摘要:

AbstractChromatographic aspects of the analysis of Group IV organometallic derivatives are reviewed. The emphasis is towards gas and liquid chromatography.

ISSN:0268-2605    

DOI:10.1002/aoc.590040202

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractPolyacetylene, which exhibits metallic‐like electrical conductivity upon redox doping, led to the development of a new class of electronic materials. Metallic conductivity in polyacetylene originates from the mobility of charge‐carriers along the highly conjugated π‐electron carbon backbone. On the other hand, organometallic polymer backbones comprising transition‐metal ions and highly conjugated ligands may themselves produce intrinsically conducting materials due to the increased molecular orbital interaction between metal atoms via ligands. For decades organometallic polymers have been the subject of great scientific interest due to their unique electrical properties and many potential uses. Following the discovery of polyacetylene, the cofacially joined metallophthalocyanine polymers emerged as a new class of electrically conducting polymers. This important class of conducting organometallic polymers now includes a wide variety of materials such as poly(metalyne), poly(metallophthalocyanines), metal poly(benzodithiolene), poly(metalloethylene tetrathiolate), poly(metal tetrathio‐oxalate), etc. Depending upon the molecular structures, many organometallic polymers are intrinsic conductors while in others metallic‐like conductivity is induced by a molecular doping process. The superiority of electrically conducting organometallic polymers is manifest in their excellent environmental stability and processability. Conducting organometallic polymers have a wide range of applications in electrocatalysis, photovoltaics, sensors and fuel‐c

ISSN:0268-2605    

DOI:10.1002/aoc.590040203

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractArsenic analogs of lecithins (i.e. with replacement of nitrogen by arsenic in the choline group) are probably trace constituents of phospholipids in many organisms. Attempts to synthesize 1,2‐bis(palmitoyloxy)‐3‐propyl 2‐trimethylarsonioethyl phosphate (arsenolecithin) according to wellestablished procedures for the synthesis of the corresponding nitrogen compound failed. However, 1,2‐bis(palmitoyloxy)‐3‐propyl 2‐trimethylarsonioethylphosphonate, an arsenic‐containing phosphonolipid, was obtained in 16% yield by reacting 1,2‐bis(palmitoyloxy)‐3‐iodopropane with silver 2‐trimethylarsonioethylphosphonate in isopropanol. The precursors to the arsenic‐containing phosphonolipid were obtained by quaternization of trimethylarsine with diethyl 2‐bromoethylphosphonate, hydrolysis of the resulting product with concentrated hydrochloric acid, and reaction of the phosphonic acid with silver oxide to give silver 2‐trimethylarsonioethylphosphonate. Quaternization and hydrolysis proceeded almost quantitatively. The silver phosphonate was n

ISSN:0268-2605    

DOI:10.1002/aoc.590040204

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractAn interaction oftrans‐[PtH(SnX3)L2] (I, L = PPh3, PMePh2, PEt3; PBu3; X = Cl, Br) with ethylene, propene and 2‐methylpropene has been studied by means of31P and1H NMR spectroscopy. The reactions of platinum hydrides I with ethylene are rapid and reversible at −90°C, givingcis‐[PtR(SnX3)L2] (II, R = C2H5). The reaction of propene with I (L = PPh3, PMePh2) gives II, R = C3H7.13C and1H NMR spectra prove the n‐propyl structure for II, L = PMePh2, X = Cl. Complexes II irreversibly isomerize intotrans‐[PtR(SnX3)L2] between −50° and 0°C. The equilibrium constants and rates are estimated for the reactions of I with alkenes. They decrease as a function of L (PMePh2>PPh3>PBu3>PEt3) and X (Br>Cl). The reactivities of alkenes decrease with increase of steric hindrances at

ISSN:0268-2605    

DOI:10.1002/aoc.590040205

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe uptake of arsenate byCandida humicolarequires an active transport system and may operate through low‐ and high‐affinity sites. Arsenite, methylarsonate and dimethylarsinate are deduced to enter the cell by slow passive diffus

ISSN:0268-2605    

DOI:10.1002/aoc.590040206

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe incorporation of a range of iron‐containing organometallic compounds into a cable and wire poly(vinyl chloride) (PVC) formulation has been investigated. Limiting Oxygen Index and smoke density data were obtained across a range of formulations and the effects of the compounds on flammability and smoke generation are discussed. All the organoiron compounds markedly reduce smoke formation and some of them synergistically reduce the flammability of the polyme

ISSN:0268-2605    

DOI:10.1002/aoc.590040207

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe electrochemical behaviour of three series of organotin(IV) compounds having the general formula RySnX4−y(R = Me, nBu or Ph,y= 2 or 3, X = Cl; R = Me or Ph,y= 3, X = NO3, N3, NCS, NCO, OAc or OH) have been examined in the non‐aqueous solvents dimethylformamide and acetonitrile, at rotating disc electrodes of glassy carbon and gold electrodes. The reduction of tin(IV) in the above series gave a single wave and obeyed the Levich plots at both electrodes in the two solvents. The electrode kinetic parameters and halfwave potentials have been determined, and the effect of solvents and substituents on these parameters have been explo

ISSN:0268-2605    

DOI:10.1002/aoc.590040208

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractInfrared spectroscopic evidence (CO stretching region) is presented to show that near‐UV irradiation (280<λ<350 nm) of Fe(CO)5in lowdensity polyethylene (LDPE), poly(vinyl chloride) (PVC) and polytetrafluoroethylene (PTFE) films atca12 K affords the coordimatively unsturated species Fe(CO)4and Fe(CO)3. The species Fe(CO)3recombines with CO atca60 K whilst Fe(CO)4recombines atca80 K. The species also react with the polymeric medium and with residual solvent molecules [hexane, dichloroethane, tetrahydrofuran (THF)] in the films. The species Fe(CO)4…(PVC) and Fe(CO)4…(dichloroethane), in which the Fe(CO)4fragments are probably coordinated by chlorine atoms in the PVC or solvent molecules, are less thermally stable than Fe(CO)4(THF) and are converted to Fe(CO)5on warming the films to aboveca140 K. Similarly, the species Fe(CO)4(LDPE) and Fe(CO)4(hexane), arising from interaction of Fe(CO)4with hydrogen atoms in the polymer or solvent molecules, are converted to Fe(CO)5on warming the films fromca100 K toca130 K. The major product formed in LDPE films at 298 K is probably Fe(CO)4(olefin) arising from olefin impurities in the poly(ethylene), whilst in the PVC films in the presence or absence of THF the major product resembles (η3–C3H5)Fe(CO)3Cl, i.e. Fe(CO)4and Fe(CO)3fragments bound to allyl chloride impurities in the PVC. The potential of polymer films for trapping and characterizing unstable species i

ISSN:0268-2605    

DOI:10.1002/aoc.590040209

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractRhodium precursor catalysts supported on palygorskite, montmorillonite and silica were obtained from an organometallic cationic rhodium species and evacuated supports at different temperatures. Based on the different times which precursors took to be active in 1‐hexene hydrogenation, in the liquid phase at atmospheric hydrogen pressure, it has been deduced that the supported rhodium species varies with the support and its dehydration temperature. Activity in this reaction also depended on the support, its dehydration temperature and storage in air. Precursors and catalysts were characterized by X‐ray photoelectron and infrared spectroscopy. Very stable complexes are obtained under humid ambient conditions. With montmorillonite support, activity decreases if rhodium/1‐hexene ratio decr

ISSN:0268-2605    

DOI:10.1002/aoc.590040210

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY

摘要:

AbstractThe organopolysilanes Me(Me2Si)nMe (n= 4–6), (Me2Si)6and (Me3Si)2SiMePh are found to be effective photoinitiators for the polymerization of vinyl‐containing siloxane rubbers. The trisilanes Me(ME2Si)3Me and Me3SiSiMe2SiMe2Ph are slightly effective, while phenyldisilanes do not exhibit initiation activity in the process of photocuring. Polydimethylsiloxanes are cured at a slower rate under the same conditions than vinylcontaining derivatives. Two mechanisms of crosslinking are proposed: silylene–silirane–silanol and silylene–hydrid

ISSN:0268-2605    

DOI:10.1002/aoc.590040211

出版商:John Wiley&Sons Ltd.    

年代:1990

数据来源: WILEY