New Heteroleptic Cobalt Precursors for Deposition of Cobalt-Based Thin Films

A new series of heteroleptic complexes of cobalt were synthesized using aminoalkoxide and ??-diketonate ligands. The complexes, [Co(dmamp)(acac)]2 (3), [Co(dmamp)(tfac)]2 (4), [Co(dmamp)(hfac)]2 (5), [Co(dmamp)(tmhd)]2 (6), and [Co(dmamb)(tmhd)]2 (7), were prepared by two-step substitution reactions and studied using Fourier transform infrared spectroscopy, mass spectrometry, elemental analysis, and thermogravimetric analysis (TGA). Complexes 3-7 displayed dimeric molecular structures for all of the complexes with cobalt metal centers interconnected by ??2-O bonding by the alkoxy oxygen atom. TGA and a thermal study of the complexes displayed high volatilities and stabilities for complexes 6 and 7, with sublimation temperatures of 120 ??C/0.5 Torr and 130 ??C/0.5 Torr, respectively

Synthesis, characterization and reactivity of oxothiomolybdates and their reactions toward sulfur dioxide.

The facile addition reaction of sulfur dioxide, SO\sb2, into the Mo(O)(S) group, depending on reaction conditions, afforded a multitude of products which contain the thiosulfite, thiosulfate, sulfite and sulfate dianions as bidentate chelating ligands terminally bound to the Mo atom. The reaction of (\rm Et\sb4N)\lbrack (CP)Mo(O)(\mu-\rm S)\sb2Mo(O)(S)) with SO\sb2 monitored by \sp1H NMR spectroscopy (Cp\sp- protons) in a SO\sb2 saturated, \rm CH\sb3CN-d\sb3 solution in a sealed NMR tube over a period of time produces various complexes as products. The \sp1H NMR spectra and structures of these ((Cp)Mo(O)($\mu$-S)\sb2Mo(O)(L)) \sp- complexes where L = SO\sb3\sp{2-}, S\sb2O\sb3\sp{2-} and SO\sb4\sp{2-} are described in detail. The reaction of SO\sb2 with the (\rm Mo\sb2O\sb2S\sb2(S\sb{n})(S\sb{n\sp\prime})\rbrack \sp{2-} complexes (n = 2,4 and n\sp\prime = 1,2) produces the (\rm Mo\sb2O\sb2S\sb2(S\sb2O\sb3)\sb2\rbrack \sp{2-} complex through the (\rm Mo\sb2O\sb2S\sb2(S\sb2O\sb3)(S\sb4)\rbrack \sp{2-} and (\rm Mo\sb2O\sb2S\sb2(S\sb2O\sb3)(S\sb2O\sb2)\rbrack \sp{2-} intermediate complexes. The reaction of the (\rm Mo\sb2O\sb2S\sb2(S\sb4)(S)\rbrack \sp{2-} and (\{\rm Mo\sb2O\sb2S\sb2(S\sb4)(S)\}\sb2\rbrack \sp{4-} complexes with excess NaHSO\sb3 in a dimethyl formamide/water mixture yields (\rm Mo\sb2O\sb2S\sb2(S\sb2)(S\sb2O\sb3)\rbrack \sp{2-}. The S,O mixed bridged (\rm Mo\sb2O\sb2(\mu-S)($\mu$-O)(S\rm \sb2O\sb3)(S\sb2O\sb3)\rbrack \sp{2-} complex is synthesized from the reaction of SO\sb2 with (\rm MoO\sb2S\sb2\rbrack \sp{2-} and characterized. Ligand substitution reactions for this complex are discussed. The thermal reaction of SO\sb2 with the (Et\sb4N)\sp+ salts of (\rm Mo\sb2O\sb2S\sb2(S\sb{n}(S\sb{n\sp\prime})rlbrack \sp{2-} complexes (n = 2,4 and n\sp\prime = 1,2) in dimethyl formamide yields the tetrameric (\{(\rm SO\sb4)Mo(O)(\mu-S)\rm sb2Mo(O)(SO\sb4)\}\sb2(\mu\sb4-SO\sb4)\rbrack\sp{6-} complexes. These complexes contain a unique \mu\sb4-SO\sb4\sp{2-} ligand which is unprecedented in coordination chemistry of the SO\sb4\sp{2-} ligand. The structures, spectroscopic properties and ligand substitution reactions of these complexes are described in detail. The synthesis and characterization of the mononuclear Mo complexes (\rm Mo\sp{VI}(O)(S\sb2)\sb2(C\sb6H\sb5COS)\rbrack \sp-, \rm\lbrack Mo\sp{V}(O)Cl\sb5\rbrack\sp{2-}, \rm\lbrack Mo\sp{VI}(O)\sb2(Cl\sb2)(C\sb6Cl\sb4O\sb2)\rbrack \sp{2-}, \lbrack Mo(O)(S\sb2C\sb2(CN)\sb2)\sb2\rbrack \sp{2-} and (\rm Mo\sp{VI}(O)\sb2(C\sb6Cl\sb4O\sb2)\sb2\rbrack \sp{2-} are described in detail.Ph.D.ChemistryUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/103788/1/9409728.pdfDescription of 9409728.pdf : Restricted to UM users only

Synthesis of new heteroleptic strontium complexes

A series of heteroleptic strontium complexes (1-9) using a combination of different aminoalkoxides and 2,2,6,6-tetramethyl-3,5-heptanedionate (tmhd) were prepared to examine the effect of the bulkiness and coordination ability of the aminoalkoxide ligand in these complexes as well as potential strontium precursors. All complexes were characterized by FT-IR, FT-NMR, elemental analyses, and thermo-gravimetric (TG) analyses. The crystal structure analyses of 1, 2, 4, and 5 demonstrate their stability in the dimer form and the unwillingness of the strontium atom to form more than six coordination bonds in these complexes. The complex 5 shows an unusual picture: the existence of one hexa-coordinated and one penta-coordinated strontium atom side by side in its dimer structure. The introduction of ether groups as coordination sites in complexes 6-9 led to a decrease in steric hindrance which resulted in the formation of the complex 7 as a tetramer. The complex 7 shows a unique Sr4O4cubane core where oxygen atoms undergo ??3-bridging between strontium atoms. The TG analyses show that the complexes exhibit a step-wise decomposition character, with the major mass losses in the region 150-400 ??C. © 2014 the Partner Organisationsclose

PROPERTIES OF COPPER LAYER ON Si(100) FROM Cu(dmamb)2

Cu seed layer was deposited by chemical vapor deposition using new Cu precursor, Cu(dmamb)2. The Cu layers still need the barrier layer to prevent the diffusion, so Ta and Ti were used for the barrier layer on Si(100). Low temperature (LT) copper buffer layer was introduced and the effect of the buffer on the Cu films was investigated. The grown Cu layers were analyzed using FESEM, XRD, and four point probe measurement. The Cu seed layers were successfully deposited using Cu(dmamb)2 precursor. Better thickness uniformity was obtained in the Cu films with the LT Cu buffer, which lowered the electrical resistivity.CVD, buffer layer, barrier layer, Cu(dmamb)2, diffusion

Synthesis of 1T WSe2 on an Oxygen-Containing Substrate Using a Single Precursor

The metallic property of metastable 1T' WSe2 and its promising catalytic performance have attracted considerable interest. A hot injection method has been used to synthesize 1T' WSe2 with a three-dimensional morphology; however, this method requires two or more precursors and long-chain ligands, which inhibit the catalytic performance. Here, we demonstrate the synthesis of 1T' WSe2 on a substrate by a simple heating-up method using a single precursor, tetraethylammonium tetraselenotungstate [(Et4N)(2)WSe4]. The triethylamine produced after the reaction is an electron donor that yields negatively charged WSe2, which is stabilized by triethylammonium cations as intercalants between layers and induces 1T' WSe2. The purity of 1T' WSe2 is higher on oxygen-containing crystalline substrates than amorphous substrates because the strong adhesion between WSe2 and the substrate can produce sufficient triethylammonium (TEA) intercalation. Among the oxygen-containing crystal substrates, the substrate with a lower lattice mismatch with 1T' WSe2 showed higher 1T' purity due to the uniform TEA intercalation. Furthermore, 1T' WSe2 on carbon cloth exhibited a more enhanced catalytic performance in the hydrogen evolution reaction (197 mV at 10 mA/cm(2)) than has been reported previously

Heteroleptic strontium complexes stabilized by donor-functionalized alkoxide and beta-diketonate ligands

Heteroleptic complexes of strontium (1-7) were prepared by employing beta-diketonates and donor-functionalized alkoxides as coordinating ligands. The results illustrate the effect of alkoxide substituent groups on the overall structures of the complexes. The presence of a terminal methoxy group in the alkoxide ligands leads to the formation of trimeric complexes 1-4, whereas the substituents on the amine nitrogen prove to have less influence in determining the structure. The attempts to increase steric bulkiness of the aminoalkoxide ligands by introducing ethyl groups on the amine nitrogen and to the alkoxy carbon did not lead to a structural change from the dimeric form in 5-7 but resulted in structurally interesting strontium complexes. In trimeric complexes 2-4, the three strontium atoms were held together by two mu(3)-O bonds using alkoxide oxygen atoms and two mu(2)-O bonds using a combination of alkoxide and beta-diketonate ligand oxygens. The strontium metal centers in these complexes exhibit seven-coordination states in 2 and 4, whereas 3 exhibits one six-coordinated and two seven-coordinated strontium metals in its structure. All of the complexes were characterized using FT-NMR, FT-IR, elemental analyses, and thermogravimetric (TG) analysesclose0

Growth of p‑Type Tin(II) Monoxide Thin Films by Atomic Layer Deposition from Bis(1-dimethylamino-2-methyl-2propoxy)tin and H₂O

Growth of p‑Type Tin(II) Monoxide Thin Films by Atomic Layer Deposition from Bis(1-dimethylamino-2-methyl-2propoxy)tin and H₂

Germanium Compounds Containing GeE Double Bonds (E = S, Se, Te) as Single-Source Precursors for Germanium Chalcogenide Materials

New germanium chalcogenide precursors, SGe­(dmamp)₂ (<b>3</b>), SGe­(dmampS)₂ (<b>4</b>), SeGe­(dmamp)₂ (<b>5</b>), SeGe­(dmampS)₂ (<b>6</b>), TeGe­(dmamp)₂ (<b>7</b>), and TeGe­(dmampS)₂ (<b>8</b>), were synthesized from Ge­(dmamp)₂ (<b>1</b>) and Ge­(dmampS)₂ (<b>2</b>) using sulfur, selenium, and tellurium powders (dmamp = 1-dimethylamino-2-methyl-2-propanolate, dmampS = 1-dimethylamino-2-methylpropane-2-thiolate). Complexes <b>1</b> and <b>2</b> were synthesized from metathesis reactions of GeCl₂·dioxane with 2 equiv of aminoalkoxide or aminothiolate ligands. Thermogravimetric analysis of complex <b>1</b> displayed good thermal stability and volatility. The molecular structures of complexes <b>2</b>–<b>8</b> from X-ray single crystallography showed distorted trigonal bipyramidal geometry at the germanium centers. Germanium chalcogenide materials (GeSe and GeTe) were obtained from the thermal decomposition of complexes <b>5</b>, <b>6</b>, and <b>8</b> in hexadecane. X-ray diffraction patterns exhibited that GeSe and GeTe had orthorhombic and rhombohedral phases, respectively. This study affords a facile method to easily prepare germanium chalcogenide materials using well-designed and stable complexes by thermal decomposition of single-source precursors in solution