Design, synthesis and characterization of novel rhenium(V) and technetium(V) complexes as potential radiopharmaceuticals
- Authors: Hlabela, Patrick Simon
- Date: 2001
- Subjects: Radiopharmaceuticals , Rhenium , Technetium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4306 , http://hdl.handle.net/10962/d1004964 , Radiopharmaceuticals , Rhenium , Technetium
- Description: A number of bidentate N, N-diethyl-N' -(R ')benzoylthiourea ligands (where R' = H,CH₃,CI,OCH₃ and N0₂) have been synthesized, as well as the three Re(V) precursor complexes, ReOCl₃(PPh₃)₂,[ReO₂(py)₄]CI and [n-Bu₄N] [ReOCI₄J. The reaction of N,N-diethyl-N'-benzoylthiourea (LH) with these three metal precursor complexes in methanol in the presence of a base gave a novel mixed-ligand complex bis(N,N-diethyl-N'-benzoylthioureato)methoxyoxorhenium(V), [ReO(L)₂(OMe)] (1). In the absence of a base and under an inert atmosphere, the reaction between [n-Bu₄N][ReOCI₄] and LH yielded bis(N,N-diethyl-N'-benzoylthioureato)chlorooxorhenium(V), [ReO(L)₂CI] (lb). The reaction of LH with [ReO₂(py)₄]CI in ethanol and iso-propanol in the presence of sodium acetate gave the novel mixed ligand complexes bis(N,N-diethyl-N'benzoylthioureato) ethoxyoxorhenium(V), [ReO(L)₂(OEt)] (6) and bis(N,N-diethyl-N'benzoylthioureato)(iso-propoxy)oxorhenium(V), [ReO(L)₂(OiPr)] (7), respectively. An oxygen bridged dirhenium complex, [(L)₂0Re-O-ReO(L)₂] (15) was obtained when the reaction was carried out in acetonitrile. A series of mixed ligand Re(V)-oxo complexes using N, N-diethyl-Nʾ-(R' )benzoylthiourea (LR'),N,N-morpholino-N' -(R')benzoylthiourea (morph-LR') and 8-(N-(R')benzoylthiocarbamoyl)-1,4-dioxa-8-azaspiro[4.5]decane ligands (spiro-LR') (where R' = H,CH₃,CI, OCH₃ and N0₂) ((1)(14) have been prepared by the reaction of [ReO₂(py)₄]CI and the ligand in the presence of sodium acetate in methanol. The solution state chemistry of these complexes has shown that complexes(1)-(14) (with the exception of (1b)) undergo dimerization in solution to give complex (15) in the presence of water. Preliminary ¹H NMR kinetics studies of the dimerization of (1), (6) and (7) to (15) have shown that the rate of dimerization decreases in the order (7) > (6) > (1). The rate of dimerization has also been compared for complexes (1), [ReO(morph-L)₂(OMe)] (8) and [ReO(spiro-L)₂(OMe)] (13) and the rate of dimerization was found to be fastest for (13). The crystal structures of (1), [ReO(LN0₂)₂(OMe)] (4), (6) and (15) have been determined. The Re(V)-oxo complexes (1), (4) and (6) have a slightly distorted octahedral geometry with the two acylthiourea ligands binding in a cis arrangement in the equatorial plane of the octahedron. The alkoxy and oxo ligands occupy the axial positions and are situated trans to each other. The crystal and molecular structure of complex (15), consist of two slightly distorted octahedral [ReO(L)₂] moieties bridged by an oxygen atom with a Re-O-Re bond angle of 175.2(2)°. The preliminary studies done in the present study have indicated that the complexation chemistry of technetium(V) with the N,N-diethyl-benzoylthiourea is different to that of rhenium (V). The reaction between [n-BuN₄][TcOCl₄] and N,N-diethyl-N'-benzoylthiourea yielded the square pyramidal cationic complex [TcO(L)₂]Cl. By contrast the octahedral methoxy complex [ReO(L )₂( OMe)] was obtained when the analogous Re(V)-oxo precursor, [n-Bu₄N] [ReOCI₄], was reacted with N,N-diethyl-N'-benzoylthiourea under the same reaction conditions.
- Full Text:
- Date Issued: 2001
- Authors: Hlabela, Patrick Simon
- Date: 2001
- Subjects: Radiopharmaceuticals , Rhenium , Technetium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4306 , http://hdl.handle.net/10962/d1004964 , Radiopharmaceuticals , Rhenium , Technetium
- Description: A number of bidentate N, N-diethyl-N' -(R ')benzoylthiourea ligands (where R' = H,CH₃,CI,OCH₃ and N0₂) have been synthesized, as well as the three Re(V) precursor complexes, ReOCl₃(PPh₃)₂,[ReO₂(py)₄]CI and [n-Bu₄N] [ReOCI₄J. The reaction of N,N-diethyl-N'-benzoylthiourea (LH) with these three metal precursor complexes in methanol in the presence of a base gave a novel mixed-ligand complex bis(N,N-diethyl-N'-benzoylthioureato)methoxyoxorhenium(V), [ReO(L)₂(OMe)] (1). In the absence of a base and under an inert atmosphere, the reaction between [n-Bu₄N][ReOCI₄] and LH yielded bis(N,N-diethyl-N'-benzoylthioureato)chlorooxorhenium(V), [ReO(L)₂CI] (lb). The reaction of LH with [ReO₂(py)₄]CI in ethanol and iso-propanol in the presence of sodium acetate gave the novel mixed ligand complexes bis(N,N-diethyl-N'benzoylthioureato) ethoxyoxorhenium(V), [ReO(L)₂(OEt)] (6) and bis(N,N-diethyl-N'benzoylthioureato)(iso-propoxy)oxorhenium(V), [ReO(L)₂(OiPr)] (7), respectively. An oxygen bridged dirhenium complex, [(L)₂0Re-O-ReO(L)₂] (15) was obtained when the reaction was carried out in acetonitrile. A series of mixed ligand Re(V)-oxo complexes using N, N-diethyl-Nʾ-(R' )benzoylthiourea (LR'),N,N-morpholino-N' -(R')benzoylthiourea (morph-LR') and 8-(N-(R')benzoylthiocarbamoyl)-1,4-dioxa-8-azaspiro[4.5]decane ligands (spiro-LR') (where R' = H,CH₃,CI, OCH₃ and N0₂) ((1)(14) have been prepared by the reaction of [ReO₂(py)₄]CI and the ligand in the presence of sodium acetate in methanol. The solution state chemistry of these complexes has shown that complexes(1)-(14) (with the exception of (1b)) undergo dimerization in solution to give complex (15) in the presence of water. Preliminary ¹H NMR kinetics studies of the dimerization of (1), (6) and (7) to (15) have shown that the rate of dimerization decreases in the order (7) > (6) > (1). The rate of dimerization has also been compared for complexes (1), [ReO(morph-L)₂(OMe)] (8) and [ReO(spiro-L)₂(OMe)] (13) and the rate of dimerization was found to be fastest for (13). The crystal structures of (1), [ReO(LN0₂)₂(OMe)] (4), (6) and (15) have been determined. The Re(V)-oxo complexes (1), (4) and (6) have a slightly distorted octahedral geometry with the two acylthiourea ligands binding in a cis arrangement in the equatorial plane of the octahedron. The alkoxy and oxo ligands occupy the axial positions and are situated trans to each other. The crystal and molecular structure of complex (15), consist of two slightly distorted octahedral [ReO(L)₂] moieties bridged by an oxygen atom with a Re-O-Re bond angle of 175.2(2)°. The preliminary studies done in the present study have indicated that the complexation chemistry of technetium(V) with the N,N-diethyl-benzoylthiourea is different to that of rhenium (V). The reaction between [n-BuN₄][TcOCl₄] and N,N-diethyl-N'-benzoylthiourea yielded the square pyramidal cationic complex [TcO(L)₂]Cl. By contrast the octahedral methoxy complex [ReO(L )₂( OMe)] was obtained when the analogous Re(V)-oxo precursor, [n-Bu₄N] [ReOCI₄], was reacted with N,N-diethyl-N'-benzoylthiourea under the same reaction conditions.
- Full Text:
- Date Issued: 2001
Young women's memories of their experiences in adolescent relationships : a qualitative study
- Authors: Breetzke, Andrea Welsh
- Date: 2001
- Subjects: Teenage girls , Adolescent psychology , Teenagers , Parent and teenager , Teenage parents
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:690 , http://hdl.handle.net/10962/d1006366 , Teenage girls , Adolescent psychology , Teenagers , Parent and teenager , Teenage parents
- Description: Democratic Government in South Africa has brought with it changes in ideology and policy as well as a focus on a new area of concern. It has recognised the importance of young people. In May 1995 the Inter-Ministerial Committee for Youth at Risk (IMC) was established to re-organise the Child and Youth Care system in order increase its effectivity in coping with vulnerable youths. The IMC proposed a new framework for understanding and working with youth based on the principle of the Sioux parenting practices, called the Circle of Courage. Traditionally, helping professionals such as social workers use western theories, such as Erikson's Psychosocial Stage theory, to understand adolescents. Both of these theories and philosophies were not developed in South Africa and there is, therefore, cause for concern as to their relevance to the diverse and unique circumstances of this country. In this qualitative study, five young South African women attending a tertiary institution were asked to tell the stories of their adolescence with specific reference to their boy/girl relationships and factors influencing these relationships. The data was gathered in one or two semi-structured interviews. Data was analysed using Miles and Huberman's (1994) broad model using data reduction (through coding), data display (with the use of two context charts and a thematic conceptual matrix)and verification and conclusion drawing (through finding synergies and contrasts between the data and the two theories). This analysis was conducted with two specific aims. The first aim was to provide a thick description of one of the women's stories to show the complexity and diversity of her experience. Secondly, synergies and contrasts were sought between the women's stories and the two theories: Erikson's stage theory and the Circle of Courage. The analysis showed strong evidence that aspects from both these theories existed in the data and that to some degree both were relevant to the experiences of these five women.
- Full Text:
- Date Issued: 2001
- Authors: Breetzke, Andrea Welsh
- Date: 2001
- Subjects: Teenage girls , Adolescent psychology , Teenagers , Parent and teenager , Teenage parents
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:690 , http://hdl.handle.net/10962/d1006366 , Teenage girls , Adolescent psychology , Teenagers , Parent and teenager , Teenage parents
- Description: Democratic Government in South Africa has brought with it changes in ideology and policy as well as a focus on a new area of concern. It has recognised the importance of young people. In May 1995 the Inter-Ministerial Committee for Youth at Risk (IMC) was established to re-organise the Child and Youth Care system in order increase its effectivity in coping with vulnerable youths. The IMC proposed a new framework for understanding and working with youth based on the principle of the Sioux parenting practices, called the Circle of Courage. Traditionally, helping professionals such as social workers use western theories, such as Erikson's Psychosocial Stage theory, to understand adolescents. Both of these theories and philosophies were not developed in South Africa and there is, therefore, cause for concern as to their relevance to the diverse and unique circumstances of this country. In this qualitative study, five young South African women attending a tertiary institution were asked to tell the stories of their adolescence with specific reference to their boy/girl relationships and factors influencing these relationships. The data was gathered in one or two semi-structured interviews. Data was analysed using Miles and Huberman's (1994) broad model using data reduction (through coding), data display (with the use of two context charts and a thematic conceptual matrix)and verification and conclusion drawing (through finding synergies and contrasts between the data and the two theories). This analysis was conducted with two specific aims. The first aim was to provide a thick description of one of the women's stories to show the complexity and diversity of her experience. Secondly, synergies and contrasts were sought between the women's stories and the two theories: Erikson's stage theory and the Circle of Courage. The analysis showed strong evidence that aspects from both these theories existed in the data and that to some degree both were relevant to the experiences of these five women.
- Full Text:
- Date Issued: 2001
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