Conformational behavior, redox and spectroscopic properties of gold dithiolene complexes: [Au(iPr-thiazYdt)2]−1 (Y = O, S, Se)

Abstract

Three monanionic gold dithiolene complexes with different exocyclic chalcogen atoms (O, S, Se) on the N-isopropyl-1,3-thiazoline-2-chalcogenone-4,5-dithiolate ligand, have been synthetized with the aim of modulating their properties. Due to the presence of the isopropyl (iPr) group in the plane of the thiazoline-2-chalcogenone ring, different syn and anti rotamers can exist, in solution and in the solid state. Characterization of these complexes by spectroscopic and electrochemical methods was carried out in order to investigate the influence of the size, electronegativity and polarizability of the exocyclic chalcogen atom.The molecular structure of the three anionic complexes [Au(iPr-thiazYdt) 2 ] -1 , with Y = O, S, Se, were established by single crystal X-ray diffraction studies. Theoretical calculations carried out at the DFT levels were realized on the three possible rotamers, syn/syn, syn/anti and anti/anti of the trans-[Au(iPr-thiazYdt) 2 ] -1 complexes.

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

“…The protected dithiolene form of the selenone 3 was prepared from the N-ethyl-thiazoline-2-thione 1, according to a modified procedure described earlier for the N-isopropyl analogue. 22 Reaction of 1 with MeI and NaHSe provides the N-Et-1,3-thiazoline-2-selenone 2, which is easily converted into the protected dithiolene 3 after the subsequent addition of LDA, sulfur and bromopropionitrile. Deprotection with NaOMe generates the air-sensitive dithiolate which reacts with NiCl2•6H2O and NBu4Br to afford, after air oxidation, the monoanionic dithiolene complex [Ni(Et-thiazSedt)2] −1 , isolated as the Bu4N + salt in 31% yield.…”

“…The strategy used to form the anionic complexes is similar to that used to synthesize the analogous gold complexes (Scheme ). The protected dithiolene form of the selenone, 3 , was prepared from N -ethylthiazoline-2-thione ( 1 ), according to a modified procedure described earlier for the N -isopropyl analogue . Reaction of 1 with MeI and NaHSe provides N -ethyl-1,3-thiazoline-2-selenone ( 2 ), which is easily converted into the protected dithiolene 3 after the subsequent addition of lithium diisopropylamide (LDA), sulfur, and bromopropionitrile.…”

Broad Spectrum Functional Activity of Structurally Related Monoanionic Au(III) Bis(Dithiolene) Complexes

“…On the other hand, the presence of electron-withdrawing substituents such as =C(CN) 2 induces an anodic shift of the oxidation potentials by 300 mV, compared with the =O derivative, leading to a monoanion which is more difficult to oxidize than the other complexes of the series. Both derivatives, [AuSEt(=C(CN) 2 )] −1 and [AuSEt(=O)] −1 exhibited a wider potential stability window of the neutral species than the sulfur analogues [AuSR(=S)] −1 [51]. Indeed, the potential difference between the second and the first oxidation potentials amounts to 470 mV and 410 mV for the =O and the =C(CN) 2 derivatives, respectively, while for the =S analogues this value is smaller (170 mV).…”

A highly conducting mixed-valence nickel bis(dithiolene) salt [Et4N][Ni(Me-thiazSe-dt)2]2 with selone substitution

“…[15][16][17] Only two such [M(R-thiazSe-dt) 2 ] complexes have been reported earlier. The N-isopropyl gold complex 24 [Au(iPr-thiazSe-dt) 2 ] 1− was prepared for comparison with the analogous thione derivative 25 [Au(iPr-thiazdt) 2 ] 1−,• , but its electrochemical oxidation failed to provide any crystalline material, neutral or mixed-valence. The N-ethyl nickel complex 26 [Ni(Et-thiazSe-dt) 2 ] 1− was reported to oxidize to the neutral closedshell complex [M(R-thiazSe-dt) 2 ] 0 , a single component semiconductor with very low conductivity (σ RT = 1.7 × 10 −5 S cm −1 ), a consequence of its closed-shell character.…”