Stereochemistry of rigid chelate–metal complexes. Part II. Crystal structure of di-µ-chloro-sym-trans-dichloro-bis-(2,9-dimethyl-1,10-phenanthroline)dinickel(II)–2-chloroform

Abstract

The crystal structure of di-µ-chloro-sym-trans-dichloro-bis-(2,9-dimethyl-1,10-phenanthroline)dinickel(II)–2-chloroform, C₃₀H₂₆N₄Ni₂, has been determined from three-dimensional precession X-ray diffraction data with 1512 visually estimated reflections. There are two molecules of the dimer in the monoclinic unit cell, space group P2₁/n, with dimensions a= 11·75(1), b= 13·46(2), c= 11·27(2)Å, β= 91·2(1)°. The structure was refined by least squares to a conventional R of 0·078. The dimeric molecule is made up of two monomeric dichloro-(2,9-dimethyl-1,10-phenanthroline)nickel(II) units linked by bridging chlorine atoms. The two halves of the dimer are related by a crystallographically imposed centre of symmetry. The nickel atom has an approximately square pyramidal co-ordination with the square defined by one nitrogen and three chlorine atoms, and the metal atom displaced 0·39 Å towards the other nitrogen. There is a large deviation of apex N–Ni–Cl(bridge) bond angle [120·8(3)°] from the expected 90° for a regular square pyramid, presumably owing to the interaction of a methyl group of the bidentate ligand with the chlorine-bridged atom [C(15)–Cl(1′) 3·63(2)Å]. Some distances and angles are: Ni–Cl 2·316(3), Ni–Cl(bridge), 2·394(3), 2·378(3), Ni–N(in-plane) 2·07(1), Ni–N (apex), 2·06(1), Ni–Ni 3·602(2)Å, N–Ni–N 81·7(4)°.