Synthesis, characterization and crystal structures of carboxy-functionalized diiron propanedithiolate complexes

Four new carboxy-functionalized diiron propanedithiolate complexes 1-4 have been successfully synthesized and fully characterized. The all-carboxyl complexes [(mu-SCH2)(2)CHCO2CH2CH2Cl][Fe-2(CO)(6)] (1) and [(mu-SCH2)(2)CHCO2C6H4I-p][Fe-2(CO)(6)] (2) were prepared by the condensation reaction of the known complex [(mu(2)-SCH2)(2)CHCO2H][Fe-2(CO)(6)] (A) with ClCH2CH2OH and p-IC6H4OH in the presence of 4-dimethylaminopyridine (DMAP) and dicyclohexylcarbodiimide (DCC) in yields of 46% and 66%, whereas the phosphine-substituted complexes [(mu-SCH2)(2)CHCO2CH2CH2Cl][Fe-2(CO)(5)PPh3] (3) and [(mu-SCH2)(2)CHCO2CH2CH2Cl][Fe-2(CO)(4)(PPh3)(2)] (4) were further synthesized through the carbonyl substitution reaction of 1 with PPh3 using the decarbonylating agent Me3NO center dot 2H(2)O in yields of 44% and 41%. The new complexes 1-4 were characterized by combustion analysis, IR and H-1, C-13 and P-31 NMR spectroscopic techniques. The molecular structures of 1-4 were unequivocally determined by single crystal X-ray diffraction analysis, in which the carboxy-functionalized substituent attached to the bridgehead-C atom resides in an equatorial position of the six-membered rings in the solid state. (C) 2013 Elsevier Ltd. All rights reserved.