Hammett neural networks: prediction of frontier orbital energies of tungsten-benzylidyne photoredox complexes

Alexander M Chang; Jessica G Freeze; Victor S Batista

doi:10.1039/c9sc02339a

Hammett neural networks: prediction of frontier orbital energies of tungsten-benzylidyne photoredox complexes

Chem Sci. 2019 Jun 12;10(28):6844-6854. doi: 10.1039/c9sc02339a. eCollection 2019 Jul 28.

Authors

Alexander M Chang¹, Jessica G Freeze¹, Victor S Batista¹

Affiliation

¹ Department of Chemistry , Energy Sciences Institute , Yale University , New Haven , CT 06520 , USA . Email: victor.batista@yale.edu.

Abstract

The successful application of Hammett parameters as input features for regressive machine learning models is demonstrated and applied to predict energies of frontier orbitals of highly reducing tungsten-benzylidyne complexes of the form W([triple bond, length as m-dash]CArR)L₄X. Using a reference molecular framework and the meta- and para-substituent Hammett parameters of the ligands, the models predict energies of frontier orbitals that correlate with redox potentials. The regressive models capture the multivariate character of electron-donating trends as influenced by multiple substituents even for non-aryl ligands, harnessing the breadth of Hammett parameters in a generalized model. We find a tungsten catalyst with tetramethylethylenediamine (tmeda) equatorial ligands and axial methoxyl substituents that should attract significant experimental interest since it is predicted to be highly reducing when photoactivated with visible light. The utilization of Hammett parameters in this study presents a generalizable and compact representation for exploring the effects of ligand substitutions.