Benzocyclobutadienes. 6. Two Tricarbonyliron Complexes from a Stable Benzodicyclobutadiene

Article abstract of DOI:10.1107/S0567740881006511

The reaction of a stable benzodicyclobutadiene with nonacarbonyldiiron afford a monoiron complex C45H38FeO3 <(2) M_r=682.64, triclinic, P1/, Z=2, a=10.267 (4), b=12.466 (1), c=14.756 (2) Angstroem, α=91.62 (1), β=99.84 (2), γ=76.05 (2) deg, μ(Mo Kα)=0.41 mm^-1> and a diiron complex C48H38FeO6*CH2Cl2*1/2C5H12 <(3) M_r=943.47, monoclinic, C2/c, Z=4, a=16.307 (5), b=17.749 (3), c=16.95 (1) Angstroem, β=102.93 (4) deg, μ(Mo Kα)=0.71 mm^-1>.Both structures were solved by the heavy-atom method and refined to R=0.038 and 0.063 for 5824 and 1559 diffractometer data respectively.In (2), one four-membered ring is strongly tetrahapto coordinated by an Fe(CO)3 group, as in pure cyclobutadiene complexes.This leads to a pronounced double-bond fixation in the fused benzene ring.In (3), both four-membered rings are tetrahapto coordinated but, in contrast to (2), the Fe(CO)3 groups are shifted towards the molecular periphery. (3) can be regarded as an organometallic anthracene.From the structures (2) and (3), the notation benzodicyclobutadiene for (1) seems to be justified.