Pd(II) and Ni(II) complexes featuring a "phosphasalen" ligand: synthesis and DFT study

A phosphorus analog of salen ligands featuring iminophosphorane functionalities in place of the imine groups was synthesised in 2 steps from o-diphenylphosphinophenol via the preparation of the corresponding bis-aminophosphonium salt. This novel tetradentate ligand (1), which we named phosphasalen, was coordinated to Pd(II) and Ni(II) metal centres affording complexes 6 and 7 respectively, which were characterised by multinuclear NMR, elemental and X-ray diffraction analyses. Both neutral complexes adopt a nearly square-planar geometry around the metal with coordination of all iminophosphorane and phenolate moieties. The electronic properties of these new complexes were investigated by cyclic voltammetry and comparison with known salens was made when possible. Moreover, the particular behaviour of the phosphasalen nickel complex 7 was further investigated through magnetic moment measurements and a DFT study.

Synthesis of Novel Phenoxyimine Ligands Containing a 2,6-Difluoro-4-Styrylaniline

An efficient synthesis of novel phenoxyimine ligands containing a difluorovinylbiphenyl group was based on the Suzuki coupling coupling of 4-bromo-2,6-difluoroaniline with 4-styrylboronic acid followed by a condensation reaction with various arylaldehydes. The structures were established by IR, 1H NMR, 13C NMR spectra and HRMS. The advantages of this synthetic route were its simple operation, mild reaction conditions and good yields.