Synthesis, structure and photophysical properties of mono- and di-nuclear platinum(II) acetylide complexes

The reactions of cis-[PtCl2{P(C6H4CH3-p)3}2] with HCC-C6H4R-p (R = NO2, CH3, OCH3), in the presence of CuCl catalyst, lead to the formation of mono-acetylide complexes trans-[PtCl{P(C6H4CH3-p)3}2(CC-C6H4R-p)] (R = NO2 1; R = CH3 2; R = OCH3, 3). These monochloro-acetylide complexes were further employed for the synthesis of symmetrical dinuclear platinum complexes. Thus, the reactions of HCC-C6H2(2,5-OC4H9)2-CCH with two molar equivalents of 1, 2 and 3, in the presence of CuCl catalyst, affords dinuclear complexes trans-trans-[Pt2{P(C6H4CH3-p)3}4(CC-C6H4R-p)2(CC-C6H2(OC4H9)2-CC)](R = NO2 4; R = CH3 5; R = OCH3; 6). All these mono- and dinuclear platinum complexes have been characterized by IR, 1H NMR, 31P NMR spectroscopy, and the molecular structures of 2 and 5 were unequivocally established by single crystal X-ray diffraction analyses. The thermal stability of these complexes has been studied by thermogravimetric analysis (TGA). The photophysical properties of these materials have been probed using electronic absorption and emission spectroscopy, and z-scan techniques.