SPECTROSCOPY, PHOTOPHYSICAL PROPERTIES, AND X-RAY CRYSTAL-STRUCTURE OF PLATINUM(II) COMPLEXES OF QUATERPYRIDINE

Two novel platinum quaterpyridine complexes have been synthesized and characterized by H-1 NMR spectroscopy and X-ray crystallography: [Pt(pQP)](ClO4)2 (pQP = 3",5,5',5"'-tetramethyl-2,2':6',2":6",2"'-quaterpyridine), monoclinic C2/c, a = 14.276 (2) angstrom, b = 12.970 (2) angstrom, c = 14.257 (1) angstrom, beta = 102.29 (1)', V = 2579.2 (6) angstrom3, Z = 4; [Pt(QP)](ClO4)2 (QP = 2,2':6',2":6",2"'-quaterpyridine), monoclinic P2(1), a = 5.904 (3) angstrom, b = 12.943 (2) angstrom, c = 14.300 (4) angstrom, beta = 100.70 (4)-degrees, V = 1073.7 (6) angstrom3, Z = 2. The shortest intermolecular Pt-Pt distances in [Pt(pQP)](ClO4)2 and [Pt(QP)](ClO4)2 are 7.249 (2) and 5.904 angstrom, respectively. Both complexes exhibit photoluminescence in the solid state at 700 nm. Only[Pt(pQp)]2+ shows room-temperature emission in acetonitrile (phi(f) = 0.026 +/- 0.001, lifetime at infinite dilution = 7.0 +/- 0.6 mus, self-quenching rate constant = 2.9 +/- 0.4 X 10(8) M-1 s-1). The excited state of [Pt(pQP)]2+ is a powerful oxidant with an E-degrees value of about 2.3 V vs NHE.