Ladder-like metal diphosphonates exhibiting field-induced magnetic transitions

Two new isomorphous phosphonates M(ahbdpH2) · H2O [M = Mn (1), Co (2); ahbdpH4 = 4-amino-1-hydroxybutane-1,1-diphosphonic acid, C4H13NO7P2] have been hydrothermally synthesized. Both exhibit a ladder-like chain structure in which the edge-shared {MO6} octahedra are linked by {CPO3} tetrahedra through corner-sharing. The double chains are connected through extensive hydrogen bonds among amino groups, phosphonate oxygen atoms and lattice water molecules, hence generating a three-dimensional network. Magnetic measurements reveal that both experience field-induced magnetic transitions at low temperature.