Back-bonding driven negative thermal expansion along the one dimensional Hg C N linkage in [HgCN](NO3) probed by Raman spectroscopy
| Autor: | Aashna Jain, Pallavi Ghalsasi, Prasanna S. Ghalsasi |
|---|---|
| Rok vydání: | 2021 |
| Předmět: |
010405 organic chemistry
Chemistry 010402 general chemistry 01 natural sciences 0104 chemical sciences Ion Inorganic Chemistry Metal Crystallography symbols.namesake Electron transfer Negative thermal expansion visual_art Materials Chemistry symbols visual_art.visual_art_medium Physical and Theoretical Chemistry Anisotropy Raman spectroscopy Single crystal Pi backbonding |
| Zdroj: | Polyhedron. 205:115293 |
| ISSN: | 0277-5387 |
| DOI: | 10.1016/j.poly.2021.115293 |
| Popis: | In this paper, the mechanistic aspect for anisotropic negative thermal expansion (NTE) in [Hg(CN)](NO3) is correlated to back-bonding along a one dimensional Hg C N network using temperature dependent Raman spectroscopy. Signatures of back-bonding are contraction of the Hg C bond (~299 cm−1), expansion of the C N bond (~2249 cm−1) and bending of the Hg C N bond. These are clearly observed in the Raman spectra, correlating to a continuous increase in the Hg C N bending frequency (~346 cm−1) with an increase in temperature. This bending of the Hg C N bond may be responsible for an expansion of the Hg lattice along the ab-plane and a reorientation of the NO3− ions, as seen by the change in frequency variation of the 1637 cm−1 mode and the reduction of its intensity with the increase in temperature. All these effects are in agreement with the reported single crystal X-ray data. Thus, the present model of back-bonding electron transfer from the metal d-orbital to the π*-orbital of the cyanide ligand and the effect of temperature changes on it can be explored to understand the NTE behaviour in metal cyanide systems and more broadly in multifunctional materials. |
| Databáze: | OpenAIRE |
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