Vibrational analysis of complexes of urate with IA group metal cations (Li+, Na+ and K+)

Vibrational frequency analysis was performed for the complexes of alkali metal cations (Li+, Na+ and K+) with urate in the gas phase. The geometries of all possible metal cation–urate complexes were optimized at the B3LYP/6-311++G(d,p) level. The most stable complex corresponding to the each cation was used for the vibrational frequency analysis including the computation of % potential energy distribution (%PED). For comparison, the vibrational frequency analysis was also performed for the uric acid. The computed results are discussed in terms of the available experimental data. It was revealed that the characteristic stretching vibrational modes corresponding to the metal cation and the interacting nucleophilic sites of urate can be used to identify metals involved in the stone formation in the living system. Changes in different vibrational frequencies of uric acid consequent to the metal cation interactions are discussed.