18433-72-2Relevant academic research and scientific papers
A Bimetallic Nickel-Gallium Complex Catalyzes CO2 Hydrogenation via the Intermediacy of an Anionic d10 Nickel Hydride
Cammarota, Ryan C.,Vollmer, Matthew V.,Xie, Jing,Ye, Jingyun,Linehan, John C.,Burgess, Samantha A.,Appel, Aaron M.,Gagliardi, Laura,Lu, Connie C.
, p. 14244 - 14250 (2017)
Large-scale CO2 hydrogenation could offer a renewable stream of industrially important C1 chemicals while reducing CO2 emissions. Critical to this opportunity is the requirement for inexpensive catalysts based on earth-abundant metals instead of precious metals. We report a nickel-gallium complex featuring a Ni(0)→ Ga(III) bond that shows remarkable catalytic activity for hydrogenating CO2 to formate at ambient temperature (3150 turnovers, turnover frequency = 9700 h-1), compared with prior homogeneous Ni-centered catalysts. The Lewis acidic Ga(III) ion plays a pivotal role in stabilizing catalytic intermediates, including a rare anionic d10 Ni hydride. Structural and in situ characterization of this reactive intermediate support a terminal Ni-H moiety, for which the thermodynamic hydride donor strength rivals those of precious metal hydrides. Collectively, our experimental and computational results demonstrate that modulating a transition metal center via a direct interaction with a Lewis acidic support can be a powerful strategy for promoting new reactivity paradigms in base-metal catalysis.
Catalytic Enantioselective Hetero-dimerization of Acrylates and 1,3-Dienes
Jing, Stanley M.,Balasanthiran, Vagulejan,Pagar, Vinayak,Gallucci, Judith C.,RajanBabu
, p. 18034 - 18043 (2017/12/26)
1,3-Dienes are ubiquitous and easily synthesized starting materials for organic synthesis, and alkyl acrylates are among the most abundant and cheapest feedstock carbon sources. A practical, highly enantioselective union of these two readily available pre
Cobalt-Catalyzed Asymmetric Hydroboration/Cyclization of 1,6-Enynes with Pinacolborane
Yu, Songjie,Wu, Caizhi,Ge, Shaozhong
supporting information, p. 6526 - 6529 (2017/05/29)
We report a cobalt-catalyzed asymmetric hydroboration/cyclization of 1,6-enynes with catalysts generated from Co(acac)2 and chiral bisphosphine ligands and activated in situ by reaction with pinacolborane (HBpin). A variety of oxygen-, nitrogen
Comprehensive thermodynamic characterization of the metal-hydrogen bond in a series of cobalt-hydride complexes
Ciancanelli, Rebecca,Noll, Bruce C.,DuBois, Daniel L.,Rakowski DuBois
, p. 2984 - 2992 (2007/10/03)
A detailed structural and thermodynamic study of a series of cobalt-hydride complexes is reported. This includes structural studies of [H2Co(dppe)2]+, HCo(dppe)2, [HCo(dppe)2(CH3CN)]+, and [Co(dppe)2-(CH3CN)]2+, where dppe = bis(diphenylphosphino)ethane. Equilibrium measurements are reported for one hydride- and two proton-transfer reactions. These measurements and the determinations of various electrochemical potentials were used to determine 11 of 12 possible homolytic and heterolytic solution Co-H bond dissociation free energies of [H2Co(dppe)2]+ and its monohydride derivatives. These values provide a useful framework for understanding observed and potential reactions of these complexes. These reactions include the disproportionation of [HCo(dppe)2]+ to form [Co(dppe)2]+ and [H2Co(dppe)2]+, the reaction of [Co(dppe)2]+ with H2, the protonation and deprotonation reactions of the various hydride species, and the relative ability of the hydride complexes to act as hydride donors.
Reactions of cobalt(II) with NaBH4 in the presence of bidentate phosphines: Crystal and molecular structures of CoH[Ph2P(CH2)3PPh2] 2·C6H6 and [Co(BH4)[Ph2P(CH2)5PPh 2]]20.5C6H6
Holah, David G.,Hughes, Alan N.,Maciaszek, Stanislaw,Magnuson, Vincent R.,Parker, Kenneth O.
, p. 3956 - 3962 (2008/10/08)
The reactions between Co(II) and NaBH4 in the presence of the phosphines Ph2P(CH2)nPPh2 (n = 2-6) and cis- and trans-Ph2PCH=CHPPh2 lead, through a series of intermediates, to the formation of CoH(phosphine)2 species, except in the case of the trans ligand, where hydrogenation occurs and CoH[Ph2P(CH2)2PPh2]2 is formed. Single-crystal X-ray diffraction studies on CoH[Ph2P(CH2)3PPh2] 2·C6H6 show that the compound crystallizes in the monoclinic space group P21/n, with unit cell parameters a = 13.640 (6) A?, b = 15.794 (5) A?, c = 23.870 (9) A?, β = 101.04 (4)°, V = 5047.2 A?3, Z = 4, and dcalcd = 1.267 g cm-3. The structure converged to a conventional R factor of 0.042 for 4754 observations and showed a five-coordinated Co(I) atom with two chelating phosphines and a hydride group in a distorted-trigonal-bipyramidal arrangement. In addition, with two of the longer chain phosphines (n = 4, 5) it is possible to isolate Co(I)-BH4 species shown, in the case of n = 5, to be [Co-(BH4)[Ph2P(CH2)5PPh 2]]2·0.5C6H6. This compound crystallizes in the triclinic space group P1 with unit cell parameters a = 10.305 (3) A?, b = 14.990 (3) A?, c = 20.343 (5) A?, α = 107.87 (2)°, β = 90.72 (2)°, γ = 105.88 (2)°, V = 2861 (3) A?3, Z = 2, and dcalcd = 1.240 g cm-3. The structure converged to a conventional R factor of 0.052 for 4290 observations. The dimeric species consists of two Co(I) atoms bridged by both phosphine ligands and BH4 ligands in a hitherto unknown way such that each BH4 group chelates to each cobalt using one common hydrogen, leaving one terminal hydrogen uninvolved. Alternatively, the BH4 group can be considered as a tridentate ligand to two cobalt atoms separated by 2.869 (1)A?. The cobalt and boron atoms are almost coplanar, but, since there is no obvious strain in the Co-P(CH2)5P-Co linkages, the steric and electronic requirements of the bridging tetrahydroborate groups apparently dictate the distorted coordination geometry about the Co atoms.
