Synthesis and reactivity of organotantalum complexes containing nitrogen ligation

Persistent Link:
http://hdl.handle.net/10150/290672
Title:
Synthesis and reactivity of organotantalum complexes containing nitrogen ligation
Author:
Fox, Peter Anthony, 1965-
Issue Date:
1996
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
This work examines various aspects of hydrodenitrogenation catalysis. Various tetrahydroquinolinyl (THQ) and indolinyl (DHI) complexes of tantalum were synthesized including: Ta(THQ)ₓCl₅₋ₓ(x = 1 to 5), Ta(DHI) ₓCl₅₋ₓ(THF) (x = 1 and 2). In addition, THQ and DHI complexes containing aryloxide (OAr = 2,6-diisopropylphenoxide) and alkyl complexes were also synthesized: Ta(THQ)(OAr)Cl₃(OEt₂), Ta(THQ)₂(OAr)₂Cl, Ta(THQ)(OAr)R₃Cl (R = Me and Et), Ta(THQ)₂(OAr)₂R (R = Me and Et), Ta(DHI)(OAr)Cl₃(OEt₂), and Ta(DHI)₂(OAr)₂Cl. The effects of sulfur ligation versus oxygen ligation was examined by comparison of the crystal structures of Ta[η²(N,C)-2,4,6-tri-t-butylpyridinel](OAr)₂(OᵗBu) and Ta[η²(N,C)-2,4,6-tri-t-butylpyridine](OAr)₂(SᵗBu). The sulfur ligand donates less π density to the metal center, resulting in a longer Ta-C bond for the pyridine ligand. The arene complexes (η⁶C₆Me₆)Ta(OAr)(SAr')Cl and (η⁶-C₆Me₆)Ta(OAr)(SAr'')Cl were also synthesized. These arene-thiolate complexes do not appear to bind quinoline, unlike the oxygen analogs A number of Ta(η⁴-diene)(OAr)₃ complexes were synthesized (diene = butadiene, isoprene, 2,3-dimethylbutadiene, 1,3-cyclohexadiene) and their reactivity with respect to nitriles examined. Nitriles typically insert into Ta(η⁴-isoprene)(OAr)₃ to form (ArO₃Ta(CH₂CHCMeCH₂CRN) which can then be thermally rearranged to (ArO) ₃Ta(=NCRCH₂CHCMeCH₂) (R = Me, Ph, ᵗBu). Similar reactivity is observed with butadiene and 2,3-dimethylbutadiene diene complexes. The Ta(η⁴-C₄H₆)(OAr)₃ complex is also capable of inserting two nitriles to form (ArO)₃Ta(NCRCH₂CHCHCH₂CRN), whereas Ta(η⁴-1,3-cyclohexadiene)(OAr)₃ only forms the bis-insertion product. Aspects of the formation of the above complexes with specific concentration on the tantalum-nitrogen interactions are presented.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Chemistry, Organic.; Chemistry, Organic.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Chemistry
Degree Grantor:
University of Arizona
Advisor:
Wigley, David E.

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleSynthesis and reactivity of organotantalum complexes containing nitrogen ligationen_US
dc.creatorFox, Peter Anthony, 1965-en_US
dc.contributor.authorFox, Peter Anthony, 1965-en_US
dc.date.issued1996en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThis work examines various aspects of hydrodenitrogenation catalysis. Various tetrahydroquinolinyl (THQ) and indolinyl (DHI) complexes of tantalum were synthesized including: Ta(THQ)ₓCl₅₋ₓ(x = 1 to 5), Ta(DHI) ₓCl₅₋ₓ(THF) (x = 1 and 2). In addition, THQ and DHI complexes containing aryloxide (OAr = 2,6-diisopropylphenoxide) and alkyl complexes were also synthesized: Ta(THQ)(OAr)Cl₃(OEt₂), Ta(THQ)₂(OAr)₂Cl, Ta(THQ)(OAr)R₃Cl (R = Me and Et), Ta(THQ)₂(OAr)₂R (R = Me and Et), Ta(DHI)(OAr)Cl₃(OEt₂), and Ta(DHI)₂(OAr)₂Cl. The effects of sulfur ligation versus oxygen ligation was examined by comparison of the crystal structures of Ta[η²(N,C)-2,4,6-tri-t-butylpyridinel](OAr)₂(OᵗBu) and Ta[η²(N,C)-2,4,6-tri-t-butylpyridine](OAr)₂(SᵗBu). The sulfur ligand donates less π density to the metal center, resulting in a longer Ta-C bond for the pyridine ligand. The arene complexes (η⁶C₆Me₆)Ta(OAr)(SAr')Cl and (η⁶-C₆Me₆)Ta(OAr)(SAr'')Cl were also synthesized. These arene-thiolate complexes do not appear to bind quinoline, unlike the oxygen analogs A number of Ta(η⁴-diene)(OAr)₃ complexes were synthesized (diene = butadiene, isoprene, 2,3-dimethylbutadiene, 1,3-cyclohexadiene) and their reactivity with respect to nitriles examined. Nitriles typically insert into Ta(η⁴-isoprene)(OAr)₃ to form (ArO₃Ta(CH₂CHCMeCH₂CRN) which can then be thermally rearranged to (ArO) ₃Ta(=NCRCH₂CHCMeCH₂) (R = Me, Ph, ᵗBu). Similar reactivity is observed with butadiene and 2,3-dimethylbutadiene diene complexes. The Ta(η⁴-C₄H₆)(OAr)₃ complex is also capable of inserting two nitriles to form (ArO)₃Ta(NCRCH₂CHCHCH₂CRN), whereas Ta(η⁴-1,3-cyclohexadiene)(OAr)₃ only forms the bis-insertion product. Aspects of the formation of the above complexes with specific concentration on the tantalum-nitrogen interactions are presented.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectChemistry, Organic.en_US
dc.subjectChemistry, Organic.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWigley, David E.en_US
dc.identifier.proquest9720625en_US
dc.identifier.bibrecord.b34546649en_US
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