SYNTHESES, PHOTOPHYSICS, AND X-RAY STRUCTURAL CHARACTERIZATION OF DINUCLEAR PLATINUM(II) ACETYLIDE COMPLEXES, [PT2(MU-DPPM)2(MU-PHCC)(PHCC)2]CLO4 AND [PT2(MU-DPPM)2(MU-TBUCC)(TBUCC)CL]CLO4

Refluxing an ethanolic solution of [Pt(dppm-P,P')2]Cl2 with Hg(PhC=C)2 in ethanol gave air-stable [Pt2(mu-dppm)2(mu-PhC=C)(PhC=C)2]+ as the major product, isolated as the Cl- or ClO4-(1) salt. A similar reaction with Hg((t)BuC=C)2 gave [Pt2(mu-dPPM)2(mu-(t)BuC=C)((t)BuC=C)Cl]+ instead, also isolated as the Cl- or ClO4- (2) salt. The crystal structures of 1 and 2 have been determined by X-ray diffraction. Compound 1 crystallizes in the monoclinic space group C2/c with Z = 4 in a unit cell of dimensions a = 27.942(7) angstrom, b = 11.218(4) angstrom, c = 25.720(7) angstrom, and beta = 124.22(2)-degrees. Compound 2 crystallizes in the triclinic space group P1BAR with Z = 2 in a unit cell of dimensions a = 11.783(3) angstrom, b = 12.791(3) angstrom, c = 21.210(7) angstrom, a = 89.11(3)-degrees, beta = 77.41(2)degrees, and gamma = 71.50(2)-degrees. Both structures have been solved by Patterson and Fourier methods and refined by full-matrix least squares on the basis of 5203 observed reflections to R and R(w) values of 0.038 and 0.048 for 1 and 9724 observed reflections to R and R(w) values of 0.033 and 0.044 for 2, respectively. Both complexes have been found to exhibit long-lived photoluminescence both in the solid state and in fluid solutions (solid-state emission: 1, lambda(em) = 618 nm, tau(o) = 2.2 +/- 0.2 mus; 2, lambda(em) = 621 nm, tau(o) = 3.5 +/- 0.3 mus). The phosphorescent state of 1 has been shown to be quenched by pyridinium acceptors.