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The reaction of [NH4]2[MO2S2], AgI and (n-Bu)4NBr in solid state produced the polyoxometalates [(n-Bu)4N]4[M6O19][Ag2I4] (1, MMo; 2, MW) which were structurally determined. The crystals of 1 and 2 are isomorphous, monoclinic, space group P21/c. 1, a = l.6624(2), b=1.6699(3), c=l.7217(2) nm, β=98.29(1)°, V=4.729(1) nm3, Z=2, R=0.040, Rw“0.037; 2, a = 1.6636(3), b = 1.6733(3), c = 1.7190(3) nm, β=98.25(1)°, V=4.736(l) nm3, Z = 2, R = 0.038, Rw = 0.047. The results of the structure determination showed that the two compounds had the same structures whose skeletons are composed of [Ag2I4]2. and [M6O19]2-. The difference of them and heteropolymetalate compounds synthesized in solution is that the title compounds contain cluster. ion, heteropolymetalate and organic cations, while the latter is only composed of heteropolymetalate and organic cations.

Two complexes with 2,2′-diamine-4,4′-bithiazole (L), [cis-L2CoCl2]·CH3OH and [cis-L2NiCl2]·CH3OH were synthesized and characterized by elemental analysis and IR spectroscopy. The X-ray crystal structure of [cis-L2CoCl2]·CH3OH has been determined. The coordinated molecules all contain a six-coordinated cobalt atom chelated by two 2,2′-diamine-4,4′-bithiazole ligands and two Cl− ions in a cis arrangement. The CoN bond lenghts range from 2.120 to 2.194 A and the CoC(1) bond lengths are 2.469 and 2.499 A. The effect of these complexes on the DNA synthesis of sarcoma 180 tumour cells has been investigated by the technique of isotopic liquid scintillation. The results indicated that complexes show ability to inhibit DNA synthesis of the tumour cells.

A new one-dimensional compound TiO 4 (Te 2 ) 4 TeI 4 has been synthesized. Its important structural features are that of a distorted tetrahedral oxygen-centered cluster of Ti atoms bridged by Te 2 groups and that each μ 4 -Te atom connects two neighboring clusters to form a chain. It is found that the stable compounds with M 4 O cluster core meet 4 n electron criterion.

The compound [(tmpa)Zn(im)Zn(tmpa)](ClO 4 ) 3 [where tmpa is tris(2-pyridyl)-methylamine and im is imidazolate anion] was synthesized, and its crystal structure was determined by X-ray diffraction methods. The structure consists of a dimeric complex bridged by the deprotonated imidazole. The geometry of the coordination polyhedron around the zinc(II) ions is very near to trigonal bipyramidal. The electronic spectrum indicates the corresponding copper(II) dimer has the same geometrical structure as the zinc(II) dimer. Its ESR powder X-band spectrum shows features typical of an S = 1 system. Variable-temperature (4.2–300 K) magnetic susceptibility data give the antiferromagnetic interaction parameter J = −32.0 cm −1 . This behaviour is best accounted for by a super-exchange mechanism involving σ-exchange pathways.

The title compound has been synthesized and its crystal structure determined at room temperature. The final R is 0.047 for 2216 independent observed reflections with I ⩾ 3σ(I). The crystal structure consists of repeated [Cu(bipy)2(sacch)]+ cations, non-coordinated saccharin anions and three lattice water molecules. In the complex cation [Cu(bipy)2(sacch)]+], the Cu2+ is bonded to the five nitrogen atoms originating from two bipyridines and one saccharin with a distorted trigonal-bipyramidal stereochemistry. The d-d transition absorption and IR spectra of the title compound crystal are also reported and are explained perfectly by the scaling radial theory proposed by us.

The synthetic route, structural features and qualitative results of molecular orbital calculations for 10 cubane-type tetranuclear molybdenum (tungsten) clusters with S 2 P(OC 2 H 5 ) 2 (dtp) as the ligand are summarized. There are two cluster cores, [Mo 4 S 4 ] and [Mo 4 OS 3 ], in the structures of a series of the compounds. Two isomer configurations—α and β—exist for both cubane cores which possess very similar total energies. The difference between the α and β configurations lies only in the coordinating fashion of the dtp ligands to the molybdenum (tungsten) atoms. A characteristic feature of these M S tetranuclear cluster compounds is that a change in the number of electrons of {Mo 4 } from 10 to 12 does not affect the fundamental cubane-like molecular configuration. This may be attributed to the effect of symmetry of the cluster structure and the nature of the ligand on the electronic structure of the compounds.

The tetranuclear molybdenum cluster {[Mo 4 S 4 (μ-OAc) 2 (dtp) 4 ·H](CH 3 ) 2 CO} ( 4 ) (dtp=S 2 P(OEt) 2 ) was obtained by the reaction of [Mo 3 S 4 (dtp) 4 (H 2 O)] with Mo(CO) 6 in HOAc/Ac 2 O medium and then by recrystallization from acetone. The crystal belongs to the space group C 4 2n - P 2/ n with two molecules in a unit cell whose dimensions are a =17.271(3), b =11.985(3), c =13.061(2) A and β=105.94(1)°, V =2599(2) A 3 , D c =1.826 g/cm 3 . On the basis of 3613 independent reflections with I ⩾3σ( I ), the structure was refined to R =0.040, R w =0.055. The cluster anion [Mo 4 S 4 (μ-OAc) 2 (dtp) 4 ] − contains a [Mo 4 S 4 ] 5+ cubane type core. This formulation is supported by XPS, ESR and 1 H NMR measurements of 4 . There are 11 electrons which make up six MoMo bonds.

The additive reaction of SbCl3 to trimolybdenum clusters with loose coordination sites, Mo3(μ3-S) (μ-S)3 [S2P (OEt)2]4 · L' (1 L' H2O; 2, L' C3H3ON), in a C2H5OH-HCl medium yields complexes {Mo3 (μ3-S) [(μ-S)3 · SbCl3] [S2P (OEt)2]4 · (C2H5OH)} (C2H5OH) (3) and {Mo3 (μ3-S) [(μ-S)3 · SbCl3] [S2P (OEt)2]3 [SXP (OEt)2] · (C3H3ON)} (X S,O) (4), respectively. The crystal and molecular structures of these two compounds have been determined by single crystal X-ray crystallography: crystal 3 belongs to the monoclinic system, P21,/n, while crystal 4 belongs to the triclinic system, P 1, The intensity data were collected on an Enraf-Nonius CAD-4 diffractometer with graphite-monochromatized MoKα radiation by using the ω-2θ technique. The structures were solved by the Patterson method as well as direct methods and refined by full matrix least-squares method. Final R values were 0.078 for crystal 3 and 0.068 for crystal 4, respectively. The result of the structure determination showed that the two molecular structures are practically formed by connecting a trimolybdenum clusters with loose coordination sites, {Mo2(μ3-S)- (μ-S)3[S2P(OEt)2]4 · L (L C2H5OH, C3H3ON), with a SbCl3 molecule through three (μ-S) atoms to form the {Mo SbS4} core of a cubane-like type. There are relatively weak coordination bonds between the Sb and the three (μ-S) atoms, while no bonding interaction between the Sb and the three Mo atoms is found. In the additive compounds the structural character of the trimolybdenum clusters with loose coordination sites has significantly been changed. In addition, 3 still has the reactivity for the loosely coordinated EtOH to be replaced by an oxazole ring to form crystal 4. However, the three (μ-S) atoms may be regarded as triple bridging S atoms each connecting two Mo atoms and a Sb atom. The information obtained serves as an evidence that the tetranuclear clusters might be formed by a [3 + 1] reaction mode.

A new kind of binuclear tungsten complex {W2[SC(NH2)NHCH2CHCH2]3Cl6} H2O was synthesized by mixing a concentrated hydrochloric acid solution of [W2Cl]3− with allylthiourea and investigated by X-ray structural analysis. The crystal is monoclinic, belonging to the space group P21, with the following parameters: a = 8.496(1)A, b = 18.760(2)A, c = 8.591(1)A, β = 91.36(1)' and Z = 2 with Dc = 2.297 g·cm−3. The structure was solved by heavy atom method and difference Fourier synthesis and refined by full-matrix least-squares technique to a final R factor of 0.038 for 2812 independent reflections with I ≥ 3σ(I). The result shows that in the structure each W atom forms an octahedral coordination with three Cl atoms and three bridging S atoms of the allylthiourea molecules. These two octahedra share a common face to form a binuclear complex with a very much shorter W-W bond distance (2.443(1)A), indicating a strong interaction between the two W atoms. Judging from the orientation of the thiourea ligand groups with respect to the W-S bonds, the thiourea S atoms are coordinated to the two W atoms in different manners. It is noted that one of the two W atoms is located at the point of intersection of the three thiourea planes, while the other W atom is located quite apart from these thiourea planes with three W-S bonds nearly perpendicular to each of them respectively.

In this paper, we report the crystal structure of the low temperature form of barium borate-a new type of SHG material. Ba3(B3O6)2 crystal belongs to trigonal system with space group C34-R3. There are 6 formula units in one hexagonal cell. The unit cell dimensions referring to hexagonal axes are a = b = 12.532?, c = 12.717?. Diffraction data were collected on Philips PW-1100 four-circle diffractometer. The number of independent reflections amounts to 693. The structure was determined by conventional three-dimensional Patterson and Fourier syntheses and refined by "block diagonal" matrix least-squres procedures to R = 0.046. This structure can be considered as a layer step type of lattice built up by Ba2+ and (B3O6)3- rings atterna-tively. The anion (B3O6)3- group is nearly planar with its plane perpendicular to the threefold axis which passes through the center of the ring. Each barium atom has seven oxygen neighbors. In comparison with the high temperature form of barium borate, it is shown that the acentric symmetry of the barium cations in this structure changes the electron density distribution of the inorganic conjugated boron-oxygen rings, thereby making principal contributions to the SHG effect.