Fundamentals of Structure and Bonding

Before considering how ligands bond to metals, it is useful to look at the types of orbitals involved in such bonds. Chapter 2 includes a brief review of atomic orbitals, followed by a discussion of the ways in which atomic orbitals can interact to form molecular orbitals. Aspects of computational chemistry are introduced and discussed in terms of their relevance to organometallic chemistry. In subsequent chapters, we will consider how molecular orbitals of a variety of ligands can interact with transition metal orbitals. In these cases, we will pay particular attention to how metal d orbitals are involved. 

The modem view of atoms holds that although atoms are composed of three types of subatomic particles—protons, neutrons, and electrons—the chemical behavior of atoms is governed by the behavior of the electrons. Furthermore, the electrons do not behave according to the traditional concept of particles, but rather exhibit the characteristics of waves. In a single atom these waves can be described by the Schrodinger wave equation  

3-C = Hamiltonian operator E = energy of the electron i = wave function 

The wave function ijr can be represented by a mathematical expression describing the wave characteristics of an electron in an atom. The Hamiltonian operator,. Hi is a set of mathematical instructions to be performed on if in such a way as to give a result that is a numerical value (the energy of the electron) multiplied by ijr. The details of the Hamiltonian operator need not concern us here elaborate discussions can be found in a variety of physical chemistry texts. The characteristics of the wave function ijr, however, are essential background for understanding the discussion of chemical bonding that will follow. 

if is a mathematical description of a region of space (an orbital) that can be occupied by up to two electrons. 

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Rhodium boryl complexes have been the subject of intense research effort, reflecting not only fundamental issues of structure and bonding but also their... 

Krebs, H., Fundamentals of Inorganic Crystal Chemistry, McGraw-Hill, 1968 (excellent discussion of structures and bonding). 

This discussion has been deliberately qualitative in order to avoid complicating the fundamental concepts of QTAIM with the mathematical equations necessary to describe it completely. Further details of the theory and its applications are detailed in the references. The point to be made here is that there is a way to reconnect the results of molecular orbital theory with the familiar concepts of structure and bonding that have served organic chemists well. The QTAIM approach is not yet available in computational packages readily accessible to organic chemists, however. 

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