An unusual reaction of hexafluoroacetone with methylenediphosphines. Facile synthesis of carbodiphosphoranes

Interaction of Some Methylenediphosphanes with Hexafluoroacetone and Hexafluorothioacetone Dimer

“…The X-ray analysis of 15 showed the following molecular structure ( Figure 2). (2) 180.40 (16), N(1)ϪC (5) 147.81 (19), C(2)ϪC (3) 152.1(2); C(1)ϪP(1)ϪN(1) 122.84 (7), C(1)ϪP (1)ϪS (1) 108.73 (5), N(1)ϪP (1)ϪN (2) 101.47 (6), N(1)ϪP (1)ϪS (1) 98.12 (5), P(1)ϪC (1)ϪP (2) 139.52 (9), P(1)ϪS(1)ϪC(2) 101.81 (5) Unlike allenes [12] and heteroallenes, in which the angle between the two double bonds is about 180°, the PϭCϭP angle in carbodiphosphoranes lies in the range 117Ϫ150°, depending on the structure and packing effects. [13Ϫ17] The only exception is hexa(dimethylamino)carbodiphosphorane, which has a linear structure and D 3d symmetry.…”

“…The analogous salts have been obtained earlier for carbodiphosphoranes 5a and 5b, and showed the same spectroscopic data. [5] The chloride 17, however, differs from its oxygen derivative. After the addition of HCl to a solution of 15 in hexane compound 17 immediately precipitates from the reaction mixture as a colorless crystalline product that is insoluble in non-polar solvents.…”

“…It is well-known that the reaction of hexafluoroacetone (HFA) with phosphorus(III) derivatives can lead to the formation of 1,3,2-or 1,4,2-dioxaphospholanes. [1Ϫ4] Recently we found that the interaction of HFA with the methylenediphosphanes 1a and 1b proceeds in a different way to yield quantitatively the carbodiphosphoranes 5a and 5b, [5,6] but not the expected 1,3,2-dioxaphospholanes 2a and 2b (Scheme 1).…”

Bis[bis(dialkylamino)phosphanyl]methanes and Bis(trifluoromethyl)acrylonitrile — Reactions and Derivatives

“…Earlier we observed the analogous coupling for the same protons of carbodiphosphoranes 3a,b. [5] The presence of ylidic and trivalent phosphorus bridged by a methylene group makes compounds 10a,b interesting synthons for further investigations. We were interested in the reaction of 10a,b with hexafluoroacetone as it could answer the question as to whether the formation of carbodiphosphoranes described at the beginning of this paper is an exception or is more common.…”

An Unusual Oxidation of 1,5-Dimethyl-2,4-bis(dialkylamino)-1,5-diaza-2,4-diphosphinan-6-one with Hexafluoroacetone

“…[1Ϫ4] Recently, however, we showed that this is not the only possible pathway for this reaction and that the presence of a methylene group in an α-position to the phosphorus atom may direct the reaction in an unusual way. [5,6] For example, bis[bis(dialkylamino)phosphinyl]methanes 1a,b easily react with only two equivalents of HFA quantitatively, giving carbodiphosphoranes 2a,b (Scheme 1). Scheme 1 …”