The ligand 4’-(3,4-dimethoxyphenyl)-2,2’:6’,2"-terpyridine (L(2)), containing a terpyridyl binding site and a masked catechol binding site, was prepared by a standard Krohnke-type synthesis. From this the complexes [Ru(terpy)(L(2))[PF6](2) (1) and [Ru(L(2))(2)][PF6](2) (2), containing one and two dimethoxyphenyl substitutents, were prepared : demethylation with BBr3 afforded [Ru(terpy)(H(2)L(1))][PF6](2) (3) and [Ru(H(2)L(1))(2)][PF6](2) (4), respectively, which have one or two free catechol binding sites pendant from the [Ru(terpy)(2)](2+) core. Binuclear complexes (based on 3) and trinuclear complexes (based on 4) were then prepared by attachment of other metal fragments at the catechol sites. In [Ru(terpy)(mu-L(1))Ru(bipy)(2)][PF6](3) (5) and [Ru(mu-L(1))2{Ru(bipy)(2)}(2)][PF6](4) (6) the pendant {Ru(bipy)(2)(O-O)}(n+) sites (O-O = catecholate, n = 0; o-benzosemiquinone, n = 1; o-benzoquinone, n = 2) are redox active and may be reversibly interconverted between the three oxidation levels. In [Ru(terpy)(mu-L(1))Pd(bipy)][PF6](2) (7), [Ru(mu-L(1))(2){Pd(bipy)}(2)][PF6](2) (8), [Ru(terpy)(mu-L(1))Pd(4,4’-(t)Bu(2)-bipy)][PF6](2) (9), and [Ru(mu-L(1))(2){Pd(4,4’-(t)Bu(2)-bipy)}(2)] [PF6](2) (10) the pendant {Pd(bipy)(catecholate)} fragments are known to be photocatalysts for production of O-1(2) in their own right. Electrochemical and UV/vis studies were performed on all complexes and consistently indicate the presence of interactions between the components in 5-10. The EPR specrum of 6 (which contains two semiquinone radicals) shows that the two spins are coupled by an exchange interaction, despite being well-separated and attached to mutually perpendicular terpyridyl fragments on either side of a central Ru(II) ion.