Hydrothermal syntheses, characterizations and crystal structures of a new lead(II) carboxylate-phosphonate with a double layer structure and a new nickel(II) carboxylate-phosphonate containing a hydrogen-bonded 2D layer with intercalation of ethylenediamines

Hydrothermal reactions of <f>N</f>,<f>N</f>-bis(phosphonomethyl)aminoacetic acid (HO2CCH2N(CH2PO3H2)2) with metal(II) salts afforded two new metal carboxylate-phosphonates, namely, Pb2[O2CCH2N(CH2PO3)(CH2PO3H)]·H2O (1) and {NH3CH2CH2NH3}{Ni[O2CCH2N(CH2PO3H)2](H2O)2}2 (2). Among two unique lead(II) ions in the asymmetric unit of complex 1, one is five coordinated by five phosphonate oxygen atoms from 5 ligands, whereas the other one is five-coordinated by a tridentate chelating ligand (1 N and 2 phosphonate O atoms) and two phosphonate oxygen atoms from two other ligands. The carboxylate group of the ligand remains non-coordinated. The bridging of above two types of lead(II) ions through phosphonate groups resulted in a 〈002〉 double layer with the carboxylate group of the ligand as a pendant group. These double layers are further interlinked via hydrogen bonds between the carboxylate groups into a 3D network. The nickel(II) ion in complex 2 is octahedrally coordinated by a tetradentate chelating ligand (two phosphonate oxygen atoms, one nitrogen and one carboxylate oxygen atoms) and two aqua ligands. These {Ni[O2CCH2N(CH2PO3H)2][H2O]2}− anions are further interlinked via hydrogen bonds between non-coordinated phosphonate oxygen atoms to form a 〈800〉 hydrogen bonded 2D layer. The 2H-protonated ethylenediamine cations are intercalated between two layers, forming hydrogen bonds with the non-coordinated carboxylate oxygen atoms. Results of magnetic measurements for complex 2 indicate that there is weak Curie–Weiss behavior with <f>θ=−4.4</f> K indicating predominant antiferromagnetic interaction between the Ni(II) ions. Indication for magnetic low-dimension magnetism could not be detected. [Copyright &y& Elsevier]