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 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.     

Preparation and reactivity of osmium(II) hydride complexes with phosphites and polypyridyls

Chloro-complexes [OsCl(N-N)P₃]BPh₄ (1, 2) [N-N=2,2^′-bipyridine (bpy) and 1,10-phenanthroline (phen); P=P(OEt)₃ and PPh(OEt)₂] were prepared by allowing OsCl₄(N-N) to react with zinc dust in the presence of phosphites. Treatment of the chloro-complexes 1, 2 with NaBH₄ yielded, in the case of bpy, the hydride [OsH(bpy)P₃]BPh₄ (4) derivatives. Mono-phosphite [OsCl(bpy)₂P]BPh₄ (3) complexes were also prepared by reacting the [OsCl₂(bpy)₂]Cl compound with zinc dust in the presence of phosphite. Protonation reaction of the hydride [OsH(bpy)P₃]⁺ (4) cations with Brønsted acid was studied and led to thermally unstable (above 0 °C) dihydrogen [Os(η²-H₂)(bpy)P₃]²⁺ (4*) derivatives. The presence of the H₂ ligand is supported by variable-temperature NMR spectra and T_1min measurements. Carbonyl [Os(CO)(bpy){P(OEt)₃}₃](BPh₄)₂ (5), nitrile [Os(CH₃CN)(bpy){P(OEt)₃}₃](BPh₄)₂ (6), and hydrazine [Os(bpy)(NH₂NH₂){P(OEt)₃}₃](BPh₄)₂ (7) complexes were prepared by substituting the H₂ ligand in the η²-H₂ (4*) derivatives. Aryldiazene complex [Os(C₆H₅NNH)(bpy){P(OEt)₃}₃](BPh₄)₂ (8) was also obtained by allowing the hydride [OsH(bpy)P₃]BPh₄ to react with phenyldiazonium cation.     

Preparation of imine complexes of ruthenium and osmium stabilised by [MCl(η -p-cymene)(PR3)] fragments

Imine complexes [MCl(η ⁶-p-cymene){η¹-NHC(H)Ar}(PR₃)]BPh₄ (1-3) [M = Ru, Os; PR₃ = PPh(OEt)₂, PPh₂OEt; Ar = Ph, p-tolyl] were prepared by reacting MCl₂(η ⁶-p-cymene)(PR₃) precursors with benzyl azide ArCH₂N₃ in the presence of NaBPh₄. Benzophenone-imine complexes [MCl(η ⁶-p-cymene){η¹-NHCPh₂}(PR₃)]BPh₄ (4-6) [M = Ru, Os; PR₃ = PPh(OEt)₂, PPh₂OEt] were also prepared by allowing MCl₂(η ⁶-p-cymene)(PR₃) to react with Ph₂CNH in the presence of NaBPh₄. The complexes were characterised spectroscopically (IR, ¹H, ¹³C, ³¹P, ¹⁵N NMR) and by X-ray crystal structure determination of [RuCl(η ⁶-p-cymene){η¹-NHC(H)-p-tolyl}{PPh(OEt)₂}]BPh₄ (1b).     

Organometallic ruthenium, rhodium and iridium complexes containing a P-bound thiophene-2-(N-diphenylphosphino)methylamine ligand: Synthesis, molecular structure and catalytic activity

Reaction of Ph₂PNHCH₂-C₄H₃S with [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂, [Ru(η⁶-benzene)(μ-Cl)Cl]₂, [Rh(μ-Cl)(cod)]₂ and [Ir(η⁵-C₅Me₅)(μ-Cl)Cl]₂ yields complexes [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-p-cymene)Cl₂], 1, [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2, [Rh(Ph₂PNHCH₂-C₄H₃S)(cod)Cl], 3 and [Ir(Ph₂PNHCH₂-C₄H₃S)(η⁵-C₅Me₅)Cl₂], 4, respectively. All complexes were isolated from the reaction solution and fully characterized by analytical and spectroscopic methods. The structure of [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2 was also determined by single crystal X-ray diffraction. 1-4 are suitable precursors forming highly active catalyst in the transfer hydrogenation of a variety of simple ketones. Notably, the catalysts obtained by using the ruthenium complexes [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-p-cymene)Cl₂], 1 and [Ru(Ph₂PNHCH₂-C₄H₃S)(η⁶-benzene)Cl₂], 2 are much more active in the transfer hydrogenation converting the carbonyls to the corresponding alcohols in 98-99% yields (TOF ≤ 200 h⁻¹) in comparison to analogous rhodium and iridium complexes.     

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.     

Synthesis of arene ruthenium triazolato complexes by cycloaddition of the corresponding arene ruthenium azido complexes with activated alkynes or with fumaronitrile

The neutral arene ruthenium azido complexes [(η⁶-p-cymene)Ru(LL)(N₃)], [LL = acetylacetonato (acac) (4), benzoylacetonato (bzac) (5) diphenylbenzoyl methane (dbzm) (6)] undergo [3+2] cycloaddition reaction with a series of activated alkynes and fumaronitrile to produce the arene ruthenium triazolato complexes: [(η⁶-p-cymene)Ru(LL){N₃C₂(CO₂R)₂}] [LL = (acac), R = Me (7); LL = (bzac), R = Me (8); LL = (dbzm), R = Me (9); LL = (acac), R = Et (10); LL = (bzac), R = Et (11); LL = (dbzm), R = Et (12) and [(η⁶-p-cymene)Ru(LL)(N₃C₂HCN)]; LL = acac (13), bzac (14); dbzm (15). However, cationic azido complexes, [(η⁶-p-cymene)Ru(dppe)(N₃)]⁺ and [(η⁶-p-cymene)Ru(dppm)(N₃)]⁺ do not undergo such cycloaddition reactions. The complexes were characterized on the basis of microanalyses, FT-IR and NMR spectroscopic data. Crystal structures of representative complexes were determined by single crystal X-ray diffraction.     

Preparation and reactivity with azo-species of hydride and dihydrogen complexes of osmium stabilised by tris(pyrazolyl)borate and phosphite ligands

Mixed-ligand OsCl(Tp)L(PPh₃) complexes 1 [Tp = hydridotris(pyrazolyl)borate; L = P(OMe)₃, P(OEt)₃ and PPh(OEt)₂] were prepared by allowing OsCl(Tp)(PPh₃)₂ to react with an excess of phosphite. Treatment of chlorocomplexes 1 with NaBH₄ in ethanol afforded hydride OsH(Tp)L(PPh₃) derivatives 2. Stable dihydrogen [Os(η²-H₂)(Tp)L(PPh₃)]BPh₄ derivatives 3 were prepared by protonation of hydrides 2 with HBF₄ · Et₂O at −80 °C. The presence of the η²-H₂ ligand is supported by short T_1 min values and J_HD measurements on the partially deuterated derivatives. Treatment of the hydride OsH(Tp)[P(OEt)₃](PPh₃) complex with the aryldiazonium salt [4-CH₃C₆H₄N₂]BF₄ afforded aryldiazene [Os(4-CH₃C₆H₄NNH)(Tp){P(OEt)₃}(PPh₃)]BPh₄ derivative 4. Instead, aryldiazenido [Os(4-CH₃C₆H₄N₂)(Tp)[P(OEt)₃](PPh₃)](BF₄)₂ derivative 5 was obtained by reacting the hydride OsH(Tp)[P(OEt)₃](PPh₃) first with methyltriflate and then with aryldiazonium [4-CH₃C₆H₄N₂]BF₄ salt. Spectroscopic characterisation (IR, ¹⁵N NMR) by the ¹⁵N-labelled derivative strongly supports the presence of a near-linear Os-NN-Ar aryldiazenido group. Imine [Os{η¹-NHC(H)Ar}(Tp){P(OEt)₃}(PPh₃)]BPh₄ complexes 6 and 7 (Ar = C₆H₅, 4-CH₃C₆H₄) were also prepared by allowing the hydride OsH(Tp)[P(OEt)₃](PPh₃) to react first with methyltriflate and then with alkylazides.     

Synthesis and characterisation of new pyrazole-phosphinite ligands and their ruthenium(II) arene complexes

The new potentially bidentate pyrazole-phosphinite ligands [(3,5-dimethyl-1H-pyrazol-1-yl)methyl diphenylphosphinite] (L¹) and [2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl diphenylphosphinite] (L²) were synthesised and characterised. The reaction of L¹ and L² with the dimeric complexes [Ru(η⁶-arene)Cl₂]₂ (arene = p-cymene, benzene) led to the formation of neutral complexes [Ru(η⁶-arene)Cl₂(L)] (L = L¹, L²) where the pyrazole-phosphinite ligand is κ¹-P coordinated to the metal. The subsequent reaction of these complexes with NaBPh₄ or NaBF₄ produced the [Ru(η⁶-p-cymene)Cl(L²)][BPh₄] and [Ru(η⁶-benzene)Cl(L²)][BF₄] compounds which contain the pyrazole-phosphinite ligand κ²-P,N bonded to ruthenium. All the complexes were fully characterised by analytical and spectroscopic methods. The structure of the complex [Ru(η⁶-p-cymene)Cl(L²)][BPh₄] was also determined by a X-ray single crystal diffraction study.     

Half sandwich complexes of Ru(II) and complexes of Pd(II) and Pt(II) with seleno and thio derivatives of pyrrolidine: Synthesis, structure and applications as catalysts for organic reactions

The reactions of PhSe⁻, PhS⁻ and Se²⁻ with N-{2-(chloroethyl)}pyrrolidine result in N-{2-(phenylseleno)ethyl}pyrrolidine (L1), N-{2-(phenylthio)ethyl}pyrrolidine (L2), and bis{2-pyrrolidene-N-yl)ethyl selenide (L3), respectively, which have been explored as ligands. The complexes [PdCl₂(L1/L2)] (1/7), [PtCl₂(L1/L2)] (2/8), [RuCl(η⁶-C₆H₆)(L1/L2)][PF₆] (3/9), [RuCl(η⁶-p-cymene)(L1/L2)][PF₆] (4/10), [RuCl(η⁶-p-cymene)(NH₃)₂][PF₆] (5) and [Ru(η⁶-p-cymene)(L1)(CH₃CN)][PF₆]₂·CH₃CN (6) have been synthesized. The L1-L3 and complexes were found to give characteristic NMR (Proton, Carbon-13 and Se-77). The crystal structures of complexes 1, 3-6, 9 and 10 have been solved. The Pd-Se and Ru-Se bond lengths have been found to be 2.353(2) and 2.480(11)/2.4918(9)/2.4770(5) Å, respectively. The complexes 1 and 7 have been explored for catalytic Heck and Suzuki-Miyaura coupling reactions. The value of TON has been found up to 85 000 with the advantage of catalyst’s stability under ambient conditions. The efficiency of 1 is marginally better than 7. The Ru-complexes 3 and 9 are good for catalytic oxidation of primary and secondary alcohols in CH₂Cl₂ in the presence of N-methylmorpholine-N-oxide (NMO). The TON value varies between 8.0 × 10⁴ and 9.7 × 10⁴ for this oxidation. The 3 is somewhat more efficient catalyst than 9.     

Synthesis,crystal structure and spectroscopic characterization of new neutral and cationic (η-p-cymene)–ruthenium(II) complexes with phosphine–amide ligands

The dimeric starting material [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ reacts with the phosphino-amides o-Ph₂P–C₆H₄CO–NH–R [R = ⁱPr (a), Ph (b), 4-MeC₆H₄ (c), 4-FC₆H₄ (d)] to give the mononuclear compounds 1a–d [RuCl(η⁶-p-cymene)(o-Ph₂P–C₆H₄–CO–NH–R)]Cl. The subsequent reaction of these complexes with KPF₆ produced the cationic species 2a–d [RuCl(η⁶-p-cymene)(o-Ph₂P–C₆H₄–CO–NH–R)][PF₆] in which phosphino-amides also act as rigid P,O-chelating ligands. The molecular structures of 2b–d were determined crystallographically. Amide deprotonation is achieved when complexes 2a–d were made react with 1 M aqueous solution of KOH, affording the corresponding neutral species 3a–d [RuCl(η⁶-p-cymene)(o-Ph₂P–C₆H₄–CO–N–R)] in which a P,N-coordination mode is suggested.     

Thermal decomposition of new chlorido(p-cymene) ruthenium(II) complexes containing N-alkylphenothiazines

The thermal decomposition of [RuCl₂(η⁶-p-cymene)]₂ (1) and its biologically active N-alkylphenothiazine compounds of composition L[RuCl₃(η⁶-p-cymene)] where L = CPH⁺ (2), TFH⁺·HCl (3), and TRH⁺ (4) (chlorpromazine hydrochloride, CP·HCl; trifluoperazine dihydrochloride, TF·2HCl; and thioridazine hydrochloride, TR·HCl, respectively) has been studied. The crystal and molecular structure of compound 3 was determined earlier by single crystal X-ray diffraction analysis. The thermal data were collected by simultaneous TG/DSC measurements. For evolved gas detection, the qualitative reaction of chlorides with AgNO₃ in an acidic solution was applied. The measurements were carried out in the temperature range to 700 °C in nitrogen atmosphere. Compounds of L[RuCl₃(η⁶-p-cymene)] crystallize with water or water/2-propanole. On the basis of thermal data, the trend in the solvent bonding energies was assessed.     

Half-sandwich para-cymene ruthenium(II) naphthylazophenolato complexes: Synthesis,molecular structure,light emission,redox behavior and catalytic oxidation properties

A series of conformationally rigid half-sandwich organoruthenium(II) complexes with the general formula [(η⁶-p-cymene)RuCl(L)] (where L = mono anionic 2-(naphthylazo)phenolato ligands) have been synthesized from the reaction of [{(η⁶-p-cymene)RuCl}₂(μ-Cl)₂] with a set of 2-(naphthylazo)phenolato O,N-donor ligands. All the ruthenium complexes were fully characterized by FT-IR, ¹H NMR, and UV–Vis spectroscopy as well as elemental analysis. In dichloromethane solution all the metal complexes exhibits characteristic metal-to-ligand charge transfer bands (MLCT) and emission bands in the visible region. The molecular structure of one of the complexes [Ru(η⁶-p-cymene)(Cl)(L2)] (2) was determined by X-ray crystallography. Electrochemical data of all the ruthenium complexes show a two metal centered voltammetric responses with respect to Ag/AgCl at scan rate 100 mV s⁻¹. Further, the complex (2) efficiently catalyzes the oxidation of a wide range of alcohols to their corresponding carbonyl compounds in the presence of N-methylmorpholine-N-oxide (NMO) up to 97%.     

Preparation of Hydride‐Ethylene Complexes of Osmium

Ethylene complexes [OsH(η²‐CH₂=CH₂)L₄]Y ( 1 , 2 ) [L = PPh(OEt)₂, P(OEt)₃; Y = OTf, BPh₄] were prepared by reacting the dihydride OsH₂L₄ first with methyl triflate CH₃OTf and then with ethylene (1 atm). Alternatively, the compound [OsH(η²‐CH₂=CH₂){PPh(OEt)₂}₄]OTf was prepared by allowing the dinitrogen derivative [OsH(N₂){PPh(OEt)₂}₄]OTf to react with ethylene. Acrylonitrile CH₂=C(H)CN reacts with OsH(OTf)L₄ [L = P(OEt)₃] to give the complex [OsH{κ¹‐NCC(H)=CH₂}{P(OEt)₃}₄]BPh₄ ( 3 ). The complexes were characterized spectroscopically (IR and ¹H, ¹³C, ³¹P NMR) and by X‐ray crystal structure determination of the [OsH(η²‐CH₂=CH₂){PPh(OEt)₂}₄]BPh₄ derivative.     

Synthesis and structural characterization of ruthenium(II) complexes bearing phosphine-pyrazolyl based tripod ligands

Phosphine-pyrazolyl based tripod ligands ROCH₂C(CH₂Pz)₂(CH₂PPh₂) (R = H, Me, allyl; Pz = pyrazol-1-yl) were efficiently synthesized and characterized. Reactions of these ligands with [Ru(η⁶-p-cymene)Cl₂]₂ afforded complexes of the type [Ru(η⁶-p-cymene)Cl₂](L) (6-8) in which the ligands exhibit κ¹-P-coordination to the metal center. Complex [Ru(η⁶-p-cymene)Cl₂{Ph₂PCH₂C(CH₂OH)(CH₂Pz)₂}] (6) underwent chloride-dissociation in CH₂Cl₂/MeCN to give complex [RuCl(η⁶-p-cymene){κ²(P,N)-Ph₂PCH₂C(CH₂OH)(CH₂Pz)₂}][Cl] (9). Complexes 6-9 demonstrated poor to moderate catalytic activity in the transfer hydrogenation of acetophenone. All these complexes were fully characterized by analytical and spectroscopic methods and their molecular structures were determined by X-ray crystallographic study.     

Influence of arene dissociation and phosphine coordination on the catalytic activity of [RuCl(κ-triphos)(p-cymene)]PF6

The catalytic activity of a ruthenium(II)-p-cymene complex containing a partially coordinated triphosphine ligand, [RuCl(κ²-triphos)(p-cymene)]PF₆1, has been investigated in the hydrogenation of styrene to ethylbenzene. The influence of arene dissociation and coordination of the free phosphine donor group on the catalytic activity have been probed directly and indirectly by comparison to structural analogues. Analogues of 1 containing in a diphosphine ligand, [RuCl(κ²-dppp)(p-cymene)]PF₆2, or a labile arene ligand, [RuCl(κ²-triphos)(η⁶-PhCO₂Et)]PF₆3, show significantly enhanced catalytic activity - demonstrating the importance of ligand coordination/dissociation dynamics in ruthenium(II)-arene compounds during catalysis. These observations are supported by thermolysis reactions of 1 in DMSO. In addition, improved syntheses of 1 and 2 are reported together with the solid-state structures of syn-1, syn-3 and [Ru(η³-C₈H₁₃)(κ³-triphos)]PF₆.     

The synthesis,structure and reactions of the novel cationic bisbut-2-yne complex [W(CO)(NCMe)(S2CNC4H8)(η2-MeC2Me)2][BPh4]

The complex [WI(CO)(S₂CNC₄H₈)(η²-MeC₂Me)₂] reacts with an equimolar amount of Na[BPh₄] in acetonitrile at room temperature to give the cationic bisbut-2-yne complex [W(CO)(NCMe)(S₂CNC₄H₈)(η²-MeC₂Me)₂][BPh₄] (1) by replacement of an iodide ligand by acetonitrile. The crystal structure of 1 has been determined and reveals a pseudo-octahedral geometry with the mid points of the two cis-but-2-yne ligands approximately coplanar with the sulphur atoms of the dithiocarbamate ligand. Carbon monoxide and acetonitrile occupy the axial sites. ¹³C NMR spectroscopy shows the two but-2-yne ligands in 1 donate a total of 6 electrons to the tungsten. Preliminary studies of the chemistry of 1 are also described.     

Chiral arene ruthenium complexes: Part 3. [Ruthenium(η6-arene)(η4-1,5-cyclooctadiene)] complexes with N or O donor functions in the arene side chain

Arene ruthenium(0) complexes with carbonyl side chain functionalities like [Ru(η⁶-C₆H₅COR)(η⁴-COD)] or [Ru(η⁶-o-C₆H₄{R¹}COR)(η⁴-COD)] (COD=1,5-cyclooctadiene; R=H, CH₃; R¹=H, CH₃, OCH₃) are easily accessible by replacing the naphthalene ligand of [Ru(η⁶-naphthalene)(η⁴-COD)] (1) through an arene exchange reaction. These carbonyl species are susceptible to standard organic reactions of the carbonyl function, thus allowing the introduction of dangling side chains bearing highly polar functions like hydroxyl or amino groups. Aldol reaction of [Ru(o-C₆H₄{CH₃}COCH₃)(COD)] (3) with (−)-menthylchloroformate in the presence of LDA (LDA=lithium diisopropylamide) leads to a diastereomeric mixture of [Ru(menthyl-{3-oxo-3-η⁶-o-tolyl}propionate)(COD)] (10). However, treatment of 3 with LDA and o-tolylaldehyde or benzaldehyde affords the unexpected products [Ru(1-η⁶-o-tolyl-3-o-tolylpropan-1-one)(COD)] (11) and [Ru(1-η⁶-o-tolyl-1-phenylpropan-1-one)(COD)] (12). A diastereoselective addition (88% de) of deprotonated menthylacetate to [Ru(o-tolylaldehyde)(COD)] (4) results in the formation of [Ru(menthyl 3-η⁶-o-tolyl-3-hydroxypropionate)(COD)] (13). Racemic planar-chiral aldehyde complexes 2 and 4 react with amines giving the imination products in good yield. In case of reaction between 2 and (R)-N-amino-2-(methoxymethyl)-pyrrolidine (RAMP), diastereomeric [Ru(N-[[η⁶-(2-methylphenyl]methylene]-(R)-2-(methoxymethyl)-1-pyrrolidinamine)(COD)] (17) is formed. The diastereomers (R,R)-17 and (S,R)-17 have been separated by fractional crystallisation. Asymmetric arene ruthenium complexes with a defined planar-chiral configuration are thus accessible. Reduction of [Ru(3-η⁶-phenyl-(R)-methylbutyrate)(COD)] (7) with LiAlH₄ yields the chiral γ-alcohol [Ru(3-η⁶-phenyl-(R)-1-butanol)(COD)] (18). A Wittig olefination converts the aldehyde complex 4 into a mixture of E- and Z-isomeric [Ru(1-η⁶-o-tolyl-2-phenylethylene)(COD)] 21a and 21b, which were separated again by fractional crystallisation.     

Synthesis and reactivity of germyl complexes of manganese and rhenium

Trichlorogermyl complexes M(GeCl₃)(CO)_nP_{5? n} (1–4) [M = Mn, Re; n = 2, 3; P = PPh(OEt)₂ (a), P(OEt)₃ (b)] were prepared by allowing chloro compounds MCl(CO)_nP_{5? n} to react with an excess of GeCl₂?dioxane in 1,2-dichloroethane. Treatment of compounds 1–4 with LiAlH₄ in thf yielded trihydridegermyl derivatives M(GeH₃)(CO)_nP_5?n (5–8), whereas treatment of the same complexes with NaBH₄ in ethanol afforded triethoxygermyl derivatives M[Ge(OEt)₃](CO)_nP_5?n (9–11). Trimethylgermyl compounds M(GeMe₃)(CO)_nP_5?n (12, 13) and the alkynylgermyl derivative Mn[Ge(CCPh)₃](CO)₃[PPh(OEt)₂]₂ (14a) were also prepared by allowing trichlorogermyl compounds 1–4 to react with either MgBrMe or Li⁺CCPh^?, respectively, in thf. Treatment of compound Re(GeCl₃)(CO)₃[PPh(OEt)₂]₂ (4a) with SnCl₂?2H₂O gave the stannyl-germyl derivative Re[GeCl₂(SnCl₃)](CO)₃[PPh(OEt)₂]₂ (15a). The complexes were characterised by spectroscopy and X-ray crystal structure determination of 4a, 5a, and 13a.     

New active ruthenium(II) complexes based N3,N3′-bis(diphenylphosphino)-2,2′-bipyridine-3,3′-diamine and P,P′-diphenylphosphinous acid-P,P′-[2,2′-bipyridine]-3,3′-diyl ester ligands for transfer hydrogenation of aromatic ketones by propan-2-ol

The dimeric starting material [Ru(η⁶-p-cymene)(μ-Cl)Cl]₂ reacts with N3,N3′-bis(diphenylphosphino)-2,2′-bipyridine-3,3′-diamine, 1 and P,P′-diphenylphosphinous acid-P,P′-[2,2′-bipyridine]-3,3′-diyl ester, 2 ligands to afford bridged dinuclear complexes [C₁₀H₆N₂{NHPPh₂-Ru(η⁶-p-cymene)Cl₂}₂], 3 and [C₁₀H₆N₂{OPPh₂-Ru(η⁶-p-cymene)Cl₂}₂], 4 in quantitative yields. These bis(aminophosphine) and bis(phosphinite) based Ru(II) complexes serve as active catalyst precursors for the transfer hydrogenation of acetophenone derivatives in 2-propanol and especially 4 acts as a good catalyst, giving the corresponding alcohols in 99% yield in 20 min (TOF ? 280 h⁻¹).