Inorganic Chemistry, Vol.39, No.9, 1907-1918, 2000
Triribbed-functionalized clathrochelate iron(II) dioximates as a new and promising tool to obtain polynucleating and polynuclear compounds with improved properties
Template condensation on iron(II) ion of dichloroglyoxime (H(2)C12Gm) with (C6H5O)(3), n-C4H9B(O-n-C4H9)(2), and BF3. O(C2H5)(2) in CH3NO2 afforded reactive clathrochelate precursors Fe(C12Gm)(3)(BC6H5); (2), Fe(C12Gm)(3)-(B-n-C4H9)(2) (3), and Fe(C12Gm)(3)(BF)(2) (4). A series of triribbed-functionalized clathrochelate dioximates have been synthesized. Reaction of 2 with C6H5SH/K2CO3 and CH3SH/t-C4H9OK in 1,4-dioxane and THF afforded Fe((C6P5S)2Gm)(3)(BC6H5)(2) (5) and Fe((CH3S)2Gm)(3)(BC6H5)(2) (6). Reaction of 3 with C6H5OK THF afforded Fe ((C6H5O)2Gm)(3)(B-n-C4H9)(2) (7). Condensation of 3 with bis(2(o-oxyphenoxy))diethyl ether in THF afforded di- and tricrown etheric Fe(CwGm)(2)(C12Gm)(Bn-C4H9)(2) (8) and Fe(CwGm)(3)(B-n-C4H9)(2) (9) clathrochelates. Condensation of 3 with 3,5-dithiaoctane-1,8-dithiol/Cs2CO3 in DMF afforded the thiocrown etheric Fe((12anS(4))- Gm)(3)(BC6h5)(2) complex (10). Reaction of 2 with n-butylamine in DMF resulted in the tetrasubstituted Fe((n-C4H9NW)2Gm)(2)(C12Gm)(BC6H5)(2) clathrochelate (11). The clathrochelates obtained have been characterized both on the basis of elemental analysis, FAB and PD mass spectrometry, IR, UV-vis, Fe-57 Mossbauer, and NMR spectroscopies and crystallographically (compounds 3, 4, 6, 7, and ii). An encapsulated iron(II) ion in a distorted trigonal-prismatic environment of six nitrogen atoms of the macrobicyclic ligand was found to be in a low-spin state. The cyclic voltammograms for the complexes 2-11 show irreversible oxidation waves assignable to Fe3+/Fe2+ couples. The con elation of E-1/2 for these couples with Hammet sigma(para) constants for substituents in dioximate fragments has been demonstrated.
Keywords:P-BLOCK ELEMENTS;ELECTRON-TRANSFER REACTIONS;TRANSITION-METALCOMPLEXES;TEMPLATE SYNTHESIS;CAGE COMPLEXES;CROSS-LINKING;CHIRAL RECOGNITION;GROUND-STATE;IONS;LIGANDS