Nabeel H. Buttrus

The crystal structure of di-t-butylsilanediol and its relevance to the liquid crystallinity of diisobutylsilanediol

The crystal structure of t-Bu2Si(OH)2 consists of hydrogen-bonded dimers linked by further hydrogen bonding into (distorted) ladder chains, the type of structure previously postulated for solid i-Bu2S(OH)2 to account for its ability to give a liquid crystal on heating. The six-membered rings of the dimers have a chair conformation with adjacent chairs inverted with respect to one another. The structure of the ladder chains is similar to that in t-Bu2Ge(OH)2, but the packings of the chains in the crystal are different.

Hydrogen-bonding in organosilanetriols. The crystal structures of tris(trimethylsilyl)silyl- and tris(trimethylsilyl)-methyl-silanetriols

Abstract The organosilanetriols (Me 3 Si) 3 CSi(OH) 3 and (Me 3 Si) 3 SiSi(OH) 3 both crystallize as hexameric hydrogen-bonded cages with no hydrogen bonding between the cages. Both (Me 3 Si) 3 CSi(OH) 3 and (Me 3 Si) 3 SiSi(OH) 3 are remarkably thermally stable as solids, melting with decomposition only at 285–290 and 210–213°C, respectively.

Novel alkylmetal hydroxides. The crystal and molecular structures of bis(µ-hydroxy)-bis{tris(dimethylphenylsilyl)methylzinc}, [{Me2PhSi)3CZnOH}2] and µ4-oxohexa(µ-hydroxy)tetrakis{tris(trimethylsilyl)methylindium}, [O{(Me3Si)3Cln}4(OH)6]

The compounds [{(Me2PhSi)3CZnOH}2] and [O{(Me3Si)3Cln}4(OH)6] have been shown by X-ray diffraction to have structures based on four-membered M2O2-rings (M = Zn or ln).

Silylmethyl and related complexes VIII. Bis[bis(trimethyl)silylmethyl]manganese(II): Its synthesis, properties, and crystal structures of its tetrahydrofuran and bis(dimethylphosphino)ethane adducts☆

Abstract Treatment of the manganese dialkyl MnR 2 [R = CH(SiMe 3 ) 2 ], prepared from anhydrous MnCl 2 and LiR in Et 2 O, with tetrahydrofuran (THF), yielded the crystalline complex [MnR 2 (THF)] ( 1 ). It was also obtained from MnCl 2 and [MgR(μ-Cl)(THF)] 2 in THF. Treatment of 1 with (Me 2 PCH 2 ) 2 (DMPE) afforded [MnR 2 (DMPE)] ( 2 ). Selected bond lengths and angles for 1 ( 2 in brackets) are MnC 2.06(2) [2.17(1)] and MnO 2.19(2) [MnP 2.775(4)] A, CMnC′ 160.1(9) [141.4(7)], OMnC 100.0(6)° [PMnC 98.7(4) and 112.1(3), and PMnP′ 74.4(1)°]. Compound 1 is also a monomer in n-C 5 H 12 . Its magnetic behaviour is consistent with high spin Mn(II), and its EPR spectrum (like that of 2 ) at ambient temperature in THF showed a broad singlet ( g av = 2.005 for 1 ). Various reactions of complex 1 have been carried out: PMe 3 gave [MnR 2 (PMe 3 ) 2 ], ArOH gave Mn(OAr) 2 (Ar = C 6 H 2 Bu 2 t -2,6-Me-4), and M[N(SiMe 3 ) 2 ] 2 gave MR 2 (M = Sn or Pb) (providing particularly convenient route to these Group 14 metal alkyls).

Hydrogen bonding in organosilicon hydroxides: crystal structures of dicyclohexylsilanediol and bis(hydroxydimethylsilyl)bis(trimethylsilyl)methane

Abstract An X-ray diffraction study has shown that dicyclohexylsilanediol crystallizes as hydrogen-bonded dimers linked by further hydrogen bonding into ladder chains, the hydrogen bonding being closely similar to that in the crystal of i-Pr 2 Si(OH) 2 . The diol (Me 2 Si)P 2 C(SiMe 2 OH) 2 forms infinite chains with one oxygen within a molecule linked by hydrogen bonding to the other, which in turn is hydrogen-bonded to the oxygen of another molecule.

Preparation and some reactions of the compounds HgVsi2, CdVsi2, and Hg(Vsi)Br [Vsi = (Me3Si)2 = CHMe2Si)C]. Crystal structure of CdVsi2

Abstract Treatment of MBr 2 (M = Hg or Cd) with a 2 molar proportion of VsiLi [Vsi = (Me 3 Si) 2 (CH 2 =CHMe 2 Si)C] gave MVsi 2 . Us eof a 1 molar proportion of VsiLi in the reaction with HgBr 2 gave VsiHgBr. The MVSi 2 compounds are stable toward HCl in Et 2 O, boiling MeCOCl containing a little LiBr, or MBr in boiling THF, and CdVsi 2 is also stable towards MeOH in PhMe under reflux. HgVsi 2 reacts with CF 3 CO 2 H at 60°C to give Hg[C(SiMe 3 ) 2 (SiMe 2 P 2 CCF 3 )] 2 . An X-ray diffraction study has shown that CdVsi 2 has a linear structure very similar to those of Hg[C(SiMe 3 ) 3 ] 2 and Mn[C(SiMe 3 ) 3 )] 2 .

The preparation and crystal structures of [(Me3Si)3C]PhSi(OH)2 and [(Me3Si)3C]PhSi(Ome)OH

Abstract The silanol Tsi(Ph)Si(H)OH (Tsi= (Me 3 Si) 3 ) was prepared by hydrolysis of Tsi(Ph)Si(H)I in aqueous dioxane, and then treated with ICl in CCl 4 to give Tsi(Ph)Si(I)OH, which in turn was hydrolysed with H 2 O/Me 2 SO to give the diol Tsi(Ph)Si(OH) 2 . Treatment of Tsi(Ph)Si(I)OH with NaOMe/MeOH gave Tsi(Ph)Si(OMe)OH. In the crystal the diol Tsi(Ph)Si(OH) 2 forms discrete cyclic dimers, with the component molecules held together by two unsymmetrical non-linear hydrogen bonds. The related species Tsi(Ph)Si(OMe)OH also forms dimers, but in these the component molecules are linked through a single hydrogen bond between OH groups, with no hydrogen-bonding to the OMe group.

The crystal structure of [(pmdeta)Li(µ-Cl)Li(pmdeta)][Li{C(SiMe3)3}2][pmdeta = Me2N(CH2)2NMe(CH2)2NMe2]. A novel linear chlorine-centred cation

Treatment with pmdeta [pmdeta = Me2N(CH2)2NMe(CH2)2NMe(CH2)2NMe2] in toluene of [Li(thf)4][Li{C(SiMe3)3}2](thf = tetrahydrofuran) containing LiCl has given [(pmdeta)Li(µ-Cl]Li(pmdeta)][Li{C(SiMe3)3}2], in which the chlorine-centred cation is linear.

Preparation and crystal structure of dimethyltris(trimethylsilyl)methylsilanatolithium tetrahydrofuranate

Abstract A single crystal X-ray diffraction study has shown that the solid isolated after treatment of (Me 3 Si) 3 CSiMe 2 OH with MeLi in THF is the dimeric species [(Me 3 Si) 3 CSiMe 2 OLi · thf] 2 . Cryoscopy shows the product to be a tetramer in benzene.

The crystal structure of t-Bu2Si(OH)F. A cyclic hydrogen-bonded tetramer

Abstract An X-ray diffraction study has shown that t-Bu2Si(OH)F crystallizes as hydrogen-bonded tetramers. The fluoride ligand does not take part in the hydrogen bonding, which involves OH--O linkages with an OH--O angle of 160°; the O---O---O angles are 89.7(3)°, but the four oxygen atoms are not quite coplanar (space group I 4 ). The t-BuSiBu-t angle is 120.5(6)°.