Crystal and molecular structure of the compound formed from tetracyanoethylene and tricarbonyl(cycloheptatriene)iron: a novel 2,3,4,9-tetrahapto-bonded system
Published 1971 · J. Weaver, P. Woodward
Journal of The Chemical Society A: Inorganic, Physical, Theoretical
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Abstract
The compound formed from tricarbonyl(cycloheptatriene)iron and tetracyanoethylene contains a bicyclononane system. Crystals of this compound are triclinic, a= 12·18, b= 9·05, c= 7·38 A, α= 107° 16′, β= 82° 19′, γ= 88° 20′, space group P, with two centrosymmetrically related molecules in the unit cell. The structure has been determined by conventional heavy-atom methods from diffractometer data and refined to R 0·081 for 885 independent reflections. The Fe(CO)3 group is bonded to the seven-membered ring via a novel four-electron donor system: C-2, C-3, and C-4 comprise a π-allyl group, while atom C-9 is σ-bonded to the iron atom. The tetracyanoethylene links to the cycloheptatriene ring at C-1 and C-6 to form a new five-membered ring system of ‘envelope’ conformation exo to the Fe(CO)3 group. The configuration around the iron atom is approximately octahedral, and the mean Fe–C and C–O distances for the three carbonyl groups are 1·75(3) and 1·19(2)A.