13C Nuclear magnetic resonance studies. XIV. Conformational effects on carbinyl carbon shieldings in cyclohexanols and derivatives

1969 ◽  
Vol 47 (19) ◽  
pp. 3605-3610 ◽  
Author(s):  
G. W. Buchanan ◽  
J. B. Stothers
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Free Energies ◽  
New Approach ◽  
Magnetic Resonance Studies ◽  
Conformational Effects ◽  
Alkyl Derivatives ◽  
Alkyl Groups ◽  
13C Nuclear Magnetic Resonance ◽  
Cis And Trans

The 13C shieldings of the alicyclic carbons bearing oxygen in several cyclohexanols, their acetates and methyl ethers depend on the orientation of the oxygen functions. The compounds examined include the cis- and trans-4-alkyl derivatives in which the alkyl groups are t-butyl,i-propyl, ethyl and methyl, as well as the 3-t-butyl isomers. The results for the parent compounds are employed for the estimation of the conformational free energies of the hydroxyl, acetoxyl, and methoxyl groups, and serve to establish that 13C magnetic resonance (c.m.r.) spectroscopy offers a new approach to conformational analysis. The data were obtained using the decoupling technique and materials containing 13C in natural abundance.

13C Nuclear Magnetic Resonance Studies of Organometallic Compounds. V. Di- and Trimethylplatinum(IV) Derivatives

1974 ◽  
Vol 52 (10) ◽  
pp. 1973-1982 ◽  
Author(s):  
Howard Charles Clark ◽  
Leo Ernest Manzer ◽  
John Edward Henry Ward
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Organometallic Compounds ◽  
Methyl Groups ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Cis And Trans ◽  
Nuclear Magnetic

The 13C n.m.r. parameters for thirteen di- and trimethylplatinum(IV) derivatives have been obtained. It is shown that the 13C shieldings and 1JPtC and 2JPtCH values of methyl groups both cis and trans to varied ligands consistently follow trends similar to those found for related methylplatinum(II) derivatives.

13C Nuclear Magnetic Resonance Studies of Organometallic Compounds. IV. cis-Dimethylplatinum(II) Derivatives

1974 ◽  
Vol 52 (7) ◽  
pp. 1165-1170 ◽  
Author(s):  
Howard Charles Clark ◽  
Leo Ernest Manzer ◽  
John Edward Henry Ward
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Organometallic Compounds ◽  
Methyl Groups ◽  
Magnetic Resonance Studies ◽  
Trans Influence ◽  
13C Nuclear Magnetic Resonance ◽  
Cis And Trans ◽  
Derivatives Of ◽  
Nuclear Magnetic

Data derived from the 13C n.m.r. spectra of seven neutral cis-dimethylplatinum(II) derivatives of the type cis-(CH3)2PtL2 and cis-(CH3)2Pt(L—L) (where L and L—L are neutral donors) are discussed and compared with data derived from the 1H n.m.r. spectra of the complexes. Simultaneous variations in L or L—L reveal that the n.m.r. trans-influence rather than the n.m.r. cis-influence is dominant. The suggestion that the n.m.r. cis- and trans-influences may be additive is discussed. In contrast with data obtained by other workers, it is shown that the 1JCH values of the platinum methyl groups are essentially insensitive to variations in the remaining ligands.

13C Nuclear magnetic resonance studies. XII. Conformational effects on 13C shieldings in alicyclic oxygenated compounds

1969 ◽  
Vol 47 (17) ◽  
pp. 3113-3118 ◽  
Author(s):  
G. W. Buchanan ◽  
J. B. Stothers ◽  
Siu-Tzyy Wu
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Similar Data ◽  
Free Energies ◽  
Methyl Substituent ◽  
Decoupling Method ◽  
Magnetic Resonance Studies ◽  
Oxygenated Compounds ◽  
Conformational Effects ◽  
13C Nuclear Magnetic Resonance ◽  
Proton Decoupling

The 13C shieldings of the primary carbinyl carbons in cyclohexylmethanol, its acetate and methyl ether as well as those for the corresponding carbon in their 4-t-butyl derivatives have been measured at 15.1 MHz using the 'proton-decoupling' method. Similar data for the 1-methyl-4-t-butylcyclohexylcarbinols and their acetates were obtained to examine the influence of the additional methyl substituent. Possible origins of the observed conformational effects on 13C nuclear shieldings are considered. The 1H results for the methylene protons in these carbinyl groups are also presented and discussed. These results, which permit estimations of the conformational free energies (−ΔG°) of the —CH2OR groupings (R = H, Ac, Me), are presented to illustrate the 13C approach to conformational analysis.

13C Nuclear Magnetic Resonance Studies. 34. The 13C Spectra of Several Methylcyclopentanones and -cyclohexanones

1974 ◽  
Vol 52 (2) ◽  
pp. 308-314 ◽  
Author(s):  
J. B. Stothers ◽  
C. T. Tan
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Model Systems ◽  
Trans Isomers ◽  
Magnetic Resonance Studies ◽  
Cis And Trans Isomers ◽  
13C Nuclear Magnetic Resonance ◽  
The Individual ◽  
Ring Distortion ◽  
Cis And Trans

The 13C spectra of 16 methyl substituted cyclohexanones and 15 methylcyclopentanones have been determined. These series were chosen as model systems for the study of steric and conformation effects on 13C shieldings. Complete assignments of the individual signals were accomplished by intercomparison of the shielding data within each series and the trends observed are readily interpreted in conformational terms. Each of the cyclohexanones exists preferentially in chair conformations although there is evidence of ring distortion in the tetramethyl derivatives. The cyclopentanones apparently strongly favor half-chair forms with maximum puckering at C-3 and C-4. In general, shielding differences between cis and trans isomers are pronounced and the assignment of stereochemistry for some cis–trans dimethyl derivatives is illustrated.Further examples of marked deshielding trends associated with sterically crowded δ nuclei in syn-axial arrangements are described.

13C Nuclear Magnetic Resonance Studies of Organometallic Compounds. III. cis-Methylplatinum(II) Derivatives

1974 ◽  
Vol 52 (4) ◽  
pp. 570-578 ◽  
Author(s):  
H. C. Clark ◽  
J. E. H. Ward
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Organometallic Compounds ◽  
Neutral Ligand ◽  
Magnetic Resonance Studies ◽  
13C Nuclear Magnetic Resonance ◽  
Related Series ◽  
Cis And Trans ◽  
Derivatives Of ◽  
Nuclear Magnetic

Eight new cis-methylplatinum(II) derivatives of the type DIARSPt(CH3)X (DIARS abbreviates o-phenylenebis(dimethylarsine), where X is an anionic substituent, and [DIARSPt(CH3)L]+PF6−, where L is a neutral ligand, have been prepared. Data derived from the 13C n.m.r. spectra of these complexes are discussed and compared with data derived from the 1H n.m.r. spectra of the complexes. Comparisons with the 13C n.m.r. parameters obtained from related series of trans-methylplatinum(II) derivatives reveal marked differences between the n.m.r. cis- and trans-influences. It appears that the n.m.r. cis-influence may in part be related to a ligand's "steric bulk".

X-Ray crystallographic and 13C nuclear magnetic resonance studies of 3,4,5,6-tetrahydro-2H-1,3,4-oxadiazin-2-ones derived from ephedrine and pseudoephedrine

Tetrahedron ◽  
2001 ◽  
Vol 57 (49) ◽  
pp. 9789-9798 ◽  
Author(s):  
Shawn R Hitchcock ◽  
George P Nora ◽  
David M Casper ◽  
Michael D Squire ◽  
Christopher D Maroules ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Studies ◽  
X Ray ◽  
13C Nuclear Magnetic Resonance ◽  
Nuclear Magnetic

Nuclear magnetic resonance studies of cis- and trans-2,3-dimethylcycloalkanones

1972 ◽  
Vol 37 (15) ◽  
pp. 2425-2428 ◽  
Author(s):  
P. E. Pfeffer ◽  
S. F. Osman
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Magnetic Resonance Studies ◽  
Cis And Trans ◽  
Nuclear Magnetic
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