4-[(E)-2-Ferrocenylethenyl]-1,8-naphthalic anhydride

In the structure of the title compound, [Fe(C5H5)(C19H11O3)], the plane of the substituted ferrocene ring is tilted by 14.17 (6)° with respect to the mean plane through the naphthalene ring system. In the crystal structure, centrosymmetric dimers are formed through π–π interactions [centroid–centroid distance = 3.624 (2) Å] between the substituted ferrocene ring and the three fused rings of the naphthalic anhydride unit. Pairs of dimers are held together by further naphthalene–naphthalene π–π interactions [distance between parallel mean planes 3.45 (3) Å]. Each dimer interacts with four neighbouring dimers in a herringbone fashion through C—H⋯π interactions, so forming a two-dimensional sheet-like structure.

In the structure of the title compound, [Fe(C 5 H 5 )(C 19 H 11 O 3 )], the plane of the substituted ferrocene ring is tilted by 14.17 (6) with respect to the mean plane through the naphthalene ring system. In the crystal structure, centrosymmetric dimers are formed throughinteractions [centroidcentroid distance = 3.624 (2) Å ] between the substituted ferrocene ring and the three fused rings of the naphthalic anhydride unit. Pairs of dimers are held together by further naphthalene-naphthaleneinteractions [distance between parallel mean planes 3.45 (3) Å ]. Each dimer interacts with four neighbouring dimers in a herringbone fashion through C-HÁ Á Á interactions, so forming a two-dimensional sheetlike structure.
The title compound, I, was prepared by the Heck coupling (Heck 1982) of 4-bromonaphthalic anhydride and vinylferrocene. Cyclic voltametry of I shows a reversible ferrocenyl oxidation at 0.62 V and an irreversible multi-electron process at -1.0 V associated with the naphthalene moiety (McAdam et al., 2003).
The molecular structure of compound I is illustrated in Fig. 1. The molecule consists of a ferrocene moiety linked in a trans fashion through an ethene to a naphthalic anhydride group. The bond length between the ethene carbons, C13 and C14, agrees well with the mean value of 1.32 (2) Å found for 49 observations in 41 structures from the Cambridge Structural Database (version 5.28, last update Nov. 2007;Allen, 2002). The ferrocene rings are eclipsed and tilted by 3.14 (9)° with respect to each other. The plane of the substituted ferrocene ring is tilted by 14.17 (6)° with respect to the plane of the naphthalene ring [C1-C12, O1] such that the ethene linked ring is above the plane. This tilt arises from steric interactions between the peri H atom of the naphthalene ring and the adjacent H atom of the ethene moiety.
In the crystal structure of I centrosymmetric dimers are formed through strong complementary π-π interactions between the substituted ferrocene rings and the heterocyclic pyrandione rings [C1, C6, C7, C11, C12, O1]. The distance between the centroids of the cyclopentadiene and the six-membered heterocyclic ring is 3.624 (2) Å. These dimers are held together by naphthalene-naphthalene π-π interactions, with a distance of 3.45 (3) Å between the symmetry related parallel mean planes of the three fused rings of the naphthalic anhydride moiety. In addition there are also complementary C=O···H-C(cyclopentadiene) interactions at 2.46 Å [corresponding separation for O3···C24 is 3.386 (4) Å]. Packing is achieved through (cyclopentadiene) C-H···π(cyclopentadiene) interactions at 2.77 Å, such that each dimer interacts with four neighbouring dimers in a herringbone fashion to form a two-dimensional sheet-like structure (Fig. 2).

Refinement
The H-atoms were included in calculated positions and treated as riding atoms: d(C-H) = 0.93 Å with U iso =1.2U eq (C). Fig. 1. The molecular structure of compound I, showing the atom numbering scheme and displacement ellipsoids drawn at the 50% probability level.