Alkynyl Coinage Metal Clusters and Complexes–Syntheses, Structures, and Strategies

Abstract

In this Concept we discuss how the chemistry of coinage metal complexes based on alkynyl ligands has developed over the past decades. The rich coordination of alkynyl, that exhibit both η (end-on) and η (side on) modes, includes non-bridged systems, as well as bridging of up to four (or six) metal centres. Resulting metal clusters often exhibit highly regular structures and typical coordination motifs forming fascinating assemblies exploiting this versatile coordination. Metallophilic interactions are often an important driving force for the formation of large clusters. In addition, the use of co-ligands as well the possibility to encapsulate counter ions greatly increases the chemical and structural diversity. Herein we attempt to summarize and highlight design principles towards multinuclear homo and hetero-bi-metallic coinage metal clusters of alkynyl ligands.

Cuprophilic Interactions in and between Molecular Entities

“…The Cu-Cud istance in 118 was determined to be 2.9217 (17) by X-ray crystallography.I ti sc lear that repulsion between two [CuCl 2 ] À ions in 118 was stabilized by the counter cations. The ion pair [CuL][CuCl 2 ][ L= 1,1'-bis(2-pyridyl)octamethylferrocene (119)] was characterized by Siemeling et al [176] ] À ion. Although the Cu-Cud istance of 2.810(2) in 119 was significantly shorter than that in 118,as trong electrostatic attraction between the two moieties was concluded based on DFT calculations, along with secondary interactions between the Cu + core of the cation and the two chlorine atoms in the [CuCl 2 ] À ion.…”

Synthesis and Reactivity of an Early‐Transition‐Metal Alkynyl Cubane Mn4C4 Cluster

“…[9,10] Alkyne ligands constitute ad istinct and versatile class of ligands for the design of metal cluster architectures.T hey offer various coordination modes (s, p 2 , p 4 ;t erminal and bridging), are competent stabilizers of atomically precise nanoclusters,a nd provide the opportunity for facile removal or ligand exchange under mild conditions. [11,12] Despite the broad availability of alkynyl metal complexes and their significance as catalytic intermediates in many organic transformations, there are only very few reports of discrete s,m 3 -alkynyl metal nanoclusters bearing late transition metals other than Group 11 metals (i.e.Ru, Rh and Ni)and ancillary ligands. [11,12] Despite the broad availability of alkynyl metal complexes and their significance as catalytic intermediates in many organic transformations, there are only very few reports of discrete s,m 3 -alkynyl metal nanoclusters bearing late transition metals other than Group 11 metals (i.e.Ru, Rh and Ni)and ancillary ligands.…”

“…[11,13] Accordingly,t he reaction of divalent Mn[N(SiMe 3 ) 2 ] 2 (1)w ith phenylacetylene in n-hexane afforded ay ellow-orange solution, which upon cooling led to the novel alkynyl manganese complex {Mn(m 3 -CCPh)(N-[SiMe 3 ] 2 )} 4 (2,S cheme 3). [11,13] Accordingly,t he reaction of divalent Mn[N(SiMe 3 ) 2 ] 2 (1)w ith phenylacetylene in n-hexane afforded ay ellow-orange solution, which upon cooling led to the novel alkynyl manganese complex {Mn(m 3 -CCPh)(N-[SiMe 3 ] 2 )} 4 (2,S cheme 3).…”

“…[10] TheM n-C distances (2.21771(4), 2.27113(4), 2.31275 (7) )and CCbond lengths (1.22291 (2) )i n2 are comparable with those of the bimetallic m 2 -h 1 :h 1 -alkynyl complexes [(nacnac)Mn(C CPh)] 2 and [CpMn(CCPh)(THF)] 2 (nacnac = HC-{CMeN(2,6-iPr 2 C 6 H 3 )} 2 ,C p = cyclopentadienyl). [11] Examples involving other transition metals are very rare,w ith only ah andful of s,m 3 -alkynyl complexes of the late transition metals Ru, Rh, and Ni reported. [11] Examples involving other transition metals are very rare,w ith only ah andful of s,m 3 -alkynyl complexes of the late transition metals Ru, Rh, and Ni reported.…”

Synthesis and Reactivity of an Early‐Transition‐Metal Alkynyl Cubane Mn4C4 Cluster

“…[11, 12b] Stable alkynyl clusters of the coinage metals (Cu, Ag, Au), which benefit from the soft carbophilicity of the Group 11 metals,have most often been prepared, and their photophysical properties and catalytic activities studied (Scheme 1). [11,12] Despite the broad availability of alkynyl metal complexes and their significance as catalytic intermediates in many organic transformations, there are only very few reports of discrete s,m 3 -alkynyl metal nanoclusters bearing late transition metals other than Group 11 metals (i.e.Ru, Rh and Ni)and ancillary ligands. [13] Documented herein is the facile and high-yielding synthesis of aw ell-defined heteroleptic alkynyl-Mn 4 cluster,c omprising the first s,m 3 -alkynyl Mn 3 unit and the first early-transitionmetal alkynyl cubane motifs (Scheme 2), its full characterization, and its application to nanoparticle formation and catalysis.…”