Reactions of Ru(C≡CPh)(L₂)Cp* (L₂ = dppm, dppe) with tetracyanoethene: cycloaddition, formation of monodentate dppm and dppmO complexes and migration of CN to ruthenium

Abstract

The reaction of C2(CN)4 with Ru(C≡CPh)(dppm)Cp* in THF has given the anticipated tetracyanobuta-1,3-dien-2-yl complex Ru{C[=C(CN)2]CPh=C(CN)2}(dppm)Cp* (3). In benzene, η3-cyano-enyl complexes complex 3 rearranges to the cyanoruthenium-ylid complex Ru(CN){C(CN)=C[CPh=C(CN)2]PPh2CH2PPh 2}Cp* (6). A possible reaction sequence, involving a zwitterionic intermediate such as Ru(δ-)(CN){C(CN)C(δ+)CPh=C(CN)2}(dppm-P)Cp* D, is discussed. Only the η1-dienyl complex 7 is obtained from Ru(C≡CPh)(dppe)Cp* and TCNE. © 2002 Published by Elsevier Science B.V.