Photoredox
catalysis can be used to manipulate the redox state
of a transition metal complex leading to the desired reactivity. While
powerful, obviating the role of the second catalyst would be attractive
from the perspective of simplifying the protocol and using visible
light to uncover unexpected, enabling reactivity. Herein we report
that Co-acetylides, formed in situ, are photoactive complexes that
undergo ligand-to-metal charge transfer using visible light. The net
transformation uses air-stable Co(II) complexes as precatalysts and
induces Co(I) chemistry. The acetylide is an electron reservoir forming
the Co(I) but accepting the electron back at the end of the catalytic
cycle. The electronic nature of the acetylide leads to either on–off
behavior or simply initiates catalysis, depending on electronics.
The dialkyl-ortho-biaryl class of phosphines,
commonly known as Buchwald-type ligands, are among the most important
phosphines in Pd-catalyzed cross-coupling. These ligands have also
been successfully applied to several synthetically valuable Ni-catalyzed
cross-coupling methodologies and, as demonstrated in this work, are
top performing ligands in Ni-catalyzed Suzuki Miyaura Coupling (SMC)
and C–N coupling reactions, even outperforming commonly employed
bisphosphines like dppf in many circumstances. However, little is
known about their structure–reactivity relationships (SRRs)
with Ni, and limited examples of well-defined, catalytically relevant
Ni complexes with Buchwald-type ligands exist. In this work, we report
the analysis of Buchwald-type phosphine SRRs in four representative
Ni-catalyzed cross-coupling reactions. Our study was guided by data-driven
classification analysis, which together with mechanistic organometallic
studies of structurally characterized Ni(0), Ni(I), and Ni(II) complexes
allowed us to rationalize reactivity patterns in catalysis. Overall,
we expect that this study will serve as a platform for further exploration
of this ligand class in organonickel chemistry as well as in the development
of new Ni-catalyzed cross-coupling methodologies.
This perspective describes Auto-QChem, an automatic, high-throughput and end-to-end DFT calculation workflow that computes chemical descriptors for organic molecules.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.