Ternary adduct {[W(CN)(8)](3-),[Pt(en)(2)](2+),[W(CN)(8)](3-)} in aqueous solution and crystal structure of [Pt(en)(2)](3)[W(CN)(8)](2)center dot 4H(2)O with infinite linear W center dot center dot center dot Pt chains

A new donor-acceptor system based on [W(CN)(8)](3-) and [Pt(en)(2)](2+) has been characterised in aqueous solution and in the solid state. Spectroscop ic studies indicate formation of the ternary adduct {[W(CN)(8)](3-),[Pt(en) (2)](2+),[W(CN)(8)](3-)} in aqueous solution. The aggregate has been descri bed as a mixed-valence species with weak-to-moderate coupling between metal centres. The solid [Pt(en)(2)](3)[W(CN)(8)](2). 4H(2)O exhibits the simult aneous presence of {W-V, Pt-II, W-V}<->{W-IV, Pt-IV, W-IV} electronic isome rs and can be interpreted in terms of ground state borderline electronic lo calised-to-delocalised species. The structure of [Pt(en)(2)](3)[W(CN)(8)](2 ). 4H(2)O consists of one-dimensional infinite chains formed by tungsten an d platinum moieties linked through hydrogen bonding from ethane-1,2-diamine nitrogens and water molecules to nitrogens of all cyano ligands.