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Langer R.,Karlsruhe Institute of Technology | Breitung B.,Karlsruhe Institute of Technology | Wunsche L.,Karlsruhe Institute of Technology | Fenske D.,Karlsruhe Institute of Technology | And 2 more authors.
Zeitschrift fur Anorganische und Allgemeine Chemie | Year: 2011

Eight new silver chalcogenide clusters with different functional groups in the ligand shell were synthesised and characterised by single-crystal X-ray diffraction. The optical properties of the isostructural clusters [Ag 6(S-C6H4-CN)6(PPh3) 6] (1) and [Ag6(S-C6H4-NO 2)6(PPh3)6] (2) are described and compared. In addition, the reactivity of 1 towards metal salts and Lewis acids was investigated, which led to the compounds [Ag6(S-C 6H4-CN)6(PPh3)5] (3) and [Ag14S(S-C6H4-CN)12(PPh 3)8][FeCl2(thf)4]3 (4). The sulfur-functionalised cluster [Ag14S(S-C6H 4-NCS)12(PPh3)8] (5) has prospects for further reactions and for the immobilisation on gold surfaces. The reactions of silver carboxylates with O,S-bis(trimethylsilyl)-4-hydroxythiophenol and bis(trimethylsilyl) chalcogenides in the presence of tertiary phosphanes lead to the formation of the clusters [Ag23S2(S-C 6H4-OSiMe3)15(S-C6H 4-OH)3(PPh3)8] (6) and [Ag 40Se4(S-C6H4-OSiMe3) 32(PPh3)8] (7). Compound 6 can be regarded as a dimer of the described Ag14-clusters in 4 and 5, whereas the inorganic core of cluster 7 has an unusual curved structural motif. The reaction of AgOAc with 4-hydroxothiophenol in the presence of triethylphosphane leads to the assembly of a three dimensional network of [Ag8(S-C 6H4-OH)6(PEt3)8](OAc) 2 (8) in the crystal structure. A solution of 8 was investigated by ESI mass spectrometry, which resulted in the detection of a series of polynuclear silver thiolates with the general composition [Ag n(S-C6H4-OH)n-1(PEt 3)2]+. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Albers A.,Kit Karlsruher Institute For Technology | Albers A.,Ipek Institute For Produktentwicklung | Bernhardt J.,Kit Karlsruher Institute For Technology | Bernhardt J.,Ipek Institute For Produktentwicklung | And 2 more authors.
Tribologie und Schmierungstechnik | Year: 2011

Lubricated multi-disc clutch systems are very often used machine elements. During sliding operation heat is generated. The heat transfer from the frictional contact to the cooling medium shows the load capacity. To enable the development of more powerful multi-disc clutch systems it is necessary to deepen the knowledge concerning heat transfer and the interaction with the systems design. The most important type of heat transfer is convection cooling. For this reason the oil flow through the clutch system which is depending on the systems design and the operating conditions is very important. As a result of the research are models available which can be used concerning the development of more powerful multi-disc clutch systems.

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