Two nickel(II) bis[(pyridin-2-yl)methyl]- amine complexes with homophthalic and benzene-1,2,4,5-tetracarboxylic acids

Abstract

Two new NiII complexes involving the ancillary ligand bis[(pyridin-2-yl)methyl]amine (bpma) and two different carboxylate ligands, i.e. homophthalate [hph; systematic name: 2-(2-carboxylatophenyl)acetate] and benzene-1,2,4,5-tetracarboxylate (btc), namely catena-poly[[aqua{bis[(pyridin-2-yl)- methyl]amine-k3N,N',N''}nickel(II)]-u-2-(2-carboxylatophenyl) aceteto-k2O:O'], [Ni(C9H6O4)(C12H13N3)(H2O)]n, and (u- benzene-1,2,4,5-tetracarboxylato-k4O1,O2:O4,O5)bis(aqua{bis- [(pyridin-2-yl)methyl]amine-k3N,N',N''}nickel(II)) bis(triaqua{ bis[(pyridin-2-yl)methyl]amine-k3N,N0,N00}nickel(II)) benzene-1,2,4,5-tetracarboxylate hexahydrate, [Ni2(C10H2O8)- (C12H13N3)2(H2O)2].[Ni(C12H13N3)(H2O)3]2(C10H2O8).6H2O, (II), are presented. Compound (I) is a one-dimensional polymer with hph acting as a bridging ligand and with the chains linked by weak C—H...O interactions. The structure of compound (II) is much more complex, with two independent NiII centres having different environments, one of them as part of centrosymmetric [Ni(bpma)(H2O)]2(btc) dinuclear complexes and the other in mononuclear [Ni(bpma)(H2O)3]2+ cations which (in a 2:1 ratio) provide charge balance for btc4- anions. A profuse hydrogen-bonding scheme, where both coordinated and crystal water molecules play a crucial role, provides the supramolecular linkage of the different groups.