A study of the aminomethyl radical CH2NH2 by vacuum UV photoelectron spectroscopy and ab initio molecular orbital calculations

Dyke, John M.; Lee, E.P.F.; Niavaran, M. Hadi Zamanpour

doi:10.1016/0168-1176(89)80044-8

Cited by 20 publications

(14 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such an expectation is consistent with all of the experimental observations, namely: (i) the TKER spectra obtained at the longest excitation wavelength (figure 4a) indicates some formation of CH 3 NH(X) fragments with no internal excitation, but the majority are formed with E int 0; (ii) the separations (ca. 900 cm −1 ) of the 'steps' apparent in the TKER spectra recorded at the longer excitation wavelengths are consistent with that expected for the in-plane HNC bending vibration in the CH 3 NH fragment (Dyke et al 1989)-a mode which, on Franck-Condon grounds and by analogy with NH 3 photolysis, we would expected to be active during the dissociation process; and (iii) the proportion of internally 'cold' fragments declines as the excitation energy increases (see figure 4).…”

Section: Resultssupporting

confidence: 85%

Near ultraviolet photolysis of ammonia and methylamine studied by H Rydberg atom photofragment translational spectroscopy

Ashfold

Dixon

Kono

et al. 1997

Philosophical Transactions of the Royal Society of London. Seri

View full text Add to dashboard Cite

H(D) Rydberg atom photofragment translational spectroscopy has been used to provide new insights into the primary photochemistry of methylamine, ammonia and various of their respective isotopomers following excitation at wavelengths in the near ultraviolet (UV). The bimodal appearance of the total kinetic energy release (TKER) spectra associated with H atom production in the near UV photolysis of methylamine is consistent with there being both 'dynamical' (high TKER) and 'statistical' (slower) contributions to the total H + CH 3 NH dissociation yield. Both contributions arise as a result of one H atom tunnelling through (or passing over) an earlier barrier in the N-H dissociation coordinate of theÃ state potential energy surface and then evolving into the region of the conical intersection connecting thẽ A state and ground-state surfaces. 'Dynamical' energy disposal is associated with those molecules which pass directly through this conical intersection en route to the ground-state (H + CH 3 NH(X)) asymptote, whilst the 'statistical' contribution is attributed to those molecules that 'miss' the conical intersection on the first traversal and only make theÃ →X transfer on a later encounter. This interpretation has inspired further consideration of the form of the TKER spectra derived from TOF measurements of the H/D atom products arising in the dissociation of various isotopomers of ammonia following excitation to the 0 0 and 2 1 levels of their respectivẽ A states. A similar model which associates 'dynamical' energy disposal with those molecules that pass through theÃ/X conical intersection during bond extension, and 'statistical' kinetic energy release with those that transfer during N-H(D) bond compression, appears to provide a qualitative explanation for the way the observed H and/or D atom yields and their associated TKER spectra vary with excitation wavelength (0 0 versus 2 1 0 band excitation) and isotopic composition.

show abstract

Section: Resultssupporting

confidence: 85%

Near ultraviolet photolysis of ammonia and methylamine studied by H Rydberg atom photofragment translational spectroscopy

Ashfold

Dixon

Kono

et al. 1997

Philosophical Transactions of the Royal Society of London. Seri

View full text Add to dashboard Cite

show abstract

“…A facile 1, 2-hydrogen atom shift in CH 3 NH + provides a plausible pathway for producing triplet state CH 2 NH 2 + . The first attempt to assess the structures and energies of the relevant CH 3 NH + and CH 2 NH 2 + species was carried out by Dyke and co-workers 32 in photoelectron spectroscopy experiments on the two distinct radical species formed when fluorine atoms abstract a hydrogen atom from methylamine, CH 3 NH 2 . Quantum chemical calculations at the SCF/CI level showed that the species ionized in this experiment was a singlet aminomethyl radical, CH 2 NH 2 , with an adiabatic ionization potential of 6.29 eV.…”

Section: Resultsmentioning

confidence: 99%

Ion imaging study of reaction dynamics in the N+ + CH4 system

Farrar

2012

The Journal of Chemical Physics

View full text Add to dashboard Cite

The velocity map ion imaging method is applied to the ion-molecule reactions of N(+) with CH(4). The velocity space images are collected at collision energies of 0.5 and 1.8 eV, providing both product kinetic energy and angular distributions for the reaction products CH(4)(+), CH(3)(+), and HCNH(+). The charge transfer process is energy resonant and occurs by long-range electron transfer that results in minimal deflection of the products. The formation of the most abundant product, CH(3)(+), proceeds by dissociative charge transfer rather than hydride transfer, as reported in earlier publications. The formation of HCNH(+) by C-N bond formation appears to proceed by two different routes. The triplet state intermediates CH(3)NH(+) and CH(2)NH(2)(+) that are formed as N(+)((3)P) approaches CH(4) may undergo sequential loss of two hydrogen atoms to form ground state HCNH(+) products on a spin-allowed pathway. However, the kinetic energy distributions for formation of HCNH(+) extend past the thermochemical limit to form HCNH(+) + 2H, implying that HCNH(+) may also be formed in concert with molecular hydrogen, and requiring that intersystem crossing to the singlet manifold must occur in a significant (~25%) fraction of reactive collisions. We also report GAUSSIAN G2 calculations of the energies and structures of important singlet and triplet [CNH(4)(+)] complexes that serve as precursors to product formation.

show abstract

“…Dyke et al, provided an experimental value for the enthalpy of formation of gas phase methyleneiminium (

{CH}_{2} {NH}_{2}^{+}

) of 755 kJ/mol . An experimental

Δ H_{f}^{0}

value of 745 kJ/mol was re‐evaluated to 752 kJ/mol by Hammerum and Solling .…”

Section: Computational Methods and Reliabilitymentioning

confidence: 99%

Computational estimates of thermochemistry and pK_avalues of cyclopropenyl imine superbases

Çiftçioğlu

Trindle

2013

Int. J. Quantum Chem.

View full text Add to dashboard Cite

The thermochemical properties of superbase species derived from cyclopropeneimine are estimated by computations on systems of isodesmic reactions. Proton affinities, gas phase basicities, and pK a values are well represented by computations incorporating G4 and CBS-QB3 schemes augmented for large systems by DFT calculations with functionals M06-2X and xB97DX in the cc-pVTZ Dunning basis. Our calculations show that relative base strengths in gas are enhanced by alkyl substitution, either by methyl groups or larger species. For acetonitrile solution, alkyl substitution seems to weaken the base.

show abstract

A study of the aminomethyl radical CH2NH2 by vacuum UV photoelectron spectroscopy and ab initio molecular orbital calculations

Cited by 20 publications

References 42 publications

Near ultraviolet photolysis of ammonia and methylamine studied by H Rydberg atom photofragment translational spectroscopy

Near ultraviolet photolysis of ammonia and methylamine studied by H Rydberg atom photofragment translational spectroscopy

Ion imaging study of reaction dynamics in the N+ + CH4 system

Computational estimates of thermochemistry and pK_avalues of cyclopropenyl imine superbases

Contact Info

Product

Resources

About

A study of the aminomethyl radical CH2NH2 by vacuum UV photoelectron spectroscopy and ab initio molecular orbital calculations

Cited by 20 publications

References 42 publications

Near ultraviolet photolysis of ammonia and methylamine studied by H Rydberg atom photofragment translational spectroscopy

Near ultraviolet photolysis of ammonia and methylamine studied by H Rydberg atom photofragment translational spectroscopy

Ion imaging study of reaction dynamics in the N+ + CH4 system

Computational estimates of thermochemistry and pKavalues of cyclopropenyl imine superbases

Contact Info

Product

Resources

About

Computational estimates of thermochemistry and pK_avalues of cyclopropenyl imine superbases