A luminescent heterometallic Au I ⋯ Cu I complex. Spectroscopic properties and crystal structures of [Au(PPh 3)(C 7H 5N 2)] and [(Au(PPh 3)(μ-C 7H 5N 2)Cu-(μ-C 7H 5N 2)} 2](C 7H 5N 2 = 7-azaindolate)

Abstract

The mono- and tetra-nuclear complexes [Au(PPh 3)(C 7H 5N 2)] 1 and [{Au(PPh 3)(μ-C 7H 5N 2)Cu(μ-C 7H 5N 2)} 2] 2, the latter containing 7-azaindolate (C 7H 5N 2 -) bridging ligands, have been prepared and their crystal structures determined. The intramolecular Au ⋯ Cu and Cu ⋯ Cu separations in 2 are 3.0104(6) and 2.941(1) Å respectively. Extended-Hückel molecular-orbital calculations revealed a weak Au I ⋯ Cu I bonding interaction but no Cu I ⋯ Cu I interaction. In acetonitrile, both complexes display intense intraligand emission at 510 nm upon photoexcitation with UV/VIS light at room temperature. In the solid state 2 shows an emission at 550 nm.