title: The synthesis of water-soluble analogues of Pt₂(μ₂-S)₂(PPh₃)₄

authors: Sutton, Ryan

subjects: Chemistry

abstract: Platinum has a very rich chemistry with sulfur, and this field has been extensively studied. Of particular interest are complexes containing the {Pt₂(μ₂-S)₂} core, comprising two platinum atoms with μ₂-sulfurs bridging through a flexible hinge. These complexes can act as potent metalloligands (through the two sulfurs) toward a wide range of transition metal and other centres, allowing for the synthesis of complexes with trinuclear mixed-metal cores {Pt₂(μ₃-S)₂M} (M = heterometal). The {Pt₂(μ₂-S)₂} core is also highly nucleophilic and alkylated by the mildest of reagents. The ancillary ligands coordinated to the {Pt₂(μ₂-S)₂} core are primarily triphenylphosphine (PPh₃), resulting in the complexes being significantly insoluble in water, preventing any forms of bioactivity or biphasic catalysis from being assessed.
This research project has widened the scope of {Pt₂(μ₂-S)₂} complexes via the synthesis of the new water-soluble complexes {Pt₂(μ₂-S)₂}(PTA)₄, [Pt₂(μ₃- S)₂(PTA)₄Rh(cod)]Cl, and [Pt₃(μ3-S)₂(PTA)6]²⁺ (PTA = 1,3,5-triaza-7- phosphaadamantane, cod = 1,5-cyclooctadiene) that were characterised by electrospray ionisation mass spectrometry (ESI-MS) and phosphorus-31 nuclear magnetic resonance spectroscopy (³¹P{¹H} NMR). The complex [Pt₃(μ₃- S)₂(PTA)₆]²⁺ was synthesised during the research into the use of a sulfide exchange column as an alternative source of sulfide for the synthesis of Pt₂(μ₂- S)₂(PTA)₄.
The water-soluble phosphine ligands tris(2-carboxyethyl)phosphine (TCEP) and monosulfonated triphenylphosphine [TPPMS]⁻ were determined to be unsuitable ligands for complexes of the general form {Pt₂(μ₂-S)₂}(L)₄ (L = TCEP, [TPPMS]⁻). During these attempted syntheses the complex {Pt₂(μ₂-S)₂} (cod)₂ was successfully produced and characterised with ESI-MS, ¹H NMR, ¹H-¹H COSY, and ¹³C-¹H HSQC (Proton nuclear magnetic resonance spectroscopy, Correlation Spectroscopy, Heteronuclear Single Quantum Coherence).
The use of thioacetamide (CH₂C(S)NH₂) as an alternative source of sulfide in the synthesis of {Pt₂(μ₂-S)₂}(PPh₃)₄ was found to be a poor substitute for the well established Na₂S·9H₂O. The reaction does result in [Pt(CH₃C(S)NH)(PPh₃)₂]⁺+, subsequently isolated as the BPh₄- salt, [Pt(CH₃C(S)NH)(PPh₃)₂](BPh₄) and was characterised by ESI-MS and ³¹P{1H} NMR. The X-ray crystal structure of the by-product trans-Pt(SC(O)CH₃)₂(PPh₃)₂ was obtained.

text: The synthesis of water-soluble analogues of Pt₂(μ₂-S)₂(PPh₃)₄ Platinum has a very rich chemistry with sulfur, and this field has been extensively studied. Of particular interest are complexes containing the {Pt₂(μ₂-S)₂} core, comprising two platinum atoms with μ₂-sulfurs bridging through a flexible hinge. These complexes can act as potent metalloligands (through the two sulfurs) toward a wide range of transition metal and other centres, allowing for the synthesis of complexes with trinuclear mixed-metal cores {Pt₂(μ₃-S)₂M} (M = heterometal). The {Pt₂(μ₂-S)₂} core is also highly nucleophilic and alkylated by the mildest of reagents. The ancillary ligands coordinated to the {Pt₂(μ₂-S)₂} core are primarily triphenylphosphine (PPh₃), resulting in the complexes being significantly insoluble in water, preventing any forms of bioactivity or biphasic catalysis from being assessed.
This research project has widened the scope of {Pt₂(μ₂-S)₂} complexes via the synthesis of the new water-soluble complexes {Pt₂(μ₂-S)₂}(PTA)₄, [Pt₂(μ₃- S)₂(PTA)₄Rh(cod)]Cl, and [Pt₃(μ3-S)₂(PTA)6]²⁺ (PTA = 1,3,5-triaza-7- phosphaadamantane, cod = 1,5-cyclooctadiene) that were characterised by electrospray ionisation mass spectrometry (ESI-MS) and phosphorus-31 nuclear magnetic resonance spectroscopy (³¹P{¹H} NMR). The complex [Pt₃(μ₃- S)₂(PTA)₆]²⁺ was synthesised during the research into the use of a sulfide exchange column as an alternative source of sulfide for the synthesis of Pt₂(μ₂- S)₂(PTA)₄.
The water-soluble phosphine ligands tris(2-carboxyethyl)phosphine (TCEP) and monosulfonated triphenylphosphine [TPPMS]⁻ were determined to be unsuitable ligands for complexes of the general form {Pt₂(μ₂-S)₂}(L)₄ (L = TCEP, [TPPMS]⁻). During these attempted syntheses the complex {Pt₂(μ₂-S)₂} (cod)₂ was successfully produced and characterised with ESI-MS, ¹H NMR, ¹H-¹H COSY, and ¹³C-¹H HSQC (Proton nuclear magnetic resonance spectroscopy, Correlation Spectroscopy, Heteronuclear Single Quantum Coherence).
The use of thioacetamide (CH₂C(S)NH₂) as an alternative source of sulfide in the synthesis of {Pt₂(μ₂-S)₂}(PPh₃)₄ was found to be a poor substitute for the well established Na₂S·9H₂O. The reaction does result in [Pt(CH₃C(S)NH)(PPh₃)₂]⁺+, subsequently isolated as the BPh₄- salt, [Pt(CH₃C(S)NH)(PPh₃)₂](BPh₄) and was characterised by ESI-MS and ³¹P{1H} NMR. The X-ray crystal structure of the by-product trans-Pt(SC(O)CH₃)₂(PPh₃)₂ was obtained.

year: 2019

title: A high resolution full-field range imaging system for robotic devices

authors: Carnegie, Dale A.

subjects: robot sensing

abstract: There has been considerable effort by many researchers to develop a high resolution full-field range imaging system. Traditionally these systems rely on a homodyne technique that modulates the illumination source and shutter speed at some high frequency. These systems tend to suffer from the need to be calibrated to account for changing ambient light conditions and generally cannot provide better than single centimeter range resolution, and even then over a range of only a few meters. We present a system, tested to proof-of-concept stage that is being developed for use on a range of mobile robots. The system has the potential for real-time, sub millimeter range resolution, with minimal power and space requirements.

text: A high resolution full-field range imaging system for robotic devices There has been considerable effort by many researchers to develop a high resolution full-field range imaging system. Traditionally these systems rely on a homodyne technique that modulates the illumination source and shutter speed at some high frequency. These systems tend to suffer from the need to be calibrated to account for changing ambient light conditions and generally cannot provide better than single centimeter range resolution, and even then over a range of only a few meters. We present a system, tested to proof-of-concept stage that is being developed for use on a range of mobile robots. The system has the potential for real-time, sub millimeter range resolution, with minimal power and space requirements.

year: 2005

title: E Ara Apanui

authors: Maxwell, Te Kahautu

abstract: E Ara Apanui recites the genealogical links between the Te Whakatōhea iwi and the host people of the Te Whānau a Apanui iwi. This new composition was performed by Ōpōtiki Mai Tawhiti at the Mātaatua Regional Kapa Haka Competition to qualify for Te Matatini 2013.

text: E Ara Apanui E Ara Apanui recites the genealogical links between the Te Whakatōhea iwi and the host people of the Te Whānau a Apanui iwi. This new composition was performed by Ōpōtiki Mai Tawhiti at the Mātaatua Regional Kapa Haka Competition to qualify for Te Matatini 2013.

year: 2012