. Author manuscript; available in PMC: 2010 Jan 21.

Published in final edited form as: J Am Chem Soc. 2009 Jan 21;131(2):653–661. doi: 10.1021/ja806715u

Table 2.

Calculated activation energies (enthalpy, in kcal/mol) for para-substituted ArNO and ArC≡CH at the (U)B3LYP/6-31+G(d) level (gas phase at room temperature). <S²> of the calculated transition states are 0.34–0.39.

Reactions	ΔH^‡ (kcal/mol)
p-O₂N-C₆H₄NO + PhC≡CH →	13.1
p-NC-C₆H₄NO + PhC≡CH →	13.8
p-Cl-C₆H₄NO + PhC≡CH →	15.5
p-Br-C₆H₄NO + PhC≡CH →	14.7
PhNO + PhC≡CH →	15.8
p-Me-C₆H₄NO + PhC≡CH →	16.4
p-MeO-C₆H₄NO + PhC≡CH →	17.4
p-O₂N-C₆H₄NO + p-O₂N-C₆H₄C≡CH →	13.4
p-O₂N-C₆H₄NO + p-NC-C₆H₄C≡CH →	13.3
p-O₂N-C₆H₄NO + p-Cl-C₆H₄C≡CH →	12.8
p-O₂N-C₆H₄NO + p-Br-C₆H₄C≡CH →	12.2
p-O₂N-C₆H₄NO + PhC≡CH →	13.1
p-O₂N-C₆H₄NO + p-Me-C₆H₄C≡CH →	12.6
p-O₂N-C₆H₄NO + p-MeO-C₆H₄C≡CH →	11.6