The influence of metal coordination on ligand geometry: the structure of N- t-butyl-2-(diphenylphosphino)benzylammoniumchloride and ( N- t-butyl-2-(diphenylphosphino)benzylamine)diacetatepalladium(II)

Abstract

The structures of N- t-butyl-2-(diphenylphosphino)benzylammoniumchloride and N- t-butyl-2-(diphenylphosphino)benzylaminediacetatepalladium(II) have been determined by X-ray crystallography. The Pd-complex was prepared by treating palladiumdiacetate with N- t-butyl-2-(diphenylphosphino)benzylamine in CH 2Cl 2 for 4 h at room temperature. The organic compound crystallises in the monoclinic space group P2 1/ c with cell dimensions a=13.664(3), b=15.635(3), c=10.408(2) A ̊ , β=100.14(3)°, V=2188.7(8) A ̊ 3 and Z=4, synchrotron radiation, λ=0.9836 A ̊ . The Pd-compound crystallises in the orthorhombic space group Pna2 1 with cell dimensions a=15.444(3), b=13.233(3), c=12.730(3) A ̊ , V=2601.6(9) A ̊ 3 and Z=4, Mo Kα radiation. Both structures were solved by direct methods and the refinements resulted in the R-values 0.080 and 0.037, respectively. N- t-butyl-2-(diphenylphosphino)benzylammoniumchloride has an extensive hydrogen bonding with two bridging Cl − between the ammonium groups from two different organic ligands. The bi-dentate ligand binds to palladium(II) via both phosphorus and nitrogen, while two acetate bind via one of their oxygens forming a pseudo square-planar coordination around palladium. The Pd–N distance is 2.075(3) Å, Pd– P=2.2133(9) A ̊ and the Pd–O distances are 2.041(3) Å ( trans to N) and 2.092(2) Å ( trans to P). Half-normal probability plot analysis indicates that the s.u.'s are underestimated in at least one of the investigated structures. Complexation with palladium influences torsion-angles in the amine side-chain in N- t-butyl-2-(diphenylphosphino)benzylamine as well as bond-angles around the N and P atoms, clearly a consequence of the formation of the chelate, while the crystal packing influences the orientation of the phenyl rings.