Synthesis and structures of cyclic gold complexes containing diphosphine ligands and luminescent properties of the high nuclearity species

A mixture of cyclic gold(i) complexes [Au 2(µ-cis-dppen) 2]X 2 (X = OTf 1, PF 63) and [Au(cis-dppen) 2]X (X = OTf 2, PF 64) is obtained from the reaction of [Au(tht) 2]X (tht = tetrahydrothiophene) with one equivalent of cis-dppen [dppen = 1,2-bis(diphenylphosphino)ethylene]. The analogous reaction with trans-dppen or dppa [dppa = bis(diphenylphosphino)acetylene] affords the cyclic trinuclear [Au 3(µ-trans-dppen) 3]X 3 (X = OTf 11, PF 612) and tetranuclear [Au 4(µ-dppa) 4]X 4 (X = OTf 13, PF 614, ClO 415) gold complexes, respectively. Recrystallization of 15 from CH 2Cl 2/MeOH yielded a crystal of the octanuclear gold cluster [Au 8Cl 2(µ-dppa) 4](ClO 4) 216. Attempts to prepare dicationic binuclear gold(ii) species from the reaction of a mixture of 3 and 4 with halogens gave a mixture of products, the components of which confirmed to be acyclic binuclear gold(i) [Au 2X 2(cis-dppen)] (X = I 5, Br 7) and cyclic mononuclear gold(iii) [AuX 2(cis-dppen)]PF 6 (X = I 6, Br 8) complexes. Complexes 11-14 reveal weak emission in butyronitrile glass at 77 K, but they are non-emissive at room temperature.