Carbidohexarhenate cluster cores bicapped by mercury with acetate or thiolate ligands

The reaction of [PPh4]3[Re7C(CO)21] (1) with 1 or more equiv of Hg(OAc)2 in dichloromethane provides the monomercury derivative [PPh4]2[Re7C(CO)21HgOAc] (2) in high yield. However, in the presence of methanol the reaction of 1 with 2 equiv of Hg(OAc)2 yields the dimercury hexarhenium cluster compound [PPh4]2[Re6C(CO)18(HgOAc)2] (3) together with the dirhenium complex [PPh4][Re2(CO)6(mu-OMe)2(mu-OAc)] (4). The dimercury compound 3 reacts with various thiols HS-Z to form thiolate-substituted derivatives [PPh4]2[Re6C(CO)18(HgSZ)2] [Z = C6H4Br (5); C5H4N (6); C2H4COOH (7)]. All new compounds have been characterized by a combination of analytical and spectroscopic data, and the molecular structures of compounds 3-6 have been determined by X-ray crystallography.