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A biomimetic iodofunctionalization of aromatic and heteroaromatic compounds has been developed using NaI as a source of iodine and 30% H2O2 as a mild oxidant, as well as SeCl4 as a commercially available catalyst in water without a co-solvent. The method affords iodinated compounds in isolated yields of 37 to 99%. The catalytic system has potential for the bromination of aromatic substrates.

Oxo- and thio-substituted quinazolines are promising biologically active objects. A special place in a number of quinazolines is occupied by its condensed analogues, namely thiazoloquinazolines, which exhibit antioxidant, antimicrobial and antitumor activity. An effective method for the synthesis of condensed quinazoline derivatives is electrophilic intramolecular cyclization of its unsaturated derivatives. The usage of pharmacoformic chalcogen-containing electrophiles in these reactions has been insufficiently studied. Organochalcogen-containing heterocyclic compounds are the promising biologically active substances with different pharmacological action. Therefore, the study of reactions of electrophilic intramolecular cyclization of N(3)-alkenyl derivatives of 2-thioxo-2,3-dihydroquinazolin-4(1H)-one under the action of chalcogen tetrahalides is an urgent task. N (3)-alkenyl derivatives of 2,3-dihydroquinazolin-4(1H)-one were used as the object of study. It was found that the interaction of tellurium tetrabromide with N(3)-alkenyl-2-thioxoquinazolin-4-ones in glacial acetic acid leads to linear hydrobromides of 2-[(tribromotelluro) methyl]-2,3-dihydro-5H-[1,3]thiazolo[2,3-b]quinazolin-5-one. In the reaction with N(3)-methallyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-one, individual tellurium tetrachloride was used, which was obtained by passing chlorine over the tellurium. It is proved that halotellurium-induced cyclization of N-methallyl quinazolone with tellurium tetrachloride occurs regioselectively with the formation of 2-methyl-2-[(trichlorotelluro)methyl]-2,3-dihydro-5H- [1,3]thiazolo[2,3-b]quinazoline-5-one hydrochloride of linear structure. In order to study the influence of the nature of chalcogen in the electrophilic reagent on the regiochemistry of cyclization in the reaction with N(3)-methallyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-one, obtained in situ selenium tetrachloride was used. The selenochlorination reaction of N(3)-methallyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-one in chloroform gave a linear hydrochloride of 2-methyl-2-[(trichloroseleno)methyl]-2,3-dihydro-5H-[1,3]thiazolo[2,3-b]quinazolin-5-one. Thus, the regiochemistry of electrophilic intramolecular cyclization of N(3)-alkenyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-ones by chalcogentetrahalides was investigated and it was proved that the annulationof the thiazoline cycle occurs with the formation of bioperspective bundles of tricyclic heterocycles of linear constitution independently from nature and origin of electrophilic reagent.

In recent years, researches on selenium nanoparticle have gained more attention due to its important role in many physiological processes. Generally, selenium nanoparticle has a high level of absorption in regular supplementation comparative to selenium. Therefore it is all-important to develop new techniques to elevate the transportation of selenium compounds (selenoproteins, selenoenzymes, etc.) by increasing their bioavailability, bioactivity, and controlled release. SeNPs have special attention regarding their application as food additives and therapeutic agents. Selenium nanoparticle has biomedical and pharmaceutical uses due to its antioxidant, antimicrobial, antidiabetic, and anticancer effects. Selenium nanoparticle is also used to antagonize the toxic effect of chemical and heavy metals. SeNPs are beneficial for the treatment of water and soil contaminated with metals and heavy metals as it has adsorption capability. Selenium nanoparticle is synthesized by the bioreduction of selenium species (sodium selenate, sodium selenite, selenium dioxide, and selenium tetrachloride, etc.) by using bacteria, fungi, plant, and plant extracts, which have given hope for the bioremediation of selenium contaminated water and soils. This article reviews the procedure of selenium nanoparticle synthesis (physical, chemical and biological methods), characterization (UV-vis spectroscopy, transmission electron microscopy, Scanning electron microscopy, electron dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform-infrared spectroscopy, etc.), with the emphasis on its role and application in health and environment.

This paper describes a simple and reproducible solution phase synthesis approach for selenium nanoparticles by reducing selenium tetrachloride in the presence of ascorbic acid. An optimization study with poly (sodium 4-styrenesulfonate) produced stable and spherical narrowly size distributed nanoparticles (46 nm) which are considered highly monodisperse. The presence of selenium nanoparticles was confirmed by UV-visible spectroscopy for surface plasmon resonance (262 nm), elemental dispersive spectroscopy (11 KeV and 12.5 KeV) and size ranges characterized by dynamic light scattering (PDI = 0.04, size range of optimized nanoparticles = 35 nm to 75 nm), and visualized using scanning and transmission electron microscopy.

Herein, selenium (Se) products were successfully synthesized via four different synthesis routes, co-precipitation, hydrothermal, microwave and sonochemical routes, involving selenium tetrachloride as a selenium source and hydrazine, potassium borohydride, and thioglycolic acid (TGA) as reducing reagents. TGA can be easily oxidized to the corresponding disulfide [SCH2CO2H]2, which can reduce SeCl4 to Se. To our knowledge, it is the first time that TGA was used as reducing agent for the synthesis of Se nanostructures. The obtained Se was characterized by XRD, SEM, EDS, and DRS. Furthermore, the effects of the reducing agent as well as solvent, NaOH and type of preparation method on the morphology and particle size of the products were investigated. Selenium thin film was deposited on the FTO–TiO2 by Dr-blading technique and it was utilized into solar cell and measured open circuit voltage (Voc), short circuit current (Jsc), and fill factor (FF). The studies showed that preparation method play crucial role on particles morphology and size. Accordingly various efficiencies of obtained nanostructures will be achieved for solar cell applications.

The binary freezing-point diagrams of SeCl4AlCl3 and TeCl4AlCl3 were determined. Both systems show a dissociating compound in a molecular ratio 1: 1 with melting points of 163.8° C resp. 149.3° C. In the case of the binary system SeCl4AlCl3 only one half of the system, with AlCl3 in excess, could be determined because of the decomposition of SeCl4 at higher temperatures. The compound TeCl4 · AlCl3 could be distilled in high-vacuum without decomposition. An approximate value for the heat of fusion of both addition compounds was calculated.

Low molecular weight seleno-organic compounds exhibit glutathione peroxidase (GPx)-like activity; the well-known compound ebselen is being used in clinical trials as a stroke medication. Here, we describe the facile one-step synthesis of novel 5-selenized salicylic acid derivatives using selenium tetrachloride. The products were analyzed by spectroscopic studies including (77)Se-NMR and some were subjected to X-ray structure determination. Several products were identified as selective inhibitors of the pro-inflammatory 5-lipoxygenase (LOX) but had little effect on the catalytic activity of 12/15-LOX, which has been implicated in the synthesis of anti-inflammatory mediators. Such isoform-specificity (specificity coefficient120) has not been reported before for any seleno-organic compound. In addition, synthesis products exhibited GPx-like activity, which was higher than that of ebselen for some derivatives.

Electrophilic reactions of sulfur dichloride with unsaturated systems underlie one of the most general methods for the synthesis of bis(2-chloroalkyl) sulfides [1]. Reactions of analogous unsaturated compounds with selenium tetrachloride yield the corresponding bis-adducts containing a four-coordinate selenium atom (>SeCl2) [2]. In recent years we performed systematic studies on reactions of SeCl2 with alkenes and their oxygenand sulfur-containing derivatives [3, 4]. Reactions with chlorinated ethylenes, such as chloroethene, 1,1and 1,2-dichloroethenes, and trichloroethene were reported only for SCl2, and they required the presence of Lewis acids as catalyst [5]. Garratt et al. [6] showed that SeCl4 failed to react with 1,2-dichloroethene in the presence of AlCl3 as catalyst. Nevertheless, we succeeded in adding SeCl2 to bis(2-chlorovinyl) selenide (a selenium-containing derivative of 1,2-dichloroethene) in the absence of a catalyst [7]. Sulfur and selenium dichlorides are known to act as chlorinating agents toward alkylsulfanyl derivatives of polychloroethenes, e.g., alkyl 2,2-dichlorovinyl sulfides [8].

The S-Se-N-based heterocycle benzo[2,1-c:3,4-c']bis(1,2,3-thiaselenazole) (BSe) can be prepared by the condensation of 1,4-diaminobenzene-2,3-dithiol with selenium tetrachloride. Crystals of this compound are not isomorphous with the related benzo[2,1-c:3,4-c']bis(1,2,3-dithiazole) (BT); a structure is adopted that allows for more extensive intermolecular Se- - -Se contacts. Electro-oxidation of BSe in the presence of [n-Bu4N][ClO4] affords metallic green needles of the charge transfer salt [BSe]3[ClO4]2, which exhibit a pressed pellet conductivity sigma(RT) = 10(-1) S cm(-1). The crystal structure of [BSe]3[ClO4]2 consists of slipped pi-stacks based on the triple-decker closed shell [BSe]3(2+) building block. The packing is analogous to that found for the charge transfer salt [BT]3[FSO3]2, for which sigma(RT) = 10(-2) S cm(-1). Extended Hückel band structure calculations on these two (sulfur- and selenium-based) 3:2 salts reveal more extensive intermolecular interactions in the selenium compound. As a result, the latter has a more two-dimensional electronic structure. Crystal data for Se2S2N2C6H2, a = 4.103(2) A, b = 12.159(2) A, c = 16.171(2) A, orthorhombic, Pbnm, Z = 4. Crystal data for Se6S6N6C18H6Cl2O4, a =17.00(1) A, b = 18.36(1) A, c = 10.679(4) A, 110.27(3), monoclinic, C2/c, Z = 4.

The electrophilic additiob of sulfur dichloride and selenium tetrachloride to diallyldimethylsilane proceeds strictly according Markownikoff rule and results in the formation of previously unknown saturated siliconcontaining heterocycles, 5,5-dimethyl-3,7-dichloro-1,5-thiasilacyclooctane and 5,5-dimethyl-1,1,3,7-tetrachloro-1,5-selena(IV)silacyclooctane. The structure of heterocycles obtained was confi rmed by 1H, 13C NMR spectra, in the case of selenium-containing heterocycle, by 77Se NMR spectrum, among them the 2D HMBC spectrum.

Selenium tetrachloride (SeCl4) has been intercalated from the gas phase in the presence of chlorine gas into highly orientated pyrolytic graphite. A mixture of second- and third-stage SeCl4 graphite intercalation compounds was obtained. X-ray diffraction measurements presented evidence that the b-axis of SeCl4 is orientated perpendicular to the basal plane of the graphite. X-ray diffraction data gave evidence that SeCl4 forms monolayers inside the host lattice. A selected-area electron diffraction study of the in-plane lattice showed (h0l) reflections of SeCl4. The axis of the guest is commensurate with the a-axis of graphite. The lattice parameters for the intercalated species are nearly identical to those of pristine SeCl4.

Die Titelverbindungen wurden durch Reaktionen von Selen und Selentetrachlorid mit PPh4Cl, NEt4Cl, NMe3PhCl oder (K-18-Krone-6)Cl in Dichlormethan oder Acetonitril hergestellt. (PPh4)2Se3Cl8 · CH2Cl2 entstand auch aus GeSe, PPh4Cl und Chlor in Acetonitril. Die 77Se-NMR-Spektren der Losungen zeigen das Vorliegen von dynamischen Gleichgewichten, bei denen je nach Zusammensetzung vor allem die Spezies SeCl2, SeCl4, Se2Cl2, SeCl62–, Se2Cl62– und/oder Se2Cl102– vorherrschen. Aus Losungen von AsCl3 und (PPh4)2Se4 in Acetonitril wurde (PPh4)2Se2Cl6 durch Chlorierung mit Cl2 oder PPh4AsCl6 erhalten, bei Chlorierung mit SOCl2 war das Produkt (PPh4)2As2Se4Cl12. Nach den Kristallstrukturanalysen haben die Ionen SeCl62–, Se2Cl9– und Se2Cl102– die bekannten Strukturen mit oktaedrischer Koordination der Se-Atome. Das Se3Cl82–-Ion ist wie das Se3Br82–-Ion aufgebaut, d. h. drei SeCl2-Molekule, die uber zwei Cl–-Ionen assoziiert sind. (PPh4)2Se4Cl12 · CH2Cl2 ist isotyp zum gleichartigen Bromoselenat und enthalt Anionen, in denen drei SeCl2-Molekule an ein SeCl62–-Ion angelagert sind, wobei eine eigenartige Se–Se-Wechselwirkung auftritt. Chloroselenates with Di- and Tetravalent Selenium: 77Se-NMR-Spectra, Syntheses, and Crystal Structures of (PPh4)2SeCl6 · 2 CH2Cl2, (NMe3Ph)2SeCl6, (K-18-crown-6)2SeCl6 · 2 CH3CN, PPh4Se2Cl9, (NEt4)2Se2Cl10, (PPh4)2Se3Cl8 · CH2Cl2, and (PPh4)2Se4Cl12 · CH2Cl2 The title compounds were obtained from reactions of selenium and selenium tetrachloride with PPh4Cl, NEt4Cl, NMe3PhCl, or (K-18-crown-6)Cl in dichloromethane or acetonitrile. (PPh4)2Se3Cl8 · CH2Cl2 was also formed from GeSe, PPh4Cl and chlorine in acetonitrile. The 77Se-NMR spectra of the solutions show the presence of dynamical equilibria which, depending on composition, mainly contain SeCl2, SeCl4, Se2Cl2, SeCl62–, Se2Cl62–, and/or Se2Cl102–. Solutions of AsCl3 and (PPh4)2Se4 in acetonitrile upon chlorination with Cl2 or PPh4AsCl6 yielded (PPh4)2Se2Cl6, while (PPh4)2As2Se4Cl12 was the product after chlorination with SOCl2. According to the X-ray crystal structure analyses the ions SeCl62–, Se2Cl9–, and Se2Cl102– have the known structures with octahedral coordination of the Se atoms. The structure of the Se3Cl82– ion corresponds to that of Se3Br82– consisting of three SeCl2 molecules associated via two Cl– ions. (PPh4)2Se4Cl12 · CH2Cl2 is isotypic with the corresponding bromoselenate and contains anions in which three SeCl2 molecules are attached to a SeCl62– ion; there is a peculiar Se–Se interaction.

The condensation of diaminobenzenedithiol with sulfur monochloride leads to the chloride salt of the radical cation of 3,6-dichlorobenzo(1,2-d:4,5-d')bis(1,2,3-dithiazole), dichloro-(BB-123-DTA)(Cl), which can be reduced to neutral dichloro-(BB-123-DTA) with triphenylantimony. A similar condensation with selenium tetrachloride leads, upon reduction, to the corresponding bis(1,2,3-thiaselenazole) dichloro-(BB-123-TSA). The crystal and molecular structures of both compounds have been determined by X-ray diffraction. Both compounds, which are formally antiaromatic 16﷿-systems, exhibit internal bond lengths consistent with a quinoid formulation. The radical cations of both rings have been characterized by ESR spectroscopy; for dichloro-(BB-123-DTA) + g ) 2.0114 and aN ) 0.201 mT, while for dichloro-(BB-123-TSA) + g ) 2.021 and aN ) 0.44 mT. Further oxidation of both rings affords the corresponding dications, both of which have been characterized crystallographically as their AlCl 4 - salts. The structural features of these compounds are consistent with those expected for dithiazolylium (or thiaselenazolylium) derivatives. The structure and redox chemistry of the benzo(1,2-d:4,5-d')bis(1,2,3-dithiazole) framework is discussed in the light of the results of ab initio calculations.

Electrophilic reactions of sulfur dichloride with unsaturated systems underlie one of the most general methods for the synthesis of bis(2-chloroalkyl) sulfides [1]. Reactions of analogous unsaturated compounds with selenium tetrachloride yield the corresponding bis-adducts containing a four-coordinate selenium atom (>SeCl2) [2]. In recent years we performed systematic studies on reactions of SeCl2 with alkenes and their oxygenand sulfur-containing derivatives [3, 4]. Reactions with chlorinated ethylenes, such as chloroethene, 1,1and 1,2-dichloroethenes, and trichloroethene were reported only for SCl2, and they required the presence of Lewis acids as catalyst [5]. Garratt et al. [6] showed that SeCl4 failed to react with 1,2-dichloroethene in the presence of AlCl3 as catalyst. Nevertheless, we succeeded in adding SeCl2 to bis(2-chlorovinyl) selenide (a selenium-containing derivative of 1,2-dichloroethene) in the absence of a catalyst [7]. Sulfur and selenium dichlorides are known to act as chlorinating agents toward alkylsulfanyl derivatives of polychloroethenes, e.g., alkyl 2,2-dichlorovinyl sulfides [8].

The electrophilic addition of SCl2 or SeCl4 to diallylsilane (I) proceeds strictly according to the Markovnikoff rule furnishing previously unknown thiasilacyclooctane (II) or selenasilaoctane (III), respectively.

The explosive black solid 3-chloro-1,3,4,2,5-triselenadiazolium chloride, Se 3 N 2 Cl 2 , has been prepared in high yield by three different reactions: (a) from [(Me 3 Si) 2 N] 2 Se and a mixture of SeCl 4 and Se 2 Cl 2 designed to give a Se:Cl ratio of 1:3, (b) from [(Me 3 Si) 2 N] 2 Se and SeOCl 2 in a 1:2 molar ratio, and (c) from Me 3 SiN 3 and Se 2 Cl 2 in a 2:3 molar ratio

Selenium dichloride and dibromide were not isolated as individual substances. It is known that selenium dichloride in solution exists in equilibrium with selenium tetrachloride and Se2Cl2, whereas the equilibrium of selenium dibromide in solution involves Se2Br2 and bromine [1, 2]. We were the first to reveal that freshly prepared selenium dichloride and selenium dibromide can be used in selective synthesis of organic selenides [3, 4]. Reactions of selenium dichloride and dibromide with divinyl chalcogenides and their derivatives opened a synthetic route to new heterocyclic compounds [5–10]. In continuation of our systematic studies on the chemical properties of selenium dihalides [3–10], we examined previously unknown addition of selenium dichloride to divinyl sulfone. It was found that the reaction occurs with high regioselectivity and leads to the formation of a new four-membered heterocyclic compound, 2,4-bis(chloromethyl)-1,3-thiaselenetane 1,1-dioxide (I). The yield of compound I was 85%, calculated on the reacted divinyl sulfone, the conversion of the latter being 58%. sional correlation techniques, as well as by mass spectrometry and elemental analysis. According to the NMR data, compound I was isolated as a mixture of two diastereoisomers at a ratio of 2.5 : 1. 2,4-Bis(chloromethyl)-1,3-thiaselenetane 1,1-dioxide (I). mp 76–77°C. Major diastereoisomer: H NMR spectrum, δ, ppm: 3.91 d.d (2H, CH2Cl, J = 11.8, J = 7.1 Hz), 4.27 d.d (2H, CH2Cl, J = 11.8, J = 7.1 Hz), 5.52 d.d (2H, CHSe, J = 7.1, 7.1 Hz). C NMR spectrum, δC, ppm: 41.39 (CH2Cl), 69.36 (CHSe). Se NMR spectrum: δSe 193 ppm. Minor diastereoisomer: H NMR spectrum, δ, ppm: 3.93 d.d (2H, CH2Cl, J = 11.9, J = 7.7 Hz), 4.31 d.d (2H, CH2Cl, J = 11.9, J = 7.9 Hz), 5.54 d.d (2H, CHSe, J = 7.7, 7.9 Hz). C NMR spectrum, δC, ppm: 41.63 (CH2Cl) , 70.03 (CHSe) . Se NMR spectrum: δSe 200 ppm. Mass spectrum, m/z (Irel, %): 268 (29) [M], 204 (12), 169 (100), 142 (56), 133 (34), 107 (82), 93 (24), 81 (13), 61 (19), 53 (21). Found, %: C 17.69; H 2.21; Cl 26.30. C4H6O2Cl2SSe. Calculated, %: C 17.93; H 2.26; Cl 26.46. The NMR spectra were recorded from solutions in CDCl3 on a Bruker DPX-400 instrument at 400.13 (H, HMDS), 100.61 (C, HMDS), and 76.30 MHz (Se, Me2Se). The mass spectrum (electron impact, 70 eV) was obtained on a Shimadzu GCMS-QP5050A instrument. This study was performed in the framework of the Basic Research Program of the Russian Academy of Sciences (project no. 5.1.8).

The reaction of selenium tetrachloride with the dichlorothiophene diselenolate 3,4-C4Cl2S(SeLi)2 gives triselenole (I) in 38% yield. Purification of I is difficult due to the occurrence of a facile decomposition on attempted dissolution in a variety of solvents.

The cyclocondensation of R 2 PN 2 (SiMe 3 ) 3 (R=Me, Et, Ph) with a mixture of selenium monochloride and selenium tetrachloride that gives a Se:Cl ratio of 1:3 in acetonitrile at 23 o C produces 1,5-Ph 4 P 2 N 4 Se 2 , 2a, in 85% yield by mixtures of 1,5- and 1,3-R 4 P 2 N 4 Se 2 in combined isolated yields of 79% (R=Me) or 96% (R=Et). The heterocycles 1,3-Me 4 P 2 N 4 Se 2 , 4b, and 1,5-Et 4 P 2 N 4 Se 2 , 2c, were separated from these mixtures by fractional crystallization and gel permeation chromatography, respectively.

Selenium dichloride is a promising reagent for organic synthesis. However, prior to our studies [1, 2], it was not used for the preparation of organoselenium compounds. It is known that selenium dichloride in solution exists in equilibrium with selenium tetrachloride and Se2Cl2 [3]. No examples of aromatic electrophilic substitution with participation of selenium dihalides have been reported so far. While continuing our systematic studies on reactions of selenium dihalides [1, 2, 4–10], we examined the reaction of selenium dichloride with methoxybenzene. The reaction occurred as aromatic replacement of hydrogen by the electrophile Se and afforded bis(4-methoxyphenyl) selenide (I) in high yield (91%). Thus selenium dichloride may be used as source of electrophilic Se species in aromatic electrophilic substitution reactions. The possibility of using selenium dihalides for performing analogous reactions with other aromatic systems is now under study. Bis(4-methoxyphenyl) selenide (I). mp 54–55°C; published data [11]: mp 54°C. H NMR spectrum, δ, ppm: 7.28 d (4H, CH, J = 7.4 Hz), 6.69 d (4H, CH, J = 7.4 Hz), 3.72 s (6H, CH3O). C NMR spectrum, δC, ppm: 158.85 (C), 135.24 (C), 122.04 (C), 114.53 (C), 54.49 (CH3O). Mass spectrum, m/z (Irel, %): 294 [M] (75), 214 (100), 199 (96), 187 (14), 171 (28), 144 (12), 128 (25), 107 (77), 92 (13), 77 (14), 63 (47), 39 (18). The H and C NMR spectra were recorded on a Bruker DPX-400 spectrometer at 400.13 and 100.61 MHz, respectively, from a solution in carbon tetrachloride; the chemical shifts were determined relative to hexamethyldisiloxane. The mass spectrum (electron impact, 70 eV) was obtained on a Shimadzu GCMS-QP5050A instrument.

Selenium tetrachloride reacts with an excess of trimethylaluminum in the presence of aromatic solvents to afford a non-stoichiometric organoaluminum-selenonium based inclusion compound of the formula [(CH3)3Se][ClAl(CH3)2(Cl)Al(CH3)3]·(aromatic solvent) n . The cation of the parent compound of the inclusion complex results from the alkylation of SeCl4 producing the (CH3)3Se+ selenonium ion while the anion consists of a dimethylaluminum chloride unit and a trimethylaluminum unit bridged by a chlorine atom. This liquid inclusion complex, liquid clathrate, can accommodate 8.5 benzene molecules or 8.3 guest toluene molecules per anionic moiety.

The chemical vapour transport (CVT) of NiTiO3 with SeCl4 is reported. In addition to small NiTiO3 crystals a more or less quantity of solid NiCl2 is deposited in the deposition zone. At higher temperature gradients the solid which is deposited besides NiCl2 is NiO. The transport behaviour is satisfactory explained using two thermodynamical models: the model of connected equilibrium states and the four-stage model. Beim chemischen Transport (CVT) von NiTiO3 mit SeCl4 wird neben kleinen NiTiO3-Kristallen ein Teil des Transportmittels in Form von festem NiCl2 in der Abscheidungszone abgeschieden. Bei groseren Temperaturgradienten wird neben NiCl2 das NiO transportiert. Das Transportverhalten wird sowohl mit dem Modell der gekoppelten Gleichgewichtsraume als auch mit dem Vier-Stufen-Modell befriedigend erklart.

Divinyl sulfide is a multipurpose product in modern organic synthesis [1]; various heterocyclic compounds were obtained on its basis [2]. Earlier, we have studied the reactions of divinyl sulfide with selenium dichloride and dibromide, which, when carried out at room temperature in chloroform, result in 5-halo-2halomethyl-1,3-thiaselenolanes, whereas in CCl4, in 2,6-dihalo-1,4-thiaselenanes [3–6].

Selenium dichloride and dibromide were not isolated as individual substances. It is known that selenium dichloride in solution exists in equilibrium with selenium tetrachloride and Se2Cl2, whereas the equilibrium of selenium dibromide in solution involves Se2Br2 and bromine [1, 2]. We were the first to reveal that freshly prepared selenium dichloride and selenium dibromide can be used in selective synthesis of organic selenides [3, 4]. Reactions of selenium dichloride and dibromide with divinyl chalcogenides and their derivatives opened a synthetic route to new heterocyclic compounds [5–10]. In continuation of our systematic studies on the chemical properties of selenium dihalides [3–10], we examined previously unknown addition of selenium dichloride to divinyl sulfone. It was found that the reaction occurs with high regioselectivity and leads to the formation of a new four-membered heterocyclic compound, 2,4-bis(chloromethyl)-1,3-thiaselenetane 1,1-dioxide (I). The yield of compound I was 85%, calculated on the reacted divinyl sulfone, the conversion of the latter being 58%. sional correlation techniques, as well as by mass spectrometry and elemental analysis. According to the NMR data, compound I was isolated as a mixture of two diastereoisomers at a ratio of 2.5 : 1. 2,4-Bis(chloromethyl)-1,3-thiaselenetane 1,1-dioxide (I). mp 76–77°C. Major diastereoisomer: H NMR spectrum, δ, ppm: 3.91 d.d (2H, CH2Cl, J = 11.8, J = 7.1 Hz), 4.27 d.d (2H, CH2Cl, J = 11.8, J = 7.1 Hz), 5.52 d.d (2H, CHSe, J = 7.1, 7.1 Hz). C NMR spectrum, δC, ppm: 41.39 (CH2Cl), 69.36 (CHSe). Se NMR spectrum: δSe 193 ppm. Minor diastereoisomer: H NMR spectrum, δ, ppm: 3.93 d.d (2H, CH2Cl, J = 11.9, J = 7.7 Hz), 4.31 d.d (2H, CH2Cl, J = 11.9, J = 7.9 Hz), 5.54 d.d (2H, CHSe, J = 7.7, 7.9 Hz). C NMR spectrum, δC, ppm: 41.63 (CH2Cl) , 70.03 (CHSe) . Se NMR spectrum: δSe 200 ppm. Mass spectrum, m/z (Irel, %): 268 (29) [M], 204 (12), 169 (100), 142 (56), 133 (34), 107 (82), 93 (24), 81 (13), 61 (19), 53 (21). Found, %: C 17.69; H 2.21; Cl 26.30. C4H6O2Cl2SSe. Calculated, %: C 17.93; H 2.26; Cl 26.46. The NMR spectra were recorded from solutions in CDCl3 on a Bruker DPX-400 instrument at 400.13 (H, HMDS), 100.61 (C, HMDS), and 76.30 MHz (Se, Me2Se). The mass spectrum (electron impact, 70 eV) was obtained on a Shimadzu GCMS-QP5050A instrument. This study was performed in the framework of the Basic Research Program of the Russian Academy of Sciences (project no. 5.1.8).

Selenium dichloride is a promising reagent for organic synthesis. However, prior to our studies [1, 2], it was not used for the preparation of organoselenium compounds. It is known that selenium dichloride in solution exists in equilibrium with selenium tetrachloride and Se2Cl2 [3]. No examples of aromatic electrophilic substitution with participation of selenium dihalides have been reported so far. While continuing our systematic studies on reactions of selenium dihalides [1, 2, 4–10], we examined the reaction of selenium dichloride with methoxybenzene. The reaction occurred as aromatic replacement of hydrogen by the electrophile Se and afforded bis(4-methoxyphenyl) selenide (I) in high yield (91%). Thus selenium dichloride may be used as source of electrophilic Se species in aromatic electrophilic substitution reactions. The possibility of using selenium dihalides for performing analogous reactions with other aromatic systems is now under study. Bis(4-methoxyphenyl) selenide (I). mp 54–55°C; published data [11]: mp 54°C. H NMR spectrum, δ, ppm: 7.28 d (4H, CH, J = 7.4 Hz), 6.69 d (4H, CH, J = 7.4 Hz), 3.72 s (6H, CH3O). C NMR spectrum, δC, ppm: 158.85 (C), 135.24 (C), 122.04 (C), 114.53 (C), 54.49 (CH3O). Mass spectrum, m/z (Irel, %): 294 [M] (75), 214 (100), 199 (96), 187 (14), 171 (28), 144 (12), 128 (25), 107 (77), 92 (13), 77 (14), 63 (47), 39 (18). The H and C NMR spectra were recorded on a Bruker DPX-400 spectrometer at 400.13 and 100.61 MHz, respectively, from a solution in carbon tetrachloride; the chemical shifts were determined relative to hexamethyldisiloxane. The mass spectrum (electron impact, 70 eV) was obtained on a Shimadzu GCMS-QP5050A instrument.

The reaction of selenium tetrachloride with the dichlorothiophene diselenolate 3,4-C4Cl2S(SeLi)2 gives triselenole (I) in 38% yield. Purification of I is difficult due to the occurrence of a facile decomposition on attempted dissolution in a variety of solvents.

The reactions of several trivalent organometallic aryl compounds with TeCl4 and SeCl4 were investigated. When diphenylboron bromide was treated with an equimolar quantity of tellurium tetrachloride in toluene, the phenyltellurium trihalide C6H5TeBr1.3Cl1.7 was obtained. The presence of the mixed halogens on tellurium can be explained in terms of a Lewis acid-base reaction between the boron and tellurium compounds. The rection of diphenylboron bromide with selenium tetrachloride in toluene, produced mixed triarylselenonium chlorides. The presence of substituted toluene molecules in the product is attributed to the reaction of selenium tetrachloride with toluene in the presence of the Lewis acid, boron trihalide. The reaction of triphenylaluminum with tellurium tetrachloride was found to produce triphenyl telluronium chloride. Both diphenyl-chloroarsine and diphenylchlorophosphine were oxidized from MIII to MV by either selenium or tellurium tetrachloride. The products were isolated as diphenylarsinic acid and diphenylphosphinic acid, respectively.

The title compounds 5 were obtained from the reaction of 3,3′,4,4′-tetramethoxybiphenyl (6) or its 2,2′-dilithio derivative 8 with various chalcogen electrophiles (sulfur dichloride, selenium tetrachloride, selenium oxychloride and tellurium tetrachloride).

Selenium(IV)-dichlorides 1 , readily available by treatment of methyl ketones with phenylselenium trichloride or selenium tetrachloride, were treated in methylene chloride with pyridine to give α-chloroselenides 2 in a Pummerer-like reaction. Sulfuryl chloride chlorination of these materials and repeated pyridine treatment similarly afforded α,α-dichloroselenides 4 .

Selenium tetrachloride(SeCl4) reacts smoothly with alcohols in various nonpolar solvents to give the corresponding alkyl chlorides in 44–97% yield. Similar reaction also proceeds with tellurium tetrachloride (TeCl4), while the treatment of benzyl, 1-phenylethyl, and t-butyl alcohols with TeCl4 in aromatic solvents results in a high yield formation of alkylated aromatics instead of alkyl chlorides. Such Friedel-Crafts aromatic alkylation hardly occurs in the SeCl4 case. The chlorinating species is not chlorine which might be evolved by dissociation of SeCl4 or TeCl4, but the metal chloride itself. The conversion of optically active (R)-(+)-1-phenylethanol to 1-phenylethyl chloride proceeds with nearly complete racemization.

The preventive effect of zinc for the toxic actions of germanium and selenium on bone metabolism was investigated in the femoral diaphysis of weanling rats. Germanium tetrachloride (1.53-30.60 mumol Ge/100 g b.w.) and selenium tetrachloride (1.53-7.65 mumol Se/100 g) was administered orally for 3 days. The doses of 1.53 and 7.65 mumol Ge/100 g caused a significant increase in DNA content although alkaline phosphatase activity was not altered significantly. By the dose of 30.60 mumol Ge/100 g, both alkaline phosphatase activity and DNA content were decreased significantly. Administration of selenium (1.53 and 7.65 mumol/100 g) produced significantly decreases in alkaline phosphatase activity and DNA content. The decreases of the enzyme activity and DNA content caused by administration of germanium (30.60 mumol/100 g) and selenium (7.65 mumol/100 g) were prevented completely by simultaneous injection of zinc sulfate (7.65 mumol Zn/100 g) for 3 days. Administration of zinc also produced appreciable increase in alkaline phosphatase activity and DNA content. The present study indicates that germanium and selenium disturbs bone metabolism in weanling rats, and that this disturbance is reversed by zinc.

Selenium tetrachloride and bromide form SeX 3 + ions whereas selenium monochloride and bromide form Se 4 2+ and SeX 3 + ions, when dissolved in disulphuric acid. In disulphuric acid containing chlorine and bromine, selenium forms SeX 3 + ions, selenium monochloride forms Se 2 Cl 3 + and Se 2 Cl 2 Br + whereas selenium monobromide forms Se 2 Br 3 + , Se 2 X 3 + disproportionates to form SeX 3 + and Se. Similar ions are formed when halogens are added to the yellow solutions of selenium (Se 4 2+ ) ions in disulphuric acid. All attempts to prepare the iodo derivatives of selenium in disulphuric acid have failed.

Raman spectra were obtained for SeCl4 in the solid and for TeCl4 in the solid and the liquid state. Polarization measurements were performed for the stronger Raman lines of liquid TeCl4. The four stronger Raman lines of SeCl4 are very close in frequency to those of pyramidal AsCl3; there is also a close analogy between the frequencies of the stronger Raman lines of TeCl4 (both in the solid and in the liquid state) and those of antimony trichloride. These findings favour the assumption that solid SeCl4 and TeCl4 have to be written as SeCl3+Cl− and TeCl2+Cl− respectively, SeCl3+ being isosteric with AsCl3 and TeCl2+ with SbCl3. Force constant and frequency calculations have been effected for the hypothetical SeCl3+ and TeCl3+ ions. The results support the above assumption.

Durch Reaktion von Tellurtetrachlorid mit Trimethylsilylazid konnten Tellur-trichlorid-azid und Tellur-dichlorid-diazid dargestellt werden. Tellur-trichlorid-azid, das mit Triphenylphosphin unter Stickstoffentwicklung zu (Ph3PNPPh3)2TeCl6 und Te reagiert, ist monomer. Im Unterschied zu Tellurtetrachlorid werden Schwefel- und Selentetrachlorid von Trimethylsilylazid reduziert. Tellurium Trichloride Azide and Tellurium Dichloride Diazide. (Reaction of Trimethylsilyl Azide with Chalkogen Halides) The reaction of tellurium tetrachloride with trimethylsilyl azide leads to the formation of tellurium trichloride azide and tellurium dichloride diazide. The monomeric tellurium trichloride azide reacts with triphenylphosphine under elimination of nitrogen to give (Ph3PNPPh3)2TeCl6 and Te. Unlike tellurium tetrachloride, sulfur tetrachloride and selenium tetrachloride are reduced by trimethylsilyl azide.

The ions Me2SCl+ and MeSCl2+ have been prepared in hydrogen chloride solution from the oxidation of dimethyl sulfide and methanesulfenyl chloride with chlorine, or from methyl sulfur trichloride (MeSCl2+), and characterized as their tetrachloroborates and hexafluorophosphates. Et2SCl+BCl4− and EtSCl2+BCl4− have been prepared analogously. Dimethyl selenium and dimethyl tellurium solutions were oxidized with chlorine to dimethyl selenium dichloride and dimethyl tellurium dichloride.Methanesulfenyl chloride solution was ionized due to the protonation of sulfur, and not to the loss of a chloride ion. Methylchlorosulfonium hexafluorophosphate has been characterized. Methane- and ethane-sulfenyl chloride solutions reacted with boron trichloride giving (RSCl)2BCl3.Sulfur tetrachloride, selenium tetrachloride, and tellurium tetrachloride were sparingly soluble and showed no acidic or basic properties in the solvent. Sulfur monochloride, sulfur dichloride, selenium monochloride, and tellurium dichloride were non-basic in solution.The new compounds, Me2S2.BCl3 and Me2Te.BCl3, have been prepared and characterized.