bluuebunny/crossref_metadata_2025_split huggingface dataset:
Halogenometallate von Übergangselementen mit Kationen stickstoffhaltiger heterocyclischer Basen. I. Die Kristallstrukturen von 1,4‐Dimethylpiperazinium‐tetrachlorocobaltat(II) und ‐zinkat(II), (dmpipzH2)[MIICl4] (M = Co, Zn)
Authors: Feist Michael , Trojanov Sergej , Kemnitz Erhard 
Published: January 2005

AbstractDie Verbindungen (dmpipzH2)[MIICl4] kristallisieren monoklin in der Raumgruppe P21/m mit a = 6,133(1), b = 14,306(1), c = 6,902(1) Å, β = 90,54(2)°, Z = 2 für M = Co und mit a = 6,141(1), b = 14,282(1), c = 6,907(1) Å, β = 90,60(2)°, Z = 2 für M = Zn. In den Strukturen liegen Tetraeder [MCl4]2− und zentrosymmetrische (dmpipzH2)2+‐Kationen in Sesselform vor. Es werden gabelförmige Wasserstoffbrückenbindungen des Typs NH …︁ Cl zu zwei Chloridionen gebildet. Zwei kurze Abstände C …︁ Cl werden als CH …︁ Cl‐Wasserstoffbrückenbindungen gedeutet.
Trifluoroethylene Sultone: Structure and Chemistry
Authors: Braden Dale A. , Gard Gary L. , Oberhammer Heinz 
Published: January 2005

AbstractThe gas phase structure of trifluoroethylene sultone, (1) (3,4,4‐trifluoro‐1,2‐oxathietane‐2,2‐dioxide) was determined by gas electron diffraction, and the four‐membered ring was found to be planar. The following ring parameters (ra distances and ∠α angles with 3σ uncertainties) were derived in the electron diffraction analysis: CO = 1.41 Å (ass.), CC = 1.541(18) Å, SO = 1.652(5) Å, SC = 1.822(8) Å, SCC = 86.2(15)°, CCO = 97.1(28)°, COS = 97.5(21)°, and OSC = 79.1(8)°. New spectral data (IR, NMR) of 1, its acyclic isomer FSO2CFHC(O)F (2), and the related anhydride, FSO2OSO2CFHC(O)F (3), are reported. New esters containing the fluorosulfonyl function, FSO2CFHC(O)OCH2CF3 (4), FSO2CFHC(O)OCH2CH = CH2 (5), and (FSO2CFHC(O)OCH2CHCH2)n (6) have been prepared and characterized.
Mechanistic aspects of the thermal stabilisation of PVC by organotin compounds
Authors: Burley Joseph William 
Published: January 2005

AbstractWhen subjected to heat and mechanical shear PVC decomposes via the elimination of HCl. This process is controlled most efficiently by the use of organotin stabilisers. This review outlines the basic degradation/stabilisation mechanisms which are involved in these processes. The organotin compounds of most commercial significance receive particular attention. Model compound studies which highlight potential stabilisation mechanisms are discussed but emphasis is placed on in‐situ studies which are much more realistic. Finally the phenomenon of synergism is discussed with reference to conventional alkyltin and the more novel estertin compounds.
Applications of fast atom bombardment mass spectrometry (FAB MS) to organometallic and coordination chemistry
Authors: Bruce Michael I , Liddell Michael J 
Published: January 2005

AbstractThis article describes the technique of fast atom bombardment mass spectrometry (FAB MS) and its applications to the analysis of organometallic and coordination complexes. Sections on ion generation and matrices are followed by a Periodic Group‐based review of FAB MS results obtained from Transition Metal and Main Group compounds, organometallic cluster carbonyls and their derivatives, and salts of poly‐oxo‐anions. The literature has been surveyed from 1981 to approximately mid‐1986.
Studies on the phytotoxic effects of some organotin(IV) compounds on the germination of the mung bean seed, Phaseolus aureus
Authors: Balabaskaran S , Tilakavati K , Das V G Kumar 
Published: January 2005

AbstractA selected range of organotin(IV) compounds of formula RxSnX4‐x (x = 2 or 3; R = alkyl, cycloalkyl or aryl), as well as the adducts, (p‐ZC6H4)3SnCl. Ph3PO (Z = H, Me) were examined in vivo for their phytotoxic effects relative to the more powerful s‐triazine herbicides against the mung bean seed, Phaseolus aureus. Phytotoxicity was assessed in terms of changes in (a) weights of primary leaves, (b) weights of cotyledons, (c) seedling heights and (d) root morphology. The triorganotin compounds were more phytotoxic than the diorganotins, and within the R3Sn structural class, inhibitory potency was greater for alkyltins than for aryltins. Decreasing the alkyl chain lengths or placing electrondonating substituents on the aromatic rings increased the phytotoxicity. A significant phytotoxic effect, comparable with that of Ph3SnCl, was manifested by tricyclohexyltin chloride, in marked contrast to the well‐known low phytotoxicity of tricyclohexyltin hydroxide.Using Ph3SnCl as the model compound, it was further demonstrated that the total chlorophyll content decreased with increasing concentration of Ph3SnCl, but the ration of chlorophyll a to chlorophyll b was constant. It was also found that tin uptake in the seedlings was directly proportional to Ph3SnCl test concentrations; the magnesium and iron levels in the treated seedlings, however, were unchanged relative to the control.
The fate of tributyltin toxicants in neoprene‐based elastomeric antifouling coatings: 119mSn Mössbauer, 119Sn NMR and chemical studies
Authors: Allen David W , Brooks John S , Bailey Stephen , Taylor Brian F 
Published: January 2005

AbstractThe fate of a series of tributyltin toxicants on incorporation into cured neoprene elastomers has been studied by 119mSn Mössbauer and 119Sn NMR spectroscopic techniques, together with supporting chemical derivatization techniques. It is shown that all of the toxicants undergo chemical change during the curing process, being converted into tributyltin chloride, together with (in some cases) tributyltin stearate and a small amount of dibutyltin distearate. Possible interactions between the organotin agents and other components of the elastomer, e.g. carbon black filler, and cure accelerators such as tetramethylthiuram disulphide, have also been investigated.
Analysis of tributyltin in estuarine sediments and oyster tissue, Crassostrea virginica
Authors: Rice C D , Espourteille F A , Huggett R J 
Published: January 2005

AbstractAn analytical method to determine tributyltin (TBT) in oyster tissue, Crassostrea virginica, and estuarine sediments is described. Recoveries of TBT from oysters range from 86 to 102% when samples are fortified at concentrations ranging from 22 to 890 μg kg−1 (wet weight); recoveries from sediment range from 92 to 105% for samples fortified from 20 to 500 μg kg−1 (dry weight).Feral oysters and natural sediments were analysed and shown to be contaminated with TBT. Oysters collected near a marina contained concentrations as high as 1.5 mg kg−1 (wet weight).
Silane compounds in hot‐water pipe and cable technology
Authors: Gale G M 
Published: January 2005

AbstractThe problems of technique and equipment used in the crosslinking of polyethylene polymer are discussed. The practice of organosilicon chemistry for crosslinking of polyethylene chains is also considered. The use of a Cavity Transfer Mixer (CTM) for control of silane‐based crosslinking is described and the properties of the resultant polymers are tested. Use of this crosslinking method via the CTM produces polyethylene with improved hot‐water characteristics.
Bis(tributyltin) oxide as a wood preservative: Its chemical nature in timber
Authors: Blunden S J , Hill R 
Published: January 2005

AbstractTributyltin compounds have been used for many years as wood preservatives. This study has provided, for the first time, an explanation for the previously reported dealkylation and/or volatilization of the tributyltin species in, and from, timber. Thus 119Sn NMR studies have shown that, on impregnation into timber, bis(tributyltin) oxide, (Bu3Sn)2O, is rapidly converted to other tributyltin species, Bu3SnOX, and that these subsequently undergo disproportionation to Bu4Sn and Bu2Sn(OX)2 compounds. We have additionally demonstrated that Bu4Sn, so produced, is not persistent in timber and is lost by volatilization. Since the rate of disproportionation of the Bu3SnOX species should be dependent upon the nature of the X group, it should be possible to affect significantly, if not to stop, this process by the use of alternative tributyltin fungicides, e.g. tributyltin methanesulphonate. However, tributyltin fungicides have been used successfully in wood preservation for at least 25 years. Therefore, it must be concluded that, even after disproportionation in timber, in service, sufficient preservative action is retained to prevent decay of wood under the conditions of natural exposure.
Characterization and studies of electroactive properties of an organometallic polymer of iron‐phthalocyanine
Authors: Nalwa Hari S 
Published: January 2005

AbstractAn iron‐phthalocyanine polymer has been characterized by infrared spectroscopy, X‐ray diffraction and Mössbauer spectroscopy. The electrical properties of resistivity, dielectric constant and the thermally stimulated depolarization effect have been investigated in the temperature range 30–240°C. The depolarization of thermoelectret shows two current peaks at about 176°C and 200°C. The unpolarized sample also displays a pyroelectric current on heating, indicating the possibility of ferroelectric polarization. A temperature‐dependent measurement of the dielectric constant exhibits a dielectric maximum around 180°C which is likely due to electret current peaks. The results have been compared with a monomer of iron‐phthalocyanine and interpretations are made in terms of the highly delocalized π‐electron system of the phthalocyanine macrocycle being further extended by polymerization.
Arsenate metabolism in aquatic plants
Authors: Benson A A , Katayama M , Knowles F C 
Published: January 2005

AbstractOf the several types of arsenic metabolic pathways in algae and aquatic higher plants, production of arsenoribosides is predominant and most interesting. Insertion of the ribosyl or adenosyl moiety by transfer from S‐adenosylmethioninine or possibly from adenosylcobalamin is the critical biochemical step which, as yet, has not been experimentally demonstrated. Oceanic or other environmental arsenate (AsO43−), absorbed in the plant's quest for phosphate, is fixed by reaction with ATP to yield the phosphoric arsenic anhydride APAs, a short‐lived but reducible intermediate which is converted to arsenic(III). The Hill Reaction, or thioredoxin reductase, reduces it to an arsine oxide (HAsO) or arsonous acid [HAs(OH)2] depending upon the water content of its environment. This readily diffusible reagent avidly attacks sulfhydryl groups of proteins to produce arsonous thioesters. The Sargassum group of algae appears to process arsenate no further than this. The reduced arsenic may be freed from its sulfur bondage by reaction with 2,3‐dimercaptopropan‐1‐ol (BAL) or dithiothreitol. In experiments with Sargassum fluitans and Sargassum natans no arsenoribosides were observed. Only protein‐bound arsenic was observed. It could be liberated by trituration with dithiothreitol to produce the cyclic arsonous dithioester.Most diatoms, dinoflagellates and macroalgae as well as freshwater higher plants release such protein‐bound arsenic as a result of sequential methylation and adenosylation. Ultimately the products are trialkylarsine oxides, innocuous substances which are slowly or not‐at‐all metabolized by herbivorous animals or bacteria. Fortunately mammals and most animals also excrete the arsenoribosides readily, unchanged. Arsenic metabolism by a cyanobacterium, Phormidium sp., was described by Matsuto et al. (Comp. Biochem. Physiol., 1984, 78c:377) as involving two modes of arsenate fixation, reduction, and excretion. We have extended those experiments with Phormidium persicinum. We have analyzed algae from 2‐ and 7‐day culture in radioarsenate media. The arsenic products included 80% of arsenolipid, similar if not identical to that formed in the brown algae. The water‐soluble products were in low concentration. Insoluble, protein‐bound arsonous thioesters accounted for 8% of the fixed arsenic. The mechanism of arsenic depuration in Phormidium appears to be primarily lipid‐mediated.
A study of dimethyltin(IV)‐L‐cysteinate in aqueous solution
Authors: Silvestri Arturo , Duca Dario , Huber Friedo 
Published: January 2005

AbstractThe in vivo activity of some R2Sn‐L‐cysteinate complexes (R = Me, Et, n‐Bu) against murine P‐388 leukaemia has been tested. Only the Et2Sn(IV) complex showed a marginal positive effect. Trigonal bipyramidal tin environments with two carbon (R) atoms and the sulfur atom in the equatorial plane and oxygen (carboxylate) and nitrogen (NH2) in apical positions have been proposed for the solid compexes (R = Me, Et, n‐Bu, Ph) on the basis of experimental Mössbauer parameters and infrared (IR) data. Aqueous solutions of the Me2SnL‐cysteinate have been studied by IR, 1H NMR and 119Sn Mössbauer spectroscopy (in frozen solution) at different pH values to identify the Me2Sn(IV) species present. At pH > 2 the dimethyltin aquocation is complexed by the ionized sulfhydryl group of L‐cysteine to form a five‐coordinated species. With increasing pH values, NH3+ is deprotonated and a chelate is proposed with both the sulfhydryl and the amino group bonded to tin, one water molecule or (at still higher pH values) one hydroxyl ion occupying the fifth coordination site of a trigonal bipyramid around tin. Finally at pH > 10 the NH2 group is substituted by a hydroxyl ion.
Organometallics in the nearshore marine environment of Australia
Authors: Maher W A , Batley G E 
Published: January 2005

AbstractThis review draws together published information on the occurrence and biogeochemical cycling of selenium, arsenic and tin in the nearshore marine environment of Australia. The selenium content of marine organisms is well documented but little information is available on the selenium content of waters and sediments. The speciation of selenium in organisms, water and sediments is unknown although it appears that selenium is associated with proteins. The occurrence and speciation of arsenic in marine organisms has been extensively studied, with arsonobetaine being isolated as the probable end‐product of arsenic metabolism in marine food chains. However, organisms can produce other organoarsenic compounds, e.g. trimethylarsine oxide, which may be metabolized to toxic end‐products. Little is known about the occurrence and speciation of arsenic in waters and sediments. Arsenic(V) is dominant in oxygenated waters, with appreciable quantities of arsenic(III) in some deoxygenated waters.There are few data for tin in water, sediments or organisms and no data on naturally occurring tin species. Tributyltin has been measured in water, sediment and organisms from areas affected by boating activity.
CVD of metal organic and other rare‐earth compounds
Authors: Deacon Glen B , MacKinnon Peter , Dickson Ron S , Pain Geoff N , West Bruce O 
Published: January 2005

AbstractThree major applications have been found for rare‐earth compounds in Metal Organic Chemical Vapour Depostion (MOCVD) or Chemical Vapour Deposition (CVD). Yttrium 2,2,6,6‐tetramethyl‐3,5‐heptanedionates and 6,6,7,7,8,8,8‐heptafluoro‐2,2‐dimethyl‐3,5‐octanedionates have been used in conjunction with barium and copper(II) β‐diketonates to deposit YBa2Cu3O7−δ as superconducting thin films. Rare‐earth fluorides and chlorides have been used for CFD doping of rare earths into MOCVD‐deposited ZnS, whilst yttrium chloride has been used, with barium iodide and copper(I) chloride, to produce YBa2Cu3O7−δ superconducting material by CVD. Lanthanoid (Ln) tris(cyclopentadienyl) compounds, Ln(C5H5)3 or Ln(C5H4Me)3, have been used for doping of rare earths into 13–15 (III–V) semiconductors. Their volatility, structure/volatility relationships, and preparations are discussed. Possible alternative reagents and problems to be faced in doping 12–16 (II–VI) semiconductors are also considered.
Interactions of organotins with biological systems
Authors: Musmeci M Teresa , Madonia Grazia , Giudice M Teresa Lo , Silvestri Arturo , Ruisi Giuseppe , Barbieri Renato 
Published: January 2005

AbstractThe bonding and structure in the environments of tin atoms in organotin‐biological molecules has been investigated by 119Sn Mössbauer spectroscopy, mainly through the rationalization of the nuclear quadrupole splitting parameter by pointcharge model approaches.Organotin moieties R2SnIV and R3SnIV (R = Me, nBu, Ph) generally assume trigonal‐bipyramidal type configurations in membranes of human erythrocytes, when incubated with whole erythrocytes and erythrocyte ghosts at the level of micromolar (μmol dm−3) organotin per mg of membrane protein. Corresponding structures are assumed by Me2SnIV and Me3SnIV in the cytoplasm. Ethanolic Me2SnCl2 yielded distorted trans‐octahedral species when reacted with ghost cells. These configurations may in principle originate through coordination of the metal by donor nitrogen or oxygen atoms from the cell constituents, such as protein side chains and related component molecules, carbohydrate fragments, and phospholipids, according to data from various model systems. Hydrolyzed species, such as bis(chlorodiorganotin) oxides and triorganotin hydroxides, could also occur for the n‐butyltin and phenyltin species.The moieties Me2SnIV and Alk3SnIV (Alk = Me, Et, nBu), present as the hydrolysis products Me2Sn(OH)2 and Alk3SnOH at physiological pH in the aqueous phase (eventually coordinated by donor atoms from buffers), react with thiol groups of model molecules, as well as of feline and rat hemoglobin, forming tetrahedral or trigonalbipyramidal tin sites characterized by covalent SnS bonds (C2SnS, C2SnS2 and C3SnS skeletons); tin atoms are eventually further coordinated by nitrogen donors from amino acid fragments or from buffers, as well as by hydroxyl oxygen.
Crystal structure and in vitro antitumor activity of bis(dicyclohexylammonium) bis(2‐sulfobenzoato)dibutylstannate
Authors: Ng Seik Weng , Das V G Kumar , Gielen Marcel 
Published: January 2005

AbstractAn X‐ray structure determination is presented for bis(dicyclohexylammonium) bis(2‐sulfobenzato)dibutylstannate, and its antitumor properties against mammary and colon carcinoma cell lines are reported.
Methylmercury(II) complexes with 2‐mercaptopyridinecarboxylic acids
Authors: Garcia M E , Thunus L , Monteagudo J C G , Fonseca J M L , Casas J S , Sordo J 
Published: January 2005

AbstractThe stability constants of the complexes [MeHgL]−(H2L = 2‐mercaptopyridine‐3‐carboxylic acid, 2‐mercaptopyridine‐4‐carboxylic acid, 2‐mercaptopyridine‐5‐carboxylic acid and 2‐mercaptopyridine‐6‐carboxylic acid) have been obtained by differential pulse polarography. The values of log β1 are in the range 14.14–14.96 at 20°C and ionic strength 0.1 mol dm−3. The complexes MeHgHL have been isolated and characterized by chemical analysis and mass and IR spectrometry.
Synthesis of polyphenylacetylene free‐standing films in the presence of rhodium–imidazole catalysts
Authors: Russo M V , Lucci G , Furlani A , Camust A , Marsich N 
Published: January 2005

AbstractA new dinuclear rhodium(I) complex [Rh2(cod)2(imH)2im]PF6 (I) has been synthesized and characterized. The complex is unstable in solution where it undergoes modifications leading to insoluble oligomers. However, it exhibits high catalytic activity towards polymerization of phenylacetylene (PPA) films can be obtained under mild reaction conditions. As‐grown PPA films are stable and soluble. Two different types of morphologies were found: one exhbits a cell‐like structure with microfibrils inside the cell and the other a dense enamel‐like smooth surface.
The interaction of organotins with native DNA
Authors: Piro Vincezo , Di Simone Francesco , Madonia Grazia , Silvestri Arturo , Giuliani Anna M. , Ruisi Giuseppe , Barbieri Renato 
Published: January 2005

AbstractThe compounds R2SnCl2 and R3SnCl (RMe, Et, nBu, nOct, Ph, in ethanol solution) as well as the aqueous species [Me2Sn(OH2)n]2+ and [Me3Sn(OH2)2]+, react with aqueous native DNA, yielding solid phases. According to the pointcharge model treatment of the 119Sn Mössbauer parameter nuclear quadrupole splitting, trans‐octahedral R2Sn(O2PXY)2, and trigonalbipyramidal R3Sn(O2PXY), (RMe, Et, nBu), would occur in the pellets, the tin atoms being coordinated by phosphodiester groups of the nucleic acid. The precipitates from Ph2SnIV would consist of the DNA complex as well as of the Ph2SnIV distannoxane obtained by hydrolysis of the reactant, whilst nOct2SnCl2, nOct3SnCl and Ph3SnCl would mainly yield stannoxanes and hydroxides. The water‐soluble hydrolyzed species [Me2Sn(OH)(OH2)n]+, Me2Sn(OH)2 and Me3Sn(OH)(OH2) do not show any interaction with native DNA, although they are possibly coordinated by phosphate oxygen atoms in model aqueous systems, in the presence of excess ligand.These trends have been rationalized by QSAR approach (Quantitative Structure‐Activity Relationships) in terms of electronic factors related to tin‐oxygen (phosphate) Coulomb interactions, as well as the lipophilicity of R in the RnSnIV moieties.
Electrochemical methods for the determination of total arsenic and arsenic compounds
Authors: Greschonig Herbert , Irgolic Kurt J 
Published: January 2005

AbstractThe determination of total arsenic and of arsenic compounds in biological and inorganic samples is a task frequently encountered by analysts. Several elecrochemical methods have been developed for the determination of total arsenic (generally after mineralization of the sample), arsenite, arsenate, methylarsonic acid and dimethylarsinic acid. The electrochemical behavior of several other organic arsenic compounds was also studied. This paper reviews these electrochemical methods, their application to environmental samples, and the problems encountered in the electrochemical determination of arsenic and arsenic compounds.
Organometallic complexes with biological molecules. I. Diorganotin(IV)chloro protoporphyrin IX complexes: Solid‐state and solution‐phase characterization
Authors: Pellerito Lorenzo , Pellerito Alessandro , Maggio Francesco , Beltramini Mariano , Salvato Benedetto , Ricchelli Fernanda 
Published: January 2005

AbstractProtoporphyrin IX (H4PPIX) complexes of diorganotin(IV)chloro moieties with formula (R2SnCl)2H2PPIX (RMe, Bu and Ph) have been obtained and their solid‐state and solution‐phase configurations have been studied through spectroscopic investigations.Coordination of the side‐chain carboxylates of H4PPIX to R2Sn(IV)Cl moieties, with bridging carboxylate (COO−) has been inferred by comparison of the free and coordinated H4PPIX IR spectra, while the occurrence of a five‐coordinated tin(IV) atom in a cis‐R2 trigonal bipyramidal structure has been deduced, for all of the synthesized complexes, by rationalization of the nuclear quadrupole splitting parameters, according to the point‐charge model formalism. Fanally, the solution‐phase spectral features of (R2SnCl)2−H2PPIX are in agreement with the monomeric character of the protoporphyrin IX, under the experimental conditions used.