Abstract
The unusual shortness of the bond length in several main group and transition metal compounds is explained on the basis of their π-alone bonding. The detailed electronic structure calculation on C2, HBBH, and Fe2(CO)6 shows that each of them has two π-alone bonds (unsupported by an underlying σ-bond), whereas B2 has two-half π-bonds. The C–C bond length in C2 is 1.240 Å, shorter than any C–C double (σ + π, in C2H4, C–C=1.338 Å) bonded species. The B–B bond distance in B2 (1.590 Å, two half-π bonds) is shorter than any B–B single σ-bonded (~1.706 Å) species. The calculated Fe–Fe bond distance of 2.002 Å in Fe2(CO)6 is shorter than those of some experimentally known M–M single bonded compounds in the range of 2.904–3.228 Å. Here, our detailed studies on the second and third row diatomics (five, six, seven and eight valence electrons species) and transition metal complexes show that π-alone bonds left to themselves are shorter than σ-bonds; in many ways, σ-bonds prevent π-bonds from adopting their optimal shorter distances.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
G.J.H. Vannes, A. Vos, Single-crystal structures and electron density distributions of ethane, ethylene and acetylene. I. Single-crystal X-ray structure determinations of two modifications of ethane. Acta Cryst. B 34, 1947–1956 (1978)
G.J.H. Vannes, A. Vos, Single-crystal structures and electron density distributions of ethane, ethylene and acetylene. III. Single-crystal X-ray structure determination of ethylene at 85 K. Acta Cryst. B 35, 2593–2601 (1979)
R.K. Mcmullan et al., Structures of cubic and orthorhombic phases of acetylene by single-crystal neutron diffraction. Acta Cryst. B 48, 726–731 (1992)
F.A. Cotton et al., The crystal and molecular structure of dipotassium octachlorodirhenate(III) dihydrate, K2[Re2Cl8]2H2O. Inorg. Chem. 4, 330–333 (1965)
B.O. Roos et al., Reaching the maximum multiplicity of the covalent chemical bond. Angew. Chem. Int. Ed. 46, 1469–1472 (2007)
G. Frenking, R. Tonner, Theoretical chemistry: The six-bond bound. Nature 446, 276–277 (2007)
T. Nguyen et al., Synthesis of a stable compound with fivefold bonding between two chromium(I) centers. Science 310, 844–847 (2005)
P.J. Bruna, Theoretical prediction of the potential curves for the lowest-lying states of the isovalent diatomics CN+, Si2, SiC, CP+, and SiN+ using the ab initio MRD-CI method. J. Chem. Phys. 72, 5437–5445 (1980)
J.M. Galbraith et al., π-Bonding in second and third row molecules: Testing the strength of linus’s blanket. Chem. Eur. J. 6, 2425–2434 (2000)
L. Pauling, The Nature of the Chemical Bond, 2nd edn. (Cornell University Press, Ithaca, NY, 1945)
P. Pyykkö et al., Triple-bond bovalent radii. Chem. Eur. J. 11, 3511–3520 (2005)
K. Raghavachari et al., A fifth-order perturbation comparison of electron correlation theories. Chem. Phys. Lett. 157, 479–483 (1989)
R.J. Bartlett et al., Non-iterative fifth-order triple and quadruple excitation energy corrections in correlated methods. Chem. Phys. Lett. 165, 513–522 (1990)
G.E. Scuseria, The open-shell restricted Hartree-Fock singles and doubles coupled-cluster method including triple excitations CCSD (T): Application to C +3 . Chem. Phys. Lett. 176, 27–35 (1991)
M. J. Frisch et al., Gaussian 03, Revision C.02, Gaussian, Inc. (Wallingford CT, 2004)
J.A. Pople et al., Quadratic configuration interaction. A general technique for determining electron correlation energies. J. Chem. Phys. 87, 5968–5975 (1987)
A.D. Becke, Density-functional thermochemistry. III. The role of exact exchange. J. Chem. Phys. 98, 5648–5652 (1993)
C. Lee, Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density. Phys. Rev. B 37, 785–789 (1988)
A.E. Reed et al., Intermolecular interactions from a natural bond orbital, donor-acceptor viewpoint. Chem. Rev. 88, 899–926 (1988)
P. Rademacher, Photoelectron spectra of cyclopropane and cyclopropene compounds. Chem. Rev. 103, 933–976 (2003)
J.G. Fox, G. Hertzberg, Analysis of a new band system of the C2 molecule. Phys. Rev. 52, 638–643 (1937)
R.S. Mulliken, Note on electronic states of diatomic carbon, and the carbon–carbon bond. Phys. Rev. 56, 778–781 (1939)
E.A. Ballik, D.A. Ramsay, Ground state of the C2 molecule. J. Chem. Phys. 31, 1128–1128 (1959)
K.P. Huber, G. Herzberg, Molecular Spectra and Molecular Structure . IV. Constants of Diatomic Molecules (Van Nostrand-Reinhold Co, New York, 1979)
L.B. Knight et al., Laser sputtering generation of B2 for ESR matrix isolation studies: Comparison with ab initio CI theoretical calculations. J. Am. Chem. Soc. 109, 3521–3525 (1987)
P.P. Power, π-Bonding and the lone pair effect in multiple bonds between heavier main group elements. Chem. Rev. 99, 3463–3504 (1999)
G.L. Gutsev et al., Structure and stability of the AlX and AlX– species. J. Chem. Phys. 110, 2928–2935 (1999)
M. Pelegrini et al., MRSDCI study of the two lower-lying doublet electronic states of the BeB, MgB, and CaB molecules. Int. J. Quantum Chem. 95, 205–212 (2003)
P.J. Bruna, F. Grein, Hyperfine coupling constants and electron-spin g-factors of B +2 , Al +2 , Ga +2 , BAl+, BGa+, and AlGa+: An ab initio study. J. Chem. Phys. 117, 2103–2111 (2002)
P.J. Bruna et al., Beryllium-beryllium bonding. 1. Energetics of protonation and hydrogenation of beryllium dimer and its ions. J. Phys. Chem. 96, 6269–6278 (1992)
L.G. Kaplan et al., Nondipole bound anions: Be −2 and Be −3 . J. Chem. Phys. 117, 3687–3693 (2002)
R. Middleton, J. Klein, Production of metastable negative ions in a cesium sputter source: Verification of the existence of N −2 and CO−. Phys. Rev. A 60, 3786–3799 (1999)
A. Moezzi et al., Enhanced thermal stability in organodiborane(4) compounds: Synthesis and structural characterization of MeO(Mes)BB(Mes)OMe, Mes2BB(Mes)OMe, Mes2BB(Mes)Ph, and Mes2BB(Mes)CH2SiMe3 (Mes = 2,4,6-Me3C6H2). Organometallics 11, 2383 (1992)
J. Kalcher, A.F. Sax, Ab initio investigation on the negative ion states of the X–Y (X = C, Si; Y = Be, Mg) diatomics. J. Mol. Struct.: THEOCHEM 498, 77–85 (2000)
S. Midda, A.K. Das, Spectroscopic constants and molecular properties of diatomic carbides. J. Mol. Spectroscopy 224, 1–6 (2004)
T.L. Windus, M.S. Gordon, π-Bond strengths of H2X:YH2: X = Ge, Sn; Y = C, Si, Ge, Sn. J. Am. Chem. Soc. 114, 9559–9568 (1992)
L.B. Knight et al., Laser vaporization generation of the SiB and SiAl radicals for matrix isolation electron spin resonance studies; comparison with theoretical calculations and assignment of their electronic ground states as X 4Σ. J. Chem. Phys. 98, 6749–6757 (1993)
D. Tzeli, A. Mavridis, First-principles investigation of the boron and aluminum carbides BC and ALC and their anions BC- and AlC-1. J. Phys. Chem. A 105, 1175–1184 (2001)
S.P. Karna, F. Grein, High-multiplicity states of BN and BN+ obtained by configuration-interaction studies. Chem. Phys. Lett. 144, 149–152 (1988)
B. Miguel et al., Theoretical study of low-lying electronic states of BP molecule. Chem. Phys. Lett. 381, 720–724 (2003)
Y. Xie et al., Binuclear homoleptic iron carbonyls: Incorporation of formal iron-iron single, double, triple, and quadruple bonds, Fe2(CO) x (x = 9, 8, 7, 6). J. Am. Chem. Soc. 122, 8746–8761 (2000)
R. Binachi et al., Experimental electron density analysis of MN2(CO)10: Metal–metal and metal-ligand bond characterization. Inorg. Chem. 39, 2360–2366 (2000)
R.D. Adams et al., Unusual structural and magnetic resonance properties of dicyclopentadienylhexacarbonyldichromium. J. Am. Chem. Soc. 96, 749–754 (1974)
R.D. Adams et al., Molecular structures and barriers to internal rotation in bis (eta. 5-cyclopentadienyl)hexacarbonylditungsten and its molybdenum analog. Inorg. Chem. 13, 1086–1090 (1974)
V. Pophristic, L. Goodman, Hyperconjugation not steric repulsion leads to the staggered structure of ethane. Nature 411, 565–568 (2001)
F.M. Bickelhaupt, E.J. Baerends, The case for steric repulsion causing the staggered conformation of ethane. Angew. Chem. Int. Edn. Engl. 42, 4183–4188 (2003)
F. Weinhold, Rebuttal to the Bickelhaupt-Baerends case for steric repulsion causing the staggered conformation of ethane. Angew. Chem. Int. Edn. Engl. 42, 4188–4194 (2003)
M.J. Chetcuti et al., Bis[benzylbis(dimethylamido)molybdenum] and -tungsten (M.tplbond.M) compounds and their reactions with carbon dioxide and 1,3-diaryltriazenes. A radical difference. J. Am. Chem. Soc. 104, 4684–4686 (1982)
M.H. Chisholm, J.F. Corning, J.C. Huffman, The molybdenum-molybdenum triple bond. 14. Preparation and characterization of mixed alkoxy-thiolate compounds of formula Mo2(OR)2(SAr)4. Inorg. Chem. 23, 754–757 (1984)
T.M. Gilbert et al., Synthesis and electronic properties of triply bonded hexakis(fluoroalkoxy)dimolybdenum complexes. Structure of Mo2[OCMe(CF3)2]6 and investigation of the nature of the frontier orbitals in triply bonded M2X6 compounds. Inorg. Chem. 31, 3438–3444 (1992)
M.H. Chisholm et al., The tungsten-tungsten triple bond. 5. Chlorine atom substitution reactions involving dichlorotetrakis(diethylamido)ditungsten. Preparation, properties, structures, and dynamical solution behavior of bis(trimethylsilylmethyl)-, dibromo- and diiodotetrakis(diethylamido)ditungsten. Inorg. Chem. 16, 320–328 (1977)
J.P. Kenny et al., Cobalt–cobalt multiple bonds in homoleptic carbonyls? Co2(CO) x (x = 5–8) structures, energetics, and vibrational spectra. Inorg. Chem. 40, 900–911 (2001)
R.F.W. Bader, Atoms in Molecules: A quantum Theory (Clarendon Press, Oxford, 1994)
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2009 Springer Science+Business Media B.V.
About this chapter
Cite this chapter
Pathak, B., Umayal, M., Jemmis, E.D. (2009). σ-Bond Prevents Short π-Bonds: A Detailed Theoretical Study on the Compounds of Main Group and Transition Metal Complexes. In: Leszczynski, J., Shukla, M. (eds) Practical Aspects of Computational Chemistry. Springer, Dordrecht. https://doi.org/10.1007/978-90-481-2687-3_7
Download citation
DOI: https://doi.org/10.1007/978-90-481-2687-3_7
Published:
Publisher Name: Springer, Dordrecht
Print ISBN: 978-90-481-2686-6
Online ISBN: 978-90-481-2687-3
eBook Packages: Chemistry and Materials ScienceChemistry and Material Science (R0)