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  • 1
    ISSN: 0044-2313
    Keywords: Nickel complexes ; nickelacyclic complexes ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Influence of Ring Size and Substitution on the Oxidative Addition of Cyclic Carboxylic Acid Anhydrides and Imides to the Moiety (N N)Niº (N N = bipy, tetramethylethylenediamine)(dipy)(COD) or a mixture of tmed/Ni(COD)2 easily react with cyclic carboxylic acid anhydrides by an oxidative addition. After decarbonylation with succinic acid anhydride a five-membered, with glutaric acid anhydride a six-membered metallacycle are formed - or With diphenic acid anhydride we obtained a seven-membered chelate in the boat form (XIV). Along their bond axis the two aromatic rings are twisted by 127°, i.e. the conjugative interaction is weak.Itaconic acid anhydride, as a polar olefine, can coordinate to the moiety (tmed)Ni side-on. But also on oxidative addition, yielding the five-membered chelate (XVI), is possible. The five-membered chelate is the only Product of the reaction with (dipy)Ni(COD).1.8-naphthalic acid anhydride (NSA), because of its rigidity, is not suitable for an oxidative addition to electron-rich nickel(O) complexes. But as a π acceptor ligand with a relatively low half wave potential NSA displaces COD of (dipy)Ni(COD) forming (dipy)Ni(NSA) · 0.25 THF (XVIII). One of the final products of the acidolysis of [(dipy)Ni]2(PPI) · 1.5 THF (XIX PPI=N-phenyl phthalimide) is benzanilide, a compound which might be an indicator of an oxidative additive connected with an -bond breaking in the course of the synthesis of XIX. But ir-data shows the framework of PPI to be preserved in the complex XIX. Evidently the bond breaking proceeds in the course of the acidolysis.
    Notes: (dipy)Ni(COD) bzw. ein Gemisch von tmed/Ni(COD)2 reagieren mit cyclischen Carbonsäure-anhydriden unter oxidativer Addition. Nach Decarbonylierung entstehen dabei mit Bernsteinsäureanhydrid ein fünfgliedriger, mit Glutarsäureanhydrid ein sechsgliedriger Nickelacyclus bzw. Mit Diphensäureanhydrid erhielten wir ein siebengliedriges Chelat in der Wannenform (XIV). Die beiden aromatischen Ringsysteme von XIV sind entlang der Bindungsachse um 127° gegeneinander verdrillt. Die konjugative Wechselwirkung zwischen diesen Ringen bleibt daher gering.Itaconsäureanhydrid kann an dem Rumpf (tmed)Ni als polares Olefin und damit side-on koordinieren. Es ist aber auch eine oxidative Addition unter Bildung von (XVI) möglich. Ausschließlich das oxidative Additionsprodukt wird bei der Umsetzung mit (dipy)Ni(COD) erhalten.Naphthalsäureanhydrid (NSA) mit seinem starren Hetero-Sechsring ist zu einer oxidativen Addition an elektronenreiche Nickel(0)-Komplexe nicht befähigt. Als π-Akzeptorligand mit einem relativ niedrigen ersten Halbstufenpotential vermag es jedoch COD aus (dipy)Ni(COD) unter Bildung von (dipy)Ni(NSA) 0,25 THF (XVIII) zu verdrängen.Die Acidolyse von [(dipy)Ni]2(PPI) · 1,5 THF (XIX; PPI = N-Phenylphthalimid) ergibt mit Benzanilid eine Verbindung, die auf eine bei der Synthese von XIX abgelaufene oxidative Addition unter -Bindungs-spaltung hindeutet. IR-Daten lassen jedoch nur den Schluß zu, daß im Komplex XIX das Skelett PPI noch erhalten ist. Die Bindungsspaltung erfolgt offenbar erst im Verlauf der Acidolyse.
    Additional Material: 2 Ill.
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  • 2
    ISSN: 0044-2313
    Keywords: [Li(TMED)2][Co(COD)2] ; π-acceptor ligands ; reactivity ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Reactions of [Li(TMED)2] [Co(COD)2] with π-Acceptor LigandsThe isoelectronic complexe [Li(TMED)2][Co(COD)2] und (dipy)Ni(COD) are compared as to their reactions with bifunctional nitrogen ligands (1, 4-Diaza-1, 3-diene, α, α′-bipyridine). In each case mixed ligand complexes of the type Li[)Co(COD)] (Solv)x (Solv = THF, TMED) are obtained. The magnetic properties, to a high degree, depend on the π-acceptor strength of the nitrogen ligand. Both diamagnetic (electron configuration 3d10 of cobalt) and paramagnetic complexes, such as Li[(tgd)Co(COD)] (Solv)x, (cobalt (0) with a 3d9-configuration and the radical anion tgd-), are formed (tgd = glyoxal[bis (4-methylphenylimin].[Li(TMED)2] [(dipy)Co(COD)] (IV) reacts with MSA by substitution of COD. In a solution of IV in THF surplus MSA is polymerised. It is unknown, whether the complex IV or TMED as a part of IV are the initiators of the polymerisation.
    Notes: Die isoelektronischen Komplexe [Li(TMED)2][Co(COD)2] und (dipy)Ni(COD) werden in bezug auf ihre Reaktivität gegenüber bifunktionellen Stickstoffliganden (1, 4-Diaza-1, 3-diene, α, α′-Dipypridyl) verglichen. In jedem Fall werden Gemischtliganden-Komplexe des Typs Li[)Co(COD)] (Solv)x (Solv = THF, TMED) erhalten. Das magnetische Verhalten dieser Verbindungen hängt in starkem Maße von der π-Akzeptorstärke des Stickstoffliganden ab; neben diamagnetischen Species (Elektronenkonfiguration 3d10 am Cobalt) steht der paramagnetische Komplex Li[tgd)Co(COD)] (Solv)x, der neben Cobalt(0) das Radikalanion tgd- enthält (tgd = Gloxal[bis(4-methylphenylimin)].[Li(TMED)2] [(dipy)Co(COD)] reagiert mit MSA unter Substitution des COD. Größere Überschüsse an MSA polymerisieren in der Lösung. Unklar bleibt, ob der Komplex oder nur seine Bestandteile diese Polymerisation initiieren.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A study using an electro-osmotic cell suitable for actuating an implantable insulin micropump showed that controlled variable flow rates in the order of 0.2 mL/day are possible. The cell functioned continuously with low energy and power requirements and long service life. The principle of operation is compatible with achieving the very low flow rates necessary if highly concentrated insulin is to be used to avoid frequent insulin reservoir refilling. An electro-osmotic cell, Ag/ AgCl/NaCl(aq)/ cation exchange membrane/NaCl(aq)/ AgCl/ Ag, was connected to a constant current power supply which reversed the direction of the current every 10 mins causing a to-and-fro transport of fluid through the membrane. Flow rates of 0.15-0.60 μL/min were achieved with currents of 2.5-10 mA. At the low flow rate, energy consumption was 6.4 × 10-2 J/μL and peak power requirement was 〈2.0 × 10-4 W. Fluid was transported against a pressure gradient of 52 cm Hg. The cell contained a total electrolyte volume of 〈0.25 mL. The membrane showed no change in properties after 10,000 current reversals (69 days). To function as an actuator for an implantable insulin micropump, the electro-osmotic cell requires a switching and valving assembly; a suitable design for this is briefly considered.
    Additional Material: 5 Ill.
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