title: Quantum Chemical Investigation of the Transition States and Intermediates for the Reaction of the Nitrosonium Ion with the Pentaammineazidocobalt(III) Ion.
abstract: The water exchange reaction on Co(NH3)5OH23+was investigated with various density functionals and basis sets. A Gibbs activation energy (ΔG⧧) agreeing with experiment was obtained with the long-range-corrected functionals ωB97X-D3 and LC-BOP-LRD, SMD hydration, and modified Karlsruhe def2-TZVP basis sets. This computational technique was then applied to the reaction of NO+with Co(NH3)5N32+. All of the possible pathways were investigated, NO+attack at the terminal N of Co(NH3)5N32+via the E and the Z isomers of the transition states, and NO+attack at the bound N of azide, also via both isomers. The most favorable pathway proceeds via the attack at the bound N via the Z isomer. This leads to the intermediate with an oxatetrazole ligand bound to Co(III) at the N in the 3-position, Co(NH3)5(cycl-N4O)3+, which undergoes N2elimination to yield the Co(NH3)5N2O3+intermediate. The subsequent substitution of N2O by water follows the Idmechanism with retention of the configuration. No evidence for the existence of the square-pyramidal pentacoordinated intermediate Co(NH3)53+was found. All of the investigated intermediates, Co(NH3)5N23+, Co(NH3)5[E-N(N2)(NO)]3+, Co(NH3)5(E-ON4)3+, Co(NH3)5ON23+, Co(NH3)5(cycl-N4O)3+, and Co(NH3)5N2O3+, exhibit short lifetimes of less than ∼60 μs and react via the Idmechanism.
authors.affiliation: Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL) , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: François P
authors.identifier: http://orcid.org/0000-0001-8759-4427
authors.initials: FP
authors.lastname: Rotzinger