Ribbed substituent

Cyclic voltammetry of the ferrocenylboron-capped oximehydrazonate iron(II) complexes with the same ribbed substituents (Table 39) reveal a reversible one-electron oxidation of the ferrocenyl iron at 320-H340 mV vs SCE. Electrolytic oxidation of the ferrocenyl iron at a potential of 750 mV in solution produces a stable mixed-valence complex. Cyclic voltammograms at this potential the solution before and after electrolysis indicate that the integrity of the complexes is maintained as the ferrocenyl is cycled between the +2 and +3 oxidation states. The redox potentials associated with the encapsulated iron ion are not affected by the oxidation state of the ferrocenyl iron, i.e., there is no apparent interaction between the two... 

D-Ribose is known as a component of the lipo- and capsular polysaccharides from many Gram-negative bacteria, where it is found as a (3-furanosyl unit.37 It is found as terminal a-D-Rib/ substituents in some serotypes of the O-antigen of lipopolysaccharides (LPS) from Stenotrophomonas maltophilia,38 Also as a-furanosyl residues, ribose is part of the extracellular polysaccharides of cyanobacteria.39... 

The i/c=N values in IR spectra of the di- and hexachloride clathrochelate precursors are the lowest of all those known so far for clathrochelate iron(II) tris-dioximates. The vc=n bands of both types of dioximate fragments distinctly appeared in the case of partially substituted Cs-nonsymmetric complexes. Alongside the vm-o and vb-o bands of the macrobicyclic framework, the IR spectra of ribbed-functionalized clathrochelates also contained characteristic lines of the substituents in dioximate fragments [65, 68]. 

The electrochemical behaviour of the ribbed-functionalized iron(II) [65, 68] and ruthenium(II) [78] clathrochelates with alkylamine, thioaryl, thioalkyl, phenoxyl and crown ether substituents in a-dioximate fragments was characterized by E1/2 values for Fe3+/2+ and Ru3+/2+ couples (Table 37). The Tomes criterion values of most complexes exhibited reversible or quasi-reversible anodic processes. Moreover, the quasi-reversible oxidation processes are accompanied by the formation of insoluble products followed by passivation of the working electrode. The Ev2 values depend on the electron-donating properties of the substituents in the ribbed fragments. The correlations of E1/2 values for Ru3" 2+ and Fe + 2+ couples with these substituents Hammet s Opara constants were observed in Refs. 65, 68, and 78. These correlations are rather qualitative, but they enable one to conclude that ruthenium complexes are less sensitive to the change of substituents in dioximate fragments. There was no correlation between the Em values and the inductive Taft s (cr,) constants for substituents in dioximate fragments. 

The synthesis of mono- and trisubstituted ribbed-functionalized d-metal tris-dioximates starting from the initial monohalogen-dioximes can be realized by Scheme 128. An alternative pathway of halogenation of the monosubstituted glyoxime derivatives is complicated because of side reactions of the clathrochelate framework destruction and halogenation of the substituents in a-dioximate fragments and at the boron atom, as well as by the fact that the products of partial halogenation (in the case of trisubstituted clathrochelates) may predominate. 

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