Surface thiolates play important roles in evincing the structures and properties of thiolated metal nanoclusters—one type of recently emerging inorganic-organic hybrids,and thus the thiolate substitution,especially single thiolate substitution,is highly desirable for subtly tailoring the structures and properties of metal nanoclusters.However,such a single-thiolate substituting is challenging,and its influence on the metal-metal and metal-sulfur bonds remains mysterious due to the absence of the singlethiolate-substituted structure.Here,we developed a combined method,concurrently synthesized the single-thiolate-substituted nanocluster and its parent nanocluster,and successfully resolved their structures by single crystal X-ray crystallography,which reveals that the single thiolate substitute has an obvious influence on the metal-metal and metal-sulfur bond lengths although it has no effect on the absorption profile.Interestingly,the metal-metal and metal-sulfur bonds show various thermal extensibility and even the negative thermal expansion phenomena of the Au–S bond were observed in the single-thiolate-substituted nanocluster.The bond length-related stability was also observed.Overall,this study highlights a novel synthesis method and offers novel structural insights and an in-depth structure-property correlation of thiolated metal nanoclusters.
Thiolate(SR)-protected gold nanoclusters(Aun(SR)m NCs)are a rare type of material capable of simultaneously exhibiting multiple physicochemical properties well-suited to specific applications,including photoluminescence,thermocatalysis,electrocatalysis,photocatalysis,magnetism,and optical activity.Over the past several decades,there has been tremendous progress in our understanding of the structure and physicochemical properties of Aun(SR)m NCs,resulting in the ability to fine-tune the characteristics of these materials.It is therefore helpful to examine the extent to which the properties of Aun(SR)m and related metal NCs can now be adjusted based on design.This review presents representative examples of previous studies concerning the geometry,electronic structure,luminescence properties,catalysis,magnetism and optical activity of Aun(SR)m and related metal NCs and discusses the current status of the designability of these NCs to impart specific structural and physicochemical characteristics.This information is expected to accelerate the fabrication of highly functional materials based on Aun(SR)m and related metal NCs.
While self-assembled monolayers(SAMs)of aromatic thiolates are frequently used in a wide range of applications,their formation is often hampered by the low solubilities of their precursors.Here we introduce the 3,4-dimethoxybenzyl group as a protective group for the thiol moiety,which increases the solubility and stability of the precursor,but becomes cleaved off during monolayer formation,especially at elevated temperature(60°C)and in presence of protons(trifluoroacetic acid).For a series of substituted terphenylthiols as model systems,it could be demonstrated by using ellipsometry,infrared-reflection absorption spectroscopy,and scanning-tunneling microscopy that the resulting SAMs have the same structure and quality as the ones obtained from the respective unprotected thiols.The protective group has the additional advantage to be stable under Pdcatalyzed C–C bond formation reaction conditions,facilitating the syntheses of the respective precursors.
Adrian WiesnerSonja KatzbachDariusz BebejMartina DettenhöferMichael ZharnikovAndreas Terfort
Atomically precise gold and/or silver nanoclusters play a key role in crystallography and coordination chemistry.Compared with gold nanoclusters,silver nanoclusters become unstable and difficult to crystallize due to the high reactivity ofmetal silver.Herein,we report a silver nanocluster Ag_(213)(Adm-S)_(44)Cl_(33)(Ag_(213))coprotected by bulky thiolates and chlorides.The low surface thiolate coverage(about 45%)endows Ag_(213)with high catalytic activity.Supported on activated carbon,Ag_(213)nanoclusters exhibit excellent electrocatalytic oxygen reduction performance with Eonset and E_(1/2)values of 0.89 and 0.72 V,respectively,close to the values of commercial Pt/C catalyst.This is the first report on the electrocatalytic oxygen reduction reaction of nanoclusters with more than 100 silver atoms.Ag_(213)with the diameter of 2.75 nm comprises a core–shell structure Ag_(7)@Ag_(32)@Ag_(77)@Ag_(97).The strong plasmonic absorption band at 454 nm reveals the metallic nature of Ag_(213).Interestingly,halide is of importance.Chloride facilitates the formation of Ag_(213)and Ag_(56)(Adm-S)_(33)Cl_(16)(Ag_(56)^(Cl))while bromide can promote the formation of Ag_(56)(Adm-S)_(33)Br_(16)(Ag_(56)Br).This work provides an example for the study of largesized metal nanoclusters and nanocluster-based electrocatalysts.
Colloidal synthesis of metal nanoclusters will inevitably lead to the blockage of catalytically active sites by organic ligands.Here,taking[Au_(25)(PET)_(18)]-(PET=2-phenylethanethiol)nanocluster as a model catalyst,this work reports a feasible procedure to achieve the controllably partial removal of thiolate ligands from unsupported[Au_(25)(PET)_(18)]-nanoclusters with the preservation of the core structure.This procedure shortens the processing duration by rapid heating and cooling on the basis of traditional annealing treatment,avoiding the reconfiguration or agglomeration of Au_(25)nanoclusters,where the degree of dethiolation can be regulated by the control of duration.This work finds that a moderate degree of dethiolation can expose the Au active sites while maintaining the suppression of the competing hydrogen evolution reaction.Consequently,the activity and selectivity towards CO formation in electrochemical CO_(2)reduction reaction of Au_(25)nanoclusters can be promoted.This work provides a new approach for the removal of thiolate ligands from atomically precise gold nanoclusters.
Liting HuangYongfeng LunYuping LiuLiming ChenBowen LiShuqin SongYi Wang
By using a unique temperature-dependent,chloride-mediated approach,two atom-precise silver nanoclusters[Cl@Ag_(14)(Tab)_(12)-(C_(5)H_(4)NCl)_(12)](PF_(6))_(13)(Cl@Ag_(14))and[Cl_(3)@Ag_(24)(Tab)_(20)(C_(5)H_(4)NCl)_(11)]Cl(PF_(6))_(20)(Cl_(3)@Ag_(24))(Tab=4-(trimethylammonio)benzenethiolate,C_(5)H_(4)NCl=3-chloropyridine)were obtained successfully.Notably,the number of chloride ions encapsulated inside the Ag-S shell could be regulated by the slow dissolution of almost insoluble KCl at various temperatures.The inclusion of additional core chloride ions results in the expansion of the surrounding Ag-S shell.This article provides a promising synthetic approach for controlling the number of Ag atoms that form a shell around the anionic core,in addition to offering a potential pathway for the introduction of other inorganic anions into silver clusters.More broadly,through the use of related ligands,the synthetic strategy offers scope for generating new families of silver thiolate clusters of varying size and composition.
Ling YangXin-Yao WangXiao-Yan TangMeng-Yi WangChun-Yan NiHong YuYing-Lin SongBrendan F.AbrahamsJian-Ping Lang
Low-valence transition metallic complexes have drawn longstanding attention due to their high reactivity toward catalytic transformation of various small molecules.Among these known complexes,the low-valence metal centres are commonly stabilized by neutral bulky ligands with strong electron-donating capacity.However,low-valence bimetallic complexes supported by anionic sulfur and cyclopentadienyl ligands are still difficult to obtain in high isolated yield.Herein,we report the synthesis and characteri-zation of two scarce thiolate-bridged Co^(I)Co^(II)and Co^(I)Co^(I)complexes bearing sterically demanding ligands through two stepwise one-electron reduction processes.Interestingly,the Co^(I)Co^(II)complex can facilely promote the homolytic cleavage of dihydrogen across the short Co−Co metallic bond to give a Co^(II)Co III dihydride bridged complex,which is capable of serving as a competent hydrogen atom transfer agent.Moreover,the anionic Co^(I)Co^(I)complex can trigger a stepwise hydrogen generation cycle involving several isolated and structurally well-characterized intermediates.
Thiolate-bridged hetero-bimetallic complexes[Cp^(*)M(MeCN)N_(2)S_(2)FeCl][PF_(6)](2,M=Ru;3,M=Co,Cp^(*)=η^(5)-C_(5)Me_(5),N_(2)S_(2)=N,N'-dimethyl-3,6-diazanonane-1,8-dithiolate)were prepared by self-assembly of dimer[N_(2)S_(2)Fe]2 with mononuclear precursor[Cp^(*)Ru(MeCN)_(3)][PF_(6)]or[Cp^(*)Co(MeCN)_(3)][PF_(6)]_(2)in the presence of CHCl_(3)as a chloride donor.Complexes 2 and 3 exhibit obviously different redox behaviors investigated by cyclic voltammetry and spin density distributions supported by DFT calculations.Notably,iron-cobalt complex 3 possesses versatile reactivities that cannot be achieved for complex 2.In the presence of CoCp_(2),complex 3 can undergo one-electron reduction to generate a stable formally Co^(II)Fe^(II)complex[Cp^(*)CoN_(2)S_(2)FeCl](4).Besides,the terminal chloride on the iron center in 3 can be removed by dehalogenation agent AgPF_(6)or exchanged with azide to afford the corresponding complexes[Cp^(*)Co(MeCN)N_(2)S_(2)Fe(MeCN)][PF_(6)]_(2)(5)and[Cp^(*)Co(MeCN)N_(2)S_(2)Fe(N_(3))][PF_(6)](6).In addition,complexes 2,3 and 4 show distinct catalytic reactivity toward the disproportionation of hydrazine into ammonia.These results may be helpful to understand the vital role of the heterometal in some catalytic transformations promoted by heteromultinuclear complexes.
