CRYSTAL AND MOLECULAR-STRUCTURE OF MONOSUBSTITUTED AND DISUBSTITUTED [NI(BZO2ME4[14]HEXAENATON4)] COMPLEXES - 1ST X-RAY CHARACTERIZATION OF THE -C(=NH)CN GROUP

The macrocyclic complex [Ni(Bzo2Me4[14]hexaenatoN4)] undergoes successive insertion by cyanogen at the two C-H methine groups. The primary reaction products do not show any ligand rearrangement and represent the first example of complexes bearing a cyanoiminomethyl substituent at a metallo-organic ring, for which the crystal and molecular structure has been determined by X-ray analysis. The mono- (I) and disubstituted complexes (II) crystallize in the orthorhombic Pnca (1) and monoclinic C2/c (II) space groups, with cell dimensions a = 22.354(3), b = 15.855(2), c = 11.417(2) angstrom (Z = 8), and a = 21.813(3), b = 9.221(2), c = 11.185(2) angstrom, beta = 99.1(2)-degrees (Z = 4), respectively. Their structures (R(w) = 0.0386 (I) and 0.0552 (II)) show a saddle-shaped deformation, which is enhanced by substitution of the methine hydrogen by the -C(= NH)CN group. The structural parameters of this substituent show, inter alia, unusually high C-C(= N) (1.470(5) angstrom) and C-C(ring) (1.499(4) angstrom) bond distances, which well account for its observed thermal instability. In complex II, the two = NH hydrogen atoms interact with the two CN nitrogens of one faced molecule in an intermolecular hydrogen bond (H...N = 2.64(5) angstrom, N-H...N = 150(4)-degrees).