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Reactions of Tp–Os nitrido complexes with the nucleophiles hydroxide and thiosulfate
Reaction of TpOs(N)(OAc) 2 ( 2) with thiosulfate occurs at the nitrido ligand to yield TpOs(NS)(OAc) 2 ( 4). Reaction with hydroxide, however, gives TpOs(N)(OH) 2 ( 3) by a direct substitution of OH − for OAc −, as confirmed by 18O-labeling. The contrasting reactivity of hydroxide with TpOs(N)Cl 2 (...
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Published in: | Inorganica Chimica Acta 2006-06, Vol.359 (9), p.2842-2849 |
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Main Authors: | , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Reaction of TpOs(N)(OAc)
2 (
2) with thiosulfate occurs at the nitrido ligand to yield TpOs(NS)(OAc)
2 (
4). Reaction with hydroxide, however, gives TpOs(N)(OH)
2 (
3) by a direct substitution of OH
− for OAc
−, as confirmed by
18O-labeling. The contrasting reactivity of hydroxide with TpOs(N)Cl
2 (
1),
2,
3, and
4, at the metal versus at a ligand, is described.
The reaction between TpOs(N)Cl
2 (
1) [Tp
=
hydrotris(1-pyrazolyl)borate] and aqueous (
n
Bu
4N)(OH) in THF-
d
8 forms the nitrosyl complex TpOs(NO)Cl
2 (
5) among other products, suggesting an initial hydroxide attack at the nitrido ligand. In contrast, the reaction of the acetate complex TpOs(N)(OAc)
2 (
2) with NaOH in Me
2CO/H
2O yields the osmium bis-hydroxide complex TpOs(N)(OH)
2 (
3), which has been structurally characterized by single-crystal X-ray diffraction. Acetate for hydroxide exchange could occur by ligand substitution or by nucleophilic attack at the carbonyl carbon of the acetate ligands (saponification). Reacting
2 with Na
18OH in H
2
18O/CD
3CN yields predominantly doubly
18O-labeled TpOs(N)(
18OH)
2 (
3-
18
O
2
) and unlabeled acetate, by ESI/MS and
13C{
1H} NMR. This indicates that hydroxide reacts by substitution rather than by attack at the ligand. The reaction of
2 with the softer nucleophile thiosulfate occurs at the nitrido ligand, giving the thionitrosyl complex TpOs(NS)(OAc)
2 (
4). Reacting
4 with NaOH in (CD
3)
2CO/D
2O also generates the bis-hydroxide complex
3. |
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ISSN: | 0020-1693 1873-3255 |
DOI: | 10.1016/j.ica.2005.11.033 |