Ruthenium Acetate Complexes as Versatile Probes of Metal–Ligand Interactions: Insight into the Ligand Effects of Vinylidene, Carbene, Carbonyl, Nitrosyl and Isocyanide

Reaction of cis ‐Ru(κ 2 ‐OAc) 2 (PPh 3 ) 2 with two‐electron donor ligands L results in the formation of complexes trans ‐[Ru(κ 1 ‐OAc)(κ 2 ‐OAc)L(PPh 3 ) 2 ] (L = CO, NO + , CN t Bu). Vinylidene complexes (L = C=CHR) may be prepared from the corresponding reaction with terminal alkynes HC≡CR, and species containing hydroxyvinylidene ligands (L = C=CHCR 1 R 2 {OH}) may be prepared from related reactions with propargyl alcohols HC≡CCR 1 R 2 {OH}. Treatment of cis ‐Ru(κ 2 ‐OAc) 2 (PPh 3 ) 2 with ω‐alkynols HC≡C(CH 2 ) n OH ( n = 2–4) results in the formation of oxacyclocarbene complexes [L = CCH 2 (CH 2 ) n O]. An analysis of the spectroscopic data and the structural metrics (as determined by X‐ray crystallography) of this series of complexes allows for the relative donor/acceptor properties of the ligand L to be evaluated. This comparison indicates that the vinylidene ligand behaves in a similar fashion to the isocyanide ligand.