Infrared spectra of sodium and benzene in solid argon

An infrared matrix isolation study has been performed for sodium and benzene mixtures in solid argon at 9 K. In contrast with the earlier report, sodium was evidenced to form complexes with benzene. Although the exact nature of the complexes is not certain, ab initio quantum mechanical calculation indicated clearly that the 1 : 1 Na-C6H6 complex should be as stable as the 1:1 Li-C6H6 complex. The tentatively assigned peak frequencies for the 1: 1 Na-C6H6 complex were also in fair agreement with the theoretical values.