title: Influence of chain length on mono- versus di-alkylation in the reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards α,ω-dihalo-n-alkanes; a synthetic route to platinum(II) ω-haloalkylthiolate complexes

authors: Devoy, Sarah M.

subjects: platinum complexes

abstract: The reactions of [Pt₂(μ-S)₂(PPh₃)₄] with a,x-dibromoalkanes Br(CH₂)nBr (n = 4, 5, 6, 8, 12) gave monoalkylated [Pt₂(μ-S){μ-S(CH₂)nBr}(PPh₃)₄]⁺ and/or di-alkylated [Pt₂(μ-S(CH₂)nS}(PPh₃)₄]²⁺ products, depending on the alkyl chain length and the reaction conditions. With longer chains (n = 8, 12), intramolecular di-alkylation does not proceed in refluxing methanol, with the mono-alkylated products [Pt₂ (μ-S){μ-S(CH₂)nBr}(PPh₃)₄]⁺ being the dominant products when excess alkylating agent is used. The bridged complex [{Pt₂(μ-S)₂(PPh₃)₄}₂{μ-(CH₂)12}]²⁺ was accessible from the reaction of [Pt₂ (μ-S)₂(PPh₃)₄] with 0.5 mol equivalents of Br(CH₂)12Br. [Pt₂(μ-S){μ-S(CH₂)₄Br}(PPh₃)₄]⁺ can be cleanly isolated as its BPh₄⁻ salt, but undergoes facile intramolecular di-alkylation at -18 degree C, giving the known species [Pt₂(μ-S(CH₂)₄S}(PPh₃)₄]²⁺. The reaction of I(CH₂)₆I with [Pt₂(μ-S)₂(PPh₃)₄] similarly gives [Pt₂ (μ-S){μ-S(CH₂)₆I}(PPh₃)₄]⁺, which is fairly stable towards intramolecular di-alkylation once isolated. These reactions provide a facile route to x-haloalkylthiolate complexes which are poorly defined in the literature. X-ray crystal structures of [Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]BPh₄ and [Pt₂(μ-S(CH₂)₅S} (PPh₃)₄](BPh₄)₂ are reported, together with a study of these complexes by electrospray ionisation mass spectrometry. All complexes fragment by dissociation of PPh₃ ligands, and the bromoalkylthiolate complexes show additional fragment ions [Pt₂(μ-S){μ-S(CH₂)n_2CH=CH₂}(PPh₃)m]⁺ (m = 2 or 3; m – 4), most significant for n = 4, formed by elimination of HBr.

text: Influence of chain length on mono- versus di-alkylation in the reactivity of [Pt₂(μ-S)₂(PPh₃)₄] towards α,ω-dihalo-n-alkanes; a synthetic route to platinum(II) ω-haloalkylthiolate complexes The reactions of [Pt₂(μ-S)₂(PPh₃)₄] with a,x-dibromoalkanes Br(CH₂)nBr (n = 4, 5, 6, 8, 12) gave monoalkylated [Pt₂(μ-S){μ-S(CH₂)nBr}(PPh₃)₄]⁺ and/or di-alkylated [Pt₂(μ-S(CH₂)nS}(PPh₃)₄]²⁺ products, depending on the alkyl chain length and the reaction conditions. With longer chains (n = 8, 12), intramolecular di-alkylation does not proceed in refluxing methanol, with the mono-alkylated products [Pt₂ (μ-S){μ-S(CH₂)nBr}(PPh₃)₄]⁺ being the dominant products when excess alkylating agent is used. The bridged complex [{Pt₂(μ-S)₂(PPh₃)₄}₂{μ-(CH₂)12}]²⁺ was accessible from the reaction of [Pt₂ (μ-S)₂(PPh₃)₄] with 0.5 mol equivalents of Br(CH₂)12Br. [Pt₂(μ-S){μ-S(CH₂)₄Br}(PPh₃)₄]⁺ can be cleanly isolated as its BPh₄⁻ salt, but undergoes facile intramolecular di-alkylation at -18 degree C, giving the known species [Pt₂(μ-S(CH₂)₄S}(PPh₃)₄]²⁺. The reaction of I(CH₂)₆I with [Pt₂(μ-S)₂(PPh₃)₄] similarly gives [Pt₂ (μ-S){μ-S(CH₂)₆I}(PPh₃)₄]⁺, which is fairly stable towards intramolecular di-alkylation once isolated. These reactions provide a facile route to x-haloalkylthiolate complexes which are poorly defined in the literature. X-ray crystal structures of [Pt₂(μ-S){μ-S(CH₂)₅Br}(PPh₃)₄]BPh₄ and [Pt₂(μ-S(CH₂)₅S} (PPh₃)₄](BPh₄)₂ are reported, together with a study of these complexes by electrospray ionisation mass spectrometry. All complexes fragment by dissociation of PPh₃ ligands, and the bromoalkylthiolate complexes show additional fragment ions [Pt₂(μ-S){μ-S(CH₂)n_2CH=CH₂}(PPh₃)m]⁺ (m = 2 or 3; m – 4), most significant for n = 4, formed by elimination of HBr.

year: 2010

title: An investigation into tacit knowledge management at the supervisory level.

authors: Williams, David John

subjects: tacit knowledge

abstract: An investigation into tacit knowledge management at the supervisory level Objective: The purpose of this study was to investigate how supervisors managed tacit knowledge. Aims: The aims were to understand what tacit knowledge looked like on the shop floor, to understand "experience‟ in terms of tacit knowledge, and to describe the methods and techniques that supervisors used to manage this elusive resource as they went about the task of achieving organisational goals. Method: Qualitative data was collected using a novel iterative participant observation method, where the researcher-as-instrument was embedded as a novice (but privileged) employee for extended periods in four different case study sites. Over the course of the study, the researcher took on the role of laboratory technician, electrical engineer, manufacturing process worker, and aircraft maintenance engineer. A grounded theory approach was taken to the analysis of the various field notes, photographs, video, audio, and found objects. The methodology was augmented with specialist qualitative research software to manage the data. Results: It was found that supervisors' tacit knowledge management activities can be classified according to formal and informal behaviours that correspond with Nonaka and Takeuchi's SECI knowledge life cycle. It was also found that a worker's task related tacit knowledge has seven aspects in five levels of competency, and their experience can be described in terms of 10 categories of tacit knowledge working capital. Insights attributed to the novel method of data collection produced an unexpected finding – the Home Guard model, which describes how the value of an individual's knowledge sharing activities is related to their power distance and self-confidence. Conclusions: The findings provide empirical support for existing knowledge management theory, identify specific supervisory behaviours that support tacit knowledge management on the shop floor, and extend the knowledge management discourse with new theories about knowledge sharing behaviours that have direct application to the supervisory role.

text: An investigation into tacit knowledge management at the supervisory level. An investigation into tacit knowledge management at the supervisory level Objective: The purpose of this study was to investigate how supervisors managed tacit knowledge. Aims: The aims were to understand what tacit knowledge looked like on the shop floor, to understand "experience‟ in terms of tacit knowledge, and to describe the methods and techniques that supervisors used to manage this elusive resource as they went about the task of achieving organisational goals. Method: Qualitative data was collected using a novel iterative participant observation method, where the researcher-as-instrument was embedded as a novice (but privileged) employee for extended periods in four different case study sites. Over the course of the study, the researcher took on the role of laboratory technician, electrical engineer, manufacturing process worker, and aircraft maintenance engineer. A grounded theory approach was taken to the analysis of the various field notes, photographs, video, audio, and found objects. The methodology was augmented with specialist qualitative research software to manage the data. Results: It was found that supervisors' tacit knowledge management activities can be classified according to formal and informal behaviours that correspond with Nonaka and Takeuchi's SECI knowledge life cycle. It was also found that a worker's task related tacit knowledge has seven aspects in five levels of competency, and their experience can be described in terms of 10 categories of tacit knowledge working capital. Insights attributed to the novel method of data collection produced an unexpected finding – the Home Guard model, which describes how the value of an individual's knowledge sharing activities is related to their power distance and self-confidence. Conclusions: The findings provide empirical support for existing knowledge management theory, identify specific supervisory behaviours that support tacit knowledge management on the shop floor, and extend the knowledge management discourse with new theories about knowledge sharing behaviours that have direct application to the supervisory role.

year: 2011

title: Spot sampling of nutrient concentrations in the Puarenga catchment, Rotorua

authors: Abell, Jonathan Michael

subjects: New Zealand

abstract: The Centre for Biodiversity and Ecology Research was approached by Tūhourangi Tribal Authority for assistance with measuring water quality in streams in the Puarenga Stream catchment. Water sampling was subsequently undertaken on 18 July 2011 and samples were analysed to determine concentrations of total and dissolved fractions of nitrogen and phosphorus. 
Nitrogen and phosphorus are both essential plant nutrients which, when present in excess, can cause eutrophication and associated water quality decline of freshwaters. High concentrations of dissolved forms of nitrogen can also be toxic to aquatic organisms. Excessive nitrogen and phosphorus concentrations are typically the result of pollution due to human activities, although groundwater in the Central Volcanic Plateau region can have elevated concentrations of phosphorus arising from natural geological sources.
This report summarises the methods used, presents the results and places measured concentrations in context by drawing comparisons with both guideline and regional mean values.

text: Spot sampling of nutrient concentrations in the Puarenga catchment, Rotorua The Centre for Biodiversity and Ecology Research was approached by Tūhourangi Tribal Authority for assistance with measuring water quality in streams in the Puarenga Stream catchment. Water sampling was subsequently undertaken on 18 July 2011 and samples were analysed to determine concentrations of total and dissolved fractions of nitrogen and phosphorus. 
Nitrogen and phosphorus are both essential plant nutrients which, when present in excess, can cause eutrophication and associated water quality decline of freshwaters. High concentrations of dissolved forms of nitrogen can also be toxic to aquatic organisms. Excessive nitrogen and phosphorus concentrations are typically the result of pollution due to human activities, although groundwater in the Central Volcanic Plateau region can have elevated concentrations of phosphorus arising from natural geological sources.
This report summarises the methods used, presents the results and places measured concentrations in context by drawing comparisons with both guideline and regional mean values.

year: 2011-09