Single-component conductors based on closed-shell Ni and Pt bis(dithiolene) complexes: metallization under high pressure

Abstract

Neutral, closed-shell nickel and platinum bis(dithiolene) complexes are explored as single-component conductors. Four complexes formulated as [Ni(R-thiazdt)2]0 and [Pt(R-thiazdt)2]0 (R-thiazdt: 2-alkyl-1,3-thiazoline-2-thione-4,5-dithiolate; R = Me, Et) were obtained by electrocrystallization from...

Conducting chiral nickel(ii) bis(dithiolene) complexes: structural and electron transport modulation with the charge and the number of stereogenic centres

“…16 The critical role of the pressure has been evidenced as well in the case of neutral [Ni(dithiolene)2] complexes without TTF units on the ligand backbone, in particular in the case of [Ni(dmit)2] (dmit = 1,3-dithiole-2-thione-4,5-dithiolate) which became metallic above 15.9 GPa, 17 or triclinic [Ni(Et-thiazdt)2] (Et-thiazdt = N-ethyl-1,3-thiazoline-2-thione-4,5-dithiolate) which reached a quasi-metallic state at 6.9 GPa. 18 However, other neutral [Ni(dithiolene)2] complexes, such as [Ni(dddt)2] (dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate) 19 (Scheme 1) or monoclinic [Ni(Etthiazdt)2], 20 remained semiconducting under pressure although their conductivity dramatically increased. The case of the former is particularly intriguing since, although it is isostructural with its [Pd(dddt)2] analogue which shows characteristics of Dirac-cone material at high pressure, such as temperature-independent resistivity at 12.6 GPa and emergence of a nodal line semimetal in the band structure under pressure, 21 , 22 , 23 it remains semiconductor up to the highest applied pressure.…”

The quest for single component molecular metals within neutral transition metal complexes

“…79 The analogue [Ni(Methiazdt) 2 ] presented semiconducting behaviour with a s RT of 0.05 S cm À1 , higher than the observed in the other Ni complexes of this family. 75 Under pressure the s RT was enhanced to 166 S cm À1 at 19 GPa, however its semiconducting behaviour remains. 75 In both [Pt(R-thiazdt) 2 ] (R: Me and Et) 75 a semiconducting behaviour was observed.…”

“…75 Under pressure the s RT was enhanced to 166 S cm À1 at 19 GPa, however its semiconducting behaviour remains. 75 In both [Pt(R-thiazdt) 2 ] (R: Me and Et) 75 a semiconducting behaviour was observed. At 12 GPa, the ethyl analogue still behaves as a semiconductor.…”

“…74 Afterwards, a new [Ni(Et-thiazdt) 2 ] phase was found and although it revealed again a semiconducting behaviour with a low s RT of 4.3 Â 10 À4 S cm À1 it also became metallic for a large range of temperatures when under a pressure of 6.9 GPa. 75 A series of [Au(R-thiazdt) 2 ] were also prepared with different substituents, such as R: EtOH, 76 i Pr, 77 c Pr, 78 n Pr, 78 NMe 2 78 and Me. 79 [Au(EtOH-thiazdt) 2 ] revealed a semiconducting behaviour with a s RT of 0.05-0.07 S cm À1 .…”

Introducing Selenium in Single-Component Molecular Conductors Based on Nickel Bis(dithiolene) Complexes

“…On the basis of this preliminary attractive result, we recently considered nickel dithiolene complexes derived from the thiazolinedithiolate ligand R-thiazdt. Indeed, such complexes with gold, that is, [Au­(R-thiazdt) 2 ] • (Chart b), proved to be excellent single-component molecular conductors (following the first approach detailed above). − Accordingly, the ethyl-substituted nickel complex, [Ni­(Et-thiazdt) 2 ] 0 , was found to organize into uniform chains and, albeit a semiconductor at ambient pressure (σ RT = 4.3 × 10 –4 S cm –1 ), to become metallic at low temperature at 4.4 GPa and metallic over the whole temperature range over 6.9 GPa . In order to explore further this family and its behavior under pressure, we considered the possibility of substituting sulfur atoms for selenium ones because such substitutions are well-known to increase the band dispersion in molecular conducting systems .…”