First oxido-bridged cubo-octahedral hexanuclear rhenium clusters

Selective Oxidation of Inner Pnictogenide Ligands in Mixed-Ligand Rhenium Cubane-Type Cluster Complexes

Reactivity of new tetrahedral rhenium cluster complexes with pnictogenide inner ligands μ₃-As^3-, μ₃-Sb^3-, and μ₃-Bi^3- has been investigated in reactions with aqueous H₂O₂. It has been found that the oxidation of clusters [{Re₄As₃Q}(CN)₁₂]^7- (Q = S or Se) led to the formation of stable clusters with μ₃-(AsO)^3- ligands. Under the same conditions, the oxidation of [{Re₄As₂S₂}(CN)₁₂]^6- cluster led to substitution of μ₃-As^3- ligands to μ₃-O^2-. The resulting cluster [{Re₄O₂S₂}(CN)₁₂]^4- easily undergoes further oxidation, and even at room temperature, a unique {Re₄} to {Re₃} rearrangement occurs with the formation of the new triangular cluster [{Re₃(μ₃-S)(μ-O)₂(μ-SO₂)}(CN)₉]^5-. Upon heating, this process proceeds faster and the triangular cluster can be isolated as individual compounds. Cluster anions [{Re₄SbSe₃}(CN)₁₂]^5- and [{Re₄BiS₃}(CN)₁₂]^5- reacted with H₂O₂, yielding clusters containing μ₃-O^2- ligands, namely, [{Re₄OSe₃}(CN)₁₂]^4- and [{Re₄OS₃}(CN)₁₂]^4-. This indicates that oxidized forms of μ₃-Sb^3- and μ₃-Bi^3- ligands can be easily substituted.

Paramagnetic Rhenium Iodide Cluster with N-Heterocyclic Carbene

triangulo-Trirhenium nonaiodide Re₃I₉ reacts with 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene (IMes) to produce the novel 13-electron paramagnetic cluster Re₃I₈(IMes)₂, which was characterized by means of X-ray diffraction analysis, ESR spectroscopy, magnetometry, and quantum chemistry.

Stabilization of Re37+/Re38+ Metalloclusters by Cyanide Ligands in New Trinuclear Rhenium Cluster Complexes [{Re3X3}(CN)9]4-/[{Re3X3}(CN)9]5- (X = Br or I)

The interaction of rhenium(III) halides Re₃Br₉ and Re₃I₉ with aqueous solution of sodium cyanide resulted in the formation of the first trinuclear halide-cyanide rhenium cluster complexes [{Re₃X₃}(CN)₉]^5-/[{Re₃X₃}(CN)₉]^4- (X = Br or I) crystallized as salts of the compositions Cs₄Na[{Re₃Br₃}(CN)₉]·5.25H₂O (1), Cs₄Na[{Re₃I₃}(CN)₉]·6H₂O (2), Cs₄[{Re₃Br₃}(CN)₉]·2H₂O·0.5CsCl (3), and Cs₄[{Re₃I₃}(CN)₉]·(4). All of the compounds are stable in air in the solid state and in aqueous solution. The substitution of apical halide ligands in the parent compounds Re₃X₉ by cyanides led to reduction of the original metallocluster Re₃⁹⁺ (12 cluster valence electrons (CVEs)) to Re₃⁷⁺ (14 CVEs), forming the compounds 1 and 2. The apical CN^- ligands affect the electronic structure of the Re₃ metallocluster stabilizing reduced form. Complexes 1 and 2 represent the first examples of triangular rhenium clusters with the Re₃⁷⁺ metallocluster. The reaction of 1 and 2 with H₂O₂ resulted in formation of compounds 3 and 4 with the formal charge of the Re₃ metallocluster equal to 8+, and no further oxidation to Re₃⁹⁺ occurred. The compounds were characterized by the X-ray diffraction analysis, NMR and UV-vis spectroscopies, mass spectrometry, cyclic voltammetry, and magnetic susceptibility measurements.

Inorganic Ligands Sb3- and Bi3-: Synthesis and Crystal Structures of Complexes with Mixed-Ligand Cluster Cores {Re4Se3Sb}7+ and {Re4Se3Bi}7

The reactions of ReI₃, Se, and KCN with Sb₂O₃ or Bi₂O₃ at elevated temperature led to the formation of two new tetrahedral clusters with mixed-ligand cluster cores {Re₄Se₃Sb}⁷⁺ and {Re₄Se₃Bi}⁷⁺. They are the first examples of complexes with either Sb^3- or Bi^3- ligands, which have never been previously described in the literature.

The {Re4} Tetrahedral Cyanometalate Cluster Anion [{Re4(μ3-CCN)4}(CN)12]8- with Inner (μ3-CCN)3- Ligands and Its Features in Coordination of Cu2+ Cations

A reaction between ReI₃ and KCN at elevated temperature led to the formation of the new cyanometalate cluster anion [{Re₄(μ₃-CCN)₄}(CN)₁₂]^8- (1). The anion contains μ₃-CCN^3- ligands, which are stabilized by the coordination to the triangular faces of the tetrahedral {Re₄} metallocluster in a μ₃ mode. The compound crystallized as a potassium salt, and its crystal structure was determined by single-crystal X-ray diffraction analysis. It was shown that μ₃-CCN^3- ligands are ambidentate and can interact with transition-metal cations similarly to terminal CN groups, resulting in the polymer framework formation.

PO23- and AsO3-: Pnictogenide Ligands in the Highly Charged Re4 Cluster Anions [{Re4(PO)3(PO2)}(CN)12]8-, [{Re4As2(AsO)2}(CN)12]8-, and [{Re4(AsO)4}(CN)12]8

New tetrahedral anionic rhenium cluster complexes [{Re₄(PO)₃(PO₂)}(CN)₁₂]^8- (1) and [{Re₄As₂(AsO)₂}(CN)₁₂]^8- (2) have been synthesized by the reaction of ReI₃ with NaCN and P_red or KCN and As_gray, respectively. Compound 2 was further oxidized by aqueous H₂O₂ to produce the cluster anion [{Re₄(AsO)₄}(CN)₁₂]^8- (3). The anions contain new pnictogen/oxygen-based ligands, PO₂^3- and AsO^3-, which were stabilized by the coordination to the triangular faces of the tetrahedral Re₄ metallocluster in μ₃-mode. All three compounds were crystallized as either sodium or potassium salts, and their crystal structures were determined by single crystal X-ray diffraction analysis.

Facile Substitution of Bridging SO22- Ligands in Re12 Bioctahedral Cluster Complexes

Selective substitution of μ-SO₂^2- groups by either O^2- or Se^2- ions occurs upon heating the bioctahedral rhenium cluster complex K₆[Re₁₂CS₁₄(μ-SO₂)₃(CN)₆] in air atmosphere or in the presence of a Se source, respectively, manifesting the remarkable lability of SO₂^2- ligands bound to a transition-metal cluster. A series of compounds based on the new mixed-ligand anions, [Re₁₂CS₁₄(μ-O)₃(CN)₆]^6-, [Re₁₂CS₁₄(μ-Se)₃(CN)₆]^6-, and [Re₁₂CS₁₄(μ-O)₃(OH)₆]^6-, were isolated and their solid-state structures were elucidated by single-crystal X-ray diffraction analysis. Along with the previously reported μ-sulfide clusters, the new species constitute a series of rhenium anionic complexes with the common formula [Re₁₂CS₁₄(μ-Q)₃L₆]^6- (Q = O, S, Se, L = CN^-; Q = O, S, L = OH^-), within which the total charge and number of cluster valence electrons (CVEs) are constant. The article presents insights into the mechanistic and synthetic aspects of the substitution process, and it comprehensively discusses the influence of inner ligand environment on the structure, spectroscopic characteristics, and electrochemical behavior of the novel compounds.