title: An X-ray absorption spectroscopy investigation of the coordination environment of electrogenerated Ni(ii)-pseudohalide complexes arising from the anodic polarization of Ni electrodes in DMSO solutions of NCO⁻ , NCS⁻ and NCSe⁻ ions

authors: Alwis, Kethsiri H.K.L.

subjects: EXAFS/XANES

abstract: X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) were used to provide direct information in solution on the coordination state of electrogenerated products from anodically polarized nickel electrodes in pseudohalide-ion-containing dimethyl sulfoxide (DMSO) solvent (i.e. NCX⁻, X = O, S, Se) in the presence of a supporting electrolyte of tetrabutylammonium perchlorate (TBAP). Electrogenerated solutions and model solutions representative of the chemical speciation in electrolyzed systems (prepared by mixing Ni(II) and pseudohalide ion solutions in DMSO), were also examined. In general for Ni(II) interacting with NCS⁻ and NCSe⁻, the complex ion generated appears to be 6-coordinate [Ni(NCX)(DMSO)5]⁺, while EXAFS/XANES data of the Ni/cyanate system suggest an average coordination number of 5, which in reality is due to the electrogenerated solution containing a mixture of 4 coordinate (tetrahedral) [Ni(NCO)4]²⁻ and octahedral [Ni(DMSO)6]²⁺ species. These observations of the octahedral geometry for the Ni(II)/thiocyanate and Ni(II)/selenocyanate systems and 5-coordinate geometry in the Ni(II)/cyanate systems (being electrogenerated products of anodic polarisation of Ni in the DMSO-supported pseudohalide ion electrolytes) agree with the differences in colour observed between samples. EXAFS/XANES measurements combined with IR spectroelectrochemical analyses of solutions provide a versatile way of analyzing these electrochemical systems without the need for isolating compounds from the electrolyte.

text: An X-ray absorption spectroscopy investigation of the coordination environment of electrogenerated Ni(ii)-pseudohalide complexes arising from the anodic polarization of Ni electrodes in DMSO solutions of NCO⁻ , NCS⁻ and NCSe⁻ ions X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) were used to provide direct information in solution on the coordination state of electrogenerated products from anodically polarized nickel electrodes in pseudohalide-ion-containing dimethyl sulfoxide (DMSO) solvent (i.e. NCX⁻, X = O, S, Se) in the presence of a supporting electrolyte of tetrabutylammonium perchlorate (TBAP). Electrogenerated solutions and model solutions representative of the chemical speciation in electrolyzed systems (prepared by mixing Ni(II) and pseudohalide ion solutions in DMSO), were also examined. In general for Ni(II) interacting with NCS⁻ and NCSe⁻, the complex ion generated appears to be 6-coordinate [Ni(NCX)(DMSO)5]⁺, while EXAFS/XANES data of the Ni/cyanate system suggest an average coordination number of 5, which in reality is due to the electrogenerated solution containing a mixture of 4 coordinate (tetrahedral) [Ni(NCO)4]²⁻ and octahedral [Ni(DMSO)6]²⁺ species. These observations of the octahedral geometry for the Ni(II)/thiocyanate and Ni(II)/selenocyanate systems and 5-coordinate geometry in the Ni(II)/cyanate systems (being electrogenerated products of anodic polarisation of Ni in the DMSO-supported pseudohalide ion electrolytes) agree with the differences in colour observed between samples. EXAFS/XANES measurements combined with IR spectroelectrochemical analyses of solutions provide a versatile way of analyzing these electrochemical systems without the need for isolating compounds from the electrolyte.

year: 2015

title: Germanium hydride derivatives of transition metal carbonyls

authors: Christie, Judy A.

abstract: Compounds of the type Fe(CO)₄(GeR₃)₂ containing two different methylgermyl substituents have been prepared and characterised. The preparation was via the exchange reaction

Fe(CO)₄(GeR₃)₂ + [Mn(CO)₅]⁻ → [Fe(CO)₄(GeR₃)]⁻ + Mn(CO)₅(GeR₃)

[Fe(CO)₄(GeR₃)]⁻ + GeXR’₃ → Fe(CO)₄(GeR₃)(GeR’₃)


The compounds characterised were Fe(CO)₄(GeMeH₂) (GeH₃) Fe(CO)₄(GeMe₂H) (GeH₃), Fe(CO)₄ (GeMe₂H) (GeMeH₂), Fe(CO)₄(GeMe₃) (GeH₃) Fe(CO)₄(GeMe₃)(GeMeH₂) and Fe(CO)₄(GeMe₃)(GeMe₂H). Of these, the species Fe(CO)₄(GeMeH₂) (GeH₃) were characterised fully by infrared, proton nmr and mass spectroscopic studies.


The self-reaction 

2Fe(CO)₄(GeR₃)₂ → [Fe(CO)₄(GeR₂)]₂ + 2GeR₄

has also been examined in some detail. The methylgermane was eliminated in preference to GeH₄ and species of the type [Fe(CO)₄(GeH₃)]₂-GeR₂ were also identified in two cases. 

Halogenation of Fe(CO)₄(GeMeH₃) (GeH₃) and Fe(CO)₄(GeMe₂H) (GeH3) was followed by ¹H nmr studies. CCℓ₄ results in the substitution of Ge-H, while HCℓ cleaves Fe-Ge bonds. 

While Fe(CO)₄(GeMe₂H) (GeMeH₂), Fe(CO)₄(GeMe₃) (GeMeH₂) and Fe(CO)₄(GeMe₃) (GeMe₂H) have been prepared, spectroscopic identification of these species is rather tenuous as these samples were found always to be contaminated with either the symmetrically substituted species Fe(CO)₄(GeR₃)₂ and/or products from the self-reaction. 

Mn(CO)₅(GeR₃) species obtained in the above syntheses react with Co₂(CO)₈ to yield the species [Co₃ (CO)₉][Mn(CO)₅]Ge, [Co₂(CO)₇[Mn(CO)₅]GeMe and possibly [Co(CO)₄][Mn(CO)₅]GeMe₂. 

These species were characterised by their infrared and mass spectroscopic properties.

text: Germanium hydride derivatives of transition metal carbonyls Compounds of the type Fe(CO)₄(GeR₃)₂ containing two different methylgermyl substituents have been prepared and characterised. The preparation was via the exchange reaction

Fe(CO)₄(GeR₃)₂ + [Mn(CO)₅]⁻ → [Fe(CO)₄(GeR₃)]⁻ + Mn(CO)₅(GeR₃)

[Fe(CO)₄(GeR₃)]⁻ + GeXR’₃ → Fe(CO)₄(GeR₃)(GeR’₃)


The compounds characterised were Fe(CO)₄(GeMeH₂) (GeH₃) Fe(CO)₄(GeMe₂H) (GeH₃), Fe(CO)₄ (GeMe₂H) (GeMeH₂), Fe(CO)₄(GeMe₃) (GeH₃) Fe(CO)₄(GeMe₃)(GeMeH₂) and Fe(CO)₄(GeMe₃)(GeMe₂H). Of these, the species Fe(CO)₄(GeMeH₂) (GeH₃) were characterised fully by infrared, proton nmr and mass spectroscopic studies.


The self-reaction 

2Fe(CO)₄(GeR₃)₂ → [Fe(CO)₄(GeR₂)]₂ + 2GeR₄

has also been examined in some detail. The methylgermane was eliminated in preference to GeH₄ and species of the type [Fe(CO)₄(GeH₃)]₂-GeR₂ were also identified in two cases. 

Halogenation of Fe(CO)₄(GeMeH₃) (GeH₃) and Fe(CO)₄(GeMe₂H) (GeH3) was followed by ¹H nmr studies. CCℓ₄ results in the substitution of Ge-H, while HCℓ cleaves Fe-Ge bonds. 

While Fe(CO)₄(GeMe₂H) (GeMeH₂), Fe(CO)₄(GeMe₃) (GeMeH₂) and Fe(CO)₄(GeMe₃) (GeMe₂H) have been prepared, spectroscopic identification of these species is rather tenuous as these samples were found always to be contaminated with either the symmetrically substituted species Fe(CO)₄(GeR₃)₂ and/or products from the self-reaction. 

Mn(CO)₅(GeR₃) species obtained in the above syntheses react with Co₂(CO)₈ to yield the species [Co₃ (CO)₉][Mn(CO)₅]Ge, [Co₂(CO)₇[Mn(CO)₅]GeMe and possibly [Co(CO)₄][Mn(CO)₅]GeMe₂. 

These species were characterised by their infrared and mass spectroscopic properties.

year: 1981

title: The 2020 cannabis referendum: Māori voter support, racialized policing, and the Criminal Justice System

authors: Dempster, Craig

abstract: In the New Zealand 2020 cannabis referendum, 50.7% of all voters rejected the creation of a legally-regulated cannabis market and instead supported retaining the current prohibitionist policy. Although the referendum failed to pass, a majority of Māori voted in favor of cannabis law reform. This paper suggests that within the Māori community there is a more nuanced appreciation of the impact of policing cannabis. Māori perceive that greater harm is caused by the racialized policing of cannabis than by the usage of it. Following McCreanor, et al. (2014), this paper employs a thematic, content analysis of the New Zealand Herald’s coverage of the 2020 cannabis referendum to investigate the presence of race-based targeting/policing in discussions of the legislation. The results reveal that racial disparities emerged as secondary to framing both the impact of cannabis and the referendum as race-neutral and affecting everyone in society equally. This paper argues that the impact of the policing of this particular drug impacts Māori differently, wherein they bear the brunt of racialized policing. Thus, Māori possess a more sophisticated understanding that warrants consideration because it is inextricably linked to lived experiences of policing that differ from wider social narratives of policing and drug policy in New Zealand.

text: The 2020 cannabis referendum: Māori voter support, racialized policing, and the Criminal Justice System In the New Zealand 2020 cannabis referendum, 50.7% of all voters rejected the creation of a legally-regulated cannabis market and instead supported retaining the current prohibitionist policy. Although the referendum failed to pass, a majority of Māori voted in favor of cannabis law reform. This paper suggests that within the Māori community there is a more nuanced appreciation of the impact of policing cannabis. Māori perceive that greater harm is caused by the racialized policing of cannabis than by the usage of it. Following McCreanor, et al. (2014), this paper employs a thematic, content analysis of the New Zealand Herald’s coverage of the 2020 cannabis referendum to investigate the presence of race-based targeting/policing in discussions of the legislation. The results reveal that racial disparities emerged as secondary to framing both the impact of cannabis and the referendum as race-neutral and affecting everyone in society equally. This paper argues that the impact of the policing of this particular drug impacts Māori differently, wherein they bear the brunt of racialized policing. Thus, Māori possess a more sophisticated understanding that warrants consideration because it is inextricably linked to lived experiences of policing that differ from wider social narratives of policing and drug policy in New Zealand.

year: 2022