title: Asymmetric Ligands Derived from Carbohydrates

authors: Jarman, Bevan Peter

subjects: Carbohydrates

abstract: This thesis describes the incorporation of carbohydrate groups in thiourea, 1, or iminophosphorane, 2, ligands. Several carbohydrate acyl thioureas, 3, were synthesised from the reaction of protected and unprotected D‐glucosamine with acyl isothiocyanates, RCONCS. Internal hydrogen‐bonding forms a planar six‐membered ring, which locks the thiourea into an Z,E,Z‐anti conformation as shown by 1H NMR spectroscopy and confirmed by X‐ray structure determination of two examples. As neutral ligands to Rh(III), Rh(I), Ru(II), Pd(II), Pt(II) and Au(I) they bond through the sulfur atom with retention of the six‐membered ring and the Z,E,Z‐anti conformation. This was confirmed by two X‐ray structure determinations on Rh(III) and Pd(II) examples which also showed the new hydrogen‐bond formed by HN2 to a halide on the metal. 
Deprotonation of the ligands 3 with NaOAc gave anionic species which formed bidentate chelating complexes with metals. When attached to Rh(III), Ru(II) or with two thiourea bonding to Pd(II) it forms a four‐membered ring through the S and N2 atoms which retains the hydrogen‐bond. If Rh(I) or (C,Ndimethylbenzylamine‐ Pd) is used a six‐membered ring is formed through the S and O atoms which disrupts the hydrogen‐bond. This disruption of the hydrogenbond is apparent from the chemical shift of HN1. For examples where coordination led to a chiral metal complex (e.g. for Cp*RhCl(N,S‐thiourea)) NMR measurements showed that the natural chirality of the ligand did not provide any selectivity with equal proportions of the two diastereoisomers formed.
Iminophosphoranes were produced by the reaction of protected sugar azides with phosphines via the Staudinger reaction. Cyclometalated complexes, 4, could not be formed directly which an X‐ray structure determination suggested was because of steric crowding of the nitrogen. An indirect transmetalation route was developed where the sugar azides were reacted with the mercurated diphosphine, Hg(2‐C₆H₄PPh₂)₂, and the resulting iminophosphoranes transmetalated with [NMe₄][AuCl₄] to produce cyclometalated Au(III) dichloride complexes. Two X‐ray structure determinations showed that the five‐membered metalocyclic ring was in an envelope conformation. The chlorides were labile and able to be displaced by PPh3 and thiosalicylic acid.
A series of N‐sugar and N‐phenyl iminophosphorane Au(III) complexes were shown to catalyse the addition of 2‐methyl furan to methyl vinyl ketone.

text: Asymmetric Ligands Derived from Carbohydrates This thesis describes the incorporation of carbohydrate groups in thiourea, 1, or iminophosphorane, 2, ligands. Several carbohydrate acyl thioureas, 3, were synthesised from the reaction of protected and unprotected D‐glucosamine with acyl isothiocyanates, RCONCS. Internal hydrogen‐bonding forms a planar six‐membered ring, which locks the thiourea into an Z,E,Z‐anti conformation as shown by 1H NMR spectroscopy and confirmed by X‐ray structure determination of two examples. As neutral ligands to Rh(III), Rh(I), Ru(II), Pd(II), Pt(II) and Au(I) they bond through the sulfur atom with retention of the six‐membered ring and the Z,E,Z‐anti conformation. This was confirmed by two X‐ray structure determinations on Rh(III) and Pd(II) examples which also showed the new hydrogen‐bond formed by HN2 to a halide on the metal. 
Deprotonation of the ligands 3 with NaOAc gave anionic species which formed bidentate chelating complexes with metals. When attached to Rh(III), Ru(II) or with two thiourea bonding to Pd(II) it forms a four‐membered ring through the S and N2 atoms which retains the hydrogen‐bond. If Rh(I) or (C,Ndimethylbenzylamine‐ Pd) is used a six‐membered ring is formed through the S and O atoms which disrupts the hydrogen‐bond. This disruption of the hydrogenbond is apparent from the chemical shift of HN1. For examples where coordination led to a chiral metal complex (e.g. for Cp*RhCl(N,S‐thiourea)) NMR measurements showed that the natural chirality of the ligand did not provide any selectivity with equal proportions of the two diastereoisomers formed.
Iminophosphoranes were produced by the reaction of protected sugar azides with phosphines via the Staudinger reaction. Cyclometalated complexes, 4, could not be formed directly which an X‐ray structure determination suggested was because of steric crowding of the nitrogen. An indirect transmetalation route was developed where the sugar azides were reacted with the mercurated diphosphine, Hg(2‐C₆H₄PPh₂)₂, and the resulting iminophosphoranes transmetalated with [NMe₄][AuCl₄] to produce cyclometalated Au(III) dichloride complexes. Two X‐ray structure determinations showed that the five‐membered metalocyclic ring was in an envelope conformation. The chlorides were labile and able to be displaced by PPh3 and thiosalicylic acid.
A series of N‐sugar and N‐phenyl iminophosphorane Au(III) complexes were shown to catalyse the addition of 2‐methyl furan to methyl vinyl ketone.

year: 2011

title: Is engineering for me? Do girls have enough information to decide?

authors: Swan, Janis E.

subjects: Engineering

abstract: Increasing the diversity in engineering starts with increasing the proportion of the specific cohort choosing to study engineering. The proportion of women doing engineering is low. Common barriers to increasing the proportion of woman in engineering include not studying the appropriate subjects to meet entry requirements, misconceptions about engineers, and lack of information on possible careers after graduation. Various strategies have been developed to overcome barriers but the proportion of woman studying engineering has not increased significantly over the past fifty years.

text: Is engineering for me? Do girls have enough information to decide? Increasing the diversity in engineering starts with increasing the proportion of the specific cohort choosing to study engineering. The proportion of women doing engineering is low. Common barriers to increasing the proportion of woman in engineering include not studying the appropriate subjects to meet entry requirements, misconceptions about engineers, and lack of information on possible careers after graduation. Various strategies have been developed to overcome barriers but the proportion of woman studying engineering has not increased significantly over the past fifty years.

year: 2018

title: Listening to the voices of Year 13 Māori students: A case study in a New Zealand secondary school

authors: Kay, Joan-Marie

subjects: Maori Achievement

abstract: This research focuses on listening to the voices of Year 13 academically successful Māori students in a large, urban, mainstream, co-educational, decile 4, New Zealand secondary school. Traditionally, researchers have tended to emphasise the poor academic performance of Māori students in New Zealand. In contrast, this qualitative case study, however, seeks to understand what influences and motivates the academically successful Year 13 Māori students who have gained the National Certificate of Educational Achievement (NCEA) Level 2 and who returned to school to study for NCEA Level 3.

Semi structured interviews as conversations with all thirteen Māori students who had achieved NCEA Level 2 formed the basis of this research. Five of their parents, seven of their teachers and the principal were also interviewed.

The findings show that these students all stress the importance of their family, in particular, one family member or significant adult in their lives who valued education and supported the student, influencing and encouraging their motivation and self-efficacy. Building positive relationships with their teachers was the next strongest influence on their academic success followed closely by the positive influence of their friends. Self-motivation was mainly extrinsic. The students perceived that the principal had little effect on their individual achievement.

The teachers also acknowledge the importance of building positive relationships with their students and acknowledge the benefits of the reflective practice provided by the Te Kotahitanga project in highlighting this factor.

The findings suggest the excellent initiatives currently taking place in the school need to be continued or strengthened and that further interventions which target particular Māori students, rather than are global across the school, should be introduced.

text: Listening to the voices of Year 13 Māori students: A case study in a New Zealand secondary school This research focuses on listening to the voices of Year 13 academically successful Māori students in a large, urban, mainstream, co-educational, decile 4, New Zealand secondary school. Traditionally, researchers have tended to emphasise the poor academic performance of Māori students in New Zealand. In contrast, this qualitative case study, however, seeks to understand what influences and motivates the academically successful Year 13 Māori students who have gained the National Certificate of Educational Achievement (NCEA) Level 2 and who returned to school to study for NCEA Level 3.

Semi structured interviews as conversations with all thirteen Māori students who had achieved NCEA Level 2 formed the basis of this research. Five of their parents, seven of their teachers and the principal were also interviewed.

The findings show that these students all stress the importance of their family, in particular, one family member or significant adult in their lives who valued education and supported the student, influencing and encouraging their motivation and self-efficacy. Building positive relationships with their teachers was the next strongest influence on their academic success followed closely by the positive influence of their friends. Self-motivation was mainly extrinsic. The students perceived that the principal had little effect on their individual achievement.

The teachers also acknowledge the importance of building positive relationships with their students and acknowledge the benefits of the reflective practice provided by the Te Kotahitanga project in highlighting this factor.

The findings suggest the excellent initiatives currently taking place in the school need to be continued or strengthened and that further interventions which target particular Māori students, rather than are global across the school, should be introduced.

year: 2008