Cyclobutadiene–metal complexes. X. Reactions of tetramethylcyclobutadienenickel chloride with iron carbonyls

Tetramethylcyclobutadieneiron tricarbonyl has been obtained in 25–37% yield from the reaction of triiron dodecacarbonyl with either 3,4-dichlorotetramethylcyclobutene or tetramethylcyclobutadienenickel chloride dimer. The latter reaction also gave small amounts of another complex, Me8C8NiFe(CO)3. The reaction of [Me4C4NiCl2]2 with iron pentacarbonyl gave Me4C4Fe(CO)3 together with two other complexes. The structures of these new complexes are discussed in the light of their nuclear magnetic resonance, mass, and infrared spectra.