The Lewis Assisted C-CN Bond Activation of Benzonitrile Using Zerovalent Group 10 Metal Complexes with Dippe Ligand

Date
2023-09-28
Authors
Escobar, Roberto
Atesin, Abdurrahman
Jones, William D.
Ateşin, Tülay
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Abstract

The exploration of C-C bond activation is significantly propelled by homogeneous transition-metal catalysts, capturing attention for their role in industrial applications and intricate organic molecule synthesis. Nonetheless, the formidable challenge of effecting mild and homogeneous activation of thermodynamically stable and kinetically inert C—C σ-bonds persists. Presently, prevailing activation strategies predominantly entail systems driven by strain relief or aromatization, excepting the intriguing activation of unstrained C—CN bonds within nitriles. Prior investigations leveraging the [(dippe)Ni] fragment alongside Lewis acids have unveiled the manipulation of reaction mechanisms concerning the C-CN bond in benzonitrile. This is suggested in yielding faster reaction rates and nitrogen lone pair coordination that imparts stability through steric bulk or charge redistribution, thereby facilitating C-CN bond cleavage. By employing advanced computational tools, encompassing Gaussian16 and GaussView6 to perform density functional theory (DFT) calculations, this study delves into the C-CN bond activation of benzonitrile. This is achieved by replacing (dippe)Ni(CN) with heavier group 10 metals (Pd and Pt) in both reaction and product substrates. This strategic substitution enables optimizations and novel potential energy surface (PES) scans, guiding the search for intermediates and transition states, with structural validation through ChimeraX ensuring 3D accuracy and predicting the reaction pathway. Furthermore, the influence of Lewis acids (BPh3 and BF3) is examined, elucidating their effects on proposed reaction mechanisms, thermodynamics, and kinetics in comparison to those without Lewis acids. Additional refinements encompass gas phase and solvent corrections (THF and toluene), employing GoodVibes v3.2 for vibrational analysis and thermodynamic predictions, and addressing functional (B3YLP) limitation on π-system interaction via empirical dispersion corrections for heightened result accuracy. This amalgamation of transition-metal catalysts and Lewis acids establishes a foundation for innovative catalytic systems, poised to reshape chemical synthesis methodologies and chart transformative routes toward groundbreaking synthetic pathways.

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