Synthesis, structures and photophysics of novel luminescent platinum-copper complexes

The novel hexanuclear platinum-copper complex [Pt2Cu4(C6F5)(4)(CdropC(t)Bu)(4)(acetone)(2)] (1) and the polynuclear derivative [PtCu2(C6F5)(2)(CdropCPh)(2)](x) (2), which crystallises in acetone as [Pt2Cu4(C6F5)(4)(CdropCPh)(4)(acetone)(4)] (2)(.)(acetone)(4), have been prepared using [cis-Pt(C6F5)(2)(THF)(2)] and the corresponding copper-acetylide [Cu(CdropCR)](x) (molar ratio 1:2) as starting materials. Treatment of 1 and 2 with 2,2'-bipyridine (molar ratio Cu-bipy 1:1), afforded the new trinuclear derivatives [{cis-Pt(C6F5)(2)(mu-CdropCR)(2)} {Cu(bipy)}(2)] (R = Bu-t 3, Ph 4), in which the dianionic 3-platina-1,4-diyne acts as a didentate bridging-ligand to two different cationic Cu(bipy) units through eta(2)-side-on coordination of the alkynyl fragments. While similar treatment of 1 with dppe (Cu-dppe 1:1) yielded [{cis-Pt(C6F5)(2)(mu-CdropC(t)Bu)(2)}{Cu(dppe)}(2)] (5), the analogous reaction of 2 with dppe afforded a mixture of complexes containing [Pt(C6F5)(CdropCPh)(dppe)] as the main platinum compound. The crystal structures of 1, 2(.)(acetone)(4), 3 and 4 and the luminescent behaviour of all complexes have been determined. A comparison of the photoluminescent spectra of 1 and 2 with those of the related platinum-silver species [PtAg2(C6F5)(2)(CdropCR)(2)](x) and the monomeric [cis-Pt(C6F5)(2)(CdropCR)(2)](2-) suggests the presence of emitting states bearing a large cluster [PtM2](x)-to-ligand (alkynide) charge transfer (CLCT). (C) 2003 Elsevier Science B.V. All rights reserved.