The influence of metal coordination on ligand geometry: the structure of 2-(diphenylphosphino)acetophenone and bis(2-(diphenylphosphino)acetophenone)palladium(II)bistriflate

The structures of 2(diphenylphosphino)acetophenone and bis(2(diphenyl phosphino)acetophenone)palladium(II)bistriflate have been determined by X-ray crystallography. The ligand is of interest because its P,O donor set combines the hard and soft properties. In the Pd-complex, which was prepared by treating tetrakisacetonitrile-palladium-bistriflate with 2-(diphenylphosphino)acetophenone in dichloromethane for 4 h at room temperature, the O-coordination provides a masked coordinative unsaturation. The ligand crystallises in the monoclinic space group P2(1)/c with cell dimensions a = 11.050(2), b = 16.052(3), c = 9.7082(19) Angstrom, beta = 109.58(3)degrees, V = 1622.4(6) Angstrom(3) and Z = 4, synchrotron radiation, lambda = 0.8520 Angstrom. The Pd-complex crystallises in the orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 11.867(2), b = 18.162(4), c = 19.603(4) Angstrom, V 4224 9(15) Angstrom(3) and Z = 4, MoKalpha radiation. Both structures were solved by direct methods and the refinements resulted in the R-values of 0.059 and 0.043, for the organic compound and the palladium compound, respectively. Two bi-dentate ligand binds to palladium(II) in a cis-configuration. The Pd-O distances are 2.060(3) and 2.096(2) Angstrom and the Pd-P distances 2.2290(10) and 2.2294(10) Angstrom, showing a large trans-influence of the phosphorus atoms. Half-normal probability plot analyses indicate that the s.u.'s are largely underestimated in the investigated structures. The bond-angles around the phosphorus atom and the orientation of the keto-substituted phenyl rings as well as the orientation of the keto-groups are highly affected by metal complexation.