RESUMO

The role of platinum basis set (PTBS) and relativistic effects for predicting the vibrational frequencies and intramolecular force constants for cisplatin are discussed. Nonrelativistic and relativistic computational protocols were built at B3LYP/PTBS/jorge-DZP/C-PCM and B3LYP-DKH2/PTBS/jorge-DZP-DKH/C-PCM levels, respectively, where 19 distinct PTBS were tested. As expected, the structural parameters were not very sensitive to the PTBS, however, the inclusion of relativistic effects improves the description of the cisplatin structure. When it comes to the vibrational frequencies, the results show that the PTBS, and mainly the relativistic effects, are both important. Moreover, the PBE0 functional led to better results than B3LYP in the protocols PBE0/LANL2TZ(f)/jorge-DZP/C-PCM (P20) and PBE0-DKH2/Sapporo-DKH3-DZP-2012/jorge-DZP-DKH/C-PCM (P22), which provided a mean absolute deviation (MAD) of only 10.8 cm-1 and 9.5 cm-1, respectively, for vibrational frequencies, which are excellent choices to study Pt complexes. Finally, a discussion of the intramolecular force constants for cisplatin is carried out, with the calculated bond and angles force constants with P20 and P22 protocols being recommended for the parameterization of the force field of cisplatin.

Assuntos

Cisplatino/química , Estrutura Molecular , Platina/química , Vibração , Cisplatino/uso terapêutico , Química Computacional , Fenômenos Mecânicos , Platina/uso terapêutico , Teoria Quântica , Espectrofotometria Infravermelho

RESUMO

The production of electronic waste due to technological development, economic growth and increasing population has been rising fast, pushing for solutions before the environmental pressure achieves unprecedented levels. Recently, it was observed that many extractive metallurgy alternatives had been considered to recover value from this type of waste. Regarding pyrometallurgy, little is known about the low-temperature processing applied before fragmentation and subsequent component separation. Therefore, the present manuscript studies such alternative based on scanning electron microscopy characterization. The sample used in the study was supplied by a local recycling center in Rio de Janeiro, Brazil. The mass loss was constant at around 30% for temperatures higher than 300 °C. Based on this fact, the waste material was then submitted to low-temperature processing at 350 °C followed by attrition disassembling, size classification, and magnetic concentration steps. In the end, this first report of the project shows that 15% of the sample was recovered with metallic components with high economic value, such as Cu, Ni, and Au, indicating that such methods could be an interesting alternative to be explored in the future for the development of alternative electronic waste extraction routes.