(n‐Bu₄N)₂[Au(mnt)₂]: Synthese, Struktur‐ und EPR‐Untersuchungen eines stabilen, mononuklearen Au^II‐Komplexes

Abstract

Die Reaktion von [AuIII(mnt)2]− mit (n‐Bu4N)[BH4] in Aceton führt zur Bildung des bisher zweiten stabilen mononuklearen AuII‐Komplexes [AuII(mnt)2]2− dessen Struktur erstmals aufgeklärt werden konnte. (n‐Bu4N)2[AuII(mnt)2] kristallisiert triklin, P$\bar 1$ (a = 904,24(5), b = 989,55(5), c = 1627,35(10) pm, α = 92,040(7), β = 94,937(7), γ = 107,220(6)°, Z = 1) mit zwei Acetonmolekülen pro Elementarzelle. Das Anion ist planar. EPR‐Untersuchungen an Einkristallen von (n‐Bu4N)2[AuII(mnt)2] gestatten Aussagen zur Anisotropie des g‐Tensors und über die Linienbreitenanalyse Aussagen zu magnetischen Austauschwechselwirkungen.

Gold(III) Complexes of Asymmetrically Aryl‐Substituted 1,2‐Dithiolene Ligands Featuring Potential‐Controlled Spectroscopic Properties: An Insight into the Electronic Properties of bis(Pyren‐1‐yl‐ethylene‐1,2‐dithiolato)Gold(III)

“…[c] Taken from Ref. 34 for L=mnt 2− . [d] Mean values of the optimized parameters calculated for the cis and trans isomers (Table 1).…”

“…These data support the hypothesis that oxidation of the monoanions should be ligand centered [Equation (1)], without affecting the formal oxidation state of the central metal ion. On the contrary, an examination of the metric parameters determined for the dithiolene core in (TBA + ) 2 {[Au(mnt) 2 ] 2− },34 the only authentic dianionic bis(1,2‐dithiolene) gold complex reported to date, suggests that reduction of monoanionic to dianionic forms of gold 1,2‐dithiolenes should not be considered simply as metal centered [Equation (1)], but should significantly involve the ligands as well. The trends observed in the experimental distances are in perfect agreement with those calculated for 1 x − in the same valence states.…”

Gold(ii) in redox-switchable gold(i) catalysis

“…39,50,51 On the other hand, gold(II) species have been reported to possess g tensors with small g anisotropy and hyperfine coupling to the gold nucleus ( 197 Au: I = 3 /2). [15][16][17][18] Due to the non-resolved coupling(s), only the giso value of 2.017 is given which fits to reported values for gold(II) complexes. [15][16][17][18] Furthermore, the resonance increases in intensity over time at room temperature converging to a limiting value after 5 h. Quantification of the EPR resonance after 5 h by double integration and calibration (ESI, Fig.…”

“…[15][16][17][18] Due to the non-resolved coupling(s), only the giso value of 2.017 is given which fits to reported values for gold(II) complexes. [15][16][17][18] Furthermore, the resonance increases in intensity over time at room temperature converging to a limiting value after 5 h. Quantification of the EPR resonance after 5 h by double integration and calibration (ESI, Fig. S17, S18) confirms that the EPR resonance accounts for 755 % of the paramagnetic species (Fig.…”

“…[8][9][10][11][12][13][14] Apart from very few examples, the chemistry of mononuclear gold(II) complexes is underdeveloped due to the favoured disproportionation or dimerisation of gold(II). [15][16][17][18][19] In gold(I) catalysed reactions, gold(I) halide complexes are usually employed as precatalysts. Typically, silver(I) salts, copper(II) triflate 20 or alkali metal salts 21 activate the precatalyst by halide abstraction.…”