X-ray diffraction and solid-state NMR studies of a germanium binuclear complex

A compound formulated as (C4H12N2)[Ge-2(pmida)(2)(OH)(2)]center dot 4H(2)O (where pmida(4-) = N-(phosphonomethyl)iminodiacetate and C4H12N22+ = piperazinedium cation), containing the anionic [Ge-2(pmida)(2)(OH)(2)](2-) Complex, has been synthesised by the hydrothermal approach and its structure determined by single-crystal X-ray diffraction analysis. Several high-resolution solid-state magic-angle spinning (MAS) NMR techniques, in particular two-dimensional H-1-X(C-13,P-31) heteronuclear correlation (HETCOR) and H-1-H-1 homonuclear correlation (HOMCOR) experiments incorporating a frequency-switched Lee-Goldburg (FS-LG) decoupling scheme, have been employed for the first time in such a material. Using these tools in tandem affords an Keywords: coordination modes germanium - bydrothermal synthesis - NMR spectroscopy - organicinorganic hybrid composites excellent general approach to study the structure of other inorganic-organic hybrids. We assigned the NMR resonances with the help of C center dot center dot center dot H and P center dot center dot center dot H internuclear distances obtained through systematic statistical analyses of the crystallographic data. The compound was further characterised by powder X-ray diffraction techniques, IR and Raman spectroscopy, and by elemental and thermal analyses (thermogravimetric analysis and differential scanning calorimetry).