A luminescent heterometallic AuI⋯ CuI complex. Spectroscopic properties and crystal structures of [Au(PPh3)(C7H5N2)] and [(Au(PPh3)(µ-C7H5N2)Cu-(µ-C7H5N2)}2](C7H5N2= 7-azaindolate)

Abstract

The mono- and tetra-nuclear complexes [Au(PPh₃)(C₇H₅N₂)]1 and [{Au(PPh₃)(µ-C₇H₅N₂)Cu(µ-C₇H₅N₂)}₂]2, the latter containing 7-azaindolate (C₇H₅N₂^–) 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.