Synthesis and crystal structure of bis-µ-(5-chloro-2-hydroxy-N-methyl-α- phenylbenzylideneiminato-N,O)-bis[ethanol(nitrato-O,O′)nickel(II)]: a new type of nickel(II) dimer
The title complex (4) is formed by reaction of nickel(II) dinitrate hexahydrate and triethoxymethane (tem) with bis(5-chloro-2-hydroxy-N-methyl-α-phenylbenzylideneiminato)nickel(II); its crystal and molecular structure were determined by single-crystal X-ray diffraction. The two nickel atoms are in distorted octahedral environments with a shared edge formed by the phenolic oxygens of the Schiff-base ligands, each of which bonds to both metal atoms. Like the Schiff-base ligands, the nitrato-groups are bidentate, and an ethanol molecule bonded at oxygen completes the octahedron. The ethanol is formed by the reaction of hydrate water with tem. These results are in contrast with those of related nickel complexes and nickel nitrate which form trinuclear complexes, in which the solvent plays no part. An analogous reaction proceeds in other solvents. e.g. ethanol and methanol, but the product is difficult to control because water and solvent molecules compete for the sixth ligand position on the metal.
Crystals of (4) Are triclinic, space group P, unit-cell parameters: a= 8.969(7), b= 9.601(3), c= 11.926(7)Å, α= 100.32(5), β= 92.12(7), γ= 114.01(3)°, Z= 1 dimer. The structure was solved by the heavy-atom method from diffractometer data, and refined by least squares to R 0.029 for 2 090 observed reflections.