Table 2 Comparison of ∆E1 and ∆E2 values of acetylene hydro- thiolation and selenation reactions
NHC catalyst Hydrothiolation Hydrothiolation Hydroselenation Hydroselenation
∆E1 (kcal/mol) ∆E2 (kcal/mol) ∆E1 (kcal/mol) ∆E2 (kcal/mol)
IH 9.53 33.06 4.13 28.66
IMe 4.80 16.83 1.81 14.75
INH2 6.43 15.40 4.20 15.66
ICN 20.33 45.99 13.91 43.53
IOH 14.80 35.45 9.41 33.49
IOMe 12.55 34.20 6.99 31.85
ISH 11.15 23.11 6.23 23.30
ISMe 9.15 20.34 4.48 19.92
BH 12.93 37.92 6.01 34.45
BMe 5.78 33.37 2.49 29.16
TH 3.67 33.94 0.74 30.94
TMe 1.62 32.56 0.17 29.35
PH# 4.85 33.14 1.48 35.56
PMe# 2.33 31.30 0.57 29.07
# implies values are computed at B3LYP/6-31+G(d) level # implies values are computed at B3LYP/6-31+G(d) level # implies values are computed at B3LYP/6-31+G(d) level # implies values are computed at B3LYP/6-31+G(d) level # implies values are computed at B3LYP/6-31+G(d) level