Diferrocenyl(methylthio)cyclopropenylium iodide reacts with organometallic compounds (methyllithium, benzyl-and ethylmagnesium chlorides, and allylmagnesium bromide) to yield 2,3-diferrocenyl-1-methylthio-1,3-dienes or -1,3,5-triene together with 3,3-dialkyl-1,2-diferrocenylcyclopropenes.

Alkylation of ferrocene with tetrachlorocyclopropene in the presence of AlCl 3 followed by aqueous workup affords 2,3-diferrocenylcyclopropenone in high yield. We have studied some of this ketone's chemical transformations and electrochemical properties. 2,3-Diferrocenylcyclopropenone withstands thermolysis; it is stable in an acidic medium; the action of tetrafluoroboric acid−diethyl ether results in the formation of diferrocenyl(hydroxy)cyclopropenylium tetrafluoroborate; nucleophiles, including methyllithium and lithium aluminum

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Reactions of 2,3-diferrocenylcyclopropenone 1 with ethyl- and benzylmagnesium chlorides afford 3,3-diethyl-and 3,3-dibenzyl- 1,2-diferrocenylcyclopropenes 2 and 3, respectively, and products of nucleophilic opening of the three-membered ring resulting from the addition of RMgCl to the carbonyl group, viz., saturated ketones(4,5-diferrocenylheptan-3-ones 4a,b and 3,4-diferrocenyl-1,5-diphenylpentan-2-ones 5a,b as ca. 3: 1 mixtures of two diastereomers) and other products. The spatial structures of compounds 2 and 4a were established by X-ray diffraction analysis of single crystals. Protonation of the cyclopropenes 2 and 3 with tetrafluoroboric acid at -40 degrees C yields the corresponding 3,3-dialkyl-1 ,2-diferrocenylcyclopropylium tetrafluoroborates. Transformation of the latter into diferrocenylallylic cations upon increasing the temperature to 20 degrees C and their eprotonation under the action of N,N-dimethylaniline were studied. Electrochemical investigation of 1 and 2 shows that in both complexes the cyclopropene spacer allows electronic communication between the two outer ferrocenyl groups, this being notably greater for 2 than for 1.

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