Synthesis, Crystal Structures, and Solution Behavior of Organomagnesium Derivatives of Alkane-1,4-diide as Well as -1,5-diide

The organomagnesium complexes [(thf)2Mg­(μ-C5H10)]2 (1), [(thf)2Mg­(μ-C4H8)]∞ (2), and [(thf)2Mg­(μ-(C­(CH3)2C2H4C­(CH3)2)]2 (3) were prepared via direct synthesis
from magnesium turnings and appropriate dichloroalkanes in tetrahydrofuran
(THF). The aggregation degree in the solid state depends on the nature
of the alkanediide. The THF solution of 3 shows a temperature-dependent
equilibrium. The reactions of MgCl2(thf)1.5 with
1,4-dilithiobutane yield the lithium magnesiates [Li­(thf)4]2[Mg3(C4H8)4] (4) and [{(tmeda)­Li}2Mg­(C4H8)2] (5) depending on the applied stoichiometry.
The addition reaction of Ph2Mg­(diox) (1,4-dioxane = diox)
with 1,4-dilithiobutane leads to the formation of the heteroleptic
magnesiate [{(tmeda)­Li}2MgPh2(C4H8)] (6), which shows in THF solution a ligand
exchange (Schlenk-type) equilibrium with the homoleptic derivatives
[{(thf)2Li}2Mg­(C4H8)2] and [{(thf)2Li}2MgPh4].