Synthesis, crystal structure and magnetic properties of an unexpected new coordination Cu(II) compound, containing two different phosphato-bridged dinuclear units; [Cu2(phen)2(μ-H2PO4-O,O′)2(H2PO4)2][Cu2(phen)2(μ-H2PO4-O,O′)(μ-H2PO4-O)(μ-HPO4-O)]2

The crystal structure of [Cu2(phen)(μ-H2PO4-O,O′)2(H2PO4)2][Cu2(phen)2(μ-H2PO4-O,O′)(μ-H2PO4-O)(μ-HPO4-O)]2(H2O)9 containing the phen ligand with mono- and di-dentate H2PO4- and monodentate HPO42- oxoanions is reported. Two crystallographically independent dinuclear units with different bridging properties of (di)hydrogenphosphato anions are found in this compound. The two Cu(II) ions in the first unit, [Cu2(phen)(μ-H2PO4-O,O′)2(H2PO4)2], are bridged by two didentate bridging dihydrogenphosphato monoanions with two non-bridging monovalent dihydrogenphosphato anions. The Cu-Cu distance is 5.043(3) Å. The magnetic susceptibility measurement (5-300 K) revealed a weak antiferromagnetic interaction between the Cu ions in one dinuclear unit with J1 = −8.2 cm−1 and a very weak ferromagnetic interaction in the other dinuclear unit with J2 = 0.96 cm−1.