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dc.contributor.authorKandel, Ramjeeen
dc.date.accessioned2018-09-29T21:09:13Z
dc.date.available2018-09-29T21:09:13Z
dc.identifier.urihttp://hdl.handle.net/1974/24918
dc.description.abstractHemilabile ligands are useful because the activity at the metal centre can be manipulated and controlled by the labile groups. P,N donors are widely used hemilabile ligands in coordination and organometallic chemistry. Phosphorus is generally considered a soft donor and inert. Alternatively, nitrogen is considered a moderately hard donor and is labile. Late transition metals can complex with either the P or the N as a monodentate ligand or through both the P and the N as a bidentate ligand depending on the hardness of the metal centre and the ligand sterics. Phosphaamidines [RC(PR2)=NR] and phosphaguanidines [R2NC(PR2)=NR] are small bite angle bidentate ligands and promising hemilabile ligands. Having strongly basic sites near the metal centre should promote heterolytic cleavage of H2 or proton transfer that can assist in homogenous catalytic reactions like CO2 hydrogenation. A facile route is developed to prepare acyclic and aprotic phosphaamidine [PhC(PR2)=NR, R=Ph, iPr] and phosphaguanidine [Me2NC(PPh2)=NiPr] ligands that coordinate to Cu(I), Rh(I) and Ru(II) metal centres. Crystal structures are reported for all complexes. Coordination to Cu(I) occurs either through P in η1 mode or by both P or Nimine in a η2 mode. Coordination to Rh(I) occurs through η1or η2 modes while to Ru(II) occurs only through η2 mode. Tests of CO2 hydrogenation using phosphaamidine complexes showed that Ru(II) phosphaamidines are active precatalysts than Rh(I) phosphaamidines. Substitution of phenyl with isopropyl doesn’t have significant impact on the TON or the yield of formic acid in the presence of DBU. However, using Ru(II) phosphaguanidine instead of Ru(II) phosphaamidine increases the yield. A Ru(II) phosphaguanidine complex is also a potential precatalyst for the hydration of benzonitrile. It is also shown that a guanidine [Me2NC(NPh2)=NiPr] and a structurally analogous phosphaguanidine [Me2NC(PPh2)=NiPr] both act as Brønsted bases and have almost same basicity in acetonitrile solution. The proton coordinated to [Me2NC(PPh2)=NHiPr]Cl and therefore the basicity of the neutral form are both retained once the P is coordinated to Cu(I). The retention of basicity upon coordination of this salt to a metal centre is also supported by the observation of π electron delocalization within the amidine unit by X-ray crystallography.en
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsQueen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canadaen
dc.rightsProQuest PhD and Master's Theses International Dissemination Agreementen
dc.rightsIntellectual Property Guidelines at Queen's Universityen
dc.rightsCopying and Preserving Your Thesisen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectHemilabileen
dc.subjectSuperbaseen
dc.subjectCatalysisen
dc.subjectPhosphaamidineen
dc.subjectPhosphaguanidineen
dc.subjectCoordinationen
dc.titlePhosphaamidines and Phosphaguanidines as Ligands: Coordination Chemistry and Catalysisen
dc.typethesisen
dc.description.degreePhDen
dc.contributor.supervisorJessop, Philipen
dc.contributor.departmentChemistryen
dc.degree.grantorQueen's University at Kingstonen


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