Ladder-like metal diphosphonates exhibiting field-induced magnetic transitions

Abstract Two new isomorphous phosphonates M(ahbdpH 2 ) · H 2 O [M = Mn ( 1 ), Co ( 2 ); ahbdpH 4  = 4-amino-1-hydroxybutane-1,1-diphosphonic acid, C 4 H 13 NO 7 P 2 ] have been hydrothermally synthesized. Both exhibit a ladder-like chain structure in which the edge-shared {MO 6 } octahedra are linked by {CPO 3 } 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.