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)(PPh3)] (L = C(OR‘)R, CCHR, CCCR2, 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)(PPh3)2] (1a) with a variety of alkynes HC⋮CR (R = Ph, Tol, Pr, Bu) afforded the vinylidene complexes [Ru(bdmpza)(Cl)(CCHR)(PPh3)] (2a−d). The carbonyl complex [Ru(bdmpza)(Cl)(CO)(PPh3)] (3) is formed via oxidative or acid-induced degradation pathways from the vinylidene complexes. Reaction of 1a with the hydroxy-functionalized alkynes HC⋮C(CH2)nOH (n = 2, 3) yielded the cyclic Fischer type carbene complexes (4a) and (4b). The ruthenium(II) allenylidene complexes [Ru(bdmpza)(Cl)(CC CR2)(PPh3)] (5a, R = Ph; 5b, R = Tol) were prepared by the reaction of 1a with propargyl alcohols HC⋮CC(R)2OH via the vinylidene intermediates [Ru(bdmpza)(Cl)(CCHCR2OH)(PPh3)]. X-ray crystal structures of one structural isomer of the vinylidene complex [Ru(bdmpza)(Cl)(CCHTol)(PPh3)] (2b), the carbonyl complex [Ru(bdmpza)(Cl)(CO)(PPh3)] (3), the carbene complex (4b-I), and two structural isomers of [Ru(bdmpza)(Cl)(CCCPh2)(PPh3)] (5a-I and 5a-II) are reported.