Double Intramolecular 1,2 C-H Addition of o-Methyl Groups To Form Ruthenium Pincer Double Tuck-In Complexes

Ruthenium pincer complexes have a rich history of coordination and reaction chemistries. In this work, we report our discoveries of previously unreported Ru pincer coordination geometries. We found that mono tuck-in κ⁴-ArPN^HPRuLCl complexes react with NaN(SiMe₃)₂ producing double tuck-in mer-κ⁵-ArPN^HPRuL complexes. Interestingly, when κ⁴-MesPN^HPRuCl is dehydrohalogenated, the resulting double tuck-in complex binds N₂, forming the nitrogen complex κ⁵-MesPN^HPRuN₂. The mer-κ⁵-ArPN^HPRuL complexes thermally isomerize to the fac-κ⁵-ArPN^HPRuL isomers, which is an uncommon reaction for pincer complexes. The mer-κ⁵-ArPN^HPRuL complexes react with CO and CO₂ to form amide κ⁴-ArPN^HPRu(CO)L or carbamate κ⁵-ArPN(CO₂)PRuL complexes, respectively, supporting the hypothesis that the κ⁴-ArPNPRuL amide intermediates are accessible and reactive.