Reaction of Ruthenium Complexes Having both a Phosphite and a Group 14 Element Ligand with a Lewis Acid

Reactions of having an alkyl group (ER3 = Me (1a), CH2SiMe3 (2a)), a silyl group (ER3 = SiMe3 (3a), SiMe2SiMe3 (4a)), a germyl group (ER3 = GeMe3 (5a)), or a stannyl group (ER3 = SnMe3 (6a), SnnBu3 (7a), SnPh3 (8a)) with a Lewis acid (BF3·OEt2 or Me3SiOSO2CF3 (TMSOTf)) have been examined. In the reactions with BF3·OEt2, in any case except for 8a, an OMe abstraction as an anion uniformly takes place at the first stage to give the corresponding cationic phosphenium complex (1b7b). The successive reaction depends on the type of ER3 group. Alkyl complexes (1b and 2b) immediately undergo migratory insertion of the phosphenium ligand into the Ru−C bond, and a subsequent reaction with PPh3 gives the cationic complex (ER3 = Me (1c), CH2SiMe3 (2c)). Silyl and germyl complexes (3b5b) are stable with the Ru−Si and Ru−Ge bonds intact. In contrast, stannyl complexes (6b and 7b) undergo migration of one of the R groups on Sn to give the stannylene complex (R = Me (6e), nBu (7e)). The reactions with another Lewis acid, TMSOTf, exhibit reactivities similar to those with BF3·OEt2, except when ER3 is a stannyl group. In the reaction of 6a, 7a, or 8a with TMSOTf, one of the R groups on Sn is directly abstracted to give the corresponding stannylene complex (R = Me (6f), nBu (7f), Ph (8f)). 8f has been determined to be a doubly base stabilized stannylene complex by single-crystal X-ray diffraction.