Structural systematics of the [Cu(chelate)3][Y]2 series. An interesting crystallographic structural insight involving vibronic coupling and the Jahn-Teller effect (JTE). The syntheses and low temperature crystal structures of tris(2,2′bipyridyl)copper(II) tetraphenylborate and tris(2,2′bipyridyl)zinc(II) tetraphenylborate

The crystal structures of [Cu(bipy)3][BPh4] 2, 1, and [Zn(bipy)3][BPh4]2, 2 have been determined at low temperature. 1 and 2 are closely related, but are not isostructural. Both contain a two-dimensional supramolecular construct (SC) involving a sandwich structure. 1 has a six-coordinate CuN6 chromophore with a regular elongated octahedral stereochemistry and rhombic in-plane bond lengths. The associated tetragonality value, T, of 1 is 0.8868. 2 involves a six-coordinate octahedral chromophore. Differences between 1 and 2 relate to the tendency of copper(ii) complexes to undergo a Jahn-Teller (JT) distortion. The zinc(ii) cation feels solely the host site strain, whereas the copper(ii) cation also involves vibronic JT type coupling. The copper polyhedron geometry is characterized by both phenomena, with the vibronic interaction dominating. Scatter plot analysis involving the tris-chelate copper(ii) series suggests that neither pure Qθ or QΕ components or the a2u mode operate in isolation over the entire series. All three operate in combination with varying quantifiable contributions, leading to distortion from the regular tetragonal octahedral stereochemistry. © The Royal Society of Chemistry 2006.