Synthesis of cyclic bifunctional organomagnesium compounds. X-ray crystal structures of tetrameric organomagnesium clusters

Two Isomers with an Al4C8 Framework

“…[9,10] In contrast to the p-like bonding in 1 and 2, one of the C atoms forms a Mg À C single bond, with the second C atom involved in a m 2 -3c 2e bond to the magnesium centres. This bonding situation is illustrated in Scheme 2.…”

“…Two different arrangements for the four divalent organic groups bridging the Mg 4 tetrahedron, with correspondingly different symmetries. [10] In contrast to 2, only one of these potential structures is adopted in the solid state for each of the three Mg 4 examples. Their different geometric situations may be one reason for the differences in their behaviour.…”

Organomagnesium clusters: Structure, stability, and bonding in archetypal models

“…Related compounds such as dineopentylmagnesium, Np 2 Mg, have a MgeC bond distance of 2.12 Å determined in gas-phase by neutron diffraction [43], which is close to our optimized value of 2.11 Å for Mg(CH 3 ) 2 . This value is in the range of 2.12e2.18 Å found experimentally for MgeC single-bond distances [10,44]. Finally, there is no experimental data on the molecular structure of CH 3 MgCl [6].…”

“…One might expect that organomagnesium compounds, being less polar than organolithium compounds, have a lower tendency to form aggregates [10]. Yet, such organomagnesium oligomers do exist in solution.…”

Novel Organoborane Lewis Acids via Selective Boron-Tin Exchange Processes Steric Constraints to Electrophilic Initiation by the Boron Halide

“…infra). The other precursors, containing two trimethylstannyl groups, were individually prepared from the corresponding organyl dibromide or dichloride by preparing the organomagnesium intermediate from magnesium metal in THF in the presence of the organotin chloride reactant (Barbier procedure [9] ). Small to moderate amounts of the trimethylstannyl derivative (9) were formed as a side product (Eq.…”