Crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand.

Torsten Beweries,Anke Spannenberg,Monty Kessler,Christian Godemann

doi:10.1107/s2056989016018363

Torsten Beweries, Anke Spannenberg + Show 2 more

Open Access

https://doi.org/10.1107/s2056989016018363

Copy DOI

Abstract

The crystal structures of two ansa-titanocene tri-fluoro-methane-sulfonate complexes bearing the Me2Si(C5Me4)2 ligand are reported, namely [di-methylbis-(η5-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κ2O,O')titanium(III) toluene monosolvate, [Ti(CF3O3S)(C20H30Si)]·C7H8, 1, and chlorido-[di-methyl-bis-(η5-tetra-methyl-cyclo-penta-dien-yl)silane](tri-fluoro-methane-sulfonato-κO)titanium(IV), [Ti(CF3O3S)(C20H30Si)Cl], 2. Both complexes display a bent metallocene unit, the metal atom being coordinated in a distorted tetra-hedral geometry, with the tri-fluoro-methane-sulfonate anion acting as a bidentate or monodentate ligand in 1 and 2, respectively. In 1, weak π-π stacking inter-actions involving the toluene solvent mol-ecules [centroid-to-centroid distance = 3.9491 (11) Å] are observed.

Highlights

The crystal structures of two ansa-titanocene trifluoromethanesulfonate complexes bearing the Me2Si(C5Me4)2 ligand are reported, namely [dimethylbis(5-tetramethylcyclopentadienyl)silane](trifluoromethanesulfonato-2O,O0 )titanium(III) toluene monosolvate, [Ti(CF3O3S)(C20H30Si)]C7H8, 1, and chlorido[dimethylbis(5-tetramethylcyclopentadienyl)silane](trifluoromethanesulfonato-O)titanium(IV), [Ti(CF3O3S)(C20H30Si)Cl], 2. Both complexes display a bent metallocene unit, the metal atom being coordinated in a distorted tetrahedral geometry, with the trifluoromethanesulfonate anion acting as a bidentate or monodentate ligand in 1 and 2, respectively
Titanocene trifluoromethanesulfonate complexes have been investigated by our group as model complexes for overall water splitting (Kessler et al, 2011; Hollmann et al, 2013; Godemann et al, 2015)
We have found that the nature of the cyclopentadienyl ligands strongly influences the outcome of the reaction

Summary

Chemical context

Titanocene trifluoromethanesulfonate complexes have been investigated by our group as model complexes for overall water splitting (Kessler et al, 2011; Hollmann et al, 2013; Godemann et al, 2015). Reaction of the silanediylbridged complex Me4Si2(C5Me4)2Ti(OTf) (B) with water was found to yield the TiIII compound [Me4Si2(C5Me4)Ti(H2O)2](OTf), which could be oxidized with TEMPO to give a TiIV species [Me4Si2(C5Me4)2Ti(H2O)(OH)](OTf). Photolysis of the latter results in a photoreduction and elimination of the OH ligand to give a TiIII trifluoromethanesulfonate complex. The crystal structure of complex 2 shows the trifluoromethanesulfonate ligand in a 1-binding mode with a Ti1—O1 distance of 2.0605 (11) Å, which is slightly shorter compared to the bis(pentamethylcyclopentadienyl) compound Cp*2Ti(Cl)(OTf) [2.097 (4) Å; Beckhaus et al, 1994]. Ti1—Cl1 bond length [2.3255 (5) Å] is in the expected range for a TiIV–chloride bond and is the same as found for the above Cp* complex [2.328 (2) Å]

Structural commentary

Synthesis and crystallization

Refinement