Hydrothermal synthesis, characterization and crystal structures of two new zinc (II) phosphonates: Zn_2[(O_3PCH_2)_2NHCH_2CO_2] and Zn_[HO_3PCH_2NH(CH_2PO_3)_2]

摘要

The hydrothermal r4eaction of zinc(II) acetate with N,N-bis (phosphonomethyl) aminoacetic acid [(H_2O_3PCH_2)_2NCH_2CO_2H, H_2L~1] and nitrilotris (methylenephosphonic acid) [N(CH_2PO_3H_2)_3, H_6L~2] at 180 deg C afforded two new zinc coordination polymers with a similar 3D network structure. Zn_2[(O_3PCH_2)_2NHCH_2CO_2] (complex 1) is hexagonal, P6_1, with a = 8.0677(12), c = 27.283(6) A, u = 1537.9(5) A~3, Z = 6. In complex 1, the Zn(II) atoms are tetrahedrally coordinated by three phosphonate oxygen aotms and one carboxylate oxygen atom from four ligands. The ZnO_4 tetrahedra are further interconnected through bridging phosphonate and carb oxylate groups into a three dimensional network. Zn_2[HO_3PCH_2NH(CH_2PO_3)_2] (complex 2) is also hexagonal, P6_1 with a = 8.3553 (8), c = 26.657(4) A, u = 1611.6(3) A~3, Z = 6. The structure of complex 2 features a 3D network built from ZnO_4 tetrahedra linked together by bridging phosphonate groups. One zinc and three phosphonate oxygen atoms are disordered. The two zinc atoms in the asymmetric unit are tetrahedrally coordinated by four phosphonate oxygen aotms of four ligands. Each ligand connects with eight zinc atoms. The effect of the extent of deprotonation of phosphonic acids and substitution groups on the type of complexes formed are discussed.