Heterobimetallic ruthenium-zinc complexes with bulky N-heterocyclic carbenes: Syntheses, structures and reactivity

Abstract

The ruthenium-zinc heterobimetallic complexes, [Ru(IPr) 2 (CO)ZnMe][BAr F4 ] (7), [Ru(IBiox6) 2 (CO)(THF)ZnMe][BAr F4 ] (12) and [Ru(IMes)'(PPh 3 )(CO)ZnMe] (15), have been prepared by reaction of ZnMe 2 with the ruthenium N-heterocyclic carbene complexes [Ru(IPr) 2 (CO)H][BAr F4 ] (1), [Ru(IBiox6) 2 (CO)(THF)H][BAr F4 ] (11) and [Ru(IMes)(PPh 3 )(CO)HCl] respectively. 7 shows clean reactivity towards H 2 , yielding [Ru(IPr) 2 (CO)(η 2 -H 2 )(H) 2 ZnMe][BAr F4 ] (8), which undergoes loss of the coordinated dihydrogen ligand upon application of vacuum to form [Ru(IPr) 2 (CO)(H) 2 ZnMe][BAr F4 ] (9). In contrast, addition of H 2 to 12 gave only a mixture of products. The tetramethyl IBiox complex [Ru(IBioxMe 4 ) 2 (CO)(THF)H][BAr F4 ] (14) failed to give any isolable Ru-Zn containing species upon reaction with ZnMe 2 . The cyclometallated NHC complex [Ru(IMes)'(PPh 3 )(CO)ZnMe] (15) added H 2 across the Ru-Zn bond both in solution and in the solid-state to afford [Ru(IMes)'(PPh 3 )(CO)(H) 2 ZnMe] (17), with retention of the cyclometallation.