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