Metallunterstützte reversible Phosphanylphosphanierung der C‐N‐Dreifachbindung eines Nitrils

Ambident PCN Heterocycles: N‐ and P‐Phosphanylation of Lithium 1,3‐Benzazaphospholides

“…NMR spectra were recorded using Bruker ARX300 or Avance 300 NMR spectrometers at 300.1 ( 1 H), 75.5 ( 13 C), and 121.5 MHz ( 31 P) (Greifswald), or using an Avance400 spectrometer at 400.13 ( 1 H) and 121.9 MHz ( 31 P) (Stuttgart). Shift references are tetramethylsilane for 1 H and 13 13 C NMR spectroscopic data unless stated otherwise, and are given as absolute values. Assignments are supported by additional distortionless enhancement by polarization transfer (DEPT) measurements and further experiments described in the text.…”

“…The magnitude of the P,P coupling constants in 6 and 7 comes close to the value of 1 J P,P in tBu 2 P À PtBu 2 (À451 Hz [19] ), which is presumably a consequence of both steric bulk (as evidenced by the large C-P-C bond angles of 112.1(1)8 for [7·LiClA C H T U N G T R E N N U N G (thf)] 2 ) and a high degree of s character in the PÀP bond. [20] Conclusive information on the constitution in solution is also provided by the characteristic 13 C resonances and JA C H T U N G T R E N N U N G (P,C) coupling constants. Thus, N-and P-substituted benzazaphospholes are clearly distinguished by the chemical shifts of C3A, C7A, and C7.…”

“…The dihedral angles N1-C2-P3-P1 127.45(11)8 and P1-P3-C3A-C7A À113.12(10)8 correspond to the direction of the P3ÀP1 bond out of the azaphosphole plane, whereas the dihedral angles around the P-P axis show that one adamantyl group is arranged nearly eclipsed to C3A (C3A-P3-P1-C11 17.10(8)8) and the other nearly anti to C2 (C2-P3-P1-C21 163.78(7)8). (14), N(1)-Li-Cl 122.22 (14), N(1)-Li-Cl#1 120.17 (13), Cl#1-Li-Cl 98.36(11), Li#1-Cl-Li 81.64 (11); further data in Table 1.…”

Recent Developments in the Chemistry of N-Heterocyclic Phosphines

“…As this effect is intimately connected with the high stability of N -heterocyclic phosphenium cations, the reaction was considered as the first organocatalytic transformation that relies decisively on the electrophilic rather than the nucleophilic character of an organophosphorus catalyst. Alkenes and alkynes that are activated by one or more electron withdrawing substituents react with P-phosphino-NHPs with addition ("phosphinylphosphination") to the double or triple bond (Scheme 11 ), thus allowing access to unsymmetrical bis-phosphine ligands of potential metal chelating ability in one step from simple organic precursors [39,43,44,73,75] . Additions of alkynes occur more easily and have also been observed for other types of diphosphines whereas addition to alkenes seems to be restricted to substrates with highly reactive P-P bonds and is thus more or less specific for phosphino-NHPs.…”

“…A similar mechanism involving configurationally more stable vinylidene-carbanions was also proposed for phosphinylphosphination of alkynes [76] . An appealing facet of additions to triple bonds is further represented by the reaction between P-phosphino-NHPs, acetonitrile, and [W(CO) 4 (cyclooctadiene)] which proceeds via phosphino-phosphination of the nitrile triple bond and formation of chelate complex 20 (Scheme 12 ) [75] . It has been shown that both the activation of the nitrile by metal coordination and the ionic polarization and concomitant activation of the P-P bond are crucial for the formation of 20 [73] , and that the addition may be reversed during thermolysis which resulted in clean conversion of 20 into the phosphenium-phospholide complex 21 [75] .…”