Viewing the Supplemental Information

. Molecular coordinates are present in the form of MDL Molfiles, which can be viewed within a Web browser using appropriate software such as MDL Chime (http://www.mdlchime.com/) or Chem3D viewer (http://www.cambridgesoft.com/) To view 3D models of the orbital models linked to the thumbnail diagrams in Figure 1, you will need a 3DMF viewer such as 3DMFPlugin, 3DMF Optimizer (a Macintosh application), Geo3D (for Mac) or 3DMF Viewer for Windows. Windows users must also install the QuickDraw3D libraries from Apple.

Table 1. Representative examples in the Cambridge Database exhibiting structural features of 2 - 5.a

yetreu/B(III)b perjeb/Al(III)c zohvib/Al(III)d ubiqur/In(III)e
kezqah/Ga(III)f gukdiz/Si(IV)g gukdul/Ge(IV)g gajfus/Sn(IV)h
mspaps/P(V)i paqwuz/P(V)j eapdop10/P(V)k doxlor/As(V)l
hegday/Sb(V)m yegduj/Bi(III)n tpcate/Te(IV)o tectcl/Te(IV)p
qirpuc/La(III)q qazreo/Y(III)r govsoz/Ti(IV)s cigtuh/Ti(IV)t
bzdtzr10/Zr(IV)u HOVTUH/V(IV)v rilhoj/Nb(V)w bzdtnb10/Nb(V)x
cuqgea/Cr(III)y doxqai/Cr(V)z sixwif/Mo(V)z gefkor/W(IV)aa
aCambridge reference code and oxidation state of X as determined from the charge on the counter ions (not shown). b K. Ishihara, M. Miyata ,K. Hattori, T. Tada and H. Yamamoto J. Am. Chem. Soc., 1994, 116, 10520. cT. Arai, H. Sasai, K. Yamaguchi and M.S Hibasaki J. Am. Chem. Soc., 1998, 120, 441. dT. Arai, H. Sasai, K. Aoe, K. Okamura, T.Date, M. Shibasaki Angew.Chem.,Int.Ed.Engl., 1996, 35, 104. eS. Chitsaz and B. Neumuller Organometallics, 2001, 20, 2338. fS. Matsunaga, J. Das, J. Roels, E. M. Vogl, N. Amamoto, T. Iida, K.Yamaguchi and M.Shibasaki J. Am. Chem. Soc., 2000, 122, 2252. g R. Tacke, A. Stewart, J. Becht, C. Burschka and I.Richter, Can.J.Chem., 2000, 78, 1380. h R. R. Holmes, S. Shafieezad, V. Chandrasekhar, A. C. Sau, J. M. Holmes, R. A. Day J. Am. Chem. Soc., 1998, 110, 1168. iH. Wunderlich Acta Crystallogr.,Sect.B, 1981, 37, 995. jD. J. Sherlock, A. Chandrasekaran, T. K. Prakasha, R.O.Day, R. R. Holmes Inorg. Chem., 37, 93. kH. R. Allcock, E. C. Bissell J. Am. Chem. Soc., 1973, 95, 3154. lB. A. Borgias, G. G. Hardin, K. N. Raymond Inorg. Chem., 1986, 25, 1057. mJ. Wegener, K. Kirschbaum and D. M. Giolando J. Chem. Soc., Dalton Trans., 1994, 1213. nG. Smith, A. N. Reddy, K. A. Byriel and C. H. L. Kennard Aust. J. Chem., 1994, 47, 1413. oK. von Deuten, W. Schnabel, G. Klar Cryst. Struct. Commun., 1980, 9, 161. pO. Lindqvist Acta Chem.Scand., 1967, 21, 1473. qT. Nemoto, T. Ohshima, K. Yamaguchi and M. Shibasaki J.Am.Chem.Soc., 2001, 123, 2725. rH. C. Aspinall, J. F. Bickley, J. L. M. Dwyer, N. Greeves, R. V. Kelly and A. Steiner Organometallics, 2000, 19, 5416. sTing-Bin Wen, Bei-Sheng Kang, Cheng-Yong Su, Da-Xu Wu, Li-Ge Wang, Sen Liao and Han-Qin Liu Bull.Chem.Soc.Jpn., 1998, 71, 2339. tB. A. Borgias, S. R. Cooper,Y. B. Koh and K. N. Raymond Inorg. Chem., 1984, 23, 1009. uM. Cowie and M. J. Bennett Inorg.Chem., 1976, 15, 1595. vBei-Sheng Kang, Xiu-Jian Wang, Cheng-Yong Su ,Han-Qin Liu, Ting-Bin Wen and Qiu-Tian Liu Transition Met.Chem., 1999, 24, 712. wP. R. Challen, D. H. Peapus and K. A. Magnus, Polyhedron, 1997, 16, 1447. xM. Cowie and M. J. Bennett, Inorg. Chem., 1976, 15, 1589. yR. J. Cross, L. J. Farrugia, D. R. McArthur, R. D. Peacock and D. S. C. Taylor, Inorg.Chem., 1999, 38, 5698. zHo-Chol Chang, S. Kitagawa, M. Kondo and T. Ishii, Mol. Cryst. Liq. Cryst. Sci. Technol.,Sect.A, 1999, 335, 183. aaC. Lorber, J. P. Donahue, C. A. Goddard, E. Nordlander and R. H. Holm, J. Am. Chem. Soc., 1998, 120, 8102.
Table 2. B3LYP/6-31G(d) Calculated energies (Hartree) and NICSa Values (ppm) for 1-5
Substituentsb Energy, Y=O NICS (angle)a Energy, Y=NR NICS (angle)a
1, X=N, R=H -359.53314 17.4 (45.7) -319.93038
 26.7 (34.9)
1, X=N, R=F -756.39305 (365.7i)c 11.1 (54.0) -915.07525 (189.9i)c
 -1.0 (59.0)
1, X=P, R=H -646.31012 18.6 (23.7) -606.60521
 19.4 (38.0)
1, X=P, R=F -1043.17777 (167.6i)c 14.3 (41.2) -1201.76006 (112.6i)c
 -2.0 (54.6)
2, RR, X=N, R=H -664.72355 -1.3 (76.6) -585.371678
 -2.8 (73.8)
2, RR, X=N, R=F d d -1775.73438
 -9.0 (84.3)
2, RR, X=P, R=H -951.62957 -0.2 (56.6) -872.17703
 -0.7 (55.4)
2, RS, X=P, R=H 0.2e -0.3 (57.4) 4.8e
 -0.7 (54.2)
2, RR, X=P, R=F -1745.37896 -4.5 (63.2) -2062.50669
 -9.3 (64.7)
2, RS, X=P, R=F 0.9e -4.5 (62.9) -0.6e
 -8.8 (60.0)
4, X=P, R=H -796.78568 -7.4 (0.0) -717.36303
 -9.8 (0.0)
3, RRS, X=Al, R=H -1158.153405 0.2, 0.3 (33.5, 34.4) -1038.79166
 0.0, 0.1 (39.0, 39.1)
3, RRS, X=Si, R=H -1205.36111 -1.0, -0.4 (43.0, 53.0) -1086.03770
 -1.4, -1.6 (42.5, 42.3)
3, RRS, X=Ge, R=H -2990.82401 -2.5,-2.3 (57.7, 58.9) -2871.52125
 -2.2,-2.9 (44.5, 53.9)
3, RRS, X=P, R=H -1257.16780 -2.6, -2.7 (67.2, 66.9) -1137.8865
-3.4,-3.4 (42.0, 53.9)
3, RRR, X=P, R=H 1.7e -2.2 (66.5) -4.7e
 -4.2 (55.0)
3, RRS, X=P, R=F -2447.98997 -6.7, -6.9 (69.2, 69.0) -2923.62738
 -9.4, -10.0 (69.2, 69.0)
3, RRR, X=P, R=F 0.8e -6.6 (69.3) 5.0e
 -10.2 (62.8)
3, RRS, X=As, R=H -3149.58333 -3.7,-3.4 (67.3, 68.3) -3030.31362
 -4.3, -4.4 (56.7, 58.8)
5, X=P, R=H -1024.96531 -6.3 (0.0) -905.65126
 -3.0 (0.0)

aNICS(0) value, ppm (dihedral angle a-b-c-d). b The designation RR/RS or RRR/RRS indicates relative rather than absolute chiral configurations for the 7-membered rings. c Wavenumber for imaginary normal mode corresponding to distortion to 6. d Dissociates to C4F4O2 and C4F4NO2+. e Energy (kcal/mol) relative to chiral diastereomer.