Bond Dissociation Energies for Diatomic Molecules Containing 3d Transition Metals: Benchmark Scalar-Relativistic Coupled-Cluster Calculations for 20 Molecules

Abstract

Benchmark scalar-relativistic coupled-cluster calculations for dissociation energies of the 20 diatomic molecules containing 3d transition metals in the 3dMLBE20 database ( J. Chem. Theory Comput. 2015 , 11 , 2036 ) are reported. Electron correlation and basis set effects are systematically studied. The agreement between theory and experiment is in general satisfactory. For a subset of 16 molecules, the standard deviation between computational and experimental values is 9 kJ/mol with the maximum deviation being 15 kJ/mol. The discrepancies between theory and experiment remain substantial (more than 20 kJ/mol) for VH, CrH, CoH, and FeH. To explore the source of the latter discrepancies, the analysis used to determine the experimental dissociation energies for VH and CrH is revisited. It is shown that, if improved values are used for the heterolytic C-H dissociation energies of di- and trimethylamine involved in the experimental determination, the experimental values for the dissociation energies of VH and CrH are increased by 18 kJ/mol, such that D(VH) = 223 ± 7 kJ/mol and D(CrH) = 204 ± 7 kJ/mol (or D(VH) = 233 ± 7 kJ/mol and D(CrH) = 214 ± 7 kJ/mol). The new experimental values agree quite well with the calculated values, showing the consistency of the computation and the measured reaction thresholds.

Thirty years of density functional theory in computational chemistry: an overview and extensive assessment of 200 density functionals

“…A recent study by Truhlar et al [227] concluded that CCSD(T) should not be used as a reference to validate density functionals, which complicates the proper benchmarking of density functionals for transition metal chemistry. Very recently, however, two studies [228,229] demonstrated that CCSD(T) can be reliably used for the prediction of transition metal bond dissociation energies. Nevertheless, it is important to verify that the best functionals resulting from this study are capable of handling transition metals with reasonable accuracy, since the database utilised thus far is entirely composed of main-group elements.…”

Predicting Ligand-Dissociation Energies of 3d Coordination Complexes with Auxiliary-Field Quantum Monte Carlo

“…[31][32][33][34][35] However, the reliability of CC methods for transition metal systems, even when multireference effects are approximated, has been the subject of vigorous debate, as illustrated by recent studies on transition metal diatomic-ligand systems. 24,[36][37][38][39][40][41] de Oliveira-Filho and co-workers found that even multireference CCSD(T) could not predict the bond dissociation energies (BDEs) for some diatomics accurately with respect to experimental measurements. A recent study by Head-Gordon and co-workers found that high levels of CC, up to CCSDTQ, are required for chemical accuracy against an exact method known as Adaptive Sampling Configuration Interaction (ASCI) results, albeit in a small basis set.…”

Accuracy of theoretical catalysis from a model of iron-catalyzed ammonia synthesis

“…The D 0 for Fe-H of 148 kJ mol −1 reported in the Handbook of Chemistry and Physics 67 has been revised to 179 kJ mol −1 based on very accurate multi-configurational ab initio methods 68 . The need for upwards revision of the low FeH value has been previously addressed by others 68,69 and thus we used the value 179 kJ mol −1 . Dispersion corrections are negligible for these reactions: The largest correction computed by the D3 method 70 amounts to −0.76 kJ mol −1 for Fe-N 2 .…”