Redox Properties of Trinuclear Osmium Carbonylhydride Clusters with Unsaturated Ligands

Schemes of redox transformations were proposed for osmium carbonylhydride clusters: trinuclear (-H)Os₃(-CR = CHR')(CO)_{1 0} (R = R' = H, Ph; R = H, R' = Ph), (-H)₂Os₃(₃-L)(CO)₉ (L = C = CHPh, CHCPh), tetranuclear CpMnOs₃ (-CH = CHPh)(-H)(-CO)(CO)_{1 1}, and trinuclear Os₃(₃-C = CHPh)(CO)₉. Two-electron reduction of the trinuclear clusters results in elimination of the unsaturated ligand with preservation of the metal framework.     

Synthesis and the crystal structure of the triosmium cluster with the μ-dehydrobenzene ligand,Os3(μ-H)2(CO)7(μ-C6H4){μ3-Ph2PCH2P(C6H4)Ph}

The Os₃(-H)₂(CO)₇(-C₆H₄){₃-Ph₂PCH₂P(C₆H₄)Ph} complex, which was isolated from the products of thermolysis of Os₃(CO)₁₀(-dppm) (dppm is Ph₂PCH₂PPh₂) in toluene, was characterized by X-ray diffraction analysis. Protonation of the resulting complex with trifluoroacetic acid afforded the cationic complex [Os₃(-H)₃(CO)₇(-C₆H₄){₃-Ph₂PCH₂P(C₆H₄)Ph}]⁺.     

Synthesis of Osmium–Palladium Mixed-Metal Clusters with 2-(diphenylphosphino)Pyridine as a Bridging Ligand

Reaction of the pentanuclear cluster [Os₅C(CO)₁₄(PPh₂py)] in CH₂Cl₂ with 1.2 equivalents of Pd(MeCN)₂Cl₂ led to the high-yield synthesis of the new osmium–palladium carbonyl cluster [Os₅PdC(CO)₁₄(-Cl)Cl(-PPh₂py)] 1. Cluster 1 is thermally unstable and converts slowly in refluxing CHCl₃ to [{Os₄C(CO)₁₀(-Cl)(-PPh₂py)}(₄-Pd){Os₄C(CO)₁₂(-Cl)}] 2 and [{Os₄ (₅-C)(CO)₁₂(-Cl)}₂(-Pd₂Cl₂)] 3 in 4% and 67% yield, respectively. Reaction of 1 with iodine gave [Os₅PdC(CO)₁₄(-Cl)I(-PPh₂py)] 4 and [{Os₄(₅-C)(CO)₁₂(-I)}₂(-Pd₂I₂)] 5 in moderate yields. All complexes have been characterized by spectroscopic and single-crystal X-ray diffraction analysis.     

Stereospecific coordination ofl-hydroxyproline esters with triosmium clusters

The reactions of cluster (-H)Os₃(CO)₁₀(-OH) with ethyl and isopropyl esters ofl-oxyproline were studied. In the presence of Me₃NO intermediate complex (-H)Os₃(CO)₉(-OH)L (L — isopropyl ester ofl-oxyproline) is formed, which slowly converts to the more stable cluster (-H)Os₃(CO)₉ . Cluster complexes containing chelate-bridging heterocycles were also obtained by heating (-H)Os₃(CO)₁₀(-OH) with esters ofl-oxyproline. In both cases, only one of the possible diastereomeric complexes (-H)Os₃(CO)₉ (R = Et, Prⁱ) is formed, which indicates that the reactions are stereospecific. Based on analysis of Dreiding's models, an attempt to determine the absolute configuration of the obtained clusters was made.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2021–2025, October, 1995.     

The reaction of [PPN][(μ2-H)Os3(CO)10(μ2-CO)] with EPh3 (E=P or As) to form the intermediate [PPN][Os3(CO)9(ν2-CHO)(EPh3)]

The anion, [(₂-H)Os₃(CO)₁₀(₂-CO)]^–, reacts with the donor ligand EPh₃ (E=P or As) to produce, as an intermediate in the reaction to the substituted anion [(₂-H)Os₃(CO)₉(₂-CO)(EPh₃)]^–, a moderately stable formyl derivative which we tentatively formulate as [Os₃(CO)₉(²-CHO)(EPh₃)]^–.     

Reactivity of the Unsaturated Triosmium Cluster [Os3(CO)8{Ph2PCH2P(Ph)C6H4}(μ-H)] with Thiols

The reaction of the unsaturated cluster [(-H)Os₃(CO)₈{Ph₂PCH₂P(Ph)C₆H₄}] 2 with C₂H₅SH, CH₃CH(CH₃)SH and C₆H₅SH are reported. The reaction of 2 with C₂H₅SH yields the new complexes [Os₃(CO)₈(-SC₂H₅)(¹-SC₂H₅){Ph₂PCH₂P(Ph)C₆H₄}(-H)] 9 and [Os₃(CO)₈)(SC₂H₅)(Ph₂PCH₂P)(Ph)C₆H₄}] 8 in 24 and 57% yields respectively and the known compound [(Os₃(CO)₈)(-SC₂H₅)(-dppm)(-H)] 7 in 5% yield. Compound 9, which exists as two isomers in solution, converts into 8 almost quantitatively in solution at 25°C and more rapidly in refluxing hexane. Compound8 reacts with H₂ at 110°C to give 7 in high yield (86%). Treatment of 2 with propane-2-thiol yields [Os₃(CO)₈{-SCH(CH₃)CH₃}{Ph₂PCH₂P(Ph)C₆H₄}] 10 and [(Os₃(CO)₈{-SCH(CH₃)CH₃}{¹-SCH(CH₃)CH₃}{Ph₂PCH₂P(Ph)C₆H₄}(-H)] 11 in 75 and 3% yields respectively while with C₆H₅SH, [(Os₃(CO)₈(-SC₆H₅)(-dppm)(-H)] 6 is obtained as the only product in 75% yield. In both 8 and 10, the thiolato ligand bridges the Os–Os edge which is also bridged by the metallated phenyl group. The new compounds have been characterized by elemental analyses and spectroscopic methods (IR, ¹H and ³¹P NMR). The molecular structures of 7, 8, 9 and 10 are reported as determined by X-ray diffraction studies.     

Synthesis and protonation of an OS3(μ-H)(CO)10(μ-σ,η2-C≡CCMe2OMe) cluster

Triosmium cluster Os₃(-H)(CO)₁₀(--²-CCC Me₂OMe) (1) was obtained by treating OS₃(-H)(-Cl)(CO)₁₀ with LiCCCMe₂OMe. The reaction of cluster1 with HBF₄ · Et₂O at –60 °C leads to the cationic complex [Os₃(-H)(CO)₁₀(-,,²-C=C=C Me₂)]⁺BF₄ ^– (2) with an allenylidene ligand. The^s1H and¹³C NMR spectra of complex2 reveal the temperature dependence caused by migration of hydrocarbon and carbonyl ligands. Thermodynamic parameters were obtained for be exchange process of the allenylidene ligand.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp, 2990–2992, December, 1996.     

Reactivity and flexibility in platinum metal clusters

The synthesis, structural properties, and fluxional behaviour of platinum-triosmium and platinum-triruthenium clusters derived from Os₃Pt(-H)₂ (CO)₁₀(PR₃) and Ru₃Pt(-H)(-CC ^t Bu)(CO)₉ (dppe) and related species are described.     

Triiron and Triruthenium Carbonyl Clusters Bearing Bridging Long Chain Diphosphine and Capping Chalcogenido Ligands

Treatment of Ru₃(CO)₁₂ with dpphSe₂ (dpph = 1,6-bis(diphenylphosphino)hexane) in refluxing toluene in the presence of Me₃NO afforded two new compounds, Ru₃(CO)₇(-CO)(₃-Se)(-dpph) (1) and Ru₃(CO)₇(₃-Se)₂(-dpph) (2). A similar reaction of Ru₃(CO)₁₂ with dpppeSe₂ (dpppe = 1,5-bis(diphenylphosphino)pentane) gave exclusively Ru₃(CO)₇(₃-Se)₂(-dpppe) (3). Treatment of Ru₃(CO)₁₂ with dpphS₂ and dpppeS₂ at 110°C in the presence of Me₃NO afforded Ru₃(CO)₇(₃-S)₂(-dpph) (4) and Ru₃(CO)₇(₃-S)₂(-dpppe) (5), respectively. Reactions of Fe₃(CO)₁₂ with dpphSe₂ and dpppeSe₂, under identical conditions, afforded Fe₃(CO)₇(₃-Se)₂(-dpph) (6) and Fe₃(CO)₇(₃-Se)₂(-dpppe) (7), respectively. Compounds 1–7 were characterized spectroscopically and the molecular structures of compounds 1–4 were determined by single crystal X-ray crystallography. The core of 1 contains an equilateral triangle of ruthenium atoms with one capping selenium, one bridging dpph, one doubly bridging carbonyl and seven terminal carbonyl ligands. Complexes 2–4 have a square-pyramidal structure with two metal and two chalcogenide atoms alternating in the basal plane and the third metal atom at the apex of the pyramid, and belong to the family of well-known nido clusters with seven skeletal electron pairs.     

Reactions of triosmium clusters Os3(CO)11(MeCN) and (μ-H)Os3(CO)10(μ-OH) withL-α-serine ethyl ester and ethanolamine

A series of novel chiral complexes with ,¹and ,² coordination of organic ligands were prepared by reactions of Os₃(CO)₁₁(MeCN) and (-H)Os₃(CO)₁₀(-OH) withL--serine ethyl ester and ethanolamine. The diastereomeric cluster complexes with serine ligands were separated by crystallization or chromatography. The structures of the compounds obtained were confirmed by¹H NMR and IR spectroscopy, mass-spectrometry, elemental analysis, and X-ray diffraction analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 525–530, March, 1994.     

Protonation of Os3(μ-H)(CO)9(μ3-σ,η2-C≡C-R) clusters (R=CMe2OH,C(Me)=CH2)

Protonation of triosmium clusters Os₃(-H)(CO)₉(₃-,²-CC-R) (R=CMe₂OH, C(Me)=CH₂) affords a cationic complex containing a six-electron propargyl ligand which has been detected for the first time.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1144–1145, June, 1993.     

Synthesis and structure of isomeric (μ-H)Os<Subscript>3</Subscript>(μ,η<Superscript>2</Superscript>-(O,N)-6,6-clusters of dimethyl-2-methylene-bicyclo[3.1.1]heptan-3-one oxime)(CO)<Subscript>10</Subscript>. Crystal structure of one of the isomers

(-H)₂Os₃(,²-(O,N)-6,6-dimethyl-2-methylene-bicyclo[3.1.1]heptan-3-one oxime)(CO)₁₀ isomeric clusters have been synthesized, separated chromatographically, and investigated by IR and NMR spectroscopy. The crystal structure of one of the isomers has been determined (Enraf-Nonius CAD-4 automatic diffractometer, graphite monochromator, MoK , /2 scan mode at a variable rate). The crystals are monoclinic with unit cell parameters: a = 9.125(2) , b = 13.629(3) , c = 10.098(2) , = 90.16(3)°, V = 1255.8(4) ³, space group P2₁, Z = 2, composition (-H)₂Os₃(,²-ONC₁₀H₁₄)(CO)₁₀, d _calc = 2.647 g/cm³. The structure is molecular; the planes of the Os₃ triangle and the OsONOs bridging ligand are linked according to the butterfly pattern with an angle of 102.0° between the planes. The Os-Os bonds vary within the range 2.840 –2.882 .Original Russian Text Copyright © 2004 by V. A. Maksakov, N. V. Pervukhina, S. V. Korenev, N. V. Podberezskaya, V. P. Kirin, and A. V. TkachevTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 4, pp. 698–705, July–August, 2004.This revised version was published online in April 2005 with a corrected cover date.     

Addition of HCl to a Cluster-Bound Vinylidene Ligand: Preparation and Structure of Ru5(μ3-SMe)(μ3-CMe)(μ-Cl)(μ-SMe)(μ-PPh2)2(CO)9·PhMe

Addition of aqueous HCl to Ru₅( ₃-C=CH₂)(-SMe)₂(-PPh₂)₂(CO)₁₀ afforded the structurally characterized carbyne complex Ru₅( ₃-SMe)( ₃-CMe)(-Cl)(-SMe)(-PPh₂)₂(CO)₉, formed by addition of H to the vinylidene ligand; a Cl atom bridges an Ru–Ru bond.     

Cp*MCpMoFe(CO)7(μ3-S), Cp*MoCpMFe(CO)7(μ3-S) (M = W,Mo) and Cp*WCp*MoFe(CO)7(μ3-S). Crystal structure of CpMoCp*WFe(CO)7(μ3-S)

CpMoFeCo(CO)₇(₃-S) reacts with Cp^*M(CO)₃Cl or CpM(CO)₃Cl (M=W, Mo) to gave the mixed-metal clusters Cp^*WCpMoFe(CO)₇(₃-S) (1), Cp^*MoCpMoFe(CO)₇(₃-S) (2), CpWCp^*MoFe(CO)₇(₃-S) (3), CpMoCp^*MoFe(CO)₇(₃-S) (4) and Cp^*WCp^*MoFe(CO)₇(₃-S) (5). The title clusters have been characterized by i.r., ¹H/¹³C-n.m.r. spectroscopy and their compositions have been confirmed by elemental analyses. The X-ray crystal structure analysis shows the two independent enantiomeric molecules of clusters (1) in one crystal structure unit.     

The X-ray Structure, Electrochemistry and Catalytic Reactivity of Os4Au(μ-H)3(CO)12(PPh3) Towards the Oxidative Carbonylation of Aniline

The reaction of the anion [Os₄(-H)₃(CO)₁₂]^– with one equivalent of Au(PPh₃)Cl affords [Os₄Au(-H)₃(CO)₁₂(PPh₃)] (1), the structure of which was established by single crystal X-ray analysis. Its electrochemical behavior and catalytic properties are also reported. This bimetallic cluster catalyses the oxidative carbonylation of aniline to give methyl phenylcarbamate in methanol with good conversion and selectivity compared to the homometallic [Os₄(-H)₄(CO)₁₂] cluster.     

Tetraplatinum Cluster Complexes

The tetranuclear platinum cluster complexes [Pt₄(-CO)₃(-dppm)₃(PPh₃)]²⁺ and [Pt₄(-H)(-CO)₂(-dppm)₃(PPh₃)]⁺ have been prepared by cluster expansion. They have butterfly structures and are fluxional.     

C-C bond formation at polynuclear metal centers

Studies on C-C bond formation between simple hydrocarbon species such as CH₂, C=CH₂, CH=CH₂, CH₂=CH₂, CH₂=C=CH₂ and CHCH at a diruthenium center suggest that the process is promoted when the dimetal center can readily compensate for the two electrons lost in the formation of the new C-C bond. Thus, whereas -CH₂ and ethene combine only under forcing conditions, the combination of -CH₂ with allene or ethyne, which have additional -electrons available for coordination, occurs readily at room temperature. Likewise, the availability of uncoordinated -electrons in -C=CH₂ allows vinylidene to link rapidly with ethene at room temperature. Alkyne complexes [Ru₂(CO)(-RCCR)(-C₅H₅)₂] (R=CF₃ or Ph) react only under vigorous conditions with additional alkyne to give [Ru₂(CO)(-C₄R₄) (-C₅H₅)₂], but give these same species at room temperature in the presence of acid, shown to be due to the intermediacy of highly reactive 30-electron -vinyl cations. Thermally, alkyne linking proceedsvia three-alkyne species [Ru₂(-C₆R₆)(-C₅H₅)₂] to a four-alkyne complex [Ru₂(-C₈R₈)(-C₅H₅)₂], containing an unprecedented C₈ ligand composed of a C₆ ring with a C₂ tail. Treatment of [Ru₂(CO)(-RCCR)(-C₅H₅)₂] with unsaturated metal fragments gives trimetal complexes such as [Ru₃(CO)₅(₃-CF₃CCCF₃) (-C₅H₅)₂]. The MeCN derivative of this species undergoes unusual linking processes on reaction with additional alkyne to giveinter alia [Ru₃(CO)₃(₃-CCF₃){₃-C₃(CF₃)₃}(-C₅H₅)₂], arising from alkyne cleavage, and [Ru₃(CO)₃{₃-C₄(CF₃)₂(CO₂Me)₂}(-C₅H₅)₂], a closo-pentagonal bipyramidal Ru₃C₄ cluster.     

The oxidative addition of diphenylphosphine and monophenylphosphine to the electron-rich rhenium-rhenium triple bond. The isolation and characterization of compounds that contain the four-center Re(μ-X)(μ-PR2)Re cluster (X=halide)

Diphenylphosphine oxidatively adds to the ReRe bonds of Re₂ X ₄(-dppm)₂ (X=Cl or Br; dppm=Ph₂PCH₂PPh₂) and Re₂Cl₄(-dpam)₂ (dpam=Ph₂AsCH₂AsPh₂) to afford the dirhenium(III) complexes Re₂(-X)(-PPh₂)HX ₃(-LL)₂. The dppm complexes have also been prepared from the reactions of Re₂(-O₂CCH₃)X ₄(-dppm)₂ with Ph₂PH, and a similar strategy has been used to prepare Re₂(-Cl)(-PPh₂)HCl₃(-dmpm)₂ (dmpm=Me₂PCH₂PMe₂) from Re₂(-O₂CCH₃)Cl₄(dmpm)₂. Phenylphosphine likewise reacts with Re₂ X ₄(-dppm)₂ to give Re₂(-X)(-PHPh)HX ₃(-dppm)₂. An X-ray crystal structure determination on Re₂(-Cl)(-PPh₂)HCl₃(-dppm)₂ confirms its edge-shared bioctahedral structure. This complex crystallizes in the space group (No. 148) witha=21.699(3) Å, =84.50(4)°,V=10084(5) ų, andZ=6. The structure was refined toR=0.049 (R _w 0.069) for 5770 data withI>3.0(I). The Re-Re distance is 2.5918(7) Å. Oxidation of the bromide complex Re₂(-Br)(-PPh₂)HBr₃(-dppm)₂ with NOPF₆ produces the unusual dirhenium(III, II) cation [Re₂(-H)(-Br)[P(O)Ph₂]Br₂(NO)(-dppm)₂]⁺ which has been structurally characterized as its perrhenate salt, [Re₂(-H)(-Br)[P(O)Ph₂]Br₂(NO)(-dppm)₂]ReO₄ · 2CH₂Cl₂. This complex crystallizes in the space group (No. 2) witha=14.187(7) Å,b=16.419(5) Å,c=16.729(5) Å, =98.76(2)°, =110.11(3)°, =104.66(3)°,V=3414(6) ų,Z=2. The structure was refined toR=0.040 (R _w =0.051) for 5736 data withI>3.0(I). The presence of a phosphorus-bound [P(O)Ph₂]^– ligand, a linear nitrosyl and a bridging hydrido ligand has been confirmed. The Re-Re distance is 2.6273(8) Å.     

Chemistry of Tetraosmium Carbonyl Clusters with Phenylazopyridine Ligands: Synthesis, Structure and Electrochemistry

Two new tetraosmium carbonyl clusters [Os₄(-H)₄(CO)₁₁{ ¹-NC₅H₄(N=N)C₆H₅}] (1) and [Os₄(-H)₄(CO)₁₀{ ²-NC₅H₄(N=N)C₆H₅}] (2) were synthesized from the reaction of [Os₄(-H)₄(CO)₁₂] with two equivalent of 2-phenylazopyridine ligand in dichloromethane at ambient temperature using trimethylamine-N-oxide as the decarbonylation reagent. Subsequent chromatographic purification led to the isolation of 1and 2as stable orange and blue solids in respectively 25 and 13% yields. Complex 1converted to 2in a 25% yield in refluxing chloroform. Treating a solution of [Os₄(-H)₄(CO)₁₂] in dichloromethane with two equivalent of 3-phenylazopyridine led to the formation of another two new clusters [Os₄(-H)₄(CO)₁₁{ ¹-NC₅H₄(N=N)C₆H₅}] (3) and [Os₄(-H)₄(CO)₁₀(NMe₃){ ¹-NC₅H₄(N=N)C₆H₅}] (4), which could be isolated as yellow solids in 34% and 21% yields respectively. Thermolysis of 3or 4in refluxing n-hexane gives [Os₄(-H)₃(CO)₁₀{- ³-NC₅H₃(N=N)C₆H₅}] (5) in 24 and 33% yields respectively. Their electronic absorption properties and electrochemical behavior are also reported.     

Cleavage of 1,4-diphenylbuta-1,3-diyne on a ruthenium-cobalt cluster: Synthesis and molecular structure of Co2Ru3(μ4−C2Ph)(μ3−C2Ph)(μ-dppm)(μ-CO)2(CO)9

The reaction between Ru₃(₃-²-PhC₂C=CPh)(-dppm)(CO)₈ and Co₂(CO)₈ afforded dark red Co₂Ru₃(₄-C₂Ph)(₃-C₂Ph)(-dppm)(-CO)₂(CO)₉, shown by an X-ray structure determination to contain a strongly twisted Co₂Ru₃ bow-tie cluster (central Co), to which two PhC₂ units derived from cleavage of the original diyne are attached. One a these is strongly interacting with four metal atoms, the other being attached in the familiar ¹,2²-mode. The dppm ligand remains bridging two of the Ru atoms.