Platinum(II) benzophenone imine complexes and the crystal structure of trans-(N,N)-(benzophenone imine)chloro-[2-(1-imino-1-phenylmethyl)phenylido]-platinum(II)-acetone (2/1)

Syntheses and characterisation by H-1 NMR and IR of the platinum(II) complexes [PtI2(Ph2C=NH)(2)], [PtCl2(Ph2C=NH)(2)], [PtCl(Ph(Ph-H)C=NH)-(NH2CH2CH2NH2)] and trans-(N,N)-[PtCl(Ph(Ph-H)C=NH)(Ph2C=NH)] are described. Absorption and emission spectra at room temperature for the latter complex are reported. The crystal structure of trans-(N,N)[PtCl(Ph(Ph-H)C=NH)(Ph2C=NH)] . 1/2{(CH3)(2)CO} was determined by X-ray diffraction methods. Space group C2/c, a = 14.318(4) Angstrom, b = 22.854(4) Angstrom. c = 15.212(3) Angstrom and beta = 108.42(2)degrees using 10 368 reflections in the refinement of 291 parameters gave R = 0.037 and wR2 = 0.074 (for all data). The ligands surround platinum in a planar configuration with bond lengths of Pt-Cl 2.404(1) Angstrom, Pt-N (monodentate imine ligand) 2.004(3) Angstrom, Pt-N (bidentate imine ligand) 1.979(3) Angstrom and Pt-C 1.988(3) Angstrom. The chemical shifts in the H-1 NMR spectrum of trans-(N,N)-[PtCl(Ph(Ph-H)C=NH)(Ph2C=NH)] (in CDCl3) display variations with concentration of the complex that indicate dimerisation. The dimerisation constant was determined from the change in chemical shift for the NH proton of the ortho-metalated ligand, K = 1.25(4) M-1 at 300 K. The structure of the dimer in solution is proposed to resemble one of the types of interactions that are encountered between platinum complexes in the solid state.