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Germanium(II)‐, Tin(II)‐ and Lead(II)‐Derivatives of the polycyclic Alumosiloxane [Ph2SiO]8[Al(O)OH]4Five new derivatives of the polycyclic alumosiloxane [Ph2SiO]8[Al(O)OH]4 have been synthesized by replacement of the protic hydrogen atoms on the hydroxy‐groups attached to the aluminium atoms by the divalent group 14 elements germanium, tin and lead. The compounds can be divided in those with one metal atom per alumosiloxane moiety, [Ph2SiO]8[Al(O)OH]2[AlO2]M (M=Ge, Sn), and those with complete substitution of the protic hydrogen atoms by metal atoms like [Ph2SiO]8[AlO2]4M2 (M= Sn, Pb). Always one element of the series Ge, Sn, Pb is missing in the two types of compounds. Crystal structure analyses of [Ph2SiO]8[Al(O)OH]2[AlO2]2M · 2 C4H8O2 (M= Ge (1), Sn (2a)), [Ph2SiO]8[Al(O)OH]2[AlO2]2Sn · 2 THF (2b) and [Ph2SiO]8[AlO2]4M2 (M= Sn (3), Pb (4)) have been performed elucidating either polycyclic basket‐type (1, 2a, 2b) or closed polyhedral structures (3, 4).

Bis(hexamethyldisilazyl)tin(II) in excess reacts with the molecular alumosiloxane (Ph 2 SiO) 8 (AlO(OH)) 4 to yield the well known tin(II) derivative (Ph 2 SiO) 8 (AlO 2 ) 4 Sn 2 and the novel bicyclic [(Me 3 Si) 2 N]Sn[N(SiMe 3 )SiMe 2 CH 2 ] 2 Sn[N(SiMe 3 ) 2 ] containing a tin-tin bond, which is formally related to the starting molecule by a missing hydrogen atom. From X-ray diffraction studies on single crystals it follows that the new compound has almost C 2 point symmetry (the twofold axis intersecting the tin-tin bond) and that this tin-tin bond is the fusion edge of anellated fivefold