In this communication, an improved perturbative triples correction (T) algorithm for domain based local pair-natural orbital singles and doubles coupled cluster (DLPNO-CCSD) theory is reported. our previous implementation, the semi-canonical approximation was used linear scaling achieved both DLPNO-CCSD parts of calculation. work, we refer to method as DLPNO-CCSD(T0) emphasize approximation. It well-established that can predict very accurate absolute relative energies with respect parent...

The challenge in the electrochemical reduction of aqueous carbon dioxide is designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes competitive proton to form hydrogen during CO2 conversion. A non-noble metal based on copper-indium (Cu-In) alloy selectively converts CO with low overpotential reported. deposition In rough Cu surfaces led Cu-In surfaces. DFT calculations showed preferentially located edge sites rather than corner or flat d-electron...

We have investigated the performance of eight popular density functionals, four which are "standard" functionals not including dispersion (B3LYP, BP86, PBE, and TPSS) been constructed to account for (B97D, wB97XD, M06, M06L), in reproducing 18 molecular structures derived from single-crystal X-ray diffraction experiments on ruthenium-based olefin metathesis catalyst precursors. Our analysis all internuclear distances reveals that standard DFT predicts systematically expanded structures. In...

A ligand-controlled and site-selective nickel catalyzed Suzuki–Miyaura cross-coupling reaction with aromatic esters alkyl organoboron reagents as coupling partners was developed. This methodology provides a facile route for C(sp2)–C(sp3) bond formation in straightforward fashion by successful suppression of the undesired β-hydride elimination process. By simply switching phosphorus ligand, ester substrates are converted into alkylated arenes ketone products, respectively. The utility this...

Abstract The challenge in the electrochemical reduction of aqueous carbon dioxide is designing a highly selective, energy‐efficient, and non‐precious‐metal electrocatalyst that minimizes competitive proton to form hydrogen during CO 2 conversion. A non‐noble metal based on copper‐indium (Cu‐In) alloy selectively converts with low overpotential reported. deposition In rough Cu surfaces led Cu‐In surfaces. DFT calculations showed preferentially located edge sites rather than corner or flat...

Previous promising tests of the new M06 family functionals in predicting ruthenium-metal phosphine bond dissociation energies (Zhao, Y.; Truhlar, D. G. Acc. Chem. Res. 2008, 41, 157) have been extended to a series complexes chromium, molybdenum, nickel, and ruthenium for which relevant experimental data are available. In addition functionals, enthalpies calculated using selection density hybrid based on generalized gradient approximation (GGA), with or without an empirical term (i.e., DFT-D)...

Recent discoveries highlighted the activity and intriguing mechanistic features of NbCl5 as a molecular catalyst for cycloaddition CO2 epoxides under ambient conditions. This has inspired preparation novel silica-supported Nb species by reacting niobium precursor, [NbCl5·OEt2], with silica dehydroxylated at 700 °C (SiO2-700) or 200 (SiO2-200) to generate diverse surface complexes. The product reaction between SiO2-700 [NbCl5·OEt2] was identified monopodal supported species, [≡SiONbCl4·OEt2]...

The performance of the domain based local pair-natural orbital coupled-cluster (DLPNO-CCSD(T)) method has been tested to reproduce experimental gas phase ligand dissociation enthalpy in a series Cu(+), Ag(+), and Au(+) complexes. For 33 Cu(+)-noncovalent enthalpies, all-electron calculations with same result MUE below 2.2 kcal/mol, although MSE 1.4 kcal/mol indicates systematic underestimation values. Inclusion scalar relativistic effects for Cu either via effective core potential (ECP) or...

The N-methylation of amines using CO2 and PhSiH3 as source CH3 was efficiently performed a N-heterocyclic carbene copper(i) complex. methodology found compatible with aromatic aliphatic primary secondary amines. Synthetic computational studies have been carried out to support the proposed reaction mechanism for this transformation.

We report here a comprehensive computational analysis of the mechanisms photoredox-nickel-HAT (HAT: hydrogen atom transfer) catalyzed arylation and alkylation α-amino Csp3–H bonds developed by MacMillan co-workers. Different alternatives for three catalytic cycles were tested to identify unambiguously operative reaction mechanism. Our indicated that IrIII photoredox catalyst, upon irradiation with visible light, can be either reduced or oxidized HAT nickel catalysts, respectively, indicating...

The validity of the main approximations used in canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) DLPNO-CCSD(T), respectively) standard chemical applications is discussed. In particular, we investigate dependence results on number electrons included correlation treatment frozen-core (FC) calculations threshold governing accuracy DLPNO all-electron (AE) calculations. Initially, scalar relativistic energies for ground state atoms from Li to Rn periodic table are...

Density functional theory calculations accounting for dispersion, thermochemical, and continuum solvent effects have been applied to study the metathesis of ethyl vinyl ether (EVE) as mediated by ruthenium catalysts L(PCy3)(X)2Ru═CHPh (L = PCy3, IMes (1,3-dimesitylimidazol-2-ylidene), H2IMes (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene); X Cl, Br, I) in toluene. The computational approach has validated against experimental data ruthenium-based olefin is found give acceptable accuracy even...

In this work, we tested canonical and domain based pair natural orbital coupled cluster methods (CCSD(T) DLPNO-CCSD(T), respectively) for a set of 32 ligand exchange association/dissociation reaction enthalpies involving ionic complexes Li, Be, Na, Mg, Ca, Sr, Ba Pb(ii). Two strategies were investigated: in the former, only valence electrons included correlation treatment, giving rise to computationally very efficient FC (frozen core) approach; latter, all non-ECP AE (all electron) approach....

Accessing highly electron deficient partially alkylated tungsten hydrides on silica <italic>via</italic> controlled hydrogenolysis of surface organometallic complex (Si–O–)W(Me)₅.

A series of semiempirical PM6* and PM7 methods has been tested in reproducing relative conformational energies 27 realistic-size complexes 16 different transition metals (TMs). An analysis derived from single-point energy evaluations on density functional theory (DFT) optimized conformers revealed pronounced deviations between DFT methods, indicating a fundamental difference potential surfaces (PES). To identify the origin deviation, we compared fully respective conformers. For many...

Several standard semiempirical methods as well the MMFF94 force field approximation have been tested in reproducing 8 DLPNO-CCSD(T)/cc-pVTZ level conformational energies and spatial structures for 37 organic molecules representing pharmaceuticals, drugs, catalysts, synthetic precursors, industry-related chemicals (37conf8 database). All contemporary surpass their counterparts resulting more reliable structures, even though at significantly higher computational costs. However, these show...

Computational electronic structure calculations are routinely undertaken to predict thermodynamic properties of various species. However, the application highly accurate wave function theory methods, such as "gold standard" coupled cluster approach including single, double, and partly triple excitations in perturbative fashion, CCSD(T), large molecules is limited due high computational cost. In this work, promising domain based local pair natural orbital approach, DLPNO-CCSD(T), has been...

The recently developed DLPNO-CCSD(T) method and seven popular DFT functionals (B3LYP, M06, M06L, PBE, PBE0, TPSS, TPSSh) with without an empirical dispersion term have been tested to reproduce 111 gas phase reaction enthalpies involving 11 different transition metals. Our calculations, corrected for both relativistic effects basis set incompleteness, indicate that most of the methods applied default settings perform acceptable accuracy on average. Nevertheless, our calculations also...

A well-defined silica-supported monoalkylated tungsten dioxo complex [(≡Si–O−)W(═O)2(CH2–tBu)] was prepared by treatment of highly dehydroxylated silica (SiO2-700: treated at 700 °C under high vacuum) with an ionic precursor [NEt4][W(═O)3(CH2–tBu)]. The identity the resulting neutral surface established means elemental microanalysis and spectroscopic studies (IR, solid-state NMR, Raman, X-ray absorption spectroscopies). supported found to act as a precatalyst for self-metathesis 1-octene in...

The experimental gas-phase thermochemistry of reactions: M+ (S)n-1 + S → (S)n and nS→ , where M is an alkali metal acetonitrile/ammonia, reproduced. Three approximations are tested: (1) scaled rigid-rotor-harmonic-oscillator (sRRHO); (2) the sRRHO(100) identical to (1), but with all vibrational frequencies smaller than 100 cm-1 replaced ; (3) Grimme's modified RRHO (msRRHO) (Grimme, Chem. Eur. J., 2012, 18, 9955-9964). msRRHO approach provides most accurate reaction entropies mean unsigned...

Abstract By using cost‐efficient density functional theory accounting for dispersion in combination with an implicit solvent model, the first time it has been possible to reproduce activation Gibbs free energies phosphane dissociation from Grubbs ruthenium olefin metathesis precatalysts solution good accuracy (mean unsigned error compared experiment &lt;2.5 kcal mol –1 ). The barrier is calculated be range 17.8–25.7 a set of nine catalysts, and found located at intermediate Ru–P distances...

A palladium N-heterocyclic carbene catalyzed methodology for the synthesis of substituted, N-unprotected indoles and azaindoles is reported. The protocol permits access to various, highly substituted members these classes compounds. Although two possible reaction pathways (deprotonative Heck-like) can be proposed, control experiments, supported by computational studies, point toward a deprotonative mechanism being operative.

The enthalpy of association Lewis bases with TiCl₄ is analyzed using experimental and computational techniques.