Coordination polymers of cobalt(II) with pyrimidine and pyrazine: Syntheses, structures and magnetic properties

New 2D-polymeric compound [Cot(mu-OH2)(mu-Piv)(2)(Piv)(2)(mu-L-1)(2)](n) (2) was synthesized in the reaction of the cobalt(II) pivalate [Co(Piv)(2)](n) (1, Piv is an anion of pivalic acid) and pyrimidine (L-1) in MeCN. 3D-polymer [Co-5(mu-OH2)(mu(3)-OH)(mu(3)-Piv)(mu-Piv)(5)(Piv)(3)(mu-L-2)(4)](n) (3) was prepared by the reaction of the polymer [Co(Piv)(2)](n) (1) with pyrazine (L-2). Complexes 2 and 3 were characterized by the X-ray diffraction and magnetic susceptibility. It was shown that compound 2 undergoes antiferromagnetic ordering with weak ferromagnetism at T-N = 4.5 K with sigma(0)(2 K) = 4000 G cm(3)/mol. Crown Copyright (C) 2008 Published by Elsevier B.V. All rights reserved.