Ligand and solvent effects on CO₂ insertion into group 10 metal alkyl bonds

Abstract

The kinetics of carbon dioxide insertion into a pincer-supported palladium methyl complex are studied. The complex inserts carbon dioxide at room temperature, and we explore both solvent and Lewis acid effects on carbon dioxide insertion.

Ethylene Dimerization and Oligomerization Using Bis(phosphino)boryl Supported Ni Complexes

“…( t Bu PBP)­NiOAc ( 1 ), and ( t Bu PBP)­NiBr ( 2 ), and ( Ph PBP)­H were synthesized based on published procedures.…”

“…Synthesis and Characterization of Ni Complexes. ( tBu PBP)-NiOAc (1), 49 and ( tBu PBP)NiBr (2), 50 and ( Ph PBP)H 33 were synthesized based on published procedures.…”

“…■ RESULTS AND DISCUSSION Initial Screening for Ethylene Dimerization. During the initial screening via in situ 1 H NMR spectroscopy, ( tBu PBP)-NiOAc (1), which was synthesized from ( tBu PBP)NiMe and CO 2 , 49 was found to catalyze the slow dimerization of ethylene to form 1-butene without a co-catalyst at 90 °C using C 6 D 6 as the solvent (Table 1, entry 1). To test if the acetate group is required for the reaction, ( tBu PBP)NiBr (2) was used, and no peaks associated with the formation of butenes were observed in the 1 H NMR spectra (Table 1, entry 2).…”

“…Pincer ligands have been widely used in transition metal-mediated catalysis due, in part, to their tunable steric and electronic properties. − As part of the pincer ligand family, examples of bis­(phosphino)­boryl ligands ( R PBP) have been designed and synthesized by the Nozaki and Yamashita groups, − and later, ( R PBP) ligands were studied with transition metals such as Os, Ir, Pt, Ru, Rh, Pd, and Co. − Nickel complexes with t Bu PBP ligands have been isolated and reported to be active for olefin hydrogenation and CO 2 reduction. − In addition, experimental evidence has been reported for the formation of a σ-borane (η 2 -B–H)­Ni­(0) species from the reaction of ( t Bu PBP)­NiH with 1,5-cyclooctadiene, which suggests that the hydride ligand is capable of migration from the Ni center to the boron center (Scheme ). Recently, the Nozaki group has synthesized a bidentate Ni(0) σ-borane complex {(η 2 -B–H/P)­Ni} and demonstrated its application in catalytic polymerization of ethylene for which the (η 2 -B–H/P)Ni complex behaves as a masked Ni­(II) boryl hydride that selectively produces linear polyethylene but not lower molecular weight ethylene oligomers (Scheme ).…”

Configurational Flexibility of a Triaryl-Supported SBS Ligand with Rh and Ir: Structural Investigations and Olefin Isomerization Catalysis

“…In 2009, Yamashita and Nozaki reported that the B–H bond in a diazaborole proligand could be oxidatively added across Ir I starting materials to form Ir III PBP pincer complexes (Chart ). Since then, these PBP ligands and variations thereof have been explored with other mid-to-late transition metals in addition to Ir . Moreover, Ozerov and Tauchert introduced a related class of PBP pincers that use a diaryl scaffold to connect the PBP donor atoms, and dipyrrole examples have also been prepared by Ozerov via Al/B transelementation …”