Thermodynamic and kinetic studies of H 2 and N 2 binding to bimetallic nickel-group 13 complexes and neutron structure of a Ni(η 2 -H 2 ) adduct.

Autor: Cammarota RC; Department of Chemistry , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA . Email: clu@umn.edu., Xie J; Department of Chemistry , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA . Email: clu@umn.edu.; Supercomputing Institute , Chemical Theory Center , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA.; Key Laboratory of Cluster Science of Ministry of Education , School of Chemistry and Chemical Engineering , Beijing Institute of Technology , Beijing 100081 , China., Burgess SA; Catalysis Science Group , Pacific Northwest National Laboratory , P. O. Box 999 , MS K2-57 , Richland , Washington 99352 , USA., Vollmer MV; Department of Chemistry , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA . Email: clu@umn.edu., Vogiatzis KD; Department of Chemistry , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA . Email: clu@umn.edu.; Supercomputing Institute , Chemical Theory Center , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA.; Department of Chemistry , University of Tennessee , Knoxville , Tennessee 37996 , USA., Ye J; Department of Chemistry , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA . Email: clu@umn.edu.; Supercomputing Institute , Chemical Theory Center , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA., Linehan JC; Catalysis Science Group , Pacific Northwest National Laboratory , P. O. Box 999 , MS K2-57 , Richland , Washington 99352 , USA., Appel AM; Catalysis Science Group , Pacific Northwest National Laboratory , P. O. Box 999 , MS K2-57 , Richland , Washington 99352 , USA., Hoffmann C; Neutron Scattering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , USA., Wang X; Neutron Scattering Division , Oak Ridge National Laboratory , Oak Ridge , Tennessee 37831 , USA., Young VG Jr; Department of Chemistry , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA . Email: clu@umn.edu., Lu CC; Department of Chemistry , University of Minnesota-Twin Cities , 207 Pleasant Street SE , Minneapolis , Minnesota 55455 , USA . Email: clu@umn.edu.
Jazyk: angličtina
Zdroj: Chemical science [Chem Sci] 2019 Jun 10; Vol. 10 (29), pp. 7029-7042. Date of Electronic Publication: 2019 Jun 10 (Print Publication: 2019).
DOI: 10.1039/c9sc02018g
Abstrakt: Understanding H 2 binding and activation is important in the context of designing transition metal catalysts for many processes, including hydrogenation and the interconversion of H 2 with protons and electrons. This work reports the first thermodynamic and kinetic H 2 binding studies for an isostructural series of first-row metal complexes: NiML, where M = Al ( 1 ), Ga ( 2 ), and In ( 3 ), and L = [N( o -(NCH 2 P i Pr 2 )C 6 H 4 ) 3 ] 3- . Thermodynamic free energies (Δ G °) and free energies of activation (Δ G ‡ ) for binding equilibria were obtained via variable-temperature 31 P NMR studies and lineshape analysis. The supporting metal exerts a large influence on the thermodynamic favorability of both H 2 and N 2 binding to Ni, with Δ G ° values for H 2 binding found to span nearly the entire range of previous reports. The non-classical H 2 adduct, (η 2 -H 2 )NiInL ( 3 -H 2 ), was structurally characterized by single-crystal neutron diffraction-the first such study for a Ni(η 2 -H 2 ) complex or any d 10 M(η 2 -H 2 ) complex. UV-Vis studies and TD-DFT calculations identified specific electronic structure perturbations of the supporting metal which poise NiML complexes for small-molecule binding. ETS-NOCV calculations indicate that H 2 binding primarily occurs via H-H σ-donation to the Ni 4p z -based LUMO, which is proposed to become energetically accessible as the Ni(0)→M(iii) dative interaction increases for the larger M(iii) ions. Linear free-energy relationships are discussed, with the activation barrier for H 2 binding (Δ G ‡ ) found to decrease proportionally for more thermodynamically favorable equilibria. The Δ G ° values for H 2 and N 2 binding to NiML complexes were also found to be more exergonic for the larger M(iii) ions.
(This journal is © The Royal Society of Chemistry 2019.)
Databáze: MEDLINE
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