title: Pseudosymmetry in pyridinium tetrachloro(oxo)pyridineniobate(V) pyridine solvate.
abstract: The title compound, (C(5)H(6)N)[NbCl(4)O(C(5)H(5)N)]center dotC(5)H(5)N, crystallizes as discrete ions, with a very strong linear N-H...N hydrogen-bonding interaction between the cation and the solvate pyridine molecule [N...N 2.755 (5) A]. All chemical species occupy crystallographic twofold axes. The ligated and solvate pyridines form ABABAB stacks in the lattice. There is pseudosymmetry which emulates a centred unit cell in Amm2, but it is not supported by the diffraction pattern, which is consistent with the correct space group Pnc2. Three crystallographic software packages suggested space group Amm2 over Pnc2, while a fourth indicated Pnc2, a subgroup of Amm2.
authors.affiliation: 2124 Chemistry Department, University of Wisconsin--Madison, 1101 University Avenue, Madison, WI 53706, USA. iguzei@chem.wisc.edu
authors.forename: Ilia A
authors.initials: IA
authors.lastname: Guzei
authors.forename: John
authors.initials: J
authors.lastname: Roberts
authors.forename: Dovas A
authors.initials: DA
authors.lastname: Saulys