Cationic benzyl nickel complexes as homogeneous catalysts for styrene oligomerization. X-ray crystal structure of [Ni(η3-CH2C6H5)(PPh3)2]PF6 · CH2CI2

An effective route for the synthesis of cationic palladium complexes of general formula [(Acac)PdL1L2]+A−

“…The 1 H and 13 C NMR spectra of the dimer products are identical to those described in Ref. [10], indicating 1,3-diphenyl-1-butene is the main product. …”

Pd-Salen and Pd-Salan complexes: Characterization and application in styrene polymerization

“…In addition, the TGA data further indicate that these polystyrenes could be stable up to 370°C. In fact, similar to the polymerization behaviors from the reported late transition metal catalysts [8, [10][11][12], the resulting polystyrenes catalyzed by the two Pd (II) complexes are essentially atactic, despite the possibly different polymerization mechanisms between the catalytic systems. Further comparing our results with the data in the literature for the polymerization of styrene mediated by the Ni 2+ β-ketoamine [25] or N-O-chelate catalysts/MAO [26], it can be seen that the lower catalytic activities while narrower molecular weight distributions are observed, which should be due to the perfectly square planar geometry of the active species in catalysts 1-2, especially in the present of AIBN co-catalyst, while there are important differences in the polymerization products.…”

“…Nevertheless, late transition metal catalysts are less oxophilic, not as sensitive as early transition metal catalysts to function groups, and thus applicable to efficiently catalyze the homo- [8] or copolymerization [9] of styrene; especially, some interesting performances have been noted for late transition metal catalysts systems by different polymerization mechanisms, giving the isotactic-enriched oligo-and polystyrenes. For example, the first styrene oligomerization to isotactic-enriched (up to mm = 90%) oligomers was reported with the cationic η 3 -benzylic Ni 2+ complexes associated with phosphorus ligands, in which, the stereoregulation was proposed by the cationic mechanism [10]. Neutral anilido-imino Ni 2+ complexes/MAO could produce non-stereospecific polystyrene, and a possible coordinationinsertion mechanism was proposed [11].…”

Novel palladium acetate based protocols for transformations of unsaturated hydrocarbons

“…Molar mass of m/z=208 of the dimer product was confirmed by mass spectroscopy. The 1 H and 13 C NMR spectra of the dimeric products are the same as that described in [4,10], indicating 1,3-diphenyl-1-butene to be the main product. Table 1 shows the dimerization of styrene using the Pd(OAc) 2 + 7BF 3 OEt 2 catalyst system modified with various amounts of PPh 3 ligand at temperatures between 45 and 80 o C. The highest conversion of 145 000 mol styrene per mol palladium with selectivity to dimers of 89.7% was reached at 80 o C with the P/Pd ratio of 2 for 5 h. For a comparison, the Pd(acac) 2 + 2PR 3 + 7BF 3 OEt 2 catalyst system led to a conversion of 75 000 mol styrene per mol palladium with selectivity to dimers of 93% for 7 h at 70 o C [4].…”