- INFRARED SPECTROSCOPIC STUDY OF VERY LOW PRESSURE PYROLYSIS PRODUCTS OF CYCLOSILTHIANES AND 3,3-DIMETHYL-3-SILATHIETANE ISOLATED IN ARGON MATRICES. A NEW SOURCE OF 1,1-DIMETHYL-1-SILAETHYLENE (Me2Si=CH2), THIOFORMALDEHYDE (H2C=S) AND DIMETHYLSILANTHIONE (Me2Si=S)
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The products of very low pressure pyrolysis (VLPP) of hexamethylcyclotrisilthiane (I), tetramethylcyclodisilthiane (II) and 3,3-dimethyl-3-silathietane (III) were isolated in Ar matrices and were studied by IR spectroscopy.The only pyrolysis product of I was cyclosilthiane II, a dimer of transient dimethylsilanthione (Me2Si=S) (IV).The starting material was recovered on pyrolysis of II.Thermal decomposition of III involves three intermediate unsaturated compounds: dimethylsilaethylene (Me2Si=CH2) (V) and thioformaldehyde (H2C=S) (VI), both isolated in Ar matrix at 10 K, as well as silanthione IV fixed in the matrix in a form of the cyclic diemr II.The latter was also observed in the study of copyrolysis of 1,1-dimethyl-1-silacyclobutane and thietane, being authentic sources of intermediates V and VI.IR spectra of starting compounds I, II and III isolated in Ar matrices were obtained.The theoretical structure of IV and force constant F(Si=S) were determined by the CNDO/2 method.With regard to CNDO/2 errors, Si=S bond distance and F(Si=S) are equal to 1.993 Angstroem and 4.72 mdyn/Angstroem, respectively.Calculation of normal vibrations resulted in the following values of vibrational frequencies of dimethylsilanthione (cm-1): 884 νs(SiC2) (A1), 735 νas(SiC2) (B2), 626 νs(Si=S) (A1), 200 1).
- Gusel'Nikov, L.E.,Volkova, V.V.,Avakyan, V.G.,Nametkin, N.S.,Voronkov, M.G.,et. al.
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- Dithiaphosphagermetannes-1,3,2,4 et dithiaphosphadigermolannes-1,4,5,2,3
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The synthesis of the new germylated and phosphorylated heterocycles 2-anisyl-4,4-dimethyl-2-thio-1,3,2,4-dithiaphosphagermetane, (1), and 5-anisyl-2,2,3,3-tetramethyl-5-thio-1,4,5,2,3-dithiaphosphadigermolane, (2), are described.The decomposition of 1 with formation of (Me2GeS)3 and (AnPS2)n is observed at room temperature.At 200 deg C 2 undergoes thermal fragmentation leading to (Me2GeS)3 and (AnPS)n.These results are explained by two mechanisms of decomposition involving formation of transient species and or , respectively.Exchange reactions between 2 and various metal (MIVB) chlorides are described.With Me2SiCl2 the reaction leads to silathione , probably via transient dithiaphosphasiletane.
- Barrau, J.,Amine, M. El,Rima, G.,Satge, J.
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p. 615 - 620
(2007/10/02)
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- METALLA IV-b-PHOSPHOLANNES II-METALLA-2 (OXA-, THIA- ou AZA-)-3 PHOSPHOLANNES
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2-sila-, germa- or stanna- 3-(oxa-, thia- or aza-) phospholanes have been synthesized by reactions of dihalometalla-IV-b compounds with dilithiated β-phosphorus alcohols, thiols or amines HYCH2CH2P(H)Ph (Y=O, S, NMe).Germa- and stanna- heterocycles can also be obtained from germyl- or stannyldiamines and the same β-phosphorus alcohols, thiols or amines. 2-sila 3-(oxa- or thia-) phospholanes are of particular interest for their decomposition reaction leading to silanone or silathione and phosphirane.
- Andriamizaka, J. D.,Escudie, J.,Couret, C.,Satge, J.
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p. 279 - 286
(2007/10/02)
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