A stable silylene in a reactive environment:: Synthesis, reactivity, and silicon extrusion chemistry of a coordinatively unsaturated ruthenium silylene complex containing chloride and η3-P-C-P ligands

Reaction of [(deypb)ClRu(mu-Cl)(3)Ru(dcypb)(N-2)] (1) with 4 equiv of the stable silylene 1,3-di-tert-butyl-1,3,2-diazasilol-2-ylidene (SiL2N) yields coordinatively unsaturated RuCl(eta(3)-dcypb)(SiL2N 2) (2). Complex 2 is a rare example of a trans-spanning diphosphine complex, this geometry resulting from an unprecedented attack of the metal on the tetramethylene ligand backbone. X-ray and solid-state P-31 NMR and IR analysis reveal an agostic interaction between the metal and a silylene Bu-t group. In solution, this interaction is observed only at low temperature. Reaction of 2 with H-2 containing trace H2O yields siloxane dimer [(L2Si)-Si-N(H)](2)O 3 and the ruthenium hydride-H-2 adduct [(dcypb)(H)Ru(mu-Cl)(2)(mu-H)Ru(dcypb)(H-2)] (4). Attempts to isolate 4 resulted in serendipitous crystallization of decomposition product 5, [(dcypb)(H)Ru(mu-Cl)(3)Ru(dcypb)(N-2)]. X-ray analysis of 5 revealed a structure closely analogous to that of 4, in which bridging hydride is replaced by chloride, and eta(2)-H-2 by eta(2)-N-2. Displacement of silylene from 2 is facile: treatment with 1 atm of CO affords free SiL2N, accompanied by RuCl(eta(3)-dcypb)(CO)(2) as a mixture of three isomers (6-8).