Sign determination of coupling constants in CF2H and CF3 derivatives of silver(III)

1997 ◽  
Vol 35 (10) ◽  
pp. 707-711 ◽  
Author(s):  
Reint Eujen ◽  
Berthold Hoge
Keyword(s):  
Coupling Constants ◽  
Derivatives Of ◽  
Sign Determination

Convenient Sign Determination of Various Coupling Constants in Alkynylplatinum(II) Phosphine Complexes

1991 ◽  
Vol 46 (1) ◽  
pp. 35-38 ◽  
Author(s):  
Bernd Wrackmeyer
Keyword(s):  
Coupling Constants ◽  
Two Dimensional ◽  
Model Compounds ◽  
Standard Equipment ◽  
Phosphine Complexes ◽  
Sign Determination

(1)The utilization of two-dimensional (2 D) 13C /1H , 31P/1H and 195Pt/1H heteronuclear shift correlations for the sign determination of various coupling constants [e.g., 2J(31PPt13C) > 0 (trans), 2J(31PPt13C) < 0 (cis), 3J( 31PPtC13C) > 0 (cis, trans), 4J(31PPtCC1H ) > 0 (trans), 4J(31PCC1H ) < 0 (cis), 3J(195PtCC1H ) > 0, 2J(31PC1H ) < 0, etc.] is demonstrated, using standard equipment. The complexes [trans-(Bu3P)2Pt(C ≡ C -H)2] and [cis-(Et2PCH2CH2PEt2)Pt(C ≡ C - H)2] (2) serve as model compounds.

A proton magnetic resonance determination of the small rotational barriers about the C—Si bond in phenyl derivatives of chloro and methyl silanes

1977 ◽  
Vol 55 (3) ◽  
pp. 557-561 ◽  
Author(s):  
William J. E. Parr ◽  
Ted Schaefer
Keyword(s):  
Magnetic Resonance ◽  
Proton Magnetic Resonance ◽  
Coupling Constants ◽  
Spin Coupling ◽  
Molecular Orbital Calculations ◽  
Spin Coupling Constants ◽  
Spin Spin Coupling ◽  
Derivatives Of ◽  
Low Energy Conformations

The long-range spin–spin coupling constants between protons bonded to silicon and ring protons in C6H5SiH3, C6H5SiH2Cl, C6H5SiH2CH3, C6H5SiHCl2, and C6H5SiH(CH3)2 are determined from the proton magnetic resonance spectra of benzene solutions. A hindered rotor treatment of the barrier to internal rotation about the C—Si bond, in conjunction with the coupling constants over six bonds, allows the deduction of the low-energy conformations for C6H5SiH(CH3)2 and for C6H5SiHCl2, as well as of barriers of 1.0 ± 0.2 kcal/mol. The approach becomes less reliable for C6H5SiH2CH3 and for C6H5SiH2Cl and, particularly for the latter compound, the derived barrier is very likely an upper limit only. Ab initio molecular orbital calculations of the conformational energies are reported for C6H5SiH3, C6H5SiH2Cl, and for C6H5SiHCl2.

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.

Relative sign determination of phosphorus-carbon coupling constants by 2D carbon-13 NMR spectroscopy

1989 ◽  
Vol 8 (2) ◽  
pp. 568-571 ◽  
Author(s):  
Leslie H. Randall ◽  
Andrew A. Cherkas ◽  
Arthur J. Carty
Keyword(s):  
Nmr Spectroscopy ◽  
Coupling Constants ◽  
Relative Sign ◽  
Sign Determination
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