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

Abstract

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 4h at room temperature, the O-coordination provides a masked coordinative unsaturation.The ligand crystallises in the monoclinic space group P21/c with cell dimensions a=11.050(2), b=16.052(3), c=9.7082(19)Å,β=109.58(3)°, V=1622.4(6)Å3 and Z=4, synchrotron radiation, λ=0.8520Å. The Pd-complex crystallises in the orthorhombic space group P212121 with cell dimensions a=11.867(2), b=18.162(4), c=19.603(4)Å,V=4224.9(15)Å3 and Z=4, MoKα 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)Å and the Pd–P distances 2.2290(10) and 2.2294(10)Å, 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.