- Deciphering ligands' interaction with Cu and Cu2O nanocrystal surfaces by NMR solution tools
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The hydrogenolysis of [Cu2{(iPrN)2(CCH3)}2] in the presence of hexadecylamine (HDA) or tetradecylphosphonic acid (TDPA) in toluene leads to 6-9 nm copper nanocrystals. Solution NMR spectroscopy has been used to describe the nanoparticle surface chemistry during the dynamic phenomenon of air oxidation. The ligands are organized as multilayered shells around the nanoparticles. The shell of ligands is controlled by both their intermolecular interactions and their bonding strength on the nanocrystals. Under ambient atmosphere, the oxidation rate of colloidal copper nanocrystals closely relies on the chemical nature of the employed ligands (base or acid). Primary amine molecules behave as soft ligands for Cu atoms, but are even more strongly coordinated on surface CuI sites, thus allowing a very efficient corrosion protection of the copper core. On the contrary, the TDPA ligands lead to a rapid oxidation rate of Cu nanoparticles and eventually to the re-dissolution of CuII species at the expense of the nanocrystals.
- Glaria, Arnaud,Cure, J??r??my,Piettre, Kilian,Coppel, Yannick,Turrin, C??dric-Olivier,Chaudret, Bruno,Fau, Pierre
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- Preparation of all N-coordinated zirconium amide amidinates and studies of their reactions with dioxygen and water
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Zr(NR2)2[MeC(NiPr)2]2 (R = Me, 1; Et, 2) have been prepared through aminolysis and their reactions with O2 and water have been studied. Two major products from the reactions are the oxo dimer {(μ-O)Zr[MeC(NiPr)2]2}2 (3) and its insoluble polymer {(μ-O)Zr[MeC(NiPr)2]2}n (4). Over time the dimer 3 polymerizes to 4. Zr peroxo trimer {(μ-η2:η2-O2)Zr[MeC(NiPr)2]2}3 (5) was also observed from the reaction of 1 with O2 and its crystal structure is reported. DFT calculations show that the reaction of 1 with O2 follows a radical process, yielding the peroxo trimer 5. Mass spectrometric studies of the reactions of water in air with 1 and 2 show the formation of the oxo monomer (O=)Zr[MeC(NiPr)2]2 (6), oxo dimer {(μ-O)Zr[MeC(NiPr)2]2}2 (3), and the dihydroxy monomer (HO)2Zr[MeC(NiPr)2]2 (7). In addition, the cations {Zr(NR2)[MeC(NiPr)2]2}+ (R = Me, Et) were observed. 2 revealed an interesting dynamic NMR behavior. Variableerature (VT) NMR spectroscopy has been used to study the Bailar twist process in 2, giving activation parameters ΔH? = 10.9(1.1) kcal mol-1, ΔS? = -11(4) eu and ΔG?303 K = 14(2) kcal mol-1.
- Lamb, Adam C.,Wang, Zheng,Cook, Tabitha M.,Sharma, Bhavna,Chen, Shu-Jian,Lu, Zheng,Steren, Carlos A.,Lin, Zhenyang,Xue, Zi-Ling
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- Comparison of Ligand Architecture on Vapor Deposition Precursors: Synthesis, Characterization, and Reactivity of Volatile Cadmium Bis-Amidinate Complexes
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The lack of low-temperature (a limitation for cadmium chalcogenide ALD. Here, the cadmium amidinate system is presented as a scaffold for vapor deposition precursor design because the alkyl groups can be altered to change the properties of the precursor. Thus, the molecular structure affects the precursor stability at elevated temperature, onset of volatility, and reactivity. Cadmium bis-N,N-diisopropylacetamidinate (1) was synthesized and evaluated for its thermal stability, volatility, and reactivity-properties relevant to ALD precursors. Compounds 2, cadmium bis-N,N-diisopropyltertertiarybutylamidinate, and 3, cadmium bis-N,N-diisopropylbutylamidinate, are analogous to 1 and were synthesized by substituting the alkyl group on the bridging carbon during amidinate synthesis. All three compounds are volatile under reduced pressure, and thermal stability studies showed 1 and 3 to be stable at 100 °C in solution for days to weeks, while 2 decomposed at 100 °C within 24 h. Solution phase reactivity studies show 1 to be reactive with thiols at room temperature in a stoichiometric manner. No reactivity with either bis-silyl sulfides or alkyl sulfides was observed up to 110 °C over more than 3 days. Overall, the cadmium amidinate compounds presented here show potential as precursors in ALD/CVD processing, which can contribute to research critical for semiconductor processing.
- Foody, Michael J.,Weimer, Matthew S.,Bhandari, Harish,Hock, Adam S.
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- METAL-CONTAINING COMPOUND, PROCESS FOR PRODUCING THE SAME, METAL-CONTAINING THIN FILM, AND METHOD OF FORMING THE SAME
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A compound which has thermal stability and moderate vaporizability and is satisfactory as a material for the CVD or ALD method; a process for producing the compound; a thin film formed from the compound as a raw material; and a method of forming the thin film. A compound represented by the general formula (1) is produced by reacting a compound represented by the general formula (2) with a compound represented by the general formula (3). The compound produced is used as a raw material to form a metal-containing thin film. [Chemical formula 1] (1) [Chemical formula 2] (2) [Chemical formula 3] Mp(NR4R5)q (3) (In the formulae, M represents a Group 4 element, aluminum, gallium, etc.; n is 2 or 3 according to cases; R1 and R3 each represents C1-6 alkyl, etc.; R2 represents C1-6 alkyl, etc.; R4 and R5 each represents C1-4 alkyl, etc.; X represents hydrogen, lithium, or sodium; p is 1 or 2 according to cases; and q is 4 or 6 according to cases.)
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Page/Page column 11
(2010/11/25)
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- Use of Lanthanide(III) Ions as Catalysts for the Reactions of Amines with Nitriles
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Catalytic amounts of lanthanide(III) triflates promote reactions between amines and nitriles leading to a variety of products.The Ln3+ ions activate weakly coordinating nitriles at large amine: Ln3+ mole ratios, even in the presence of amines that form thermodynamically stable complexes with Ln3+ ions.The reactions involving primary monoamines and diamines appear to be general and provide a viable synthetic route to N,N'-disubstituted amidines (2) and cyclic amidines (4), respectively.Symmetrically substituted triazines (8 or 9) are observed as byproducts in some of these systems when the reactions are carried out by using excess nitrile.Secondary alicyclic amines or dimethylamine reacts with acetonitrile to yield pyrimidines (6) and 2,4,6-trimethyl-s-triazine (8).Two routes to triazine have been proposed, one involving the reaction of ammonia with the nitrile and the second involving the reaction of an amidine (1 or 5) with the nitrile.The ability of Ln3+ ions to activate nitriles under conditions that oppose nitrile coordination is attributed to the lability of Ln3+ complexes derived from N-donors.
- Forsberg, John H.,Spaziano, Vincent T.,Balasubramanian, Trichey M.,Liu, Gordon K.,Kinsley, Steven A.,et al.
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p. 1017 - 1021
(2007/10/02)
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