ansa
‐Titanocene and ‐Zirconocene η
2
‐Alkyne Complexes ‐Synthesis, Spectral Characteristics, and X‐ray Crystal Structure
摘要:
AbstractThe reduction of the complex [(η5‐C5H4)‐ansa‐(η5‐C5H4)]TiCl2 with magnesium in the presence of Me3SiC2‐SiMe3 in THF at room temperature gives the ansa‐titanocone alkyne complex [(η5‐C5H4)‐ansa‐(η5‐C5H4)]Ti(η2‐Me3SiC2‐SiMe3) (ansa = Me2Si‐O‐SiMe2, 1). The similar pyridine‐stabilized zirconium complexes could be obtained by analogous reactions and addition of pyridine: [(η5‐C5H4)‐ansa‐(η5‐C5H4)]Zr(L)(η2‐Me3SiC2SiMe3) (ansa = Me2Si‐O‐SiMe2, L = pyridine: 2; ansa = SiMe2, L = pyridine: 3). All complexes were characterized by spectroscopic methods. An X‐ray structure determination of complex 3 was conducted, and the data were compared to those of the complexes rac‐(EB‐HI)Zr(L)(η2‐Me3SiC2SiMe3) [L = (S)‐(‐)‐nicotine: 6, EBHI = ethylenebis(tetrahydroindenyl)] and Cp2Zr(py)(Me3SiC2‐SiMe3).
Zirconocenophane dichlorides with di- and trisiloxane-bridged ring ligands: crystal structure of rac-[1,1,3,3-tetramethyldisiloxane-diyl-bis(3-tert-butyl-η5-cyclopentadienyl)zirconium(IV) dichloride]
摘要:
The three novel zirconocenophane dichlorides [{O(Me(2)SiC(5)H(4))(2)}ZrCl2] (3), [{O(Me(2)SiC(5)H(3)-(C4H9)-C-t)(2)}ZrCl2] (4) and [{Me(2)Si(OMe(2)SiC(5)H(4))(2)}ZrCl2](n) (5) have been prepared and characterized by H-1 NMR spectroscopy. According to a successful single-crystal X-ray study, 4 crystallizes from n-hexane as a racemic mixture with exclusively 1,3-disubstituted cyclopentadienyl ligands and Cl-2 centres oriented transoid to the O atoms. 4: monoclinic; space group P2(1)/c, a = 1167.7(2), b = 1590.2(2), c = 1491.3(3) pm; beta = 104.64(2)degrees; R = 0.061 (R(w) = 0.058). In solution (room temperature), all three complexes are fluxional; moreover the NMR spectrum of 4 displays the resonances of two isomers (25:1). According to a mass spectrometry study of 5, the B-2/E-coupled scan of the molecular ion M(+) (m/z = 494) indicates at least four ''parent'' fragments with 509 less than or equal to m/z less than or equal to 1275, suggesting here dinuclear or even trinuclear precursors.