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• Synthesis of titanium indenyls with alkyloxy ligands. • Single-crystal structure analysis confirms a piano-stool arrangement at titanium. • Structural and electronic analysis using DFT calculations provides significant insights into the complexes molecular orbitals and the molecular electrostatic surface potentials. Indenyl-titanium trichloride complexes of type [Ti{η5-1-(SiMe 3)-3-(R)-C 9 H 5 }Cl 3 ] (R = SiMe 3 (3a); R = t Bu (3b)) were obtained by treatment of Li[1-(SiMe 3)-3-(R)-C 9 H 5 ] (R = SiMe 3 (1a); R = t Bu (1b)) with titanium tetrachloride (2) in a 1:1 molar ratio in the presence of isopropanol and SOCl 2. Compounds [Ti{η5-1-(SiMe 3)-3-(R)-C 9 H 5 }Cl 2 (OEt)] (R = SiMe 3 (4a); R = t Bu (4b)) are accessible by reacting 1a,b (R = SiMe 3 (1a); R = t Bu (1b)) with TiCl 4 (2) in the presence of ethanol and SOCl 2 , 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. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Alkyloxy- and aryloxy-functionalized titanocenes of type [Ti](Cl)(OR) (R=Me (2), CH2PPh2 (3), CH2Fc (4), C6H5 (5), C6H4-4-Cld>6), C6H4-4-NO2 (7), C6H4-4-Me (8), C6H4-4-OMe (9), C6H4-4-C(O)Me (10), C6H4-4-CO2Me (11), C6H4-3-NO2 (12); [Ti]=(η5-C5H4SiMe3)2Ti; Fc=(η5-C5H4)(η5-C5H5)Fe) were synthesized by the reaction of [Ti]Cl2 (1) with ROH in a 1:1 molar ratio and in presence of Et2NH. Diaryloxy-titanocenes (e.g., [Ti](OC6H4-4-NO2)2 (13)) are accessible, when the ratio of 1 and ROH is changed to 1:2. This synthesis methodology also allowed the preparation of dinuclear complexes of composition ([Ti](Cl))2(μ-OC6H4O) (14) and ([Ti](Cl)(μ-OC6H4-4))2 (15) by the reaction of 1 with hydroquinone or 1,1′-dihydroxybiphenyl in a 2:1 stoichiometry. Cyclic voltammetric studies show the characteristic [Ti(IV)/Ti(III)] reductions. It was found that the potentials of the alkyloxy titanocenes 2–4 do not differ, while for the aryloxy-titanocenes 5–15 the reduction potentials correlate linearly with the σ p/m Hammett substituent constants showing a strong influence of the substituents on the electron density at titanium. The structures of titanocenes 4, 5, 9, and 11–13 in the solid state are reported. Typical for these organometallic sandwich compounds is a distorted tetrahedral coordination geometry around titanium with D1–Ti–D2 angles (D1, D2=centroids of the cyclopentadienyl ligands) of ca. 130°. In comparison to FcCH2O-functionalized 4, for the aryloxy-titanocenes 5, 9, and 11–13 a significant larger Ti–O–C angle was found confirming electronic interactions between the titanium atom and the appropriate aryl group. [Copyright &y& Elsevier]

Titanocene dichloride, [Ti]Cl 2 ( 1 ) ([Ti] = Ti(η 5 -C 5 H 4 SiMe 3 ) 2 ), with one equiv. of the lithium thiolates LiSCHR-2- c C 4 H 3 S ( 2a , R = H; 2b , R = Me) gave the appropriate [Ti](Cl)(SCHR-2- c C 4 H 3 S) compounds ( 3a , R = H; 3b , R = Me) under mild reaction conditions. Further treatment of 3a , b with another equiv. of thiolates 2a , b produced the respective bis(thiolates) species [Ti](SCHR-2- c C 4 H 3 S) 2 ( 4a , b ). Titanocenes 4a , b are also accessible, when 1 is reacted with 2a , b in a 1:2 M ratio. The hydrolysis reaction of 4a , b produced the titanoxane cluster 5 , consisting of a [Ti′] 6 O 9 cage ([Ti′] = Ti(η 5 -C 5 H 4 SiMe 3 )) with a silsesquioxane analog structure. The molecular structure of 5 in the solid state is the first example of a trigonal prismatic Ti 6 -polyhedron. Upon treatment of 4a , b with MCl 2 (M = Pd, Pt), aiming to obtain heterobimetallic coordination complexes, however, either 1 or 3a , b were formed, depending on the reaction conditions. All the compounds have been characterized by elemental analysis, IR, NMR ( 1 H, 13 C{ 1 H}) spectroscopy and mass-spectrometry. [ABSTRACT FROM AUTHOR]