Synthesis, characterization of a new open-framework gallium phosphite containing 5,6-fold coordinate gallium atoms

A new open-framework gallium phosphite Ga5(OH)2(HPO3)8(C4N3H16) · 2H2O (1) is synthesized solvothermally using diethylenetriamine (DETA) as template from a mixed solvent system in which ethylene glycol (EG) was used as the co-solvent. The as-synthesized product is characterized by single crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, thermogravimetric analysis (TGA), ICP-AES and elemental analyses. The three-dimensional open-framework of compound 1 is constructed from two novel secondary building units (SBUs), Ga2O7(OH)(HPO3) three-membered ring (3R) and Ga(HPO3)6 tooth-wheel type unit. These two novel secondary building units are first found in gallium phosphate/phosphite, which lead to form the one-dimensional 8-membered ring channels along the a-axis. Moreover, it is noted that compound 1 is the first gallium phosphite containing 5-fold coordinate gallium atom.