X-ray Crystallography; Experimental
Intensity data were measured at 21±1 C by using w/2q scans (2qmax = 48 ) on a Nicolet R3mV diffractometer with graphite-monochromated Mo Ka radiation (l = 0.71073 Å). The data were corrected for Lorentz and polarization effects; the intensities of three reflections, remeasured periodically throughout data collection varied by less than 2%, indicating no need for a decay correction. An absorption correction, based on azimuthal scans of several intense reflections, was applied to the data. The structures were solved by direct methods and refined by using full-matrix least-squares techniques. All non-hydrogen atoms were refined anisotropically and all hydrogen atoms were refined with isotropic thermal parameters. Structure solution, refinement and the calculation of derived results were perforemd with the SHELXTL package of computer programs. Neutral atom scattering factors and the real and imaginary anomalous dispersion corrections were taken from International Tables for X-ray Crystallography, Vol. IV . Relevant crystallographic data are given in Table 1.
1. Sheldrick, G.M. SHELXTL, Crystallographic Computing System; Nicolet Instruments Division: Madison, WI, 1986.
2. International Tables for X-ray Crystallography, Vol. IV, The Kynoch Press, Birmingham England, 1974.