The reaction of [Mo3(m3-O)(m-Cl)3(m-OAc)3Cl3]- with Fe(III) results in the disintegration of [Mo3(m3-O)(m-Cl)3] core to form the isopolymolybdate compound [FeCl(DMF)5][Mo6O19] (1) and if CuI is employed in the synthetic reaction for the preparation of [Mo3(m3-S)(m-S2)3(dtp3Cl] [dtp = S2P(OEt2)], a heteropolymolybdate compound (Et4N)4[PMo12O40].2DMF (2) is obtained. The crystal structure of 1 and 2 were established by x-ray diffraction. The related disintegration reactions are discussed. Crystal data: 1; orthorhombic, space group Pmcn, a 1.4011(5), b 1.5180(14), c 1.7841(3) ? Z = 4, R = 0.075; 2; monoclinic, space group P21/n, a 1.4248(5), b 1.3786(4), c 1.9883(6) ? b 94.02(3)? Z = 2, R = 0.062.

Key words: CRYSTAL STRUCTURE DETERMINATION, IRON ION, HETEROPOLYACID, MOLYBDATE, MOLYBDATE, PHOSPHATE, MOLYBDENUM COMPLEX, CLUSTER COMPOUND, ISOPOLYACID, DIMETHYLFORMAMIDE