Luminescent Tetranuclear Copper(I) and Gold(I) Heterobimetallic Complexes: A Phosphine Acetylide Amidinate Orthogonal Ligand Framework for Selective Complexation

The synthesis of phosphine acetylide amidinate stabilized copper(I) and gold(I) heterobimetallic complexes was achieved by reacting ligand [{Ph$_2$PC≡CC(NDipp)$_2$}Li(thf)$_3$] (Dipp=2,6-N,N′-diisopropylphenyl) with CuCl and Au(tht))Cl, yielding the eight membered ring [{Ph$_2$PC≡CC(NDipp)$_2$}$_2$Cu$_2$] and the twelve membered ring [{Ph$_2$PC≡CC(NDipp)$_2$}$_2$Au$_2$]. {Ph$_2$PC≡CC(NDipp)$_2$}$_2$Cu$_2$] features a Cu$_2$ unit, which is bridged by two amidinate ligands, served as a metalloligand to synthesize the heterobimetallic Cu$^I$/Au$^I$ complexes [{(AuX)Ph$_2$PC≡CC(NDipp)$_2$}$_2$Cu$_2$] (X=Cl, C4$_6$F$_5$). In these reactions, the central ring structure is retained. In contrast, when the twelve membered ring [{Ph$_2$PC≡CC(NDipp)$_2$}$_2$Au$_2$] was reacted with CuX (X=Cl, Br, I and Mes), the reaction led to the rearrangement of the central ring structure to give [{(AuX)Ph$_2$PC≡CC(NDipp)$_2$}$_2$Cu$_2$] (X=Cl, Br, I and Mes), which feature the same the eight membered Cu$_2$ ring as above. These compounds were also synthesized by a one-pot reaction. The luminescent heterobimetallic complexes were further investigated for their photophysical properties.