Synthesis and characterization of (R-C5H14N2)2[Ga4(C2O4)(H2PO4)2(PO4)4].2H2O, a layered gallium phosphatooxalate containing a chiral amine.

The first metal phosphatooxalate containing a chiral amine, (R-C5H14N2)2[Ga4(C2O4)(H2PO4)2(PO4)4].2H2O, has been synthesized hydrothermally and characterized by single-crystal X-ray diffraction and 31P MAS NMR spectroscopy. It crystallizes in the monoclinic space group P2(1) (No. 4) with a = 8.0248(4) A, b = 25.955(1) A, c = 9.0127(5) A, beta = 100.151(1) degrees, and Z = 2. The structure consists of GaO6 octahedra and GaO4 tetrahedra connected by coordinating C2O4(2-) and phosphate anions to form anionic sheets in the ac plane with charge-compensating diprotonated R-2-methylpiperazinium cations and water molecules between the layers. There is a good correlation between the NMR spectrum and the structure.