New metal phosphonates containing coordination piperazine or pyridyl groups

Abstract

Reactions of transition metal(II) salts with three aminophosphonic acids, 1-[(H 2O 3PCH 2) 2NCH 2CH 2−]-piperazine-4-CH 2PO 3H 2 (H 6L 1), 3-pyridyl-CH 2N(CH 2PO 3H 2) 2 (H 4L 2) and 4-pyridyl-CH 2N(CH 2PO 3H 2) 2 (H 4L 3) afforded three new metal phosphonates, namely, Cu(H 4L 1)·2H 2O (1), Co(H 3L 2) 2·H 2O (2) and [Co(H 2L 3)(H 2O)]·H 2O (3). The structure of compound 1 features a 1D chain in which the CuN 2O 3 and CPO 3 polyhedra are interconnected by bridging phosphonate ligands to form 1D chains. Compound 2 has a layered structure. The cobalt(II) ions in the octahedral coordination geometries and {CPO 3} tetrahedra are interconnected into an inorganic chain via –N(CH 2PO 3H) 2 moieties, and adjacent chains are further bridged by the coordination pyridyl groups of H 3L 2 into a 2D layer. The structure of compound 3 features a 2D double layered structure, in which the Co(II) ions are interconnected by bridging phosphonate groups into a 1D chain along b-axis. Neighboring chains are interconnected by coordination pyridyl groups into a double layer perpendicular to the c-axis.