ChemInform Abstract: NEW ROUTE TO THE SYNTHESIS OF 1,1‐DIMETHYL‐1‐SILA‐3‐CYCLOPENTENE

Gusel’nikov, L. E.; Kerzina, Z. A.; Polyakov, Yu. P.; Nametkin, N. S.

doi:10.1002/chin.198224272

Cited by 1 publication

(4 citation statements)

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“…In contrast to most of the other silacyclobutanes, which start to polymerize on heating to 210 °C, 1,2-TMDSCB − and its 1,1,2-Me-2-Et analogue ( 5 ) were reported by Gusel’nikov et al to undergo spontaneous exothermal polymerization at room temperature via Si–Si bond cleavage with formation of high-molecular-weight poly(ethylenedisilene). Herein this process was followed by Raman spectroscopy, and the results are presented in Figure .…”

Section: Resultsmentioning

confidence: 97%

“…As a possible mechanism of 1 polymerization, Gusel’nikov et al − , proposed thermal ring opening. However, this mechanism can now be excluded on the following grounds.…”

Section: Resultsmentioning

confidence: 99%

“…1,1,2,2-Tetramethyl-1,2-disilacyclobutane ( 1 ) was first synthesized in 1980; some of its properties were reported later − and reviewed. , To the best of our knowledge, no other laboratory but Professor Guselnikov’s has ever worked with 1 because this compound was reported to be thermally unstable and highly reactive. It could be stored only at liquid nitrogen temperature.…”

Section: Introductionmentioning

confidence: 99%

“…The interest in 1 is due not only to its structure (hitherto unknown!) but also to its reported capability for spontaneous polymerization on heating to room temperature with the formation of high-molecular-weight poly(ethylenetetramethyldisilene) ([−CH 2 Me 2 SiSiMe 2 CH 2 −] n ). − Before 1980, only a few differently Si- and C-substituted 1,2-disilacyclobutanes had been described. − …”

Section: Introductionmentioning

confidence: 99%

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Unstable 1,1,2,2-Tetramethyl-1,2-disilacyclobutane and Its Polymerization. Vibrational Spectroscopy and Quantum-Chemistry Study

et al. 2012

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The structure of 1,1,2,2-tetramethyl-1,2-disilacyclobutane (1) has been investigated by experimental means, by Raman and IR spectra, and by quantum-chemical calculations at various levels of theory. All the data obtained show that the four-membered ring of 1 is puckered, the ring puckering mode being 80 cm–1 and the barrier to planarity 1.76 kcal/mol (617 cm–1). Temperature investigations of the Raman spectrum have shown that the liquid 1 solidifies into a plastic mesophase at ∼210 K and crystallizes below ∼110 K. Strain energies (SEs) for 1, the parent molecule 1,2-disilacyclobutane (2), and, for comparison, their 1,3-isomers (3 and 4) were estimated as enthalpies of corresponding homodesmic reactions taken with a reversed sign. These values (in kcal/mol) for 1 (8.6) and 2 (12.4) appeared lower than those for 3 (18.3) and 4 (19.6). To rationalize these results, a QTAIM topological analysis of electron density distribution was carried out for 1–4. Examination of the molecular graphs has demonstrated that the Si–Si bond paths (BPs) in 1 and 2 are significantly bent (“banana” bonds), thus decreasing the SE of these molecules. The corresponding Si–Si BP lengths are increased by Δ ≈ 0.03 Å in comparison to the corresponding endocyclic Si–Si interatomic distances, while the Si–C BPs in all four molecules are nearly straight lines (Δ ≈ 0.002 Å). Monitoring of the process of 1 polymerization on heating to room temperature has revealed that this process is not spontaneous, as was supposed previously, but is initiated by minor radical impurities. Indeed, the value of the ring-opening enthalpy for 1 was calculated as 70 kcal/mol, too high for spontaneous thermal polymerization to occur.

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Section: Resultsmentioning

confidence: 97%

“…As a possible mechanism of 1 polymerization, Gusel’nikov et al − , proposed thermal ring opening. However, this mechanism can now be excluded on the following grounds.…”

Section: Resultsmentioning

confidence: 99%