- Preparation of stable and metastable coordination compounds: Insight into the structural, thermodynamic, and kinetic aspects of the formation of coordination polymers
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The reaction of Znl2 and pyrimidine in acetonitrile results in the formation of the 1:2 compound Znl2(pyrimidine)2 (1), which consists of discrete tetrahedral building blocks. Slow heating of 1 at 1°C/min leads to its transformation into the ligand-deficient intermediate 1:1 compound Znl2(pyrimidine) (3), which upon further heating decomposes into the most ligand-deficient 2:1 compound (Znl2) 2(pyrimidine) (4). In contrast, the 2:3 compound (Znl 2)2(pyrimidine)3 (2) is formed as an intermediate by decomposing 1 using a faster heating rate of 8°C/min. Compound 2 consists of oligomeric units in which each Znl2 unit is coordinated by two iodine atoms and one bridging and one terminal pyrimidine ligand. The crystal structure of compound 3 is built up of Znl2 units, which are connected by the ligands into chains. For the thermal transformation of 1 into 3 via 2 as the intermediate, a smooth reaction pathway is found in the crystal structure, for which only small translational and rotational changes are needed. The metastable solvated compound (Znl 2)(pyrimidine)(acetonitrile)0.25 (5) consisting of (Znl2)4(pyrimidine)4 rings is obtained by quenching the reaction of Znl2 and pyrimidine in acetonitrile using an antisolvent. On heating, 5 decomposes into a new polymorphic 1:1 compound 6, which consists of (Znl2)(pyrimidine) chains. On further heating, 6 transforms into a third polymorphic 1:1 compound 7, which consists of (Znl 2)3(pyrimidine)3 rings, and finally into the 1:1 compound 3. Solvent-mediated conversion experiments reveal that compounds 1-4 are thermodynamically stable, whereas compounds 5-7 are metastable. Time-dependent crystallization experiments unambiguously show that compound 7 is formed by kinetic control and transforms within minutes into compound 6, which finally transforms into 3. Compound 3 represents the thermodynamically most stable 1:1 modification, whereas compounds 6 and 7 are metastable. The different compounds obtained by thermal decomposition and by crystallization from solution represent a snapshot of the species in solution and thus provide insight into the formation of coordination compounds.
- Naether, Christian,Bhosekar, Gaurav,Jess, Inke
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- New framework lodoargentates: M(en)3Ag2I4 (M = Zn, Ni) with tridymite topology
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Two novel framework compounds, Zn(en)3Ag2I 4 (1) and Ni(en)3Ag2I4 (2), have been synthesized by a self-assembly reaction. Both of them contain an unexpected framework, Ag2I42- with tridymite topolopy, and the discrete M(en)32+ cations are located in the channels. Their thermal properties and circular dichroism spectra were investigated.
- Jiang, Yan-Si,Yao, Hua-Gang,Ji, Shou-Hua,Ji, Min,An, Yong-Lin
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- Cyclotrimerization of terminal alkynes catalyzed by the system of NiCl 2/Zn and (benzimidazolyl)-6-(1-(arylimino)ethyl)pyridines
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An effective regioselective cyclotrimerization of terminal alkynes is achieved by the direct utilization of NiCl2·6H2O, Zn, and 2-(benzimidazolyl)-6-(1-(arylimino)ethyl)pyridine in one step under ambient temperature.
- Xi, Chanjuan,Sun, Zelin,Liu, Yongbing
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- Synthesis and molecular structure of two zinc complexes of 1,2-bis[(trimethylsilyl)imino]acenaphthene
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The reaction of 1,2-bis[(trimethylsilyl)imino]acenaphthene (1, tms-BIAN) with ZnCl2 and ZnI2 in THF and Et2O afford (tms-BIAN)ZnCl2 (2) and (tms-BIAN)ZnI2 (3), respectively. The compounds 2 and 3 were characterized by IR- and NMR spectroscopy as well as by single crystal X-ray analysis.
- Fedushkin, Igor L.,Skatova, Alexandra A.,Eremenko, Olga V.,Hummert, Markus,Schumann, Herbert
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- Synthesis, crystal structures, and thermal properties of new [ZnX 2(2,5-dimethylpyrazine)] (X = Cl, Br, I) coordination compounds
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Eight new halidozinc(II) coordination compounds with 2,5-dimethylpyrazine as a ligand were prepared. The reaction of ZnX2 (X = Cl, Br, I) and 2,5-dimethylpyrazine in methanol results in the formation of catena-(μ2-2,5-dimethylpyrazin
- Wriedt, Mario,Jess, Inke,Naether, Christian
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- Revealing the structural chemistry of the group 12 halide coordination compounds with 2,2′-bipyridine and 1,10-phenanthroline
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The coordination compounds of group 12 halides with 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen), 2[CdF2(bpy)2]·7H2O (1), [ZnI(bpy)2]+·I3 ? (2), [CdI2(bpy)2] (3), [Cd(SiF6)H2O(phen)2]·[Cd(H2O)2(phen)2]2+·F–·0.5(SiF6)2–·9H2O (4), [Hg(phen)3]2+·(SiF6)2–·5H2O (5), [ZnBr2(phen)2] (6), 6[Zn(phen)3]2+·12Br–·26H2O (7) and [ZnI(phen)2]+·I– (8), have been synthesized and characterized by X-ray crystallography, IR spectroscopy, elemental and thermal analysis. Structural investigations revealed that metal : ligand stoichiometry in the inner coordination sphere is 1 : 2 or 1 : 3. A diversity of intra- and intermolecular interactions exists in structures of 1–8, including the rare halogen?halogen and halogen?π interactions. The thermal and spectroscopic properties were correlated with the molecular structures of 1–8. Structural review of all currently known coordination compounds of group 12 halides with bpy and phen is presented.
- Swiatkowski, Marcin,Kruszynski, Rafal
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p. 642 - 675
(2017/02/05)
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- Stereoselective Retentive Domino Transmetalations of Secondary Alkyllithium Compounds to Functionalized Secondary Alkylcopper Reagents
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Functionalized secondary alkyllithium reagents obtained by I/Li exchange from the corresponding secondary alkyl iodides undergo two successive transmetalations with Me3SiCH2ZnBr.LiBr and CuBr.2LiCl.Me2S to provide functionalized secondary alkylcopper compounds with high retention of configuration. These alkylcopper derivatives react further with electrophiles such as alkynyl esters, acid chlorides, allylic chlorides, ketals, ethylene oxide, and 3-iodocyclopentanone with high retention of configuration. A related sequence of transmetalations with MeMgI and LaCl3.2LiCl allows a retentive addition of secondary alkyllithium reagents to acetone. The influence of the solvent on the configurational stability of secondary alkylzinc reagents is described.
- Moriya, Kohei,Simon, Meike,Mose, Rasmus,Karaghiosoff, Konstantin,Knochel, Paul
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supporting information
p. 10963 - 10967
(2015/09/15)
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- STABILIZED COMPOSITIONS AND METHODS OF MANUFACTURE
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A method for stabilization of potent alkanone-heterocyclic flavorants in dry powder form is provided. Coordination of alkanone-heterocyclic flavorants to transition metal salts results in the formation of stable crystalline complexes, which upon hydration release the free flavorant. Food and topping products containing the stabilized alkanone-heterocyclic flavorant are provided as are methods for stabilizing the alkanone-heterocyclic flavorant.
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Paragraph 0026
(2014/09/30)
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- Novel inhibitors of bacterial virulence: Development of 5,6-dihydrobenzo[h]quinazolin-4(3H)-ones for the inhibition of group A streptococcal streptokinase expression
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Resistance to antibiotics is an increasingly dire threat to human health that warrants the development of new modes of treating infection. We recently identified 1 (CCG-2979) as an inhibitor of the expression of streptokinase, a critical virulence factor in Group A Streptococcus that endows blood-borne bacteria with fibrinolytic capabilities. In this report, we describe the synthesis and biological evaluation of a series of novel 5,6-dihydrobenzo[h] quinazolin-4(3H)-one analogs of 1 undertaken with the goal of improving the modest potency of the lead. In addition to achieving an over 35-fold increase in potency, we identified structural modifications that improve the solubility and metabolic stability of the scaffold. The efficacy of two new compounds 12c (CCG-203592) and 12k (CCG-205363) against biofilm formation in Staphylococcus aureus represents a promising additional mode of action for this novel class of compounds.
- Yestrepsky, Bryan D.,Xu, Yuanxi,Breen, Meghan E.,Li, Xiaoqin,Rajeswaran, Walajapet G.,Ryu, Jenny G.,Sorenson, Roderick J.,Tsume, Yasuhiro,Wilson, Michael W.,Zhang, Wenpeng,Sun, Duxin,Sun, Hongmin,Larsen, Scott D.
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p. 1880 - 1897
(2013/05/08)
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- Zinc-zinc bonded zincocene structures. Synthesis and characterization of Zn2(η5-C5Me5)2 and Zn2(η5-C5Me4Et)2
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While, in general, decamethylzincocene, Zn(C5Me 5)2, and other zincocenes, Zn(C5Me 4R)2 (R = H, But, SiMe3), react with dialkyl and diaryl derivatives, ZnR′2, to give the half-sandwich compounds (η5-C5Me4R) ZnR′, under certain conditions the reactions of Zn(C5Me 5)2 with ZnEt2 or ZnPh2 produce unexpectedly the dizincocene Zn2(η5-C 5Me5)2 (1) in low yields, most likely as a result of the coupling of two (η5-C5Me 5)Zn. radicals. An improved, large scale (ca. 2 g) synthesis of 1 has been achieved by reduction of equimolar mixtures of Zn(C 5Me5)2 and ZnCl2 with KH in tetrahydrofuran. The analogous reduction of Zn(C5Me 4R)2 (R = H, SiMe3, But) yields only decomposition products, but the isotopically labeled dimetallocene 68Zn2(η5-C5Me5) 2 and the related compound Zn2(η5-C 5Me4Et)2 (2) have been obtained by this procedure. Compound 2 has lower thermal stability than 1, but it has been unequivocally characterized by low-temperature X-ray diffraction studies. As for 1 a combination of structural characterization techniques has provided unambiguous evidence for its formulation as the Zn-Zn bonded dimer Zn 2(η5-C5Me4Et)2, with a short Zn-Zn bond of 2.295(3) A indicative of a strong Zn-Zn bonding interaction. The electronic structure and the bonding properties of 1 and those of related dizincocenes Zn2(η5-Cp′)2 have been studied by DFT methods (B3LYP level), with computed bond distances and angles for dizincocene 1 very similar to the experimental values. The Zn-Zn bond is strong (ca. 62 kcal-mol-1 for 1) and resides in the HOMO-4, that has a contribution of Zn orbitals close to 60%, consisting mostly of the Zn 4s orbitals (more than 96%).
- Grirrane, Abdessamad,Resa, Irene,Rodriguez, Amor,Carmona, Ernesto,Alvarez, Eleuterio,Gutierrez-Puebla, Enrique,Monge, Angeles,Galindo, Agustin,Del Rio, Diego,Andersen, Richard A.
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p. 693 - 703
(2007/10/03)
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- Methods and compositions for selectin inhibition
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The present invention relates to the field of anti-inflammatory substances, and more particularly to novel compounds that act as antagonists of the mammalian adhesion proteins known as selectins. In some embodiments, methods for treating selectin mediated disorders are provided which include administration of compound of Formula I: wherein the constituent variables are defined herein.
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Page/Page column 19-20
(2008/06/13)
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- Preparation and structural characterization of bis[tris(trimethylsilyl)-germyl]zinc, [(Me3Si)3Ge]2Zn
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Bis[tris(trimethylsilyl)germyl]zinc, [(Me3Si)3Ge]2Zn, was prepared by the reaction of [tris(trimethylsilyl)germyl]lithium, (Me3Si)3GeLi(thf), with zinc chloride, ZnCl2, and by the reaction of tris(trimethylsilyl)germane, (Me3Si)3GeH, with diethylzinc, Et2Zn. The molecular structure of [(Me3Si)3Ge]2Zn was determined by spectroscopic and X-ray diffraction methods. In [(Me3Si)3Ge]2Zn, the two tris(trimethylsilyl)germyl ligands, (Me3Si)3Ge, are bonded in a linear fashion to the zinc atom and are staggered with respect to each other. The reactions of bis(germyl)zinc with substrates were also examined.
- Nanjo, Masato,Oda, Takashi,Mochida, Kunio
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p. 1261 - 1264
(2007/10/03)
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- The reaction of triorganophosphorus diiodides, R3PI2, with zinc metal powder; Dependency of product on R; The X-ray crystal structures of dimeric {ZnI2[P(NMe2)3]}2 and monomeric ZnI2(PPh2Me)2
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Seventeen zinc(II) tertiary phosphine complexes have been synthesised directly from elemental zinc by reaction with the reagents R3PI2. The complexes have been characterised by elemental analysis and 31P{H} NMR spectroscopy. The present work represents the first comprehensive study of a wide variety of zinc(II) tertiary phosphine complexes containing different parent tertiary phosphines and the majority of the complexes are reported for the first time. In most cases, reaction of R3PI2 with zinc metal powder in diethyl ether in a 1:1 stoichiometric ratio, produces the dimeric complexes [ZnI2(PR3)]2, analogous to the previously reported [ZnI2(PEt3)]2. In contrast, reaction of R3PI2 (R=Ph3, Ph2Et, Ph2Me) with zinc metal powder produces the monomeric bis complexes ZnI2(PR3)2 and an equimolar quantity of zinc(II) iodide, the latter product being identified by X-ray powder diffraction. The X-ray crystal structures of dimeric {ZnI2[P(NMe2)3]}2 and monomeric ZnI2(PPh2Me)2 are also described. The formation of the bis complexes ZnI2(PR3)2 (R3=Ph3, Ph2Me, Ph2Et) is surprising and cannot be due to steric factors since complexes containing less bulky tertiary phosphines are shown to be dimeric and the adoption of a monomeric zinc(II) centre increases steric crowding at the metal atom. The existence of the bis complexes is therefore reasoned to be due to favourable Π-Π interactions on the ligands and crystal packing forces.
- Godfrey, Stephen M.,McAuliffe, Charles A.,Pritchard, Robin G.,Sheffield, Joanne M.
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p. 213 - 219
(2008/10/08)
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