Singlet-to-Triplet Spin Transitions Facilitate Selective 1‑Butene Formation during Ethylene Dimerization in Ni(II)-MFU‑4l

• Published in: Journal of physical chemistry. C Vol. 125; no. 40; pp. 22036 - 22043
• Main Authors: Mancuso, Jenna L, Gaggioli, Carlo A, Gagliardi, Laura, Hendon, Christopher H
• Format: Journal Article
• Language: English
• Published: American Chemical Society 14-10-2021
• Subjects: C: Chemical and Catalytic Reactivity at Interfaces
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/acs.jpcc.1c07658

Catalytic ethylene dimerization is an important chemical reaction that suffers from a lack of selectivity for the desired product, 1-butene. Metal–organic frameworks (MOFs) bearing Ni-based catalytic sites have been shown to yield record selectivity for 1-butene. Early efforts to understand this selectivity revealed that chain propagation and 2-butene formation are competitive with 1-butene, seemingly at odds with experimental evidence that these products are disfavored. Here, we present an alternative mechanism for selective 1-butene formation in the highest performing MOF, Ni­(II)-MFU-4l. Our study reveals competing electronic spin configuration pathways that intersect along the reaction coordinate. Intersystem crossing provides an explanation for the selective formation of 1-butene in the MOF. Furthermore, we explore intersystem crossing as a unique design principle for MOF catalyst design and highlight a departure from conventional molecular catalyst design paradigms.