A NEW CLASS OF DIIRON ARENE COMPLEXES WITH DISULFIDE AND DIAMINE BRIDGES

The synthesis and characterization of a new class of bis(cyclopentadienyliron) arene complexes of disulfides and diamines with aliphatic and aromatic bridges are presented. Reactions of the aromatic or aliphatic dithiols with a wide range of cyclopentadienyliron complexes of chloroarenes (1a-i), in the presence of potassium carbonate in a 4:1 THF/DMF mixture, led to the formation of the dicationic iron species (3a-k, 7a-s) in high yields. The synthesis of diiron systems with ether/thioether linkages was also found to be successful. In these reactions, 4-hydroxythiophenol (4) was used as an example with various chloroarene complexes to give the bis(cyclopentadi-enyliron) arene dications with ether/thioether bridges (5a-f). Reactions of chloroarene complexes (1a,g) with 1,6-hexanediamine (8a) resulted in the formation of the diiron complexes 9a,b in very poor yields (28 and 17%, respectively). However, the use of nitroarene complexes (11a-f) as starting materials proved to increase the reaction yields and decreases the reaction time, which minimized product decomposition in the preparation of complexes 9a and 12a-n. The change in the number of methylene groups of the aliphatic diamines from 2 to 6 resulted in an increase in the product yield. Aromatic diamine bridges were also introduced to yield complexes 14a-e in a similar fashion. The proposed synthetic strategy allowed for the synthesis of a larger number of diiron complexes with various heteroatom linkages, while the traditional route to similar complexes (ligand-exchange reaction of ferrocene with the appropriate aromatic compound) proved to be unsuccessful in terms of yield and versatility.