Bimetallic Nickel–Cobalt Hexacarbido Carbonyl Clusters [H_6–<i>n</i>Ni₂₂Co₆C₆(CO)₃₆]^<i>n</i>− (<i>n</i> = 3–6) Possessing Polyhydride Nature and Their Base-Induced Degradation to the Monoacetylide [Ni₉CoC₂(CO)_{16–<i>x</i>}]^3– (<i>x</i> = 0, 1)

The reaction of [Ni₁₀C₂(CO)₁₆]^2– with Co₃(μ₃-CCl)­(CO)₉ results in the new bimetallic Ni–Co hexacarbido carbonyl clusters [H_6–<i>n</i>Ni₂₂Co₆C₆(CO)₃₆]^<i>n</i>− (<i>n</i> = 3–6), which possess polyhydride nature and can be interconverted by means of acid–base reactions. The tetra-anion [H₂Ni₂₂Co₆C₆(CO)₃₆]^4– and the hexa-anion [Ni₂₂Co₆C₆(CO)₃₆]^6– have been isolated in a crystalline state and structurally characterized via X-ray crystallography. The six carbide atoms are lodged into Ni₇CoC square antiprismatic cages. Addition of strong bases to [Ni₂₂Co₆C₆(CO)₃₆]^6– affords mixtures of the monoacetylides [Ni₉CoC₂(CO)₁₆]^3– and [Ni₉CoC₂(CO)₁₅]^3–, which have been cocrystallized as [NEt₄]₃[Ni₉CoC₂(CO)_{16–<i>x</i>}] (<i>x</i> = 0.58–0.84) salts, displaying tightly bonded interstitial C₂ units

Tetrahedral [H_<i>n</i>Pt₄(CO)₄(P^∧P)₂]^<i>n</i>+ (<i>n</i> = 1, 2; P^∧P = CH₂C(PPh₂)₂) Cationic Mono- and Dihydrido Carbonyl Clusters Obtained by Protonation of the Neutral Pt₄(CO)₄(P^∧P)₂

The reaction of [Pt₁₂(CO)₂₄]^2– with CH₂C­(PPh₂)₂ (P^∧P) results in the neutral tetrahedral cluster Pt₄(CO)₄(P^∧P)₂. This reacts with strong acids such as HBF₄ to afford, first, the [HPt₄(CO)₄(P^∧P)₂]⁺ monohydride monocation and, then, the [H₂Pt₄(CO)₄(P^∧P)₂]²⁺ dihydride dication. The three clusters have been fully characterized in solution by means of IR and ¹H and ³¹P NMR spectroscopy. Both Pt₄(CO)₄(P^∧P)₂ and [H₂Pt₄(CO)₄(P^∧P)₂]²⁺ are static in solution, whereas [HPt₄(CO)₄(P^∧P)₂]⁺ displays a fluxional behavior of the unique hydride ligand. In addition, the molecular structures of all these clusters have been fully determined in the solid state via single-crystal X-ray diffraction, showing that all of them possess the same 56-electron tetrahedral Pt₄(CO)₄(P^∧P)₂ core to which the hydride ligands are added stepwise

PPh₃‑Derivatives of [Pt_3<i>n</i>(CO)_6<i>n</i>]^2– (<i>n</i> = 2–6) Chini’s Clusters: Syntheses, Structures, and ³¹P NMR Studies

The reaction of the [Pt_3<i>n</i>(CO)_6<i>n</i>]^2– (<i>n</i> = 2–6) Chini’s clusters with increasing amounts of PPh₃ has been investigated in detail by combined FT-IR, ³¹P­{¹H} NMR, and electrospray ionization-mass spectrometry (ESI-MS) studies, showing that up to three CO ligands are gradually substituted by PPh₃, resulting in isonuclear phosphine-substituted anionic clusters of general formula [Pt_3<i>n</i>(CO)_{6<i>n</i>−<i>x</i>}(PPh₃)_<i>x</i>]^2– (<i>n</i> = 2–6; <i>x</i> = 1–3). Further addition of PPh₃ results in the elimination of the neutral Pt₃(CO)₃(PPh₃)₃ species and formation of lower nuclearity anionic clusters. [Pt₁₂(CO)₂₂(PPh₃)₂]^2– and [Pt₉(CO)₁₆(PPh₃)₂]^2– have been structurally characterized, and they maintain the trigonal prismatic structures of the parent homoleptic clusters, with the two PPh₃ ligands bonded to different external Pt₃-triangles in relative cis-position. Conversely, the crystal structure of [Pt₆(CO)₁₀(PPh₃)₂]^2– shows that its metal cage is transformed from trigonal prismatic to trigonal antiprismatic after CO/PPh₃ exchange

New High-Nuclearity Carbonyl and Carbonyl-Substituted Rhodium Clusters and Their Relationships with Polyicosahedral Carbonyl-Substituted Palladium- and Gold-Thiolates

A reinvestigation of the synthesis of [H_5–<i>n</i>Rh₁₃(CO)₂₄]^<i>n</i>− (<i>n</i> = 2, 3) led to isolation of a series of Rh₁₉, Rh₂₆, and Rh₃₃ high-nuclearity carbonyl and carbonyl-substituted rhodium clusters. The [Rh₁₉(CO)₃₁]^5– (<b>1</b>) is electronically equivalent with [Pt₁₉(CO)₂₂]^4–, but poor crystal diffraction data of all salts obtained to date have prevented its geometrical analysis. The structures of Rh₂₆(CO)₂₉(CH₃CN)₁₁ (<b>2</b>) as <b>2</b>·2CH₃CN and [Rh₃₃(CO)₄₇]^5– (<b>3</b>) as [NEt₄]₅[<b>3</b>]·Me₂CO were determined from complete X-ray diffraction determinations. The latter two species adopt polyicosahedral metal frameworks, and notably, [Rh₃₃(CO)₄₇]^5– represents the molecular group 9 metal carbonyl cluster of highest nuclearity so far reported

New High-Nuclearity Carbonyl and Carbonyl-Substituted Rhodium Clusters and Their Relationships with Polyicosahedral Carbonyl-Substituted Palladium- and Gold-Thiolates

A reinvestigation of the synthesis of [H_5–<i>n</i>Rh₁₃(CO)₂₄]^<i>n</i>− (<i>n</i> = 2, 3) led to isolation of a series of Rh₁₉, Rh₂₆, and Rh₃₃ high-nuclearity carbonyl and carbonyl-substituted rhodium clusters. The [Rh₁₉(CO)₃₁]^5– (<b>1</b>) is electronically equivalent with [Pt₁₉(CO)₂₂]^4–, but poor crystal diffraction data of all salts obtained to date have prevented its geometrical analysis. The structures of Rh₂₆(CO)₂₉(CH₃CN)₁₁ (<b>2</b>) as <b>2</b>·2CH₃CN and [Rh₃₃(CO)₄₇]^5– (<b>3</b>) as [NEt₄]₅[<b>3</b>]·Me₂CO were determined from complete X-ray diffraction determinations. The latter two species adopt polyicosahedral metal frameworks, and notably, [Rh₃₃(CO)₄₇]^5– represents the molecular group 9 metal carbonyl cluster of highest nuclearity so far reported

Bonjean Louis-Bernard

Entrée de dictionnaireDictionnaire historique des juristes français XIIe-XXe siècle

Synthesis, Structure, and Electrochemistry of the Ni–Au Carbonyl Cluster [Ni₁₂Au(CO)₂₄]^3– and Its Relation to [Ni₃₂Au₆(CO)₄₄]^6–

A detailed study of the reaction between [Ni₆(CO)₁₂]^2– and [AuCl₄]⁻ afforded the isolation of the new Ni–Au cluster [Ni₁₂Au­(CO)₂₄]^3– as well as identifying an improved synthesis for the previously reported [Ni₃₂Au₆(CO)₄₄]^6–. The new [Ni₁₂Au­(CO)₂₄]^3– cluster is composed by two [Ni₆(CO)₁₂]^2– moieties coordinated to a central Au­(I) ion, as determined by X-ray diffraction. It is noteworthy that the two [Ni₆(CO)₁₂]^2– fragments display different geometries, i.e., trigonal antiprismatic (distorted octahedral) and distorted trigonal prismatic (monocapped square pyramidal). The chemical reactivity of these clusters and their electrochemical behavior have been studied. [Ni₁₂Au­(CO)₂₄]^3– is irreversibly transformed, upon electrochemical reduction, into Au(0) and [Ni₆(CO)₁₂]^2–, followed by the reversible reduction of the latter homometallic cluster. Conversely, [Ni₃₂Au₆(CO)₄₄]^6– displays five reductions, with apparent features of reversibility, confirming the ability of larger metal carbonyl clusters to reversibly accept and release electrons

Octahedral Co-Carbide Carbonyl Clusters Decorated by [AuPPh₃]⁺ Fragments: Synthesis, Structural Isomerism, and Aurophilic Interactions of Co₆C(CO)₁₂(AuPPh₃)₄

The Co₆C­(CO)₁₂(AuPPh₃)₄ carbide carbonyl cluster was obtained from the reaction of [Co₆C­(CO)₁₅]^2– with Au­(PPh₃)­Cl. This new species was investigated by variable-temperature ³¹P NMR spectroscopy, X-ray crystallography, and density functional theory methods. Three different solvates were characterized in the solid state, namely, Co₆C­(CO)₁₂(AuPPh₃)₄ (<b>I</b>), Co₆C­(CO)₁₂(AuPPh₃)₄·THF (<b>II</b>), and Co₆C­(CO)₁₂(AuPPh₃)₄·4THF (<b>III</b>), where THF = tetrahydrofuran. These are not merely different solvates of the same neutral cluster, but they contain three different isomers of Co₆C­(CO)₁₂(AuPPh₃)₄. The three isomers <b>I–III</b> possess the same octahedral [Co₆C­(CO)₁₂]^4– carbido–carbonyl core differently decorated by four [AuPPh₃]⁺ fragments and showing a different Au­(I)···Au­(I) connectivity. Theoretical investigations suggest that the formation in the solid state of the three isomers during crystallization is governed by packing and van der Waals forces, as well as aurophilic and weak π–π and π–H interactions. In addition, the closely related cluster Co₆C­(CO)₁₂(PPh₃)­(AuPPh₃)₂ was obtained from the reaction of [Co₈C­(CO)₁₈]^2– with Au­(PPh₃)­Cl, and two of its solvates were crystallographically characterized, namely, Co₆C­(CO)₁₂(PPh₃)­(AuPPh₃)₂·toluene (<b>IV</b>) and Co₆C­(CO)₁₂(PPh₃)­(AuPPh₃)₂·0.5toluene (<b>V</b>). A significant, even if minor, effect of the cocrystallized solvent molecules on the structure of the cluster was observed also in this case

The Redox Chemistry of [Co₆C(CO)₁₅]^2–: A Synthetic Route to New Co-Carbide Carbonyl Clusters

The oxidation and reduction reactions of [Co₆C­(CO)₁₅]^2– have been studied in detail, leading to the isolation of several new Co-carbide carbonyl clusters. Thus, [Co₆C­(CO)₁₅]^2– reacts in tetrahydrofuran (THF) with oxidants such as HBF₄·Et₂O and [Cp₂Fe]­[PF₆], resulting first in the formation of the previously reported [Co₆C­(CO)₁₄]⁻; then, in CH₂Cl₂, the new dicarbide [Co₁₁C₂(CO)₂₃]^2– is formed. The latter may be further oxidized, yielding the isostructural monoanion [Co₁₁C₂(CO)₂₃]⁻, whereas its reduction with (cyclopentadienyl)₂Co affords the unstable trianion [Co₁₁C₂(CO)₂₃]^3–, which decomposes during workup. Oxidation of [Co₆C­(CO)₁₅]^2– in CH₃CN with [C₇H₇]­[BF₄] affords the same major products, and besides, the new monoacetylide [Co₁₀(C₂)­(CO)₂₁]^2– was obtained as side-product. Conversely, the reduction of [Co₆C­(CO)₁₅]^2– in THF with increasing amounts of Na/naphthalene results in the following species: [Co₆C­(CO)₁₃]^2–, [Co₁₁(C₂)­(CO)₂₂]^3–, [Co₇C­(CO)₁₅]^3–, [Co₈C­(CO)₁₇]^4–, [Co₆C­(CO)₁₂]^3–, and [Co­(CO)₄]⁻. The new [Co₁₁C₂(CO)₂₃]⁻, [Co₁₁C₂(CO)₂₃]^2–, [Co₁₀(C₂)­(CO)₂₁]^2–, [Co₈C­(CO)₁₇]^4–, [Co₆C­(CO)₁₂]^3–, and [Co₇C­(CO)₁₅]^3– clusters were structurally characterized. Moreover, the paramagnetic species [Co₁₁C₂(CO)₂₃]^2– and [Co₆C­(CO)₁₂]^3– were investigated by means of electron paramagnetic resonance spectroscopy. Finally, electrochemical studies were performed on [Co₁₁C₂(CO)₂₃]^<i>n</i>− (<i>n</i> = 1–3)