Acta Crystallographica Section C

Crystal Structure Communications

Volume 64, Part 5 (May 2008)

metal-organic compounds

 

Cobalt(II) and cobalt(III) complexes with 4'-(4-cyanophenyl)-2,2':6',2''-terpyridine

Z. Yu, A. Nabei, T. Izumi, T. Okubo and T. Kuroda-Sowa

Abstract: 4'-Cyanophenyl-2,2':6',2''-terpyridine (cptpy) was employed as an N,N',N''-tridentate ligand to synthesize the compounds bis[4'-(4-cyanophenyl)-2,2':6',2''-terpyridine]cobalt(II) bis(tetrafluoridoborate) nitromethane solvate, [Co^II(C₂₂H₁₄N₄)₂](BF₄)₂·CH₃NO₂, (I), and bis[4'-(4-cyanophenyl)-2,2':6',2''-terpyridine]cobalt(III) tris(tetrafluoridoborate) nitromethane sesquisolvate, [Co^III(C₂₂H₁₄N₄)₂](BF₄)₃·1.5CH₃NO₂, (II). In both complexes, the cobalt ions occupy a distorted octahedral geometry with two cptpy ligands in a meridional configuration. A greater distortion from octahedral geometry is observed in (I), which indicates a different steric consequence of the constrained ligand bite on the Co^II and Co^III ions. The crystal structure of (I) features an interlocked sheet motif, which differs from the one-dimensional chain packing style present in (II). The lower dimensionality in (II) can be explained by the disturbance caused by the larger number of anions and solvent molecules involved in the crystal structure of (II). All atoms in (I) are on general positions, and the F atoms of one BF₄^- anion are disordered. In (II), one B atom is on an inversion center, necessitating disorder of the four attached F atoms, another B atom is on a twofold axis with ordered F atoms, and the C and N atoms of one nitromethane solvent molecule are on a twofold axis, causing disorder of the methyl H atoms. This relatively uncommon study of analogous Co^II and Co^III complexes provides a better understanding of the effects of different oxidation states on coordination geometry and crystal packing.

Formula: [Co(C₂₂H₁₄N₄)₂](BF₄)₂·CH₃NO₂ and [Co(C₂₂H₁₄N₄)₂](BF₄)₃·1.5CH₃NO₂

	Structure factor file (CIF format) (502.1 kbytes) [ doi:10.1107/S010827010800992X/sq3135Isup2.hkl ] Contains datablock I
	Structure factor file (CIF format) (1284.7 kbytes) [ doi:10.1107/S010827010800992X/sq3135IIsup3.hkl ] Contains datablock II

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