{"id":{"repo_id":"ubc","oai_identifier":"oai:circle.library.ubc.ca:2429/1315"},"canonical_url":"https://search.dev.ndltd.org/etd/ubc/oai:circle.library.ubc.ca:2429/1315","repository":{"repo_id":"ubc","name":"University of British Columbia","base_url":"http://circle.library.ubc.ca/oai/request"},"display":{"title":"Dinitrogen complexes of titanium and vanadium stabilized by phosphine ligands","abstract":"The goal of the work presented in this thesis is to investigate the preparation of dinitrogen complexes of titanium and vanadium from phosphine-based starting materials. The reactions of TiCl₄, TiCl₃(THF)₃, or VCl₂(TMEDA)₂ with LiN(SiMe₂CH₂PR₂)₂ (R = isopropyl or methyl) yielded the new phosphine complexes TiCl₃[N(SiMe₂CH₂PPri₂)₂] (1), TiCl₃[N(SiMe₂CH₂PMe₂)₂] (2), {TiCl₂[N(SiMe₂CH₂PPri₂)₂]}x (x = 1 or 2) (3), or [(Pri₂PCH₂SiMe₂)₂N]V(μ-Cl)₂Li(TMEDA) (4), respectively. NMR spectroscopy revealed that complexes 1 and 2 have C₂v symmetry. The titanium(III) species, 3, is likely to be a dimer as indicated by mass spectrometry. The structure of the vanadium mono(amido-diphosphine) complex, 4, is suggested to be a lithium-chloride adduct. The reduction of 1 with magnesium powder under dinitrogen resulted in the synthesis of the binuclear titanium dinitrogen complex, {[(Pri₂PCH₂SiMe₂)₂N]TiCl}₂(μ-η¹:η¹-N₂) (5). The unsuccessful reduction of 3 suggests that it is not an intermediate in the synthesis of 5. The most interesting structural feature of 5 is the end-on bound dinitrogen ligand with an N-N bond distance of 1.275 (7) Å, typical of other binuclear end-on bound dinitrogen complexes. The ¹H and ³¹P{¹H} NMR spectra indicate that this dinitrogen complex is fluxional at room temperature by a process that is proposed to involve dissociation of the phophorus atoms of the tridentate ligand and then rotation about the Ti-N (amide) bond, followed by reassociation. The low temperature ³¹P{¹H} NMR spectrum shows an AB quartet which is consistent with the solid state structure. Upon addition of HCl, 0.75 ± 0.04 equivalents of hydrazine and 0.29 ± 0.05 equivalents of dinitrogen were detected. The reaction between VCl₂(TMEDA)₂ and LiN(SiMe₂CH₂PRi₂)₂ under dinitrogen resulted in the formation of a similar vanadium dinitrogen complex, {[(Pri₂PCH₂SiMe₂)₂N]VCl}₂(μ-η¹:η¹-N₂) (7). An alternate synthetic route involves exposure of [(Pri₂PCH₂SiMe₂)₂N]V(μ-Cl)₂Li(TMEDA), 4, in the solid or solution state to one atmosphere of dinitrogen. Complex 7 was also characterized by X-ray crystallography; the end-on dinitrogen bond length is 1.257 (8) Å. Degradation of 7 with HCl produced 0.29 ± 0.04 equivalents of hydrazine.","abstract_html":"The goal of the work presented in this thesis is to investigate the preparation of dinitrogen complexes of titanium and vanadium from phosphine-based starting materials. The reactions of TiCl₄, TiCl₃(THF)₃, or VCl₂(TMEDA)₂ with LiN(SiMe₂CH₂PR₂)₂ (R = isopropyl or methyl) yielded the new phosphine complexes TiCl₃[N(SiMe₂CH₂PPri₂)₂] (1), TiCl₃[N(SiMe₂CH₂PMe₂)₂] (2), {TiCl₂[N(SiMe₂CH₂PPri₂)₂]}x (x = 1 or 2) (3), or [(Pri₂PCH₂SiMe₂)₂N]V(μ-Cl)₂Li(TMEDA) (4), respectively. NMR spectroscopy revealed that complexes 1 and 2 have C₂v symmetry. The titanium(III) species, 3, is likely to be a dimer as indicated by mass spectrometry. The structure of the vanadium mono(amido-diphosphine) complex, 4, is suggested to be a lithium-chloride adduct. The reduction of 1 with magnesium powder under dinitrogen resulted in the synthesis of the binuclear titanium dinitrogen complex, {[(Pri₂PCH₂SiMe₂)₂N]TiCl}₂(μ-η¹:η¹-N₂) (5). The unsuccessful reduction of 3 suggests that it is not an intermediate in the synthesis of 5. The most interesting structural feature of 5 is the end-on bound dinitrogen ligand with an N-N bond distance of 1.275 (7) Å, typical of other binuclear end-on bound dinitrogen complexes. The ¹H and ³¹P{¹H} NMR spectra indicate that this dinitrogen complex is fluxional at room temperature by a process that is proposed to involve dissociation of the phophorus atoms of the tridentate ligand and then rotation about the Ti-N (amide) bond, followed by reassociation. The low temperature ³¹P{¹H} NMR spectrum shows an AB quartet which is consistent with the solid state structure. Upon addition of HCl, 0.75 ± 0.04 equivalents of hydrazine and 0.29 ± 0.05 equivalents of dinitrogen were detected. The reaction between VCl₂(TMEDA)₂ and LiN(SiMe₂CH₂PRi₂)₂ under dinitrogen resulted in the formation of a similar vanadium dinitrogen complex, {[(Pri₂PCH₂SiMe₂)₂N]VCl}₂(μ-η¹:η¹-N₂) (7). An alternate synthetic route involves exposure of [(Pri₂PCH₂SiMe₂)₂N]V(μ-Cl)₂Li(TMEDA), 4, in the solid or solution state to one atmosphere of dinitrogen. Complex 7 was also characterized by X-ray crystallography; the end-on dinitrogen bond length is 1.257 (8) Å. Degradation of 7 with HCl produced 0.29 ± 0.04 equivalents of hydrazine.","abstract_has_math":false,"creators":["Chow, Pauline Chang"],"institution":"University of British Columbia","degree_name":"Master of Science - MSc","degree_level":"master's","degree_discipline":"Chemistry","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1993,"date_issued":"1993","date_published":"1993","updated_at":"2026-07-24T05:07:15Z","subjects":[],"languages":["eng"],"rights":["For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://hdl.handle.net/2429/1315","outbound_label":"Handle","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Chow, Pauline Chang"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1993"]},{"key":"dc:publisher","label":"Institution","values":["University of British Columbia"]},{"key":"dc:type","label":"Dc Type","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Chemistry"]},{"key":"thesis:degree_level","label":"Degree Level","values":["master's"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science - MSc"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of British Columbia"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["eng"]},{"key":"dc:rights","label":"Dc Rights","values":["For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://hdl.handle.net/2429/1315","http://circle.library.ubc.ca/bitstream/2429/1315/3/ubc_1993_spring_chow_pauline_c.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["The goal of the work presented in this thesis is to investigate the preparation of dinitrogen complexes of titanium and vanadium from phosphine-based starting materials. The reactions of TiCl₄, TiCl₃(THF)₃, or VCl₂(TMEDA)₂ with LiN(SiMe₂CH₂PR₂)₂ (R = isopropyl or methyl) yielded the new phosphine complexes TiCl₃[N(SiMe₂CH₂PPri₂)₂] (1), TiCl₃[N(SiMe₂CH₂PMe₂)₂] (2), {TiCl₂[N(SiMe₂CH₂PPri₂)₂]}x (x = 1 or 2) (3), or [(Pri₂PCH₂SiMe₂)₂N]V(μ-Cl)₂Li(TMEDA) (4), respectively. NMR spectroscopy revealed that complexes 1 and 2 have C₂v symmetry. The titanium(III) species, 3, is likely to be a dimer as indicated by mass spectrometry. The structure of the vanadium mono(amido-diphosphine) complex, 4, is suggested to be a lithium-chloride adduct. The reduction of 1 with magnesium powder under dinitrogen resulted in the synthesis of the binuclear titanium dinitrogen complex, {[(Pri₂PCH₂SiMe₂)₂N]TiCl}₂(μ-η¹:η¹-N₂) (5). The unsuccessful reduction of 3 suggests that it is not an intermediate in the synthesis of 5. The most interesting structural feature of 5 is the end-on bound dinitrogen ligand with an N-N bond distance of 1.275 (7) Å, typical of other binuclear end-on bound dinitrogen complexes. The ¹H and ³¹P{¹H} NMR spectra indicate that this dinitrogen complex is fluxional at room temperature by a process that is proposed to involve dissociation of the phophorus atoms of the tridentate ligand and then rotation about the Ti-N (amide) bond, followed by reassociation. The low temperature ³¹P{¹H} NMR spectrum shows an AB quartet which is consistent with the solid state structure. Upon addition of HCl, 0.75 ± 0.04 equivalents of hydrazine and 0.29 ± 0.05 equivalents of dinitrogen were detected. The reaction between VCl₂(TMEDA)₂ and LiN(SiMe₂CH₂PRi₂)₂ under dinitrogen resulted in the formation of a similar vanadium dinitrogen complex, {[(Pri₂PCH₂SiMe₂)₂N]VCl}₂(μ-η¹:η¹-N₂) (7). An alternate synthetic route involves exposure of [(Pri₂PCH₂SiMe₂)₂N]V(μ-Cl)₂Li(TMEDA), 4, in the solid or solution state to one atmosphere of dinitrogen. Complex 7 was also characterized by X-ray crystallography; the end-on dinitrogen bond length is 1.257 (8) Å. Degradation of 7 with HCl produced 0.29 ± 0.04 equivalents of hydrazine."]},{"key":"dc:format","label":"Dc Format","values":["4070322","application/pdf"]},{"key":"dc:title","label":"Title","values":["Dinitrogen complexes of titanium and vanadium stabilized by phosphine ligands"]}]}],"canonical_facts":{"dc:creator":["Chow, Pauline Chang"],"dc:date":["1993"],"dc:description":["The goal of the work presented in this thesis is to investigate the preparation of dinitrogen complexes of titanium and vanadium from phosphine-based starting materials. The reactions of TiCl₄, TiCl₃(THF)₃, or VCl₂(TMEDA)₂ with LiN(SiMe₂CH₂PR₂)₂ (R = isopropyl or methyl) yielded the new phosphine complexes TiCl₃[N(SiMe₂CH₂PPri₂)₂] (1), TiCl₃[N(SiMe₂CH₂PMe₂)₂] (2), {TiCl₂[N(SiMe₂CH₂PPri₂)₂]}x (x = 1 or 2) (3), or [(Pri₂PCH₂SiMe₂)₂N]V(μ-Cl)₂Li(TMEDA) (4), respectively. NMR spectroscopy revealed that complexes 1 and 2 have C₂v symmetry. The titanium(III) species, 3, is likely to be a dimer as indicated by mass spectrometry. The structure of the vanadium mono(amido-diphosphine) complex, 4, is suggested to be a lithium-chloride adduct. The reduction of 1 with magnesium powder under dinitrogen resulted in the synthesis of the binuclear titanium dinitrogen complex, {[(Pri₂PCH₂SiMe₂)₂N]TiCl}₂(μ-η¹:η¹-N₂) (5). The unsuccessful reduction of 3 suggests that it is not an intermediate in the synthesis of 5. The most interesting structural feature of 5 is the end-on bound dinitrogen ligand with an N-N bond distance of 1.275 (7) Å, typical of other binuclear end-on bound dinitrogen complexes. The ¹H and ³¹P{¹H} NMR spectra indicate that this dinitrogen complex is fluxional at room temperature by a process that is proposed to involve dissociation of the phophorus atoms of the tridentate ligand and then rotation about the Ti-N (amide) bond, followed by reassociation. The low temperature ³¹P{¹H} NMR spectrum shows an AB quartet which is consistent with the solid state structure. Upon addition of HCl, 0.75 ± 0.04 equivalents of hydrazine and 0.29 ± 0.05 equivalents of dinitrogen were detected. The reaction between VCl₂(TMEDA)₂ and LiN(SiMe₂CH₂PRi₂)₂ under dinitrogen resulted in the formation of a similar vanadium dinitrogen complex, {[(Pri₂PCH₂SiMe₂)₂N]VCl}₂(μ-η¹:η¹-N₂) (7). An alternate synthetic route involves exposure of [(Pri₂PCH₂SiMe₂)₂N]V(μ-Cl)₂Li(TMEDA), 4, in the solid or solution state to one atmosphere of dinitrogen. Complex 7 was also characterized by X-ray crystallography; the end-on dinitrogen bond length is 1.257 (8) Å. Degradation of 7 with HCl produced 0.29 ± 0.04 equivalents of hydrazine."],"dc:format":["4070322","application/pdf"],"dc:identifier":["http://hdl.handle.net/2429/1315","http://circle.library.ubc.ca/bitstream/2429/1315/3/ubc_1993_spring_chow_pauline_c.pdf"],"dc:language":["eng"],"dc:publisher":["University of British Columbia"],"dc:rights":["For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use."],"dc:title":["Dinitrogen complexes of titanium and vanadium stabilized by phosphine ligands"],"dc:type":["Text"],"thesis:degree_discipline":["Chemistry"],"thesis:degree_level":["master's"],"thesis:degree_name":["Master of Science - MSc"],"thesis:institution_name":["University of British Columbia"]},"updated_at":"2026-07-24T05:07:15Z"}