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N, N-Dibenzoylferrocenecarboxamide

A survay of Cambridge Structural Database (Allen, 2002) revealed that 1 (Fig. 1) is the first structure with a N–(C=O)3 fragment linked to the ferrocenyl moiety. N1 is pyramidal and is displaced by 0.228 (1)Å out of the plane defined by atoms C11/C12/C19. Because of pyramidality, the angular sum around N1 is 352.6°. A somehow close C14–H14···N1 interaction of 2.55 Å seems to be indicative for a intramolecular hydrogen bond forming a five-membered ring that could be described by graph set descriptors as S(5) (Bernstein et al., 1995). On the other hand, the C14–H14···N1 angle is very small (101°) and there is no difference in chemical shifts for protons at C14 and C18 in the 1H NMR spectrum (7.91 p.p.m., doublet, for 4 protons of the C14, C18, C21, C25), therefore indicating the absence of an intramolecular hydrogen bond at least in solution. The C11=O1 carbonyl group and C1–C5 ring form an extended π-conjugated system, and therefore C1–C11 bond is shortened. The coplanar arrangement of a carbonyl group attached to the cyclopetadienyl (Cp) ring should allow maximum interaction of two π-systems. The C11=O1 bond is twisted out of the plane of the C1–C5 ring for 18.81 (11)°. The Cp rings deviate 9.3 (2)° from an eclipsed conformation. The value of the C–Cg1–Cg2–C pseudo-torsion angles, defined by joining two eclipsing Cp carbon atoms through the ring centroids range from 8.8 (1) to 9.8 (1)°. The Cp rings are almost parallel, with a dihedral angle between the mean planes of the rings of 1.84 (11)°. The amide groups do not lie in the plane of the attached aromatic rings. Thus, the plane of the C13/C12/O2/N1 atoms is inclined to the C13–C18 phenyl ring for 17.86 (9)°, and the plane of the C19/C20/O3/N1 atoms is inclined to the C20–C25 phenyl ring for even 27.27 (11)°. Two phenyl rings are perpendicular with respect to the C1–C5 ring. The corresponding dihedral angles are 85.36 (9) and 88.17 (10)° for C13–C18 and C20–C25 rings, respectively. Molecules of 1 are self-assembled by C4–H4···O1 hydrogen bonds (Fig. 2 ; Table 1) into C(6) (Bernstein et al., 1995) spirals parallel to the b axis. Hydrogen-bonded chains are further weakly linked by one C–H···π interaction, C15–H15···Cg2, also parallel to the b axis forming a two-dimensional framework.

N ; N-dibenzoylferrocenecarboxamide ; ferrocene ; crystal structure

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