Supplementary Material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2001
SUPPLEMENTARY MATERIAL
Triple Decker Main Group Cations
Alan H. Cowley*, Charles L. B. Macdonald, Joel S. Silverman, John D. Gorden and Andreas Voigt
Department of Chemistry and Biochemistry
The University of Texas at Austin
Austin, Texas 78712
Supplementary Material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2001
Summary of Theoretical Results
All calculations done with the Gaussian 941 package of programs. Each molecule/ion was fully optimized in the
indicated symmetry. Bond lengths in Å, angles in degrees, X t is the centroid of a terminal aromatic ring, Xb is the
centroid of the bridging aromatic ring and dihedral is defined as the angle between the two planes defined by the points
(Xt,n, Mn, and Xb) for n=1 and n=2 (0 = cisoid, 180 = transoid).
BP862/A3,4
In+
CpIn
[InCpIn]+
Symmetry
C5v
D5h
Energy (au)
-1.6620558
-195.4527391
-197.1866895
CpIn + In+ 
[InCpIn]+
H (Kcal/mol)
-45.11
C6H6
[(C6H6)In]+
Symmetry
D6h
C6v
Energy (au)
-232.2333777
-233.9481026
C6H6 + In+ 
[C6H6-In]+
H (Kcal/mol)
-33.05
[(C6H6)InCpIn(C6H6)]+
Symmetry
C1
Energy (au)
-661.685627
2 C6H6 + [InCpIn]+ 
[(C6H6)InCpIn(C6H6)]+
Average Bond Energies
H (Kcal/mol)
-20.19
(Kcal/mol)
(Kcal/mol)
[(C6H6)InCpIn-(C6H6)]+
[(C6H6)InCp-In(C6H6)]+
6.64
42.36
M-Xt
M-Xb
2.328
2.515
M-Xt
M-Xb-M
Xt-M-Xb
Dihedral
180
M-Xb
M-Xb-M
Xt-M-Xb
Dihedral
M-Xb
2.591
M-Xb-M
176.3
Xt-M-Xb
143.3
Dihedral
23.5
M-Xb
M-Xb-M
Xt-M-Xb
Dihedral
2.773
178.0
149.9
148.9
61.0
2.621
M-Xt
3.069
B3LYP5/A3,4
CpSn+
Cp2Sn
[CpSnCpSnCp]+
Symmetry
C5v
C2v
C1
Energy (au)
-196.6881022
-390.4229961
-587.1545468
CpSn+ + Cp2Sn 
[Cp3Sn2]+
H (Kcal/mol)
-27.26
Average Bond Energies
(Kcal/mol)
[CpSnCp-SnCp]+
[CpSnCpSn-Cp]+
36.63
265.32
1
M-Xt
2.196
2.504
2.331
Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Gill, P. M. W.; Johnson, B. G.; Robb, M. A.; Cheeseman, J. R.; Keith,
T. A.; Petersson, G. A.; Montgomery, J. A.; Raghavachari, K.; Al-Laham, M. A.; Zakrewski, V. G.; Ortiz, J. V.;
Foresman, J. B.; Cioslowski, J.; Stefanow, B. B.; Nanayakkara, A.; Challacombe, M.; Peng, C. Y.; Ayala, P. Y.; Chen,
W.; Wong, M. W.; Andres, J. L.; Replogle, E. S.; Gomperts, R.; Martin, R. L.; Fox, D. J.; Binkley, J. S.; DeFrees, D. J.;
Supplementary Material (ESI) for Chemical Communications
This journal is © The Royal Society of Chemistry 2001
Baker, J.; Stewart, J. P.; Head-Gordon, M.; Gonzalez, C.; Pople, J. A. GAUSSIAN 94 (Revision B.2) (Gaussian, Inc.;
Pittsburgh PA, 1995).
2
(a) A. D. Becke, Phys. Rev., 1988, 38, 3098. (b) J. P. Perdew, Phys. Rev., 1986, 33, 8822.
3
6-31G* for C and H, ECP and (3s3p1d) basis sets of Bergner et al. (ref 4.) for In and Sn.
4
A. Bergner, M. Dolg,W. Kuechle, H Stoll, and H Preuss, H. Mol. Phys., 1993, 80, 1431.
5
(a) A. D. Becke, J. Chem. Phys., 1993, 98, 5648. (b) A. D. Becke, Phys. Rev. A, 1988, 38, 3098. (c) C. Lee, W. Yang,
and R. G. Parr, Phys. Rev. B, 1988, 37, 785. (d) S. H. Vosko, L. Wilk, and M. Nusair, Can. J. Phys., 1980, 58, 1200.