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Each Pd(dppp) unit retains its chelating phosphine and offers two adjacent pyridyl binding sites at an approximately right angle. Three such units bridge pairs of metalloligands, giving $[{\mathrm{Fe}}_2{\mathrm{Pd}}_3{L}_2(\mathrm{dppp}{)}_3{]}^{10+}$, a trigonal bipyramid with two Fe vertices and three equatorial Pd vertices. All six outward pyridines are used: $2\times 3=3\times 2$. The Pd/Fe ratio is $3/2$, matching the reagent dose, and the cation charge is $2(2)+3(2)=10$ because the organic ligands are neutral.

The two donor sites left by dppp are cis, so each equatorial Pd joins one arm from each Fe cap. A mere mass-spectral maximum charge is not an independent structure determination, but its consistency with donor counting and binding geometry strongly selects this model.

The six diphosphines bind the six Pd centres, occupying two adjacent sites on each and displacing two pyridines per Pd. Reassembly therefore favours the two-connected Pd nodes of the bipyramid instead of the cube's four-connected nodes. The balanced transformation isThus two cages of type 4 and four free metalloligands of type 3 form per cage 5. iron, palladium, ligand and charge balances all close. Strong phosphine chelation drives the donor replacement, while the release of additional discrete species can favour entropy. The analogous conversion is observed experimentally in the cited heterobimetallic system.^[ref]