scholarly journals Hydrolysis of Scandium Alkyl Derivatives Supported by a Pentadentate Diborate Ligand: Interconversion of Hydroxo and Oxo Complexes

2019 ◽  
Author(s):  
Daniel W. Beh ◽  
Warren Piers ◽  
Laurent Maron ◽  
Yan Yang ◽  
Benjamin S. Gelfand ◽  
...  
Keyword(s):  
Solid State ◽  
Hydroxo Complex ◽  
Ambient Atmosphere ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrolysis Products ◽  
Alkyl Derivatives ◽  
Rapid Formation ◽  
Hydrolysis Of ◽  
Pentadentate Ligand

Uncontrolled reaction of water with scandium alkyls (compounds <b>1-R</b>) supported by a dianionic, pentadentate ligand leads to rapid formation of an oxo-bridged dimer (<b>2</b>). Solid state samples can be exposed to ambient atmosphere to generate samples enriched in the bridging dihydroxo dimer <b>3</b>, which slowly converts to the m-oxo species with elimination of water. DFT computations show that <b>3</b> is actually more thermodynamically stable than <b>2</b>, but the reactivity of <b>3</b> with the water eliminated leads to its decomposition to <b>2</b> and several hydrolysis products. Some of these products were characterized by X-ray crystallography, specifically a hexameric scandium dihydroxo cluster (<b>4</b>) in which the pentadentate ligand has partially demetallated. Attempts to synthesize hydroxo complex <b>3</b> by protonation of <b>2</b> also lead to hydrolysis products.

scholarly journals Hydrolysis of Scandium Alkyl Derivatives Supported by a Pentadentate Diborate Ligand: Interconversion of Hydroxo and Oxo Complexes

2019 ◽  
Author(s):  
Daniel W. Beh ◽  
Warren Piers ◽  
Laurent Maron ◽  
Yan Yang ◽  
Benjamin S. Gelfand ◽  
...  
Keyword(s):  
Solid State ◽  
Hydroxo Complex ◽  
Ambient Atmosphere ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrolysis Products ◽  
Alkyl Derivatives ◽  
Rapid Formation ◽  
Hydrolysis Of ◽  
Pentadentate Ligand

Uncontrolled reaction of water with scandium alkyls (compounds <b>1-R</b>) supported by a dianionic, pentadentate ligand leads to rapid formation of an oxo-bridged dimer (<b>2</b>). Solid state samples can be exposed to ambient atmosphere to generate samples enriched in the bridging dihydroxo dimer <b>3</b>, which slowly converts to the m-oxo species with elimination of water. DFT computations show that <b>3</b> is actually more thermodynamically stable than <b>2</b>, but the reactivity of <b>3</b> with the water eliminated leads to its decomposition to <b>2</b> and several hydrolysis products. Some of these products were characterized by X-ray crystallography, specifically a hexameric scandium dihydroxo cluster (<b>4</b>) in which the pentadentate ligand has partially demetallated. Attempts to synthesize hydroxo complex <b>3</b> by protonation of <b>2</b> also lead to hydrolysis products.

scholarly journals The synthesis and X-ray structures of the geometric isomers of 1-amino-1,2-cyclopentanedicarboxylic acid

1993 ◽  
Vol 71 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Kenneth Curry ◽  
Hugh McLennan ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Elevated Temperatures ◽  
Geometric Isomers ◽  
X Ray ◽  
X Ray Crystallography ◽  
Hydrolysis Products ◽  
Hydrolysis Of ◽  
Cis Isomer ◽  
C Nmr

The geometric isomers of 1-amino-1,2-cyclopentanedicarboxylic acid were isolated as the hydrolysis products of 2-cyclopentanecarboxylic acid-5,5′-hydantoin. The hydantoin ester was formed from ethyl -2-oxocyclopentanecarboxylate via a Bucherer–Bergs reaction. Hydrolysis of the hydantoin at elevated temperatures gave a mixture of trans- and cis-1 -amino-1,2-cyclopentanedicarboxylic acids indicating epimerization during hydrolysis. The trans product has not been described previously and the cis not extensively characterized. X-ray crystallography reveals that both isomers are zwitterionic in the solid state and the cis isomer molecules are linked by unusually strong hydrogen bonding. Structures were confirmed by 13C NMR, X-ray crystallography, and elemental analysis. Physical data are also presented.

Synthesis, characterization, and reactivity of the first hafnium alkyl complex stabilized by amidate ligands

2005 ◽  
Vol 83 (6-7) ◽  
pp. 1037-1042 ◽  
Author(s):  
Robert K Thomson ◽  
Brian O Patrick ◽  
Laurel L Schafer
Keyword(s):  
Coordination Chemistry ◽  
Solid State ◽  
Key Words ◽  
Low Temperatures ◽  
Variable Temperature ◽  
X Ray ◽  
X Ray Crystallography ◽  
Exchange Processes ◽  
Hydrolysis Of

A photo and thermally stable bis(amidate)–dibenzyl complex of Hf ([DMP(NO)Ph]2Hf(CH2Ph)2(THF) (2a) was formed as a monosolvated THF adduct in near quantitative yield from Hf(CH2Ph)4 and N-2,6-dimethylphenyl(phenyl)amide (1). Isomerization between the THF-bound product and the THF-free product can be observed visually by the conversion from a red-orange product at low temperatures to a pale yellow product at high temperatures. Solid-state crystallographic characterization of the orange product confirmed its constitution as a monosolvated species. Kinetic parameters for the exchange of the THF moiety were determined from variable-temperature NMR experiments. The product of the hydrolysis of the Hf dibenzyl species by water was characterized by X-ray crystallography, and was found to be a rare tetrametallic Hf oxo cluster species (3).Key words: hafnium, protonolysis, amidate, coordination chemistry, organometallic chemistry, exchange processes.

scholarly journals Synthesis, Characterization and Reactivity of Neutral Octahedral Alkyl-Cobalt(III) Complexes Bearing a Dianionic Pentadentate Ligand

2020 ◽  
Author(s):  
Lucie Nurdin ◽  
Warren Piers ◽  
Jian-Bin Lin ◽  
Benjamin S. Gelfand
Keyword(s):  
Strong Acid ◽  
Ambient Atmosphere ◽  
Pyridyl Nitrogen ◽  
Protonation Site ◽  
Methyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Radical Trap ◽  
Bond Homolysis ◽  
Pentadentate Ligand

<div>A variety of neutral alkyl-cobalt(III) complexes bearing a dianionic tetrapodal </div><div>pendadentate ligand B2Pz4Py are reported. Compounds 2-R (R = CH3, CH2SiMe3, </div><div>CH2SiMe2Ph, i Bu, CH2(c-C5H9) and (CH2)4CH=CH2) are synthesized in 58-90% yield. These </div><div>diamagnetic, octahedral complexes are thermally stable up to 110˚C and are also </div><div>remarkably stable to ambient atmosphere. They were fully characterized by spectroscopic </div><div>techniques, and in three cases, X-ray crystallography. Evidence for reversible homolytic </div><div>cleavage of the Co-C bonds was found in their reactions with the hydrogen atom donor 1,4-</div><div>cyclohexadiene and the radical trap TEMPO, as well as the observed cyclization of the 5-</div><div>hexenyl group to the methylcyclopentyl derivative over the course of several hours. </div><div>Despite these observations, it can be concluded that the diborate B2Pz4Py ligand provides a </div><div>very stable platform for these Co(III) alkyls. Reduction by one electron to a Co(II) alkyl can </div><div>accelerate bond homolysis, but in this instance, using cobaltocene as the reducing agent, </div><div>leads to ejection of an alkide anion through bond heterolysis, an unusual reaction for </div><div>Co(III) alkyls. Finally, protonation of compound 2-Me with the strong acid HNTf2 leads to </div><div>divergent reactivity in which the major protonation site is the pyridyl nitrogen of the ligand </div><div>as opposed to protonation of the methyl group. The produce of protonation at nitrogen is </div><div>the dimeric species 4 which was prepared via separate synthesis and characterized by Xray crystallography.</div>

scholarly journals Synthesis, Characterization and Reactivity of Neutral Octahedral Alkyl-Cobalt(III) Complexes Bearing a Dianionic Pentadentate Ligand

2020 ◽  
Author(s):  
Lucie Nurdin ◽  
Warren Piers ◽  
Jian-Bin Lin ◽  
Benjamin S. Gelfand
Keyword(s):  
Strong Acid ◽  
Ambient Atmosphere ◽  
Pyridyl Nitrogen ◽  
Protonation Site ◽  
Methyl Group ◽  
X Ray ◽  
X Ray Crystallography ◽  
Radical Trap ◽  
Bond Homolysis ◽  
Pentadentate Ligand

<div>A variety of neutral alkyl-cobalt(III) complexes bearing a dianionic tetrapodal </div><div>pendadentate ligand B2Pz4Py are reported. Compounds 2-R (R = CH3, CH2SiMe3, </div><div>CH2SiMe2Ph, i Bu, CH2(c-C5H9) and (CH2)4CH=CH2) are synthesized in 58-90% yield. These </div><div>diamagnetic, octahedral complexes are thermally stable up to 110˚C and are also </div><div>remarkably stable to ambient atmosphere. They were fully characterized by spectroscopic </div><div>techniques, and in three cases, X-ray crystallography. Evidence for reversible homolytic </div><div>cleavage of the Co-C bonds was found in their reactions with the hydrogen atom donor 1,4-</div><div>cyclohexadiene and the radical trap TEMPO, as well as the observed cyclization of the 5-</div><div>hexenyl group to the methylcyclopentyl derivative over the course of several hours. </div><div>Despite these observations, it can be concluded that the diborate B2Pz4Py ligand provides a </div><div>very stable platform for these Co(III) alkyls. Reduction by one electron to a Co(II) alkyl can </div><div>accelerate bond homolysis, but in this instance, using cobaltocene as the reducing agent, </div><div>leads to ejection of an alkide anion through bond heterolysis, an unusual reaction for </div><div>Co(III) alkyls. Finally, protonation of compound 2-Me with the strong acid HNTf2 leads to </div><div>divergent reactivity in which the major protonation site is the pyridyl nitrogen of the ligand </div><div>as opposed to protonation of the methyl group. The produce of protonation at nitrogen is </div><div>the dimeric species 4 which was prepared via separate synthesis and characterized by Xray crystallography.</div>

scholarly journals A Mixed-metal Mixed-halide Complex Prepared from Zerovalent Copper and Lead Salts: Solution and Solid-state Chemistry

1999 ◽  
Vol 23 (11) ◽  
pp. 670-671
Author(s):  
Larisa A. Kovbasyuk ◽  
Olga Yu. Vassilyeva ◽  
Vladimir N. Kokozay ◽  
Wolfgang Linert ◽  
Paul R. Raithby
Keyword(s):  
Solid State ◽  
Direct Interaction ◽  
Solid State Chemistry ◽  
X Ray ◽  
Mixed Metal ◽  
X Ray Crystallography ◽  
Halide Complex ◽  
Layer Arrangement ◽  
Lead Salts

The mixed-metal mixed-halide complex [CuPbBrlL2]2 has been prepared by the direct interaction of zerovalent copper with lead halides and 2-dimethylaminoethanol (HL) in dmso and has been characterized by X-ray crystallography; the structure shows a layer arrangement of the tetranuclear metal units through the μ3-halogen bridging.

Bis(1-phenyl-1-propyne) complexes of tungsten(II): crystal structures of [WI2(CO)(NCR)(η2-MeC2Ph)2] (R = Me, Et, or Ph)

2001 ◽  
Vol 79 (3) ◽  
pp. 263-271
Author(s):  
Paul K Baker ◽  
Michael GB Drew ◽  
Deborah S Evans
Keyword(s):  
Carbon Monoxide ◽  
Solid State ◽  
Crystal Structures ◽  
Octahedral Geometry ◽  
X Ray ◽  
X Ray Crystallography ◽  
Alkyne Complexes ◽  
First Time

Reaction of [WI2(CO)3(NCMe)2] with two equivalents of 1-phenyl-1-propyne (MeC2Ph) in CH2Cl2, and in the absence of light, gave the bis(1-phenyl-1-propyne) complex [WI2(CO)(NCMe)(η2-MeC2Ph)2] (1) in 77% yield. Treatment of equimolar quantities of 1 and NCR (R = Et, i-Pr, t-Bu, Ph) in CH2Cl2 afforded the nitrile-exchanged products, [WI2(CO)(NCR)(η2-MeC2Ph)2] (2-5) (R = Et (2), i-Pr (3), t-Bu (4), Ph (5)). Complexes 1, 2, and 5 were structurally characterized by X-ray crystallography. All three structures have the same pseudo-octahedral geometry, with the equatorial sites being occupied by cis and parallel alkyne groups, which are trans to the cis-iodo groups. The trans carbon monoxide and acetonitrile ligands occupy the axial sites. In structures 1 and 2, the methyl and phenyl substituents of the 1-phenyl-1-propyne ligands are cis to each other, whereas for the bulkier NCPh complex (5), the methyl and phenyl groups are trans to one another. This is the first time that this arrangement has been observed in the solid state in bis(alkyne) complexes of this type.Key words: bis(1-phenyl-1-propyne), carbonyl, nitrile, diiodo, tungsten(II), crystal structures.

Preparation and structural analysis of (±)-threo-ritalinic acid

2013 ◽  
Vol 69 (11) ◽  
pp. 1225-1228 ◽  
Author(s):  
Sara Wyss ◽  
Irmgard A. Werner ◽  
W. Bernd Schweizer ◽  
Simon M. Ametamey ◽  
Selena Milicevic Sephton
Keyword(s):  
Methyl Ester ◽  
Free Acid ◽  
Nmr Analysis ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
X Ray Crystallography ◽  
Ph Values ◽  
Ritalinic Acid ◽  
Methyl Phenidate ◽  
Hydrolysis Of

Hydrolysis of the methyl ester (±)-threo-methyl phenidate afforded the free acid in 40% yield,viz.(±)-threo-ritalinic acid, C13H17NO2. Hydrolysis and subsequent crystallization were accomplished at pH values between 5 and 7 to yield colourless prisms which were analysed by X-ray crystallography. Crystals of (±)-threo-ritalinic acid belong to theP21/nspace group and form intermolecular hydrogen bonds. An antiperiplanar disposition of the H atoms of the (HOOC—)CH—CHpygroup (py is pyridine) was found in both the solid (diffraction analysis) and solution state (NMR analysis). It was also determined that (±)-threo-ritalinic acid conforms to the minimization of negativegauche+–gauche−interactions.

Synthesis and structural characterization of a magnesium phthalocyanine(3–) anion

2012 ◽  
Vol 16 (01) ◽  
pp. 154-162 ◽  
Author(s):  
Edwin W.Y. Wong ◽  
Daniel B. Leznoff
Keyword(s):  
Absorption Spectrum ◽  
Solid State ◽  
Single Crystal ◽  
Structural Characterization ◽  
Heterometallic Complex ◽  
State Structure ◽  
Solid State Structure ◽  
X Ray ◽  
X Ray Crystallography

The reduction of magnesium phthalocyanine (MgPc) with 2.2 equivalents of potassium graphite in 1,2-dimethoxyethane (DME) gives [K2(DME)4]PcMg(OH)(1) in 67% yield. Compound 1 was structurally characterized using single crystal X-ray crystallography and was found to be a monomeric, heterometallic complex consisting of a μ3-OH ligand that bridges a [MgIIPc3-]- anion to two potassium cations solvated by four DME molecules. An absorption spectrum of 1 confirms the Pc ligand is singly reduced and has a 3–charge. The solid-state structure of 1 does not indicate breaking of the aromaticity of the Pc ligand. Compound 1 is only the second Pc3- complex and the first reduced MgPc to be isolated and structurally characterized.

47,49Ti NMR in Metals, Inorganics, and Gels

2000 ◽  
Vol 55 (1-2) ◽  
pp. 291-297 ◽  
Author(s):  
T. J. Bastow
Keyword(s):  
Solid State ◽  
Titanium Oxide ◽  
Recent Progress ◽  
Titanium Isopropoxide ◽  
Metallic State ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrolysis Of ◽  
C Nmr

Some recent progress in solid state 47,49Ti NMR is described and reviewed. The metallic-state work described covers metals such as hep titanium, TiB2 , a number of intermetallics such as TiAl2 and TiAl3· The inorganic work covers the various titanium oxide based materials including the TiO2 polymorphs, anatase, rutile and brookite. The gel work covers the evolution of crystalline titania from gels formed by hydrolysis of titanium isopropoxide. Some complementary data from 17O and 13C NMR and powder X-ray diffraction is also included.

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