Abstract: A new compound (NH4)6•[Ca2(H2O)6(CH3COO)2]•{Ca@[O52(OH)4(CH3COO)2]}•14H2O was prepared and the structure was determined by Xray diffraction analysis. The compound shows an interesting girdlelike structure that is composed of eighteen Mo－O octahedra. There is a Ca2＋ cation in the center of the girdle, which connects to the girdle backbone by bonding to four oxygen atoms of the girdle. The valences of ten Mo atoms are ＋6 while those of the other eight Mo atoms are ＋5, between which Mo－Mo bonds are found. Four acetic ligands connect to the girdle. The girdles link into 1D chains by the Ca2＋ cations above and below the girdle bonding to the backbone oxygen atoms. This compound is triclinic, space group P1, a=1.055 2(2)nm, b=1.515 0(3)nm, c=1.544 9(3)nm, α=60.84(3), β=88.00(3), γ=71.21(3)°, V=2.019 4(7)nm3, R1=0.036 6 and wR2=0.083 3.

Key words: Molybdenum, Polyoxomolybdate, Girdlelike structure, Chainlike structure, Crystal structure