Bonding in Complexes of Bis(pentalene)dititanium, Ti2(C8H6)2

被引:17
作者
Kilpatrick, Alexander F. R. [1 ]
Green, Jennifer C. [2 ]
Cloke, F. Geoffrey N. [1 ]
机构
[1] Univ Sussex, Sch Life Sci, Dept Chem, Brighton BN1 9QJ, E Sussex, England
[2] Univ Oxford, Dept Chem, Inorgan Chem Lab, Oxford OX1 3QR, England
基金
欧洲研究理事会;
关键词
ELECTRON-PARAMAGNETIC-RESONANCE; DOUBLE-SANDWICH COMPLEX; TRANSITION-METALS; PENTALENE; APPROXIMATION; METALLOCENES; TITANOCENE; CHEMISTRY; ENERGIES; ANIONS;
D O I
10.1021/acs.organomet.5b00363
中图分类号
O61 [无机化学];
学科分类号
070301 ; 081704 ;
摘要
Bonding in the bis(pentalene)dititanium "double-sandwich" species Ti(2)Pn(2) (Pn = C8H6) and its interaction with other fragments have been investigated by density functional calculations and fragment analysis. Ti(2)Pn(2) with C-2v symmetry has two metal-metal bonds and a low-lying metal-based empty orbital, all three frontier orbitals having a(1) symmetry. The latter may be regarded as being derived by symmetric combinations of the classic three frontier orbitals of two bent bis(cyclopentadienyl) metal fragments. Electro-chemical studies on Ti(2)Pn(2)(dagger) (Pn(dagger) =1,4-{(SiPr3)-Pr-i}(2)C8H4) revealed a one-electron oxidation, and the formally mixed-valence Ti(II)-Ti(III) cationic complex [Ti(2)Pn(2)(dagger)] [B(C6F5)(4)] has been structurally characterized. Theory indicates an S = 1/2 ground-state electronic configuration for the latter, which was confirmed by EPR spectroscopy and SQUID magnetometry. Carbon dioxide binds symmetrically to Ti(2)Pn(2), preserving the C-2v symmetry, as does carbon disulfide. The dominant interaction in Ti(2)Pn(2)CO(2) is sigma donation into the LUMO of bent CO2, and donation from the O atoms to Ti(2)Pn(2) is minimal, whereas in Ti(2)Pn(2)CS(2) there is significant interaction with the S atoms. The bridging O atom in the mono(oxo) species Ti(2)Pn(2)O, however, employs all three O 2p orbitals in binding and competes strongly with Pn, leading to weaker binding of the carbocyclic ligand, and the sulfur analogue Ti(2)Pn(2)S behaves similarly. Ti(2)Pn(2) is also capable of binding one, two, or three molecules of carbon monoxide. The bonding demands of a single CO molecule are incompatible with symmetric binding, and an asymmetric structure is found. The dicarbonyl adduct Ti(2)Pn(2)(CO)(2) has C-5 symmetry with the Ti2Pn2 unit acting as two MCp2 fragments. Synthetic studies showed that in the presence of excess CO the tricarbonyl complex Ti(2)Pn(2)(dagger)(CO)(3) is formed, which optimizes to an asymmetric structure with one semibridging and two terminal CO ligands. Low-temperature C-13 NMR spectroscopy revealed a rapid dynamic exchange between the two bound CO sites and free CO.
引用
收藏
页码:4830 / 4843
页数:14
相关论文
共 49 条
  • [1] Albright TA, 2013, ORBITAL INTERACTIONS IN CHEMISTRY, 2ND EDITION, P1, DOI 10.1002/9781118558409
  • [2] [Anonymous], 2006, AMST DENS FUNCT ADF
  • [3] [Anonymous], 2011, CRYSALISPRO VERS 1 1
  • [4] Homoleptic Permethylpentalene Complexes: "Double Metallocenes" of the First-Row Transition Metals
    Ashley, Andrew E.
    Cooper, Robert T.
    Wildgoose, Gregory G.
    Green, Jennifer C.
    O'Hare, Dermot
    [J]. JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2008, 130 (46) : 15662 - 15677
  • [5] Diamagnetic corrections and Pascal's constants
    Bain, Gordon A.
    Berry, John F.
    [J]. JOURNAL OF CHEMICAL EDUCATION, 2008, 85 (04) : 532 - 536
  • [6] A Dichromium(II) BiS(η8-pentalene) double-sandwich complex with a spin equilibrium:: Synthetic, structural, magnetic, and theoretical studies
    Balazs, Gabor
    Cloke, F. Geoffrey N.
    Gagliardi, Laura
    Green, Jennifer C.
    Harrison, Andrew
    Hitchcock, Peter B.
    Shahi, Abdul Reharnan Moughal
    Summerscales, Owen T.
    [J]. ORGANOMETALLICS, 2008, 27 (09) : 2013 - 2020
  • [7] Mn2 bis(pentalene):: a mixed-spin bimetallic with two extremes of bonding within the same molecule
    Balazs, Gabor
    Cloke, F. Geoffrey N.
    Harrison, Andrew
    Hitchcock, Peter B.
    Green, Jennifer
    Summerscales, Owen T.
    [J]. CHEMICAL COMMUNICATIONS, 2007, (08) : 873 - 875
  • [8] DENSITY-FUNCTIONAL EXCHANGE-ENERGY APPROXIMATION WITH CORRECT ASYMPTOTIC-BEHAVIOR
    BECKE, AD
    [J]. PHYSICAL REVIEW A, 1988, 38 (06): : 3098 - 3100
  • [9] The versatility of pentalene coordination to transition metals:: A density functional theory investigation
    Bendjaballah, S
    Kahlal, S
    Costuas, K
    Bévillon, E
    Saillard, JY
    [J]. CHEMISTRY-A EUROPEAN JOURNAL, 2006, 12 (07) : 2048 - 2065
  • [10] AN EMPIRICAL CORRECTION FOR ABSORPTION ANISOTROPY
    BLESSING, RH
    [J]. ACTA CRYSTALLOGRAPHICA SECTION A, 1995, 51 : 33 - 38