Anisotropic Chemical Pressure Effects in Single-Component Molecular Metals Based on Radical Dithiolene and Diselenolene Gold Complexes
摘要:
On the basis of the reported radical neutral complex [Au(Et-thiazdt)(2)] (Et-thiazdt = N-ethyl-1,3-thiazoline-2-thione-4,5-dithiolate), a series of single-component conductors derived from [Au(Et-thiazdt)(2)], also noted as [AuS4(=S)(2)], has been developed, by replacing the outer sulfur atoms of the thiazoline-2-thione rings by oxygen atoms and/or by replacing the coordinating sulfur atoms by selenium atoms toward the corresponding diselenolene complexes. Comparison of the X-ray crystal structures and transport properties of the four isostructural complexes, noted as [AuS4(=S)(2)], [AuS4(=O)(2)], [AuSe4(=S)(2)], and [AuSe4(=O)(2)], shows that the oxygen substitution on the outer thiazoline ring actually decreases the conductivity by a factor of 100, despite a contracted unit cell volume reflecting a positive chemical pressure effect. On the other hand, the S/Se substitution increases the conductivity by a factor of 100, and the pressure needed to transform these semiconductors into the metallic state is shifted from 13 kbar in [AuS4(=S)(2)] to only approximate to 6 kbar in [AuSe4(=S)(2)] Analysis of unit cell evolutions and ab initio band structure calculations demonstrates the strongly anisotropic nature of this chemical pressure effect and provides an explanation for the observed changes in conductivity. The greater sensitivity of these neutral single-component conductors to external pressure, as compared with "classical" radical salts, is also highlighted.
Anisotropic Chemical Pressure Effects in Single-Component Molecular Metals Based on Radical Dithiolene and Diselenolene Gold Complexes
摘要:
On the basis of the reported radical neutral complex [Au(Et-thiazdt)(2)] (Et-thiazdt = N-ethyl-1,3-thiazoline-2-thione-4,5-dithiolate), a series of single-component conductors derived from [Au(Et-thiazdt)(2)], also noted as [AuS4(=S)(2)], has been developed, by replacing the outer sulfur atoms of the thiazoline-2-thione rings by oxygen atoms and/or by replacing the coordinating sulfur atoms by selenium atoms toward the corresponding diselenolene complexes. Comparison of the X-ray crystal structures and transport properties of the four isostructural complexes, noted as [AuS4(=S)(2)], [AuS4(=O)(2)], [AuSe4(=S)(2)], and [AuSe4(=O)(2)], shows that the oxygen substitution on the outer thiazoline ring actually decreases the conductivity by a factor of 100, despite a contracted unit cell volume reflecting a positive chemical pressure effect. On the other hand, the S/Se substitution increases the conductivity by a factor of 100, and the pressure needed to transform these semiconductors into the metallic state is shifted from 13 kbar in [AuS4(=S)(2)] to only approximate to 6 kbar in [AuSe4(=S)(2)] Analysis of unit cell evolutions and ab initio band structure calculations demonstrates the strongly anisotropic nature of this chemical pressure effect and provides an explanation for the observed changes in conductivity. The greater sensitivity of these neutral single-component conductors to external pressure, as compared with "classical" radical salts, is also highlighted.
Efficient routes towards a series of 5,5′-bithiazolidinylidenes as π-electron acceptors
作者:Y. Le Gal、D. Ameline、N. Bellec、A. Vacher、T. Roisnel、V. Dorcet、O. Jeannin、D. Lorcy
DOI:10.1039/c5ob01169h
日期:——
Among different approaches, the thermal treatment of the fused bicycle involving a dithiole-2-one ring is the most efficient one and opens access to a variety of π-conjugated electron acceptors.