The ID zigzag chain compound of [{La(DMSO)_6(H2O)}(Pmo_(12)O_(40))· H2O]_n has been synthesized by reaction ofα-H3PMo12 O_(40)·Nh_2O, La2O_3 and DMSO in acetonitrile-water mixture and characterized by elemental analysis, IR and UV spectra, and X-ray single crystal structural analysis. The crystal structure indicates that the title compound forms an unprecedented one-dimensional zigzag chain built from the alternating polyanions and cationic units through Mo-O_d-La- O_d-Mo links. In the compound, there is a crystal water molecule in every unsymmetric structure unit and La~(3+) cations are nine- coordinated in a tricapped trigonal prism geometry environment with oxygen atoms from six DMSO molecules, one H2O molecule and two adjacent polyanions. It belongs to monoclinic space group P2_1/c, with unit cell dimensions a = 1.3916(3) nm, 6 = 1.7058(3) nm, c = 2.4750(5) nm, β= 99.16(3)°, V = 5.800(2) nm3, D_c = 2.825 g/cm3, Z = 4, R_1 = 0.0446, wR2 = 0.0871. The result of the single crystal X-ray diffraction analysis is in agreement with that of IR measurement, and both show that the metal cation units are coordinately bonded to the Keggin cluster. The UV spectrum of the title compound suggests that the compound is entirely disruptive in dilute solution. The result of TG-DTA shows that the title compound is thermally more table than that ofα-H_3Pmo_(12)O_(40) ·nH_2O.

Key words: polyoxometallate, CRYSTAL STRUCTURE, DIMETHYLSULFOXIDE, ACETONITRILE, WATER, IR, XRD, LANTHANUM COMPLEX