Crystal and molecular structure of mono- and disubstituted [Ni(Bzo 2Me 4[14]hexaenatoN 4)] complexes. First X-ray characterization of the C(NH)CN group

Abstract

The macrocyclic complex [Ni(Bzo 2Me 4[14]hexaenatoN 4)] 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 ( I) and monoclinic C2/c ( II) space groups, with cell dimensions a=22.354(3), b=15.855(2), c=11.417(2) Å ( Z=8), and a=21.813(3), b=9.221(2), c=11.185(2) Å,β=99.1(2)° ( 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) Å) and CC(ring) (1.499(4) Å) 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) Å, NH…N = 150(4)°).