Cautions on use of the AM1 semiempirical parameters for germanium

Abstract

Reaction of Lithium 2,3,4,5-Tetramethylpyrrolide with [(i)4-C7H8)RuCl2],. In a three-necked round-bottom flask, equipped with a bar stirrer, nitrogen inlet, and septum, was added 2,3,4,5-tetramethylpyrrole (1.23 g, 10.0 mmol) and dry tetrahydrofuran (70 mL). To the stirred solution under nitrogen was added 6.9 mL (11.0 mmol) of a 1.6 M solution of n-butyllithium in hexane. The solution was stirred under nitrogen for 1 h, [(7j4-C7H8)RuCl2], (1.31 g 5.0 mmol) was added, and the mixture was stirred for 15 h. The solvent was evaporaed under a steady stream of dry nitrogen to give a black solid, which was extracted with two 100-mL portions of pentane. The volume of pentane was reduced under a stream of nitrogen to a volume of 5 mL and chromatographed on a 15-cm column of activity III neutral alumina. Elution with chloroform-acetone (1:1) gave a light brown solid, which was recrystallized from pentane to give 1.37 g (78% yield) of 2 as orange-brown crystals. The complex was identified as above.Acknowledgment. The helpful comments of Professor C. H. Winter are greatly appreciated.