Novel Hydrogen Transfer Reactions to the Ligated 1,2,4-Triphosphole in [Ru(η4-C8H12){η-P3C2But 2CH(SiMe3)2}]

INTRODUCTION

As discussed in a recent preliminary publication¹, the complex [Ru(η⁴-C₈H₁₂){η-P₃C₂Bu^t ₂CH(SiMe₃)₂}] (1) (C₈H₁₂ = cycloocta-l,5-diene) was prepared by the reaction of [Ru(η⁶-C₁₀H₈)(η⁴-C₈H₁₂)] (2) (C₁₀H₈ = naphthalene) with the 1,2,4-triphosphole P₃C₂Bu^t ₂CH(SiMe₃)₂ (3) (Fig. 1), illustrating the aromatic behaviour of (3).     

π-Olefin—iridium -komplexe : III. Über (η4-cyclodien)(η5-cyclodienyl)iridium-verbindungen,einen neuartigen hydridoiridium-komplex und das (η4-cyclooctadien)(η6-cyclooctatrien)iridium-kation

The complexes [Ir(COD)(η⁵-C₇H₉)] and [Ir(COD)(η⁵-C₈H₁₁)] are obtained by the isoprophyl Grignard synthesis of [Ir(COD)Cl]₂ (COD = η⁴-1,5-cyclooctadiene) in the presence of cycloheptatriene, and cyclooctatriene, respectively. The later reaction yields [IrH(COD)(δ⁴-1,3,6-C₈H₁₀)] as a by-product which, in contrast to other [IrH(η⁴-cyclodiene)₂] complexes, does not show H-addition-elimination equilibria. Reduction of [Ir(1,3-C₇H₁₀)₂Cl] with C₂H₅OH/Na₂CO₃ yields [Ir(η⁴-1,3-C₇H₁₀)](η⁵-C₇H₉)] which was characterized by X-ray analysis. [Ir(COD)Cl]₂ reacts with Na₂C₈H₈, and after hydrolysis unstable [Ir(COD)(η⁵-C₈H₉)] is formed which by protonation with HPF₆ is converted into the [Ir(COD)(η⁶-1,3,5-C₈H₁₀)]⁺ cation. All these compounds are fluxional in solution.     

Nickelocene chemistry : II. New methylidyne trinickel cluster compounds

The new methylidene trinickel cluster complexes, [RCNi₃(η⁵-C₅H₅₃] (R  CMe₃ or SiMe₃) and [Me₃SiCNi₃(η⁵-C₅H₅)2(η⁵-C₅H₄CH₂SiMe₃)] have been isolated in low yield from reactions between nickelocene and the corresponding alkyllithium reagents, RCH₂Li. The compounds [RCNi₃(η⁵-C₅H₅)₃] (R  Ph, CMe₃ or SiMe₃) have also been obtained by treatment of the σ-alkylnickel complexes [(η⁵-C₅H₅)Ni(CH₂R)(PPh₃)] with n-BuLi in the presence of an excess of nickelocene, but under similar conditions [(η⁵-C₅H₅)Ni(CH₂C_1OH₇-2)-(PPh₃)] (where C_1OH₇-2  2-naphthyl) failed to give [2-C_1OH₇CNi₃(η⁵-C₅H₅)₃]. The attempted synthesis of [(η⁵-C₅H₅)Ni(CH₂CCH)(PPh₃)] from [(η⁵-C₅H₅)-NiBr(PPh₃)] and CHCCH₂MgBr gave only [(η⁵-C₅H₅)Ni(CCMe)(PPh₃)] by an unusual rearrangement reaction.     

New η-allyl η-cyclopentadienylcobalt cations

[Co(R-η-C₃H₄)(η-C₅H₅)I] is a good precursor for the preparation of some new cationic complexes as the iodide can easily be replaced; thus addition of PEt₃ to the iodo-complex (R  H) gives [Co(η-C₃H₅)(η-C₅H₅)(PEt₃)]⁺. The reactions of [Co(R-η-C₃H₄)(η-C₅H₅))I] (R  H or 2-Me) with AgBF₄ give solutions containing the coordinatively unsaturated species [Co(R-η-C₃H₄)(η-C₅H₅)⁺. The presence of traces of water leads to the formation of [Co(R-ηC₃H₄)-(η-C₅H₅)(H₂O)]⁺. The addition of monodentate ligands L  PEt₃ PPh₃, AsPh₃, SbPh₃, CNCH₃ and bidentate ligands LL  Ph₂PCH₂CH₂PPh₂(dppe) and o-C₆H₄(AsMe₂)₂(diars), gives, respectively mononuclear [Co(2-Me-ηC₃H₄)-(η-C₅H₅)L]⁺ and binuclear ligand-bridged [(2-Me-ηC₃H₄)(η-C₅H₅)CoLLCo(2-Me-ηC₃H₄)(η-C₅H₅))]²⁺ complexes. Crystals of [Co(2-Me-ηC₃H₄)(η-C₅H₅)-(H₂O)]⁺[BF₄]^- are monoclinic, space group P2₁/c, with a 7.858(3), b 10.262(4), c 15.078(4) Å, β 98.36(1)°. The molecular structure contains the cobalt atom bonded to planar 2-Me-allyl and cyclopentadienyl substituents, which are almost parallel with the H₂O molecule in a staggered conformation with respect to the 2-Me group.     

Metal-Assisted Opening of Intact P4 Tetrahedra

The reactivity of ruthenium and manganese complexes bearing intact white phosphorus in the coordination sphere was investigated towards the low-valent transition-metal species [Cp′′′Co] (Cp′′′=η⁵-C₅H₂-1,2,4-tBu₃) and [L⁰M] (L⁰=CH[CHN(2,6-Me₂C₆H₃)]₂; M=Fe, Co). Remarkably, and irrespective of the metal species, the reaction proceeds by the selective cleavage of two P–P edges and the formation of a square-planar cyclo-P₄ ligand. The reaction products [{CpRu(PPh₃)₂}{CoCp′′′}(μ,η^1:4-P₄)][CF₃SO₃] ( 5 ), [{Cp^BIGMn(CO)₂}₂{CoCp′′′}(μ,η^1:1:4-P₄)] ( 6 ) and [{Cp^BIGMn(CO)₂}₂{ML⁰}(μ,η^1:1:4-P₄)] (Cp^BIG=C₅(C₆H₄nBu)₅; L⁰=CH[CHN(2,6-Me₂C₆H₃)]₂; M=Fe ( 7 a ), Co ( 7 b )), respectively, were fully characterized by single-crystal X-ray diffraction and spectroscopic methods. The electronic structure of the cyclo-P₄ ligand in the complexes 5 – 7 is best described as a π-delocalized P₄²⁻ system, which is further stabilized by two and three metal moieties, respectively. DFT calculations envisaged a potential intermediate in the reaction to form 5 , in which a quasi-butterfly-shaped P₄ moiety bridges the two metals and behaves as an η³-coordinated ligand towards the cobalt center.     

Dithiocarbamate complexes of cyclopentadienylcobalt(III), [Co(η-C5H5)(L)(S2CNR2)] (L = ligand)

The reactions of [Co(η-C₅H₅)(L)I₂] with Na[S₂CNR₂] (R = alkyl or phenyl) give [Co(η-C₅H₅)(I)(S₂CNR₂)] (I) when L = CO and [Co(η-C₅H₅)(L)(S₂CNR₂)]I (II) when L is a tertiary phosphine, phosphite or stibine, or organo-isocyanide ligand. In similar reactions [Co(η-C₅H₅)(CO)(C₃F₇)I] gives [Co(η-C₅H₅)(C₃F₇)(S₂CNMe₂)] and [Mn(η-MeC₅H₄)(CO)₂(NO)]PF₆ forms [Mn(η-MeC₅H₄)(NO)(S₂CNR₂)]. The iodide ligands in I may be displaced by L, to give II, or by other ligands such as [CN]^?, [NCS]^?, H₂O or pyridine whilst SnCl₂ converts it to SnCl₂I. The iodide counter-anion in II may be replaced by others to give [BPh₄]^?, [Co(CO)₄]^? or [NO₃]^? salts. However [CN]^? acts differently and displaces (PhO)₃P from [Co(η-C₅H₅){P(OPh)₃}(S₂CNMe)]I to give [Co(η-C₅H₅)(CN)(S₂CNMe₂)] which may be alkylated reversibly by MeI and irreversibly by MeSO₃F to [Co(η-C₅H₅)(CNMe)(S₂CNMe₂)]⁺ salts. Conductivity measurements suggest that solutions of I in donor solvents are partially ionized with the formation of [Co(η-C₅H₅)(solvent)(S₂CNR₂)]⁺ I^? species. The IR and ¹H NMR spectra of the various complexes are reported. They are consistent with pseudo-octahedral “pianostool” molecular structures in which the bidentate dithiocarbamate ligands are coordinated to the metal atoms through both sulphur atoms.     

Photochemical reactions of allyl and crotyl halides with cyclopentadienyl-chromium, -molybdenum and -tungsten complexes

[MoCl(CO)₃(η⁵-C₅H₅)] on photolysis with allyl or crotyl halides C₅H₄RX gives Mo^IV complexes [MoX₂(CO)(η³-C₃H₄R)(η⁵-C₅H₅)] (R = H, X = Cl, Br, I; R = Me, X = Cl, Br). [WCl(CO)₃(η⁵-C₅H₅)] under similar conditions gives trihalides [WX₃(CO)₂(η⁵-C₅H₅)] (X = Cl, Br) on reaction with C₃H₅Cl and C₃H₅Br while [WCl(CO)₃(η⁵-C₅H₄SiMe₃)] and [CrI(CO)₃(η⁵-C₅H₅)] react with allyl chloride to give [WCl₃(CO)₂(η⁵-C₅H₄SiMe₃)] and [CrCl₂(η⁵-C₅H₅)] respectively.     

C2-Bridged sandwich and half-sandwich entities with Ti(IV) and Cr(0) centers

The intense purple colored bi- and trimetallic complexes {Ti}(CH₂SiMe₃)[CC(η⁶-C₆H₅)Cr(CO)₃] (3) ({Ti}=(η⁵-C₅H₅)₂Ti) and [Ti][CC(η⁶-C₆H₅)Cr(CO)₃]₂ (5) {[Ti]=(η⁵-C₅H₄SiMe₃)₂Ti}, in which next to a Ti(IV) center a Cr(0) atom is present, are accessible by the reaction of Li[CC(η⁶-C₆H₅)Cr(CO)₃] (2) with {Ti}(CH₂SiMe₃)Cl (1) or [Ti]Cl₂ (4) in a 1:1 or 2:1 molar ratio. The chemical and electrochemical properties of 3, 5, {Ti}(CH₂SiMe₃)(CCFc) [Fc=(η⁵-C₅H₅)Fe(η⁵-C₅H₄)] and [Ti][(CC)_nMc][(CC)_mM′c] [n, m=1, 2; n=m; n≠m; Mc=(η⁵-C₅H₅)Fe(η⁵-C₅H₄); M′c=(η⁵-C₅H₅)Ru(η⁵-C₅H₄); Mc=M′c; Mc≠M′c] will be comparatively discussed.     

Synthesis of homo- and heterodinuclear metal complexes with dimethylsilylene bridged unsymmetrical bis(cyclopentadienyl) ligand

The reaction of the dilithium salt Li₂[Me₂Si(C₅H₄)(C₅Me₄)] (2) of Me₂Si(C₅H₅)(C₅HMe₄) (1) with [MCl(C₈H₁₂)]₂ (M=Rh, Ir) and [RhCl(CO)₂]₂ afforded homodinuclear metal complexes [{Me₂Si(η⁵-C₅H₄)(η⁵-C₅Me₄)}{M(C₈H₁₂)}₂] (M=Rh: 3; M=Ir: 4) and [{Me₂Si(η⁵-C₅H₄)(η⁵-C₅Me₄)}Rh₂(CO)₂(μ-CO)] (5), respectively. The reaction of 2 with RhCl(CO)(PPh₃)₂ afforded a mononuclear metal complex [{Me₂Si(C₅HMe₄)(η⁵-C₅H₄)}Rh(CO)PPh₃] (6) leaving the C₅HMe₄ moiety intact. Taking advantage of the difference in reactivity of the two cyclopentadienyl moieties of 2, heterodinuclear complexes were prepared in one pot. Thus, the reaction of 2 with RhCl(CO)(PPh₃)₂, followed by the treatment with [MCl(C₈H₁₂)]₂ (M=Rh, Ir) afforded a homodinuclear metal complex [Rh(CO)PPh₃{(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}Rh(C₈H₁₂)] (7) consisting of two rhodium centers with different ligands and a heterodinuclear metal complex [Rh(CO)(PPh₃){(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}Ir(C₈H₁₂)] (8). The successive treatment of 2 with [IrCl(C₈H₁₂)]₂ and [RhCl(C₈H₁₂)]₂ provided heterodinuclear metal complex [Ir(C₈H₁₂){(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}Rh(C₈H₁₂)] (9). The reaction of 2 with CoCl(PPh₃)₃ and then with PhCCPh gave a mononuclear cobaltacyclopentadiene complex [{Me₂Si(C₅Me₄H)(η⁵-C₅H₄)}Co(CPhCPhCPhCPh)(PPh₃)] (10). However, successive treatment of 2 with CoCl(PPh₃)₃, PhCCPh and [MCl(C₈H₁₂)]₂ in this order afforded heterodinuclear metal complexes [M(C₈H₁₂){(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}Co(η⁴-C₄Ph₄)] (M=Rh: 11; M=Ir: 12) in which the cobalt center was connected to the C₅Me₄ moiety. Although the heating of 10 afforded a tetraphenylcyclobutadiene complex [{Me₂Si(C₅Me₄H)(η⁵-C₅H₄)}Co(η⁴-C₄Ph₄)] (13), in which the cobalt center was connected to the C₅H₄ moiety, simple heating of the reaction mixture of 2, CoCl(PPh₃)₃ and PhCCPh resulted in the formation of a tetraphenylcyclobutadiene complex [{Me₂Si(C₅H₅)(η⁵-C₅Me₄)}Co(η⁴-C₄Ph₄)] (14), in which the cobalt center was connected to the C₅Me₄ moiety. The mechanism of the cobalt transfer was suggested based on the electrophilicity of the formal trivalent cobaltacyclopentadiene moiety. In the presence of 1,5-cyclooctadiene, the reaction of 2 with CoCl(PPh₃)₃ provided a mononuclear cobalt cyclooctadiene complex [{Me₂Si(C₅Me₄H)(η⁵-C₅H₄)}Co(C₈H₁₂)] (15). The reaction of 15 with n-BuLi followed by the treatment with [MCl(C₈H₁₂)]₂ (M=Rh, Ir) afforded the heterodinuclear metal complexes of [Co(C₈H₁₂){(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}M(C₈H₁₂)] (M=Rh: 16; M=Ir: 17). Treatment of 6 with Fe₂(CO)₉ at room temperature afforded a heterodinuclear metal complex [{Me₂Si(C₅HMe₄)(η⁵-C₅H₄)}{Rh(PPh₃)(μ-CO)₂Fe(CO)₃}] (18) in which the C₅HMe₄ moiety was kept intact. Treatment of dinuclear metal complex 5 with Fe₂(CO)₉ afforded a heterotrinuclear metal complex [{(η⁵-C₅H₄)SiMe₂(η⁵-C₅Me₄)}{Rh(CO)Rh(μ-CO)₂Fe(CO)₃}] (19) having a triangular metal framework. The crystal and molecular structures of 3, 11, 12, 18 and 19 have been determined by single-crystal X-ray diffraction analysis.     

Synthese,Struktur und Eigenschaften von [nacnac]MX3‐Verbindungen (M = Ge,Sn; X = Cl,Br, I)

Synthesis, Structure, and Properties of [nacnac]MX₃ Compounds (M = Ge, Sn; X = Cl, Br, I) Reactions of [nacnac]Li [(2,6‐ⁱPr₂C₆H₃)NC(Me)C(H)C(Me)N(2,6‐ⁱPr₂C₆H₃)]Li ( 1 ) with SnX₄ (X = Cl, Br, I) and GeCl₄ in Et₂O resulted in metallacyclic compounds with different structural moieties. In the [nacnac]SnX₃ compounds (X = Cl 2 , Br 3 , I 4 ) the tin atom is five coordinated and part of a six‐membered ring. The Sn–N‐bond length of 3 is 2.163(4) Å and 2.176(5) Å of 4 . The five coordinated germanium of the [nacnac]GeCl₃ compound 5 shows in addition to the three chlorine atoms further bonds to a carbon and to a nitrogen atom. In contrast to the known compounds with the [nacnac] ligand the afore mentioned reaction creates a carbon–metal‐bond (1.971(3) Å) forming a four‐membered ring. The Ge–N bond length (2.419(2) Å) indicates the formation of a weakly coordinating bond.     

Synthesis of Cationic 2,4-Dimethylpenta-2,4-dienylruthenium Complexes. Crystal Structure of Carbonyl(η4-cyclohexa-1,3-diene)-(η5-2,4-dimethylpenta-2,4-dienyl)ruthenium Tetrafluoroborate

The complex [Ru(η⁵-C₇H₁₁)₂H]BF₄ (C₇H₁₁ = 2,4-dimethylpenta-2,4-dienyl) is highly reactive towards two- and six-electron ligands. e.g. giving with CO complex [RuCO(η⁴-C₇H₁₂)(η⁵-C₇H₁₁)]BF₄. The 2,4-dimethylpenta-1,3-diene ligand (C₇H₁₂) of the latter complex is readily displaced giving, e.g. with excess cyclohexa-1,3-diene (C₆H₈) complex [RuCO(η⁴-C₆H₈)(η⁵-C₇H₁₁)]BF₄. These reactions provide a convenient entry into monopentadienylruthenium chemistry.     

Interfragment transmission of electronic effects of π-acceptor ligands in heterometallic triad complexes with trans-[Ru(Py)4(CN)2] as a central unit

The complex trans-[RuPy₄(CN)₂] cleaves chloride bridges in the binuclear rhodium(i) and palladium(ii) complexes [Rh(CO)₂Cl]₂, [Rh(η⁴-C₈H₁₂)Cl]₂, [(η⁴-C₈H₁₂)Rh(μ-Cl)₂Rh(CO)₂], [Pd(η³-C₃H₅)Cl]₂, and [(η₃-C₃H₅)Pd(μ-Cl)₂Rh(CO)₂] to form heterometallic triad complexes [(CO)₂ClRh(NC)RuPy₄(CN)RhCl(CO)₂] (1), [(η⁴-C₈H₁₂)ClRh(NC)RuPy₄(CN)RhCl-(η⁴-C₈H₁₂)] (2), [(CO)₂ClRh(NC)RuPy₄(CN)RhCl(η⁴-C₈H₁₂)] (3), [(η³-C₃H₅)ClPd(NC)-Ru(Py)₄(CN)PdCl(η³-C₃H₅)] (4), and [(CO)₂ClRh(NC)Ru(Py)₄(CN)PdCl(η₃-C₃H₅)] (5), respectively. In solutions, complex 3 coexists with equilibrium amounts of compounds 1 and 2; complex 5 is in the equilibrium with compounds 4 and 1. In both cases, the ratio of concentrations is close to binomial. Complexes 2 and 5 treated with [Rh(CO)₂Cl]₂ are converted into 1 with the simultaneous formation of [Rh(η⁴-C₈H₁₂)Cl]₂ and [Pd(η³-C₃H₅)Cl]₂, respectively. The δ_H and δ_C values for the ligands η⁴-C₈H₁₂, η³-C₃H₅, and CO are sensitive to the nature of the remote triad unit. The ligand effects are shown to be transmitted along the chain L′-M′-(NC)-Ru-(CN)-M″-L″.     

Five- and six-membered palladacycles derived from [(η5-C5H5)Fe{(η5-C5H4)-CH=N-(C6H4-2-C6H5)}]

The reaction of the novel ferrocenyl Schiff base: [(η⁵-C₅H₅)Fe{(η⁵-C₅H₄)-CH=N-(C₆H₄-2-C₆H₅)}] (1) with Na₂[PdCl₄] and Na(CH₃COO)·3H₂O in a 1:1:1 molar ratio in methanol is reported. In this reaction two different di-μ-chloro-bridged cyclopalladated complexes: [Pd{[(η⁵-C₅H₃)-CH=N-(C₆H₄-2-C₆H₅)]Fe(η⁵-C₅H₅)}(μ-Cl)]₂ (2a) and [Pd{[(C₆H₄-2-C₆H₄)-N=CH-(η⁵-C₅H₄)]Fe(η⁵-C₅H₅)}(μ-Cl)]₂ (2b) can be formed depending on the experimental conditions. Compounds 2a and 2b, which differ in the nature of the metallated carbon atom (C_{sp²,ferrocene} or C_{sp²,biphenyl}, respectively), undergo cleavage of the ‘Pd(μ-Cl)₂Pd’ bridges in the presence of thallium (I) acetylacetonate, deuterated pyridine or triphenylphosphine giving the monomeric derivatives: [Pd(C^∧N)(acac)] (3a, 3b) and [Pd(C^∧N)Cl(L)] {with L=py- d₅(4a, 4b), PPh₃(5a, 5b)}. The reactions of 2 with 1,2-bis(diphenylphosphino)ethane (dppe) reveal that the two isomers (2a and 2b) exhibit different reactivity versus dppe. These results have been interpreted on the basis of steric effects.     

Homo- and hetero-binuclear ansa-metallocenes of the group 4 transition metals as homogeneous co-catalysts for the polymerisation of ethene and propene

The compounds [M{(CH₂)₄C(η-C₅H₄)₂}(η-C₅H₅)Cl] (M=Zr^*, Hf), [M{(CH₂)₄C(η-C₅H₄)₂}(η-C₅H₅)Me] (M=Zr, Hf), [(η-C₅H₅)MCl₂{(CH₂)₄C(η-C₅H₄)₂}MCl₂(η-C₅H₅)] (M=Zr, Hf), [(η-C₅H₅)ZrCl₂{(CH₂)₄C(η-C₅H₄)(η-C₉H₆)}ZrCl₂(η-C₅H₅)], [(η-C₅H₅)MMe₂{(CH₂)₄C(η-C₅H₄)₂}MMe₂(η-C₅H₅)] (M=Zr, Hf), [(η-C₅H₅)ZrCl₂{(CH₂)₄C(η-C₅H₄)₂}HfCl₂(η-C₅H₅)], [(η-C₅H₅)MCl₂{(CH₂)₄C(η-C₅H₄)₂}Rh(η-C₈H₁₂)] (M=Zr^*, Hf), [(η-C₅H₅)ZrCl₂{(CH₂)₄C(η-C₅H₄)₂}TiCl₃], [(η-C₅H₅)ZrMe₂{(CH₂)₄C(η-C₅H₄)₂}HfMe₂(η-C₅H₅)], [(η-C₅H₅)MMe₂{(CH₂)₄C(η-C₅H₄)₂}Rh(η-C₈H₁₂)] (M=Zr^*, Hf) have been prepared and characterised. ^* indicates the crystal structure has been determined. Their catalytic properties for ethene and propene polymerisation have been explored.     

Metal fragment exchange from a molybdaborane to a tungstaborane

Reaction of the molybdaborane arachno-2-[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)B₄H₇] (I) with the electron-rich molecule [W(PMe₃)₃H₆] at 60 °C for 12 h in toluene gives the novel tungstaborane nido-2-W(PMe₃)₃H₂B₄H₇[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)H₂] (II) in 60% yield. The reaction is almost quantitative when followed by NMR. This is a rare example of metal fragment exchange within a metallaborane cage. The molybdenum atom is retained in the molecule via a σ-bond between the substituted cyclopentadienyl ring and a basal boron atom in the metallaborane cluster.     

Preparation and characterization of Cp-functionalized cycloheptatrienyl–cyclopentadienyl titanium sandwich complexes (troticenes)

Cp-functionalized monotroticenes [(η⁷-C₇H₇)Ti(η⁵-C₅H₄E)] (2, E = Ph₂SiCl; 3, E = tBu₂SnCl; 12, E = I) and bitroticenes [(η⁷-C₇H₇)Ti(η⁵-C₅H₄)]₂E′ (5, E′ = PPh; 6, E′ = BN(SiMe₃)₂; 7, E′ = Cp₂Ti) were prepared by salt elimination metathesis between the monolithiated troticene [(η⁷-C₇H₇)Ti(η⁵-C₅H₄Li)]·pmdta (1b) (pmdta = N,N′,N′,N″,N″-pentamethyldiethylene-triamine) and the appropriate electrophile. The troticenyl-substituted zirconocene monochloride [(η⁷-C₇H₇)Ti(η⁵-C₅H₄ZrClCp*₂)] (Cp* = η⁵-C₅Me₅) (8) and hafnocene ethoxide [(η⁷-C₇H₇)Ti{η⁵-C₅H₄Hf(OEt)Cp₂}] (Cp = η⁵-C₅H₅) (11), and the heterobimetallic μ-oxo complexes [(η⁷-C₇H₇)Ti(η⁵-C₅H₄MCp₂)]₂O (9, M = Zr; 10, M = Hf) were obtained instead of the expected zircona- and hafna[1]troticenophanes by reaction of the dilithiated troticene [(η⁷-C₇H₆Li)Ti(η⁵-C₅H₄Li)]·pmdta (1a) with [Cp₂MCl₂] (M = Zr, Hf) or [Cp*₂ZrCl₂] in stoichiometric amounts. These compounds were characterized by single crystal X-ray diffraction analyses and, in the case of 2, 3, 5–7, 9, 10 and 12, also by elemental analyses and ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. Exposure of the troticenyl organotin chloride 3 to moisture resulted in its partial hydrolysis and formation of the organostannoxane-bridged bitroticene 4, while palladium-catalyzed Negishi C–C cross-coupling reaction between the troticenylzinc chloride [(η⁷-C₇H₇)Ti(η⁵-C₅H₄ZnCl)] (13) and the iodotroticene 12 or iodobenzene (PhI) led to the fulvalene complexes [(η⁷-C₇H₇)Ti(η⁵-C₅H₄)]₂ (14) and [(η⁷-C₇H₇)Ti(η⁵-C₅H₄Ph)] (15). Compound 4 displays an unsymmetrical structure with the troticenyl fragments cis with respect to the Sn–O–Sn core, whereas compound 14 is centrosymmetrically trans oriented.     

Thermochemistry of bis-arene- and arenetricarbonyl-chromium compounds containing hexamethylbenzene, 1,3,5-trimethylbenzene and naphthalene.

Microcalorimetric measurements at elevated temperatures of the heats of thermal decomposition and iodination have led to values of the standard enthalpies of formation of the following crystalline compounds (values given in kJ mol^?1) at 298K: [Cr(η⁶-1,3,5-C₆H₃(CH₃)₃)₂] = (63±12); [Cr(η⁶-C₆(CH₃)₆)₂] : -(88±12); [Cr(1,2,3,4,4a,8a-η-C₁₀H₈)₂] = (407±11); [Cr(CO)₃(1,2,3,4,4a,8a-η-C₁₀H₈)] = -(258±8). Separate measurements by the vacuum sublimation microcalorimetric technique gave the following values for the enthalpy of sublimation at 298K (kJ mol^?1) : [Cr(η⁶-1,3,5-C₆H₃(CH₃)₃)₂] = (104±1); [Cr(η⁶-C₆(CH₃)₆)₂] = (119±4); [Cr(CO)₃(1,2,3,4,4a,8a-η-C₁₀H₈)] = (107±3). From these and other data, the bond enthalpy contributions of the metal-ligand bonds in the gaseous metal complexes were evaluated as follows: [(η₆-C₆(CH₃)₆)-Cr] (155±7); [(η⁶-C₆H₃(CH₃)₃)-Cr] (151±6); [(1,2,3,4,4a, 8a-η-C₁₀H₈)-Cr](145±6) kJ mol^?1]The question of the transferability of the enthalpy contributions of chromium—ligand bonds between organochronium complexes is discussed with aid of information from structural and spectroscopic investigation. The limitations of the procedure are defined.The thermodynamic data are used to discuss various substitution, redistribution and exchange reaction of Cr(η-arene)₂ and [Cr(CO)₃(η-arene)] compounds.     

Preparation and characterization of Cp-functionalized cycloheptatrienyl–cyclopentadienyl titanium sandwich complexes (troticenes)

Cp-functionalized monotroticenes [(η⁷-C₇H₇)Ti(η⁵-C₅H₄E)] (2, E = Ph₂SiCl; 3, E = tBu₂SnCl; 12, E = I) and bitroticenes [(η⁷-C₇H₇)Ti(η⁵-C₅H₄)]₂E′ (5, E′ = PPh; 6, E′ = BN(SiMe₃)₂; 7, E′ = Cp₂Ti) were prepared by salt elimination metathesis between the monolithiated troticene [(η⁷-C₇H₇)Ti(η⁵-C₅H₄Li)]·pmdta (1b) (pmdta = N,N′,N′,N″,N″-pentamethyldiethylene-triamine) and the appropriate electrophile. The troticenyl-substituted zirconocene monochloride [(η⁷-C₇H₇)Ti(η⁵-C₅H₄ZrClCp*₂)] (Cp* = η⁵-C₅Me₅) (8) and hafnocene ethoxide [(η⁷-C₇H₇)Ti{η⁵-C₅H₄Hf(OEt)Cp₂}] (Cp = η⁵-C₅H₅) (11), and the heterobimetallic μ-oxo complexes [(η⁷-C₇H₇)Ti(η⁵-C₅H₄MCp₂)]₂O (9, M = Zr; 10, M = Hf) were obtained instead of the expected zircona- and hafna[1]troticenophanes by reaction of the dilithiated troticene [(η⁷-C₇H₆Li)Ti(η⁵-C₅H₄Li)]·pmdta (1a) with [Cp₂MCl₂] (M = Zr, Hf) or [Cp*₂ZrCl₂] in stoichiometric amounts. These compounds were characterized by single crystal X-ray diffraction analyses and, in the case of 2, 3, 5–7, 9, 10 and 12, also by elemental analyses and ¹H, ¹³C and ¹¹⁹Sn NMR spectroscopy. Exposure of the troticenyl organotin chloride 3 to moisture resulted in its partial hydrolysis and formation of the organostannoxane-bridged bitroticene 4, while palladium-catalyzed Negishi C–C cross-coupling reaction between the troticenylzinc chloride [(η⁷-C₇H₇)Ti(η⁵-C₅H₄ZnCl)] (13) and the iodotroticene 12 or iodobenzene (PhI) led to the fulvalene complexes [(η⁷-C₇H₇)Ti(η⁵-C₅H₄)]₂ (14) and [(η⁷-C₇H₇)Ti(η⁵-C₅H₄Ph)] (15). Compound 4 displays an unsymmetrical structure with the troticenyl fragments cis with respect to the Sn–O–Sn core, whereas compound 14 is centrosymmetrically trans oriented.     

The Thermolysis of [Ru3(CO)12] in Cyclohexene: Synthesis and Charaterisation of the New Clusters [Ru3H2(CO)9(μ3-η1:η2:η1-C6H8)] and [Ru5(CO)12(μ4-η2-C6H8)(η4-C6H8)]

Thermolysis of [Ru₃(CO)₁₂] in cyclohexene for 24 h affords the complexes [Ru(CO)₃(η⁴-C₆H₈)] (1), [Ru₃H₂(CO)₉(μ₂-η¹:η²:η¹-C₆H₈)] (2), [Ru₄(CO)₁₂(μ₄-C₆H₈)] (3) [Ru₄(CO)₉(μ₄-C₆H₈)(η⁶-C₆H₆)] (4a and 4b, two isomers) and [Ru₅(CO)₁₂(μ₄-η²-C₆H₈)(η⁴-C₆H₈)] (5), where 1, 3, 4a and 4b have been previously characterised as products of the thermolysis of [Ru₃(CO)₁₂] with cyclohexa-1,3-diene. The molecular structures of the new clusters 2 and 5 were determined by single-crystal X-ray crystallography, showing that two conformational polymorphs of 5 exist in the solid state, differing in the orientation of the cyclohexa-1,3-diene ligand on a ruthenium vertex.     

Synthesis,structure, electrochemistry,and Mössbauer effect studies of (ring)Fe complexes (ring = Cp,Cp1, and C6H7). Photochemical replacement of benzene in the cyclohexadienyl complex [(η5-C6H7)Fe(η-C6H6)]+

Visible light irradiation of cation [(η⁵-C₆H₇)Fe(η-C₆H₆)]⁺ (1⁺) in acetonitrile results in substitution of the benzene ligand giving the labile acetonitrile derivative [(η⁵-C₆H₇)Fe(MeCN)₃]⁺ (2a⁺). The stable isonitrile and phosphite complexes [(η⁵-C₆H₇)FeL₃]⁺ [L = ^tBuNC (2b⁺), P(OMe)₃ (2c⁺), P(OEt)₃ (2d⁺)] were obtained by reaction of 1 with L in MeCN. The structures of 2cPF₆, [CpFe(η-C₆H₆)]PF₆ (3PF₆), and Cp¹Fe(η-C₆H₆)]PF₆ (4PF₆) were determined by X-ray diffraction.The redox activity of the cyclohexadienyl complexes 1⁺, 2b⁺?2d⁺ has been investigated by electrochemical techniques and compared with that of the related cyclopentadienyl complexes 3⁺ and 4⁺. DFT calculations of the redox potentials and the respective geometrical changes were performed.Variable temperature Mössbauer (ME) spectroscopy has elucidated the relationship between structure and formal oxidation state of the iron atom in these complexes. In the case of 3⁺ an unexpected pair of crystallographic changes has been observed and interpreted in terms of both a second and first order phase transition. The mean-square-amplitude-of-vibration of the metal atom has been compared between the ME and X-ray data. ME measurements in a magnetic field have shown that in 4⁺ the quadrupole splitting is positive as it is in ferrocene.