STRUCTURES AND INTRAMOLECULAR MOTIONS OF SPECIAL POLYCYCLIC GERMANIUM(II) AMIDES

Compounds of the general formula MeSi(NtBu)(3)Ge(2)X (X = Cl (1), N(Si Me(3))(2) (2), P(C6H5)(2) (3)) have been synthesized and characterized by X-ray structure analyses and multinuclear NMR-spectroscopy. The te mperature dependent NMR investigations of 2 in solution show bond fluc tuations concerning the metal-nitrogen bonds and ElMe(3) (El = C, Si) rotations. Some of these intramolecular motions also occur in the soli d state as detected by means of temperature dependent C-13 CP/MAS NMR spectroscopy. The special nature of these NMR spectroscopically detect ed movements in solution are compared with the results of the X-ray st ructure analyses. A model of the dynamical behaviour of 2 in solution suggests a quasi circular movement of the two germanium atoms within t he molecular cage. After the phase transition from solution to the sol id state at ambient temperature this special metal fluctuation is stop ped. In the solid state the rotations of the SiMe(3) groups in 2 are o nly hindered at low temperatures.