The stereoselective reaction of sodium cyanide with the cationic ruthenium vinylidene complex [(η5-C5H5)(PMe3)2RuCC(Me)Ph]+

The reaction of sodium cyanide with [(η⁵-C₅H₅)(PMe₃)₂RuCC(Me)Ph]PF₆ (1) proceeds with high stereoselectivity (> 95 : 5) to give (Z)-(η⁵-C₅H₅)(PMe₃)₂RuC(CN)C(Me)Ph, which under acid conditions isomerises (< 5 : 95) to the E isomer.     

Selective dilithiation of [Ti(η(5)-C5H5)(η(8)-C8H8)] and subsequent conversion into neutral and cationic ansa-complexes

Selective dimetalation of a sandwich complex featuring the cyclooctatetraene ligand has been accomplished for the first time. The isolation of the dilithiated species 1 subsequently enabled the isolation of a paramagnetic [2]stannatitanoarenophane (2) via salt elimination reaction. Chemical oxidation resulted in the formation of a rare example of a cationic ansa-complex (3).     

(η^5-C5H5)(η^5-C5H4R)TiCl2类化合物的新合成方法

本文报道了取代环戊二烯基负离子与[(η^5-C5H5)TiCl2]2O反应生成(η^5-C5H5)(η^5-C5H4R).TiCl2的新方法. 研究了取代环戊二烯基负离子的空间位阻和(η^5-C5H5)TiCl3, [(η^5-C5H5)TiCl2]2O的结构以及反应温度对产物产率的影响. 合成了七个新的(η^5-C5H5)(η^5C5H4R)TiCl2类型的化合物及七个相应的二氟化合物。     

(η^5-C5H5)(η^5-C5H4R)TiCl2类化合物的新合成方法

本文报道了取代环戊二烯基负离子与[(η~5-C_5H_5)TiCl_2]_2O反应生成(η~5-C_5H_5)(η~5-C_5H_4R)·TiCl_2的新方法。研究了取代环戊二烯基负离子的空间位阻和(η~5-C_5H_5)TiCl_3,[(η~5-C_5H_5)TiCl_2]_2O的结构以及反应温度对产物产率的影响。合成了七个新的(η~5-C_5H_5)(η~5-C_5H_4R)TiCl_2类型的化合物及七个相应的二氟化合物。     

π-complexes of monoanionic carborane ligand [9-(Me2S)-7,8-C2B9H10]− with [η-C5R5Fe]+ (R=H, Me) and [η-C4Me4Co]+ cationic fragments

Compounds (η-C₅R₅)Fe[η-9-(Me₂S)-7,8-C₂B₉H₁₀] (R=H, Me) and (η-C₄Me₄)Co[η-9-(Me₂S)-7,8-C₂B₉H₁₀] were synthesized by the reactions of Na[9-(Me₂S)-7,8-C₂B₉H₁₀] with complexes [(η-C₅H₅)Fe(MeCN)₃]PF₆, [(η-C₅Me₅)Fe(MeCN)₃]BF₄, and [(η-C₄Me₄)Co(MeCN)₃]PF₆, respectively. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 177–179, January, 1999.     

Synthesis, spectroscopy and electronic structure of the vinylidene and alkynyl complexes [W(C=CHR)(dppe)(η-C₇H₇)](+) and [W(C≡CR)(dppe)(η-C₇H₇](n+) (n = 0 or 1)

The first examples of vinylidene complexes of the cycloheptatrienyl tungsten system [W(C=CHR)(dppe)(η-C?H?)](+) (dppe = Ph?PCH?CH?PPh?; R = H, 3; Ph, 4; C?H?-4-Me, 5) have been synthesised by reaction of [WBr(dppe)(η-C?H?)], 1, with terminal alkynes HC≡CR; a one-pot synthesis of 1 from [WBr(CO)?(η-C?H?)] facilitates its use as a precursor. The X-ray structure of 4[PF?] reveals that the vinylidene ligand substituents lie in the pseudo mirror plane of the W(dppe)(η-C?H?) auxiliary (vertical orientation) with the phenyl group located syn to the cycloheptatrienyl ring. Variable temperature 1H NMR investigations on [W(C=CH?)(dppe)(η-C?H?)][PF?], 3, estimate the energy barrier to rotation about the W=C(α) bond as 62.5 ± 2 kJ mol?1; approximately 10 kJ mol?1 greater than for the molybdenum analogue. Deprotonation of 4 and 5 with KOBu(t) yields the alkynyls [W(C≡CR)(dppe)(η-C?H?)] (R = Ph, 6; C?H?-4-Me, 7) which undergo a reversible one-electron oxidation at a glassy carbon electrode in CH?Cl? with E(?) values approximately 0.12 V negative of Mo analogues. The 17-electron radicals [6](+) and [7](+) have been investigated by spectroelectrochemical IR, UV-visible and EPR methods. The electronic structures of representative vinylidene (3) and alkynyl (6) complexes have been investigated at the B3LYP/Def2-SVP level. In both cases, electronic structure is characterised by a frontier orbital with significant metal d(z2)character and this dominates the structural and spectroscopic properties of the system.     

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.     

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.     

Concerning the silicon-germanium bond: mass spectral fragmentations of isomeric SiGe compounds R3EE′R3 (E  Si,E′  Ge,R  Ph,Me,(η5-C5H4)Fe (C5H5), (η5-C5H5)Fe(CO)2 and (η5-C9H7) Fe(CO)2)

Isomeric pairs of silicon-germanium compounds containing a SiGe bond (Me₃SiGePh₃ (I) and Ph₃SiGeMe₃ (II); FpSiMe₂GeMe₃ (III) and FpGeMe₂SiMe₃ (IV) (Fp = (η⁵-C₅H₅)Fe(CO)₂); IFpSiMe₂GeMe₃ (V) and IFpGeMe₂SiMe₃ (VI) (IFp = (η⁵-C₉H₇)Fe(CO)₂); IFpSiMe₂GePh₃ (VII) and IFpGeMe₂SiPh₃ (VIII) and the complex FcSiMe₂GeMe₂Fc (IX) (Fc = ferrocenyl) have been synthesized and examined by mass spectrometry.The R₃SiGeR′₃ compounds I and II exhibit considerable exchange of R groups to produce [R_3-nR′_nSi]⁺ and [R′_3-nR_nGe]⁺ ion in progressively lesser amounts as n = 1 → 2 → 3. For the metal-substituted complexes containing the grouping FeSiGe fragmentation occurs predominantly via SiGe bond cleavage with formation of ions containing the silylene ligand [FeSiR₂]⁺. Complexes with the FeGeSi backbone undergo preferential scission of the FeGe bond, illustrating the general bond strength trend FeSi > SiGe. Upon direct cleavage of the SiGe bond in R₃SiGeR₃ compounds, the percentage of the charge carried by [R₃Si]⁺ ions significantly exceeds that carried by [R₃Ge]⁺ ions, reflecting the greater electronegativity of Ge polarizing the SiGe bond.     

A convenient,one-step synthesis of the cationic η3-allyl-molybdenum complex [(η5-C5H5)2Mo(η3-C3H5)]+[p-CH3C6H4SO3]−

[(η⁵-C₅H₅)₂Mo(η³-C₃H₅)]⁺ [p-CH₃C₆H₄SO₃]⁻ is conveniently synthesized by the reaction of (η⁵-C₅H₅)₂MoH₂ with allyl alcohol in the presence of p-toluene sulfonic acid, the mechanism of which is explained by the electrophilic cleavage of the allylO bond of the coordinated allyl alcohol.     

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.     

Reactions of (CO)2(η5-C5H5)Fe Alkyls and Ph3C+ BF4 : A Search for Hydrogen-Atom Abstraction following One-Electron-Transfer

The reaction products of Ph₃C⁺BF₄^- (2) and (CO)₂^- (η⁵-C₅H₅)Fe-(2-cyclopropylethyl) (1), -neopentyl (10), and -(1-norbornyl-carbinyl) (13) under N₂ and under CO have been determined in an effort to detect evidence of hydrogen-atom abstraction from the 17e, Fe(III) cation-radical intermediate produced by one-electron transfer to the starting cation. None was observed. Labeling studies reveal that migratory CO insertion to produce (CO)₂(η⁵-C₅H₅)FeCO(2-cyclo-propylethyl) (8) is accompanied by β- not α-hydride abstraction to form [(CO)₂(η⁵-C₅H₅)Fe(η²-cyclopropylethene)]⁺BF₄^-(3) when 1 reacts with 2 under CO. The insertion is catalytic in 2. Hydrogen is not lost from 10 or 13 under these conditions; the acyl complexes (CO)₂(η⁵-C₅H₅)FeCOCH₂-C(CH₃)₃ (11), 71%, or (CO)₂(η⁵-C₅H₅)FeCO(1-norbornylcarbinyl) (14), 80%, respectively, are the only organometallic products.     

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.     

Synthesis and reactions of phosphido-bridged μ3-alkylidyne clusters; X-ray crystal structures of the complexes [Co2W(μ-PEt2)3(CO)5(η-C5H5)], [Co2W{μ3-C(R)C(Et)C(Et)C(O)}(μ-CO)(CO)4(PPh2{C(Et)CHEt})(η-C5H5)], and [CoW{μ-C(R)C(Et)C(Et)C(OH)}(CO)4(η-C5H5)] (R = C6H4Me-4)

Reactions of the phosphido-bridged complexes [Co₂W(μ-H)(μ₃-CC₆H₄Me-4)(μ-PR₂)(CO)₆(η-C₅H₅)] (R = Ph or Et) with PR₂H (R = Ph or Et) or RCCR (R = Me or Et) are dominated by processes involving facile PC, CC and CH bond formation. The X-ray structures of the complexes [Co₂W(μ-PEt₂)₃(CO)₅(η-C₅H₅)], [Co₂W{μ₃-C(R)C(Et)C(Et)C(O)}(μ-CO)(CO)₄(PPh₂{C(Et)CHEt})(η-C₅H₅)], and [CoW{μ-C(R)C(Et)C(Et)C(OH)}(CO)₄(η-C₅H₅)] (R = C₆H₄Me-4) have been determined.     

Insertion reactions of t-Bu(η5-C5H5)Fe(CO)2

The complex t-Bu(η⁵-C₅H₅)FE(CO)₂ has been treated with triphenylphosphine in refluxing THF to produce t-BuCO(η⁵-C₅H₅)Fe(CO)(PPh₃). The large steric bulk of the t-butyl group suggests that this reaction should be faster than the reaction involving the methyl group, and a kinetic investigation illustrates this to be the case. The same steric bulk predicts that the reaction with SO₂ should be slow, and indeed we have been unable to effect the related SO₂ insertion reaction. Attempts to prepare the corresponding t-Bu(η⁵-C₅H₅)W(CO)₃ led to formation of the related isobutyl complex.     

Ligand-centred coupling of the alkynyl radical cations [Mo(CCR)(Ph2PCH2CH2PPh2)(η-C7H7)]+ (R = Ph or Bun: crystal structure of the dimeric product [Mo2(Ph2PCH2CH2PPh2)2(η-C7H7)2(μ-C4R2)][PF6]2 (R = Ph)

The radical cations [Mo(CCR)(dppe)(η-C₇H₇)]⁺ (R = Ph or Buⁿ); dppe = Ph₂PCH₂CH₂PPh₂) undergo coupling at C_β of the alkynyl ligand to afford the divinylidene-bridged, dimeric products [Mo₂(dppe)₂(η-C₇H₇)₂(μ-C₄R₂)]²⁺, characterised crystallographically for R = Ph.