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IV.A.4. (XIV.F.)

Relative enthalpies of isomers - Comparison of 298.15K enthalpies (kJ mol-1)

Isomers of C6H4F2

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C6H4F2 372189 metadifluorobenzene 0.0 sketch of metadifluorobenzene
b C6H4F2 540363 1,4-difluorobenzene 2.5 sketch of 1,4-difluorobenzene
c C6H4F2 367113 orthodifluorobenzene 26.2 sketch of orthodifluorobenzene
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1 0.0 a
-0.4 b
5.8 c
PM3 0.0 a
0.2 b
1.0 c
PM6 0.0 a
-205.2 b
composite G1 0.0 a
240.5 b
253.3 c
G2MP2 0.0 a
241.2 b
253.7 c
G2 0.0 a
241.3 b
254.0 c
G3 0.0 a
240.4 b
253.4 c
G3B3 0.0 a
2.5 b
15.3 c
G3MP2
NC
NC
G4
NC
NC
CBS-Q 0.0 a
17.8 b
51.7 c

Methods with standard basis sets
NC = not calculated
For descriptions of the methods (AM1, HF, MP2, ...) and basis sets (3-21G, 3-21G*, 6-31G, ...) see the glossary in section I.C. Predefined means the basis set used is determined by the method.
gaw refers to the group additivity method implemeted in the NIST Chemistry Webbook.

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.