Luminescent hepta- and tetradecanuclear complexes of 5,5'-diethynyl-2,2'-bipyridine capped with triangular trinuclear Cu3/Ag3 cluster units

Heteroheptanuclear ReM6 (M = Cu 2, Ag 3) complexes of 5,5-diethynyl-2,2'-bipyridine were prepared by the reaction of M2(mu-dppm)2(MeCN)2]2+ (dppm = bis(diphenylphosphino)methane) with the precursor compound Re(Me3SiCtriple bond]CbpyCtriple bond]CSiMe3)(CO)3Cl in the presence of potassium fluoride by fluoride-catalyzed desilylation. When Cu2(mu-dppm)2(MeCN)2]2+ reacts directly with Me3SiCtriple bond]CbpyCtriple bond]CSiMe3, a binuclear CuI complex Cu2(mu-dppm)2(SiMe3Ctriple bond]CbpyCtriple bond]CSiMe3)2]2+ (4) was isolated. Further addition of Cu2(mu-dppm)2(MeCN)2]2+ into a THF-MeOH (3:1, v/v) solution of 4 in the presence of potassium fluoride induced isolation of a tetradecanuclear CuI14 complex Cu14(mu-dppm)14(Ctriple bond]CbpyCtriple bond]C)2]10+, which is composed of a binuclear Cu2(mu-dppm)2 and four triangular trinuclear Cu3 units. Both heteroheptanuclear ReIMI6 and tetradecanuclear CuI14 complexes display luminescence in both solid states and dichloromethane solutions at room temperature with emissive lifetimes in the range of microseconds. The dual emissive feature for the ReM6 and CuI14 complexes is ascribed tentatively to originate from both MLCT d(Re/Cu) -->pi* (bpy)] and LMCT (acetylide --> M3) transitions. .