lithium aluminium tetrahydride in hexane N2-atmosphere; stirring Cr-complex with excess of ethylmesitylene, AlEt3 and LiAlH4; distn. (100°C, 1.3 Pa, then 130-140°C), repeated sublimation (130°C, 1.3 Pa), chromy. (SiO2, hexane), sublimation (110°C, 1.3 Pa), recrystn. (hexane); elem. anal.;