Insertion of olefins into palladium(II)-acyl bonds. Mechanistic and structural studies

Insertion Reactions into Palladium–Carbon Bonds of Complexes Containing Terdentate Nitrogen Ligands; Experimental and Ab initio MO Studies

“…These values agree well with that D exchange in 1a in the presence of D 2 ϩ (CϪO ϭ 1.28 Å ; PdϪO ϭ 2.07 Å ) [76] and and the structure of complexes 1fϪ6f show the ability of ligands 1Ϫ6 to coordinate in a bidentate fashion. Furtherthose experimentally observed for [Pd{C 7 H 10 C(O)Me}-(PPh 3 ) 2 ]BF 4 [16] (CϪO ϭ 1.240(10) Å ; PdϪO ϭ 2.114(6) Å ) more, a mechanism by substitution of one of the distal nitrogen donor atoms by the substrate followed by rate-deand [Pd{C 10 H 12 C(O)Me}(bpy)]SO 3 CF 3 [22] (CϪO ϭ 1.249(6) Å ; PdϪO ϭ 2.026(3) Å ). In the calculations, the termining migratory insertion explains the following observations.…”

“…Studdium bonds. [3] [4] [5] [6] [7] We [8] [15] and others [16] [24] have extensively studied ies of the insertion reactions of CO into the methylϪpal-ladium bond of complexes Pd(Me)X(P-P) (X ϭ Cl, PPh 3 , CO and alkene insertion reactions in model complexes of the type Pd(R)X(L-L) {R ϭ Me, C(O)Me; X ϭ Cl, Br, I, MeCN; P-P ϭ bidentate phosphorus ligand) showed that the reactions were enhanced by flexible bidentate phos-SO 3 CF 3 , BF 4 , [3,5-(CF 3 ) 2 C 6 H 3 ) 4 B]; L-L ϭ P-P, P-N, N-N} mimicking the intimate steps of the catalytic cycle of poly-phorus ligands, which are able to coordinate with a large bite angle, thereby lowering the energy of the transition ketone formation. [25] From these studies it is clear that the mechanism of CO and alkene insertion reactions is highly state.…”

Enantioselective isotactic alternating copolymerization of styrene and 4‐methylstyrene with carbon monoxide catalyzed by a cationic bioxazoline pd(II) complex

“…Accordingly the styrene phenyl ring and the ligand isopropyl group are respectively above and below the coordination plane thus minimizing the steric repulsion. If this assumption is correct an R configuration may be anticipated for both the insertion product ' c, 6) and the asymmetric carbon atom of the polymer chain. We have also investigated the catalytic properties of complex l c which is similar to complexes 1 a and 1 b used by Brookhart for the 4-tert-butylstyrene/carbon monoxide copolymerization3).…”

Stepwise Successive Insertion of Carbon Monoxide and Allenes into Palladium−Carbon Bonds of Complexes Containing the Rigid Bidentate Nitrogen Ligand Bis(p-anisylimino)acenaphthene

“…44 The observed chemical shift difference of about 0.4 ppm for the two remaining alkene protons in the C 7 H 8 C(O)R fragment in the 1 H NMR, together with the high chemical shift of 229.2 ppm in the 13 C NMR and the low CO stretching frequency of 1601 cm -1 in the IR for the CO in the C 7 H 8 C(O)R fragment indicate that the oxygen atom of this CO is coordinated to the palladium resulting in a fivemembered palladacycle. 17,19,44,45 The observed high equivalent conductivity of 19.0 Ω -1 cm 2 mol -1 in dichloromethane at 20°C is also in agreement with a structure, in which the chloride is dissociated. [Pd- (C 7 H 8 C(O)C 5 H 8 C(O)Me)(p-An-BIAN)]SO 3 CF 3 (13b), obtained by reacting 13a with 1 equiv of AgSO 3 CF 3 , is in contrast to 13a stable enough to obtain correct analytical data.…”