STEPWISE REDUCTION OF ELECTRON-PRECISE, 6-ELECTRON, TRIANGULAR, [MO3(IV)S4(CN)(9)](5-) TO ELECTRON-RICH 7-ELECTRON, 8-ELECTRON AND UNSTABLE9-ELECTRON SPECIES RESULTING IN-CORE EXPANSION TO ELECTRON-PRECISE, 12-ELECTRON, TETRAHEDRAL, [MO4(III)S4(CN)(12)](8-)

Facile reduction of the triangular {Mo-3(IV)}(6)-core containing [Mo3S 4 (CN)(9)](5-) derivative is achieved in aqueous medium, containing th e KOH-KCN-K-2[Zn(CN)(4)] ternary system as supporting electrolyte, in a two-step one-electron reduction reaction followed by an irreversible one. The diamagnetic species containing the {Mo-3}(8) core, obtained by chemical reduction of [Mo3S4(CN)(9)](5-) with zinc in aqueous mediu m containing KOH-KCN, is oxidized by air in two steps. The partially o xidized species with {Mo-3}(7) core in the first step exhibits charact eristic ESR signals which on further oxidation quantitatively reverts to the original compound with {Mo-3}(6) core displaying distinctly sep arate isosbestic points in the stepwise conversion of {Mo-3}(8) to {Mo -3}(7) and {Mo-3}(7) to {Mo-3}(6) cores. Under drastic reduction condi tions with aluminium in 40% aqueous KOH solution the {Mo-3}(6) core is reduced to unstable trinuclear {Mo-3(III)}(9) core which expands to t etrahedral {Mo-4(III)}(12)-core containing [Mo4S4(CN)(12)](8-) derivat ive according to electron-precise cluster rule.