Mono-, Di- and Tetranuclear Complexes and Clusters With Bromine-Functionalized Bis(diphenylphosphino)amine Ligands

Abstract

We report the preparation of bromo-aryl functionalized bis(diphenylphosphino)amine ligands of the type Ph2PNArPPh2 (1, Ar = p-BrC6H4; 2, Ar = p-BrC6H4–C6H4) and their coordination properties. Mono- and dinuclear complexes were formed with Cu(I), Au(I), Pd(II), Pt(II) and tetranuclear cobalt carbonyl clusters were obtained. The crystal structures of [PdCl2(1)] (3), [PdCl2(2)] (4), [(AuCl)(μ-1)] (6), [Co4(CO)5(μ-CO)3(μ-dppa)(μ-1)] (dppa = Ph2PNHPPh2) (8) and [Co4(CO)5(μ-CO)3(μ-dppm)(μ-1)] (dppm = Ph2PCH2PPh2) (9) have been determined by X-ray diffraction. Whereas the diphosphine ligands chelate the metal center in 3 and 4, and in the Pt(II) complex 5 which is analogous to 3, ligand 1 acts as a bridge in 6 where the separation between the two Au(I) centers is 3.0402(5) A. In the tetranuclear clusters 8 and 9, and in the cluster 10 analogous to 9 with 2 as bridging ligand, two orthogonal Co–Co edges are bridged by a diphosphine ligand and each cobalt center is thus coordinated by one P donor. Complex 3 was shown to react with the Pd(0) complex [Pd(dba)2] (dba = dibenzylideneacetone) to afford a tetranuclear complex resulting from both the insertion of Pd(0) into the ligand C–Br bond and Pd(II)/Pd(0) comproportionation to form a doubly ligand-bridged Pd(I)–Pd(I) core.