Metal–carbonyl and metal–nitrosyl complexes. Part XII. The crystal and molecular structure of (3-acetyl-1h-azepine)tricarbonyliron(0)

Abstract

The molecular geometry of (3-acetyl-1H-azepine)tricarbonyliron(0), C₁₁H₉NO₄Fe, has been determined by singlecrystal X-ray analysis from diffractometer data. The positional and thermal parameters of the iron, carbon, nitrogen, and hydrogen atoms were obtained by Fourier and least-squares procedures, and the final value R was 7·1%. The tricarbonyliron group binds to the C(4), C(5), C(6), C(7) butadiene fragment of the azepine ring, with Fe–C(4), C(7) distances of 2·182 and 2·168 Å and Fe–C(5), C(6) distances of 2·063 and 2·055 Å. The mean Fe–C(carbonyl) distance is 1·797 Å. The bond lengths in the azepine ring are: N(1)–C(2) 1·343, C(2)–C(3) 1·364, C(3)–C(4) 1·458, C(4)–C(5) 1·457, C(5)–C(6) 1·392, C(6)–C(7) 1·464, and C(7)–N(1) 1·391 Å, all with σ ca. 0·01 Å. The dihedral angle between the plane of the butadiene fragment, C(4)–(7), and the plane N(1), C(2)–(4) is 141°, the latter plane being inclined at 3·6° to that of the acetyl group. The crystals are triclinic, space group P, with a= 7·002 ± 0·005, b= 9·006 ± 0·006, c= 9·886 ± 0·008 Å, α= 86° 47′± 4′, β= 96° 11′± 4′, γ= 114° 19′± 3′, and Z= 2.