title: Isomerism of Complexes Containing Thiourea Dianion Ligands

authors: Spenceley, Jane Estelle

subjects: Thiourea

abstract: This thesis reports the synthesis and characterisation of eight new platinum thiourea complexes. Thiourea dianion complexes of the type (Ph₃P)₂PtSC(=NR)NPh, R=Me, Et, Prⁿ, Prⁱ, Buⁿ and (Ph₃P)₂PtSC(=NPh)NR R=Buͭ , p-tol, and the thiourea monoanion complex of the type [(Ph₃P)₂PtSC(=NEtH)NPh]⁺ were synthesised. This research confirms the prediction made by Henderson et al that asymmetrically substituted thiourea dianion complexes could form isomers. NMR studies show that the kinetically favoured isomer is formed initially, and then undergoes a solution phase isomerisation process to form the thermodynamically favoured isomer. Evidence that this isomerisation is affected by difference in substituent size and the energy difference between the two structures was obtained both experimentally, by use of NMR spectroscopy techniques, and theoretically using DFT calculations. Theoretically optimised geometries of each isomer allowed the calculation of ΔG(GPtrem-GPtadj) for each pair. NMR techniques were used to monitor the isomerisation process, which was clearly visible in both ¹H and ³¹P spectra. The relative substituent size, difference in energy between the two structures and rate of isomerisation appear to be proportional to each other. The greater the substituent size difference, the greater the difference in energy and faster the rate of isomerisation from the kinetically favoured isomer to the thermodynamically favoured isomer.

text: Isomerism of Complexes Containing Thiourea Dianion Ligands This thesis reports the synthesis and characterisation of eight new platinum thiourea complexes. Thiourea dianion complexes of the type (Ph₃P)₂PtSC(=NR)NPh, R=Me, Et, Prⁿ, Prⁱ, Buⁿ and (Ph₃P)₂PtSC(=NPh)NR R=Buͭ , p-tol, and the thiourea monoanion complex of the type [(Ph₃P)₂PtSC(=NEtH)NPh]⁺ were synthesised. This research confirms the prediction made by Henderson et al that asymmetrically substituted thiourea dianion complexes could form isomers. NMR studies show that the kinetically favoured isomer is formed initially, and then undergoes a solution phase isomerisation process to form the thermodynamically favoured isomer. Evidence that this isomerisation is affected by difference in substituent size and the energy difference between the two structures was obtained both experimentally, by use of NMR spectroscopy techniques, and theoretically using DFT calculations. Theoretically optimised geometries of each isomer allowed the calculation of ΔG(GPtrem-GPtadj) for each pair. NMR techniques were used to monitor the isomerisation process, which was clearly visible in both ¹H and ³¹P spectra. The relative substituent size, difference in energy between the two structures and rate of isomerisation appear to be proportional to each other. The greater the substituent size difference, the greater the difference in energy and faster the rate of isomerisation from the kinetically favoured isomer to the thermodynamically favoured isomer.

year: 2014

title: Construction of Good Rank-1 Lattice Rules Based on the Weighted Star Discrepancy

authors: Joe, Stephen

subjects: mathematics

abstract: The ‘goodness’ of a set of quadrature points in [0, 1]d may be measured by the weighted star discrepancy. If the weights for the weighted star discrepancy are summable, then we show that for n prime there exist n-point rank-1 lattice rules whose weighted star discrepancy is O(n−1+δ) for any δ>0, where the implied constant depends on δ and the weights, but is independent of d and n. Further, we show that the generating vector z for such lattice rules may be obtained using a component-by-component construction. The results given here for the weighted star discrepancy are used to derive corresponding results for a weighted Lp discrepancy.

text: Construction of Good Rank-1 Lattice Rules Based on the Weighted Star Discrepancy The ‘goodness’ of a set of quadrature points in [0, 1]d may be measured by the weighted star discrepancy. If the weights for the weighted star discrepancy are summable, then we show that for n prime there exist n-point rank-1 lattice rules whose weighted star discrepancy is O(n−1+δ) for any δ>0, where the implied constant depends on δ and the weights, but is independent of d and n. Further, we show that the generating vector z for such lattice rules may be obtained using a component-by-component construction. The results given here for the weighted star discrepancy are used to derive corresponding results for a weighted Lp discrepancy.

year: 2006

title: Maori and goldfields revenue

authors: Hart, Philip

abstract: When gold was first discovered, the Crown accepted that it needed Maori consent to open their land for mining and had to assuage fears of losing their land. Accordingly, officials devised agreements to protect Maori interests and to provide a financial return. Because of what had occurred in other countries after goldfields opened, both Maori and the government agreed that these must be well controlled. Over time, the regulations increasingly favoured the mining industry rather than the original landowners, who were not informed about the true value of their land, auriferous or otherwise. Maori were confused about their financial entitlement because of changes made by the government to the fees payable to them. 
Some rangatira, most notably Wirope Hoterene Taipari of Ngati Maru, saw a chance to obtain unexpected (and unearned) wealth, as shown by his insistence on opening Thames to miners despite the opposition of most of his hapu. Later, other rangatira wanted to open Ohinemuri and other potential fields because of the money they were promised by impatient miners and by more patient officials. For a brief time, some Maori considered controlling the potential Ohinemuri goldfield themselves. The main incentive to opening land was the wealth received by landowners during the early days of the Thames goldfield, but as mining faded later so did goldfields revenue. Changes to mining regulations diminished the amount distributed to Maori in ways that some Pakeha considered unfair, and these provoked complaints from Maori.
A continuing problem for officials was to ensure that revenue was allocated to the right owners. The system was complex, resulting in delays in paying money and in some Maori obtaining too much and others too little (or none at all), an outcome often resulting from rangatira distributing it as they chose rather than caused by government officials, who did their best to ensure fairness. Over time, the government unilaterally made changes to the system. For their part, miners complained about being required to pay for the right to mine, and encouraged the government to acquire the freehold of goldfield land because miners’ rights on Crown land were one-quarter the cost of those on Maori land. 
The revenue received by the landowners soon slipped through their fingers, sometimes in traditionally competitive gatherings such as tangi. It can be argued that Taipari, who very shrewdly adapted to the new economy (and experienced its perils, becoming bankrupt in 1870), used his income not just to give himself a luxurious lifestyle but also to boost the mana of his hapu. The government has been blamed for not insisting that revenue be protected for the use of future generations, a concept that occurred to only a few Pakeha at the time and to no Maori; far from considering the interests of their descendents, cultivating the land decreased while this revenue was received. But due to the nature of mining, by the twentieth century the landowners were lamenting the serious decline in their income from this source; despite having sold so much of their goldfield lands, some complained at not receiving any more revenue. 
Evaluating the outcome, the Waitangi Tribunal indulged in some counter-factual history by suggesting that the government should have encouraged rangatira to set up trusts to protect the income for future generations, but no rangatira had suggested this idea, nor did they ask that they should manage goldfields jointly with the Crown. After imagining that Maori in partnership with Pakeha capitalists could have developed the goldfields without the involvement of the Crown, the Tribunal had to accept that the outcome would have been the same: loss of money (because apart from anything else mining could not remain payable indefinitely) combined with the loss of much of their land.

text: Maori and goldfields revenue When gold was first discovered, the Crown accepted that it needed Maori consent to open their land for mining and had to assuage fears of losing their land. Accordingly, officials devised agreements to protect Maori interests and to provide a financial return. Because of what had occurred in other countries after goldfields opened, both Maori and the government agreed that these must be well controlled. Over time, the regulations increasingly favoured the mining industry rather than the original landowners, who were not informed about the true value of their land, auriferous or otherwise. Maori were confused about their financial entitlement because of changes made by the government to the fees payable to them. 
Some rangatira, most notably Wirope Hoterene Taipari of Ngati Maru, saw a chance to obtain unexpected (and unearned) wealth, as shown by his insistence on opening Thames to miners despite the opposition of most of his hapu. Later, other rangatira wanted to open Ohinemuri and other potential fields because of the money they were promised by impatient miners and by more patient officials. For a brief time, some Maori considered controlling the potential Ohinemuri goldfield themselves. The main incentive to opening land was the wealth received by landowners during the early days of the Thames goldfield, but as mining faded later so did goldfields revenue. Changes to mining regulations diminished the amount distributed to Maori in ways that some Pakeha considered unfair, and these provoked complaints from Maori.
A continuing problem for officials was to ensure that revenue was allocated to the right owners. The system was complex, resulting in delays in paying money and in some Maori obtaining too much and others too little (or none at all), an outcome often resulting from rangatira distributing it as they chose rather than caused by government officials, who did their best to ensure fairness. Over time, the government unilaterally made changes to the system. For their part, miners complained about being required to pay for the right to mine, and encouraged the government to acquire the freehold of goldfield land because miners’ rights on Crown land were one-quarter the cost of those on Maori land. 
The revenue received by the landowners soon slipped through their fingers, sometimes in traditionally competitive gatherings such as tangi. It can be argued that Taipari, who very shrewdly adapted to the new economy (and experienced its perils, becoming bankrupt in 1870), used his income not just to give himself a luxurious lifestyle but also to boost the mana of his hapu. The government has been blamed for not insisting that revenue be protected for the use of future generations, a concept that occurred to only a few Pakeha at the time and to no Maori; far from considering the interests of their descendents, cultivating the land decreased while this revenue was received. But due to the nature of mining, by the twentieth century the landowners were lamenting the serious decline in their income from this source; despite having sold so much of their goldfield lands, some complained at not receiving any more revenue. 
Evaluating the outcome, the Waitangi Tribunal indulged in some counter-factual history by suggesting that the government should have encouraged rangatira to set up trusts to protect the income for future generations, but no rangatira had suggested this idea, nor did they ask that they should manage goldfields jointly with the Crown. After imagining that Maori in partnership with Pakeha capitalists could have developed the goldfields without the involvement of the Crown, the Tribunal had to accept that the outcome would have been the same: loss of money (because apart from anything else mining could not remain payable indefinitely) combined with the loss of much of their land.

year: 2016