Structural and spectroscopic studies of fluoroprotactinates.
Seven protactinium(V) fluoride compounds have been synthesized, and their crystal structures and Raman spectra are reported. (NH4)2PaF7, K2PaF7, Rb2PaF7, and Cs2PaF7 were found to crystallize in the monoclinic space group P21/c for the ammonium compound and C2/c for the K(+)-, Rb(+)-, and Cs(+)-containing compounds, with nine-coordinate Pa forming infinite chains through fluorine bridges. Na3PaF8 crystallizes in the tetragonal space group I4/mmm with eight-coordinate Pa in tetragonal geometry, while tetramethylammonium fluoroprotactinate shows two different structures: (Me4N)2(H3O)PaF8, an eight-coordinate molecular compound crystallizing in the monoclinic space group C2/c, and (Me4N)PaF6, an eight-coordinate Pa compound forming infinite chains and crystallizing in the orthorhombic space group Pnnm. A comparison of solid- and solution-state Raman data indicates that the PaF8(-) anion could be the predominant Pa(V) complex in concentrated solutions of aqueous HF.
Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
Stéphanie M
SM
De Sio
Richard E
RE
Wilson