Remote Steric Control of the Tetrahedral Coordination Geometry around Heteroleptic Copper(I) Bis(Diimine) Complexes

Abstract

In this study, a series of new heteroleptic copper(I) bis(diimine) complexes are described. Using one highly hindered phenanthroline ligand and a second less-hindered diimine ligand led to unexpected results. Following a two-step one-pot method to obtain heteroleptic copper(I) complexes, an almost perfect tetrahedral coordination geometry around the copper(I) ion was obtained in several cases, despite the fact that at least one ligand was not sterically encumbered near the coordination site (at the position α to the nitrogen atoms of the ligand). This was demonstrated in the solid state by resolution of crystal structures, and these findings, corroborated by calculations, showed that the non-covalent interactions between the two diimine ligands present in these complexes were governing these structural features. The electronic properties of all complexes were also determined and the fluorescence lifetimes of two complexes were compared.

Enhanced Visible Light Absorption in Heteroleptic Cuprous Phenanthrolines

“…This platform facilitates a facile pathway for obtaining heteroleptic Cu­(I) complexes with the generic formula [Cu­(mesPhen)­(L)] + , where L is a second and distinct phenanthroline ligand (Chart ). The secondary phenanthroline moiety can be systematically varied to impart desired photophysical and electrochemical properties. ,− Optically and electronically tuned HETPHEN Cu­(I) complexes have been designed to feature bulky substituents to limit the distortion similar to numerous homoleptic complexes , and have incorporated phenyl groups at the 4,7-positions to increase the absorbance cross-section in the visible MLCT region by promoting π-delocalization of the charge-transfer excited state to increase oscillator strength. ,,− …”