Simple RZnOR’ alkoxides are among the first known organozinc compounds, and widespread interest in their multifaced chemistry has been driven by their fundamental significance and potential applications including various catalytic reactions. Nevertheless, their chemistry in solution and in the solid state remains both relatively poorly understood and a subject of constant debate. Herein, the synthesis and structural characterization of long‐sought structural forms, a roof‐like trimer [(tBuZn)3(μ‐OC(H)Ph2)2(μ3‐OC(H)Ph2)] and a ladder‐type tetramer [(PhZn)4(μ‐OC(H)Ph2)2(μ3‐OC(H)Ph2)2], incorporating diphenylmethanolate as a model alkoxide ligand, are reported. Both novel aggregates are robust in the solid state and resistant towards mechanical force. By using 1H NMR and diffusion‐order spectroscopy, it is demonstrated that new RZnOR’ alkoxides are kinetically labile in solution and readily undergo ligand scrambling, such as in the case of Schlenk equilibrium. The elucidated key structural issues, which have remained undiscovered for decades, significantly advance the chemistry of RZnOR’ alkoxides and should support the rational design of zinc alkoxide‐based applications.
While aluminum alkyls are often considered
to be exemplary compounds of main-group organometallics and an in-depth
understanding of their multifaceted chemistry is continually vital,
the controlled oxygenation of organoaluminum complexes still remains
a largely undeveloped area. In the course of our systematic studies
on the relationship between the Lewis acidity of metal centers and
noncovalent interactions in the secondary coordination sphere, we
report the oxygenation of dialkylaluminum complexes incorporating
a pyrrole–ester ligand, as purposefully selected dormant Lewis
acidic octet-compliant model compounds, and the isolation and characterization
of a new, dimeric aluminum
tert
-butylperoxide and
an unique example of an aluminum oxoethoxide cluster. Our studies
provide a more in-depth look at the diversity and complexity of the
oxygenation chemistry of aluminum alkyls.
The distinct research
areas related to CO
2
capture and
mechanochemistry are both highly attractive in the context of green
chemistry. However, merger of these two areas,
i.e.
, mechanochemical CO
2
capture, is still in an early stage
of development. Here, the application of biguanidine as an active
species for CO
2
capture is investigated using both solution-based
and liquid-assisted mechanochemical approaches, which lead to a variety
of biguanidinium carbonate and bicarbonate hydrogen-bonded networks.
We demonstrate that in solution, the formation of the carbonate vs
bicarbonate networks can be directed by the organic solvent, while,
remarkably, in the liquid-assisted mechanochemical synthesis employing
the same solvents as additives, the selectivity in network formation
is inversed. In general, our findings support the view of mechanochemistry
not only as a sustainable alternative but rather as a complementary
strategy to solution-based synthesis.
Studies on the reactivity of zinc alkyl compounds towards SO2 are relatively less explored than either the oxygenation or hydrolysis reactions. We report on environmentally friendly and efficient syntheses of...
β-Hydroxy sulfones are important in organic synthesis. The simplest method of β-hydroxy sulfones synthesis is the hydrogenation of β-keto sulfones. Herein, we report the reducing properties of alkyl aluminum compounds R3Al (R = Et, i-Bu, n-Bu, t-Bu and n-Hex); i-Bu2AlH; Et2AlCl and EtAlCl2 in the hydrogenation of β-keto sulfones. The compounds i-Bu2AlH, i-Bu3Al and Et3Al are the at best reducing agents of β-keto sulfones to β-hydroxy sulfones. In reactions of β-keto sulfones with aluminum trialkyls, hydroalumination products with β-hydroxy sulfone ligands [R2AlOC(C6H5)CH2S(O)2(p-R1C6H4]n [where n = 1,2; 2aa: R = i-Bu, R1 = CH3; 2ab: R = i-Bu, R1 = Cl; 2ba: R = Et, R1 = CH3; 2bb: R = Et, R1 = Cl] and {[Et2AlOC(C6H5)CH2S(O)2(p-ClC6H4]∙Et3Al}n3bb were obtained. These complexes in the solid state have a dimeric structure, while in solutions, they appear as equilibrium monomer–dimer mixtures. The hydrolysis of both the isolated 2aa, 2ab, 2ba, 2bb and 3bb and the postreaction mixtures quantitatively leads to pure racemic β-hydroxy sulfones. Hydroalumination reaction of β-keto sulfones with alkyl aluminum compounds and subsequent hydrolysis of the complexes is a simple and very efficient method of β-hydroxy sulfones synthesis.
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