Crystal and molecular structure of benzophenone azine: evidence for an Fe(II) carbene intermediate

Article abstract of DOI:10.1007/BF01665274

Benzophenone azine crystallizes in the monoclinic space group A2/a (No. 15) with a=16.303(3) Angstroem, b=5.4864(2) Angstroem, c=21.973(5) Angstroem, β=85.52(2)deg, V=1959.4(8) Angstroem³, and D_calc=1.22 g cm^-3 for Z=4.The structure was solved by direct methods and refined against F to a final R value of 0.047.The unit cell contains four molecules of the title compound; the asymmetric unit consists of half a molecule.Despite the high crystallographic symmetry, the two halves of the molecule are not related by a center of symmetry; instead, the molecule adopts C² symmetry; the molecular C² axis is coincident with the crystallographic twofold axis.The formation of benzophenone azine from the reaction of the iron-containing Lewis acid complex <(η⁵-C5H5)Fe(CO)2(THF)>^{+ -} and diphenyldiazomethane provides strong evidence for an Fe(II) carbene intermediate.KEY WORDS: Azine; azitine; iron(II) carbene; catalyst.