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 (H2C12Gm) 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 (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((C6H5S)2Gm)3(BC6H5)2 (5) and Fe((CH3S)2Gm)3(BC6H5)2 (6). Reaction of 3 with C6H5OK in 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((12anS4)Gm)3(BC6H5)2 complex (10). Reaction of 2 with n-butylamine in DMF resulted in the tetrasubstituted Fe((n-C4H9NH)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, 57Fe Mössbauer, and NMR spectroscopies and crystallographically (compounds 3, 4, 6, 7, and 11). 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 correlation of E1/2 for these couples with Hammet sigma para constants for substituents in dioximate fragments has been demonstrated.