A SIMPLE ROUTE FOR SYNTHESES OF TRIHALIDE-BRIDGED CARBONYL DIRUTHENIUM(II,III) COMPLEXES: CRYSTAL AND MOLECULAR STRUCTURE OF ttt-[RuIICl2(CO)2(PPh3)2],[(CO)(AsPh3)2RuII(μ-Cl3)RuIIICl2(AsPh3)] AND ([CO)(PPh3)2RuII(μ-Br3)RuIIIBr2(PPh3)], SPECTROSCOPIES,ELECTROCHEMISTRY AND PROPERTIES

Abstract

The triply halide-bridged binuclear complexes [Ru₂Cl₅(CO)(AsPh₃)₃] (AsPh₃ = triphenylarsine), [Ru₂Cl₅(CO)(PPh₃)₂(AsPh₃)] (PPh₃ = triphenylphosphine), [Ru₂Cl₅(CO)(AsPh₃)₂(PPh₃)], [Ru₂ Br₅(CO)(PPh₃)₃], [Ru₂Cl₅(CO)(P{p-tol}₃)₂(PPh₃)] (P{p-tol}₃ = tri-p-tolylphosphine) and [Ru₂ Br₂Cl₃(PPh₃)₂(AsPh₃)] were prepared from the precursor compounds ttt-[RuX₂(CO)₂(P)₂] (X = Cl or Br) and [RuY₃(P')₂S]·S (Y = Cl or Br; P=PPh₃, AsPh₃ or P{p- tol}₃ and P' = AsPh₃ or PPh₃; S=DMA or MeOH, where DMA = N,N'-dimethylacetamide). The molecular structures of the binuclear complexes [Ru₂Cl₅(CO)(AsPh₃)₃] (P2_1/c), [Ru₂Br₅(CO)(PPh₃)₃] (P2_1/c) and ttt-[RuCl₂(CO)₂(PPh₃)₂] (P1) were determined by X-ray diffraction methods. The complexes are always formed by two Ru atoms bridged through three halide anions, two of which are × type (from the Ru^II precursor) and the other is Y type (from the ruthenium^III precursor) confirming our previously suggested mechanism for obtaining this class of complexes. The Ru^II atom is also coordinated to a carbon monoxide molecule and two P ligands from the ttt-starting isomer whereas the Ru^III atom is bonded to two non-bridging Y halides and one P' molecule. The presence of Ru^III was confirmed by EPR data, a technique that was also useful to suggest the symmetry of the complexes. The absence of intervalence charge-transfer transitions (IT) in the near infrared spectrum confirms that the binuclear complexes have localized valence. The IR spectra of the complexes show; (CO) bands close to 1970 cm^?1 and ν(Ru-Cl) or(Ru-Br) bands at about 230–380 cm^?1 corresponding to halides at terminal or bridged positions. Two widely separated redox processes, Ru^II/Ru^II←Ru^II/Ru^III→Ru^III/Ru^III, were observed by cyclic voltammetry and differential pulse voltammetry.     

Synthesen und Kristallstrukturen neuer sulfidoverbrückter Rutheniumclusterverbindungen

Syntheses and Crystal Structures of New Sulfido‐bridged Ruthenium Clusters The reaction of S(SiMe₃)₂ or NaSH with [RuCl₂(PPh₃)₃] or [Ru₃Cl₈(PEt₃)₄] leads to the formation of sulfidobridged ruthenium clusters. In this publication the compounds [Ru₆S₈(PPh₃)₆][PF₆] ( 1 ), [Ru₆S₈(PPh₃)₆][RuCl₄(PPh₃)₂] ( 2 ), [Ru₆S₈(PEt₃)₆] ( 3 ) and [Ru₃S₄Cl₂(PPh₃)₃]₂ ( 4 ) are described. The structures of these compounds were elucidated by single crystal X‐ray structural analyses.     

Neue phosphidoverbrückte Mehrkernkomplexe des Ag und Zn. Die Kristallstrukturen von [Ag3(PPh2)3(PnBu2tBu)3], [Ag4(PPh2)4(PR3)4] (PR3 = PMenPr2, PnPr3), [Ag4(PPh2)4(PEt3)4]n, [Zn4(PPh2)4Cl4(PRR2)2] (PRR′2 = PMenPr2, PnBu3, PEt2Ph), [Zn4(PhPSiMe3)4Cl4(C4H8O)2] und [Zn4(PtBu2)4Cl4]

New Phosphido-bridged Multinuclear Complexes of Ag and Zn. The Crystal Structures of [Ag₃(PPh₂)₃(PⁿBu₂^tBu)₃], [Ag₄(PPh₂)₄(PR₃)₄] (PR₃ = PMeⁿPr₂, PⁿPr₃), [Ag₄(PPh₂)₄(PEt₃)₄]_n, [Zn₄(PPh₂)₄Cl₄(PRR′₂)₂] (PRR′₂ = PMeⁿPr₂, PⁿBu₃, PEt₂Ph), [Zn₄(PhPSiMe₃)₄Cl₄(C₄H₈O)₂] and [Zn₄(P^tBu₂)₄Cl₄] AgCl reacts with Ph₂PSiMe₃ in the presence of tertiary Phosphines (PⁿBu₂^tBu, PMeⁿPr₂, PⁿPr₃ and PEt₃) to form the multinuclear complexes [Ag₃(PPh₂)₃(PⁿBu₂^tBu)₃] 1 , [Ag₄(PPh₂)₄(PR₃)₄] (PR₃ = PMeⁿPr₂ 2 , PⁿPr₃ 3 ) and [Ag₄(PPh₂)₄(PEt₃)₄]_n 4 . In analogy to that ZnCl₂ reacts with Ph₂PSiMe₃ and PRR′₂ to form the multinuclear complexes [Zn₄(PPh₂)₄Cl₄(PRR′₂)₂] (PRR′₂ = PMeⁿPr₂ 5 , PⁿBu₃ 6 , PEt₂Ph 7 ). Further it was possible to obtain the compounds [Zn₄(PhPSiMe₃)₄Cl₄(C₄H₈O)₂] 8 and [Zn₄(P^tBu₂)₄Cl₄] 9 by reaction of ZnCl₂ with PhP(SiMe₃)₂ and ^tBu₂PSiMe₃, respectively. The structures were characterized by X-ray single crystal structure analysis. Crystallographic data see “Inhaltsübersicht”.     

Synthesis and characterisation of new triple halide-bridged mixed valence binuclear complexes of ruthenium and osmium

Several isomers of the type [M₂Cl₅L₄] (M = Ru, L = AsPh₃, As(p-tol)₃, As(p-PhCl)₃, PEt₂Ph, PMe₂Ph; L₂ = Ph₂As(CH₂)₂AsPh₂; M = Os, L = PPh₃, AsPh₃) have been synthesised by various routes and characterised by magnetic, ESR and electrochemical measurements, and for [(PEt₂Ph)Cl₂RuCl₃Ru(PEt₂Ph)₃] by X-ray structural analysis.     

Chemistry of ruthenium in N2P2X2 (X = Cl, Br) coordination sphere: Synthesis, characterization and reactivities

Reaction of 2-(phenylazo)pyridine (pap) with [Ru(PPh₃)₃X₂] (X = Cl, Br) in dichloromethane solution affords [Ru(PPh₃)₂(pap)X₂]. These diamagnetic complexes exhibit a weakdd transition and two intense MLCT transitions in the visible region. In dichloromethane solution they display a one-electron reduction of pap near − 0.90 V vs SCE and a reversible ruthenium(II)-ruthenium(III) oxidation near 0.70 V vs SCE. The [Ru^III(PPh₃)₂(pap)Cl₂]⁺ complex cation, generated by coulometric oxidation of [Ru(PPh₃)₂(pap)Cl₂], shows two intense LMCT transitions in the visible region. It oxidizes N,N-dimethylaniline and [Ru^II(bpy)₂Cl₂] (bpy = 2,2′-bipyridine) to produce N,N,N′,N′-tetramethylbenzidine and [Ru^III(bpy)₂Cl₂]⁺ respectively. Reaction of [Ru(PPh₃)₂(pap)X₂] with Ag⁺ in ethanol produces [Ru(PPh₃)₂(pap)(EtOH)₂]²⁺ which upon further reaction with L (L = pap, bpy, acetylacetonate ion(acac⁻) and oxalate ion (ox²⁻)) gives complexes of type [Ru(PPh₃)₂(pap)(L)]ⁿ⁺ (n = 0, 1, 2). All these diamagnetic complexes show a weakdd transition and several intense MLCT transitions in the visible region. The ruthenium(II)-ruthenium(III) oxidation potential decreases in the order (of L): pap > bpy > acac⁻ > ox²⁻. Reductions of the coordinated pap and bpy are also observed.     

Redox Reactions Of Polyhydride Complexes of Rhenium: electrochemistry and Reactions With Alkyl Isocyanides

The dark red octahydride complex of dirhenium, Re₂H₈(PPh₃)₄, undergoes a reversible one-electron oxidation to the blue mono-cation [Re₂H₈(PPh₃)₄]⁺ (E_{$\text{buit;1}\text{2}$} ?0.24 V vs. SCE by cyclic voltammetry). The X-band ESR spectrum of a dichloromethane glass (?160°C) containing the monocation is in accord with the HOMO being a delocalized metal-based orbital. Treatment of the heptahydrides ReH₇(PR₃)₂ (PR₃ = PPh₃ or PEtPh₂) with C₆H₁₁NC or Me₃CNC in the presence of KPF₆ leads to the elimination of hydrogen and the formation of [Re(CNR)₄(PR₃)₂]PF₆. Electrochemical oxidation of ReH₅(PPh₃)₂L (L = PPh₃, PEt₂Ph, pyridine, piperidine or cyclohexylamine) activities these molecules to attack by RNC to afford rhenium(I) species     

On the structure of tetracoordinated organocobalt complexes of the type [CoR2L2]

A series of square-planar organocobalt complexes of the type [CoR₂L₂] (R = 2,3,4,6-C₆,HCl₄ and 2,3,6-C₆H₂Cl₃, L = PEtPh₂, PEt₂Ph, and PEt₃; R = 2,3,5,6-C₆HCl₄, and 2,6-C₆H₃Cl₂, L = PEt₂Ph, PEt₃, and $\text{1}\text{2}$dpe) have been prepared in which the electronegativities of the ligand R vary progressively. The reaction of o-C₆H₄ClMgBr with [CoCl₂L₂] (L = PEtPh₂ PEt₂Ph, γ-pic or $\text{1}\text{2}$bipy) did not give air stable compounds at room temperature, but the solutions obtained at ?78°C appear to contain square-planar species for L = PEtPh₂, PEt₂Ph, and γ-pic, and tetrahedral for L₂ = bipy. The tendency towards square-planar or tetrahedral structures for the compounds [CoR₂L₂] depends on the following factors in order of importance: (i) when the neutral ligand is a phosphine a square-planar structure is adopted; (ii) when L is an aromatic amine, bulky ortho substituents on R favour a square-planar structure; and (iii) a tetrahedral geometry is favoured by bidentate amine ligands. The electronegativity of the organic group R seems to be less important.     

Substitution reactions of metal-metal quadruply-bonded tetrachlorotetrakis(phosphine)dimolybdenum compounds

Summary The substitutions of dimolybdenum compounds of the type [Mo₂Cl₄L₄] (where L=PEt₃, PEt₂Ph or PEtPh₂), together with the preparation and characterization of the metal-metal quadruply bonded [Mo₂Cl₄(triphos)₂] obtained from K₄Mo₂Cl₈] are described.     

Synthesen und Kristallstrukturen neuer selenidoverbrückter Ruthenium-Clusterverbindungen

Syntheses and Crystal Structures of New Selenido-bridged Ruthenium Clusters The reaction of Se(SiMe₃)₂ with [RuCl₂(PPh₃)₃], or a mixture of [RuCl₂(PPh₃)₃] and alkylphosphines leads to the formation of selenido-bridged ruthenium clusters. In this publication the compounds [Ru₆Se₈(PPh₃)₆] ( 1 ), [Ru₆Se₈(PEt₃)₆] ( 2 ) und[Ru₆Se₈(PⁿPr₃)₆] ( 3 ) are described.The compounds 1-3 contain Ru₆¹⁶⁺ cluster cores with Ru²⁺ and Ru³⁺ centers. The structures of these compounds were elucidated by single crystal X-ray structural analyses.     

Synthese und Kristallstrukturen von [Cu4(As4Ph4)2(PRR′2)4], [Cu14(AsPh)6(SCN)2(PEt2Ph)8], [Cu14(AsPh)6Cl2(PRR′2)8], [Cu12(AsPh)6(PPh3)6], [Cu10(AsPh)4Cl2(PMe3)8], [Cu12(AsSiMe3)6(PRR′2)6] und [Cu8(AsSiMe3)4(PtBu3)4] (R,R′ = organische Gruppen)

Syntheses and Crystal Structures of [Cu₄(As₄Ph₄)₂(PRR′₂)₄], [Cu₁₄(AsPh)₆(SCN)₂(PEt₂Ph)₈], [Cu₁₄(AsPh)₆Cl₂(PRR′₂)₈], [Cu₁₂(AsPh)₆(PPh₃)₆], [Cu₁₀(AsPh)₄Cl₂(PMe₃)₈], [Cu₁₂(AsSiMe₃)₆(PRR′₂)₆], and [Cu₈(AsSiMe₃)₄(P^tBu₃)₄] (R, R′ = Organic Groups) Through the reaction of CuSCN with AsPh(SiMe₃)₂ in the presence of tertiary phosphines the compounds [Cu₄(As₄Ph₄)₂(PRR′₂)₄] ( 1 – 3 ) ( 1 : R = R′ = ⁿPr, 2 : R = R′ = Et; 3 : R = Me, R′ = ⁿPr) and [Cu₁₄(AsPh)₆(SCN)₂(PEt₂Ph)₈] ( 4 ) can be synthesised. Using CuCl instead of CuSCN results to the cluster complexes [Cu₁₄(AsPh)₆Cl₂(PRR′₂)₈] ( 5–6 ) ( 5 : R = R′ = Et; 6 : R = Me, R′ = ⁿPr), [Cu₁₂(AsPh)₆(PPh₃)₆] ( 7 ) and [Cu₁₀(AsPh)₄Cl₂(PMe₃)₈] ( 8 ). Through reactions of CuOAc with As(SiMe₃)₃ in the presence of tertiary phosphines the compounds [Cu₁₂(AsSiMe₃)₆(PRR′₂)₆] ( 9 – 11 ) ( 9 : R = R′ = Et; 10 : R = Ph, R′ = Et; 11 : R = Et, R′ = Ph) and [Cu₈(AsSiMe₃)₄(P^tBu₃)₄] ( 12 ) can be obtained. In each case the products were characterised by single‐crystal‐X‐ray‐structure‐analyses. As the main structure element 1 – 3 each have two As₄Ph₄^2–‐chains as ligands. In contrast 4 – 12 contain discrete AsR^2–ligands.     

Derivate des borols: IX. (η5-borol)metall-komplexe von ruthenium,osmium und rhodium

Dehydrogenating complexation of borolenes with carbonyls (Ru₃(CO)₁₂, Os₃(CO)₁₂), Wilkinson's catalyst (RhCl(PPh₃)₃) and related compounds (RuCl₂(PPh₃)₃, RuHCl(PPh₃)₃, OSCl₂(PPh₃)₃), and (η⁶-arene)ruthenium complexes (Ru(η-C₆H₆)(η⁴-C₆H₈), [Ru(η-C₆H₆)Cl₂]₂, [Ru(η-C₆-Me₆)Cl₂]₂) leads to the (η⁵-borole)metal complexes of Ru, Os, and Rh. Inter alia, the preparation of the complexes Ru(CO)₃(η⁵-C₄H₄BF) (R = Ph, OMe, Me), Os(CO)₃L (L = η⁵-C₄H₄BPh), MHClL(PPh₃)₂ (M = Ru, Os), RhClL(PPh₃)₂, and RuL(η-C₆R₆) (R = H, Me) is described. The structures of RuHClL(PPh₃)₂ and RhClL(PPh₃)₂ have been determined by X-ray diffraction analysis.     

Decomposition reactions of square-planar bis-aryl-cobalt(II) complexes

The organocobalt complexes [CoR₂L₂], with (a) L = PEtPh₂ and R = 2,3,5,6- C₆HCl₄, 2,4,6-C₆H₂Cl₃ and 2,6-C₆H₃Cl₂; and (b) R = 2,4,6-C₆H₂Cl₃ and L = PEt₃, PEt₂Ph, $\text{1}\text{2}$ dpe, 3,5-lut and $\text{1}\text{2}$ bipy, have been obtained by reaction of RMgX with [CoCl₂L₂] or by ligand exchange from [CoR₂(PEtPh₂)₂]. The decompositions in benzene and carbon tetrachloride, and under oxidative conditions have been studied. In benzene solutions, the stability decreases with decrease in the number of chlorine atoms in R. A mixture of RH and RR is obtained in a ratio which depends on the nature of L, the configuration of the complex, and the presence of oxidants. The thermal decomposition takes place through a tricoordinate intermediate “CoR₂L”, when L = phosphine, or directly from [CoR₂L₂] when L = amine. The oxidatively induced decomposition takes place through a cobalt(III) intermediate, which gives RR when L = phosphine or RX (X = H, Br) when L = amine. The process is intramolecular in all cases.     

Tetracarbonyl group 6 complexes containing secondary and tertiary phosphines

The mixed ligand tetracarbonyl derivatives, cis-M(CO)₄(PPh₂H)(PPh₃) (M  Cr, Mo, W) and cis-W(CO)₄(PPh₂H)(L) (L  PEt₃, PEt₂Ph, PEtPh₂) have been prepared from the reaction of M(CO)₅PPh₂H with L in THF in the presence of potassium t-butoxide. These reactions are accompanied in most instances by the formation of [W(CO)₅PPh₂]⁻, [(OC)₅M(μ-PPh₂)M(CO)₅]⁻, [(OC)₅M(μ-PPh₂)-M(CO)₄(PPh₂H)]⁻, [(OC)₄M(μ-PPh₂)₂M(CO)₄]²⁻, (OC)₄M(μ-PPh₂)₂M(CO)₄, and cis-M(CO)₄(PPh₂H)₂.     

Reactions of cationic rhodium(I) carbonyl compounds with nucleophiles to form alkoxo,carboalkoxy and carboxylato complexes. Part II

Summary The rhodium(I) carbonyl compounds [Rh(CO)L₂2] [BF₄]. 1/2CH₂Cl_nn2 (L = PPh₂ or AsPh₃) react with the nucleophiles OMe⁻, RCOO⁻ (R = Me, Et) under nitrogen to form [Rh(OR)(CO)L₂] (1)–(2) and [Rh(OOCR)(CO)L₂] (7)–(₁₀), respectively. Addition of [Rh(CO)₂(PPh₃)₂]-[BF ₄] to OMe⁻ under nitrogen produces [Rh(COOMe)-(CO) (PPh₃)₂]-MeOH (3), whilst reactions of [Rh(CO)-(PPh₃)₂] [BF₄]·1/2CH₂Cl₂ and [Rh(CO)₂(PPh₃)₂] [BF₄] with OR_- (R = Me, Et or n-Pr) in the presence of CO produce [Rh(COOR)(CO)₂(PPh₃)₂] (4)–(6). The products have been characterised by i.r., ¹H, ³¹P, ¹³Cn.m.r. spectroscopy and elemental analysis.     

Zweikernige Palladium(II)‐, Platin(II)‐ und Iridium(III)‐Komplexe von Bis[imidazol‐4‐yl]alkanen

Dinuclear Palladium(II), Platinum(II), and Iridium(III) Complexes of Bis[imidazol‐4‐yl]alkanes The reaction of bis(1,1′‐triphenylmethyl‐imidazol‐4‐yl) alkanes ((CH₂)_n bridged imidazoles L(CH₂)_nL, n = 3–6) with chloro bridged complexes [R₃P(Cl)M(μ‐Cl)M(Cl)PR₃] (M = Pd, Pt; R = Et, Pr, Bu) affords the dinuclear compounds [Cl₂(R₃P)M–L(CH₂)_nL–M(PR₃)Cl₂] 1 – 17 . The structures of [Cl₂(Et₃P)Pd–L(CH₂)₃L–Pd(PEt₃)Cl₂] ( 1 ), [Cl₂(Bu₃P)Pd–L(CH₂)₄L–Pd(PBu₃)Cl₂] ( 10 ), [Cl₂(Et₃P)Pd–L(CH₂)₅L–Pd(PEt₃)Cl₂] ( 3 ), [Cl₂(Et₃P)Pt–L(CH₂)₃L–Pt(PEt₃)Cl₂] ( 13 ) with trans Cl–M–Cl groups were determined by X‐ray diffraction. Similarly the complexes [Cl₂(Cp*)Ir–L(CH₂)_nL–Ir(Cp*)Cl₂] (n = 4–6) are obtained from [Cp*(Cl)Ir(μ‐Cl)₂Ir(Cl)Cp*] and the methylene bridged bis(imidazoles).     

Oxorhenium(V) Complexes with 1,3,4‐Triphenyl‐1,2,4‐triazol‐5‐ylidene

Reactions of the oxorhenium(V) complexes [ReOX₃(PPh₃)₂] (X = Cl, Br) with the N‐heterocyclic carbene (NHC) 1,3,4‐triphenyl‐1,2,4‐triazol‐5‐ylidene (L^Ph) under mild conditions and in the presence of MeOH or water give [ReOX₂(Y)(PPh₃)(L^Ph)] complexes (X = Cl, Br; Y = OMe, OH). Attempted reactions of the carbene precursor 5‐methoxy‐1,3,4‐triphenyl‐4,5‐dihydro‐1H‐1,2,4‐triazole ( 1 ) with [ReOCl₃(PPh₃)₂] or [NBu₄][ReOCl₄] in boiling xylene resulted in protonation of the intermediately formed carbene and decomposition products such as [HL^Ph][ReOCl₄(OPPh₃)], [HL^Ph][ReOCl₄(OH₂)] or [HL^Ph][ReO₄] were isolated. The neutral [ReOX₂(Y)(PPh₃)(HL^Ph)] complexes are purple, airstable solids. The bulky NHC ligands coordinate monodentate and in cis‐position to PPh₃. The relatively long Re–C bond lengths of approximate 2.1Å indicate metal‐carbon single bonds.     

Ruthenium complexes containing group 5b donor ligands : Part VII. Rearrangement reactions of some ruthenium (II) complexes containing triphenylphosphine,tri-p-tolylphosphine or ethyldiphenylphosphine ligands.

As for [RuCl₂(PPh₃₃], carbonylation of [RuCl₂(PR₃)₃] [PR₃ = P(p-tolyl)₃, PEtPh₂) in N,N ¹-dimethylformamide (dmf) gives [Ru(CO)Cl₂ (dmf) (PR₃)₂] (II). For PR₃ = PEtPh₂, rearrangement of (II) in various solvents gives inseparable mixtures (³¹P evidence) but for PR₃ = P(p-tolyl)₃ [Ru₂(CO)₂Cl₄-{P(p-tolyl)₃}₃]is obtained. Reaction of [Ru(CO)Cl₂ (dmf) - {P(p-tolyl)₃}₂] with [RuCI₂{(P(p-tolyl)₃}₃] (1:1 mol ratio) gives [Ru₂ (CO) Cl₄ {P (p-tolyl)₃}₄] whereas reaction of [Ru (CO) Cl₂ (dmf) - (PPh₃₂] with (Rul₂ {P (p-tolyl)₃}₃] gives [Ru₂(CO)Cl₄ (PPh₃)₂] - {P(p-tolyl)₃}₂] - Reaction of [RuCl₂ {P(p-tolyl)₃}₃] with CS₂ gives the related [Ru₂Cl₄(CS) {P(p-tolyl)₃}₄] and [{RuCl₂(CS)}P(p-tolyl)₃{₂}₂] whereas [RuCl₂(PEtPh₂)₃] and CS₂ produce [RuCl₂(S₂CPEtPh₂) (PEtPh₂)₂]CS₂ and [Ru₂Cl₄(CS)₂(PEtph₂)₃].     

Ruthenium(II) and ruthenium(III) complexes derived from O,O-donor ligands

The new [Ru¹¹(PPh₃)₂L₂] complexes [L=monoanion of tropolone, benzoylacetone, or 3-hydroxy-2-pyridinone (hypy)], [RuH(PPh₃)₃L′][HL′=maltol, dibenzoylmethane or 1,2-dimethyl-3-hydroxy-4-pyridinone (Hdmhypy)] and [Ru^IIIX₂(EPh₃)₂L″] complexes (X=Cl, Br; E=As or P; L″=hypy, dmhypy) have been prepared, and characterized by spectroscopic techniques. Their redox behaviour was studied by cyclic voltammetry. Most of the complexes were found to be effective catalysts for the oxidation ofp-methoxybenzyl alcohol to the corresponding aldehyde in the presence ofN-methylmorpholine-N-oxide as co-oxidant.     

Electrochemical behaviour of [Ru(L)(CO)2Cl2] [Ru(L)(CO)Cl3][Me4N] and [Ru(L)(CO)2(CH3CN)2][CF3SO3]2 complexes (L = 2,2′- bipyridine or 4,4′-isopropoxycarbonyl-2,2′-bipyridine)

The clectrochemical behaviour of the complexes [Ru^II(L)(CO)₂Cl₂], [Ru^II(L)(CO)Cl₃][Me₄N] and [Ru^II(L)(CO)₂(CH₃CN)₂][CF₃SO₃]₂ (L = 2,2′-bipyridine or 4,4′-isopropoxycarbonyl-2,2′-bipyridine) has been investigated in CH₃CN. The oxidation of [Ru(L)(CO)₂Cl₂] produces new complexes [Ru^III(L)(CO)(CH₃CN)₂Cl]²⁺ as a consequence of the instability of the electrogenerated transient Ru^III species [Ru^III(L)(CO)₂Cl₂]⁺. In contrast, the oxidation of [Ru^II(L)(CO)Cl₃][Me₄N] produces the stable [Ru^III(L)(CO)Cl₃] complex. In contrast [Ru^II(L)(CO)₂(CH₃CN)₂][CF₃SO₃]₂ is not oxidized in the range up to the most positive potentials achievable. The reduction of [Ru^II(L)(CO)₂Cl₂] and [Ru^II(L)(CO)₂(CH₃CN)₂][CF₃SO₃]₂ results in the formation of identical dark blue strongly adherent electroactive films. These films exhibit the characteristics of a metal-metal bond dimer structure. No films are obtained on reduction of [Ru^II(L)(CO)Cl₃][Me₄N]. The effect of the substitution of the bipyridine ligand by electron-withdrawing carboxy ester groups on the electrochemical behaviour of all these complexes has also been investigated.     

Reactions of zero-valent platinum complexes with some diacetylenes

The complexes[Pt(C₂H₄)L₂] (L = PPh₃ or PMePh₂) react with 1,4-diphenyl-buta-1,3-diyne to give, successively, mono- and di-platinum compounds [Pt-(PhC₄Ph)L₂] and [Pt₂(PhC₄Ph)L₄]. Hexa-2,4-diyne and [Pt(C₂H₄)(PPh₃)₂] react similarly. In the di-platinum compounds both acetylenic linkages are η²-bonded to platinum atoms, as also occurs in the complex [Pt₂{HC₂(CH₂)₂C₂H}(PPh₃)₄] obtained from hexa-1,5-diyne. Reaction of [Pt₃(CN-t-Bu)₆ with 1,4-diphenylbuta-1,3-diyne and hexa-2,4-diyne affords di-platinum complexes, shown by spectroscopic studies to have structures containing diplatinacyclobutene rings.