Synthesis and crystal structures of tetraethylammonium µ3-acetyl-C1-(Fe1Fe2)O(Fe1Fe3)-nonacarbonyl-triangulo-triferrate and tetraethyl-ammonium µ-carbonyl-nonacarbonyl-µ3-2,4-dioxapentylidyne-triangulo-triferrate

Abstract

The iron carbonylate anion [Fe₂(CO)₈]^2– reacts with iodomethane and with chloromethyl methyl ether to give the tri-iron cluster anions [Fe₃(CO)₉(µ₃-CH₃CO)]^–(1) and [Fe₃(CO)₉(µ-CO)(µ₃-COCH₂OCH₃)]^–(2) respectively. The structures of the cluster anions have been determined by X-ray diffraction studies of their tetraethylammonium salts. The compound [NEt₄][Fe₃(CO)₉(µ₃-CH₃CO)] is orthorhombic, space group Pna2₁, with a= 16.559(2), b= 11.986(2), c= 12.142(2)Å, and Z= 4, while [NEt₄][Fe₃(CO)₁₀(µ₃-COCH₂OCH₃)] is monoclinic, space group P2₁/n, with a= 12.806(2), b= 14.922(2), c= 15.098(2)Å, β= 105.34(2)°, and Z= 4. The structures have been solved and refined by standard procedures to R values of 0.068 and 0.080 respectively using 2 273 and 2 677 observed [I > 1.5σ(I)] diffractometer data. Possible mechanisms for the formation of the anions are considered.