Water-soluble (η-arene)ruthenium(II)-phosphine complexes and their catalytic activity in the hydrogenation of bicarbonate in aqueous solution

The reactions of [(η⁶-C₆H₆)RuCl₂]₂ and [(η⁶-p-cymene)RuCl₂]₂ with hydrogen in the presence of the water-soluble phosphines tppts (meta-trisulfonated triphenylphosphine) and pta (1,3,5-triaza-7-phosphaadamantane) afforded as the main species [(η⁶-C₆H₆)RuH(tppts)₂]⁺, [(η⁶-C₆H₆)RuH(pta)₂]⁺, [(η⁶-p-cymene)RuH(tppts)₂]⁺ and [(η⁶-p-cymene)RuH(pta)₂]⁺. This latter complex was also formed in the reaction of [(η⁶-p-cymene)RuCl₂(pta)] and hydrogen with a redistribution of pta. In addition, prolonged hydrogenation at elevated temperatures and in the presence of excess of pta led to the formation of the arene-free [RuH(pta)₄Cl], [RuH(pta)₄(H₂O)]⁺, [RuH₂(pta)₄] and [RuH(pta)₅]⁺ complexes. Ru-hydrides, such as [(η⁶-arene)RuH(L)₂]⁺, catalyzed the hydrogenation of bicarbonate to formate in aqueous solutions at p(H₂)=100 bar, T=50-70 °C.     

Selenoquinones Stabilized by Ruthenium(II) Arene Complexes: Synthesis,Structure, and Cytotoxicity

A new series of monoselenoquinone and diselenoquinone π complexes, [(η⁶‐p‐cymene)Ru(η⁴‐C₆R₄SeE)] (R=H, E=Se ( 6 ); R=CH₃, E=Se ( 7 ); R=H, E=O ( 8 )), as well as selenolate π complexes [(η⁶‐p‐cymene)Ru(η⁵‐C₆H₃R₂Se)][SbF₆] (R=H ( 9 ); R=CH₃ ( 10 )), stabilized by arene ruthenium moieties were prepared in good yields through nucleophilic substitution reactions from dichlorinated‐arene and hydroxymonochlorinated‐arene ruthenium complexes [(η⁶‐p‐cymene)Ru(C₆R₄XCl)][SbF₆]₂ (R=H, X=Cl ( 1 ); R=CH₃, X=Cl ( 2 ); R=H, X=OH ( 3 )) as well as the monochlorinated π complexes [(η⁶‐p‐cymene)Ru(η⁵‐C₆H₃R₂Cl)][SbF₆]₂ (R=H ( 4 ); R=CH₃ ( 5 )). The X‐ray crystallographic structures of two of the compounds, [(η⁶‐p‐cymene)Ru(η⁴‐C₆Me₄Se₂)] ( 7 ) and [(η⁶‐p‐cymene)Ru(η⁴‐C₆H₄SeO)] ( 8 ), were determined. The structures confirm the identity of the target compounds and ascertain the coordination mode of these unprecedented ruthenium π complexes of selenoquinones. Furthermore, these new compounds display relevant cytotoxic properties towards human ovarian cancer cells.     

Synthesis,Characterization and Molecular Structure of a new (?6-P-Cymene) Ruthenium(II) Amidine Complex, [(?6-P-Cymene)Ru{NH=C(Me)3,5-Dmpz}(3,5-Hdmpz)](BF4)2·H2O

A new arene ruthenium(II) complex [(η⁶-p-cymene)Ru(L)(3,5-Hdmpz)](BF₄)₂[sdot]H₂O (L = 1-methylcarbaldimino-3,5-dimethylpyrazole; 3,5-Hdmpz = 3,5-dimethylpyrazole) has been synthesized. The ligand L has been generated in situ through the condensation of 3,5-dimethylpyrazole and acetonitrile in the presence of [{(η⁶-p-cymene)RuCl₂}₂]. The complex [(η⁶-p-cymene)Ru{NH=C(Me)3,5-dmpz}(3,5-Hdmpz)](BF₄)₂[sdot]H₂O crystallizes in monoclinic space group P2₁/c, a = 10.943(2), b = 26.394(7), c = 11.502(1) Å, Β = 115.43(1)°, V = 3000.1(19) ų and Z = 4. The compound has been characterized by FTIR, ¹H NMR, 2D-COSY NMR spectroscopy and a single-crystal X-ray diffraction study.     

Synthesis and properties of monometallic, homo- and heterobimetallic complexes based on {(η-arene)RuCl} and {(η-arene)OsCl} fragments with tetrathioether and tetraselenoether ligands

The reaction of [Ru(η⁶-p-cymene)Cl₂]₂ with 2.0 mol equivalents of C(CH₂SMe)₄, C(CH₂SeMe)₄, 1,2,4,5-C₆H₂(CH₂SMe)₄ or 1,2,4,5-C₆H₂(CH₂SeMe)₄ (L₄) and [NH₄][PF₆] in ethanol solution forms the [RuCl(η⁶-p-cymene){κ²-L₄}][PF₆] complexes. Similar Os(II) complexes are obtained starting with [Os(η⁶-p-cymene)Cl₂]₂. Treatment of [RuCl(η⁶-p-cymene){κ²-L₄}][PF₆] with a further 0.5 mol equivalents of [Ru(η⁶-p-cymene)Cl₂]₂ or reaction of [Ru(η⁶-p-cymene)Cl₂]₂ directly with 1.0 mol equivalent of L₄ forms the homobimetalllic [{RuCl(η⁶-p-cymene)}₂{κ²κ′²-L₄}][PF₆]₂. Reaction of [OsCl(η⁶-p-cymene)-{κ²-C(CH₂SeMe)₄}][PF₆] with [Ru(η⁶-p-cymene)Cl₂]₂ or [PtCl₂(MeCN)₂] affords the heterobimetallic [{OsCl(η⁶-p-cymene)}{RuCl(η⁶-p-cymene)}{κ²κ′²-C(CH₂SeMe)₄}][PF₆]₂ and [{OsCl(η⁶-p-cymene)}{PtCl₂}{κ²κ′²-C(CH₂SeMe)₄}][PF₆] respectively. The complexes have been characterised by multinuclear NMR and IR spectroscopy and X-ray crystallography.     

Syntheses of (η6-p-cymene)ruthenium(II) piano-stool amine complexes: molecular structure of [(η6-C10H14)RuCl2(H2N-C6H4-p-Cl)]

The dimeric complex [{(η⁶-p-cymene)Ru(μ-Cl)Cl}₂] (1) reacts with S,N-donor Schiff base ligands, para-substituted S-(thiophen-2-ylmethylene)phenylamines in methanol to give mononuclear amine complexes of the type [(η⁶-p-cymene)RuCl₂(NH₂–C₆H₄–p-X)] {X?=?H (2a); X?=?CH₃ (2b); X?=?OCH₃ (2c); X?=?Cl (2d); Br (2e) X?=?NO₂ (2f), respectively} by hydrolysis of the imine group of the ligand after coordination to the metal. The complexes were characterized by analysis and IR and NMR spectroscopy. The molecular structure of [(η⁶-C₁₀H₁₄)RuCl₂(H₂N–C₆H₄–p-Cl)] (2d) was established by a single-crystal X-ray diffraction study.     

N-Heterocyclic Carbene Analogues of Nucleophilic Phosphinidene Transition Metal Complexes

Chloride abstraction from the complexes [(η⁶-p-cymene){(IDipp)P}MCl] ( 2 a , M=Ru; 2 b , M=Os) and [(η⁵-C₅Me₅){(IDipp)P}IrCl] ( 3 b , IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) with sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBAr^F) in the presence of trimethylphosphine (PMe₃), 1,3,4,5-tetramethylimidazolin-2-ylidene (^MeIMe) or carbon monoxide (CO) afforded the complexes [(η⁶-p-cymene){(IDipp)P}M(PMe₃)]BAr^F] ( 4 a , M=Ru; 4 b , M=Os), [(η⁶-p-cymene){(IDipp)P}Os(^MeIMe)]BAr^F] ( 5 ) and [(η⁵-C₅Me₅){(IDipp)P}IrL][BAr^F] ( 6 , L=PMe₃; 7 , L=^MeIMe; 8 , L=CO). These cationic N-heterocyclic carbene-phosphinidene complexes feature very similar structural and spectroscopic properties as prototypic nucleophilic arylphosphinidene complexes such as low-field ³¹P NMR resonances and short metal-phosphorus double bonds. Density functional theory (DFT) calculations reveal that the metal-phosphorus bond can be described in terms of an interaction between a triplet [(IDipp)P]⁺ cation and a triplet metal complex fragment ligand with highly covalent σ- and π-contributions. Crystals of the C−H activated complex 9 were isolated from solutions containing the PMe₃ complex, and its formation can be rationalized by PMe₃ dissociation and formation of a putative 16-electron intermediate [(η⁵-C₅Me₅)Ir{P(IDipp)}I][BAr^F], which undergoes C−H activation at one of the Dipp isopropyl groups and addition along the iridium-phosphorus bond to afford an unusual η³-benzyl coordination mode.     

Preparation and reactivity of p-cymene complexes of ruthenium and osmium incorporating 1,3-triazenide ligands

p-Cymene complexes MCl₂(η⁶-p-cymene)L [M = Ru, Os; L = P(OEt)₃, PPh(OEt)₂, (CH₃)₃CNC] were prepared by allowing [MCl(μ-Cl)(η⁶-p-cymene)]₂ to react with phosphites or tert-butyl isocyanide. Treatment of MCl₂(η⁶-p-cymene)L complexes with 1,3-ArNNN(H)Ar triazene and an excess of NEt₃ gave the cationic triazenide derivatives [M(η²-1,3-ArNNNAr)(η⁶-p-cymene)L]BPh₄ (Ar = Ph, p-tolyl). Neutral triazenide complexes MCl(η²-1,3-ArNNNAr)(η⁶-p-cymene) (M = Ru, Os) were also prepared by allowing [MCl(μ-Cl)(η⁶-p-cymene)]₂ to react with 1,3-diaryltriazene in the presence of triethylamine. p-Cymene complexes MCl₂(η⁶-p-cymene)L reacted with equimolar amounts of 1,3-ArNNN(H)Ar triazene to give both triazenide complexes [M(η²-1,3-ArNNNAr)(η⁶-p-cymene)L]BPh₄ and amine derivatives [MCl(ArNH₂)(η⁶-p-cymene)L]BPh₄. A reaction path for the formation of the amine complex is also reported. The complexes were characterised by spectroscopy and X-ray crystallography of RuCl₂(η⁶-p-cymene)[PPh(OEt)₂] and [Ru(η²-1,3-p-tolyl-NNN-p-tolyl)(η⁶-p-cymene){CNC(CH₃)₃}]BPh₄. Selected triazenide complexes were studied as catalysts in the hydrogenation of 2-cyclohexen-1-one and cinnamaldehyde.     

Synthesis,Structure, Reactivity and Catalytic Implications of a Cationic,Acetylide-Bridged Trigold–JohnPhos Species

The cationic complex [(JohnPhos–Au)₃(acetylide)][SbF₆] (JohnPhos=(2-biphenyl)di-tert-butylphosphine, L1) has been characterised structurally and features an acetylide–trigold(I)–JohnPhos system; the trinuclear–acetylide unit, coordinated to the monodentate bulk phosphines, adopts an unprecedented μ,η¹,η²,η¹ coordination mode with an additional interaction between distal phenyl rings and gold centres. Other cationic σ,π-[(gold(I)L1)₂] complexes have also been isolated. The reaction of trimethylsilylacetylene with various alcohols (iPrOH, nBuOH, n-HexOH) catalysed by cationic [Au^IL1][SbF₆] complexes in CH₂Cl₂ at 50 °C led to the formation of acetaldehyde acetals with a high degree of chemo- and regioselectivity. The reaction mechanism was studied, and several organic and inorganic intermediates have been characterised. A comparative study with the analogous cationic [Cu^IL1][PF₆] complex revealed different behaviour; the copper metal is lost from the coordination sphere leading to the formation of cationic vinylphosphonium and copper nanoparticles. Additionally, a new catalytic approach for the formation of this high-value cationic vinylphosphonium has been established.     

Reactivity studies of (η6-arene)ruthenium(II) dimers with arylazoimidazole ligands: molecular structure of [(η6-p-cymene)RuCl(Me-C6H4-Nequals;N-C3H2N2-1-CH3)]PF6

The complexes [{(η ⁶-arene)Ru(μ-Cl)Cl}₂] (arene?=?p-cymene (1), hexamethylbenzene reacts at low temperature with the arylazoimidazole (RaaiR′) ligands 2-(phenylazo)imidazole (Phai-H), 1-methyl-2-(phenylazo)imidazole (Phai-Me), 1-ethyl-2-(phenylazo)imidazole (Phai-Et), 2-(tolylazo)imidazole (Tai-H), 1-methyl-2-(tolylazo)imidazole (Tai-Me) and 1-ethyl-2-(tolylazo)imidazole (Tai-Et) to give complexes of the type [(η ⁶-arene)RuCl(RaaiR′)]⁺. The complexes were characterized by FTIR and ¹H NMR and ¹³C {¹H} NMR spectroscopy. The molecular structure of [(η ⁶-p-cymene)RuCl(Me-C₆H₄-N=N-C₃H₂N₂-1-CH₃)]PF₆ was established by single-crystal X-ray diffraction methods.     

Mono- and di-nuclear azido η6-p-cymene ruthenium(II) complexes; synthesis,reactivity, and structures

The azide bridge complex [(η⁶-p-cymene)Ru(µ-N₃)Cl]₂ (2) was prepared from the reaction of sodium azide with [(η⁶-p-cymene)RuCl]₂ in ethanol. The molecular structures and spectroscopic properties of the various azido ruthenium complexes so obtained from the reaction with monodentate and bidentate ligands are described.     

Syntheses of [(η 6- p -cymene)Ru(EPh3)2Cl]+ complexes and molecular structure of chloro(η 6- p -cymene)-bis(triphenylphosphine)ruthenium(II) tetrafluoroborate (E = P,As and Sb)

The reaction of [(η⁶-p-cymene)RuCl₂]₂ with excess EPh₃ (E = P, As, Sb) in methanol in the presence of ammonium tetrafluoroborate leads to the formation of complexes of the type [(η⁶-p-cymene)Ru(EPh₃)₂Cl]BF_4, E = P (1), As (2), Sb (3), which arise through cleavage of the chloride bridges. These complexes were characterized by spectral and analytical data. The crystal structure of 1 was solved by single-crystal X-ray crystallography in order to establish the exact structure in the solid state. The complex crystallizes in monoclinic space group P2₁/n (#14) with a = 12.42500(10), b = 30.1925(3), c = 11.06530(10)?Å, β = 103.1470(10)°.     

Syntheses and characterization of cyano-bridged homo and hetero bimetallic complexes containing η and η-cyclic hydrocarbons

The reactions of [(ind)Ru(PPh₃)₂CN] (ind = η⁵-C₉H₇) (1) and [CpRu(PPh₃)₂CN] (Cp = η⁵-C₅H₅) (2) with [(η⁶-p-cymene)Ru(bipy)Cl]Cl (bipy = 2,2′-bipyridine) (3) in the presence of AgNO₃/NH₄BF₄ in methanol, respectively, yielded dicationic cyano-bridged complexes of the type [(ind)(PPh₃)₂Ru(μ-CN)Ru(bipy)(η⁶-p-cymene)](BF₄)₂ (4) and [Cp(PPh₃)₂Ru(μ-CN)Ru(bipy)(η⁶-p-cymene)](BF₄)₂ (5). The reaction of [CpRu(PPh₃)₂CN] (2), [CpOs(PPh₃)₂CN] (6) and [CpRu(dppe)CN] (7) with the corresponding halide complexes and [(η⁶-p-cymene)RuCl₂]₂ formed the monocationic cyano-bridge complexes [Cp(PPh₃)₂Ru(μ-CN)Os(PPh₃)₂Cp](BF₄) (8), [Cp(PPh₃)₂Os(μ- CN)Ru(PPh₃)₂Cp](BF₄) (9) and [Cp(dppe)Ru(μ-CN)Os(PPh₃)₂Cp](BF₄) (10) along with the neutral complexes [Cp(PPh₃)₂Ru(μ-CN)Ru (η⁶-p-cymene)Cl₂] (11), [Cp(PPh₃)₂Os(μ-CN)Ru(η⁶-p-cymene)Cl₂] (12), and [Cp(dppe) Ru(μ-CN)Ru(η⁶-p-cymene)Cl₂] (13). These complexes were characterized by FT IR, ¹H NMR, ³¹P{¹H} NMR spectroscopy and the molecular structures of complexes 4, 8 and 11 were solved by X-ray diffraction studies.     

Preparation and reactivity of half-sandwich hydrazine complexes of ruthenium and osmium

Hydrazine complexes [MCl(η⁶-p-cymene)(RNHNH₂)L]BPh₄ (1–6) [M = Ru, Os; R = H, Me, Ph; L = P(OEt)₃, PPh(OEt)₂, PPh₂OEt] were prepared by allowing dichloro complexes MCl₂(η⁶-p-cymene)L to react with hydrazines RNHNH₂ in the presence of NaBPh₄. Treatment of ruthenium complexes [RuCl(η⁶-p-cymene)(RNHNH₂)L]BPh₄ with Pb(OAc)₄ led to acetate complex [Ru(κ²–O₂CCH₃)(η⁶-p-cymene)L]BPh₄ (7). Instead, the reaction of osmium derivatives [OsCl(η⁶-p-cymene)(CH₃NHNH₂)L]BPh₄ with Pb(OAc)₄ afforded the methyldiazenido complex [Os(CH₃N₂)(η⁶-p-cymene)L}]BPh₄ (8). Treatment with HCl of this diazenido complex 8 led to the methyldiazene cation [OsCl(CH₃NNH)(η⁶-p-cymene)L}]⁺ (9⁺). The complexes were characterised spectroscopically and by X-ray crystal structure determination of [OsCl(η⁶-p-cymene)(PhNHNH₂){PPh(OEt)₂}]BPh₄ (6b) and [Ru(κ²–O₂CCH₃)(η⁶-p-cymene){PPh(OEt)₂}]BPh₄ (7b).     

Synthesis,characterization and cytotoxic activity of organoruthenium(II)-halido complexes with 5-chloro-1H-benzimidazole-2-carboxylic acid

Three new ruthenium(II)-arene halido complexes, [(η⁶-p-cymene) RuX(L)] (1–3), were synthesized in a reaction of [(η⁶-p-cymene)RuX₂]₂ with 5-chloro-1H-benzimidazole-2-carboxylic acid (HL) in ethanol (X^– = Cl^– (1), Br^– (2), I^– (3)). The complexes were characterized by elemental analysis, mass spectrometry, IR, ¹H and ¹³C NMR spectroscopy. The cytotoxic activity of the ligand precursor and its ruthenium complexes was tested by MTT assay in human cancer cell lines: lung adenocarcinoma (A549), myelogenous leukemia (K562) as well as in one normal human fetal lung fibroblast cell line (MRC-5). The results show that ruthenium(II)-arene complexes possess enhanced cytotoxicity when compared to HL in the range of concentrations up to 300 µM. In terms of halido ligand substitution, cytotoxic activity toward A549 and K562 cell lines in 1–3 serie significantly increased (e.g., IC₅₀ values for K562: 1: 205.76 µM; 2: 174.77 µM; 3: 83.97 µM). All studied compounds were found to be ineffective toward MRC-5. Hydrolysis of 1–3 was followed by UV-vis spectroscopy at 25?°C, revealing ligand-substitution reactions at the Ru(II) center. Compounds 2 and 3 underwent rapid hydrolysis ranging from a few minutes for the aquation to ca. 20?min, confirming typical Ru-arene behavior in aqueous solutions.     

Coordination and Hydroboration of Ru(II)-Borate Complexes: Dihydridoborate vs. Bis(dihydridoborate)

Treatment of [Cp*RuCl₂]₂, 1 , [(COD)IrCl]₂, 2 or [(p-cymene)RuCl₂]_2, 3 (Cp*=η⁵-C₅Me_5, COD= 1,5-cyclooctadiene and p-cymene=η⁶-ⁱPrC₆H₄Me) with heterocyclic borate ligands [Na[(H₃B)L], L₁ and L₂ ( L₁ : L=amt, L₂ : L=mp; amt=2-amino-5-mercapto-1,3,4-thiadiazole, mp=2-mercaptopyridine) led to the formation of borate complexes having uncommon coordination. For example, complexes 1 and 2 on reaction with L₁ and L₂ afforded dihydridoborate species [L^AM(μ-H)₂BHL] 4 – 6 ( 4 : L^A=Cp*, M=Ru, L=amt; 5 : L^A=Cp*, M=Ru, L=mp; 6 : L^A=COD, M=Ir, L=mp). On the other hand, treatment of 3 with L₂ yielded cis- and trans-bis(dihydridoborate) species, [Ru{(μ-H)₂BH(mp)}₂], cis- 7 and trans- 7 . The isolation and structural characterization of fac- and mer-[Ru{(μ-H)₂BH(mp)}{(μ-H)BH(mp)₂}], 8 from the same reaction offered an insight into the behaviour of these dihydridoborate species in solution. Fascinatingly, despite having reduced natural charges on Ru centres both at cis-and trans- 7 , they underwent hydroboration reaction with alkynes that yielded both Markovnikov and anti-Markovnikov addition products, 10 a – d .     

Bimetallic complexes with ruthenium and tantalocene moieties: Synthesis and use in a catalytic cyclopropanation reaction

The reaction of the tantalocene dichloride monophosphines (1-2) with the binuclear complex [(p-cymene)RuCl₂]₂ gives the heterobimetallic compounds (p-cymene)[(η⁵-C₅H₅)(μ-η⁵:η¹-C₅H₄(CH₂)₂PR₂)TaCl₂]RuCl₂ (3-4). The air oxidation of these bimetallic species 3-4, leads to the cationic hydroxo tantalum ruthenium derivatives 5-6. The last ones are easily deprotonated by a base to afford the oxo analogues 7-8. A preliminary assessment in catalytic cyclopropanation of styrene with tantalum ruthenium bimetallic complexes 3-8 as precatalysts revealed a cooperative effect with a subtle role of the early metal fragment.     

Donor-Stabilised [SbF4]+: SbF5 as a Fluoride-Ion Donor

Antimony pentafluoride is a strong Lewis acid and fluoride-ion acceptor that has not previously demonstrated any discreet fluoride-ion donor properties. The first donor-stabilised [SbF₄]⁺ cations were prepared from the autoionisation of SbF₅ in the presence of bidentate N-donor ligands 2,2’-bipyridine (bipy) and 1,10-phenanthroline (phen) as their [SbF₆]⁻ salts. The [SbF₄(N−N)][Sb₂F₁₁] (N−N=bipy, phen) salts were synthesised by the addition of one equivalent of SbF₅⋅SO₂ to [SbF₄(N−N)][SbF₆] in liquid SO_2. The salts show remarkable stability and were characterised by Raman spectroscopy and multinuclear NMR spectroscopy. The crystal structures of [SbF₄(phen)][SbF₆] ⋅ 3CH₃CN and [SbF₄(phen)][SbF₆] ⋅ 2SO₂ were determined, showing distorted octahedral cations. DFT calculations and NBO analyses reveal that significant degree of electron-pair donation from N to Sb stabilizes [SbF₄]⁺ with the Sb−N bond strength being approximately two thirds of that of the Sb−F bonds in these cations and the cationic charge being primarily ligand-centred.     

Heterobimetallische phosphanido-verbrückte Zweikern-Komplexe - Synthese von cis-rac-[(η-C5H4R)2Zr{μ-PH(2,4,6−iPr3C6H2)}2M(CO)4] (RMe,MCr,Mo; RH,MMo)

Heterobimetallic Phosphanido-bridged Dinuclear Complexes - Syntheses of cis-rac-[(η-C₅H₄R)₂Zr{μ-PH(2,4,6-ⁱPr₃C₆H₂)}₂M(CO)₄] (R?Me, M?Cr, Mo; R?H, M?Mo) The zirconocene bisphosphanido complexes [(η-C₅H₄R)₂Zr{PH(2,4,6-ⁱPr₃C₆H₂)}₂] (R?Me, H) react with [(NBD)M(CO)₄] (NBD?norbornadiene, M?Cr, Mo) to give only one diastereomer of the phosphanido-bridged heterobimetallic dinuclear complexes cis-rac-[(η-C₅H₄R)₂Zr{μ-PH(2,4,6-ⁱPr₃C₆H₂)}₂M(CO)₄] [R?Me, M?Cr ( 1 ), Mo ( 2 ); R?H, M?Mo ( 3 )]. However, no reaction was observed between [(η-C₅H₅)₂Zr{PH(2,4,6-^tBu₃ C₆H₂)}₂] and [Pt(PPh₃)₄]. 1—3 were characterised spectroscopically. For 1—3 , the presence of the racemic isomer was shown by NMR spectroscopy. No reaction was observed at room temperature for 3 and CS₂, (NO)BF₄, Me₃NO or PH(2,4,6-Me₃C₆H₂)₂. With Et₂AlH or PhC?CH decomposition of 3 was observed.     

Half-sandwich ruthenium(II) complexes containing a tricyclic β-iminophosphine ligand: Catalytic activity in Diels–Alder reactions

The diastereoselective κ²-P,N-coordination of a chiral tricyclic β-iminophosphine ligand to the half-sandwich ruthenium(II) fragments [RuCl(η⁶-arene)]⁺ (arene = C₆H₆, p-cymene, 1,3,5-C₆H₃Me₃, C₆Me₆), [Ru(η⁶-p-cymene)(NCMe)]²⁺ and [Ru(η⁵-C₅H₅)(NCMe)]⁺ is described. The structures of the resulting mono- and dicationic cymene derivatives have been confirmed by X-ray crystallography. Studies on the catalytic activity of these Ru(II) compounds in Diels–Alder cycloaddition processes are also reported.     

Half-sandwich Ru(II), Ir(III) and Rh(III) complexes with bridging or chelating N-heterocyclic bis-carbene ligand: Synthesis and characterization

N-heterocyclic bis-carbene ligand (bis-NHC) which was derived from 1,1′-diisopropyl-3,3′-ethylenediimidazolium dibromide (L·2HBr) via silver carbene transfer method, reacted with [(η⁶-p-cymene)RuCl₂]₂ and [Cp^∗MCl₂]₂ (Cp^∗ = η⁵-C₅Me_5, M = Ir, Rh) respectively, afforded complexes [(η⁶-p-cymene)RuCl₂]₂(L) (1), [Cp^∗IrCl₂]₂(L) (2) and [Cp^∗RhCl(L)][Cp^∗RhCl₃] (3). When [Cp^∗IrCl₂]₂ was treated with 2 equiv AgOTf at first, and then reacted with bis-NHC ligand, [Cp^∗IrCl(L)]OTf (4) was obtained. The molecular structures of complexes 1-4 were determined by X-ray single crystal analysis, showing that 1 and 2 adopted bridging coordination mode, 3 and 4 adopted chelating coordination mode. All of these complexes were characterized by ¹H, ¹³C NMR spectroscopy and element analysis.