SPECTROSCOPIC AND CRYSTALLOGRAPHIC CHARACTERIZATION OF CADMIUM COMPLEXES INCORPORATING A BIDENTATE PHOSPHINE LIGAND

The 1:1 stoichiometric addition of the bidentate phosphine ligand dime thyl-2-sila-1,3-bis(diphenylphosphino)-propane (L-2) to a range of cad mium(II) salts produced a series of moisture-sensitive complexes of ge neral formula [CdX2(L-2)](X = Cl 1, Br, I, SCN or NO3). These complexe s have been investigated by vibrational and multinuclear (P-31 and Cd- 113) NMR spectroscopy and by X-ray crystallography. Complex 1 crystall ises in the orthorhombic space group P2(1)2(1)2(1), with a = 9.2862(10 ), b = 15.386(2), c = 20.724(3) Angstrom, U = 2960.9(6) Angstrom(3) an d Z = 4. The metal centre exhibits four-co-ordinate, tetrahedral geome try, with the ligand bound in a bidentate manner. Both the solution-an d solid-state cross-polarisation magic angle spinning P-31 NMR spectra of the complexes show clearly resolved Cd-113-P-31 and Cd-111-P-31 on e bond couplings in a Cd-113:Cd-111 ratio of 1.044:1.046 as expected. Vibrational spectroscopy indicates that each complex is mononuclear, w ith no evidence for bridging species; [Cd(NO3)(2)(L-2)] features monod entate nitrate groups. The addition of 2 equivalents of the ligand to cadmium perchlorate yields a complex which has been established as [Cd (L-2)(2)][CIO4](2) by spectroscopic and conductance studies.