Experimental separation of the coherent component of X-ray scattering prior to RDF analysis of non-crystalline polymers

An experimental method is described which enables the inelastically scattered X-ray component to be removed from diffractometer data prior to radial density function analysis. At each scattering angle an energy spectrum is generated from a Si(Li) detector combined with a multi-channel analyser from which the coherently scattered component is separated. The data obtained from organic polymers has an improved signal/noise ratio at high values of scattering angle, and a commensurate enhancement of resolution of the RDF at low r is demonstrated for the case of PMMA (ICI `Perspex'). The method obviates the need for the complicated correction for multiple scattering.

The molecular structure and one-pot synthesis of [Li(thf)3·Sn(SiMe3)3]

The molecular structure of [Li(thf)3 · Sn(SiMe3)3], prepared by a new, one-pot synthesis in 44% yield, has been determined by a single crystal X-ray diffraction study using synchrotron radiation and a CCD detector. The +Li(thf)3 and −Sn(SiMe3)3 moieties are joined by a Li–Sn bond, 2.865(5) Å in length. [Li(thf)3 · Sn(SiMe3)3] is isomorphous with its germanium analogue.