Zur Koordination unterschiedlicher Hauptgruppenmetalle mit einem speziellen, chelatisierenden Silazan

The cis-isomer of the silazane H2L (1) (L=[NtBu][Me]Si(ntBu)2Si[Me][NtBu]) has been used as a ligand to main group metals. By displacing the hydrogen atoms of 1 the compounds L(MgMe)2 (4), L(MgCl)2 (5) and L(Li)(InMe2) (6) have been obtained. According to the 1H NMR spectra the structures of 4-6 are very similar: a polycyclic, cubane-like Si2N4M2 framework results from the special atomic arrangements and from intramolcular Lewis acid-base interactions between the metals M and the nitrogen atoms. Divalent metals and metal-centered groups can also be incorporated into 1. In the latter case a seco norcubane-like polycycle Si2N4M is produced as confirmed by X-ray structure determinations of LGaMe (8) and LSb+InCl4- (11). LInMe (7) and LSn (9) seem to adopt the same tricyclic structure as 8, although the 1H NMR spectra are not consistent with a rigid molecule (low symmetry), but rather with a fluxional behaviour (high symmetry). When 5 is allowed to react with sodium/naphthalene in THF part of the magnesium is reduced and LMg(THF)2 (12) is formed. An X-ray structure determination of 12 reveals the compound to be only bicyclic with the magnesium atom coordinated by two nitrogen and two THF oxygen atoms.