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Marcel Gielen
Free University of Brussels
182Publications
34H-index
4,326Citations
Publications 182
Newest
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
Marcel Gielen8
Estimated H-index: 8
(Free University of Brussels),
Jacques Nasielski9
Estimated H-index: 9
(Free University of Brussels),
Gilbert Vandendunghen2
Estimated H-index: 2
(Free University of Brussels)
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 Citations Source Cite
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
C. Deblandre1
Estimated H-index: 1
(ULB: Université libre de Bruxelles),
Marcel Gielen8
Estimated H-index: 8
(ULB: Université libre de Bruxelles),
Jacques Nasielski9
Estimated H-index: 9
(ULB: Université libre de Bruxelles)
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 Citations Source Cite
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
Stéphane Boué7
Estimated H-index: 7
(ULB: Université libre de Bruxelles),
Marcel Gielen8
Estimated H-index: 8
(ULB: Université libre de Bruxelles),
Jacques Nasielski9
Estimated H-index: 9
(ULB: Université libre de Bruxelles)
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 Citations Source Cite
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
Marcel Gielen8
Estimated H-index: 8
(ULB: Université libre de Bruxelles),
Jacques Nasielski9
Estimated H-index: 9
(ULB: Université libre de Bruxelles)
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 Citations Source Cite
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
Marcel Gielen4
Estimated H-index: 4
(VU: VU University Amsterdam)
Matrix representations are given to describe how octahedral and trigonal prismatic stereoisomers are converted into one another.
6 Citations Source Cite
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
Marcel Gielen8
Estimated H-index: 8
(ULB: Université libre de Bruxelles),
Jacques Nasielski9
Estimated H-index: 9
(ULB: Université libre de Bruxelles)
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 Citations Source Cite
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
Marcel Gielen8
Estimated H-index: 8
(ULB: Université libre de Bruxelles),
Jacques Nasielski9
Estimated H-index: 9
(ULB: Université libre de Bruxelles),
R. Yernaux1
Estimated H-index: 1
(ULB: Université libre de Bruxelles)
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 Citations Source Cite
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
Marcel Gielen34
Estimated H-index: 34
(Free University of Brussels),
Marie-Rose Barthels1
Estimated H-index: 1
(Free University of Brussels)
+ 1 AuthorsJacques Nasielski9
Estimated H-index: 9
(Free University of Brussels)
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 Citations Source Cite
Published on Sep 2, 2010in Bulletin des Sociétés Chimiques Belges
Stéphane Boué7
Estimated H-index: 7
(ULB: Université libre de Bruxelles),
Marcel Gielen8
Estimated H-index: 8
(ULB: Université libre de Bruxelles),
Jacques Nasielski9
Estimated H-index: 9
(ULB: Université libre de Bruxelles)
The mass spectra of mixed tetraalkyltins are described and analysed. The fragmentation pattern is in agreement with the hypothesis of prefered Sn(IV) and Sn(II) valence states in the tin‐containing fragments. These states are reached by losing an alkyl radical from the next higher unfavourable valence state, or by losing an alkene or alkane molecule from a favourable valence state. The ease of cleavage of a carbon‐tin bond in the molecular ion parallels the stabilization of the leaving alkyl rad...
31 Citations Source Cite
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