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Marcel Gielen
Free University of Brussels
217Publications
35H-index
4,795Citations
Publications 214
Newest
#1Marcel Gielen (ULB: Université libre de Bruxelles)H-Index: 35
#2Jacques Nasielski (ULB: Université libre de Bruxelles)H-Index: 10
8 CitationsSource
#1Marcel Gielen (Free University of Brussels)H-Index: 35
#2Jacques Nasielski (Free University of Brussels)H-Index: 10
Last.Gilbert Vandendunghen (Free University of Brussels)H-Index: 2
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Iodine cleavage of the metal-metal bond in hexasubstituted dimetals of the fourth group has been studied kinetically. The reactivities of disiliciums, digermaniums, ditins and mixed dimetals are discussed in function of the substituents and of the metals involved in the metal-metal bond.
6 CitationsSource
#1Stéphane Boué (ULB: Université libre de Bruxelles)H-Index: 8
#2Marcel Gielen (ULB: Université libre de Bruxelles)H-Index: 35
Last.Jacques Nasielski (ULB: Université libre de Bruxelles)H-Index: 10
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The P.M.R. spectra of 29 compounds containing a Sn(CH3)3 group have been recorded. The chemical shifts and the coupling constants are related to Tafťs and Hammetťs σ sequences. For polycyclic aromatic tin derivatives, the shift is influenced by the ring current. Copyright © 1967 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim
5 CitationsSource
#1C. Deblandre (ULB: Université libre de Bruxelles)H-Index: 1
#2Marcel Gielen (ULB: Université libre de Bruxelles)H-Index: 35
Last.Jacques Nasielski (ULB: Université libre de Bruxelles)H-Index: 10
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Symmetrical tetraalkyltins react with chromic anhydryde to yield aldehydes and acids. The rates have been measured, and the kinetic results suggest a five-membered transition state for this bimolecular electrophilic substitution on a saturated carbon atom.
8 CitationsSource
#1Marcel Gielen (ULB: Université libre de Bruxelles)H-Index: 35
#2Jacques Nasielski (ULB: Université libre de Bruxelles)H-Index: 10
The mass spectra of a series of aryltrimethyltins are described and analysed. The main features are: a relatively weak molecular ion, a very important ArSnMe2+ ion (base peak), a low intensity ArSnMe+ fragment and a non negligible ArSn+ peak. These findings may be related to the well known stable valence states of tin (IVSn and IISn) and the unfavourable IIISn and ISn states. Whereas a methyl group is easier to cleave from the ArSnMe3+ ion than the phenyl radical, n-butyl seems to be more strong...
20 CitationsSource
Matrix representations are given to describe how octahedral and trigonal prismatic stereoisomers are converted into one another.
6 CitationsSource
#1Marcel Gielen (ULB: Université libre de Bruxelles)H-Index: 35
#2Jacques Nasielski (ULB: Université libre de Bruxelles)H-Index: 10
Last.R. Yernaux (ULB: Université libre de Bruxelles)H-Index: 1
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Trialkyltin bromides are found to act as Lewis acids towards iodide ions. Equilibrium constants for the complexation in acetone solution are reported. Copyright © 1963 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim
10 CitationsSource
#1Marcel Gielen (Free University of Brussels)H-Index: 35
#2Marie-Rose Barthels (Free University of Brussels)H-Index: 1
Last.Jacques Nasielski (Free University of Brussels)H-Index: 10
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The J(Sn‐CH2) coupling constants in a series of benzyltin derivatives are examined as a function of the substituents. A J vs Σσ* graph shows three equidistant and parallel lines. The mass spectra of these compounds confirm the fragmentation rules described before. Copyright © 1971 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim
8 CitationsSource
#1Marcel Gielen (ULB: Université libre de Bruxelles)H-Index: 35
#2Jacques Nasielski (ULB: Université libre de Bruxelles)H-Index: 10
The rates of the reactions of tetraalkyltins (R4Sn) with bromine in dimethylformamide and acetic acid solutions and with iodine in acetic acid are found to depend on steric effects (kMe> kEt > knPr), caused by the R3Sn leaving group. Trialkyltin bromides (R3SnBr) are cleaved by bromine in acetic acid in a reactivity sequence (kMe knPr) which is best explained by an increasing importance of inductive effects.
13 CitationsSource
#1Klaus Jurkschat (MLU: Martin Luther University of Halle-Wittenberg)H-Index: 34
#2Alfred Tzschach (MLU: Martin Luther University of Halle-Wittenberg)H-Index: 22
Last.Rudolph Willem (Vrije Universiteit Brussel)H-Index: 38
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The compound 5-chloro-1-aza-5-silatricyclo[3.3.3.01,5]undecane (C9H18NSiCl) combines with water to form an association complex with the formula C9H18NSiCl·H2O. Proton NMR studies at various temperatures, concentrations and magnetic fields indicate that this compound exists in solution as an equilibrium mixture of the initial chloride and its association complex with water, a structure for which is proposed. Evidence is provided against a rigid hexacoordinate complex. The equilibrium is shown to ...
5 CitationsSource
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