Synthesis and Crystal Structure of Tetrakis(2-pyridinecarboxylato)niobium(IV).2Ethanol, an Octacoordinate Dodecahedral d1 M(A-B)4 System

Ooi, Bee-Lean; Sakane, Genta; Shibahara, Takashi

crystal structure niobium pyridinecarboxylato octacoordinate complex; niobium pyridinecarboxylato octacoordinate complex prepn structure
The red-purple octacoordinate [Nb(pyc)4].2EtOH complex was obtained by reaction of zinc-reduced EtOH solns. of niobium pentachloride with 2-pyridinecarboxylic acid (Hpyc).  It crystallizes in a monoclinic cell with dimensions a 15.524(4), b 11.981(3), c 15.353(4) angstrom, b 92.19(2)degree, V = 2853(1) angstrom cubed, and Z = 4.  The x-ray crystallog. revealed an approx. dodecahedral D2d geometry with four pyc ligands spanning the Hoard-Silverton designated m edges with the p-donor oxygen atoms (Nb-Oav = 2.009 angstrom) occupying the A sites while the p-acceptor nitrogen atoms (Nb-Nav = 2.302 angstrom) residing at the B.  This compd. provides the 1st evidence for Orgel's postulate regarding octacoordinate d1 M(AB)4 stereochem.

Inorganic Chemistry

American Chemical Society

35

25

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