HYDROGEN SHIFTS IN FORMYLPHOSPHINE AND DIFORMYLPHOSPHINE

The energetics of the [1,3]-hydrogen shift in formyl and diformylphosp hine are determined at MP4SDQ/6-31G*//MP2/6-31G** + ZPE(HF/6-31G**). These results are compared to the [1,3]-hydrogem shift in acetaldehyde and malonaldehyde. The keto forms of formylphosphine and acetaldehyde are more stable than the corresponding enol forms, by 7.01 and 14.93 kcal mol(-1), respectively. The activation energy for the antarafacial TS for the phosphine systems is approximately 20 kcal mol(-1) lower t han the carbon systems. The enol form of diformylphoshine having an in tramolecular hydrogen bond is 0.79 kcal mol(-1) more stable than the d iketo form. The activation barrier for the [1,5]-hydrogen shift in the intramolecular hydrogen-bonded enol form of diformylphosphine is 1.5 kcal mol(-1) lower than in malonaldehyde. Conformational analysis show s the intramolecular hydrogen bonded enol for diformylphosphine and ma lonaldehyde to be at least 6 kcal mol(-1) more stable than the other c onformers.