Synthesis and Molecular Structures of 2-Trimethylsilyl-, 2-Trimethylgermyl-, and 2-Trimethylstannyl-pyridines

Z. Naturforsch. 54 b, 13-17 (1999); received June 1, 1998 Pyridine, 2-Silyl-pyridine, 2-Germyl-pyridine, 2-Stannyl-pyridine, Molecular Structure 5-Methyl-2-trimethylsilyl-pyridine (1) has recently been prepared via the “in situ” Grignard reaction of 1-bromo-5-methyl-pyridine with magnesium and trimethylchlorosilane in refluxing tetrahydrofuran (thf) and structurally characterized. 2-Trimethylgermyl(2) and 2trimethylstannyl-pyridine (3) were now obtained from 2-bromo-pyridine through metallation (with /?-BuLi) and treatment of the intermediates with Me.^GeBr and Me.^SnCl, respectively, in diethylether/ thf at -70°C. The crystal and molecular structure of compound 2 has been determined by low temperature (in situ) single crystal X-ray diffraction methods. There is a significant bending of the Me.^Ge substituent towards the nitrogen heteroatom [Ge-C-N = 114.7(2)°]. This phenomenon is known from previous studies of the silicon analogue 1 to be not due to intramolecular (peripheral) Si/Ge—N coordination, but to be rather an intrinsic property of the heteroarene skeleton, as also confirmed by quantum-chemical calculations. Furthermore, there is no evidence for mtermolecular coordination in the crystals. Such inter­ actions could also be ruled out for the solution state of 2 and 3 through variable temperature multinuclear NMR investigations.