New Inorganic–Organic Coordination Polymers Generated from Rigid or Flexible Bidentate Ligands and Co(NCS)2·xH2O

Abstract

The coordination chemistry of the long rigid bidentate Schiff-base ligands 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene (L1), 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene (L2), and of the flexible ligand 1,3-bis(4-pyridyl)propane with Co(NCS)2·xH2O has been investigated. Three new coordination polymers were prepared and fully characterized by infrared spectroscopy, elemental analysis, thermogravimetric analysis, and single-crystal X-ray diffraction. The magnetic behavior of all compounds was also investigated and found to follow the Curie law. [Co(NCS)2(L1)2·2CH2Cl2]n (1, monoclinic, C2/m; a= 11.995(2) Å, b=14.596(3) Å, c=10.846(2) Å, β=110.99(3)°, Z=2) features a two-dimensional non-interpenetrating distorted square pattern. [Co(NCS)2(L2)2]n (2, monoclinic, P21/n; a=9.5315(19) Å, b=17.299(4) Å, c=9.6646(19) Å, β=99.11(3)°, Z=2) features a one-dimensional ring-like chain motif. Important C–H···S hydrogen bonding interactions exist in 2, which play a significant role in aligning the polymer strands in the crystalline solid. [Co(1,3-bis(4-pyridyl)propane)2(NCS)2·0.33 H2O]n (3, monoclinic, P21/n; a=18.701(4) Å, b=16.593(3) Å, c=20.696(4) Å, β=114.45(3)°, Z=4) exhibits a polymeric pattern similar to that of 1. All three compounds feature similar {CoN6} pseudooctahedral coordination spheres.