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and others6 shows that fluorocarbon complexation, although weak, may be a common phenomenon in the coordination chemistry of fluorocarbons, at least for coordinatively unsaturated metal centers. The 19F coordination shift and, in suitable cases, the observation (21) Cromer, D.

S02CF3)2] was secured to the end of a glass fiber with 5-min epoxy resin. The crystal was maintained at -90 ± 1 °C during lineup and data collection. The crystal was found to belong to the monoclinic crystal class by the Enraf-Nonius CAD 4-SDP peak search, centering, and indexing programs.40 Background counts were measured at both ends of the scan range with use of an -2ß scan, equal, at each side, to one fourth of the scan range of the peak. In this manner, the total duration of background measurements is equal to half of the time required for the peak scan. The intensities of three standard reflections were measured every 1.5 h of X-ray exposure, and no decay was noted. The data were corrected for Lorentz, polarization, and background effects and for the effects of absorption (µ = 22.0 cm"1). An empirical absorption correction was applied by using the SDP program eac.39 Solution and Refinement of the Structure. The structure was solved by conventional heavy-atom techniques. The Os atom was located by Patterson synthesis. Full-matrix least-squares refinement and difference-Fourier calculations were used to locate all the remaining hydrogen atoms. The atomic scattering factors were taken from the usual tabulation,41 and the effects of anomalous dispersion were included in Fc by using Cromer and Ibers'42 values of /' and /". In the final leastsquares cycle, the largest parameter shift was 0.05 times its esd. The final difference-Fourier map did not reveal significant residual electron density except in the region approximately 1 Á from the Os atom. The highest peak in this region was 5 e Á"3. Phenyl hydrogen atom positions were calculated (

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