Cyclotétra(λ³-phosphazanes) dérivant de diamines-1,2. Précurseurs de composés du phosphore dicoordonné

Abstract

Cyclotetraphosphazanes 2 and 5 obtained from 1,2-diamines are 1,3,2-diazaphosphole oligomers leading to the monomeric form by either thermal equilibrium or by complexing with boron trifluoride. The dicoordinated form stabilized by an orthophenylene ring could explain the reactivity of 4,5-benzo 1,3,2-diazaphosphole 3 with compounds having a mobile hydrogen; these reactions were a 1.2 type addition while butanol led to a 1.1 type addition with complexed 1,3,2-diazaphospholes 4 and 8.

Recent Developments in the Chemistry of N-Heterocyclic Phosphines

“…1 The fact that seemingly no other substrates apart from diaminomaleonitrile have been employed presumably reflects a lack of easily accessible starting materials. Benzannulated 1,3,2-diazaphospholes 5 form readily upon condensation of monosubstituted o -phenylenediamines (R = H, alkyl, Ph) with P(NMe 2 ) 3 [13,14] (Scheme 2 ). N -Alkylated products can be detected by NMR but evade isolation by 1 This is indeed corroborated by the use of similar condensation reactions for the synthesis of triazaphosphole derivatives; cf.…”

“…The upsurge in the chemistry of the five-membered ring compounds VIII was triggered by the discovery of stable carbenes ( VIII , E = C:) at the beginning of the 1990s, and the finding that these carbenes are powerful nucleophiles and valuable tools for many applications in coordination chemistry or catalysis [4][5][6] . This boom stimulated a quest for inorganic carbene analogues which are derived from the prototype by formal isoelectronic replacement of the divalent carbon atom by other elements of groups [13][14][15][16], and also increased the interest in cyclic phosphenium ions IIIc which had been discovered even before the carbenes [7] but received at first only moderate attention. Neutral N -heterocyclic phosphines (NHPs) IV entered the scene as synthetic precursors of cations IIIc and moved into focus as primary targets of further research when it was found that they exhibit likewise a quite unique bonding situation and appealing reactivity [8] .…”

A multinuclear NMR study of some cyclic phosphonic diamides

“…The ISN chemical shifts appear in the range typical for phosphonic amide [6], and the IJ(ISN_IH) couplings are typical in value for amino groups. The 31p chemical shifts for the compoWlds 1-3 are characteristic values for phosphonic amides [6][7] and the 31p chemical shift for compound 4 has a nonstandard value for a pentavalent phosphorus atom as found for phosphonic amides [3]. Consequently we may conclude that for the purposes of structural investigation of the compounds studied the 31p NMR data chemical shifts and IJ~lp_ISN) couplings are much more sensitive than the result produced by IH, I3C and ISN NMR.…”

“…Thus, the high frequency broad doublets were assigned to the NH groups, with the coupling constant 2Jrlp-IH) = 17-19 Hz. The doublet at 6.5 ppm in compound 4, with the big coupling constant IJ~lp_lH) = 579.4 Hz is assigned to the H atom of the PH group by comparison with literatw"e data [3]. The BC signals were assigned by analysis of the chemical shifts and BC_1H coupling constants obtained from the BC Nrv1R fully coupled spectra.…”

Sulfur derivatives of 3‐methyl‐5‐phenyl‐1,2,4,3‐triazaphosphole

“…By the oligomerization of endocylic P=N bonds of azaphospholes, only tetramers have been clearly identified so far [ 11. Structurally investigated were tetramers of triazaphospholes [11,12] …”