Stereochemistry of addition of carbanion reagents to `diacetone fructose aldehyde'. Configurational assignment of a 1-deoxyheptulose derivative by X-ray crystallography and NMR studies directed to the assignment of isomeric adducts

The complex salts CdL4(O3SCF3)2 (L = 2(1H)-pyridinethione (Py2SH), 4(1H)-pyridinethione (Py4SH), or 2(1H)-quinolinethione (Q2SH)) have been synthesized by the stoichiometric reaction of Cd(O3SCF3)2 and the appropriate thione. Both ambient-temperature 13C and reduced-temperature 111Cd NMR of CdL4(O3SCF3)2 in solution are consistent with L being bound through sulfur. Reduced-temperature NMR (31P, 77Se, 111Cd, as appropriate) of mixtures of CdL4(O3SCF3)2 and Cd(EPCy3)4(O3SCF3)2 (E = Se, Cy = c-C6H11) and of Cd(EPCy3)4(O3SCF3)2 (E = S, Se) and L in solution provides evidence for various [CdLn(EPCy3)4-n]2+. Similarly, reduced-temperature metal NMR of [CdL4]2+ and [CdL'4]2+ (L, L' = Py2SH, Py4SH, Q2SH; L not equal L') in solution shows the formation of [CdLnL'4-n]2+. Thus it has been demonstrated that at reduced temperature [CdL4]2+ is intact in solution and exchange of L is slow on the timescale of the metal chemical shift differences. From the NMR studies of Cd(EPCy3)4(O3SCF3)2 (E = S, Se):L mixtures, the binding preferences are found to be L > EPCy3 in solution. Similarly, from the reduced temperature metal NMR spectra of mixtures where L and L' compete for Cd(II) in solution, the binding preferences are Py4SH > Py2SH > Q2SH. The structure of Cd(Py2SH)4(NO3)2 (4) has been determined by single crystal X-ray analysis. Colorless crystals of 4 are tetragonal, I4(1)/acd with 8 molecules per unit cell of dimensions a = 18.660(3), c = 15.215(3) Å. The structure is comprised of recognizable NO3- anions and [Cd(Py2SH)4]2+ cations. In the cations, which have S4 symmetry, the ligands are S-bound. A network of NH···O hydrogen bonds links the cations and anions.Key words: aromatic heterocyclic thiones, cadmium complexes, phosphine chalcogenides, 111Cd, 31P, 77Se NMR, X-ray crystallography.

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Silylated gallium and indium chalcogenide ring systems as potential precursors to ME (E=O, S) materials

Open Chemistry ◽

10.2478/s11532-013-0255-y ◽

2013 ◽

Vol 11 (7) ◽

pp. 1225-1238

Author(s):

Iliana Medina-Ramírez ◽

Cynthia Floyd ◽

Joel Mague ◽

Mark Fink

Keyword(s):

Thermal Decomposition ◽

Room Temperature ◽

Membered Ring ◽

Molecular Structures ◽

Nmr Studies ◽

X Ray ◽

X Ray Crystallography ◽

High Yields ◽

Vt Nmr ◽

State 1

AbstractThe reaction of R3M (M=Ga, In) with HESiR′3 (E=O, S; R′3=Ph3, iPr3, Et3, tBuMe2) leads to the formation of (Me2GaOSiPh3)2(1); (Me2GaOSitBuMe2)2(2); (Me2GaOSiEt3)2(3); (Me2InOSiPh3)2(4); (Me2InOSitBuMe2)2(5); (Me2InOSiEt3)2(6); (Me2GaSSiPh3)2(7); (Et2GaSSiPh3)2(8); (Me2GaSSiiPr3)2(9); (Et2GaSSiiPr3)2(10); (Me2InSSiPh3)3(11); (Me2InSSiiPr3)n(12), in high yields at room temperature. The compounds have been characterized by multinuclear NMR and in most cases by X-ray crystallography. The molecular structures of (1), (4), (7) and (8) have been determined. Compounds (3), (6) and (10) are liquids at room temperature. In the solid state, (1), (4), (7) and (9) are dimers with central core of the dimer being composed of a M2E2 four-membered ring. VT-NMR studies of (7) show facile redistribution between four- and six-membered rings in solution. The thermal decomposition of (1)–(12) was examined by TGA and range from 200 to 350°C. Bulk pyrolysis of (1) and (2) led to the formation of Ga2O3; (4) and (5) In metal; (7)–(10) GaS and (11)–(12) InS powders, respectively.

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Supersize Cp! Tetrabenzo[a,c,g,i]fluorenyl complexes of yttrium

Canadian Journal of Chemistry ◽

10.1139/cjc-2016-0485 ◽

2017 ◽

Vol 95 (4) ◽

pp. 363-370 ◽

Cited By ~ 2

Author(s):

Jianlong Sun ◽

David J. Berg ◽

Brendan Twamley

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Ethylene Polymerization ◽

Nmr Studies ◽

X Ray ◽

X Ray Crystallography ◽

Trinuclear Cluster ◽

Polymerization Catalyst ◽

Dynamic Nuclear Magnetic Resonance ◽

Trimethylsilyl Isocyanate

The synthesis of tetrabenzo[a,c,g,i]fluorenyl (Tbf) yttrium dialkyl complexes, (Tbf)Y(CH2SiMe3)2(L) (L = tetrahydrofuran (THF), 1; L = bipy, 2), by direct protonolysis of the tris(alkyl) complex, Y(CH2SiMe3)3(THF)2, are reported. The X-ray crystal structures of 1 and 2 display the helical twisting typically observed for the Tbf ligand. Dynamic nuclear magnetic resonance (NMR) studies on 1 show a barrier to Tbf helical inversion (epimerization or “wagging”) of 38.1 ± 0.5 kJ mol−1. The reaction of 1 with acidic hydrocarbons such as 1,3-bis(trimethylsilyl)cyclopentadiene or trimethylsilylacetylene results in protonolysis to form the mixed Cp derivative [(Tbf){C5H3(SiMe3)2}Y(CH2SiMe3)(THF)] (3) or [(Tbf)Y(CCSiMe3)2(THF)]n (4), respectively. In the case of 4, a small amount of the trinuclear cluster (Tbf)Y3(μ3-CCSiMe3)2(μ2-CCSiMe3)3(CCSiMe3)3(THF)2 (5) was isolated and characterized by X-ray crystallography. Dialkyl 1 undergoes smooth insertion of trimethylsilyl isocyanate to afford [(Tbf)Y{κ2-(N,O)-Me3SiN(Me3SiCH2)CO}2(THF)] (6) but it does not react with alkenes. Treating 1 with [Ph3C]+[B(C6F5)4]− in bromobenzene generates a moderately active ethylene polymerization catalyst (36 kg mol−1 h−1 bar−1).

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Synthesis and coordination studies of new aminoalcohol functionalized tertiary phosphines

Canadian Journal of Chemistry ◽

10.1139/v01-037 ◽

2001 ◽

Vol 79 (5-6) ◽

pp. 780-791 ◽

Cited By ~ 13

Author(s):

Sean E Durran ◽

Martin B Smith ◽

Alexandra MZ Slawin ◽

Thomas Gelbrich ◽

Michael B Hursthouse ◽

...

Keyword(s):

Precious Metals ◽

Nmr Studies ◽

X Ray ◽

X Ray Crystallography ◽

Tertiary Phosphines ◽

Linear Chains ◽

Metal Precursors ◽

I 11 ◽

Late Transition ◽

Hybrid Ligands

The synthesis of two new aminoalcohol functionalized tertiary phosphines o-Ph2PCH2N(H)C6H4(OH) (I) and o-Ph2PCH2N(H)C6H4(CH2OH) (II) are reported. Oxidation with aqueous H2O2 gave the corresponding phosphine oxides o-Ph2P(O)CH2N(H)C6H4(OH) (III) and o-Ph2P(O)CH2N(H)C6H4(CH2OH) (IV) (31P NMR evidence only). The ligating ability of I, II and, in several cases, the known ligand 2,3-Ph2PCH2N(H)C5H3N(OH) (V), was investigated with a range of late transition-metal precursors. Accordingly, reaction of 2 equiv of I (or II) with [MCl2(cod)] (M = Pd or Pt, cod = cycloocta-1,5-diene) gave the corresponding dichloro metal(II) complexes [MCl2(I)2] (M = Pd 1; M = Pt 2) and [MCl2(II)2] (M = Pd 3; M = Pt 4) in which I (and II) P-coordinate. Solution NMR studies reveal that 2 and 4 are exclusively cis whereas 1 and 3 are present as a mixture of cis and (or) trans isomers [4.7:1 (for 1); 2.2:1 (for 3)]. Reaction of 2 equiv of II with [Pt(CH3)2(cod)] gave the neutral complex [Pt(CH3)2(II)2] (5) whose X-ray structure confirmed a cis disposition of "hybrid" ligands. In contrast, reaction of I with [Pt(CH3)2(cod)] gave initially [Pt(CH3)2(I)2] (6) which, upon standing, afforded several products possibly reflecting an increased acidity of the phenolic groups of ligated I. Chloro bridge cleavage reactions of [{Ru(µ-Cl)Cl(p-cymene)}2] or [{Rh(µ-Cl)Cl{C5(CH3)5}}2] with I (or II) proceeds smoothly and gave the mononuclear complexes [RuCl2(p-cymene)I] (7), [RuCl2(p-cymene)II] (8), [RhCl2{C5(CH3)5}I] (9), and [RhCl2{C5(CH3)5}II] (10) in good yield. X-ray crystallography confirms both ruthenium complexes bear P-coordinated I (or II) ligands. Molecules of 7 are linked into linear chains via O-H···Clcoord intermolecular hydrogen bonding, a feature absent in the closely related compound 8. Reaction of [AuCl(tht)] (tht = tetrahydrothiophene) with 1 equiv of I (or II) gave the corresponding gold(I) complexes [AuCl(I)] (11) and [AuCl(II)] (12). Bridge cleavage of the cyclometallated palladium(II) dimers [{Pd(µ-Cl)(C~N)}2] [C~N = C,N-C6H4CH2N(CH3)2, C,N-C10H6N(CH3)2, C,N-C6H4N=NC6H5] with V (or I) gave the neutral complexes [PdCl(C~N)V] (13-15) (or [PdCl(C9H12N)I] (16)), respectively. Chloride abstraction from 13 (or 15) with Ag[BF4] gave the cationic complexes [Pd(C~N)V][BF4] (17) (or 18) in which V P,N pyridyl-chelates to the palladium(II) metal centre. The X-ray structures of 13 and 18 have been determined and confirm the expected coordination environments. An array of intra- and intermolecular H-bonding contacts are also observed. All compounds have been characterized by a combination of spectroscopic and analytical studies.Key words: phosphines, crystal structures, alcohols, precious metals.

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Meta-metallation of N,N-dimethylaniline: Contrasting direct sodium-mediated zincation with indirect sodiation-dialkylzinc co-complexation

Beilstein Journal of Organic Chemistry ◽

10.3762/bjoc.7.144 ◽

2011 ◽

Vol 7 ◽

pp. 1234-1248 ◽

Cited By ~ 15

Author(s):

David R Armstrong ◽

Liam Balloch ◽

Eva Hevia ◽

Alan R Kennedy ◽

Robert E Mulvey ◽

...

Keyword(s):

Theoretical Calculations ◽

Major Product ◽

Basis Set ◽

Nmr Studies ◽

Additional Species ◽

X Ray ◽

X Ray Crystallography ◽

Bimetallic Systems ◽

Reaction Solution ◽

B3lyp Method

Previously we reported that direct zincation of N,N-dimethylaniline by the mixed-metal zincate reagent 1 ((TMEDA)Na(TMP)(t-Bu)Zn(t-Bu)) surprisingly led to meta-metallation (zincation) of the aniline, as manifested in the crystalline complex 2 ((TMEDA)Na(TMP)(m-C6H4-NMe2)Zn(t-Bu)), and that iodination of these isolated crystals produced the meta-isomer N,N-dimethyl-3-iodoaniline quantitatively. Completing the study here we find that treating the reaction solution with iodine produces a 72% conversion and results in a mixture of regioisomers of N,N-dimethyliodoaniline, with the meta-isomer still the major product (ortho:meta:para ratio, 6:73:21), as determined by NMR. In contrast to this bimetallic method, sodiation of N,N-dimethylaniline with n-BuNa produced the dimeric, ortho-sodiated complex 3 (((TMEDA)Na(o-C6H4-NMe2))2), as characterised by X-ray crystallography and NMR. No regioisomers were observed in the reaction solution. Introducing t-Bu2Zn to this reaction solution afforded a cocrystalline product in the solid-state, composed of the bis-anilide 4 ((TMEDA)Na(o-C6H4-NMe2)2Zn(t-Bu)) and the Me2N–C cleavage product 5 ({(TMEDA)2Na}+{(t-Bu2Zn)2(µ-NMe2)}−), which was characterised by X-ray crystallography. NMR studies of the reaction mixture that produces 4 and 5 revealed one additional species, but the mixture as a whole contained only ortho-species and a trace amount of para-species as established by iodine quenching. In an indirect variation of the bimetallic reaction, TMP(H) was added at room temperature to the reaction mixture that afforded 4 and 5. This gave the crystalline product 6 ((TMEDA)Na(TMP)(o-C6H4-NMe2)Zn(t-Bu)), the ortho-isomer of the meta-complex 2, as determined from X-ray crystallographic and NMR data. Monitoring the regioselectivity of the reaction by iodination revealed a 16.6:1.6:1.0 ortho:meta:para ratio. Interestingly, when the TMP(H) containing solution was heated under reflux for 18 hours more meta-isomer was produced (corresponding ratio 3.7:4.2:1.0). It is likely that this change has its origin in a retro reaction that produces the original base 1 as an intermediate. Theoretical calculations at the DFT level using the B3LYP method and the 6-311G** basis set were used to probe the energetics of both monometallic and bimetallic systems. In accord with the experimental results, it was found that ortho-metallation was favoured by sodiation; whereas meta- (closely followed by para-) metallation was favoured by direct sodium-mediated zincation.

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Short-Chained Anthracene Strapped Porphyrins and Their Endoperoxides

10.26434/chemrxiv.11927283.v1 ◽

2020 ◽

Author(s):

Susan Callaghan ◽

Keith Flanagan ◽

John E. O'Brien ◽

Mathias Senge

Keyword(s):

Singlet Oxygen ◽

1H Nmr ◽

Absorption Spectroscopy ◽

Cycloaddition Reactions ◽

Nmr Studies ◽

X Ray ◽

X Ray Crystallography ◽

Polychromatic Light

The synthesis of short-chained anthracene-strapped porphyrins and their Zn(II)complexes are reported. The key synthetic step employed was a [2+2] condensation between a dipyrromethane and 2,2'-((anthracene-9,10-diylbis(methylene))bis(oxy))dibenzaldehyde. Following exposure to polychromatic light, self-sensitized singlet oxygen and the anthracene moieties underwent [4+2] cycloaddition reactions to yield the corresponding endoperoxides. 1H NMR studies demonstrate that the endoperoxide readily formed in chloroform-d and decayed at 85 Â°C. X-ray crystallography and absorption spectroscopy were used to confirm macrocyclic distortion in the parent strapped porphyrins and endoperoxides. Additionally, X-ray crystallography indicated that endoperoxide formation occurred exclusively on the outside face of the anthracene moiety.

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Uncovering Redox Non-Innocent H-Bonding in Cu(I)-Diazene Complexes

10.26434/chemrxiv.14604483.v1 ◽

2021 ◽

Author(s):

Evan Gardner ◽

Sean C. Marguet ◽

Caitlyn Cobb ◽

Dominic Pham ◽

Jeffery A. Bertke ◽

...

Keyword(s):

Electronic Structure ◽

Dynamic Equilibrium ◽

Cation Radical ◽

High Energy ◽

Dft Studies ◽

Nmr Studies ◽

X Ray ◽

X Ray Crystallography ◽

H Nmr ◽

Potential Strategy

<div>The life-sustaining reduction of N2 to NH3 is thermoneutral yet kinetically challenged by high energy intermediates such as N2H2. Exploring intramolecular H-bonding as a potential strategy to stabilize diazene intermediates, we employ a series of [xHetTpCu]2(𝜇-N2H2) complexes that exhibit H-bonding between pendant aromatic N-heterocycles (XHet) such as pyridine and a bridging trans-N2H2 ligand at copper(I) centers. X-ray crystallography and IR spectroscopy clearly reveal H-bonding in [pyMeTpCu]2(𝜇-N2H2) while low temperature 1H NMR studies coupled with DFT analysis reveals a dynamic equilibrium between two closely related, symmetric H-bonded structural motifs. Importantly, the xHet pendant negligibly influences the electronic structure of xHetTpCuI centers in xHetTpCu(CNAr2,6-Me2) complexes that lack H-bonding as judged by nearly indistinguishable n(CN) frequencies (2113 - 2117 cm-1). Nonetheless, H-bonding in the corresponding [xHetTpCu]2(𝜇-N2H2) complexes results in marked changes in n(NN) (1398 - 1419 cm-1) revealed through rRaman studies. Due to the closely matched N-H BDE’s of N2H2 and the neutral pyH0 cation radical, the aromatic N-heterocylic pendants may encourage partial H-atom transfer (HAT) from N2H2 to xHet through redox non-innocent H-bonding in [xHetTpCu]2(𝜇-N2H2). DFT studies reveal modest thermodynamic barriers for concerted transfer of both H-atoms of coordinated N2H2 to the xHet pendants to generate tautomeric [xHetHTpCu]2(𝜇-N2) complexes, identifying concerted dual HAT as a thermodynamically favorable pathway for N2 / N2H2 interconversion.</div>

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NMR studies and X-ray crystallography of galdosol 5-methyl ether from Salvia officinalis L.

Journal of Crystallographic and Spectroscopic Research ◽

10.1007/bf01161344 ◽

1992 ◽

Vol 22 (5) ◽

pp. 585-590 ◽

Cited By ~ 1

Author(s):

Z. Djarmati ◽

R. M. Jankov ◽

J. Csanadi ◽

A. Djordjević ◽

B. Ribar ◽

...

Keyword(s):

Methyl Ether ◽

Salvia Officinalis ◽

Nmr Studies ◽

X Ray ◽

X Ray Crystallography ◽

Salvia Officinalis L

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Tautomerism of 1-(2′,4′-dinitrophenyl)-3-methyl-2-pyrazolin-5-one: theoretical calculations, solid and solution NMR studies and X-ray crystallography

New Journal of Chemistry ◽

10.1039/a805415k ◽

1998 ◽

Vol 22 (12) ◽

pp. 1421-1430 ◽

Cited By ~ 20

Author(s):

Christophe Dardonville ◽

Jose´ Elguero ◽

Isabel Rozas ◽

Cristina Fernández-Castaño ◽

Concepción Foces-Foces ◽

...

Keyword(s):

Theoretical Calculations ◽

Solution Nmr ◽

Nmr Studies ◽

X Ray ◽

X Ray Crystallography

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New perceptions of transcription factor properties from NMR

Biochemistry and Cell Biology ◽

10.1139/o98-064 ◽

1998 ◽

Vol 76 (2-3) ◽

pp. 368-378 ◽

Cited By ~ 4

Author(s):

Stefan Bagby ◽

Cheryl H Arrowsmith ◽

Mitsuhiko Ikura

Keyword(s):

Transcription Factor ◽

Protein Interactions ◽

Dna Interaction ◽

Protein Protein Interactions ◽

Nmr Studies ◽

X Ray ◽

X Ray Crystallography ◽

Protein Protein Interaction ◽

Structural Problems ◽

Induced Folding

The complementarity of NMR and X-ray crystallography for biomacromolecular studies has been particularly evident in analysis of transcription factor structures and interactions. While X-ray crystallography can be used to tackle relatively complicated structural problems including multicomponent (three and higher) complexes, NMR studies have provided new insights into the nature of protein-DNA and protein-protein interactions that would be difficult to obtain by other biophysical methods. We describe herein some of the novel and important information recently derived from NMR studies of transcription factors.Key words: protein-DNA interaction, protein-protein interaction, induced folding, conformational fluctuations, transcriptional regulation.

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