Vitamin A structure

The splitting of the absorption maximum at 327 mp of vitamin A acetate into two peaks on ir-complex formation can be said to be due to a "ir-complex effect". The NMR spectrum of the compound was found to be very complex. However, it was possible to assign all strong peaks to the proposed structure by a comparison with the NMR spectrum of vitamin A acetate. The peaks due to the protons around the six-membered ring of the vitamin A structure kept their position on ir-complex formation. Therefore the six-membered ring may not participate in ir-complex formation with the iron tricarbonyl group. However, the exact location of ir -bonding in the vitamin A structure could not be determined unequivocally. 

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