Theoretical studies organometallic compounds

Chemical Properties. Simple molecular-orbital theory predicts that many organometallic molecules should show electronic effects similar to conjugated systems, since the electronic structure is generally expressed in terms of molecular orbitals which involve both ring and metal orbitals. The ESR spectra (Sec. III.C) provide physical evidence for this formulation however correlation between chemical reactivities and theoretical quantities, such as charge densities and localization energies, which has been of use in aromatic systems (60) has not been attempted. Indeed, very few detailed kinetic studies of organometallic compounds have been reported with which to compare theory. We consider the different classes of compounds in turn. 

Formation of metal-organic compound co-condensates presents a peculiar problem, which is difficult to study. Most experimental methods are inapplicable to the study of the processes that take place at the instant of cocondensation. This brings to the fore theoretical approaches. The state of the art of computational quantum-chemical methods makes it possible to adequately describe the structure of organometallic compounds and estimate their stability and, sometimes, reactivity. 

In the following we review quantum chemical work about organic germanium, tin and lead compounds which has been published since 1990. The presentation of the results is organized as follows. First, we discuss in brief some relevant theoretical work about parent compounds of Ge to Pb. Then we summarize calculations of organometallic compounds. The latter section is divided into studies of neutral closed-shell molecules, charged species and radicals. E is used for any of the group-14 elements C to Pb. 

The previous sections discussed theoretical work of parent compounds of heavier group-14 elements which are homologues of important carbon reference compounds. In the next sections we will discuss in brief theoretical studies of organometallic molecules of germanium, tin and lead which were published since 1990. 

Most theoretical work on group-14 organometallic compounds was devoted to neutral closed-shell species. We divided the presentation of the papers into two parts. The first part focuses on theoretical studies of geometries and properties of molecules. The second part describes work where reaction mechanisms of chemical reactions of organometallic Ge-, Sn- and Pb-organic compounds have been investigated theoretically. 

State " Pb NMR. Besides pure inorganic compounds and theoretical studies wide variety of Pb NMR of organometallic derivatives with Pb—X(X = C, N, P) and Pb—O—bonds were described both in solution and in the solid state. 

Little information is available in the literature on higher lying excited states of Pd(2-thpy)2. Therefore, it is highly attractive to have a better resolved spectrum than the one shown in Fig. 2. This is of particular interest, since presently more detailed theoretical studies of organometallic Pd and Pt compounds become possible (compare Ref. [66]). The calculated results should be tested on a sufficiently accurate experimental basis. However, due to several reasons it is often very difficult to obtain well-resolved spectra of higher lying states. For example, homogeneous linewidths become broader due to short lifetimes of the states (see also below) and absorptions of different states and additionally of different... 

Stahl, M., Pidun, U., Frenking, G. Theoretical studies of organometallic compounds. XXVII. On the mechanism of the McMurry reaction. 

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