Synthesis and Characterization ofZero and First Generation Organometallic Nanorods by Evelyn Lazich Submitted in Partial Fulfillment ofthe Requirements for the Degree of Master ofScience in the Chemistry Program YOUNGSTOWN STATE UNNERSITY August, 2004 Synthesis and Characterization of Zero and First Generation Organometallic Nanorods by Evelyn Lazich I hereby release this thesis to the public. I understand this thesis will be housed at the Circulation Desk of the University library and will be available for public access. I also authorize the University or other individuals to make copies of this thesis as needed for scholarly research. Signature: ~~U-~1 Student, Evelyn Lazich Date Approvals: ' '21v~LL.·'. 1~'~...u(c.(i/. 1 ;,,' (- (i?:,fYl{1 (/Y) KJs!oLf ~.ommittee Mem er, Dr. Sherri R. Lovelace-Cameron Date -tz-L.{tz {~(. 4.....· ---.:c-c----.----. c0=z:;:ember, Dr. Matthias Zeller 4'~------"---.~ Dean of GradUa~udies,o Dr. Peter J. Date Evelyn Lazich, 2004, All Rights Reserved. 11l Abstract There is substantial interest in new materials exhibiting one, two, and three­ dimensional structures that are patterned on the nanoscale. Such organometallic materials have potential use in electronics, photonics, and nonlinear optical applications. The complexes discussed in this thesis were designed to have thermally and chemically stable repeating units such as [trans-Mo(PhzPCHzCHzPPhz)z(Il-CN-l,4-C6H4-NC)]. Isonitrile-bridged species have valuable features such that there is substantial conjugation down the oligomer backbone and because they form strong complexes with rationally tunable bonding characteristics. The aromatic isonitriles were prepared by reacting the aromatic amines with formic acid and then dehydrating the resulting formamides with trichloromethylchloroformate. The phosphine ancillary ligands were prepared by Grignard reactions and allow the nanorod's steric and electronic properties to be varied independently of one another. The phosphine ligands were reacted in the presence of MoCl5 to form the desired dinitrogen complexes. The monomers and oligomers were prepared by condensation reactions between the un-complexed bifunctional isonitriles and Mo(PR3)4(Nz)z moieties. After synthesizing the nanorods of the desired length, they were capped on each end using the terminal organometallic groups such as, Cr(CO)5 and CpFe(CO)/. IV Acknowledgements I would like to thank Dr. Allen D. Hunter for his guidance throughout my studies and research at Youngstown State University. I would like to thank Dr. Matthias Zeller for his patience. He gave me the opportunity to gain valuable experience and knowledge, which is carrying me through my current graduate studies. I would also like to thank Dr. Sherri R. Lovelace-Cameron and the Hunter group for their insights and suggestions while completing this thesis. I thank my family and friends for their support. Last and most importantly I thank my fiance, John L. Payton for his encouragement and understanding. Without his love and support, I would have not completed this thesis. v Table of Contents Page Abstract 111 Acknowledgements IV Table ofContents V List ofFigures x List ofTables xu List ofEquations X111 List ofAbbreviations xvu Chapter 1. Introduction Section One: Organometallic Structure and Bonding 1 Section Two: Organometallic Polymers and Dendrimers 14 Section Three: Organometallic Nanomaterials 1.3.1. Introduction 20 1.3.2. Requisite Organic and Organometallic Reagents 22 1.3.3. Characterization ofOrganometallic Building Blocks 29 Section Four: References 31 Chapter 2. Experimental 2.1 Reagents and reaction conditions 35 2.2 Syntheses 1. Synthesis ofthe formamides 1a. Preparation of l,4-bis(N-formylamino)benzene 36 VI lb. Preparation of 1,4-bis(N-formylamino)-2,3,5,6- 37 tetramethylbenzene 2. Synthesis ofthe isonitriles 2a. Preparation of 1,4-diisocyanobenzene 39 2b. Preparation of 1,4-bisisocyano-2,3,5,6-tetramethylbenzene 40 3. Synthesis ofthe chelating phosphines 3a. Preparation of I,2-bis(di-p-anisylphosphino)ethane 42 3b. Preparation of I ,2-bis(di-p-tolylphosphino)ethane 44 4. Synthesis ofthe dinitrogen complexes 4a. Preparation ofbis[I,2-bis(di-p-tolylphosphino)ethane]bis 46 (dinitrogen)molybdenum(O) 4b. Synthesis ofbis[I ,2-bis(di-p-anisylphosphino)ethane]bis 47 (dinitrogen) molybdenum(0) 5. Synthesis ofthe carbonyl "caps" Sa. Synthesis ofbis[l,2-bis(di-p-tolylphosphino)ethane] 49 dinitrogencarbonylmolybdenum(O) 6. Synthesis of first generation nanorods containing monofunctional isonitriles 6a. Attempted preparation of l-isocyano-4-methoxybenzene-bis-(1,2- 50 bis(di-p-tolylphosphino)ethane)carbonylmolybdenum(0) 7. Synthesis ofzero generation nanorods containing monofunctional isonitriles Vll 7a. Preparation ofbis(1-isocyano-4-methoxybenzene)bis[1,2-bis(di-p- 52 anisylphosphino)ethane]molybdenum(O) 8. Synthesis ofzero generation nanorods containing bisfunctional isonitriles 8a. Preparation ofbis(1 ,4-diisocyanobenzene)bis[1,2-bis(di-p- 54 anisylphosphino)ethane]molybdenum(O) 8b. Preparation ofBis(2,3,5,6-tetramethyl-1,4-diisocyano 56 benzene)bis[1,2-bis(di-p-tolylphosphino)ethane] molybdenum(O) 8c. Preparation ofbis(l,4-diisocyanobenzene)bis[1,2-bis(di-p- 58 ethylphenylphosphino)benzene]molybdenum(O) 9. Synthesis ofthe iron complexes 9a. Synthesis of(dicarbonyl)(ll-cyc1opentadienyl) 60 (tetrahydrofuran)iron(II)tetrafluoroborate 10. Synthesis offirst generation nanorods containing bisfunctional isonitriles lOa. Attempted preparation of f..l- {bis[tetramethyl-1 ,4- 62 (diisocyano)benzene]bis[1,2-bis(di-p-tolylphosphino) ethane]molybdenum(O)}bis[(dicarbonyl)( 1]5-cyc1opentadienyl) iron(II)] lOb. Preparation of f..l- {bis(1 ,4-diisocyanobenzene)bis[1,2-bis(di-p- 64 ethylphenylphosphino)benzene]molybdenum(O)}bis[(chromium pentacarbonyl)] viii lOco Preparation of 11- {bis[2,3,5,6-tetramethyl-l,4-(diisocyano) 66 benzene]bis[1,2-bis(di-p-tolylphosphino)ethane]molybdenum (O)}bis[(chromium pentacarbonyl)] References 68 Chapter 3. Results and Discussion 1. Formamide synthesis 70 2. Isonitrile synthesis 71 3. Chelating phosphines 72 4. Dinitrogen complexes 73 5. Carbonyl capped complexes 74 6. First generation nanorods containing monofunctional isonitriles 6a. l-isocyano-4-methoxybenzene-bis-(1,2-bis(di-p- 78 tolylphosphino)ethane)carbonylmolybdenum(O) 7. Zero generation nanorods containing monofunctional isonitriles 7a. Bis(1-isocyano-4-methoxybenzene)bis[1,2-bis(di-p- 79 anisylphosphino)ethane]molybdenum(O) 8. Zero generation nanorods containing bisfunctional isonitriles 8a. Bis(1,4-diisocyanobenzene)bis[1,2-bis(di-p-anisylphosphino) 80 ethane]molybdenum(O) 8b. Bis(2,3,5,6-tetramethyl-l,4-diisocyanobenzene)bis[l,2-bis(di-p- 82 tolylphosphino)ethane]molybdenum(O) 8c. Bis(l,4-diisocyanobenzene)bis[1,2-bis(di-p- 84 ethylphenylphosphino)benzene] molybdenum(O) IX 8d. Bis(2,3,5,6-tetramethyl-1,4-diisocyanobenzene)bis[l,2-bis(di(p­ 85 ethy1pheny1)phosphino)benzene]mo1ybdenum(0) 9. Synthesis ofthe iron complexes 9a. (Dicarbonyl)(r/-cyclopentadienyl)(tetrahydrofuran)iron(ll) 86 tetrafluoroborate 10. Iron-capped first generation nanorods lOa. J.!- {bis[tetramethyl-1 ,4-(diisocyano)benzene]bis[1,2-bis(di-p­ 87 tolylphosphino)ethane]molybdenum(O)}bis[(dicarbonyl)(ll­ cyclopentadienyl)iron(ll)] 11. Chromium-capped first generation nanorods lla. J.!- {bis(1,4-diisocyanobenzene)bis[1,2-bis(di-p-ethylphenyl 88 phosphino)benzene]molybdenum(O)}bis[(chromiumpentacarbonyl)] llb. J.!- {bis[2,3,5,6-tetramethyl-1,4-(diisocyano)benzene]bis[1,2-bis(di­ 89 p-tolyl phosphino)ethane]molybdenum(O)}bis[(chromium pentacarbonyl)] References 95 Chapter 4. Conclusion 97 Appendix 1. 98 Appendix 2. 100 x List of Figures Figure Page 1.1.1 Metal "acting" as a Lewis acid. 1 1.1.2 A Dewar-Chatt-Duncanson representation ofthe bonding ofthe 5 carbonyl ligand to a transition metal. 1.1.3 Valence Bond Theory representation ofthe bonding ofthe carbonyl 6 ligand. 1.1.4 A Dewar-Chatt-Duncanson model representation ofthe bonding ofan 7 isocyanide ligand to a transition metal. 1.1.5 Valence Bond Theory model for the isocyanide ligand. 8 1.1.6 A Dewar-Chatt-Duncanson model representation for the bonding ofan 9 alkene ligand to a transition metal. 1.1.7 Valence Bond Theory representation ofthe bonding ofa metal-olefin 10 and metallocydopropane. 1.1.8 A Dewar-Chatt-Duncanson representation for the bonding ofthe 11 bidentate dppe ligand to a transition metal. 1.1.9 A Dewar-Chatt-Duncanson model representation for the bonding ofa 12 dinitrogen ligand to a transition metal. 1.1.10 Valence Bond Theory representation ofthe bonding ofa dinitrogen 12 ligand to a transition metal. 1.2.1 Structures ofa polyphosphazene, polysiloxane, and polysi1ane. 15 xi 1.2.2 Transition metal based polymers containing ferrocene organosiloxane 16 spacers. 1.2.3 Example ofa rigid-rod metal polyyne. 17 1.2.4 Some examples ofmain-chain organometallic polymers. 17 1.2.5 A first generation organometallic dendrimer. 18 1.3.1 Organometallic polymer containing aromatic isocyanides. 20 1.3.2 Free isonitriles bridging molecular wire junctions. 21 1.3.3 Metal phosphine center bridging aromatic isonitriles. 21 1.3.4 Possible geometries ofhomoleptic metal complexes. 22 1.3.5 Examples ofsome chelating phosphines. 24 3.1 Possible mechanistic scheme for the reaction ofbenzyl propionate 76 with a dinitrogen complex. 1.1 ORTEP plot of 1,2-Bis(ditolylphosphino)ethane. 99 2.1 ORTEP plot of 'l75-Cyclopentadienyl-dicarbonyl-iodo-iron. 101 xu List ofTables Table Page 1.1.1 Structure and bonding properties ofsome commonly encountered ligands. 3 1.1 X-ray crystal data of 1,2-bis(ditolylphosphino)ethane. 98 1.2 X-ray data collection of 1,2-bis(ditolylphosphino)ethane. 98 1.3 X-ray refinement of 1,2-bis(ditolylphosphino)ethane. 99 1.4 X-ray geometric parameters of 1,2-bis(ditolylphosphino)ethane. 99 2.1 X-ray crystal data of rl-cyclopentadienyl-dicarbonyl-iodo-iron. 100 2.2 X-ray data collection of r,s-cyclopentadienyl-dicarbonyl-iodo-iron. 100 2.3 X-ray refinement of r,s-cyclopentadienyl-dicarbonyl-iodo-iron. 101 2.4 X-ray geometric parameters of r,s-cyclopentadienyl-dicarbonyl-iodo-iron.