PREPARATION AND CRYSTAL-STRUCTURE OF LN(3)VO(4)CL(6) (LN=LA, CO, PR, ND)

The new compounds Ln(3)VO(4)Cl(6)(Ln = La, Ce, Pr, Nd) were prepared b y heating a mixture of LnCl(3), LnOCl, and V2O5 (3:3:1) in evacuated, sealed silica ampoules (850 degrees C, 5 d). Single crystals of the la nthanum compound could be obtained by chemical vapor transport (900 -- > 800 degrees C; 10 d; transport agent Cl-2, p{298 K} = 1 atm). The si ngle-crystal study showed that La3VO4Cl6 crystallizes in the hexagonal space group P6(3)/m (No. 176), (Z = 2), with a = 12.5346(9) Angstrom and c = 4.1331(4) Angstrom (diffractometer data). Least-squares refine ment based on 618 unique reflections led to a conventional R value of 1.49% for all data. Vanadium is tetrahedrally coordinated (d((V-0)) = 1.72-1.75 Angstrom). For lanthanum, a C.N. = 10 (3 x O {d((La-0)) = 2. 44-2.98 Angstrom}, 7 X Cl {d((La-Cl)) = 2.95-3.12 Angstrom}) was found . Apart from the smaller coordination number of V5+ as compared to Nb5 +, the structure is closely related to that of Pr3NbO4Cl6. (C) 1996 Ac ademic Press, Inc.