**Author details**

and solvent). Presumably, the key factor determining the dependence of enantioselectivity

bimetallic Zr, Al‐intermediates, which control the reaction pathways. The effect of a solvent nature on the rate of intramolecular exchange between conformers of neomenthyl‐substituted zirconocenes **32a**, **35** and **36**, which are formed as a result of the rotation of the indenyl frag‐

(DNMR) spectroscopy [68]. Comparison of the conformer composition and dynamics of the complexes with their activity and stereoselectivity in the reactions of OACs with alkenes led to the conclusion that the enantioselectivity of the reactions is determined by the kinetic factor, namely, by the rate of interaction in a pair: conformer of catalytically active center‐substrate. Thus, in order to achieve high enantioselectivity in the studied reactions, the catalyst molecule should have a specific conformational mobility for the formation of a suitable rotamer, which

In this connection, further optimization of the ligand environment, namely the search for appro‐ priate conformers that could be formed via either introduction of suitable substituents into the indenyl ligand or upon binding of ligands could advance these studies toward the design of more efficient catalysts for alkene functionalization by organomagnesium and ‐aluminum reagents.

Thus, the catalytic alkene hydro‐, carbo‐ and cycloalumination are complex multi‐step pro‐ cesses, in which a large number of intermediate bimetallic Zr, Al‐complexes are involved. Studies of the reaction mechanisms allow to understand the chemistry of the processes on a

Finally, the next remarks should be sound. First, the initial OACs exist as self‐associated struc‐ tures in the solutions, where the exchange between hydride atoms or alkyl groups could run via dissociation on monomers, which represents the Lewis acids and which effective concen‐ tration influences on the stages of key intermediates formation. Second, since the catalyst (IV group transition metals) is a Lewis acid too due to a free nonbonding orbital, then it disturbs the above balance, making the system more dynamic. Thus, one of the important roles of the catalyst besides the formation of active species is to accelerate the exchange through the disso‐ ciation with the release of the active OAC monomer. Third, the interaction of alkyl or hydride complex with the monomer gives active species—bimetallic intermediates, which reactivity depends on the availability of the free nonbonding orbital (**Scheme 9**). The active species should be coordinatively unsaturated, where at least one of the bridge bond is broken. In the case of bimetallic hydride complexes, there is the tendency to form inactive bridge bonds, whereas bimetallic alkyl substituted intermediates are inclined to the dissociation. Therefore, the activity of intermediates depends on the living time of active species, in which the electro‐

of alkene introduction. However, there is a danger of another process—C─H activation in the products, which could be prevented by using more bulky ligands or more polar solvents.

‐ligand, thereby accelerating the process

], has been shown by the means of dynamic nuclear magnetic resonance

*‐*ligands in

on the solvent nature and OAC structure is the conformational behavior of the η<sup>5</sup>

ments relative to [ZrCl<sup>2</sup>

56 Alkenes

**4. Conclusions**

lifetime will be sufficient for the alkene insertion.

deeper level and to narrow the search for new catalytic systems.

philicity of the metal center could be increased via η<sup>5</sup>

Lyudmila V. Parfenova\*, Pavel V. Kovyazin, Tatyana V. Tyumkina, Leonard M. Khalilov and Usein M. Dzhemilev

\*Address all correspondence to: luda\_parfenova@mail.ru

Institute of Petrochemistry and Catalysis, Russian Academy of Sciences, Ufa, Russian Federation
