Metalloligands of stoichiometry [AuCl(P−N)] have been obtained by the reaction of the heterofunctional phosphines P−N = PPh2py, PPh2CH2CH2py, or PPhpy2 with [AuCl(tht)] (tht = tetrahydrothiophene). Reactions of these metalloligands with several metal compounds have afforded heteropolynuclear species which exhibit luminescent properties. The stoichiometries depend on the molar ratio and the heterometal. Thus, the reaction with [Cu(NCMe)4]+ in a molar ratio 2:1 gives the trinuclear compounds [Au2CuCl2(P−N)2]+, in which the structure and Au···Cu interactions depend on the phosphine ligand. With rhodium and iridium derivatives the reactivity is different leading to complexes of the type [AuMCl2(cod)(P−N)] for P−N = PPh2py, PPhpy2, and [Au2M2Cl(cod)2(P−N)2]Cl with PPh2CH2CH2py. Using [MCl2(NCPh)2] (M = Pd, Pt) in a 2:1 molar ratio yields [Au2MCl4(P−N)2] and in a 1:1 molar ratio [AuPdCl3(μ3-PPhpy2)]. Several compounds have been characterized by X-ray diffraction showing in many cases short Au···M distances. The luminescence of these derivatives has been studied. The metalloligands display bands assigned to intraligand (IL) transitions. For the bimetallic (Au/M) systems the luminescence depends on the heterometal present and on the metallophilic interactions. The most important excitations in the relevant energy range were assigned essentially a MMLCT character (from Rh/Ir and Au to ligands) based on density functional theory (DFT) calculations in selected complexes. The luminescence behavior in Rh/Ir [AuMCl2(cod)(PPh2py)] complexes was interpreted on the basis of the different nature of the half occupied orbitals in the triplet state.
The reaction of [AuCl(PR'3)] with KTeR, prepared from RTeTeR and K-selectride, gives the gold-tellurolate clusters [Au8(mu-TeR)8(PR'3)4] (R = Ph, Tol; PR'3 = PPh3, PPh2py) in high yield. This result contrasts with the one obtained from the reaction with thiolates or selenolates, from which mononuclear complexes are synthesized. The structures of these species have been determined and consist on three layers of gold and tellurium atoms in the ratio Au3Te2:Au2Te4:Au3Te2. There are short gold...gold interactions ranging from 2.9463(7) to 3.31132(7) A, and the clusters are composed of di- and tri-coordinated gold centers. The result is unprecedented in gold-chalcogenolate chemistry from which mononuclear species are expected and represents one of the few examples of gold-tellurolate derivatives. These species show an interesting luminescent behavior in the solid state (at 77 K) and in solution (both at 298 and 77 K).
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