Oxidative addition of 2-formyl-furan and related pyrrole and thiophene compounds at triosmium clusters

The bridging acyl complexes [Os₃H(μ-COC₄H₃X)(CO)₁₀] (X = NH, O, or S) have been prepared by oxidative addition of the 2-formyl derivatives of pyrrole, furan, or thiophene (C₄H₃XCHO) at [Os₃(CO)₁₀(MeCN)₂] with cleavage of the aldehydic CH bonds. On heating double decarbonylation of the acyl complexes occurs, to afford high yields of the compounds [Os₃H₂(CO)₉(μ₃-C₄H₂X)], reported previously for X = NH or O. For X = NH, two isomers with this formulation were characterised by ¹H NMR and IR data; the one containing the μ₃-2,3-C₄H₃N ligand isomerises to one containing μ₃-1,2-C₄H₃N. The direct reaction of pyrrole with [Os₃(CO)₁₂] has been re-examined at lower temperatures than before, and observed to give new products, including [Os₃H(CO)₁₀(C₄H₄N)], which contains a bridging non-aromatic tautomeric form of pyrrole. The ability of Os₃ clusters to stabilize non-aromatic tautomers of aromatic ligands is discussed.     

The reaction of H2Os5(CO)15 with nucleophilic reagents

The reaction of H₂Os₅(CO)₁₅ with nucleophiles Y leads either to deprotonation (Y = OH^? or Me^?) or addition (Y = I^?, P(OMe)₃, or CO). The geometrical consequences of these reactions are discussed.     

Activation of the carbon—nitrogen triple bond of benzonitrile in the presence of triosmium clusters and acetic acid. Crystal structure of (μ-H)Os3(CO)10(μ-O2CCH3), a product of the reaction

The activation of the CN triple bond of benzonitrile in the presence of acetic acid and of Os₃(CO)₁₂ or H₂Os₃(CO)₁₀ has been studied. When Os₃(CO)₁₂ reacts with PhCN and acetic acid in refluxing n-octane the three main products are (μ-H)Os₃(CO)₁₀(μ-O₂CCH₃) (I), (μ-H)Os₃(CO)₁₀(μ-NCHPh) (II) and (μ-H)Os₃(CO)₁₀(μ-NHCH₂Ph) (III); II and III are analogues of (μ-H)Ru₃(CO)₁₀(μ-NCHPh) and (μ-H)Ru₃(CO)₁₀(μ-NHCH₂Ph) obtained from PhCN, Ru₃(CO)₁₂ or H₄Ru₄(CO)]₁₂, and acetic acid. In contrast to the reaction with ruthenium clusters, Os₃(CO)₁₂ and H₂Os₃(CO)₁₀ also give the adduct Os₃(CO)₁₀(CH₃COOH) (I). The structure of I has been fully elucidated by X-ray diffraction. Crystals of I are monoclinic, space group P2₁/m, with unit cell parameters a 7.858(6), b 12.542(8), c 9.867(6) Å, β 109.92(2)°, Z = 2. In I an edge of the triangular cluster of osmium atoms is doubly bridged by a hydride and an acetate ligand. Ten terminal carbonyl groups are bonded to the metal atoms.     

The Pyrolysis of Isonitrile Substituted Derivatives of Triosmium Dodecacarbonyl

The pyrolysis of the isonitrile substituted complexes Os₃(CO)_12?x(CNR)x (R = Bu^t, x = 1,2) in refluxing octane has been studied. From these pyrolysis reactions and from the reaction of Os₃(CO)₁₂ with Bu^tNC in refluxing octane the series of hexanuclear complexes Os₆(CO)_18?x(CNBu^t)_x (x = 1?5) has been isolated. The pyrolysis of Os₃(CO)₁₁(CNBuⁿ) also leads to the formation of higher nuclearity clusters and evidence is presented that one product of the reaction is Os₆(CO)₁₇(CNBuⁿ)₂. Possible structures for these isonitrile substituted hexanuclear complexes are discussed in the light of the known structures of Os₆(CO)₁₆(CNBu^t)₂ and Os₆(CO)₁₈(CNC₆H₄Me)₂.     

Calorimetric study of adduct formation at 300 K between H2Os3(CO)10 and Lewis bases

The enthalpies of the reactions H₂Os₃(CO)₁₀(I)+L=H₂Os₃(CO)₁₀L(II),L=PR₃, P(OR)₃, in chloroform were determined by means of microcalorimetry. Satisfactory agreement was found between the basicity parameters and the measured reaction enthalpies. As concerns the kinetics, qualitative correlation of a thermokinetics parameter with the steric factor of the ligand was observed.     

Syntheses of some mixed AuOs and PtOs clusters and the X-ray structure of [Os4H2(CO)12(AuPPh3)2]

Some reactions of [Os₄H₃(CO)₁₂AuPR₃] (R = Et, Ph) resulting in the formation of [Os₄H₂(CO)₁₂(AuPR₃)₂] are presented. A single-crystal X-ray structure of [Os₄H₂(CO)₁₂(AuPPh₃)₂] is reported and reveals a novel Ph₃PAuAuPPh₃ unit asymmetrically bridging one edge of an Os₄ tetrahedron, the first example of a mixed gold-metal carbonyl cluster with an AuAu bond.     

Triosmium clusters containing diphosphine and triphosphine ligands

The isomeric butadiene compounds 1,1- and 1,2-[Os₃(C₄H₆)(CO)₁₀] and the acetonitrile compound 1,2-[Os₃(CO)₁₀(MeCN)₂] react with the diphosphines Ph₂P(CH₂)_nPPh₂ (n = 2, 3 or 4) to give separable isomers of [Os₃(CO)₁₀(diphosphine)] in which the diphosphine is either bridging or chelating, whereas dppm (n = 1) gives only the 1,2-isomer. The mono-acetonitrile compound [Os₃-(CO)₁₁(MeCN)] reacts to give two series of compounds: [Os₃(CO)₁₁(diphosphine)], containing one coordinated and one free phosphorus atom, and [Os₆(CO)₂₂(diphosphine)] with two Os₃(CO)₁₁ groups bridged by the diphosphine. The triphosphine, Ph₂PCH₂CH₂PPhCH₂CH₂PPh₂ (triphos), reacts similarly to give two separable isomers of [Os₃(CO)₁₁(triphos)] and two inseparable isomers of [Os₆(CO)₂₂(triphos)]. Whereas [Os₃(CO)₁₁(dppm)] readily undergoes decarbonylation to give 1,2-[Os₃(CO)₁₀(dppm)], other compounds of the type [Os₃(CO)₁₁(diphosphine)] are not decarbonylated under the same conditions, but react with Me₃NO to give the 1,2-but not the 1,1-isomers of [Os₃(CO)₁₀(diphosphine)].     

Cage Opening of a Carborane Ligand by Metal Cluster Complexes

The reaction of Os₃(CO)₁₀(NCMe)₂ with closo‐o‐C₂B₁₀H₁₀ has yielded two interconvertible isomers Os₃(CO)₉(μ₃‐4,5,9‐C₂B₁₀H₈)(μ‐H)₂ ( 1 a ) and Os₃(CO)₉(μ₃‐3,4,8‐C₂B₁₀H₈)(μ‐H)₂ ( 1 b ) formed by the loss of the two NCMe ligands and one CO ligand from the Os₃ cluster. Two BH bonds of the o‐C₂B₁₀H₁₀ were activated in its addition to the osmium cluster. A second triosmium cluster was added to the 1 a / 1 b mixture to yield the complex Os₃(CO)₉(μ‐H)₂(μ₃‐4,5,9‐μ₃‐7,11,12‐C₂B₁₀H₇)Os₃(CO)₉(μ‐H)₃ ( 2 ) that contains two triosmium triangles attached to the same carborane cage. When heated, 2 was transformed to the complex Os₃(CO)₉(μ‐H)(μ₃‐3,4,8‐μ₃‐7,11,12‐C₂B₁₀H₈)Os₃(CO)₉(μ‐H) ( 3 ) by a novel opening of the carborane cage with loss of H₂.     

Triosmium clusters with μ3-AsR group as a building block for hexaosmium-arsenic cluster synthesis. Synthesis and characterisation of [(CO)11Os3As(Os3(CO)9H3)] and [(CO)9H3Os3As(Os3(CO)9H3)]. Crystal structure of [(CO)11Os3As(Os3(CO)9H3)]

Reaction of the activated cluster [Os₃(CO)₁₁(CNMe)] with primary arsine AsH₃ forms the arsinidine compound [H₂Os₃(μ₃-AsH)(CO)₁₁] (1a, 1b), which on further reaction with [Os₃(CO)₁₁(NCMe)] yields [(CO)₁₁Os₃As(Os₃(CO)₉H₃)] (2) and with [H₂Os₃(CO)₁₀] yields [H₂Os₃(CO)₉As(Os₃(CO)₉H₂)] (3). Similarly [H₂Os₃(CO)₁₀] reacts with AsH₃ at room temperature to afford 3 in good yields. Thermal degradation and rearrangement of 2 gives the pentanuclear cluster [H₂Os₅(CO)₁₇AsH] (4).     

Photoassisted synthesis of mixed-metal clusters: [PPN] [CoOs3(CO)13], H2RuOs3(CO)13, and H2FeOs3(CO)13

The utility of photochemical methods for the directed synthesis of mixed-metal metal clusters has been explored. The 366 nm photolysis of a solution containing [PPN] [Co(CO)₄] (PPN = (Ph₃P)₂N⁺) and Os₃(CO)₁₂ gives the new cluster [PPN][CoOs₃(CO)₁₃] in 33% yield. Irradiation of a mixture of Fe(CO)₅ and H₂Os₃(CO)₁₀ yields H₂FeOs₃(CO)₁₃ in 95% yield, and photolysis of Ru₃(CO)₁₂ in the presence of H₂Os₃(CO)₁₀ gives the new cluster H₂RuOs₃(CO)₁₃. Details of these syntheses, their probable mechanisms, and the characterization of the new compounds are discussed.     

Products from the reaction of M3(CO)12 (M = Ru or Os) with water

Reaction of the carbonyl Ru₃(CO)₁₂ with water leads to the formation of polynuclear hydrides α-H₄Ru₄(CO)₁₂, α-H₂Ru₄(CO)₁₃; the corresponding reaction with Os₃(CO)₁₂ yields the complexes (H)(OH)Os₃(CO)₁₀, H₂Os₄(CO)₁₃, H₄Os₄(CO)₁₂, H₂Os₅(CO)₁₆, H₂Os₅(CO)₁₅, H₂Os₆(CO)₁₈ and H₂Os₇(CO)₁₉C.     

Negative ion mass spectra of Os3(CO)12X2 and Os3(CO)10X2 complexes (X = Br,I)

The negative-ion mass spectra at 70 eV of the compounds Os₃(CO)₁₂X₂ and Os₃(CO)₁₀X₂ (X =Br, I) are reported. Negative molecular ions are absent and only Os₃-containing fragments due to the loss of carbonyl groups are observed. [M  CO]^? is the base peak in the spectrum of Os₃(CO)₁₀I₂ and has a very high abundance in that of Os₃(CO)₁₀Br₂, whereas it is very weak in the spectra of Os₃(CO)₁₂X₂, where [M  3 CO]^? is the base peak. This change in the ionic intensities is related to the closed and open structure of the Os₃ unit in Os₃(CO)₁₀X₂ and Os₃(CO)₁₂X₂ respectively.     

Syntheses of double- and triple-decker clusters of osmium and cobalt metals linked by cyclotetradeca-1,8-diyne ligands

Photoirradiation of Os₃(CO)₁₀(C₁₄H₂₀) (1) in n-hexane produces the double-decker cluster [Os₃(CO)₉(C₂₈H₄₀)] [Os₃(CO)₁₀] (7), which can also be prepared from the reaction of Os₃(CO)₉(C₂₈H₄₀) (2) and Os₃(CO)₁₀(NCMe)₂. Further reaction of 7 with Os₃(CO)₁₀(NCMe)₂ affords the triple-decker cluster [Os₃(CO)₉(C₂₈H₄₀)][Os₃(CO)₁₀]₂ (8). The bis(diyne) complex Os₃(CO)₈(C₁₄H₂₀)₂ (3) reacts with Os₃(CO)₁₀(NCMe)₂ sequentially to yield the double-decker cluster [Os₃(CO)₈(C₁₄H₂₀)₂][Os₃(CO)₁₀] (4) and the triple-decker cluster [Os₃(CO)₈(C₁₄H₂₀)₂][Os₃(CO)₁₀]₂ (5). Treatment of 3 with Co₂(CO)₈ at room temperature leads to the mixed-metal triple-decker cluster [Os₃(CO)₈(C₁₄H₂₀)₂][Co₂(CO)₆]₂ (6), while the reaction of 2 and Co₂(CO)₈ produces [Os₃(CO)₉(C₂₈H₄₀)][Co₂(CO)₆]₂ (9) and [Os₂(CO)₆(C₂₈H₄₀)][Co₂(CO)₆]₂ (10). Compound 10, which involves cluster degradation from Os₃ to Os₂, has been structurally characterized by an X-ray diffraction study.     

Products of the reaction of H2Os3(CO)10 with cyclonona-1,2diene

Treatment of H₂Os₃(CO)₁₀ with cyclonona-l,2-diene produced HOs₃(CO)₉C₉H₁₃ and Os₂(CO)₆(C₉H₄)₂. Single crystal X ray analysis has shown that the latter is not isostructural with Fe₂(CO)₆(C₉H₁₄)₂.     

Triosmium carbonyl clusters of sulfur and oxygen mixed donor ligands

The reaction of the lightly stablized cluster [Os₃(CO)₁₀(NCMe)₂] with thiosalicylic acid affords two products [{Os₃(CO)₁₀(µ-H}]₂SC₆H₄CO₂],1 and [Os₃H(CO)10SC₆,H₄C(O)OOs₃H(CO)₁₁],2. Complex 2 undergoes CO dissociation to give1 or fragmentation to give [Os₃H(CO)10SC₆H₄ COOH], 3 in solution. Reaction of phthalic acid and [ Os₃(CO)₁₀(NCMc)₂] gives two products [{Os₃(CO)₁₀(µ-H)}₂O₂CC₆H₄CO₂], 4 and [Os₃H(CO)₁₀O₂CC₆ H₄C(O)OOs₃H(CO)₁₁], 5. 5 also undergoes CO dissociation to give4, but no such conversion is observed in the preparation of [{Os₃(CO)₁₀(µH)}₂ (SC₆H₄S)],6 from the reaction betweeno-dithiobenzene and [Os₃(CO)₁₀ (NCMe)₂]. Unlike thiosalicylic acid, treatment of [Os₃(CO)₁₀(NCMe)₂] with 1 equivalent 2,2'-dithiosalicylaldehyde in dichloromethane produces the compounds [Os₃(CO)₁₀(SC₆H₄CHO)₂],7 and [Os₃(CO)₁₀µ-H)(SC₆H₄CHO)].8 in moderate yields which are stable in both the solid state and solution. The mechanism for the formation of1-5 is also proposed. All the clusters1-8 have been fully characterized by conventional spectroscopic methods and the structures of1, 3, 4, 7, and8 have been established by X-ray, crystallography.     

Poly-(1,4-naphthalene) as support of catalytically active osmium clusters for olefin isomerisation

[H₂Os₃(CO)₉-(PPh₂)_x-C10H_6−x]_n (x = 2–3, n≈55) was synthesized and shown to have significantly higher catalytic activity for the isomerisation of 1-hexene than H₂Os₃(CO)₉-xxx (xxx = polystyryl chain) or free H₂Os₃(CO)₁₀. It can be considered as a model system for comparing its ‘linear’ or rather non-coiled structure with polymer-supported catalysts with alkane backbones.     

Volcano relationships in metal cluster catalysis: An infrared spectroscopic monitor of site character

Active osmium cluster catalysts (derived from Os₃(CO)₁₂, H₂Os₃(CO)₁₀, H₄Os₄(CO)₁₂, Os₆(CO)₁₈ and H₂Os₁₀C(CO)₂₄ supported on silica, alumina, titania, and ceria) contain, in their infrared spectra, a band in the region 1930–1985 cm⁻¹ that is characteristic of the cluster/support combination. The activities of these catalysts for reactions of hydrogen with ethene, carbon monoxide, carbon dioxide, and ethane, relate to their characteristic CO stretching frequencies, giving ‘volcano’ curves. Evidence from ethene hydrogenation kinetics confirms that the characteristic CO-frequency is a monitor of strength of adsorption at the catalytically active site. Dedicated to Professor Pál Tétényi on the occasion of his 70th birthday     

The preparation,characterisation and some reactions of Os3(CO)9(μ2-H)(μ3-SR) (R  Me or Et)

The complex Os₃(CO)₉(μ₂-H)₂(μ₃-S) reacts with KOH/MeOH to produce the anionic complex [Os₃(CO)₉(μ₂-H)(μ₃-S)^?, which reacts in turn with RO⁺ (R = Me, Et) to form HOs₃(CO)₉SR. This complex is especially reactive towards ligands L (L = C₂H₄, CO, PR₃ and MeCN) to generate complexes of the type Os₃(CO)₉(μ₂-H)(μ₂-SR)(L). At 125°C the complex Os₃(CO)₉(μ₂-H)(μ₂-SR)(C₂H₄) (in the presence of C₂H₄) ejects RH and CO to form Os₃(CO)₈(μ₂-H)?(μ₃-S)(CHCH₂). The structures of the new complexes are described and the probable reaction pathways discussed.     

The photochemical and thermal reactions of a triosmium cluster carrying a γ-pyrone ligand with alkynes

The reaction of the cluster Os₃(CO)₁₀(μ-H)(μ-γ-C₅H₃O₂) (1) with a number of alkynes under thermal or visible light irradiation conditions, afforded in most cases the dinuclear complexes Os₂(CO)₆(μ-γ-C₅H₃O₂)(μ-LH) (L=PhCCPh, ^tBuCCH, ^tBuCCMe or EtCCEt) (2) or the trinuclear chain complexes Os₃(CO)₉(μ-H)(μ-γ-C₅H₃O₂)(μ-RCCHC₆H₄) (R=H, Ph) (3). In the case of PhCCPh, a new isomer of Os₃(CO)₈(PhCCPh)₂, viz., Os₃(CO)₈(μ-PhCCPh)(μ-PhCCHC₆H₄) (7) has been isolated and characterised.     

Carbonylate anion [(μ-H)Os<Subscript>3</Subscript>(CO)<Subscript>10</Subscript>L]<Superscript>−</Superscript> as a precursor in the synthesis of heterometallic Os<Subscript>3</Subscript>M clusters

A new method for the synthesis of heterometallic clusters Os₃M is developed. The reactions of hydridocarbonyl cluster (μ-H)₂Os₃(CO)₁₀ (I) with binuclear carbonyls Co₂(CO)₈ and Fe₂(CO)₉ in the presence of 1,4-diazabicyclo[2.2.2]octane (Dabco) afford anionic complexes [Os₃Co(CO)₁₃]⁻ (II) and [HOs₃Fe(CO)₁₃] (III) with the counterion N₂C₆H₁₃⁺. Similar reactions with halide complexes [MCp*Cl₂]₂ (M = Rh and Ir) yield neutral complexes [Os₃M(CO)₁₀(μ-H)(μ-Cl)] (M = Rh(IV) and Ir(V)). The reactions occur rapidly at room temperature with high yields. The newly obtained clusters are characterized by the data of IR and ¹H NMR spectroscopy, elemental analysis, and X-ray diffraction analysis.