Preparation of Telluro- and Selenoalumoxanes under Mild Conditions

Synthesis of unsymmetrical B2E2 and B2E3 heterocycles by borylene insertion into boradichalcogeniranes

We report the selective insertion of a range of borylene fragments into the E-E bonds (E = S, Se, Te) of cyclic boron dichalcogenides. This method provides facile synthetic access to a variety of symmetrical and unsymmetrical four- and five-membered rings.

Single Electron Delivery to Lewis Pairs: An Avenue to Anions by Small Molecule Activation

Single electron transfer (SET) reactions are effected by the combination of a Lewis acid (e.g., E(C₆F₅)₃ E = B or Al) with a small molecule substrate and decamethylferrocene (Cp*₂Fe). Initially, the corresponding reactions of (PhS)₂ and (PhTe)₂ were shown to give the species [Cp*₂Fe][PhSB(C₆F₅)₃] 1 and [Cp*₂Fe][(μ-PhS)(Al(C₆F₅)₃)₂] 2 and [Cp*₂Fe][(μ-PhTe)(Al(C₆F₅)₃)₂] 3, respectively. Analogous reactions with di-tert-butyl peroxide yielded [Cp*₂Fe][(μ-HO)(B(C₆F₅)₃)₂] 4 with isobutene while with benzoyl peroxide afforded [Cp*₂Fe][PhC(O)OE(C₆F₅)₃] (E = B 5, Al 6). Evidence for a radical pathway was provided by the reaction of Ph₃SnH and p-quinone afforded [Cp*₂Fe][HB(C₆F₅)₃] 7 and [Cp*₂Fe]₂[(μ-O₂C₆H₄)(E(C₆F₅)₃)₂] (E = B 8, Al 9). In addition, the reaction of TEMPO with Lewis acid and Cp*₂Fe afforded [Cp*₂Fe][(C₅H₆Me₄NOE(C₆F₅)₃] (E = B 10, Al 11). Finally, reactions with O₂, Se, Te and S₈ gave [Cp*₂Fe]₂[((C₆F₅)₂Al(μ-O)Al(C₆F₅)₃)₂]₂ 12, [Cp*₂Fe]₂[((C₆F₅)₂Al(μ-Se)Al(C₆F₅)₃)₂]₂ 13, [Cp*₂Fe][(μ-Te)₂(Al(C₆F₅)₂)₃] 14 and [Cp*₂Fe]₂[(μ-S₇)B(C₆F₅)₃)₂] 15, respectively. The mechanisms of these SET reactions are discussed, and the ramifications are considered.

Advances in the development of complexes that contain a group 13 element chalcogen multiple bond

The advances in the synthesis and isolation of complexes that contain a group 13 element chalcogen multiple bond are accounted for.

A monotopic aluminum telluride with an Al=Te double bond stabilized by N-heterocyclic carbenes

Aluminum chalcogenides are mostly encountered in the form of bulk aluminum oxides that are structurally diverse but typically consist of networks with high lattice energy in which the chalcogen atoms bridge the metal centres. This makes their molecular congeners difficult to synthesize because of a pronounced tendency for oligomerization. Here we describe the isolation of the monotopic aluminum chalcogenide (L(Dip)N)AlTe(L(Et))2 (L(Dip)=1,3-(2,6-diisopropylphenyl)-imidazolin-2-imine, L(Et)=1,3-diethyl-4,5-dimethyl-imidazolin-2-ylidene). Unique features of (L(Dip)N)AlTe(L(Et))2 are the terminal position of the tellurium atom, the shortest aluminum-tellurium distance hitherto reported for a molecular complex and the highest bond order reported for an interaction between these elements, to the best of our knowledge. At elevated temperature (L(Dip)N)AlTe(L(Et))2 equilibrates with dimeric {(L(Dip)N)AlTe(L(Et))}2 in which the chalcogen atoms assume their common role as bridges between the metal centres. These findings demonstrate that (L(Dip)N)AlTe(L(Et))2 comprises the elusive Al=Te double bond in the form of an N-heterocyclic carbene-stabilized species.