Octacyanotungstate(V) reacts with Cu(NO(3))(2).2H(2)O and 1,4,7-trimethyl-1,4,7-triazacyclononane in methanol, resulting in an eicosanuclear cluster [Cu(13)W(7)], which shows a diamondoid shape with a Tolkowsky cut and bears intracluster ferromagnetic coupling.