STRUCTURAL STUDIES OF PENTACOORDINATE SILICON .4. M-NITROPHENYL(2,2',2''-NITRILOTRIETHOXY)SILANE

The molecular and crystal structures of m-nitrophenyl(2,2ʹ,2ʹʹ-nitrilotriethoxy)silane, SiO5N2C12H16, have been determined by three-dimensional X-ray diffraction methods. This material crystallizes in space group P21/c with a = 10.102, b = 11.013, and c = 12.961 Å, β10.28°= 4. The intensity data were collected on a Picker automatic diffractometer and the structure was solved by direct methods. All hydrogen atoms were located. Refinement by full-matrix least-squares gave a final reliability index of R1= 0.061 for 1350 reflections above background. The molecular geometry at silicon is a distorted trigonal bipyramid, but the distortion, as measured by the average C-Si-O angle of 95.8° is less than that found for the other structures in this series. Also, the Si-N distance of 2.116 Å is shorter than observed previously. The three equatorial Si-O distances are 1.656, 1.661, and 1.650 Å, a d the Si-C distance is 1.904 Å. The plane of the nitro group is at an angle of 16.6° to the plane of the phenyl ring, and the N-O distances are 1.239 and 1.203 Å. © 1969, American Chemical Society. All rights reserved.