Synthesis of monohydridohexamethylbenzeneruthenium(II) complexes containing group V donor ligands. Isomerism arising from cyclometallation of a tertiary phosphine at aliphatic and aromatic carbon atoms |
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Authors: | Martin A Bennett Tai-Nang Huang Jozef L Latten |
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Institution: | Research School of Chemistry, The Australian National University, Box 4, G.P.O., Canberra, A.C.T. 2601 Australia |
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Abstract: | The η-hexamethylbenzenehydridoruthenium(II) complexes RuHCl(η-C6Me6)L (L = PPh3 (11), AsPh3 (12), P(C6H4-p-F)3 (14), P(C6H4-p-Me)3 (15), P(C6H4-p-OMe)3 (16), P-t-BuPh2 (17), P-i-PrPh2 (18), P-i-Pr3 (19), PCy3 (20) and P-t-BuMe2 (21)) have been made by heating RuCl2(η-C6Me6)]2, the ligand and sodium carbonate in propan-2-ol. The triarylphosphine complexes 11, 14 and 15 react with methyllithium to give aryl ortho-metallated hydridoruthenium(II) complexes such as Ph2)(η-C6Me6) (22) and 19 similarly gives the isopropyl cyclometallated complex -i-Pr2(η-C6Me6) (29) as a mixture of diastereomers. Reaction of 17 with methyllithium gives initially the t-butyl cyclometallated complex Ph2)(η-C6Me6) (25) which isomerizes by a first order process (k.2 h?1 in C6D6 or THF-d8 at 50°C) to the aryl ortho-metallated complex -t-BuPh)(η-C6Me6) (26). The similarly generated isopropyl cyclometallated complex Ph2)(η-C6Me6) (27) has not been isolated in a pure state owing to rapid isomerization to -i-PrPh)(η-C6Me6) (28); both 27 and 28 exist as a pair of diastereomers. The formation of the cyclometallated complexes and the isomerizations are thought to involve intermediate 16-electron ruthenium(O) complexes Ru(η-C6Me6)L. |
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Keywords: | Me methyl i-Pr isopropyl Cy cyclohexyl |
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