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

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

Isomers of C3H3

index Species CAS number Name Relative experimental enthalpy (kJ mol-1) sketch
a C3H3+ 2932787 Propargyl cation   sketch of Propargyl cation
b C3H3+ 9000220 cyclopropenyl cation   sketch of cyclopropenyl cation
The calculated enthalpies include the calculated and scaled vibrational zero-point energy.
Methods with predefined basis sets
semi-empirical AM1 1253.7 a
PM3 1259.8 a
PM6 1173.7 a
1122.8 b
composite G1 NC
NC
G2MP2 NC
NC
G2 NC
NC
G3 NC
NC
G3B3 NC
NC
G3MP2 NC
NC
CBS-Q NC
NC
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.