THE 1ST CYCLIDENE COMPLEXES - RELATIONSHIPS BETWEEN MACROCYCLIC RING SIZE, LACUNAR CAVITY SHAPE, AND DIOXYGEN AFFINITY OF THE COBALT CYCLIDENE DIOXYGEN CARRIERS
UNSPECIFIED. (1993) THE 1ST CYCLIDENE COMPLEXES - RELATIONSHIPS BETWEEN MACROCYCLIC RING SIZE, LACUNAR CAVITY SHAPE, AND DIOXYGEN AFFINITY OF THE COBALT CYCLIDENE DIOXYGEN CARRIERS. INORGANIC CHEMISTRY, 32 (6). pp. 904-910. ISSN 0020-1669Full text not available from this repository.
The nickel(II) and cobalt(II) complexes have been synthesized and characterized as the first examples of metal complexes of a 14-membered cyclidene. [(2,3,16,17,19,25-Hexamethyl-3,16,20,23,26,29-hexaazabicyclo-[16.6.6]triaconta- 1, 17,19,23,25,29-hexaene-kappa4N20,23,26,29)nickel(II)) hexafluorophosphate, NiC30H52N6P2F12, crystallized in the orthorhombic space group Pna2(1), with a = 24.543(11) angstrom, b = 8.077(4) angstrom, c = 18.576(8) angstrom, and Z = 4. The structure revealed that the planar cyclidene complex has a wide but very low cavity within which it might accommodate 02, in sharp contrast to the deep-saddle shaped cavities of the 15- and 16-membered homologs The cobalt(II) complex of the 14-membered cyclidene binds dioxygen reversibly at low temperatures with a reduced dioxygen affinity that has been ascribed to the cavity shape. Electrochemical data for the cobalt complex suggested that charge separation in the ligand system, which is caused by the twisting of the so-called vinyl groups, increases the electron density on the metal to some extent. Change in the parent macrocycle from a 16-membered ring to a 14-membered ring had little effect on the ESR spectra of the cobalt(II) complex and its dioxygen adduct. Autoxidation of the 14-membered cobalt(II) complex was found to be faster than that of its 16-membered analog, probably due to the more open cavity in the cyclidene derivative and the more cathodic potential of its cobalt(III/II) couple.
|Item Type:||Journal Article|
|Subjects:||Q Science > QD Chemistry|
|Journal or Publication Title:||INORGANIC CHEMISTRY|
|Publisher:||AMER CHEMICAL SOC|
|Date:||17 March 1993|
|Number of Pages:||7|
|Page Range:||pp. 904-910|
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