Über das [C₇H₇Fe₂(CO)₅]^--Anion (C₇H₇ = Cycloheptatrienyl) / About the [C₇H₇Fe₂(CO)₅]^--Anion (C₇H₇ = Cycloheptatrienyl)

Abstract

Abstract The extremely unstable anionic complex [C 7 H 7 Fe 2 (CO) 6 ] - (C 7 H 7 = cycloheptatrienyl) which decomposes in polar solvents under CO elimination to give [C 7 H 7 Fe 2 (CO) 5 ] - can be prepared by deprotonation of C 7 H 8 Fe 2 (CO) 6 (C 7 H 8 = cycloheptatriene) with NaN(SiMe 3 ) 2 in C 6 H 6 .The NMR spectra of [C 7 H 7 Fe 2 (CO) 5 ] - show the highly fluctional character of this anion in solution. The X-ray structural parameters of Ph 4 As[C 7 H 7 Fe 2 (CO) 5 ] (space group P2 1 /n) can be interpreted in terms of a rotation of the tub shaped C 7 H 7 ring against the CO bridged Fe 2 (CO) 5 fragment in the solid state. Consequently, each iron atom is alternatingly η 3 -or η 4 -coordinated to the allyl anion and the diene part, respectively, of the anionic 8π system of the cycloheptatrienyl ring.