Dihydropyridines in synthesis and biosynthesis. III. Coupling of dihydropyridinetricarbonylchromium(0) complexes: bipyridyls

1982 ◽  
Vol 60 (3) ◽  
pp. 323-326 ◽  
Author(s):  
James P. Kutney ◽  
Lucas Kaczmarek ◽  
Danuta Mostowicz ◽  
Brian R. Worth
Keyword(s):  
Low Temperature ◽  
Crystallographic Analysis ◽  
High Yield ◽  
X Ray ◽  
Methyl Pyridine

Reaction of 1,2- and 1,6-dihydro-3-ethyl-N-methyl pyridine tricarbonylchromium(0) complexes with methyllithium at low temperature afforded a high yield of dimeric tricarbonylchromium(0) complexes. Structures of the latter products were established by X-ray crystallographic analysis. Some chemistry of these novel compounds is described.

scholarly journals Attempted Synthesis and Unexpected β-Fragmentation of a Hindered β-Keto Nitroxide

2017 ◽  
Vol 70 (10) ◽  
pp. 1106 ◽  
Author(s):  
Chris Edwards ◽  
Peter C. Healy ◽  
W. Ken Busfield ◽  
Ezio Rizzardo ◽  
San H. Thang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Ring Opening ◽  
Sodium Tungstate ◽  
Crystallographic Analysis ◽  
High Yield ◽  
Fragmentation Mechanism ◽  
Pentanoic Acid ◽  
X Ray ◽  
Ring Opening Reaction

The attempted synthesis of a β-keto imidazolidinone nitroxide by oxidation of the β-hydroxy imidazolidinone precursor with hydrogen peroxide and sodium tungstate led to an unexpected ring-opening reaction to produce 1,4-diazaspiro[4.5]dec-1-en-3-oxo-2-pentanoic acid 1-oxide (13) in high yield. The structure of 13 was confirmed by X-ray crystallographic analysis. A β-fragmentation mechanism is suggested for the oxidative ring-opening reaction.

The direct electrochemical synthesis of thiolato complexes of cobalt and nickel, and the crystal structure of bis(phenylthiolato)bis(1,10-phenanthroline)cobalt(III) perchlorate

1988 ◽  
Vol 66 (9) ◽  
pp. 2151-2156 ◽  
Author(s):  
Raj K. Chadha ◽  
Rajesh Kumar ◽  
Jaime Romero Lopez-Grado ◽  
Dennis G. Tuck
Keyword(s):  
Crystal Structure ◽  
Electrochemical Oxidation ◽  
Electrochemical Synthesis ◽  
Crystallographic Analysis ◽  
High Yield ◽  
X Ray ◽  
Metal Anode ◽  
Aerial Oxidation ◽  
Perchlorate Salt ◽  
Cobalt And Nickel

Cobalt(II) and nickel(II) thiolates, M(SR)2, can be prepared in high yield by the electrochemical oxidation of a metal anode in an acetonitrile or acetone solution of RSH (R = C6H5, o-CH3C6H4, 2-C10H7, 2,3,4,5-C6F4H; not all combinations). When 2,2-bipyridine or 1,10-phenanthroline (=L) is added to the electrolyte phase, the products are the adducts M(SR)2L2. In the case of Co(SC6H5)2(phen)2, aerial oxidation leads to the formation of the cobalt(III) cation [Co(SC6H5)2(phen)2]+, isolated as the perchlorate salt. X-ray crystallographic analysis showed that this cation has a cis-CoS2(N2)2 kernel.

scholarly journals Synthesis of Some Biologically Important 3-Oxacepham Derivatives

1970 ◽  
Vol 5 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Mohammad Rafiqul Islam ◽  
Mohammad Nurnabi ◽  
AM Sarwaruddin Chowdhury ◽  
Mohammad Mehdi Masud
Keyword(s):  
Key Words ◽  
Full Text ◽  
Crystallographic Analysis ◽  
High Yield ◽  
Methyl Group ◽  
X Ray ◽  
Tert Butyl ◽  
Relative Stereochemistry

The 6H-oxathiazines 1a-e having imine moiety underwent [2+2] cycloaddition with phenoxyacetylchloride in the presence of Et3N to give β-lactam derivatives 2a-e in high yield. The X-ray crystallographic analysis revealed the relative stereochemistry that the substituents at C-2 and C-4 were cis configurated. The subtituents at C-6 and C-7 were also cis to each other. However, the 6H-oxathiazines 1f-i containing tert-butyl or methyl group at C-4 did not undergo the cycloaddition. Key words: Azetedinone, β-lactam, oxacepham, cycloaddition, imine, ketene, oxathiazine. Dhaka Univ. J. Pharm. Sci. Vol.5(1-2) 2006 The full text is of this article is available at the Dhaka Univ. J. Pharm. Sci. website

Organometallic macrocycles and cages based on bis(amidinate) ligands

2014 ◽  
Vol 86 (6) ◽  
pp. 953-965 ◽  
Author(s):  
Ying-Ying Zhang ◽  
Yue-Jian Lin ◽  
Xiao-Chao Shi ◽  
Guo-Xin Jin
Keyword(s):  
Carbon Monoxide ◽  
Low Temperature ◽  
Silver Salt ◽  
High Yield ◽  
Binuclear Complexes ◽  
Cavity Size ◽  
X Ray ◽  
Multinuclear Complexes ◽  
Half Sandwich ◽  
Very High

Abstract A series of half-sandwich iridium-based complexes bearing 1,4-benzenebis (N,N′-dicyclohexylamidine) (H2L1) or 4,4′-bisphenylbis(N,N′-dicyclohexylamidine) (H2L2) has been synthesized and characterized. Treatment of [Cp*IrCl2]2 (Cp* = η5-pentamethyl-cyclo pentadienyl) with deprotonated H2L1 or H2L2 at low temperature resulted in formation of binuclear complexes [Cp*IrCl]2 (L1) and [Cp*IrCl]2(L2). They were chosen as precursors to construct macrocycles and cages. Tetranuclear metallamacrocycles [(Cp*Ir)4(L1)2 (pyrazine)2][OTf]4 and [(Cp*Ir)4(L2)2(pyrazine)2][OTf]4 were assembled by the reaction of complex [Cp*IrCl]2 (L1) or [Cp*IrCl]2(L2) with pyrazine after the removal of chloride from the iridium centers with silver salt AgOTf (OTf = O2SCF3). When 2,4,6-tri(4-pyridyl)-1,3,5-triazine (tpt) is used instead of pyrazine under the same conditions, hexanuclear metallacages [(Cp*Ir)6(L1)3(tpt)2][OTf]6 and [(Cp*Ir)6(L2)3(tpt)2][OTf]6 were formed. Single-crystal X-ray analysis indicated that the cation of complex [(Cp*Ir)4(L1)2 (pyrazine)2][OTf]4 is a rectangular structure, while the cation of complex [(Cp*Ir)4(L2)2(pyrazine)2][OTf]4 is seriously distorted, nearly to a tetrahedral state. Moreover, complexes [(Cp*Ir)6(L1)3(tpt)2][OTf]6 and [(Cp*Ir)6(L2)3(tpt)2][OTf]6 are prism-like cages with large cavity size, which can be prepared in very high yield in the absence of templates. Surprisingly, solutions of multinuclear complexes are very sensitive to carbon monoxide, in which the frameworks were destroyed, giving the binuclear complexes [(Cp*Ir)2(CO)2(L1)][OTf]2 and [(Cp*Ir)2(CO)2(L2)][OTf]2.

Synthesis and Structure of the Potassium Salt with Monodeprotonated 1,2,3-Tri(ethoxycarbonylpropyl)-p-t-butylcalix[6]arene

2008 ◽  
Vol 61 (7) ◽  
pp. 537 ◽  
Author(s):  
Ze-Bao Zheng ◽  
Ren-Tao Wu ◽  
Ji-Kun Li ◽  
Yi-Feng Sun
Keyword(s):  
Potassium Salt ◽  
Crystallographic Analysis ◽  
Potassium Ion ◽  
High Yield ◽  
Cone Conformation ◽  
X Ray ◽  
Partial Cone ◽  
Phenyl Rings ◽  
Close Contacts

Alkylation of p-t-butylcalix[6]arene with ethyl 4-bromobutanoate in the presence of K2CO3 results in a potassium salt of the monodeprotonated 1,2,3-tri(ethoxycarbonylpropyl)-p-t-butylcalix[6]arene in high yield. X-Ray crystallographic analysis shows that this compound exists as a double partial cone conformation. The potassium ion is positioned near the centre of the cavity of the macrocycle and binds to four phenolic oxygens. Close contacts between the potassium ion and phenyl rings observed in this compound are indicative of the presence of the cation–π interaction. The molecules are connected via intermolecular K+···O interactions into infinite chains.

β-octabromo-meso-tris(pentafluorophenyl)corrole: reductive demetalation-based synthesis of a heretofore inaccessible, perhalogenated free-base corrole

2010 ◽  
Vol 14 (06) ◽  
pp. 509-512 ◽  
Author(s):  
Can Capar ◽  
Lars-Kristian Hansen ◽  
Jeanet Conradie ◽  
Abhik Ghosh
Keyword(s):  
Copper Complex ◽  
Free Ligand ◽  
Crystallographic Analysis ◽  
The Other ◽  
High Yield ◽  
Free Base ◽  
X Ray ◽  
The Mean

Long known in various metal-complexed forms, β-octabromo-meso-tris(pentafluorophenyl)corrole, H3[Br8TPFPC ], has not been available as a free ligand until now. It can be prepared in high yield (86%) via reductive demetalation (conc. H2SO4 , FeCl2 ) of Mn[Br8TPFPC ]. Interestingly, the same conditions did not result in demetalation of the analogous copper complex, which may be contrasted to the behavior of many other copper corroles, which demetalate cleanly. X-ray crystallographic analysis revealed a unique "half-saddled" conformation, wherein two of the pyrrole rings on one side of the direct pyrrole-pyrrole linkage are strongly tilted up and down relative to each other, whereas the other two pyrrole rings are roughly in the mean plane of the macrocycle.

Synthesis, characterization, and thermal properties of benzylammonium pentaborate [C6H5CH2NH3][B5O6(OH)4]

2010 ◽  
Vol 75 (9) ◽  
pp. 971-980 ◽  
Author(s):  
Michael A. Beckett ◽  
Peter N. Horton ◽  
Michael B. Hursthouse ◽  
James L. Timmis ◽  
K. Sukumar Varma
Keyword(s):  
Thermal Properties ◽  
Solid State ◽  
Low Temperature ◽  
Boric Acid ◽  
Single Crystal ◽  
High Yield ◽  
Dsc Analysis ◽  
State Structure ◽  
Solid State Structure ◽  
X Ray

[C6H5CH2NH3][B5O6(OH)4] was obtained as colourless crystals in high yield from a MeOH/ H2O (1:1) solution of benzylamine and boric acid (1:5). A single-crystal X-ray study confirmed that the solid-state structure was comprised of a supramolecular H-bonded pentaborate anion lattice, templated by the benzylammonium cations which occupy positions within the lattice cavities. Each pentaborate anion formed 4 H-bonds to 4 neighbouring pentaborate anions at α,α,α,β acceptor sites. Additionally, each cation H-bonds to 3 pentaborate anions. Crystals were monoclinic, P21/c, with a = 9.3511(2) Å, b = 14.5157(4) Å, c = 10.4670(2) Å, β = 90.778(2)°, T = 120 K, V = 1420.64(6) Å3, and Z = 4. TGA/DSC analysis showed that [C6H5CH2NH3][B5O6(OH)4] thermally decomposed in air at 800 °C to 2.5B2O3, via a low-temperature (200–250 °C) dehydration step to a condensed pentaborate.

Low Temperature Synthesis of Nanoscale Magnesium Hydroxide under Normal Pressure

2013 ◽  
Vol 779-780 ◽  
pp. 247-250 ◽  
Author(s):  
Jun Zheng ◽  
Wei Zhou
Keyword(s):  
Low Temperature ◽  
Magnesium Hydroxide ◽  
Normal Pressure ◽  
High Yield ◽  
X Ray Diffraction ◽  
Hexagonal Crystal ◽  
Low Temperature Synthesis ◽  
X Ray ◽  
Transmission Electron ◽  
Wet Chemical

In the present paper, nano-scale magnesium hydroxide has been prepared at low temperature via a wet chemical process using MgCl2· 6H2O (or Mg(NO3)2) and NaOH as the starting reagents under normal pressure. The fresh synthesized magnesium hydroxide nanocrystals were characterized by X-ray diffraction (XRD), selected area electronic diffraction (SAED) and transmission electron microscopy (TEM) measurements. Patterns of XRD and SAED exhibited that the products were high-quality hexagonal crystal system nanocrystals. Though the TEM pictures, large quantities of lamellar-like and needle-like magnesium hydroxide nanocrystals could be observed without obvious aggregation. Using the present method, high yield magnesium hydroxide nanoparticles would be produced without expensive equipments like the high temperature and high-pressure reactor.

trans-Bromocarbonylbis(triphenylphosphine)rhodium

2006 ◽  
Vol 62 (5) ◽  
pp. m1127-m1129 ◽  
Author(s):  
Gideon Steyl ◽  
Leo Kirsten ◽  
Alfred Muller ◽  
Andreas Roodt
Keyword(s):  
Low Temperature ◽  
Title Compound ◽  
Crystallographic Analysis ◽  
X Ray ◽  
Type Compound

The title compound, [RhBr(C18H15P)2(CO)], can be characterized as a rhodium(I) Vaska-type compound based only on the spectroscopic [νKBr(CO), 31P] data. A low-temperature X-ray crystallographic analysis shows that the compound possesses a crystallographically imposed centre of symmetry with a statistically disordered Br atom and CO group. The essentially different occupancies for the Br atom and the CO group [0.283 (2) and 0.717 (2), respectively] suggest that the compound exists as a mixture of rhodium(0), rhodium(I) and rhodium(II) complexes.

Quaternary structure of Limulus polyphemus hemocyanin

1978 ◽  
Vol 36 (2) ◽  
pp. 176-177
Author(s):  
T. Wichertjes ◽  
E.J. Kwak ◽  
E.F.J. Van Bruggen
Keyword(s):  
Electron Microscopy ◽  
Functional Properties ◽  
Horseshoe Crab ◽  
Temperature Jump ◽  
Quaternary Structure ◽  
Crystallographic Analysis ◽  
Limulus Polyphemus ◽  
Oxygen Binding ◽  
X Ray ◽  
Intact Molecule

Hemocyanin of the horseshoe crab (Limulus polyphemus) has been studied in nany ways. Recently the structure, dissociation and reassembly was studied using electron microscopy of negatively stained specimens as the method of investigation. Crystallization of the protein proved to be possible and X-ray crystallographic analysis was started. Also fluorescence properties of the hemocyanin after dialysis against Tris-glycine buffer + 0.01 M EDTA pH 8.9 (so called “stripped” hemocyanin) and its fractions II and V were studied, as well as functional properties of the fractions by NMR. Finally the temperature-jump method was used for assaying the oxygen binding of the dissociating molecule and of preparations of isolated subunits. Nevertheless very little is known about the structure of the intact molecule. Schutter et al. suggested that the molecule possibly consists of two halves, combined in a staggered way, the halves themselves consisting of four subunits arranged in a square.

Sign in / Sign up

Export Citation Format

Share Document