Molecular structure determinations of BF3‐tetralone complexes by NMR spectroscopy

Abstract The 13 C NMR shielding effects of the carbonyl‐BF 3 interaction for a series of methyl‐ and methoxy‐tetralones were determined. Once the conformations of the complexes have been defined, the major shift data which can be related to charge density changes can be qualitatively discussed in terms of the transmission of the electronic properties of the CO:BF 3 group. Complexation mainly causes a reorganization of the conjugated π‐system via a resonance mechanism. Delocalization of the π‐electrons towards the BF 3 electron‐withdrawing group increases the carbonyl reactivity of the base, while complex stability is favoured.