- Schwabe T, Grimme S (2007) Phys Chem Chem Phys 9:3397, and references therein.
B2PLYP does have empirical parameters, albeit just two - Wennmohs F, Neese F (2008) Chem Phys 343:217
- Clark T (2000) J Mol Struct (Theochem) 530:1
- Nooijen M (2009) Adv Quant Chem 56:181
- Dewar MJS (1992). In: Seeman JI (ed) “A semiempirical life”, profiles, pathways and
dreams series. American Chemical Society, Washington, DC, p 185 - Zhao Y, Truhlar DG (2008) Theor Chem Account 120:215
- Levine IN (2000) Quantum chemistry, 5th edn. Prentice Hall, Upper Saddle River, NJ; cited
in index - Hehre WJ (1995) Practical strategies for electronic structure calculations. Wavefunction Inc,
Irvine, CA - Hehre WJ, Lou L (1997) A guide to density functional calculations in Spartan. Wavefunction
Inc, Irvine CA - Hehre WJ, Radom L, Schleyer pvR, Pople JA (1986) Ab initio molecular orbital theory.
Wiley, New York; section 6.2
70.H 2 C¼CHOH reaction:The only quantitative information on the barrier for this reaction
seems to be: Saito S (1976) Chem Phys Lett 42:399, halflife in the gas phase in a Pyrex flask
at room temperature ca. 30 minutes. From this one calculates (Chapter 5, Section 5.5.2.2d,
Eq. 5.202) a free energy of activation of 93 kJ mol"^1. Since isomerization may be catalyzed
by the walls of the flask, the purely concerted reaction may have a much higher barrier. This
paper also shows by microwave spectroscopy that ethenol has the O–H bondsynto the C¼C.
The most reliable measurement of the ethenol/ethanal equilibrium constant, by flash photol-
ysis, is 5.89. 10 "^7 in water at room temperature (Chiang Y, Hojatti M, Keeffe JR, Kresge
AK, Schepp NP, Wirz J (1987) J Am Chem Soc 109:4000). This gives a free energy of
equilibrium of 36 kJ mol"^1 (ethanal 36 kJ mol"^1 below ethenol). The accurate G3MP2
method [Chapter 5, Section 5.5.2.2b] places the gas phase free energy of ethanal 43 kJ mol"^1
below that of ethenol.HNC reaction:The barrier for rearrangement of HNC to HCN has
apparently never been actually measured. The equilibrium constant in the gas phase at room
temperature was calculated (Maki AG, Sams RL (1981) J Chem Phys 75:4178) at 3.7.
10 "^8 , from actual measurements at higher temperatures; this gives a free energy of equilib-
rium of 42 kJ mol"^1 (HCN 42 kJ mol"^1 below HNC). The G3MP2 method places the gas
phase free energy of HCN 59 kJ mol"^1 below that of HNC.CH 3 NC reaction:The reported
experimental activation energy is 161 kJ mol"^1 (Wang D, Qian X, Peng J (1996) Chem Phys
Lett 258:149; Bowman JM, Gazy B, Bentley JA, Lee TJ, Dateo CE (1993) J Chem Phys
99:308; Rabinovitch BS, Gilderson PW (1965) J Am Chem Soc 87:158; Schneider FW,
Rabinovitch BS (1962) J Am Chem Soc 84:4215). The energy difference between CH 3 NC
and CH 3 CN has apparently never been actually measured. The G3MP2 method places the
gas phase free energy of CH 3 CN 99 kJ mol"^1 below that of CH 3 NC.Cyclopropylidene
reaction:Neither the barrier nor the equilibrium constant for the cyclopropylidene/allene
reaction have been measured. The only direct experimental information of these species
come from the failure to observe cyclopropylidene at 77 K (Chapman OL (1974) Pure Appl
Chem 40:511). This and other experiments (references in Bettinger HF, Schleyer PvR,
Schreiner PR, Schaefer HF (1997) J Org Chem 62:9267 and in Bettinger HF, Schreiner
PR, Schleyer PvR, Schaefer HF (1996) J Phys Chem 100:16147) show that the carbene is
much higher in energy than allene and rearranges very rapidly to the latter. Bettinger et al.
1997 (above) calculate the barrier to be 21 kJ mol"^1 (5 kcal mol"^1 ). The G3MP2 method
places the gas phase free energy of allene 283 kJ mol"^1 below that of cyclopropylidene - Spartan is an integrated molecular mechanics, ab initio and semiempirical program with an
outstanding input/output graphical interface that is available in UNIX workstation and PC
versions: Wavefunction Inc.,http://www.wavefun.com, 18401 Von Karman, Suite 370,
Irvine CA 92715, USA - Perdew JP, Burke K, Ernzerhof M (1996) Phys Rev Lett 77:3865; Erratum: Perdew JP,
Burke K, Ernzerhof M (1997) Phys Rev Lett 78;1396
514 7 Density Functional Calculations