Study of the aqueous reactions of metallic ions with benzenetetracarboxylate ions Part 2. Crystal structures of compounds of the type M(H2O)(5)(mu-C6H2(COO)(4))M(H2O)(5) (M = Mn and Co) and a novel mixed-metallic Mn-Co dimeric compound

The reactions of barium 1,2,4,5-benzenetetracarboxylate with CoSO4 produced the dinuclear species Co(H2O)(5)(mu -C6H2(COO)(4))Co(H2O)(5) which was cha racterized by crystallographic methods. The results have shown that the com pound belongs to the monoclinic C2/c space group and it crystallized with s ix molecules of water in the lattice. The crystal is stabilized by a very e laborate H-bonded 3D network. The molecule contains an inversion center. Th e average Co-OH2 distance is 2.0710(8) Angstrom and the sixth Co-O bond is 2.0356(7) Angstrom. The reaction of MnCl2 with benzenetetracarboxylate ions produced a similar dinuclear species, Mn(H2O)(5)(mu -C6H2(COO)(4))Mn(H2O)( 5).H2O (2). The crystallographic results have shown that there are two inde pendent molecules, which each contains an inversion center. This compound c rystallized with only one molecule of water, and again the H-bonding system is very elaborate. The aqueous reaction of K2Mn(C6H2(COO)(4)). 3H(2)O with CoSO4 produced a compound containing two dinuclear species {Mn(H2O)(5)(mu -C6H2(COO)(4))Mn(H2O)(5)} {Co(H2O)(5)(mu -C6H2(COO)(4))Co(H2O)(5)}. 2H(2)O, which was characterized by X-ray diffraction methods. The results have sho wn that the latter compound is isomorphous with the Mn(II) compound. One of the Mn(II) dimer in 2 has been replaced by a Co(II) dimer. (C) 2001 Elsevi er Science B.V. All rights reserved.