Cooperativity in luminescent heterobimetallic diphosphine-β-diketiminate complexes

The bis(phosphine)-functionalized beta-diketiminate ligand [HC{(CH3)C}2{(o-[P(C6H5)2]2C6H4)N}2]- (PNac) was used for the synthesis of luminescent closed-shell bimetallic complexes. The PNNP pocket combining both soft and hard donor sites can act as an orthogonal ligand scaffold to selectively coordinate two different metal ions. Deprotonation and subsequent salt elimination with [AuCl(tht)] (tht = tetrahydrothiophene) or AgI yielded the mononuclear complexes [PNacAu] (1) or [PNacAg] (2), respectively. The AuI ion is linearly coordinated by the two phosphines, forming a 12-membered metalla-macrocycle with an empty beta-diketiminate pocket available for complexation of hard d10 metal ions (ZnII, CdII, and HgII). According to this synthetic protocol, a series of heterobimetallic complexes were isolated. The complexation of the second metal ion in close spatial proximity has led to drastic changes in the photophysical properties. For further studies and understanding, quantum chemical calculations were performed. A PNNP ligand was used for the synthesis of luminescent bimetallic complexes, featuring the combination of group 11 and 12 metals. The cooperativity of the metal ions in close spatial proximity led to drastic changes in the photophysical properties.