Role of Anions Associated with the Formation and Properties of Silver Clusters

Abstract

Metal clusters have been very attractive due to their aesthetic structures and fascinating properties. Different from nanoparticles, each cluster of a macroscopic sample has a well-defined structure with identical composition, size, and shape. As the disadvantages of polydispersity are ruled out, informative structure-property relationships of metal clusters can be established. The formation of a high-nuclearity metal cluster involves the organization of metal ions into a complex entity in an ordered way. To achieve controllable preparation of metal clusters, it is helpful to introduce a directing agent in the formation process of a cluster. To this end, anion templates have been used to direct the formation of high nuclearity clusters. In this Account, the role of anions played in the formation of a variety of silver clusters has been reviewed. Silver ions are positively charged, so anionic species could be utilized to control the formation of silver clusters on the basis of electrostatic interactions, and the size and shape of the resulted clusters can be dictated by the templating anions. In addition, since the anion is an integral component in the silver clusters described, the physical properties of the clusters can be modulated by functional anions. The templating effects of simple inorganic anions and polyoxometales are shown in silver alkynyl clusters and silver thiolate clusters. Intercluster compounds are also described regarding the importance of anions in determining the packing of the ion pairs and making contribution to electron communications between the positive and negative counterparts. The role of the anions is threefold: (a) an anion is advantageous in stabilizing a cluster via balancing local positive charges of the metal cations; (b) an anion template could help control the size and shape of a cluster product; (c) an anion can be a key factor in influencing the function of a cluster through bringing in its intrinsic properties. Properties including electron communication, luminescent thermochromism, single-molecule magnet, and intercluster charge transfer associated with anion-directed silver clusters have been discussed. We intend to attract chemists' attention to the role that anions could play in determining the structures and properties of metal complexes, especially clusters. We hope that this Account will stimulate more efforts in exploiting new role of anions in various metal cluster systems. Anions can do much more than counterions for charge balance, and they should be considered in the design and synthesis of cluster-based functional materials.

Anion‐Templated Nanosized Silver Alkynyl Clusters: Cluster Engineering and Solution Behavior

“…[3] Further advances in silver-alkynyl complexes were achieved by introducing variousa nionsa s templates, including inorganic Cl À ,N O 3 À ,C O 3 2À ,S O 4 2À ,C rO 4 2À , largerp olyoxometalate, and even organic squarate to achieve high-nuclear clusters. [6] To the besto fo ur knowledge,o nly one example is an anionic Ag 36 cluster template by one Cl À and two [(O) 2 cluster. On the other hand,d ifferent anionsa st emplates caged in one silver alkynyl clusterh ave rarely been observed in this field.…”

Silver(I) Clusters with Carba‐closo‐dodecaboranylethynyl Ligands: Synthesis, Structure, and Phosphorescence

“…[1-3, 7, 8] An especially unique facet of the chemistry of silver(I)-alkynyl complexes is the accessibility of different types of well-definedc lusters. [8,11] Often,a rgentophilic interactions are decisive in these self-organization reactions to yield silver(I) clusters. [8,11] Often,a rgentophilic interactions are decisive in these self-organization reactions to yield silver(I) clusters.…”

“…[Ag16 8 (Py) 9.25 (CH 3 CN) 2 (CH 2 Cl 2 ) 0.75 ]int he crystal of 11·CH 2 Cl 2 (hydrogen atoms and the disordered Py ligand are omitted for clarity; d(Ag···Ag) 344 pm:bold dashed lines; d(Ag···Ag) > 344 pm:t hin dashedl ines;d isplacemente llipsoids of the Ag atomsa tthe 50 %p robability level).…”

High‐Nuclear Organometallic Copper(I)–Alkynide Clusters: Thermochromic Near‐Infrared Luminescence and Solution Stability

“…The Fenske group has reported Cu I clusters as large as 136 Cu incorporating small E 2À ligands( E= S, Se, andT e) and co-protected by phosphine and thiolate. [9] However,m ixingC u I and alkynyl can indiscriminately form intractable polymericm aterials, which are very hard to obtain as crystals,t hat makes the synthesis of discrete Cu I -alkynyl clusters more challenging. [8] Alkynyl has provedt ob easuperior bridging ligand for the construction of Ag I clusters using its characteristic s-a nd p-coordination modes.…”