- FIVE-COORDINATE COMPLEXES OF 2,2-DIBUTYL-1,3,2-DIOXASTANNOLANS
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2,2-Dibutyl-1,3,2-dioxastannolans, Bu2Sn(OCR2)2, unlike the dioxastannanans, Bu2Sn(OCR2)2CR2, or the acyclic dialkoxides, Bu2Sn(OR)2, react with ligands L, such as pyridine, dimethyl formamide, dimethyl sulphoxide, sulpholane, and tetrahydrofuran to form a series of solid complexes, Bu2Sn(OCR2)2L.Under reduced pressure, the ligands, L, are lost, and the dioxastannolans are regenerated.Measurements of IR, 1H and 119Sn NMR, and Moessbauer spectra, and of molecular weights in solution, imply that the complexes have a trigonal bipyramidal configuration, with equatorial butyl groups, apical ligand L, and the dioxastannolan ring bridging apical and equatorial positions.It is suggested that the relative stability of these complexes results from minimisation of angle strain in the 5-membered ring.
- Davies, Alwyn G.,Price, Allan J.
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- Etude Structurale de Bisalcoxy et de Dialcoxyetains Derives de l'Ethyleneglycol et du Pyridinedimethanol-2,6. Mise en Evidence d'une Forme Stannatrane pour un Stannadioxocanne Pyridinique
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119Sn NMR is a good medium for determining the coordination number of tin atoms and association phenomena involved.By this technique the structures of three monomeric linear-bis-alkoxy-tin(IV) (R3SnO-A-OSnR3) derivatives of ethyleneglycol and pyridine-2,6-dimethanol have been determined (R= n-Bu, Ph).In the case of cyclic dialkyltins the ethyleneglycol derivative shows a variable temperature SnV dimeric SnIV monomeric equilibrium (ΔH 64 kJ mol-1), while the pyridinylstannadioxocane contains a SnV stannatrane as determined by its 1H, 13C and 119Sn NMR and mass spectra, and by cryogenic measurements.The pyridinylstannadioxocane is the only known stannatrane containing a pyridinic nitrogen atom.
- Picard, C.,Tisnes, P.,Cazaux, L.
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- Oligomerization equilibria and dynamics of 2,2-di-n-butyl-1,3,2-dioxastannolanes
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The 119Sn and 13C NMR spectra of solutions of 2,2-di-n-butyl-1,3,2-dioxastannolane (1) and a number of its symmetrical derivatives in nonpolar solvents have been studied as functions of temperature and concentration. The compounds studied included (1S,6S)-8,8-di-n-butyl-7,9,8-dioxastannabicyclo[4.3.0]nonane (2), obtained from di-n-butyltin oxide and (S,S)-1,2-cyclohexanediol. A new method of resolution of trans-1,2-cyclohexanediol has been developed. Solutions of 1, 2, and related derivatives of disecondary diols were found to contain mixtures of oligomers that have been identified as dimers, trimers, tetramers, and pentamers. In contrast to earlier work, no evidence for the presence of monomers was obtained. The compositions of the mixtures are extremely temperature dependent; trimers and tetramers are the major constituents below -20 °C, but dimers increasingly dominate as the temperature is raised. Thermodynamic parameters for the equilibria of 1 and 2 have been measured. A derivative of a ditertiary diol, 2,2-di-n-butyl-4,4,5,5-tetramethyl-1,3.2-dioxastannolane, exists in nonpolar solvents predominantly as a dimer over the temperature range studied, from -60 to +80 °C. Activation parameters for a process in this dimer that causes the 13C NMR signals of the pairs of nonequivalent methyl carbons to coalesce have been determined by total line shape analysis. A series of related reversible associative processes involving dimers, trimers, tetramers, pentamers, and possibly monomers and hexamers accounts for the changes observed in the NMR spectra with temperature.
- Grindley, T. Bruce,Thangarasa, Rasiah
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- PROCESS FOR REGIOSELECTIVE DIOL MONO-TOSYLATION USING CATALYTIC AMOUNTS OF A GENERIC DIALKYLTINACETAL
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The present invention concerns the use of dibutyl tin oxide for regioselective catalytic diol mono-tosylat ion at a concentration lower than 2 mol%. The present invention also concerns the use of a generic acetal compound of Formula (Ic) in a catalytic process for regioselective diol mono-tosylat ion, wherein Y is selected from the group of C1-6alkyl, phenyl and benzyl. The concentration of the generic acetal compound of Formula (Ic) is less than about 2 mol%, preferably ranges between about 2 mol% and about 0.0005 mol%, preferably ranges between about 0.1 mol% and about 0.005 mol%.
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Page/Page column 7-8
(2008/12/05)
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- Une methode simple et efficace de preparation des dihydrures organostanniques
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A new and efficient method of preparation of R2SnH2 is proposed.Organodioxastannolanes were used as starting materials, these compounds being easily obtained by azeotropic distillation of water from a solution of diorganotin oxides and 1,2 diols in cyclohexane.Their reduction by commercial BH3/THF complex gave raw dialkyltin dihydrides with excellent yields and high purity degrees. Keywords: Borane; Reduction; Dialkylstannanes; 1,3-dioxa-2-stannolanes; Synthesis
- Deleuze, H.,Maillard, B.
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p. C14 - C17
(2007/10/02)
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- TELOMERIZATION OF POLY(DIALKYLTIN OXIDE) AND ALKANE- OR ALKENE-1,2-DIOLS: THE IDENTIFICATION OF CYCLIC DERIVATIVES OF OLIGOMERIC DIBUTYLTIN OXIDE
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1,1-Dibutyl-1,3,2-dioxastannolan and 1,1-dibutyl-4,5-diphenyl-1,3,2-dioxastannolen undergo a telomerization reaction with dibutyltin oxide to give a series of oligomers which have been isolated and characterised.
- Davies, Alwyn G.,Hawari, Jalal A.-A.,Hua-De, Pan
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p. 203 - 208
(2007/10/02)
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- THE REACTION OF 1,3,2-DIOXASTANNOLANS WITH DIACYL CHLORIDES: DECARBONYLATION IN THE REACTION WITH OXALYL CHLORIDE
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2,2-Dibutyl-1,3,2-dioxastannolans react with carbonyl chloride to give the corresponding ethylene carbonates, and with malonyl chloride or succinyl chloride to give the oligomeric malonates or succinates.The reaction of oxalyl chloride, however, depends of the number of methyl substituents carried by the carbon atoms of the ring; with none, ethylene oxalate is essentially the only product, but increasing methylation induces the evolution of carbon monoxide and the formation of the ethylene carbonate until, with four methyl substituents, only the carbonate of pinacol, and no oxalate is formed, providing a striking example of the Thorpe-Ingold effect.The mechanism of this decarbonylation is discussed.
- Davies, Alwyn G.,Hua-De, Pan,Hawari, Jalal A. -A.
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p. 251 - 260
(2007/10/02)
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