title: Synthesis and Characterisation of Cycloaurated Gold(III) Complexes with Bidentate (O,O), (N,S) and (S,S) Chelating Ligands

authors: Smith, Tiffany Sharee

subjects: Cycloaurated Gold(III) Complexes

abstract: The reaction of C,N-coordinated gold(III) dihalides; BpAuCl₂ (Bp = 2 benzylpyridyl), AnpAuCl₂ (Anp = 2 anilinopyridyl) and TypAuCl₂ (Typ = 2 tolylpyridyl) with catecholate ligands in hot methanol and trimethylamine produced metallacycles with structural isomers of the general formula (C,N)Au{O,O}. Similarly, BpAuCl₂ and AnpAuCl₂ were reacted with thiourea ligands to form complexes giving high yield and good purity with the general formula (C,N)Au{PhNCSNR₂}+, by means of the addition of BPh₄- for precipitation. X-ray crystal structures of the compounds [AnpAu{PhNCSNMe₂}]BPh₄ and [AnpAu{PhNCSNCy₂}]BPh₄ confirmed the coordination of the thiourea to the gold centre through the N and S atoms. In both cases the geometry around the gold atom is square-planar with complex [AnpAu{PhNCSNCy₂}]BPh₄ showing a slightly more puckered conformation than [AnpAu{PhNCSNMe₂}]BPh₄ due to the sterically bulky cyclohexyl groups attached. Some thiourea derivatives were tested against P388 murine leukaemia cells with complex [AnpAu{PhNCSNHPh}]BPh₄ showing promising anti-tumour activity.

When thiourea ligands were replaced by dithiophosphinate and dithiophosphate ligands the reaction proceeded at room temperature without the need for the presence of a base. Relatively low yields of impure metallacycles with the general formula (C,N)Au{S₂PR₂}+ were obtained on the addition of BPh₄- or BF₄-. Attempts to improve purity by varying batches of starting materials, anion and solvents used were unsuccessful. X-ray crystal data from a single crystal of [(C,N)Au{S₂PPh₂}]BPh₄ shows the reduction of gold(III) to gold(I) forming a known polymeric gold(I) dithiophosphinate complex. In order to extend this study the synthesis of complexes with the general formula R₂PS₂AuCl₂ was attempted, but no new compounds were characterised.

Where possible, all new compounds reported in this thesis were characterised by ES-MS, IR, NMR, melting point and micro-elemental analysis.

text: Synthesis and Characterisation of Cycloaurated Gold(III) Complexes with Bidentate (O,O), (N,S) and (S,S) Chelating Ligands The reaction of C,N-coordinated gold(III) dihalides; BpAuCl₂ (Bp = 2 benzylpyridyl), AnpAuCl₂ (Anp = 2 anilinopyridyl) and TypAuCl₂ (Typ = 2 tolylpyridyl) with catecholate ligands in hot methanol and trimethylamine produced metallacycles with structural isomers of the general formula (C,N)Au{O,O}. Similarly, BpAuCl₂ and AnpAuCl₂ were reacted with thiourea ligands to form complexes giving high yield and good purity with the general formula (C,N)Au{PhNCSNR₂}+, by means of the addition of BPh₄- for precipitation. X-ray crystal structures of the compounds [AnpAu{PhNCSNMe₂}]BPh₄ and [AnpAu{PhNCSNCy₂}]BPh₄ confirmed the coordination of the thiourea to the gold centre through the N and S atoms. In both cases the geometry around the gold atom is square-planar with complex [AnpAu{PhNCSNCy₂}]BPh₄ showing a slightly more puckered conformation than [AnpAu{PhNCSNMe₂}]BPh₄ due to the sterically bulky cyclohexyl groups attached. Some thiourea derivatives were tested against P388 murine leukaemia cells with complex [AnpAu{PhNCSNHPh}]BPh₄ showing promising anti-tumour activity.

When thiourea ligands were replaced by dithiophosphinate and dithiophosphate ligands the reaction proceeded at room temperature without the need for the presence of a base. Relatively low yields of impure metallacycles with the general formula (C,N)Au{S₂PR₂}+ were obtained on the addition of BPh₄- or BF₄-. Attempts to improve purity by varying batches of starting materials, anion and solvents used were unsuccessful. X-ray crystal data from a single crystal of [(C,N)Au{S₂PPh₂}]BPh₄ shows the reduction of gold(III) to gold(I) forming a known polymeric gold(I) dithiophosphinate complex. In order to extend this study the synthesis of complexes with the general formula R₂PS₂AuCl₂ was attempted, but no new compounds were characterised.

Where possible, all new compounds reported in this thesis were characterised by ES-MS, IR, NMR, melting point and micro-elemental analysis.

year: 2012

title: Shareholders’ requirements for corporate environmental disclosures: A cross country comparison

authors: de Villiers, Charl

subjects: Shareholders’ opinions

abstract: e survey individual shareholders in Australia, the UK and the US regarding corporate environmental disclosures. In general, respondents in the three countries are interested in, and positively disposed towards, these disclosures. We observe country and gender differences with Australian and female respondents more in favour of environmental reporting than others. Specifically, respondents require disclosure of an overview of environmental risks and impacts, the environmental policy, performance against measurable environmental targets and information on a range of environmental costs. Most shareholders require environmental disclosures to be audited. Shareholders call for environmental information because they believe managers should be accountable to shareholders for their companies’ environmental impacts. Furthermore, shareholders have indicated the uses for specific types of environmental information. Our results imply that legislators, standard setters and companies have to consider the policy implications of these shareholder views.

text: Shareholders’ requirements for corporate environmental disclosures: A cross country comparison e survey individual shareholders in Australia, the UK and the US regarding corporate environmental disclosures. In general, respondents in the three countries are interested in, and positively disposed towards, these disclosures. We observe country and gender differences with Australian and female respondents more in favour of environmental reporting than others. Specifically, respondents require disclosure of an overview of environmental risks and impacts, the environmental policy, performance against measurable environmental targets and information on a range of environmental costs. Most shareholders require environmental disclosures to be audited. Shareholders call for environmental information because they believe managers should be accountable to shareholders for their companies’ environmental impacts. Furthermore, shareholders have indicated the uses for specific types of environmental information. Our results imply that legislators, standard setters and companies have to consider the policy implications of these shareholder views.

year: 2010

title: He whiringa aroha: A mokopuna and a pare in the peabody essex museum

authors: Murray, Moana

abstract: Taonga, Māori ancestral treasures, embody the mana and knowledge of Māori ancestors. He Whiringa Aroha is one such treasure: a carved pare that affirms the mana of wāhine in the colonial archives, but whose whakapapa has been obscured. This thesis uses the name ‘He Whiringa Aroha’ and the te reo Māori pronoun ‘ia’ to refer to ‘E5501’, which is located in the 1806 Richardson collection in the Peabody Essex Museum. As He Whiringa Aroha travelled from Aotearoa New Zealand to Massachusetts, United States, ia became entangled in historical narratives that disembodied the taonga from hapū and iwi Māori. Taonga were not only physically removed from Aotearoa, but taonga and Māori creative practices were named, gendered, and displayed by colonisers. American sailors collected and displayed He Whiringa Aroha as an exotic ‘curiosity’ to showcase their triumph over Pacific waters. Yet, He Whiringa Aroha is a power portal—a potent braid to the past, the future, and to those Māori ways of being that defy the limiting archival language of colonialism. How do we relate to taonga Māori that have been fragmented by the colonial archive? What are alternatives to restory and reclaim taonga that remain in overseas museums? 

Using a creative methodology grounded in Mana Wahine and pūrākau, this thesis weaves a whiri (braid) of aroha (reverence) that attempts to restore he hononga mokopuna–the connection between taonga and their descendants. Through poetry, a decolonial map, interviews with ringatoi (Māori creatives), and archival research, I explore how the histories of taonga can be reclaimed in Māori worldviews. Interviews with pūkenga and tohunga toi reveal Māori understandings of taonga as expressions of toi, defying western taxonomies of ‘art’ and ‘curio’. Furthermore, archival research into the East India Marine Society and Peabody Essex Museum unmasks the American sailors and their provenance practices that
have marginalised Māori, and in particular, wāhine Māori. Finally, I use pūrākau of atua wāhine, Mana Wahine and takatāpui scholarship to restory and rename He Whiringa Aroha. This archival storytelling raises new ethical questions about ownership and kaitiakitanga (guardianship), which pose interventions for existing conversations about the place of taonga Māori in overseas museum collections. Reclaiming the histories of ancestors in museums is more than decolonizing colonial archives; on the contrary, restorying taonga is an act of Indigenous resurgence. This Masters research opens new possibilities to reclaiming takatāpui narratives and the mana of wahine in museum archives.

text: He whiringa aroha: A mokopuna and a pare in the peabody essex museum Taonga, Māori ancestral treasures, embody the mana and knowledge of Māori ancestors. He Whiringa Aroha is one such treasure: a carved pare that affirms the mana of wāhine in the colonial archives, but whose whakapapa has been obscured. This thesis uses the name ‘He Whiringa Aroha’ and the te reo Māori pronoun ‘ia’ to refer to ‘E5501’, which is located in the 1806 Richardson collection in the Peabody Essex Museum. As He Whiringa Aroha travelled from Aotearoa New Zealand to Massachusetts, United States, ia became entangled in historical narratives that disembodied the taonga from hapū and iwi Māori. Taonga were not only physically removed from Aotearoa, but taonga and Māori creative practices were named, gendered, and displayed by colonisers. American sailors collected and displayed He Whiringa Aroha as an exotic ‘curiosity’ to showcase their triumph over Pacific waters. Yet, He Whiringa Aroha is a power portal—a potent braid to the past, the future, and to those Māori ways of being that defy the limiting archival language of colonialism. How do we relate to taonga Māori that have been fragmented by the colonial archive? What are alternatives to restory and reclaim taonga that remain in overseas museums? 

Using a creative methodology grounded in Mana Wahine and pūrākau, this thesis weaves a whiri (braid) of aroha (reverence) that attempts to restore he hononga mokopuna–the connection between taonga and their descendants. Through poetry, a decolonial map, interviews with ringatoi (Māori creatives), and archival research, I explore how the histories of taonga can be reclaimed in Māori worldviews. Interviews with pūkenga and tohunga toi reveal Māori understandings of taonga as expressions of toi, defying western taxonomies of ‘art’ and ‘curio’. Furthermore, archival research into the East India Marine Society and Peabody Essex Museum unmasks the American sailors and their provenance practices that
have marginalised Māori, and in particular, wāhine Māori. Finally, I use pūrākau of atua wāhine, Mana Wahine and takatāpui scholarship to restory and rename He Whiringa Aroha. This archival storytelling raises new ethical questions about ownership and kaitiakitanga (guardianship), which pose interventions for existing conversations about the place of taonga Māori in overseas museum collections. Reclaiming the histories of ancestors in museums is more than decolonizing colonial archives; on the contrary, restorying taonga is an act of Indigenous resurgence. This Masters research opens new possibilities to reclaiming takatāpui narratives and the mana of wahine in museum archives.

year: 2024