19738-46-6Relevant academic research and scientific papers
Trimethylsilyl esters of phosphorus acids. III. Esters of difluoro- and bis(trifluoromethyl)phosphinous and -thiophosphinous acids
Cavell,Leary,Sanger,Tomlinson
, p. 1374 - 1380 (2008/10/08)
The esters R2PESi(CH3)3 (R = F, E = O; R = CF3, E = O, S) have been prepared using one or more of four synthetic routes (CF3)2PSSi(CH3)3 is the first known example of a PIII-S-Si bridged compound, but the analogous difluoro ester F2PSSi(CH3)3 appears to be thermally unstable at 25°. Attempted syntheses of the P(V) isomers R2P(E)Si(CH3)3 gave only the P(III) forms, indicating that these systems are susceptible to anti-Arbuzov rearrangements. The difference in the stability and polarity between the P-O-Si and P-S-Si bridge units was demonstrated by the reactions of the esters with HCl and (CH3)2NH. At least three different reactions of the esters with dimethylamine were observed: cleavage at the E-Si bond with or without concomitant subsequent reaction of (CH3)3SiN(CH3)2 with the ionic product R2PE- and, in the case of (CF3)2POSi(CH3)3, displacement of CF3H to yield CF3[N(CH3)2]POSi(CH3)3. The latter phosphine showed a temperature-dependent nmr spectrum consistent with conformational isomerism of the N(CH3)2 group.
Trimethylsilyl esters of phosphorus acids. II. Reactions of fluoro- and trifluoromethylphosphorus(V) oxides and sulfides with hexamethyldisiloxane and hexamethyldisilthiane and the synthesis of a novel phosphorane
Cavell,Leary,Tomlinson
, p. 2578 - 2583 (2008/10/08)
The reactions of the phosphoryl and thiophosphoryl compounds R2P(E)X (R = F, CF3; E = O, S; X = F, Cl, Br, CF3) with hexamethyldisiloxane and hexamethyldisilthiane ((Me3Si)2E′, E′ = O, S) have been investigated. The esters R2P-(E)E′SiMe3 or R2P(E′)ESiMe3 are generally formed, the yield obtained and ease of reaction being reduced when S replaces O in either starting reactant. Evidence indicates that the reactions proceed via intermediates having pentacoordinate phosphorus atoms, and one such phosphorane intermediate, (CF3)3P(OSiMe3)2, has been isolated and characterized. This new phosphorane, the first to be directly synthesized from a phosphine oxide, exhibits temperature-dependent 19F and 1H nmr spectral behavior which can be partially interpreted in terms of a fluxional trigonal-bipyramidal model. Nmr and new infrared data are also reported for (CF3)2P(O)Br.
