(NH4)2MoS4 and (NH4)2MoOS3 were converted to (Bu4N)2(Mo2OS7) and [(Bu)4N]2(Mo3O2S8) or (Ph4P)2(Mo3S9) in different acidic solns. In HOAc/MeOH system (NH4)2WS4 was converted to (Bu4N)2(W4S12) and (Me4N)2(W3S10). When (NH4)2WOS3 was used as starting material, (Bu4N)2(W3O2Ss) was obtained. In dilute HCl aqueous solution, (NH4)2WS4 or (NH4)2WOS3 was converted to (Bu4N)2(W3OS8). (Ph4P)2(MoW2S10) is a heteronuclear cluster which contains Mo, W, and S. The regularity of the formation of chain cluster of (NH4)2MOnS4-n (M = Mo, W; n = O-2) under acidic condition is suggested. In chain Mo-S and W-S clusters, terminal S atoms linked with the metal, especially in trinuclear clusters, were more reactive. They could be removed readily either by tertiary phosphine or by cyanide to form terminal oxo-substitution products.

Key words: CRYSTAL STRUCTURE, CLUSTER COMPOUND, MOLYBDENUM COMPOUNDS, SULFUR COMPOUNDS, TUNGSTEN COMPOUNDS, CHAIN COMPOUNDS