Reactions of half-sandwich rhodium(III) and iridium(III) compounds with pyridinethiolate ligands: Mono-, di-, and tri-nuclear complexes

Neutral trinuclear metallomacrocycles, [Cp^*RhCl(μ-4-PyS)]₃ (3) and [Cp^*IrCl(μ-4-PyS)]₃ (4) [Cp^* = pentamethylcyclopentadienyl, 4-PyS = 4-pyridinethiolate], have been synthesized by self-assembly reactions of [Cp^*RhCl₂]₂ (1) and [Cp^*IrCl₂]₂ (2) with lithium 4-pyridinethiolate, respectively. In situ reaction of complex 3 with three equivalent of lithium 4-pyridinethiolate resulted in [Cp^*Rh(μ-4-PyS)(4-PyS)]₃ (5) containing both skeleton and pendent 4-PyS groups. Chelating coordination of 2-pyridinethiolate broke down the triangular skeleton to give mononuclear metalloligands Cp^*Rh(2-PyS)(4-PyS) (6) and Cp^*Ir(2-PyS)(4-PyS) (7) [2-PyS = 2-pyridinethiolate], which could also be synthesized from Cp^*RhCl(2-PyS) (10) and Cp^*IrCl(2-PyS) (11) with lithium 4-pyridinethiolate. The coordination reactions of 6 with complexes 1 and 2 gave dinuclear complexes [Cp^*Rh(2-PyS)(μ-4-PyS)][Cp^*RhCl₂] (8) and [Cp^*Rh(2-PyS)(μ-4-PyS)][Cp^*IrCl₂] (9), respectively. Molecular structures of 3, 4, 6 and 11 were determined by X-ray crystallographic analysis. All the complexes have been well characterized by elemental analysis, NMR and IR spectra.     

Synthesis of neutral tri- and tetranuclear organometallic clusters of group VIII transition metals

A number of earlier unknown tri- and tetranuclear organometallic clusters of group VIII transition metals was synthesized by the addition of coordinatively unsaturated species to a single metal-metal bond. A number of novel heteronuclear clusters, CpCp ₂ ^′ Rhm₂(μ−CO)₃(μ₃−CO), (Cp′=Cp, Cp^*; M₂=Ru₂, Fe₂; RuFe); Cp₂Cp ₂ ^* Rh₂M₂(μ₃−CO)₃ (M = Ru, Fe); , Cp₃Cp^*Rh₃M(μ₃−CO)₂(μ₃−d) (M = Ru, Fe); Cp₂Cp ₂ ^*> Rh₂Co₂(μ₃−CO)₂,etc., was obtained. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 579–586, March, 1997.     

Stacking reactions of the borole complex Cp*Rh(η5-C4H4BPh) with the dicationic fragments [Cp*M]2+ (M = Rh or Ir)

The reaction of the (borole)rhodium iodide complex [(η-C₄H₄BPh)RhI]₄ with Cp^*Li afforded the sandwich compound Cp^*Rh(η-C₄H₄BPh) (4). The reactions of compound 4 with the solvated complexes [Cp^*M(MeNO₂)₃]²⁺(BF ₄ ⁻ )₂ gave triple-decker cationic complexes with the central borole ligand [Cp^*Rh(η-η⁵:η⁵-C₄H₄BPh)MCp^*]²⁺(BF ₄ ⁻ )₂ (M = Rh (5) or Ir (7)). The structure of complex 4 was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1525–1527, September, 2006.     

Triazamethylenemethane complexes of zirconium and tantalum

Addition of [Li₂(THF)₄][C(NPh)₃] (2) to a THF solution of Cp^*ZrCl₃ (Cp^*=C₅Me₅) yields, after recrystallization in Et₂O, the zwitterionic species Cp^*[C(NPh)₃]ZrCl₂Li(Et₂O)(THF) (3). Treating 3 with excess methylaluminoxane (MAO) affords a homogeneous Ziegler–Natta catalyst for ethylene polymerization. Addition of LiNPh₂ to 3 allows for Cl substitution to give the new product Cp^*[C(NPh)₃]Zr(NPh₂)ClLi(THF)₂ (4). A single crystal diffraction study of 4 reveals that the [C(NPh)₃] ligand is η²-bound. The group 5 complex Cp^*[C(NPh)₃]TaMe₂ (5) was prepared by addition of 2 to Cp^*TaMe₂Cl(OSO₃CF₃). The X-ray diffraction structure of 5 shows that the [C(NPh)₃] ligand is η²-bound to tantalum and that, when compared to 4, there is less electron delocalization across the inner core of [C(NPh)₃].     

Oxidation of Alcohols by [Cp*Rh(ppy)(OH)]+

Summary.  Rh(III) polypyridine complexes ([Cp ^*Rh(ppy)(H₂O)]²⁺; ppy = 2,2′-bipyridine, 2,2′-bipyridine-4,4′-dicarboxylate, o-phenanthroline, tetrahydro-4,4′-dialkyl-bis-oxazole) oxidize in organic or aqueous alkaline solution primary and secondary alcohols to aldehydes or ketones and are thereby reduced to the Rh(I) complexes Cp ^*Rh(ppy). The Rh(III) form can be regenerated byoxidants like pyruvate or oxygen, making the reaction quasi-catalytic. The reaction follows anautocatalytic pathway; hydrogen transfer from the α-CH₂ group of an alcoholate complex [Cp ^*Rh(ppy)(OR)]⁺ to Cp ^*Rh(I)(ppy) is suggested to yield the Rh(II) intermediate Cp ^*Rh(ppy)H as the key and rate determining step. The knowledge of Rh(III)/Rh(I) redox potentials allows to estimate the thermodynamic driving force of the reaction which is not more than about 300 mV.     

UV photolysis of protonated ruthenium and osmium decamethylmetallocenes as a new method for synthesis of the metallonium cations

Decamethylmetallocenes Cp^* ₂M (M=Ru, Os) in the presence, of acids (CF₃CO₂H, CF₃SO₃H) give thepprotonation products [Cp^* ₂MH]⁺An⁻. Broad-band UV photolysis of their solutions results in the formation of the salts of onium cations . A preparative procedure for the synthesis of these salts has been developed. Hydrolysis of the salts gives the carbinol Cp^*MC₅Me₄CH₂OH. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 587–591. March, 1999.     

Zur Bildung von Vinylverbindungen des Lanthans und Lutetiums

On Preparation of Vinyl Compounds of Lanthanum and Lutetium At reaction of permethyllanthanocene chloride with vinyl lithium coupling of vinyl groups takes place with formation of the butadiene complex [Li(dme)₃][Cp₂*La(C₄H₆)] ( 1 ). The corresponding lutetium compound yields the expected vinyl complex Cp₂*Lu(CH?CH₂) · LiCl · dme ( 4 ) with low stability. Furthermore, the more stable alkenyl compounds Cp₂*LaCPh?CMe₂ · 2 thf ( 2 ) and Cp₂*LuCPh?CMe₂ · MgCl₂ · dme ( 3 ) could be obtained. The new complexes were characterized by their ¹H and ¹³C-n.m.r. spectra.     

Molecular versus Silica-Supported Iridium Water Oxidation Catalysts

A stringent comparison between two pairs of molecular/immobilized water oxidation catalysts ([Cp^*Ir(Me-pica)Cl], 1 , versus 1_SiO₂ , Me-pica=κ²-N-methyl-picolinamide; [Cp^*Ir(pysa)NO₃], 2 , versus 2_SiO₂ , pysa=κ²-pyridine-2-sulfonamide]) reveals distinctive catalytic trends. While the molecular compound 1 exhibits a substantial higher activity than the analogous immobilized system 1_SiO₂ , under all the experimental conditions explored, the contrary is found with 2 that is far less active than its immobilized counterpart 2_SiO₂ . This is explained by the unique tendency of 2 to form dimeric complexes [Cp^*Ir-(κ²-μ₂-Hpysa)(κ²-μ₂-pysa)IrCp^*], 2 a , in phosphate buffered solution at pH 7, and [Cp^*Ir-(κ²-μ₂-Hpysa)₂IrCp^*], 2 b , in water. 2 a and 2 b have been completely characterized in solution by multinuclear and multidimensional NMR spectroscopy. They have been also isolated as single crystals and their structure in solid state determined by X-Ray diffractometry. 2 a and 2 b appear to be off-cycle species, whose formation is detrimental for water oxidation activity, as indicated by the observation of a long induction period when 2 a is used as catalytic precursor. In addition, TOF versus ΔE (E−E⁰=−RT/nF ln([IO₄⁻]/[IO₃⁻]) trends for the first two runs do not overlap for catalyst 2 and TOF_max is remarkably higher in the second run upon the addition of fresh NaIO₄. In the immobilized system 2_SiO₂ the detrimental associative processes are likely inhibited leading to an activity higher than that of 2 .     

Density functional theory study of the interaction of CP2*ZrCH 3+ (Cp* = C5H5, C5Me5, and C13H9) with ethylene molecule

Density functional theory was used to study gas-phase reactions between the Cp₂*ZrMe⁺ cations, where Cp* = C₅H₅ (1), Me₅Cp = C₅Me₅ (2), and Flu = C₁₃H₉ (3), and the ethylene molecule, Cp₂*ZrMe⁺ + C₂H₄ → Cp₂*ZrPr⁺ → Cp₂*ZrAllyl⁺ + H₂. The reactivity of the Cp₂*ZrMe⁺ cations with respect to the ethylene molecule decreased in the series 1 > 3 ≈ 2. Substitution in the Cp ring decreased the reactivity of the Cp₂*ZrMe⁺ cations toward ethylene, in agreement with the experimental data on the comparative reactivities of complexes 1 and 3. The two main energy barriers along the reaction path (the formation of the C-C bond leading to the primary product Cp₂*ZrPr⁺ and hydride shift leading to the secondary product Cp₂*Zr(H₂)Allyl⁺) vary in opposite directions in the series of the compounds studied. For Flu (3), these barriers are close to each other, and for the other compounds, the formation of the C-C bond requires the overcoming of a higher energy barrier. A comparison of the results obtained with the data on the activity of zirconocene catalysts in real catalytic systems for the polymerization of ethylene led us to conclude that the properties of the catalytic center changed drastically in the passage from the model reaction in the gas phase to real catalytic systems.     

Synthesis of a linear-type pentanuclear (RhIII-WVI-CuI-WVI-RhIII) sulfide cluster predicted by fast atom bombardment mass spectrometry

The positive ion FAB mass spectrum of a linear trinuclear sulfide cluster, [Cp^*RhP(OEt)₃(-WS₄CuCl] (1; Cp^* = ⁵-C₅Me₅), shows many ions heavier than the molecular ion. One of the envelopes corresponds to a pentanuclear cationic cluster of [{Cp^*RhP(OEt)₃(WS₄)}₂Cu]⁺. It has been synthesized by a reaction between [Cp^*RhP(OEt)₃WS₄] and Cu⁺ in a 2:1 molar ratio as the PF₆ salt [{Cp^*RhP(OEt)₃(-WS₄)}₂Cu][PF₆] (2 · PF₆), which is characterized by a single-crystal X-ray diffraction, EXAFS, and IR measurements.This paper is dedicated to Professor Jiaxi Lu on the occassion of this 80th birthday and in recognition of his pioneering contribution to this field.     

Spectral studies of the mechanism of oxidation of Cp2Fe by ozone

The mechanism of oxidation of Cp₂Fe by ozone in CCl₄ was studied by chemiluminescence (CL), photoluminescence, IR, UV, and NMR spectral techniques, Ozone attacks Cp₂Fe at the Fe−C and C=C bonds to form peroxides CpOOFe, CpFeOOH, triplet (3 nπ^*) ketones (CL emitters), and organic acids. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 794–797, April, 1999.     

Synthesis and molecular structure of [1, 3-(Me3Si)2C5H3]2Lu(μ-Cl)2

Cp^* ₂Lu(-Cl)₂ (1) was isolated following the reaction of Cp^*Na (Cp^* = 1, 3-(Me₃Si)₂C₅H₃) with LuCl₃ in THF and subsequent treatment with toluene at 80°C. An X-ray structural investigation of1 was performed (MoK radiation, 2933 reflections,R = 0.020). The crystals are triclinic,a = 10.744(3) Å,b=11.821(2) Å, c=12.966(3) Å, a=71.54(1)°, =85.32(2)°, =74.83(1)°,Z = 2, space groupP-1. Two Lu atoms withdistorted tetrahedral coordination are linked by two chloride bridges with a mean Lu-Cl distance equal to 2.62 Å.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 568–570, March, 1993.     

Synthesis,thermochemistry, and structural characterization of organoruthenium arene and triene complexes

The synthetic, thermodynamic and structural investigations of organoruthenium complexes of the form Cp^*Ru(triene)OTf (Cp^*=n⁵-(CH₃)₅C₅; triene=anisole 1, indole 2, cycloheptatriene 3, OTf=OSO₂CF₃) are presented in this contribution. A direct entryway into the thermochemistry of these complexes is made possible by the rapid and quantitative arene/triene substitution for the three acetonitrile ligands in Cp^*Ru(CH₃CN)₃OTf. The solution calorimetric study establishes the following order of stability: cycloheptatriene < anisole < indole. This study helps clarify the enthalpic and entropic components to the thermodynamic driving forces behind the formation of ruthenium arene/triene complexes. The solid-state structures of these three complexes(1–3) were determined by X-ray single-crystal studies. Thermodynamic factors affecting the Ru-triene bond energy are compared with structural results for these three ruthenium complexes.     

Cp*MCpMoFe(CO)7(μ3-S), Cp*MoCpMFe(CO)7(μ3-S) (M = W,Mo) and Cp*WCp*MoFe(CO)7(μ3-S). Crystal structure of CpMoCp*WFe(CO)7(μ3-S)

CpMoFeCo(CO)₇(₃-S) reacts with Cp^*M(CO)₃Cl or CpM(CO)₃Cl (M=W, Mo) to gave the mixed-metal clusters Cp^*WCpMoFe(CO)₇(₃-S) (1), Cp^*MoCpMoFe(CO)₇(₃-S) (2), CpWCp^*MoFe(CO)₇(₃-S) (3), CpMoCp^*MoFe(CO)₇(₃-S) (4) and Cp^*WCp^*MoFe(CO)₇(₃-S) (5). The title clusters have been characterized by i.r., ¹H/¹³C-n.m.r. spectroscopy and their compositions have been confirmed by elemental analyses. The X-ray crystal structure analysis shows the two independent enantiomeric molecules of clusters (1) in one crystal structure unit.     

Analysis of the Solid-State Rearrangementof Hydrido-Alkynyl Ruthenium Complexesto their Vinylidene Tautomers

Summary.  The solid-state tautomerization of the hydrido-alkynyl derivatives [Cp ^*RuH(C&*CR)-(dippe)][BPh₄] (Cp^* = C₅Me₅; R = SiMe₃, Ph, H; dippe = 1,2-bis-(diisopropylphosphino)-ethane) to their vinylidene isomers [Cp ^*Ru*C*CHR(dippe)][BPh₄] was studied by IR spectroscopy. Characteristic isothermic αvs. t curves for each individual rearrangement process were recorded. Their shape, and hence the isomerization mechanism, depends strongly on the nature of the substituent R. The kinetic analysis of the above curves using the Avrami-Erofeev provided some mechanistic information about the isomerization process in the solid. Received July 7, 2000. Accepted August 29, 2000     

半夹芯16电子碳硼烷化合物Cp*CoS2C2B10H10与含磷化合物的反应性

半夹芯16电子碳硼烷化合物Cp~*CoS_2C_2B_(10)H_(10)分别与二苯基甲基膦、苯基二甲基膦和三甲基膦反应得到碳硼烷衍生物(Cp~*CoS_2C_2B_(10)H_(10))(PPh_2Me)(1)、(Cp~*CoS_2C_2B_(10)H_(10))(PPhMe_2)(2)和(Cp~*CoS_2C_2B_(10)H_(10))(PMe_3)(3)。分别用红外、核磁、元素分析、质谱和单晶X射线衍射等表征方法对1、2和3进行了结构表征。紫外可见吸收光谱结果显示化合物1、2和3在乙腈溶剂中均有2个吸收峰,第一个吸收峰分别位于321、316和321 nm;第二个吸收峰分别位于425、399和407 nm。荧光光谱结果显示化合物1、2和3在乙腈中的最大发射波长位于406 nm左右。     

Uranium-sulfilimine chemistry. The preparation of Cp2*UCl2(HNSPh2) and its hydrolysis with HNSPh2 · H2O

The reaction of Cp₂*UCl₂ with HNSPh₂ produces Cp₂*UCl₂(HNSPh₂), which is the first structurally characterized complex of a sulfilimine. The hydrolysis of Cp₂*UCl₂(HNSPh₂) with HNSPh₂ · H₂O yields a tetrauranium cluster whose heavy atom structure has been determined by x-ray diffraction and which is formulated as a U^IV/U^V complex: [Cp*(Cl)(HNSPh₂)U(μ₃-O)(μ₂-O)₂U(Cl)(HNSPh₂)₂]₂.     

E4 Transfer (E=P,As) to Ni Complexes

The use of [Cp′′₂Zr(η^1:1-E₄)] (E=P ( 1 a ), As ( 1 b ), Cp′′=1,3-di-tert-butyl-cyclopentadienyl) as phosphorus or arsenic source, respectively, gives access to novel stable polypnictogen transition metal complexes at ambient temperatures. The reaction of 1 a/1 b with [Cp^RNiBr]₂ (Cp^R=Cp^Bn (1,2,3,4,5-pentabenzyl-cyclopentadienyl), Cp′′′ (1,2,4-tri-tert-butyl-cyclopentadienyl)) was studied, to yield novel complexes depending on steric effects and stoichiometric ratios. Besides the transfer of the complete E_n unit, a degradation as well as aggregation can be observed. Thus, the prismane derivatives [(Cp′′′Ni)₂(μ,η^3:3-E₄)] ( 2 a (E=P); 2 b (E=As)) or the arsenic containing cubane [(Cp′′′Ni)₃(μ₃-As)(As₄)] ( 5 ) are formed. Furthermore, the bromine bridged cubanes of the type [(Cp^RNi)₃{Ni(μ-Br)}(μ₃-E)₄]₂ (Cp^R=Cp′′′: 6 a (E=P), 6 b (E=As), Cp^R=Cp^Bn: 8 a (E=P), 8 b (E=As)) can be isolated. Here, a stepwise transfer of E_n units is possible, with a cyclo-E₄²⁻ ligand being introduced and unprecedented triple-decker compounds of the type [{(Cp^RNi)₃Ni(μ₃-E)₄}₂(μ,η^4:4-E′₄)] (Cp^R=Cp^Bn, Cp′′′; E/E′=P, As) are obtained.     

Preparation,Crystal Structure and Spectroscopic Studies of Mixed valence Compound [(Cp4i Rh)2 (μ‐Cl)3] [Rh(CO)2Cl2]

[(Cp⁴ⁱ Rh)₂(μ‐Cl)₃] [Rh(CO)₂Cl₂] (Cp⁴ⁱ = tetraisopropyl‐cyclopenta‐dienyl) has been prepared and its crystal is in the space group of Pbar with a= 0.9417 (8), b = 1.4806 (3), c = 1.5062 (2) nm, a = 92.980(10), β = 97.42(3), γ = 93.98 (3)°, V = 2.0735(18) nm³ and Z = 2. The crystal structure consists of a cation of [(η⁵‐Cp⁴ⁱ) Rh (III)(μ‐Cl)₃ Rh (III) (η⁵‐Cp⁴ⁱ)]⁺ and an anion of [Rh (I) (CO)₂ Cl₂]. The two bulky tetraisopropylcyclopentadienyl ligands are in the ecliptic conformation with angle of 10.19° between two cyclopentadienyl ring planes.     

New divalent samarocenes for butadiene polymerisation: influence of the steric effect and the electron density on the catalytic activity

Two new divalent samarocenes, Cp^*′₂Sm(THF) (1) and (Cp^Ph3)₂Sm(THF) (2) (Cp^*′=C₅Me₄ⁿPr, Cp^Ph3=H₂C₅Ph₃-1,2,4), were synthesized and characterized by ¹H NMR and elemental analysis. The activity of 1 and 2 as butadiene polymerisation catalysts was studied, in the presence of MAO and MMAO, and compared to this of Cp^*₂Sm(THF)₂ (3) and (Cp⁴ⁱ)₂Sm (4) (Cp^*=C₅Me₅, Cp⁴ⁱ=C₅HⁱPr₄), in the same conditions. The 1/MAO system presents the highest activity. The less active 2/MAO system leads to a high cis-1,4 regular structure up to 97%. The MMAO cocatalyst is found very sensitive to the steric hindrance of the samarocenes: the activity decreases from 1/MAO to 1/MMAO, and no activity is observed in the case of complexes 2 and 4, associated to MMAO. Complexes 1 and 2 can be both oxidized with AlMe₃ to give the corresponding Sm/Al bimetallics and , respectively.