Abstract
Qualitative molecular orbital (MO) theory has for years been used to interpret trends in <H-A-H in molecules of type AH2. We show that such MO concepts apply equally well to more complex molecules and to solids. In particular, for the general molecule or molecular cluster B-A-B, where B may be a group of atoms, the qualitative MO model explains the observed decrease in <B-A-B with: (1) decreasing electronegativity of A, e.g., <Si-O-Si vs. <Si-S-Si, (2) increasing electronegativity of B, e.g., <Si-O-Si vs. <C-O-C, and (3) increasing R(A-B), e.g., as observed in calculations in which both R(Si-O) and <Si-O-Si are varied. It also explains why the value of <B-A-B′, with B′ more electronegative than B, is similar to that for <B′-A-B′ and why the variability of <B-A-B′ is reduced when A is protonated. All the concepts employed are well established in quantum chemistry but have not previously been applied to the interpretation of bridging bond angles in minerals.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Allen LC (1972) The Shape of Molecules Theor Chim Acta 24:117–131
Allred AL (1961) Electronegativity Values for Thermochemical Data. J Inorg and Nuclear Chem 17:215–221
Burdett JK (1980) Molecular Shapes: Theoretical Models of Inorganic Stereochemistry. Wiley-Interscience, New York
Dixon DA, Marynick DO (1977) Inversion Barriers of AsH3 and SeH +3 . J Am Chem Soc 99:6101–6103
Geisinger K, Gibbs GV (1981) SiSSi and SiOSi Bonds in Molecules and Solids: A Comparison. Phys Chem Minerals 7:204–210
Gibbs GV (1982) Molecules as Models for Bonding in Silicates. Am Minerals 67:421–450
Gimarc BM (1979) Molecular Structure and Bonding: The Qualitative Molecular Orbital Approach. Academic Press, New York
Newton MD (1981) Theoretical Probes of Bonding in the Disiloxy Group. In: Structure and Bonding in Crystals, Vol 1. eg. M. O'Keefe and A Navrotsky, Academic Press, New York
Newton MD, Gibbs GV (1980) Ab initio Calculated Geometries and Charge Distributions for H4SiO4 and H6Si2O7 Compared with Experimental Values for Silicates and Siloxanes. Phys Chem Minerals 6:221–246
Newton MD, Lathan WA, Hehre WJ, Pople JA (1970) Self-consistent Molecular Orbital Methods. V. Ab Initio Calculation of Equilibrium Geometries and Quadratic Force Constants. J Chem Phys 52:4064–4072
Riekel C, Schollhörn R (1975) Structure refinement of nonstoichiometric TiS2. Mat Res Bull 10:629–634
Stenkamp LZ, Davidson ER (1973) An ICSCF Investigation of Walsh's Rules. Theor Chim Acta 30:283–314
Tossell JA, Gibbs GV (1978) The Use of Molecular-Orbital Calculations on Model Systems for the Prediction of Bridging-Bond-Angle Variations in Siloxanes, Silicates, Silicon Nitrides and Silicon Sulfides. Acta Crystallogr A34:463–472
Walsh AD (1953) The Electronic Orbitals, Shapes and Spectra of Polyatomic Molecules. Part 1. AH2 Molecules. J Chem Soc 2260–2265 (and later pages in volume)
Wells AF (1975) Structural Inorganic Chemistry, Clarendon Press, Oxford
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Tossell, J.A. A qualitative MO model for bridging bond angle variations in minerals. Phys Chem Minerals 11, 81–84 (1984). https://doi.org/10.1007/BF00308009
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF00308009