Synthesis and Characterization of Barium Fluoro-beta-ketoiminate Complexes Having Appended Polyether "Lariats"

A facile approach to C-functionalized β-ketoimine compounds via terminal alkylation of a tetralithiated intermediate

A series of C-functionalized β-ketoimine compounds at the terminal methyl groups of the β-ketoimine precursor L^phH₂ (L^ph = C₆H₄[NC(Me)CHC(Me)O]₂) were prepared. This convenient transformation was realized via straightforward double alkylation on the terminal C_α of a novel bis-dianionic β-ketoiminate lithium complex [L^ph'Li₄(THF)₄]₂ (L^ph' = C₆H₄[NC(Me)CHC(O)CH₂]₂) followed by hydrolysis.

Crystalline oxides on silicon

This review outlines developments in the growth of crystalline oxides on the ubiquitous silicon semiconductor platform. The overall goal of this endeavor is the integration of multifunctional complex oxides with advanced semiconductor technology. Oxide epitaxy in materials systems achieved through conventional deposition techniques is described first, followed by a description of the science and technology of using atomic layer-by-layer deposition with molecular beam epitaxy (MBE) to systematically construct the oxide-silicon interface. An interdisciplinary approach involving MBE, advanced real-space structural characterization, and first-principles theory has led to a detailed understanding of the process by which the interface between crystalline oxides and silicon forms, the resulting structure of the interface, and the link between structure and functionality. Potential applications in electronics and photonics are also discussed.

Novel analogues of degarelix incorporating hydroxy-, methoxy-, and pegylated-urea moieties at positions 3, 5, 6 and the N-terminus. Part III

Novel degarelix (Fe200486) analogues were screened for antagonism of GnRH-induced response (IC(50)) in a reporter gene assay. Inhibition of luteinizing hormone release over time was measured in the castrated male rat. N(omega)-Hydroxy- and N(omega)-methoxy-carbamoylation of Dab and Dap at position 3 (3-6), and N(omega)-hydroxy-,N(omega)-methoxy-carbamoylation and pegylation of 4Aph at positions 5 and 6 (7-10, 15-17, 22-25) were carried out. Modulation of hydrophobicity was achieved using different acylating groups at the N-terminus (11-14, 18-21, 26-28). Analogues 8, 15-17, 22, and 23 were equipotent to acyline (IC(50) = 0.69 nM) and degarelix (IC(50) = 0.58 nM) in vitro. Analogues 7, 17, and 23 were shorter acting than acyline, when 9, 11, 13, 15, 16, and 22 were longer acting. Only 9 and 14 were inactive at releasing histamine. No analogue exhibited a duration of action comparable to that of degarelix. Analogues with shorter and longer retention times on HPLC (a measure of hydrophilicity) than degarelix were identified.

Synthesis and characterization of zinc AP-MOCVD precursors and their utility in the growth of ZnO

A novel beta-ketoimine, 4-N-(n-butylamino)-3-penten-2-one (1), and beta-enaminoester, Ethyl 3-N-(isopropylamino)-2-butenoate (2), were synthesized by the reaction of the 2,4-pentanedione or ethyl 3-oxo butanoate with the n-butyl and isopropyl amine, respectively. The isolated free ligands 1 and 2 were reacted with diethylzinc to afford Zn(CH3C(NCH2CH2CH2CH3)CHCOCH3)2 (3) and Zn(CH3C(NCH(CH3)2)CHC(O)OCH2CH3)2 (4) respectively. The isolated zinc complexes, 3 and 4, were characterized by elemental analysis, NMR, and MALDI-TOFMS. The molecular structure of 3 and 4 were determined via single crystal X-ray diffraction which revealed both compounds to be four coordinate, monomeric and homoleptic in the solid state. TG analysis showed the air stable compounds to be thermally robust as they both sublimed in a one-step process at atmospheric pressure. The compounds were utilized in the growth of ZnO via AP-MOCVD in the absence of additional oxidant. The carbon content of the film grown from 3 as determined by XPS was 26.2% while that of the film grown by 4 was 8.71%.

Synthesis and characterization of volatile, fluorine-free beta-ketoiminate lanthanide MOCVD precursors and their implementation in low-temperature growth of epitaxial CeO(2) buffer layers for superconducting electronics

A new class of volatile, low-melting, fluorine-free lanthanide metal-organic chemical vapor deposition (MOCVD) precursors has been developed. The neutral, monomeric Ce, Nd, Gd, and Er complexes are coordinatively saturated by a versatile, multidentate ether-functionalized beta-ketoiminato ligand series, the melting point and volatility characteristics of which can be tuned by altering the alkyl substituents on the keto, imino, and ether sites of the ligand. Direct comparison with conventional lanthanide beta-diketonate complexes reveals that the present precursor class is a superior choice for lanthanide oxide MOCVD. Epitaxial CeO(2) buffer layer films can be grown on (001) YSZ substrates by MOCVD at significantly lower temperatures (450-650 degrees C) than previously possible by using one of the newly developed cerium beta-ketoiminate precursors. Films deposited at 540 degrees C have good out-of-plane (Deltaomega = 0.85 degrees ) and in-plane (Deltaphi = 1.65 degrees ) alignment and smooth surfaces (rms roughness approximately 4.3 A). The film growth rate decreases and the films tend to be smoother as the deposition temperature is increased. High-quality yttrium barium copper oxide (YBCO) films grown on these CeO(2) buffer layers by pulsed organometallic molecular beam epitaxy exhibit very good electrical transport properties (T(c) = 86.5 K, J(c) = 1.08 x 10(6) A/cm(2) at 77.4 K).

A logical concept of structure prediction derived from supramolecular polymers of alkaline Earth metal halides formed by hydrogen bonding and complexation of the metal ion

Several different dimensional polymers derived from alkaline earth metal iodides are obtained as a result of supramolecular noncovalent bonding modes of the metal ion, namely complexation and hydrogen bonding. These polymers consist of complex cations linked to the halide ions by hydrogen bonds of the water ligands coordinated to the metal. They are built up in a logical way, depending on the ratio of complexing ligands to complexing and hydrogen-bonding ligands so that their dimensionality and, to a certain extent, their structure can be predicted.

Ancillary ligand effect on the properties of "Mg(thd)2" and crystal structures of [Mg(thd)2(ethylenediamine)]2, [Mg(thd)2(tmeda)], and [Mg(thd)2(trien)]

Complexes [Mg(thd)2(A)] (Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione; A = ethylenediamine, en (2); N,N'-dimethylethylenediamine, dmeda (3); N,N'-diethylethylenediamine, deeda (4); N,N,N',N'-tetramethylethylenediamine, tmeda (5); diethylenetriamine, dien (6); triethylenetetra-amine, trien (7); 1,2-ethanediol (8)) and [Mg(thd)2(EtOH)]2(1,3-propanediol) (9) were prepared and characterized by NMR spectroscopy, mass spectrometry, and thermal analysis. Crystal structures of compounds 2, 5, and 7 are presented. In all structures, Mg exhibits distorted six-coordination, with four shorter distances between Mg and keto-oxygens and two longer distances between Mg and nitrogen atoms (2, 5, 7). The structure of 2 consists of two monomeric complexes which form an asymmetric unit. The structure of 7 is similar to 2, but the trien molecule has coordinated through one terminal and one vicinal N atom to Mg. All complexes containing amines evaporated almost completely, but the complex 8, which contained 1,2-ethanediol, was thermally unstable and decomposed when heated. At temperatures below the dissociation temperature, all adducts of diamines appeared to evaporate intact.

Encapsulating bis(beta-ketoiminato) polyethers. Volatile, fluorine-free barium precursors for metal-organic chemical vapor deposition

The synthesis, characterization, and incorporation in volatile metal-organic chemical vapor deposition (MOCVD) precursors of a new class of linked beta-ketoiminate-polyether-beta-ketoiminate ligands is presented. These ligands are designed to encapsulate alkaline-earth cations having low charges and large ionic radii. Barium complexes having the general formula Ba[(RCOCHC(R')N)2(R")] (R = tert-butyl or CF3; R' = tert-butyl, methyl, or CF3; R" = -(CH2CH2O)4CH2CH2- or -(CH2CH2O)5CH2CH2)-) were prepared and characterized by 1H and 13C NMR spectroscopy, elemental analysis, and mass spectrometry. Single-crystal X-ray diffraction analysis of 2,2,5,25,28,28-hexamethyl-9,12,15,18,21-pentaoxa-4,25-diene-6,24- diimino-3,27-pentacosadionatobarium(II) reveals a monomeric, nine-coordinate, tricapped trigonal prismatic coordination geometry. Single-crystal X-ray structural analysis of 1,1,1,24,24,24-hexafluoro-4,21-ditrifluoromethyl-8,11,14,17- tetraoxa-3,21-diene-5,20-diimino-2,23-tetracosadionatobarium(II).2DMSO reveals a monomeric, ten-coordinate, distorted tetracapped trigonal prismatic coordination geometry. Volatility data are presented for these barium complexes, demonstrating viability as MOCVD precursors. In addition, it is demonstrated that thin epitaxial films of BaTiO3 can be grown on (001) MgO by low-pressure MOCVD techniques using one of these barium complexes and Ti(dipivaloylmethanate)2(isopropoxide)2 as precursors.