skip to main content

Title: Synthesis and characterization of a tert- butyl ester-substituted titanocene dichloride: t-BuOOC Cp 2 TiCl 2
Bis[η 5 -( tert -butoxycarbonyl)cyclopentadienyl]dichloridotitanium(IV), [Ti(C 10 H 13 O 2 ) 2 Cl 2 ], was synthesized from LiCp COO t -Bu using TiCl 4 , and was characterized by single-crystal X-ray diffraction and 1 H NMR spectroscopy. The distorted tetrahedral geometry about the central titanium atom is relatively unchanged compared to Cp 2 TiCl 2 . The complex exhibits elongation of the titanium–cyclopentadienyl centroid distances [2.074 (3) and 2.070 (3) Å] and a contraction of the titanium–chlorine bond lengths [2.3222 (10) Å and 2.3423 (10) Å] relative to Cp 2 TiCl 2 . The dihedral angle formed by the planes of the Cp rings [52.56 (13)°] is smaller than seen in Cp 2 TiCl 2 . Both ester groups extend from the same side of the Cp rings, and occur on the same side of the complex as the chlorido ligands. The complex may serve as a convenient synthon for titanocene complexes with carboxylate anchoring groups for binding to metal oxide substrates.  more » « less
Award ID(s):
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Acta Crystallographica Section E Crystallographic Communications
Page Range / eLocation ID:
1562 to 1565
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. null (Ed.)
    The green compound poly[(tetrahydrofuran)tris[μ-η 5 :η 5 -1-(trimethylsilyl)cyclopentadienyl]caesium(I)ytterbium(II)], [CsYb(C 8 H 13 Si) 3 (C 4 H 8 O)] n or [(THF)Cs(μ-η 5 :η 5 -Cp′) 3 Yb II ] n was synthesized by reduction of a red THF solution of (C 5 H 4 SiMe 3 ) 3 Yb III with excess Cs metal and identified by X-ray diffraction. The compound crystallizes as a two-dimensional array of hexagons with alternating Cs I and Yb II ions at the vertices and cyclopentadienyl groups bridging each edge. This, based off the six-electron cyclopentadienyl rings occupying three coordination positions, gives a formally nine-coordinate tris(cyclopentadienyl) coordination environment to Yb and the Cs is ten-coordinate due to the three cyclopentadienyl rings and a coordinated molecule of THF. The complex comprises layers of Cs 3 Yb 3 hexagons with THF ligands and Me 3 Si groups in between the layers. The Yb—C metrical parameters are consistent with a 4 f 14 Yb II electron configuration. 
    more » « less
  2. The synthesis of previously unknown bis(cyclopentadienyl) complexes of the first transition metal, i.e., Sc(II) scandocene complexes, has been investigated using C5H2(tBu)3 (Cpttt), C5Me5 (Cp*), and C5H3(SiMe3)2 (Cp″) ligands. Cpttt 2ScI, 1, formed from ScI3 and KCpttt, can be reduced with potassium graphite (KC8) in hexanes to generate dark-red crystals of the first crystallographically characterizable bis(cyclopentadienyl) scandium(II) complex, Cpttt 2Sc, 2. Complex 2 has a 170.6° (ring centroid)-Sc-(ring centroid) angle and exhibits an eight-line EPR spectrum characteristic of Sc(II) with Aiso = 82.6 MHz (29.6 G). It sublimes at 200 °C at 10−4 Torr and has a melting point of 268−271 °C. Reductions of Cp*2ScI and Cp″2ScI under analogous conditions in hexanes did not provide new Sc(II) complexes, and reduction of Cp*2ScI in benzene formed the Sc(III) phenyl complex, Cp*2Sc(C6H5), 3, by C−H bond activation. However, in Et2O and toluene, reduction of Cp*2ScI at −78 °C gives a dark-red solution, 4, which displays an eight-line EPR pattern like that of 1, but it did not provide thermally stable crystals. Reduction of Cp″2ScI, in THF or Et2O at −35 °C in the presence of 2.2.2-cryptand, yields the green Sc(II) metallocene iodide complex, [K(crypt)][Cp″2ScI], 5, which was identified by X-ray crystallography and EPR spectroscopy and is thermally unstable. The analogous reaction of Cp*2ScI with KC8 and 18-crown-6 in Et2O gave the ligand redistribution product, [Cp*2Sc(18- crown-6-κ2O,O′)][Cp*2ScI2], 6, as the only crystalline product. Density functional theory 
    more » « less
  3. Bis(benzene-1,2-diolato-κ 2 O , O ′)bis(dimethyl sulfoxide-κ O )titanium(IV), [Ti(C 6 H 4 O 2 ) 2 (C 2 H 6 OS) 2 ], crystallizes with two crystallographically independent molecules in the space group P 2 1 / c emulating orthorhombic Pbca symmetry (β = 90.0445 (9)°]. The two molecules are related by pseudo-glide symmetry, broken by modulation of each one catecholate and dimethyl sulfoxide (DMSO) ligand. Twinning by pseudomerohedry was observed [twin ratio 0.5499 (7):0.4401 (7)]. Complex 3 was obtained by heating of diprotonated titanium tris-catecholate precursor 2 H in DMSO, by formal displacement of a catechol molecule by two DMSO molecules. Complex 3 is just the second heteroleptic, mono-nuclear, neutral bis-catecholate complex with TiO 6 metal coordination, the only other one being its bis-DMF analogue 6 . The two molecules of 3 exhibit a distorted octahedral geometry. The geometry and distortions from ideal symmetry of 3 are discussed and compared to 6 and to cationic tris-catecholate titanium complexes. 
    more » « less
  4. null (Ed.)
    The title compounds, [Mo(C 5 H 5 )(COCH 3 )(C 6 H 12 N 3 P)(CO) 2 ], (1), and [Mo(C 5 H 5 )(COCH 3 )(C 9 H 16 N 3 O 2 P)(C 6 H 5 ) 2 ))(CO) 2 ], (2), have been prepared by phosphine-induced migratory insertion from [Mo(C 5 H 5 )(CO) 3 (CH 3 )]. The molecular structures of these complexes are quite similar, exhibiting a four-legged piano-stool geometry with trans -disposed carbonyl ligands. The extended structures of complexes (1) and (2) differ substantially. For complex (1), the molybdenum acetyl unit plays a dominant role in the organization of the extended structure, joining the molecules into centrosymmetrical dimers through C—H...O interactions with a cyclopentadienyl ligand of a neighboring molecule, and these dimers are linked into layers parallel to (100) by C—H...O interactions between the molybdenum acetyl and the cyclopentadienyl ligand of another neighbor. The extended structure of (2) is dominated by C—H...O interactions involving the carbonyl groups of the acetamide groups of the DAPTA ligand, which join the molecules into centrosymmetrical dimers and link them into chains along [010]. Additional C—H...O interactions between the molybdenum acetyl oxygen atom and an acetamide methyl group join the chains into layers parallel to (101). 
    more » « less
  5. Abstract

    Irradiation of Cp2TiCl2with green light leads to electronically excited [Cp2TiCl2]*. This complex constitutes an efficient photoredox catalyst for the reduction of epoxides and for 5‐exocyclizations of suitably unsaturated epoxides. To the best of our knowledge, our system is the first example of a molecular titanium photoredox catalyst.

    more » « less