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Low-valent iron complex bis(cyclooctatetraene)iron reacts with triethylphosphine telluride, TePEt3, to form extended inorganic solid-state tellurides of iron, FexTey. Various phosphine ligands produce different Fe/Te-containing compounds that are intermediates in the process. Structures of these intermediates are related to the final extended solid products. Use of larger ligands leads to the formation of smaller clusters and molecular structure of the complex influences the coupling characteristics of the Fe centers.

Crystallographs are used to examine the molecular cluster compound Cr1Te8(PEt3)6 (1), which results from the reaction of TePEt3 with (Et3P)2Cr(allyl)2 or Cr(2,4-dimethylpentadienyl)2, to establish its structure. Simple thermolysis can be used to transfrom 1 into the extended inorganic solid state compound Cr3Te4. Cr6 octahedron, Te8 cube and (PEt3)6 octahedron constitute the molecule.

The reaction of Ni(super 0) with triethylphosphine selenide was examined. It was shown that Ni(COD)2 (COD = cyclooctadiene) reacts with Et3PSe at elevated temperature to give a mixture of Ni3Se2 and Ni, that the two combine at lower temperature to give the cluster compound Ni23Se12(PEt3)13, and that this compound gives a similar mixture of Ni3Se2 and Ni on heating. The structure of the cluster is a molecular example of an intergrowth of NiSe and Ni.

Structure relationships in the Ni9Te6(PEt3), Ni20Te18(PEt3)12 clusters and the NiTe solid were presented. The study revealed that a conformation structured between the cluster and the solid could serve as the favored geometry of the compound. Moreover, the structure of the Ni20Te18 cluster was found to relate to the structure of the bulk compound. In addition, rearrangement of NiTe groups could involve heterogenous decomposition or polymerization of the clusters .

Yellow orange crystals of cis-Mo6Cl8Cl4P(C2H5)3(sub 2).2THF are obtained by reacting the trans form with P(C2H5)3 in THF solution. Eight chlorides and eight Mo atoms are arranged octahedrally. The two triethylphophine ligands are bound to 2 Mo atoms and the remaining 4 Mo atoms are coordinated to chlorine atoms. The phosphine ligands occupy a cis geometry. This represents progress in linking metal clusters into crystalline forms.

The conductance measurements and characterization of the molecule-electrode binding geometries of four pyridine-terminated molecules by elongating and then compressing gold point contacts in a solution of molecules is described. The results of first-principles conductance calculations for the four molecules in the low-conductance geometry which confirmed with the experimental results revealed that the dominant conducting channel in the conjugated pyridine-linked molecules is through the [[pi].sup.*] orbital.

Carbon incorporation in Ta2O5 and its effect on the material and electrical properties of Ta2O5 is studied. Carbon removes defects from the film and reduces conduction. It generates a conduction path such that at high concentrations, conduction dramatically increases.

Thermal and photoconductive charge transport processes are studied in Ta2O5 metal-oxide-metal capacitors fabricated by anodization, reactive sputtering, and chemical vapor deposition. The results obtained from each of the three methods are similar when compared with films that have the same thickness and electrodes.

The isolation andd characterization of (Et3P)4Fe4Te4 (1) and the synthesis of a mixture of beta- and epsilon-FeTe (2a,2b) are dicussed. It is observed that Fe(COT) reacts rapidly with Et3PTe to yield (1). Structural analysis of (1) shows Fe-Te bonding and suggests Fe-FE bonding as well. Heating (1) releases the phosphine and polymerizes the Fe4Te4 unit to produce polycrystalline iron tellurides. X-ray diffraction characterization on the telluride reveals the presence of both 2a and 2b.

Analyzes the composition and chemical states of the tantalum pentoxide or Ta[sub 2]O[sub 5] film in its interface with titanium nitride and tantalum nitride using x-ray photoelectron spectroscopy and Rutherford backscattering spectrometry. Metal-oxide-metal capacitor structures; More effective oxygen-diffusion barriers; Reduction of tantalum pentoxide.

Part I. Describes interfacial reactions and thermal stability between tantalum pentoxide (Ta2O5) and titanium nitride (TiN) as materials for metal-oxide-metal capacitors. Deposition of Ta2O5 films; Specific capacitance and leakage currents due to imperfect interface; Effect of elemental titanium on thermal behavior of Ta2O5. INSET: Special editorial series.