Computational Investigation into the Ni(SeNHC2(CN)2)2 and Ni(SNHC2(CN)2)2 Complexes as Potential Catalysts for Hydrogen Production.
19 Aug 2019-Journal of Physical Chemistry A (American Chemical Society)-Vol. 123, Iss: 36, pp 7822-7827
TL;DR: From the calculated thermodynamics, it appears that the Ni(SeNHC2(CN)2)2 complex is predicted to catalyze the production of H2 gas under mildly reducing conditions relative to the SHE, and may offer a means to improve the catalysts for H2 production.
Abstract: To reduce our carbon footprint, we must look at alternative non-carbon-containing fuels to prevent continued global climate change. One environmentally friendly alternative fuel is molecular hydrog...
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01 Feb 1995
TL;DR: In this paper, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg
1,652 citations
01 Jan 1994
TL;DR: In this article, the synthesis, structures, and redox properties of isomorphous Ni(I1) thiolato and selenolato complexes of the tridentate ligands bis(2-(hydrochalcogeno)ethyl)methylamines are reported.
Abstract: The syntheses, structures, and redox properties of isomorphous Ni(I1) thiolato and selenolato complexes of the tridentate ligands bis(2-(hydrochalcogeno)ethyl)methylamines are reported. Reaction of Ni(0Ac)z with bis(2mercaptoethy1)methylamine leads to the formation of a dimeric complex, bis{ [@-2-mercaptoethyl)(2-mercaptoethyl)methylaminato(2-)]nickel(II)}, [Ni(l)]2. This complex contains planar, diamagnetic Ni(I1) centers ligated by a tertiary amine N-donor atom, a terminal thiolate, and two thiolates that bridge to the second Ni center in the dimer. Crystals of [Ni(l)]2 form in orthorhombic space group h a 2 1 with cell dimensions a = 19.695(2) 8, b = 6.042(2) 8, c = 13.463(3) 8, V = 1602(1) A3, and Z = 4. Reaction of Ni(0Ac)p with bis(2-(hydroseleno)ethy1)methylamine results in the formation of a structurally analogous dimeric complex, bis([@-2-(hydroseleno)ethyl)(2-(hydroseleno)ethyl)methylaminato(2-)]nickel(II)}, [Ni(2)]2, where all of the chalcogenolate donors are selenolates. Crystals of [Ni(2)]2 are isomorphous with those of [Ni(l)]z, with a = 20.040(8) 8, b = 6.265(2) 8, c = 13.590(5) 8, and V = 1706(2) A3, One-electron oxidation of either dimeric complex leads to the formation of radical cations, which exhibit EPR spectra consistent with S = l/2 radicals. For [Ni(l)]2+ the g values observed (gx = 2.20, g, = 2.14, g, = 2.02) are essentially identical to those observed for a reduced and catalytically viable redox state of Fe,Ni hydrogenases (gx = 2.20, g, = 2.14, g, = 2.01). The substitution of Sefor S-donors in [Ni(2)]2 does not alter the observed g values much (gx = 2.23, g, = 2.14, g, = 2.05) but leads to the observation of 77Se hyperfine coupling (A, = 129 G) that indicates that the molecular orbital containing the unpaired spin is largely Se in character (54%). Reaction of either dimeric complex with CNleads to the formation of mononuclear trans-dichalcogenolate complexes, [Ni(l)CN]and [Ni(2)CN]-. Exposure of [Ni(l)CN]to 0 2 leads to the quantitative formation of a monosulfinato complex. In contrast, the selenolato complex does not react with 0 2 under the same conditions. The role of selenocysteinate ligation in Fe,Ni,Se hydrogenases is discussed in view of this chemistry.
37 citations
TL;DR: A new cobalt complex, [(btep)CoBr2], was produced by the reaction of CoBr2 and bis(methylthioether)pyridine (btep), and its structure has been determined by X-ray crystallography as mentioned in this paper.
3 citations
TL;DR: In this article, the reactivity of OH with Ni(X2C2H2)2 and Ni(S or Se) was investigated, and it was found that the OH radical attacks a backbone C atom.
Abstract: In the present study, the reactivity of OH with Ni(X2C2H2)2 and Ni(X2C2H2)2 – (where X = S or Se) was investigated. From the thermodynamics, it found that the OH radical attacks a backbone C atom o...
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TL;DR: In this article, a semi-empirical exchange correlation functional with local spin density, gradient, and exact exchange terms was proposed. But this functional performed significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
Abstract: Despite the remarkable thermochemical accuracy of Kohn–Sham density‐functional theories with gradient corrections for exchange‐correlation [see, for example, A. D. Becke, J. Chem. Phys. 96, 2155 (1992)], we believe that further improvements are unlikely unless exact‐exchange information is considered. Arguments to support this view are presented, and a semiempirical exchange‐correlation functional containing local‐spin‐density, gradient, and exact‐exchange terms is tested on 56 atomization energies, 42 ionization potentials, 8 proton affinities, and 10 total atomic energies of first‐ and second‐row systems. This functional performs significantly better than previous functionals with gradient corrections only, and fits experimental atomization energies with an impressively small average absolute deviation of 2.4 kcal/mol.
87,732 citations
TL;DR: Numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, show that density-functional formulas for the correlation energy and correlation potential give correlation energies within a few percent.
Abstract: A correlation-energy formula due to Colle and Salvetti [Theor. Chim. Acta 37, 329 (1975)], in which the correlation energy density is expressed in terms of the electron density and a Laplacian of the second-order Hartree-Fock density matrix, is restated as a formula involving the density and local kinetic-energy density. On insertion of gradient expansions for the local kinetic-energy density, density-functional formulas for the correlation energy and correlation potential are then obtained. Through numerical calculations on a number of atoms, positive ions, and molecules, of both open- and closed-shell type, it is demonstrated that these formulas, like the original Colle-Salvetti formulas, give correlation energies within a few percent.
84,646 citations
TL;DR: The M06-2X meta-exchange correlation function is proposed in this paper, which is parametrized including both transition metals and nonmetals, and is a high-non-locality functional with double the amount of nonlocal exchange.
Abstract: We present two new hybrid meta exchange- correlation functionals, called M06 and M06-2X. The M06 functional is parametrized including both transition metals and nonmetals, whereas the M06-2X functional is a high-nonlocality functional with double the amount of nonlocal exchange (2X), and it is parametrized only for nonmetals.The functionals, along with the previously published M06-L local functional and the M06-HF full-Hartree–Fock functionals, constitute the M06 suite of complementary functionals. We assess these four functionals by comparing their performance to that of 12 other functionals and Hartree–Fock theory for 403 energetic data in 29 diverse databases, including ten databases for thermochemistry, four databases for kinetics, eight databases for noncovalent interactions, three databases for transition metal bonding, one database for metal atom excitation energies, and three databases for molecular excitation energies. We also illustrate the performance of these 17 methods for three databases containing 40 bond lengths and for databases containing 38 vibrational frequencies and 15 vibrational zero point energies. We recommend the M06-2X functional for applications involving main-group thermochemistry, kinetics, noncovalent interactions, and electronic excitation energies to valence and Rydberg states. We recommend the M06 functional for application in organometallic and inorganometallic chemistry and for noncovalent interactions.
22,326 citations
TL;DR: In this article, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
Abstract: : The unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio. Harmonic force fields are obtained using Density Functional Theory (DFT), MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set. DFT calculations use the Local Spin Density Approximation (LSDA), BLYP, and Becke3LYP (B3LYP) density functionals. Mid-IR spectra predicted using LSDA, BLYP, and B3LYP force fields are of significantly different quality, the B3LYP force field yielding spectra in clearly superior, and overall excellent, agreement with experiment. The MP2 force field yields spectra in slightly worse agreement with experiment than the B3LYP force field. The SCF force field yields spectra in poor agreement with experiment.The basis set dependence of B3LYP force fields is also explored: the 6-31G* and TZ2P basis sets give very similar results while the 3-21G basis set yields spectra in substantially worse agreements with experiment. jg
17,871 citations
TL;DR: The authors assess various approximate forms for the correlation energy per particle of the spin-polarized homogeneous electron gas that have frequently been used in applications of the local spin density a...
Abstract: We assess various approximate forms for the correlation energy per particle of the spin-polarized homogeneous electron gas that have frequently been used in applications of the local spin density a...
17,531 citations