Synthesis and structure of the framework scandium methylphosphonates ScF(H2O)CH3PO3 and NaSc(CH3PO3)(2)center dot 0.5H(2)O

Two framework scandium methylphosphonates have been prepared hydrothermally and their structures solved. ScF(H2O) CH3PO3 is a non-porous solid built up from - ScF - chains linked by methylphosphonate groups. The ScO4F2 octahedra are completed by a coordinated water molecule. NaSc(CH3PO3)(2) center dot 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 ScO6 octahedra share vertices with PO3CH3 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 CD3 groups in a fully staggered orientation with respect to the phosphonate oxygen atoms.