Donorstabilisierte Aluminiumiodide: Ein Strukturvergleich
摘要:
In order to compare aluminium-iodides in different oxidation states the following species containing identical donor ligands have been synthesized: Al4I4 . 4PEt(3) and AlI3 . 2PEt(3). Their structural data are compared with those of the recently prepared Al2I4 . 2PEt(3). In spite of different coordination numbers (4 and 5) the expected trends in the size of Al-I, A(II) and Al-III and of their bonding to iodine and PEt3 could be realized.
AbstractNach Abschrecken von gasförmigem AlI‐iodid, das bei Temperaturen um 1000°C aus Al(fl) und HI(g) erzeugt wird, erhält man metastabile Lösungen von AlI‐iodid in einem Toluol/Diethylether‐Gemisch. Mit Triethylamin als Donor und Lösungsmittel kann kristallines (AlI · NEt3)41 isoliert werden. Die Röntgenstrukturanalyse zeigt, daß ein planarer Al4‐Ring vorliegt. Die AlAl‐Bindung in diesem ersten bei Raumtemperatur stabilen AlI‐iodid entspricht mit 265 pm dem Wert einer typischen AlAl‐Einfachbindung.
AbstractBy the end of the last century there were already the first indications of the possible existence of Al1 halides. However, it was only through the pioneering works of W. Klemm, who would have celebrated his 100th birthday on January 6, 1996, that detailed spectroscopic investigations became possible. Since the end of the 1970s the reactivity of AlX and GaX species in solid noble gases has been confirmed by numerous examples. In recent years formally monovalent Al and Ga species have been successfully synthesized on a preparative scale. In addition to the first halides, organometallic compounds with metal–metal bonds have been isolated and investigated with regard to their chemical properties. The fundamental importance of such species has been documented in this journal among others in the form of two highlight articles in which experimental and theoretical aspects have been examined with examples, and parallels and differences with respect to boron chemistry have been illustrated. This review is intended to give an account of the chronological development of this research area over the last few years, but an attempt is also made to categorize the experimental results achieved not only with respect to structure, thermodynamics, and reactivity, but also with the aid of quantum chemical calculations and by comparative considerations.
By co-condensation of a mixture of solvents (toluene and a donor species (Do)) together with the high-temperature molecule ALT. metastable solutions are obtained which are suitable starting materials for different reactions: the reaction with sulfur leads to Do(I)Al-(mu(2)-S)(2)-Al(I)Do; together with dimeric Cp*MgCl . OEt2 an unexpected redox reaction ends up with (eta(1)-Cp*)AlI2 . OEt2; treatment with DME results in an intermediate of ether-cleavage: (Me(I)AlOC2H4OMe)(2). These three compounds have been structurally analyzed by means of X-ray methods. - NMR-spectroscopic techniques provide evidence of Al-I-species stabilized by interaction with aromatic compounds. This conclusion could be confirmed with the help of ab initio calculations.