The {[Pt(en)(2)] [PtBr2(en)(2)]}(3)(CuBr4)(4) which consists of the double
chain structures of the main one-dimensional Pt(II)-Pt(IV) chain and one-di
mensional counteranion of trigonal bipyramidal Cu(I) ions, is doped with Br
-2. The intensities of d-d transitions and ESR spectra in Cu(II) species in
counteranions increase as increase of exposure time. Accordingly, the indu
ced Pt(III) species attributable to neutral solitons are considered to incr
ease in the main chain by doping.