Ruthenium Carbene, Vinylidene, and Allenylidene Complexes with a Bis(3,5-dimethylpyrazol-1-yl)acetato Heteroscorpionate Ligand

Abstract

A series of neutral ruthenium(II) carbonyl, carbene, vinylidene, and allenylidene complexes [Ru(bdmpza)(Cl)(L)(PPh 3 )] (L = C(OR‘)R, C CHR, C C CR 2, CO) containing the bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) ligand, an N, N, O heteroscorpionate ligand, have been prepared. Treatment of [Ru(bdmpza)(Cl)(PPh 3 ) 2 ] ( 1a ) with a variety of alkynes HC⋮CR (R = Ph, Tol, Pr, Bu) afforded the vinylidene complexes [Ru(bdmpza)(Cl)( C CHR)(PPh 3 )] ( 2a − d ). The carbonyl complex [Ru(bdmpza)(Cl)(CO)(PPh 3 )] ( 3 ) is formed via oxidative or acid-induced degradation pathways from the vinylidene complexes. Reaction of 1a with the hydroxy-functionalized alkynes HC⋮C(CH 2 ) n OH ( n = 2, 3) yielded the cyclic Fischer type carbene complexes ( 4a ) and ( 4b ). The ruthenium(II) allenylidene complexes [Ru(bdmpza)(Cl)( C C CR 2 )(PPh 3 )] ( 5a, R = Ph; 5b, R = Tol) were prepared by the reaction of 1a with propargyl alcohols HC⋮CC(R) 2 OH via the vinylidene intermediates [Ru(bdmpza)(Cl)( C CHCR 2 OH)(PPh 3 )]. X-ray crystal structures of one structural isomer of the vinylidene complex [Ru(bdmpza)(Cl)( C CHTol)(PPh 3 )] ( 2b ), the carbonyl complex [Ru(bdmpza)(Cl)(CO)(PPh 3 )] ( 3 ), the carbene complex ( 4b - I ), and two structural isomers of [Ru(bdmpza)(Cl)( C C CPh 2 )(PPh 3 )] ( 5a - I and 5a-II ) are reported.