Synthesis, structure and magnetic properties of [Cu4(Hmbpp)2(H2NC(O)NH2)2(H2O)8]•4H2O

Cu-4(Hmbpp)(2)(H2NC(O)NH2)(2)(H2O)(8)] . 4H(2)O 1, the first example of a discrete polynuclear copper phosphonate complex isolated from aqueous media was synthesised by the addition of urea to a solution of a copper(II) salt and the bisphosphonic acid ligand 4-methyl-2,6-bis(phosphonomethyl) phenol (H(5)mbpp). 1 contains four distorted square pyramidal copper atoms and the Cu-4 units are linked by a complicated hydrogen bonded network involving co-crystallised water molecules.