Synthesis and Structural Diversity of Mono‐, Di‐ and Trinuclear Complexes with N,N′‐Bis[(2‐diphenylphosphanyl)phenyl]formamidine

Abstract

AbstractThe synthesis, characterization, and coordination chemistry of a series of mono‐, di‐, and trinuclear homo‐/heterometallic complexes with the dinucleating ligand, N,N′‐bis[(2‐diphenyl‐phosphanyl)phenyl]formamidine (pnnp)1 are reported. Treatment of (pnnp)PdMe (1) with NiCl2(dme) forms the heterobimetallic (pnnp)PdMe(μ‐Cl)NiCl (3) complex, whereas reaction of 1 with Cu(CH3CN)4+PF6– yields the Pd···Cu···Pd heterometallic trinuclear complex (pnnp)Pd(Me)CuPd(Me)(pnnp)·PF6 (8). The reaction of pnnp with NiCl2(dme) (dme = 1,2‐dimethoxyethane) produces the Ni dimer [(pnnp)NiCl(μ‐Cl)]2 (5) or the dinuclear (pnnp)NiCl(μ‐X)NiCl (X = Cl or OH) (4) complexes, depending upon the stoichiometry. The reaction of pnnp with CoII or FeII ions leads to the monometallic complexes (pnnp)CoCl2 (6) or (pnnp)FeCl2 (7), respectively. The dinuclear (pnnp)PdMe(μ‐Cl)NiCl (3) and (pnnp)NiCl(μ‐X)NiCl (X = Cl or OH) (4) complexes adopt A‐frame structures with two square‐planar d8 metal complexes hinged by the bridging ligand; the angles between the square planes correlate to the covalent radii, in which the smaller homo‐bimetallic Ni complex adopts a more coplanar arrangement of the two Ni square planes. The heterometallic trinuclear complex (pnnp)Pd(Me)CuPd(Me)(pnnp)·PF6 (8) adopts an unusual structure around the Cu center, suggestive of a weak d8–d10 interaction between the Pd and Cu atoms. All complexes have been characterized by NMR spectroscopy, elemental analysis, and X‐ray crystallography, and their structural diversity is discussed.