Komplexe mit kohlenstoffsulfiden und -seleniden als liganden : X. Synthese und kristallstruktur von C5H5(PMe3)Co(μ-CS)2CoC5H5: Ein zweikernkomplex mit unsymmetrischen Co(CS)Co-brückenbindungen

The complex C₅H₅(PMe₃)Co(μ-CS)₂CoC₅H₅ (I) is formed by the reaction of C₅H₅Co(PMe₃)CS and CH₂I₂. The X-ray structure analysis shows an unsymmetrical non-planar Co₂C₂-skeleton with different Co---C bond lengths. The Co---Co distance is 239.2 pm. Compound I thus represents a new example of binuclear (18 + 16)-electron complexes in which the more electron-rich metal atom forms a donor bond to the more electron-poor counterpart. The reaction of I with ligands such as P(NMe₂)₃ does not lead to bridge cleavage indicating the stability of the Co(CS)₂Co-framework.     

Synthesis and crystal structures of (C8h8)Nd(C5H9C5H4) (THF)2 and [(C8H8)Gd(C5H9C4H4(THF)][(C8H8)GD(C5H9C5H4(THF)2]

LnCl₃ (Ln=Nd, Gd) reacts with C₅H₉C₅H₄Na (or K₂C₈H₈) in THF (C₅H₉C₅H₄ = cyclopentylcyclopentadienyl) in the ratio of 1 : to give (C₅H₉C₅H₄)LnCl₂(THF)_n (orC₈H₈)LnCl₂(THF)_n], which further reacts with K₂C₈H₈ (or C₅H₉C₅H₄Na) in THF to form the litle complexes. If Ln=Nd the complex (C₈H₈)Nd(C₅H₉C₅H₄)(THF)₂ (a) was obtained: when Ln=Gd the 1 : 1 complex [(C₈H₈)Gd(C_%H₉)(THF)][(C₈H₈)Gd(C₅H₉H₄)(THF)₂] (b) was obtained in crystalline form.

The crystal structure analysis shows that in (C₈H₈)Ln(C₅H₉C₅H₄)(THF)₂ (Ln=Nd or Gd), the Cyclopentylcyclopentadieny (η⁵), cyclooctatetraenyl (η⁸) and two oxygen atoms from THF are coordinated to Nd³⁺ (or Gd³⁺) with coordination number 10.

The centroid of the cyclopentadienyl ring (Cp′) in C₅H₉C₅H₄ group, cyclooctatetraenyl centroid (COTL) and two oxygens (THF) form a twisted tetrahedron around Nd³⁺ (or Gd³⁺). In (C₈H₈)Gd(C₅H₉C₅H₄)(THF), the cyclopentyl-cyclopentadienyl (η⁵), cyclooctatetraenyl (η⁸) and one oxygen atom are coordinated to Gd³⁺ with the coordination number of 9 and Cp′, COT and oxygen atom form a triangular plane around Gd³⁺, which is almost in the plane (dev. -0.0144 Å).     

Synthesis and characterization of (C5H9C9H6)2Yb(THF)2(II) (1) and [(C5H9C5H4)2Yb(THF)]2O2 (2), and ring-opening polymerization of lactones with 1

Reaction of YbI₂ with two equivalents of cyclopentylindenyl lithium (C₅H₉C₉H₆Li) affords ytterbium(II) substituted indenyl complex (C₅H₉C₉H₆)₂Yb(THF)₂ (1) which shows high activity to ring-opening polymerization (ROP) of lactones. The reaction between YbI₂ and cyclopentylcyclopentadienyl sodium (C₅H₉C₅H₄Na) gives complex [(C₅H₉C₅H₄)₂Yb(THF)]₂O₂ (2) in the presence of a trace amount of O₂, the molecular structure of which comprises two (C₅H₉C₅H₄)₂Yb(THF) bridged by an asymmetric O₂ unit. The O₂ unit and ytterbium atoms define a plane that contains a C_i symmetry center.     

Darstellung und Molekülstruktur des (μ-Alkylidenamido)titanocenkomplexes [(C5H5)2TiCl]2[μ-{N=C(CH2C6H5)C(CH2C6H5)=N}]

Reduction of (C₅H₅)₂TiCl₂ with Zn in presence of benzyl cyanide gives the (μ-alkyl-ideneamido)titanocene complex [(C₅H₅)₂TiCl]₂[μ-{N=C(CH₂C₆H₅)---C(CH₂C₆H₅)=N}] with C---C bond formation between two benzyl cyanide molecules.

X-ray structure investigation indicates a symmetrical structure. The C=N distances are smaller than usual, the Ti---N distances are very short, and the Ti---N---C angle differs only a little from 180°, which infers a heteroallene structure of the complex.     

Synthesis of metallocenes of zirconium, hafnium, manganese, iron, tin, lead and half-sandwich complexes of rhodium and iridium containing the ligands (η-C5R4CR′2PMe2), where R and R′ may be H or Me

The dimethylphosphino substituted cyclopentadienyl precursor compounds [M(C₅Me₄CH₂PMe₂)], where M=Li⁺ (1), Na⁺ (2), or K⁺ (3), and [Li(C₅H₄CR′₂PMe₂)], where R′₂=Me₂ (4), or (CH₂)₅ (5), [HC₅Me₄CH₂PMe₂H]X, where X⁻=Cl⁻ (6) or PF₆⁻ (7) and [HC₅Me₄CH₂PMe₂] (8), are described. They have been used to prepare new metallocene compounds, of which representative examples are [Fe(η-C₅R₄CR′₂PMe₂)₂], where R=Me, R′=H (9); R=H and R′₂=Me₂ (10), or (CH₂)₅ (11), [Fe(η-C₅H₄CMe₂PMe₃)₂]I₂ (12), [Fe{η-C₅Me₄CH₂P(O)Me₂}₂] (13), [Zr(η-C₅R₄CR′₂PMe₂)₂Cl₂], where R=H, R′=Me (14), or R=Me, R′=H (15), [Hf(η-C₅H₄CMe₂PMe₂)₂]Cl₂] (16), [Zr(η-C₅H₄CMe₂PMe₂)₂Me₂] (17), {[Zr(η-C₅Me₄CH₂PMe₂)₂]Cl}{(C₆F₅)₃BClB(C₆F₅)₃} (18), [Zr{(η-C₅Me₄CH₂PMe₂)₂Cl₂}PtI₂] (19), [Mn(η-C₅Me₄CH₂PMe₂)₂] (20), [Mn{(η-C₅Me₄CH₂PMe₂B(C₆F₅)₃}₂] (21), [Pb(η-C₅H₄CMe₂PMe₂)₂] (23), [Sn(η-C₅H₄CMe₂PMe₂)₂] (24), [Pb{η-C₅H₄CMe₂PMe₂B(C₆F₅)₃}₂] (25), [Pb(η-C₅H₄CMe₂PMe₂)₂PtI₂] (26), [Rh(η-C₅Me₄CH₂PMe₂)(C₂H₄)] 29, [M(η,κP-C₅Me₄CH₂PMe₂)I₂], where M=Rh (30), or Ir, (31).     

Crystal structure of the 1/ 1 molecular complex of 5,5′,12,12′-bis(triseleno)bis(naphthacene-6,11-quinone) with benzonitrile, (C18H8Se3O2)2(C6H5CN)

The structure of the (C₁₈H₈Se₃O₂)₂(C₆H₅CN) molecular complex isolated from the TSeT + HgI₂ reaction in benzonitrile has been determined. The -Se-Se-Se- fragment has been found to have Se---Se bond lengths equal to 2.348(3) and 2.350(4) Å.     

SYNTHESIS of(η~5-C_9H_7)Ln(η~8-C_8H_8)·2THF AND CRYSTAL STRUCTURE OF(η~5-C_9H_7)Pr(η~8-C_8H_8)·2THF

The reaction of LnCl_3 with K _9H_7(C_9H_7=indenyl)andK_2C_8H_8(C_8H_8=cyclooctatetraene)in tetrahydrofuran(THF)give thecorresponding complexes(η~5-C_9H_7)Ln(η~8-C_8H_8)·2THF.The synthesis of(η~5-C_9H_7)Ln(η~8-C_8H_8)·2THF(Ln=Pr,Nd)and crystal structure of(η~5-C_9H_7)Pr(η~8-C_8H_8)·2THF are described.     

Homochiral cyclopentane-based C1-symmetric P,P ligands C5H8(PPh2)(PR2) from C2-symmetric C5H8(PCl2)2

Treatment of 1,2-trans-C₅H₈(PCl₂)₂ with 1,2-C₂H₄(NHPr-i)₂ gave the C₂-symmetric perhydro-1,6,2,5-diazaphosphocine C₅H₈{P(Cl)N(Pr-i)CH₂}₂-cyclo, which produced dissymmetric C₅H₈(PPh₂){P[N(Pr-i)CH₂]₂-cyclo} on further reaction with PhMgBr. Cleavage of the P---N bonds with gaseous HCl afforded C₅H₈(PPh₂)(PCl₂), which was converted to C₅H₈(PPh₂){P(OPh)₂}₂ by reaction with phenol. All chiral P,P derivatives were obtained as racemates as well as resolved (1R,2R)- and (1S,2S)-enantiomers.     

Dimethylchalkogenide als liganden in kationischen cyclopentadienyleisen-bis(phosphin)-komplexen: synthese, reaktivität und kristallstruktur von [C5H5Fe(P(OCH3)3)2(S(CH3)2)]PF6

Thermal displacement of coordinated nitriles RCN (R = CH₃, C₂H₅ or n-C₃H₇) in [C₅H₅Fe(L₂)(NCR)]X complexes (L₂ = P(OCH₃)₃)₂, (P(OC₆H₅)₃)₂ or (C₆H₅)₂PC₂H₄P(C₆H₅)₂ (DPPE)) by E(CH₃)₂ affords high yields of [C₅H₅Fe(L₂)(E(CH₃)₂)]X compounds (E = S, Se and Te; X = BF₄ or PF₆). Spectroscopic data and ligand displacement reactions are presented and discussed together with related observations on [C₅H₅Fe(CO)₂(E(CH₃)₂)]BF₄ compounds. The molecular structure of [C₅H₅Fe(P(OCH₃)₃)₂(S(CH₃)₂)]PF₆ was determined by a single-crystal X-ray diffraction study: monoclinic, space group P2₁/n-C⁵_2h (No. 14) with a = 8.4064(12), b = 11.183(2), c = 50.726(8) Å, β = 90.672(13)° and Z = 8 molecules per unit cell. The coordination sphere of the iron atom is pseudo-tetrahedral with an Fe---S bond distance of 2.238 Å.     

Synthese et etude des complexes [C5H4(CH2)3C5H4]Ti(C5H5)2 presentant un pont entre deux ligands cyclopentadienyles

The complex (di-η⁵-C₅H₄CH₂CH₂CH₂C₅H₄)Ti(η¹-C₅H₅)₂ (I) can be obtained unambiguously starting from the corresponding bridged titanocene dichloride. Attempts to synthesize the isomeric compounds (η⁵-C₅H₅)₂ Ti(di-η¹-C₅H₄-CH₂CH₂CH₂C₅H₄) (I′) by the action of a convenient bridged dianion on (C₅H₅)₂ TiCl₂ afford several compounds, one of them is the complex I. The possibility of interconversion of these complexes by a fluctional process is discussed.     

Ab initio computation of the potential energy surfaces of the water·hydrocarbon complexes H2O·C2H2, H2O·C2H4 and H2O·CH4: minimum energy structures, vibrational frequencies and hydrogen bond energies

On the basis of ab initio MP2/6–31 + + G(2d,2p) calculations, we examined the potential energy surfaces of the water·hydrocarbon complexes H₂O·CH₄, H₂O·C₂H₂ and H₂O·C₂H₂ to locate all the minimum energy structures and estimate the hydrogen bond energies and vibrational frequencies associated with the C(spⁿ)---H·O and the O---H·C(spⁿ) bonds (n = 1−3). Our calculations show that H₂O·C₂H₂, H₂O·C₂H₄ and H₂O·CH₄ have two minimum energy structures (i.e., the C---H·O and O---H·C hydrogen bond forms), but H₂O·C₂H₄ has only one when the vibrational motion is taken into account, the O---H·C hydrogen bond form. We have also computed the barrier for the interconversion from one minimum to the other. The fully optimized geometries of H₂O·CH₄, H₂O·C₂H₄ and H₂O·C₂H₂ as well as the vibrational shifts of the C---H stretching frequencies in their C---H·O hydrogen-bonded forms are in good agreement with the available experimental data. The calculated hydrogen bond energies show that the C(spⁿ---H·O bond strengths decrease in the order C(sp)---H·O>C(sp²)---H·O>C(sp³)---O>C(sp³---H·O, which is also consistent with the available experimental data.     

Stability of the silicon-ruthenium bond in the presence of a strong nucleophile. Phase sensitive H NMR COSY and crystal structure of Ru(CO)2(NH2CH2C6H5)2(Si(C6H5)(CH3)2)I

The ruthenium(II) complex Ru(CO)₂(NH₂(NH₂CH₂C₆H₅)₂(Si(C₆H₅)(CH₃)₂)I has been prepared by the reaction of Ru(CO)₄(Si(C₆H₅)(CH₃)₂)I with benzylamine. Two-dimensional homonuclear ¹H NMR experiments examine the scalar coupling of the enantiotopic amino and methylene protons of the benzylamine ligand. X-ray analysis of Ru(CO)₂(NH₂CH₂C₆H₅)₂(Si(C₆H₅)(CH₃)₂)I·1/3C₅H₁₂ (triclinic; P ; a = 14.266(4), b = 15.748(5), c = 20.082(6) Å; = 94.38(3), β = 96.30(2), γ = 101.52(2)°) indicates three crystallographically unique complexes form a clathrate with a pentane guest.     

Synthesis and crystal structure of the complex [MoW(OEt)(μ-CH2){μ-C(C6H4Me-4)C(Me)O}(η-C7H7)(η-C2B9H10Me)]

The complex [MoW(μ-CC₆H₄Me-4)(CO)₂(η⁷-C₇H₇)(η⁵-C₂B₉H₁₀Me)] reacts with diazomethane in Et₂O containing EtOH to afford the dimetal compound [MoW(OEt)(μ-CH₂){μ-C(C₆H₄Me-4)C(Me)O}(η⁷-C₇H₇)(η⁵-C₂B₉H₁₀Me)]. The structure of this product was established by X-ray diffraction. The Mo---W bond [2.778(4) Å] is bridged by a CH₂ group [μ-C---Mo 2.14(3), μ-C---W 2.02(3) Å] and by a C(C₆H₄Me-4)C(Me)O fragment [Mo---O 2.11(3), W---O 2.18(2), Mo---C(C₆H₄Me-4) 2.41(3), W---C(C₆H₄Me-4) 2.09(3), Mo---C(Me) 2.26(3) Å]. The molybdenum atom is η⁷-coordinated by the C₇H₇ ring and the tungsten atom is η⁵-coordinated by the open pentagonal face of the nido-icosahedral C₂B₉H₁₀Me cage. The tungsten atom also carries a terminally bound OEt group [W---O 1.88(3) Å]. The ¹H and ¹³C-{¹H} NMR data for the dimetal compound are reported and discussed.     

Velocity map imaging of the photolysis of n-C4H9Br in UV region

Using velocity map ion imaging technique, the photodissociation of n-C₄H₉Br in the wavelength range 231–267 nm was studied. The results and our ab initio calculations indicated that the absorption of n-C₄H₉Br in the investigated region originated from the excitations to the lowest three repulsive states, as assigned as 1A″, 2A′ and 3A′ in C_s symmetry. Dissociations occurred on the PES surfaces of the three states, terminating in C₄H₉+Br (²P_3/2) or C₄H₉ + Br^* (²P_1/2) as two channels, and being impacted by an avoided crossing between the PES surfaces of the 2A′ and 3A′ states. The transition dipole to the 1A″ state was perpendicular to the symmetry plane, so perpendicular to the C–Br bond. The transitions to the 3A′ state was polarized parallel to the symmetry plane, and also parallel to the C–Br bond. While the transition dipole to the 2A′ state was in the symmetry plane, but formed an angle of about 53.1° with the C–Br bond. We have also determined the avoided crossing probabilities, which affected the relative fractions of the individual pathways, for the photolysis of n-C₄H₉Br near 234 nm and 267 nm.     

Reaction of [(C6H6)RuCl2]2 with 7,8-benzoquinoline and 8-hydroxyquinoline

The reaction of [(C₆H₆)RuCl₂]₂ with 7,8-benzoquinoline and 8-hydroxyquinoline in methanol were performed. The obtained complexes have been studied by IR, UV–VIS, ¹H and ¹³C NMR spectroscopy and X-ray crystallography. In the reaction with 8-hydroxyquinoline the arene ruthenium(II) complex oxidized to Ru(III). The electronic spectra of the obtained compounds have been calculated using the TDDFT method. Magnetic properties of [Ru(C₉H₆NO)₃] · CH₃OH complex suggest the antiferromagnetic coupling of the ruthenium centers in the crystal lattice. EPR spectrum of [Ru(C₉H₆NO)₃] · CH₃OH compound indicates single isotropic line only characteristic for Ru³⁺ with spin equal to 1/2.     

Synthesis and structure of ansa-cyclopentadienyl pyrrolyl titanium complexes: [(η-C5H4)CH2(2-C4H3N)]Ti(NMe2)2 and [1,3-{CH2(2-C4H3N)}2(η-C5H3)]Ti(NMe2)

Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C₅H₅)CH₂(2-C₄H₃NH) (2) with Ti(NMe₂)₄ affords bis(dimethylamido)titanium complex [(η⁵-C₅H₄)CH₂(2-C₄H₃N)]Ti(NMe₂)₂ (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH₂(2-C₄H₃NH)}₂C₅H₄ (4), undergoes an analogous reaction with Ti(NMe₂)₄ to give [1,3-{CH₂(2-C₄H₃N)}₂(η⁵-C₅H₃)]Ti(NMe₂) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies.     

An ab initio and matrix isolation infrared study of the 1:1 C2H2–CHCl3 adduct

The details of weak C–Hπ interactions that control several inter and intramolecular structures have been studied experimentally and theoretically for the 1:1 C₂H₂–CHCl₃ adduct. The adduct was generated by depositing acetylene and chloroform in an argon matrix and a 1:1 complex of these species was identified using infrared spectroscopy. Formation of the adduct was evidenced by shifts in the vibrational frequencies compared to C₂H₂ and CHCl₃ species. The molecular structure, vibrational frequencies and stabilization energies of the complex were predicted at the MP2/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels. Both the computational and experimental data indicate that the C₂H₂–CHCl₃ complex has a weak hydrogen bond involving a C–Hπ interaction, where the C₂H₂ acts as a proton acceptor and the CHCl₃ as the proton donor. In addition, there also appears to be a secondary interaction between one of the chlorine atoms of CHCl₃ and a hydrogen in C₂H₂. The combination of the C–Hπ interaction and the secondary ClH interaction determines the structure and the energetics of the C₂H₂–CHCl₃ complex. In addition to the vibrational assignments for the C₂H₂–CHCl₃ complex we have also observed and assigned features owing to the proton accepting C₂H₂ submolecule in the acetylene dimer.     

Darstellung von metallkomplexen des thio- und selenoacetaldehyds sowie die kristallstruktur von C5H5Rh(η-CH3CHSe)P(i-Pr)3

The compounds C₅H₅Co(η²-CH₃CHS)PMe₃ (I) and C₅H₅Co(η²-CH₃CHSe)PMe₃ (II) are prepared from C₅H₅Co(CO)PMe₃, CH₃CHBr₂ and NaSH or NaSeH, respectively. The synthesis of the corresponding rhodium complexes C₅H₅Rh(η²-CH₃CHS)P(i-Pr)₃ (VI) and C₅H₅Rh(η²-CH₃CHSe)P(i-Pr)₃ (VII) has been achieved through hydrogenation of C₅H₅Rh(η²-EC=CH₂)P(i-Pr)₃ (E = S, Se), using RhCl(PPh₃)₃ as a catalyst. The crystal structure of VII has been determined.     

Organopolysilane oligomers bearing transition-metal moieties: Synthesis, reactivities and molecular structure of [η-Me3SiMe2SiC5H4(CO)Fe(CO)2Fe(CO)-η-C5H4SiMe2SiME3]

Reaction of Me₃SiMe₂SiC₅H₅ (4), prepared from Me₃SiMe₂SiCl and C₅H₅Na, with Fe(CO)₅ in refluxing xylene afforded the title compound (3). The silicon-silicon bond in 3 is exceptionally stable in refluxing xylene and also in succeeding reactions to prepare a series of its derivatives. Thus, 3 reacted with I₂ in either chloroform or benzene, giving [η⁵-Me₃SiMe₂SiC₅H₄Fe(CO)₂I] (6). Compound 3 was reduced by sodium amalgam and reacted subsequently with CH₃I, PhCH₂Cl, CH₃COCl, PhCOCl, Cy₃SnCl (Cy = cyclohexyl) and Ph₃SnCl, producing [η⁵-Me₃SiMe₂SiC₅H₄Fe(CO)₂R][7 : R = CH₃ (a), PhCH₂ (b), CH₃CO (c), PhCO (d), Cy₃Sn (e) and Ph₃Sn (f), respectively]. The molecular structure of 3 has been determined by X-ray diffraction crystallography. It was found that 3 has a trans-configuration with a symmetrical centre located at the middle of the Fe---Fe bond. It is abnormal that the conformation of the disilane part around the Si---Si bond is almost eclipsed rather than staggered.     

Preparation and study of cyclic polynuclear ferrocenes derived from (C6H5)2PCH2CH2Si(CH3)2C5H4Li as a bridging ligand

The synthesis of the potential bridging ligand (C₆H₅)₂PCH₂CH₂Si(CH₃)₂C₅H₄ (3) is described. The ferrocene (6 derived from 3 has been found to form macrocyclic complexes with metal fragments NiCl₂, NiBr₂, and Co₂(CO)₆. Although monomeric, bimetallic products might have been expected based upon the reduced steric demands of ligand 3 relative to an analogous ligand, (C₆H₅)₂PCH₂Si(CH)₃)₂C₅H₄ (1), it appears that the increased flexibility in 3 is the overriding factor leading to a preference for inter- rather than intramolecular coordination of the second phosphine function in 6.