Search

Copper hydrides are very useful in hydrogenation reactions. We report a stable Stryker-type copper hydride reagent protected by hemilabile phosphines: [Cu8H6(dppy)6](OTf)2 (Cu8-H, dppy = diphenylphosphino-2-pyridine). The metal core of this cluster has a bicapped octahedral configuration, and the copper-bound hydrides each triply bridges over a triangular face of the octahedron. This cluster is attractive due to its facile preparation and excellent stability under ambient conditions. The comparable activity and selectivity both in the stoichiometric and catalytic reactions make Cu8-H a promising alternative to Stryker's reagent. [ABSTRACT FROM AUTHOR]

The identification of hydride(s) in gold nanoclusters is a challenging task, due to the instability of gold nanoclusters containing hydrides. Herein, we report two ultrastable hydrido gold nanoclusters protected by phosphine ligands: [Au20(PPh3)12H3](SbF6)3 (1H) and [Au20(PPh3)12H2(2-COOH-PhS)](PF6)3 (2H). The presence of hydrides in gold(0)–gold(I) nanoclusters is clearly demonstrated by ESI mass spectrometry and NMR spectroscopy. Single crystal structural determination reveals that both nanoclusters have an unprecedented Au20 core consisting of a Au9 unit and a Au11 unit. Such cores derived from the connection of different basic units are important for understanding the evolution and stability of metal nanoclusters. The hydride (H−) was also verified by a charge distribution calculation. [ABSTRACT FROM AUTHOR]

We report the total structure determination of a covalently bonded nanocluster polymer [Au7Ag9(dppf)3(CF3CO2)7BF4]n (1). This features a one-dimensional linear chain, consisting of unique molecular building blocks, Au7Ag8(dppf)3(CF3CO2)7 clusters, which are linked together by Ag–O bonds rather than Au–Au interactions or bidentate organic bridges as previously reported. [ABSTRACT FROM AUTHOR]

We report a series of Ag–S nanoscale clusters in an attempt to understand the growth process of Ag2S clusters. UV-vis monitoring and crystallization at different stages of the reaction map out the cluster growth steps from Ag31S3(StBu)17(tfa)8(MeCN)4 (tfa = trifluoroacetate), to Ag45S7(StBu)24(tfa)7 to [Ag62S13(StBu)32(tfa)2](tfa)2, showing sequential eye-catching color changes. The cluster growth is associated with the in situ generation of S2−, which comes from the C–S bond cleavage of tert-butyl thiolate. [ABSTRACT FROM AUTHOR]

An alkynyl-protected gold nanocluster [Au40(PhC≡C)20(dppm)4](SbF6)4 (dppm = bis(diphenylphosphino)methane) (1) has been synthesized. Single-crystal X-ray diffraction reveals that the cluster has a face-centered cubic (FCC) Au34 kernel that is made up of two Au20 units via sharing a rectangular face. Two linear PhC≡C–Au–C≡CPh staple motifs are located around the central part of the Au34 core, and four L-shaped PhC≡C–Au–P^P staple motifs are located at the four corners of the Au34 core. Cluster 1 and [Au38(PhC≡C)20(PPh3)4](CF3SO3)2 both have the FCC Au34 core, and it is found that the diphosphine ligands bringing two more Au atoms into the system have significant effects on the optical properties and stability of the clusters. The combination of a diphosphine ligand and an alkynyl ligand is helpful in generating new ligand-protected metal nanoclusters. [ABSTRACT FROM AUTHOR]

Gold(i) phosphinopyridyl clusters [Au9(PNC)6](BF4)3 (1) and [Au11(PNC)6(PPh3)2](BF4)5 (2) (PNC = 2-diphenylphosphinopyridyl monoion) are assembled. In contrast to the green luminescence of 1, 2 is brightly orange emissive in CH2Cl2, which shows the presence of unsupported AuI–AuI interactions in solution. Besides, 1 and 2 can selectively light up the mitochondria of living cells. [ABSTRACT FROM AUTHOR]

Ligand-protected metal nanoclusters as unique nanomaterials have attracted great attention. The protecting ligands that directly bind on the cluster surfaces are crucial in dictating the structures and properties of the clusters. In contrast to the extensively studied thiolates, alkynyl ligands have been found recently to be important ligands for passivating gold/silver cluster surfaces. In this Frontier article, recent advances in alkynyl-protected metal nanoclusters are overviewed, and the structures, luminescence and catalytic activities are also discussed. It is demonstrated that alkynyls are very promising ligands in the control of the structures and properties of gold/silver nanoclusters. [ABSTRACT FROM AUTHOR]

A gold(i)–silver(i) cluster bearing six carboxylate groups has been synthesized through the oxidation of its aldehyde precursor and the Au6 core of this cluster displays an octahedral or a trigonal prismatic configuration depending on the crystallization conditions. The reversible interconversion between these two isomers can be triggered in the solid state by the addition or removal of acetonitrile solvent molecules. Interestingly, luminescence changes were observed as each configuration shows different emission colors, yellow for octahedral type and red for the trigonal prismatic one. [ABSTRACT FROM AUTHOR]

We report a unique intercluster compound comprising a Ag41 cage encapsulating a divacant [α-SiW10O37]10− anion and a complete [β-SiW12O40]4− anion as a counteranion. Two electro-redox centers associated with the inner and outer POM anions show interesting electrochemical behaviours, because the stable Ag41 cage acts as an electron transfer mediator. [ABSTRACT FROM AUTHOR]

Enantiopure chiral cubic cages have been diastereoselectively synthesized for the first time. Chiral amines lead to the isolation of O symmetric homochiral cubic cages, while an achiral amine gives a racemic mixture. CD enhancement is observed as a result of configuration rigidity. [ABSTRACT FROM AUTHOR]

A convenient method for the synthesis of silver alkynyl compounds containing different nuclearities has been developed. The reaction of AgC≡CBut and AgX (X = CF3CO2−, C2F5CO2−) in the presence of auxiliary ligands L (L = bipyridine, bipy; 1,10-phenanthroline, phen; 2-(diphenylphosphino)pyridine, dppy) under different conditions afforded a family of new silver alkynyl compounds, namely, [Ag3(bipy)(C≡CBut)(CF3CO2)2]n (1), [Ag4(bipy)2(C≡CBut)(CF3CO2)3]n (2), [Ag6(phen)3(C≡CBut)2(C2F5CO2)4(MeOH)(EtOH)] (3), [Ag8L4(C≡CBut)2(C2F5CO2)6] (L = bipy, 4; L = phen, 5), [Ag10(dppy)2(C≡CBut)6X4] (X = CF3CO2−, 6; X = C2F5CO2−, 7), [Ag12(bipy)2(C≡CBut)8(C2F5CO2)4] (8) and [Ag12(phen)4(C≡CBut)6(CF3CO2)6]·2EtOH (9). Single-crystal X-ray analysis revealed that compounds 1 and 2 display infinite-chain structures, while the other seven compounds are discrete molecules containing silver nuclearities varying from 6 to 12. The formation of various structural motifs depends on the reactant ratios and the ligands/anions with different nature. [ABSTRACT FROM AUTHOR]

The exact interaction between Au cores and surface ligands remains largely unknown because of the complexity of the structure and chemistry of ligand/Au-core interfaces in ligand-protected Au nanoclusters (AuNCs), which are commonly found in many organic–inorganic complexes. Here, femtosecond transient absorption measurement of the excited-state dynamics of a newly synthesized phosphine-protected cluster [Au20(PPhpy2)10Cl4]Cl2 (1) is reported. Intramolecular charge transfer (ICT) from the Au core to the peripheral ligands was identified. Furthermore, we found that solvation strongly affected ICT at ligand/Au-core interfaces while by choosing several typical alcoholic solvents with different intrinsic solvation times, we successfully observed that excited-state relaxation dynamics together with displacive excited coherent oscillation of Au20 clusters were significantly modulated through the competition between solvation and surface trapping. The results provide a fundamental understanding of the structure–property relationships of the solvation-dependent core–shell interaction of AuNCs for the potential applications in catalysis, sensing and nanoelectronics. [ABSTRACT FROM AUTHOR]

Two new tri-connected copper(i) coordination polymers have been synthesized, featuring a 1D staircase-like structure and an interpenetrating 2D polycyclohexane framework. The geometries are controlled by steric factors that are generated from the terminal blocking ligand 2-diphenylphosphino-n-methyl pyridine (n = 3, 6) with the methyl group at different substituted positions. [ABSTRACT FROM AUTHOR]

The first silver cluster encapsulating an organic anion―squarate dianion―has been synthesized. Two C4O42− anions arranged in a staggered sandwich type arrangement are confined in the Ag24 cage. The incorporation of squarate anions into the silver alkynyl system leads to the red shift of absorption of the cluster in comparison to silver squarate. [ABSTRACT FROM AUTHOR]

A silver alkynyl cluster containing a Ag70 shell and two lacunary [PW9O34]9− templating ions was synthesized by an ionothermal approach. Fast core–shell electronic communication between silver(i) centers and polyoxometalates was verified via cyclic voltammetry studies in [BMIm]BF4. [ABSTRACT FROM AUTHOR]

Methanol drives the blue emissive complex, [Cu2(dppy)3(MeCN)](BF4)2(dppy = diphenylphosphino-pyridine), with a head-to-tail arrangement of the three bridging phosphine ligands to convert to its linkage isomer (head-to-head, green emissive) in the solid state, and the transformation could be reversibly realized through recrystallization in different solvents. [ABSTRACT FROM AUTHOR]

We report a unique intercluster compound comprising a Ag41 cage encapsulating a divacant [α-SiW10O37]10− anion and a complete [β-SiW12O40]4− anion as a counteranion. Two electro-redox centers associated with the inner and outer POM anions show interesting electrochemical behaviours, because the stable Ag41 cage acts as an electron transfer mediator. [ABSTRACT FROM AUTHOR]

For the first time site-specific doping of silver into a spherical Au 25 nanocluster has been achieved in [Au 19 Ag 6 (MeOPhS) 17 (PPh 3 ) 6 ] (BF 4 ) 2 (Au 19 Ag 6 ) through a dual-ligand coordination strategy. Single crystal X-ray structural analysis shows that the cluster has a distorted centered icosahedral Au@Au 6 Ag 6 core of D 3 symmetry, in contrast to the I h Au@Au 12 kernel in the well-known [Au 25 (SR) 18 ] - (R = CH 2 CH 2 Ph). An interesting feature is the coexistence of [Au 2 (SPhOMe) 3 ] dimeric staples and [P-Au-SPhOMe] semi-staples in the title cluster, due to the incorporation of PPh 3 . The observation of only one double-charged peak in ESI-TOF-MS confirms the ordered doping of silver atoms. Au 19 Ag 6 is a 6e system showing a distinct absorption spectrum from [Au 25 (SR) 18 ] - , that is, the HOMO-LUMO transition of Au 19 Ag 6 is optically forbidden due to the P character of the superatomic frontier orbitals., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We report the total structure determination of a covalently bonded nanocluster polymer [Au7Ag9(dppf)3(CF3CO2)7BF4]n (1). This features a one-dimensional linear chain, consisting of unique molecular building blocks, Au7Ag8(dppf)3(CF3CO2)7 clusters, which are linked together by Ag-O bonds rather than Au-Au interactions or bidentate organic bridges as previously reported.

An alkynyl-protected gold nanocluster [Au40(PhC[triple bond, length as m-dash]C)20(dppm)4](SbF6)4 (dppm = bis(diphenylphosphino)methane) (1) has been synthesized. Single-crystal X-ray diffraction reveals that the cluster has a face-centered cubic (FCC) Au34 kernel that is made up of two Au20 units via sharing a rectangular face. Two linear PhC[triple bond, length as m-dash]C-Au-C[triple bond, length as m-dash]CPh staple motifs are located around the central part of the Au34 core, and four L-shaped PhC[triple bond, length as m-dash]C-Au-P^P staple motifs are located at the four corners of the Au34 core. Cluster 1 and [Au38(PhC[triple bond, length as m-dash]C)20(PPh3)4](CF3SO3)2 both have the FCC Au34 core, and it is found that the diphosphine ligands bringing two more Au atoms into the system have significant effects on the optical properties and stability of the clusters. The combination of a diphosphine ligand and an alkynyl ligand is helpful in generating new ligand-protected metal nanoclusters.

Ligand-protected metal nanoclusters as unique nanomaterials have attracted great attention. The protecting ligands that directly bind on the cluster surfaces are crucial in dictating the structures and properties of the clusters. In contrast to the extensively studied thiolates, alkynyl ligands have been found recently to be important ligands for passivating gold/silver cluster surfaces. In this Frontier article, recent advances in alkynyl-protected metal nanoclusters are overviewed, and the structures, luminescence and catalytic activities are also discussed. It is demonstrated that alkynyls are very promising ligands in the control of the structures and properties of gold/silver nanoclusters.

We report a unique intercluster compound comprising a Ag41 cage encapsulating a divacant [α-SiW(10)O37](10-) anion and a complete [β-SiW(12)O40](4-) anion as a counteranion. Two electro-redox centers associated with the inner and outer POM anions show interesting electrochemical behaviours, because the stable Ag41 cage acts as an electron transfer mediator.

A convenient method for the synthesis of silver alkynyl compounds containing different nuclearities has been developed. The reaction of AgC[triple bond, length as m-dash]CBu(t) and AgX (X = CF3CO2(-), C2F5CO2(-)) in the presence of auxiliary ligands L (L = bipyridine, bipy; 1,10-phenanthroline, phen; 2-(diphenylphosphino)pyridine, dppy) under different conditions afforded a family of new silver alkynyl compounds, namely, [Ag3(bipy)(C[triple bond, length as m-dash]CBu(t))(CF3CO2)2]n (), [Ag4(bipy)2(C[triple bond, length as m-dash]CBu(t))(CF3CO2)3]n (), [Ag6(phen)3(C[triple bond, length as m-dash]CBu(t))2(C2F5CO2)4(MeOH)(EtOH)] (), [Ag8L4(C[triple bond, length as m-dash]CBu(t))2(C2F5CO2)6] (L = bipy, ; L = phen, ), [Ag10(dppy)2(C[triple bond, length as m-dash]CBu(t))6X4] (X = CF3CO2(-), ; X = C2F5CO2(-), ), [Ag12(bipy)2(C[triple bond, length as m-dash]CBu(t))8(C2F5CO2)4] () and [Ag12(phen)4(C[triple bond, length as m-dash]CBu(t))6(CF3CO2)6]·2EtOH (). Single-crystal X-ray analysis revealed that compounds and display infinite-chain structures, while the other seven compounds are discrete molecules containing silver nuclearities varying from 6 to 12. The formation of various structural motifs depends on the reactant ratios and the ligands/anions with different nature.

The exact interaction between Au cores and surface ligands remains largely unknown because of the complexity of the structure and chemistry of ligand/Au-core interfaces in ligand-protected Au nanoclusters (AuNCs), which are commonly found in many organic-inorganic complexes. Here, femtosecond transient absorption measurement of the excited-state dynamics of a newly synthesized phosphine-protected cluster [Au20(PPhpy2)10Cl4]Cl2 (1) is reported. Intramolecular charge transfer (ICT) from the Au core to the peripheral ligands was identified. Furthermore, we found that solvation strongly affected ICT at ligand/Au-core interfaces while by choosing several typical alcoholic solvents with different intrinsic solvation times, we successfully observed that excited-state relaxation dynamics together with displacive excited coherent oscillation of Au20 clusters were significantly modulated through the competition between solvation and surface trapping. The results provide a fundamental understanding of the structure-property relationships of the solvation-dependent core-shell interaction of AuNCs for the potential applications in catalysis, sensing and nanoelectronics.

A silver alkynyl cluster containing a Ag70 shell and two lacunary [PW9O34](9-) templating ions was synthesized by an ionothermal approach. Fast core-shell electronic communication between silver(i) centers and polyoxometalates was verified via cyclic voltammetry studies in [BMIm]BF4.

Blue or yellow-green emission is observed from two different crystal types of the same gold(I)-silver(I) molecular cluster [SAu(3)Ag(L1)(3)](BF(4))(2) (L1 = 2-diphenylphosphino-4-methylpyridine) depending on the crystallization conditions; structural data suggest that intermolecular Au···Au interactions account for the luminescence vapochromic responses; a similar observation was made on two other pairs of analogues.

An unprecedented trigonal prismatic (μ(6)-C)Au(6) structure has been found in a novel gold(I)-copper(I) cluster with a hypercoordinated carbon, [CAu(6)Cu(2)(dppy)(6)](BF(4))(4); the incorporation of copper ions enhances the rigidity and integrity of the cluster and turns on the bright red solution luminescence., (© The Royal Society of Chemistry 2011)

A novel nonadecanuclear silver double cage was isolated, in which a square antiprism and a pentacapped pentagonal prism templated by a chloride ion share a tetragonal face to form a snowman-like cluster that is held together by bridging alkynyl groups and trifluoroacetates.

Unprecedented eta 3 pi-donor behavior of the benzyltrimethy-lammonium ion is observed in the polymeric silver(I) complex [(PhCH2NMe3)Ag7(C2)(CF3CO2)6]n that comprises a columnar backbone constructed from the fusion of Ag8 square antiprisms each enclosing an acetylide dianion.

9-Fluorenylidenemalononitrile reacts with 10-methyl-9,10-dihydroacridine in deaerated acetonitrile under irradiation with lambda > 320 nm to give a coupling product 9-dicyanomethyl-9-(10'-methyl-9'-acridinyl)fluorene, characterized by X-ray crystallographic, MS and NMR analyses.