Formation of PCP pincer cobalt complexes with cobaltacyclopropane moieties via double Csp3–H bond activation

Abstract

The introduction and changes of the substituents at the middle carbon atom of the preligand dipyrrolmethane have a significant impact on the reaction results. When the substituent at the C_sp³ atom is a methyl group, the reaction of the preligand with CoMe(PMe₃)₄ delivered cobalt(I) complex 2 as a C_sp³–H bond activation product. In the case of ethyl, propyl and pentyl groups, PCP pincer cobalt complexes 3–5 with cobaltacyclopropane moieties were formed via double C_sp³–H bond activation. With iso-propyl as the substituent, cobalt(I) complex 6 as C_sp²–H activation product was obtained.