New rhodium---ruthenium heterobimetallic complexes with bridging bi- or tri-dentate phosphine ligands

The mononuclear chelated complex [RuCl(Cp)(η²-dppa)] has been synthesised and reacted with [Rh₂Cl₂(CO)₄] to form the heterobimetallic complex [(Cp)Ru(μ-CO)₂{(μ-Ph₂PN(H)PPh₂}RhCl₂]. Complexes of [RuCl(Cp){(PPh₂)₂CHCH₂PPh₂}] have been reacted with [Rh₂Cl₂(CO)₄] or [RhCl(CO)₂(p-toluidene)]. Characterisation of these new ruthenium complexes was carried out using ³¹P-NMR, FAB mass spectroscopy, elemental analysis and IR spectrophotometry.     

Conversion of rhenium alkylidyne complexes that contain unsupported metal-metal double bonds into relatives that contain μ-alkylidyne ligands

Photolysis of compounds of the type [Re(CCMe₂R)(OR′)₂] (R = Me or Ph; OR′ = O′Bu, OCMe₂(CF₃), or OCMe(CF₃)₂) in benzene with a medium pressure mercury lamp yields compounds of the type [Re(OR′)₂]₂(μ-CCMe₂R)₂ in an intramolecular and irreversible manner. [Re(CCMe₂R)(OR′)₂]₂ and [Re(OR′)₂]₂(μ-CCMe₂R)₂ (OR′ = O′Bu or OCMe₂(CF₃)₂) both react with excess carbon monoxide in several solvents to afford the dimers [Re(OR′)₂(CO)]₂(μ-CCMe₂R)₂ quantitatively. An X-ray study of [Re(O^tBu)₂(CO)]₂ (μ-C^tBu)₂ shows it to consist of two distorted trigonal bipyramids connected by two symmetrically bridging neopentylidyne ligands. The unbridged dimers of general formula [Re(CCMe₂R)(OR′)₂]₂ do not react readily with simple substrates such as phosphines, olefins, or acetylenes, although [Re(CCMe₂R)(O^tBu)₂]₂ can be oxidized by iodine to yield Re(CCMe₂R)(O^tBu)₂I₂ in good yield. In contrast, {Re[OCMe(CF₃)₂]₂}₂(μ-C^tBu)₂ reacts with one equivalent of phenylacetylene to give a species in which one of the two bridging alkylidyne ligands is retained.     

Reductive dehalogenation of chloro(alkynyl)phosphines by octacarbonyldicobalt

Reductive dehalogenation of the (chloro)(phenylethynyl)phosphine (2,4,6-^tBu₃C₆H₂O)(PhCC)PCl, I, by Co₂(CO)₈, II, yields the neutral phosphenium ion complex [(R)(R′)]P=Co(CO)₃, III, (R = 2,4,6-^tBu₃C₆H₂O; R′ = (η²-C≡CPh)Co₂(CO)₆), which contains a trigonally planar coordinated phosphorus atom. When NaCo(CO)₄, V, is used instead of II a dinuclear complex, Co₂(CO)₆[μ²-P(R)(R′)]₂, VI, (R = 2,4,6-^tBu₃C₆H₂O; R′ = C≡CPh) is formed in which the phosphido ligands P(R)(R′), bridge in a μ₂ fashion two Co(CO)₃ units. The mechanism of formation of VI, involving a formal dimerization of two [(2,4,6-^tBu₃C₆H₂O)(PhC≡C)]P=Co(CO)₃ fragments, is discussed. However, (^tBu)(PhC≡C)PCl, VII, reacts with II, to yield the cluster compound VIII, containing the two μ₂-bridging units (^tBu)[(η²-C≡CPh)Co₂(CO)₅]P and (^tBu)(PhC≡C)P.

Compounds II and VI–VIII were identified from their analytical and spectroscopic (IR, ¹H-, ¹³C- and ³¹P-NMR) data. The molecular structure of the cluster compound VIII was determined by an X-ray diffraction study.     

Synthesis, characterization of new Rh---Co mixed-metal clusters and reactions of clusters containing [Rh2Co2C2] core with 1-alkynes and/or carbon monoxide

Six new cluster derivatives [Rh₂Co₂(CO)₆(μ-CO)₄(μ₄,η²-HCCR)] (R=FeCp₂ 1, CH₂OH 2, (CH₃O)C₁₀H₆CH(CH₃)COOCH₂CCH 3) and [RhCo₃(CO)₆(μ-CO)₄(μ₄,η²-HCCR)] (R=FeCp₂ 4, CH₂OH 5, (CH₃O)C₁₀H₆CH(CH₃)COOCH₂CCH 6) were obtained by the reactions of [Rh₂Co₂(CO)₁₂] and [RhCo₃(CO)₁₂] with substituted 1-alkyne ligands HCCR [R=FeCp₂ 7, CH₂OH 8, (CH₃O)C₁₀H₆CH(CH₃) COOCH₂CCH 9] in n-hexane at room temperature, respectively. Alkynes insert into the Co---Co bond of the tetranuclear clusters to give butterfly clusters. [Rh₂Co₂(CO)₆(μ-CO)₄(μ₄,η²-HCCFeCp₂)] (1) was characterized by a single-crystal X-ray diffraction analysis. Reactions of 1, 2 with 7, 8 and ambient pressure of carbon monoxide at 25 °C gave two known cluster complexes [Co₂(CO)₆(μ₂, η²-HCCR)] (R=FeCp₂ 10, CH₂OH 11), respectively. All clusters were characterized by element analysis, IR and ¹H-NMR spectroscopy.     

Formation and structure of [Co{Ph2PN(Bu)PPh2-P,P′}2(CO)][Co)(CO)4] - a cage molecule-pair or an ion-pair complex?

The strong π-acid ligand Ph₂PN(ⁱBu)PPh₂ reacts with Co₂(CO)_S (1:1) to give Co₂[μ-Ph₂PN(ⁱBu)PPh₂] (μ-CO)₂(CO)₄ (1); however, when the ratio is 2:1 a novel species [Co{Ph₂PN(ⁱBu)PPh₂-P,P′}₂(CO)][Co(CO)₄] (2) has been obtained. Crystal data for 2: M_r = 1140.83; triclinic, space group P , a = 12.330(2), b = 13.340(2), c = 18.122(3) Å, = 86.63(1), β = 80.75(1), γ = 84.24(1)°, V = 2924 ų, Z = 2; R = 0.060 for 3711 reflections having I 3σ(I). The results of X-ray diffraction, ESR, variable-temperature magnetic susceptibility, conductivity, and XPS analysis support that the species 2 is a d⁹-d⁹ cage molecule-pair. The mechanism for the formation of the species 2 has been investigated initially by ³¹P NMR.     

Preparation, structures, and haptotropic rearrangement of novel dinuclear ruthenium complexes, (μ2,η:η-guaiazulene)Ru2(CO)4(CNR)

Novel isonitrile derivatives of a diruthenium carbonyl complex, (μ₂,η³:η⁵-guaiazulene)Ru₂(CO)₅ (2), were synthesized by substitution of a CO ligand by an isonitrile, and were subjected to studies on thermal and photochemical haptotropic interconversion. Treatment of 2 (a 45:55 mixture of two haptotropic isomers, 2-A and 2-B) with RNC at room temperature resulted in coordination of RNC and alternation of the coordination mode of the guaiazulene ligand to form (μ₂,η¹:η⁵-guaiazulene)Ru₂(CO)₅(CNR), 5d–5f, [5d; R=^tBu, 5e; 2,4,6-Me₃C₆H₂, or 5f; 2,6-ⁱPr₂C₆H₃] in moderate to good yields. Thermal dissociation of a CO ligand from 5 at 60 °C resulted in quantitative formation of a desirable isonitrile analogue of 2, (μ₂,η³:η⁵-guaiazulene)Ru₂(CO)₄(CNR), 4d–4f, [4d; R=^tBu, 4e; 2,4,6-Me₃C₆H₂, or 4f; 2,6-ⁱPr₂C₆H₃], as a 1:1 mixture of the two haptotropic isomers. A direct synthetic route from 2 to 4d–4f was alternatively discovered; treatment of 2 with one equivalent of RNC at 60 °C gave 4d–4f in moderate yields. All of the new compounds were characterized by spectroscopy, and structures of 5d (R=^tBu) and 4d-A (R=^tBu) were determined by crystallography. Thermal and photochemical interconversion between the two haptotropic isomers of 4d–4f revealed that the isomer ratios in the thermal equilibrium and in the photostatic state were in the range of 48:52–54:46.     

Homo- and hetero-bridged mixed-valence dinuclear complexes which contain the fragment ‘Rh(C6F5)3’

The reaction of the anionic mononuclear rhodium complex [Rh(C₆F₅)₃Cl(Hpz)]^t- (Hpz = pyrazole, C₃H₄N₂) with methoxo or acetylacetonate complexes of Rh or Ir led to the heterodinuclear anionic compounds [(C₆F₅)₃Rh(μ-Cl)(μ-pz)M(L₂)] [M = Rh, L₂ = cyclo-octa-1,5-diene, COD (1), tetrafluorobenzobarrelene, TFB (2) or (CO)₂ (4); M = Ir, L₂ = COD (3)]. The complex [Rh(C₆F₅)₃(Hbim)]⁻ (5) has been prepared by treating [Rh(C₆F₅)₃(acac)]⁻ with H₂bim (acac = acetylacetonate; H₂bim = 2,2′-biimidazole). Complex 5 also reacts with Rh or Ir methoxo, or with Pd acetylacetonate, complexes affording the heterodinuclear complexes [(C₆F₅)₃Rh(μ-bim)M(L₂)]⁻ [M = Rh, L₂ = COD (6) or TFB (7); M = Ir, L₂ = COD (8); M = Pd, L₂ = η³-C₃H₅ (9)]. With [Rh(acac)(CO)₂], complex 5 yields the tetranuclear complex [{(C₆F₅)₃Rh(μ-bim)Rh(CO)₂}₂]₂₋. Homodinuclear Rh^III derivatives [{Rh(C₆F₅)₃}₂(μ-L)₂]^·- [L₂ = OH, pz (11); OH, S^tBu (12); OH, SPh (13); bim (14)] have been obtained by substitution of one or both hydroxo groups of the dianion [{Rh(C₆F₅)₃(μ-OH)}₂]²⁻ by the corresponding ligands. The reaction of [Rh(C₆F₅)₃(Et₂O)_x] with [PdX₂(COD)] produces neutral heterodinuclear compounds [(C₆F₅)₃Rh(μ-X)₂Pd(COD)] [X = Cl (15); Br (16)]. The anionic complexes 1–14 have been isolated as the benzyltriphenylphosphonium (PBzPh₃⁺) salts.     

Double bond shifts induced by reaction of hex-5-en-2-one with triosmium clusters

Carbon---hydrogen bond cleavage at the terminal 6-position occurs when hex-5-en-2-one (CH₂=CHCH₂CH₂COMe) oxidatively adds to [Os₃(CO)₁₀(MeCN)₂] to give [Os₃H(μ-CH=CHCH₂CH₂COMe)(CO)₁₀], which is completely analogous to the simple vinyl complex [Os₃H(μ-CH=CH₂)(CO)₁₀]. A minor product from the reaction is [Os₃(CH₃CH=CHCH₂COMe)(CO)₁₀], an isomer in which double-bond migration has occurred to give the βγ-unsaturated ketone; stabilisation occurs through chelation and ketone coordination. [Os₃H₂(CO)₁₀] reacts with CH₂=CHCH₂CH₂COMe in refluxing cyclohexane to give a third isomer, [Os₃H(CH₃CH₂C=CHCOMe)(CO)₁₀], in which further double bond migration has occurred to give the β-unsaturated ketone. Metallation at the β-site gives an Os---C bond as part of a 5-membered chelate ring. Thermolysis of each of the three isomeric decarbonyl species in refluxing cyclohexane or heptane leads to the elimination of an Os(CO)₄ group to give the dinuclear compound [Os₂H(EtC=CHCOMe)(CO)₆] in varying yield. Pathways from γδ to the βγ and finally the β unsaturated ketones may be mapped out.     

Disproportionation of homoleptic rhodium carbonyls

Both [Rh₄(CO)₁₂] and [Rh₆(CO)₁₆] disproportionate in pyridine to cis-[Rh(CO)₂(py)₂]⁺ and [Rh₅(CO)₁₃(py)₂]⁻. In the same solvent, cis-[Rh(CO)₂(py)₂]⁺ is reduced by CO/H₂O to [(py)₂H][Rh₅(CO)₁₃-(py)₂], which has been structurally characterized.     

P and C NMR investigation of the system tetracarbonyldi-μ-chlorodirhodium(I) — tertiary phosphine

¹³C and ³¹P{¹H} NMR data at low temperature prompted us to characterize cis-[Rh(CO)₂(PR₃)Cl] (3) (3a, PR₃ = PPh₃; 3b, PR₃ = PMe₂Ph), as surprisingly stable products of the reaction between [{Rh(CO)₂(μ-Cl)}₂] (1) and tertiary phosphines in toluene (P : Rh = 1). Every attempt to isolate solid 3a led to the cis- and trans- halide-bridged dimers [{Rh(CO)₂(μ-Cl)}₂] (5a) and 6a which are formed from 3a by slow decarbonylation, a process which is greatly accelerated by the evaporation of the solvent under vacuum.

The analogous reaction of 1 with dimethylphenylphosphine follows a similar pathway; in this case, however, low temperature NMR spectra allowed us to characterize the pentacoordinated dinuclear species [{Rh(CO)₂(μ-Cl)}₂] (2b) as the unstable intermediate of the bridge-splitting process.

The reaction of 3 with a second equivalent of phosphine (P : Rh = 2) leads, at room temperature, to the well known product trans-[Rh(CO)(PR₃)₂Cl] (8) accompanied by evolution of CO; however our data show that when the reaction is performed at 200 K, decarbonylation is prevented and spectroscopic evidence of trigonal bipyramidal pentacoordinate [Rh(CO)₂(PR₃)₂Cl] (7), stable only at low temperature, can be obtained.     

Recent studies on metal and metalloid bis(trimethylsilyl)methyls and the transformation of the bis(trimethylsilyl)methyl into the azaallyl and β-diketinimato ligands

Recent results (post-1990) on the synthesis and structures of bis(trimethylsilyl)methyls M(CHR₂)_m (R = SiMe₃) of metals and metalloids M are described, including those of the crystalline lipophilic [Na(μ-CHR₂)]_∞, [Rb(μ-CHR₂)(PMDETA)]₂, K₄(CHR₂)₄(PMDETA)₂, [Mg(CHR₂)(μ-CHR₂)]_∞, P(CHR₂)₂ (gaseous) and P₂(CHR₂)₄, [Yb(CHR₂)₂(OEt₂)₂] and [{Yb(CR₃)(μ-OEt)(OEt₂)}₂]; earlier information on other M(CHR₂)_m complexes and some of their adducts is tabulated. Treatment of M(CHR₂) (M = Li or K) with four different nitriles gave the X-ray-characterized azaallyls or β-diketinimates , and (LL′ = N(R)C(^tBu)CHR, L′L′ = N(R)C(Ph)C(H)C(Ph)NR, LL″ = N(R)C(Ph)NC(H)C(Ph)CHR, R = SiMe₃ and Ar = C₆H₃Me₂-2,5). The two lithium reagents were convenient sources of other metal azaallyls or β-diketinimates, including those of K, Co(II), Zr(IV), Sn(IV), Yb(II), Hf(IV) and U(VI)/U(III). Complexes having one or more of the bulky ligands [LL′]⁻, [L′L′]⁻, [LL]⁻, [LL″]⁻, [L″L]⁻, [LL]⁻ and [{N(R)C(^tBu)CH}₂C₆H₄-2]²⁻ are described and characterized (LL = N(H)C(Ph)C(H)C(Ph)NH, L″L = N(R)C(^tBu)C(H)C(Ph)NR, LL = N(R)C(^tBu)CHPh). Among the features of interest are (i) the contrasting tetrahedral or square-planar geometry for and , respectively, and (ii) olefin-polymerization catalytic activity of some of the zirconium(IV) chlorides.     

Synthesis, structure and hydrogenation catalytic activity of [Ru3(μ3,η-ampy)(μ,η:η-PhC=CHPh)(CO)6(PPh3) (Hampy = 2-amino-6-methylpyridine)

The compound [RU₃(μ₃,η²- -ampy)(μ₃η¹:η²-PhC=CHPh)(CO)₆(PPh₃)₂] (1) (ampy = 2-amino-6-methylpyridinate) has been prepared by reaction of [RU₃(η-H)(μ₃,η²- ampy) (μ,η¹:η²-PhC=CHPh)(CO)₇(PPh₃)] with triphenylphosphine at room temperature. However, the reaction of [RU₃(μ-H)(μ₃, η² -ampy)(CO)₇(PPh₃)₂] with diphenylacetylene requires a higher temperature (110°C) and does not give complex 1 but the phenyl derivative [RU₃(μ₃,η²-ampy)(μ,η ¹:η² -PhC=CHPh)(μ,-PPh₂)(Ph)(CO)₅(PPh₃)] (2). The thermolysis of complex 1 (110°C) also gives complex 2 quantitatively. Both 1 and 2 have been characterized by0 X-ray diffraction methods. Complex 1 is a catalyst precursor for the homogeneous hydrogenation of diphenylacetylene to a mixture of cis- and trans -stilbene under mild conditions (80°C, 1 atm. of H₂), although progressive deactivation of the catalytic species is observed. The dihydride [RU₃(μ-H)₂(μ ₃,η²-ampy)(μ,η¹:η²- PhC=CHPh)(CO)₅(PPh₃)₂] (3), which has been characterized spectroscopically, is an intermediate in the catalytic hydrogenation reaction.     

New seven-coordinate thiourea and N,N,N′,N′-tetramethylthiourea complexes of molybdenum(II) and tungsten(II)

The compounds [MI₂(CO)₃(NCMe)₂] (M = Mo or W) react with one equivalent of thiourea (tu) in MeOH or N,N,N′,N′-tetramethylthiourea (tmtu) in CH₂Cl₂ at room temperature to initially afford the monoacetonitrile compounds [MI₂(CO)₃(NCMe)L] (L = tu or tmtu) which rapidly transform to the isolated iodide bridged dimers, [M(μ-I)I(CO)₃L]₂ with loss of acetonitrile. Reaction of [WI₂(CO)₃(NCMe)₂] with two equivalents of tu or tmtu gave the expected mononuclear seven-coordinate compounds [WI₂(CO)₃L₂]. However, reaction of [MoI₂(CO)₃(NCMe)₂] with two equivalents of tu or tmtu rapidly affords the iodide-bridged dimers [Mo(μ-I)I(CO)₂L₂]₂ with loss of carbon monoxide from [MoI₂(CO)₃L₂]. The low temperature (−70°C) ¹³C NMR spectrum of [Mo(μ-I)I(CO)₂ {SC(NMe₂)₂}₂]₂ suggests the complex is based on two capped octahedra with a carbonyl ligand capping each octahedral face.     

Reactions of tetrakis(trifluoromethyl) diphosphine and bis(trifluoromethyl) phosphine with ruthenium carbonyl clusters; X-ray structure of tetraruthenium carbonyl cluster derivatives

Reaction of [Ru₃(CO)₁₂ with (CF₃)₂P---P(CF₃)₂ in p-xylene at 140°C yielded the compounds [Ru₄(CO)₁₃{μ-P(CF₃)₂}₂] (1), [Ru₄(CO)₁₄{μ-P(CF₃)₂}₂] (2) and [Ru₄(CO)₁₁{μ-P(CF₃)₂}₄] (3). Reaction with [(μ-H)₄Ru₄(CO)₁₂] under similar conditions yielded [(μ-H)₃Ru₄(CO)₁₂{μ-P(CF₃)₂}] (4). All four compounds have been characterised by X-ray crystallography. The fluxional behaviour of the hydrides in 4 has also been studied by variable-temperature NMR spectroscopy. Compounds 1, 2 and 4 were also obtained from the reactions of Ru₃(CO)₁₂ with (CF₃)₂PH in dichloromethane at 80°C.     

Solid-state static Cu and P CP/MAS NMR, and liquid-state EXAFS studies on copper(I) O,O′-dialkyldithiophosphate cluster compounds: Formation of the copper(I) O,O′-di-iso-amyldithiophosphate cluster compound on the surface of synthetic chalcocite

Polycrystalline octa-nuclear copper(I) O,O′-di-i-propyl- and O,O′-di-i-amyldithiophosphate cluster compounds, {Cu₈[S₂P(OR)₂]₆(μ₈-S)} where R = ⁱPr and ⁱAm, were synthesized and characterized by ³¹P CP/MAS NMR at 8.46 T and static ⁶⁵Cu NMR at multiple magnetic field strengths (7.05, 9.4 and 14.1 T). The symmetries of the electronic environments around the P sites were estimated from the ³¹P chemical shift anisotropy (CSA) parameters, δ_aniso and η. Analyses of the ⁶⁵Cu chemical shift and quadrupolar splitting parameters for these compounds are presented with the data being compared to those for the analogous octa-nuclear cluster compounds with R = ⁿBu and ⁱBu. The ⁶⁵Cu transverse relaxation for the copper sites in {Cu₈[S₂P(OⁱPr)₂]₆(μ₈-S)} and {Cu₈[S₂P(OⁱAm)₂]₆(μ₈-S)} was found to be very different, with a relaxation time, T₂, of 590 μs (Gaussian) and 90 μs (exponential), respectively. The structures of {Cu₄[S₂P(OⁱPr)₂]₄} and {Cu₈[S₂P(OⁱPr)₂]₆(μ₈-S)} cluster compounds in the liquid- and the solid-state were studied by Cu K-edge EXAFS. The disulfide, [S₂P(OⁱAm)₂]₂, was obtained and characterized by ³¹P{¹H} NMR. The interactions of the disulfide and of the potassium O,O′-di-i-amyldithiophosphate salt with the surfaces of synthetic chalcocite (Cu₂S) were probed using solid-state ³¹P NMR spectroscopy and only the presence of copper(I) dithiophosphate species with the {Cu₈[S₂P(OⁱAm)₂]₆(μ₈-S)} structure was observed.     

Synthesis of novel platinum-silver and platinum-copper complexes with bridging alkynyl ligands

The study of the reactivity of [Pt₂M₄(CCR)₈] (M=Ag or cu; R=Ph or ^tBu) towards different neutral and anionic ligands is reported. This study reveals that reactions of the phenylacetylide derivatives [Pt₂M₄(CCPh)₈] with anionic, X⁻ (X=Cl or Br) or neutral donors (CN^tBu or py) in a molar ratio 1:4 (m/donor ratio 1:1) yield the trinuclear anionic (NBu₄)₂[{Pt(CCPh)₄ (MX)₂] (M=Ag or Cu, X =Cl or Br) or neutral [{Pt(CCPh0₄=sAGL)₂] (L=CN^tBu or py) complexes, respectively. The crystal structure of (NBu₄)₂[{Pt(CCPh)₄}(CuBr)₂](4) shows that the anion is formed by a dianionic Pt(CCPh)₄ fragment and two neutral CuBr units joined through bridging alkynyl ligands. All the alkynyl groups are σ bonded to Pt and η²-coordinated to a Cu atom which have an approximately trigonal-planar geometry. By contrast, similar reactions with [Pt₂M₄(CC^tBu)₈] (molar ratio M/donor 1:1) afford hexanuclear dianionic (NBu₄)₂[Pt₂M₄(CC^tBu)₈X₂] or neutral [Pt₂Ag₄(CC^tBu0₈Py₂]. Only by treatment with a large exces of Br ⁻ (molar ratio M/Br⁻ 1:2) are the trinuclear complexes (NBu₄)₂[{Pt(CC^tBu₄ (MBr)₂] (M=Ag, Cu) obtained. Attempted preparations of analogous complexes with phosphines (L′=PPh₃ or PEt₃) by reactions of [Pt₂M₄(CCR₈] with L′ leads to displacement of alkynyl ligands from platinum and formation of neutral mononuclear complexes [trans-Pt(CCR)₂L′₂].     

Synthesis of Re-Ru heterobimetallic polyhydride complexes. Study of the influence of ligands bonded to the monometallic precursors on the nature of the isolated binuclear complexes

The reaction of K[H₆ReL₂] with [RuHCl(CO)(PPh₃)_3−x {P(OPrⁱ}₃)_x](L₂ = (PMePh₂)₂, dppe, (AsPh₃)₂, or (PPh₃)₂; x = 0, 1 or 2) leads to [L₂(CO)HRe(μ-H)₃RuH(PPh₃)_2−y{P(OPrⁱ)₃}_y] (x = 0 or 1, Y = 0; X = 2, Y = 1(L₂ = PPh₃)) in a first step. Under the reaction conditions most of these complexes react rapidly with the liberated phosphine giving [L₂(CO)Re(μ-H)₃Ru(PPh₃)_3−y- {P(OPrⁱ)₃}_y] (L₂ = (PMePh₂)₂ or dppe, Y = 0; L₂ = (PPh₃)₂, Y = 1) as the only iso complexes. The structure of [(PMePh₂)₂(CO)Re(μ-H)₃Ru(PPh₃)₃] has been establishedby X-ray structure analysis. The complex [(PPh₃)₂(CO)Re(μ-H)₃Ru(PPh₃)₂(P(OPrⁱ)₃)] reacts with molecular hydrogen under pressure to generate [L₂(CO)HRe(μ-H)₃RuH(PPh₃)(P(OPrⁱ)₃) as the sole product.     

Reactions of metalloalkynes VII. Protonation of ruthenium ethyne-1,2-diyl complexes

The acid–base chemistry of some ruthenium ethyne-1,2-diyl complexes, [{Ru(CO)₂(η-C₅H₄R)}₂(μ₂-CC)] (R=H, Me) has been investigated. Initial protonation of [{Ru(CO)₂{η-C₅H₄R}}₂(μ₂-CC)] gave the unexpected complex cation, crystallised as the BF₄ salt, [{Ru(CO)₂(η-C₅H₄R}}₃(μ₃-CC)][BF₄] (R=Me structurally characterised). This synthesis proved to be unreliable but subsequent, careful protonation experiments gave excellent yields of the protonated ethyne-1,2-diyl complexes, [{Ru(CO)₂{η-C₅H₄R)}₂(μ₂-η¹:η²-CCH)](BF₄) (R=Me structurally characterised) which could be deprotonated in high yield to return the starting ethyne-1,2-diyl complexes.     

A new approach to the synthesis of carbon chains capped by metal clusters

Reactions of Co₃(μ₃-CBr)(μ-dppm)(CO)₇ with {Au[P(tol)₃]}₂{μ-(CC)_n} (n=2–4) have given {Co₃(μ-dppm)(CO)₇}{μ₃:μ₃-C(CC)_nC} [n=2 (1), 3 (2), 4 (3)] containing carbon chains capped by the cobalt clusters. Tetracyanoethene reacts with 2 to give {Co₃(μ-dppm)(CO)₇}₂{μ₃:μ₃-C(CC)₂C[=C(CN)₂]C[=C(CN)₂]C} (4). X-ray structural characterisation of 1, 3 and 4 are reported, that for 3 being the first of a cluster-capped C₁₀ chain.     

Oxidative addition of 2,2′-dipyridyl disulfphide to the cluster [Os3(CO)10(MeCN)2]

The cluster [Os₃(CO)₁₀(MeCN)₂] reacts with 2,2′-dipyridyl disulphide (1, pySSpy) to give a range of oxidative addition products which were separated by TLC on silica and crystallization : [Os₃(pyS)₂(CO)₁₀] (2), [Os₃(pyS)₂(CO)₉] (3), [Os₂(pyS)₂(CO)₆] (4) and [Os(pyS)₂(CO)₂] (5), together with some of the hydride [Os₃H(pyS)(CO)₉] (6), which is not an expected oxidative addition product. The X-ray crystal structures of compounds 2, 3, 4 and 6 (compounds 2 and 6 occurring within a single crystal), together with the known structure of compound 5, reveal several modes of pyS bonding : chelating pyS, μ₂-pyS (both sulphur-bonded and nitrogen, sulphur-bonded) and μ₃-pyS.