Umsetzung von Metall- und Metalloidverbindungen mit mehrfunktionellen Molekülen, 31. Mitteilung

The reaction of galliumtrichloride and galliumtribomide resp. with 2,6-dimethyl- and 2,4,6-trimethyl-N-trimethylsilyl-trifluoroacetanilide leads to the trifluoracetanilidodihalogenogallanes1–3. The 2,6,9-trioxa-4,8-diaza-1,5-digalla-bicyclo-[3.3.1]-nonadiene derivatives1 a–3 a are formed probably as by products.N-Trimethylsilyltrifluoroacetamide reacts with galliumtrichloride to yield the trifluoroacetamido-dichlorogallane4.N-Trimethylsilyl-N,N,N-triorganyl-thioureas react with galliumtrichloride under elimination of chlorotrimethylsilane to give the thio-ureido-gallanes5 and6. IfN,N-diorganylureas andN,N-diorganyl-thio-ureas resp. are reacted with galliumtrichloride and methyl-gallium-dichloride resp., the thio-ureido- and ureido-gallanes7–9 are obtained by elimination of hydrogenchloride. The compounds are characterized by analysis and spectral data (NMR:¹H,¹⁹F; MS; IR). The substances are monomeric in the gas phase, obviously due to internal coordination.

30. Mitt.:W. Maringgele undA. Meller, J. Organomet. Chem., im Druck.     

Volumetric and viscometric study of aqueous binary mixtures of some glycol ethers at T = (275.15 and 283.15) K

The experimental data for the density (ρ) and viscosity (η) are reported for aqueous binary mixtures of different glycol ethers, namely ethylene glycol monomethyl ether (EGMME), ethylene glycol monoethyl ether (EGMEE), diethylene glycol monomethyl ether (DEGMME), and diethylene glycol monoethyl ether (DEGMEE), at different temperatures (T = 275.15 K and 283.15 K) within the concentration range 0 mol · kg⁻¹ to 0.1 mol · kg⁻¹. The values of density (ρ) and viscosity (η) of the solutions were used to compute different derived parameters, such as apparent molar volume (?_V) of the solute, excess molar volume (V^E) of the solution, viscosity B and D coefficients of solution and temperature coefficient of viscosity B-coefficient (dB/dT) of solution. The limiting apparent molar volume of the solutes () have been obtained for aqueous binary mixtures of these glycol ethers by smooth extrapolation of ?_V–m curves to zero concentration. By using the values of , the limiting excess partial molar volumes () have also been calculated. The results are interpreted in term of various interactions such as solute–solvent interactions and hydrogen bonding.     

A convenient synthesis of linear pyranocoumarins. Xanthyletin and 3-Phenylxanthyletin

A convenient synthesis of linear pyranocoumarins, viz., 8,8-dimethyl-2H,8H-benzo[1,2-b; 5,4-b]dipyran-2-one (xanthyletin,1) and 8,8-dimethyl-3-phenyl-2H,8H-benzo[1,2-b; 5,4-b]dipyran-2-one (3-phenylxanthyletin,2) is described. The key steps are blocking the 8-position of appropriate 7-hydroxy-2H-1-benzopyran-2-one derivatives with iodine and 1,1-dimethyl-2-propynylation followed by cyclisation.

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Ein einfacher Syntheseweg zu linearen Pyranocumarinen. Xanthyletin und 3-Phenylxanthyletin

Zusammenfassung Es wird ein vorteilhafter Weg zur Synthese von linearen Pyranocumarinen am Beispiel von Xanthyletin und 3-Phenylxanthyletin gezeigt. Das Syntheseprinzip besteht in einer Blockierung der 8-Position des entsprechenden 7-Hydroxy-2H-1-benzopyran-2-ons mit Jod und einer 1,1-Dimethyl-2-propinylierung mit nachfolgender Cyclisierung.

     

Extraction and spectrophotometric determination of titanium(IV) withN 1-hydroxy-N 1,N 2-diphenylbenzamidine and thiocyanate

A precise, reliable, sensitive, and selective method for the determination of titanium(IV) is described. Titanium(IV) reacts withN ¹-hydroxy-N ¹,N ²-diphenylbenzamidine (HDPBA) and thiocyanate to form an orange-coloured mixed-ligand complex of stoichiometry 112 (Ti SCN^– HDPBA). The complex is quantitatively extractable into toluene from 0.05–0.15M hydrochloric acid. The spectrum of the complex exhibits an absorption maximum at 400 nm with a molar absorptivity of 20000M ^–1 cm^–1 and the coloured system obeys Beer's law in the concentration range 0.20–3.0 gml^–1 titanium. The effects of foreign ions and of various experimental parameters have been studied to establish the optimum conditions for the extraction and determination of titanium. The precision of the method has been evaluated and the relative standard deviation has been found to be 0.53%. The method has been successfully applied to the determination of titanium in synthetic matrices corresponding to titanium-containing ores, minerals, and alloys.     

Spectrophotometric determination of ciprofloxacin in pure form and in tablets through charge-transfer complexation reactions

Three simple, quick and sensitive spectrophotometric methods are described for the determination of ciprofloxacin. The methods are based on the reaction of this drug as ann-electron donor with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), 7,7,8,8,-tetracyanoquinodimethane (TCNQ) andp-chloranil (CL) as -acceptors to give highly coloured complex species. The coloured products are quantitated spectrophotometrically at 460, 843 and 550 nm for DDQ, TCNQ and CL, respectively. Optimization of the different experimental conditions is described. Beer's law is obeyed in the concentration ranges 5–50, 1.5–15 and 20–200 g ml^–1 ciprofloxacin, but the concentration ranges for best accuracy are 10–48, 2.5–15 and 35– 195 g ml^–1 of drug for DDQ, TCNQ and CL, respectively. The relative standard deviations are less than 1.5%. Applications of the suggested methods to ciprofloxacin tablets are presented and compared with the USP method. The stability constants of the 11 DDQ and CL complexes were 1.086 × 10⁴ and 2.581 × 10⁴ lmol^–1, respectively, whereas for the 12 TCNQ complex it was 3.62 × 10⁸1. mol^–1.     

S-Shaped composition dependence of excess thermodynamic quantities for cyclohexane mixtures with globular alkanes

Expansion coefficients , isothermal compressibilities, thermal pressure coefficients and heat capacities have been measured at 25°C for the cyclohexane+trans-decalin system. An S-shaped composition dependence, positivelnegative for highllow cyclohexane compositions is found for C _p ^E dV ^E /dT and the thermal expansion contribution to C _p ^E namely VT. The thermal motion contribution to C _p ^E , namely C _v is close to zero. The positive excursion of these mixing quantities at high cyclohexane content is anomalous. Correspondingly, the mixing quantity-VT deviates strongly in this region from the predicted equality with H ^E . The literature and this work show that all these excess quantities behave similarly for cyclohexane mixed with cyclooctane, methylcyclohexane and some highly branched alkanes. The unusual composition dependence of the thermodynamic quantities is consistent with order occurring when any large alkane molecule of globular shape is added to cyclohexane. This is speculatively associated with an interference by the globular alkane with the relatively free rotation of cyclohexane molecules.     

Thermodynamic, transport, and spectroscopic studies for mixtures of isomeric butanediol and N-methyl-2-pyrrolidinone

The thermodynamic parameters viz. excess molar volume V^E and speed of sound u, transport parameter viscosity η, and spectroscopic parameters viz. IR, ¹H, ¹³C NMR have been measured for the mixtures of isomeric butanediol (1,2-, 1,3-, 1,4-, and 2,3-butanediol) and N-methyl-2-pyrrolidinone over the whole composition range at 308.15 K. The partial molar quantities , isentropic compressibility , viscosity deviation Δη, deviation in Gibbs free energies of activation for viscous flow g(x), and excess NMR chemical shift δ^E have been estimated and analyzed. Results show that the interaction between unlike molecules takes place through hydroxyl groups of isomeric butanediol and CO group of N-methyl-2-pyrrolidinone. Excellent agreement between thermodynamic and spectroscopic measurements is observed.     

Spectrophotometeric determination of someN-substituted phenothiazine derivatives usingN-bromophthalimide

A simple, rapid and sensitive spectrophotometric method is described for the quantitative determination ofN-substituted phenothiazines. The method depends on the formation of a stable phenothiazine free radical cation by the use ofN-bromophthalimide as oxidising agent in a strong acid medium (methanol/ sulphuric acid 1 1 v/v). The produced red or violet color possesses absorption maximum range from 500 to 530 nm. A linear relationship exists between the absorbance at (_max) and concentration in the range 5 to 40 g ml^–1 with apparent molar absorptivities range from 6 × 10³ to 12 × 10³1 mol^–1 cm^–1. The color is developed instantaneously for all the studied phenothiazines except for thioproperazine mesylate, trifluoperazine dihydrochloride and prochlorperazine mesylate that require 25, 15 and 25 min, respectively, for complete reaction. The developed colors are stable over 24 h. The average % recovery is 99.85±0.61 to 100.28±0.95. The method was applied successfully to the microdetermination of chlorpromazine HCl, promethazine HCl, pericyazine, thioproperazine mesylate, perphenazine, prochlorperazine mesylate, trimeprazine tartrate and trifluoperazine 2HCl either in pure form or incorporated in their pharmaceutical preparations. The results of analysis are in good agreement with those of the official B.P. 1988 and USP XXII.     

16-Demethoxymethyllycaconitine,a new norditerpenoid alkaloid from Delphinium cuneatum

A new norditerpenoid alkaloid has been isolated from the roots of Delphinium cuneatum. On the basis of ¹H, ¹³C NMR, IR, and mass spectra, the structure of the alkaloid was established as 1,6,14-trimethoxy-7,8-dihydroxy-18-(2-methyl)succinylanthranoyloxyaconane (16-demethoxymethyllycaconitine). The roots of Delphinium cuneatum also contain the known alkaloid methyllycaconitine and N,N"-di(methoxycarbonyl)-3,4-diaminotoluene.     

The relation of directly bonded C-H coupling constants to s-characters revisited

Summary Following earlier theoretical studies of orbital delocalization effects on one-bond ¹³C-H coupling constants (¹ J _CH) an approximate proportionality of (¹ J _CH) to ^3/2, where is the s-character of the carbon hybrid orbital appropriate to the construction of the best localized molecular orbitals, is predicted and verified by using published data. It is proposed that this proportionality should replace the previous linear correlations of (¹ J _CH) with , which involve large additive constants.     

Kinetics of oxidation of glycine and valine by chloramine-T in hydrochloric acid medium

The kinetics of oxidation of glycine and valine by chloramine-T in hydrochloric acid medium has been studied. The rate of disappearance of chloramine-T shows a first order dependence on both chloramine-T and the amino acid, and an inverse first order with respect to [H⁺]. The solvent isotope effect was studied using heavy water. The kinetic parameters,E _a ,Arrhenius factorA, H and S and G have been calculated. A rate law in agreement with experimental results has been derived. A mechanism is proposed.

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Über die Kinetik der Oxidation von Glycin und Valin mit Chloramin-T in salzsaurem Medium

Zusammenfassung Die Kinetik der Oxidation von Glycin und Valin mit Chloramin-T in Salzsäure wurde untersucht. Die Geschwindigkeitskonstante des Wegreagierens von Chloramin-T zeigt eine Abhängigkeit erster Ordnung sowohl von Chloramin-T als auch von der Aminosäure und ist invers erster Ordnung bezüglich [H⁺]. Der Lösungsmittel-Isotopeneffekt wurde mit D₂O untersucht. Es wurden die kinetischen Parameter,E _a , derArrhenius-FaktorA, H , S und G , bestimmt. Ein Mechanismus, der in Übereinstimmung mit den experimentenllen Daten ist, wird vorgeschlagen.

     

Synthesis and X-ray crystal structure of [1,3-bis(η5-cyclopentadienyl)-1,1,3,3-tetramethyldisiloxane]hafnium(IV) dichloride

Summary The tetramethyldisiloxane-bridged hafnocene complex [HfCl₂{-(⁵-C₅H₄)SiMe₂OSiMe₂(²-C₅H₄)}] (1) has been prepared by the reaction of HfCl₄ with the dilithiatedbis(cyclopentadienyl)disiloxane (LiC₅H₄SiMe₂)₂O in a molar ratio of 1:2. The new compound was characterized by spectroscopic and X-ray diffraction methods. The crystals are monoclinic of space groupP2₁/c and isostructural with the corresponding complexes of titanium and zirconium. The unit cell dimensions area=13.51(1) Å,b=8.672(7) Å,c=15.41(1) Å, =97.15(2)°, andZ=4.

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Darstellung und Röntgenkristallstruktur von [1,3-Bis(⁵-cyclopentadienyl)-1,1,3,3-tetramethyldisiloxan]hafnium(IV)dichlorid

Zusammenfassung Der tetramethyldisiloxan-überbrückte Hafnocenkomplex [HfCl₂{-(⁵-C₅H₄)-SiMe₂OSiMe₂(²-C₅H₄)}] (1) wurde durch Umsetzung von HfCl₄ mit dem lithiiertenBis(cyclopentadienyl)disiloxan (LiC₅H₄SiMe₂)₂O im Molverhältnis 1:2 dargestellt. Die neue Verbindung wurde spektroskopisch und röntgenographisch charakterisiert. Sie kristallisiert in der monoklinen RaumgruppeP2₁/c und ist isostrukturell mit den entsprechenden Titan-und Zirkoniumkomplexen. Die Dimensionen der Einheitszelle sinda=13.51(1) Å,b=8.672(7) Å,c=15.41(1) Å, =97.15(2)° undZ=4.

     

Einfluß der Polarität und Viskosität des Lösungsmittels auf die Deaktivierung des S1-Zustandes von Donator-Akzeptor-substituiertentrans-Stilbenen

The dependence of the fluorescence constantsk _f ⁿ and the adiabatic twisting constantsk _tpof the S₁-State upon the solvent polarity, the capacity of hydrogen-bonding, as well as the solvent viscosity, were investigated for donor-acceptor substitutedtrans-stilbenes [4-dimethylamino-4-cyano-stilbene (1 g), 4-dimethylamino-4-diphenylphosphinyl-stilbene (1 b), 4-dimethylamino-4-brom-stilbene (1 h) and 4-dimethylamino-4-methoxistilbene (1 k)] by using the multiparameter model. An increase of the solvent polarity results in the decrease of the fluorescence ratek _f ⁿ for all these compounds. The specific interaction between the strongly polar stilbenes such as1 g and1 b and a solvent leads to additional decrease ink _f ⁿ but in the case of a relatively weak polar compound1 k to its growth. The linear combination of universal and specific solvent-solute interactions yields distinct relations fork _tp. Both interactions have an influence onk _tpfor1 g,1 b, and1 k to an equal degree. The twisting observed for1 g and1 b due to the interaction with solvent is hindered, however it is being supported for1 k. The influence of the investigated small range of viscosity onk _tpat simultaneous variable solvent polarity (pure solvent) is only visible for the weak polar1 k. In the other cases the effect of solvent-polarity is predominant.The viscosity dependence ofk _tpwas also experimentally proved for1 g,1 b and1 k by applying the obtained different dimethylformamid-acetonitril mixtures. According previous results the radiationless deactivation process is caused by twisting around ethyl-bonding, thereforek _tpevidently decreases with an increase of viscosity.

     

Nitrate ion association with Nd3+

The overall stability constantsK ₁ andK ₂ of NdNO ₃ ²⁺ and Nd(NO₃) ₂ ⁺ complexes were determined (K ₁=1.77;K ₂=1.28) using an extraction method with tri-n-butyl phosphate as the extractant. The ratio ₁/₂ of the stepwise stability constants is discussed. It was established that the Nd(NO₃) ₂ ⁺ complex was an outer-sphere ion pair.

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Die Assoziation von Nitrat-Ion mit Nd³⁺

Zusammenfassung Mittels einer Extraktionsmethode wurden die StabilitätskonstantenK ₁ undK ₂ von NdNO ₃ ²⁺ - und Nd(NO₃)⁺-Komplexen bestimmt (K ₁=1.77;K ₂=1.28; Tri-n-butylphosphat als Extraktionsmittel). Das Verhältnis ₁/₂ der stufenweisen Stabilitätskonstanten wird diskutiert. Es stellte sich heraus, daß der Nd(NO₃)⁺-Komplex als ein Outer-Shere-Ionenpaar vorliegt.

     

Konzentrations- und Temperaturabhängigkeit der Viskosität von Polyacrylnitril-Lösungen in Dimethylformamid

Viscosity measurements were carried out with polyacrylonitrile dissolved in dimethylformamide up to 0.36 g/ml. The temperature range was 20°C to 130°C, the highest shear gradient applied, 5.6·10³s^–1. The temperature variation of viscosity is reproduced with sufficient accuracy by the equation =k·exp (Q/RT). Bothk andQ increase as concentration increases, and the viscosity increases withc ^1.12 toc ^6.4 Inverse proportionality appears to exist between concentration and the longest relaxation time.

     

Host-guest interactions in aqueous media withp-tert.-butylcalix[4]arene bearing polyoxyethylene chains

The interactions ofp-tert.-butylcalix[4]arene bearing polyoxyethylene chains (C3) with pyrene (Py), 1-anilino-8-naphthalenesulfonate (ANS) andN-phenyl-naphthylamine (NPN) in aqueous solution were studied by absorption and fluorescence measurements. Absorption spectral changes and fluorescence enhancements reveal that C3, which has a hydrophobic cavity, can include organic molecules and ions in aqueous solution and form 11 host-guest complexes with ANS and NPN. C3 forms inclusion complexes with Py at different stoichiometries depending on the host: guest molar ratio. Binding constants of 2.2×10⁴, 2.0×10⁴ and 3.6×10⁵ dm³ mol^–1 were calculated for the C3Py, C3ANS and C3NPN complexes (11), respectively, based on the Benesi-Hildebrand equation.Author for correspondence.     

Extension of a simplified method for molecular correlation energy calculations to molecules containing third row atoms II. Application to HCl,HCl+, ClO and NCl molecules

A simplified method for molecular correlation energy calculations developed in I is applied to the determination of the potential curves of some diatomic chlorinated molecules HCl(¹⁺), HCl⁺(²II), ClO(²II) and NCl(X ^3–, a ¹, b ¹⁺). Dissociation energies, vibrational frequencies and equilibrium internuclear distances are derived from these curves. The ionisation potential (I _p) of HCl, the proton affinity (PA) of Cl, and the term energies of the excited states of the NCl radical are also calculated. It is shown that the results are very sensitive to correlation effects and that the correlated results converge to the corresponding experimental values within 10% for PA, D _e , T _e and _e, 2% for R _e and 0.3% for I _p. This agreement allows us to predict the following lower limits for the dissociation energies of the NCl radical: 2.14, 3.28 and 2.47 eV respectively for the X^3–, a ¹ and b ¹⁺ states. Results on HF and HF⁺ are also discussed and compared with those obtained for HCl and HCl⁺.Boursier IRSIA     

Complexes of dioxouranium(VI) with zwitter-ionic forms of Bi- and tetra-dentateSchiff bases

Potentially bi- and tetra-dentateSchiff bases derived from salicylaldehyde react with hydrated uranyl salts to give complexes: UO₂H₂ LX ₂, UO₂H₂ LX ₂ and UO₂(HL)₂ X ₂ [H₂ L=N,N-propane-1,3-diylbis(salicylideneimine), H₂ L=N,N-ethylenebis(salicylideneimine) and HL=N-phenylsalicylideneimine;X ^–=Cl^–, Br^–, I^–, NO₃ ^–, ClO₄ ^–, and NCS^–]. Because of marked spectral similrities with the structurally known Ca(H₂ L) (NO₃)₂, theSchiff bases are coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms of the azomethine groups which carry the protons transferred from phenolic groups on coordination. Halide, nitrate, perchlorate and thiocyanate groups are covalently bonded to the uranyl ion, resulting a 6-coordinated uranium ion in the halo and thiocyanato complexes and 8-coordinated in nitrato and perchlorato complexes.

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Komplexe von Dioxouranyl(VI) mit zwitterionischen Formen von zwei- und vierzähnigen Schiff-Basen

Zusammenfassung Von Salizylaldehyd abgeleitete zwei- und vierzähnigeSchiff-Basen reagieren mit hydratisierten Uranylsalzen zu Komplexen folgenden Typs: UO₂H₂ LX ₂, UO₂H₂ LX ₂ und UO₂(HL)₂ X ₂ [H₂ L=N,N-Propan-1,3-diylbis(salicylidenimin), H₂ L=N,N-Ethylen-bis(salicylidenimin) und HL=N-Phenylsalicylidenimin;X ^–=Cl^–, Br^–, I^–, NO₃ ^–, ClO₄ ^– und NCS^–]. Auf Grund eindeutiger spektraler Ähnlichkeiten mit dem bekannten Ca(H₂ L) (NO₃)₂ wird auf Koordination über die negativ geladenen phenolischen Sauerstoffatome (und nicht über die Azomethin-Stickstoffe) geschlossen. Die AnionenX ^– sind kovalent an das Uranyl-Ion gebunden; damit ergibt sich ein hexakoordiniertes Uranyl-Ion für die Halogen- und Thiocyanat-Komplexe und Oktakoordination für die Nitrat- und Perchlorat-Komplexe.

     

Absorption spectra of 2-styryl-4-phenyl-thiazole ethiodides in organic solvents of varying polarities and determination of the formation constant of the charge transfer complex formed

The electronic absorption spectra of some 2-styryl-4-phenyl-thiazole ethiodides are studied in organic solvents of different polarities. The shorter wavelength band appearing in the visible region is assigned to an intramolecular charge transfer (CT)-transition originating from the phenyl moiety to the positively charged hetero ring, while the longer wavelength one is due to an intermolecular CT-transition from the iodide ion to the 2-styryl-4-phenyl-thiazolinium cation. These assignments are based on the nature of the aldehydic residue and effects of solvent, concentration, and temperature on both the position and absorptivity of the CT complex-band. It is concluded that the CT complex formed will be highly solvated inDMF, DMSO, ethanol and methanol relative to in CHCl₃, dioxane and acetone. The formation constant of the CT complex in solutions of different polarities is determined at different temperatures. Furthermore, the thermodynamic parameters H ^o, G ^o and S ^o for complex formation are calculated and discussed.

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Absorptionsspektren von 2-Styryl-4-phenyl-thiazol-ethiodiden in verschiedenen Lösungsmitteln und Bestimmung der Bildungskonstanten der Charge-Transfer-Komplexe

Zusammenfassung Die Elektronenanregungsspektren einiger substituierter 2-Styryl-4-phenyl-thiazol-ethiodide wurden in einigen Lösungsmitteln unterschiedlicher Polarität untersucht. Die Absorption bei kürzerer Wellenlänge wird einem intramolekularen Charge-Transfer (CT)-Übergang zugeordnet, die langwellige Bande einem intermolekularen CT-Übergang (Jodid—organ. Kation). Die Diskussion erfolgt basierend auf Substitutions-, Lösungsmittel-, Konzentrations-, und Temperatur-Effekten. Die Komplexbildungskonstanten und die thermodynamischen Parameter H ^o, G ^o und S ^o werden angegeben.

     

Synthese,Kristallstruktur und Konformation von N2-Dibenzyl-N1-t-butoxycarbonylhydrazin

Summary The synthesis and the crystal structure of N²-dibenzyl-N¹-butoxycarbonyl hydrazine are reported. The compound was prepared from commercially availablet-butyl carbazate. It crystallizes in the triclinic space group P 1 witha=5.479(1) Å,b=9.559(1) Å,c=9.748(1) Å,a=63.81(1)°, =87.52(1)°, =74.07(1) Å,Z=1,D=1.18 g/cm³. The structure was solved by direct methods and refined toR=0.0329.