Synthesis of new phosphorus ylides: Spectroscopic and X‐ray structural studies

Abstract

Stable phosphoranes, Ar 3 P = CHCOR (R = C

Oxygen- versus carbon-coordination of the alpha-stabilized phosphorus ylide Ph3P=C(H)R in palladacycles bearing secondary amines

“…The presence of two lines of different intensities can be explained by the presence of two isomers in these complexes. The 31 P{ 1 H} NMR spectrum of the 6b complex shows a sharp signal attributed to the PCH group at 18.4 ppm, shifted slightly upfield relative to the free ylides and is again in agreement with O-coordination [3,17,[20][21][22].…”

“…The m(CO) bands, which are sensitive to complexation, occur at 1,507 and 1,519 cm -1 in the parent ylides, as in the case of other resonance-stabilized ylides [17,18,20]. In general, coordination of the ylide through C causes an increase in m(CO), while for O-coordination, a lowering of m(CO) is expected.…”

“…The 1 H NMR spectra of the complexes 5a-6b show a doublet or broad signal attributed to the proton methine CH at 3.8-4.4 ppm in O-bound complexes [3,17,[20][21][22] and the C-bound complexes 4b 0 -6b 0 observed in 5.4-5.6 ppm. The 1 H NMR spectra of the complexes showed only one signal for the CH methine with a coupling constant 2 J (P-H) near to that of the free ylides and close to those observed in other O-bonded complexes, this coupling is usually smaller in C-linked ylides [4-9, 20, 23, 24].…”

1-(4-Chlorophenyl)-2-[tris(4-methylphenyl)-λ5-phosphanylidene]butane-1,3-dione

“…For a general background to organophosphorus compounds and a review of stabilized phosphonium ylides, see: Bachrach & Nitsche (1994). For other related literature on ylides, see: Wilson & Tebby (1972); Sabounchei et al (2010). For analogous structures, see: Bart (1969); Kalyanasundari et al (1994); Sabounchei et al (2007); Castañ eda et al (2001,2003).…”