Vibrational Study of Eight-Membered Zirconium- and Boron-Containing Siloxane Rings

Haoudi-Mazzah, A.; Mazzah, Ahmed; Gnado, J.; Dhamelincourt, P.

doi:10.1002/(sici)1097-4555(199606)27:6<451::aid-jrs977>3.0.co;2-o

Cited by 6 publications

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“…Molecular metallasiloxanes have attracted considerable attention in recent years due to their role as model compounds for structurally modified silica surfaces or minerals, their interesting physical properties, and their potential as precursors for new inorganic materials. − A rich structural diversity of eight-membered rings incorporating various heteroatoms, such as B, Al, Ge, Sn, P, Ti, Zr, Hf, Mo, and W, exists among the cyclo -metallasiloxanes. − Single-crystal X-ray diffraction studies show that even very similar compounds can have drastically different ring conformations. A large variety of ring conformations have also been observed in the crystal structures of cyclo -tetrasiloxanes. − …”

Section: Introductionmentioning

confidence: 99%

Comparison of the Flexibility of Eight-Membered Tetrasiloxane and Stannasiloxane Rings: A Crystallographic and Computational Study

Beckmann¹,

Jurkschat²,

Schürmann³

et al. 2001

Organometallics

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The syntheses and crystal structures of the eight-membered cyclo-stannasiloxanes cyclo-[t-Bu(OH)Si(OSnt-Bu2O)2Si(OH)t-Bu] (1) and cyclo-{t-Bu2Si[OSn(CH2SiMe3)2O]2Sit-Bu2} (2) as well as the synthesis of the six-membered cyclo-stannasiloxane cyclo-{t-Bu2Si[OSn(CH2SiMe3)2]2O} (3) are reported. Compound 1 crystallizes as its trans isomer, but the cis isomer dominates in solution. In agreement with the experimentally obtained results, ab initio and DFT calculations on the model compounds cyclo-(H2SiO)4 (4), cyclo-[H2Si(OSnH2)OSiH2] (5), cyclo-O(H2SiOSnH2)2O (6), and cyclo-[H2Si(OSiH2)OSnH2] (7) indicate that the energetic preference to adopt puckered structures increases and the ring flexibility decreases with an increasing number of tin atoms in the ring. The rich diversity of puckered conformations is attributed to the steric demand of the different organic substituents.

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