Reductive Coupling of Metal Triangles in Sandwich Complexes

Di- and trinuclear sandwich complexes of a cross-conjugated fulvene

We report di- and trinuclear palladium sandwich complexes of cross-π-conjugated fulvenes. Structural and theoretical analysis revealed that a fulvene sandwich framework holds a metal-metal bonded moiety, where the dinuclear and trinuclear bonds feature strong donation and back-donation, respectively. The trinuclear fulvene sandwich complex undergoes a unique reversible extrusion of a Pd atom from inside to outside the sandwich framework.

Pyridine dicarbanion-bonded Ag13 organometallic nanoclusters: synthesis and on-surface oxidative coupling reaction

Unprecedented pyridine dicarbanion-bonded Ag13 nanoclusters were constructed according to a macrocycle-involved two-step synthetic protocol.

Selective dimerization of a trinuclear mixed-metal sandwich complex: construction of an axially chiral metal skeleton

Certain metal sandwich complexes undergo dimerization through metal-metal bond formation. Here, we found that a reductive dimerization of mixed-metal Pd₂Pt or PdPt₂ sandwich complexes proceeds through selective Pt-Pt bond formation. A restricted rotation at the Pt-Pt bond of the PdPt₂ dimer gave a unique axially chiral structure derived from a heterometal arrangement in a mixed-metal cluster.

Heterometallic d8 -d10 Coupling of Rh(I) and M(0) (M=Pd, Pt) in a Sandwich Framework of π-Conjugated Ligands

A heterometallic M-M' bond formation is a key to construct atomically precise bimetallic clusters and materials. However, it is sometimes not straightforward to construct a heterometallic M-M' bond through conventional methods including redox condensation. Here, we found that a sandwich framework of π-conjugated unsaturated hydrocarbon ligands provides a unique coordination environment that facilitates unusual coupling of d⁸ Rh^I and d¹⁰ M⁰ (M=Pd, Pt). The molecular orbital analysis showed that the electron-accepting ability of the sandwich framework through back-donation allows the formation of a dσ-type Rh-Pd bond in a (d-d)¹⁸ electron system.

Exceeding Metal Capacity in Sandwich Complexes: Ligand-Unsupported Docking of Extra Metal Moieties at Edges of a Metal Sheet Sandwich Complex

The ligand-unsupported accommodation of extra metal moieties in a sandwich complex is reported. Although it has been considered that the metal-capacity of a metal sheet sandwich complex is strictly limited by the size of cyclic unsaturated hydrocarbon ligands, the M-M edge bonds in a metal sheet sandwich complex provide a ligand-unsupported docking site for extra metal moieties, allowing expansion of metal-capacity in sandwich complexes. The metal sheet sandwich complex [Pd₄ (μ₄ -C₈ H₈ )(μ₄ -C₉ H₉ )]⁺ , in which the ligand-based metal capacity is full in terms of the usage of all C=C moieties of the smaller carbocyclic ligand C₈ H₈ in coordination, can accommodate extra M⁰ {P(OPh)₃ }₂ (M=Pd, Pt) moieties without coordinative assistance by either the C₉ H₉ or the C₈ H₈ ligand.

Three-Dimensional Sandwich Nanocubes Composed of 13-Atom Palladium Core and Hexakis-Carbocycle Shell

Coordination of cyclic unsaturated hydrocarbons to transition metal generally gives bis-ligated sandwich complexes, which are a fundamental class of organometallic compounds. This sandwich structure may be extended to a higher-order three-dimensional one when more than two carbocyclic ligands surround an agglomerate of many transition metal atoms. Here, we report synthesis of three-dimensional sandwich nanocube compounds containing a close-packed transition metal cluster core. Reduction of a [Pd₃(μ₃-C₇H₇)₂]²⁺ with tetraarylborate under neat conditions afforded [Pd₁₃(μ₄-C₇H₇)₆]²⁺ containing a cuboctahedral Pd₁₃ core with an octahedral ligand-shell.

B-Hb⋯π interactions in benzene–borazine sandwich and multidecker complexes: a DFT study

Multidecker complexes of benzene/borazine can be formed through B-H_b⋯π interactions.

Theoretical studies on the bonding and electron structures of a [Au3Sb6]3− complex and its oligomers

Theoretical studies of an all-metal [Sb₃Au₃Sb₃]³⁻ sandwich complex and its congeners [X₃M₃X₃]³⁻ (M = Cu, Ag, Au, Rg; X = N, P, As, Sb, Bi, Uup) as well as [Sb₃(Au₃Sb₃)_n]³⁻ (n = 1–4) oligomers indicate the possible existence of other [A_pM_pA_p]^x− sandwich compounds and oligomers.

On the nature of chemical bonding in the all-metal aromatic [Sb3Au3Sb3]3− sandwich complex

All-metal aromatic sandwich [Sb₃Au₃Sb₃]³⁻ is held together via three 3c–2e Sb–Au–Sb σ bonds, due to the collective contributions from some 17 molecular orbitals.

Modulation of benzene or naphthalene binding to palladium cluster sites by the backside-ligand effect

The backside-ligand modulation strategy to enhance the substrate binding property of Pd clusters is reported. The benzene or naphthalene binding ability of Pd3 or Pd4 clusters is enhanced significantly by the backside cyclooctatetraene ligand, leading to the formation of the first solution-stable benzene- or naphthalene Pd clusters. The present results imply that the ligand design of the metal clusters, especially for the backside ligand of the metal cluster site, is crucial to acquire a desired reactivity of metal clusters.

Structures and magnetism of multinuclear vanadium-pentacene sandwich clusters and their 1D molecular wires

Two types of multinuclear sandwich clusters, (V(3))(n)Pen(n+1), (V(4))(n)Pen(n+1) (Pen = Pentacene; n = 1, 2), and their corresponding infinite one-dimensional (1D) molecular wires ([V(3)Pen](∞), [V(4)Pen](∞)) are investigated theoretically, especially on their magnetic coupling mechanism. These sandwich clusters and molecular wires are found to be of high stability and exhibit intriguing magnetic properties. The intra-layered V atoms in (V(3))(n)Pen(n+1) clusters prefer antiferromagnetic (AFM) coupling, while they can be either ferromagnetic (FM) or AFM coupling in (V(4))(n)Pen(n+1) depending on the intra-layered V-V distances via direct exchange or superexchange mechanism. The inter-layered V atoms favor FM coupling in (V(3))(2)Pen(3), whereas they are AFM coupled in (V(4))(2)Pen(3). Such magnetic behaviors are the consequence of the competition between direct exchange and superexchange interactions among inter-layered V atoms. In contrast, the 1D molecular wires, [V(3)Pen](∞) and [V(4)Pen](∞), appear to be FM metallic with ultra high magnetic moments of 6.8 and 4.0 μ(B) per unit cell respectively, suggesting that they can be served as good candidates for molecular magnets.

Selective construction of Pd2Pt and PdPt2 triangles in a sandwich framework: carbocyclic ligands as scaffolds for a mixed-metal system

Sandwich time! The mixed-metal triangular-trinuclear sandwich complexes of Pd(2)Pt and PdPt(2) were selectively synthesized. The Pd(2)Pt and PdPt(2) triangles in a cycloheptatrienyl sandwich framework were identified by (31)P NMR analyses of the tris-triphenylphosphine complexes (see scheme).

Theoretical study of structure, bonding, and electronic behavior of novel sandwich compounds M₃(C6R6)₂ (M = Ni, Pd, Pt; R = H, F)

The correlations between the structural and electronic properties of the monolayer clusters M₃ (where M = Ni, Pd, Pt) and the sandwich complexes M₃(C₆R₆)₂ (where M = Ni, Pd, Pt; R = H, F) were studied by performing quantum-chemical calculations. All of the sandwich complexes are strongly donating and backdonating metal-ligand bonding structures. The influence of the ligand as well as significant variations in the M-C, M-M, and C-C bond lengths and binding energies were examined to obtain a qualitative and quantitative picture of the intramolecular interactions in C₆R₆-M₃. Our theoretical investigations show that the binding energies of these sandwich complexes gradually decrease from Ni to Pt as well as from H to F, which can be explained via the frontier orbitals of the clusters M₃ and C₆R₆.