Structural Studies of Binuclear Cobalt (III) Cyano Complexes

Citation

Fronczek, Franklin Robert (1975) Structural Studies of Binuclear Cobalt (III) Cyano Complexes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/wc2q-8t48. https://resolver.caltech.edu/CaltechTHESIS:03252022-181352122

Abstract

The crystal structures of six closely related binuclear cobalt(III) complexes have been determined by single crystal X-ray diffraction methods, in order to study the effects of the pentacyano system upon the bonding to various bridging ligands. Studies pertinent to dioxygen bridging ligands include the bis(pentacyanocobalt(III)) structures K₅{(CN)₅Co₂(CN)₅}·H₂O and the double salt K₈{(CN)₅Co₂(CN)₅} (NO₃)₂·4H₂O, as well as the bis(pentaamminecobalt(III)) structure {(NH₃) ₅Co₂(CN)₅}(SCN)₄. In all cases, the dioxygen ligands (peroxo and superoxo) are found to bridge to two cobalt atoms in the asymmetric, staggered arrangement, and both planar and nonplanar structures are noted. The structures of two molecules of the type pentacyanocobalt(III)pentaamminecobalt(III) are determined, with the bridging ligands cyanide and thiocyanate. These compounds are (CN)₅CoNCCo(NH₃)₅·H₂O and (CN)₅CoSCNCo(NH₃)₅·H₂O. The preparation and structure of the compound K₆{(CN)₅Co₂(CN)₅}·6H₂O, containing the new bridging ligand thiosulfite (SSO₂^2-) are reported. This ligand bridges the two cobalt atoms through its two sulfur atoms, and has a geometry similar to that of normal coordinated sulfites. Coordination to cobalt is trans planar.

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