(Cyclopentadienyl)dihalogenochromium-Donor Compounds. Synthesis and NMR Investigation

1995 ◽  
Vol 50 (11) ◽  
pp. 1739-1747 ◽  
Author(s):  
Brigitte Bräunlein ◽  
Frank H. Köhler ◽  
Werner Strauß ◽  
Harald Zeh
Keyword(s):  
Dynamic Behavior ◽  
Spin Density ◽  
Nmr Spectra ◽  
Rapid Identification ◽  
Spin Transfer ◽  
H Nmr ◽  
Electronegative Substituent ◽  
Intramolecular Dynamic ◽  
Nmr Signals

A series of paramagnetic (S = 3/2) chromium half-sandwiches of the type CpCrX2D (D = donor) were synthesized by starting from [CpCrX2]2, Cp2Cr, CpCrCl2(THF), and Cp*Cr(CH3)2[P(CH3)3]. Besides the parent cyclopentadienyl (Cp) the alkylated derivatives CH3C5H4, (CH3)5C5 (Cp*), and C2H5(CH3)4C5 were bound to chromium. The electronegative substituent was X = F, Cl, Br, I, and triflate, while the donors were three ethers, four ketones, dimethylsulfoxide, acetonitrile, methylisocyanide, pyridine, and seven molecules ER3 where E = N, P, As, Sb. The half-sandwiches were partly isolated and partly established in solution. The 13C and 1H NMR spectra showed strongly shifted signals which allowed to quantitatively investigate the equilibrium between CpCrX2D and the anti ferromagnetic species [CpCrX2]2. The NMR signals of CpCrX2D and its substituted derivatives appeared in characteristic ranges thus providing a means of rapid identification. Considerable spin density was found to be induced on the ligands; it is negative in the Cp π system. As for the donors, inter- and intramolecular dynamic behavior as well as selective spin transfer to the γ protons of acetonitrile, methylisocyanide, and ketones was detected.

scholarly journals 13C and 1H NMR Spectra of Synthetic (25R)-5α-Spirostanes

1999 ◽  
Vol 23 (1) ◽  
pp. 48-49
Author(s):  
Martín A. Iglesias Arteaga ◽  
Carlos S. Pérez Martinez ◽  
Roxana Pérez Gil ◽  
Francisco Coll Manchado
Keyword(s):  
1H Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
1H Nmr Spectra ◽  
H Nmr ◽  
C 23 ◽  
Main Effects ◽  
Nmr Signals

The assignment of 13C and 1H NMR signals of synthetic (25 R)-5α-spirostanes is presented; the main effects on chemical shifts due to substitution at C-23 are briefly discussed.

Electronic structure of low-spin six-coordinate iron(III) meso-tetrapropylchlorin complexes

2014 ◽  
Vol 18 (08n09) ◽  
pp. 778-791 ◽  
Author(s):  
Akira Ikezaki ◽  
Jyunpei Ono ◽  
Yoshiki Ohgo ◽  
Mari Fukagawa ◽  
Takahisa Ikeue ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Ground State ◽  
Nmr Spectra ◽  
Spectroscopic Properties ◽  
H Nmr ◽  
Axial Ligands ◽  
Splitting Parameter ◽  
Nmr Signals ◽  
Electronic Ground ◽  
C Nmr

Low-spin iron(III) tetrapropylchlorins [ Fe ( T n PrC ) L 2]± (L = HIm, 1-MeIm, DMAP, CN-, 4-CNPy, tBuNC) adopt the dxy-type ground state regardless of the nature of axial ligands. Among the complexes examined, [ Fe ( T n PrC )( t BuNC )2]+ has shown quite unique spectroscopic properties as described below. (1) 1 H NMR signals were extremely broad as compared with those of other complexes. In particular, 5,20- CH 2(α) signal was too broad to detect. (2) No signals except C γ were observed in 13 C NMR spectra. (3) Tetragonal splitting parameter (|Δ|) estimated by the EPR g values at 4.2 K reached as much as 12.4 λ, which is the largest |Δ| value among all the low-spin iron(III) porphyrins and porphyrinoids reported previously. On the basis of these results, we have concluded that [ Fe ( T n PrC )( t BuNC )2]+ adopts the low-spin iron(III) with (dxz, dyz)4(dxy)1 electronic ground state at 4.2–30 K where the EPR spectra are taken, while it should be expressed as the low-spin Fe ( II ) chlorin π-radical cation [ Fe II ( T n PrC .)( t BuNC )2]+ at ambient temperature where the NMR spectra are taken.

Investigation of Luminescent Poly(propylene imine) Dendrimer

2008 ◽  
Vol 8 (9) ◽  
pp. 4329-4334 ◽  
Author(s):  
Kana Tamano ◽  
Toyoko Imae
Keyword(s):  
Emission Band ◽  
Nmr Spectra ◽  
Chemical Structure ◽  
Acidic Solution ◽  
Structure Change ◽  
H Nmr ◽  
Long Time ◽  
Poly Propylene ◽  
Nmr Signals ◽  
Comparable Intensity

Luminescence phenomenon from NH2-terminated third generation poly(propylene imine) dendrimers in water was investigated. Two excitation bands (340 and 370 nm) and corresponding emission bands (∼400 and ∼450 nm, respectively) were detected. Emission bands were intensified with time, heating and air-bubbling and converged at certain intensities, where the ∼400 nm band was red-shifted. The initially weak emission band at ∼450 nm in an alkaline solution was intensified up to the comparable intensity to the strongest emission band at ∼400 nm in an acidic solution, after long time. While 1H NMR spectra depended on pH owing to the protonation of amine, those were slightly affected by the time, heating and air-bubbling. However, no new 1H NMR signals appeared even after long time, indicating no finding of chemical structure change of dendrimer. This suggests that the luminescent property should result from any interaction of amine with oxygen but not the chemical reaction.

Bicyclo[3.2.1]octa-2,6-dienyllithium and -potassium Chemistry Solvation, Aggregation, and 119Sn-7Li Coupling of Stannylated Derivatives

1990 ◽  
Vol 45 (6) ◽  
pp. 848-856 ◽  
Author(s):  
Norbert Hertkorn ◽  
Frank H. Köhler
Keyword(s):  
Nmr Spectra ◽  
Ion Pair ◽  
Lithium Cation ◽  
H Nmr ◽  
Triple Ions ◽  
Nmr Signals ◽  
Independent Confirmation ◽  
Triple Ion ◽  
C Nmr ◽  
Very Low Temperature

The 13C NMR spectra of bicyclo[3.2.1]octa-2,6-dienyl anion (1) as the lithium (1 Li) and the potassium salt (1 K) were recorded at various temperatures and in different solvents. The results show 1K to exist as a contact ion pair (CIP), whereas for 1 Li solvent separated ions (SSIP) are also found as the temperature is lowered and when the solvating power of the solvent is increased. In the 7Li NMR spectra at very low temperature the signals of the SSIP disappear and only those of a monomeric CIP and a triple ion (1 Li 1) consisting of two carbanions and one lithium cation are present. For independent confirmation, the hitherto unknown 6-, 7-, and 3-trimethylstannyl substituted bicyclo[3.2.1]octa-2,6-dienyllithium derivatives 2 a Li, 2 b Li, and 3 Li were synthesized and also studied by 119Sn, 13C, and 1H NMR. According to the temperature dependence of the δ(13C)-values the CIP/SSIP-equilibrium of 2 a Li in THF/TMEDA is shifted to the CIP side. The observation of a unique 119Sn-7Li coupling (6.2 Hz) shows that at –90 °C a species containing 2 a and lithium exists under slow exchange conditions. A similar coupling of 3.5 Hz can be estimated for 3Li. A mixture of the epimeric carbanions 2a and 2 b yields two sets of 13C NMR signals which are due to the diastereomeric triple ions 2 aLi 2 a and 2 aLi 2 b.

scholarly journals Nor-kurarinone Characteristic of Chinese Sophora flavescens

2019 ◽  
Vol 14 (1) ◽  
pp. 1934578X1901400
Author(s):  
Ryuichiro Suzuki ◽  
Utsumi Takahiro ◽  
Risa Takao ◽  
Yoshiaki Shirataki
Keyword(s):  
Nmr Spectra ◽  
Hplc Analysis ◽  
Sophora Flavescens ◽  
Nmr Metabolomics ◽  
Root Extracts ◽  
H Nmr ◽  
Plot Analysis ◽  
Metabolomics Study ◽  
Loading Plot ◽  
Nmr Signals

The root of Sophora flavescens is used as a Chinese crude drug for treating various disorders. S. flavescens is grown in Japan, China and Korea. We previously used Principle Component Analysis (PCA) to demonstrate that 1H NMR spectra of root extracts of S. flavescens can be used to identify the country of origin of the sample (Japan or China). In the present study we identified a compound characteristic of Chinese S. flavescens using NMR metabolomics. Loading plot analysis of the PCA results and an NMR metabolomics study identified NMR signals from a compound identified as nor-kurarinone and characteristic of Chinese S. flavescens grown in Hangzhou. This compound was confirmed by HPLC analysis to be a distinctive marker for Chinese S. flavescens.

Conformational structure of ethylene glycol dibenzoate. Vibrational and NMR spectra

1981 ◽  
Vol 46 (8) ◽  
pp. 1913-1929 ◽  
Author(s):  
Bohdan Schneider ◽  
Pavel Sedláček ◽  
Jan Štokr ◽  
Danica Doskočilová ◽  
Jan Lövy
Keyword(s):  
Ethylene Glycol ◽  
Vibrational Spectra ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
Conformational Structure ◽  
Infrared And Raman Spectra ◽  
H Nmr ◽  
Liquid States ◽  
Crystalline Forms ◽  
C Nmr

It was found that three crystalline forms of ethylene glycol dibenzoate can be prepared. Infrared and Raman spectra of these three forms, as well as of the glassy and liquid states, were measured. From 3JHH coupling constants obtained by analysis of the 13C satellite band of the -CH2- group in 1H NMR spectra, and from the 3JCH coupling constants of the -CO.O.CH2- fragment obtained by analysis of the carbonyl band in 13C NMR spectra it was found that in the liquid state the -CH2-CH2- group exists predominantly in the gauche conformational structure, and the bonds C-O-C-C assume predominantly a trans orientation. The results of the analysis of NMR and vibrational spectra were used for the structural interpretation of conformationally sensitive bands in vibrational spectra of ethylene glycol dibenzoate.

Preparation and absolute configuration at C(20) of 21-nor-5α-chol-22-en-24→20-olide derivatives

1981 ◽  
Vol 46 (4) ◽  
pp. 917-925 ◽  
Author(s):  
Vladimír Pouzar ◽  
Miroslav Havel
Keyword(s):  
Absolute Configuration ◽  
Nmr Spectra ◽  
Lithium Salt ◽  
H Nmr ◽  
Chemical Correlation ◽  
Unsaturated Lactones

Reaction of the aldehyde I with the lithium salt of 1-(2-tetrahydropyranyloxy)-2-propyne yielded the compounds II and IV. From the compound II the lactone XII was prepared via the intermediates III and X, the lactone XVIII was prepared from the substance IV via the intermediates V and XVI. The unsaturated lactones XII and XVIII were also prepared by sulfenylation and dehydrosulfenylation of the saturated lactones XIII and XIX. Based on chemical correlation and 1H-NMR spectra analyses of the compounds II and IV, the lactone XII was assigned the 20R-configuration whereas the lactone XVIII was allotted the 20S-configuration.

New type of addition to 5-substituted 4-arylidene-2-(4,5-dihydrofurfurylidene)-N,N-dimethyliminium bisperchlorates. Preparation of 4-substituted 5-(N,N-dimethylamino)-2-furancarbaldehydes

1986 ◽  
Vol 51 (3) ◽  
pp. 573-580 ◽  
Author(s):  
Tibor Gracza ◽  
Zdeněk Arnold ◽  
Jaroslav Kováč
Keyword(s):  
Nmr Spectra ◽  
Addition Reaction ◽  
H Nmr ◽  
Organic Bases ◽  
New Type

4-Arilidene-5-(N,N-dimethyliminium)-2-(4,5-dihydrofurfurylidene)-N,N-dimethyliminium bisperchlorate I undergoes a 1,4-addition reaction with organic bases under re-formation of the furan nucleus; this behaviour has been utilized in the preparation of new 4-substituted 5-(N,N-dimethylamino)-2-furancarbaldehydes II, III. The structure of the prepared compounds has been confirmed by 13C and 1H NMR spectra.

Preparation, properties and structure of some intermediate nido- and arachno-monocarbaboranes

1981 ◽  
Vol 46 (10) ◽  
pp. 2345-2353 ◽  
Author(s):  
Karel Baše ◽  
Bohumil Štíbr ◽  
Jiří Dolanský ◽  
Josef Duben
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Nmr Spectra ◽  
Liquid Ammonia ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Starting Compound

The 6-N(CH3)3-6-CB9H11 carbaborane reacts with sodium in liquid ammonia with the formation of 6-CB9H12- which was used as a starting compound for preparing the 4-CB8H14, 9-L-6-CB9H13 (L = (CH3)2S, CH3CN and P(C6H5)3), 1-(η5-C5H5)-1,2-FeCB9H10-, and 2,3-(η5-C5H5)2-2,31-Co2CB9H10- carboranes. The 4-CB8H14 compound was dehydrogenated at 623 K to give 4-(7)-CB8H12 carborane. Base degradation of 6-N(CH3)3-6-CB9H11 in methanol resulted in the formation of 3,4-μ-N(CH3)3CH-B5H10. The structure of all compounds was proposed on the basis of their 11B and 1H NMR spectra and X-ray diffraction was used in the case of the transition metal complexes.

The preparation of 3-amino-3-deoxy-1,2-O-isopropylidene-α-L-erythrofuranose, 3-amino-3-deoxy-1,2-O-isopropylidene-β-D-threofuranose and their derivatives

1980 ◽  
Vol 45 (12) ◽  
pp. 3378-3390 ◽  
Author(s):  
Jiří Jarý ◽  
Milena Masojídková ◽  
Ivan Kozák ◽  
Miroslav Marek ◽  
Jan Staněk
Keyword(s):  
Nucleophilic Substitution ◽  
Sodium Azide ◽  
Sodium Benzoate ◽  
Nmr Spectra ◽  
Subsequent Reduction ◽  
H Nmr ◽  
Amino Derivatives

The title amino derivatives VI and XIV were prepared by nucleophilic substitution of p-toluenesulfonyl derivatives II and XVII with sodium azide or hydrazine and subsequent reduction. Nucleophilic substitution of compounds II and XVII with sodium benzoate was also investigated. The 1H NMR spectra of the substances prepared are discussed.

Sign in / Sign up

Export Citation Format

Share Document