Abstract
The 13C n.m.r. chemical shifts of several 2-substituted indenes are reported and the induced substituent shieldings of the remote proton-bearing aromatic carbons are analysed by a multivariate data analysis method. A dual parameter model is necessary to describe the shift variations and the two components obtained were found to correlate to a mesomeric σR° and field–inductive σI scale, respectively. The two dual parameter models are tested on a structurally similar heterocyclic system. The limitations of multiparameter equations in predicting 13C chemical shifts and in separating electronic effects are briefly discussed.

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