Accurate computed spin-state energetics for Co(iii) complexes: implications for modelling homogeneous catalysis

Abstract

DLPNO-CCSD(T) calculations provide accurate spin state energetics for a range of Co(iii) complexes and so represent a promising approach to modelling homogeneous catalysis based on Co(iii) species.

Effects of 2,6‐Dichlorophenyl Substituents on the Coordination Chemistry of Pyridine Dipyrrolide Iron Complexes

“…A further complication is that the doubleshell effect has not been captured by our CAS(10,8) reference. The inclusion of the 4d (often called 3d’) shell in the zeroth‐order wavefunction is important to account for radial electron correlation, a phenomenon which is not handled by perturbation theory but has been shown to improve the accuracy of electronic structures and spin‐state energetics [30,32–36] . Inclusion of these high‐energy orbitals has also proven critical to obtaining more accurate electronic descriptions for other systems with M=E (M=Mn or Fe; E=O or N) multiple bonds [35,36] .…”

[Ni(NHC)2] as a Scaffold for Structurally Characterized trans [H−Ni−PR2] and trans [R2P−Ni−PR2] Complexes

“…The much higher barrier associated with TS(II ‐ trans ‐ III) arises from the coupling of P−H bond cleavage with a cis‐trans isomerisation process. The triplet form of [Ni(IMe 4 ) 2 (PPh 2 )H], 3 III , has a computed energy of +23.7 kcal mol −1 and so is not implicated in this isomerisation [51] . IMe 4 dissociation from cis ‐ III was also ruled out as this incurs a free energy penalty of 25.7 kcal mol −1 .…”

“…The triplet form of [Ni(IMe 4 ) 2 (PPh 2 )H], 3 III , has a computed energy of +23.7 kcal mol −1 and so is not implicated in this isomerisation. [51] IMe 4 dissociation from cis ‐ III was also ruled out as this incurs a free energy penalty of 25.7 kcal mol −1 . Overall, trans ‐ III is formed with an overall barrier of 19.6 kcal mol −1 in a process that is exergonic by 2.4 kcal mol −1 relative to I .…”

Successes, challenges, and opportunities for quantum chemistry in understanding metalloenzymes for solar fuels research

“…DLPNO-CCSD(T). [215][216][217] The method has already been applied with success in smaller transition metal systems, [218][219][220][221] but the OEC presents much greater challenges. Pilot applications on minimal structural models have been reported but it remains to be seen whether successful applications are possible on realistic models of the OEC.…”