Carboranes are of topical interest due to their unique structures and applications in the fields of catalysis, polymers, material sciences and supramolecular chemistry. Icosahedral closo-dicarbadodecaboranes are remarkably robust three-dimensional boron-carbon clusters with two slightly acidic C-H bonds. Coordinatively unsaturated transition-metal complexes containing C-functionalized ortho-carborane are considered as potential catalysts for activation of small molecules. Recently, we reported the synthesis of a pyridine-backbone pincer complex {(C5H3N)(C2B10H10)2}Ni(CH3CN) (1) in which two ortho-carboranes act as the arms of the pincer ligand. The complex 1 was found to be a competent catalyst for nucleophilic addition of piperidine to acetonitrile. Upon addition of KOtBu, we observed activation of a C-H bond of a labile acetonitrile ligand at the nickel center, and N-bound acetonitrile (Ni-NCCH3) was converted to a C-bound cyanomethyl ligand (Ni-CH2CN). Oxidation of K{(C5H3N)(C2B10H10)2}Ni(CH2CN) (2) by oxygen yielded a cyano complex K{(C5H3N)(C2B10H10)2}Ni(CN) (3), along with HCHO, CO2, HO-CH2CN and another unidentified compound. EPR and 1H NMR studies revealed that the reaction followed a free radical pathway (Scheme 1). Currently we are working to identify the active free radical species by using a spin trapping agent, 5,5-Dimethyl-1-pyrroline N-oxide (DMPO). Furthermore, we observed the formation of acrylonitrile and acrylamide by coupling of acetonitrile with aldehyde at the nickel center.

Sterically encumbered dianionic dicarboranyl pincer ligand (C5H3N)(C2B10H11)2 and its nickel(II) complex

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.