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The synthesis method and crystal structure of a novel Mo3 cluster wmpound are reported. The results of structural analysis and the quantum calculation for the entire cluster molecule reveal that though two Mo3 cluster units, which belong to two different kinds of structural type respectively, show an apparent ionic characteristic, the interaction between them via the bridging S atoms is still quite certain. The relationship between cluster electron counting and stability of the Mo3 clusters are also primarily discussed.

A new oxo-centred heterotrinuclear complex [Cr 2 MnO(PhCOO) 6 Py 3 ][CrO 3 Cl] was synthesized, which exhibited weak antiferromagnetic interaction between three atoms Cr III , Cr III and Mn III . The J values for Cr III Mn III and Cr III Cr III have been estimated; the central O atom provides the main superexchange pathway. It indicated that the distance of M( μ 3 -O) is an important factor for metal-metal superexchange interaction.

The new layered compound [FexMn1−x]Ta(O2)O2 (x ≈ 0.3) has been prepared and structurally characterized. This compound crystallizes in orthohombic system (C22v - Pmc21), a = 4.726(1), b = 5.697(2), c = 4.963(1)A with two formula units in the cell. The structure contains Ta and M atoms in unusual trigonal prismatic environments with the TaO distances ranging from 1.74(2) to 1.995(9) A, and the MO distances from 2.10(2) to 2.24(2) A. Each M site is statistically occupied by about 30% Fe atoms and 70% of Mn atoms (M ≈ 0.3 Fe + 0.7 Mn). Metrical details are discussed. Results of electrical resistivity measurements on the new material indicate the saturated semiconductor behavior along the c-axis.

A novel ESR-silent polyoxomolybdate Na(21)([Na(5)(H(2)O)(14)][Mo(46)O(134)(OH)(10)(mu-CH(3)COO)(4)]).CH(3)COONa.approximately equal to 90H(2)O (3) was simply synthesized in high yield by reducing an acidified aqueous solution of Na(2)MoO(4).2H(2)O and CH(3)COONa.3H(2)O. The structure of 3 is constructed by a 46-member crown-shaped anion, [Na(5)(H(2)O)(14)]within[Mo(V)(20)Mo(VI)(26)O(134)(OH)(10)(mu-CH(3)COO)(4)](21-), 3a, which is built up by three different but related building blocks in a new mode and further connected into layers via Na(+) and hydrogen bonds. Crystal data of compound 3: triclinic space group P(-1); a = 16.4065(3), b = 17.4236(2), c = 20.8247(3) A; alpha= 87.57, beta= 67.9810(10), gamma= 80.6970(10)o; V = 5445.08(14) A(3); Z = 1; D(calcd) = 2.902. Structure solution and refinement are based on 19014 reflections, R = 0.0750.

The six Mo atoms in the title compound, (C4H12N)2[Mo6O19].H2O, form a standard octahedral cage through bridging O atoms. The [Mo6O19]2− anion as a whole has Oh symmetry with three crystallographic fourfold axes aligned along Mo—O—Mo. There exist weak O⋯O hydrogen bonds (O100⋯O3 2.951 A) between the terminal O3 atoms of the anions and O100 atoms of the solvate hydrates in the unit cell.