While the formation and breaking of transition metal (TM)-carbon bonds plays a pivotal role in the catalysis of organic compounds, the reactivity of inorganometallic species, that is, those involving the transition metal (TM)-metalloid (E) bond, is of key importance in most conversions of metalloid derivatives catalyzed by TM complexes. This Review presents the background of inorganometallic catalysis and its development over the last 15 years. The results of mechanistic studies presented in the Review are related to the occurrence of TM-E and TM-H compounds as reactive intermediates in the catalytic transformations of selected metalloids (E = B, Si, Ge, Sn, As, Sb, or Te). The Review illustrates the significance of inorganometallics in catalysis of the following processes: addition of metalloid-hydrogen and metalloid-metalloid bonds to unsaturated compounds; activation and functionalization of C-H bonds and C-X bonds with hydrometalloids and bismetalloids; activation and functionalization of C-H bonds with vinylmetalloids, metalloid halides, and sulfonates; and dehydrocoupling of hydrometalloids. This first Review on inorganometallic catalysis sums up the developments in the catalytic methods for the synthesis of organometalloid compounds and their applications in advanced organic synthesis as a part of tandem reactions.

New efficient synthetic routes for preparation of molecular and macromolecular organosilicon compounds based on silicon-containing alkene metathesis and metathesis polymerization catalyzed by transition metals (W, Mo, Re and Ru), which initate the formation of metal carbenes (ill-defined first generation catalysts), or by metallacarbene complexes (second generation catalysts, most of which are well defined) are reviewed. The group of reactions involve self-metathesis and cross- metathesis of alkenes (ring closing metathesis (RCM) of dienes, tandem ring opening of cycloalkene - cross-metathesis of alkenes (ROM/CM), as well as alkyne and enyne metathesis, which lead to molecular unsaturated organosilicon products. On the other hand, ring opening metathesis polymerization (ROMP) of silaalkenes and acyclic diene metathesis (ADMET) polymerization of siladienes yield linear macromolecular unsaturated organosilicon compounds. Polymer degradation via crossmetathesis with silicon-containing alkenes is also discussed in this review. All these reactions of alkenyl substituted (except vinylsubstituted) silicon compounds proceed according to the generally accepted metallacarbene mechanism. Vinylderivatives of organosilicon compounds while being inert to self-metathesis and ADMET polymerization, in the presence of complexes containing M-H and M-Si bonds (or initiating their formation) undergo effective transformations leading, in most cases, to metathesis-type products according to a non-metallacarbene mechanism.

Vinylsubstituted boronates i.e. vinyldioxaborolane and vinyldioxaborinane react regioselectively with olefins in the presence of RuHCl(CO)(PCy₃)₂ with the formation of functionalized vinylboron derivatives. The reaction opens a new catalytic route for preparation of organoboranes.

The reversible insertion of the vinylsilane molecule into the Ru–Si bond occurs in two different ways to give E-1,2-bis(silyl)ethene and 1,1-bis(silyl)ethene which, in combination with the previous experiments by Wakatsuki et al., provides convincing evidence for a non-metallacarbene mechanism of silylalkene disproportionation.