The potential surfaces of diphenylcarbene and phenylcarbene, in singlet and triplet states, have been studied by using the AM1 molecular orbital method. The triplet was found to be the ground state in both cases. The energy difference between the triplet and singlet surfaces is calculated to be somewhat higher than that required by a mechanism for reaction of triplet I with methanol via a thermally populated singlet state. The electron affinity of I was calculated to be quite large (43.2 kcal/mol), suggesting the possibility of a mechanism involving electron transfer from methanol to I. The characteristics of suberanyl and suberenyl carbenes were calculated for comparison. © 1989, American Chemical Society. All rights reserved.