Syntheses, Structures, and Properties of Tricarbonyl Rhenium(I) Heteronuclear Complexes with a New Bridging Ligand Containing Coupled Bis(2-pyridyl) and 1,2-Dithiolene Units

A new type of polypyridine ligand containing coupled bis(2-pyridyl) and cyanoethylthio-protected dithiolene, 4,5-bis(2-cyanoethylthio)-2-bis(2-pyridyl)methylene-1,3-dithiole (BPyDT(SCH2CH2CN)2, 3), two mononuclear complexes, BrRe(CO)3(BPyDT(SCH2CH2CN)2) (4) and BPyDTS2Pt(dbbpy) (7), and one homodinuclear complex, BPyDT(SAuPPh3)2 (5), have been synthesized and characterized. With the deprotected polypyridine ligand BPyDTS22− as the bridging unit, one tricarbonyl rhenium(I) heterotrinuclear complex, ClRe(CO)3(BPyDT(SAuPPh3)2) (6), and one heterodinuclear complex, ClRe(CO)3(BPyDTS2Pt(dbbpy)) (8, dbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine), have been studied. The structures of all these compounds have been determined by X-ray crystallography. UV–vis studies have been carried out for them, showing distinct electronic absorptions. Compounds 3–6 exhibit blue to red luminescence in CH2Cl2 solution at room temperature. Ground-state electronic structures for 3–8 have been analyzed by the B3LYP calculations.