Neutral Binuclear and Anionic Trinuclear Rhenium Carbonyl Complexes Containing Bridging Ligands Derived from 2-Amino- and 2-Mercaptopyridines

The reactions of the nitrile-stabilized complex [Re3(μ-H)3(CO)11(MeCN)] (1) and of the unsaturated complex [Re4(μ-H)4(CO)12] (2) with 2-amino-6-methylpyridine (Hampy), 2-mercaptopyridine (Hmerpy), and 2-hydroxy-6-methylpyridine (Hhympy) have been studied. Complex 1 reacts slowly with Hampy and Hmerpy (refluxing toluene, 5−7 h) to give the binuclear derivatives [Re2(μ-ampy)2(CO)6] (3) and [Re2(μ-merpy)2(CO)6] (4), but no reaction is observed between 1 and Hhympy under analogous conditions. Complex 2 reacts with Hampy and Hmerpy (refluxing 1,2-dichloroethane, 10−20 min) to give the trinuclear anionic derivatives [Re3(μ-H)3(μ3-ampy)(CO)9]- (5) and [Re3(μ-H)3(μ3-merpy)(CO)9]- (6), which have been isolated as pyridinium ([H2ampy]5) or triethylammonium ([HNEt3]5, [HNEt3]6) salts. Under analogous conditions, the reaction of 2 with Hhympy gives an inseparable mixture of compounds. The X-ray structures of [HNEt3]5 and [HNEt3]6 confirm that the three edges of the clusters are spanned by hydride ligands, that the am...