Organometallic compounds group 18

The mass spectra of main group organometallic compounds have been discussed in many of the reviews listed in the Introduction, and here we only summarize some recent examples. 

Structures of Main Group Organometallic Compounds Containing Electron-Deficient... 

In this review, emphasis will be placed first on definitive proof of structure for compounds of main group organometallic compounds that contain the electron-deficient or multicentered bonds described. Evidence for the occurrence of these systems in both liquid an gaseous states also will be given. Finally, this structural information will be used to elucidate the bonding in the molecules. 

Main-group organometallic compounds are versatile tools in organic synthesis, but their structures are complicated by the involvement of the multicenter, two-electron bonds and ion-dipole interactions that are involved in aggregate formation (5). Electron deficiency or Lewis acidity of the metallic center and nucleophilicity or basicity of the substituents are important considerations in synthesis. The complexity of the structures and interactions is, however, the origin of much of the unique behavior of these organometallic compounds. 

Most main group organometallic compounds undergo nucleophilic reactions with carbonyl groups, whereas 1,4-conjugate addition to enones... 

A range of main group organometallic compounds such as Cd(GePh3)2, Ph3PbPbPh3 and Hg Ge(C6F5)3 2 have been shown to react with [Pd(PPh3)4] to form Pd compounds which contain Pd—M bonds.53,54... 

In this section, a short account will be given of the scope of the major references dealing with main group organometallic compounds, although no claim to completeness is made here. 

Thus, as distinct from conventional Grignard reagents, their cluster congeners exhibit catalytic properties. This phenomenon is of great interest for a main group organometallic compound. 

The stable fourth main group organometallic compounds all contain the metal in the oxidation state four. Since most of the relevant compounds contain only one metal atom per molecule the following basic types of compounds must be distinguished ... 

The majority of main group organometallic compounds for which SET mechanisms were postulated involves Grignard reagents [13,69-75] in their reactions with carbonyl compounds. Even the formation of these important laboratory reagents RMgHal (which does not fall within the scope of this article) is now believed to involve electron transfer mechanisms and radical formation at the surface of metallic Mg [76,77]. In contrast to Grignard compounds with their... 

---