4134
” 3
0
silane looking down the N-Si-C axis.
Figure 2. Top view of m-nitrophenyl(2,2’,2”-nitrilotriethoxy)-
Figure 3. Stereo view of molecular packing in m-nitrophenyl(2,2’,2 ’ ’-nitri1otriethoxy)silane.
nitro group is significantly larger than 120’. Other investigators have noted the same effect is-17 and the suggestion has been made that the strongly electronwithdrawing nitro group causes the C-N bond to have less than one-third s character. The nitro group is twisted by an angle of 16.6” from the plane of the benzene ring, a slightly larger twist angle than is found for m-dinitrobenzene (13 ‘ ) I 8 and 3-nitroperchlqrylbenzene (13°).1s Our C-N bond distance of 1.472 A is shqrter than the values found for m-dinitrobenzene (1!9.3 A), for N-methyl-N,2,4,6-tetranitroaniline (1.490 A), l9 and
for 3-nitroperchlorylbenzene (1.497 A). It has been observed that this distance is usually shortened in structures with strong resonance interaction between the nitro group and the ring, and the effect of the nitro substituent on the Si-N distance in our structure does require a strong nitro group-phenyl ring interaction. Molecular packing for this structure is illustrated in Figure 3. Bridge ring 1 is perpendicular to the phenyl ring both internally and externally, but strong dipoledipole interaction appears to dominate th? packing. The shortest intermolecular approach is 3.40 A.
(15) G. J. Palenik, J. Donohue, and I
