Antimony contamination and its risk management in complex environmental settings: A review

Oxidative addition of Cp*SbX2 (X=Cl, Br, I; Cp*=C5 Me5 ) to group 13 diyls LM (M=Al, Ga, In; L=HC[C(Me)N (Dip)]2 , Dip=2,6-iPr2 C6 H3 ) yields elemental antimony (M=Al) or the corresponding stibanylgallanes [L(X)Ga]Sb(X)Cp* (X=Br 1, I 2) and -indanes [L(X)In]Sb(X)Cp* (X=Cl 5, Br 6, I 7). 1 and 2 react with a second equivalent of LGa to eliminate decamethyl-1,1'-dihydrofulvalene (Cp*2 ) and form stibanyl radicals [L(X)Ga]2 Sb. (X=Br 3, I 4), whereas analogous reactions of 5 and 6 with LIn selectively yield stibanes [L(X)In]2 SbH (X=Cl 8, Br 9) by elimination of 1,2,3,4-tetramethylfulvene. The reactions are proposed to proceed via formation of [L(X)M]2 SbCp* as reaction intermediate, which is supported by the isolation of [L(Cl)Ga]2 SbCp (11, Cp=C5 H5 ). The reaction mechanism was further studied by computational calculations using two different models. The energy values for the Ga- and the In-substituted model systems showing methyl groups instead of the very bulky Dip units are very similar, and in both cases the same products are expected. Homolytic Sb-C bond cleavage yields van der Waals complexes from the as-formed radicals ([L(Cl)M]2 Sb. and Cp*. ), which can be stabilized by hydrogen atom abstraction to give the corresponding hydrides, whereas the direct formation of Sb hydrides starting from [L(Cl)M]2 SbCp* via concerted β-H elimination is unlikely. The consideration of the bulky Dip units reveals that the amount of the steric overload in the intermediate I determines the product formation (radical vs. hydride).

https://chemistry-europe.onlinelibrary.wiley.com/doi/pdf/10.1002/chem.202001739

A Mechanistic Study on Reactions of Group 13 Diyls LM with Cp*SbX2 : From Stibanyl Radicals to Antimony Hydrides.

Reversing Lewis acidity from bismuth to antimony

A Stiboranyl Platinum Triflate Complex as an Electrophilic Catalyst

The pentamethylcyclopentadienyl (Cp*) antimony(III) cations [Cp*2Sb][B(C6F5)4], [Cp2*Sb][OTf], [Cp*SbCl][B(C6F5)4] and [Cp*Sb][OTf]2 have been isolated and structurally characterised. [Cp*SbCl]+ forms dimers in the solid state via an intermolecular Sb–Cl interaction. Initial screening shows that [Cp*SbCl][B(C6F5)4] is significantly Lewis acidic and can catalyse the dimerisation of 1,1-diphenylethylene; [Cp2*Sb][B(C6F5)4] exhibits negligible Lewis acidity. Highly unstable [Cp*SbF][B(C6F5)4] could not be isolated, but stabilisation with the IMes ligand allowed isolation of [Cp*SbF(IMes)][B(C6F5)4]. Fluorodechlorination of CH2Cl2 and PhCCl3 was observed in the presence of crude [Cp*SbF][B(C6F5)4] in solution. A computational mechanistic investigation suggests that the latter proceeds via a carbocation intermediate.

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Diverse structure and reactivity of pentamethylcyclopentadienyl antimony(iii) cations.

Arsenic, Antimony and Bismuth

The title compound, diethyl (6-methyl-2-pyridyl)aminoethylenemalonate (1), crystallises in the monoclinic space group P21/c (No. 14). The unit cell parameters are a = 10.5657(7) A, b = 9.1784(5) A, c = 14.5681(7) A, β = 101.636(6)°, Z′ = 1 and Z = 4 at 150 K. The extended structure forms approximately orthogonal columns of stacked molecules. All bond lengths and angles are unremarkable. No disorder, twinning or co-crystallised solvent is present in the structure. An intramolecular hydrogen bond exists between the enamine nitrogen and carbonyl oxygen. Hirshfeld surface analysis reveals a short contact between a carbonyl oxygen and neighbouring aryl hydrogen, as well as a carbonyl–carbonyl interaction. The X-ray structure of diethyl (6-methyl-2-pyridyl)aminoethylenemalonate (1), an intermediate in the synthesis of ethyl nalidixate, is reported, and Hirshfeld surface analysis employed to identify intermolecular interactions within the structure.

/pdf/crystal-structure-and-hirshfeld-surface-analysis-of-diethyl-3tf6xll7by.pdf

Omar Coughlin

Papers

Diverse structure and reactivity of pentamethylcyclopentadienyl antimony(iii) cations.

Arsenic, Antimony and Bismuth

Crystal Structure and Hirshfeld Surface Analysis of Diethyl (6-methyl-2-pyridyl)aminoethylenemalonate