摘要:

Abstract2D NOESY, COSY and31P,1H correlation measurements have been carried out on the optically active β‐pineneallyl‐(R)(+)‐BINAP palladium complex, [Pd(η3‐C10H15){(R)(+)‐BINAP}](CF3SO3). Theorthoprotons of the four non‐equivalent phenyl rings have been assigned, as have the 15 protons of the β‐pineneallyl. The 2D NOE data show selective interactions of the phenylorthoprotons with different sections of the allyl ligand, thereby contributing to our knowledge of the three‐dimensional solution structure of thi

ISSN:0749-1581    

DOI:10.1002/mrc.1260290302

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe applicability of 2D EXSY NMR spectroscopy for studying quantitatively the dynamic behaviour in three aroylcyanoketene‐S,S‐dimethylacetals was tested by means of1H NMR spectroscopy. It can be concluded that the method is a reasonable qualitative supplement to complete line‐shape ana

ISSN:0749-1581    

DOI:10.1002/mrc.1260290303

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe1H and13C NMR spectra of eledoisin, an antidiuretic hormone, were studied by two‐dimensional NMR techniques. All the1H and13C NMR resonances were unambiguously determined from a combination of the 2D homo‐ and hetero‐nuclear NMR sp

ISSN:0749-1581    

DOI:10.1002/mrc.1260290304

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractPush‐pull alkenes with variable structure were investigated with respect to the influence of the different substituents at the central C,C double bond on the dynamic behaviour of this type of compound.1H and13C NMR spectroscopic investigations were carried out for ketene‐S,S‐, ‐S,N‐ and ‐N,N‐acetals. HMO calculations were employed to discuss the related π‐electron densi

ISSN:0749-1581    

DOI:10.1002/mrc.1260290305

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe1H NMR spectra and the barriers to rotation about exocyclic partial C,N double bonds of various series of thiazinethiones 1, the corresponding thiazinium salts 5–9 and some pyrimidinethiones 10–13 are reported and discussed with respect to the π‐electron deficiency of these heteroaromatic compounds. Substituent influences are critically considered; in particular, the C,N barrier differences of C,NMe2and C, pyrrolidino were used to estimate the type of dynamic process, which is different in pyrimidinethiones 10–13 and thiazinethiones/thiazinium salts 1–9. The compounds studied corroborate the pseudo‐chalcogeno analogy principle. Previously studied compounds are included to display the π‐electron deficiency influence of the heterocyclic system on the1H chemical shifts of NR2, phenyl, the H‐5 protons and the exocyclic barriers to C,N rotation; adequate quantitative estimat

ISSN:0749-1581    

DOI:10.1002/mrc.1260290306

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe34S isotope effect on the chemical shift of PIIInuclei in P(SR)3esters [R = Et, (C12H25)n, Ph] is close to 20.6 ppb per PIII34S bond, i.e. 3–4 times larger than for thiolo sulphur atoms in S = P(SR)3or O = P(SR)3. A similar behaviour is noted for the P(S)3sites in P4S9and P4S3and for the downfield triplet of P4S8, which, accordingly, is assigned to the tri‐coordinate P atoms of this sulphide.13C isotope effects are also reported for trialkyl(aryl) phosphorotrithioites andS,S,S‐phosphoro

ISSN:0749-1581    

DOI:10.1002/mrc.1260290307

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractSeveral 1D and 2D inverse proton editing pulse sequences have recently been introduced. One of these, the REPAY sequence, allows the individual editing of XH or XH2groups. Some new 2D combinations of one‐ and two‐dimensional REPAY experiments with a COSY or TOCSY transfer are described. These combinations provide various possibilities for structural elucidation: the determination of heteronuclear long‐range coupling constantsnJ(CH) (n= 2, 3), the editing of XH or XH2groups in two‐dimensional H,H COSY spectra and the editing of XH or XH2groups in X,H COSY spectra followed by a relayed transfer. In contrast to earlier versions of SHIPPED‐COSY experiments, the spectra show improved sensitivity and offer the possibility of selecting XH2groups only, and contain no1J(XH) coupling because of heteronuclear X d

ISSN:0749-1581    

DOI:10.1002/mrc.1260290308

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe1H and13C NMR spectra of 26 2,3‐dihydro‐[1,5]benzoxazepin‐4(5H)‐one derivatives and four thiono analogues are interpreted in terms of conformational equilibria. Similar to 1,3,4,5‐tetrahydro‐2H‐1,5‐benzodiazepin‐2‐ones, these compounds favour boat conformations of the seven‐membered ring. In the lactams the conformational energy difference is very low, whereas a difference of 0.3 kcal mol−1is recorded for the thionolactams, the conformation with the quasi‐axial methyl g

ISSN:0749-1581    

DOI:10.1002/mrc.1260290309

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe77Se,13C and1H NMR spectra of 46 mostly new compounds with phenylselenenyl groups attached to carbocycles and of three new corresponding selenoxides and the125Te NMR of phenyltellurenylcyclohexane are reported. Substituent effects on the chemical shifts of these nuclei are compiled and discussed in terms of the configuration and conformation. Low‐temperature NMR spectra of some cyclohexane derivatives allowed the evaluation of thermodynamic data, such asAvalues of the PhSe, PhSe(O) and PhTe group

ISSN:0749-1581    

DOI:10.1002/mrc.1260290310

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractSolid‐state CP‐MAS29Si‐,119Sn‐ and207Pb NMR spectra of bis(pentamethylcyclopentadienyl)‐silicon (1) ‐tin (2) and ‐lead (3) were measured. The spectra reflect the gross structural features, known from x‐ray analyses for 1–3. In 1a, which has a parallel arrangement of the Me5C5rings, the29Si nuclear shielding is found to be 20.2 ppm higher than that of the bent structure in 1b. The assignment is supported by the relative intensities of the29Si resonances and by the analyses of the spinning sideband patterns. The δ29Si value of 1 in solution is close to that of 1b, suggesting that the bent structure is preferred in solution. The comparison of the solution‐ and solid‐state δ values shows that the η5‐bonding of the cyclopentadienyl rings is retained in solution. Attempts to analyse the spinning sideband pattern of 2 by the usual methods failed, which may be explained by the presence of molecular reorientation in the solid state which occurs at room temperature at a rate affecting

ISSN:0749-1581    

DOI:10.1002/mrc.1260290311

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY