Crystal structures of twoansa-titanocene trifluoromethanesulfonate complexes bearing the Me2Si(C5Me4)2ligand

The crystal structures of twoansa-titanocene trifluoromethanesulfonate complexes bearing the Me2Si(C5Me4)2ligand are reported, namely [dimethylbis(η5-tetramethylcyclopentadienyl)silane](trifluoromethanesulfonato-κ2O,O′)titanium(III) toluene monosolvate, [Ti(CF3O3S)(C20H30Si)]·C7H8,1, and chlorido[dimethylbis(η5-tetramethylcyclopentadienyl)silane](trifluoromethanesulfonato-κO)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 in1and2, respectively. In1, weak π–π stacking interactions involving the toluene solvent molecules [centroid-to-centroid distance = 3.9491 (11) Å] are observed.

A Model of a Closed Cycle of Water Splitting Using ansa-Titanocene(III/IV) Triflate Complexes

A series of ansa-titanocene triflate complexes are described as model compounds for the elementary steps of light-driven overall water splitting. Titanocene(III) triflate complexes are readily obtained by reaction of a titanocene source with Yb(OTf)3. Subsequent reactions with water and with/without TEMPO as hydrogen scavenger are studied. The as-obtained titanocene(IV) compounds can be photoreduced to give titanocene(III) triflate complexes, which can undergo further hydrolysis to form a closed catalytic cycle of water splitting. No further degradation of the photoreduced species was observed because of the presence of the OTf group. The stability of the system was evaluated in an experiment with high concentrations of water and TEMPO. X-ray crystallography on all titanocene complexes, EPR and NMR spectroscopy, and DFT were used to support our observations.

Crystal structure of 1-hydroxy-2,2,6,6-tetramethylpiperidin-1-ium trifluoromethanesulfonate

In the cation of the title salt, C9H20NO+·CF3O3S−, the six-membered heterocyclic ring displays a chair conformation. In the crystal, centrosymmetric pairs of cations and anions are linked by N—H...O and O—H...O hydrogen bonds to form rings with aR44(14) graph-set motif.

Crystal structure of 1,1,2,2-tetra-methyl-1,2-bis-(2,3,4,5-tetra-methyl-cyclo-penta-2,4-dien-1-yl)disilane

The mol­ecular structure of the title compound, C₂₂H₃₈Si₂, features a trans arrangement of the cyclo­penta­dienyl rings to avoid steric strain [C—Si—Si—C torsion angle = −179.0 (5)°]. The Si—Si bond length is 2.3444 (4) Å. The most notable inter­molecular inter­actions in the mol­ecular packing are C—H⋯π contacts that lead to the formation of wave-like supra­molecular chains along the b axis.

Highly selective visible light-induced Ti–O bond splitting in an ansa-titanocene dihydroxido complex

Visible light irradiation of an ansa-titanocene(iv) dihydroxido complex Me₄Si₂(C₅Me₄)₂Ti(OH)₂ induces highly selective Ti–O bond activation to exclusively yield Ti(iii) complexes.