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

Reactions of having an alkyl group (ER 3 = Me ( 1a ), CH 2 SiMe 3 ( 2a )), a silyl group (ER 3 = SiMe 3 ( 3a ), SiMe 2 SiMe 3 ( 4a )), a germyl group (ER 3 = GeMe 3 ( 5a )), or a stannyl group (ER 3 = SnMe 3 ( 6a ), Sn n Bu 3 ( 7a ), SnPh 3 ( 8a )) with a Lewis acid (BF 3 ·OEt 2 or Me 3 SiOSO 2 CF 3 (TMSOTf)) have been examined. In the reactions with BF 3 ·OEt 2, 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 ( 1b − 7b ). The successive reaction depends on the type of ER 3 group. Alkyl complexes ( 1b and 2b ) immediately undergo migratory insertion of the phosphenium ligand into the Ru−C bond, and a subsequent reaction with PPh 3 gives the cationic complex (ER 3 = Me ( 1c ), CH 2 SiMe 3 ( 2c )). Silyl and germyl complexes ( 3b − 5b ) 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 ), n Bu ( 7e )). The reactions with another Lewis acid, TMSOTf, exhibit reactivities similar to those with BF 3 ·OEt 2, except when ER 3 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 ), n Bu ( 7f ), Ph ( 8f )). 8f has been determined to be a doubly base stabilized stannylene complex by single-crystal X-ray diffraction.