The Structure of 1,3-Enaminoketonatoboron Difluorides in Solution and in the Solid State

2003 ◽  
Vol 56 (12) ◽  
pp. 1209 ◽  
Author(s):  
Kuniaki Itoh ◽  
Kazuhiko Okazaki ◽  
Miki Fujimoto
Keyword(s):  
Solid State ◽  
Nmr Spectra ◽  
Electron Distribution ◽  
Chelate Ring ◽  
Chemical Shifts ◽  
Electron System ◽  
The Other ◽  
13C Nmr Spectra ◽  
X Ray ◽  
Tautomeric Forms

Nuclear magnetic resonance, infrared, and ultraviolet spectra and X-ray analysis of three 1,3-enaminoketonatoboron difluorides (BF2 complexes, (2a)–(2c)) both in solution and in the solid state have been recorded. Their structures are discussed in relation to the electron distribution in their chelate rings and in comparison with those of their parent compounds (1a)–(1c) and 1,3-diketonatoboron difluorides. C1 and C3 chemical shifts in the 13C NMR spectra indicated that the ketoamine and enolimine tautomeric forms may be present in equal amounts. Additionally, the phenyl groups participate in the delocalized π-electron system of the chelate ring. On the other hand, in the solid state, a comparison of the bond lengths by X-ray analysis provides information on processes occurring as contribution of the enolimine form increases. The information found may offer valuable suggestions for the reactivity and the structure of the products for the reactions of the BF2 complexes.

17O and 13C NMR spectra of some geminal diacetates

1988 ◽  
Vol 53 (3) ◽  
pp. 588-592 ◽  
Author(s):  
Antonín Lyčka ◽  
Josef Jirman ◽  
Jaroslav Holeček
Keyword(s):  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
The Other ◽  
13C Nmr Spectra ◽  
Other Hand ◽  
Carboxylic Esters ◽  
C Nmr ◽  
Oxygen Atoms

The 17O and 13C NMR spectra of eight geminal diacetates RCH(O(CO)CH3)2 derived from simple aldehydes have been measured. In contrast to the dicarboxylates R1R2E(O(CO)R3)2, where E = Si, Ge, or Sn, whose 17O NMR spectra only contain a single signal, and, on the other hand, in accordance with organic carboxylic esters, the 17O NMR spectra of the compound group studied always exhibit two well-resolved signals with the chemical shifts δ(17O) in the regions of 183-219 ppm and 369-381 ppm for the oxygen atoms in the groups C-O and C=O, respectively.

Triferrocenylborane – Molecular Structure in Solution and in the Solid State

1995 ◽  
Vol 50 (2) ◽  
pp. 201-204 ◽  
Author(s):  
Bernd Wrackmeyer ◽  
Udo Dörfler ◽  
Wolfgang Milius ◽  
Max Herberhold
Keyword(s):  
Molecular Structure ◽  
Solid State ◽  
Low Temperature ◽  
Single Crystal ◽  
Nmr Spectra ◽  
The Other ◽  
X Ray ◽  
Single Diastereomer ◽  
Structure In Solution ◽  
C Nmr

According to a single crystal X-ray structure determination all three ferrocenyl substituents of triferrocenylborane (1) adopt the same orientation with respect to the BC3-plane [P21/c monoclinic; Z = 4; a = 1353.5(3), b = 1695.6(3), c = 1056.4(2) pm, β = 109.27(3)°]. The simulated X-ray powder pattern of the single crystal is identical with the powder diagram of a macroscopic sample, indicating the presence of a single diastereomer (1a) in the solid state. However, at low temperature (< - 95 °C) in solution, the 13C NMR spectra suggest the presence of the second diastereomer (1b) in which one ferrocenyl group is oriented opposite to the other two with respect to the central BC3-plane.

Thioanalogs of Sparteine Lactams [6]. Part II. (+)-2-Thionosparteinium Perchlorate

1999 ◽  
Vol 54 (10) ◽  
pp. 1307-1312 ◽  
Author(s):  
Teresa Borowiak ◽  
Grzegorz Dutkiewicz ◽  
Waleria Wysocka ◽  
Renata Kolanoś
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Intermolecular Hydrogen Bond ◽  
Solution Nmr ◽  
Boat Conformation ◽  
Coupling Constant ◽  
X Ray ◽  
Ir And Nmr Spectroscopy

(+)-2-Thionosparteinium perchlorate has been obtained and characterized by IR and NMR spectroscopy. On the basis of the coupling constant J7 - J17β and chemical shifts for C(12) and C( 14) a boat conformation of ring C is proposed. The infrared spectrum in the solid state indicates an intermolecular hydrogen bond N+-H···S. This has been ascertained by X-ray crystal structure determination: H···S - 2.44(8)Å, N+···S - 3.279(6)Å, N+- H···S - 160(6)°. The solution NMR spectra clearly show that the solid state stucture is retained in solution.

scholarly journals 13C and15N NMR shieldings of 1,2,4-diazaphospholes in the solid state and in solution

2001 ◽  
Vol 15 (1) ◽  
pp. 27-32 ◽  
Author(s):  
R.M. Claramunt ◽  
C. López ◽  
A. Schmidpeter ◽  
A. Willhalm ◽  
J. Elguero ◽  
...  
Keyword(s):  
Solid State ◽  
Proton Transfer ◽  
Ab Initio Calculations ◽  
Ab Initio ◽  
Single Crystals ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Cyclic Dimer ◽  
X Ray ◽  
The Absolute

The solid state13C and15N CPMAS NMR spectra of 3,5-di-tert-butyl-1,2,4-diazaphosphole4and 3,5-diphenyl-1,2,4-diazaphosphole5have been recorded. The X-ray structure of the first compound was already known (it is a cyclic dimer with localized N–H protons) while the structure of the second cannot be determined due to the difficulty to grow suitable single crystals. NMR results pointed out that4is a “classical” compound while5is probably a tetramer showing Intermolecular Solid-State Proton Transfer (ISSPT). GIAO/ab initio calculations have been carried out to estimate the absolute1H,13C and15N shieldings. The agreement with the experimental chemical shifts is good enough to assign the signals of carbons C-3 and C-5.

scholarly journals Synthesis of C2-Symmetrical Bis-(β-Enamino-Pyran-2,4-dione) Derivative Linked via 1,6-Hexylene Spacer: X-ray Crystal Structures, Hishfeld Studies and DFT Calculations of Mono- and Bis-(Pyran-2,4-diones) Derivatives

Symmetry ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1646
Author(s):  
Ahmed T. A. Boraei ◽  
Matti Haukka ◽  
Ahmed A. M. Sarhan ◽  
Saied M. Soliman ◽  
Abdullah Mohammed Al-Majid ◽  
...  
Keyword(s):  
Dft Calculations ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
X Ray ◽  
Crystal Stability ◽  
Dione Derivative ◽  
Intermolecular Contacts ◽  
First Time

The synthesis of C2-symmetrical bis(β-enamino-pyran-2,4-dione) derivative 3 connected via 1,6-hexylene linker was reported for the first time. X-ray structures and Hirshfeld studies of the new bis- β-enamino-pyran-2,4-dione derivative 3 along with two structurally related pyran-2,4-dione derivatives 2a,b were discussed. A comparative analysis of the different intermolecular contacts affecting the crystal stability was presented. Generally, the H…H, O…H, and H…C interactions are common in all compounds and are considered the most abundant contacts. In addition, DFT calculations were used to compute the electronic properties as well as the 1H and 13C NMR spectra of the studied systems. All compounds (except 3) are polar where 2a (3.540 Debye) has a higher dipole moment than 2b (2.110 Debye). The NMR chemical shifts were calculated and excellent correlations between the calculated and experimental data were obtained (R2 = 0.93–0.94).

The structure of 2,2-dibutyl-1,3,2-dioxastannane in the solid state and in solution

1992 ◽  
Vol 70 (1) ◽  
pp. 197-204 ◽  
Author(s):  
T. Bruce Grindley ◽  
Rasiah Thangarasa ◽  
Pradip K. Bakshi ◽  
T. Stanley Cameron
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Carbon Atom ◽  
Low Temperature ◽  
Nmr Spectra ◽  
Monomer Unit ◽  
The Other ◽  
Mirror Plane ◽  
X Ray ◽  
X Ray Crystallography

Crystals of 2,2-dibutyl-1,3,2-dioxastannane (1) are orthorhombic, of space group Pnma, with a = 7.663(3), b = 18.437(2), c = 9.277(4) Å, Z = 4, R = 0.0568 (Rw = 0.0551) for 1183 independent reflections with I > 3σ(I). Compound 1 is a polymer in which each monomer unit is joined to the next by a four-membered (SnO)2 ring. The Sn—O bond lengths inside the monomer units average 2.04 Å while those between monomers average 2.57 Å. The mirror plane of the crystal contains the atoms in the four-membered rings and the other oxygen atoms. Two of the three remaining carbon atoms in the six-membered rings of the monomer units are close to the mirror plane. The other carbon atom is disordered above and below the plane. It was shown by 119Sn NMR spectroscopy that solutions of 1 contain mixtures of oligomers that consist mainly of dimers, trimers, and tetramers in chloroform-d. ΔG0 values for dimmer–trimer equilibria and dimmer–tetramer equilibria of −2.5 and −1.5 kcal mol−1 were obtained from integration of low temperature 119Sn NMR spectra. These values favour the higher oligomers slightly less than those for 2,2-dibutyl-1,3,2-dioxastannolane. Keywords: 1,3,2-dioxastannanes, stannylene acetals. X-ray crystallography, 119Sn NMR spectroscopy.

Some Considerations Regarding the 1H and 13C Spectra of 4-(1-azulenyl)-2,6-bis(2-heteroaryl-vinyl)- pyrylium and Pyridinium and their Corresponding Pyridines

2018 ◽  
Vol 69 (1) ◽  
pp. 64-69
Author(s):  
Liviu Birzan ◽  
Mihaela Cristea ◽  
Constantin C. Draghici ◽  
Alexandru C. Razus
Keyword(s):  
Double Bond ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Pyridinium Salts ◽  
13C Nmr Spectra ◽  
1H And 13C Nmr ◽  
Pyrylium Salts

The 1H and 13C NMR spectra of several 2,6-diheteroarylvinyl heterocycles containing 4-azulenyl moiety were recorded and their proton and carbon chemical shifts were compared with those of the compounds without double bond between the heterocycles. The influence of the nature of central and side heterocycles, molecule polarization and anisotropic effects were revealed. The highest chemical shifts were recorded for the pyrylium salts and the lowest at pyridines, but in the case of the pyridinium salts, the protons chemical shifts at the central heterocycle are more shielded due to a peculiar anisotropy of the attached vinyl groups.

The Electron Effect of Aromatic Group: Control Conformation of 2-Aromatic Cyclododecanone Derivatives

2020 ◽  
Vol 24 (10) ◽  
pp. 1139-1147
Author(s):  
Yang Mingyan ◽  
Wang Daoquan ◽  
Wang Mingan
Keyword(s):  
1H Nmr ◽  
13C Nmr ◽  
Nmr Spectra ◽  
Coupling Constants ◽  
The Other ◽  
Repulsive Interaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Effect ◽  
Group Control

2-Phenylcyclododecanone and 2-cyclohexylcyclododecanone derivatives were synthesized and characterized by 1H NMR, 13C NMR, HR-ESI-MS and X-ray diffraction. Their preferred conformations were analyzed by the coupling constants in the 1H NMR spectra and X-ray diffraction, which showed the skeleton ring of these derivatives containing [3333]-2-one conformation, and the phenyl groups were located at the side-exo position of [3333]-2-one conformation due to the strong π-π repulsive interaction between the π- electron of benzene ring and π-electron of carbonyl group. The cyclohexyl groups were located at the corner-syn or the side-exo position of [3333]-2-one conformation depending on the hindrance of the other substituted groups. The π-π electron effect played a crucial role in efficiently controlling the preferred conformation of 2-aromatic cyclododecanone and the other 2-aromatic macrocyclic derivatives with the similar preferred square and rectangular conformations.

Proximity and conformation effects in 29Si and 13C NMR spectra of di-ortho substituted trimethylsiloxybenzenes

1990 ◽  
Vol 55 (8) ◽  
pp. 2027-2032 ◽  
Author(s):  
Jan Schraml ◽  
Robert Brežný ◽  
Jan Čermák
Keyword(s):  
Benzene Ring ◽  
13C Nmr ◽  
Proximity Effect ◽  
Nmr Spectra ◽  
Methoxy Group ◽  
Chemical Shifts ◽  
Proximity Effects ◽  
13C Nmr Spectra ◽  
Methoxy Groups ◽  
C Nmr

29Si and 13C NMR spectra of five 4-substituted 2,6-dimethoxytrimethylsiloxybenzenes were studied with the aim to elucidate the nature of the deshielding proximity effects observed in the spectra of ortho substituted trimethylsiloxybenzenes. The sensitivity of 29Si chemical shifts to para substitution is in the studied compounds essentially the same as in mono ortho methoxytrimethylsiloxybenzenes. The deshielding proximity effect of the ìsecondî methoxy group is somewhat smaller than that of the ìfirstî group. The present results indicate that the two methoxy groups assume coplanar conformations with the benzene ring and are turned away from the trimethylsiloxy group which is not in the benzene plane. It is argued that in mono ortho methoxytrimethylsiloxybenzenes the two substituent groups adopt the same conformations as in the compounds studied here.

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