ic025920s_si_001.cif (21.59 kB)
Reactions of Tris(amino)phosphines with Arylsulfonyl Azides: Product Dependency on Tris(amino)phosphine Structure
dataset
posted on 2002-12-24, 00:00 authored by Natesan Thirupathi, Xiaodong Liu, John G. VerkadeThe Staudinger reaction of N(CH2CH2NR)3P [R = Me (1), iPr (2)] with 1 equiv of N3SO2C6H4Me-4 gave the ionic
phosphazides [R = Me (3), R = iPr (5a)], and the same reaction of 2 with
N3SO2C6H2Me3-2,4,6 gave the corresponding aryl sulfinite 5b. On the other hand, the reaction of 1 with 0.5 equiv
of N3SO2Ar (Ar = C6H4Me-4) furnished the novel ionic phosphazide {[N(CH2CH2NMe)3P]2(μ-N3)}[SO2Ar] (6). Data
that shed light on the mechanistic pathway leading to 3 were obtained by low temperature 31P NMR spectroscopy.
A crystal and molecular structure analysis of the phosphazide sulfonate (4),
obtained by atmospheric oxidation of 3, indicated an ionic structure, the cationic part of which is stabilized by a
transannular P−N bond. A crystal and molecular structure analysis of 6 also indicated an ionic structure in which
the cation features two untransannulated N(CH2CH2NMe)3P cages bridged by an azido group in an η1:μ:η1 fashion.
The reaction of P(NMe2)3 with N3SO2Ar (Ar = C6H4Me-4) in a 1:0.5 molar ratio furnished {[(Me2N)3P]2(μ-N3)}[SO2Ar] (11) in quantitative yield. On the other hand, the same reaction involving a 1:1 molar ratio of P(NMe2)3 and
N3SO2Ar produced a mixture of 11, [(Me2N)3PN3][SO2Ar] (12), and the iminophosphorane (Me2N)3PNSO2Ar (10).
In contrast, the bicyclic tris(amino)phosphines MeC(CH2NMe)3P (7) and OP(CH2NMe)3P (8) reacted with N3SO2Ar (Ar = C6H4Me-4) to give the iminophosphorane MeC(CH2NMe)3PNSO2Ar (14) (structured by X-ray means)
and OP(CH2NMe)3PNSO2Ar (16) via the intermediate phosphazides MeC(CH2NMe)3PN3SO2Ar (13) and OP(CH2NMe)3PN3SO2Ar (15), respectively. The variety of products obtained from the reactions of arylsulfonyl azides
with proazaphosphatranes (1 and 2), acyclic P(NMe2)3, bicyclic tris(amino)phosphines 7 and 8 are rationalized in
terms of steric and basicity variations among the phosphorus reagents.