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A three‐dimensional cadmium(II) coordination polymer with unequal homochiral double‐stranded concentric helical chains
Author(s) -
Shi Wei,
Liu JianJun,
Ou XiangPing,
Huang ChangCang
Publication year - 2015
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229615004258
Subject(s) - concentric , cadmium , coordination polymer , polymer , materials science , crystallography , chemistry , geometry , mathematics , composite material , metallurgy
A homochiral helical three‐dimensional coordination polymer, poly[[(μ 2 ‐acetato‐κ 3 O , O ′: O )(hydroxido‐κ O )(μ 4 ‐5‐nicotinamido‐1 H ‐1,2,3,4‐tetrazol‐1‐ido‐κ 5 N 1 , O : N 2 : N 4 : N 5 )(μ 3 ‐5‐nicotinamido‐1 H ‐1,2,3,4‐tetrazol‐1‐ido‐κ 4 N 1 , O : N 2 : N 4 : N 5 )dicadmium(II)] 0.75‐hydrate], {[Cd 2 (C 7 H 5 N 6 O) 2 (CH 3 COO)(OH)]·0.75H 2 O} n , was synthesized by the reaction of cadmium acetate, N ‐(1 H ‐tetrazol‐5‐yl)isonicotinamide (H‐NTIA), ethanol and H 2 O under hydrothermal conditions. The asymmetric unit contains two crystallographically independent Cd II cations, two deprotonated 5‐nicotinamido‐1 H ‐1,2,3,4‐tetrazol‐1‐ide (NTIA − ) ligands, one acetate anion, one hydroxide anion and three independent partially occupied water sites. The two Cd II cations, with six‐coordinated octahedral and seven‐coordinated pentagonal bipyramidal geometries are located on general sites. The tetrazole group of one symmetry‐independent NTIA − ligand links one of the independent Cd II cations into 6 1 helical chains, while the other NTIA − ligand links the other independent Cd II cations into similar but unequal 6 1 helical chains. These chains, with a pitch of 24.937 (5) Å, intertwine into a double‐stranded helix. Each of the double‐stranded 6 1 helices is further connected to six adjacent helical chains through an acetate μ 2 ‐O atom and the tetrazole group of the NTIA − ligand into a three‐dimensional framework. The helical channel is occupied by the isonicotinamide groups of NTIA − ligands and two helices are connected to each other through the pyridine N and carbonyl O atoms of isonicotinamide groups. In addition, N—H...O and O—H...N hydrogen bonds exist in the complex.