A STUDY OF SEVERAL MIXED CATIONIC SYSTEMS OF (PR LA)CO(CN)(6)CENTER-DOT-5H(2)O/

Three mixed cationic (Pr/La)Co(CN)(6) . 5H(2)O compounds have been syn thesized where the ratios of (Pr/La) are 1:9, 2:8, and 4:6. The struct ural analyses of these systems using single-crystal diffractometry and full-matrix least-squares refinement yielded reliability factors of 0 .036, 0.034, and 0.067 based on 643, 594, and 578 observed reflections , respectively. These complexes crystallize in the centrosymmetric hex agonal space group P6(3)/m with cell parameters a = 7.500(1), 7.491(2) , and 7.477(2) and c = 14.317(3), 14.297(2), and 14.265(2) Angstrom, r espectively (Z = 2). Observed densities, thermogravimetric results, an d infrared spectroscopic data are presented, as well as X-ray powder d iffraction analyses. The trivalent lanthanide (Ln) metal atoms are nin e-coordinate in the form of (Ln)N-6(H2O)(3) groups (TTP) which are lin ked to the octahedrally arranged CoC6 groups by cyanide bridging. Thre e of the five H2O molecules are coordinated to the Ln atoms and two ar e zeolitic in nature, occupying cavities in the polymeric array within hydrogen-bonding distances to the coordinated H2O molecules. Selectiv e bond distances and angles are listed and discussed as well as oxygen -oxygen intermolecular contact lengths. (C) 1997 Academic Press.