Studies in the cycloproparene series. the formation of charge-transfer complexes from 1-aryl- and 1-diarylmethylidene-1H-cyclopropa[b]naphthalenes

The only charge-transfer (CT) complex formed from (p-dimethylaminophenyl) methylidene-1H-cyclopropa[b]-naphthalene 7a is with 2,3-dichloro-5,6-dicyano-1, 4-benzoquinone (DDQ) 1 in acetonitrile. The methoxy-, thiomethyl-, and unsubstituted-phenyl analogues 7b-7d complex only with 2,3,5,6-tetrafluoro-7,7, 8,8-tetracyano-1,4-benzoquinodimethane (TCNQF) 2, and then only in dichloromethane; TCNQ 3, TCNE 4, and the o-CA 5 and p-CA 6 are without effect on any of 7a-7j. In contrast, the bis(dimethylaminophenyl)methylidene homologue 9a complexes with each of 1-5 but is the only diaryl derivative to do so. The polar parent, 1H-cyclopropa[b]naphthalene, does not form a CT complex with any of the acceptors employed. © CSIRO 2005.