Abstract :
A series of f-block chromates, CsM(CrO4)2 (M=La, Pr, Nd, Sm, Eu; Am), are prepared revealing notable differences between the AmIII derivatives and their lanthanide analogs. The covalent contributions to bonding by the f orbitals are found to be more than twice as large in the AmIII chromate than in the SmIII and EuIII compounds, and even larger in magnitude than the Am-5f spinuorbit splitting in this system. The analysis indicates also that the AmuO covalency in [alpha]-CsAm(CrO4)2 is driven by the degeneracy of the 5f and 2p orbitals, and not by orbital overlap.