Determination of Coupling Signs 1J(119Sn, 15N ) and 2J(119Sn, 117Sn) in Trimethylstannylamines

1998 ◽  
Vol 53 (12) ◽  
pp. 1494-1500 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Jürgen Weidinger ◽  
Heinrich Nöth ◽  
Wolfgang Storch ◽  
Thomas Seifert ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Lone Pair ◽  
Coupling Constants ◽  
Positive Sign ◽  
Two Dimensional ◽  
Ultrahigh Resolution ◽  
Sign Inversion ◽  
First Time ◽  
Influence Of Substituents

The l5N-labelled trimethylstannylamines 1 - 3 [(Me3Sn)3N, (Me3Sn)2NPh, (Me3Sn)2NBCgHi4 (BCgHi4 = 9-borabicyclo[3.3.0]nonyn and the non-labelled 4, Me3Sn-N(BC8Hi4)2 , were prepared and studied by 1H, 1C, 15N and 119Sn NMR. The 15N ultrahigh resolution NMR spectra of 1 revealed otherwise unobserved parameters such as 2J(15N ,Sn ,13C ) and the isotope induced chemical shift 2Δ12/13C(15N). 119Sn NMR spectra of 1, recorded under similar conditions, also show new parameters such as 3J(119Sn,N,Sn,13C) which are not resolved in the non-labelled derivative. By using various types o f two-dimensional heteronuclear shift correlations, absolute coupling signs of 1J(119Sn,15N) (all < 0) in 1 - 3 were determined. By the same techniques it proved possible to confirm the negative sign o f :7(Sn,Sn) (-195.4 Hz) in 1. In contrast, the coupling constants 2J(Sn,Sn) for 2 (+71.7) and 3 (+62.0) possess a positive sign. This sign inversion, observed here for the first time for apparently similar compounds, demonstrates the enormous influence of substituents on the nature of the lone pair of electrons at the nitrogen atom. It also shows that these experiments for sign determinations of coupling constants are necessary in order to interpret these data correctly.

15N Nucelar Magnetic Resonance Study of Two-Coordinate Phosphorus Cations - Sign-Determination of Coupling Constants – Application of Two-Dimensional (2D) Heteronuclear Shift Correlations

1992 ◽  
Vol 47 (5) ◽  
pp. 662-667 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Jürgen Schiller
Keyword(s):  
Chemical Shifts ◽  
Double Resonance ◽  
Lone Pair ◽  
Coupling Constants ◽  
Phosphorus Compounds ◽  
Positive Sign ◽  
Nuclear Shielding ◽  
First Time ◽  
N Natural Abundance

Cyclic and non-cyclic bis(amino)phosphenium cations (1 to 4) together with their precursors (bis(amino)phosphorus chlorides 5 to 8) and some other bis(amino)phosphorus compounds (9 to 14) have been studied by 13C, 15N (natural abundance), 29Si and 31P NMR spectroscopy. 15N chemical shifts and coupling constants 1J(31P15N) of phosphenium cations have been determined for the first time. NMR data of 1 to 4 are compared with those of a bis(amino)carbene and various bis(amino)stannylenes. In the phosphenium cations 1 to 4 the 15N nuclear shielding is considerably reduced (ca. 70 to 100 ppm as compared with 5 to 14) and there is a crude linear relationship between δ15N and δ31P values. Changes in the δ15N values of 1 to 4 do not reflect P-N (pp)π interactions. A positive sign has been determined for the coupling constants 1J(31Ρ15Ν) [reduced coupling constants 1K(31P15N) < O] for the phosphenium cations and for all other P(III)-N compounds studied. This was achieved by applying various one- and twodimensional heteronuclear double resonance techniques. The experiments also gave signs of the coupling constants 2J(31PN13C), 2J(31PN29Si), 3J(31PNC13C), 3J(31PNSi13C), 4J(31PNCC1H) and 4J(31PNSiC1H). Negative contributions to 1K(31P15N), arising from the lone pair of electrons at phosphorus, are more noticeable in the case of the phosphenium cations.

Notizen: Geminal Coupling Constants 2.J(15N13C) in 2-Substituted Pyridines, Measured by Hahn-Echo Extended (HEED) Pulse Sequences

1993 ◽  
Vol 48 (10) ◽  
pp. 1433-1436
Author(s):  
Bernd Wrackmeyer ◽  
Gerald Kehr
Keyword(s):  
High Resolution ◽  
Nmr Spectra ◽  
Pulse Sequences ◽  
Coupling Constants ◽  
Positive Sign ◽  
Two Dimensional ◽  
H Nmr ◽  
Substituted Pyridines ◽  
Geminal Coupling

Coupling constants 2J(15N13CR) and nJ(15N1HR) in 2-substituted pyridines [R = Me (1), CH=CH2 (2), C≡CH (3), C(O)H (4), C(O)Me (5)] have been measured by using Hahn-echo extended (HEED) pulse sequences for one- (1 D) and two-dimensional (2D) 13C/1H NMR (HEED-INEPT, HEED-HETCOR). The magnitude of |2J(15N13CR)| is hardly affected by the hybridization of 13CR. 15N NMR spectra, measured under conditions of ultra high resolution (UHR) confirm the values 2J(15N13CR). 2D 13C/1H HEED-HETCOR experiments show that the sign of 3J(15Ν1HR) is negative in 1, whereas the coupling constants 3J(15N1HR) in 4 and 4J(15N1HR) in 3 have a positive sign

scholarly journals Sign-Determination of Spin-Spin Coupling Constants in tert-Butylphosphaalkyne

1992 ◽  
Vol 47 (3) ◽  
pp. 437-438
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Coupling Constants ◽  
Spin Coupling ◽  
Positive Sign ◽  
Two Dimensional ◽  
Tert Butyl ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Sign Determination

The signs o f the coupling constants 1J(31P≡13C) ( > O ) , J(31P13C) ( > O ) , 3J(31P13C) ( > O ) and 4J(31P1H) ( > O ) in tert-butyl-phosphaalkyne (1) were determined by selective 1H {31P} NMR experiments and two-dimensional (2 D ) 13C/1H heteronuclear shift correlations based on nJ(13C1H ) (n = 1,2,3), confirming the previously assumed positive sign of 1J( 31P≡13C) in phosphaalkynes.

Determination of Absolute Signs of 119Sn-117Sn Spin-Spin Coupling Constants

1994 ◽  
Vol 49 (10) ◽  
pp. 1407-1409 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Gerald Kehr
Keyword(s):  
Long Range ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Two Dimensional ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
First Time

AbstractIf for a given system two-dimensional (2D) 119Sn/1H heteronuclear shift correlations can be established for long range coupling constants nJ(119Sn,1H) (n = 4, 6), absolute signs of coupling constants J(Sn,Sn) are accessible by this technique for the first time. This has been demonstrated for tetrakis(trimethylstannyl)allene (1) with 2J(119Sn,117Sn) (>0) and 4J(Sn. 117Sn) (<0) and for tris(trimethylstannyl)phosphane (2) and bis(trimethvlstannyl)- sulfane (3) with 2J(119Sn,117Sn) (<0).

Structural studies of digitoxin and related cardenolides by two-dimensional NMR

1990 ◽  
Vol 68 (2) ◽  
pp. 272-277 ◽  
Author(s):  
Torbjörn Drakenberg ◽  
Peter Brodelius ◽  
Deane D. McIntyre ◽  
Hans J Vogel
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chair Conformation ◽  
Coupling Constants ◽  
Two Dimensional ◽  
Structural Studies ◽  
Solution Conformation ◽  
Phase Sensitive ◽  
Multiple Relay ◽  
C Nmr

The 1H and 13C NMR spectra of the cardenolides digitoxigenin, digoxigenin, digitoxin, and mono- and bis-digitoxigenin digitoxosides have been completely assigned by two-dimensional NMR spectroscopy. The techniques used include phase-sensitive COSY, multiple relay COSY, and carbon–proton correlation (HETCOR and HMQC) spectra. Various aspects of the solution conformation of the steroid moiety of digitoxin and digoxigenin could be determined from coupling constants and NOE difference experiments and they are indicative of an all-chair conformation. The carbohydrate rings in digitoxin and the mono- and bis-digitoxigenin digitoxosides are also in the chair conformation. Keywords: cardenolides, digitoxigenin, digitoxin, 2-dimensional NMR, conformational analysis.

scholarly journals Five sesquiterpenes from the root Aucklandia lappa Decne.

2019 ◽  
pp. 5-11
Author(s):  
Chjuo Fuguan ◽  
Seesregdorj S ◽  
Gerelt-Od Ya
Keyword(s):  
Phenolic Compounds ◽  
Nmr Spectra ◽  
Previous Literature ◽  
Two Dimensional ◽  
Nmr Data ◽  
Nmr Techniques ◽  
The One ◽  
Dehydrocostus Lactone ◽  
First Time

The four sesquiterpenes calameone (1), dehydrocostus lactone (2), aristolone (3), alantolactone (4) and one triterpenoid α-amyrine (5), simple phenolic compounds such as 4-hydroxybenzaldehyde, (6), piceol (7), apocynin (8), dihydroconiferyl (9) and coniferyl (10) have been identified by using the proton and carbon NMR spectra which were isolated from a dichloromethane extract of the roots of Aucklandia lappa Decne. Their structures were established by the one‐and two‐dimensional NMR techniques including DEPT, COSY and HMBC spectroscopy. This work examined proton and carbon NMR data of calameone (1) and aristolone (3) for the first time, which had not yet been fully studied in previous literature. Рүда ургамлын (Aucklandia lappa Decne.) терпент нэгдлийн судалгаа Хураангуй: Рүда ургамлын үндэсний дихлорметаны ханднаас хроматографийн аргуудаар эвдесман хэлбэрийн сесквитерпен каламеон (1), аристолон (3), алантолактон (4), гвяан хэлбэрийн сесквитерпен дегидрокостасын лактон (2), тритерпеноид α-амурин (5) болон энгийн фенолт нэгдэл 4-гидроксибензальдегид (6), пицелол (7), апоцинин (8), дегидрокониферол (9), кониферол (10) зэрэг бодисыг химийн цэвэр байдалтай ялгав. Эдгээр бодисын бүтэц байгуулалтыг нэг болон хоёр хэмжээст ЦСР-ын DEPT, COSY, HMBC спектроскопийн аргаар таньж тодорхойлов. Урьд өмнө каламеон (1), аристолон (3) бодисуудын устөрөгч ба нүүрстөрөгчийн атомуудын химийн шилжилтийн утгуудад оноолт бүрэн хийгдээгүй байсан ба энэ хоёр бодисын оноолтыг гүйцээж хийв. Түлхүүр үг: Терпеноид, сесквитерпент лактон, дегидрокостасын лактон, ЦСР.

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