EFFECT OF 2ND-SPHERE COORDINATION .3. ADDUCT FORMATION OF MONONUCLEARAND BINUCLEAR RUTHENIUM-AMINE COMPLEXES WITH 18-CROWN-6 ETHER

Adduct formation of 18-crown-6 ether (18C6) has been investigated on [ RU(NH3)(5)(pz)](PF6)(2) (pz = pyrazine), [Ru(NH3)(5)(dmapy)](PF6)(3) ( dmapy = 4-(dimethylamino)pyridine), and [(NH3)(5)Ru(pz)Ru(NH3)(5)](PF6 )(5) by spectrophotometry, cyclic voltammetry, and H-1-NMR spectroscop y. The results show that ruthenium(II)- and ruthenium(III)-ammine comp lexes form the adducts with 18C6 interacting at different ammine sites , that is, at the trans-ammine for the ruthenium(II) complex and at th e cis-ammines for the ruthenium(III) complex. The binuclear mixed-vale nce complex forms the adduct stepwise with 18C6 having 1:2, 1:3, and 1 :4 stoichiometries. The formation of an asymmetric 1:3 adduct offers t he possibility of partial valence trapping of the delocalized valence over the binuclear complex.