SYNTHESIS OF MONOHYDRIDOHEXAMETHYLBENZENERUTHENIUM(II) COMPLEXES CONTAINING GROUP V DONOR LIGANDS. ISOMERISM ARISING FROM CYCLOMETALLATION OF A TERTIARY PHOSPHINE AT ALIPHATIC AND AROMATIC CARBON ATOMS

Article abstract of DOI:10.1016/0022-328X(84)80466-0

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 2, the ligand and sodium carbonate in propan-2-ol.The triarylphosphine complexes 11, 14 and 15 react with methyllithium to give aryl artho-metallated hydridoruthenium(II) complexes such as (22) and 19 similarly gives the isopropyl cyclometallated complex (29) as a mixture of diastereomers.Reaction of 17 with methyllithium gives initially the t-butyl cyclometallated complex (25) which isomerizes by a first order process (k ca. 0.2 h^-1 in C6D6 or THF-d₈ at 50 deg C) to the aryl ortho-metallated complex (26).The similarly generated isopropyl cyclometallated complex (27) has not been isolated in a pure state owing to rapid isomerization to (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(0) complexes Ru(η-C6Me6)L.