New ferrocene and cobaltocenium acetal and aldehyde containing compounds have been prepared. The acid catalysed condensations of both metallocene bis(aldehydes) (5, 6) with 1,3-dihydroxybenzene yielded complex products. The new metallocene cyclic monoaldehydes (7, 8), differed markedly in their reactions with 1,3-dihydroxybenzene with the ferrocene derivative 8 producing [1 + 1] and [1 + 2] bisphenol: aldehyde adducts, whereas the cobaltocenium analogue gave a cyclic diene compound (16). A single crystal X-ray structure of 16 is also described and the electrochemical properties of some of the new metallocene derivatives reported.
