Synthesis and Structural Characterization of a New Layered Aluminophosphate Intercalated with Triply-Protonated Triethylenetetramine [C6H21N4][Al3P4O16]

A new layered aluminophosphate [C6H21N4][Al3P4O16] has been synthesized solvothermally by using triethylenetetramine (tetam) as the structure-directing agent and ethylene glycol as the solvent. The structure of the compound was solved by single-crystal X-ray diffraction analysis. [C6H21N4][Al3P4O16] crystallizes in the monoclinic space group P21/c with a=9.550 (1), b=24.064(1), c=9.601(1) ?, BETA=97.99(1)°, V=2184.9(1) ?3 and Z=4 (R=0.057 and Rw=0.052), and its structure consists of [Al3P4O16]3- macroanionic sheets stacked in an AAAA sequence. As primary building units in the individual sheet, alternating PO4 with terminal P=O and AlO4 tetrahedra are corner-shared to form elliptical eight-membered rings as well as four- and six-membered rings. The macroanionic sheets are held together through H bonds between the terminal P=O groups in the inorganic layers and the N atoms of the tetam molecules, which are triply-protonated.