17-C18-C19-C20 1.7(5) C20-C21-C24-H24B 63.1(4)
C17-C18-C19-C23 -180.0(3) C20-C21-C24-H24C -57.0(4)
H18A-C18-C19-C20 -178.3(3) P1-C25-C26-C27 142.7(3)
H18A-C18-C19-C23 -0.0(5) P1-C25-C26-C31 -40.6(5)
C18-C19-C20-H20A 178.4(3) H25A-C25-C26-C27 -37.4(4)
C18-C19-C20-C21 -1.7(5) H25A-C25-C26-C31 139.4(3)
C23-C19-C20-H20A 0.2(5) C25-C26-C27-H27A -1.4(5)
C23-C19-C20-C21 -179.9(3) C25-C26-C27-C28 178.7(3)
C18-C19-C23-H23A -3.0(5) C31-C26-C27-H27A -178.3(3)
C18-C19-C23-H23B -122.9(3) C31-C26-C27-C28 1.8(5)
C18-C19-C23-H23C 116.9(3) C25-C26-C31-C30 -177.1(3)
C20-C19-C23-H23A 175.1(3) C25-C26-C31-H31A 2.9(5)
180
C27-C26-C31-C30 -0.4(5)
C27-C26-C31-H31A 179.7(3)
C26-C27-C28-H28A 178.5(3)
C26-C27-C28-C29 -1.5(5)
H27A-C27-C28-H28A -1.4(6)
H27A-C27-C28-C29 178.6(3)
C27-C28-C29-Br2 179.1(3)
C27-C28-C29-C30 -0.3(5)
H28A-C28-C29-Br2 -0.9(5)
H28A-C28-C29-C30 179.7(3)
Br2-C29-C30-H30A 2.4(5)
Br2-C29-C30-C31 -177.7(2)
C28-C29-C30-H30A -178.3(3)
C28-C29-C30-C31 1.7(5)
C29-C30-C31-C26 -1.3(5)
C29-C30-C31-H31A 178.7(3)
H30A-C30-C31-C26 178.6(3)
H30A-C30-C31-H31A -1.4(5)
181
Table C.1.Crystal data and structure refinement for 3.8
P
Crystal structure of 3.8
NO2 Compound 3.8
Empirical formula C31H30 NO2P
Formula weight (g/mol) 479.53
Temperature (°K) 100(2)
Wavelength (Å) 0.71073
Crystal system Monoclinic
Space group P2(1)/c
Unit cell dimensions a = 23.2380(6) Å
b = 8.2716(2) Å 183
c = 13.8440(4) Å
α = 90°
β = 101.539(2) °
γ = 90 °
Volume (Å)3 2607.25(12)
Z 4
Density calculated (Mg/m3) 1.222
Absorption Coefficient (mm-1) 0.133
F(000) 1016
Crystal size (mm) 0.26 x 0.12 x 0.07
θ-range 0.89 to 26.00°
Limiting indices -28<=h<=28
-10<=k<=9
-15<=l<=17
Reflections collected 18803
Unique (Rint) 5124 (Rint = 0.0451)
Completeness to θ 26.00, 100.0%
Absorption correction Multi-scan
Max & min transmission 0.9907 & 0.9661
Refinement method Full-matrix least-squares on F2
Data/restraint/parameters 5124 / 0 / 322
Goodness-of-fit on F2 1.049
184
Final R indices [ I > 2σ(I)] R1 = 0.0504
wR2 = 0.1234
R indices (all data) R1 = 0.0768
wR2 = 0.1449
Largest diff. peak and hole (Å-3) 0.857 and -0.322
Table C.2. Bond lengths [Å] for 3.8.
C(11)-C(10) 1.388(3)
P(1)-C(25) 1.657(2) C(8)-C(9) 1.398(3)
P(1)-C(1) 1.834(2) C(8)-C(13) 1.510(3)
C(2)-C(3) 1.391(3) C(10)-C(9) 1.388(3)
C(2)-C(1) 1.413(3) C(10)-C(14) 1.514(3)
C(2)-C(16) 1.497(3) C(19)-C(18) 1.388(3)
C(1)-C(6) 1.412(3) C(19)-C(20) 1.389(4)
C(3)-C(4) 1.377(3) C(19)-C(23) 1.505(4)
C(6)-C(5) 1.388(3) C(16)-C(17) 1.402(3)
C(6)-C(7) 1.500(3) C(16)-C(21) 1.406(3)
C(5)-C(4) 1.389(3) C(22)-C(17) 1.508(3)
C(7)-C(12) 1.404(3) C(21)-C(20) 1.387(3)
C(7)-C(8) 1.405(3) C(21)-C(24) 1.510(3)
C(12)-C(11) 1.394(3) C(17)-C(18) 1.387(3)
C(12)-C(15) 1.513(3) C(26)-C(27) 1.397(3)
185
C(26)-C(31) 1.408(3)
C(26)-C(25) 1.464(3)
C(31)-C(30) 1.382(3)
C(27)-C(28) 1.379(3)
C(30)-C(29) 1.386(3)
C(29)-C(28) 1.378(3)
C(29)-N(1) 1.463(3)
N(1)-O(2) 1.228(3)
N(1)-O(1) 1.233(3)
Table C.3. Bond angles [°] for 3.8 C(1)-C(6)-C(7) 122.97(19)
C(25)-P(1)-C(1) 105.53(11) C(6)-C(5)-C(4) 121.8(2)
C(3)-C(2)-C(1) 119.9(2) C(3)-C(4)-C(5) 119.5(2)
C(3)-C(2)-C(16) 120.3(2) C(12)-C(7)-C(8) 119.7(2)
C(1)-C(2)-C(16) 119.71(19) C(12)-C(7)-C(6) 119.8(2)
C(6)-C(1)-C(2) 119.3(2) C(8)-C(7)-C(6) 120.5(2)
C(6)-C(1)-P(1) 126.03(16) C(11)-C(12)-C(7) 119.0(2)
C(2)-C(1)-P(1) 114.32(17) C(11)-C(12)-C(15) 119.1(2)
C(4)-C(3)-C(2) 120.7(2) C(7)-C(12)-C(15) 121.9(2)
C(5)-C(6)-C(1) 118.7(2) C(10)-C(11)-C(12) 122.2(2)
C(5)-C(6)-C(7) 118.3(2) C(9)-C(8)-C(7) 119.0(2)
186
C(9)-C(8)-C(13) 119.7(2) C(18)-C(17)-C(22) 120.1(2)
C(7)-C(8)-C(13) 121.3(2) C(16)-C(17)-C(22) 120.5(2)
C(9)-C(10)-C(11) 117.9(2) C(17)-C(18)-C(19) 121.8(2)
C(9)-C(10)-C(14) 121.9(2) C(27)-C(26)-C(31) 118.3(2)
C(11)-C(10)-C(14) 120.3(2) C(27)-C(26)-C(25) 119.3(2)
C(10)-C(9)-C(8) 122.0(2) C(31)-C(26)-C(25) 122.3(2)
C(18)-C(19)-C(20) 118.0(2) C(30)-C(31)-C(26) 121.1(2)
C(18)-C(19)-C(23) 120.5(2) C(28)-C(27)-C(26) 121.1(2)
C(20)-C(19)-C(23) 121.5(2) C(31)-C(30)-C(29) 118.3(2)
C(17)-C(16)-C(21) 119.7(2) C(26)-C(25)-P(1) 123.80(18)
C(17)-C(16)-C(2) 119.8(2) C(28)-C(29)-C(30) 122.3(2)
C(21)-C(16)-C(2) 120.5(2) C(28)-C(29)-N(1) 118.7(2)
C(20)-C(21)-C(16) 119.0(2) C(30)-C(29)-N(1) 119.0(2)
C(20)-C(21)-C(24) 120.5(2) C(29)-C(28)-C(27) 118.9(2)
C(16)-C(21)-C(24) 120.5(2) O(2)-N(1)-O(1) 123.5(2)
C(21)-C(20)-C(19) 122.0(2) O(2)-N(1)-C(29) 118.5(2)
C(18)-C(17)-C(16) 119.3(2) O(1)-N(1)-C(29) 118.0(2)
Table C.4. Torsion angles [°] for 8
C25-P1-C1-C2 -142.8(2) C1-P1-C25-H25 5.2(2)
C25-P1-C1-C6 44.0(2) C3-C2-C1-P1 -174.9(2)
C1-P1-C25-C26 -174.9(2) C3-C2-C1-C6 -1.3(3)
187
C16-C2-C1-P1 4.0(3) C1-C6-C7-C12 73.3(3)
C16-C2-C1-C6 177.6(2) C1-C6-C7-C8 -107.3(3)
C1-C2-C3-H3 179.9(2) C5-C6-C7-C12 -103.9(3)
C1-C2-C3-C4 -0.1(4) C5-C6-C7-C8 75.5(3)
C16-C2-C3-H3 1.0(4) C6-C5-C4-C3 0.8(4)
C16-C2-C3-C4 -179.0(2) C6-C5-C4-H4 -179.2(2)
C1-C2-C16-C21 89.3(3) H5-C5-C4-C3 -179.2(2)
C1-C2-C16-C17 -88.3(3) H5-C5-C4-H4 0.8(4)
C3-C2-C16-C21 -91.8(3) C6-C7-C12-C11 -177.9(2)
C3-C2-C16-C17 90.7(3) C6-C7-C12-C15 2.0(3)
P1-C1-C6-C5 175.2(2) C8-C7-C12-C11 2.6(3)
P1-C1-C6-C7 -2.0(3) C8-C7-C12-C15 -177.4(2)
C2-C1-C6-C5 2.4(3) C6-C7-C8-C13 -1.7(3)
C2-C1-C6-C7 -174.8(2) C6-C7-C8-C9 177.0(2)
C2-C3-C4-C5 0.3(4) C12-C7-C8-C13 177.7(2)
C2-C3-C4-H4 -179.7(2) C12-C7-C8-C9 -3.6(3)
H3-C3-C4-C5 -179.7(2) C7-C12-C11-H11 -179.6(2)
H3-C3-C4-H4 0.4(4) C7-C12-C11-C10 0.5(4)
C1-C6-C5-H5 177.8(2) C15-C12-C11-H11 0.5(4)
C1-C6-C5-C4 -2.2(4) C15-C12-C11-C10 -179.4(2)
C7-C6-C5-H5 -4.8(4) C7-C12-C15-H15A 159.1(2)
C7-C6-C5-C4 175.2(2) C7-C12-C15-H15B 39.1(3)
188
C7-C12-C15-H15C -80.9(3) C11-C10-C14-H14A -21.0(3)
C11-C12-C15-H15A -21.0(3) C11-C10-C14-H14B -141.0(2)
C11-C12-C15-H15B -141.0(2) C11-C10-C14-H14C 98.9(3)
C11-C12-C15-H15C 99.0(3) C9-C10-C14-H14A 159.1(2)
C12-C11-C10-C9 -2.6(4) C9-C10-C14-H14B 39.1(3)
C12-C11-C10-C14 177.6(2) C9-C10-C14-H14C -80.9(3)
H11-C11-C10-C9 177.5(2) C23-C19-C20-C21 178.3(2)
H11-C11-C10-C14 -2.4(4) C23-C19-C20-H20 -1.6(4)
C7-C8-C13-H13A -70.4(3) C18-C19-C20-C21 -2.3(4)
C7-C8-C13-H13B 169.7(2) C18-C19-C20-H20 177.8(2)
C7-C8-C13-H13C 49.7(3) C20-C19-C23-H23A -83.1(3)
C9-C8-C13-H13A 110.9(3) C20-C19-C23-H23B 156.9(2)
C9-C8-C13-H13B -9.0(3) C20-C19-C23-H23C 36.9(4)
C9-C8-C13-H13C -129.0(2) C18-C19-C23-H23A 97.5(3)
C7-C8-C9-C10 1.4(4) C18-C19-C23-H23B -22.5(4)
C7-C8-C9-H9 -178.6(2) C18-C19-C23-H23C -142.5(3)
C13-C8-C9-C10 -179.8(2) C20-C19-C18-C17 0.9(4)
C13-C8-C9-H9 0.1(4) C20-C19-C18-H18 -179.0(2)
C11-C10-C9-C8 1.6(4) C23-C19-C18-C17 -179.6(2)
C11-C10-C9-H9 -178.3(2) C23-C19-C18-H18 0.4(4)
C14-C10-C9-C8 -178.6(2) C2-C16-C21-C20 -175.8(2)
C14-C10-C9-H9 1.5(4) C2-C16-C21-C24 3.1(3)
189
C17-C16-C21-C20 1.8(4) C16-C17-C18-C19 1.7(4)
C17-C16-C21-C24 -179.4(2) C16-C17-C18-H18 -178.3(2)
C2-C16-C17-C22 -5.2(3) C22-C17-C18-C19 -178.6(2)
C2-C16-C17-C18 174.5(2) C22-C17-C18-H18 1.4(4)
C21-C16-C17-C22 177.2(2) C27-C26-C31-H31 179.8(2)
C21-C16-C17-C18 -3.1(3) C27-C26-C31-C30 -0.2(4)
H22-C22-C17-C16 174.5(2) C25-C26-C31-H31 -1.5(4)
H22A-C22-C17-C18 -5.2(3) C25-C26-C31-C30 178.5(2)
H22B-C22-C17-C16 54.5(3) C31-C26-C27-H27 -179.7(2)
H22B-C22-C17-C18 -125.1(2) C31-C26-C27-C28 0.4(4)
H22C-C22-C17-C16 -65.5(3) C25-C26-C27-H27 1.6(4)
H22C-C22-C17-C18 114.9(3) C25-C26-C27-C28 -178.4(2)
C16-C21-C20-C19 1.0(4) C31-C26-C25-P1 -21.3(3)
C16-C21-C20-H20 -179.1(2) C31-C26-C25-H25 158.6(2)
C24-C21-C20-C19 -177.9(2) C27-C26-C25-P1 157.4(2)
C24-C21-C20-H20 2.0(4) C27-C26-C25-H25 -22.7(3)
C16-C21-C24-H24A 171.7(2) C26-C31-C30-H30 -179.3(2)
C16-C21-C24-H24B 51.7(3) C26-C31-C30-C29 0.7(4)
C16-C21-C24-H24C -68.4(3) H31-C31-C30-H30 0.7(4)
C20-C21-C24-H24A -9.4(4) H31-C31-C30-C29 -179.3(2)
C20-C21-C24-H24B -129.5(3) C26-C27-C28-C29 -1.1(4)
C20-C21-C24-H24C 110.5(3) C26-C27-C28-H28 178.9(2)
190
H27-C27-C28-C29 179.0(2)
H27-C27-C28-H28 -1.0(4)
C31-C30-C29-C28 -1.4(4)
C31-C30-C29-N1 177.2(2)
H30-C30-C29-C28 178.6(2)
H30-C30-C29-N1 -2.8(4)
C30-C29-C28-C27 1.6(4)
C30-C29-C28-H28 -178.4(2)
N1-C29-C28-C27 -177.0(2)
N1-C29-C28-H28 3.0(4)
C30-C29-N1-O2 -1.9(3)
C30-C29-N1-O1 177.6(2)
C28-C29-N1-O2 176.8(2)
C28-C29-N1-O1 -3.7(3)
191
Table D.1.Crystal data and structure refinement for 3.9
P
Crystal structure of 3.9
CN Compound 3.9
Empirical formula C32 H30 N P
Formula weight (g/mol) 459.54
Temperature (°K) 273(2)
Wavelength (Å) 0.71073
Crystal system Monoclinic
Space group P2(1)/n
Unit cell dimensions a = 8.8864(3) Å
b = 13.3717(5) Å
c = 21.7122(7) Å 192
α = 90°
β = 93.848(2) °
γ = 90 °
Volume (Å)3 2574.16(15)
Z 4
Density calculated (Mg/m3) 1.186
Absorption Coefficient (mm-1) 0.127
F(000) 976
Crystal size (mm) 0.32 x 0.22 x 0.22
θ-range 1.79 to 23.14°
Limiting indices -9<=h<=9
-14<=k<=14
-23<=l<=23
Reflections collected 31244
Unique (Rint) 3637 [R(int) = 0.0543]
Completeness to θ 23.14°,99.9 %
Absorption correction Multi-scan
Max & min transmission 0.9726 and 0.9605
Refinement method Full-matrix least-squares on F2
Data/restraint/parameters 3637 / 0 / 313
Goodness-of-fit on F2 1.093
Final R indices [ I > 2σ(I)] R1 = 0.0599
193
wR2 = 0.1317
R indices (all data) R1 = 0.0766
wR2 = 0.1442
Largest diff. peak and hole (Å-3) 1.281 & -0.765
Table D.2. Bond lengths [Å] for 3.9
P(1)-C(25) 1.604(4) C(10)-C(11) 1.378(5)
P(1)-C(1) 1.850(3) C(10)-C(15) 1.512(5)
N(1)-C(32) 1.141(5) C(11)-C(12) 1.399(5)
C(1)-C(6) 1.406(5) C(12)-C(13) 1.503(5)
C(1)-C(2) 1.413(4) C(16)-C(21) 1.397(5)
C(2)-C(3) 1.384(5) C(16)-C(17) 1.402(5)
C(2)-C(16) 1.502(5) C(17)-C(18) 1.395(5)
C(3)-C(4) 1.377(5) C(17)-C(23) 1.506(5)
C(4)-C(5) 1.392(5) C(18)-C(19) 1.386(5)
C(5)-C(6) 1.385(5) C(19)-C(20) 1.379(5)
C(6)-C(7) 1.509(4) C(19)-C(24) 1.510(5)
C(7)-C(12) 1.395(5) C(20)-C(21) 1.391(5)
C(7)-C(8) 1.402(5) C(21)-C(22) 1.514(5)
C(8)-C(9) 1.392(5) C(25)-C(26) 1.477(5)
C(8)-C(14) 1.506(4) C(26)-C(31) 1.406(5)
C(9)-C(10) 1.387(5) C(26)-C(27) 1.409(5)
194
C(27)-C(28) 1.375(5)
C(28)-C(29) 1.367(5)
C(29)-C(30) 1.425(5)
C(29)-C(32) 1.434(5)
C(30)-C(31) 1.374(5)
Table D.3. Bond angles [°] for 3.9
C(25)-P(1)-C(1) 105.97(17) C(8)-C(7)-C(6) 119.0(3)
C(6)-C(1)-C(2) 119.5(3) C(9)-C(8)-C(7) 118.4(3)
C(6)-C(1)-P(1) 126.1(2) C(9)-C(8)-C(14) 120.4(3)
C(2)-C(1)-P(1) 114.2(2) C(7)-C(8)-C(14) 121.2(3)
C(3)-C(2)-C(1) 119.7(3) C(10)-C(9)-C(8) 122.2(3)
C(3)-C(2)-C(16) 121.3(3) C(11)-C(10)-C(9) 118.1(3)
C(1)-C(2)-C(16) 119.0(3) C(11)-C(10)-C(15) 121.8(3)
C(4)-C(3)-C(2) 120.8(3) C(9)-C(10)-C(15) 120.2(3)
C(3)-C(4)-C(5) 119.7(3) C(10)-C(11)-C(12) 122.1(3)
C(6)-C(5)-C(4) 121.2(3) C(7)-C(12)-C(11) 118.7(3)
C(5)-C(6)-C(1) 119.1(3) C(7)-C(12)-C(13) 121.2(3)
C(5)-C(6)-C(7) 118.3(3) C(11)-C(12)-C(13) 120.1(3)
C(1)-C(6)-C(7) 122.6(3) C(21)-C(16)-C(17) 120.5(3)
C(12)-C(7)-C(8) 120.5(3) C(21)-C(16)-C(2) 120.0(3)
C(12)-C(7)-C(6) 120.5(3) C(17)-C(16)-C(2) 119.5(3)
195
C(18)-C(17)-C(16) 118.5(3) N(1)-C(32)-C(29) 176.7(4)
C(18)-C(17)-C(23) 120.2(3)
C(16)-C(17)-C(23) 121.3(3)
C(19)-C(18)-C(17) 121.8(3)
C(20)-C(19)-C(18) 118.4(3)
C(20)-C(19)-C(24) 120.6(3)
C(18)-C(19)-C(24) 121.1(3)
C(19)-C(20)-C(21) 122.1(3)
C(20)-C(21)-C(16) 118.7(3)
C(20)-C(21)-C(22) 120.2(3)
C(16)-C(21)-C(22) 121.1(3)
C(26)-C(25)-P(1) 126.3(3)
C(31)-C(26)-C(27) 117.3(3)
C(31)-C(26)-C(25) 122.7(3)
C(27)-C(26)-C(25) 120.0(3)
C(28)-C(27)-C(26) 120.5(3)
C(29)-C(28)-C(27) 122.2(3)
C(28)-C(29)-C(30) 118.7(3)
C(28)-C(29)-C(32) 122.1(3)
C(30)-C(29)-C(32) 119.2(3)
C(31)-C(30)-C(29) 119.2(3)
C(30)-C(31)-C(26) 122.1(3)
196
Table D.4. Torsion angles [°] for 3.9
C25-P1-C1-C2 136.1(3) C2-C3-C4-C5 3.1(5)
C25-P1-C1-C6 -49.6(3) H3-C3-C4-H4 3.2(6)
C1-P1-C25-H25 -1.4(4) H3-C3-C4-C5 -176.8(3)
C1-P1-C25-C26 178.6(3) C3-C4-C5-H5 178.5(3)
P1-C1-C2-C3 174.3(3) C3-C4-C5-C6 -1.6(5)
P1-C1-C2-C16 -6.6(4) H4-C4-C5-H5 -1.5(6)
C6-C1-C2-C3 -0.4(5) H4-C4-C5-C6 178.5(3)
C6-C1-C2-C16 178.7(3) C4-C5-C6-C1 -1.0(5)
P1-C1-C6-C5 -172.1(2) C4-C5-C6-C7 176.8(3)
P1-C1-C6-C7 10.2(4) H5-C5-C6-C1 179.0(3)
C2-C1-C6-C5 2.0(5) H5-C5-C6-C7 -3.2(5)
C2-C1-C6-C7 -175.7(3) C1-C6-C7-C8 97.7(4)
C1-C2-C3-H3 177.8(3) C1-C6-C7-C12 -82.7(4)
C1-C2-C3-C4 -2.1(5) C5-C6-C7-C8 -80.0(4)
C16-C2-C3-H3 -1.3(5) C5-C6-C7-C12 99.6(4)
C16-C2-C3-C4 178.7(3) C6-C7-C8-C9 -177.2(3)
C1-C2-C16-C17 -87.2(4) C6-C7-C8-C14 2.3(5)
C1-C2-C16-C21 91.0(4) C12-C7-C8-C9 3.2(5)
C3-C2-C16-C17 92.0(4) C12-C7-C8-C14 -177.3(3)
C3-C2-C16-C21 -89.9(4) C6-C7-C12-C11 178.2(3)
C2-C3-C4-H4 -176.9(3) C6-C7-C12-C13 -3.2(5)
197
C8-C7-C12-C11 -2.2(5) C9-C10-C15-H15C -59.8(5)
C8-C7-C12-C13 176.4(3) C11-C10-C15-H15A 0.3(5)
C7-C8-C9-H9 178.2(3) C11-C10-C15-H15B -119.6(4)
C7-C8-C9-C10 -1.9(5) C11-C10-C15-H15C 120.3(4)
C14-C8-C9-H9 -1.4(5) C10-C11-C12-C7 -0.2(5)
C14-C8-C9-C10 178.6(3) C10-C11-C12-C13 -178.9(3)
C7-C8-C14-H14A -42.1(5) H11-C11-C12-C7 179.9(3)
C7-C8-C14-H14B -162.0(3) H11-C11-C12-C13 1.2(5)
C7-C8-C14-H14C 77.9(4) C7-C12-C13-H13A -71.7(4)
C9-C8-C14-H14A 137.5(3) C7-C12-C13-H13B 168.3(3)
C9-C8-C14-H14B 17.5(5) C7-C12-C13-H13C 48.3(5)
C9-C8-C14-H14C -102.5(4) C11-C12-C13-H13A 106.9(4)
C8-C9-C10-C11 -0.4(5) C11-C12-C13-H13B -13.1(5)
C8-C9-C10-C15 179.7(3) C11-C12-C13-H13C -133.1(3)
H9-C9-C10-C11 179.5(4) C2-C16-C17-C18 176.4(3)
H9-C9-C10-C15 -0.4(6) C2-C16-C17-C23 -2.9(5)
C9-C10-C11-H11 -178.6(3) C21-C16-C17-C18 -1.8(5)
C9-C10-C11-C12 1.5(5) C21-C16-C17-C23 178.9(3)
C15-C10-C11-H11 1.3(6) C2-C16-C21-C20 -176.3(3)
C15-C10-C11-C12 -178.6(3) C2-C16-C21-C22 1.1(5)
C9-C10-C15-H15A -179.8(3) C17-C16-C21-C20 1.8(5)
C9-C10-C15-H15B 60.3(5) C17-C16-C21-C22 179.2(3)
198
C16-C17-C18-H18 180.0(3) C20-C19-C24-H24B 147.4(4)
C16-C17-C18-C19 -0.0(5) C20-C19-C24-H24C 27.4(5)
C23-C17-C18-H18 -0.7(5) C19-C20-C21-C16 -0.0(5)
C23-C17-C18-C19 179.3(3) C19-C20-C21-C22 -177.4(3)
C16-C17-C23-H23A -59.2(4) H20-C20-C21-C16 180.0(3)
C16-C17-C23-H23B -179.2(3) H20-C20-C21-C22 2.6(5)
C16-C17-C23-H23C 60.8(4) C16-C21-C22-H22A 169.2(3)
C18-C17-C23-H23A 121.5(4) C16-C21-C22-H22B 49.2(4)
C18-C17-C23-H23B 1.5(5) C16-C21-C22-H22C -70.8(4)
C18-C17-C23-H23C -118.5(4) C20-C21-C22-H22A -13.4(5)
C17-C18-C19-C20 1.7(5) C20-C21-C22-H22B -133.5(3)
C17-C18-C19-C24 -176.9(3) C20-C21-C22-H22C 106.5(4)
H18-C18-C19-C20 -178.3(3) P1-C25-C26-C27 -169.3(3)
H18-C18-C19-C24 3.1(6) P1-C25-C26-C31 10.6(5)
C18-C19-C20-H20 178.3(3) H25-C25-C26-C27 10.7(5)
C18-C19-C20-C21 -1.7(5) H25-C25-C26-C31 -169.4(3)
C24-C19-C20-H20 -3.1(6) C25-C26-C27-H27 0.3(5)
C24-C19-C20-C21 176.9(3) C25-C26-C27-C28 -179.6(3)
C18-C19-C24-H24A 85.9(5) C31-C26-C27-H27 -179.6(3)
C18-C19-C24-H24B -34.0(5) C31-C26-C27-C28 0.5(5)
C18-C19-C24-H24C -154.0(4) C25-C26-C31-C30 179.3(3)
C20-C19-C24-H24A -92.6(4) C25-C26-C31-H31 -0.6(6)
199
C27-C26-C31-C30 -0.8(5)
C27-C26-C31-H31 179.3(3)
C26-C27-C28-H28 -179.6(3)
C26-C27-C28-C29 0.4(6)
H27-C27-C28-H28 0.5(6)
H27-C27-C28-C29 -179.5(4)
C27-C28-C29-C30 -0.9(6)
C27-C28-C29-C32 177.5(4)
H28-C28-C29-C30 179.0(4)
H28-C28-C29-C32 -2.5(6)
C28-C29-C30-H30 -179.3(4)
C28-C29-C30-C31 0.6(5)
C32-C29-C30-H30 2.2(6)
C32-C29-C30-C31 -177.9(3)
C28-C29-C32-N1 12(7)
C30-C29-C32-N1 -170(7)
C29-C30-C31-C26 0.3(5)
C29-C30-C31-H31 -179.8(3)
H30-C30-C31-C26 -179.8(3)
H30-C30-C31-H31 0.1(6)
200
Table E.1.Crystal data and structure refinement for 3.10
O
P
Crystal structure of 3.10 CN
Compound 3.10
Empirical formula C33H32NOP
Formula weight (g/mol) 489.57
Temperature (°K) 100(2)
Wavelength (Å) 0.71073
Crystal system Triclinic
Space group P-1
Unit cell dimensions a = 12.408(4) Å
b = 13.525(5) Å
201
c = 19.559(9) Å
α = 100.417(7)°
β = 101.084(7)°
γ = 114.306(4)°
Volume (Å)3 2808.8(18)
Z 4
Density calculated (Mg/m3) 1.158
Absorption Coefficient (mm-1) 0.123
F(000) 1040
Crystal size (mm) 0.18 x 0.11 x 0.10
θ-range 1.11 to 26.00°
Limiting indices -15<=h<=15
-16<=k<=16
-24<=l<=24
Reflections collected 30129
Unique (Rint) 11001 [R(int) = 0.1048]
Completeness to θ 26.00°, 99.6 %
Absorption correction Multi-scan
Max & min transmission 0.9878 and 0.9783
Refinement method Full-matrix least-squares on F2
Data/restraint/parameters 11001 / 0 / 663
Goodness-of-fit on F2 0.973
Final R indices [ I > 2σ(I)] R1 = 0.0634 202
wR2 = 0.1048
R indices (all data) R1 = 0.1625
wR2 = 0.1434
Largest diff. peak and hole (Å-3) 0.325 and -0.278
Table E.2. Bond lengths [Å] for 3.10
P1-C1 1.827(3) C12-C15 1.500(6)
P1-C26 1.655(4) C7-C8 1.403(6)
C6-C5 1.385(4) C8-C13 1.506(5)
C6-C1 1.394(6) C8-C9 1.395(5)
C6-C7 1.505(5) C11-H11 0.949(4)
C2-C1 1.413(5) C11-C10 1.387(7)
C2-C3 1.387(4) C13-H13A 0.979(5)
C2-C16 1.501(6) C13-H13B 0.980(3)
C5-H5 0.950(5) C13-H13C 0.980(5)
C5-C4 1.392(5) C9-H9 0.950(4)
C4-C3 1.389(6) C9-C10 1.379(5)
C4-O1 1.364(3) C10-C14 1.521(6)
C3-H3 0.950(4) C15-H15A 0.980(3)
C12-C7 1.399(5) C15-H15B 0.980(4)
C12-C11 1.399(6) C15-H15C 0.980(5)
203
C14-H14A 0.980(4) C23-H23C 0.980(3)
C14-H14B 0.980(4) C25-H25A 0.979(4)
C14-H14C 0.979(5) C25-H25B 0.980(3)
C16-C21 1.394(6) C25-H25C 0.979(4)
C16-C17 1.401(6) C25-O1 1.430(5)
C21-C20 1.395(6) C26-H26 0.950(4)
C21-C24 1.520(6) C26-C27 1.462(4)
C20-H20 0.950(4) C27-C28 1.402(5)
C20-C19 1.389(6) C27-C32 1.396(6)
C17-C18 1.395(6) C28-H28 0.950(4)
C17-C22 1.513(6) C28-C29 1.371(5)
C19-C18 1.383(6) C29-H29 0.950(4)
C19-C23 1.513(6) C29-C30 1.397(6)
C18-H18 0.950(4) C32-H32 0.950(4)
C24-H24A 0.981(4) C32-C31 1.380(5)
C24-H24B 0.980(4) C30-C31 1.395(5)
C24-H24C 0.980(3) C30-C33 1.439(5)
C22-H22A 0.980(4) C31-H31 0.949(4)
C22-H22B 0.981(4) C33-N1 1.146(5)
C22-H22C 0.980(3)
C23-H23A 0.979(4)
C23-H23B 0.980(4)
204
Table E.3. Bond angles [°] for 3.10
C1-P1-C26 104.0(2) C11-C12-C15 120.6(4)
C5-C6-C1 121.4(3) C6-C7-C12 119.0(3)
C5-C6-C7 119.4(3) C6-C7-C8 120.5(3)
C1-C6-C7 119.2(3) C12-C7-C8 120.6(4)
C1-C2-C3 119.1(3) C7-C8-C13 120.2(3)
C1-C2-C16 121.5(3) C7-C8-C9 118.5(4)
C3-C2-C16 119.4(3) C13-C8-C9 121.3(4)
C6-C5-H5 120.4(4) C12-C11-H11 119.2(4)
C6-C5-C4 119.2(3) C12-C11-C10 121.7(4)
H5-C5-C4 120.4(4) H11-C11-C10 119.1(4)
P1-C1-C6 116.6(3) C8-C13-H13A 109.5(4)
P1-C1-C2 124.1(3) C8-C13-H13B 109.5(4)
C6-C1-C2 119.1(3) C8-C13-H13C 109.5(4)
C5-C4-C3 120.2(4) H13A-C13-H13B 109.5(4)
C5-C4-O1 124.4(3) H13A-C13-H13C 109.4(4)
C3-C4-O1 115.5(3) H13B-C13-H13C 109.4(4)
C2-C3-C4 121.0(3) C8-C9-H9 118.9(4)
C2-C3-H3 119.5(4) C8-C9-C10 122.1(4)
C4-C3-H3 119.5(4) H9-C9-C10 118.9(4)
C7-C12-C11 118.7(4) C11-C10-C9 118.5(4)
C7-C12-C15 120.7(3) C11-C10-C14 120.1(4)
205
C9-C10-C14 121.4(4) C16-C17-C18 119.0(4)
C12-C15-H15A 109.4(3) C16-C17-C22 121.6(3)
C12-C15-H15B 109.4(3) C18-C17-C22 119.4(3)
C12-C15-H15C 109.5(3) C20-C19-C18 118.0(4)
H15A-C15-H15B 109.5(4) C20-C19-C23 120.9(3)
H15A-C15-H15C 109.4(4) C18-C19-C23 121.1(3)
H15B-C15-H15C 109.5(4) C17-C18-C19 122.0(4)
C10-C14-H14A 109.4(4) C17-C18-H18 118.9(4)
C10-C14-H14B 109.5(4) C19-C18-H18 119.1(4)
C10-C14-H14C 109.5(4) C21-C24-H24A 109.5(3)
H14A-C14-H14B 109.4(4) C21-C24-H24B 109.5(3)
H14A-C14-H14C 109.6(4) C21-C24-H24C 109.5(3)
H14B-C14-H14C 109.5(4) H24A-C24-H24B 109.4(4)
C2-C16-C21 120.5(3) H24A-C24-H24C 109.4(4)
C2-C16-C17 119.4(3) H24B-C24-H24C 109.4(4)
C21-C16-C17 120.0(4) C17-C22-H22A 109.4(3)
C16-C21-C20 119.2(4) C17-C22-H22B 109.5(3)
C16-C21-C24 121.9(3) C17-C22-H22C 109.5(3)
C20-C21-C24 118.9(3) H22A-C22-H22B 109.5(4)
C21-C20-H20 119.1(4) H22A-C22-H22C 109.5(4)
C21-C20-C19 121.9(4) H22B-C22-H22C 109.5(4)
H20-C20-C19 119.1(4) C19-C23-H23A 109.5(3)
206
C19-C23-H23B 109.4(3) C28-C27-C32 117.4(3)
C19-C23-H23C 109.4(3) C27-C28-H28 119.3(4)
H23A-C23-H23B 109.5(4) C27-C28-C29 121.5(4)
H23A-C23-H23C 109.6(4) H28-C28-C29 119.3(4)
H23B-C23-H23C 109.4(4) C28-C29-H29 119.9(4)
H25A-C25-H25B 109.5(4) C28-C29-C30 120.2(4)
H25A-C25-H25C 109.5(4) H29-C29-C30 119.9(4)
H25A-C25-O1 109.4(3) C27-C32-H32 119.0(4)
H25B-C25-H25C 109.5(4) C27-C32-C31 122.1(4)
H25B-C25-O1 109.4(3) H32-C32-C31 119.0(4)
H25C-C25-O1 109.5(3) C29-C30-C31 119.5(4)
C4-O1--C25 117.7(3) C29-C30-C33 119.5(4)
P1-C26-H26 117.6(3) C31-C30-C33 121.0(4)
P1-C26-C27 124.8(3) C32-C31-C30 119.4(4)
H26-C26-C27 117.6(4) C32-C31-H31 120.4(4)
C26-C27-C28 121.9(3) C30-C31-H31 120.2(4)
C26-C27-C32 120.7(3) C30-C33-N1 178.0(5)
207
Table E.4. Torsion angles [°] for 3.10
C26-P1-C1-C6 116.2(3) C1-C2-C3-H3 -179.0(4)
C26-P1-C1-C2 -69.9(4) C16-C2-C3-C4 -177.7(4)
C1-P1-C26-H26 -1.3(4) C16-C2-C3-H3 2.2(6)
C1-P1-C26-C27 178.7(3) C1-C2-C16-C21 105.0(4)
C1-C6-C5-H5 179.2(4) C1-C2-C16-C17 -74.8(5)
C1-C6-C5-C4 -0.8(6) C3-C2-C16-C21 -76.3(5)
C7-C6-C5-H5 0.4(6) C3-C2-C16-C17 104.0(4)
C7-C6-C5-C4 -179.6(3) C6-C5-C4-C3 1.1(6)
C5-C6-C1-P1 174.8(3) C6-C5-C4-O1 -179.8(3)
C5-C6-C1-C2 0.6(6) H5-C5-C4-C3 -178.9(4)
C7-C6-C1-P1 -6.4(5) H5-C5-C4-O1 0.2(6)
C7-C6-C1-C2 179.4(3) C5-C4-C3-C2 -1.3(6)
C5-C6-C7-C12 91.7(5) C5-C4-C3-H3 178.8(4)
C5-C6-C7-C8 -88.3(5) O1-C4-C3-C2 179.6(3)
C1-C6-C7-C12 -87.1(5) O1-C4-C3-H3 -0.4(6)
C1-C6-C7-C8 92.9(5) C5-C4-O1-C25 8.2(5)
C3-C2-C1-P1 -174.5(3) C3-C4-O1-C25 -172.7(3)
C3-C2-C1-C6 -0.7(5) C11-C12-C7-C6 179.6(4)
C16-C2-C1-P1 4.2(5) C11-C12-C7-C8 -0.3(6)
C16-C2-C1-C6 178.0(3) C15-C12-C7-C6 0.5(6)
C1-C2-C3-C4 1.1(6) C15-C12-C7-C8 -179.5(4)
208
C7-C12-C11-H11 179.8(4) C13-C8-C9-H9 0.0(6)
C7-C12-C11-C10 -0.1(6) C13-C8-C9-C10 -180.0(4)
C15-C12-C11-H11 -1.0(6) C12-C11-C10-C9 0.3(6)
C15-C12-C11-C10 179.1(4) C12-C11-C10-C14 179.0(4)
C7-C12-C15-H15A -61.2(5) H11-C11-C10-C9 -179.6(4)
C7-C12-C15-H15B 178.8(4) H11-C11-C10-C14 -1.0(7)
C7-C12-C15-H15C 58.8(5) C8-C9-C10-C11 -0.1(6)
C11-C12-C15-H15A 119.7(4) C8-C9-C10-C14 -178.7(4)
C11-C12-C15-H15B -0.3(5) H9-C9-C10-C11 179.9(4)
C11-C12-C15-H15C -120.4(4) H9-C9-C10-C14 1.3(6)
C6-C7-C8-C13 0.2(6) C11-C10-C14-H14A 178.1(4)
C6-C7-C8-C9 -179.4(3) C11-C10-C14-H14B 58.2(5)
C12-C7-C8-C13 -179.8(4) C11-C10-C14-H14C -61.8(5)
C12-C7-C8-C9 0.5(6) C9-C10-C14-H14A -3.3(6)
C7-C8-C13-H13A 173.1(4) C9-C10-C14-H14B -123.2(4)
C7-C8-C13-H13B 53.0(5) C9-C10-C14-H14C 116.8(5)
C7-C8-C13-H13C -67.0(5) C2-C16-C21-C20 -179.1(3)
C9-C8-C13-H13A -7.3(6) C2-C16-C21-C24 1.6(6)
C9-C8-C13-H13B -127.3(4) C17-C16-C21-C20 0.6(6)
C9-C8-C13-H13C 112.7(4) C17-C16-C21-C24 -178.6(4)
C7-C8-C9-H9 179.7(4) C2-C16-C17-C18 179.3(3)
C7-C8-C9-C10 -0.3(6) C2-C16-C17-C22 -2.9(6)
209
C21-C16-C17-C18 -0.4(6) C16-C17-C22-H22C -66.6(5)
C21-C16-C17-C22 177.3(4) C18-C17-C22-H22A -8.8(5)
C16-C21-C20-H20 180.0(4) C18-C17-C22-H22B -128.8(4)
C16-C21-C20-C19 0.1(6) C18-C17-C22-H22C 111.2(4)
C24-C21-C20-H20 -0.8(6) C20-C19-C18-C17 1.1(6)
C24-C21-C20-C19 179.3(4) C20-C19-C18-H18 -179.0(4)
C16-C21-C24-H24A -45.0(5) C23-C19-C18-C17 -179.3(4)
C16-C21-C24-H24B -164.9(4) C23-C19-C18-H18 0.7(6)
C16-C21-C24-H24C 75.1(5) C20-C19-C23-H23A 139.0(4)
C20-C21-C24-H24A 135.8(4) C20-C19-C23-H23B 18.9(5)
C20-C21-C24-H24B 15.8(5) C20-C19-C23-H23C -100.9(4)
C20-C21-C24-H24C -104.2(4) C18-C19-C23-H23A -40.7(5)
C21-C20-C19-C18 -0.9(6) C18-C19-C23-H23B -160.8(4)
C21-C20-C19-C23 179.4(4) C18-C19-C23-H23C 79.4(5)
H20-C20-C19-C18 179.2(4) H25A-C25-O1-C4 -62.5(4)
H20-C20-C19-C23 -0.5(6) H25B-C25-O1-C4 177.5(3)
C16-C17-C18-C19 -0.4(6) H25C-C25-O1-C4 57.5(4)
C16-C17-C18-H18 179.6(4) P1-C26-C27-C28 -10.8(6)
C22-C17-C18-C19 -178.2(4) P1-C26-C27-C32 170.8(3)
C22-C17-C18-H18 1.8(6) H26-C26-C27-C28 169.2(4)
C16-C17-C22-H22A 173.4(4) H26-C26-C27-C32 -9.2(6)
C16-C17-C22-H22B 53.4(5) C26-C27-C28-H28 2.8(6)
210
C26-C27-C28-C29 -177.1(4) C33-C30-C31-H31 1.1(6)
C32-C27-C28-H28 -178.7(4) C29-C30-C33-N1 17(14)
C32-C27-C28-C29 1.3(6) C31-C30-C33-N1 -164(14)
C26-C27-C32-H32 -1.8(6)
C26-C27-C32-C31 178.2(4)
C28-C27-C32-H32 179.8(4)
C28-C27-C32-C31 -0.3(6)
C27-C28-C29-H29 178.5(4)
C27-C28-C29-C30 -1.6(6)
H28-C28-C29-H29 -1.5(6)
H28-C28-C29-C30 178.5(4)
C28-C29-C30-C31 0.8(6)
C28-C29-C30-C33 179.9(4)
H29-C29-C30-C31 -179.2(4)
H29-C29-C30-C33 -0.2(6)
C27-C32-C31-C30 -0.4(6)
C27-C32-C31-H31 179.6(4)
H32-C32-C31-C30 179.5(4)
H32-C32-C31-H31 -0.5(6)
C29-C30-C31-C32 0.2(6)
C29-C30-C31-H31 -179.8(4)
C33-C30-C31-C32 -178.9(4)
211
Table F.1.Crystal data and structure refinement for 3.12
O
P
Crystal structure of 3.12
Compound 3.12
Empirical formula C32 H33 O P
Formula weight (g/mol) 464.55
Temperature (°K) 100(2)
Wavelength (Å) 0.71073
Crystal system Monoclinic
Space group P2(1)/c
Unit cell dimensions a = 13.1255(16)
212
b = 8.3261(10)
c = 24.814(3)
α = 90°
β = 101.8120(10)°
γ = 90°
Volume (Å)3 2654.3(6)
Z 4
Density calculated (Mg/m3) 1.162
Absorption Coefficient (mm-1) 0.125
F(000) 992
Crystal size (mm) 0.35 x 0.28 x 0.20
θ-range 1.59 to 27.50°
Limiting indices -17<=h<=17
-10<=k<=10
-32<=l<=32
Reflections collected 30125
Unique (Rint) 6043 [R(int) = 0.0252]
Completeness to θ 27.50°, 99.3 %
Absorption correction Multi-scan
Max & min transmission 0.9754 and 0.9575
Refinement method Full-matrix least-squares on F2
Data/restraint/parameters 6043 / 0 / 362
Goodness-of-fit on F2 1.025 213
Final R indices [ I > 2σ(I)] R1 = 0.0427
wR2 = 0.1136
R indices (all data) R1 = 0.0491
wR2 = 0.1196
Largest diff. peak and hole (Å-3) 0.877 and -0.348
Table F.2. Bond lengths [Å] for 3.12
P1-C1 1.829(1) C8-C9 1.392(2)
P1-C26 1.672(1) C8-C13 1.504(2)
C1-C6 1.408(2) C9-C10 1.389(2)
C1-C2 1.411(2) C9-H9 0.97(2)
C5-C6 1.397(2) C12-C11 1.398(2)
C5-C4 1.391(2) C12-C15 1.504(2)
C5-H5 0.97(2) C11-C10 1.390(2)
C6-C7 1.502(2) C11-H11 0.97(2)
C2-C3 1.385(2) C10-C14 1.513(2)
C2-C16 1.499(2) C15-H15A 0.980(2)
C3-C4 1.394(2) C15-H15B 0.980(2)
C3-H3 0.93(2) C15-H15C 0.979(1)
C4-O1 1.369(2) C13-H13A 0.980(2)
C7-C8 1.404(2) C13-H13B 0.980(2)
C7-C12 1.399(2) C13-H13C 0.980(2)
214
C14-H14A 0.980(2) C23-H23A 0.980(2)
C14-H14B 0.980(2) C23-H23B 0.981(2)
C14-H14C 0.981(2) C23-H23C 0.980(2)
C17-C16 1.401(2) C25-H25A 0.980(2)
C17-C18 1.392(2) C25-H25B 0.979(2)
C17-C22 1.508(2) C25-H25C 0.981(2)
C20-C21 1.394(2) C25-O1 1.420(2)
C20-C19 1.391(2) C26-C27 1.463(2)
C20-H20 1.00(2) C26-H26 0.96(2)
C16-C21 1.403(2) C27-C32 1.397(2)
C18-C19 1.392(2) C27-C28 1.399(2)
C18-H18 0.98(2) C32-C31 1.389(3)
C21-C24 1.506(2) C32-H32 0.98(2)
C19-C23 1.509(2) C28-C29 1.385(3)
C22-H22A 0.981(1) C28-H28 0.97(2)
C22-H22B 0.979(2) C31-C30 1.387(3)
C22-H22C 0.981(2) C31-H31 0.97(2)
C24-H24A 0.980(2) C30-C29 1.382(3)
C24-H24B 0.980(2) C30-H30 0.94(2)
C24-H24C 0.981(2) C29-H29 0.98(2)
215
Table F.3. Bond angles [°] for 3.12
C1-P1-C26 103.29(7) C8-C7-C12 119.9(1)
P1-C1-C6 125.3(1) C7-C8-C9 119.0(1)
P1-C1-C2 115.6(1) C7-C8-C13 121.4(1)
C6-C1-C2 118.9(1) C9-C8-C13 119.6(1)
C6-C5-C4 120.6(1) C8-C9-C10 121.9(1)
C6-C5-H5 118(1) C8-C9-H9 119(1)
C4-C5-H5 121(1) C10-C9-H9 119(1)
C1-C6-C5 119.7(1) C7-C12-C11 119.3(1)
C1-C6-C7 122.2(1) C7-C12-C15 121.7(1)
C5-C6-C7 118.2(1) C11-C12-C15 119.0(1)
C1-C2-C3 120.7(1) C12-C11-C10 121.5(1)
C1-C2-C16 119.5(1) C12-C11-H11 119(1)
C3-C2-C16 119.7(1) C10-C11-H11 119(1)
C2-C3-C4 120.0(1) C9-C10-C11 118.3(1)
C2-C3-H3 120(1) C9-C10-C14 120.8(1)
C4-C3-H3 120(1) C11-C10-C14 120.9(1)
C5-C4-C3 120.1(1) C12-C15-H15A 109.5(1)
C5-C4-O1 124.5(1) C12-C15-H15B 109.5(1)
C3-C4-O1 115.4(1) C12-C15-H15C 109.4(1)
C6-C7-C8 119.6(1) H15A-C15-H15B 109.5(1)
C6-C7-C12 120.5(1) H15A-C15-H15C 109.4(1)
216
H15B-C15-H15C 109.5(1) C17-C18-C19 121.7(1)
C8-C13-H13A 109.5(1) C17-C18-H18 119(1)
C8-C13-H13B 109.5(1) C19-C18-H18 119(1)
C8-C13-H13C 109.4(1) C20-C21-C16 119.0(1)
H13A-C13-H13B 109.5(2) C20-C21-C24 120.4(1)
H13A-C13-H13C 109.4(2) C16-C21-C24 120.6(1)
H13B-C13-H13C 109.5(2) C20-C19-C18 118.3(1)
C10-C14-H14A 109.5(2) C20-C19-C23 121.2(1)
C10-C14-H14B 109.5(2) C18-C19-C23 120.5(1)
C10-C14-H14C 109.5(2) C17-C22-H22A 109.5(1)
H14A-C14-H14B 109.5(2) C17-C22-H22B 109.5(1)
H14A-C14-H14C 109.5(2) C17-C22-H22C 109.5(1)
H14B-C14-H14C 109.5(2) H22A-C22-H22B 109.5(1)
C16-C17-C18 119.1(1) H22A-C22-H22C 109.4(1)
C16-C17-C22 120.8(1) H22B-C22-H22C 109.5(1)
C18-C17-C22 120.1(1) C21-C24-H24A 109.5(1)
C21-C20-C19 121.7(1) C21-C24-H24B 109.5(1)
C21-C20-H20 119(1) C21-C24-H24C 109.5(1)
C19-C20-H20 119(1) H24A-C24-H24B 109.5(2)
C2-C16-C17 120.3(1) H24A-C24-H24C 109.4(2)
C2-C16-C21 119.5(1) H24B-C24-H24C 109.5(2)
C17-C16-C21 120.2(1) C19-C23-H23A 109.5(1)
217
C19-C23-H23B 109.4(1) C29-C28-H28 119(1)
C19-C23-H23C 109.5(1) C32-C31-C30 120.2(2)
H23A-C23-H23B 109.5(2) C32-C31-H31 120(1)
H23A-C23-H23C 109.4(2) C30-C31-H31 120(1)
H23B-C23-H23C 109.5(2) C31-C30-C29 119.8(2)
H25A-C25-H25B 109.5(2) C31-C30-H30 121(1)
H25A-C25-H25C 109.4(2) C29-C30-H30 119(1)
H25A-C25-O1 109.5(2) C28-C29-C30 120.1(2)
H25B-C25-H25C 109.5(2) C28-C29-H29 119(1)
H25B-C25-O1 109.5(2) C30-C29-H29 120(1)
H25C-C25-O1 109.5(2) C4-O1-C25 117.2(1)
P1-C26-C27 124.9(1)
P1-C26-H26 120(1)
C27-C26-H26 115(1)
C26-C27-C32 123.1(1)
C26-C27-C28 118.6(1)
C32-C27-C28 118.3(1)
C27-C32-C31 120.6(1)
C27-C32-H32 119(1)
C31-C32-H32 121(1)
C27-C28-C29 120.9(2)
C27-C28-H28 120(1)
218
Table F.4. Torsion angles [°] for 3.12
C26-P1-C1-C6 54.6(1) C1-C6-C7-C12 75.5(2)
C26-P1-C1-C2 -131.1(1) C5-C6-C7-C8 74.8(2)
C1-P1-C26-C27 -176.9(1) C5-C6-C7-C12 -105.2(2)
C1-P1-C26-H26 -1(1) C1-C2-C3-C4 -0.3(2)
P1-C1-C6-C5 174.5(1) C1-C2-C3-H3 -179(1)
P1-C1-C6-C7 -6.2(2) C16-C2-C3-C4 177.2(1)
C2-C1-C6-C5 0.4(2) C16-C2-C3-H3 -1(1)
C2-C1-C6-C7 179.7(1) C1-C2-C16-C17 -95.7(2)
P1-C1-C2-C3 -174.5(1) C1-C2-C16-C21 83.9(2)
P1-C1-C2-C16 8.0(2) C3-C2-C16-C17 86.8(2)
C6-C1-C2-C3 0.2(2) C3-C2-C16-C21 -93.7(2)
C6-C1-C2-C16 -177.3(1) C2-C3-C4-C5 -0.2(2)
C4-C5-C6-C1 -1.0(2) C2-C3-C4-O1 -180.0(1)
C4-C5-C6-C7 179.7(1) H3-C3-C4-C5 178(1)
H5-C5-C6-C1 -178(1) H3-C3-C4-O1 -1(1)
H5-C5-C6-C7 3(1) C5-C4-O1-C25 -7.9(2)
C6-C5-C4-C3 0.9(2) C3-C4-O1-C25 171.9(1)
C6-C5-C4-O1 -179.4(1) C6-C7-C8-C9 176.4(1)
H5-C5-C4-C3 178(1) C6-C7-C8-C13 -3.6(2)
H5-C5-C4-O1 -2(1) C12-C7-C8-C9 -3.6(2)
C1-C6-C7-C8 -104.5(2) C12-C7-C8-C13 176.4(1)
219
C6-C7-C12-C11 -177.5(1) C7-C12-C15-H15A 173.5(1)
C6-C7-C12-C15 3.0(2) C7-C12-C15-H15B 53.4(2)
C8-C7-C12-C11 2.5(2) C7-C12-C15-H15C -66.6(2)
C8-C7-C12-C15 -177.0(1) C11-C12-C15-H15A -6.0(2)
C7-C8-C9-C10 2.0(2) C11-C12-C15-H15B -126.1(1)
C7-C8-C9-H9 -180(1) C11-C12-C15-H15C 113.9(2)
C13-C8-C9-C10 -178.0(1) C12-C11-C10-C9 -1.8(2)
C13-C8-C9-H9 -0(1) C12-C11-C10-C14 179.2(2)
C7-C8-C13-H13A 169.1(1) H11-C11-C10-C9 178(1)
C7-C8-C13-H13B 49.0(2) H11-C11-C10-C14 -1(1)
C7-C8-C13-H13C -71.0(2) C9-C10-C14-H14A -78.7(2)
C9-C8-C13-H13A -10.9(2) C9-C10-C14-H14B 161.3(2)
C9-C8-C13-H13B -131.0(2) C9-C10-C14-H14C 41.3(2)
C9-C8-C13-H13C 109.0(2) C11-C10-C14-H14A 100.3(2)
C8-C9-C10-C11 0.7(2) C11-C10-C14-H14B -19.7(3)
C8-C9-C10-C14 179.7(2) C11-C10-C14-H14C -139.7(2)
H9-C9-C10-C11 -177(1) C18-C17-C16-C2 179.6(1)
H9-C9-C10-C14 2(1) C18-C17-C16-C21 0.0(2)
C7-C12-C11-C10 0.2(2) C22-C17-C16-C2 0.2(2)
C7-C12-C11-H11 -179(1) C22-C17-C16-C21 -179.4(1)
C15-C12-C11-C10 179.7(1) C16-C17-C18-19 0.6(2)
C15-C12-C11-H11 0(1) C16-C17-C18-H18 -179(1)
220
C22-C17-C18-C19 -180.0(1) H18-C18-C19-C20 179(1)
C22-C17-C18-H18 0(1) H18-C18-C19-C23 -2(1)
C16-C17-C22-H22A 179.7(1) C20-C21-C24-H24A -0.3(2)
C16-C17-C22-H22B 59.7(2) C20-C21-C24-H24B -120.3(2)
C16-C17-C22-H22C -60.3(2) C20-C21-C24-H24C 119.7(2)
C18-C17-C22-H22A 0.3(2) C16-C21-C24-H24A 178.6(1)
C18-C17-C22-H22B -119.7(2) C16-C21-C24-H24B 58.6(2)
C18-C17-C22-H22C 120.3(2) C16-C21-C24-H24C -61.5(2)
C19-C20-C21-C16 -0.3(2) C20-C19-C23-H23A 22.4(2)
C19-C20-C21-C24 178.6(1) C20-C19-C23-H23B -97.7(2)
H20-C20-C21-C16 -179(1) C20-C19-C23-H23C 142.3(2)
H20-C20-C21-C24 -0(1) C18-C19-C23-H23A -156.9(1)
C21-C20-C19-C18 0.8(2) C18-C19-C23-H23B 83.1(2)
C21-C20-C19-C23 -178.5(1) C18-C19-C23-H23C -37.0(2)
H20-C20-C19-C18 180(1) H25A-C25-O1-C4 -54.8(2)
H20-C20-C19-C23 0(1) H25B-C25-O1-C4 -174.8(2)
C2-C16-C21-C20 -179.8(1) H25C-C25-O1-C4 65.1(2)
C2-C16-C21-C24 1.4(2) P1-C26-C27-C32 -19.5(2)
C17-C16-C21-C20 -0.2(2) P1-C26-C27-C28 159.7(1)
C17-C16-C21-C24 -179.0(1) H26-C26-C27-C32 164(1)
C17-C18-C19-C20 -1.0(2) H26-C26-C27-C28 -17(1)
C17-C18-C19-C23 178.3(1) C26-C27-C32-C31 179.5(1)
221
C26-C27-C32-H32 1(1) H30-C30-C29-H29 1(2)
C28-C27-C32-C31 0.3(2)
C28-C27-C32-H32 -178(1)
C26-C27-C28-C29 -178.7(2)
C26-C27-C28-H28 1(1)
C32-C27-C28-C29 0.5(2)
C32-C27-C28-H28 -180(1)
C27-C32-C31-C30 -0.6(3)
C27-C32-C31-H31 177(1)
H32-C32-C31-C30 178(1)
H32-C32-C31-H31 -4(2)
C27-C28-C29-C30 -1.1(3)
C27-C28-C29-H29 179(2)
H28-C28-C29-C30 179(1)
H28-C28-C29-H29 -1(2)
C32-C31-C30-C29 0.1(3)
C32-C31-C30-H30 180(2)
H31-C31-C30-C29 -178(2)
H31-C31-C30-H30 2(2)
C31-C30-C29-C28 0.8(3)
C31-C30-C29-H29 -179(2)
H30-C30-C29-C28 -179(2)
222
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