bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Probable Phase Composition of the Mineral in Sound Enamel and Dentine
Authors: Driessens F. C. M. , Verbeeck R. M. H. 
Published: September 2010

AbstractA reevaluation of the chemical, physical and physicochemical properties of the mineral in tooth enamel and dentine shows that the current models can not adequately account for the observed characteristics. On the basis of thermodynamical and solid state chemical principles an alternative model for the mineral in tooth enamel and dentine is proposed. According to the model the tooth enamel mineral consists of a magnesium whitlockite, a sodium‐ and carbonate containing apatite and a slightly carbonated hydroxyapatite approximately in the ratio 1: 1: 3. The latter phase also contains the chloride and fluoride ions of the mineral. The consistency of this three‐phase model is discussed. Dentine mineral appears to have qualitatively the same phase composition as bone mineral, although the relative amounts of the three constituting mineral phases differ considerably.
Structures et Étude Comparative des Géométries de Six Dérivés du Cyano‐1 Diphényl‐1, 2 Cyclopropane
Authors: Tinant B. , De Block I. , Declercq J. P. , Germain G. , van Meerssche M. , Leroy G. , Weiler J. 
Published: September 2010

AbstractThe structure of six l‐aryl‐l‐cyanocyclopropane derivatives were solved by direct methods (MULTAN) from diffractometer data. (I): r‐I‐cyano‐c‐2‐p‐dimethylamlnophenyl‐1‐phenylcyclopropane C18 H18 N2 is orthorhombic, P21 21 21 with a = 20.537(6), b = 9.010(2), c = 7.956(3)Å, z = 4. (II): r‐l‐cyano‐c‐ ‐2‐ ‐ v‐dimethylaminophenyl‐1‐p‐nitrophenylcyclopropane C 18H17N3O2 is triclinic, P1 with a = 14.547(5), b = 8.521(2), c = 6.402(2)Å, α = 93.59(2), β = 96.37(3), γ = 88.30(2)°, = 2. (III): r‐l‐cyano‐c‐2‐p‐dimethylaminophenyl‐t‐3‐methyl‐l‐p‐nitrophenylcyclopropane C 19H19N3O2 is triclinic, P1 with a = 9.873(3), b = 10.134(3), c = 9.335(3)°, α = 73.10(2), β = 84.07(2), γ = 98.68(2)°, Z = 2. (IV): r‐l‐cyano‐c‐2‐ (p‐dimethylamino‐α‐methylbenzyl) ‐t‐3‐methyl‐1‐p‐nitrophenylcyclopropane C21H23 N3 O2 is monoclinic, C2/c with a = 23.837(5), b = 12.389 (3), c = 14.374(5)Å, β = 113.82°, Z = 8. (V): r‐l‐cyano‐l‐p‐nitrophenyl‐c‐2‐ phenylcyclopropane C16H12 N2O2 is monoclinic, P21/c with a = 7.152(1), b = 17.814(6), c = 10.717(4)Å, β = 96.40(3)°, Z = 4. (VI): r‐l‐cyano‐t‐3‐methyl‐l‐p‐nitrophenyl‐c‐2‐phenylcyclopropanc C17H14N2O2 is monoclinic, P21/a with a = 7.783(2), b = 24.492(4), c = 8.501(1)Å, β = 115.59(1)°, Z = 4. The substituent induced bond length asymmetries observed in these cyclopropane derivatives are in good agreement with analysis of Allen (1980). There is no evidence of conjugation transmission from an electrodonor substituent to an acceptor one through the small ring.
Carbon‐13 Chemical Shifts of Three Oxo‐, Six Monohydroxy‐, and Six Dihydroxycyclohexyl Derivatives of Procyclidine
Authors: Paeme G. , Grimée R. , Vercruysse A. 
Published: September 2010

AbstractIn order to elucidate the metabolic pattern of procyclidine in the rat, a variety of OXO‐, monohydroxy‐, and dihydroxycyclohexyl derivatives of this drug were synthetized. All of them have been identified by 13C‐NMR spectroscopy.
Spectres RMN ‐1H et ‐13C de Quelques Quinoléines et Quinaldines Mono et Disulfonees
Authors: Gelbcke M. , Masiala‐Tsobo C. , Dumont L. , Parmentier F. , Grimée R. 
Published: September 2010

AbstractProton and carbon‐13 chemical shifts and coupling constants are reported for one disulfonated and four monosulfonated quinolines, two monosulfonated and two disulfonated quinaldines. Substituent effects for the alpha, ortho, meta, para and peri positions are discussed.
Cavernosine, a Novel Ichthyotoxic Terpenoid Lactone from the Sponge Fasciospongia Cavernosa
Authors: Braekman J. C. , Daloze D. , Bertau R. , Macedo De Abreu P. 
Published: September 2010

AbstractCavernosine, a novel ichthyotoxic terpenoid lactone has been isolated from the sponge Fasciospongia cavernosa. Its structure has been determined by spectral analysis, chemical degradation and correlation with β‐ionone.
Calculation of Diagonal Force Constants by the Stepwise Coupling Method: M.P.E.M. (Matrix Polynomial Expansion Method)
Authors: Alix Alain J. P. , van Der Veken Benjamin , Isotani Sadao , Manfait Michel 
Published: September 2010

AbstractThe calculation of an approximate Simple symmetry Valence Force Field including determination of diagonal symmetry valence force constants is achieved by using an iterative process derived from the Stepwise Coupling Method (SCM) in the form of the Matrix Polynomial Expansion Method (M.P.E.M.) of Alix. The discussion on the method itself and the comparison with similar methods such as the Eigen‐Vector Method (EVM) is given in detail. Numerical examples are given to illustrate the effectiveness of the method.
X‐ray Diffraction Study of 2,4a,4b,5,6,7,8,9,9a,10‐Decahydro‐7, 10‐Dihydroxy‐2, 4a‐epoxy‐8‐methylene‐7, 9a‐Methanobenz |a| Azu‐lene‐1‐Carboxylic Acid Ethyl Ester (2α, 4aα, 4bβ, 7β, 9aα, 10β)
Authors: van Meerssche M. , Declercq J. P. , Grootaert W. M. , De Clercq P. J. 
Published: September 2010

AbstractC19H22O5, monoclinic, P21/a, a = 16.298(6), b = 8.359(2), c = 13.183(3) Å, β = 112.32(2)°; V = 1661.4(8)Å3, Dx = 1.32 g cm−3 for Z = 4.The structure has been solved by direct methods (MULTAN 80) and refined to a final R value of 0.051 for 2017 observed reflections. The stereochemistry of the title compound is as depicted for one enantiomer in 1; the configuration of the asymmetric carbons can be specified as C(3)R, C(6)R, C(8)S, C(9)R, C(10)R, and C(13)S. The five‐membered B ring is a half‐chair with pseudodiad axis through C(10). The six‐membered ring of the bicyclo|3.2.1| octane substructure adopts a distorted chair conformation.
The Determination of the Rotational Strength of the Gauche C‐C‐C‐SH Unit, Based on the 1H NMR Conformational Analysis of 2‐Butanethiol
Authors: Tavernier D. , Hosten N. , Anteunis M. J. O. , Spiessens L. I. 
Published: September 2010

Abstract2‐Butanethiol was analysed by 1H NMR spectroscopy and its conformational composition in CDCl3 was determined: a: 0.53; g+: 0.35; g−: 0.12 (see Table I). The rotational strength of the gauche C‐C‐C‐SH fragment was thus estimated to be 126°. Analogously, the optical activity of 2‐butanol was related to its conformational composition, as determined by 1H NMR spectroscopy (T = 298 K): a: 0.45; g+: 0.32; g−: 0.23.
Ring Current and Aromaticity in Annulenes
Authors: Verbruggen A. 
Published: September 2010

AbstractIF T0 ‐ Ti is the chemical shift difference of outer and inner protons in annulenes, S is their ring area and REPE their resonance energy per π‐electron, the linear correlation (T0 ‐Ti)/S=k.REPE is confirmed, both in theory and practice.
Prominent Aspects of Electroorganic Synthesis in β‐Lactam Chemistry
Authors: Torii Sigeru , Tanaka Hideo , Sasaoka Michio , Saitoh Norio , Siroi Takashi , Nokami Junzo 
Published: September 2010

AbstractThe potentiality of electrolysis procedures in the penicillin‐cephalosporin conversion as well as in the direct transform of penicillins into oxazolineazetidinones as an intermediate for the preparation of the sulfur‐free analogues of cephalosporins are discussed. Especially, a chemoselective electrolytic chlorination of methyl group of 3‐methyl‐3‐butenoate moiety of thiazolineazetidinone derived from penicillins, a direct synthesis of 3′‐thiosubstituted cephalosporins from the thiazoline‐azetidinones, an improved synthesis of exomethylenecephams, an efficient route to 3‐chloromethyl‐Δ3‐cephems, electrochemical S‐S bond fission of 4‐(2‐benzothiazolyldithio) azetidinones, a direct transformation of penicillins into oxazoline‐azetidinones by chloride salt‐promoted electrolysis, and a versatile intermediate for new β‐lactam antibiotics are presented.
Spectres RMN‐1 H et‐13 C Des Acides Mercapto‐2 Pyridinecarboxylique‐3, Mercapto‐3 Pyridinecarboxylique‐2 et de Leurs Derives Methyles Correspondants
Authors: Gelbcke M. , Grimée R. , Lejeune R. , Thunus L. , Dejardin J. V. 
Published: September 2010

AbstractProton and carbon‐13 chemical shifts and coupling constants of 2‐mercapto‐3‐pyridinecarboxylic acid, 3‐mercapto‐2‐pyridinecarboxylic acid and their seven respective methylated derivatives are reported. Substituent effects are discussed.
Rates of alkaline racemisation of carbobenzoxy protected pentachlorophenyl esters of γ‐Thiapipecolic acid and γ‐thiaproline
Authors: Wante Dirk P. M. , Borremans Frans A. M. , Anteunis Marc J. O. 
Published: September 2010

AbstractRacemisation rates of Z‐blocked pentachlorophenylesters of the imino acids proline, pipecolic acid and their γ‐thia congeners are measured in triethylamine chloroform or tetrahydrofuran as the base/solvent system. The data is discussed in relation to the corresponding (but different) racemisation behaviour of the same residues in cyclic dipeptides.
Ouverture Par Les Orcanolithiens D'Isothiazoles et Isoselenazoles Heterocondenses
Authors: Onvamboko N. V. , Weber R. , Fauconnier A. , Renson A. 
Published: September 2010

AbstractThe ring‐opening of bi‐and tricyclic systems bearing an isothiazole or isoselenazole ring fused to a thiophene or a selenophene ring was studied by their reaction with methyl lithium.The ring‐opening of the nitrogen ring occurs preferentially, except when, in a tricyclic system, the selenophene ring is central and fused to an isothiazole ring. In this case, the selenium heterocycle is opened before the nitrogen ring.
Structure and Stability Constants of Some Transition and Rare Earth Metal Complexes with Eiknogen
Authors: Abou‐Elwafa S. M. , Elzawawi F. M. , Issa R. M. 
Published: September 2010

AbstractThe complex formation of divalent ions, Mn, Co, Ni, Cu, Zn, Cd; the trivalent ions, Fe, Y, La‐Lu and U ion with eiknogen have been investigated spectrophotometrically and potentiometrically in 75% (v/v) dioxane. The metals form 1:1 and 1:2 complexes. Stability constants log K1 and log K2 are determined. The complexes formed have been characterised by elemental analyses and infra‐red spectral data from which bonding mode have been suggested.Phenolic ligands are frequently used as complexing agents for the detection and determination of metal ions in solution1,2. Eiknogen (1‐amino‐2‐naphthol‐4‐sulphonic acid) is usually used for the determination of low silicate and arsenate ion concentrations3, however, few studies on metal chelates with eiknogen are also reported. It was considered, of interest, to study the complex formation of some transition metals with eiknogen and determination of their structures and stability constants.
The Analysis of the Homogeneous Saponification Reaction Applied to High Pressure Ethylene Vinylacetate Copolymers Part II: Influence of the Reaction Parameters on the Formation of EVA1/EVA1VA Polymers
Authors: Koopmans R. J. , Van Linden R. Der , Vansant E. F. 
Published: September 2010

AbstractThe influence of 4 reaction parameters on the homogeneous saponification method is examined. Firstly, the use of xylene, cyclohexane and tetrachloromethane instead of toluene indicates some experimental complications. It could however be concluded that a changing solubility parameter had a minor effect on the VA conversion rate. Secondly, reactions in an ethanol or a 2‐propanol medium are faster than when a methanol medium is used. Thirdly, it is not possible to control the % wt conversion VA only by a suitable amount of potassiumhydroxide. A larger than expected % wt conversion VA is observed, due to a base catalyzed transesterification sidereaction. Fourthly, a methanol concentration change influences the contribution of the sidereaction. Furthermore, the methanol and potassiumhydroxide concentration influence, on the VA conversion rate is not independent of each other.
Studies on the Dissociation Constants and Ion‐Solvation in Aqueous Ethanol, Non‐Aqueous Solvents and their Aqueous Mixtures of Some Benzocyclobuten‐1 (2H) Ones
Authors: Wasif Saad , Nashid Barsoum , Iskander George M. 
Published: September 2010

AbstractThe pK'a values of five 4‐hydroxybenzocyclobuten‐1 (2H)ones (I) in aqueous ethanol, dioxane, acetonitrile and dimethylformamide have been determined. The Hammett parameter ρ varies for each phenolic ketone with the aqueous solvent composition, which reflects possible sensitivity to solvent polarity. The molar free energies of transfer of (I) from water to 20‐60 wt % of organic solvent‐water mixtures haven evaluated. The results so obtained, are explained by a structural theory of ion salvation.
Étude Structurale Des Stilbènes I. Structures Par Diffraction de Rayons X de Trois α‐Cyanostilbènes
Authors: Tinant B. , Touillaux R. , Declercq J. P. , van Meerssche M. , Leroy G. , Weiler J. 
Published: September 2010

AbstractThe X‐Ray crystal and molecular structures of three α‐cyanostilbene derivatives were solved by direct methods from diffractometer data. (I) Trans‐4′‐dimethylamino‐4‐nitro‐α‐cyano‐β‐ethylstilbene, C19 H19 N3 C2, is triclinic, P 1, with a=10.725(3), b=10.860(3), c=8.451(2)Å, α=113.24(3), β=79.56(2), γ=111.13(3)°, V=842.8 Å3, Z=2. (II) Cis‐4′‐nitro‐α‐cyanostilbene, C15 H10 N2 O2, is monoclinic, P21, with a=5.655(2), b=17.004(5), c=6.521(2) Å, β=95.50(3)°, V=624.1 Å3, Z=2. (III) Cis‐4‐nitro‐α‐cyano‐β‐methylstilbene, C16 H12 N2 O2, is monoclinic, C2/c, with a=23.104(3), b=10.319(2), c=13.310(4)Å, β=118.08(2)°, V=2799.8 Å3, Z=8.In the three compounds, the phenyl groups are twisted out of the ethylenic bond plane in order to avoid steric hindrance. The C(phenyl)‐CC bond angles are significantly greater than 120° except around C(β) in I and III.
X‐Ray diffraction study of 5‐hydroxy‐6‐methyl‐14‐oxatetracyclo|7.4.11,11.O2,6|tetradecan‐8‐one (lα, 2α, 5β, 6β, 9β, 11α)
Authors: van Meerssche M. , Declercq J. P. , van Royen L. A. , De Clercq P. J. 
Published: September 2010

AbstractC14 H20 O3, monoclinic P21/n, a=14.479(5), b=11.693(5), c=7.139(2)Å, β=98.70(3)°; V=1194.7(7)Å3, Dx=1.31 g cm−3 for Z=4. The structure has been solved by direct methods (MULTAN 80) and refined to a final R value of 0.046 for 1402 observed reflections. The stereochemistry of the title compound is as depicted for one enantiomer in 1; the configuration of the asymmetric carbons corresponds to C(5)S, C(8)S, C(9)S, C(13)S, C(14)R and C(17)S (numbering according to steroid convention). The five‐membered D‐ring is a quasi‐envelope with pucker at C(13). The six‐membered C‐ring adopts a distorted boat conformation.
Activation Collisionnelle D'Ions Fragments Générés en Région Libre de Champ D'Un Spectromètre de Masse a Trois Secteurs
Authors: Maquestiau A. , Flammang R. , Meyrant P. 
Published: September 2010

AbstractThe structure of some fragment ions formed in the source and in the first field‐free region (FFR) of a triple sector mass spectrometer has been investigated by the collisional activation technique. It is shown that the elucidation of fragmentation pathways by metastable peak analysis may lead to erroneous conclusions. Indeed, high energy (source) fragmentation and the corresponding low energy (FFR) processes produce frequently isobaric or even isomeric ions.
Acétonylation Radicalaire de la Norbornanone‐2 Par Réaction Avec le Percarbonate de O,O‐t‐Butyle et O‐Isopropenyle
Authors: Villenave J‐J. , Jaouhari R. , Baratchart M. , Filliatre C. 
Published: September 2010

AbstractThe free radical decomposition of O,O‐t‐butyl and O‐isopropenyl peroxycarbonate in 2‐norbornanone leads to isomeric derivatives of the solvent. The products are identified using 13C NMR spectroscopy. The composition of the reaction mixture depends on the concentration of the peroxycarbonate solutions. At lowest concentrations, intermolecular transfer reactions enhance markedly the relative amounts of the 3‐acetonylated isomer.
Synthesis of a Series of 12‐Oxo‐5α‐Steroids with Variable 17β‐Side Chain
Authors: Biesemans M. , van de Woude G. , van Hove L. 
Published: September 2010

Abstract5α‐Androstan‐12‐one and its homologues up to 5α‐cholan‐12‐one were synthesized, partly by breaking down the 17β‐side chain of 5α‐pregnan‐12,20‐dione 12‐ethylene acetal 7 and partly by means of Wittig condensation reactions. They were all characterized by their spectral properties.
Synthesis of NAD+ Analogs. Part II. Synthesis and Anomeric Separation of 3‐Benzoylpyridine Nucleotide
Authors: Winné C. H. R. , Dommisse R. A. , Lepoivre A. J. , Alderweireldt F. C. 
Published: September 2010

AbstractThe title compound is synthesized from the corresponding 2′,3′‐O‐isopropylidene nucleoside with POCl3 in trimethylphosphate. The anomers are separated by preparative HPLC.
1H And 1 3C NMR of some mercaptopyridine and pyridinethione carboxylic acids
Authors: Schanck A. , Dereppe J. M. , van Meerssche M. 
Published: September 2010

AbstractProton and carbon‐13 NMR data are presented for positional isomers of mercapto‐pyridine carboxylic acids.A tautomerism effect is observed for 2‐and 4‐mercapto‐pyridine derivatives.
Spectres RMN‐13C de β‐Aminothiols Disulfures et Thiazolidines Derivés de la Thioephedrine
Authors: Kone B. , Gelbcke M. 
Published: September 2010

AbstractThe carbon‐13 NMR spectra of β‐aminothiols and disulfides related to nor‐and pseudonorthiophedrine (N‐CH3; N‐C2H5; N‐iC3H7 and N‐tC4H9) and the series of the corresponding thiazolidine from paraformaldehyde were obtained. Their study allowed the differentiation of the diastereomers in these three series.
Organometallics, part VII. The synthesis of α,α‐disubstituted methyl ethers by reaction of ethyldiphenylorthoformate with organomagnesium compounds
Authors: Poncini L. 
Published: September 2010

AbstractThe reaction conditions are investigated for the production of pure α,α‐disubstituted methyl ethers. Crotyl‐and ethyl‐magnesium bromides on reaction with ethyldiphenylorthoformate in ether, under reflux conditions, yielded mixtures of mono‐and disubstituted ethers; the former with total allylic transposition. Crotyl Grignard, at room temperature, gave only the monosubstituted mixed acetal. Acetylenic organomagnesiums produced high yields of pure α,α‐disubstituted methyl ethers when the solvent was dichloromethane. Methyl vinyl and isopropenyl vinyl organomagnesiums in THF gave only disubstituted ethers. The products obtained are rationalized in terms of a mechanism incorporating a two‐fold nucleophilic attack on the ethoxyphenoxycarbonium ion formed from the orthoformate by the organometallic anion, displacing two phenoxy groups to yield the α,α‐disubstituted methyl ethers.
The catalytic decomposition of formic acid into carbon monoxide
Authors: Malinowski Marek , Malinowska Krystyna , Zatorski Leon Wiesław 
Published: September 2010

AbstractDecomposition of formic acid has been studied at 250°‐400°C on some heterogeneous catalysts. Alumina, silica, natural (clinoptilolite) and synthetic (3A, ZSM‐5) zeolites were used as catalysts. H‐ZSM‐5 mixed with γ‐alumina has been found to be the very good catalyst to prepare pure carbon monoxide in a laboratory practice.
The unusual rearrangement of N‐nitroso‐N,O‐dibenzylhydroxylamines with acetic anhydride
Authors: Kano Kunio , Anselme Jean‐Pierre 
Published: September 2010

AbstractTreatment of N‐nitroso‐N,O‐dibenzylhydroxylamine (2a) with acetic anhydride in benzene at reflux results in a remarkable rearrangement to 2‐benzoyl‐1‐acetylbenzylhydrazine and it was established that it is the N‐benzyl substituent of 2a that is transformed into the benzoyl group of the rearranged product (3a).
The crystal structure of racemic sodium‐hydrogen‐1‐malate
Authors: Doesburg M. M. , Lenstra A. T. H. 
Published: September 2010

AbstractNa+C4H5O5− crystallizes in the monoclinic space group Pa with Z=4. The unit cell is given by a=10.074(4)Å, b=6.032(2)Å, c=10.338(4)Å and β=120.11(2)°. The OOC‐CH2‐CHOH‐COO chain has the gauche conformation in contrast to the trans conformation observed in the ammonium‐and potassium‐(dl)‐hydrogen‐malates.
A New electrochemical access to unsymmetrical γdiketones via the corresponding γbisdioxolanes. Application to the synthesis of dihydrojasmone
Authors: Bacquet‐Einhorn Cathy , Soulier Jean‐Louis , Lelandais Daniel 
Published: September 2010

AbstractSummary: A series of unsymmetrical γ bisdioxolanes has been prepared by a mixed coupling of the Kolbe's radicals obtained by anodic oxidation of mixtures of two dioxolanes of γ ketoacids.
The Conformation and Charge Distribution in the Hydrogen Bonded Chelate Ring of Mannich Bases
Authors: Koll A. 
Published: September 2010

AbstractThe dipole moment of 17 Mannich bases has been measured for a broad range of the intramolecular hydrogen bond strength. The increase of the dipole moment caused by the hydrogen bond formation has been calculated and is discussed in terms of the proton transfer equilibrium.The conformation of the chelate ring was analyzed by means of the atom‐atom and Lippincott‐Schroeder potentials. The calculations predict a nonplanar structure for both the molecular hydrogen bonded form and the zwitterionic proton transfer form. The correlation between the chelate ring structure and the hydrogen bond strength is discussed.
Temperature Dependence of the Dipole Moment of Mannich Bases with An Intramolecular Hydrogen Bond
Authors: Rospenk M. , Koll A. 
Published: September 2010

AbstractThe dipole moments of Mannich bases with an intramolecular hydrogen bond have been measured as function of temperature. For two compounds where proton transfer is apparent in benzene from UV‐VIS spectra, a distinct decrease of dipole moment with increasing temperature has been observed. The dipole moments and their temperature dependence have been analyzed in terms of a tautomeric equilibrium related to the proton transfer within the bridge. It is shown that the quantitative description of the proton transfer process obtained by UV‐spectroscopy is completely valid in the interpretation of the dielectric behavior.
Polarographic Behaviour of Some Arylidene Salicylichydrazides in Solutions of Varying PH at the Dropping Mercury Electrode
Authors: Temerk Y. M. , Kamal M. M. , Ahmed Z. A. 
Published: September 2010

AbstractThe polarographic reduction of some arylidene salicylichydrazides at a dropping mercury electrode was studied in universal buffer solutions containing 40 % ethanol. The mechanism of the electrode processes corresponding to the observed cathodic wave is reported. The effect of substituent group on the half‐wave potential has also been discussed. The values of the kinetic parameters for the electrode reaction at different pH values are computed using the Koutecky and Delahay equations.
Études Structurales en Relation Avec le Concept de Substitution “Capto‐Dative” II. Analyse des déformations moléculaires dans cinq déhydrodimères de formule générale: RCH2 (CN) (SR') C‐C (CN) (SR') CH2R(1, 2)
Authors: Parfonry A. , Tinant B. , Declercq J. P. , van Meerssche M. 
Published: September 2010

AbstractThe crystal structures of five 1,4‐butanedinitrile derivatives have been determined using X‐Ray diffractometry in order to study the effects of captodative substitution on molecular geometry. (I) meso 2,3‐diacetonyl‐2,3‐bis (tert‐butylthio)‐1,4‐butanedinitrile, C18H28N2O2S2, is monoclinic, P21/c with a = 9.694(6), b = 10.208(4), c = 10.404(4) Å, β = 97.46(4) º, V = 1020.8(8)Å3, Z = 2. (II) meso 2,3‐bis[(acetylthio)methyl]‐2,3‐bis(tert‐butylthio)‐1,4‐butanedinitrile, C18H28N2O2S4, is triclinic, PI, with a = 12.867(4), b = 11.175(3), c = 10.430(2)Å, α = 90.43(2), β = 54.82(2), γ = 103.61(2) º, V = 1175.8(6)Å3, Z = 2. (III) meso 2,3‐bis(tert‐butylthio)‐2,3‐bis(butyrylmethyl)‐1,4‐butanedinitrile, C22H36N2O2S2 is monoclinic, C2/c, with a = 22.562(6), b = 10.932(4), c = 10.157(4)Å, β = 90.35(4) º, V = 2505.2(8)Å3, Z = 4. (IV) meso 2,3‐bis (tert‐butylthio)‐2,3‐diethyl‐l,4‐butanedinitrile, C16H28N2S2, is monoclinic, P21/n, with a = 10.004(2), b = 13.794(2), c = 6.633(1)Å, β = 95.61(2) º, V= 910.9(3)Å3 Z = 2. (V) dl 2,3‐diacetonyl‐2,3‐bis(methylthio)‐1,4‐butanedinitrile, C12H16N2O2S2, is triclinic, P1, with a = 9.347(3), b = 9.646(1), c = 8.318(2)Å, α = 99.70(2), β = 104.65(2), γ = 99.23(2) º, V = 698.8(3)Å3, Z = 2.The central carbon carbon bond lengths are very long in the five molecules. Mean C‐C distance is 1.593(2)Å. Bond angles around central carbon atom take values between 105 and 115°.