摘要:

AbstractThe13C NMR spectra of some 1,3‐diaryltriazenes, 3(1)‐aryl‐1(3)‐hetaryltriazenes and their methylated derovatives have been recorded. From the comparison of the13C chemical shifts between 3‐aryl‐1‐(3,4‐dimethyl‐5‐isoxazolyl)triazenes 1 and compounds with fixed structure, such as 1‐aryl‐3,3‐dimentyltriazenes and methylated derivatives of 5‐amino‐3,4‐dimethylisxazole, we found that the triazenes 1 have the sturcture (A) in which the azo group is conjugated with the heterocycllic moiety.para‐Substituent on the aromatic ring have a week influence on the displacement of this tautomeric equilibrium.13C NMR gives only qualitatives results. Theoretical calculation (HMO, CNDO‐2) are also consistent with the gre

ISSN:0030-4921    

DOI:10.1002/mrc.1270140402

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractThe results of13C and (when pertinent)77Se NMR spectra of thiopene and selenophene derivatives containing exocyclic selenium atoms are presented. The77Se spectra show an interaction between nitro or carbonyl groups and selenium when they areorthoto each other. The measurement of1J(SeSe),2J(SeSe) and3J(SeSe) has been attempted on disymmetric diselenides; only1J(SeSe) can be measured and values are very low, generally below 20 Hz. Other coupling cannot be observed and are smaller than the line width, which is 2 Hz. No theoretical interpretation can be advanced at present.

ISSN:0030-4921    

DOI:10.1002/mrc.1270140403

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractThe solvent shifts of the methylenic protond of CH2Cl2, CH2Br2and CH2I2have been measured in amines, ethers and non‐polar solvents. Correlation of the solvent shifts of the bromine and iodine compounds ΔCl, serves as a monitor of halogen bonding interactions which are competitive with hydrogen bonding association. Amines interact with CH2I2via a halogen bond while in ethers hydrogen bonding predpminates. CH2Br2shows solute–solvent interactions identical to CH

ISSN:0030-4921    

DOI:10.1002/mrc.1270140404

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractThe position and the isotope distribution within labelled compounds can be determined by NMR by analysing the difference spectrum, and its integral, of the labelled and the corresponding parent compound. The method is applied tom‐terphenyl and it 4–4″‐dideutero der

ISSN:0030-4921    

DOI:10.1002/mrc.1270140405

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractUsing the analysis of the splitting constants of the ESR spectra, factor are described which affect the stability of free phenoxyls and of phenoxyls co‐ordinated on cobalt, generated by the reaction oftert‐butyleperoxyls and 4,4′‐biphenyldiols (1), 4,4′–thiobisphenols (2 and 5), 4,4′‐dithiobisphenol 3a, the 4,4′‐trithiobisphenol 3b, di(3,5‐di‐tert‐butyl‐4‐hydroxybenzyl) sulphide (4a) and its corresponding sulphoné (4b). Phenoxy radicals are formed from compounds of type 1–4 in the presence and in the absence of oxygen. In the case of generation with oxygem complexed to cobalt, compounds 4, for steric reasons, form co‐ordinated radicals of the cyclohexadienonyloxyl type. Free phenoxyls are also formed from 2a–2c, 3a and 3b as a result of the direct transfer of electrons from the sulphur non‐bonding electron pair to the peroxidic bond oftert‐buty

ISSN:0030-4921    

DOI:10.1002/mrc.1270140406

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractThe signal shifts caused by replacing the carbonyl oxygen by sulphur represent a valuable method of assignment of the13C NMR signals in coumarins and furocoumarins substituted at the benzoic and furanoic rings.

ISSN:0030-4921    

DOI:10.1002/mrc.1270140407

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

Abstract19F and1H NMR spectra of the products of nucleophilic attack on octafluoroindene are analysed and structures assigned. The major product in the reaction of butyllithium with octafluoroindene is 3‐methylheptafluoroindene, with sodium borohydride it is 2‐hydroheptafluoroindene and with sodium methoxide it is 3‐methoxyheptafluoroindene. Vacuum pyrolysis of undecafluorotricyclo[5.2.2.02,6]undeca‐ 2,5,8‐triene, with elimination of C2F4, gives 6‐hydroheptafluoroindene as the major product. The NMR assignments are based on the unambiguous synthesis via vacuum pyrolysis of 5,6‐dihydrohexafluoroindene, 3‐hydro‐ and 3‐methyl‐heptafluoroindene and the large long‐range coupling of 15 Hz assigned to t

ISSN:0030-4921    

DOI:10.1002/mrc.1270140408

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractUsing a topological parameter, λR, to characterize the effects of a variable mono or polyalkyl environment,R, on widely varied types of13C sites gives rise to a homogeneous description of their chemical shifts over the entire range of δ13C variation (220 ppm/TMS). The proposed model, δ13C=ωcλR+ηcexpresses the chemical shift in terms of this parameter together with the sensitivity, ωc, of the perturbed13C site, bonded to a constant environment in a given family, and with ηcas the reference shift. In the case of polyalkyl environments,R=∑ i= 1NRi(n ⩽ 4); since the use of λRpresupposes that groupsRicoexist inRwithout interacting, it is expressed as the sum of the intrinsic effects of each of these groups. Thus, this model demonstrates the general character of most of the common alkyl environment effects and the specific behaviour of the various types of13C atoms. The homogeneity of this description relies on an assessment of theRicontribution by the DARC/PELCO topological analysis of alkyl sites in a series of reference alkynes. The δ13C values calculated for 138 compounds, belonging to the alkane, alkene, allene, alcohol, amine, epoxide, ester and ketone families, are highly satisfactory (r̄

ISSN:0030-4921    

DOI:10.1002/mrc.1270140409

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractThe overlapping spin systems in the 220 MHz1H spectra of 1‐methylfluorene (1) in carbon disulphide and deuteriated chloroform solutions have been analysed separately and refined by LAOCOON with the aid of methyl‐ and methylene‐decoupled spectra.Ortho‐coupling constants in the 6‐membered rings are similar to each other and to those in fluorene (4). Solvent and concentration shifts suggest loose pairing of solute molecules. 220 MHz1H spectra of α‐truxene (2) in carbon tetrachloride and deuteriated nitrobenzene, 220 MHz1H spectra of decacyclene (3) in carbon tetrachloride, and 90 MHz FT1H spectra of 3 in deuteriated chloroform show steric deshielding; the solvent dependence of shifts also suggests solute pairing in 2. Shifts in1H decoupled 22.6 MHz13C spectra of 2 in deuteriated chloroform were assigned with the aid of Cr(acac)3rela

ISSN:0030-4921    

DOI:10.1002/mrc.1270140410

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY

摘要:

AbstractThe tetraphenyl–metal, hexaphenyl–dimetal, and triphenylchloro–metal derivatives of the Group IV elements were examined using13C NMR methods. Chemical shifts and metal–carbon coupling constants were obtained for all compounds

ISSN:0030-4921    

DOI:10.1002/mrc.1270140411

出版商:John Wiley&Sons Limited    

年代:1980

数据来源: WILEY