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).     

Adduct formation of [(η7-C7H7)Hf(η5-C5H5)] with isocyanides,phosphines and N-heterocyclic carbenes: An experimental and theoretical study

The reactions of [(η⁷-C₇H₇)Hf(η⁵-C₅H₅)] (1b) with the two-electron donor ligands tert-butyl isocyanide (tBuNC), 2,6-dimethylphenyl isocyanide (XyNC), 1,3,4,5-tetramethylimidazolin-2-ylidene (IMe) and trimethylphosphine (PMe₃) are reported. The 1:1 complexes [(η⁷-C₇H₇)Hf(η⁵-C₅H₅)L] (2b, L = tBuNC; 3b, L = XyNC; 4b, L = IMe, 5b, L = PMe₃) have been isolated in crystalline form, and their molecular structures have been determined by X-ray diffraction analyses. The stabilities of these hafnium complexes were probed via spectroscopic and theoretical methods, and the results were compared to those previously reported for the corresponding zirconium complexes derived from [(η⁷-C₇H₇)Zr(η⁵-C₅H₅)] (1a). The X-ray crystal structure of the PMe₃ adduct [(η⁷-C₇H₇)Zr(η⁵-C₅H₅)(PMe₃)] (5a) was also established.     

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.     

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.     

On the stereochemistry of chiral (η5-C9H7)Rh(diphosphine) complexes

The dynamic behaviour of some indenyl complexes of the type (η⁵-C₉H₇)Rh(Ph₂PCHRCHR′PPh₂) (R = or ≠ R′) has been investigated, and the relevant energy barrier involved evaluated (10–11 kcal/mol). For the complexes in which the diphosphine has a C₁ symmetry (R ≠ R′), the energy differences between the two diastereometric conformations seem to depend on both steric and electronic factors.     

Cyclooctaselenadiazole: synthesis,decomposition pathway,and reaction with (η5-C5H5) Co(L)2 (L = C2H4, PPh3). Crystal and molecular structure of [(η5-C5H5)CO]2(μ2-η3,η2-C8H6Se)

Thermolysis of cyclooctaselenadiazole (2) yields only selenium-containing products. Compound 2 reacts with CpCo sources to give [(η⁵-C₅H₅)CO]₂(μ₂η³,η²-C₈H₆Se), a fluxional compound whose structure has been determined by X-Ray crystallography.     

In Situ Generation of the Fulvalene Ligand via C–H Activation by Gray Antimony and Its Incorporation into the Tetrahedral Cluster [(μ,η5:η5-C10H8) (η5-C5H5)M3(CO)6(μ3-Sb)] (M=Mo or W)1

The first tetrahedral clusters containing a single naked antimony atom have been prepared by the thermolysis of [CpM(CO)₃]₂ (M=Mo or W) in the presence of gray antimony at 180°C in toluene in a sealed Carius tube. X-ray structural characterization revealed that, in addition to the incorporation of Sb in the cluster, it has also affected coupling of two Cp rings to form [(, ⁵: ⁵-C₁₀H₈)( ⁵-C₅H₅)-M₃(CO)₆( ₃-Sb)]. It is only the second example of in situ formation of the fulvalene ligand for group-6 metal. Simultaneous with the C–C coupling reaction, a mirror of Sb forms on the reaction tube; this indicates that SbH₃ is formed in the hydrogen abstraction step, which then subsequently decomposes at the tube wall.     

The formation and molecular structure of (η5-C5H5)3Sm · OC4H8

Reaction of 1/2 mole ratio of (η⁵-C₅H₅)SmCl₂ ·3THF and NaCCCH₂OCH₂CHCH₂ in THF solution resulted in the formation of (η⁵-C₅H₅)Sm·OC₄H₈; the complex crystallizes in monoclinic space group P2₁/n with unit cell constants a = 8.254(5), b = 24.63(1), c = 8.339(3) Å, β = 101.33(5)° and D_c = 1.67 g/cm³ for Z = 4. Refinement has led to a final R value of 0.041 based on 2106 independent observed reflections. The THF molecule is coordinated to the samarium atom at a SmO distance of 2.522(6) Å. The SmC(cyclopentadienyl) bond lengths range from 2.70(1) to 2.80(1) Å and average 2.742(1) Å. A comparison of some significant structural parameters along the isostructural series (η⁵-C₅H₅)₃Ln·THF (LnLa, Pr, Nd, Gd, Dy, Lu and Sm) with the ionic radii of Ln³⁺ was made.     

Structural chemistry of titanium and aluminium bimetallic hydride complexes VI. Molecular structure and physico-chemical properties of (η5-C5 H5) 2Ti(μ2-H)2 Al(Cl) (μ2 -H)2Ti(η5-C5H 5)2, a catalyst-precursor for hydrogenation in the [(η5-C5H5)2TiCl]2-LiAIH4 system

The complex (Cp₂Ti)₂AlH₄Cl has been isolated from the catalytic system (Cp₂TiCl)₂-LiAlH₄, which is a precursor of the catalyst for the hydrogenation and isomerization of olefins. This complex has been studied by X-ray diffraction. The complex forms rhomboidal crystals with unit cell dimensions a = 10.414, b = 11.998, c = 16.008 Å, space group P2₁2₁2₁, Z = 4, and density ϱ_calc = 1.40 g/cm³. The Cp₂Ti moieties are linked to the Al atom via double hydrogen bridges; the Cl atom is bonded to the Al atom. Analysis of the EPR spectral data and some chemical properties of (Cp₂Ti)₂AlH₄Cl solutions has led us to suggest a mechanism for the formation of the catalytically active species upon interaction of this compound with olefins and solvating solvents.     

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.     

Synthesis and structure of (boratabenzene)rhodacarborane (η-7,8-C2B9H11)Rh(η-C5H5BMe)

The bromide complex [(η-C₅H₅BMe)RhBr₂]₂ (1) was synthesized by the reaction of the cyclooctadiene derivative (η-C₅H₅BMe)Rh(1,5-C₈H₁₂) with Br₂. The reaction of compound 1 with Tl[Tl(η-7,8-C₂B₉H₁₁)] gave (boratabenzene)rhodacarborane (η-7,8-C₂B₉H₁₁)Rh-(η-C₅H₅BMe) (2). The structure of compound 2 was determined by X-ray diffraction     

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.     

Aromaticity, optical properties and zero field splitting of homo- and hetero-bimetallic (C8H8)M(μ2-,η8═C8H8)M(C8H8) where M = Ti, Zr, Th Complexes

This work presents a relativistic calculation of electron delocalization, optical properties, and zero field splitting in a group of molecules with the structure (C(8)H(8))M(μ(2)-,η(8)═C(8)H(8))M(C(8)H(8)), where M = Ti, Zr and Th. Additionally we also studied the heterobimetallic combinations (Ti-Th and Zr-Th). The molecular properties are discussed based on their electronic structure and the influence of the electron mobility in metal-metal communication. Nucleus independent chemical shift (NICS) was determined via the gauge-including-atomic-orbital (GIAO) method with the OPBE functional. The time-dependent density functional theory (TDDFT) was employed to calculate excitation energies, and the electronic transitions over 500 nm are presented with the objective to analyze the transition metal role as an antenna effect in the absorption band in the near-IR region. Finally the ZFS was calculated using Pederson-Khana and coupled perturbed DFT approaches implemented in the ORCA code. The contributions to spin-spin coupling (SS) and spin-orbit coupling (SOC) were analyzed, and the spin-density over the metal centers is discussed employing our scheme of metal-metal communication. Our aim is to determine the influence of the electronic structure over the optical and magnetic properties in a group of model compounds to understand the transition metals effect over these properties.     

Synthesis and Anti-inflammatory Action of （η-C5H5 ）2Ti（ Sal）2 and （η-C5H5 ）2Ti（Clo）2

IntroductionSince K pf[1]discovered that dicyclopenta die-nyltitanium dichloride possesses antitumour action in1979,a large number of cyclopentadienyltitanium com-plexes with different substituents have been synthe-sized[2,3].The experimental data reveal …     

The crystal and molecular structure of bis(η5-trimethylsilylcyclopentadienyl)titanium(IV) dichloride,Ti(η5-C5H4SiMe 3)2Cl2

Summary The crystal and molecular structure of the titanocene complex Ti(⁵-C₅H₄SiMe ₃)₂Cl₂ has been determined by X-ray diffraction studies. The compound crystallizes in the triclinic crystal system [a=6.747(8),b=12.815(2),c=12.928(4) Å and =67.16(2), =82.29(5), =74.83(4)°] in the space group with 2 formula units in the unit cell. The coordination about the titanium atom formed by the two chlorine atoms and the centroids of the cyclopentadienyl rings is that of a distorted tetrahedron. The Cl-Ti-Cl angle is 91.63° while the (centroid)-Ti-(centroid) angle is 131.02°.

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Die Kristall- und Molekülstruktur von Bis(⁵-trimethylsilylcyclopentadienyl)titan(IV)dichlorid, Ti(⁵-C₅H₄SiMe ₃)₂Cl₂

Zusammenfassung Die Kristall- und Molekülstruktur des Titanocen-Komplexes Ti(⁵-C₅H₄SiMe ₃)₂Cl₂ wurde durch eine Röntgenstrukturanalyse bestimmt. Die Verbindung kristallisiert im triklinen Kristallsystem [a=6.747(8),b=12.815(2),c=12.928(4) Å und =67.16(2), =82.29(5), =74.83(4)°] in der Raumgruppe mit 2 Formeleinheiten pro Elementarzelle. Das Titanatom ist von zwei Chloratomen und den Centroiden der Cyclopentadienylringe umgeben, wobei die Koordination des Titanatoms verzerrt tetraedrisch ist. Die Winkel Cl-Ti-Cl und (Centroid)-Ti-(Centroid) betragen 91.63° bzw. 131.02°.

     

Substitution and insertion reactions of (η5-C5H5)Cr(CO)3C2H5

The complex (η⁵-C₅H₅)Cr(CO)₃Cp42 H₅ has been made and its reactions with σ donor ligands L (L = (MeO)₃P and (EtO)₃P) and with SO₂ studied. The alkyl phosphites give compounds of the composition (η⁵-C₅H₅)Cr(CO)₂LC₂H₅, and sulfur dioxide gives the corresponding S-sulfinato (η⁵-C₅H₅)Cr(CO)₃SO₂C₂H₅.     

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.     

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.