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A new type of dicationic sigma-telluranes (eta4-tellane), (10-Te-4(C2X2))2+*2Y- (X = S or Se, Y = BF4 or CF3SO3) was prepared from the new flexible acryclic tris-chalcogenide, 2,6-bis((phenylthio)-methyl)phenyl phenyl telluride and 2,6-bis((phenylseleno)-methyl)phenyl phenyl telluride and the corresponding telluroxide through transannular bond formation. Based on single-crystal X-ray structure determinations, two apical sulfonio- or selenonio ligands bond to the central tellurium atom.

The structure, synthesis, infrared absorption properties, electrical conductivity and thermoelectric power of the compound BaBiTe3 are discussed. The compound is described as one-dimensional and layered with slabs sandwiching Ba cations in pseudotrigonal prismatic sites. It is a narrow gap semiconductor that has one of the lowest lattice thermal conductivity values known for crystalline metal chalcogenides. Improvement of crystal quality and control of the level of dopants could greatly increase the thermoelectric performance of the compound.

The mixed tellurium/selenium Re6 clusters (NMe4)4(Re6(Te(sub 8-n)Se(sub n))(CN)6) (n=0 (1), n=1 (2), n=4 (3), n=7 (4) and n=8 (5)) were produced from the reactions of Re6Te15 with the required stoichiometry of NaCN and Se at 600 degrees C, followed by cation exchange with NMe4Br. These were synthesized by conventional solid state methods and were recrystallized after cation exchange. Compounds 1, 3 and 5 were characterized by single-crystal X-ray diffraction methods and the results on compound 3 stimulated the study of this series of compounds. The complications of cocrystallized mixtures, geometrical disorder and orientational disorder were observed.

The rigidity and stability of (Ag2Te2)(super 2-) layers and their tetragonal symmetry are most likely responsible for K(sub 0.33)Ba(sub 0.67)AgTe2 stabilization. Electron diffraction measurements indicate the presence of an incommensurate orthorhombic and a commensurate tetragonal superstructure. The structure, synthesis, and band-structure analysis of K(sub 0.33)Ba(sub 0.67)AgTe2 are discussed.

Extended Huckel level tight binding calculations help examine the bonding in three copper tellurides that have Cu atoms at the center of the tetrahedral site. The Te atoms exhibit a square pyramidal coordination to four copper atoms. NaCuTe is a semiconductor and K2Cu5TeS is metallic. Holes at Fermi levels are delocalized over three Te sites. The extended Huckel method fails to predict the exact structure and energy of CuTe.

An experiment was conducted to examine in detail the addition of carbon radicals to various diazirines, and also the mechanistic insights for this rare transformation. Carbon radicals produced from related organotellurides through radical exchange contribute to the nitrogen-nitrogen double bond of diazirines which produces diazirinyl radicals. These produce imines after dimerization and extrusion which, in the case of 3-(trifluoromethyl)-3-phenyldiazirine can be hydrolized to the required amines.

Ab initio studies on the elimination, disproportionation and exchange reactions of group 13 and period 6 hydrides and halides reveal the following periodic trends in relativistic and electron correlation effects. Lower metal-ligand bond strength with increasing atomic number gives rise to low valencies for heavier elements. Endothermicity of X2 elimination rises for heavier elements within group 13 but drops sharply along period 6. Period 6 fluorides resist disproportionation, which is favored in TlH and PbH2. Halides form weaker bonds with Tl(III) than with Tl(II). Finally, there is no special inert pair (6s) effect among period 6 elements.

A class of silyl tellurolate complexes of the -TeSi(SiMe3)3 anion was synthesized and characterized. The thermally stable lithium tellurolate derivative (THF2LiTeSi(SiMe3)3)2 was generated from the insertion of THF into (THF)3LiSi(SiMe3)3. X-ray crystallography revealed the molecule and its Li2Te2 core to be dimeric, with no interactions between dimeric units. The reaction of the compound with Et4NClin diethyl ether yielded (Et4N)(TeSi(SiMe3)3), while its treatment with triflicacid in hexane gave HTeSi(SiMe3)3.

Homoleptic tellurolates of zirconium and hafnium were prepared from -TeSi(SiMe3)3 ligand by tellurolysis of several metal tetraalkyls. X-ray crystal analysis of zirconium tellurolates showed the structure to consist of evenly-spaced molecules with the zirconium and four tellurium atoms in a pseudotetrahedral coordination environment. The reactivity of the compounds were investigated by reacting with a series of Lewis bases.

The synthesis of tellurium(VI)-azide species is described. The spectroscopic and crystal structure is determined.

Cucurbit[6]uril is identified to form the pseudorotaxanes along with the diammonium cations and the different varieties in concentrated medium. Te complicated structure indicates the stability of the reaction in association with the pseudorotaxane structure.

Research is presented demonstrating the characterization and synthesis of the first stacked planar diacyl dichalcogenide, (2-MeOC6H4CO)2Te2.

Diaryl- and alkyl arylgermanetellones 3 and 4, the heaviest congeners in the family of germanium-chalcogen double-bond compounds were synthesized and characterized structurally. The synthesis of the compounds was accomplished through the direct telluration of germylenes Tbt(R)Ge with elemental tellurium. X-ray crystallographic studies demonstrated that germanetellones 3 and 4 have a germatellurocarbonyl unit that is protected by bulky substituents. They were also confirmed to bear a Ge-Te double bond which is characteristic of the family of germanium-chalcogen compounds.

The first demonstration of an easy oxidative addition of a C-Te bond of diorganyl tellurides (R2Te) with group 10 transition metal complexes M(PEt3)n (M = Pt, Pd, Ni; n = 3, 4) producing MR(RTe)(PEt3)2 in high yields is presented. The oxidative addition of C-Te bonds with the platinum complex presented an interesting regioselectivity when an unsymmetrical telluride was used as the substrate.

An alternative method for generating single-source precursors of metal tellurides has been developed. This new approach involves catalytic dehydrocoupling reactions to generate the molecules or polymers that contain element-element bonds. The stoichiometric reactions utilized in the pathway by which the catalytic dehydrocoupling reaction took place are presented and discussed.

Experimental studies on the synthesis of cyclic Te compounds containing Te-N doublebond reveal that a reaction between TeCl4 and tBuNHLi in toluene at -100 degrees Celsius results in a compound with Te-N double bond, a cyclic tellurium imide and an N,N'-diorganotellurium diimide. The length of the double bond is 1.83 angstroms, which agrees with the expected value. The diimide possesses exocyclic imido substituents oriented in cis-manner to the folded Te2N2 ring, while the cyclic imide has a Te3N3 ring in a chair conformation.

X-ray and electron diffraction and ab initio theoretical studies yield the structure of tetramethyltellurium(IV). The apparent structure is a superposition of all geometries between the equilibrium and transition structures due to a low barrier to pseudorotation. The proton-decoupled 13C NMR spectrum exhibits a single resonance due to this pseudorotation.

Ternary polytelluride (ET4N)3Cu4SbTe12 is isolated by the solvent extraction of quaternary intermetallic materials containing transition, alkali and two main-group metals. Diffraction studies show the ternary polytelluride cluster (Cu4SbTe12)3- and tetraethyl ammonium cations. Ternary and quaternary polyanions with main group metal tellurides and coinage metals are also synthesized.

The synthesis of (NEt4)3(AuTe7) provides an example of a structurally unique metal-chalcogenide anion. The reaction of gold cyanide with a polytelluride dianion in dimethylformamide in the presence of triethylphosphine and tetraethylammonium chloride yields the complex as thin black parallelpipeds. X-ray analysis shows that the (AuTe7)3- anion is extremely planar, with the Au atom bonded to four Te atoms. A unique feature of this anion is the bonding between two Te atoms and the intermediacy of another Te-Te distance between bonding and nonbonding modes.

The photostimulated reactions of acyl aryl tellurides were investigated. The results indicate that acyl tellurides are an efficient source of acyl radicals suitable for use in oxidative processes. The generation of acyl radicals is proposed to occur by the photochemical and/or thermal initiation of homolytic cleavage of the acyl-tellurium bond followed bythe attack of the acyl radical on the trap.

Azobisisobutyronitrile catalyzes the regioselective carbotelluration of alkynes to form allenyl tellurides in modestto excellent (42-99%) yields. The stereoselectivity of the reaction can be as high as 81%. Evidence is presented suggesting a mechanism involving a radical chain initiated by addition of 1-cyano-1-methylethyl radical to the acetylenic bond. More efficient reactions occur with alkynes bearing electron-withdrawing groups. The carbotelluration is one of the few cases of the efficient addition of heteroatom-containing compounds to C-C olefinic bonds.

The synthesis and characterization of group two tellurolates based from the -TeSi(SiMe3)3 ('sitel') ligand were reported. Sitel complexes of calcium, strontium and barium were obtained from the reaction of the metal silylamides with HTeSi(SiMe3)3 in hexane. The complex (Mg(12-C-4)2)(TeSi(SiMe3)3)2 produced from the reaction of the magnesium derivative with 12-crown-4 was isolated as the THF salt and structurally characterized.

The structure of the Ru2+/Te2(super 2+) cluster (Ru6(Te2)7(CO)12)2- was investigated. (Ph4P)2(Ru6(Te2)7(CO)12) was generated byheating of Ru3(CO)12 with Na2Te2 and Ph4PCl in water at 110 degrees C. The cluster possesses an octahedral arrangement of six ruthenium atoms supported bya central Te2(super 2-). The cluster also possesses a peculiar central (Ru6(Te2)7)2- core which is similar to an excised segment of the RuTe2 pyrite-type lattice.