Spectral properties and crystal structure of the complex iodo-[NN-bis-(2-diphenylphosphinoethyl)-2-methoxyethylamino]nickel(II) iodide

Abstract

The potentially quadridentate tripod-like ligand NN-bis-(2-diphenylphosphinoethyl)-2-methoxyethylamine (NOP₂) forms diamagnetic complexes with nickel(II) of general formula [Ni(NOP₂)X]Y. Their electronic spectra fail to indicate unambiguously whether the complexes are five-co-ordinate or square-planar with a terdentate ligand. Definitive answer is provided by a three-dimensional X-ray analysis of the [Ni(NOP₂)I]I complex. The co-ordination polyhedron about the nickel atom can be described as a distorted square pyramid with an unusually long apical bond between the metal and oxygen atoms.

The crystals are monoclinic, space group P2₁/c with a= 8·736 ± 0·005, b= 12·185 ± 0·011, c= 28·722 ± 0·016 Å, β= 90° 02′± 4′, and Z= 4.