Synthesis and characterization of mononuclear nickel(II) and cobalt(II) complexes of 2,2,4,4-tetrakis(3,5-dimethylpyrazolyl)-6,6-diphenyl-2λ5,4λ5,6λ5-cyclotriphosphaza-1,3,5-triene L: crystal structure of [NiLCl2]

Abstract

Three complexes [NiLCl₂]2a, [NiLBr₂]2b and [CoLCl₂]2c, where L is the potentially multidentate ligand 2,2,4,4-tetrakis(3,5-dimethylpyrazolyl)-6,6-diphenyl-2λ⁵,4λ⁵,6λ⁵-cyclotriphosphaza-1,3,5-triene, have been prepared and characterized spectroscopically (IR, ¹H and ³¹P NMR) and in the case of 2a, crystallographically. The Ni^II atom in 2a has been shown to exist in a distorted trigonal-bipyramidal geometry in which the halide atoms and a ring nitrogen atom define the equatorial plane; the axial positions are occupied by two nitrogen atoms derived from two pyrazolyl rings. Crystals of 2a are monoclinic with space group C2/c and unit cell dimensions: a= 38.190(8), b= 9.225(3), c= 21.830(4)Å, β= 108.29(2)° and Z= 8. The structure was refined to final R= 0.045 for 4414 observed data.