Polydentate chalcogen bonding: anion trapping with a water-stable host compound carrying Se-CF functions.

Bidentate and tetradentate chalcogen bonding host systems with SeCF functions as σ-hole donors in close proximity at the alkyne functions of 1,8-diethynylanthracene and its -dimer were prepared in quantitative yield by tin-selenium exchange reactions of the corresponding trimethylstannyl precursors with ClSeCF. The bidentate system shows chalcogen bonding interactions with THF, but does not bind halide ions. The tetradentate system cooperatively chelates chloride, bromide and iodide ions with its four CC-SeCF units by rotating the four σ-holes towards the halide ion.

Oxidative Additions of C-F Bonds to the Silanide Anion [Si(C F ) ].

Compounds exhibiting main group elements in low oxidation states were found to mimic the reactivity of transition metal complexes. Like the latter, such main group species show a proclivity of changing their oxidation state as well as their coordination number by +2, therefore fulfilling the requirements for oxidative additions. Prominent examples of such main group compounds that undergo oxidative additions with organohalides R-X (R=alkyl, aryl, X=F, Cl, Br, I) are carbenes and their higher congeners.

Salts of Tris(pentafluoroethyl)silylchalcogenolates [Si(CF)E] with E = S, Se, and Te: Synthesis, Structure, and Reactivity.

Unlike silanolates [SiRO] (R = alkyl, aryl), which have been intensely studied, the heavier derivatives [SiRE] (E = S, Se, Te) have been much less examined. Among such species, virtually nothing is known about perfluoroalkyl-substituted silylchalcogenolates. In this contribution, a convenient synthesis of tris(pentafluoroethyl)silylchalcogenolate salts [{(EtN)P═N}PN(H)Bu][Si(CF)E] (E = S, Se, Te; Bu = -butyl) is presented.

Tris(pentafluoroethyl)silanol Derivatives and the Lewis Amphoteric Tris(pentafluoroethyl)silanolate Anion, [Si(C F ) O].

While alkyl-substituted siloxanes are widely known, virtually nothing is known about perfluoroalkyl siloxanes and their congener species, the silanols and silanolates. We recently reported on the tris(pentafluoroethyl)silanide ion, [Si(C F ) ] , which features Lewis amphoteric character deriving from the pentafluoroethyl substituents and their strong electron-withdrawing properties. Transferring this knowledge, we investigated the Lewis amphoteric behavior of the tris(pentafluoroethyl)silanolate, [Si(C F ) O] .

Evidence of the Lewis-Amphoteric Character of Tris(pentafluoroethyl)silanide, [Si(C F ) ].

According to a first view on the geometrical and electronic structure of the tris(pentafluoroethyl)silanide, this anion appears as a Lewis base. Quantum chemical calculations on perfluoroalkylated silanides show significantly lower HOMO and LUMO energy levels in comparison to their non-fluorinated counterparts, which implies reduced Lewis basicity and increased Lewis acidity of the [Si(C F ) ] ion. With these findings and a HOMO-LUMO gap of 4.

Synthesis and Characterization of Tetrakis(pentafluoroethyl)aluminate.

While perfluorinated aryl, aryloxy and alkoxy aluminum species are well-established as weakly coordinating anions (WCAs), corresponding perfluoroalkyl aluminum derivatives are virtually unknown. Reaction of Si(C F ) CH with Li[AlH ] afforded the tetrakis(pentafluoroethyl)aluminate, [Al(C F ) ] . Several salts of the [Al(C F ) ] ion were synthesized and characterized by NMR spectroscopic methods, mass spectrometry, X-ray diffraction studies and elemental analysis.