Accurate molecular weight determination of small molecules via DOSY-NMR by using external calibration curves with normalized diffusion coefficients

Neufeld, Roman; Stalke, Dietmar

doi:10.1039/c5sc00670h

Cited by 211 publications

(214 citation statements)

References 72 publications

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“…1 HNMR spectroscopy (Figure S5) revealed ac omplex spectrum with multiple signals in the aromatic, aliphatic, and NH regions. By using the externalc alibration curve (ECC) for dissipated spheres and ellipsoids as elaborated by Stalke'sg roup, [24] the molecular weighto fc ompound 5 in solution was estimated to be 1183 gmol À1 .T his result deviates by only 5% when compared to the dimerics tructure observed for 5 in the solid state. [23] Further confirmation of the retention of the dimeric arrangement of 5 in C 6 D 6 was gained by using 1 HDOSY NMR spectroscopy (see the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Structural and Mechanistic Insights into s‐Block Bimetallic Catalysis: Sodium Magnesiate‐Catalyzed Guanylation of Amines

Tullio

Hernán‐Gómez

Livingstone

et al. 2016

Chemistry A European J

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To advance the catalytic applications of s-block mixed-metal complexes, sodium magnesiate [NaMg(CH SiMe ) ] (1) is reported as an efficient precatalyst for the guanylation of a variety of anilines and secondary amines with carbodiimides. First examples of hydrophosphination of carbodiimides by using a Mg catalyst are also described. The catalytic ability of the mixed-metal system is much greater than that of its homometallic components [NaCH SiMe ] and [Mg(CH SiMe ) ]. Stoichiometric studies suggest that magnesiate amido and guanidinate complexes are intermediates in these catalytic routes. Reactivity and kinetic studies imply that these guanylation reactions occur via (tris)amide intermediates that react with carbodiiimides in insertion steps. The rate law for the guanylation of N,N'-diisopropylcarbodiimide with 4-tert-butylaniline catalyzed by 1 is first order with respect to [amine], [carbodiimide], and [catalyst], and the reaction shows a large kinetic isotopic effect, which is consistent with an amine-assisted rate-determining carbodiimide insertion transition state. Studies to assess the effect of sodium in these transformations denote a secondary role with little involvement in the catalytic cycle.

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Section: Resultsmentioning

confidence: 99%

Structural and Mechanistic Insights into s‐Block Bimetallic Catalysis: Sodium Magnesiate‐Catalyzed Guanylation of Amines

Tullio

Hernán‐Gómez

Livingstone

et al. 2016

Chemistry A European J

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“…The nature of second species (monomeric and dimeric) is still in question. In order to clarify the structure we carried out DOSY NMR experiment [42][43][44] for 3a to determine the molecular mass of 3а in DMSO-d6 solution. Two species were detected in this spectrum (see Supplementary materials), too.…”

Section: Methylmentioning

confidence: 99%

Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP

et al. 2015

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A series of substituted pyridine dialcohols (2,6-bis(hydroxyalkyl)pyridines), 1-4, was used for the synthesis of various types of aluminum complexes. Aluminum methyl derivatives, 2-4a, were obtained by the reaction of AlMe3 with the corresponding ligand or transmetallation reactions of germylenes. Aluminum chloride complexes, 3-4b, were obtained by substitution of the Me group under the action of chlorinating agents. Methoxy-, 2-4c, or benzyloxy-, 2d, aluminum complexes were synthesized in transalkoxylation reaction of Me2Al(OX) (X = Me, Bn) by the corresponding ligand. All complexes obtained were thoroughly investigated by multinuclear NMR and X-ray analysis. It has been established that the structure of the ligand (number of carbon atoms) determines the nature of the complexes formed. Compounds were used as initiators of ring-opening polymerization of l-lactide and ε-caprolactone and showed moderate activity with controlled or immortal character.

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“…Die Anwesenheit zweier Maxima in der Elektronendichteverteilung entlang des N Ligand ···O Wasser -Vektors zeigt dabei das Vorliegen einer Wasserstoffbrücke mit Doppelpotential an. [41][42][43] Vorangegangene Studien zeigten, dass bei Verwendung der DSE-Kalibrierungskurve ("dissipated spheres and ellipsoids") die zuverlässigsten Ergebnisse füre ine akkurate Gewichtsabschätzung der meisten organometallischen s-Block-Verbindungen erhalten werden. [36] In diesem Zusammenhang wurde bemerkenswerterweise auch über ein vermeintlich hydrolyseempfindliches Phenylen-1,4bis(trifluoroborat)-Kalium-Doppelsalz berichtet, in dem ein ebenfalls cokristallisiertes Wassermoleküld urch K···O-und OH···p-Wechselwirkungen entscheidend zur Fähigkeit der Selbstorganisation des Moleküls im Festkçrper beiträgt.…”

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Eine wasserhaltige Organokaliumverbindung basierend auf Bis(4,6‐tert‐Butylbenzoxazol‐2‐yl)methanid und ihre unerwartete Hydrolysebeständigkeit

2017

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AufG rundlage des sterischa nspruchsvollen Ligandensystems Bis(4,6-tBu-benzoxazol-2-yl)methan konnte mit der wasserhaltigen Organokaliumverbindung [(18-Krone-6)K{(4,6-tBu-OCNC 6 H 2 ) 2 CH}·H 2 O] (2)e in einzigartiges Beispiel einer reaktiven, wasserbeständigen Organokaliumverbindung synthetisiert werden. Darüber hinaus ist 2 ein seltener Vertreter eines Metallkomplexes,i nd em ein Bis(benzoxazol-2-yl)methanid eine ausschließlicheO -Koordination zu einem Metallion zeigt. Verbindung 2 wurde vollständig anhand ihrer Festkçrperstruktur charakterisiert. Zusätzlichwurde sein Verhalten in Lçsung durchD OSY-NMR-und durch NMR-Titrationsexperimente beschrieben. Letztere zeigten eine vollständige Protonierung des Komplexes erst nachd er Zugabe von 114 ¾quivalenten Wasser und einer Reaktionszeit von sieben Tagen.

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Accurate molecular weight determination of small molecules via DOSY-NMR by using external calibration curves with normalized diffusion coefficients

Abstract: We describe a novel development of MW-determination by using an external calibration curve approach with normalized diffusion coefficients.

Cited by 211 publications

References 72 publications

Structural and Mechanistic Insights into s‐Block Bimetallic Catalysis: Sodium Magnesiate‐Catalyzed Guanylation of Amines

Structural and Mechanistic Insights into s‐Block Bimetallic Catalysis: Sodium Magnesiate‐Catalyzed Guanylation of Amines

Aluminum complexes based on pyridine substituted alcohols: synthesis, structure, and catalytic application in ROP

Eine wasserhaltige Organokaliumverbindung basierend auf Bis(4,6‐tert‐Butylbenzoxazol‐2‐yl)methanid und ihre unerwartete Hydrolysebeständigkeit

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