New one-pot methods for the synthesis of metallonium dications [1,2-(η5:σ:σ-C5Me3(CH2)2)(η5-Cp*)Os]2+ and [1,1"-(η5:σ-C5Me4CH2)2Os]2+ based on decamethylosmocene or its derivatives

The reaction of Cp*₂Os or [Cp*₂OsH]⁺PF₆ ^– with oleum on heating or UV photolysis of Cp*₂Os in oleum under an inert atmosphere afforded two metallonium dications, viz., [1,2-(⁵::-C₅Me₃(CH₂)₂)(⁵-Cp*)Os]²⁺ and [1,1"-(⁵:-C₅Me₄CH₂)₂Os]²⁺. The structures of these dications were confirmed by the results of their alkoxylation. The [Os(H)₂(Cp*)₂]²⁺ and [Os(H)(Cp*)(C₅Me₄CH₂)]²⁺ dications were detected as intermediates in the above syntheses. All compounds were characterized by NMR spectroscopy. Calculations of the dications were carried out using the density functional theory (DFT).     

The reductive dimerization of [W(NCMe)(MeC2Me)2(η-C5H5)]+: Synthesis and X-ray structure of the novel bis(metallacyclopentadiene) complex [W2(μ-σ,σ,η2,η2-C4Me4)2(η-C5H5)2]

Treatment of [W(CO)(MeC₂Me)₂(-C₅H₅)][PF₆] with ONMe₃ in acetonitrile yields [W(NCMe)(MeC₂Me)₂(-C₅H₅)][PF₆] which undergoes irreversible reduction at a Pt electrode in THF. Sodium amalgam reduction of [W(NCMe) (MeC₂Me)₂(-C₅H₅)][PF₆] gives orange crystals of [W₂(µ-,, ², ²-C₄Me₄)₂ (-C₅H₅)₂] X-ray studies on which reveal pairwise alkyne coupling and a novel bis(metallacyclopentadiene) structure.Dedicated to Professor L. F. Dahl on the occasion of his 65th birthday.     

Triphospha-Ferrocenes as Ligands. Crystal Structures of [Fe(η5-C5Me5)(η5-C2 TBu2P3)M(CO)5)], (M= Cr,MO, W) and the Novel ruthenium and Nickel Complexes [Fe(η5-C5Me5) (η5-C2 TBu2P3)Ru3(CO)9] and [Fe(η5-C5Me5)(η5-C2 tBu2P3)Ni(Co)2]2

Abstract

Syntheses and structures of penta- and hexaphosphorus analogues of ferrocene have been described recently¹. Unlike their simple ferrocene analogues, these complexes have further ligating potential towards other transition metal centres by virtue of the availability of the ring phosphorus lone-pair electrons that are not involved in the η⁵-coordination. We now describe the first examples of coordination compounds of the triphospha-ferrocene [Fe(η⁵-C₅Me₅) (η⁵-C₂ ^tBu₂P₃]. In the ruthenium complex [Fe(η⁵-C₅Me₅)(η⁵-C₂ ^tBu₂P₃) Ru₃(CO)₉] ² two adjacent phosphorus atoms of the η⁵-C₂ ^tBu₂P₃ ring are interlinked by a ruthenium carbonyl cluster in which all three ruthenium atoms interact with the phosphorus atoms. The tetrametallic nickel complex [Fe(η⁵-C₅Me₅)(η⁵-C₂ ^tBu₂P₃)Ni(CO)₂]₂ ³ represents the first example of intermolecular interlinkage of two phospha-ferrocene systems by two metal centres.     

Reactivity of the tethered alkyl uranium bonds of (η5:κ1-C5Me4SiMe2CH2)2U

Uranium-carbon bond reactivity has been investigated with the bis(tethered silylalkyl) uranium metallocene (η⁵:κ¹-C₅Me₄SiMe₂CH₂)₂U, 1. Tert-butyl nitrile, ^tBuCN, inserts into both of the tethered U-C bonds to produce the bis(tethered ketimide) complex [η⁵:κ¹-C₅Me₄SiMe₂CH₂C(^tBu)N]₂U, 2, which has unusually bent U-N-C bond angles. Carbon dioxide also inserts into both U-C bonds of 1 yielding the bis(tethered carboxylate) (C₅Me₄SiMe₂CH₂CO₂)₂U, 3. Neither PhCCPh nor PhCCH insert into the U-C bonds, but PhCCH cleaves the silylalkyl tethers in 1 to generate (C₅Me₄SiMe₃)^1? ligands in the complex (C₅Me₄SiMe₃)₂U(CCPh)₂, 4.     

Insertions of nitriles and pyridine into the ZrSi bond of (η5-C5H5)(η5-C5Me5)Zr[Si(SiMe3)3]Me

The zirconium silyl complex CpCpZr[Si(SiMe₃)₃]Me (1; Cp = η⁵-C₅H₅; Cp = η⁵-C₅Me₅) reacts with nitriles RCN (R = Me, CHCH₂, Ph) to form the azomethine derivatives CpCpZr[NC(R)Si(SiMe₃)₃]Me (2, R = Me; 3, R = CHCH₂; 4, R = Ph). Pyridine reacts with 1 to give a 75% yield of CpCpZr[NC₅H₅Si(SiMe₃)₃]Me (5), which results from 1,2-addition of the ZrSi bond of 1 to pyridine. These reactions provide the first examples of nitrile and pyridine insertions into a transition metal-silicon bond. The related silyl complexes Cp₂Zr[Si(SiMe₃)₃]Me and CpCpZr[Si(SiMe₃)₃]Cl are much less reactive toward nitriles and pyridine.     

Zinc-zinc bonded decamethyldizincocene Zn2(η(5)-C5Me5)2 as catalyst for the inter- and intramolecular hydroamination reaction

The Zn-Zn bonded compound [(η(5)-Cp*)(2)Zn(2)] was investigated as catalyst for the inter- and intramolecular hydroamination reaction. High reaction rates under mild conditions were observed. This is the first application of a Zn-Zn bonded compound as catalyst.     

Regioselective permethylation,perallylation and perbenzylation of the arene ligand in [Ru(η5-C5Me5)(η6-C6Me6)][PF6]: a remarkable periodic effect

The reactions of [MCp^*(η⁶-C₆Me₆)][PF₆], M = Fe: 1, Ru: 2, Cp^* = η⁵-C₅Me₅, with KOH (in DME) or tert-BuOK (in THF) and methyl iodide, allyl bromide or benzyl bromide are regioselective on the arene ligand only for 2, giving the complexes [RuCp^*{η⁶-C₆(CH₂R)₆}][PF₆], R = methyl (3), allyl (4) or benzyl (5), although some formations of C-C bonds also occur on the Cp^* ligand in the case of the reactions of allyl and benzyl bromides. This contrasts with the complete lack of regioselectivity formerly observed with the iron analogue 1, and is best taken into account by the difference of steric effects which are less marked in 2 than in 1.     

A mild,phosphine-assisted synthesis of (η-C5Me5)Ta(CO)4. Isolation and crystal structure of intermediate (η-C5Me5)TaCl2(CO)2(PMe3)

Mild, reductive carbonylation of (C₅Me₅)TaCl₄ in the presence of trimethylphosphine gives (C₅Me₅)Ta(CO)₄ in 47% yield. The intermediate (C₅Me₅)TaCl₂- (CO)₂(PMe₃) has been isolated from the reaction of (C₅Me₅)TaCl₂(PMe₃)₂ with carbon monoxide and its crystal structure determined (space group P2₁2₁2₁).     

Generation of the dichloromethane complex [(η5-C5Me5)Re(NO)(PPh3)(ClCH2Cl]+ BF4−, and its conversion to the oxidative addition product [(η5-C5Me5)Re(NO)(PPh3)(Cl)(CH2Cl)]+ BF4−

Reaction of (η⁵-C₅Me₅)Re(NO)(PPh₃)(CH₃) and HBF₄ · OEt₂ in CH₂Cl₂ at −78°C gives the dichloromethane complex [η⁵-C₅Me₅Re(NO)(PPh₃)(ClCH₂Cl)]⁺ BF₄⁻, which undergoes the title transformation at −35°C. The ReClCH₂Cl carbon is attacked by halide nucleophiles (X⁻) to give XCH₂Cl and the chloride complex (η⁵-C₅Me₅)Re(NO)(PPh₃)(Cl), and exhibits a ¹³C NMR resonance that is coupled to phosphorus (d, ³J(CP) 5.0 Hz) and geminal hydrogens (t, ¹J(CH) 186 Hz).     

Molecular structure of ansa-compound (η5-C5H4)CMe2(η5-C9H6)TiCl2

The structure of a new ansa compound, (⁵-C₅H₄)CMe₂(⁵-C₉H₆)TiCl₂ (1), was studied by X-ray analysis:a = 15.00(1),b =15.500(5),c = 13.032(4) Å, = 92.66°(4),V = 3025.1(1) ų, space groupP2₁/.,R = 0.038. The distorted tetrahedral coordination sphere of the Ti atom is formed by two Cl atoms and two -ligands. It was proposed that the angle () between theC-M direction and the line normal to M-Cp can be considered as one of the geometric parameters characteristic of the structure-properties correlation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 305–308, February, 1995.     

Synthesis and the fluxional behavior of the 30-electron cationic iron-molybdenum triple-decker complex with a central pentaphospholyl ligand, [(η-C7H7)Mo(μ-η:η-P5)Fe(η-C5Me5)]BF4

The reaction of [(η-C₇H₇)Mo(MeCN)₃)]BF₄ with (η-C₅Me₅)Fe(η-P₅) afforded the new 30-electron triple-decker complex [(η-C₇H₇)Mo(μ-η:η-P₅)Fe(η-C₅Me₅)]BF₄. Studies of the temperature dependence of the¹H NMR spectra demonstrated that the resulting compound contains a fluxional cyclohepatrienyl ligand. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1374–1376, July, 1999.     

Electron density distribution in vanadocene (η5-C5H5)2V and mixed metallocenes (η5-C5H5)M(η5-C7H7) (M = Ti,V, or Cr) and (η5-C5H5)Ti(η8-C8H8). Effect of the nature of the cyclic ligand on the character of the M--(π-ligand) bond

The electron density distribution and atomic displacements were analyzed based on the results of precision low-temperature X-ray diffraction studies of a series of isostructural (Pnma, Z = 4) mixed metallocenes (⁵-C₅H₅)M(⁵-C₇H₇) (M = Ti, V, or Cr) and (⁵-C₅H₅)Ti(⁸-C₈H₈). The barriers to rotation of the cyclic ligands were evaluated based on rms libration amplitudes. Analysis of the deformation electron density demonstrated that the character of the M--(-ligand) chemical bond depends substantially both on the nature of the metal atom and the size of the ligand. Lowering of the local symmetry of the (⁵-C₅H₅)M(⁵-C₇H₇) complexes to C_S leads to distortion of the cylindrical symmetry of the electron density distribution observed in vanadocene (⁵-C₅H₅)₂V and titanocene (⁵-C₅H₅)Ti(⁸-C₈H₈).     

Electron transfer in organometallic clusters: XIV. Crystal and electronic structures of the tricobalt carbon cluster (η5-C5H5)Fe[η5-C5H4-CCo3(CO)9] and the biscarbyne cluster (η5-C5H5)Fe[η5-C5H4CCo3(η5-C5H5)3CH]

The crystal and molecular structures of (η⁵-C₅H₅)Fe[η⁵--C₅H₄CCo₃(CO)₉] (1), Pna2₁, α 17.354, b 11.463, c 11.207 Å Z = 4, R = 0.053, R_w = 0.056 for 939 reflections (I>3σ(I)) at 293 K, and (η⁵-C₅H₅Fe[η⁵--C₅H₄CCo₃(η⁵C₅H₅)₃CH] (2), P2₁/n, a 13.807(9), b 11.254(4), c 13.991(9) Å, β 99.98(5)°, Z = 4, R = 0.033 and R_w = 0.033 for 3051 observed reflections (I>3σ(I)) at 180 K, have been determined by X-ray methods.The results provide a detailed characterisation of related tricobalt-carbon complexes directly bound to ferrocene residues. In 1 the ferrocenyl moiety tops the pyramidal CCo₃ cluster core, while in 2 the CCo₃C core is bipyramidal with a ferrocenyl substituent on one capping carbon atom and a hydrogen atom at the other. In both cases the ferrocenyl group is tilted towards one cobalt atom of the cluster core, a distortion believed to be the consequence of the non-degeneracy of the carbyne p(π) orbitals resulting from a cooperative π-interaction between the clusters and the ferrocenyl substituents.     

Replacement of terminal and bridging oxo groups by phenylimido groups in (η-C5H5)OMo(μ-O)2OMo(η-C5H5) giving (η-C5H5)(NPh)Mo(μ-NPh)2Mo(NPh)(η-C5H5)

The treatment of (η-C₅H₅)OMo(μ-O)₂MoO(η-C₅H₅) with excess phenylisocyanate at reflux in tetrahydrofuran yields the arylimido-substituted complex (η-C₅H₅)(NPh)Mo(η-NPh)₂Mo(NPh)(η-C₅H₅), which has been characterized by elemental analysis, and mass, IR and ¹H NMR spectra.     

The preparation of a series of ring-linked derivatives of [Fe2(η-C5H5)2(CO)2(μ-CO)2] starting from [Fe2η5,η5-C5H4CH(NMe3)CH(NMe2)C5H4}(CO)2(μ-CO)2]+ salts

The salts [Fe₂η⁵,η⁵-C₅H₄CH{NMe₃)CH(NMe₂)C₅H₄}(CO)₂(μ-CO)₂][X] (X = I or SO₃CF₃) are the synthetic precursors to a wide range of [Fe₂(η-C₅H₅)₂(CO)₂(μ-CO)₂] derivatives in which the two cyclopentadienyl ligands are joined by a two-carbon bridge.     

Enantioselective synthesis: Catalysis of the aldol reaction by neutral gold(I)-chiral ferrocenylphosphine complexes. Crystal structure of the complex [{(η5-C5H4PPh2)(η5-C5H3(PPh2)CH(Me)N(Me)CH2CH2NMe2)Fe}2(AuCl)3] · Et2O

The chiral aminoferrocenylphosphine [(η⁵-C₅H₄PPh₂)(η⁵-C₅H₃(PPh₂)CH(CH₃)-N(CH₃)CH₂CH₂N(CH₃)₂)Fe] (1) reacts with (H₃C)₂SAuCl to give neutral gold(I) complexes that are active catalysts for the enantioselective coupling of isocyanoacetate esters with aldehydes, forming dihydrooxazoles. The structure of the trimeric complex [(rac-1)₂(AuCl)₃] · Et₂O has been determined by X-ray diffraction.