Efficient Blue Phosphorescence In Gold(I)-Acetylide Functionalized Coinage Metal Bis(Amidinate) Complexes

The synthesis of linear symmetric ethynyl- and acetylide-amidinates of the coinage metals is presented. Starting with the desilylation of the complexes [{Me3SiC equivalent to CC(NDipp)(2)}(2)M-2] (Dipp= 2,6-diisopropylphenyl) (M= Cu, Au) it is demonstrated that this compound class is suitable to serve as a versatile metalloligand. Deprotonation with n-butyllithium and subsequent salt metathesis reactions yield symmetric tetranuclear gold(I) acetylide complexes of the form [{(PPh3)AuC=CC(NDipp)(2)}2M(2)] (M= Cu, Au). The corresponding Ag complex [{(PPh3)AuC=CC(NDipp)(2)}(2)Ag-2] was obtained by a different route via metal rearrangement. All compounds show bright blue or blue-green microsecond long phosphorescence in the solid state, hence their photophysical properties were thoroughly investigated in a temperature range of 20-295 K. Emission quantum yields of up to 41% at room temperature were determined. Furthermore, similar emissions with quantum yields of 15% were observed for the two most brightly luminescent complexes in thf solution.