Jahn–Teller distortions of six-coordinate CuIIcompounds: cisor trans?Electronic supplementary information (ESI) available: Shape measures and bond distances for cis- and trans-distorted CuIIcompounds; atomic coordinates of the optimized structures of [Cu(1)]2+, [Cu(2-pyridyl2)]2+, [Cu(2-carboxylate2)]2+(isomers Aand B), [Cu(4)]2+, [Cu(cyclen)Cl2] and [Cu(cyclen{CH2CH2NH2}2)]. See DOI: 10.1039/b903867a

Unlike their octahedral analogues, copper(ii) compounds with trigonal prismatic stereochemistry undergo an elongation of two bonds in cispositions due to a Jahn–Teller effect, a behavior that can also occur in slightly twisted octahedra. [ABSTRACT FROM AUTHOR]