Synthesis, crystal structures and molecular modelling of rare earth complexes with bis(2-pyridylmethyl)amine: aim topological analysis and ligand conformation search
- Authors: Matthews, Cameron
- Date: 2017
- Subjects: Rare earths , Ligands , Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/8230 , vital:26229
- Description: Eight rare earth complexes with bis(2-pyridylmethyl)amine (DPA) were synthesised and recrystallised, under air-sensitive or low moisture conditions. The crystal structures were successfully determined, via SC-XRD, and the asymmetric units of five complexes (1, 3, 5, 6 and 7) were submitted for DFT molecular modelling calculations, which involved geometry optimisation and frequency calculations. The neutral complexes obtained were bis(bis(2-pyridylmethyl)amine)-trichloro-lanthanum(III) [LaCl3(DPA)2] (1), bis(bis(2-pyridylmethyl)amine)-trichloro-cerium(III)) [CeCl3(DPA)2] (2), bis(μ2-chloro)-diaqua-tetrachloro-bis(bis(2-pyridylmethyl)amine)-di-praseodymium(III) [PrCl2(μ-Cl)(DPA)(OH2)]2 (3) and bis(μ2-methoxo)-bis(bis(2-pyridylmethyl)amine)- tetrachloro-di-dysprosium(III) [DyCl2(μ-OCH3)(DPA)]2 (4). The cationic complexes obtained in this study were dichloro-bis(bis(2-pyridylmethyl)amine)- neodymium(III) chloride methanol solvate [NdCl2(DPA)2]Cl·CH3OH (5), dichloro-bis(bis(2- pyridylmethyl)amine)-dysprosium(III) chloride methanol solvate [DyCl2(DPA)2]Cl·CH3OH (6), dichloro-bis(bis(2-pyridylmethyl)amine)-yttrium(III) chloride methanol solvate [YCl2(DPA)2]Cl·CH3OH (7) and dichloro-bis(bis(2-pyridylmethyl)amine)-lutetium(III) chloride methanol solvate [LuCl2(DPA)2]Cl·CH3OH (8). The ‘Quantum theory of atoms in molecules’ approach was used to investigate the electron density topology, primarily in order to investigate the hydrogen and coordination bonds for three of the eight complexes. Two of the neutral complexes contain the ‘early’ rare earth elements lanthanum and praseodymium and one cationic complex contains the ‘late’ lanthanide element dysprosium. Noncovalent interaction analysis was also performed on the aforementioned complexes in order to gain a deeper understanding of the intra-molecular stereo-electronic interactions. Spin density analysis was used to investigate the distribution of unpaired electron density at and around the metal centres of the aforementioned paramagnetic Pr- and Dy-complexes. A ligand conformation search for DPA was undertaken and 32 low energy conformers were identified and their relative energies were determined using two DFT functionals, namely M06 and M06-2X.
- Full Text:
- Date Issued: 2017
- Authors: Matthews, Cameron
- Date: 2017
- Subjects: Rare earths , Ligands , Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/8230 , vital:26229
- Description: Eight rare earth complexes with bis(2-pyridylmethyl)amine (DPA) were synthesised and recrystallised, under air-sensitive or low moisture conditions. The crystal structures were successfully determined, via SC-XRD, and the asymmetric units of five complexes (1, 3, 5, 6 and 7) were submitted for DFT molecular modelling calculations, which involved geometry optimisation and frequency calculations. The neutral complexes obtained were bis(bis(2-pyridylmethyl)amine)-trichloro-lanthanum(III) [LaCl3(DPA)2] (1), bis(bis(2-pyridylmethyl)amine)-trichloro-cerium(III)) [CeCl3(DPA)2] (2), bis(μ2-chloro)-diaqua-tetrachloro-bis(bis(2-pyridylmethyl)amine)-di-praseodymium(III) [PrCl2(μ-Cl)(DPA)(OH2)]2 (3) and bis(μ2-methoxo)-bis(bis(2-pyridylmethyl)amine)- tetrachloro-di-dysprosium(III) [DyCl2(μ-OCH3)(DPA)]2 (4). The cationic complexes obtained in this study were dichloro-bis(bis(2-pyridylmethyl)amine)- neodymium(III) chloride methanol solvate [NdCl2(DPA)2]Cl·CH3OH (5), dichloro-bis(bis(2- pyridylmethyl)amine)-dysprosium(III) chloride methanol solvate [DyCl2(DPA)2]Cl·CH3OH (6), dichloro-bis(bis(2-pyridylmethyl)amine)-yttrium(III) chloride methanol solvate [YCl2(DPA)2]Cl·CH3OH (7) and dichloro-bis(bis(2-pyridylmethyl)amine)-lutetium(III) chloride methanol solvate [LuCl2(DPA)2]Cl·CH3OH (8). The ‘Quantum theory of atoms in molecules’ approach was used to investigate the electron density topology, primarily in order to investigate the hydrogen and coordination bonds for three of the eight complexes. Two of the neutral complexes contain the ‘early’ rare earth elements lanthanum and praseodymium and one cationic complex contains the ‘late’ lanthanide element dysprosium. Noncovalent interaction analysis was also performed on the aforementioned complexes in order to gain a deeper understanding of the intra-molecular stereo-electronic interactions. Spin density analysis was used to investigate the distribution of unpaired electron density at and around the metal centres of the aforementioned paramagnetic Pr- and Dy-complexes. A ligand conformation search for DPA was undertaken and 32 low energy conformers were identified and their relative energies were determined using two DFT functionals, namely M06 and M06-2X.
- Full Text:
- Date Issued: 2017
Studies towards the synthesis of novel tridentate ligands for use in ruthenium metathesis catalysts
- Authors: Millward, Tanya
- Date: 2009
- Subjects: Ligands , Catalysis , Metathesis (Chemistry) , Ruthenium , Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4360 , http://hdl.handle.net/10962/d1005025 , Ligands , Catalysis , Metathesis (Chemistry) , Ruthenium , Complex compounds
- Description: This work has focussed on the preparation of a variety of tridentate ligands, designed to form ruthenium complexes as potential metathesis catalysts. Various approaches to the tridentate, malonate-tethered imidazolidine system have been investigated, and a promising route to accessing ligands of this type is discussed. A tridentate malonate-tethered pyridine ligand has been successfully prepared and its dithallium salt has been accessed by hydrolysis with thallium carbonate; approaches to a longer-chain analogue have also been investigated. A thallium pyridine-2,6- dicarboxylate ligand has been has been successfully prepared, as have a range of pyridine diamine ligands, with various alkyl and aromatic substituents on the amine donor atoms. Preliminary investigations into the potential of these compounds as ligands for alkylidene ruthenium complexes are reported using molecular modelling techniques. The geometries and steric energies of the ligands and their corresponding complexes have been analysed, and results obtained from two different software packages are compared. Finally, some preliminary complexation studies have been undertaken.
- Full Text:
- Date Issued: 2009
- Authors: Millward, Tanya
- Date: 2009
- Subjects: Ligands , Catalysis , Metathesis (Chemistry) , Ruthenium , Complex compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4360 , http://hdl.handle.net/10962/d1005025 , Ligands , Catalysis , Metathesis (Chemistry) , Ruthenium , Complex compounds
- Description: This work has focussed on the preparation of a variety of tridentate ligands, designed to form ruthenium complexes as potential metathesis catalysts. Various approaches to the tridentate, malonate-tethered imidazolidine system have been investigated, and a promising route to accessing ligands of this type is discussed. A tridentate malonate-tethered pyridine ligand has been successfully prepared and its dithallium salt has been accessed by hydrolysis with thallium carbonate; approaches to a longer-chain analogue have also been investigated. A thallium pyridine-2,6- dicarboxylate ligand has been has been successfully prepared, as have a range of pyridine diamine ligands, with various alkyl and aromatic substituents on the amine donor atoms. Preliminary investigations into the potential of these compounds as ligands for alkylidene ruthenium complexes are reported using molecular modelling techniques. The geometries and steric energies of the ligands and their corresponding complexes have been analysed, and results obtained from two different software packages are compared. Finally, some preliminary complexation studies have been undertaken.
- Full Text:
- Date Issued: 2009
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