Thermodynamic Properties in Gold Phenylacetylide in the Range 0-330 K

The temperature dependence of the heat capacity of gold phenylacetylide in the range 13-330 K was measured in an adiabatic vacuum calorimeter with an accuracy of 0.3%. These data were used for calculating the thermodynamic functions C _p0(T), H ⁰(T) - H ⁰(0), S ⁰(T) - S ⁰(0), and G ⁰(T) - H ⁰(0) for the range 0-330 K. The standard entropy of formation _f S ⁰ of gold phenylacetylide from the elements at T 298.15 K and p 101.325 kPa was calculated. The thermodynamic properties of gold phenylacetylide and related silver and copper compounds were compared.     

Thermodynamic Properties of Tetraphenyltetrahydroxycyclotetrasiloxane,Octaphenyltetrahydroxytricyclooctasiloxane, Octaphenylpentacyclosilsesquioxane,and Polyphenylsilsesquioxane in the Range 0-300 K

The temperature dependences of the heat capacities of crystalline tetraphenyltetrahydroxycyclotetrasiloxane, octaphenyltetrahydroxytricyclooctasiloxane, and octaphenylpentacyclosilsesquioxane and of glassy polyphenylsilsesquioxane were measured in the range 6-300 K with an adiabatic vacuum calorimeter, with an accuracy of 0.3%. From these data, the thermodynamic functions C ⁰ _p (T), H ⁰(T) - H ⁰(0), S ⁰(T) - S ⁰(0), and G ⁰(T) - H ⁰(0) of these substances were calculated for the range 0-300 K. The standard entropies of their formation from elements at 298.15 K, _f S ⁰, and the entropies of mutual transformations of these substances in the range 0-298.15 K were calculated.     

Thermodynamic Properties of Dibenzo-24-crown-8 in the Range from T → 0 to 500 K

The temperature dependence of the heat capacity of dibenzo-24-crown-8 in the range 6-500 K was measured by adiabatic vacuum and dynamic calorimetry with an accuracy of 0.2-0.5%. The physical transformations of the title compound occurring on its heating and cooling within the above temperature range were revealed and characterized. From the experimental data obtained for dibenzo-24-crown-8, its thermodynamic functions C _4p ⁰(T), H ⁰(T) - H ⁰(0), S ⁰(T) - S ⁰(0), and G ⁰(T) - H ⁰(0) were calculated for the range from T 0 to 500 K; the standard entropy of formation from the elements, _s S ⁰, at T 298.15 K was also calculated. The fractal dimensions D in the heat capacity function of the multifractal version of the Debye heat capacity theory, characterizing the heterodynamic characteristics of the title compound, were calculated.     

Zur Mannich-Reaktion von Dihydro-6-methyl-2(1H)-pyrimidinonen

Zusammenfassung Dihydro-4,4,6-trimethyl-2(1H)-pyrimidinone reagieren mit Formaldehyd und sekundären bzw. primären Aminen zu 6-Dialkylaminoäthylidentetrahydro-2(1H)-pyrimidinonen bzw. Hexahydro-2(1H)-pyrido[4,3-d]Pyrimidinonen. Mit Succindialdehyd bzw. Glutardialdehyd und primären Aminen entstehen 5,7-Äthanohexahydro-2(1H)-pyrido[4,3-d]pyrimidinone bzw. Tetrahydro-6,8-propano-6H-pyrimido[1,6-c]pyrimidin-1(2H)-one. Die 6-Dialkylaminoäthylidentetrahydro-2(1H)-pyrimidinone geben mit Phenolen Tetrahydrospiro([1]benzopyran-2,4(1H)-pyrimidin)-2(3H)-one, mit cycl. -Dicarbonylverbindungen Hexahydrospiro([1]benzopyran-2,4(1H)-pyrimidin)-2,5(3H, 6H)-dione bzw. Tetrahydrospiro(2H,5H-pyrano[3,2-c][1]benzopyran-2,4(1H)-pyrimidin)-2(3H),5-dione bzw. mit Malonestern -(Tetrahydro-4,4-dimethyl-2-oxo-6-pyrimidyl)-äthylmalonester.Zusammenfassung Dihydro-4.4.6-trimethyl-2(1H)-pyrimidinones react with formaldehyde and sec. and prim. amines resp. to 6-dialkylaminoethylidentetrahydro-2(1H)-pyrimidinones and hexahydro-2(1H)-pyrido[4.3-d]pyrimidinones, resp. succindialdehyde and glutaraldehyde with primary amines give 5.7-ethanohexahydro-2(1H)-pyrido[4.3-d]pyrimidinones and tetrahydro6.8-propano-6H-pyrimido[1.6-c]pyrimidin-1(2H)-ones, resp. 6-Dialkylaminoethylidentetrahydro-2(1H)-pyrimidinones react with phenols to tetrahydrospiro([1]benzopyran-2.4(1H)-pyrimidin)-2(3H)-ones, with cyclic -dicarbonyl compounds to hexahydrospiro([1]benzopyran-2.4 (1H)-pyrimidin)-2,5 (3H), 6H)-diones and tetrahydrospiro(2H,5H-pyrano[3.2-c][1]benzopyran-2.4(1H)-pyrimidin)-2(3H),5-diones, resp., with malonates -(tetrahydro-4.4-dimethyl-2-oxopyrimidyl-6)-ethylmalonates.

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Mannich reaction with dihydro-6-methyl-2(1H)-pyrimidinones

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Herrn Prof. Dr.F. Kuffner zum 65. Geburtstag gewidmet.     

Iron(II) Complexes with 4-R-1,2,4-Triazoles (R = Ethyl,Propyl, Isopropyl): Synthesis and Properties

Fe(II) complexes with 4-R-1,2,4-triazoles of compositions FeL₃A₂ · nH₂O (where L is 4-propyl-1,2,4-triazol; A is Br^- (n = 4), CF₃SO₃ ^- (n = 5)), and FeL₂A₂ · nH₂O (where L are 4-ethyl-, 4-propyl-, 4-isopropyl-1,2,4-triazoles (Ettrz, Prtrz, Iprtrz, respectively), A = NCS^-, NO₃ ^- (n = 0-2)) were synthesized. Magnetochemical studies revealed that FeL₃A₂ · nH₂O complexes exhibit reversible spin transition (ST) ¹ A ₁ ⁵ T ₂ that is accompanied by thermochromism (a reversible change of color rose white). The temperatures of direct (T _s) and reverse (T _s) spin transitions are, respectively, 252 and 247 K for Fe(rtrz)₃Br₂ · 4H₂O and 207 and 202 K for Fe(rtrz)₃(CF₃SO₃)₂ · 5H₂O. Dehydration of the complexes is attended by significant changes in the type and temperatures of ST.     

Asymmetrical synthesis of organometallic analogs of natural compounds. 8. Reactions of pentafluorobenzaldehyde with the Ni(II) complex of a schiff base of glycine and (S)-2-[N-(benzylprolyl)amino]benzophenone

Reaction of pentafluorobenzaldehyde with a Ni(II) complex of a Schiff base formed from glycine and (S)-2-[N-(benzylprolyl)amino]benzophenone yields, depending on the reaction conditions, the hitherto unknown, diastereo-and enantiomerically pure amino acids 2R,3S--(4-methoxytetrafluorophenyl)serine, 2S,3R--(4-methoxytetrafluorophenyl)serine, 2S,3S--(pentafluorophenyl)serine, and 2S,3R--(pentafluorophenyl)serine.A. N. Nesmeyanov Institute of Organometallic Compounds, Russian Academy of Sciences, 117813 Moscow. Institute of Bioorganic Chemistry and Petroleum Chemistry, Ukrainian Academy of Sciences, 252028 Kiev. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 687–693, March, 1992.     

Complex formation constants and thermodynamic parameters for La(III) and Y(III)L-serine complexes

Summary The stoichiometric stability constants for La(III) and Y(III)L-serine complexes were determined by potentiometric methods at different ionic strengths adjusted with NaClO₄ and at different temperatures. The overall changes in free energy (G ^o), enthalpy (H ^o), and entropy (S ^o) during the protonation ofL-serine and that accompanying the complex formation with the metal ions have been evaluated.

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Komplexbildungskonstanten und thermodynamische Parameter für La(III)- und Y(III)-L-Serin-Komplexe

Zusammenfassung Die stöchiometrischen Komplexbildungskonstanten für La(III)- und Y(III)-L-Serin-Komplexe wurden mittels potentiometrischer Methoden bei verschiedenen Ionenstärken (mit NaClO₄ adjustiert) und bei verschiedenen Temperaturen bestimmt. Die Änderungen in der freien Energie (G ^o), Enthalpie (H ^o) und Entropie (S ^o) während der Protonierung und der Komplexbildung mit den Metallionen wurden ermittelt.

     

Thermodynamics of copper,silver, gold,and mercury acetylenides

Thermodynamic characteristics of the copper, silver, gold, and mercury acetylenides obtained from the data of precise calorimetric measurements in the region from 5 to 340 K are considered. Tables of the thermodynamic functions C _p°(T), H°(T) — H°(0), S°(T), and G°(T) — H°(0) at 0—340 K, standard enthalpies of combustion H _c°, and thermodynamic characteristics of formation of the acetylenides from simple substances H _f°, S _f°, G _f°, and logK _f° at 298.15 K and standard pressure are presented. Temperature plots of the heat capacity of the acetylenides were analyzed in the framework of Tarasov's theory and the fractal version of Debye's theory of heat capacity. The values of heat capacity of several acetylenides yet unstudied were estimated.     

Complex formation between glycine and magnesium (II), calcium(II), and iron(II) at 25 °C in 3.00M NaClO4

Equilibria occurring between glycine (L) and magnesium(II) and calcium(II) were studied by measuring at 25 °C the electromotive force (e.m.f.) of the cell: (–) Pt, H₂/SolutionS/R.E. (+) where R.E. is the reference electrode described in the text.Equilibria taking place in solutions containing iron(II) and glycine were investigated by means of the cell: (–) R.E./SolutionS/G.E. (+) where G.E. is the glass electrode. The general composition of solutionS was in both cases the following: B M inM ²⁺;H M in H⁺;A M inL; 3.00M in ClO ₄ ^– ; (3-H-2B)M in Na⁺.Experimental data were explained by assuming the existence of the species:: MgL(log _1,0,1=1.53±0.05); MgL ₂(log _2,0,1=2.26±0.05); CaL(log _1,0,1==0.75±0.03); FeL(log _1,0,1=4.20±0.04).Protonation constants of aminoacetate, not known in the experimental conditions selected, were determined by means of e.m.f. measurements carried out with a H₂ electrode.

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Komplexbildung zwischen Glycin und Magnesium(II), Calcium(II), bzw. Eisen(II) bei 25 °C in 3,00M NaClO₄

Zusammenfassung Die Gleichgewichte zwischen Glycin (L) und Magnesium(II) bzw. Calcium(II) wurden bei 25 °C durch E.M.K. Messungen der folgenden Meßkette untersucht: (–) Pt, H₂/ProbenlösungS/R.E. (+) wobei R.E. Referenz-Elektrode bedeutet (siehe Text).Zum Studium der Reaktion zwischen Eisen(II) und Glycin bei 25 °C wurde folgende Meßkette benutzt: (–) R.E./ProbenlösungS/G.E. (+) wobei G.E. Glas-Elektrode bedeutet.Alle Meßproben hatten die folgende allgemeine Zusammensetzung:B M inM ²⁺;H M in H⁺;A M inL; 3,00M in ClO ₄ ^– ; (3-H-2B)M in Na⁺.Die experimentellen Daten konnten unter Annahme folgender Komplexe erklärt werden: MgL(log _1,0,1=1,53±0,05); MgL ₂(log _2,0,1=2,26±0,05); CaL(log _1,0,1=0,75±0,03); FeL(log _1,0,1=4,20±0,04). Die Protonierungskonstanten von Aminoacetat, die bei den gewählten experimentellen Bedingungen nicht bekannt sind, wurden mittels E.M.K. Messungen (mit Wasserstoff-Elektrode) bestimmt.

     

Mixed ligand titanium(IV) complexes. Chlorobis(dithiocarbamato)bis(methylsalicylato)titanium(IV) andbis(dithiocarbamato)bis(methylsalicylato)titanium(IV)

Summary Dichlorobis(methylsalicylato)titanium(IV) reacts with potassium or amine salts of dialkyl or diaryl dithiocarbamates in 11 and 12 molar ratios in anhydrous benzene (room temperature) or in boiling CH₂Cl₂ to yield mixed ligand complexes: (AcOC₆H₄O)₂ Ti(S₂CNR₂)Cl (1) and (AcOC₆H₄O)₂ Ti(S₂CNR₂)₂ (2), R=Et, n-Pr, n-Bu, cyclo-C₄H₈ and cyclo-C₅H₁₀. These compounds are moisture sensitive and highly soluble in polar solvents. Molecular weight measurement in conjunction with i.r.,¹H and¹³C n.m.r. spectral studies suggest coordination number 7 and 8 around titanium(IV) in (1) and (2) respectively.     

Synthesis and magnetic properties of trinuclear chromium(III)palladium(II)-chromium(III) complexes bridged by extended dioximato groups

Summary Heterotrinuclear Cr^III-Pd^II-Cr^III complexes of formulae [Cr(salen)-Pd(dmg)₂-Cr(salen)]·H₂O (1), [Cr(salen)-Pd(-BD) ₂-Cr(salen)]·H₂O (2) and [Cr(salen)-Pd(-FD) ₂-Cr(salen)]·2H₂O (3) [dmg^2- =dimethyl-glyoximato, (-BD)^2/2- = -benzyldioximato, (-FD)^2/2- = -furildioximato and salen^2– = N,N-ethylenebis(salicylideneiminate)] have been prepared and characterized by elemental analysis, i.r. and electronic spectroscopies, and molar conductances. These complexes are thought to contain extended diomixato bridges. The magnetic properties of complex (1) has been investigated over the 80–300 K range and corresponds to what is expected for an antiferromagnetic Cr^III-Cr^IIIi pair with S _Cr = 3/2 and S _Pd = 0 (Pd²⁺ is a diamagnetic in a square-planar environment) local spins. The exchange integral (J) was evaluated as -3.38cm^–1 using the spin Hamiltonians = -2J _{A B}(S _A = S _B = 3/2).     

Reactions of ortho-Phenylenediamine with a Nickel Trimethylacetate Complex

Interaction of ortho-phenylenediamine with the nonanuclear nickel trimethylacetate cluster Ni₉(₄-OH)₃(₃-OH)₃( _n -OOCMe₃)₁₂(HOOCCMe₃)₄(I) in an amine deficiency yields the antiferromagnetic trinuclear complex [Ni₃{-N,N"-(NH₂)₂C₆H₄}₂(HCCOOCMe₃)₃(₃-OH)(-OOCCMe₃)₄]⁺(OOCCMe₃)^–(III) containing bridging diamine ligands. Reaction of excess diamine with Ior IIIleads to the formation of the paramagnetic monomer Ni{²-o-(NH₂)₂C₆H₄}₂(OOCCMe₃)₂(IV), which reacts with atmospheric oxygen to form the known bis(semiquinonediimine) complex Ni[1,2-(NH)₂C₆H₄]₂(V).     

Thermodynamic Properties of Styrenetricarbonylchromium, α-Methylstyrenetricarbonylchromium,and p-Methylstyrenetricarbonylchromium in the Range 0-450 K

The thermodynamic properties of styrenetricarbonylchromium, -methylstyrenetricarbonylchromium, and p-methylstyrenetricarbonylchromium were studied with adiabatic vacuum and dynamic calorimeters. The heat capacity in the range 5-450 K (error about 0.3% in most cases) and the temperatures and enthalpies of the phase transitions were determined. The experimental data were used to calculate the thermodynamic functions C ⁰ _p(T), H ⁰(T) - H ⁰(0), S ⁰(T), and G ⁰(T) - H ⁰(0) for the range from 0 to 330-400 K, and also the isochoric heat capacity C _v and its lattice (_Cv,latt) and atomic (C _v,at) contributions for the range from 0 K to T ⁰ _m; the parameters = C ⁰ _p/C _v were evaluated. The thermodynamic properties were considered in relation to the composition and structure of the compounds.     

Thermodynamic properties of carbynoid structures in the 0—340 K range

The temperature dependences of the heat capacity (C _p°) of carbynoid structures prepared by alkaline dehydrochlorination of poly(vinylidene chloride) and 1,1,2- and 1,2,3-polytrichlorobutadienes were studied by adiabatic vacuum calorimetry between 5 and 340 K with an accuracy of 0.2%. The low-temperature relaxation transitions and abnormal patterns of the C _p° vs. T dependences were identified and characterized. The experimental results were used to calculate the thermodynamic functions C _p°(T), H°(T) – H°(0), S°(T) – S°(0), and G°(T) – H°(0) for 0—340 K. These data were compared with the corresponding data for carbyne produced by oxidative dehydropolycondensation of acetylene, which is a mixture of amorphous - and -forms with a minor impurity of crystals of both forms.     

Novel dioximato-bridged chromium(III)-copper(II)-chromium(III) trinuclear complexes with ferromagnetic exchange interactions

Summary Two new dioximato-bridged trinuclear Cr^II-Cu^II-Cr^III complexes, [Cr(salen)-Cu(-BD)₂-Cr(salen)] (1) and [Cr(salen)-Cu(-FD)₂-Cr(salen)]-H₂O (2), have been prepared and characterized [salen^2– = N,N-ethylene- bis (salicylideneiminate), (-BD)^2– = -benzyldioximato and (-FD)^2– = -furildioximato]. Magnetic susceptibility measurements in the 4.2–300 K range demonstrated the operation of a ferromagnetic interaction between the adjacent Cr^III and Cu^II ions through oximato bridges in both (1) and (2). Based on spin Hamiltonians =–2J(₁₂+₂₃)(S₁=S₃=3/2,S₂=1/2) the exchange integrals (J) were evaluated as 3.19 and 5.38 cm^–1 for (1) and (2), respectively.     

Doubly-bridged binuclear complexes of oxomolybdenum(V) and oxotungsten(V) containing sexadentate ligands

Binuclear oxomolybdenum(V) and oxotungsten(V) complexes of the type, [M ₂(O)₂(-X)(-X ¹)], where M=Mo, W;X.X ¹=O, S; L=edta, pdta (n=2-), tpen, tppn (n=2+) (edta^4– =ethylenediaminetetraacetate(4–), pdta=R- orR,S-propylenediaminetetraacetate(4–), tpen=N,N,N ¹,N¹-tetrakis(2-pyridyhnethyl)-ethylenediamine, and tppn=R- orR,S-N,N,N ¹,N¹-tetrakis(2-pyridylmethyl)-propylenediami ne) are reviewed with respect to their preparation, structure, spectroscopic properties, reactivities, and in particular asymmetric distortion around the bicyclo [4.1.1 ] type core and stereoselectivity related to this distortion,Dedicated to Professor Jiaxi Lu on the occasion of his 80th birthday and in recognition of his pioneering contributions.     

Redox Properties of Rhodium(III) Oxo-Bridged Carboxylate Complexes

Chemical and electrochemical oxidation of rhodium (III) oxo-bridged carboxylate complexes was studied. The chemical [with O₃ and Ce(IV) salts] or electrochemical (at potentials of 1.00-1.20 V) oxidations of the binuclear complexes [Rh₂(-O)(-O₂CCH₃)₂(H₂O)₆]^{2 +} and [Rh₂(-O)(-O₂CCF₃)₂(H₂O)₆]^{2 +} leads to the superoxo complexes [Rh₂(-O)(O₂-)(-O₂CCH₃)₂(H₂O)₅]⁺ and [Rh₂(-O)(O₂ ^-)(-O₂CCF₃)₂(H₂O)₅]⁺ with terminal coordination of O₂-. The trinuclear acetate [Rh₃(₃-O)(-O₂CCH₃)₆(H₂O)₃]⁺, unlike its trifluoroacetate analog [Rh3(₃-O)(-O₂CCF₃)₆(H₂O)₃]⁺, is oxidized only electrochemically at a potential of 1.38 V. The oxidation of [Rh₃(₃-O)(-O₂CCH₃)₆(H₂O)₃]⁺ is reversible and involves formation of an unstable superoxo group O₂ ^- between two Rh₃III(₃-O) cores.     

Substituted 1,2-Thiazetidine 1,1-Dioxides. Synthesis of (<Emphasis Type="Italic">RS</Emphasis>)- and (<Emphasis Type="Italic">S</Emphasis>)-1,2-Thiazetidine-3-acetic Acid 1,1-Dioxide and its Reactions with Amino Acids and Dipeptides

Summary. (RS)-2-tert-Butyldimethylsilyl-1,2-thiazetidine-3-acetic acid 1,1-dioxide prepared from (RS)-S-benzyl--homocysteine was condensed via DCC/NHS with various L-amino acid esters or dipeptide esters yielding N-silylated -sultam peptides. A -sultam active ester was isolated as an intermediate. Desilylation with TBAF in THF yielded stable N-unsubstituted products, and deprotection of the benzyl esters was achieved by catalytic hydrogenation. (S)-S-Benzyl--homocysteine was obtained by fractional crystallization of the brucine salt of the racemate and transformed into benzyl (S)-1,2-thiazetidine-3-acetate, which was on the other hand synthesized by an enantiospecific route from -benzyl Boc-L-aspartate. Some -sultam peptides were prepared from the (S)-enantiomer, and finally some -sultam peptides containing D-Ala units were obtained.     

Molecular mechanics modelling of Pt(II) complexes with antitumor activity. Influence of the type and the positions of the ring substituents on the conformational energies and thermodynamic stabilities

Summary The influence of the type and the positions of the ring substituents on the conformational energies and thermodynamic stabilities of a series of Pt(II) complexes of the general formula [1,2-bis(hydroxyphenyl)ethylenediamine]PtL ₂(L ₂=2Cl^–, 2I^–, SO ₄ ^2– ) has been studied by molecular mechanics. The calculations were carried out for the ligand conformations (R,S/S,R)-, (R,S/S,R)-, (R,R)-, and (S,S)-. The obtained energies and thermodynamic stabilities are in agreement with experimental data on the reactivity and antitumor activity of the compounds.

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Molecular Modelling von Pt(II)-Komplexen mit Antitumoraktivität. Einfluß von Art und Position von Substituenten auf Konformationsenergien und thermodynamische Stabilitäten

Zusammenfassung Die konformationellen Energien und thermodynamischen Stabilitäten einer Reihe von Pt(II)-Komplexen mit der allgemeinen Formel [1,2-bis(Hydroxyphenyl) ethylendiamin]PtL ₂(L ₂=2Cl^–, 2I^–, SO ₄ ^2– ) wurden mittels molekularmechanischer Methoden in Abhängigkeit von Art und Stellung der Substituenten an den Phenylringen untersucht. Die Berechnungen wurden für die Ligandenkonformationen (R,S/S,R)-, (R,S/S,R)-, (R,R)- und (S,S)- durchgeführt. Die erhaltenen Energien und Stabilitäten stimmen mit experimentellen Daten über Reaktivität und Antitumoraktivität der Verbindungen überein.

     

Formation of cobalt(iii) cations with semiquinonediimine ligands

The reactions of polynuclear cobalt(ii) trimethylacetates [Co(OH) _n (OOCCMe₃)_2–n ] _x , Co₆(₃-OH)₂(OOCCMe₃)₁₀(HOOCCMe₃)₄, or Co₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ with an excess of N-phenyl-o-phenylenediamine (1) in toluene followed by treatment with atmospheric oxygen afforded the diamagnetic complex [Co{²-(NPh)(NH)C₆H₄}₂{¹-(NH₂)C₆H₄(NPhH)}]⁺(Me₃CCOO...H...OOCCMe₃)^– (3), whose cation contains the Co^III atom. The reaction of Co₄(₃-OH)₂(OOCCMe₃)₆(HOEt)₆ with a deficient amount of diamine 1 in acetonitrile under an argon atmosphere gave rise to the antiferromagnetic ionic complex [Co{²-(NPh)(NH)C₆H₄}₂MeCN]⁺[Co₂(₂,²-OOCCMe₃)(₂-OOCCMe₃)₂(²-OOCCMe₃)₂]^–·2MeCN (4), whose cation is an isoelectronic analog of the cation in complex 3. The structures of the new compounds were established by X-ray diffraction analysis.