σ versus π‐radical: Tuning the electronic nature of neutral carbon (I) compounds with three non‐bonding electrons

Abstract The bonding and reactivity of the hypo‐coordinated compounds with one, two, and four non‐bonding electrons namely, carbon‐centered free radical, carbenes, and carbones were well earlier established. Here, we report stability, bonding and reactivity of compounds RCL, where R is one‐electron donor group (R = CH 3 ( a ), CHO ( b ), and NO 2 ( c )) and L is two‐electron donor ligand (L = cAAC ( 1 ), CO ( 2 ), NHC ( 3 ) and PMe 3 ( 4 )), having three non‐bonding electrons. The ground states of molecules exist in a doublet with a lone pair of electrons and an unpaired electron at the central carbon atom (C1). The spin hops over from π‐ to σ‐type orbitals is observed as the π‐acceptor strength of the donor ligand increases. The replacement of the methyl group by CHO and NO 2 indicate that the cAAC and CHO substituted compounds gives a σ‐radical except in compound 2c . These molecules show very high proton affinity and exothermic reaction energy for the hydrogen atom addition indicating dual reactivity namely, radical and lone pair reactivity.