Delivery agents which can carry the {Ru(NO)} 6 chromophore (“caged NO”) are desired for vasodilation and for photodynamic therapy of tumors. Toward these goals, complexes derived from [RuCl 3(NO)(H 2O) 2]= ( 1) have been prepared using dipyridylamine (dpaH) as mono and bis adducts, [Ru(NO)Cl 3(dpaH)] = ( 2) and [Ru(NO)Cl(dpaH) 2]Cl 2 = ( 3). The dpaH ligands coordinate cis to the Ru(NO) axis.The mono derivative is a model for a potential DNA groove-spanning binuclear complex {[RuNO)Cl 3] 2(tpada)} = ( 4) which has two DNA-coordinating Ru II centers, photo-labile {Ru(NO)} 6 sites, and a groove-spanning tether moiety.The binuclear assembly is prepared from the tethered dipyridylamine ligand N,N,N',N'-tetrakis(2-pyridylmethyl)adipamide (tpada) which has recently been shown to provide a binuclear carrier complex suited to transporting Ru II and Pd II agents. A related complex, [Ru(NO)Cl(pida)] = ( 5) with the {Ru(NO)} 6 moiety bound to (2-pyridylmethyl) iminodiacetate (pida 2-) is also characterized as a potential “caged NO” carrier. Structural information concerning the placement of the pyridyl donor groups relative to the {Ru(NO)} 6 unit has been obtained from 1H and 13C NMR and infrared methods, noting that a pyridyl donor trans to NO+ causes “trans strengthening” of this ligand for [Ru(NO)Cl(pida)], whereas placement of pyridyl groups cis to NO+ causes a weakening of the N-O bond and a lower NO stretching frequency in the dpa-based complexes.