Issue 36, 2012

An unprecedented “linear-bent” isomerism in tri-nuclear Cu2IIZnII complexes with a salen type di-Schiff base ligand

Abstract

Two new trinuclear hetero-metallic copper(II)–zinc(II) complexes [(CuL)2Zn(N3)2] (1A and 1B) have been synthesized using [CuL] as a so-called “metalloligand” (where H2L = N,N′-bis(salicylidene)-1,3-propanediamine) and structurally characterized. Complexes 1A and 1B have the same molecular formula but crystallize in different crystal systems (triclinic for 1A and monoclinic for 1B) with space group P[1 with combining macron] for 1A and P21/c for 1B. 1A is an angular trinuclear species, in which two terminal four-coordinate square planar “metalloligand” [CuL] are coordinated to a central Zn(II) through double phenoxido bridges. The Zn(II) is in a six-coordinate distorted octahedral environment being bonded additionally to two mutually cis nitrogen atoms of terminal azide ions. In complex 1B, in addition to the double phenoxido bridge, the two terminal Cu(II) ions are linked to the central Zn(II) via a μ-l,l azido bridge giving rise to a square pyramidal environment around the Cu(II) ions and consequently the structure becomes linear. These two species can be considered as “linear-bent” isomers. EPR spectra and ESI mass spectra show that the two isomers are identical in solution. The DFT calculation reveals that the energy of 1A is 7.06 kcal mol−1 higher than that of 1B. The existence of both isomers in the solid state suggests that crystal packing interactions in 1A are more efficient and probably compensate for the difference in energy.

Graphical abstract: An unprecedented “linear-bent” isomerism in tri-nuclear Cu2IIZnII complexes with a salen type di-Schiff base ligand

Supplementary files

Article information

Article type
Paper
Submitted
09 May 2012
Accepted
22 Jun 2012
First published
22 Jun 2012

Dalton Trans., 2012,41, 11009-11017

An unprecedented “linear-bent” isomerism in tri-nuclear Cu2IIZnII complexes with a salen type di-Schiff base ligand

L. K. Das, S. Park, S. J. Cho and A. Ghosh, Dalton Trans., 2012, 41, 11009 DOI: 10.1039/C2DT31011B

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