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

The structural, spectroscopic and catalytic properties of the two Cu(l) complexes [Cu-2(L1)(2)](PF6)(2);(1) and [Cu-2(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(l) interactions within the reported distance 2.947-3.020 angstrom. They are expected to have luminescent properties due to Cu(l) -Cu(I) interactions. Preliminary studies revealed both complexes to possess catalytic efficiency in general hydrosilylation reactions. (C) 2016 Elsevier B.V. All rights reserved.