Synthese und Multikern-NMR-Spektroskopie einiger vier-und fünfgliedriger Zinn—Stickstoff-Heterocyclen / Synthesis and Multinuclear NMR Spectroscopy of Some Four-and Five-Membered Tin —Nitrogen Heterocycles

1988 ◽  
Vol 43 (6) ◽  
pp. 707-714 ◽  
Author(s):  
Carin Stader ◽  
Bernd Wrackmeyer ◽  
Dieter Schlosser
Keyword(s):  
Nmr Spectroscopy ◽  
Lone Electron Pair ◽  
Electron Pair ◽  
Chemical Shifts ◽  
Nitrogen Heterocycles ◽  
Spiro Compounds ◽  
Coupling Constants ◽  
Ring Size ◽  
Multinuclear Nmr Spectroscopy ◽  
Cyclic Compounds

Tin-nitrogen heterocycles [1,3,2,4λ2-diazasila- (1), -λ4-stannetidines (2), spiro-compounds (3, 4), 1,3,2λ4,4λ4-diazadistannetidines (5), 1,3,4,5,2λ2-diazadisila- (6) and -λ4-stannolidines (7)] have been characterized by 13C, 15N, 29Si and 119Sn NMR spectroscopy [chemical shifts δX and coupling constants nJ(119Sn-X) (n = 1, 2, 3; X = 13C, 15N, 29Si, 119Sn]. The influence of the ring size becomes apparent in particular by comparison of the various coupling constants. In the compounds 1 and 6 the presence of a two-coordinate tin atom is reflected by the extremely low shielding of the 119Sn nuclei and also by the reduced shielding of the 29Si nucleus. The comparison with δ(29Si) data for corresponding non-cyclic compounds indicates that the latter effect may be traced to intra-annular interactions in 1 and 6 which involve the lone electron pair at the tin atom.

Zinn(IV)-Verbindungen mit Ferrocenylchalkogenat- und Ferrocenylendichalkogenat-Liganden. Synthese und Multikern-NMR-Spektroskopie / Tin(IV) Compounds Containing Ferrocenyl Chalcogenate and Ferrocenylene Dichalcogenate Ligands. Synthesis and Multinuclear NMR Spectroscopy

1993 ◽  
Vol 48 (7) ◽  
pp. 940-950 ◽  
Author(s):  
Max Herberhold ◽  
Michaela Hübner ◽  
Bernd Wrackmeyer
Keyword(s):  
Nmr Spectroscopy ◽  
Systematic Study ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Spiro Compounds ◽  
Coupling Constants ◽  
Solution Nmr ◽  
Multinuclear Nmr Spectroscopy ◽  
Cp Mas Nmr ◽  
Sulfur Containing

A series of tin(IV) compounds containing ferrocenyl chalcogenate (FcE) and ferrocenylene dichalcogenate (fcE2) ligands (E = S, Se, Te) has been synthesized for a systematic study of the NMR spectra with particular emphasis on 13C, 119Sn, 77Se and 125Te NMR. All compounds are formally derived from tetramethylstannane, SnMe4, by stepwise replacement of methyl by either FcE or fcE2 ligands. Starting from lithioferrocene the products are tetrasubstituted stannanes Me4-nSn(EFc)n (n = 1 and 2, E = S, Se, Te; n = 3 and 4, E = S, Se). Starting from 1,1′dilithioferrocene, the products are 1,1′-disubstituted ferrocenes such as fc(E-SnMe3)2 (E = S, Se, Te), although 1,3-dichalcogena[3]ferrocenophane rings are formed whenever possible to give [3]ferrocenophanes fcE2SnMe2 (E = S, Se, Te) and fc[E-Sn(Me)E2fc]2 (E = S, Se) or tin spiro compounds Sn(E2fc)2 (E = S, Se, Te). Whereas all (8) possible sulfur-containing and all (8) selenium-containing products were accessible, some of the tellurium-rich compounds could not be isolated due to preferred formation of either Fc2Te2 or fcTe3.All compounds were characterized on the basis of their 1H, 13C, 119Sn and, if possible, 77Se and 125Te solution NMR spectra. In many cases, coupling constants such as 2J(119Sn1H), nJ(119Sn13C) (n = 1,2,3), 1J(119Sn77Se) and 1J(125Τe119Sn), 1J(77Se13C) and 1J(125Te13C) could be determined. The δ119Sn chemical shifts of analogous phenyl and ferrocenyl compounds, Me4-nSn(EPh) and Me4-nSn(EFc)n (n = 0-4, E = S, Se, Te), are discussed, and for a microcrystalline sample of tetrakis(ferrocenylselenolato)stannane, Sn(SeFc)4, the 119Sn and 77Se CP/MAS NMR spectra are reported and compared with the solution spectra.

Eine 15N-NMR-untersuchung einiger trimethylstannylhydrazine / A15N-NMR study of some trimethylstannylhydrazines

1989 ◽  
Vol 44 (6) ◽  
pp. 653-658 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Theo Gasparis-Ebeling ◽  
Heinrich Nöth
Keyword(s):  
Nmr Spectroscopy ◽  
Lone Electron Pair ◽  
Electron Pair ◽  
Relative Magnitude ◽  
Coupling Constants ◽  
15N Nmr ◽  
Nmr Study ◽  
Geminal Coupling ◽  
In Cis ◽  
First Time

The trimethylstannylhydrazines (Me3Sn)2N-NMe2 (1), Me3Sn(Me)N-N(Me)SnMe3 (2), (Me3Sn)2N-N(Me)SnMe3 (3), and (M e3Sn)2N-N(Ph)SnMe3 (4) have been studied by δ15N NMR at natural abundance. A correlation between δ15N of hydrazines and δI5N of corresponding am ines (replacement of one N-atom by the CH-unit) is proposed in order to estimate δI5N values and to support the non-trivial assignment of 15N resonances of hydrazines. Geminal coupling constants 2J(119SnN 15N) have been observed for the first time. Their relative magnitude is related to the probability of the N-Sn bond being in cis-position with respect to the orientation of the lone electron pair at the 15N nucleus in the 119Sn-N-15N fragment. Treatment of 4 with phenylacetylene causes non-selective cleavage of the Sn-N bonds, leading to the trim ethylstannylhydrazines 5 and 6 which have been characterized by 119Sn and 15N NMR spectroscopy in solution

Hexaethyl-2,4-dicarba-nido-hexaborane(8), Deprotonation and Complexation Studied by NMR Spectroscopy and Density Functional Theory (DFT) Calculations

2004 ◽  
Vol 59 (6) ◽  
pp. 685-691 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Hans-Jörg Schanz
Keyword(s):  
Density Functional Theory ◽  
Nmr Spectroscopy ◽  
Density Functional ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Analogous Reaction ◽  
Sandwich Complex ◽  
Dft Methods ◽  
Functional Theory ◽  
Nmr Data

Deprotonation of hexaethyl-2,4-dicarba-nido-borane(8) 2 leads first to the hexaethyl-2,4-dicarbanido- borate(1−) 3, and further deprotonation, using BuLi/KOtBu, gives the hexaethyl-2,4-dicarbanido- hexaborate(2−) 4. The reaction of 3 with FeCl2 affords the commo-ferracarborane [Fe(Et6-2,4- C2B4H)2] 5, and the analogous reaction of 4 leads to the anionic sandwich complex [Fe(Et6-2,4- C2B4)2]2− 6 which can be protonated to give 5. The complex 5 contains two hydrido ligands, each bridging the iron and two boron atoms. Reactions were monitored and the products were characterised by 11B NMR spectroscopy in solution. The geometries of the carboranes, the borates (all unsubstituted and permethyl-substituted) and the iron complexes (all unsubstituted) were optimised by DFT methods [B3LYP/6-311+G(d,p) or B3LYP/6-31+G(d)], and the relevant NMR data [chemical shifts δ11B, δ13C, δ57Fe, and coupling constants 1J(13C,1H), 1J(11B,1H), 1J(57Fe,1H), 1J(57Fe,11B)] were calculated at the same level of theory.

A nuclear magnetic resonance investigation of the micellar properties of a series of sodium cyclohexylalkanoates

1999 ◽  
Vol 77 (11) ◽  
pp. 1994-2000 ◽  
Author(s):  
Judith A MacInnis ◽  
R Palepu ◽  
D Gerrard Marangoni
Keyword(s):  
Nmr Spectroscopy ◽  
Chemical Shift ◽  
Conformational Changes ◽  
Chemical Shifts ◽  
Micelle Formation ◽  
Counterion Binding ◽  
Micellar Properties ◽  
Aggregation Numbers ◽  
Multinuclear Nmr Spectroscopy ◽  
Magnetic Resonance Investigation

The micellar properties of a family of surfactants, the sodium cyclohexylalkanoates, have been investigated in aqueous solution using multinuclear NMR spectroscopy. C-13 chemical shift measurements have been used to determine both the cmc values and the micellar aggregation numbers (Ns values) of these surfactants. The cmc values and the degrees of counterion binding were estimated from 23Na chemical shift measurements. The critical micelle concentrations (cmc's) and the aggregation numbers determined from the NMR experiments indicate that these amphiphiles have high cmc's and low aggregation numbers when compared to other single-headed surfactants (most notably the sodium alkanoates). The conformational changes incurred by the carbon atoms upon micelle formation have been deduced from the 13C chemical shift differences (δsurf,mic - δsurf,aq). These results are used to discuss the formation of the aggregates of the sodium cyclohexylalkanoate surfactants as a function of the length of the alkanoate side chain.Key words: micelles, surfactants, NMR spectroscopy, chemical shifts, aggregation numbers, degree of counterion binding, conformational changes.

9-Borafluorenes – NMR spectroscopy and DFT calculations. Molecular structure of 1,2-(2,2′-diphenylylene)-1,2-diethyldiborane

2010 ◽  
Vol 75 (7) ◽  
pp. 743-756 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Peter Thoma ◽  
Rhett Kempe ◽  
Germund Glatz
Keyword(s):  
Molecular Structure ◽  
Nmr Spectroscopy ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Spin Coupling ◽  
X Ray Diffraction ◽  
Data Set ◽  
Chemical Shift Tensors ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling

9-Borafluorene derivatives 1 (9-R = Et (a), Ph (b), Cl (c), NEt2 (d)), the pyridine adduct 1py+ and 1,2-(2,2′-biphenylylene)-1,2-diethyldiborane(6) (3), were studied by 11B and 13C NMR spectroscopy to obtain a fairly complete data set for the first time. The molecular structure of the doubly hydrogen-bridged 1,2-diphenylenediborane 3 was determined by X-ray diffraction. The gas-phase structures of the compounds 1, related derivatives, and of some doubly hydrogen-bridged 1,2-diphenylenediboranes were optimized by quantum chemical calculations (B3LYP/6-311+G(d,p) level of theory) and NMR parameters, such as chemical shifts, 11B chemical shift tensors and indirect nuclear 13C–11B spin–spin coupling constants were calculated at the same level of theory and compared with experimental data.

13C, 15N, and 19F NMR spectra of 2-phenylhydrazonopropanedinitriles and methyl 2-phenyl hydrazonocyanoacetates

1984 ◽  
Vol 49 (12) ◽  
pp. 2801-2806 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Nmr Spectra ◽  
Electron Pair ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Azo Coupling ◽  
19F Nmr Spectra ◽  
Mutual Comparison ◽  
Cyano Groups ◽  
Free Electron Pair

13C, 15N, and 19F NMR spectra of the azo coupling products obtained from 4-X-benzenediazonium salts (X = H, F, NO2) and propanedinitrile (I) or methyl cyanoacetate (II) and of their 15N isotopomers have been measured. The 13C chemical shifts of cyano groups have been assigned unambiguously on the basis of the 2J(15Nβ13C) coupling constants, and mutual comparison of the 15N chemical shifts in compounds I and II enabled also the assignment of the15N chemical shifts of these groups. The 13C chemical shifts of cyano groups in cis position with respect to free electron pair at Nβ nitrogen atom are shifted downfield, whereas δ(15N) of the same groups exhibit upfield shifts as compared with the cyano in trans position. The azo coupling products of benzenediazonium salts and methyl cyanoacetate contain predominantly the E isomer even after long-term standing in hexadeuteriodimethyl sulphoxide.

Some Applications of Ultrahigh Resolution 15N NMR Spectroscopy

1998 ◽  
Vol 53 (4) ◽  
pp. 411-415 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Ēriks Kupče
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Absolute Magnitude ◽  
Natural Abundance ◽  
Coupling Constants ◽  
15N Nmr ◽  
Ultrahigh Resolution ◽  
Tert Butyl ◽  
15N Nmr Spectroscopy

Abstract Ultrahigh resolution 15N NMR spectra were measured for two nitroalkanes (MeNO2 la, tBuNO2 1c), two isocyanates (tBuNCO 2c, Me3SiNCO 2d), four isothiocyanates (MeNCS 3a, EtNCS 3b, tBuNCS 3c, Me3SiNCS 3d), one carbodiimide (Me3SiNCNSiMe3 4d), one keteneimine [Me3SiNCC(SiMe3)2 5d], two sulphinyl imides (tBuNSO 6c, Me3SiNSO 6d), and N-tert-butyl-pyrrole 7c, in order to determine coupling constants J(15N ,I3C) and isotope induced chemical shifts 1∆12/13C (15N) at the natural abundance of the isotopes. The values 1∆12/13C (15N) can be separated into two groups, one dealing with NC single and another one with NC double bonds. In each group (with few exceptions), the values 1∆12/13C (15N) become more negative with a decrease in the absolute magnitude of l1J(l5N ,13C)l. The corresponding values 1∆14/15N (13C) show a sim ilar behaviour. However, N-substituted pyrroles appear to be exceptional in this respect.

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