An investigation of the reaction between [{Fe(η5–C5H5)(CO)2}2] and aryl isonitriles

Abstract

The direct reaction between [{Fe(η5-C5H4X)(CO)2}2](X = H, Me, or COOMe) and aryl isonitriles RNC (R = 2,6-Me2C6H3 or C6H5) in refluxing toluene readily yields the tetrasubstituted derivatives [{Fe(η5-C5H4X)(RNC)2}2]. The intermediate derivatives [Fe2(η5-C5H5)2(CO)4–n(RNC)n](n= 1 or 2) can be prepared by the exchange reaction between [{Fe(η5-C5H5)(RNC)2}2] and [{Fe(η5-C5H5)(CO)2}2]. Reaction rates for the substitution of [{Fe(η5= C5H5X)(CO)2}2] by RNC are dependent on both the nature of R and X, and increase with both the nucleophilicity of R and the electron-withdrawing power of X. An alternative route to [Fe2(η5-C5H5)2(CO)4–n(RNC)n](n= 1 or 2) is via the reaction between Na[Fe(η5-C5H5)(CO)2] and 2,6-Me2C6H3NC in the presence of C7H7+BF4–. The isonitrile complexes have been characterized by i.r. and n.m.r. spectroscopy.