C-13 AND H-1-NMR LINE BROADENING IN DESFERRIOXAMINE-B SPECTRA - KINETICS AND MECHANISM OF SIDEROPHORE CHEMISTRY

A slow rotation around C-N bonds of the naturally occurring trishydrox amic acid desferrioxamine B was investigated by H-1 and C-13 dynamic N MR techniques. Corresponding rate constants for the C-terminal, middle and N-terminal hydroxamates are 12 s(-1), 15 s(-1), and 9 s(-1), resp ectively. The slow rotation around the C-N bond of the middle hydroxam ato group is proposed to be the rate determining step in dechelation o f the middle hydroxamato group in ferrioxamine B. [GRAPHICS] study. Th e present paper reports a methylation process which deals with a MeOC- Rhm(III)... Pd ... Rh-III-COMe system. [GRAPHICS] t><bullet><bullet> R h-III-COMe system. [GRAPHICS] ation of a dimeric entity is achieved by a bridging ClO4 while hydrogen bonds from the imino groups to termina l and bridging ClO4 link two dimers to yield a ''dimer of dimers''. [G RAPHICS] GRAPHICS]