856321-14-7Relevant articles and documents
Synthesis and properties of calcium tetraorganylalanates with [Me 4-nAlPhn]- anions
Krieck, Sven,Goerls, Helmar,Westerhausen, Matthias
, p. 5052 - 5057 (2008)
Triphenylalane yields in THF or Et2O the corresponding ether complexes [(thf)AlPh3] (1a) and [(Et2O)-AlPh3] (1b). The reaction of these triphenylalanes with phenylcalcium iodide in THF yielded quantitatively [(thf)5CaI][AlPh4] (2), which can be recrystallized from diethyl ether/THF mixtures without ether exchange reactions. The reaction of PhCa(thf)4I with trimethylalane in THF in an equimolar ratio leads to the formation of solvent-separated [(thf) 6Ca][AlMe3Ph]2 (5), which immediately shows ligand redistribution. Therefore, a fractionated crystallization gives [(thf)6Ca][AlMe2Ph2]2 (4) at 4°C, [(thf)4CaI2] at -20°C, and after reduction of the volume of the mother liquor [(thf)6Ca][AlMe3Ph] 2 (5) at -40°C and [(thf)6Ca][AlMe4] 2 (6) at -78°C. The formation of (thf)4Cal2 confirms that a Schlenk equilibrium is operative besides the ligand redistribution reactions. A solution of crystalline [(thf)6Ca] [AlMe2Ph2]2 (4) in THF shows 4 as the major component besides [(thf)6Ca][AlMe3Ph]2 (5) and [(thf)6Ca][AlMePh3]2 (3). With an increasing number of methyl groups the melting points decrease from 210°C for the tetraphenylalanate 2 to 20°C for the tetramethylalanate 6.
