New orthopalladated complexes of phosphorus ylides: Crystal structure of [Pd{CH{P(C7H6)(p-tolyl)2}COCH3}Cl{P(p-tolyl)3}]

Synthesis and structure of mono- and di-nuclear complexes of ortho-palladated derived from phosphorus ylides

“…13 C-NMR spectra of these complexes show the upfield shift of the signals due to the ylidic carbon. Such an upfield shift has been observed in PdCl(h 3 e2-XC 3 H 4 ) (C 6 H 5 ) 3 PCHCOR (X ¼ H, CH 3 ; R ¼ CH 3 , C 6 H 5 ) [24] and our synthesized complexes [12,27]. The 13 C shifts of the CO group in the complexes are around 195 ppm, relative to 183 and 186 ppm noted for the same carbon in the parent ylides, indicating much lower shielding of the carbon of the CO group in these complexes [27].…”

“…The 1 H NMR spectra of complexes 5a and 5b show duplicates signals that must arise from the presence of both possible isomers (cis and trans, see Scheme 2) [23].These 1 H NMR spectra of 5a and 5b show broad signals for the methinic CH groups due to the coupling with ylidic phosphorus. The 1 H NMR spectra of 4a, 6a and 6b are consistent with doublet of doublets and that of 4b is triplet and for 3a and 3b are broad signals that must arise from the simultaneously coupling with two or three phosphorus centers [12,23]. Furthermore, the values of the 2 J PH coupling constants between the methin proton and the phosphorus atom of the ylide ligands in these complexes are lower than those of the free ylides, suggesting that sp 2 / sp 3 rehybridization of the ylide carbon occurs upon coordination to the palladium atom [24].…”

“…It should be worth noting that in CDCl 3 solution the coupling constant between the phosphorus atoms of the chelate bidentate phosphine ligands and ylidic phosphorus are observed in the 13 P{ 1 H} NMR spectra of compounds 3a, 3b, 4a and 4b, although this was not observed before [13]. The 31 P{ 1 H} NMR spectra of 5a and 5b are two singlets due to cis and trans isomers and those of 6a and 6b show two doublets around 12 and 29 ppm due to PPh 3 and ylidic phosphorus, respectively [12,23]. 13 C-NMR spectra of these complexes show the upfield shift of the signals due to the ylidic carbon.…”

Seven-membered Pd(II) complexes containing symmetric phosphorus ylides: Synthesis, characterization and high catalytic activity toward Suzuki cross-coupling reactions

“…In the 1 H NMR spectra, the signals due to the methinic protons for all the complexes are broad and centered at 5-6 ppm. The 1 H chemical shift values for the complexes appear to be shifted downfield with respect to the parent ylide, indicating also that the coordination of the ylides has occurred [40,41]. Selected NMR chemical shifts for compounds 1-9 are reported in Table 2.…”

A Robust, Moisture- and Air-Stable Phosphine Mono-Ylide Palladacycle Precatalyst: A Simple and Highly Efficient System for Mizoroki–Heck Reactions

“…It is well established that palladacycle complexes containing phosphine ligands that combine both good donor strength and π-accepting capacity have high catalytic activities in Heck cross-coupling reactions. [20][21][22] Over the past ten years, we have studied phosphorus ylides and their palladium complexes, [23][24][25][26][27][28] and we have used some of these complexes in carbon-carbon coupling reactions. [29][30] Here, we describe the use of precatalyst 1 to promote the Mizoroki-Heck coupling reaction of aryl bromides or chlorides with olefins (Scheme 1).…”