Synthesis and structure of the pentanuclear mixed-metal cluster [Co4MoCp(μ3-SBut)(μ3-S)(μ3-CO)(μ-CO)2(CO)6]

The pentanuclear mixed-metal cluster [Co₄MoCp(μ₃-SBu^t)(μ₃-S)(μ₃-CO)(μ-CO)₂(CO)₆] (1) has been synthesised by reaction of [CoMoCp(CO)₇] with Bu^tSSBu^t. X-ray structural analysis identified an asymmetric unit with three cobalt atoms and one molybdenum forming an irregular tetrahedron while one cobalt–molybdenum edge is bridged by a cobalt atom. Crystal data: space group P2(1)/n, a=10.162(2), b=13.722(3), c=17.69(5) Å, β=91.44(2)°, Z=4.     

The structural characterization and hydroformylation activity of the tri-rhodium complex [Rh3(μ2-dppm)2(μ2-CO)3(K-CO)3]BF4

Rh₂(cod)₂(μ₂-dppm)(μ₂-Cl)]BF₄ (1) rearranges under carbon monoxide to give [Rh₃(μ₂-dppm)₂(μ₂-CO)₃(K¹-CO)₃]BF₄ (2). Complex 2 has been structurally characterized by single crystal X-ray crystallography. The hydroformylation activities of 1 and 2 were compared for substrates styrene and 1-hexene and the activity of 2 found to be unexpectedly high.     

Characterization of rigid endo- and exo-η3-allyl carbonyl diethyldithiophosphate molybdenum complexes: crystal structure of endo-Mo(η3-allyl)(CO){η2-S2P(OEt)2}(Dppe)

The stereochemical rigid complexes endo-Mo(η³-allyl)(CO){η²-S₂P(OEt)₂}(η²-dppm) (2a) and exo-Mo(η³-allyl)(CO){η²-S₂P(OEt)₂}(η²-dppm) (2b) are accessible by the reaction of complex Mo(η³-allyl)(CO)₂{η²-S₂P(OEt)₂}(CH₃CN) (1) with dppm in refluxing acetonitrile. Treatment of 1 with dppe in the similar reactive conditions of 2 affords the sole complex endo-Mo(η³-allyl)(CO){η²-S₂P(OEt)₂}(η²-dppe) (3). Complex 3 is characterized by X-ray diffraction analysis.     

Phosphorus–carbon bond cleavage of Ph2PCH2PPh2 at a triruthenium center: synthesis and structural characterization of [Ru3(μ-CO)(CO)6(μ-PPh2)2(μ3-CH2PPh)]

The reaction of Ph₂PH with [Ru₃(CO)₁₀(μ-dppm)] (1) at 98°C gave [Ru₃(μ-CO)(CO)₆(μ-PPh₂)₂(μ₃-CH₂PPh)] (7) in 20% yield. Compound 7 was characterized by elemental analysis, ¹H and ³¹P{¹H} NMR and mass spectroscopic data and also by a single crystal structure determination. The compound is shown to consist of a triruthenium cluster with an unusual example of a triply bridging CH₂PPh ligand and two doubly bridging PPh₂ ligands.     

Migration of phenyl from dppm to allenylidene and cyclisation to 1,3-diarylindenyl on an Ru3 cluster

Thermolysis of Ru₃(μ₃-CCCPh₂)(μ-dppm)(μ-CO)(CO)₇ affords sequentially Ru₃(μ₃-PPhCH₂PPh₃)(μ₃-C₉H₅Ph₂)(CO)_n (n = 6 (3), 5 (4)) by trapping of the Ph group (from PC bond cleavage in the dppm ligand) by the allenylidene and cyclisation to a 1,3-diarylindenyl ligand, which is attached to the cluster in 3 via one of the Ar groups and in 4 by the η²:η²:η⁵-indenyl group; similar experiments with the di-4-tolylallenylidene provide information concerning the course of these reactions.     

Diastereotopic relationship between planar and central chiralities in the formation of Ru(η3-allyl)(CO)(PPh3)(L–L′) complexes

Hydride ruthenium complexes, RuHCl(CO)(PPh₃)₂(L–L^′) 3 (L–L^′=bidentate ligand having nitrogen and oxygen) react with allenes to give Ru(η³-allyl)(CO)(PPh₃)(L–L^′) complexes 5 in good yields via hydrometalation reaction. The complexes 5 have planar chirality at the η³-allyl ligand and central chirality at the Ru metal, and consist of one pair of enantiomers. Ligand substitution reaction of Ru(η³-allyl)Cl(CO)(PPh₃)₂ complexes 6 with bidentate ligands (L–L^′) also afford the complexes 5 which have the same stereochemistry as those formed by the hydrometalation reaction. The planar chirality is controlled by the central chirality at the Ru metal in both the formations of the complexes 5. The structure of 5a (L–L^′=N–N bidentate ligand) was determined by the X-ray crystal structure analysis.     

Reactivity of [Ru3(μ-H)(μ-Me2pz)(CO)10] with 2,4-hexadiyne. Characterization of the first tetranuclear ynenyl complex

The tetranuclear ynenyl complex [Ru₄(μ-η²-Me₂pz)(μ₄-η⁴-MeCHCCCMe)(μ-CO)(CO)₁₀] (Me₂pz=3,5-dimethylpyrazolate) has been prepared by reaction of [Ru₃(μ-H)(μ-η²-Me₂pz)(CO)₁₀] with 2,4-hexadiyne and has been characterized by X-ray diffraction methods. It consists of an unusual broken-wing butterfly (spiked triangle) tetraruthenium framework (64-electron) with all the metal atoms bridged by a hex-2-yn-4-en-4-yl ligand (7-electron donor). This type of coordination is unprecedented for ynenyl ligands.     

Formation of [8,8-η2-{(μ-Cl)2Ru(η6-p-cym)Ph2PCH2PPh2}-nido-8,7-RhSB9H10], a bimetallic derivative of the novel species [8,8-(η2-dppm)-8-(η1-dppm)-nido-8,7-RhSB9H10]

Treatment of [8,8-(η²-dppm)-8-(η¹-dppm)-nido-8,7-RhSB₉H₁₀] (I) with [Ru(η⁶-p-cym)Cl₂]₂ leads to the formation of a new bimetallic complex, [8,8-η²-{(μ-Cl)₂Ru(η⁶-p-cym)Ph₂PCH₂PPh₂}-nido-8,7-RhSB₉H₁₀], (II) containing the group [(μ-Cl)₂Ru(η⁶-p-cym)Ph₂PCH₂PPh₂] that coordinates in a multidentate mode to Rh.     

Synthesis and characterization of ruthenium (II) carbonyl complexes containing naphthyridine and acetylacetonate ligands and their catalytic activity in the hydrogen transfer reaction

A series of novel complexes of the Ru(L)₂(CO)₂ L = 2-(3′ methoxyphenyl)-1,8-naphthyridine (complex 1), and type Ru(acac)₂(L)(CO) with L = 2-(3′ methoxyphenyl)-1,8-naphthyridine (complex 2), 2-(2′-bromophenyl)-1,8-naphthyridine (complex 3) and 2-phenyl-1,8-naphthyridine (complex 4) was synthesized and characterized. We found that the complexes 2, 3, and 4 can be directly synthesized from Ru₃(CO)₁₂. The complex Ru(acac)₂(L)(CO) L = 2-(3′ methoxyphenyl)-1,8-naphthyridine (2) was characterized by X-ray single crystal analysis which confirms the monodentate coordination mode of the 1,8-naphthyridine derivate and the cis arrangement of the acac ligands. Preliminary studies in transfer hydrogenation of acetophenone in the presence of 2-propanol show the good catalytic activity of complex 2 with 92% conversion.     

Preparation and chemical properties of π-conjugated poly(1,10-phenanthroline-3,8-diyl)s with crown ether subunits

π-Conjugated polymers consisting of 1,10-phenanthroline units and crown ether subunits (Poly-1, Poly-2, and Poly-3) were prepared by dehalogenation polycondensation of the corresponding dibromo monomers using a zero-valent nickel complex as a condensing agent. They were characterized by elemental analysis, ¹H NMR and UV–Vis spectroscopies, and cyclic voltammetry (CV). They were partly soluble in CHCl₃, and the number average molecular weight of the soluble part of Poly-2, which had 15-crown-5 subunits, was estimated to be 5300. The polymers exhibited UV–Vis peaks at approximately λ_max = 360 nm, which was reasonable. Complexation with [Ru(bpy)₂]²⁺ and alkaline metal ions made the polymer soluble in organic solvents. The complexation of [Ru(bpy)₂]²⁺ to the 1,10-phenanthroline unit proceeded quantitatively, and the [Ru(bpy)₂]²⁺ complexes exhibited CV curves characteristic of [Ru(N-N)₃]²⁺ complexes.     

Synthesis and characterization of some metal carbonyls with 2-hydroxyacetophenone ethanesulfonylhydrazone

Five new complexes, [M(CO)₅(apesh)] [M=Cr; (1), Mo; (2), W; (3)], [Re(CO)₄ Br(apesh)] (4) and [Mn(CO)₃(apesh) ] (5) have been synthesized by the photochemical reaction of metal carbonyls [M(CO)₆] (M=Cr, Mo, W), [Re(CO)₅ Br], and [Mn(CO)₃ Cp] with 2-hydroxyacetophenone ethanesulfonylhydrazone (apesh). The complexes have been characterized by elemental analysis, mass spectrometry, FT-IR, ¹H NMR spectroscopy. The spectroscopic studies show that apesh behaves as a monodentate ligand coordinating via imine N donor atom in (1)–(4) and as tridentate ligand in (5).     

Ru4(μ-CO)(CO)9(η4-μ4-C6H4)(η2-μ1,μ4-PPhCH2CH2PPh2): an unusual pyrolysis product of Ru3(CO)10(dppe) containing a benzyne ligand

The thermal decomposition of Ru₃(CO)₁₀(dppe) in refluxing benzene gives, in contrast to the pyrolysis of the dppm analogue, the tetranuclear cluster Ru₄(μ-CO)(CO)₉(η⁴-μ₄-C₆H₄)(η²-μ₁,μ₄-PCH₂CH₂PPh₂) (1) along with Ru₃(CO)₉(η²-μ₁,μ₂-C₆H₅)(η³-μ₁,μ₂-PPhCH₂CH₂PPh₂) (2). The single-crystal structure analysis of 1 reveals a square-planar tetraruthenium skeleton containing a η⁴-μ₄-benzyne ligand as well as a η²-μ₁,μ₄-phosphinidene–phosphine ligand.     

Diruthenium alkyne chemistry: stepwise formation of an alkenyl(alkynyl)vinylidene complex

A new form of reactivity, in which up to three terminal alkyne molecules may react with the binuclear compound [Ru₂(CO₄)(μ-CO)(μ-dppm)₂] without alkyne coupling, is described.     

The unexpected synthesis of rhodium(I) complexes with the 1-(2′-pyridyl)-3-oxo-1-propenoxide anionic ligand

The enaminone compound 1-(2^′-pyridyl)-3-dimethylamine-1-propenone (1) reacts with [{Rh(μ-OY)(COD)}₂] (OY=OMe, OH) dimers in the presence of water to form a mononuclear square-planar rhodium(I) complex 2, which incorporates the unexpected 1-(2^′-pyridyl)-3-oxo-1-propenoxide ligand (N, O). The mediation of the metal in this ligand transformation is demonstrated. The crystal structure of [Rh(N,O)(COD)] (2) reveals the coordination of the new propenoxide ligand as a N,O-bidentate with the presence of an additional non-coordinated aldehyde group. Complex 2 reacts with CO by displacement of the COD molecule, but maintaining the N,O-coordination of the chelate propenoxide ligand.     

Ru(II)–CO complexes of thioarylazoimidazoles: Syntheses,structures, spectroscopy and DFT calculation

The complexes, cis-(CO)-trans-(Cl)-[Ru(SRaaiNR)(CO)₂Cl₂] (2) and trans-(Cl)-[Ru(SRaaiNR)(CO)Cl₂] (3) (SRaaiNR = 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazoles; R = Me (1a) and Et (1b)) have been synthesized and characterized. The structural confirmation is achieved by single crystal X-ray structure determinations. The complexes show Ru(III)/Ru(II) couple and ligand reductions. Electronic structure and spectral properties of the complexes have been explained with the DFT and TDDFT calculation.     

Approaches to the Chemical,Electrochemical, and Photochemical Activation of Carbon Dioxide by Transition Metal Complexes

The activation of CO₂ by chemical, electrochemical, and photochemical means is discussed. Binuclear transition metal complexes mediate oxygen atom transfers from CO₂ by three distinct chemical pathways: (i) deoxygenation of CO₂, (ii) multiple bond metathesis, and (iii) disproportionation. The complex Ir₂ (μ-CNR)₂(CNR)₂(dmpm),(dmpm = bis(dimethylphosphino)methane) undergoes double cycloaddition of CO₂ to its μ-CNR ligands. A subsequent reaction produces the bis(carbamoyl) complex [Ir₂(μ-CO)(μ-H)(CONHR)₂(CNR)₂(dmpm)₂]Cl. Isotope labelling studies show that the μ-CO ligand results from net deoxygenation of CO₂. In contrast, the binuclear nickel complex Ni₂(μ-CNMe)(CNMe)₂(dppm)₂ (dppm = bis-(diphenylphosphino)methane) reacts with liquid CO₂ to give the tricarbonyl complex Ni₂(μ-CO)(CO)₂(dppm)₂. Isotope labelling indicates that the carbonyl ligands are not derived from CO₂ deoxygenation, but from C/CO triple bond metathesis. The reaction of CO₂ with the Ir(0) complex Ir₂(CO)₃(dmpm)₂ leads to CO₂ disproportionation by formation of the carbonate, Ir₂(CO₃)(CO)₂(dmpm)₂, and tetracarbonyl, Ir₂(CO)₄(dmpm)₂, complexes. The complex Ir₂(CO₃)(CO)₂ (dmpm)₂ undergoes reversible O-atom transfers from its carbonate ligand. The electrochemical activation of CO₂ by the binuclear Ni₂(μ-CNMe)(CNMe)₂(dppm)₂ and trinuclear [Ni₃(μ-CNMe)(μ-I)(dppm)₃][PF₆] species is described. The triangular nickel complex [Ni₃(μ₃-CNMe)(μ₃-I)(dppm)₃][PF₆] is an electrocatalyst for the reduction of CO₂. The cluster exhibits a reversible single electron reduction at E⁰(^+/0) = −1.09 V vs. Ag/AgCl. In the presence of CO₂, the cluster reduces CO₂ by an EC' electrochemical mechanism. The reduction products correspond to the disproportionation and H-atom abstraction products of CO₂^*−, with a partitioning ratio of 10:1. Isotope labelling studies with ¹³CO₂ indicate that ¹³CO₂^*− disproportionation produces ¹³CO and ¹³CO₃²⁻. Studies of the photochemical activation of CO₂ by Ni₂(μ-CNMe)(CNMe)₂(dppm)₂ are described. The bimolecular photochemical addition of CO₂ to the complex was examined by laser transient absorbance spectroscopy. Photolysis at 355nm in the presence of CO₂ (1 atm) leads to cycloaddition of CO₂ to the μ-CNMe ligand and the complex Ni₂(μ-CN(Me)C(O)O)(CNMe)₂(dppm)₂ with Φ₃₅₅=0.05. The triplet excited state of Ni,(μ-CNMe)(CNMe)₂(dppm)₂ was determined to react with CO₂ with the bimolecular reaction rate constant k = 1 × 10⁴ M⁻¹ s⁻¹. Bridging ligand substituent effects and solvent dependence of the lowest energy electronic absorption spectral bands of the series of complexes, Ni₂(μ-L)(CNMe)₂(dppm)₂, L = CNMe, CNC₆H₅, CN-p-C₆H₄Cl. and CN-p-C₆H₄Me, confirm the assignment of di-metal to bridging ligand charge transfer (M₂→μ-LCT). This assignment is supported by results of extended Hückel calculations which indicate a LUMO of predominantly μ-isocyanide π* character. A systematic study of the nature of the lowest excited states of related d¹⁰–d¹⁰ binuclear complexes of the type Ni₂(μ-L)(CNMe)₂(dppm)₂, where L = CNMe(Ph)⁺, CNMe₂⁺, CNMe(C₅H₁₁)⁺, CNMe(H)⁺, CNMe(CH₂C₆H₅)⁺, and NO⁺ reveals dramatic differences in the lowest excited states of the three classes of complexes: μ-isocyanide, μ-aminocarbyne, and μ-nitrosyl. Spectroscopic and extended Hückel MO studies confirm that the μ-isocyanide complexes are characterized by di-metal to bridging ligand charge transfer (M₂ → μ-LCT) excited states. However, the μ-aminocarbyne and μ-nitrosyl complexes exhibit bridging ligand to metal charge transfer (μ-L→M₂) and intraligand (IL) lowest excited states, respectively.     

Unexpected fragmentation of the Fe3(CO)9(μ3-Se)(μ3-AsCH3) cluster core in the reaction with CpCo(CO)2: synthesis and structure of Fe3(CO)6(μ3-Se)(μ-AsCH3{CpFe(CO)2})2(μ-CO)

The [Fe₃(CO)₆(μ₃-Se)(μ-AsCH₃{CpFe(CO)₂})₂(μ-CO)] (Cp=η⁵-C₅H₅) cluster has been obtained by the reaction of [Fe₃(CO)₉(μ₃-Se)(μ₃-AsCH₃)] with [CpCo(CO)₂]. Its crystal and molecular structures have been determined by X-ray analysis.     

Supported organometallic complexes. Part 37: synthesis and structures of diamine-bis(methoxyethyldimethylphosphine)ruthenium(II) complexes

The first two examples of diamineruthenium(II) complexes containing the hemilabile methoxyethyldimethylphosphine ligand, Cl₂Ru(en)(η¹-Me₂PCH₂CH₂OMe)₂ (2a) and Cl₂Ru[(R,R)-dpen](η¹-Me₂PCH₂CH₂OMe)₂ (2b) (en=1,2-diaminoethane, (R,R)-dpen=1R,2R-1,2-diamino-1,2-diphenylethane) have been synthesized and structurally characterized.     

A triheterometallic cluster: synthesis and structural characterisation of a cyclopentadienyl-substituted pentanuclear cluster based on an Os3CoRu metal core

The ionic coupling of the carbonyl cluster anion [Os₃Co(CO)₁₃]⁻ (1) with [Ru(η⁵-C₅H₅)(NCMe)₃]⁺ affords the new pentanuclear triheterometallic cluster Os₃CoRu(CO)₁₃(η⁵-C₅H₅) (2) as well as the known bimetallic cluster compounds HOs₃Ru(CO)₁₁(η⁵-C₅H₅) and Os₃Ru₂(CO)₁₁(η⁵-C₅H₅)₂. The crystal structure of cluster 2 shows that the metal framework is based on a trigonal bipyramid (approximate C_s symmetry) with the Ru, Co and an Os atom occupying the equatorial metal plane.     

Preparation of Ru(η3-2-alkenylallyl)(CO)Cl(PPh3)2 complexes via carbometallation of allenes with alkenyl ruthenium complexes

Alkenyl ruthenium complex, Ru(CHCHR)(Cl)(CO)(PPh₃)₂ 1, reacted with allenes 2 to give η³-allyl ruthenium complexes, Ru(η³-2-alkenylallyl)(Cl)(CO)(PPh₃)₂ 3, in good yields. The reaction depends on the structure of the alkenyl group. When R was phenyl or methoxycarbonyl group, the carbometallated complex 3 was yielded as a sole product. However, when R was butyl or trimethylsilyl group, besides the carbometallation product as main product, was obtained a small amount of 2-unsubstituted η³-allyl ruthenium complex which was formed via β-elimination of the alkenyl complex followed by the reaction with allene. Structure of 3 was determined by the X-ray crystal structure analysis.