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 [(dcypb)ClRu(μ-Cl)3Ru(dcypb)(N2)] (1) with 4 equiv of the stable silylene 1,3-di-tert-butyl-1,3,2-diazasilol-2-ylidene (SiLN 2) yields coordinatively unsaturated RuCl(η3-dcypb)(SiLN 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 31P 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 H2 containing trace H2O yields siloxane dimer [LN 2Si(H)]2O 3 and the ruthenium hydride−H2 adduct [(dcypb)(H)Ru(μ-Cl)2(μ-H)Ru(dcypb)(H2)] (4). Attempts to isolate 4 resulted in serendipitous crystallization of decomposition product 5, [(dcypb)(H)Ru(μ-Cl)3Ru(dcypb)(N2)]. X-ray analysis of 5 revealed a structure closely analogous to that of 4, in which bridging hydride is replaced by chloride, and η2-H2 by η2-N2. Displacement of silylene from 2 is facile: treatment with 1 atm of CO affords free SiLN 2, accompanied by RuCl(η3-dcypb)(CO)2 as a mixture of three isomers (6−8).