J. Phys. Chem. 1992, 96,7978-7982
7978
dl\
I\
1
2
3
EXPERIllENTRL
4
5
6
7A
Figure 3. Radial distribution curve8 for tetrabromoformaldazine. The experimental curve is calculated from the composite of the two average intensity curves with use of theoretical data for the region 0 5 s/A-I S 2.25, and B / A =~ 0.0025. The vertical lines indicate the interatomic distances and have lengths proportional to the distance weights. Torsion dependent distances are shown for #I = 120O.
to be expected since the van der Waals radius of the bromine atom is the larger by about 0.15 A. Also consistent with this picture is the observation that T~ has a larger value for the tetrabromo
compound than for the tetrachloro compound (Q = 59 (9)' for C2N2Br4and 41 (7)' for C2N2C14). There are some small differences in the values of the bond lengths and valence angles obtained in our two studies (the early values are r,(C-N) = 1.266 (8) A, r,(N-N) = 1.381 (18) A, rJC-Br) = 1.877 ( 5 ) A, LN-NSC = 114.5 (la)', LN
