Unusual coordination assemblies from platinum(II) thienyl and bithienyl complexes.

Dinuclear Pt(2)Br(2)(dppf)(2)(mu-C(8)H(4)S(2)) exchanges with isonicotinic acid to release free bithiophene and gives a molecular square [Pt(4)(dppf)(4)(mu(2)-O(2)CC(5)H(4)N)(4)](4+)4OTf(-) which is an "all-ring" system with four Pt rings disposed at the corners of a larger macrocyclic ring. The related mononuclear complex PtBr(eta(1)(C2)-C(4)H(3)S)(dppf) reacts with AgOTf (OTf = triflate) to give [Pt(2)(dppf)(2)(mu(2),eta(1)(C),eta(1)(S)-C(4)H(3)S)(2)](2+)2OTf(-) with an unusual six-membered ring formed by the fusion of two Pt-thienyl entities at the sulfur sites. All the complexes are structurally characterized by single-crystal X-ray crystallography.