Abstract: There are described compounds of formula I, ##SPC1##in which R is alkyl, chlorine, bromine, phenyl, or phenyl substituted by one or more halogen or alkyl groups,One of X and Y is group --CO--, --CHOH-- or --CH.sub.2 -- and the other is an exocyclic carbon-carbon bond linking the ferrocenyl or the R group respectively to the -A- group,A contains 5, 6 or 7 carbon atoms and is an ethylenically unsaturated (the double bond being connected to the carbon atom which is connected to X), unsubstituted (except by X and Y) cyclic hydrocarbon group; or is a saturated cyclic hydrocarbon group substituted by X and Y and, when X is a group --CO-, optionally substituted on the carbon atom to which Y is attached by an -OH group, andX and Y are attached to adjacent carbon atoms on the A group. There are also described processes for the production of compounds of formula I and haematinic compositions containing them.