A novel 2D phosphomolybdate hybrid [Cu(En)(EnH)]2[P2Mo5O23] · 3H2O constructed from strandberg-type polyoxometalate units and copper-organic cation bridges

A 2D Strandberg-type phosphomolybdate hybrid [Cu(En)(EnH)]2[P2Mo5O23] · 3H2O (I) (En = ethylenediamine) has been successfully synthesized under hydrothermal conditions and structurally characterized by elemental analyses, IR spectrum, UV spectrum and single-crystal X-ray diffraction. The molecular structural unit of I consists of one Strandberg-type [P2Mo5O23]6− subunit, two [Cu(En)(EnH)]3+ cations and three lattice water molecules. The most remarkable feature of I is that each molecular structural unit is connected with adjacent four same units by four [Cu(En)(EnH)]3+ bridges constructing the 2D organic-inorganic hybrid sheet structure with a 4-connected topology. As far as we know, such 2D hybrid sheet structure constructed from Strandberg-type phosphomolybdate units and copper-organic cation bridges is very rare.