Catalytic reactivity of the complexes [Pd{(Ph2P)2N( Bu)-P,P´}X2], X = Cl, Br, I, in the Suzuki-Miyaura C−C coupling reaction: Probing effects of the halogeno ligand X− and the ligand's Bu group

Effects of the halogenido ligands on the Kumada-coupling catalytic activity of [Ni{tBuN(PPh2)2-κ2P}X2], X = Cl, Br, I, complexes

“…Based on the comparison with similar [Ni{R′N(PPh 2 ) 2 -κ 2 P}X 2 ] complexes reported in the literature, 17–38 as well as with the corresponding [Pd(P,P)X 2 ] complexes, 14 the IR bands of [Ni(P,P)X 2 ], occurring at 1437, 1433 and 1437 cm −1 for X = Cl, Br and I, respectively, should be assigned to the ν (P–Ph) stretching modes, whereas the band occurring uniformly at 868 cm −1 is assigned to the ν (P–N–P) stretching mode. These data indicate nearly identical conformation of the P–N–P backbone of the ligand in all three complexes, as confirmed by X-ray crystallography analysis ( vide infra ).…”

“…These observations demonstrate that, in all complexes, the ligand is coordinated to nickel(II) via both Phosphorus atoms that are equivalent to each other, in agreement with recently reported data on the analogous [Pd(P,P)X 2 ] complexes. 14 In addition, the spectra monitored during the six-month storage of samples did not show any signicant change, which conrmed the longterm stability of all three complexes when exposed to air at room temperature. 13 C NMR spectra are affected by the presence of paramagnetic impurities formed in the presence of the air and moisture.…”

“… 3–8 In addition, a large number of [M{R′N(PPh 2 ) 2 -κ 2 P}X 2 ] complexes, M = Ni, Pd, Pt; X = Cl, Br, I (see Scheme 1 ), exhibiting small P–M–P bite angles, were recently reviewed. 2 Selected palladium( ii ) complexes bearing X = Cl, 9–14 Br, 14,15 I, 14,16 catalyze the Suzuki–Miyaura and Heck coupling reactions. Some structurally characterized Ni( ii ) analogous complexes bearing X = Cl, 17–28 Br, 18,29–37 I, 18,36,38 catalyze polymerization of norbornene 20,21 or oligomerization (X = Br, 32,34 I, 38 ) and polymerization (X = Br 29 ) of ethene.…”