Computational design of molecular homogeneous organometallic catalysts followed by experimental realization remains a significant challenge. Here, we report the development and use of a density functional theory transition-state model that provided quantitative prediction of molecular Cr catalysts for controllable selective ethylene trimerization and tetramerization. This computational model identified a general class of phosphine monocyclic imine (P,N)-ligand Cr catalysts where changes in the ligand structure control 1-hexene versus 1-octene selectivity. Experimental ligand and catalyst synthesis as well as reaction testing quantitatively confirmed predictions.

The use of data science tools to provide the emergence of nontrivial chemical features for catalyst design is an important goal in catalysis science. Additionally, there is currently no general...

Homodinuclear transition-metal catalysts with a direct metal–metal bond have the potential to induce novel reaction mechanisms and selectivity compared with mononuclear catalysts. The dinuclear ( i‑PrNDI)­Ni2(C6H6) (NDI = naphthyridine-diimine) complex catalyzes selective cyclotrimerization of monosubstituted alkynes, whereas mononuclear Ni catalysts generally give cyclotetramerization of alkynes. Density functional theory calculations reveal that the homodinuclear Ni–Ni catalyst induces a spin crossover mechanism that involves metallacyclopentadiene and nonclassical bridging metallacycloheptatriene intermediates. The cis configuration of the nonclassical bridging metallacycloheptatriene Ni–vinyl bonds results in alkyne cyclotrimerization by fast reductive elimination. This dinuclear mechanism differs from previously reported mononuclear Ni mechanisms and provides an explanation for cyclotrimerization versus cyclotetramerization selectivity and arene regioselectivity.