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

Resumen

The novel hexanuclear platinum-copper complex [Pt2Cu4(C6F5)4 (C≡CtBu)4] (acetone)2] (1) and the polynuclear derivative [PtCu2(C6F5)2 (C≡CPh)2]x (2), which crystallises in acetone as [Pt2Cu4 (C6F5)4 (C≡CPh)4(acetone)4] (2).(acetone)4, have been prepared using [cis-Pt(C6F5)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(C6F5)2 (μ-C≡CR)2}{Cu(bipy)}2] (R = tBu 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 η2-side-on coordination of the alkynyl fragments. While similar treatment of 1 with dppe (Cu-dppe 1:1) yielded [{cis-Pt(C6F5)2 (μ-C≡CtBu)2} {Cu(dppe)}2] (5), the analogous reaction of 2 with dppe afforded a mixture of complexes containing [Pt(C6F5)(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 [PtAg2(C6F5)2 (C≡CR)2]x and the monomeric [cis-Pt(C6F5)2 (C≡CR)2]2- suggests the presence of emitting states bearing a large cluster [PtM2]x -to-ligand (alkynide) charge transfer (CLCT). © 2003 Elsevier Science B.V. All rights reserved.