Gas-Phase Generation of Phenylnitrene Anion Radical - Proton Affinity and ΔHf0 of PhN-. and Its Clustering with ROH Molecules

Article abstract of DOI:10.1021/ja00412a011

Phenylnitrene anion radical (PhN^-.) was prepared in a flowing afterglow apparatus by dissociative electron attachement of phenyl azide (PhN3).PhN^-. undergoes a very slow reaction with PhN3, producing PhN4Ph^-. and PhN2Ph^-. in a ratio of 4:1.The proton affinity pf PhN^-. was bracketed from kinetic studies with various potential proton donors, PA(PhN^-.) = 372 +/- 2 kcal mol^-1, from which ΔH_f⁰(PhN^-.) = 60 +/- 2 kcal mol ^-1 was calculated.With alcohols which are too weakly acidic to directly protonate PhN^-. , a sequence of bimolecular reactions is observed involving ROH; PhN^-. -> PhN^-.(HOR) -> PhNH^. + RO^-(HOR) -> RO^-(HOR)x.Although the first step of the sequence is slow, the second step, a cluster-to-cluster transformation, is fast.The related reaction sequence of PhN^-. reacting with HOH involves the ions PhN^-. -> PhN^-.(HOH) -> PhN^-.(HOH)2 -> PhNH^. + HO^-(HOH)2 -> HO^-(HOH)x with the third reaction as the fast step.The relationship of these sequential processes to acidities and basicities found in solution is discussed.Of the five observed reaction channels for PhN^-. with CH3CN, the major channel yields the adduct m/z 132 and a minor channel produces the M-1 species, m/z 131.Additions by PhN^-. to C_α or N or CH3CN are considered to account for these product anions.The reaction of PhN^-. with (CH3)3CCN also yields its adduct.