Molecular main group compounds

The exceptions to the octet rule described in the previous section, the xenon compounds and the tri-iodide ion, are dealt with by the VSEPR and valence bond theories by assuming that the lowest energy available d orbitals participate in the bonding. This occurs for all main group compounds in which the central atom forms more than four formal covalent bonds, and is collectively known as hypervalence, resulting from the expansion of the valence shell This is referred to in later sections of the book, and the molecular orbital approach is compared with the valence bond theory to show that d orbital participation is unnecessary in some cases. It is essential to note that d orbital participation in bonding of the central atom is dependent upon the symmetry properties of individual compounds and the d orbitals. 

Much effort has been devoted to the connection between the heuristic chemical models and the quantum theory of molecular electronic structure in theoretical chemistry in recent years. It is important to understand why and where the models are valid descriptions of experimental results and why and where they fail. It is also possible to examine the validity of the explanations that are given to understand the reactivity, geometry, and other properties of molecules. This article deals with important chemical models and recent quantum chemical studies, which shed light on the electronic structure and bonding situation in main-group compounds. 

Bonding Energetics of OrganometaUic Compounds Electronic Structure of Main-group Compounds Electronic Structure of Solids Electronic Structure of Clusters Ligand Field Theory Spectra Molecular Orbital Theory Photoelectron Spectroscopy of Transition Metal Systems. 

Electronic Structure of Main-group Compounds Electronic Stmcture of Organometallic Compounds Magnetism of Extended Arrays in Inorganic Solids Molecular Orbital Theory Solids Computer Modeling Structure Property Maps for Inorganic Solids Superconductivity. 

Cluster Compounds Inorganometalhc Compounds Containing Transition Metal Main Group Elements Electronic Stmcture of Main-group Compounds Molecular Orbital Theory Phosphorus Inorganic Chemistry. 

This chapter comprises three sections. The first section briefly discusses the existing reviews of molecular mechanics computations of inorganic systems, the problems intrinsic in the application of molecular mechanics force fields to inorganic molecules and materials, and the current, state-of-the-art force fields. The remaining two sections review the recent literature concerning transition metal complexes and main group compounds. 

Soc., 114, 10024 (1992). UFF, a Full Periodic Table Force Field for Molecular Mechanics and Molecular Dynamics Simulations. C. J. Casewit, K. S. Colwell, and A. K. Rappe,/. Am. Chem. Soc., 114, 10035 (1992). Application of a Universal Force Field to Organic Molecules. C. J. Casewit, K. S. Colwell, and A. K. Rappe,/. Am. Chem. Soc., 114,10046 (1992). Application of a Universal Force Field to Main Group Compounds. 

Halland A (2008) Molecules and models - the molecular structures of main group compounds. Oxford University Press, Oxford, 298... 

In this work, we have reviewed the fundamental differences between the transitimi metal complexes and main group compounds. We have then exploited such differences to extend the classical Lewis descriptimi and formulate a revised picture to correlate electronic structure to molecular geometry for transition metal complexes. 

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