Rhenium complexes with multidentate imine-, amine-, thione-, thiol-, hydroxy- and carboxamide chelates
- Authors: Habarurema, Gratien
- Date: 2016
- Subjects: Rhenium Metal complexes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12679 , vital:27106
- Description: This study entails the synthesis, spectroscopic and structural characterization of new rhenium complexes with multidentate imine-, amine-, thione-, thiol-, hydroxy- and carboxamide chelates in various oxidation states. Rhenium(I) and (V) complexes with imidazolidine, pyrimidine and bridging pyridyl derivatives are reported in Chapter 3. The reactions of the potential tridentate N,N,Odonor ligand 2,2'-dipyridylketone (dpk) with trans-[ReOCl3(PPh3)2], (n-Bu4N)[ReOCl4] and trans-[ReOI2(OEt)(PPh3)2] led to the isolation of cis-[ReOCl2(edpm)], cis-[ReOCl2(dpk.OH)] and [ReO3(dpk.OH)] respectively (see Scheme 1). The reaction of (E)-N-((pyridine-2-yl)methylene)benzo[d]thiazol-2-amine (pbt) with trans- [ReOCl3(PPh3)2] produced a mononuclear oxorhenium(V) complex cis- [ReOCl2(epm)(PPh3)]. Both dpk and pbt exhibited a nucleophilic attack by acetonitrile (for Hedpm), water (for dpk) and ethanol (for pbt) leading to chelates that act as uninegative tridentate N,N,O- and bidentate N,O-donor chelates respectively. The reaction of [Re(CO)5Cl] with 2,3-dihydro-2,2-di(pyridin-2-yl)-1H-benzo[d]imidazole (H2dpb), (2,6-diaza-cyclohex-1-enylolonium)2-aza-benzoate (H2den) and 2-(2-(pyridine-2-yl)imidazolidin-2-yl)pyridine (H2pip) (see Scheme 1) gave rise to novel rhenium(I) complexes fac-[Re(CO)3(H2dmb)Cl], fac-[Re(CO)3(Hhdm)] and fac-[Re(CO)3(H2pip)]Cl respectively. The monomeric cationic salt fac-[Re(CO)3(H2salbam)]Br and ligand-bridged dimer fac- (μ-H2salet)[Re(CO)3]2 complexes were formed by the reactions of [Re(CO)5X] (X = Br or Cl) with the potentially heptadentate Schiff base 2,2,2-tris (salicylideneimino)- triethylamine (H3salet; Scheme 2) respectively. The reactions of the potentially hexadentate ligands acting as tridentate monoanionic N,N,O- or N,O,O-donor chelates N1-(3-(2-hydroxy enzylideneamino) propylamino) ethyl)benzylidenepropane-1,3-diamine (H2salpd) and N,N -bis(salicylidene) -3,6-dioxa-1,8-diaminooctane (H2saldane) (Scheme 2) with [Re(CO)5Cl] led to the isolation of the mononuclear and dinuclear complexes fac-[Re(CO)3(Hsaldane)] and fac-(μ-salpd)[Re(CO)3]2 respectively. The reactions of [Re(CO)5Cl] with the tetradentate ligands 2-{[2-hydroxy-3-{[(E)-(2- hydroxyphenyl)-methylidene]amino}propyl)imino]methyl}phenol (H2hmp), 6-((6E)- ((3E)-3-((oxocyclohexa-2,4-dienyl)methyleneamino)-2-hydroxypropylimino)methyl)- cyclohexa-2,4-dienone (H2hcd.H2O) zwitterion and 2-((1E)-1-((E)-3-(2-hydoxyphenylmethylideneamino)propylimino)methyl)phenol (H2hdp) (see Scheme 2) resulted in the formation of the neutral fac-[Re(CO)3(Hamp)], fac-[Re(CO)3(Hhetp)] and fac- [Re(CO)3(Happ)] respectively. The treatment of 2-((3-(2-hydroxybenzylamino)-propylamino)methyl)phenol (H2hbp) with [Re(CO)3Cl] and trans-[ReOCl3(PPh3)2] gave the fac-[Re(CO)3(Hhbp)] and (μ-O)[ReO(hbp)]2 complexes. The reactions of the ligands H2hmp, H2hdp and H2hap (see Scheme 2) with trans-[ReOBr3(PPh3)2] and trans-[ReOI2(OEt)(PPh3)2] produced dinuclear oxo-bridged rhenium(V) complexes (μ-O)[ReO(hmp)]2, [(μ-O)[ReO(hdp)]2 and (μ-O)[ReO(hap)]2 respectively. The neutral and anionic binding modes of thiosemicarbazones to the fac-[Re(CO)3]+, cis- [ReO2]+ and trans-[ReO2]+ cores have been investigated in Chapter 6. The reactions of the potentially tridentate ligand 1-{1-(2- hydroxyphenyl)ethylidene}-4- phenylthiosemicarbazide (H2hpt) (see Scheme 3) with [Re(CO)5Cl], cis-[ReO2I(PPh3)2]cand trans-[ReO2(py)4]Cl led to the isolation of the complexes fac-[Re(CO)3(H2hpt)2]Cl, [Re(hipt)(Hipht)(PPh3)] and trans-[ReO(hpt)(Hhpt)] respectively. The X-ray crystal analysis of the complexes show that the ligand H2hpt exhibits decomposition, thiol-enol tautomerism and a thiolate-iminium zwitterionic process, and coordinates in the neutral form via its thione sulfur and nitrogen and anionic through the azo nitrogen, thiolate sulfur and acetophenolic oxygen. A series of nitrogen-heterocyclic amide-, acid-, thiol- and diol-based ligands as well as their related monomeric rhenium(III) and (V) complexes have also been studied (see Chapter 7). The reaction of N-(2-(pyrazine-2-carboxamido)phenyl)pyrazine-2- carboxamide (H2ppc) (Scheme 3) with trans-[ReOBr3(PPh3)2] yielded the complex trans- [ReBr2(Hppca)(PPh3)2]. The reactions of trans-[ReOX3(PPh3)2] (X = Cl, Br) with pyridine-2,6-dicarboxylic acid (H2pda) produced the neutral oxorhenium(V) complexes [ReOX2(epca)(PPh3)]. The treatment of trans-[ReOBr3(PPh3)2] with 2-mercaptopyridine- 3-carboxylic acid (H2mpc) gave rise to the rhenium(III) complex [Re(empc)3(PPh3)]. The reaction of 2,6-bis(hydroxymethyl)pyridine (H2bhp) with trans-[ReOI2(EOt)(PPh3)2], trans-[ReOBr3(PPh3)2] and [Re(CO)5Cl] gave the complexes [ReO(Hbhp)2(PPh3)]I.PPh3, cis-[ReOBr2(Hbhp)(PPh3)] and fac-(μ- O)2[Re(CO)3(Hbhp)]2 respectively. Their X-ray crystal structures indicate that the ligand acts as a bidentate monoanionic N,O-donor chelate leaving a free aliphatic hydroxyl group.
- Full Text:
- Date Issued: 2016
- Authors: Habarurema, Gratien
- Date: 2016
- Subjects: Rhenium Metal complexes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/12679 , vital:27106
- Description: This study entails the synthesis, spectroscopic and structural characterization of new rhenium complexes with multidentate imine-, amine-, thione-, thiol-, hydroxy- and carboxamide chelates in various oxidation states. Rhenium(I) and (V) complexes with imidazolidine, pyrimidine and bridging pyridyl derivatives are reported in Chapter 3. The reactions of the potential tridentate N,N,Odonor ligand 2,2'-dipyridylketone (dpk) with trans-[ReOCl3(PPh3)2], (n-Bu4N)[ReOCl4] and trans-[ReOI2(OEt)(PPh3)2] led to the isolation of cis-[ReOCl2(edpm)], cis-[ReOCl2(dpk.OH)] and [ReO3(dpk.OH)] respectively (see Scheme 1). The reaction of (E)-N-((pyridine-2-yl)methylene)benzo[d]thiazol-2-amine (pbt) with trans- [ReOCl3(PPh3)2] produced a mononuclear oxorhenium(V) complex cis- [ReOCl2(epm)(PPh3)]. Both dpk and pbt exhibited a nucleophilic attack by acetonitrile (for Hedpm), water (for dpk) and ethanol (for pbt) leading to chelates that act as uninegative tridentate N,N,O- and bidentate N,O-donor chelates respectively. The reaction of [Re(CO)5Cl] with 2,3-dihydro-2,2-di(pyridin-2-yl)-1H-benzo[d]imidazole (H2dpb), (2,6-diaza-cyclohex-1-enylolonium)2-aza-benzoate (H2den) and 2-(2-(pyridine-2-yl)imidazolidin-2-yl)pyridine (H2pip) (see Scheme 1) gave rise to novel rhenium(I) complexes fac-[Re(CO)3(H2dmb)Cl], fac-[Re(CO)3(Hhdm)] and fac-[Re(CO)3(H2pip)]Cl respectively. The monomeric cationic salt fac-[Re(CO)3(H2salbam)]Br and ligand-bridged dimer fac- (μ-H2salet)[Re(CO)3]2 complexes were formed by the reactions of [Re(CO)5X] (X = Br or Cl) with the potentially heptadentate Schiff base 2,2,2-tris (salicylideneimino)- triethylamine (H3salet; Scheme 2) respectively. The reactions of the potentially hexadentate ligands acting as tridentate monoanionic N,N,O- or N,O,O-donor chelates N1-(3-(2-hydroxy enzylideneamino) propylamino) ethyl)benzylidenepropane-1,3-diamine (H2salpd) and N,N -bis(salicylidene) -3,6-dioxa-1,8-diaminooctane (H2saldane) (Scheme 2) with [Re(CO)5Cl] led to the isolation of the mononuclear and dinuclear complexes fac-[Re(CO)3(Hsaldane)] and fac-(μ-salpd)[Re(CO)3]2 respectively. The reactions of [Re(CO)5Cl] with the tetradentate ligands 2-{[2-hydroxy-3-{[(E)-(2- hydroxyphenyl)-methylidene]amino}propyl)imino]methyl}phenol (H2hmp), 6-((6E)- ((3E)-3-((oxocyclohexa-2,4-dienyl)methyleneamino)-2-hydroxypropylimino)methyl)- cyclohexa-2,4-dienone (H2hcd.H2O) zwitterion and 2-((1E)-1-((E)-3-(2-hydoxyphenylmethylideneamino)propylimino)methyl)phenol (H2hdp) (see Scheme 2) resulted in the formation of the neutral fac-[Re(CO)3(Hamp)], fac-[Re(CO)3(Hhetp)] and fac- [Re(CO)3(Happ)] respectively. The treatment of 2-((3-(2-hydroxybenzylamino)-propylamino)methyl)phenol (H2hbp) with [Re(CO)3Cl] and trans-[ReOCl3(PPh3)2] gave the fac-[Re(CO)3(Hhbp)] and (μ-O)[ReO(hbp)]2 complexes. The reactions of the ligands H2hmp, H2hdp and H2hap (see Scheme 2) with trans-[ReOBr3(PPh3)2] and trans-[ReOI2(OEt)(PPh3)2] produced dinuclear oxo-bridged rhenium(V) complexes (μ-O)[ReO(hmp)]2, [(μ-O)[ReO(hdp)]2 and (μ-O)[ReO(hap)]2 respectively. The neutral and anionic binding modes of thiosemicarbazones to the fac-[Re(CO)3]+, cis- [ReO2]+ and trans-[ReO2]+ cores have been investigated in Chapter 6. The reactions of the potentially tridentate ligand 1-{1-(2- hydroxyphenyl)ethylidene}-4- phenylthiosemicarbazide (H2hpt) (see Scheme 3) with [Re(CO)5Cl], cis-[ReO2I(PPh3)2]cand trans-[ReO2(py)4]Cl led to the isolation of the complexes fac-[Re(CO)3(H2hpt)2]Cl, [Re(hipt)(Hipht)(PPh3)] and trans-[ReO(hpt)(Hhpt)] respectively. The X-ray crystal analysis of the complexes show that the ligand H2hpt exhibits decomposition, thiol-enol tautomerism and a thiolate-iminium zwitterionic process, and coordinates in the neutral form via its thione sulfur and nitrogen and anionic through the azo nitrogen, thiolate sulfur and acetophenolic oxygen. A series of nitrogen-heterocyclic amide-, acid-, thiol- and diol-based ligands as well as their related monomeric rhenium(III) and (V) complexes have also been studied (see Chapter 7). The reaction of N-(2-(pyrazine-2-carboxamido)phenyl)pyrazine-2- carboxamide (H2ppc) (Scheme 3) with trans-[ReOBr3(PPh3)2] yielded the complex trans- [ReBr2(Hppca)(PPh3)2]. The reactions of trans-[ReOX3(PPh3)2] (X = Cl, Br) with pyridine-2,6-dicarboxylic acid (H2pda) produced the neutral oxorhenium(V) complexes [ReOX2(epca)(PPh3)]. The treatment of trans-[ReOBr3(PPh3)2] with 2-mercaptopyridine- 3-carboxylic acid (H2mpc) gave rise to the rhenium(III) complex [Re(empc)3(PPh3)]. The reaction of 2,6-bis(hydroxymethyl)pyridine (H2bhp) with trans-[ReOI2(EOt)(PPh3)2], trans-[ReOBr3(PPh3)2] and [Re(CO)5Cl] gave the complexes [ReO(Hbhp)2(PPh3)]I.PPh3, cis-[ReOBr2(Hbhp)(PPh3)] and fac-(μ- O)2[Re(CO)3(Hbhp)]2 respectively. Their X-ray crystal structures indicate that the ligand acts as a bidentate monoanionic N,O-donor chelate leaving a free aliphatic hydroxyl group.
- Full Text:
- Date Issued: 2016
A critical study of voice teaching method, with specific reference to solo singing, choral singing and vocal health for the teenage singer
- Authors: Olivier, Madelie Charlotte
- Date: 2012
- Subjects: Singing -- Instruction and study , Voice culture -- Exercises , Singing -- Methods
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:8523 , http://hdl.handle.net/10948/d1019926
- Description: This dissertation presents a critical study of voice teaching method as this pertains to the high school learner studying voice within the South African educational environment, with learning outcomes determined for subject music within the GET (General Education and Training) and FET (Further Education and Training) bands of the Department of Basic Education at each school grade level, as well as by external examining bodies such as Unisa (University of South Africa), Trinity Guildhall and ABRSM (Amalgamated Board of the Royal Schools of Music). Emphasis is placed on the methodological principles applicable in the case of the Western classical music solo vocal repertoire, but reference is also made to the applicability of this method in other vocal genres and, in particular, in the case of choral music participation. Special attention is given to the subject of the vocal health of the developing teenage voice, which includes an overview of vocal disorders and suggestions for rehabilitation and remedial programmes where necessary. Triangulation of research results is achieved in this study through inclusion of: - A thorough survey of selected pertinent bibliographic sources - Description of and engagement with the researcher’s own numerous phenomenological encounters in this field - Interviews conducted in Port Elizabeth with Jill Nock, voice teacher, on the subject of voice teaching method, and with John Black, Ear, Nose and Throat Specialist, on the subject of vocal health. The researcher concludes that there is a need for continued education and training of music educators in the South African high school environment, many of whom are not trained voice specialists, in order to cater for the growing number of high school music learners who choose to specialise in voice. Although educator networking can go a long way towards creating an informal support system to address this need, it is ultimately the responsibility of the Department of Basic Education to address this in a formal and all-encompassing fashion.
- Full Text:
- Date Issued: 2012
- Authors: Olivier, Madelie Charlotte
- Date: 2012
- Subjects: Singing -- Instruction and study , Voice culture -- Exercises , Singing -- Methods
- Language: English
- Type: Thesis , Masters , MMus
- Identifier: vital:8523 , http://hdl.handle.net/10948/d1019926
- Description: This dissertation presents a critical study of voice teaching method as this pertains to the high school learner studying voice within the South African educational environment, with learning outcomes determined for subject music within the GET (General Education and Training) and FET (Further Education and Training) bands of the Department of Basic Education at each school grade level, as well as by external examining bodies such as Unisa (University of South Africa), Trinity Guildhall and ABRSM (Amalgamated Board of the Royal Schools of Music). Emphasis is placed on the methodological principles applicable in the case of the Western classical music solo vocal repertoire, but reference is also made to the applicability of this method in other vocal genres and, in particular, in the case of choral music participation. Special attention is given to the subject of the vocal health of the developing teenage voice, which includes an overview of vocal disorders and suggestions for rehabilitation and remedial programmes where necessary. Triangulation of research results is achieved in this study through inclusion of: - A thorough survey of selected pertinent bibliographic sources - Description of and engagement with the researcher’s own numerous phenomenological encounters in this field - Interviews conducted in Port Elizabeth with Jill Nock, voice teacher, on the subject of voice teaching method, and with John Black, Ear, Nose and Throat Specialist, on the subject of vocal health. The researcher concludes that there is a need for continued education and training of music educators in the South African high school environment, many of whom are not trained voice specialists, in order to cater for the growing number of high school music learners who choose to specialise in voice. Although educator networking can go a long way towards creating an informal support system to address this need, it is ultimately the responsibility of the Department of Basic Education to address this in a formal and all-encompassing fashion.
- Full Text:
- Date Issued: 2012
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