catena-Poly[zinc-tris-(μ-dimethyl-carbamato-κO:O')-zinc-μ-(2-phenyl-benzimidazolido-κN:N']

Abstract

The crystal structure of the title compound, [Zn(2)(C(13)H(9)N(2))(C(3)H(6)NO(2))(3)](n), displays a long chiral chain. This is composed of zinc-dimer clusters capped by dimethyl-carbamate ligands, which lie on crystallographic twofold rotation axes and are polymerically linked in one dimension by 2-phenyl-benzimidadole (2-PBImi) organic ligands. The two Zn(2+) ions defining the dimetal cluster are crystallographically independent, but display very similar coordination modes and tetra-hedral geometry. As such, each Zn(2+) ion is coordinated on one side by the N-donor imidazole linker, while the other three available coordination sites are fully occupied by the O atoms from the capping dimethyl-carbamates. The chirality of the chain extends along the c axis, generating a rather long 52.470 (11) Å cell axis. Inter-estingly, the chiral material crystallizes from completely achiral precursors. A twofold axis and 3(1) screw axis serve to generate the long asymmetric unit.

Fig. 1.

A view of the molecular building block (MBB) for the title compound, with labels and 50% probability displacement ellipsoids for non-H atoms. A twofold rotation axis extends through the polymeric chain parallel to the N4—C14 bond (and coincident with the a axis) and relates atoms by symmetry. For clarity of the MBB, dimethylcarbamate molecules attached to the Zn2 metal center have been removed. Atom labels containing asterisks indicate symmetry equivalent atoms.

Fig. 2.

Capped stick image of the entire asymmetric unit for the title compound. This plot shows the second set of demethylcarbamate molecules which coordinate to the Zn2 atom. Atom labels containing asterisks indicate symmetry equivalent atoms.

Fig. 3.

A ball-and-stick representation of a single chiral chain for the title compound. The chain propagates in the c axis direction.