An abinitio molecular orbital theory study of the structure and stability of the hydrogen bridged radical cation molecule pairs [CH2CHOHOH2]+ and [CH2CHOHOHCH3]+

Abinitio molecular orbital theory was used to determine if C 2 H 6 O 2 +• and C 3 H 8 O 2 +• radical cations represented as hydrogen bridged radical cation molecular pairs, viz. [Formula: see text] and [Formula: see text] can be expected to exist as stable species in the gas phase.The use of several basis sets was explored at the SCF level and it was found that the above species have appreciable stabilisation energies with respect to dissociation into CH 2 =CHOH +• and H 2 O or CH 3 OH. Using a 6-31**/4-31G basis set and applying BSSE (Basis Set Superposition Error) corrections, respective stabilisation energies of 88 kJ/mol and 84 kJ/mol were calculated. Preliminary calculations further indicate that conversion barriers towards isomeric structures are high and thus ions of this type may well have been observed by experiment. Several reaction profiles have been calculated at the STO-3G level and at the 4-31G level, which show that the ions can exist in a syn and an anti conformation having comparable energies, their interconversion barrier being small.The structure parameters and stabilisation energies for these two hydrogen bridged ions are similar to those of the well known class of even electron species, usually designated as proton bound dimers.