[Ti{η5-1-(SiMe3)-3-(R)-C9H5}Cl2(OEt)] Half-Sandwich Complexes: Synthesis, Solid-State Structure, Hirshfeld Surface Analysis and Theoretical Studies

Indenyl-titanium trichloride complexes of type [Ti{η5-1-(SiMe3)-3-(R)-C9H5}Cl3] (R = SiMe3 (3a); R = tBu (3b)) were obtained by treatment of Li[1-(SiMe3)-3-(R)-C9H5] (R = SiMe3 (1a); R = tBu (1b)) with titanium tetrachloride (2) in a 1:1 molar ratio in the presence of iso-propanol and SOCl2. Compounds [Ti{η5-1-(SiMe3)-3-(R)-C9H5}Cl2(OEt)] (R = SiMe3 (4a); R = tBu (4b)) are accessible by reacting 1a,b (R = SiMe3 (1a); R = tBu (1b)) with TiCl4 (2) in the presence of ethanol and SOCl2, or when 3a,b were treated with equimolar amounts of EtOH in refluxing benzene. Spectroscopic methods and single crystal X-ray diffraction analysis confirmed the piano-stool geometry of 3a and 4b in the solid state. Hirshfeld surface analysis using 2D fingerprint plots of 3a and 4b were conducted to elaborate non-covalent, intermolecular interactions existing in the solid state, which accounted for the strengthening of the crystal lattice. The molecular structures of the 3 and 4 were further investigated by quantum-chemical calculations. The geometries of the compounds were optimized at the B3LYP/6-31G(d)+LANL2DZ level of theory, and their related molecular parameters including frontier orbital energy gap and molecular electrostatic surface potential have also been calculated to better understand their properties.