.eta.2 Coordination of RuII(hedta)- at the C-5-C-6 bonds of cytidine and uridine

ESI‐MS studies of the non‐covalent interactions between biologically important metal ions and N‐sulfonylcytosine derivatives

“…). It is known that monodentate metal binding to the N1‐blocked cytosine nucleobase can occur in any of the following ways: through N3, O2, N4, C5, or in a π ‐fashion through C5 and C6 . With isolated cytosine bases, binding to either N3 or O2 is favored, depending on the softness to hardness ratio of the metal ion and possible steric aspects.…”

Relative reactivity of N- and S-donor ligands in substitution reactions of aquaethylenedinitrilotetraacetatoruthenium(III) in aqueous solution *

“…Values for k 2 and k 4 obtained from this plot are 110 ± 15 and 1560 ± 50  Ϫ1 s Ϫ1 at 25 ЊC, respectively. Furthermore, for studies at pH <3 equation ( 12) can be rearranged 26 by correcting for the contribution of k 2 and k 4 to (14). Thus it is possible to…”

“…The chemistry of aminopolycarboxylate complexes of Ru II ,Ru III is also of continued interest due to their biochemical importance [14][15][16][17] and catalytic activity in oxidation reactions. [18][19][20] On dissolution of K[Ru(Hedta)Cl]ؒ2H 2 O the complex undergoes rapid aquation to produce [Ru(edta)(H 2 O)] Ϫ .…”

Five coordination modes of 4-aminopyrimidine with N-hydroxy-ethylethylenediaminetriacetatoruthenate(II)

“…The EI/2 values of the N(1) coordinated forms (0.14, 0.10 and 0.16V) for pym, 4CH3pym and 2NHzpy are very near the value of the pyridine complex (0.13 V)(8) while the EI/2 values of the t/2 forms (0.50, 0.44 and 0.53 V) for the same series are very near the 0.55 V average Rul~mI(hedta)(olefin) couple (~'23). The high potential wave for the ,,~/3,, species requires either a ruthenium(III/IV) or ruthenium(II/IV) wave, reflecting the much higher potential needed to achieve ruthenium(IV), but with the more favourable aspects of re-donor ligands for these waves.…”

“…A similar chemistry is known for the closely related [Run(edta)L] 2 species, studied previously by Diamantis and Dubrawski (4'5) and Matsubara and Creutz t6'7). In 1990, Zhang et al discovered that [Run(hedta)] -also form :12 complexes via the C(5)-C(6) bonds of thc pyrimidine nucleobases cytidinc (C) and uridine (U), and related pyrimidine nucleobase derivatives (8). These t/2 isomers exist in isomeric competition with coordination of the ruthenium(II) centre at the normal N(3) position and, at high pH, with a chelated form which involves N(3) and the exo-keto or amino functionalities at C(4) of uracils and cytosines ts).…”