The quasi-one-dimensional chain [{PtRh(TCM)(2)(NH3)(2)Cl-2.5}(2){Pt-2(PVM)(2)(NH3)(4)}(2)](n)(PF6)(6n)ce nter dot 2nH(2)O (Chain-2; TCM = Cl3CCONH-, PVM = (BuCONH-)-Bu-t), which consists of Pt and Rh atoms, has been obtained from two dinuclear compounds, [Pt-2(PVM)(2)(NH3)(4)](PF6)(2)center dot H2O (1) and [PtRh(TCM)(2)(NH3)(2)Cl-3] (2). Single-crystal X-ray analysis showed that the dinuclear compounds stack with metal-metal bonds to form octameric units, Pt Rh Pt Pt Pt Pt Rh Pt (Pt6Rh2), that are bridged by the Cl- ion to be a quasi-one-dimensional chain. Elemental analysis, X-ray photoelectron spectroscopy, electron paramagnetic resonance (EPR), and magnetic susceptibility measurements showed that Chain-2 has a mixed valency and one unpaired electron per octameric Pt6Rh2 unit. Taking into account the small observed g(av) value (g(av) = 2.01 at room temperature) obtained by EPR measurement and B3LYP density functional theory calculations of the model complex, oxidation states of the octameric unit are postulated to be Pt3+-Rh2.5+-Pt2+-Pt2+-Pt2+-Pt2+-Rh2.5+-Pt3+, where the EPR isotropic signal showed that the unpaired electron resides in the Rh d(xy) orbitals (delta* orbitals in Pt-Rh dinuclear parts) and hops from one Rh atom to another.