THE NATURE OF ORGANOSULFUR LONE PAIR ORBITAL INTERACTIONS WITH TRANSITION METAL D-ORBITALS.

Persistent Link:
http://hdl.handle.net/10150/183814
Title:
THE NATURE OF ORGANOSULFUR LONE PAIR ORBITAL INTERACTIONS WITH TRANSITION METAL D-ORBITALS.
Author:
ASHBY, MICHAEL THOMAS.
Issue Date:
1986
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 research has been directed at the study of organosulfur frontier orbital interactions with transition metal d-orbitals. Two novel thioether complexes tricarbonyl(1,4,7-trithiacyclononane)molybdenum(O) and tricarbonyl(2,5,8-trithianonane)molybdenum(O), have been prepared and structurally characterized by single crystal x-ray crystallography. The facial configuration of the carbonyl ligands provides a unique point of reference for describing the two polythioether ligands in terms of the free ligand's frontier orbitals. The relative carbonyl stretching frequencies of the two metal complexes indicate that 1,4,7-trithiacyclononane is a poorer donor than 2,5,8-trithianonane. This result is explained in terms of mechanical constraints placed on the mesocyclic polythioether which are absent in its acyclic analogue. The coordinatively unsaturated species (n⁵-C₅H₅)MO(NO)(SC₆H₅)₂ has been characterized by x-ray crystallography and its electronic structure has been modeled using Fenske-Hall molecular orbital calculations. The monomeric nature and chemical inertness of (n⁵-C₅H₅)MO(NO)(SC₆H₅)₂ are attributed to dπ-pπ bonding between the thiolate ligands and an empty molybdenum dπ orbital. The dπ-pπ interaction simultaneously strengthens the metal thiolate bond and makes the complex less susceptible to nucleophilic attack by raising the energy of the LUMO. The rotational orientations of the thiolate ligands observed in the solid state support this electronic model. For (n⁵-C₅H₅)Fe(CO)₂SR, the dπ-pπI antibonding interaction between the thiolate ligand and the metal has been modeled using Fenske-Hall molecular orbital calculations and experimentally investigated by photoelectron spectroscopy. The calculations predict that the HOMO is metal-sulfurn-antibonding and largely sulfur 3p in character. The observed HOMO ionization energies of (n⁵-C₅H₅)Fe(CO)₂SC₆H₄-p-Z; Z = OMe, H, Cl, CF₃, N0₂; correlate with several chemical properties including the rate of electrophilic attack on the sulfur by alkyl halides to give the thioether complex [(n⁵-C₅H₅)Fe(CO)₂(SR₂)]X and by electron-deficient alkynes to give the heterometallacycle (n⁵-C₅H₅)(CO)FeS(R)-C=C=C=0. The latter reaction is compared to the similar reaction of alkenes and alkynes with (n⁵-C₅H₅)Fe(CO)₂PR₂ to give (n⁵-C₅H₅)(CO)FeP(R)₂-C=C-C=0. X-ray crystal structures of one of the sulfur-containing and one of the phosphorus-containing heterometallacycles have been obtained.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Organosulfur compounds.; Ligands -- Reactivity.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Chemistry; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Enemark, John

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleTHE NATURE OF ORGANOSULFUR LONE PAIR ORBITAL INTERACTIONS WITH TRANSITION METAL D-ORBITALS.en_US
dc.creatorASHBY, MICHAEL THOMAS.en_US
dc.contributor.authorASHBY, MICHAEL THOMAS.en_US
dc.date.issued1986en_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 research has been directed at the study of organosulfur frontier orbital interactions with transition metal d-orbitals. Two novel thioether complexes tricarbonyl(1,4,7-trithiacyclononane)molybdenum(O) and tricarbonyl(2,5,8-trithianonane)molybdenum(O), have been prepared and structurally characterized by single crystal x-ray crystallography. The facial configuration of the carbonyl ligands provides a unique point of reference for describing the two polythioether ligands in terms of the free ligand's frontier orbitals. The relative carbonyl stretching frequencies of the two metal complexes indicate that 1,4,7-trithiacyclononane is a poorer donor than 2,5,8-trithianonane. This result is explained in terms of mechanical constraints placed on the mesocyclic polythioether which are absent in its acyclic analogue. The coordinatively unsaturated species (n⁵-C₅H₅)MO(NO)(SC₆H₅)₂ has been characterized by x-ray crystallography and its electronic structure has been modeled using Fenske-Hall molecular orbital calculations. The monomeric nature and chemical inertness of (n⁵-C₅H₅)MO(NO)(SC₆H₅)₂ are attributed to dπ-pπ bonding between the thiolate ligands and an empty molybdenum dπ orbital. The dπ-pπ interaction simultaneously strengthens the metal thiolate bond and makes the complex less susceptible to nucleophilic attack by raising the energy of the LUMO. The rotational orientations of the thiolate ligands observed in the solid state support this electronic model. For (n⁵-C₅H₅)Fe(CO)₂SR, the dπ-pπI antibonding interaction between the thiolate ligand and the metal has been modeled using Fenske-Hall molecular orbital calculations and experimentally investigated by photoelectron spectroscopy. The calculations predict that the HOMO is metal-sulfurn-antibonding and largely sulfur 3p in character. The observed HOMO ionization energies of (n⁵-C₅H₅)Fe(CO)₂SC₆H₄-p-Z; Z = OMe, H, Cl, CF₃, N0₂; correlate with several chemical properties including the rate of electrophilic attack on the sulfur by alkyl halides to give the thioether complex [(n⁵-C₅H₅)Fe(CO)₂(SR₂)]X and by electron-deficient alkynes to give the heterometallacycle (n⁵-C₅H₅)(CO)FeS(R)-C=C=C=0. The latter reaction is compared to the similar reaction of alkenes and alkynes with (n⁵-C₅H₅)Fe(CO)₂PR₂ to give (n⁵-C₅H₅)(CO)FeP(R)₂-C=C-C=0. X-ray crystal structures of one of the sulfur-containing and one of the phosphorus-containing heterometallacycles have been obtained.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectOrganosulfur compounds.en_US
dc.subjectLigands -- Reactivity.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineChemistryen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorEnemark, Johnen_US
dc.contributor.committeememberLichtenberger, Dennisen_US
dc.contributor.committeememberGlass, Richarden_US
dc.identifier.proquest8615820en_US
dc.identifier.oclc697532724en_US
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