Os Compounds Research Articles

Reactivity and isomerization of tert-butyldiallylphosphine with Os3 metallic cluster: Insights into the reaction mechanism and plausible intermediates through spectroscopic evidence and computational calculations

The reaction of tert‑butyldiallylphosphine with [Os3(CO)10(CH3CN)2] give the compounds [Os3(CO)11{κ(P)-tBuP(CH2CHCH2)2}] 1a, [Os3(CO)11{κ(P)-tBuP(CHCHCH3)2}] 1b, [Os3(CO)10{κ(P)-tBuP(CH2CHCH2)2}2] 2, diastereoisomers [Os3(CO)10{µ:η2-κ3(P,C2,C3)-tBuP(CH2CHCH2)2}] (3a Sp, 3b Rp) and [Os3(CO)9{µ:η2-κ3(P,C2,C3)-tBuP(CH2CHCH2)2)(κ(P)-tBuP(CH2CHCH2)2}] (4a Sp, 4b Rp). Thermolysis of 2 or 3 gave the complexes [Os3(CO)8(μ-H){μ3:η1:η2:η2-κ5(P,C2,C3,C5,C6)-P(CH2CHCH2)(CH2CCH2)}] 5 and diastereoisomers [Os3(CO)8(µ-H)2{µ3:η1:η1:η2-κ3(P,C2,C3)-tBuP(CH2CHCH2)(CCHCH2)}] (6a Sp, 6b Rp). 1a, 1b, 3a, 5 and 6a which were characterized by X-ray analysis. To the best of our knowledge, 1b is the first characterized structure involving isomerization of the double bond of the allylic substituent at room temperature in the case of metallic clusters. X-ray coordinates were used to study the possible reaction mechanisms through computational calculations at the MN15L/def2svp level of theory, obtaining good agreement between experimental and computational results.

Dichloroacetonitrile hydrogenation by osmium cluster: Crystal structure of (μ-Cl)Os3(CO)10(μ-N=CHCHCl2)

Dichloroacetonitrile undergoes hydrogenation by triosmium dihydride cluster under mild conditions. The reaction of cluster complex (μ-H)2Os3(CO)10 (1) with CHCl2CN in the presence of morpholine as a base results in two novel compounds (μ-Cl)Os3(CO)10(μ-N=CHCHCl2) (2) and (μ-H)Os3(CO)10(μ,η2-HN=CHCHCl2) (3). Both compounds were characterized using FTIR, 13C, 1H NMR spectra, and CHN analysis, molecular structure of 2 was determined by X-Ray diffraction study.

Intramolecular Cyclization of Butadiyne Functionalized Ligands coordinated to Triosmium‐Carbonyl Cluster

AbstractReactions between diynes and [Os3(CO)11(CH3CN)] in the presence of water give rise to the formation of intriguing hydride triosmium clusters [Os3(μ‐H)(CO)9{μ3,η1:η3:η1‐RC2COHC≡CR}] (1a–1c) under mild conditions in high yields. When these allylic alcohol compounds 1a–1c are dissolved in dry polar and donor solvents, an intramolecular cyclization process takes place to give [Os3(μ‐H)(CO)9{μ3,η1:η3:η1‐RC2CH=COCR}] (2a–2c) in quantitative yield. The utilization of [Os3(CO)11(CH3CN)] as starting material together with the addition of water can replace the inconvenient use of [Os3(μ‐H)2(CO)10]. This method of synthesis provides a facile pathway for diyne cyclizations and has a clear advantage over those described to date in the literature. Additionally, the analogous cyclized mixed‐metal complex [Os3(μ‐H)(CO)9{μ3,η1:η3:η1‐FcC2CH=COCFc}] (2d) (Fc = ferrocenyl), was synthesized in order to carry out a comparative electrochemical study with the related compounds [Os3(CO)11(μ3‐FcC4Fc)] (I) and [Os3(CO)10(μ3‐FcC4Fc)] (II), which were previously reported by R. D. Adams.

Opening of Carborane Cages by Metal Cluster Complexes: The Reaction of a Thiolate-Substituted Carborane with Triosmium Carbonyl Cluster Complexes

The reaction of Os3(CO)10(NCMe)2 with closo-o-(1-SCH3)C2B10H11 has yielded the complex Os3(CO)9[μ3-η(3)-C2B10H9(SCH3)](μ-H)2, 1, by the loss of the two NCMe ligands and one CO ligand from the Os3 cluster and the coordination of the sulfur atom and the activation of two B-H bonds with transfer of the hydrogen atoms to the cluster. Reaction of 1 with a second equivalent of Os3(CO)10(NCMe)2 yielded the complex Os3(CO)9(μ-H)[(μ3-η(3)-1,4,5-μ3-η(3)-6,10,11-C2B10H8S(CH3)]Os3(CO)9(μ-H)2, 2, that contains two triosmium triangles attached to the same carborane cage. The carborane cage was opened by cleavage of two B-C bonds and one B-B bond. The B-H group that was pulled out of the cage became a triply bridging group on one of the Os3 triangles but remains bonded to the cage by two B-B bonds. When heated to 150 °C, 2 was transformed into the complex Os3(CO)9(μ-H)[(μ3-η(3)-μ3-η(3)-C2B10H7S(CH3)]Os3(CO)9(μ-H), 3, by the loss of two hydrogen atoms and a rearrangement that led to further opening of the carborane cage. Reaction of 1 with a second equivalent of closo-o-(1-SCH3)C2B10H11 has yielded the complex Os3(CO)6)(μ3-η(3)-C2B10H9-R-SCH3) (μ3-η(3)-C2B10H10-S-SCH3)(μ-H)3, 4a, containing two carborane cages coordinated to one Os3 cluster. Compound 4a was isomerized to the compound Os3(CO)6(μ3-η(3)-C2B10H9-R-SCH3)(μ3-η(3)-C2B10H10-R-SCH3)(μ-H)3, 4b, by an inversion of stereochemistry at one of the sulfur atoms by heating to 174 °C.

Ligand substitution in the osmium-antimony rings Os3(μ-SbPh2)2 (CO)10 and Os3(μ-SbPh2)3(Cl)(CO)9

TMNO-activated ligand substitution in the fused ring compounds Os3(μ-SbPh2)2(CO)10, 1, and Os3(μ-SbPh2)3(Cl)(CO)9, 2, in acetonitrile affords the mono- and disubstituted CH3CN-derivatives. The initial product of CH3CN substitution in 1 is an equatorial isomer, which can isomerize to the axial isomer upon heating; they are the first examples in which both isomers have been characterized crystallographically. Subsequent reaction of the CH3CN-derivatives of 2 with two-electron donor ligands L do not always result in the displacement of the acetonitrile ligands; displacement of a carbonyl ligand can also occur and appears to depend on the stereoelectronic properties of L. This is suggestive of an associative mechanism.

Isomerization of the osmium-tellurium cluster Os3(μ-TeR)2(CO)10: a kinetic and computational study.

The kinetics for the isomerization of the 50e cluster Os3(μ-TeTol-p)2(CO)10 (), where the tellurides bridge two different Os-Os edges, to one in which the tellurides bridge the same open OsOs edge () have been measured experimentally by (1)H NMR spectroscopy. The determined activation parameters are ΔH(‡) = 77 ± 9 kJ mol(-1) and ΔS(‡) = -12 ± 28 J mol(-1) K. The conversion of to has been computationally investigated by electronic structure calculations using the model compound Os3(μ-TeMe)2(CO)10. The computed isomerization pathway is consistent with the kinetic data and the thermodynamic preference for the product stereoisomer that possesses a slipped, eclipsed conformation for the two p-tolyl groups.

Phenazine-substituted polynuclear osmium clusters: Synthesis and DFT evaluation of the C-metalated derivatives Os3(CO)9(μ3,η2-C12H7N2)(μ-H) and Os3(CO)9(μ3,η2-C12H6N2)(μ-H)2

Os3(CO)12 reacts with phenazine in refluxing xylene to yield the monohydride cluster Os3(CO)9(μ3,η2-C12H7N2)(μ-H) (1) in 18% yield and the dihydride cluster Os3(CO)9(μ3,η2-C12H6N2)(μ-H)2 (2) in 21% yield. Compound 1 reacts reversibly with CO to give the decacarbonyl compound Os3(CO)10(μ,η2-C12H7N2)(μ-H) (3) and with PPh3 to afford the addition product Os3(CO)9(μ,η2-C12H7N2)(PPh3)(μ-H) (4). Compounds 1, 2, and 4 have been structurally characterized. 1 contains a C-metalated phenazine ligand that is coordinated to the cluster by a dative nitrogen bond and a benzylidene-type bond, the latter which bridges the same cluster edge as the bridging hydride. The activated phenazine ligand in 2 derives from a double C–H bond metalation sequence, affording a face-capping heterocyclic ligand that binds adjacent osmium centers through two σ–Os–C bonds and the third osmium atom via an aryl π bond in an η2 fashion. Compound 4 exhibits a closed trimetallic Os3(CO)9 core that contains edge-bridging phenazine (C,N coordination) and hydride moieties, and a triphenylphosphine ligand that is coordinated at the non-phenazine-ligated osmium center. These compounds represent rare examples of polynuclear osmium clusters containing C-metalated phenazine ligands. The potential energy surfaces that afford clusters 1 and 2 from Os3(CO)12 and phenazine have been modeled by DFT calculations, and these data indicate that both product clusters originate from the unsaturated cluster Os3(CO)11.

Facile cleavage of phenyl groups from BiPh3 in its reactions with Os3(CO)10(NCMe)2 and evidence for localization of π-bonding in a bridging benzyne ligand

Three new compounds were obtained from the reaction of Os3(CO)10(NCMe)2, 1 with BiPh3 in a methylene chloride solution at reflux. These have been identified as Os3(CO)10(μ3-C6H4), 3, Os3(CO)10Ph(μ-η2- OCPh), 4, and HOs6(CO)20(μ-η2-C6H4)(μ4-Bi), 6. Two other products Os2(CO)8(μ-BiPh), 2, and HOs5(CO)18(μ-η2-C6H4)(μ4-Bi), 5 were obtained previously from the reaction of Os3(CO)11(NCMe) with BiPh3. Cleavage of the phenyl groups from the BiPh3 was the dominant reaction pathway and two of the products 3 and 4 contain rings but no bismuth. Each of the new compounds was characterized structurally by single-crystal X-ray diffraction methods. Compound 3 contains a triply-bridging benzyne (C6H4) ligand that exhibits a pattern of alternating long and short C–C bonds that can be attributed to partial localization of the π-bonding in the C6 ring. The localization in the π-bonding in the ring is supported by DFT calculations. Compound 4 contains a triangular cluster of three osmium atoms with a bridging benzoyl ligand and a terminally coordinated phenyl ligand. Compound 6 contains six osmium atoms divided into two groups of four and two and the two groups are linked by a spiro-bridging bismuth atom. The group of two osmium atoms contains a bridging C6H4 ligand. When heated, compound 4 was converted into 3 and the compound Os3(CO)10(μ-η2-OCPh)2, 7. Compound 7 contains two bridging benzoyl ligands.

Dynamic Rotation of Bridging Aryl Ligands in Unsaturated Metal Carbonyl Cluster Complexes

Variable-temperature NMR studies of the compound Os3(CO)10(μ-η 1 -C6H5)(μ-AuPPh3 )( 1) have revealed a dynamic process of hindered rotation of the bridging phenyl ligand about the metalmetal bond. The activation parameters for the process, ΔH ⧧ = 73.33(42) kJ/mol and ΔS ⧧ = �2.66(1.25) J/(K mol), were determined by analysis of variable-temperature 1 H NMR spectra. A density functional theory analysis has provided a mechanism that involves a shift of the ligand out of the bridging position with the formation of an agostic interaction of one of the ortho-positioned CH bonds of the phenyl ring to the neighboring metal atom. The related compound Os3(CO)10(μ-η 1 -Py)(μ-AuPPh3 )( 2; Py = 2-C15H9) was synthesized and was found to exhibit a similar rotation of the bridging pyrenyl ligand about the metalmetal bond: ΔH ⧧ = 70.93(61) kJ/mol and ΔS ⧧ = �6.98(1.83) J/(K mol).

Osmium–Germanium and Osmium–Germanium–Gold Carbonyl Cluster Complexes: Syntheses, Structures, Bonding, and Reactivity

Reactions of Os3(CO)10(NCMe)2 with HGePh3 have yielded the compounds Os3(CO)10(NCMe)(GePh3)(μ-H) (1) and Os3(CO)10(GePh3)2(μ-H)2 (2) by the sequential replacement of the NCMe ligands and the oxidative addition of the GeH bonds of one and two HGePh3 molecules, respectively, to the osmium atoms of the cluster. Compound 2 exists as two isomers in solution at low temperatures which interconvert rapidly on the 1H NMR time scale at room temperature. When it was heated, 1 was transformed into the pentaosmium complex Os5(CO)17(μ-GePh2) (3), which exhibits a planar raft structure with one bridging GePh2 ligand. Compound 1 reacts with the compound PhAu(PPh3) to yield the compound Os3(CO)8(μ-CO)(μ-O═CPh)(μ-GePh2)(μ-AuPPh3) (4), which contains a bridging O═CPh ligand and a Au(PPh3) group that bridges an Os–Ge bond. A minor product, Os(CO)4(GePh3)(AuPPh3) (5), was also obtained in this reaction. Compound 4 was also obtained from the reaction of 1 with CH3Au(PPh3). Compound 4 reacted with PhC2Ph to yield the complex Os...

Decarbonylation Reaction of [Os3(CO)10(μ-H)(μ-SN2C4H5)]: X-ray Structures of the Two Isomers of [Os3(CO)9(μ-H)(μ 3-η 2-SN2C4H5)

The thermal reaction of [Os3(CO)10(μ-H)(μ-SN2C4H5)] (1) at 110 °C afforded the new compound [Os3(CO)9(μ-H)(μ 3-η 2-SN2C4H5)] (2) in 84% yield. Compound 2 exists as two isomers, which differ in the disposition of the bridging hydride ligand. Both of the isomers of 2 have been characterized by a combination of elemental analysis, infrared and 1H NMR spectroscopic data together with single crystal X-ray crystallography. The isomers crystallize together in the triclinic space group P-1 with a = 10.4775(2), b = 13.3056(3), c = 15.0325(3) A, α = 110.8890(10), β = 99.3880(10), γ = 96.1620(10)°, Z = 2 and V = 1900.31(7) A3. The synthesis and the molecular structures of the two isomers of [Os3(CO)9(μ-H)(μ 3-η 2-SN2C4H5)] are described. The isomers differ in the disposition of the hydride ligand.

Activation of Hydrogen and Related Small Molecules by the Unsaturated Cluster Complex PtOs3(CO)7(PBut3)(μ-PBut2)(μ4-CHCMeCH)

Reactions of the unsaturated mixed metal cluster complex PtOs3(CO)7(PBut3)(μ-PBut2)(μ4-CHCMeCH), 1, with hydrogen, HGePh3, and PhC2H have been investigated. Compound 1 reacts reversibly with hydrogen at room temperature to yield the dihydrido complex PtOs3(CO)7(PBut3)(μ-PBut2)(μ4-CHCMeCH)(μ-H)(H), 2. A computational analysis shows that the hydrogen addition occurs by oxidative addition at the electronically unsaturated platinum atom and passes through two unstable intermediates before giving the final product 2. Compound 1 reacts with HGePh3 at the Ge−H bond to form the complex PtOs3(CO)7(PBut3)(μ-PBut2)(μ4-CHCMeCH)(GePh3)(μ-H), 3, but in this reaction the HGePh3 addition occurred at one of the osmium atoms and a CO ligand was shifted to the platinum atom. Compound 1 reacts with PhC2H by loss of the platinum atom and the PBut3 ligand to give the compound Os3(CO)7(μ-PBut2)[μ3-η5-CHCMeC(H)CCPhH], 4. In the process, the PhC2H molecule became bonded to the CHCMeCH ligand in 1 and its hydrogen atom was shifted to the phenyl-substituted carbon atom to form a triply bridging CHCMeC(H)CCPhH ligand. All of the products were characterized by single-crystal X-ray diffraction analyses.

An Electron-Deficient Triosmium Cluster Containing the Thianthrene Ligand: Synthesis, Structure and Reactivity of [Os3(CO)9(μ3-η2-C12H7S2)(μ-H)

Reaction of [Os3(CO)10(CH3CN)2] with thianthrene at 80 °C leads to the nonacarbonyl dihydride compound [Os3(CO)9(μ-3,4-η2-C12H6S2)(μ-H)2] (1) and the 46-electron monohydride compound [Os3(CO)9(μ3-η2-C12H7S2)(μ-H)] (2). Compound 2 reacts reversibly with CO to give the CO adduct [Os3(CO)10(μ-η2-C12H7S2)(μ-H)] (3) whereas with PPh3 it gives the addition product [Os3(CO)9)(PPh3)(μ-η2-C12H7S2)(μ-H)] (4) as well as the substitution product 1,2-[Os3(CO)10((PPh3)2] (5) Compound 2 represents a unique example of an electron-deficient triosmium cluster in which the thianthrene ring is bound to cluster by coordination of the sulfur lone pair and a three-center-two-electron bond with the C(2) carbon which bridges the same edge of the triangle as the hydride. Electrochemical and DFT studies which elucidate the electronic properties of 2 are reported.

Synthesis and Characterization of Osmium-Containing Silsesquioxanes: High-Yield Routes to {Os3(CO)10(μ-H)[(μ-O)Si7O10(c-C6H11)7]} and the New Clusters {Os3(CO)10(μ-H)[(μ-O)Si7O9(OH)2(c-C6H11)7]}, {[Os3(CO)10(μ-H)]2(μ-O)2Si7O9(OH)(c-C6H11)7}, {Os3(CO)10(μ-H)[(μ-O)Si8O11(OH)(c-C6H11)8]}, and {[Os3(CO)10(μ-H)]2(μ-O)2Si8O11(c-C6H11)8}

The reactions of [Os3(CO)10(μ-H)(μ-OH)] (3) with the incompletely condensed silsesquioxanes [(c-C6H11)7Si7O9(OH)3] (1) and [(c-C6H11)8Si8O11(OH)2] (2) afford in high yield {Os3(CO)10(μ-H)[(μ-O)Si7O10(c-C6H11)7]} (4) and the new compounds {Os3(CO)10(μ-H)[(μ-O)Si7O9(OH)2(c-C6H11)7]} (5), {[Os3(CO)10(μ-H)]2(μ-O)2Si7O9(OH)(c-C6H11)7} (6), {Os3(CO)10(μ-H)[(μ-O)Si8O11(OH)(c-C6H11)8]} (8), and {[Os3(CO)10(μ-H)]2(μ-O)2Si8O11(c-C6H11)8} (9), which are discrete molecular models of silica-anchored [Os3(CO)10(μ-H)(μ-OSi⋮)]. Compounds 6 and 9 represent the first examples of complexes containing two [Os3(CO)10(μ-H)] cluster cores. The X-ray structures of 5, 8, and 9 are reported.

S−C and C−H Bond Activations as well as C−C Couplings in C5H5FeC5H4C⋮CSC⋮CSiMe3 Promoted by the Cluster Os3(CO)10(NCMe)2

The new compounds [Os3(CO)9(μ-CO){μ-η2-(Fc)CCSC⋮CSiMe3}] (1), [Os3(CO)10(μ-η1-SC⋮CSiMe3)(μ-η2-C⋮CFc)] (2), [Os3(CO)9(μ-η1-SC⋮CSiMe3)(μ3-η2-C⋮CFc)] (3), [Os3(CO)9(μ3-η2,η3,η3-{C5H5FeC5H3CCC(S)C(SiMe3)CHO}] (4), and [Os3(CO)9(μ3-S){μ3-η2-(Me3Si)CCC⋮CFc}] (5) were obtained from the reaction of FcC⋮CSC⋮CSiMe3 with the activated cluster Os3(CO)10(NCMe)2, as a result of S−C and C−H bond activation as well as C−C coupling reactions in the thioether. The crystal structures of all of them were determined by X-ray diffraction analysis.

Reactions of Electron-Deficient Triosmium Clusters with Diazomethane: Electrochemical Properties and Computational Studies of Charge Distribution

The 46-electron quinoline triosmium clusters (μ-H)Os3(CO)9(μ3-η2-C9H5(R)N) (6, R = 4-CH3; 7, R = H) react with excess CH2N2 at 0 to 25 °C to give (μ-H)2Os3(CO)9(μ3-η2-CHC9H5(R)N) (10, R = 4-CH3; 11, R = H), formed by insertion and subsequent C−H oxidative addition of a CH2 moiety into the ring C(8)−Os bond. In contrast, the related 46-electron quinoxaline compound (μ-H)Os3(CO)9(μ3-η2-C8H5N2) (8) reacts with excess CH2N2 at 0 to 25 °C to give (μ-H)2Os3(CO)9(μ3-η2-CHC8H4(5-CH3)N2) (12), where two CH2 groups have inserted into the C(5)−H bond as well as the C(8)−Os bond, and (μ-H)2Os3(CO)9(μ3-η2-CHC8H5N2) (13), the analogue of 11. The 5-methylquinoxaline compound (μ-H)Os3(CO)9(μ3-η2-C8H4(5-CH3)N2) (9) reacts with diazomethane at 0 to 25 °C to give 12 and Os3(CO)9(μ3-η2-C8H4(5-CH3)N2)(μ-CH2)(CH3) (14), containing an edge-bridging methylene group and a σ-bound methyl group. Thermolysis of 10 and 11 at 98 °C yields (μ-H)3Os3(CO)8(μ3-η2-C(C9H5)(R)N) (15, R = 4-CH3; 16, R = H), (μ-H)Os3(CO)9(μ3-η2-C(C9H5)(R)N) (17, R = 4-CH3; 18, R = H), and (μ-H)Os4(CO)11(μ3-η2-C(C9H5)(R)N) (19, R = 4-CH3; 20, R = H). The trihydrides 15 and 16 are formed by a further C−H activation of the coordinated methylidene group of 10 and 11, respectively. Thermolysis of 10 and 11 in the presence of H2 at 1 atm at 80 °C gives 15 and 16 in high yields. The solid-state structure of 17 reveals that the methylidyne carbon atom has a significant bonding interaction with the osmium atom coordinated to nitrogen. Thermolysis of 12 and 13 at 98 °C gives (μ-H)Os3(CO)9(μ3-η2-CC8H4(R)N2) (21, R = 5-CH3; 22, R = H), whereas a similar thermolysis in the presence of H2 (1 atm) at 80 °C gives (μ-H)3Os3(CO)8(μ3-η2-CC8H4(5-CH3)N2) (23, R = 5-CH3; 24, R = H). The compounds 12, 13, 23, and 24 all show one-electron reversible reductions, and the reduction potentials are similar to previously studied quinoxaline clusters. DFT calculations show that most of the spin density is confined to the heterocyclic ligand, and this explains the similarity between the observed reduction potentials for the products with different bonding modes to cluster but containing the same heterocycle. The qualitative correlation between the calculated natural charges and the distribution of unpaired spin densities in 12 and 13 corroborate this conclusion. The molecular structures of 10, 12, 13, 17, and 20 have been determined by single-crystal X-ray diffraction studies.

Syntheses, Structures, Bonding, and Redox Behavior of 1,4-Bis(ferrocenyl)butadiyne Coordinated Osmium Clusters

The reaction of Os3(CO)11(NCMe) (1) with 1,4-bis(ferrocenyl)butadiyne (3) yielded two products: Os3(CO)10(μ3-η2-FcC4Fc) (4) and Os3(CO)11(μ3-η4-FcC4Fc) (5). Compound 4 was obtained in better yield (94%) from the reaction of Os3(CO)10(NCMe)2 (2) with 3 at 67 °C. Compound 4 contains a bis(ferrocenyl)butadiyne ligand coordinated to a triangular triosmium cluster via one of its alkyne groups in a triply bridging fashion. Compound 5 contains an open triosmium cluster with the two C−C triple bonds coordinated in a parallel fashion to the three metal atoms. Compound 2 reacts with 3 at 97 °C to yield the compound Os2(CO)6(μ-η4-FcC2C⋮CFc)2 (6) as a result of cluster fragmentation. Compound 6 exhibits a ferrole-type structure formed by the coupling two molecules of diyne 3. At 97 °C 4 is transformed into the new compound Os3(CO)9(μ3-η2-C⋮CFc)(μ-η2-C⋮CFc) (7), which contains two bridging ferrocenylacetylide ligands formed by cleaving the C−C bond between the two alkyne groups. All four products were characterized by IR, 1H NMR, and single-crystal X-ray diffraction analyses. The two ferrocenyl units in 4, 6, and 7 are inequivalent. The redox potentials of the ferrocenyl groups in 4 are very closely spaced, ΔEp = 0.057 V, suggesting that there is little electrocommunication between them. The redox potentials of the ferrocenyl groups in 6 are widely spaced, probably due to their intrinsic inequivalence. The two ferrocenyl units in 5 are equivalent but show two resolved one-electron redox processes, ΔEp = 0.184 V, which indicates that there is significant electrocommunication between them. This is attributed to greater interactions in the π-orbital network in the ligand 3 induced by coordination to the metal atoms. A molecular orbital model based on a butatrienediyl group is proposed to explain the coordination and π-bonding in the 1,4-bis(ferrocenyl)butadiyne ligand in 5.

Carboxylation of a μ3-Diazo Methylidyne Triosmium Cluster

The unsaturated cluster Os3(CO)8(Ph2PCH2P(Ph)C6H4)(μ-H) (1) reacts with CH2N2 at −10 to 25 °C to give two novel compounds Os3(CO)7(μ3-CN2)(μ-dppm)(μ-H)2 (2) and Os3(CO)7(μ3-CCO2H)(μ-dppm)(μ-H)3 (3) characterized by single-crystal X-ray crystallography. Compound 2 is converted to 3 in almost quantitative yield by reaction with CO (atmospheric pressure) and trace H2O. The reaction of 2 with molecular hydrogen at atmospheric pressure at 80 °C yields Os3(CO)8(μ-dppm)(μ-H)2 (4) and Os3(CO)10(μ-dppm) (5).

Reactivity of Triosmium Carbonyl Clusters with 1,8-Diaminonaphthalene − Synthesis and Structural Characterization of Amido, Diamido, andC-Metalated Trinuclear Derivatives

The compounds [Os3(CO)12] and [Os3(μ-H)2(CO)10] do not react with 1,8-diaminonaphthalene (H2dan) under thermal conditions (110 °C, 30 min). However, [Os3(CO)10(MeCN)2] reacts with H2dan (THF, reflux temperature) to give two isomers of [Os3(μ-H)(μ-Hdan)(CO)9] (1 and 2). In toluene at reflux temperature, these reagents afford [Os3(μ-dan)(CO)10] (3). Compound 2 can be converted into 3 under thermal conditions, but no interconversion between 1 and 2 has been observed. The three compounds have been characterized by X-ray diffraction methods. Compound 1 arises from the C-metalation of H2dan in a position adjacent to an NH2 group; this generates a hydride and a ligand that interacts with the three metal atoms through one of the NH2 groups, through the metalated carbon atom (which spans an Os−Os edge), and through one of the C=C bonds of the metalated ring. In compound 2, the hydride arises from the oxidative addition of an N−H bond of H2dan; the resulting ligand interacts with two of the three metal atoms through the amido NH fragment (bridging position) and through the remaining NH2 group. Compound 3 is derived from the transformation of both NH2 groups of H2dan into amido NH groups and consists of a 50-electron trinuclear cluster with the longest edge doubly-bridged by both amido groups.

Hydrido-sulfido-bridged triangular Os3 cluster compounds with different phosphine ligand substitution patterns

In the course of our studies of trinuclear osmium cluster complexes with bridging sulfido and hydrido ligands, the new compounds Os3(μ-H)(μ-SR)(CO)9(PHCy2) (Cy = cyclo­hexyl) with R = phenyl, (I) (nona­carbonyl-1κ3C,2κ3C,3κ3C-di­cyclo­hexyl­phosphine-3κP-μ-hydrido-1:2κ2H-μ-phenyl­thio-1:2κ2S-triangulo-triosmium), [Os3H(C6H5S)(C12H23P)(CO)9], and R = naphthyl, (II) [nona­carbonyl-1κ3C,2κ2C,3κ4C-di­cyclo­hexyl­phosphine-2κP-μ-hydrido-1:2κ2H-μ-(2-naphthyl­thio)-1:2κ2S-triangulo-triosmium], [Os3H(C10H7S)(C12H23P)(CO)9], were prepared. We report on these two phosphine-substituted complexes, which exhibit perceptible changes of the Os—Os bond parameters due to the ligand-substitution pattern.