Na^I/Cu^I-II heterometallic cages interconnected by unusual linear 2-coordinate OCN-Cu(I)-NCO links: Synthesis, structural, magnetostructural correlation and computational studies

A new Na^I/Cu^I-II heterometallic coordination complex [Cu₂L₂Na(NCO)₂Cu]_n (1) with an unusual architecture has been synthesised. In 1 cyclic Na-O-Cu-O-Cu cages constructed by the tetradentate N₂O₂ donor Schiff base ligand (H₂L = N,N'-bis(2-hydroxyacetophenone)propylenediimine) are interconnected to each other by a rare singly end-to-end bridged OCN-Cu(I)-NCO link generating 1D chain. The complex has been characterised by elemental, spectral and structural analysis. The cyclic voltammogram of 1 has been compared with the analogous complexes. Cryomagnetic susceptibility studies indicate the copper(II) centers in the cyclic Na-O-Cu-O-Cu cages are antiferromagnetically coupled with J = -13.8 cm^-1. Complex 1 is a new addition to a class of rare singly end-to-end cyanato bridged copper(I) species and interestingly the copper ions involved in OCN-Cu(I)-NCO links possess a linear 2-coordinate geometry. Density functional theory calculations have been carried out to gain additional insights into the metal and ligand orbitals participating in this unusual structure. © The Royal Society of Chemistry 2009.