Synthesis and spectroscopic characterisation of compounds with formula [{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}] and [{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2] (n=3, 4 and 6)

This work describes the synthesis and characterisation of the title compounds. This is the second in a series of reactions involving iron bis-phosphine cluster compounds [{Fe3(CO)11}Ph2P(CH2)nPPh2{Fe(CO)4}] and [{Fe3(CO)11}2Ph2P(CH2)nPPh2] (n=3, 4 and 6). Here, the iron bis-phosphine cluster compounds are reacted with stoichiometric amounts of diphenyldisulphide (Ph2S2) in toluene at 65–70 °C for 30 min. The reactions afforded three products regardless of the n-value. Irrespective of the iron-containing reagent, one product is common to all reactions. A total of seven different compounds were isolated, six of which are new. The product formulations are: 1. the known compound [Fe2(SPh)2(CO)6] (common product); 2. [{Fe2(SPh)2(CO)5}Ph2P(CH2)nPPh2{Fe(CO)4}]; and 3. [{Fe2(SPh)2(CO)5}2Ph2P(CH2)nPPh2], (n=3, 4 and 6). Yields ranged 2–37% depending on the particular reactions. Reactions involving the {Fe3Fe} type species with [Ph2S2] (1:1 or 1:2 mole ratio) afforded predominantly phosphine sulphur compounds type (ii) above, whereas, when the {Fe3Fe3} type species were reacted (1:2 or 1:4 mole ratio), the major products were of type (iii) above.