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Table 1

Energetics: ΔE with ZPE correction and ΔG calculated at 15 K as obtained from MP2/aug-cc-pVTZ//CCSD(T)/aug-cc-pVTZ calculations.

Reaction ΔE (kcal/mol) ΔG (kcal/mol) Ea (kcal/mol)
Ion-molecule

(1) NH3 + CONH → UreaH+ –50.48 –50.30 (–7.82)a
(2) NH + HNCO → UreaH+ –20.31 –20.14 (23.15)a
(3) NH3OH+ + HCONH2 → UreaH+ + H2O –71.60 –70.10 17.60
(4) NH2OH + HCONH2 → UreaH+ + H2O –97.40 –97.30 –8.04
(5) NH2OH + HCOHNH → UreaH+ + H2O –70.49 –70.40 18.80
(6) NH + HCONH2 → UreaH+ + H2 –4.89 –4.73 85.18
(7) NH3 + HCOHNH → UreaH+ + H2 –12.41 –12.26 77.66
(8) CH3NH2 + HCOHNH → UreaH+ + CH4 –35.47 –35.44 70.58
(9) CH3NH + HCONH2 → UreaH+ + CH4 –16.94 –16.89 89. 13

Neutral-neutral

(10) NH3 + HNCO → Urea –14.78 –14.64
(11) NH2OH + HCONH2 → Urea + H2O –57.46 –57.38 60.26
(12) NH3 + HCONH2 → Urea + H2 0.61 0.75
(13) CH3NH2 + HCONH2 → Urea + CH4 –22.44 –22.79

Radical

(14) NH2⋅ + HCONH2 → Urea + H⋅ –1.84 –1.65 16.22
(15) NH3 + HCONH⋅ → Urea + H⋅ –11.76 –11.65 6.18

Notes: Activation energies, Ea (with ZPE correction), as obtained at the same level of theory for the different path investigated are shown. When a pathway was not characterized (see text) it is marked with –. For UreaH+ we report the energy formation for the most stable isomer. (a) Values as from Spezia et al. (2009).

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