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Results show that bonding requirements of the constituent elements in rare-earth metal halides determine their structural configurations. Data reveal that the structural distortions originate from orbital energies of the respective rare-earth and interstitial elements.

The electronic structures of binary M21S8 (M = Nb, Zr) and isostructural ternary (M,M')(sub 21)S8 (M,M' = Hf, Ti; Nb, Ta) phases are analyzed by means of extended Huckel tight-binding band structure calculations. The distribution of hafnium and titanium atoms on the six crystallographically independent metal sites in the ternary phase Hf(sub 7.5)Ti(sub 13.5) are rationalized using metal-metal bond strength, electronegatavity/charge, and site volume arguments.

The electrical conductivity of Nb(sub 21)S(sub 8) is moderate metallic with a specific resistivity of 3.90 m(upper case omega) cm at 273 K in temperatures ranging from five to 290 K. This was gleaned from the synthesis of phase pure samples of Nb(sub 21)S(sub 8) and results of magnetic susceptibility and electric resistivity measurements. It was also found that the chemical picture of superconductivity wherein it is favored by the tendency of pairwise attraction of conducting electrons at the Fermi level is applicable on Nb(sub 21)S(sub 8).

Research was conducted to prepare a derivative of the unknown W5Si3-type Ca5Sn3. The structure has an inherent problem of short A-A separations along the tetrahedral chains that lie on the side faces of the tetragonal cell and partial substitution of a smaller cation like Mg2+ was more appropriate. The reaction yielded a second compound in the process, Ca6.2Mg3.8Sn7. Results indicate the effect that different cations have on phase stability. Findings also suggest the existence of a new type of infinite tin chain derived from square-planar tin units. Its synthesis and crystal structure are described.

The synthesis and characterization of well-reduced and heavily interbridged zirconium chloride-iodide cluster systems are described. The scheme involves the reactions of Zr, ZrCl4, ZrI4 and B or Be in sealed tubes for four weeks at 850 degrees C. The results showed that the tight closed-shell repulsions in the halogen-bridged structures can be altered by substitution of differently sized anions.

The addition of alkali or silver salts of dicyananoamide (dca), tricyanomethanide (tcm) and tetracyanoborate (tcb) to a solution of B[([C.sub.6][F.sub.5]).sub.3] in diethyl ether has produced salts containing voluminous C[([C.sub.6][F.sub.5]).sub.3] adduct anions. The studies have shown that as counterions for cationic early transition metal catalysts, the anions have displayed reduced ion pairing and hence increased catalytic activity.

The synthesis and structural determination of the first zirconium cluster compound with acetonitrile ligands, which has all the necessary properties for a widely usable starting material for new cluster phases, are described. The advantage of both title phases is that they contain Lewis acidic zirconium cluster units, which are useful as catalysts, with the additional advantage of tuneable redox properties.

The excision of chloride based Zr cluster units from solid-state start materials, their transformation to bromides by using EMIm-Br/Al[Br.sub.3] ionic liquids, the crystal structures of [(EMIm).sub.4][([Zr.sub.6]Z)[Br.sub.18]] (Z = Be, Fe) and spectroscopic data of the iron centered phase in different ionic liquids are reported. The results have concluded that this complete ligand exchange is considered as reversible, with the equilibrium being largely determined by the free ligand concentration.

The straightforward preparation and the crystal structure of the new compound [[Nb.sub.6][Cl.sup.i.sub.12][(CH3OH).sup.a.sub.4][Cl.sup.a.sub.2]].6C[H.sub.3]OH which contains the neutral [N[b.sub.6]C[l.sup.i.sub.12][(C[H.sub.3]OH).sup.a.sub.4]C[l.sup.a.sub.2]] cluster unit with an octahedral [[N[b.sub.6]C[l.sup.i.sub.12].sup.2+] cluster core is reported. The three-dimensional arrangement of the cluster units follows a stacking along the unit cell directions, resulting in a layered arrangement of the clusters, between which the methanol molecules are located.

Research has been conducted on dimeric rhodium(I) bis(carbonyl) chloride. The reaction of this compound with Lewis acids carried out in CO atmosphere at room temperature has led to salts which have been characterized by Raman spectroscopy and single-crystal X-ray diffraction.

The research of mixed-halide zicronium systems is presented. It is found that inter cluster-bridging halide positions are occupied by one halide type.

A study was conducted on the synthesis and structure of the mixed-halide cluster compound NaZr6Cl10.94(1)I3.06B. The findings indicate that the presence of both iodide and chloride ligands is necessary to form the structure of the title phase. Moreover, NaZr6Cl10.94I3.06B was found to be the first compound to be three-dimensionally linked by Ia-a-a functions only. The results also show that the chemistry of the reduced zirconium halides contains new variations.

One-pot three-component reactions of secondary or primary phosphines and primary amines with glyoxylic acid provide a wide variety of acyclic or cyclic phosphinoglycines, in the case of some chiral amines with high diastereoselectivity. The structure, hydrolysis, oxidation, coordination at M(CO)5 (M = Cr, Mo, W), and use in nickel-catalyzed ethylene oligomerization were studied. [ABSTRACT FROM AUTHOR]

Describes a mixed-halide structure with zigzag chains of clusters in multiply twinned crystals. Zigzag chains of boron-centered octahedra; Description of the noncluster interconnecting two-bonded X[sup i] sites; Appearance of crystals.

Reports on an extended Huckle tight-binding band structure study of the bonding in binary and isostructural ternary phases to understand the metal site occupation. Computational details; Electronic structure of the M[sub 12]S[sub 8] phases; Site occupation problem in the (M,M')[sub 21]S[sub 8] phases.

Reports the synthesis of phase pure samples of niobium Nb21-sulfur (S)8. Experimental section; Discussion on the results.