Disassembly of Diruthenium(IlJlI) Tetraacetate with P-N Donor Ligands Ernest Essoun Thesis submitted to the Department of Chemistry as partial fulfillment of the requirements for the degree of Master of Science St. Francis Xavier University Antigonish, Nova Scotia Thesis Supervisor: Dr. M.A.S. 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Canada Abstract Mixed-valent diruthenium(II,III) tetraacetate, [Ru2(jx-02CCH3)4(H20)2](PF6), was reacted with various bidentate P-N donor ligands. These reactions lead to the partial displacement of some of the bridging carboxylate groups and concomitant cleavage of the Ru-Ru bond, producing novel complexes. Disassembly reactions with the aminophosphines, diphenyl-2-pyridylphosphine (dpppy) and 2-(diphenylphosphino)ethylamine (dppea), produce the homoleptic tris-chelated complexes, 7&c-[Ru(dpppy-P,iV)3](PF6)2 (HI) and mer-[Ru(dppea-P,iV)3](PF6)2 (VI), respectively. Disassembly reactions with the aromatic aminophosphines, 2-(diphenylphosphino)methylpyridine (dppmpy) and 2-(diphenylphos- phino)ethylpyridine (dppepy), lead to the heteroleptic tris-chelated complexes cis, cis,trans- [Ru(dppmpy-P, ^(r^-C^CCHa)](PF 6>MeOH (IV) and cis.cis.trans- [Ru(dppepy-P,iV)2(Ti2-02CCH3)](PF6) (V), respectively, whereas reaction with the non- cyclic aminophosphine, 3-(diphenylphosphino)-l-propylamine (dpppa) and non-cyclic iminophosphine, 2-(diphenylphosphino)benzylidinebenzylamine (dppbba), lead to the A , heteroleptic tris-chelated complexes cis, cis, /rons-[Ru(dpppa-/ 1/^(ri -O2CCH3XKPF6)- •EtOH (VII) and cw,cis,/r<am-[Ru(dppbba-P,AT)2(n2-02CCH3)](PF6)*2Me0H»H20 (VIII), respectively. All complexes were characterized using elemental analysis; FT-IR, UV-vis and NMR spectroscopies; electrochemistry and X-ray crystallography. Electrochemical studies (CV, OSWV) of the complexes showed that the homoleptic tris-chelated complexes had higher oxidation potentials (Epa) than the corresponding heteroleptic tris-chelated complexes, due to the weak Jt-acceptor ability of the acetate group. Of all the complexes studied, both homo- and heteroleptic, ^c-[Ru(dpppy-P,iV)3](PF6)2 (HI) had the highest Epa as it contained the strongest ii combination of ^-accepting groups (i.e. three phosphine and three pyridyl groups). The Epa values of the heteroleptic complexes were found to be in the order: dppbba (CH=N) > dppmpy, dppepy (py) > dpppa (NH3), since amine are much poorer (essentially nonexistent) a-acceptors compared to the pyridyl and imino groups. Complexes (ID), (VI) and (VII) showed irreversible oxidation waves, while complexes (IV), (V) and (VIII) showed a quasi-reversible one electron processes with varying chemical reversibility. iii Acknowledgements First and foremost I would like to express my sincere gratitude to my supervisor Dr. Manuel Aquino from whom I have learnt so much and for the opportunity to do this research work. Thank you for your guidance and endless encouragement throughout. I would like to thank the other research students that worked in the Aquino lab; Ian Arbuckle, Sam Minaker, Travis Lundrigan and Brandon Groves. Also, I would like to acknowledge Ian Wyman, Terri Clarice, Luc Boudreau and Dr. Ramesh Vadavi who started this study of the disassembly reactions. To members of the Department of Chemistry, thank you for your advice and guidance. I also wish to thank the lab technicians for their help and use of equipment and supplying most of the chemicals. I would like to thank my parents, Francis Essoun and Grace Essoun-Brew, sisters and brothers for their support. iv Table of Contents Abstract ii Acknowledgements iv Table of Contents v List of Tables viii List of Figures x List of Reaction Schemes xiv List of Abbreviations xv List of Ligand Structures xix List of Complex Structures xx CHAPTER 1: Introduction 1 1.1 Non-disassembly (or traditional) Processes of Complex Synthesis 2 1.2 The Disassembly Process 16 1.3 Research Aims 27 CHAPTER 2: Experimental 29 2.1 Reagents 29 2.2 Solvents 29 2.3 Synthesis 30 2.3.1 Synthesis of Starting Materials 30 2.3.1.1 Tetra-|i-acetatodiruthenium(II,III) chloride 30 2.3.1.2 Bis(aquo)tetra-p.-acetatodiruthenium(II,III) 30 hexafluorophosphate v 2.4 Synthesis of P-N donor ligands 31 2.4.1 2-(diphenylphosphino)benzylidinemethylamine 31 2.4.2 2-(diphenylphosphino)benzylidinebenzylamine 32 2.5 Synthesis of Novel Complexes 33 2.5.1 Tris(diphenyl-2-pyridylphosphino-P,N)ruthenium(II) 33 bis(hexafluorophosphate) (HI) 2.5.2 (Acetato-0,0')-bis[2-(diphenylphosphino)methylpyridyl- 34 P,N]ruthenium(II)hexafluorophosphate (TV) 2.5.3 (Acetato-0,0')-bis[2^(2-diphenylphosphino)ethylpyridyl- 34 P ,N]ruthenium(II)hexafluorophosphate (V) 2.5.4 Tris[2-(diphenylphosphino)ethylamino-P,N]ruthenium(II) 35 bis(hexafluoiophosphate) (VI) 2.5.5 (Acetato-0,0')-bis[3-(diphenylphosphino)-l-propylamino- 35 P,N]ruthenium(II)hexafluorophosphate (VII) 2.5.6 (Acetato-0,0')-bis[2-(diphenylphoshino)benzylidinebenzyl- 36 amino-P,N]ruthenium(n)hexafluorophosphate (VIII) 2.5.7 Recrystallization 36 2.6 Physical Measurement 37 2.6.1 Elemental Analysis 37 2.6.2 Infrared Spectroscopy 37 2.6.3 Electronic Spectroscopy 37 2.6.4 Nuclear Magnetic Resonance (NMR) Spectroscopy 38 2.6.5 Electrochemistry 38 2.6.6 X-ray Crystallography 39 vi CHAPTER 3: Results and Discussion 40 3.1 Synthesis of Diruthenium(II,III) Tetraacetate Complexes 40 and their Disassembly 3.2 Elemental Analysis 43 3.3 Infrared Spectroscopy 46 3.4 Electronic Spectroscopic 58 3.5 Nuclear Magnetic (NMR) Spectroscopy 63 3.6 X-ray Crystallography 77 3.7 Electrochemistry 108 CHAPTER 4: Conclusions and Future Work 128 References 134 Appendix 140 Appendix A.1: X-ray data of [Ru(dpppy-P,iV)3](PF6)2 (III) 140 Appendix A.2: X-ray data of 158 2 [Ru(dppmpy-P,AD2(tl -02CCH3)](PF6)«MeOH(IV) Appendix A.3: X-ray data of 171 2 [Ru(dppepy-P)iV)2(ti -O2CCH3)](PF6)-0.5MeOH(V) Appendix A.4: X-ray data of [Ru(dppea-P,iV)3](PF6)2,2Et0H*H20 (VI) 188 Appendix A.5: X-ray data of 206 [Ru(dpppa-P,AW-02CCH3)](PF6)«EtOH(VII) Appendix A.6: X-ray data of 216 > 2 [Ru(dppbba-/ ,iV)2(Tl -02CCH3)](PF6)«2Me0H-H20(Vin) vii List of Tables Table Description Page 3.1 Elemental Analysis of [Ru(dpppy-P,7V)3](PF(HI) 44 r 2 3.2 Elemental Analysis of |1Ru(dppmpy-.P>A )2(Tl -02CCH3)](PF6)*MeOH (IV) 44 3.3 Elemental Analysis of [Ru(dppepy-.P,A^r^-C^CCHs)](PF6) (V) 44 3.4 Elemental Analysis of [Tlu(dppea-.P)A')3](PF6)2 (VI) 45 2 3.5 Elemental Analysis of [Ru(dpppa-/>,iV)2(n -02CCH3)](PF6)«Et0H (Vn) 45 3.6 Elemental Analysis of 45 2 [Ru(dppbba-P,JV)2(Ti -02CCH3)](PF6)'2Me0H-H20(Vra) 3.7 FT-IR Data for [Ru2(n-02CCH3)4C1 49 3.8 FT-IR Data for [Ru2(m-02CCH3)4(H20)2](PF6) 50 3.9 FT-IR Data for [Ru(dpppy-P, AOaKPFsk (HI) 51 2 3.10 FT-IR Data for [Ru(dppmpy-P,iV)2(T1 -02CCH3)](PF6)-Me0H (IV) 52 2 3.11 FT-IR Data for [Ru(dppepy-P,^(n -02CCH3)](PF6) (V) 53 3.12 FT-IR Data for [Ru(dppea-/>,7V)3](PF6)2 (VI) 54 2 3.13 FT-IR Data for [Ru(dpppa-P,iV)2(ri -02CCH3)](PF6)-Et0H(Vn) 55 2 3.14 FT-IR Data for [Ru(dppbba-P,iV)2(n -02CCH3)](PF6>2Me0H*H20 (VIII) 56 3.15 Asymmetric and Symmetric Carboxylate (C02) IR bands for 57 various complexes 3.16 UV-vis Bands for Complexes (III) to (VIII) 62 3.17 31P NMR Data of Complexes (HI) to (VIII) 70 3.18 Crystallographic Data for [Ru(dpppy-P,iV)3](PF6)2 (HI) 78 3.19 Selected Bond Lengths and Bond angles of [R^dpppy-P.A^KPFg^ (HI) 80 2 3.20 Crystallographic Data for [Ru(dppmpy-P,iV)2(T| -02CCH3)](PF6)*Me0H (IV) 81 viii 3.21 Selected Bond Lengths and Bond angles of 83 [Ru(dppmpy-/,,iV)2(ti2-02CCH3)](PF6)*MeOH(rV) 3.22 Ciystallographic Data for [Ru(dppepy-P,A%Tf-02CCH3)](PF6) (V) 84 3.23 Selected Bond Lengths and Bond angles of 86 2 [Ru(dppepy-/»,A02(Tl -O2CCH3)](PF6) (V) 3.24 Crystallographic Data for [Ru(dppea-P,^/)3](PF6)2 (VI) 87 3.25 Selected Bond Lengths and Bond angles of 89 [Ru(dppea-P,^03](PF6)2 (VI) 2 3.26 Crystallographic Data for [Ru(dpppa-P,A%ti -02CCH3)](PF6)*EtOH (VII) 90 3.27 Selected Bond Lengths and Bond angles of 92 y [Ru(dpppa-P,A^(Ti -02CCH3)](PF6)-Et0H(VII) 3.28 Ciystallographic Data for 93 2 [Ru(dppbba-P,iV)2(Ti -02CCH3)](PF6)-2Me0H»H20 (VW) 3.29 Selected Bond Lengths and Bond angles of 95 2 [Ru(dppbba-P,^)2(Ti -02CCH3)](PF6)«2Me0H«H20 (Vffl) 3.30 Selected Ru-P Bond Lengths as function of trans atoms 103 3.31 Selected Ru-N Bond lengths as function of hybridization and trans 104 influence 3.32 Cyclic Voltammetry Data for the Ru2+/3+ couple of Complexes 119 (ID) through (VIII) vs.