bluuebunny/crossref_metadata_2025_split huggingface dataset:
1H and 13C NMR study of novel fused 1,2,4‐triazole heterocycles
Authors: Szabó Zoltán , Kóródi Ferenc , Batta Gyula 
Published: May 2005

AbstractThe 1H and 13C NMR spectra of some novel 1,2,4‐triazolo [1,3] thiazinoquinoline isomeric pairs are interpreted in terms of structural assignments. The structure of most compounds has been confirmed by NOE difference spectroscopy. Characteristic differences have been observed in both 1H and 13C NMR spectra of these isomeric Pairs: some of the 1H and 13C chemical shifts, and also the one bond 13C1H couplings of triazole protons, differ consistently in the NMR spectra of the isomers. The coupling constants have been determined using a combination of INEPT and chemical shift selective filtering.
Complete assignment of the 1H and 13C NMR spectra of 8‐hydroxy‐7‐methoxy‐4‐methyl‐1α,4α,4aα,8β,8aα‐tetrahydro‐1,4‐methanonaphthalen‐5(1H)‐one
Authors: Minter David E. , Marchand Alar P. , Lu Shao‐Po 
Published: May 2005

AbstractDiels–Alder cycloaddition of a mixture of 1‐ and 2‐methylcyclopentadienes (1a and 1b, respectively) to 2‐methoxy‐p‐benzoquinone (2) gave a mixture of isomeric endo [4 + 2] cycloadducts (3a–3d). Fractional recrystallization of this product mixture from EtOAc‐hexane gave 6‐methoxy‐1‐methyl‐1α,4α,4aα,8aα‐tetrahydro‐1,4‐methanonaphthalene‐5,8‐dione (3a). Reaction of 3a with NaBH4 in the presence of cerium(III) chloride resulted in the selective reduction of the less hindered CO group in 3a, thereby affording 8‐hydroxy‐7‐methoxy‐4‐methyl‐1α,4α,4aα,8β,8aα‐tetrahydro‐1,4‐methanonaphthalen‐5(1H)‐one (4). The 1H and 13C NMR spectra of 4, a novel tricyclic ketoalcohol, have been completely assigned by using a combination of one‐ and two‐dimensional NMR techniques.
1H and 13C NMR spectra of some 2‐substituted 4,5‐dimethylfurans
Authors: Dandárová Miloslava , Végh Daniel 
Published: May 2005

Abstract1H and 13C NMR spectra of 22 2‐substituted 4,5‐dimethylfurans are reported. The J(C, H) values were used for signal assignments and for the identification of geometrical isomers of some derivatives.
Solid‐state 31P NMR investigations of unsaturated phosphorus–nitrogen–sulfur rings
Authors: Chivers Tristram , Edwards Mark , Fyfe Colin A. , Randall Leslie H. 
Published: May 2005

AbstractSolid‐state CP/MAS 31P NMR spectra were measured for the following unsaturated phosphorus–nitrogen–sulfur ring systems: 1,5‐R4P2N4S2 (R = Me, Et, Ph), 1,5‐Ph4P2N4S2Ph2, Ph2PN4S3NPPh3 and Ph2PN3S2. The isotropic solid‐state shifts correlate well with the corresponding shifts in solution, the largest difference being 9.0 ppm, indicating that there are no phase‐dependent structural features. Analysis of the principal elements of the shielding tensor by the spinning side band method showed that one of these elements is primarily responsible for the anomalously low‐field isotropic chemical shifts of 1,5‐R4P2N4S2, but no correlation was found between this individual tensor component and any of the structural parameters of these folded eight‐membered rings. Two isotropic shifts were observed for the crystallographically inequivalent phosphorus atoms of 1,5‐Et4P2N4S2, but the individual 31P isotropic shifts of 1,5‐Me4P2N4S2 were not resolved.
Simultaneous measurement of one‐bond and long‐range carbon–carbon coupling constants in cembrene
Authors: Ma L. , Bigler P. 
Published: May 2005

AbstractA 1D pulse sequence designed for the selective detection of carbon–carbon connectivities and the measurement of the corresponding coupling constants is presented. The sequence takes advantage of the increased sensitivity and the higher accuracy obtained with multiselective excitation and 1D detection, respectively. The sequence is shown to be a valuable alternative to the popular 2D INADEQUATE experiment in cases where parts, instead of the full, carbon–carbon connectivity matrix are of interest. The sequence is especially useful for the selective measurement of the stereochemically interesting long‐range coupling constants.
Assignment of the 1H and 13C NMR spectra and conformational analysis of the pyrrolizidine alkaloid 13‐O‐acetyldicrotaline
Authors: Rycroft David S. , Stirling Iain R. , Robins David J. 
Published: May 2005

AbstractThe 1H and 13C NMR spectra of the pyrrolizidine alkaloid 13‐O‐acetyldicrotaline were studied at 4.7 T. A full assignment of the 1H and 13C signals was achieved by application of a variety of NMR techniques, including homonuclear 1H NOE difference, 2D δH/δH phase‐sensitive COSY and δC/δH direct and long‐range correlation experiments. The stereochemistry at C‐13 in dicrotaline is confirmed to be S, and the conformation of the elevenmembered macrocycle is compared with that of related pyrrolizidine alkaloids.
Characterization of oligosaccharides from the non‐reducing termini of keratan sulphate chains
Authors: Huckerby Thomas N. , Dickenson John M. , Nieduszynski Ian A. 
Published: May 2005

AbstractKeratan sulphate (KS) chains prepared from both bovine tracheal rings and bovine femoral head cartilage were digested with the enzyme keratanase from Pseudomonas species and non‐reducing terminal oligosaccharides were fractionated and purified using high‐performance ion‐exchange chromatography. Two oligosaccharides were fully characterized using one‐ and two‐dimensional NMR spectroscopic methods. An oligosaccharide derived from bovine tracheal ring KS chains was shown to have the structure NeuAcα2–3Galβ1–4GlcNAc(6‐SO4)β1–3Gal(6‐SO4)β1–4GlcNAc(6‐SO4)β1–3Gal‐ol (1). An oligosaccharide derived from bovine articular cartilage after treatment with a keratanase preparation containing neuraminidase activity was shown to have the structure Galβ1–4GlcNAc(6‐SO4)β1–3Gal(6‐SO4)β1–4GlcNAc(6‐SO4)β1–3Gal‐ol (2). These non‐reducing terminal structures are KS chain caps or terminators which, because of their accessibility, are likely to be involved in interactions with other macromolecules of the extracellular matrix.
NMR spectroscopy of paramagnetic complexes. Part 39—natural abundance 2H NMR of paramagnetic sandwich compounds
Authors: Blümel Janet , Hofmann Peter , Köhler Frank H. 
Published: May 2005

AbstractThe methylated metallocenes (MeCp)2M with M = V, Cr, Mn, Co, Ni (1–5) were investigated by 1H and 2H NMR spectroscopy at natural abundance. The 2H NMR signals are narrower by a factor of up to 30 compared with the corresponding 1H NMR signals, thus establishing an inexpensive method and a general improvement of the NMR spectra of paramagnetic π‐complexes. This has allowed the resolution of the signal splitting of Cp deuterons of 1 and 5 which could not be observed earlier in the 1H NMR spectra. The origin of the small (1 and 5) and large (2–4) signal splittings is discussed and related to an extended Hückel calculation. The relative magnitude of the signal splitting is reproduced, but the signal assignment had to be deduced from 13C NMR results. Primary isotope shifts of up to 4.0 ppm were found for 1, 2, 4 and 5. The much higher values for 3 (up to 16.6 ppm) reflect the combined influence of the intrinsic isotope shift and the isotope effect on the spin crossover.
Substituent effects on deuterium isotope effects on nuclear shielding of intramolecularly hydrogen‐bonded aromatic ketones, aldehydes and esters
Authors: Hansen Poul Erik 
Published: May 2005

AbstractDeuterium isotope effects on 13C nuclear shielding, nΔC(OD), were investigated for a large number of substituted ortho‐substituted aromatic hydroxyacyl compounds of the type salicylaldehyde, 2‐hydroxyacetophenone, etc. The isotope effects were analysed as a function of substitution patterns. 2ΔC‐2(OD) shows a linear dependence on ΔOH, with one slope for 4‐ and 6‐substituted derivatives and another for 5‐substituted derivatives. A similar pattern is also found for the long range isotope effects. In addition, isotope effects also correlate with 13C chemical shifts. Isotope effects in o‐hydroxyacetophenones can be predicted from the δOH and nΔC(OD) values of salicylaldehyde, and vice versa. The isotope effects were analysed in terms of a vibrational term related to the intramolecular hydrogen bond and an electronic term related to the substituent influence on the transmission of the effect along the pathway between the deuterium‐substituted oxygen and the carbon in question. 2ΔC(OD) isotope effects are found to depend on the one‐bond bond order of the CC bond of the unsubstituted hydrocarbons. Long‐range isotope effects are observed to the olefinic carbons of 2‐hydroxychalcone, whereas no effects beyond C‐1′ are seen in o‐hydroxyketones or o‐hydroxybenzophenones. The tautomeric equilibrium of usnic acid is perturbed by the removal of the weak hydrogen bond between 9‐OH and the carbonyl group at C‐1.
Effect of the ortho‐nitro group on the 13C NMR chemical shifts of substituted pyridines
Authors: Rasala Danuta , Gawinecki Ryszard 
Published: May 2005

AbstractThe 13C NMR spectra of 40 vicinally substituted 2‐ and 3‐nitropyridines were recorded. The observed chemical shifts are, in general, non‐additive. These results are discussed in terms of the effects of 2‐, 3‐ and 4‐substitutents on the ring carbons and of the position of the fixed nitro group and the substituent. The chemical shifts of the para carbon, with respect to the substitutent, follow well the dual substituent parameter approach, which shows their electronic origin. However, the substituent chemical shifts of both ipso and ortho positions can be rationalized, in terms of multiple parameter substituent correlation analysis, only on a approximate level.
NMR spectra and stereochemistry of 6‐ and 7‐substituted cyclopenta [d][1,3]dioxanes
Authors: Crabb Trevor A. , Porssa Manuchehr , Patel Asmita V. , Elmore Norman F. 
Published: May 2005

AbstractThe reaction between 6‐ and 7‐ketocyclopenta[d] [1,3]dioxane and methyl‐phenylmagnesium bromide gave in each case only one isomer of the 6‐hydroxy‐6‐methyl‐phenyl‐ and 7‐hydroxy‐7‐methyl‐phenylcyclopenta [d] [1,3]dioxanes. The configurations of these derivatives were determined from a detailed analysis of the 1H NMR spectra. All the compounds were found to adopt the O‐inside cis‐fused conformations.
Assignment of the configuration of a substituent in saturated six‐membered ring compounds using the 13C chemical shifts of a single epimer
Authors: Pandiarajan K. , Manimekalai A. 
Published: May 2005

AbstractThe possibility of assigning the configuration of a substituent in six‐membered ring compounds from the 13C chemical shifts of a single epimer was examined. The chemical shifts of the ring carbons in saturated six‐membered ring compounds were calculated using standard substituent parameters obtained from tert‐butyl systems, and these calculated values were compared with the observed values. It was found that in isomeric 1,3‐ and 1,4‐disubstituted cyclohexanes the configuration could be assigned correctly for each isomer by comparing the observed chemical shifts with the calculated values, an exception being trans‐1,3‐dihydroxycyclohexane. However, in the 1,2‐disubstituted cyclohexanes the configuration could be assigned correctly only by comparing the observed and calculated chemical shifts for the γ‐ or β‐methylene carbons. The configuration cannot be assigned correctly in heterocyclic systems by using the individual chemical shifts as probes. However, when the sum of the chemical shifts of the ring carbons could be calculated for equatorial and axial orientations of the substituent using standard substituent parameters to a reasonable degree of accuracy, the configuration for any epimer could be assigned correctly by comparing the observed and calculated sums.
13C NMR of pyrazoles
Authors: Begtrup Mikael , Boyer Gérard , Cabildo Pilar , Cativiela Carlos , Claramunt Rosa M. , Elguero José , García José Ignacio , Toiron Catherine , Vedsø Per 
Published: May 2005

AbstractThe carbon‐13 chemical shifts and coupling constants of 1168 pyrazoles are reported, some of them in several solvents. These data are briefly discussed on the basis of statistical treatment and qualitative comparisons.
Isogambogic acid and isomorellinol from Garcinia hanburyi
Authors: Lin Lee‐Juian , Lin Long‐Ze , Pezzuto John M. , Cordell Geoffrey A. , Ruangrungsi Nijsiri 
Published: May 2005

AbstractThree xanthone derivatives, gambogic acid, isogambogic acid and isomorellinol, were isolated from the dried latex of Garcinia hanburyi. Two of them, isogambogic acid and isomorellinol, are new. Determinations of the structures and stereochemistry were achieved independently by a series of NMR experiments including COSY, ROESY, HMQC, HMBC and selective INEPT. Isolation of isomorellinol from G. hanburyi provided important chemical evidence to link this species to G. morella. The presence of gambogic acid and isogambogic acid, however, demonstrated the difference between these two species. Cytotoxic evaluation of these isolates revealed that all three were active against KB and drug‐resistant KB‐V1 cell lines.
Theoretical study of the γ‐gauche effect for an n‐paraffin by using an ab initio GIAO–CHF procedure
Authors: Kurosu Hiromichi , Ando Isao , Webb Graham A. 
Published: May 2005

AbstractAb initio 13C nuclear shielding calculations of the γ‐gauche effect for an n‐paraffin using the GIAO–CHF procedure are reported. The geometrical parameters used are optimized for each dihedral angle. The dihedral angle dependences of shielding constant calculations are carried out and the γ‐gauche effect on n‐octane is discussed.
Temperature effects on the 1H1H, 1H19F and 1919F coupling constants of fluorobenzene and 1,2‐difluorobenzene
Authors: Suntioinen Sirpa , Weber Ursula , Laatikainen Reino 
Published: May 2005

AbstractThe 1H NMR spectra of fluorobenzene and 1,2‐difluorobenzene were measured in acetonitrile‐d3 and cyclohexane‐d12 at four temperatures to study the temperature dependence of 1H1H, 1H19F and 19F19F coupling constants. In acetonitrile‐d3 the 5J(F,H) coupling constant of fluorobenzene decreases by 5%, the 5J(H,H) coupling increases by 0.5% and all other couplings decrease by less than 1% when the temperature increases from 283 to 333 K. In cyclohexane‐d12 the change in 5J(F,H) for fluorobenzene is much smaller than in acetonitrile‐d6; the other changes are normally slightly smaller than in acetonitrile‐d5. The changes for 1,2‐difluorobenzene are generally of the same order as those for fluorobenzene.
Structural studies on mesoionic 1,2,3,4‐thiatriazolo‐5‐aminides and 1,2,3,4‐thiatriazolo‐5‐methylides by nitrogen and carbon NMR
Authors: Jażwiński Jaroslaw , Stefaniak Lech 
Published: May 2005

Abstract15N, 14N, 13C and 1H NMR data were used for the structural analysis of seven 1,2,3,4‐thiatriazoles with various exocyclic groups. Measurements at various temperatures were carried out in order to study the behaviour of exocyclic groups. Some 15N‐labelled compounds were prepared to assist in the interpretation of the 15N NMR spectra. The results suggest that the investigated compounds exist in the cyclic structure. Three of the investigated compounds have not been previously synthesized.
Synthesis, EPR, ENDOR and TRIPLE resonance investigations of anthracycline‐related semiquinones
Authors: Stegmann Hartmut B. , Jülich Thomas , Höfler Ulrike , Schuler Paul , Koch Wolfhard , Krohn Karsten , Eickhoff Astrid 
Published: May 2005

AbstractThe synthesis of five substituted anthraquinones related to anthracyclines is described. One‐electron reduction of these compounds yields the corresponding semiquinones, which were characterized by EPR, ENDOR and TRIPLE resonance spectroscopy. The data indicate a rapid conformational interconversion of the cyclohexene moiety (ring A in the anthracyclines). The low‐temperature structures could be assigned to half‐chair conformers whose splitting constants and torsion angles were obtained by simple calculations. Introduction of substituents in the 4‐position, disturbing the symmetry of the anthraquinone, results in remarkable changes in the spin density distribution, in contrast to published results. A reinterpretation and assignment of known anthraquinone radicals is presented.
Motional heterogeneity and polymorphism of bisphenol‐A diacetate
Authors: Casarini Daniele , Harris Robin K. , Kenwright Alan M. 
Published: May 2005

AbstractTwo polymorphs of bisphenol‐A diacetate [2,2‐bis(p‐acetoxyphenyl)propane] were characterized by solid‐state 13C cross‐polarization magic‐angle spinning NMR, X‐ray powder diffraction and differential scanning calorimetic measurements. The structure of one polymorph was determined by single‐crystal x‐ray diffraction methods, and shown to have two molecules in the asymmetric unit. The two polymorphs show markedly different molecular mobilities, as reflected in variable‐temperature solid‐state NMR measurements, with one polymorph exhibiting motional heterogeneity in the flipping of the phenylene rings.
Complete 1H and 13C NMR spectral assignment of pentacyclo [6.4.0.02,6.05,9.04,12]dodecane derivatives and structure elucidation of pentacyclo [6.4.0.02,6.03,11.05,9]dodecane
Authors: Martins F. J. C. , Coetzee G. H. , Fourie L. , Venter H. J. , Viljoen A. M. , Wessels P. L. 
Published: May 2005

AbstractTreatment of pentacyclo[6.4.0.02,6.05,9.04,12]dodecane‐2‐ol with concentrated sulphuric acid produced the rearranged hydrocarbon pentacyclo[6.4.0.02,6.03,11.05,9]dodecane as the main product. High‐field 1H and 13C NMR techniques were used in the structure elucidation and assignment of the different NMR resonances of these two and related compounds.
Experimental appraisal of solvent effects on internal rotation barriers and stabilization energies of disubstituted methyl radicals
Authors: Mordi Raphael C. , Walton John C. 
Published: May 2005

AbstractThe EPR spectra of aminopropynyl and aminocyanomethyl radicals were recorded in a variety of solvents with different dielectric constants. For the former radical the spectra showed exchange broadening due to restricted rotation about the H2NC˙ bond. Arrhenius parameters for the bond rotation, i.e. for the interconversion of the two rotamers, were obtained by computer simulation of the exchange‐broadened spectra. The rotational barrier height was found to change only marginally in solvents with dielectric constants ranging from 2.1 to 37.5. For both radicals the temperature dependences of the α(NH2) values also indicated little change in their H2NC˙ rotation barriers in solvents of differing polarity. Because rotation barriers are directly related to the stabilization energies (SE) of the radicals, it was concluded that solvent polarity has little effect on the SE of a capto‐datively substituted radical.
Synthesis and configurational assignment of epimeric 22‐hydroxy‐, 23, 24‐acetylenic, olefinic or epoxy steroids using carbon‐13 NMR Spectroscopy
Authors: Hazra Braja G. , Pore Vandana S. , Joshi Padmakar L. , Padalkar Sharmila N. , Deshpande Shubhada A , Rajamohanan Pattuparambil R. 
Published: May 2005

AbstractStereoisomers of steroidal 22‐hydroxy‐23‐acetylenic, 23‐olefinic and 23, 24‐isomeric epoxides were synthesized from C‐22 aldehydes and their 13C NMR spectra were analysed. A correlation regarding the combined effect of the 22‐hydroxy and 23, 24‐substituents on the stereochemistry of the attached groups at C‐22, ‐23 and ‐24 is derived.
13C nuclear magnetic resonance data for methyl 3,4‐disubstituted benzoates
Authors: Varma R. S. , Shukla Amita 
Published: May 2005

AbstractThe 13C NMR spectral assignments and 1J(C,H) spin–spin coupling constants for methyl 4‐anilino‐3‐nitrobenzoate, methyl 4‐p‐chloroanilino‐3‐nitrobenzoate, methyl 4‐p‐toluidino‐3‐nitrobenzoate, methyl 4‐p‐ anisidino‐3‐nitrobenzoate, methyl 4‐hydroxy‐ 3‐methoxybenzoate and methyl 3,4‐dimethoxybenzoate are reported.
Determination of the structure of alkoxysilane polymers in solution by natural abundance two dimensional 29Si‐29Si INEPT DQF COSY NMR
Authors: Lux Philippe , Brunet Francine , Desvaux Hervé , Virlet Joseph 
Published: May 2005

AbstractIn order to determine the nature and the structure of polymers formed by condensation of alkoxysilanes, a two‐dimensional INEPT double quantum filtered COSY NMR experiment was developed to observe 29Si29Si correlations at 29Si natural abundance. This experiment was tested on a mixture containing a trimer, [(CH3)3SiO]2Si(CH3)2, and a tetramer, [(CH3)3SiOSi(CH3)2]2O. This 2D INEPT DQF COSY experiment was then used to investigate the nature and the structure of the polymers which are formed in the early stages of the condensation reaction of diethoxydimethylsilane (DEDMS) in a DEDMS–water mixture containing a small amount of water at low pH (1.0).
Complete 1H and 13C resonance assignments of stereoisomeric 3α,6,7,12α‐tetrahydroxycholanoic acids by two‐dimensional shift‐correlated NMR
Authors: Iida Takashi , Chang Frederic C. , Mushiake Kumiko , Goto Junichi , Nambara Toshio 
Published: May 2005

AbstractComplete 1H and 13C NMR resonance assignments were carried out for six stereoisomeric 6,7‐glycol derivatives of deoxycholic acid as their methyl esters (four being in the 5β‐series and two in the 5α‐series). In addition to conventional 1D NMR methods, 2D shift‐correlated NMR techniques (1H1H COSY, 1H1H NOESY and 1H13C HETCOR) were used for the signal assignments. Several 1H and 13C resonances have been reassigned from those previously reported. Substituent effects of the 6,7‐glycol moieties on the proton and carbon resonances were clarified and used in the structural elucidation of these compounds.
Chemical shift anisotropy of the anomeric protons in α‐ and β‐D‐glucose
Authors: Poppe Leszek , van Halbeek Herman 
Published: May 2005

AbstractValues for the chemical shift anisotropies of the α‐ and β‐anomeric protons in [1‐13C]‐D‐glucose were measured by ortho‐ROESY and SLOESY experiments using non‐selective and selective 1H spin‐locking by DANTE pulse trains, respectively. The experiments were performed under the condition ωHτo ≈ 1, in order to enhance cross‐correlated cross‐relaxation due to interference between 1H chemical shift anisotropy and 1H‐13C dipolar interactions. Assuming axial symmetry for the 1H chemical shift tensor, chemical shift anisotropy values of ΔσH‐1(α) ≈ −6.1 ppm and ΔσH‐1(β) ≈ −2.4 ppm were obtained.
Use of indirect 199Hg NMR detection for aromatic mercury compounds of biological interest
Authors: Neirinck Vincent , Robert Danielle , Nardin Robert 
Published: May 2005

AbstractWhen vanillin (4‐hydroxy‐3‐methoxbenzaldehyde) and syringaldehyde (4‐hydroxy‐3,5‐dimethoxybenzaldehyde) react with Hg(OAc)2, selective monomercuration occurs on the aromatic ring. The three 3J, 4J and 5(199Hg,1H) coupling constants of phenylmercury acetate were used as 1/2J delays in the 1D inverse 1H 199Hg, sequence applied to 5‐acetoxymercuriovanillin and 2‐acetoxymercuriosyringaldehyde, the edited proton spectra obtained for each nJ(199Hg, 1H) coupling gave the value of n and the J(199Hg, 1H) coupling constants, and therefore yielded information about the position of the mercury substitution on the aromatic ring. A 2D 199Hg,1H shift correlation with 1H detection was applied in the case of phenylmercury acetate, using the mean value of the three J couplings; the 3J and 4J couplings were clearly resolved. As vanillin and syringaldehyde are representative monomer models of lignin, the indirect detection of 199Hg is then an appropriate method to determine the aromatic substitution pattern, which is a key point in lignin structural elucidation.
1H, 13C, 15N, 113Cd, 2D 15N1H and solid‐state 13C CP/MAS NMR of Hg and Cd complexes of 4(1H)‐quinazolinone‐2,3‐dihydro‐2‐thioxo
Authors: Martínez‐Martínez Francisco Javier , Ariza‐Castolo Armando , Ramos‐Nava Victor , Barba‐Behrens Norah , Contreras Rosalinda 
Published: May 2005

AbstractThe Cd(II) and Hg(II) complexes of 4(1H)‐quinazolinone‐2,3‐dihydro‐2‐thioxo (1) and the free ligand were studied by 1D and 2D multinuclear magnetic resonance in solution and 13C cross polarization magic angle spinning NMR in the solid state. Compound 1 adopts only one of five possible tautomeric structures in solution, namely the thiouracyl‐like structure. It was found that the metal atom is linked to two molecules of deprotonated 1 by N‐1 and coordinated by the sulphur atom. The compounds retain the same structure in the solid state and in dimethyl sulphoxide solution.