THE CRYSTAL AND MOLECULAR STRUCTURE OF AN OCTACOORDINATED IRON(II) COMPOUND—TETRAKIS(1,8-NAPHTHYRIDINE)Fe(II) PERCHLORATE
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Recently, Hendricker and Bodner reported the synthesis of a series of first-row transition metal complexes of the type M(L)4(C 104)2, where M is a metal of the 3d transition series and L = 1, 8-naphthyridine. Preliminary space group determination indicates that all the perchlorates of the 3d-transition series from M = Mn2+ to M = Zn2+ are isomorphic. Single crystals suitable for X-ray diffraction studies were grown from methanol solutions of the perchlorate salts. Red, prismatic, crystals of the Fe(II) salt were found to be triclinic with the following cell dimensions: a = 9.163(3), b = 9.315(3), c = 20.116(8)Å, α = 99.66(8), β = 77.37(8) and γ = 91.70(8)°; Z = 2 molecules/unit cell. [formula omitted]. It was assumed that the space group is PI, which was verified by structure solution and refinement. The intensity data were collected with MoKa radiation (λ = 0.71069 Å) using a manually-operated Picker four-circle goniometer. In all 1969 non-zero, independent, reflections were obtained for which the value of |F2| > 3σ. The structure was solved by standard Patterson methods using an unsharpened 3-dimensional function. The coordination polyhedron is a distorted dodecahedron, the distortions of which are the result of the rather rigid constraints introduced by a planar, inflexible ligand having a small “bite” and by ligand-ligand repulsions. The disposition of the nitrogen ligands around Fe(U) can be described as follows: one nitrogen of each naphthyridine ligand occupies the A positions of the dodecahedron while the second is constrained to occupy the B positions. The Fe—N bond of the latter set is shorter than the Fe—N bonds formed by the A set of nitrogen ligands. One Fe—N bond is longer (2.756 Å) than the rest which range from 2.184 to 2.465 Å. The average length for the eight Fe—N bonds is 2.35 Å, which is in close agreement with similar Fe—N bonds studied elsewhere. The naphthyridine fragments are planar and in the four ligands the worst deviation of any atom from planarity is 0.02 Å. The perchlorate anions have considerable freedom of libration. Their bond lengths were corrected for errors due to torsional motion and the average value of the corrected Cl—O bonds is 1.450 Å. The final value of the discrepancy indices are R = 0.069 and Ri = 0.071. © 1971, Taylor & Francis Group, LLC. All rights reserved.
author list (cited authors)
Singh, P., Clearfield, A., & Bernal, I.