N-Atom transfer via thermal or photolytic activation of a Co-azido complex with a PNP pincer ligand

Thermal or photolytic activation of well-defined mononuclear [Co(N₃)(PNP)] (PNP = 2,2′-bis(diisopropylphosphino)-4,4′-ditolylamido) results in the structurally characterized dinuclear species [Co(μ-N;κ³-P,N,N-PN^PN)]₂ (3), with two N-bridging phosphiniminato bridgeheads. Density Functional Theory (DFT) calculations indicate the intermediacy of a mononuclear cobalt–nitrido complex, followed by N-migratory insertion into a Co–P bond. Reaction of 3 with two equiv. HCl leads to rupture of the dimer with formation of mononuclear [CoCl(PN^PN^H)] (4) by protonation of the N-bridges.