A B3LYP-DBLOC empirical correction scheme for ligand removal enthalpies of transition metal complexes: parameterization against experimental and CCSD(T)-F12 heats of formation

Abstract

Average ligand removal enthalpies of 30 differently coordinated mono-nuclear fourth-row transition metal complexes taken from a database recently considered by Johnson and Becke [Can. J. Chem., 2009, 8, 1369] have been computed in the gas phase using unrestricted pseudo-spectral (LACV3P) and fully analytic (qzvp(-g)) B3LYP including a recently developed empirical dispersion correction. Heats of formation of neutral singlet reactants and neutral, potentially high spin, products have been taken from NIST's Organometallic Thermochemistry Database. Comparison of B3LYP-MM//qzvp(-g) and experimental average ligand removal enthalpies reveals a systematic error in the reported experimental enthalpies for manganese-containing complexes which is verified with high-level, CCSD(T)-F12//family of cc-pVTZ, explicitly correlated coupled-cluster methods. Other B3LYP-MM//qzvp(-g) error patterns give rise to a d-block localized orbital correction (DBLOC) scheme containing six transferable parameters that correct the functional's description of metal-ligand bonding, cation-π, and dispersion interactions as well as metal and/or ligand multi-reference effects. Metal-ligand cation-π and dispersion interactions have been fit to the monopole/induced-dipole, C(4)/R(4), and induced-dipole/induced-dipole, C(6)/R(6), interaction functions, respectively. This DBLOC model has been built upon a previously determined set of metal atom parameters which are necessary to properly describe the free metal atom reaction products. The final DBLOC model brings the mean unsigned error of B3LYP-MM//qzvp(-g) from 3.74 ± 3.51 kcal/mol to 0.94 ± 0.68 kcal/mol and corrects the functional's under binding in nearly every case. Several important connections among DBLOC parameters have been made.

Jaguar: A high‐performance quantum chemistry software program with strengths in life and materials sciences

“…Included are ionization potentials and electron affinities, transition state energetics, and a model that covers transition metals (redox potentials, spin splittings, and atomization energies). The errors remain consistent with those discussed above; MUEs of ∼1 kcal/mole for second and third row atoms, and 2–3 kcal/mole for transition metals . The increased error in case of transition metals is due to a combination of the greater complexity of the electronic structure of transition metal atoms and chemical bonding, and the paucity and lower quality of experimental data for transition‐metal‐containing systems.…”

“…The reference state ligand field diagram is defined to be the electronic state of lowest spin multiplicity for the metal cation in its most common oxidation state. Each operator is associated with a B3LYP‐DBLOC correction parameter which has been fit to large and diverse databases of experimental spin‐splitting, redox, and ligand removal energetics.…”

“…The basic idea is to associate errors in DFT energetics, particularly for the B3LYP functional, with specific electron pairs (chemical bonds and lone pairs) and singly occupied orbitals, and to assume the transferability of these errors for a specific chemical environment from one molecule to another. This approach has enabled chemical accuracy (∼1 kcal/mole average errors) to be obtained for molecules composed of second and third row atoms, and somewhat larger average errors of 2‐3 kcal/mole for redox potentials, spin splittings, and metal‐ligand bond energies in systems containing transition metal atoms . These results compare favorably with alternative efforts to improve DFT accuracy, and therefore we decided to include several LOC‐based methods in Jaguar.…”

Diagnosekompetenz durch informelle Lernarrangements?

“…Hughes et al. recently presented a special dispersion correction for ligand‐removal enthalpies of transition‐metal complexes 29…”

Computational Kinetics of Cobalt‐Catalyzed Alkene Hydroformylation

“…Based on our experience, [18] our CCSD(T)-F12 protocol should yield accurate energies for transition metal compounds, with an error of approximately 10 kJ mol À1 . The experimental room temperature enthalpy change for the hydrogenation and hydroformylation of propene are À123.9 and À109.9 kJ mol À1 respectively, [19] compared to calculated values of À122.9 and À108.4 kJ mol À1 .…”