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).     

Preparation and Structural Characterization of a Heterobimetallic Sulfide Cluster Compound [(η 5-C5Me5)WS3Au(dppms)]

A novel heterobimetallic sulfide cluster [( ⁵-C₅Me₅)WS₃Au(dppms)][dppms = bis(diphenylphosphino)methane monosulfide] was prepared by the reaction of [PPh₄][( ⁵-C₅Me₅)WS₃] with AuI and dppm [dppm = bis(diphenylphosphino)methane] in MeCN. The title compound was fully characterized by elemental analysis, i.r., u.v.–vis., ¹H-n.m.r. spectra, and by single crystal X-ray crystallography. In the molecular structure, the Au atom is trigonally coordinated by two bridging S atoms of a [( ⁵-C₅Me₅)WS₃]^– anion and a P atom of the dppms molecule. The formation mechanism for this compound is discussed.     

Base Stabilized σ-Borane Complex of Group 5 Metals: Synthesis and Structure of [(η5-C5Me5)Ta(H3BNC5H4) (C5H4NS)(η2-S2)]

Azametallacyclopropane-containing base stabilized borane complexes of group 5 transition metals have been synthesized and their structural aspects have been described. Treatment of Cp* based Ta and Nb chlorides, Cp*TaCl₄ and Cp*NbCl₄ with [LiBH₄ ⋅ THF] followed by addition of ligands, such as 2-mercaptobenzothiazole, MBT, (C₇H₅NS₂) and 2-mercaptobenzoxazole, MBO (C₇H₅NSO) led to the formation of complexes [Cp*M-[BHS(CH₂ENC₆H₄)(C₇H₄NSE)] ( 1 : M=Ta, E=S; 2 ; M=Nb, E=S; 3 : M=Ta, E=O; 4 ; M=Nb, E=O, Cp*=pentamethyl-η⁵-cyclopentadienyl). By means of UV-vis absorption spectra, the electronic properties of these complexes associated with central metal atoms and heteroatoms (S or O) have been evaluated. In contrast, treatment of Cp*TaCl₄ with 2-mercaptopyridine, MP, (C₅H₅NS) under the same reaction conditions yielded the agostic σ-borane Ta complex, [Cp*Ta(H₃BNC₅H₄) (C5H₄NS)(η²-S₂)], 5 . Unlike 1 – 4 , where the metals interact with boron through bridging sulphur, 5 shows a notable σ-B−H bond interaction with Ta. All spectroscopic data of 1 – 5 along with the X-ray diffraction studies suggest complexes 2 , 4 , and 5 are base (amine) stabilized borane species. Computational studies based on Density Functional Theory (DFT) also supported this conclusion.     

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.     

Structure and bonding analysis of dimethylgallyl complexes of iron, ruthenium, and osmium [(η5-C5H5)(CO)2M(GaMe2)] and [(η5-C5H5)(Me3P)2M(GaMe2)

Density functional theory calculations have been performed for the dimethylgallyl complexes of iron, ruthenium, and osmium [(η(5)-C(5)H(5))(L)(2)M(GaMe(2)] (M = Fe, Ru, Os; L = CO, PMe(3)) at the DFT/BP86/TZ2P/ZORA level of theory. The calculated geometry of the iron complex [(η(5)-C(5)H(5))(CO)(2)Fe(GaMe(2))] is in excellent agreement with structurally characterized complex [(η(5)-C(5)H(5))(CO)(2)Fe(Ga(t)Bu(2))]. The Pauling bond order of the optimized structures shows that the M-Ga bonds in these complexes are nearly M-Ga single bond. Upon going from M = Fe to M = Os, the calculated M-Ga bond distance increases, while on substitution of the CO ligand by PMe(3), the calculated M-Ga bond distances decrease. The π-bonding component of the total orbital contribution is significantly smaller than that of σ-bonding. Thus, in these complexes the GaX(2) ligand behaves predominantly as a σ-donor. The contributions of the electrostatic interaction terms ΔE(elstat) are significantly smaller in all gallyl complexes than the covalent bonding ΔE(orb) term. The absolute values of the ΔE(Pauli), ΔE(int), and ΔE(elstat) contributions to the M-Ga bonds increases in both sets of complexes via the order Fe < Ru < Os. The Ga-C(CO) and Ga-P bond distances are smaller than the sum of van der Waal radii and, thus, suggest the presence of weak intermolecular Ga-C(CO) and Ga-P interactions.     

Palladacycles of novel bisoxazoline chelating ligands based on the dimeric cyclobutadiene linked cobalt sandwich compound [(η5-Cp)Co(η4-C4Ph3)]2

The reaction of 1,4-diphenylbutadiyne along with diphenylacetylene, when carried out with η(5)-[MeOC(O)Cp]Co(PPh(3))(2) resulted in the cyclobutadiene linked dimeric cobalt sandwich compound {[η(5)-MeOC(O)Cp]Co(η(4)-C(4)Ph(3))}(2) (1) along with the known monomeric compound η(5)-[MeOC(O)Cp]Co(η(4)-C(4)Ph(4)). Compound 1, on treatment with KOH gave the dicarboxylic acid {η(5)-[HOC(O)Cp]Co(η(4)-C(4)Ph(3))}(2) (2) which on reaction with oxalyl chloride followed by (S)-2-amino-3-methyl-1-butanol, triethylamine and mesylchloride was converted to the bis(cobalt oxazoline) based chiral ligand {[η(5)-(4-iPr-2-Ox)Cp]Co(η(4)-C(4)Ph(3))}(2) (3) (Ox = Oxazolinyl). Compound 3 on reaction with palladium acetate gave an NCN bound bis(cobalt-oxazolinyl) palladacycle {[η(5)-(4-iPr-2-Ox)Cp]Co(η(4)-C(4)Ph(3))}(2)PdOAc (4) having both the oxazolinyl groups bound to the palladium in a chelate mode and one of the Cp rings forming a five membered [C,N] palladacycle. Reaction of 4 with aq. NaCl resulted in the chloro analogue of 4, {[η(5)-(4-iPr-2-Ox)Cp]Co(η(4)-C(4)Ph(3))}(2)PdCl (5). A nonchiral bidentate bis cobalt oxazoline ligand {[η(5)-(Ox)Cp]Co(η(4)-C(4)Ph(3))}(2) (6) was also prepared by replacing (S)-2-amino-3-methyl-1-butanol with 2-amino-1-ethanol in the procedure used for the preparation of 3. A reaction of 1,4-diphenylbutadiyne, diphenylacetylene and (η(5)-Cp)Co(PPh(3))(2) resulted in the dimer [(η(5)-Cp)Co(η(4)-C(4)Ph(3))](2) (7) and small amounts of a trimer [(η(5)-Cp)Co(η(4)-C(4)Ph(3))](2)[(η(5)-Cp)Co(η(4)-C(4)Ph(2))] (8) having no substituents on the Cp rings. All the compounds except 2 were structurally characterized. Structural studies on palladacycles 4 and 5 showed interesting anagostic C-H···Pd interactions between the ortho hydrogen of one of the Cp rings and the palladium centre. Preliminary studies carried out on the palladacycles showed promising catalytic activity in the asymmetric rearrangement of trichloroacetimidates.     

Synthesis and Crystal Structure of an Incomplete Cubane-like Heterobimetallic Cluster [(η5-C5Me5)2Mo2(μ3-S)(μ-S)3(CuCl)]

The reaction of [(η5-C5Me5)2Mo2(μ3-S)4(CuCl)2] 1 with Na2S in MeCN produced a trinuclear cluster [(η5-C5Me5)2Mo2(μ3-S)( μ3-S)3(CuCl)] 2. 2 crystallizes in the monoclinic system, space group P21/c with a=15.563(3), b=8.9547(18), c=17.846(4) (A), β=101.29(3)°, V=2438.9(9) (A)3, Z=4, Dc=1.878 g/cm3, T=193(2) K, C20H30ClCuMo2S4, Mr=689.60, F(000)=1376, μ(MoKα)=2.335 mm–1, S=1.050, R=0.0305 and wR=0.0688 for 4033 observed reflections with Ⅰ ＞ 2σ(Ⅰ). In the structure of 2, one [(η5-C5Me5)2Mo2(μ-S)2S2] moiety and one CuCl unit are assembled into an incomplete cubane-like [Mo2S4Cu] core framework, in which the Cu center adopts a distorted tetrahedral geometry coordinated by oneμ3-S atom, twoμ-S atoms and one terminal chloride. The two Mo…Cu contacts are 2.7519(7) and 2.7689(8) (A), respectively.     

Some reactions of [(η6-C6Me6)Ru(η6-[2.2]paracyclophane)]-[BF4]2 with nucleophiles

Single addition of the nucleophiles X⁻ (X = H, CN, OH) to the less sterically hindered ring in [(η⁶-C₆Me₆)Ru(η⁶-C₁₆H₁₆)][BF₄]₂ (1) proceeds smoothly to produce, as the sole product, [(exo-η⁵-C₆Me₆X)Ru(η⁶-C₁₆H₁₆)][BF₄]. Use of Na[BD₄] in place of Na[BH₄] gives the expected shift in ν(C-H_exo) in the infrared spectrum.     

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.     

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.     

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.     

Synthesis of a Mo–Ru/Carbon Nanocomposite Using (η-C7H7)(OC)2MoRu(CO)2(η-C5H5) as a Single-Source Molecular Precursor

Degradation of a (-C₇H₇)(OC)₂MoRu(CO)₂(-C₅H₅)/carbon powder composite under appropriate thermal conditions affords a nanocomposite containing crystalline nanoclusters of Mo–Ru alloy highly dispersed on the carbon support. The alloy nanoparticles have an average diameter of 2.2 nm and crystallize as a fully disordered fcc lattice having a cell constant of 4.09 Å. When tested as an cathode catalyst in a direct methanol fuel cell, this nanocomposite shows significant methanol tolerance but affords current production too low to be of practical importance.     

Diphenylcarbene rhodium complexes: of the halfsandwich type with (η5-C5H4SiMe3)Rh as a molecular unit

The square-planar rhodium(I) complexes trans-[RhCl(=CPh₂)(L)₂] (L = SbiPr₃, PiPr₃, PPh₃) react with LiC₅H₄SiMe₃ to give the halfsandwich type compounds [(η⁵-C₅H₄SiMe₃)Rh(=CPh₂)(L)] 7–9 in good to excellent yields. While the phosphine complexes 8 and 9 are rather inert toward Lewis bases, the stibine derivative 7 reacts with CO, CNtBu and PMe₃ to afford the corresponding substitution products [(η⁵-C₅H₄SiMe₃)Rh(=CPh₂)(L′] 10–12. In contrast, the reaction of 7 with C₂H₄ leads to the displacement of the carbene ligand and to the formation of the ethene complex [(η⁵-C₅H₄SiMe₃)Rh(C₂H₄)(SbiPr₃)] 14 together with the C−C coupling product Ph₂C=CHCH₃13. Upon treatment of 9 (L = PPh₃) with an equimolar amount of HCl, the chloro(hydrido)rhodium(III) compound [{η⁵-C₅H₃)(CHPH₂)(SiMe₃)}RhHCl(PPh₃)] 15 is formed. With an excess of HCl, a mixture of two products is obtained, one of which, with the composition [η⁵-C₅H₄)CHPh₂)RhCl₂(PPH₃)] 17 has been independently prepared from η⁵-C₅H₅)Rh(=CPh₂)(PPh₃] 18 and 2 equiv of HCl.     

The asymmetric sythesis of (-)-actinonin using the iron chiral auxiliary [(η5-C5H5)Fe(CO)(PPh3)]

The asymmetric synthesis of the α-pentyl succinate fragment of (-)-Actinonin is achieved using the chiral iron acetyl S-(+)-[(η⁵-C₅H₅)Fe(CO)(PPh₃)COCH₃] and subsequently converted to (-)-Actinonin in an overall yield of 41%.     

Synthesis and characterisation of a pyrazine bridged bis-allyl ruthenium(IV) complex. Crystal structure of [{(η3:η3-C10H16)RuCl2}2(μ-C4H4N2)]·2CHCl3

The reaction of pyrazine with the ruthenium(IV) bis-allyl dimer [(η³:η³-C₁₀H₁₆)RuCl(μ-Cl)]₂ gives the bridged binuclear complex [{(η³:η³-C₁₀H₁₆)RuCl₂}₂(μ-C₄H₄N₂)] in high yield. The complex has been characterised by ¹H NMR spectroscopy and by a single-crystal X-ray diffraction study.     

30-Electron cationic iron- and cobalt-containing triple-decker complexes with a central cyclopentadienyl ligand. The first synthesis of the parent triple-decker iron complex with cyclopentadienyl ligands, [(η-C5H5)Fe(μ-η:η-C5H5)Fe(η-C5H5)]PF6

The parent 30-electron triple-decker iron complex with cyclopentadienyl ligands, [(η-C₅H₅)Fe(μ-η:η-C₅H₅)Fe(η-C₅H₅)]PF₆ (1), was prepared for the first time by visible-light irradiation of ferrocene and [(η-C₅H₅)Fe(η-C₆H₆)]PF₆ in CH₂Cl₂ at 0 °C. An analogous reaction performed with the use of (η-C₅H₅)Co(η-C₄Me₄) (2) instead of ferrocene afforded the thermally labile 30-electron cationic iron-cobalt triple-decker complex [(η-C₅H₅)Fe(μ-η:η-C₅H₅)Co(η-C₄Me₄)]PF₆. The latter reacted with compound 2 at 20 °C to form the symmetrical 30-electron cationic dicobalt triple-decker complex [(η-C₄Me₄)Co(μ-η:η-C₅H₅)Co(η-C₄Me₄)] PF₆. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya. No. 7, pp. 1364–1367, July, 1999.     

Palladium(II) compounds with planar chirality. X-Ray crystal structures of (+)-(R)-[{(η5-C5H4)–CHN–CH(Me)–C10H7}Fe(η5-C5H5)] and (+)-(Rp,R)-[Pd{[(Et–CC–Et)2(η5-C5H3)–CHN–CH(Me)–C10H7]Fe(η5-C5H5)}Cl]

A wide variety of planar chiral cyclopalladated compounds of general formulae [Pd{[(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl(L)] (with L=py-d₅ or PPh₃), [Pd{[(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}(acac)] or [Pd{[(R¹–CC–R²)₂(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl] (with R¹=R²=Et; R¹=Me, R²=Ph; R¹=H, R²=Ph; R¹=R²=Ph; R¹=R²=CO₂Me or R¹=CO₂Et, R²=Ph) are reported. The diastereomers {(R_p,R) and (S_p,R)} of these compounds have been isolated by either column chromatography or fractional crystallization. The free ligand (R)-(+)-[{(η⁵-C₅H₄)–CHN–CH(Me)–C₁₀H₇}Fe(η⁵–C₅H₅)] (1) and compound (+)-(R_p,R)-[Pd{[(Et–CC–Et)₂(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl] (7a) have also been characterized by X-ray diffraction. Electrochemical studies based on cyclic voltammetries of all the compounds are also reported.     

Synthesis and structures of the η5-C5H5Cl(CO)2W-η1,η5-(PPh2)C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)3 and MeSi[C5H4(CO)2Fe-η1,η5-C5H4Mn(CO)2PPh3]3 complexes

The metallation of the η⁵-C₅H₅(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ complex with BuⁿLi (THF, ?78 °C) followed by the treatment of the lithium derivative with Ph₂PCl afforded the η⁵-Ph₂PC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃ complex. The reaction of the latter with η⁵-C₅H₅(CO)₃WCl in the presence of Me₃NO produced the trinuclear complex η⁵-C₅H₅Cl(CO)₂W-η¹,η⁵-(Ph₂P)C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₃. The structure of the latter complex was established by IR, UV, and 1H and ³¹P NMR spectroscopy and X-ray diffraction. The reaction of MeSiCl₃ with three equivalents of LiC₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₂PPh₃ gave the hexanuclear complex MeSi[C₅H₄(CO)₂Fe-η¹,η⁵-C₅H₄Mn(CO)₂PPh₃]₃.