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

Abstract

The novel hexanuclear platinum–copper complex [Pt 2Cu 4(C 6F 5) 4(CC t Bu) 4(acetone) 2] ( 1) and the polynuclear derivative [PtCu 2(C 6F 5) 2(CCPh) 2] x ( 2), which crystallises in acetone as [Pt 2Cu 4(C 6F 5) 4(CCPh) 4(acetone) 4] ( 2) ·(acetone) 4, have been prepared using [ cis-Pt(C 6F 5) 2(THF) 2] and the corresponding copper–acetylide [Cu(CCR)] 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(C 6F 5) 2(μ-CCR) 2}{Cu(bipy)} 2] (R= t Bu 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 η 2-side-on coordination of the alkynyl fragments. While similar treatment of 1 with dppe (Cu–dppe 1:1) yielded [{ cis-Pt(C 6F 5) 2(μ-CC t Bu) 2}{Cu(dppe)} 2] ( 5), the analogous reaction of 2 with dppe afforded a mixture of complexes containing [Pt(C 6F 5)(CCPh)(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 [PtAg 2(C 6F 5) 2(CCR) 2] x and the monomeric [ cis-Pt(C 6F 5) 2(CCR) 2] 2− suggests the presence of emitting states bearing a large cluster [PtM 2] x -to-ligand (alkynide) charge transfer (CLCT).