A social licence to operate: Corporate social responsibility, local communities and the constitution of global production networks

This article contributes to the theorization of the role of informal regulation (undertaken by leading firms) in the ongoing organization of global production networks. It does so through a qualitative case study of BHP Billiton's Ravensthorpe Nickel Operation (RNO) in the rural Shire of Ravensthorpe in Western Australia. This less tangible, and to date under-researched, dimension of global production networks is foregrounded through a focus on the corporate social responsibility strategy implemented by RNO in the service of achieving and/or demonstrating a broader ‘social licence to operate’. This ‘licence’ functions – beyond the corporation – as a legitimated and legitimating multi-scalar mechanism through which to gain and maintain access to mineral resources and thus to establish viable and ongoing global production networks. Further, this informal regulation is shown to shape social relations and qualities of place conducive to competitive global mineral extraction and to facilitate the positioning of local communities and places in mineral global production networks.

The exhaustive reduction of formylporphyrins to methylporphyrins using dimethylformamide/water as reductant under microwave irradiation

The reduction of meso-formyl derivatives of 5,15-diaryl- and 5,10,15-triphenylporphyrin (and their nickel(II) complexes) to the corresponding meso-methyl porphyrins is achieved in high yield by microwave heating of the substrate in dimethylformamide (DMF) in the presence of acids such as trifluoroacetic acid, or even just with added water. The reactions are complete in less than 30 min at 250 °C. The reaction is strongly suppressed in very dry DMF in the absence of added acid. The meso-hydroxymethyl porphyrins are also reduced to the methyl derivatives, suggesting the primary alcohols may be intermediates in the exhaustive reduction. UV-visible spectra taken at intervals during reaction at 240 °C indicated that at least one other intermediate is present, but it was not identified. In d7-DMF, the methylporphyrin isolated was mainly Por-CD2H, showing that both of the added hydrogens arise from the solvent, and not from the added water or acid.

Experimental and theoretical characterization of 5,10- diminoporphodimethenes: Dearomatized porphyrinoids from palladium-catalyzed hydrazinations of 5,10-diarylporphyrins

A new dearomatized porphyrinoid, 5,10-diiminoporphodimethene (5,10-DIPD), has been prepared by palladium-catalyzed hydrazination of 5,10-dibromo-15,20-bis(3,5-di-tert-butylphenyl)porphyrin and its nickel(II) complex, by using ethyl and 4-methoxybenzyl carbazates. The oxidative dearomatization of the porphyrin ring occurs in high yield. Further oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone forms the corresponding 5,10-bis(azocarboxylates), thereby restoring the porphyrin aromaticity. The UV/visible spectra of the NiII DIPDs exhibit remarkable redshifts of the lowest-energy bands to 780 nm, and differential pulse voltammetry reveals a contracted electrochemical HOMO–LUMO gap of 1.44 V. Density functional theory (DFT) was used to calculate the optimized geometries and frontier molecular orbitals of model 5,10-DIPD Ni7c and 5,10-bis(azocarboxylate) Ni8c. The conformations of the carbamate groups and the configurations of the CNZ unit were considered in conjunction with the NOESY spectra, to generate the global minimum geometry and two other structures with slightly higher energies. In the absence of solution data regarding conformations, ten possible local minimum conformations were considered for Ni8c. Partition of the porphyrin macrocycle into tri- and monopyrrole fragments in Ni7c and the inclusion of terminal conjugating functional groups generate unique frontier molecular orbital distributions and a HOMO–LUMO transition with a strong element of charge transfer from the monopyrrole ring. Time-dependent DFT calculations were performed for the three lowest-energy structures of Ni7c and Ni8c, and weighting according to their energies allowed the prediction of the electronic spectra. The calculations reproduce the lower-energy regions of the spectra and the overall forms of the spectra with high accuracy, but agreement is not as good in the Soret region below 450 nm.

Combining the diaza-Diels-Alder reaction and palladium-catalyzed aminations to prepare amino-substituted porphyrins

A strategy to tackle the synthesis of azoporphyrins with unsubstituted terminal meso positions was investigated. It comprised the combination of diaza-Diels–Alder (DADA) reaction of 1,3-dienes with dialkyl azodicarboxylates, decarboxylative hydrolysis of the bis(carbamates), palladium-catalyzed amination of bromoporphyrin precursors, and retro-DADA reactions to release the ultimate targets. The somewhat confused historical results on the DADA reactions of 1,3-cyclohexadiene were clarified, but the hydrolyses yielded extremely air-sensitive amines which decomposed completely in minutes via autooxidation and retro-DADA reaction. With anthracene or 2,3-dimethyl-1,3-butadiene as the diene, the synthesis of azoporphyrin was not achieved but three amino-substituted porphyrins were obtained in moderate yields under mild conditions. The X-ray crystal structures of several of the intermediates and the final aminoanthracene-porphyrin nickel(II) complex were determined.

Thermal properties of single-phase Y2SiO5

Y2SiO5 is a promising candidate for oxidation-resistant or environmental/thermal barrier coatings (ETBC) due to its excellent high-temperature stability, low elastic modulus and low oxygen permeability. In this paper, we investigated the thermal properties of Y2SiO5 comprehensively, including thermal expansion, thermal diffusivity, heat capacity and thermal conductivity. It is interesting that Y2SiO5 has a very low thermal conductivity (∼1.40 W/m K) but a relatively high linear thermal expansion coefficient ((8.36 ± 0.5) × 10-6 K-1), suggesting compatible thermal and mechanical properties to some non-oxide ceramics and nickel superalloys as ETBC layer. Y2SiO5 is also an ideal EBC on YSZ TBC layer due to their close thermal expansion coefficients. As a continuous source of Y3+, it is predicted that Y2SiO5 EBC may prolong the lifetime of zirconia-based TBC by stopping the degradation aroused by the loss of Y stabilizer.

The effects of humidity on tin whisker growth by immersion tin plating and tin solder dipping surface finishes

The drive to replace lead (Pb) from electronics has led to the replacement of tin (Sn) alloys as the terminal plating for electronic devices. However, the deposition of Sn based alloys as the component surface finish tends to induce Sn whisker that causes unintended electric shorts when the conductive whiskers grow across to the adjacent conductor. Internal stress is considered as the driving force that causes the growth of Sn whiskers. In this study, stress type of elevated temperature/ humidity exposure at 55C/85%RH with the storage for up to 24 months was conducted to define the acceleration factor in samples with deposition of immersion Sn plating and Sn solder dipping. The addition of Nickel (Ni) under-layer was also applied to examine the correlation to field conditions. The results showed that the whisker length increased in high humidity irrespective of the deposition methods. It was also shown that pure Sn solder dipping mitigated the whisker growth but does not completely prevent it when alloying Sn with 0.4%wtCu. Additionally, Ni under-layer was indicated to be more efficient in mitigating the growth of whisker by prolonging the incubation time for whisker formation.