Reactions of ortho-Phenylenediamine with a Nickel Trimethylacetate Complex

Interaction of ortho-phenylenediamine with the nonanuclear nickel trimethylacetate cluster Ni₉(₄-OH)₃(₃-OH)₃( _n -OOCMe₃)₁₂(HOOCCMe₃)₄(I) in an amine deficiency yields the antiferromagnetic trinuclear complex [Ni₃{-N,N"-(NH₂)₂C₆H₄}₂(HCCOOCMe₃)₃(₃-OH)(-OOCCMe₃)₄]⁺(OOCCMe₃)^–(III) containing bridging diamine ligands. Reaction of excess diamine with Ior IIIleads to the formation of the paramagnetic monomer Ni{²-o-(NH₂)₂C₆H₄}₂(OOCCMe₃)₂(IV), which reacts with atmospheric oxygen to form the known bis(semiquinonediimine) complex Ni[1,2-(NH)₂C₆H₄]₂(V).     

Chemistry on the rhomboidal Ru4 faces of the clusters RU4(CO)13(μ-PR2)2: Novel small molecule,ligand, and skeletal transformations

Tetrametal clusters such as Ru₄(CO)₁₃(-PPh₂)₂ and Ru₄(CO)₁₀(-PPh₂)₄ are 64-electron systems and, with five metal-metal interactions, are formally electron rich. In fact these clusters have unusual rhomboidal (or flat butterfly) structures with three or four elongated Ru-Ru bonds. With molecular orbitals antibonding with respect to metal metal interactions occupied in such clusters, facile two electron oxidation or ligand dissociation processes should occur, giving electron precise molecules. The molecule Ru₄(CO)₁₃(-PPh₂)₂ 1a undergoes a remarkable, reversible transformation upon loss of CO affording (-H)Ru₄(CO)₁₀(-PPh₂)[₄-¹(P),¹(P),¹(P),¹,²-{C₆H₄}PPh]3 a cluster which contains a five coordinate phosphido bridge and an orthometallated ² arene ring. This conversion is reversible under CO. These and other results which will be discussed confirm that M₄ clusters with electrons in excess of the expected EAN rule count may exhibit unusual reactivity. The solid-state CP/MAS and static powder³¹P NMR spectra of some of these clusters exhibit^99/101Ru-³¹P couplings, values of which have been measured for the first time.     

Reaction of the Hexa-1,3,5-triyne Me3SiC≡CC≡CC≡CSiMe3 with Ru4(CO)13(μ 3-PPh): Parallels with the Chemistry of Alkynes and Diynes

Reaction of Ru₄(CO)₁₃(₃-PPh) (1) with the 1,3,5-hexatriyne Me₃SiCCCCC CSiMe₃ under mild thermal conditions affords initially Ru₄(CO)₁₀(-CO)₂{₄-¹,¹,²-P(Ph)C(CCSiMe₃)C(CCSiMe₃) (2), via the facile formation of a P–C bond in a manner similar to that demonstrated previously with alkynes and diynes. The 62-CVE cluster 2 readily decarbonylates to give crystallographically characterised Ru₄(CO)₁₀(-CO)(₄-PPh){₄-¹,¹,²,²-Me₃SiCCC₂CCSiMe₃} (3). Attempts to further incorporate the pendant alkyne moieties in 3 into the Ru₄ coordination environment were partially successful with Ru₄(CO)₁₀(₄-PPh)(₄-¹,¹,³,³-RC₄R') (4, R/R'=SiMe₃/CCSiMe₃) being formed as a minor product together with the unusual toluene coordinated species Ru₄(CO)₇(⁶-C₆H₅Me)(₄-PPh)(₄-¹,¹,³,³-Me₃SiC₄CCSiMe₄) (5). Cluster 3 reacts with an excess of Me₃SiCCCCCCSiMe₃ to give the open chain cluster Ru₄(CO)₉(₃-PPh){₄-²,²,⁴,⁴,-C₄(CCSiMe₃)(SiMe₃)C₄(CCSiMe₃)₃} (6).     

Role of metal center in reactions of polynuclear nickel(ii) and cobalt(ii) trimethylacetates with 8-amino-2,4-dimethylquinoline

The reactions of 8-amino-2,4-dimethylquinoline (L) (1) with polynuclear nickel(ii) and cobalt(ii) hydroxotrimethylacetato complexes under anaerobic conditions were studied. The nonanuclear cluster Ni₉(₄-OH)₃(₃-OH)₃(_n-OOCCMe₃)₁₂(HOOCCMe₃)₄ gave the mononuclear complex Ni(²-L)(²-OOCCMe₃)₂ (2). The tetranuclear complex Ni₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆ produced the mononuclear complex Ni(²-L)(²-OOCCMe₃)(OOCCMe₃)L (3). At room temperature, the cobalt-containing polynuclear trimethylacetates, viz., the polymer [Co(OH) _n (OOCCMe₃)_2–n ] _x and the tetranuclear complex Co₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆, were transformed into the trinuclear cobalt(ii) complex Co₃(₃-OH)(-OOCCMe₃)₄(²-L)₂(OOCCMe₃) (4). Meanwhile, at 80 °C these compounds generated the binuclear cobalt(iii) complex Co₂(₂²-(HN)C₉NMe₂)₂(-OOCCMe₃)(L)(OOCCMe₃)₃ (5). The structures of the resulting compounds were established by X-ray diffraction analysis. Compounds 2—4 exhibit the antiferromagnetic spin-spin exchange coupling, whereas compound 5 is diamagnetic.     

Diacetylenic Derivatives of Fe2(CO)6(μ-EE′): Spectroscopic Investigations of Fe2(CO)6{μ-EC(H) = C(C≡ CMe)E′} (E = E′, E ≠ E′; E, E′ = S, Se, Te)

The diacetylenic adducts, Fe₂(CO)₆{-EC(H) = C(C CMe)E} (E = E, E E; E, E = S, Se, Te) (1–8) have been obtained from the room temperature stirring of Fe₂(CO)₆(-EE) with HC CC CMe in methanol solvent containing sodium acetate. Compounds 1–8 have been characterized by IR and multinuclear NMR (¹H, ¹³C, ⁷⁷Se, and ^l25Te) spectroscopy. Trends in the chemical shifts of ⁷⁷Se and ¹²⁵Te NMR spectra of Fe₂(CO)₆{-EC(H) = C(C CMe)E} with a variation of EE are discussed.     

Unsymmetrical dinuclear cobalt and nickel trimethylacetate complexes

The reaction of the dinuclear complex Co₂(-OOCCMe₃)₂(²-OOCCMe₃)₂bpy₂ (1) with the polymer [Co(OH) _n (OOCCMe₃)_2–n ] _x afforded the unsymmetrical dinuclear complex bpyCo₂(₂-O,²-OOCCMe₃)(₂-O,O"-OOCCMe₃)₂(²-OOCCMe₃) (2). The reaction of 2,2"-dipyridylamine with [Co(OH) _n (OOCCMe₃)_2–n ] _x gave rise to the analogous complex [(C₅H₄N)₂NH]Co₂(₂-O,²-OOCCMe₃)(-OOCCMe₃)₂(²-OOCCMe₃) (3). The reaction of complex 1 with Ni₄(₃-OH)₂(-OOCCMe₃)₄(OOCCMe₃)₂(MeCN)₂[²-o-C₆H₄(NH₂)(NHPh)]₂ (4) produced an isostructural heterometallic analog of complex 2 with composition bpyM₂(₂-O,²-OOCCMe₃)(₂-O,O"-OOCCMe₃)₂(²-OOCCMe₃) (5) (M = Co, Ni; Co : Ni = 1 : 1) and the dinuclear heterometallic complex bpy(HOOCCMe₃)M(-OH₂)(-OOCCMe₃)₂M(OOCCMe₃)₂[o-C₆H₄(NH₂)(NHPh)] (6) (M = Co, Ni; Co : Ni = 0.15 : 1.85). Compounds 2 and 5 exhibit ferromagnetic spin-spin exchange interactions.     

New cobalt trimethylacetate complexes with pyridine

The reaction of the tetranuclear trimethylacetate complex Co₄(₃-OH)₂(-OOCCMe₃)₄(²-OOCCMe₃)₂(EtOH)₆ with pyridine in acetonitrile was studied. Two new compounds, viz., the hexanuclear cobalt(ii) complex Co₆py₄(₃-OH)₂(-OOCCMe₃)₁₀ (25% yield) and the unusual ionic compound [Co₃py₃(₃-O)(-OOCCMe₃)₆]⁺[Co₄py(₄-O)(-OOCCMe₃)₇]^– (5% yield), were prepared. The structures of the new compounds were established by X-ray diffraction analysis.     

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.     

Reactions of the Ru3(CO)10(μ-Ph2PCH2PPh2) cluster with enynes RCH=CHC≡CR (R is phenyl or ferrocenyl). Formation of indenone derivatives of triruthenium clusters

The thermal reaction of Ru₃(CO)₁₀(-Ph₂PCH₂PPh₂) (1) with enyne PhCH=CHCCPh afforded the trinuclear ruthenium clusters Ru₃(CO)₆{₃-P(Ph)CH₂PPh₂}{₃-C(Ph)=CHCC(Ph)(1,2-C₆H₄)C(=0)} (2), Ru₃(-H)(CO)₅{₃-P(Ph)CH₂PPh₂}{₃-C(Ph)=CHCC(Ph)(1,2-C₆H₄)C(—0)} (3), and Ru₃(CO)₆(-CO){₃-P(Ph)CH₂PPh₂}{₃-C(C=CPh₂)CH=C(H)Ph} (4) and also two isomers of Ru₃(CO)₅(-CO)(-Ph₂PCH₂PPh₂){₃-C₄Ph₂(CH=CHPh)₂} (5a and 5b). Clusters 2, 3, and 4 were characterized by IR spectroscopy, ¹H and ³¹P NMR spectroscopy, and X-ray diffraction analysis. The reaction of complex 1 with enyne FcCH=CHCCFc gave rise to the Ru₃(CO)₆{₃-P(Ph)CH₂PPh₂}{₃-C(Fc)=CHCC(Fc)(1,2-C₆H₄)C(=0)} (6) and Ru₃(-H)(CO)₅{₃-P(Ph)CH₂PPh₂}{₃-C(Fc)=CHCC(Fc)(1,2-C₆H₄)C(—0)} (7) clusters. According to the spectral data, the latter compounds are isostructural to complexes 2 and 3, respectively.     

Homo- and heterometallic trinuclear nickel(ii) and cobalt(ii) pivalate complexes

The reaction of the dinuclear complex Co₂(bpy)₂(OOCBu^t)₄ with the tetranuclear complex Ni₄(₃-OH)₂(OOCBu^t)₆(EtOH)₆ afforded the trinuclear heterometallic complex M₃(bpy)₂(₃-OH)(-OOCBu^t)₄(OOCBu^t) (6) (M = Ni, Co; Ni : Co = 1.2 : 1) in which two metal atoms are in an octahedral environment and one metal atom is in a tetrahedral environment. The reaction of 2,2"-bipyridine with Co₄(₃-OH)₂(OOCBu^t)₆(HOEt)₆ (reagent ratio was 2 : 1) or the reaction of bpy with Co₈(₄-O)₂( _n -OOCBu^t)₁₂ (reagent ratio was 4 : 1) produced a homometallic analog of 6, viz., the trinuclear cluster Co₃(bpy)₂(₃-OH)(-OOCBu^t)₄(OOCBu^t) (8). The reaction of 1,10-phenanthroline (phen) with the [Co(OH) _n (OOCBu^t)_2–n ] _x polymer gave the analogous trinuclear cluster (phen)₂Co₃(₃-OH)(₂-OOCBu^t)₄(¹-OOCBu^t). Compounds 6 and 8 exhibit antiferromagnetic spin-spin exchange interactions.     

Redox Properties of Rhodium(III) Oxo-Bridged Carboxylate Complexes

Chemical and electrochemical oxidation of rhodium (III) oxo-bridged carboxylate complexes was studied. The chemical [with O₃ and Ce(IV) salts] or electrochemical (at potentials of 1.00-1.20 V) oxidations of the binuclear complexes [Rh₂(-O)(-O₂CCH₃)₂(H₂O)₆]^{2 +} and [Rh₂(-O)(-O₂CCF₃)₂(H₂O)₆]^{2 +} leads to the superoxo complexes [Rh₂(-O)(O₂-)(-O₂CCH₃)₂(H₂O)₅]⁺ and [Rh₂(-O)(O₂ ^-)(-O₂CCF₃)₂(H₂O)₅]⁺ with terminal coordination of O₂-. The trinuclear acetate [Rh₃(₃-O)(-O₂CCH₃)₆(H₂O)₃]⁺, unlike its trifluoroacetate analog [Rh3(₃-O)(-O₂CCF₃)₆(H₂O)₃]⁺, is oxidized only electrochemically at a potential of 1.38 V. The oxidation of [Rh₃(₃-O)(-O₂CCH₃)₆(H₂O)₃]⁺ is reversible and involves formation of an unstable superoxo group O₂ ^- between two Rh₃III(₃-O) cores.     

Binuclear Osmium μ-Oxocarboxylate Complexes [Os2(μ-O)(μ-O2CR)2Cl4L2] (R = CH3, CCl3; L = PPh3, AsPh3) and Their Electrochemical Behavior in Dichloromethane

Cyclic voltammetry and galvanostatic coulometry techniques were used to determine how the redox properties of osmium binuclear -oxocarboxylates [Os₂ ^IV(-O)(-O₂CR)₂Cl₄L₂] (R = CH₃, CCl₃; L = PPh₃ and R = CH₃; L = AsPh₃) are influenced by the nature of the bridging carboxylate ligand RCOO^– and ligand L. It was shown that all compounds in solution of dichloromethane undergo two single-electron reduction processes. The data obtained were compared with the DFT calculations of the electronic structure of the model complexes [Os₂ ^IV(-O)(-O₂CR)₂Cl₄L₂] (R = CH₃, CCl₃; L = PH₃ and R = CH₃; L = AsH₃).     

Synthesis and X-ray structures of some mono- and binuclear ruthenium complexes with bisphosphine ligands

Summary The dinuclear complexes {RuCp*(-Cl)}₂(-dppm) (1) and {RuCp*(-Cl)}₂ (-dppe) (3) are obtained by reacting [RuCp*(³-Cl)]₄ withdppm, anddppe, respectively.1 is readily oxidized with AgCF₃SO₃, instead of chloride abstraction, to afford the dinuclear complex [{RuCp*(-Cl)}₂(-dppm)](SO₃CF₃)₂ (2) with two metal centers connected by a single Ru-Ru bond. Under the same conditions,3 decomposes to several intractable materials. Similarly to1, RuCp* (dmpe)Cl reacts with AgCF₃SO₃ to afford the Ru(III) complex [RuCp*(dmpe)Cl](SO₃CF₃) (4) without no halide abstraction. The crystal structures of2,3, and4 are presented.

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Synthese und Röntgenstrukturanalyse einiger ein- und zweikerniger Rutheniumkomplexe mit Bisphosphinliganden

Zusammenfassung Die Komplexe {RuCp*(-Cl)}₂(-dppm) (1) und {RuCp*(-Cl₂(-dppe) (3) wurden durch Umsetzung von [RuCp*(³-Cl)]₄ mitdppm bzw.dppe dargestellt.1 wird durch AgCF₃SO₃ zum zweikernigen Komplex [{RuCp*(-Cl)}₂(-dppm)](SO₃CF₃)₂ (2) oxidiert, welcher eine Ru-Ru-Metallbindung aufweist. Unter den gleiche Reaktionsbedingungen zersetzt sich3 zu undefinierten Produkten. Analog zu1 reagiert RuCp* (dmpe)Cl mit AgCF₃SO₃ zum Ru(III)-Komplex [Ru(Cp*)(dmpe)Cl](SO₃CF₃) (4) wobei es zu keiner Chloridabspaltung kommt. Von2,3, und4 wurden die Kristallstrukturen bestimmt.

     

Formation and Transformations of Polynuclear Hydroxo- and Oxotrimethylacetate Complexes of Ni(II) and Co(II)

Transformations of polymeric trimethylacetate complexes [M(OH) _n (OOCCMe₃)_{2 – n} ] _m (M = Ni (I) and Co (II)) and clusters Ni₉(₄-OH)₃(₃-OH)₃(-O,O-OOCCMe₃)(-O,O"-OOCCMe₃)₇(₃-O,O,O"-OOCCMe₃)₃(₄-O,O,O",O"-OOCCMe₃)(HOOCCMe₃)₄(III) and Co₆(₃-OH)₂(-OOCCMe₃)₁₀(HOOCCMe₃)₄(VIII), which are formed from Iand IIupon their recrystallization from nonpolar solvents, were studied. It was shown that the action of N-phenyl-o-phenylenediamine (L) on Ior IIIresults, depending on the solvent, in different tetranuclear clusters with the hydroxo bridges. For example, in benzene, the L₂Ni₄(₃-OH)₂(HOOCCMe₃)₄(-OOCCMe₃)₆complex (IX) is formed; its L molecules are coordinated in a monodentate way, whereas in acetonitrile, they chelate to give the {[o-C₆H₄(NH₂)(NHPh)]₂Ni₄(₃-OH)₂(MeCN)₂(OOCCMe₃)₂(-OOCCMe₃)₄} compound (X). Heating of Xin the presence of atmospheric oxygen yields IX, the mononuclear bissemiquinonediimine [o-C₆H₄(NH)(NPh)]₂Ni complex (XI), and water. It was noted that the use of aniline in these reactions affords, independent of the nature of the solvent, only one (NH₂C₆H₅)₂Ni₄(₃-OH)₂(HOOCCMe₃)₄(-OOCCMe₃)₆cluster (VI); in acetonitrile, this cluster is formed as the solvate VI· 2HOOCCMe₃(VIa). When treated with ethanol, Iand IIIgive the Ni₄(EtOH)₆(₃-OH)₂(₂-OOCCMe₃)₄(OOCCMe₃)₂cluster (V), which is structurally close to the known cobalt-containing analog IV. Thermolysis of IVin decalin at 170° causes its dimerization, giving the octanuclear Co₈(₄-O)₂( _n -OOCCMe₃)₁₂complex (VII) with the tetradentate oxo bridges.     

Equilibrium Particle Distribution in the Disperse System with Coagulation and Aggregate Disintegration

Kinetic equations were formulated, which describe coagulation–fragmentation process in a low concentrated suspension flow at a low shear rate. In such a system dispersed phase divided into fine and coarse fractions as the system is brought to equilibrium. Kinetic equations of two-fraction model were formulated. An approximate solution and, in one particular case, the exact solution of these equations were obtained for the equilibrium state. Detailed analysis of equilibrium particle distribution over the mass m was performed for an exponential coagulation kernel = ₀ m and an degenerated disintegration kernel = ₁₂, in which the disintegration frequency is an exponential function of aggregate mass ₁ = ₀ m ⁺ , and the probability of the fragment detachment from an aggregate is independent ofm and decreases exponentially with an increase in mass of a fragment: ₂ = ₀ ^–1exp(–/₀). The equilibrium distribution was shown to exist only at > 0, and in particular, it is described at = = 1 by the f() = ₀₀ ^–1exp(–/₀) and F(m) = Cx ^–1(x + 1)^{2 – 1} e ^–x functions for the particles of fine and coarse fractions (x = m/m ₀, = m ₀/₀, m ₀ and ₀ are the characteristic masses of coarse and fine fractions, respectively). The particle distribution for the fine fraction at 1 is well approximated by the Gaussian distribution exp[–(m – m ₀)²/(4^–1 m ₀₀)].     

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.     

Chemistry of heterometallic phenyl imido and phosphinidene clusters

Triruthenium imido cluster Ru₃(CO)₁₀(₃-NPh)⁽¹⁾ reacts with tungsten hydride LW(CO)₃H to afford heterometallic imido clusters LWRu₂(CO)₈(-H) (₃-NPh), L=Cp, (IIa); L=Cp*, (IIb), whereas the respective phosphinidene complexes LWRu₂(CO)₈(-H)(₃-PPh), L=Cp, (IXa); L=Cp*, (IXb), were generated via reaction of Ru₃(CO)₁₀(-H)(-PPh₂) with CpW(CO)₃H and with CP*W(CO)₃H followed by thermolysis in the presence of carbon monoxide. Their molecular structure, solution dynamics, and the subsequent reaction with hexafluoro-2-butyne are presented.     

Lithium and lanthanum complexes with acenaphthylene dianion. Molecular structure of [Li(Et2O)2]2μ2:η3[Li(η3:η3-C12H8)]2 complex

The lithium complex with the acenaphthylene dianion [Li(Et₂O)₂]₂₂:³[Li(³:³-C₁₂H₈)]₂ (1) was synthesized by the reduction of acenaphthylene with lithium in diethyl ether. According to the X-ray diffraction data, compound 1 has a reverse-sandwich structure with the bridging dianion ₂:³[Li(³:³-C₁₂H₈)]₂. Two lithium atoms in complex 1 are located between two coplanar acenaphthylene ligands of the ₂:³[Li(³:³-C₁₂H₈)]₂ ^2– dianion and are ³-coordinated with the five- and six-membered rings. The lanthanum complex with the acenaphthylene dianion [LaI₂(THF)₃]₂(₂-C₁₂H₈) (2) was synthesized by the reduction of acenaphthylene in THF with the lanthanum(iii) complex [LaI₂(THF)₃]₂(₂-C₁₀H₈) containing the naphthalene dianion. The ¹H NMR spectrum of complex 2 in THF-d₈ exhibits four signals of the acenaphthylene dianion, whose strong upfield shifts compared to those of free acenaphthylene indicate the dianionic character of the ligand. The highest upfield chemical shift belongs to the proton bound to the C atom on which, according to calculation, the maximum negative charge is concentrated.     

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.     

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.