Influence of Cyclopentadienyl Ring‐Tilt on Electron‐Transfer Reactions: Redox‐Induced Reactivity of Strained [2] and [3]Ruthenocenophanes |
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| Authors: | Dr Andrew D Russell Prof Joe B Gilroy Prof Kevin Lam Dr Mairi F Haddow Prof Jeremy N Harvey Prof William E Geiger Prof Ian Manners |
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| Institution: | 1. School of Chemistry, University of Bristol, Bristol, BS8?1TS (UK);2. Present Address: Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, ON (Canada) N6A?5B7;3. Department of Chemistry, University of Vermont, Burlington VT 05405‐0125 (USA);4. Present Address: Nazarbayev University, School of Science and Technology, 53 Kabanbay Batyr Ave, Block 7, Office 7107, 0100000, Astana (Republic of Kazakhstan) |
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| Abstract: | In contrast to ruthenocene Ru(η5‐C5H5)2] and dimethylruthenocene Ru(η5‐C5H4Me)2] ( 7 ), chemical oxidation of highly strained, ring‐tilted 2]ruthenocenophane Ru(η5‐C5H4)2(CH2)2] ( 5 ) and slightly strained 3]ruthenocenophane Ru(η5‐C5H4)2(CH2)3] ( 6 ) with cationic oxidants containing the non‐coordinating B(C6F5)4]? anion was found to afford stable and isolable metal?metal bonded dicationic dimer salts Ru(η5‐C5H4)2(CH2)2]2B(C6F5)4]2 ( 8 ) and Ru(η5‐C5H4)2(CH2)3]2B(C6F5)4]2 ( 17 ), respectively. Cyclic voltammetry and DFT studies indicated that the oxidation potential, propensity for dimerization, and strength of the resulting Ru?Ru bond is strongly dependent on the degree of tilt present in 5 and 6 and thereby degree of exposure of the Ru center. Cleavage of the Ru?Ru bond in 8 was achieved through reaction with the radical source (CH3)2NC(S)S?SC(S)N(CH3)2] (thiram), affording unusual dimer (CH3)2NCS2Ru(η5‐C5H4)(η3‐C5H4)C2H4]2B(C6F5)4]2 ( 9 ) through a haptotropic η5–η3 ring‐slippage followed by an apparent 2+2] cyclodimerization of the cyclopentadienyl ligand. Analogs of possible intermediates in the reaction pathway C6H5ERu(η5‐C5H4)2C2H4]B(C6F5)4] E=S ( 15 ) or Se ( 16 )] were synthesized through reaction of 8 with C6H5E?EC6H5 (E=S or Se). |
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| Keywords: | electron‐transfer reactions organometallic chemistry ruthenium |
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