NiN2S2 complexes as metallodithiolate ligands to RhI, RhII and RhIII

Abstract

Three molecular structures are reported which utilize the NiN₂S₂ ligands Ni-1, (bis(mercaptoethyl)diazacyclooctane)nickel and Ni-1′, bis(mercaptoethyl)diazacycloheptane)nickel, as metallodithiolate ligands to rhodium in oxidation states I, II and III. For the Rh^I complex, the NiN₂S₂ unit behaves as a bidentate ligand to a square planar Rh^I(CO)(PPh₃)⁺ moiety with a hinge or dihedral angle (defined as the intersection of NiN₂S₂ and S₂Rh(C)(P) planes) of 115°. Supported by Ni-1′ ligands, the Rh^II oxidation state occurs in a dirhodium C₄ paddlewheel complex wherein four NiN₂S₂ units serve as bidentate bridging ligands to two singly-bonded Rh^II ions at 2.893(8) Å apart. A compilation of the remarkable range of M–M distances in paddlewheel complexes which use NiN₂S₂ complexes as paddles is presented. The Rh^III state is found as a tetrametallic [Rh(Ni-1′)₃]³⁺ cluster, roughly shaped like a boat propeller and structurally similar to tris(bipyridine)metal complexes.