Novel Unsymmetrical Ru(III) and Mixed-valence Ru(III)/Ru(II)Dinuclear Compounds Related to the Antimetastatic Ru(III) Drug NAMI-A

摘要

In this paper we report the stepwise preparation and the characterization of new unsymmetrical monoanionic Ru(III) dinuclear compounds, [NH4][{trans-RuCl4(Me2SO-S)}(μ-L){mer-RuCl3(Me2SO-S)(Me2SO-O)}] (L = pyz (>1), pym (>2)). By a similar synthetic approach we also prepared new mixed-valence Ru(III)/Ru(II) dinuclear compounds of formula [NH4][{trans-RuCl4(Me2SO-S)}(μ-pyz){cis,cis,cis-RuCl2(Me2SO-S)2(CO)}] (L = pyrazine (pyz, >3), pyrimidine (pym, >4)). Moreover, we describe the chemical behavior of compounds >1-4 in physiological solution, also after complete reduction (with ascorbic acid) to the corresponding Ru(II)/Ru(II) species. Overall, the chemical behavior of >1 and >2 after reduction resembles that of the corresponding dianionic and neutral dinuclear species, [{trans-RuCl3(Me2SO-S)}2(μ-L)]²⁻and [{mer-RuCl3(Me₂SO-S)(Me₂SO-O)}₂ (μ-L)]. On the other hand, the mixed-valence dinuclear compounds >3 and >4, owing to the great inertness of the cis,cis,cis-RuCl₂(Me₂SO-S)₂(CO)(1/2μ-L) fragment, behave substantially like the mononuclear species [trans-RuCl₄(Me₂SO-S)(L)]⁻ in which the terminally bonded L ligand can be considered as bearing a bulky substituent on the other N atom.