Trinuclear iron carbonyl complexes of the non-benzenoid tricyclic hydrocarbon aceheptylene: Relationship to heptalene metal complexes

The lowest energy (aceheptylene)Fe3(CO)8 structure is the experimental structure with separate (diene)Fe(CO)3 and (azulene)Fe2(CO)5 subunits. The lowest energy (aceheptylene)Fe3(CO)9 precursor to this experimental structure has three separate (diene)Fe(CO)3 subunits and an uncomplexed CC double bond. Related (heptalene)Fe3(CO)n (n = 9, 8) structures are also optimized and suggested to be viable species.