CRYSTAL-STRUCTURE OF HEXAKIS(1,8-NAPHTHYRIDINE)PRASEODYMIUM(III) PERCHLORATE
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Crystals of hexakis(1,8-naphthyridine)praseodymium(III) perchlorate, (C8H6N2)6Pr(ClO4)3, are monoclinic, with space group P21/c. The cell dimensions are a = 13.748 (3) , b = 16.979 (6) , c = 22.949 (8) , and = 107.34 (1), V = 5113.14 3. With Z = 4 the density is calculated to be 1.5850 g cm3 which compares to a density measured by flotation in a KI solution of 1.583 g cm3. A total of 2263 intensities above background were collected with a scintillation counter automated diffractometer by the -2 scan method. The structure was refined by block-diagonal least-squares methods to a conventional RF factor of 0.049 and a weighted residual RwF of 0.063. Anisotropic thermal parameters were obtained only for the metal atom and perchlorate groups. All six naphthyridine rings act as bidentate ligands forming a distorted icosahedron of nitrogen atoms about the metal. Pr-N bond distances range from 2.735 (12) to 2.768 (11) . Distortion of the icosahedron results principally from the unequal lengths of the nitrogen-nitrogen interatomic distances. Those which occur within individual naphthyridine ring systems are short averaging 2.257 (12) while those between adjacent nitrogen atoms in two different naphthyridine rings range from 2.890 (16) to 3.195 (16) . The rings are also arranged such that a patohedron is not formed. 1977, American Chemical Society. All rights reserved.
