Formation and isomerization of cis,cis-Ir(H)2(--Ph)(CO)(PPh3)2 and cis,cis-Ir(H)(--Ph)2(CO)(PPh3)2 in oxidative addition of hydrogen and phenylacetylene to trans-Ir(CO)(--Ph)(PPh3)2

Oxidative addition of H–R (H--Ph and H₂) to trans-Ir(--Ph)(CO)(PPh₃)₂ (2) gives the initial products, cis, cis-Ir(H)(--Ph)₂(CO)(PPh₃)₂ (3a) and cis, cis-Ir(H)₂(--Ph)(CO)(PPh₃)₂ (3b), respectively. Both cis-bis(PPh₃) complexes, 3a and 3b undergo isomerization to give the trans-bis(PPh₃) complexes, trans, trans-Ir(H)(--Ph)₂(CO)(PPh₃)₂ (4a) and cis, trans-Ir(H)₂(--Ph)(CO)(PPh₃)₂ (4b). The isomerization, 3b→4b is first order with respect to 3b with k₁=6.37×10⁻⁴ s⁻¹ at 25°C under N₂ in CDCl₃. The reaction rate (k₁) seems independent of the concentration of H₂. A large negative entropy of activation (ΔS^≠=−24.9±5.7 cal deg⁻¹ mol⁻¹) and a relatively small enthalpy of activation (ΔH^≠=14.5±3.3 kcal mol⁻¹) were obtained in the temperature range 15∼35°C for the isomerization, 3b→4b under 1 atm of H₂.     

Microwave Promoted Oxidative Addition Reactions of Os3(CO)12: Efficient Syntheses of Triosmium Clusters of the Type Os3(μ-X)2(CO)10 and Os3(μ-H)(μ-OR)(CO)10

Microwave heating allows for the high-yield, one-step synthesis of the known triosmium complexes Os₃(μ-Br)₂(CO)₁₀ (1), Os₃(μ-I)₂(CO)₁₀ (2), and Os₃(μ-H)(μ-OR)(CO)₁₀ with R = methyl (3), ethyl (4), isopropyl (5), n-butyl (6), and phenyl (7). In addition, the new clusters Os₃(μ-H)(μ-OR)(CO)₁₀ with R = n-propyl (8), sec-butyl (9), isobutyl (10), and tert-butyl (11) are synthesized in a microwave reactor. The preparation of these complexes is easily accomplished without the need to first prepare an activated derivative of Os₃(CO)₁₂, and without the need to exclude air from the reaction vessel. The syntheses of complexes 1 and 2 are carried out in less than 15 min by heating stoichiometric mixtures of Os₃(CO)₁₂ and the appropriate halogen in cyclohexane. Clusters 3–6 and 8–10 are prepared by the microwave irradiation of Os₃(CO)₁₂ in neat alcohols, while clusters 7 and 11 are prepared from mixtures of Os₃(CO)₁₂, alcohol and 1,2-dichlorobenzene. Structural characterization of clusters 2, 4, and 5 was carried out by X-ray crystallographic analysis. High resolution X-ray crystal structures of two other oxidative addition products, Os₃(CO)₁₂I₂ (12) and Os₃(μ-H)(μ-O₂CC₆H₅)(CO)₁₀ (13), are also presented.     

ESR study of reactivity of the complex (η2-C60)Os(CO)(PPh3)2(CNBut) toward free radicals

Addition of the ^·P(O)(OPrⁱ)₂, Me^·, Et^·, ^·Bu^t, and Cl₃C^· radicals to the (ν²-C₆₀)Os(CO)-(PPh₃)₂(CNBu^t) complex (1) was studied by ESR spectroscopy. The spectral parameters of the spin-adducts of these radicals with complex 1 were determined. The predominant direction of the attack by the ^·P(O)(OPrⁱ)₂, ^·Bu^t, and Cl₃C^· radicals are the cis-1 and cis-2 bonds of the fullerene molecule. The stability of the spin-adducts depends substantially on the nature of the added radical. The addition rate constants of the ^·P(O)(OPrⁱ)₂, ^·But, and Cl₃C^· radicals to complex 1 and the dimerization rate constants for these spin-adducts were determined. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 301–307, February, 2008.     

Cluster synthesis. 42. The synthesis and crystal and molecular structures of the sulfur-bridged platinum-ruthenium carbonyl cluster compounds PtRu3(CO)9 L(PPh3)(μ3-S)2 (L=CO,PPh3) and PtRu4(CO)12(PPh3)(μ4-S)2

Two new mixed metal cluster complexes PtRu₃(CO)₁₀(PPh₃)(₃-S)₂,3 14% yield and PtRu₃(CO)₉(PPh₃)₂(₃-S)₂,4 23% yield were obtained from the reaction of Ru₃(CO)₉(₃-S)₂,1 with Pt(PPh₃)₂(C₂H₄) at 0°C. The cluster of4 consists of a spiked triangle of four metal atoms with two triply bridging sulfido ligands. The reaction of Ru₄(CO)₁₁(₄-S)₂,2 with Pt(PPh₃)₂(C₂H₄) yielded the expanded mixed-metal cluster complex PtRu₄(CO)₁₂(PPh₃)(₄-S)₂,5 in 12% yield. The structure of the cluster5 can be described as a pentagonal bipyramid of five metal atoms and two sulfido ligands with one metal-metal bond missing. Compounds4 and5 were characterized by a single-crystal X-ray diffraction analyses.     

New triosmium–iridium clusters: Synthesis and molecular structure of [Os3Ir2(Cp1)2(μ-OH)(μ-CO)2(CO)8Cl] (1), [Os3IrCp1(μ-OH)(CO)10Cl] (2), [Os3IrCp1(μ-H)(μ-Cl)(η3,μ3-C5H2N(NH2)Br)(CO)9] (3) and [Os3IrCp1(μ-Cl)2(η2,μ3-C5H3N(NH)Br)(CO)7] (4)

The trinuclear osmium carbonyl cluster, [Os₃(CO)₁₀(MeCN)₂], is allowed to react with 1 equiv. of [IrCp¹Cl₂]₂ (Cp¹ = pentamethylcyclopentadiene) in refluxing dichloromethane to give two new osmium–iridium mixed-metal clusters, [Os₃Ir₂(Cp¹)₂(μ-OH)(μ-CO)₂(CO)₈Cl] (1) and [Os₃IrCp¹(μ-OH)(CO)₁₀Cl] (2), in moderate yields. In the presence of a pyridyl ligand, [C₅H₃N(NH₂)Br], however, the products isolated are different. Two osmium–iridium clusters with different coordination modes of the pyridyl ligand are afforded, [Os₃IrCp¹(μ-H)(μ-Cl)(η³,μ₃-C₅H₂N(NH₂)Br)(CO)₉] (3) and [Os₃IrCp¹(μ-Cl)₂ (η²,μ₃-C₅H₃N(NH)Br)(CO)₇] (4). All of the new compounds are characterized by conventional spectroscopic methods, and their structures are determined by single-crystal X-ray diffraction analysis.     

New routes to carbonyl complexes of general formula [RuCl2(CO)(S)(PPh3)2] (S = DMA,DMF, DMSO): crystal structure of [RuCl2(CO)(DMA)(PPh3)2] · 1/2CH2Cl2

The compound [RuCl₂(CO)(DMA)(PPh₃)₂] [DMA = dimethylacetamide] was obtained from [RuCl₃(PPh₃)₂-(DMA)] · DMA and CO in DMA. Orange crystals of [RuCl₂(CO)(DMA)(PPh₃)₂] · 1/2CH₂Cl₂ were isolated by slow evaporation of a CH₂Cl₂/DMA solution and its structure was determined by single crystal X-ray diffraction. The analogous compounds containing DMF and DMSO were obtained from the precursor ttt-[RuCl₂(CO)₂(PPh₃)₂]. Characterization of the other complexes is based on i.r. and n.m.r. spectroscopy, including ³¹P{¹H} data.     

Synthesis and structure of three isomeric cluster complexes (μ-H)Os3μ-O2CC5H4Mn(CO)3(PPh3)2(CO)8

The reaction of (μ-H)Os₃μ-O₂CC₅H₄Mn(CO)₃(CO)₁₀ with PPh₃ in the presence of Me₃NO gave mono- and disubstituted heterometallic complexes (μ-H)Os₃μ-O₂CC₅H₄Mn(CO)₃(PPh₃)(CO)₉ and (μ-H)Os₃μ-O₂CC₅H₄Mn(CO)₃ (PPh₃)₂(CO)₈. Crystal structure determination was performed for three isomeric cluster complexes (μ-H)Os₃μ-O₂CC₅H₄Mn(CO)₃(PPh₃)₂(CO)₈, which are both geometrical and conformational isomers differing in color. The geometrical isomerism is due to the attachment of the PPh₃ group at different vertices of the Os₃ triangle relative to the O₂CC₅H₄Mn(CO)₃ bridging ligand. The conform ational isomerism implies that the molecules have the same arrangement of ligands and differ only in the values of bond angles between the planar fragments of the clusters.     

Osmium(IV) Binuclear Nonelectrolytic Oxo-Bridged Carboxylates. Molecular Structure of [Os2 IV(μ-O)(μ-O2CCCl3)2Cl4(PPh3)2] · CH2Cl2

The reactions between trans-[Os^VIO₂Cl₂L₂] (L = PPh₃, AsPh₃, SbPh₃) and carboxylic acids RCO₂H (R = CH₃, C(CH₃)₃, CH₂Cl, CCl₃, CF₃) are studied. The resulting binuclear compounds were found to have the general formula [Os₂ ^IV(-O)(-O₂CR)₂Cl₄(L)₂] (L = PPh₃; R = CH₃, C(CH₃)₃, CH₂Cl, CCl₃, CF₃, and L = AsPh₃; R = CH₃, CH₂Cl, CCl₃, CF₃). X-ray diffraction analysis revealed that the [Os₂ ^IV(-O)(-O₂CCCl₃)₂Cl₄(PPh₃)₂] · CH₂Cl₂ complex crystallizes in a triclinic system with space group P ; a = 10.747(2) Å, b = 19.291(4) Å, c = 24.614(5) Å, = 100.08(3)°, = 90.63(3)°, = 97.05(3)°, V = 4983.5(17) ų, Z = 4. The Os(-O)Os angle is 142.2(7)°. The interaction of trans-[Os^VIO₂Cl₂(SbPh₃)₂] with all the acids under study is attended by intramolecular redox reaction resulting in SbCl₂Ph₃.     

Synthesis and X-ray crystal structure of the electron-deficient metal carbonyl cluster [Os3(CO)5(μ3-H)(μ-H)(μ-PtBu2)2(μ-Ph2PCH2PPh2)]

The reaction of [Os₃(CO)₁₀(μ-dppm)] (1) with ^tBu₂PH in refluxing diglyme results in the electron-deficient metal cluster complex [Os₃(CO)₅(μ₃-H)(μ-P^tBu₂)₂(μ-dppm)] (2) (dppm = Ph₂PCH₂PPh₂) in good yields. The molecular structure of 2 has been established by a single crystal X-ray structure analysis. In contrast to the known homologue [Ru₃(μ-CO)(CO)₄(μ₃-H)(μ-H)(μ-P^tBu₂)₂(μ-dppm)] (3), no bridging carbonyl ligand was found in 2. The electronically unsaturated cluster 2 does not react with carbon monoxide under elevated pressure, therefore 2 seems to be coordinatively saturated by reason of the high steric demands of the phosphido ligands.     

Reactions of [Rh(Tp*)(PPh3)2] (Tp*=hydrotris(3,5-dimethylpyrazolyl)-borate) involving fragmentation or loss of Tp*. Structures of [Rh(Cl)2(H)(PPh3)2(pz*)], [(PPh3)2Rh(μ-SC6F5)2Rh(SC6F5)(H)(PPh3)(pz*)] (pz*=3,5-dimethylpyrazole) and [{Rh(Cl)2(PPh3)2}2Hg]

The complex [Rh(Tp*)(PPh₃)₂] reacts with dichloromethane to give [Rh(Cl)(H)₂(PPh₃)₂(pz*)] (1) and [Rh(Cl)₂(H)(PPh₃)₂(pz*)] (2), with C₆F₅SH to give [(PPh₃)₂Rh(μ-SC₆F₅)₂Rh(SC₆F₅)(H)(PPh₃)(pz*)] (3) and with HgCl₂ to give [{Rh(Cl)₂(PPh₃)₂}₂Hg] (4), all under mild conditions. The crystal structures show that 2 has a slightly distorted octahedral geometry, 3 has approximately square planar Rh(I) and octahedral Rh(III) geometries, with an angle of 160.7° between the two RhS₂ planes and 4 has rhodium with a square pyramidal geometry where mercury occupies a position at the apex of the pyramid; the Rh–Hg–Rh geometry is linear and, with respect to the Rh–Hg–Rh axis, the ligands (Cl, PPh₃) on one rhodium are offset by approximately 42° relative to their counterparts on the second rhodium. In 2 an intramolecular hydrogen bond exists between the pyrazole NH and one of the chloride ligands. Structure 4 is unusual in that it contains an unsupported mercury bridge.     

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).     

Preparation and reactivity of metal-containing monomers 53. Synthesis and stability of a cluster monomer (μ-H)Os3(μ-OCNMe2)(CO)9PPh2CH2CH=CH2 in solution

The stability of the complex (μ-H)Os₃(μ-OCNMe₂)(CO)₉PPh₂CH₂CH=CH₂ (1), which contains a free unsaturated functional group in the terminal ligand PPh₂CH₂CH=CH₂, with respect to isomerization, chelation of the ligand, and other transformations in solutions was examined. No transformations of complex1 were observed in the course of synthesis from (μ-H)Os₃(μ-OCNMe₂)(CO)₉NMe₃ or upon heating in solution. Complex1 as well as complexes (μ-H)Os₃(μ-OCNMe₂)(CO)₉PHPh₂ and (μ-H)Os₃(μ-OCNMe₂)(CO)₉PPh₃, which were formed as admixtures, were isolated in the solid state and identified by¹H,¹H-{³¹P}, and¹H-{¹H} NMR, IR, and Raman spectroscopy and mass spectrometry. For Part 52, see Ref. 1. Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1455–1460, August, 2000.     

The oxidative addition of SnCl4 to [W(CO)4(NCMe)(PPh3)]. The X-ray crystal structure of [WH(CO)3(NCMe)(PPh3)2][SnCl5·MeOH]

The oxidative addition reaction of SnCl₄ with [W(CO)₄(NCMe)(PPh₃)] in acetonitrile gives a mixture of seven-coordinate tungsten(II) compounds: [WCl(SnCl₃)(CO)₃(NCMe)(PPh₃)] (1), [WCl₂(CO)₃(NCMe)(PPh₃)] (2), [WCl(SnCl₃)(CO)₂(NCMe)₂(PPh₃)] (3), and [WCl₂(CO)₂(NCMe)₂(PPh₃)] (4) identified by IR and NMR (¹H, ¹³C{¹H}, and ³¹P{¹H}) studies. Treatment of [W(CO)₄(NCMe)(PPh₃)] with 1 equiv. of SnCl₄ in CH₂Cl₂ solution besides compounds 1 and 2 also gives ionic species such as [HPPh₃]⁺ and [SnCl₆]²⁻ and cationic tungsten(II) complexes. The crystal structure of one of these, [WH(CO)₃(NCMe)(PPh₃)₂][SnCl₅·MeOH] (5), has been established by single-crystal X-ray diffraction. The IR, ¹H, ¹³C{¹H} and ³¹P{¹H} spectra of 5 are also described and can be correlated with the crystallographically observed geometry. A notable feature of 5 is the presence of an agostic interaction of the hydride ligand with one of the carbonyl ligands.     

The oxidative addition of 1-haloalkanes to monomeric trans-[Rh(X(CO)(PR3)2] (X  Cl,Br; R  aryl) and dimeric trans-[Rh(μ-X)(CO)(PPh3)]2 (XCl,I)

The oxidative addition of 1-bromopropane to trans-[RhBr(CO){P(p-EtC₆H₄)₃}₂] has been found to follow pseudo first-order kinetics and give only an acylrhodium(III) product. The reaction is not catalysed by added bromide ion in chloroform solution, indicating that an anionic intermediate such as [RhBr₂(CO){P(p-EtC₆H₄)₃}]⁻ does not play an important part in this reaction. The oxidative addition of iodomethane to trans-[Rh(μ-X)(CO)(PPh₃)]₂ (X  Cl and I) is pseudo first-order, the reactivity increasing on replacing chloride by iodide.     

Protonation and acylation of the heterometallic complexes (μ-H)Os3(μ-O2CC5H4FeCp)(CO)10 and Fe{(μ-O2CC5H4)(μ-H)Os3(CO)10}2

The reactions of the heterometallic complexes (-H)Os₃(-O₂CC₅H₄FeCp)(CO)₁₀ (1) and Fe{(-O₂CC₅H₄)(-H)Os₃(CO)₁₀}₂ (2) with CF₃COOH, CF₃SO₃H, and AcCl were studied. The reaction of 1 with CF₃COOH involves interaction with the Cp ligands, protonation of the O atom of the bridging carboxylate group, and oxidative degradation of the complex. At low concentrations, CF₃SO₃H protonates the O atom of the bridging carboxylate group, while at high concentrations, degradation of the complex takes place. The reaction of complex 2with either CF₃COOH or low concentrations of CF₃SO₃H results in successive elimination of two [(-H)Os₃(CO)₁₀] cluster fragments due to protonation of the O atoms of the carboxylate groups. In the case of high CF₃SO₃H concentrations, the Os—Os bonds of both cluster fragments of 2 are also protonated to give the [Fe{(-O₂CC₅H₄)(-H)₂Os₃(CO)₁₀}₂]²⁺ dication. The Friedel—Crafts acylation of 1 takes place only when a large excess of AcCl and AlCl₃ is used to give two new complexes, (-H)Os₃(-O₂CC₅H₄FeC₅H₄C(O)CH₃)(CO)₁₀ and (-H)Os₃(-O₂CC₅H₃C(O)CH₃FeCp)(CO)₁₀ in a 2 : 1 ratio.     

The insertion of cycloheptatriene and cyclohepta-1,3-diene into the RuH bond of RuHCl(PPh3)3 to give Ru(η5-C7H9)Cl(PPh3)2 and Ru(η3-C7H11)Cl(PPh3)2

RuHCl(PPh₃)₃ reacts quantitatively with cycloheptatriene in CH₂Cl₂ at 35°C in 15 min to give Ru(η⁵-C₇H₉)Cl(PPh₃)₂ and PPh₃. The major isomer adopts a conformation with inequivalent phosphorus ligands and no plane of symmetry through the C₇H₉ ligand, but rapid intramolecular scrambling with δG³ = 10.6 kcal mol⁻¹ results in an averaged ¹H, ¹³C, and ³¹P NMR spectrum at room temperature. RuHCl(PPh₃)₃ reacts with cyclohepta-1,3-diene to give initially Ru(η³-C₇H₁₁)Cl(PPh₃)₂, but in a subsequent reaction this is dehydrogenated to give Ru(η⁵-C₇H₉)Cl(PPh₃)₂.     

The nido–osmaboranes [2,2,2-(CO)(PPh3)2-nido-2-OsB5H9] and [6,6,6-(CO)(PPh3)2-nido-6-OsB9H13]

The structural characterization of the osmahexaborane 2-carbonyl-2,2-bis­(tri­phenyl­phosphine)-nido-2-osmahexaborane(9), [Os(B₅H₉)(C₁₈H₁₅P)₂(CO)], (I), a metallaborane analogue of B₆H₁₀, confirms the structure proposed from NMR spectroscopy. The structure of the osmadecaborane 6-carbonyl-6,6-bis­(tri­phenyl­phosphine)-nido-6-osmadecaborane(13), [Os(B₉H₁₃)(C₁₈H₁₅P)₂(CO)], (IV), is similarly confirmed. The short basal B—B distance of 1.652 (8) Å in (I), not bridged by an H atom, mirrors that in the parent hexaborane(10) [1.626 (4) Å].