TY - JOUR
T1 - Photoelectron Spectroscopy of the Aminomethoxide Anion, H2C(NH2)O–
AU - Oliveira, Allan M.
AU - Lehman, Julia H.
AU - Lineberger, W. Carl
PY - 2018/6/7
Y1 - 2018/6/7
N2 - We report the photoelectron spectrum of the aminomethoxide anion (H2C(NH2)O–). The electron affinity (EA) of the aminomethoxy radical is determined to be 1.944(1) eV. Transitions to the ground (X̃ 2A″) and first excited (Ã 2A′) electronic states of aminomethoxy are observed, with the term energy measured to be T0(Ã ← X̃) = 0.085(1) eV. A long vibrational progression is observed for the transition to the ground X̃ 2A″ electronic state of aminomethoxy, primarily consisting of OCN bending and HNH wagging vibrations, leading to the assignment of these two fundamental vibrational frequencies of H2C(NH2)O· X̃ 2A″. The gas-phase acidity of aminomethanol is calculated at the G4 level of theory to be ΔacidH0Ko = 374.0 kcal mol–1, which, when combined with the experimental EA of aminomethoxy in a thermochemical cycle, provides a determination of the O–H bond dissociation energy, D0(H2C(NH2)O–H) as 106(2) kcal mol–1. Comparisons of the EAs and T0(Ã ← X̃) for the aminomethoxy, methoxy, ethoxy, and hydroxymethoxy radicals provides insight into how the substituent group affects the electronic structure of singly substituted alkoxy radicals.
AB - We report the photoelectron spectrum of the aminomethoxide anion (H2C(NH2)O–). The electron affinity (EA) of the aminomethoxy radical is determined to be 1.944(1) eV. Transitions to the ground (X̃ 2A″) and first excited (Ã 2A′) electronic states of aminomethoxy are observed, with the term energy measured to be T0(Ã ← X̃) = 0.085(1) eV. A long vibrational progression is observed for the transition to the ground X̃ 2A″ electronic state of aminomethoxy, primarily consisting of OCN bending and HNH wagging vibrations, leading to the assignment of these two fundamental vibrational frequencies of H2C(NH2)O· X̃ 2A″. The gas-phase acidity of aminomethanol is calculated at the G4 level of theory to be ΔacidH0Ko = 374.0 kcal mol–1, which, when combined with the experimental EA of aminomethoxy in a thermochemical cycle, provides a determination of the O–H bond dissociation energy, D0(H2C(NH2)O–H) as 106(2) kcal mol–1. Comparisons of the EAs and T0(Ã ← X̃) for the aminomethoxy, methoxy, ethoxy, and hydroxymethoxy radicals provides insight into how the substituent group affects the electronic structure of singly substituted alkoxy radicals.
UR - https://doi.org/10.1021/acs.jpca.8b02921
U2 - 10.1021/acs.jpca.8b02921
DO - 10.1021/acs.jpca.8b02921
M3 - Article
SN - 1089-5639
VL - 122
SP - 4954
EP - 4962
JO - The Journal of Physical Chemistry A
JF - The Journal of Physical Chemistry A
IS - 22
ER -