Binuclear organoplatinum(II) complexes with double bis(diphenylphosphino)acetylene bridges: Synthesis, X-ray structure determination, electronic structures and DFT calculations

Abstract

The organoplatinum complexes cis-[PtAr2(SMe2)2] (Ar = p–MeC6H4 and p–MeOC6H4) and cis,cis-[Me2Pt(μ-SMe2)2PtMe2] react very easily - in acetone at room temperature - with 1 or 2 equiv 1,1′–bis(diphenylphosphino)acetylene (= dppac), to give the diplatinum(II) complexes [Pt2R4(μ–dppac)2], (1, R = Me; 2, R = p–MeC6H4; 3, R = p–MeOC6H4) in which two square-planar R2Pt units are held together by two bridging dppac ligands. All the complexes were characterized using multinuclear (1H, 31P and 195Pt) NMR spectroscopy and single crystal X-ray structure determination. Investigation of electronic structures and related DFT and TD-DFT calculations supported a mixed 1IL (intraligand charge transfer)/1MLCT (metal-to-ligand charge transfer) for R = Me and L'LCT (ligand-to-ligand charge transfer) for R = p–MeC6H4 and p–MeOC6H4.