A catalyst don’t appear in the overall stoichiometry of the reaction it catalyzes, but it must appear in at least one of the elementary reactions in the mechanism for the catalyzed reaction. 791-28-6, Name is Triphenylphosphine oxide, molecular formula is C18H15OP. In an article, author is Perez-Iglesias, Maria,once mentioned of 791-28-6, COA of Formula: C18H15OP.
Intriguing Behavior of an Apparently Simple Coupling Promoter Ligand, PPh2(p-C6H4-C6F5), in Their Pd Complexes
Ligand PPh2(p-C6H4-C6F5), L-HF, is an example of monodentate biphenyl phosphine that allows for cis coordination of two phosphines to Pd, as in complex cis-[PdPf(2)Pd(L-HF)(2)] (A) (Pf = C6F5). At 25 degrees C, complex A undergoes easy reductive elimination to decafluorobiphenyl and, competitively, isomerizes to trans-[Pd(C6F5)(2)Pd-(L-HF)(2)] via functionally three-coordinate intermediates cis-[PdPf(2)(L-HF)-(S)] with the fourth position empty or weakly protected (S=THF, OH2, or pi-aryl). Unexpectedly, the direct reductive C6F5-C6F5 elimination is faster from the four-coordinate complex A than from the intermediates with only one strong L-HF. The reason for this is that two cis L-HF ligands play the role of a chelate with a large bite angle and some tetrahedral distortion. As a matter of fact, using L-HF in excess (Pd:L << 1:2), a Pf-Pf coupling barrier Delta G(Pf-Pf)(double dagger) = 23.1 kcal. mol(-1) is measured, which ranks its efficiency for coupling and formation of the corresponding Pd-0 catalyst as better than XantPhos or PhPEWO-F and about the same as (t)BuBrettPhos. On the other hand, complex (mu-Cl)(2)[Pd(2)Rf(2)(L-HF)(2)] (B) (Rf = C6F3Cl2 = 3,5-dichloro-2,4,6-trifluorophenyl), obtained by reaction of (mu-Cl)(2)[Pd(2)Rf(2)(tht)(2)] (tht = tetrahydrothiophene) with L-HF, presents in the F-19 NMR COSY spectrum a very intriguing through-space coupling pattern of the F-ortho atoms of the C6F5 group in L-HF and the 3-5-C6F3Cl2 group on Pd. The intermittent coupling mechanism proposed is based on the switching of pi-pi-stacking of C6F5 from one Ph group to another Ph group of L-HF, which gives rise to enantiomers at the chiral P atom. Rotation around the P-biphenyl bond under hindered rotation around the C-C6F5 bond produces the intriguing selective coupling observed. Interested yet? Keep reading other articles of 791-28-6, you can contact me at any time and look forward to more communication. COA of Formula: C18H15OP.
Reference:
Phosphine ligand,
,Chiral phosphine ligands in asymmetric synthesis. Molecular structure and absolute configuration of (1,5-cyclooctadiene)-(2S,3S)-2,3-bis(diphenylphosphino)butanerhodium(I) perchlorate tetrahydrofuran solvate