Studies on synthesis and reactions of anionic P-NR2/P-OR organophosphane complexesSearching for the boundary between phosphanide and phosphinidenoid complexes
Studies on synthesis and reactions of anionic P-NR2/P-OR organophosphane complexes
Searching for the boundary between phosphanide and phosphinidenoid complexes
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DissertationDate of Exam
25.10.2011Date of Publication
15.11.2011Advisor
Streubel, RainerCo-Referee
Beck, JohannesMetadata
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Abstract
This thesis was focused on the studies of synthesis and reactivity of the first Li/OR phosphinidenoid complexes, in pursuit of the boundary between phosphanide complex and phosphinidenoid complex chemistry.
First, the three modified methodologies were used to generate the precursors – P-functional phosphane complexes. Then subjection of P-functional phosphane complexes to LDA (lithium diisopropylamide) in presence of 12-crown-4 at –78°C led to the Li/OR phosphinidenoid complexes: bearing a downfield 31P chemical shift, combined with a small tungsten-phosphorus coupling constants. But an unexpected decomposition product was observed in the deprotonation of P-acetyl phosphane complex, in which a P–H and a P–O–Li moiety were contained in one molecule. Again, the deprotonation of P-acetyl phosphane complex without 12-crown-4 gave rise to the first observation of phosphorus-lithium coupling (quart, δ = 220 ppm, 1J(P,Li) = 40.7 Hz).
Moreover, the effects of reaction conditions (e.g. different bases, different co-ligands, etc) on the NMR signature and thermal stability of Li/OR phosphinidenoid complexes were investigated. However, in all of cases, the 31P NMR signature showed little (or no) difference, therefore it was deduced that the Li/OR phosphinidenoid complexes might be an ion pair complex, in which metal cations bear the co-ligand (such as 12-crown-4 or cryptand[2.1.1]) or solvents and P-OR phosphanide complexes as anions. This assumption was confirmed additionally by the single-crystal X-ray analysis of [N,N-di-tert-butyl-imidazolium] stabilized phosphinidenoid complex.
In the chapter 7, reactivity studies of Li/OR phosphinidenoid complexes were introduced. In most cases, the “phosphanide-type” reactivity was displayed. Only in the thermal reaction of Li/OPh derivative, the “phosphinidene-type” reactivity was revealed, which was explained by the observation of cyclotriphosphane compound, although the mechanism was not clear. Besides, for Li/OMe phosphinidenoid complex, the redox reactivity was observed and also confirmed by the ESR measurement.
First, the three modified methodologies were used to generate the precursors – P-functional phosphane complexes. Then subjection of P-functional phosphane complexes to LDA (lithium diisopropylamide) in presence of 12-crown-4 at –78°C led to the Li/OR phosphinidenoid complexes: bearing a downfield 31P chemical shift, combined with a small tungsten-phosphorus coupling constants. But an unexpected decomposition product was observed in the deprotonation of P-acetyl phosphane complex, in which a P–H and a P–O–Li moiety were contained in one molecule. Again, the deprotonation of P-acetyl phosphane complex without 12-crown-4 gave rise to the first observation of phosphorus-lithium coupling (quart, δ = 220 ppm, 1J(P,Li) = 40.7 Hz).
Moreover, the effects of reaction conditions (e.g. different bases, different co-ligands, etc) on the NMR signature and thermal stability of Li/OR phosphinidenoid complexes were investigated. However, in all of cases, the 31P NMR signature showed little (or no) difference, therefore it was deduced that the Li/OR phosphinidenoid complexes might be an ion pair complex, in which metal cations bear the co-ligand (such as 12-crown-4 or cryptand[2.1.1]) or solvents and P-OR phosphanide complexes as anions. This assumption was confirmed additionally by the single-crystal X-ray analysis of [N,N-di-tert-butyl-imidazolium] stabilized phosphinidenoid complex.
In the chapter 7, reactivity studies of Li/OR phosphinidenoid complexes were introduced. In most cases, the “phosphanide-type” reactivity was displayed. Only in the thermal reaction of Li/OPh derivative, the “phosphinidene-type” reactivity was revealed, which was explained by the observation of cyclotriphosphane compound, although the mechanism was not clear. Besides, for Li/OMe phosphinidenoid complex, the redox reactivity was observed and also confirmed by the ESR measurement.
Classification (DDC)
540 ChemieDuan, Lili: Studies on synthesis and reactions of anionic P-NR2/P-OR organophosphane complexes : Searching for the boundary between phosphanide and phosphinidenoid complexes. - Bonn, 2011. - Dissertation, Rheinische Friedrich-Wilhelms-Universität Bonn.
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5N-26980
Online-Ausgabe in bonndoc: https://nbn-resolving.org/urn:nbn:de:hbz:5N-26980
@phdthesis{handle:20.500.11811/5061,
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5N-26980,
author = {{Lili Duan}},
title = {Studies on synthesis and reactions of anionic P-NR2/P-OR organophosphane complexes : Searching for the boundary between phosphanide and phosphinidenoid complexes},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2011,
month = nov,
note = {This thesis was focused on the studies of synthesis and reactivity of the first Li/OR phosphinidenoid complexes, in pursuit of the boundary between phosphanide complex and phosphinidenoid complex chemistry.
First, the three modified methodologies were used to generate the precursors – P-functional phosphane complexes. Then subjection of P-functional phosphane complexes to LDA (lithium diisopropylamide) in presence of 12-crown-4 at –78°C led to the Li/OR phosphinidenoid complexes: bearing a downfield 31P chemical shift, combined with a small tungsten-phosphorus coupling constants. But an unexpected decomposition product was observed in the deprotonation of P-acetyl phosphane complex, in which a P–H and a P–O–Li moiety were contained in one molecule. Again, the deprotonation of P-acetyl phosphane complex without 12-crown-4 gave rise to the first observation of phosphorus-lithium coupling (quart, δ = 220 ppm, 1J(P,Li) = 40.7 Hz).
Moreover, the effects of reaction conditions (e.g. different bases, different co-ligands, etc) on the NMR signature and thermal stability of Li/OR phosphinidenoid complexes were investigated. However, in all of cases, the 31P NMR signature showed little (or no) difference, therefore it was deduced that the Li/OR phosphinidenoid complexes might be an ion pair complex, in which metal cations bear the co-ligand (such as 12-crown-4 or cryptand[2.1.1]) or solvents and P-OR phosphanide complexes as anions. This assumption was confirmed additionally by the single-crystal X-ray analysis of [N,N-di-tert-butyl-imidazolium] stabilized phosphinidenoid complex.
In the chapter 7, reactivity studies of Li/OR phosphinidenoid complexes were introduced. In most cases, the “phosphanide-type” reactivity was displayed. Only in the thermal reaction of Li/OPh derivative, the “phosphinidene-type” reactivity was revealed, which was explained by the observation of cyclotriphosphane compound, although the mechanism was not clear. Besides, for Li/OMe phosphinidenoid complex, the redox reactivity was observed and also confirmed by the ESR measurement.},
url = {https://hdl.handle.net/20.500.11811/5061}
}
urn: https://nbn-resolving.org/urn:nbn:de:hbz:5N-26980,
author = {{Lili Duan}},
title = {Studies on synthesis and reactions of anionic P-NR2/P-OR organophosphane complexes : Searching for the boundary between phosphanide and phosphinidenoid complexes},
school = {Rheinische Friedrich-Wilhelms-Universität Bonn},
year = 2011,
month = nov,
note = {This thesis was focused on the studies of synthesis and reactivity of the first Li/OR phosphinidenoid complexes, in pursuit of the boundary between phosphanide complex and phosphinidenoid complex chemistry.
First, the three modified methodologies were used to generate the precursors – P-functional phosphane complexes. Then subjection of P-functional phosphane complexes to LDA (lithium diisopropylamide) in presence of 12-crown-4 at –78°C led to the Li/OR phosphinidenoid complexes: bearing a downfield 31P chemical shift, combined with a small tungsten-phosphorus coupling constants. But an unexpected decomposition product was observed in the deprotonation of P-acetyl phosphane complex, in which a P–H and a P–O–Li moiety were contained in one molecule. Again, the deprotonation of P-acetyl phosphane complex without 12-crown-4 gave rise to the first observation of phosphorus-lithium coupling (quart, δ = 220 ppm, 1J(P,Li) = 40.7 Hz).
Moreover, the effects of reaction conditions (e.g. different bases, different co-ligands, etc) on the NMR signature and thermal stability of Li/OR phosphinidenoid complexes were investigated. However, in all of cases, the 31P NMR signature showed little (or no) difference, therefore it was deduced that the Li/OR phosphinidenoid complexes might be an ion pair complex, in which metal cations bear the co-ligand (such as 12-crown-4 or cryptand[2.1.1]) or solvents and P-OR phosphanide complexes as anions. This assumption was confirmed additionally by the single-crystal X-ray analysis of [N,N-di-tert-butyl-imidazolium] stabilized phosphinidenoid complex.
In the chapter 7, reactivity studies of Li/OR phosphinidenoid complexes were introduced. In most cases, the “phosphanide-type” reactivity was displayed. Only in the thermal reaction of Li/OPh derivative, the “phosphinidene-type” reactivity was revealed, which was explained by the observation of cyclotriphosphane compound, although the mechanism was not clear. Besides, for Li/OMe phosphinidenoid complex, the redox reactivity was observed and also confirmed by the ESR measurement.},
url = {https://hdl.handle.net/20.500.11811/5061}
}
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