Synthesis and spectroscopic characterisation of compounds with formula [{Fe2S2(CO)(5)}Ph2P(CH2)(n)PPh2{Fe(CO)(4)}] and [{Fe2S2(CO)(5)}(2)Ph2P(CH2)(n)PPh2] (n=3, 4 and 6)

The work described herein concerns the synthesis and characterisation of co mpounds with formula [{Fe2S2(CO)(5)}-Ph2P(CH2)(n)PPh2{Fe(CO)(4)}] and [{Fe2 S2(CO)(5)}(2)Ph2P(CH2)(n)PPh2] (n = 3, 4, 6). The iron bis-phosphine cluste r compounds with formula [{Fe-3(CO)(11)}(2)Ph2P(CH2)(n)PPh2] and [{Fe-3(CO) (11)}Ph2P(CH2)(n)PPh2{Fe(CO)(4)}] (n = 3, 4, 6)] were reacted with stoichio metric amounts of cyclohexene episulfide [SC6H10] in toluene at 70 degrees C for 30-60 min. Optimum yields of 42.1-78.2%, were obtained for {Fe2S2-Fe} type species when a 1:4 cluster-ligand mole ratio was used, while the {Fe2 S2}(2) type species were prepared in yields of 30-38% when a 1:8 cluster-li gand mole ratio was used. The volume of reaction solvent was kept to a mini mum. For the latter cluster compounds, three isomeric products were isolate d from each reaction; a justification for their presence is offered. All of these reactions afford clusters with fewer iron atoms but with S atoms inc orporated. In these reactions the Fe-3-unit is 'degraded' but at the same t ime the cluster is expanded from three atoms {Fe-3} to four {Fe2S2}. (C) 20 00 Elsevier Science S.A. All rights reserved.