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.

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.

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.

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