Synthesis and crystal structures of 2-(ferrocenyl-carbon-yl)benzoic acid and 3-ferrocenylphthalide.

The title compounds, 2-(ferrocenylcarbon-yl)benzoic acid, [Fe(C5H5)(C13H9O3)], 1, and 3-ferrocenylphthalide [systematic name: 3-ferrocenyl-2-benzo-furan-1(3H)-one], [Fe(C5H5)(C13H9O2)], 2, have been synthesized and structurally characterized by single-crystal X-ray diffraction. The crystal structure of compound 1 was solved recently at room temperature [Qin, Y. (2019 ▸). CSD Communication (CCDC deposition number 1912662). CCDC, Cambridge, England]. Here we report a redetermination of its crystal structure at 90 K with improved precision by a factor of about three. The mol-ecular structures of both compounds exhibit a typical sandwich structure. In the crystal packing of compound 1, each mol-ecule engages in inter-molecular hydrogen bonding, forming a centrosymmetric dimer with graph-set notation R 2 2 (8) and an O⋯O distance of 2.6073 (15) Å. There are weak C-H⋯O and C-H⋯π inter-actions in the crystal packing of compound 2. The phthalide moiety in 2 is oriented roughly perpendicular to the ferrocene backbone, with a dihedral angle of 77.4 (2)°.