Colour, isomerism, and structure of some copper co-ordination compounds. Part XXI. Crystal and molecular structure of the 2:1 adduct between 1,3,5-trinitrobenzene and bis-(N-methylsalicylaldiminato)-copper(II)

Abstract

An X-ray structural analysis by the heavy-atom method of the title compound has revealed a donor–acceptor interaction between trinitrobenzene and the salicylidene residues. The monoclinic cell has dimensions a= 11·726(4), b= 9·327(2), c= 14·10(1)Å, β= 93·55(5)°, Z= 2, space group P2₁/c. Diffractometer data (1972 observations) were refined by block-diagonal least-squares to R 0·072. The two species are arranged alternately in stacks so that each donor interacts with two acceptors and vice versa. Their molecular planes are not parallel, but make dihedral angles of 5·8 and 26·4° with one another, the interactions at ca. 3·2 Å being between specific regions of each. The complex shows the familiar stepping feature and the copper atom completes a distorted but centrosymmetric octahedral stereochemistry by interaction with an oxygen atom of two symmetry related nitro-groups at 3·08 Å.