Cu(I)-N heterocyclic carbene complexes: Synthesis, catalysis and DFT studies

Abstract

The structural, spectroscopic and catalytic properties of the two Cu(I) complexes [Cu2(L1)2](PF6)2;(1) and [Cu2(L2)2](PF6)2; (2), bearing proligands 2,6-bis-(N-methylimidazolium)pyrazine hexafluorophosphate (L1) and 2,6-bis-(N-methylbenzimidazolium)pyrazine hexafluorophosphate (L2), have been investigated. The solid state structure of 1 has been determined by X-ray diffraction studies, while DFT computation technique has been used to optimize structure 2. From molecular orbital calculations using TD-DFT, the absorption bands are assigned to metal to ligand charge transfer(MLCT) along with some inter ligand charge transfer (ILCT) transitions. Complexes 1 and 2 possess very weak Cu(I)Cu(I) interactions within the reported distance 2.947–3.020 Å. They are expected to have luminescent properties due to Cu(I)Cu(I) interactions. Preliminary studies revealed both complexes to possess catalytic efficiency in general hydrosilylation reactions.