A Molecular Boroauride: A Donor–Acceptor Complex of Anionic Gold

Taylor, Jordan W.; McSkimming, Alex; Moret, Marc‐Etienne; Harman, W. Dean

doi:10.1002/ange.201703235

Cited by 12 publications

(10 citation statements)

References 35 publications

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“…The 12-electron auride anion is typically generated by the reduction of metallic gold with alkali metals, to give salts such as CsAu and RbAu 11,12 ; the solution chemistry of these salts, however, is restricted to liquid ammonia 13,14 .Reduction of organometallic gold compounds to give systems in low oxidation states (i.e. zero or below) has been attempted, but with limited success [15][16][17][18][19][20] . Thermodynamics typically drive the aggregation of molecular Au(0) systems to clusters of colloidal gold [15][16][17][18] .…”

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confidence: 99%

A nucleophilic gold complex

et al. 2019

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Solid-state auride salts featuring the negatively charged Auion are known to be stable in the presence of alkali metal counter-ions. While such electron-rich species might be expected to be nucleophilic (cf. I -), their instability in solution means that this has not been verified experimentally. Here we report the two-coordinate gold complex (NON)AlAuP t Bu3 (3, NON = 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene) synthesised by the reaction of the potassium aluminyl complex [K{Al(NON)}]2 (1) with t Bu3PAuI, and which features a strongly polarized bond, Au(d-)-Al(d+). 3 has been studied computationally, with QTAIM charge analysis implying a charge at gold (-0.82) which is in line with the relative electronegativities of the two metals (Au: 2.54; Al: 1.61 on the Pauling scale). Consistently, 3 is found to act as an unprecedented nucleophilic source of gold, reacting with diisopropylcarbodiimide and CO2 to give the Au-C bonded insertion products (NON)Al(X2C)AuP t Bu3 (X = N i Pr, 4; X = O, 5).Transition elements are known to be able to access multiple oxidation states 1 , a property which underpins widespread application in fields such as small molecule activation and catalysis 2,3 . The vast majority of transition metal complexes however, feature cationic metals in positive oxidation states, ligated by neutral or anionic donors 1,4 . Systems featuring formal negative oxidation states, such as the tetracarbonylferrate 5 or bis(benzene)vanadium 6 anions are much less common, and usually require strong p-acceptor ligands, most frequently CO 7 . In this regard, gold is unique, being the only transition metal to give rise to a stable "naked" monoanion (Au -, auride) in the condensed phase 8 . In part, this is due to relativistic effects which contract the 6s orbital significantly, resulting in an electron affinity of 2.30 eV, the highest of any transition metal 9,10 .This value is more comparable to those of the chalcogens (e.g. S: 2.08 eV; Se: 2.02 eV) than to the lighter group 11 congeners (Cu: 1.23 eV; Ag 1.30 eV) 10 . The 12-electron auride anion is typically generated by the reduction of metallic gold with alkali metals, to give salts such as CsAu and RbAu 11,12 ; the solution chemistry of these salts, however, is restricted to liquid ammonia 13,14 .Reduction of organometallic gold compounds to give systems in low oxidation states (i.e. zero or below) has been attempted, but with limited success [15][16][17][18][19][20] . Thermodynamics typically drive the aggregation of molecular Au(0) systems to clusters of colloidal gold [15][16][17][18] . Recently however, electron-rich gold complexes have been reported by Bertrand and co-workers, by making use of strongly p-accepting cyclic(alkyl)(amino)carbenes (CAAC) ligands (I and II, Figure 1) 19 . In addition, a four-coordinate molecular 'boroauride' was reported by Harman and co-workers last year in which the gold centre is stabilized by a diboraanthracene-based scaffold (III, Figure 1) 20 .Notwithstanding these examples, and even though Auions...

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A nucleophilic gold complex

et al. 2019

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“…The chemistry of gold compounds bonded to main group elements has been developed extensively. 7,[18][19][20][21] Very recently, a nucleophilic gold complex I released by Goicoechea, Aldridge and colleagues (Chart 1), was employed rstly in the activation of CO 2 and carbodiimide unfolding an unprecedented nucleophilicity of auride complex. 20 The umpolung reactivity of gold was ascribed to its high polarization of Au-Al bond.…”

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confidence: 99%

Unique Digoldgermanes: Structural Characteristics, Dynamic Behaviour and Distinctive Reactions

Wang

Zhen

et al. 2021

Preprint

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Digoldgermanes with a gold coordinated by a dialkylgermylene ligand, R’2Ge(AuPR3)(AuGeR’2) (3a; R = Me, 3b; R = Et), were synthesized as green solids through the reactions of stable dialkylgermylene 1 with R3PAuCl followed by the reduction with KC8 at ambient temperatures. The structural characteristics of 3a and 3b were elucidated using NMR spectroscopy, X-ray crystallography, and DFT calculations. An intense absorption maximum was observed at 590 nm in the UV-vis spectrum of 3a in hexane. A pendular motion of AuPR3 group between Ge(IV) and Ge(II) of 3a and 3b occurring in the NMR time scale was found by the dynamic 1H NMR analysis, suggesting that the Ge(II) ligand has an enhanced electrophilicity to be attacked by the nucleophilic gold atom which closes to ‒1 oxidation state. DFT calculations of 3a revealed the existence of high-lying σ(Ge-Au) type HOMO and low-lying LUMO with germylene pπ nature. We show the bond formation and activation alternatively at Au or Ge atom, a methylation of digoldgermane 3a with MeOTf affords methylgermane 5. Moreover, the digoldgermane 3a reacts with Cl− ion of Ph4PCl and CH3C(O)Cl smoothly to form the corresponding chloride-addition product 7 and chlorogoldgermane 9, respectively. Cyclic trimerization reactions of aromatic isocyanates were high-efficiently catalyzed by 3a giving the corresponding 1,3,5-triaryl isocyanurates.

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“…The chemistry of gold compounds bonded to main-group elements has been developed extensively in recent years 3 – 7 . Goicoechea, Aldridge and coworkers have reported that novel gold-aluminum complex I (Fig.…”

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confidence: 99%

Structure and reactivity of germylene-bridged digold complexes

Wang

Zhen

et al. 2022

Nat Commun

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The bonding between gold and main-group metallic elements (M) featuring Auδ−−Mδ+ polarity, has been studied recently. The gold in the bonds is expected to have the oxidation number of −1, and hence, nucleophilic. However, the knowledge of the reactivity of the gold-metal bonds remains limited. Here, we report digold-substituted germanes of the form of R’2Ge(AuPR3)(AuGeR’2) (3a; R = Me, 3b; R = Et), featuring two Au-Ge(IV) and one Au-Ge(II) bonds. DFT calculations of 3a revealed the existence of high-lying σ(Ge-Au) type HOMO and low-lying LUMO with germylene pπ nature. A pendular motion of AuPR3 group between Ge(IV) and Ge(II) of 3 occurs in the NMR time scale, suggesting that the Ge(II) center has an enhanced electrophilicity to be attacked by the nucleophilic gold (−I) atom. 3a reacts with nucleophilic Cl− and electrophilic MeOTf reagents at Ge(II) and Ge(IV) centers, respectively.

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A Molecular Boroauride: A Donor–Acceptor Complex of Anionic Gold

Cited by 12 publications

References 35 publications

A nucleophilic gold complex

A nucleophilic gold complex

Unique Digoldgermanes: Structural Characteristics, Dynamic Behaviour and Distinctive Reactions

Structure and reactivity of germylene-bridged digold complexes

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