Synthesis and structure of the framework scandium methylphosphonates ScF(H2O)CH3PO3 and NaSc(CH3PO3)2.0.5H2O.

Two framework scandium methylphosphonates have been prepared hydrothermally and their structures solved. ScF(H(2)O)CH(3)PO(3) is a non-porous solid built up from -ScF- chains linked by methylphosphonate groups. The ScO(4)F(2) octahedra are completed by a coordinated water molecule. NaSc(CH(3)PO(3))(2).0.5H(2)O was solved ab initio from high-resolution synchrotron X-ray powder diffraction data. It has a fully connected, negatively charged scandium phosphonate framework where ScO(6) octahedra share vertices with PO(3)CH(3) groups. The solid contains charge balancing sodium cations, coordinated by a water molecule, which may be reversibly removed and adsorbed. The structure of the perdeuterated, dehydrated solid has been refined against neutron powder diffraction data collected at 2.5 K, showing the CD(3) groups in a fully staggered orientation with respect to the phosphonate oxygen atoms.