The structures and properties of different gold and silver mixed-metal trinuclear complexes, [AunAgm(HNCOH)3] (m+n=3), were investigated theoretically. The computed properties were compared with those of the [Au3(HNCOH)3] complex. The geometries of all complexes were optimized at the B3LYP level of theory using the GEN basis set. The optimization results revealed that the most stable structures of pure Au and Ag complexes are almost similar. In addition, all complexes are flat and highly symmetric. It was shown that the silver substitution had a significant influence on the electronic properties. The metalemetal distances were in the order of: AueAu < AueAg < AgeAg. The ionization potential and hardness were found to be decreased while the electron affinity, HOMOeLUMO gap and chemical potential were found to be increased from the [Au3(HNCOH)3] to the [Ag3(HNCOH) 3] complex. The [Au3(HNCOH)3] complex was the least reactive in the studied series with the electronic chemical potential equal to3.98 eV. On the other hand, the value of the chemical potential characterizing the most reactive complex, [Ag3(HNCOH)3],was -3.80 eV.
