Bis(diphenylphosphinomethyl)phenylphosphine as a chelating and bridging ligand. The preparations and molecular structures of palladium complexes

Abstract

The following three complexes of bis(diphenylphosphinomethyl)phenylphosphine (dpmp) have been isolated from the reaction of the ligand with palladium chloride complexes: (dpmp)PdCl 2, (CH 3CN)PdCl 2(μ-dpmp)PdCl 2 and (dpmp) 2Pd 3Cl 6. The structures of the first two have been established by X-ray crystallography. (Dpmp)PdCl 2·CH 2Cl 2 crystallizes in the space group P2 1/m (No.11) with cell dimensions (determined at 140 K) of a = 9.864(10), b = 17.513(8), c = 10.706(10) Å, β = 112.85(6)°, Z = 2, V = 1704(3) Å 3. The structure was refined by blocked-cascade least-squares to a conventional R value of 0.073 using 2021 significant data. The structure consists of square planar palladium bound in a six-membered chelate ring. The central phosphorus atom is not coordinated. (Ch 3CN)PdCl 2(μ-pdmp)PdCl 2·CH 3CN crystallizes in the space group P2 12 12 1 (No.19) with cell dimensions (at 140 °K) of a = 12.302(4), b = 12.483(3), c =24.316 Å, Z = 4, V = 3734 Å 3. It was refined as described above to an R value of 0.069 using 3193 significant reflections. The structure consists of two square planar palladium atoms. One is bound to two chlorine atoms and the chelating phosphine. The other palladium is bound to a linear acetonitrile molecule, two trans chlorine atoms, and to the central atom of the triphosphine ligand. The two palladium atoms are separated by 5.854 Å. The chelate ring conformations differ in the two structures ((dpmp)PdCl 2, boat; (CH 3CN)PdCl 2(μ-dpmp)PdCl 2, symmetric skew boat). The flexibility of chelate ring conformation in chelated dpmp coupled with the ability of the central phosphorus to bind a second metal ion suggests that this ligand will be a versatile unit in the preparation of binuclear transition metal complexes.