Structures of tetrasilylmethane derivatives (XMe2Si)2C(SiMe3)2 (X = H, Cl, Br) in the gas phase, and their dynamic structures in solution

The structures of the molecules (XMe2Si)2C(SiMe3)2, where X = H, Cl, Br, have been determined by gas electron diffraction (GED) using the SARACEN method of restraints, with all analogues existing in the gas phase as mixtures of C1- and C2-symmetric conformers. Variable temperature 1H and 29Si solution-phase NMR studies, as well as 13C NMR and 1H/29Si NMR shift correlation and 1H NMR saturation transfer experiments for the chlorine and bromine analogues, are reported. At low temperatures in solution there appear to be two C1 conformers and two C2 conformers, agreeing with the isolated-molecule calculations used to guide the electron diffraction refinements. For (HMe2Si)2C(SiMe3)2 the calculations indicated six conformers close in energy, and these were modeled in the GED refinement

Attachment of the bulky bidentate ligand C(SiMe3)2SiMe2CH2CH2Me2si(Me3Si)2C to K Zn Sn and Yb. Crystal structures of LnMC(SiMe3)2Sime2CH2CH2Me2Si(Me3Si)2CMLn (MLn = K(C6H6)2 K(THF)2 SnCl3 or SnMe2Cl) and CH2SiMe2C(SiMe3)2ZnC(SiMe3)2SiMe2CH2 (THF = t

Reaction of the lithate [Li(THF)(4)][CH2SiMe2C(SiMe3)(2)LiC(SiMe3)(2)SiMe2CH2] with (KOBu)-Bu-t in THF has given the organopotassium reagent (THF)(2)KC(SiMe3)(2)SiMe2CH2CH2Me2Si(Me3Si)(2)CK(THF)(2), 8, and reaction of HC(SiMe3)(2)SiMe2CH2CH2Me2Si(Me3Si)(2)CH with KMe in benzene has given the related ether-free species (C6H6)(2)KC(SiMe3)(2)SiMe2CH2CH2Me2Si-(Me3Si)(2)CK(C6H6)(2), 7. The structures of 7 and 8 have been confirmed by X-ray studies which indicate that both compounds show K ... Me contacts in the range 3.3-3.5 Angstrom. The ether-free reagent 7 reacted with YbI2 in benzene to give the cyclic Yb(II) derivative CH2SiMe2(SiMe3)(2)YbC(SiMe3)(2)SiMe2CH2, which was found to be somewhat more stable toward Et2O than the I previously studied Yb{C(SiMe3)(3)}(2). Reaction of the lithate [Li(TMEDA)(2)][CH2SiMe2C(SiMe3)(2)LiC(SiMe3)(2)SiMe2CH2] (2a) with ZnCl2 in THF gave a cyclic compound CH2SiMe2C(SiMe3)(2)ZnC(SiMe3)(2)SiMe2CH2, which is stable toward boiling aqueous THF. An X-ray study shows that the angle at Zn is 170 degrees. In contrast, the reactions of 2a with SnCl4 or Me2SnCl2 gave linear species ClX2SnC(SiMe3)(2)SiMe2CH2CH2Me2Si(Me3Si)(2)CSnX2Cl, X = Cl or Me, the structures of which were confirmed by single-crystal X-ray diffraction studies