Synthesis and Reactivity of New Functionalized Perfluoroalkylfluorophosphates

Allefeld N, Neumann B, Stammler H-G, Roeschenthaler G-V, Ignat'ev N, Hoge B. Synthesis and Reactivity of New Functionalized Perfluoroalkylfluorophosphates. Chemistry - A European Journal. 2014;20(25):7736-7745.A new efficient synthesis of functionalized perfluoroalkyl fluorophosphates by oxidative addition of Me2NCH2F to the electron-deficient phosphanes (C2F5)(n)PF3-n (n = 0-3) is reported. The initially formed zwitterionic, hexa-coordinated phosphates [(C2F5)(n)F5-nP(CH2NMe2-CH2NMe2)] are converted into the corresponding phosphonium salts [(Me3PCH2NMe2](+)[(C2F5)(n)F5-nP(CH2NMe2)](-) by treatment with PMe3. In addition [(C2F5)(3)F2P(CH2NMe2-CH2NMe2)] can undergo a 1,3-methyl shift from the internal to the terminal nitrogen-a structural characterization was achieved from the CF3 analogue. Reaction of [(C2F5)(3)F2P(CH2NMe-CH2NMe3)] and PMe3 gave rise to the formation of the zwitterionic phosphonium phosphate [(C2F5)(3)F2P(CH2NMe-CH2PMe3)], which was fully characterized by X-ray diffraction analysis. Moreover, an efficient one-pot synthesis of Cs+ [(C2F5)(3)F2P(CH2NMe2)](-) was pursued. This salt turned out to be a useful nucleophile in several alkylation reactions

Synthesis, Reactivity and Structural Properties of Trifluoromethylphosphoranides

Shyshkov OO, Kolomeitsev AA, Hoge B, et al. Synthesis, Reactivity and Structural Properties of Trifluoromethylphosphoranides. Chemistry . 2022.Phosphoranides are interesting hypervalent species which serve as model compounds for intermediates or transition states in nucleophilic substitution reactions at trivalent phosphorus substrates. Herein, we report on the syntheses and properties of stable trifluoromethylphosphoranide salts. [K(18-crown-6)][P(CF 3 ) 4 ], [K(18-crown-6)][P(CF 3 ) 3 F], and [NMe 4 ][P(CF 3 ) 2 F 2 ] were obtained by treatment of trivalent precursors with sources of CF 3 - or F - units. These [P(CF 3 ) 4-n F n ] - (n = 0-2) salts exhibit fluorinating (n = 1-2) or trifluoromethylating (n = 0) properties, which is disclosed by studying their reactivity towards selected electrophiles. The solid-state structures of [K(18-crown-6)][P(CF 3 ) 4 ] and [K(18-crown-6)][P(CF 3 ) 3 F] are ascertained by single crystal X-ray crystallography. The dynamics of these compounds are investigated by variable temperature NMR spectroscopy. © 2022 Wiley-VCH GmbH

NHC -> SiCl4 : An Ambivalent Carbene-Transfer Reagent

Boettcher T, Steinhauer S, Lewis-Alleyne LC, et al. NHC -> SiCl4 : An Ambivalent Carbene-Transfer Reagent. Chemistry - A European Journal. 2015;21(2):893-899.The addition of BCl3 to the carbene-transfer reagent NHC -> SiCl4 (NHC = 1,3-dimethylimidazolidin-2-ylidene) gave the tetra-and pentacoordinate trichlorosilicon(IV) cations [(NHC)SiCl3](+) and [(NHC)(2)SiCl3](+) with tetrachloroborate as counterion. This is in contrast to previous reactions, in which NHC -> SiCl4 served as a transfer reagent for the NHC ligand. The addition of BF3 center dot OEt2, on the other hand, gave NHC -> BF3 as the product of NHC transfer. In addition, the highly Lewis acidic bis(pentafluoroethyl) silane (C2F5)(2)SiCl2 was treated with NHC -> SiCl4. In acetonitrile, the cationic silicon(IV) complexes [(NHC)SiCl3](+) and [(NHC)(2)SiCl3](+) were detected with [(C2F5)SiCl3](-) s counterion. A similar result was already reported for the reaction of NHC -> SiCl4 with (C2F5)(2)SiH2, which gave [(NHC)(2)SiCl2H][(C2F5)SiCl3]. If the reaction medium was changed to dichloromethane, the products of carbene transfer, NHC -> Si(C2F5)2Cl(2) and NHC -> Si(C2F5)(2)ClH, respectively, were obtained instead. The formation of the latter species is a result of chloride/hydride metathesis. These compounds may serve as valuable precursors for electron-poor silylenes. Furthermore, the reactivity of NHC -> SiCl4 towards phosphines is discussed. The carbene complex NHC -> PCl3 shows similar reactivity to NHC -> SiCl4, and may even serve as a carbene-transfer reagent as well

Carbene complexes of phosphorus(V) fluorides substituted with perfluoroalkyl-groups synthesized by oxidative addition. Cleavage of the complexes reveals a new synthetic protocol for ionic liquids

Boettcher T, Steinhauer S, Allefeld N, et al. Carbene complexes of phosphorus(V) fluorides substituted with perfluoroalkyl-groups synthesized by oxidative addition. Cleavage of the complexes reveals a new synthetic protocol for ionic liquids. Dalton Transactions. 2014;43(7):2979-2987.The crystal structures of the previously reported 2,2-difluoro-1,3-dimethylimidazolidine and its acyclic analog were determined by in situ crystallization. Both liquid fluorinating agents have recently been introduced as potent precursors for the synthesis of p-block element carbene complexes. These fluorine compounds were compared with chloro-amidinium chlorides, which are already established carbene precursors. The chlorides were characterized as ion pairs and contrasted to the previous interpretation as charge-transfer complexes between carbene and dichlorine. Furthermore, the two precursors are used for the synthesis of a series of new carbene complexes of phosphorus( V) fluorides substituted with perfluoroalkyl-groups. These unusually stable hexacoordinate phosphorus( V) complexes were treated with anhydrous hydrogen fluoride to yield imidazolium phosphates. This procedure allows the synthesis of salts used as ionic liquids in high yield and high purity