The synthesis, magnetic properties and crystal structure of a Cu(II) methylenediphosphonate, [Cu2(O3PCH2PO3)]

The hydrothermal reaction of Cu(SO4)·5H2O, methylenediphosphonate and water in the mole ratio 1.0:1.5:4100 at 150 °C for 48 h yielded clear colorless crystals of [Cu2(O3PCH2PO3)] (1). The structure of 1 is a three-dimensional framework constructed from chains of edge-sharing {CuO5} trigonal bipyramids linked through the {O3PCH2PO3}4− subunits. The magnetic data from 35 to 300 K were fit to the Heisenberg linear antiferromagnetic chain model, giving g=1.98 and J/kB=−35.9 K. At lower temperatures, a Néel transition suggests three-dimensional long-range ordering. Crystal data: CH2Cu2O6P2, orthorhombic, Pnma, a=13.698(1), b=8.0094(6), c=4.8950(4) Å, V=537.04(7) Å3, Z=4, Dcalc=3.699 g cm−3.