Cluster HOs3 Research Articles

Reactions of [HOs3(CO)10(µ-L)] (L = saccharinate, thiosaccharinate) with Ph3SnH and Ph3GeH

Reactions of triosmium clusters bearing a bridging saccharinate (sac) or thiosaccharinate (tsac) ligand with Ph3EH (E = Sn, Ge) are examined. The saccharinate cluster [HOs3(CO)10(µ-N,O-sac)] reacts with Ph3EH at 110°C to yield [H2Os3(CO)9(EPh3)(µ-N,O-sac)] (1a, E = Sn; 1b, E = Ge) through oxidative-addition of E‒H bond to the parent cluster. Similar reaction between the thiosaccharinate cluster [HOs3(CO)10(µ-N,S-tsac)] and Ph3EH at 98°C affords [H2Os3(CO)9(EPh3)(µ-N,S-tsac)] (2a, E = Sn; 2b, E = Ge) and [H2Os3(CO)8(EPh3)(µ-N,C-C6H4CNSO2)(µ3-S)] (3a, E = Sn; 3b, E = Ge), the latter being isolated as the major product. Control experiments show that competitive pathways are involved in this reaction, and the products are formed via separate reaction pathways. Another product namely [Os3(CO)9(µ3-N,C-C6H4CHNSO2)(µ3-S)] (4) was also isolated from the reaction between [HOs3(CO)10(µ-N,S-tsac)] and Ph3GeH which does not contain any germanium ligand, and is directly formed from the parent tsac-substituted cluster as confirmed by independent control experiments. The molecular structures of the different types of products isolated from these reactions have been confirmed by single crystal X-ray diffraction analyses.

Bimodal substitution behavior in the reaction of N,N’-diisopropylformamidine with [Os3(CO)10(NCMe)2]: Kinetics and molecular structures of the formamidinate-substituted clusters HOs3(CO)9[μ-C(O)NPriC(H)NPri], HOs3(CO)10[μ-NPriC(H)NPri], and HOs3(CO)9[μ3-NPriC(H)NPri

The dinitrogen donor N,N’-diisopropylformamidine [PriN=C(H)NHPri] reacts with the triosmium cluster Os3(CO)10(NCMe)2 at room temperature to yield the isomeric clusters HOs3(CO)9[μ-C(O)NPriC(H)NPri] (1) and HOs3(CO)10[μ-NPriC(H)NPri] (2) in a 1:2.8 ratio. 1 contains an edge-bridging iminocarbamoyl ligand, while 2 contains a bridging formamidinate ligand. Thermolysis of 1 yields 2 plus the face-capped cluster HOs3(CO)9[μ3-NPriC(H)NPri] (3). The decarbonylation of 2 to 3 + CO confirms the molecularity of the observed reaction steps. The three products have been fully characterized in solution by IR and NMR spectroscopies, and the solid-state structures for 1-3 have been determined by X-ray crystallography. The kinetics for the thermolysis reaction were investigated over the temperature range 342–383 K, and the concentration versus time profiles for the conversion of 1 → 2 → 3 + CO have been successfully modeled using two consecutive, irreversible first-order reactions. The bonding in clusters 1-3 have been examined by DFT, and these data support cluster 1 as the kinetic substitution product and cluster 2 as the thermodynamically favored isomer.

Synthesis of the Stereoisomeric Clusters 1,2-Os3(CO)10(trans-dpmn) and 1,2-Os3(CO)10(cis-dpmn) [where dpmn = 2,3-bis(diphenylphosphinomethyl)-5-norbornene]: DFT Evaluation of the Isomeric Clusters 1,2-Os3(CO)10(dpmn) and Isomer-Dependent Diphosphine Ligand Activation

The bicyclic diphosphines trans- and cis-2,3-bis(diphenylphosphinomethyl)-5-norbornene (dpmn) react with 1,2-Os3(CO)10(MeCN)2 (1) to furnish the corresponding ligand-bridged clusters Os3(CO)10(trans-dpmn) (2) and Os3(CO)10(cis-dpmn) (3). Both new products have been isolated and the molecular structures established by X-ray diffraction analyses. The dihydroxyl-bridged cluster 1,2-Os3(CO)8(µ-OH)2(cis-dpmn) (4), which accompanied the formation of 3 in one reaction, has been isolated and characterized by mass spectrometry and X-ray crystallography. Whereas cluster 2 is stable in toluene at 373 K, 3 is thermally sensitive under identical conditions and undergoes loss of CO (2 equiv), coupled with the activation of three norbornene C–H bonds and one P–C(phenyl) bond, to furnish the dihydride cluster H2Os3(CO)8[µ3-2-PhPC-3-endo-Ph2PCH2(C7H7)] (5). The solid-state structure of 5 confirms the multiple activation of the cis-dpmn ligand and accompanying formation of the face-capping 2-PhPC-3-endo-Ph2PCH2(C7H7) moiety in the product. DFT calculations on 2 and 3 indicate that the former cluster is the thermodynamically more stable isomer, and the conversion of 3 → 5 + 2CO + benzene is computed to be exergonic by 12.7 kcal/mol and is entropically favored due to the release of the CO and benzene by-products.

CO Substitution in HOs3(CO)10(μ-SC6H4Me-4) by the Diphosphine 4,5-Bis(diphenylphosphino)-4-cyclopentadiene-1,3-dione (bpcd): Structural and DFT Evaluation of the Isomeric Clusters HOs3(CO)8(bpcd)(μ-SC6H4Me-4)

The reaction of the cluster HOs3(CO)10(μ-SC6H4Me-4) (1) with the diphosphine 4,5-bis(diphenylphosphino)-4-cyclopentadiene-1,3-dione (bpcd) has been investigated. 1 reacts with bpcd at room temperature in the presence of Me3NO to give the isomeric clusters 1,2-HOs3(CO)8(bpcd)(μ-SC6H4Me-4) (2a) and 1,1-HOs3(CO)8(bpcd)(μ-SC6H4Me-4) (2b). Clusters 2a and 2b have been isolated, and the molecular structure of each compound has been established by X-ray crystallography. The X-ray structure of 2a confirms the coordination of one of the non-hydride-bridged Os–Os vectors by the bpcd ligand, while the structure of 2b exhibits a chelating bpcd ligand that is bound to one of the osmium centers ligated by the thiolate and hydrido ligands. 2a and 2b are stable in refluxing toluene and show no evidence for bridge-to-chelate isomerization of the ancillary bpcd ligand. DFT calculations on 2a and 2b indicate that the former cluster is the thermodynamically more stable isomer. Near-UV irradiation of 2b leads to CO loss and ortho metalation of the thiolate moiety, yielding the dihydride cluster H2Os3(CO)7(bpcd)(μ,σ-SC6H3Me-4) (3). The conversion of 2b to 3 and free CO is computed to be endothermic by 14.1 kcal/mol and the reaction is driven by the entropic release of CO. The photochemically promoted ortho-metalation reaction is isomer dependent since cluster 2a is inert under identical conditions.

Isomeric clusters [HOs3(CO)10(C18H11N6)] obtained from the reaction of [Os3(CO)10(CH3CN)2] with new tris-pyridyl-1,2,4-triazines

The new tris-pyridyl-as-triazines 3-(3-pyridyl)-5,6-bis(2-pyridyl)-1,2,4-triazine (3TPT) and 3-(4-pyridyl)-5,6-bis(2-pyridyl)-1,2,4-triazine (4TPT) have been synthesized from the corresponding pyridyl-amidrazone and 2,2′-pyridyl in good yields. The reaction of 3TPT with [Os3(CO)10(CH3CN)2] at room temperature gives the new compounds [HOs3(CO)9(C18H11N6)] (1 and 2) by orthometallation of the 3-pyridyl ring at the 2- and 6-positions. The reaction of 4TPT with [Os3(CO)10(CH3CN)2] gives only one derivative, the isomer [HOs3(CO)9(C18H11N6)] (3) by orthometallation of the 4-pyridyl ring. In all cases, C–H activation of the 3-pyridyl or 4-pyridyl is favored, so the 2-pyridyl substituents remain uncoordinated.

Coordination Behavior and Transformations of Thienyl-Substituted Diacetylenes upon Coordination to Os3H2(CO)10

The reaction between 2- and 3-thienyl-substituted 1,3-butadiynes and the electron-deficient osmium cluster Os3H2(CO)10 yields trinuclear coordination products, associated with transformations of the diacetylene ligands. Depending on the heteroaryl end groups, osmium clusters with both a closed and open Os-triangle core were formed. The reaction between Os3H2(CO)10 and 1,4-bis(2-thienyl)butadiyne yielded [Os3(μ-H)(CO)10{(μ-η-(C4H3S)(C8H4S)}] (1) and [Os3(μ-H)(CO)10{(μ3-η2-η1-η1-(SC7H4)C(SC4H3)}] (2), whereas in the analogous case of 1,4-bis(3-thienyl)butadiyne the main coordination product was found to be [Os3(μ-H)(CO)10{(μ-η-(C4H3S)(C8H4S)}] (3). Compounds 1–3 were stable in air, but lost carbon monoxide upon prolonged heating. Thermal decarbonylation of 1 under N2 yielded a mixture of [Os3(μ-H)(CO)9{(μ3-η3-(C4H3S)(C8H4S)}] (4) and [Os3(μ-H)2(CO)9{(μ3-η1-η1-(C4H3S)(C8H3S)}] (5). Thermal decarbonylation of 2 yielded [Os3(μ-H)(CO)9{(μ3-η3-(C4H3S)(C8H4S)}] (6), while thermal decarbonylation of 3 yielded [Os3(μ-H)(CO)9{(μ3-η3-(C4H3S)(C8H4S)}] (7). A reaction involving 3 with CF3COOH affords as the main cluster product the known cluster [Os3(μ-H)(CO)10(O2CF3)] (8) and, unusually, permits the isolation and characterization of the novel organic molecule [(C4H3S)(C8H4S)(OCF3)] (9) cleaved from the parent cluster. The structures of the new compounds were established by single-crystal X-ray studies and spectroscopic methods and supported by density functional theory.

Experimental and Computational Studies of the Isomerization Reactions of Bidentate Phosphine Ligands in Triosmium Clusters: Kinetics of the Rearrangements from Bridged to Chelated Isomers and X-ray Structures of the Clusters Os3(CO)10(dppbz), 1,1-Os3(CO)10(dppbzF4), HOs3(CO)9[μ-1,2-PhP(C6H4-η1)C6H4PPh2], and HOs3(CO)9[μ-1,2-PhP(C6H4-η1)C6F4PPh2

The diphosphine ligand 1,2-bis(diphenylphosphino)benzene (dppbz) reacts with the activated cluster 1,2-Os3(CO)10(MeCN)2 (1) at room temperature to furnish a mixture of the triosmium clusters 1,2-Os3(CO)10(dppbz) (2) and 1,1-Os3(CO)10(dppbz) (3), along with a trace amount of the hydride cluster HOs3(CO)9[μ-1,2-PhP(C6H4-η1)C6H4PPh2] (4). The dppbz-bridged cluster 2 forms as the kinetically controlled product and irreversibly transforms to the corresponding chelated isomer 3 at ambient temperature. The disposition of the dppbz ligand in 2 and 3 has been established by X-ray crystallography and 31P NMR spectroscopy, and the kinetics for the conversion 2 → 3 have been followed by UV−vis spectroscopy in toluene over the temperature range 318−343 K. The calculated activation parameters (ΔH⧧ = 21.6(3) kcal/mol; ΔS⧧ = −11(1) eu) and lack of CO inhibition support an intramolecular isomerization mechanism that involves the simultaneous migration of phosphine and CO groups about the cluster polyhedron. The reaction between 1 and the fluorinated diphosphine ligand 1,2-bis(diphenylphosphino)tetrafluorobenzene (dppbzF4) was examined under similar reaction conditions and was found to afford the chelated cluster 1,1-Os3(CO)10(dppbzF4) (6) as the sole observable product. The absence of the expected bridged isomer 1,2-Os3(CO)10(dppbzF4) (5) suggests that the dppbzF4 ligand destabilizes 5, thus accounting for the rapid isomerization of 5 to 6. Near-UV irradiation of clusters 3 and 6 leads to CO loss and ortho metalation of an ancillary aryl group. The resulting hydride clusters 4 and HOs3(CO)9[μ-1,2-PhP(C6H4-η1)C6F4PPh2] (7) have been isolated and fully characterized by spectroscopic and X-ray diffraction analyses. Both 4 and 7 react with added CO under mild conditions to regenerate 3 and 6, respectively, in quantitative yield. The rearrangements of bridged to chelated diphosphine complexes in this genre of decacarbonyl clusters have been investigated by DFT calculations. The computational results support a concerted process, involving the scrambling of equatorial CO and phosphine groups via a classical merry-go-round exchange scheme. The barriers computed for this mechanism agree well with those that have been measured, and steric compression within the bridged diphosphine groups of the reactants has been calculated to reduce the barrier heights for the rearrangement.

Ortho-Metalation Dynamics and Ligand Fluxionality in the Conversion of Os3(CO)10(dppm) to HOs3(CO)8[μ-PhP(C6H4-μ2,η1)CH2PPh2]: Experimental and DFT Evidence for the Participation of Agostic C−H and π-Aryl Intermediates at an Intact Triosmium Cluster

The mechanism for the stepwise conversion of Os3(CO)10(dppm) to HOs3(CO)9[μ-PhP(C6H4)CH2PPh2] and HOs3(CO)8[μ-PhP(C6H4-μ2,η1)CH2PPh2] has been investigated. The octacarbonyl cluster HOs3(CO)8[μ-PhP(C6H4-μ2,η1)CH2PPh2] is in rapid equilibrium with the isomer containing a metalated phenyl ring that is bound to a single osmium, HOs3(CO)8[μ-PhP(C6H4-η1)CH2PPh2], which in turn captures CO to give HOs3(CO)9[μ-PhP(C6H4)CH2PPh2] in a reaction that is first-order in cluster and CO with a rate constant of 23.9(3) × 10−3 M−1 s−1 at 288 K. The kinetics for the transformation of HOs3(CO)9[μ-PhP(C6H4)CH2PPh2] to Os3(CO)10(dppm) have been studied in toluene over the temperature range 317−340 K and found to be first-order in starting cluster and independent of CO. Important insight into the reductive coupling process was obtained from the carbonylation kinetics employing DOs3(CO)9[μ-(Ph-d2)P(C6H3D)CH2PPh2-d4], which was prepared from Os3(CO)10(dppm-d8) and where all of the ortho sites on the aryl groups contained deuteri...

α-Diimine Ligand Coordination and C–H Bond Activation in the Reaction of Os3(CO)10(MeCN)2 with 6-R-2,2′-Bipyridine (where R = Et, Ph): X-ray Diffraction Structures of the Ortho-Metalated Hydride Clusters HOs3(CO)9(N2C10H6-6-R)

The reactivity of the labile cluster Os3(CO)10(MeCN)2 (1) with the monofunctionalized heterocyclic ligands 6-R-2,2′-bipyridine (where R = Et, Ph) has been investigated. The alkyl-substituted heterocycle 6-Et-2,2′-bipyridine reacts with 1 in refluxing CH2Cl2 to give an isomeric mixture of HOs3(CO)9(N2C12H11) due to cyclometalation of the side-chain ethyl group (2) and ortho metalation of the unsubstituted bipyridine ring (3). The solid-state structure of the latter cluster, HOs3(CO)9(N2C10H6-6-Et) (3), has unequivocally established the site of the C-H bond activation in the product. Treatment of 1 with the aryl-substituted ligand 6-Ph-2,2′-bipyridine proceeds similarly with ortho metalation at the ancillary phenyl group and the C-6′ ortho site of the unsubstituted bipyridine ring, as verified by 1H NMR spectroscopy. The X-ray diffraction structure of the thermodynamically more stable bipyridine-metalated cluster HOs3(CO)9(N2C10H6-6-Ph) (5) has been determined. The course of these reactions is discussed with respect to our recent study involving the reaction of cluster 1 with the ligand 6-Me-2,2′-bipyridine. The reaction between the labile cluster Os3(CO)10(MeCN)2 (1) and the monofunctionalized heterocyclic ligand 6-Et-2,2′-bipyridine proceeds readily at room temperature to furnish an isomeric mixture of the cyclometalated and ortho-metalated hydride-bridged clusters HOs3(CO)9(N2C12H11) (2 and 3). Treatment of 1 with 6-Ph-2,2′-bipyridine also yields two distinct hydride-containing clusters that result from independent ortho-metalation paths involving the 6-phenyl substituent and unsubstituted bipyridine group. The bipyridine-derived ortho metalation attendant in the new clusters HOs3(CO)9(N2C10H6-6-Et) (3) and HOs3(CO)9(N2C10H6-6-Ph) (5) has been established by X-ray crystallography.

Reaction of 6-Methyl-2,2′-bipyridine with 1,2-Os3(CO)10(MeCN)2: Syntheses, Reductive Elimination/Ligand Displacement Kinetics, and X-ray Diffraction Structures of the Isomeric Clusters HOs3(CO)9(μ2-N2C11H9) and H2Os3(CO)8(μ3-N2C11H8)

Treatment of Os3(CO)10(MeCN)2 (1) with the heterocyclic ligand 6-methyl-2,2′-bipyridine (6-Me-2,2′-bpy) at room temperature leads to the formation of the isomeric hydride-bridged clusters HOs3(CO)9(μ2-CH2N2C10H7) (2) and HOs3(CO)9(μ2-N2C11H9) (3). The cyclometalation of the ancillary 6-Me group in 2 and the ortho metalation of the nonsubstituted pyridyl ring in 3 have been confirmed by spectroscopic and crystallographic methods. Thermolysis of 2 leads to the formation of 3 and the dihydride cluster H2Os3(CO)8(μ3-N2C11H8) (4); the latter cluster, whose structure has been crystallographically determined, derives from a formal loss of CO and C−H bond activation of the methylene moiety in 2. Heating 2 in the presence of ligand-trapping agents proceeds with the release of the 6-Me-2,2′-bpy ligand and formation of Os3(CO)9L3 [where L = CO, P(OMe)3]. The kinetics for the reaction between 2 and added ligand have been investigated by UV−vis and NMR spectroscopies and found to be first-order in starting cluster and independent of the incoming ligand. Parallel kinetic experiments employing the deuterated cluster DOs3(CO)9(μ2-CD2N2C10H7) (2-d3), which was prepared from cluster 1 and 6-Me-d3-2,2′-bpy, confirm the existence of a primary kinetic isotope effect (KIE) of 1.78 at 323 K. The KIE data and the calculated activation parameters [ΔH⧧ = 21.7(4) kcal/mol; ΔS⧧ = −13(1) eu] are strongly suggestive of a reaction scheme involving a rate-limiting reductive coupling of the bridging hydride ligand and cyclometalated alkyl moiety in 2 to furnish a putative sigma complex containing an intact methyl group bound to the Os3 cluster, prior to the generation of the unsaturated cluster Os3(CO)9(μ-N2C11H10). Thermolysis of 3 in the presence of added P(OMe)3 does not furnish free 6-Me-2,2′-bpy but proceeds by a ligand-induced displacement of the methyl-substituted pyridyl ring and formation of the cluster compound HOs3(CO)9[P(OMe)3](μ2-N2C11H9) (5). The kinetics for the reaction between 3 and P(OMe)3 have been studied over the temperature range 333−356 K, and on the basis of the observed activation parameters [ΔH⧧ = 13.0(3) kcal/mol; ΔS⧧ = −30(1) eu] and the first-order dependence on the cluster and ligand, an associative process that involves P(OMe)3 ligand attack on the cluster and release of the methyl-substituted pyridyl ring in the rate-limiting step is proposed.

Photochemical reactivity of the triosmium cluster 1,1-Os3(CO)10(bpcd) in the presence of P(OEt)3 and X-ray crystal structure of HOs3(CO)7[P(OEt)3][μ-{PPh(C6H4)} C=C(PPh2)C(O)CH2C(O)]: Unexpected ortho metalation and cluster face capping by a diphosphine ligand

Photochemical activation of the bpcd-chelated cluster 1,1-Os3(CO)10(bpcd) (1) in the presence of P(OEt)3 furnishes the simple substitution product 1,1,2-Os3(CO)9[P(OEt)3](bpcd) (2) initially, followed by the formation of the hydride cluster HOs3(CO)7[P(OEt)3][μ-{PPh(C6H4)}C=C(PPh2)C(O)CH2C(O)] (3). Both new clusters were isolated and characterized in solution by IR and NMR (1H and 31P) spectroscopies, with the solid-state structure of cluster 3 determined by X-ray diffraction analysis. Cluster 3 crystallizes in the triclinic space group P−1, a=9.366(2) A, b=14.182(4) A, c=17.672(4) A, α=87.787(4)°, β=78.488(4)°, γ=71.785(4)°, V=2184.1(9) A3, Z=2, D cacl=2.123 Mg/m3; R=0.0488, R w=0.1059 for 8527 observed reflections with I > 2σ(I). The presence of the seven-electron ligand μ-P{Ph(C6H4)}C=C(PPh2)C(O)CH2C(O) that caps one of the triangular faces in 3 through both phosphine moieties, the π bond of the dione ring, and an ortho-metalated aryl ligand is established.

Diphosphine Isomerization and C−H and P−C Bond Cleavage Reactivity in the Triosmium Cluster Os3(CO)10(bpcd): Kinetic and Isotope Data for Reversible Ortho Metalation and X-ray Structures of the Bridging and Chelating Isomers of Os3(CO)10(bpcd) and the Benzyne-Substituted Cluster HOs3(CO)8(μ3-C6H4)[μ2,η1-PPhCC(PPh2)C(O)CH2C(O)

The coordination and reactivity of the diphosphine ligand 4,5-bis(diphenylphosphino)-4-cyclopentene-1,3-dione (bpcd) with Os3(CO)10(MeCN)2 (1) has been explored. The initial substitution product 1,2-Os3(CO)10(bpcd) (2b) undergoes a nondissociative, intramolecular isomerization to furnish the bpcd-chelated cluster 1,1-Os3(CO)10(bpcd) (2c) over the temperature range of 323−343 K. The isomerization reaction is unaffected by trapping ligands, yielding the activation parameters ΔH⧧ = 25.0(0.7) kcal/mol and ΔS⧧ = −2(2) eu. Thermolysis of 2c in refluxing toluene gives the hydrido cluster HOs3(CO)9[μ-(PPh2)CC{PPh(C6H4)}C(O)CH2C(O)] (3) and the benzyne cluster HOs3(CO)8(μ3-C6H4)[μ2,η1-PPhCC(PPh2)C(O)CH2C(O)] (4). Time−concentration profiles obtained from sealed-tube NMR experiments starting with either 2c or 3 suggest that both clusters are in equilibrium with the unsaturated cluster 1,1-Os3(CO)9(bpcd) and that the latter cluster serves as the precursor to the benzyne-substituted cluster 4. The product composition...

Unusual C–H bond activation—aldol condensation of aromatic aldehydes with the methyl group of a carbene-like triosmium cluster

Reactions of the triosmium cluster [HOs3(CO)10(η1:η1-OC4H2CCH3)] with a series of aromatic aldehydes under mild conditions result in condensation of the ligand methyl group with the aldehyde CO moiety to give typical aldol condensation products.

Reactions of Diacetylene Ligands with Trinuclear Clusters. 3. Cyclization of Diynes with β-Amino Moieties on the Metal Core of [H2Os3(CO)10

Reactions of [H2Os3(CO)10] with the substituted diynes R-C2-C2-R' (1, R = Ph, R' = CH2NHPh; 2, R = Ph, R' = CH2NHCH2Ph; 3, R = R' = CH2NHPh) afford the clusters [HOs3(CO)10(L)] (L = {-1:2-PhCH2C(H)=C-C(H)=C-NPh} (4), {-1:2-PhCH2C(H)=C-C(H)=C-NCH2Ph} (5), and {-1:1-CH3CC=C-C(H)=C(H)-NPh} (6), which have been characterized by single-crystal X-ray diffraction analyses as well as by various spectroscopic methods. In clusters 4-6, the starting diynes 1-3 have been rearranged to form substituted pyrrolyl rings which bridge two osmium atoms in 1:2- (4, 5) or 1:1- (6) coordination modes depending on the nature of substituents in 1-3. A possible reaction pathway for the diyne cyclization reactions that yield 4-6 involves initial transfer of a hydride onto a coordinated diyne followed by a series of 1,3-shifts and subsequent nucleophilic attack of the nitrogen on the third carbon atom of the diyne system to afford the five-membered pyrrolyl ring. Cluster 6 and its previously characterized furanyl analogue [HOs3(CO)10{-1:1-(OCHCHCC)-C-CH3)}] (7) undergo facile thermal transformation accompanied by the loss of a CO ligand to give the clusters [HOs3(CO)9{3,3-CH3CC=C-C(H)=C(H)-NPh}] (8) and [HOs3(CO)9{3,3-(OCH=CHC=CCCH3)}] (9). In both 8 and 9, single-crystal X-ray analysis revealed the presence of pentagonal pyramid cluster cores containing three osmium and three carbon atoms. (Less)

Oxidative Addition of Group 14 Hydrides to an Unsaturated Metal Cluster. Kinetics of Addition of HER3 (ER3 = SiEt3, SiPh3, GeBu3, SnBu3, SnPh3) to H2Os3(CO)10

The kinetics and mechanism of oxidative addition of HER3 = HSiEt3, HGeBu3, HSnBu3, HSnPh3 to the unsaturated cluster H2Os3(CO)10, initially forming H3Os3(CO)10(ER3), are reported. For HSiEt3 the addition is readily reversible, with an equilibrium constant of 100 M-1 at 303 K. In each case the rate law for the forward reaction is first-order in both reagents. Rate constants (M-1 s-1) at 303 K are as follows: HSnBu3 (23) > HSnPh3 (1.5) > HGeBu3 (0.15) > HSiEt3 (3.8 × 10-3). Comparisons are made to additions of group 14 element hydrides to 16-electron Ir(I) complexes. The reaction with HSiPh3, which forms H3Os3(CO)9(SiPh3) and further addition products, was also examined.

Mercury–osmium carbonyl clusters resulting from facile Hg–C bond cleavage: reactions of [Os3H2(CO)10] with [Hg(CCPh)2] and [RHgCCHgR](R = Ph, Me or Et)

Reaction of the unsaturated cluster [Os3H2(CO)10] with Hg(CCPh)2 afforded two new Os–Hg clusters cis-[Os(CO)4{(µ-Hg)Os3(CO)10(µ-η2-CHCHPh)}2]1 and [{Os3(CO)10(µ-η2-CHCHPh)}2(µ4-Hg)]2 in 30 and 20% yield, respectively. Cluster 1 consists of two (µ-Hg)Os3(CO)10(µ-η2-CHCHPh) subunits bonded to a central Os(CO)4 moiety in the cis configuration which under ambient conditions converts into 2 over 3–5 d with the extrusion of a HgOs(CO)4 unit. Cluster 2 comprises two skewed Os–Hg metal butterflies sharing a common wingtip Hg atom. In refluxing tetrahydrofuran (66 °C)2 underwent redistribution with the symmetrical mercurials [Hg{M(CO)3(η5-C5H5)}2](M = Cr, Mo or W) to afford respectively the heterometallic clusters [{Os3(CO)10(µ-η2-CHCHPh)}(µ3-Hg){M(CO)3(η5-C5H5)}](M = Cr 3, Mo 4 or W 5) in moderate yield. Alternatively, 3–5 can be obtained more readily from the reaction of cluster 1 with the corresponding symmetric mercurials at room temperature. Reactions of [Os3H2(CO)10] with [RHgCCHgR](R = Ph, Me or Et) afforded the clusters [{Os3(CO)10(µ-η2-CHCH2)}(µ4-Hg){Os3(CO)10(µ-H)}]6(12%) and [{Os3(CO)10(µ-η2-CHCH2)}2(µ4-Hg)]7(25%). Cluster 7 is isostructural with 2, whilst 6 bears a central Hg atom connecting two structurally different osmium triangles. Clusters 1, 2, 6 and 7 all result from Hg–C bond cleavage of the parent organomercury species, hence the generality of this cleavage is demonstrated. The new clusters 1, 2, 4, 6 and 7 have been fully characterised by both spectroscopic and crystallographic techniques.

ChemInform Abstract: Kinetics of Reactions of Hydrogen with (Os3(CO)11(NCMe)) and (Os3(CO)10(NCMe)2)

ChemInformVolume 21, Issue 8 Organoelement Compounds ChemInform Abstract: Kinetics of Reactions of Hydrogen with (Os3(CO)11(NCMe)) and (Os3(CO)10(NCMe)2) R. H. E. HUDSON, R. H. E. HUDSON J. Tuzo Wilson Lab., Univ. Toronto, Mississauga, Ont., Can. L5L 1C6Search for more papers by this authorA. J. POE, A. J. POE J. Tuzo Wilson Lab., Univ. Toronto, Mississauga, Ont., Can. L5L 1C6Search for more papers by this authorC. N. SAMPSON, C. N. SAMPSON J. Tuzo Wilson Lab., Univ. Toronto, Mississauga, Ont., Can. L5L 1C6Search for more papers by this authorA. SIEGEL, A. SIEGEL J. Tuzo Wilson Lab., Univ. Toronto, Mississauga, Ont., Can. L5L 1C6Search for more papers by this author R. H. E. HUDSON, R. H. E. HUDSON J. Tuzo Wilson Lab., Univ. Toronto, Mississauga, Ont., Can. L5L 1C6Search for more papers by this authorA. J. POE, A. J. POE J. Tuzo Wilson Lab., Univ. Toronto, Mississauga, Ont., Can. L5L 1C6Search for more papers by this authorC. N. SAMPSON, C. N. SAMPSON J. Tuzo Wilson Lab., Univ. Toronto, Mississauga, Ont., Can. L5L 1C6Search for more papers by this authorA. SIEGEL, A. SIEGEL J. Tuzo Wilson Lab., Univ. Toronto, Mississauga, Ont., Can. L5L 1C6Search for more papers by this author First published: February 20, 1990 https://doi.org/10.1002/chin.199008285Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume21, Issue8February 20, 1990 RelatedInformation

Reaction of Os3H2(CO)9(C6H4) with diphenylacetylene: the formation and structural characterisation of Os3(CO)7(C6H4)[PhCC(H)Ph

The reaction of the 'benzyne' cluster Os3H2(CO)9(C6H4) with diphenylacetylene affords the new compound Os3(CO)7(C6H4)[PhCC(H)Ph]2; a single crystal X-ray analysis of this product shows that two PhCC(H)Ph units and the benzyne moiety are bonded to the Os3 core as separate ligands, and that under these conditions there is no ligand condensation.

Kinetics of reactions of hydrogen with [Os3(CO)11(NCMe)] and [Os3(CO)10(NCMe)2

The kinetics of reactions of [Os3(CO)11(NCMe)] with H2 and CO, and of [Os3(CO)10(NCMe)2] with H2, have been studied in the presence of free MeCN. The reactions involve slow dissociation of MeCN from the clusters and subsequent competition between MeCN and H2 or CO for the vacant co-ordination site on the intermediate cluster. Rate constants for nucleophilic attack on [Os3(CO)11] are in the order MeCN > PPh3≈ CO > H2 and temperature-dependence studies provide activation enthalpy and entropy differences. These, together with a value of 1.34 ± 0.03 for the deuterium kinetic isotope effect, are consistent with a simple three-centre transition state for reaction of [Os3(CO)11] with H2. The cluster [Os3H2(CO)10] reacts with MeCN to form [Os3H2(CO)10(NCMe)] and equilibrium data for this reaction have been obtained.

Synthesis and characterisation of the tetranuclear phosphinidene clusters [Os3MH2(CO)12(PR)](M = Os, R = Ph or cyclo-C6H11; M = Ru, R = cyclo-C6H11) and the crystal and molecular structure of [Os4(µ-H)2(CO)12(µ3-PC6H11)

Reaction of the phosphinidene-capped cluster [Os3H2(CO)9(PR)](R = Ph or cyclo-C6H11) with the binary carbonyl [M3(CO)12](M = Ru or Os), under reflux in nonane, affords the tetranuclear clusters [Os3MH2(CO)12(PR)][(1) M = Os, R = Ph; (2) M = Os, R = cyclo-C6H11; (3) M = Ru, R = cyclo-C6H11] together with the previously reported penta- and hexa-nuclear clusters [Os3M2(CO)15(PR)] and [Os3M3(CO)17(PR)]. The structure of (2) has been established by an X-ray analysis which shows that there are two independent but structurally similar tetranuclear clusters per asymmetric unit. Within each molecule the four Os atoms adopt a ‘butterfly’ arrangement, consistent with the 62-electron count, and the phosphinidene ligand bridges an open triangular face defined by one ‘bridge’ and two ‘wingtip’ Os atoms. The 12 carbonyl ligands are terminal, and the two hydrides bridge the two remaining ‘hinge’ to ‘wingtip’ Os–Os edges. Solution 1H and 31P n.m.r. spectra for clusters (1)–(3) are consistent with this ground-state structure, and the positions of the hydrides are confirmed by the observation of 187Os satellites in the 1H n.m.r. spectra of (1) and (2). The cluster (3) exists as a mixture of three inseparable isomers which arise from the juxtaposition of the Ru atom around the three inequivalent positions of the metal ‘butterfly’. The existence of these isomers is confirmed by a detailed analysis of the 1H and 31P n.m.r. spectra of this complex.