Fig. 1. Proposed optimized structures depicted with ball and sticks for [Bk(CO3)4]4‒(1 ) and [Bk(CO3)3(OH)2]4‒(2 ) complexes.
The calculated spectra seem to agree with the experimental data and the initial supposition of the replacement of one carbonate by two hydroxyl ligands that matches the experimental Bk(IV) spectrum in 2 M carbonate solution (Fig. 2). The peak corresponding to the pure carbonate coordinated structure was predicted to be located at 307.7 nm while the peak for the carbonate-hydroxide structure was predicted to be at 302.1 nm (Table 1). Unlike the homoleptic complex, an intense transition (370.9 nm) is observed in the calculated absorption spectrum of the heteroleptic complex that matches the shoulder observed in the 2 M carbonate spectrum.2