Ruthenium(III) Triazacyclononane Dithiocarbamate, Pyridinecarboxylate, or Aminocarboxylate Complexes as Scavengers of Nitric Oxide

The preparation of a series of [RuIII(tacn)((eta)^2-dtc)((eta)^1-dtc)][PF6] (tacn = 1,4,7-triazacyclononane; dtc = dimethyldithiocarbamate, diethyldithiocarbamate, pyrrolidinedithiocarbamate, L-prolinedithiocarbamate, L-prolinemethyl ester dithiocarbamate, L-Nmethylisoleucinedithiocarbamate) complexes, 5-11, is described. Complex 5 reacts with NO to form the ruthenium nitrosyl complex 12. A series of [RuIII(tacn)(pyc)Cl][PF6] (pyc = 2-pyridinecarboxylic acid, 2,4- and 2,6-pyridinecarboxylic acid) complexes, 14-16, were prepared along with [RuIII(tacn) (mida)][PF6] (mida = N-methyliminodiacetic acid), 13, and [RuIII(Hnota)Cl], 17, (Hnota = 1-acetic acid-4,7-bismethylcarboxylate-1,4,7-triazacyclononane). Complexes 5-17 were evaluated for use as NO scavengers in an in vitro assay using RAW264 murine macrophage cells. [RuIII(tacn)((eta)^2-dtc)((eta) ^1-dtc)][PF6] complexes 5-11 are very efficient NO scavengers in this assay.