N,N,N′,N′-Tetramethylethylendiamin-di(tert-butyl)aluminium-Kationen — Molekülstruktur des [(Me3C)2Al · TMEDA]⊕[(Me3C)2AlBr2]⊖

(N,N,N′,N′ -tetramethylethylendiamine) di(tert-butyl)aluminium Cations — Molecular Structure of [(Me₃C)₂Al(TMEDA)]^⊕[(Me₃C)₂AlBr₂]^? Dimeric di(tert-butyl)aluminium halides (Me₃C)₂AlX (X = Cl, Br) react with N,N,N′,N′ -tetramethylethylendiamine (TMEDA) to give three compounds: the salt-like [(Me₃C)₂Al(TMEDA)]^⊕[(Me₃C)₂AlX₂]^? 1 , characterized by crystal structure determination, and [(Me₃C)₂Al(TMEDA)]^⊕X^? 3 both with chelating amine, and the more covalent, pentane soluble (Me₃C)₂AlX(TMEDA) 2 with TMEDA bound by only one nitrogen atom. The reaction resembles the symmetrical and unsymmetrical cleavage of diborane(6). 3 (X = Cl) is also formed by treatment of 1 with boiling n-hexane in the presence of TMEDA over a period of 24 hours, while for X = Br the more covalent 2 is the main product under similar conditions. In solution 2 decomposes slowly yielding different products in dependency of the solvent: in benzene 3 and in n-pentane 1 are formed.     

Preparation of p-[(S)(—)-2-phthalimidopropionyl] polystyrene

Samples of atactic and isotactic polystyrene were acylated with N-phthaloyl-L -alanyl chloride under the conditions of Friedel-Crafts reaction. The degree of acylation was strongly dependent on molecular weight, but not on the tacticity of polystyrene. Similarly the specific rotation of acylated polymers was not influenced by the structure of the polymer chain.     

NaAg3S2, ein Thioargentat mit dem Clusteranion [Ag6S4]2−

NaAg₃S₂, a Thioargentate Containing the Anionic Cluster [Ag₆S₄]^2? . Dark-red octahedrally shaped crystals of NaAg₃S₂ could be obtained by the reaction of NaAg(CN)₂ and NaCN in a stream of hydrogen sulfide at 630 K. NaAg₃S₂ crystallizes cubic, a=12.358(1) Å, space group Fd3 m, Z=16. The structure was determined from four-circle diffractometer data. NaAg₃S₂ contains the anionic cluster [Ag₆S₄]^2?. The structure can be traced back to the spinel structure typ. An extended Hückel calculation for the cluster anion, which is considered to be isolated, shows weak bonding silver-silver interactions. NaAg₃S₂ is diamagnetic at room temperature.