Organogermyl,Organostannyl, and Organoplumbyl Phosphines,Arsines, Stibines,and Bismuthines

The preparation, properties, and reactions of the compounds named in the title are described, with particular reference to the possible participation of (p→d)_π components in the bonding between the group IVB and the group VB elements.     

Structural, magnetic, and spectroscopic studies of YAgSn, TmAgSn, and LuAgSn

The rare earth-silver-stannides YAgSn, TmAgSn, and LuAgSn were synthesized from the elements by arc-melting and subsequent annealing. The three stannides were investigated by X-ray powder and single-crystal diffraction: NdPtSb type, P6₃mc, Z=2, a=468.3(1), pm, wR₂=0.0343, 353 F² values, 12 variables for YAgSn, and ZrNiAl type, P6¯2 m, a=726.4(2), , wR₂=0.0399, 659 F² values, 15 variables for TmAgSn, and a=723.8(2), , wR₂=0.0674, 364 F² values, 15 variables for LuAgSn. Besides conventional laboratory X-ray data with monochromatized Mo radiation, the structures were also refined on the basis of synchrotron data with , in order to clarify the silver-tin ordering more precisely. YAgSn has puckered, two-dimensional [AgSn] networks with Ag-Sn distances of 278 pm, while the [AgSn] networks of TmAgSn and LuAgSn are three-dimensional with Ag-Sn distances of 279 and 284 pm for LuAgSn. Susceptibility measurements indicate Pauli paramagnetism for YAgSn and LuAgSn. TmAgSn is a Curie-Weiss paramagnet with an experimental magnetic moment of 7.2 μ_B/Tm. No magnetic ordering is evident down to 2 K. The local environments of the tin sites in these compounds were characterized by ¹¹⁹Sn Mössbauer spectroscopy and solid-state NMR (in YAgSn and LuAgSn), confirming the tin site multiplicities proposed from the structure solutions and the absence of Sn/Ag site disordering. Mössbauer quadrupolar splittings were found in good agreement with calculated electric field gradients predicted quantum chemically by the WIEN2k code. Furthermore, an excellent correlation was found between experimental ¹¹⁹Sn nuclear magnetic shielding anisotropies (determined via MAS-NMR) and calculated electric field gradients. Electronic structure calculations predict metallic properties with strong Ag-Sn bonds and also significant Ag-Ag bonding in LuAgSn.     

Mild, powerful, and robust methods for esterification, amide formation, and thioesterification between acid chlorides and alcohols, amines, thiols, respectively

We developed two efficient practical methods for esterification, amide formation, and thioesterification between acid chlorides and alcohols, amines, thiols, respectively. The present mild and robust reaction was performed by two separate methods both by combining cheap and readily available amines, N-methylimidazole, and N,N,N′,N′-tetramethylethylenediamine (TMEDA). Method A uses catalytic N-methylimidazole and TMEDA with an equimolar amount of K₂CO₃, whereas Method B uses equimolar amounts of N-methylimidazole and TMEDA. The salient features are as follows. (i) With regard to reactivity, Method B was superior to Method A for esterification and thioesterification, whereas cost-effective Method A was superior to Method B for amide formation. (ii) Amide formation proceeded smoothly between acid chlorides and less nucleophilic and stereocongested amines such as 2,6-dichloroaniline. (iii) This protocol was applied to the successful synthesis of two agrochemicals, bromobutide and carpropamid.     

Determination of Cd, Co, Cr, Cu, Fe, Ni and Pb in Milk, Cheese and Chocolate

 Combined analytical procedures consisting of wet digestion step followed by instrumental determination – differential pulse cathodic stripping voltammetry (DPCSV) or electrothermal atomic absorption spectrometry (ETAAS) – as well as a direct analysis method – slurry sampling ETAAS – for the determination of Cd, Co, Cr, Cu, Fe, Ni and Pb in milk, cheese and chocolate are described and compared. Wet digestion using a mixture of HNO₃-HClO₄-H₂O₂ is proposed for complete matrix decomposition prior to trace analyte determinati on by DPCSV or ETAAS. A mixture of HNO₃-H₂O₂ is used for slurry preparation. Optimal instrumental parameters for trace analyte measurements are presented. The reliability of the procedures has been verified by analyzing standard reference materials. Results obtained are in good agreement with the certified values and the relative standard deviations (for these results) are in the range 5–10% for wet digestion DPCSV or ETAAS and 3–9% for slurry sampling ETAAS in the range of 2 μgċg⁻¹ (Cd) to 12 μgċg⁻¹ (Fe). Received August 24, 1999. Revision January 20, 2000.     

Synthesis of yttrium,lanthanum, neodymium,praseodymium, and lutetium alkoxides and acetylacetonates

A convenient and practical method is proposed for the synthesis of lanthanide and yttrium alkoxides. The method involves dissolving the metals or their hydrides in a solution of dry HCl in the corresponding alcohol, with subsequent dehalogenation of the LnCl₃ solution by an equivalent amount of alkali metal (Na, Li), The rareearth alkoxides are easily converted into acetylacetonates Ln(acac)₃ by the action of acetylacetone.A. N. Nesmeyanov Institute of Elementoorganic Compounds, Russian Academy of Sciences, 117813 Moscow. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2490–2493, November, 1992.     

Theoretical Study of Molecular Structure,Reactivity, Lipophilicity,and Solubility of N-Hydroxyurea,N-Hydroxythiourea,and N-Hydroxysilaurea

Ab initio molecular orbital methods at the CBS-QB3 level of theory have been used to study the structure and gas-phase stability of various tautomers and rotamers of N-hydroxyurea, N-hydroxythiourea, and N-hydroxysilaurea, their anions and protonated forms. The geometries of N-hydroxyurea, N-hydroxythiourea, and N-hydroxysilaurea, their anions and cations were optimized at the Becke3LYP/CBSB7 level of theory. For all compounds studied, the amidic form is computed to be substantially more stable than the iminolic tautomer. N-Hydroxyurea and its thio and sila derivatives are computed to behave as Nacids in the gas phase. These compounds are in gas-phase weak acids with a calculated acidity of about 1425 to 1355 kJ-mol^–1. Basicities increase in the order: N-hydroxyurea < N-hydroxythiourea < N-hydroxysilaurea. The most stable protonated structures are represented by several isomers with almost equal stability. Thus, in the N-hydroxyurea, N-hydroxythiourea, and N-hydroxysilaurea, both protonation at the double bonded (C=O, C=S and Si=O) oxygen and sulfur atoms, as well as the protonation at the N(H)OH nitrogen basic center is equally probable. The experimental pK _a value (10.6) of N-hydroxyurea and the computed value (9.7) for its monohydrated complex with the specifically hydrogen-bonded water molecule to the ionizable OH group are in a good agreement. The experimental partition coefficient of N-hydroxyurea is best reproduced by the Alog P_s method. The formation of nitroxide radical in the reaction of N-hydroxyurea and its sulfur and silicon substituted derivatives with the phenol radical is an exothermic process. Thus, the \bondN(H)OH moiety of these compounds may quench the structurally related tyrosyl radicals in the active site of ribonucleotide reductase.     

Electronic structure,geometry, and stability of organic cations,dications, and donor-acceptor complexes

Geometric, electronic, and energy characteristics of the complexes formed in the CF₄ ·nAIF₃ (n = I or 2) and CBr₄ ·nAIBr₃ (n = 1, 2, or 4) systems have been determined by the semiempirical AM I method. Besides the donor-acceptor complexes, the CBr₃ ⁺...AIBr₄ ^–, CBr₃ ⁺...Al₂Br₇ ^–, CBr2²⁺...(AlBr₄ ^–)₂, and CBr₂ ²⁺...(Al₂Br₇ ^–)₂ ionic complexes can be formed in the CBr₄ ·nAlBr₃ systems. In the cations and dications of polyhalomethanes (when Hal = Cl, Br, or l) in both the free and bound (included in ionic complexes) states, carbon atoms carry negative charges, the C-Hal bonds are substantially shortened, and the positive charges are located on one-coordinate halogen atoms. These cations and dications can be considered as halenium ions that differ from halenium salts with dicoordinate halogen atoms. In the cationic and dicationic complexes of the CBr₄ ·nAlBr₃ systems, the maximum positive charges on the Br atoms are 0.39 and 0.94, respectively. Fluorine-containing cations and dications have structures similar to those of carbenium ions, whereas in the CF₄ ·nAIF₃ systems (n = l or 2), only donor-acceptor complexes are formed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 3, pp. 554–560, March, 1996.     

The Separation of Mo,Ti, In,and Ga by Di-n-butylphosphate and Tri-n-butylphosphate,and Its Mechanism

Summary Data are given for the possibility of extracting molybdenum, titanium, indium and gallium with di-n-butyl phosphate dissolved in carbon tetrachloride, at various concentrations of acid. The extraction of peroxymolybdate and normal molybdate from hydrochloric and sulphuric acid with tri-n-butylphosphate was investigated. The extraction maxima of indium and gallium occur at p_H's corresponding to the existence of their hydroxides.A specific method for the separation of molybdenum with di-n-butyl phosphate and for its micro-determination with morin are described.From the infrared spectra it is evident that with molybdenum, only complexes in which [Mo]/[HDBP]=1/4 can be formed. The hexavalent Mo is present as MoO₂ ²⁺ in the complex extracted, (MoO₂) (DBP)₂· 2 HDBP. It is probable that only Ti(DBP)₄ can exist, and no adduct of Ti(DBP)₄ and (HDBP)₂ can form. With gallium and indium, complexes of the type Me(OH)_(3–n)· (DBP) _n can be extracted.

---

Zusammenfassung Die Möglichkeit, Molybdän, Titan, Indium und Gallium mit Lösungen von Di-n-butylphosphat in Tetrachlorkohlenstoff bei verschiedenen Säurekonzentrationen zu extrahieren, wurde experimentell nachgewiesen. Die Extraktion von Peroxymolybdat und normalem Molybdat aus Salzsäure und Schwefelsäure mit Tri-n-butylphosphat wurde untersucht. Die maximale Extraktion von Indium und Gallium gelingt bei p_H-Werten, bei denen sie als Hydroxide vorliegen.Eine spezifische Methode zur Abtrennung von Molybdän mit Di-n-butylphosphat und zur Mikrobestimmung mit Morin wurde beschrieben. Aus IR-Spektren ergibt sich, daß mit Molybdän nur Komplexe gebildet werden, in denen [Mo]/[HDBP]=1/4. Sechswertiges Mo liegt in dem extrahierten Komplex als MoO₂ ²⁺ vor; dessen Zusammensetzung entspricht der Formel (MoO₂)(DBP)₂ · 2 HDBP. Es ist wahrscheinlich, daß nur Ti(DBP)₄ gebildet werden kann, nicht aber ein Addukt aus Ti(DBP)₄ und (HDBP)₂. Mit Gallium und Indium lassen sich Komplexe vom Typus Me(OH)_(3–n)·(DBP) _n extrahieren.

---

Résumé On communique les données concernant la possibilité d'extraire le molybdène, le titane, l'indium et le gallium par le phosphate den-dibutyle dissous dans le tétrachlorure de carbone, pour différentes concentrations en acide. On a étudié l'extraction du peroxymolybdate et du molybdate normal par le phosphate den-tributyle dans l'acide chlorhydrique et sulfurique. L'extraction de l'indium et du gallium s'effectue avec une valeur maximale au p_H correspondant au domaine d'existence de leurs hydroxydes.On décrit une méthode spécifique pour la séparation du molybdène par le phosphate den-dibutyle et pour son microdosage par le morin. Les spectres infrarouges mettent en évidence que, seuls, les complexes où [Mo]/[HDBP]=1/4 peuvent se former avec le molybdène. Le molybdène hexavalent se trouve sous forme de MoO₂ ²⁺ dans le complexe qui est extrait, (MoO₂)(DBP)₂· 2 HDBP. Il est probable que seul Ti(DBP)₄ peut exister, et qu'il ne peut pas se former de produits d'addition de Ti(DBP)₄ et (HDBP)₂. On peut extraire des complexes de type Me(OH)in(3–n) · (DBP)(inn) avec le gallium et l'indium.

---

---

This paper was presented at the Symposium on Analytical Chemistry held in Graz, 29th September–1st October 1965.     

The Synthesis of Novel S-, S,S-, S,S,S-, and N,S-Substituted Nitrodienes from Polyhalonitrodienes and Thiols

Abstract

The novel S-, S,S-, and S,S,S-substituted nitrobutadienes were synthesized from the reactions of 2-nitrobutadiene compounds with some thiols. The new N,S-substituted nitrobutadienes were obtained from the reaction of the mono-thiosubstituted butadienes with morpholine, thiomorpholine, homopiperazine, and piperazine derivatives. The structures of new compounds were determined by spectroscopic techniques.

GRAPHICAL ABSTRACT      

基于多羧酸烟酸配体的镝、钬、铒和铥配合物的合成及荧光、磁学性质的表征

以5-(4-羧基苯氧基)烟酸配体(H₂cpna)和稀土金属离子Dy³⁺、Ho³⁺、Er³⁺和Tm³⁺为原料,采用水热法合成了4种稀土金属配合物[M(Hcpna)(cpna)(H₂O)₃]_n,其中M=Dy(1)、Ho (2)、Er (3)、Tm (4)。单晶X射线衍射分析表明配合物1、2、3和4为同构配合物,均为一维链状结构。通过红外、元素分析以及粉末X射线衍射对所得配合物进行了表征,同时对配合物的荧光和磁学性质开展了研究。荧光测试结果表明,配合物1～4的荧光强度均低于配体H2cpna的荧光强度。在2～300 K温度范围内1 kOe直流电场下测试了配合物1～4的磁性,结果表明配合物1、2、3和4的χ_mT值分别为14.04、14.15、11.08和6.83 cm³·mol^-1·K,与文献理论值相符合。     

Synthesis and Antibacterial and Antifungal Properties of Novel S-, N-, N,S-, and S,O-Substituted 1,4-Naphthoquinone Derivatives

Abstract

A novel series of substituted 1,4-naphthoquinone derivatives were synthesized and evaluated for their antibacterial and antifungal activity. The structures of the novel products were characterized by spectroscopic methods. Among the tested compounds, 2,2′,3,3′-alkoxy substituted naphthoquinones, S,O-substituted naphthoquinone, and N,S-substituted naphthoquinone derivatives are the most potent antifungals against C. tenuis. 2,3-Thio-2′,3′-alkoxy substituted naphthoquinones are the most effective antifungal compounds against A. niger.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Synthesis,Characterization, and Crystal Structures of Cu,Ag, and Pd Dinitramide Salts

The literature known, but not fully characterized, silver dinitramide transfer reagents AgN(NO₂)₂ ( 1 ), [Ag(NCCH₃)][N(NO₂)₂] ( 2 ), and [Ag(py)₂][N(NO₂)₂] ( 3 ) have been investigated by ¹⁰⁹Ag, ¹⁴N NMR and vibrational spectroscopy (IR, Raman). In addition, the poorly understood [Cu(NH₃)₄][N(NO₂)₂)]₂ ( 4 ) and [Pd(NH₃)₄][N(NO₂)₂]₂, ( 5 ) have also been prepared and characterized by ¹⁴N NMR and vibrational spectroscopy (IR, Raman). The structures of 2 — 5 have also been determined by X‐ray diffraction.     

Generation,low-temperature stabilization,structure, and reactivity of intermediates with low-coordinated carbon,silicon, and germanium atoms

The mechanisms of thermal and photochemical transformations of organic and organometallic compounds which pass through formation of different reactive intermediates were investigated by low-temperature matrix IR spectroscopy. Low-temperature matrix stabilization of the intermediates, the primary products of these reactions, was conducted at 10–15 K. The spectral and structural parameters of the free radicals (CCl₃, CCl₂Br, CClBr₂, CH₂CH=CH₂, CF₂CF=CF₂, CH₂-CCH, CH₂CN, CH₂Ph, CF₂C₆F₅), halocarbenes and their silicon and germanium analogs, and unstable molecules with double-bond silicon and germanium atoms were obtained as a result.The article is based on a plenary report to the 10th IUPAC Conference on Physical-Organic Chemistry (Haifa, Israel, August, 1990) [1] and partially includes data from Low-Temperature Matrix Stabilization and IR Spectroscopic Study of Free Radicals by O. M. Nefedov, A. K. Mal'tsev, and V. A. Korolev, awarded the N. N. Semenov Prize, Academy of Sciences of the USSR, Moscow, for 1991.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2425–2442, November, 1991.We would like to thank V. A. Korolev for assisting in writing this article.     

Densities,viscosities, refractive indices,and surface tensions for binary and ternary mixtures of 2-propanol,tetrahydropyran, and 2,2,4-trimethylpentane

Densities, viscosities, refractive indices, and surface tensions of the ternary system (2-propanol + tetrahydropyran + 2,2,4-trimethylpentane) at T = 303.15 K and its constituent binary systems (2-propanol + tetrahydropyran, 2-propanol + 2,2,4-trimethylpentane, and tetrahydropyran + 2,2,4-trimethylpentane) at T = (293.15, 303.15, 313.15, and 323.15) K were measured at atmospheric pressure. Densities were determined using a vibrating-tube densimeter. Viscosities were measured with an automatic microviscometer based on the rolling-ball principle. Refractive indexes were measured using a digital Abbe-type refractometer. Surface tensions were determined by the Wilhelmy-plate method. From these data, excess molar volumes, deviations in viscosity, deviations in refractive index, and deviations in surface tension were calculated. The results for the binary and ternary systems were fitted to the Redlich–Kister equation and the variable-degree polynomials in terms of compositions, respectively. The experimental and calculated quantities are used to study the nature of mixing behaviour between mixture components.     

Syntheses and Crystal Structures of LaRhMg,CeRhMg, PrRhMg,and NdRhMg

New intermetallic rare earth compounds LaRhMg, CeRhMg, PrRhMg, and NdRhMg were prepared by reaction of the elements in sealed tantalum tubes in a high‐frequency furnace. The compounds were investigated by X‐ray diffraction both on powders and single crystals. LaRhMg crystallizes with the LaNiAl type structure, space group Pnma, Z = 8, a = 760.1(2), b = 419.92(8), c = 1702.6(2) pm, wR2 = 0.0482, 740 F² values and 38 variable parameters. The cerium compound adopts the ZrNiAl structure: P6¯2m, Z = 3, a = 752.3(1), c = 417.6(1) pm, wR2 = 0.0497, 250 F²2 values and 17 variable parameters. PrRhMg and NdRhMg crystallize with the TiNiSi type: Pnma, Z = 4, a = 721.62(7), b = 415.98(4), c = 869.47(8) pm, wR2 = 0.1864, 440 F² values, 20 variables for PrRhMg and a = 720.6(1), b = 417.6(1), c = 868.8(1) pm, wR2 = 0.0779, 425 F² values, 22 variables for NdRhMg. Refinements of the occupancy parameters revealed mixed Mg/Rh occupancy for the magnesium sites of the cerium and the neodymium compound leading to the compositions CeRh_1.262(8)Mg_0.738(8) and NdRh_1.114(9)Mg_0.886(9) for the investigated single crystals. From a geometrical point of view, the four crystal structures are built up from different rhodium centered trigonal prisms. The rhodium and magnesium atoms form three‐dimensional [RhMg] networks in which the rare earth metal atoms are located in different types of channels. The networks show Rh—Mg and Mg—Mg bonding.     

Polar-Functionalized,Crosslinkable, Self-Healing,and Photoresponsive Polyolefins

The nonpolar nature of polyolefins is one of their biggest limitations. Now, an efficient route to generate polar-functionalized, crosslinkable, self-healing, photoresponsive polyolefins with thermoplastic, elastomeric, and thermosetting properties is reported. Tunable amounts of carboxylic acid and a cyclic comonomer are installed onto polyolefins by palladium-catalyzed terpolymerization reactions. The incorporated carboxylic acid unit can alter the surface properties of polyolefins. The subsequently introduced Fe³⁺/citric acid combination induces dynamic crosslinking and enables self-healing. Under UV light irradiation, citric acid reduces Fe³⁺ to Fe²⁺ and decreases the crosslinking density. The Fe²⁺ moiety can be easily oxidized back to Fe³⁺, making the process reversible at the expense of citric acid. The incorporated cyclic comonomer modulates the crystallinity of polyolefins, provides elastic properties, and installs carbon–carbon double bonds for sulfur-induced vulcanization.     

Structure and properties of HOO,HOS, HSO,HSS, FSO,FOS and FSS

High quality SCF-MO calculations are reported for the title molecules, including geometry optimization. One-electron properties are presented and discussed, and relative stabilities of (HOS, HSO) and (FOS, FSO) compared. Little experimental geometric data are available at present, but the calculated and experimental geometries of HO₂ agree well.     

Use,analysis, and regulation of pesticides in natural extracts,essential oils,concretes, and absolutes

Natural extracts used by the fragrance and cosmetics industries, namely essential oils, concretes, resinoids, and absolutes, are produced from natural raw materials. These are often cultivated by use of monoculture techniques that involve the use of different classes of xenobiotica, including pesticides. Because of these pesticides’ potential effect on public health and the environment, laws regarding permitted residual levels of pesticides used in cultivation of raw materials for fragrance and cosmetic products are expected to become stricter. The purpose of this review is to present and classify pesticides commonly used in the cultivation of these natural raw materials. We will summarize the most recent regulations, and discuss publications on detection of pesticides via chemical analysis of raw natural extracts. Advances in analytical chemistry for identification and quantification of pesticides will be presented, including both sample preparation and modern separation and detection techniques, and examples of the identification and quantification of individual pesticides present in natural extracts, for example essential oils, will be provided.