ISSN:
0009-2940
Keywords:
Phosphoranes, bis(methylene), isomerization of
;
λ3-Phosphiranes
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Bis(methylene)phosphoranes - Synthesis, Spectroscopic Investigations and Thermal Isomerizations to λ3-PhosphiranesA great number of differently substituted bis(methylene)phosphoranes 10 [R - P{ = C(SiMe3)2}2] are obtained by nucleophilic substitution from bis[bis(trimethylsilyl)methylene]-chlorophosphorane (8). The reactions of dichlorophosphanes 1 and methylenephosphanes 3 with lithium carbenoides 2 furnish the mixed derivatives 6 [R - P( = CR1R2)( = CR3R4)] and 7 [R - P( = C(SiMe3)2( = CR3R4)]. Among these the reaction of the sterically less hindered methylenephosphanes 3c, d [R2N - P = C(H)SiMe3, R = Et, iPr] with an excess of the lithium carbenoide 2b results in the formation of the σ4λ5-phosphiranes 11a, b {R2N - P[ = C(H)SiMe3]2}. The sterically highly demanding substituents in 10a - o render great thermal stability, while the mixed bis(methylene)phosphoranes 6, 7 rearrange to the corresponding σ4λ5-phosphiranes 15a-o. Investigations performed between 30 and 180°C reveal that all bis(methylene)phosphoranes, with the exception of 6c, k - m and 7e, can be isomerized. - The phosphino-substituted bis(methylene)phosphoranes 10k, 1 show different reactivity. Light-and thermally induced cleavage of the P - P bond, and dimerization of the corresponding fragments result in the formation of 14 and the diphosphanes 13a, b. The bis(methylene)phosphoranes 10a-o are investigated by UV and NMR spectroscopy.
Additional Material:
3 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19921250404
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