79269-70-8Relevant academic research and scientific papers
Titanium(IV) carboxylate complexes: Synthesis, structural characterization and cytotoxic activity
Gómez-Ruiz, Santiago,Gallego, Beatriz,?i?ak, ?eljko,Hey-Hawkins, Evamarie,Jurani?, Zorica D.,Kaluderovi?, Goran N.
, p. 354 - 360 (2010/04/04)
Four titanium(IV) carboxylate complexes [Ti(η5-C5H5)2 (O2CCH2SMes)2] (1), [Ti(η5-C5H4Me)2 (O2CCH2SMes)2] (2), [Ti(η5-C5H5)(η5 -C5H4SiMe3)(O2CCH2SMes )2] (3) and [Ti(η5-C5Me5)(O2CCH 2SMes)3] (4; Mes = 2,4,6-Me3C6H2) have been synthesised by the reaction of the corresponding titanium derivatives [Ti(η5-C5H5)2Cl 2], [Ti(η5-C5H4Me) 2Cl2], [Ti(η5-C5H5)(η5 -C5H4SiMe3)Cl2] and [Ti(η5-C5Me5)Cl3] and two (for 1-3) or three (for 4) equivalents of mesitylthioacetic acid. Complexes 1-4 have been characterized by spectroscopic methods and the molecular structure of the complexes 1, 2 and 4 have been determined by X-ray diffraction studies. The cytotoxic activity of 1-4 was tested against tumor cell lines human adenocarcinoma HeLa, human myelogenous leukemia K562, human malignant melanoma Fem-x, and normal immunocompetent cells, that is peripheral blood mononuclear cells PBMC and compared with those of the reference complexes [Ti(η5-C5H5)2Cl 2] (R1), [Ti(η5-C5H4Me)2Cl 2] (R2), [Ti(η5-C5H5)(η5 -C5H4SiMe3)Cl2] (R3) and cisplatin. In all cases, the cytotoxic activity of the carboxylate derivatives was higher than that of their corresponding dichloride analogues, indicating a positive effect of the carboxylato ligand on the final anticancer activity. Complexes 1-4 are more active against K562 (IC50 values from 72.2 to 87.9 μM) than against HeLa (IC50 values from 107.2 to 142.2 μM) and Fem-x cells (IC50 values from 90.2 to 191.4 μM).
Die Best?ndigkeit von (η5-C5H4R)2Ti(CCR′) 2 in Abh?ngigkeit von den elektronischen Eigenschaften der Cyclopentadienyl-Liganden. Die Festk?rperstruktur von (η5-C5H5)(η5-C 5H4SiMe3)Ti(CCSiMe3)2
Lang,Meichel,Stein,Back,Hovestreydt
, p. 71 - 78 (2007/10/03)
The synthesis of the titanocene dichlorides (η5-C5H5)(η5-C 5H4SiMe3)TiCl2 (3) and (η5-C5H4CO2R) 2TiCl2 (8a, R=CH3; 8b, R=CH2CH3), which contain either electron-donating or electron-withdrawing substituents at the cyclopentadienyl fragments is discussed. While the reaction of 8a or 8b with LiCCR′ in different stoichiometric ratios leads only to product mixtures from which no pure components could be isolated, treatment of 3 with two equivalents of LiCCR′ (9a, R′=C6H5; 9b, R′=tBu; 9c, R′=SiMe3) selectively produces the bis(alkinyl) titanocenes (η5-C5H5)(η5-C 5H4SiMe3)Ti(CCR′)2 (10a, R′=C6H5; 10b, R′=tBu; 10c, R′=SiMe3). However, it was found that when complex 10c is stirred in tetrahydrofuran solutions, Me3SiCC is eliminated and Me3SiCC-CCSiMe3 (11) along with [(η5-C5H5)(η5-C 5H4SiMe3)Ti(CCSiMe3)]2 (12) is formed.The solid-state structure of (η5-C5H5)(η5-C 5H4SiMe3)Ti(CCSiMe3)2 (10c) is reported. Complex 10c crystallises in the monoclinic space group Pc with two independent molecules in the asymmetric unit and with the cell constants a=20.8131(6), b=10.6615(3), c=12.2543(4) A?, β=101.12(3)°, V=2668.14(14) A?3 and Z=4. 10c exhibits a pseudotetrahedrally coordination sphere around the Ti(IV) centre comprised of the two σ-bonded alkynyl ligands Me3SiCC and the η5-coordinated cyclopentadienyl moieties C5H5 as well as C5H4SiMe3.
An investigation of the reaction of bis(cyclopentadienyl)titanium dichlorides with trimethylaluminum. Mechanism of an α-hydrogen abstraction reaction
Ott, Kevin C.,DeBoer,Grubbs, Robert H.
, p. 223 - 230 (2008/10/08)
The reaction of Me3Al with Cp2TiCl2 and its derivatives has been studied. Synthetic procedures for the preparation of (C5R5)(C5H5)TiCl2 from (C5R5)Li and (C5H5)TiCl3 were developed, and sources of the major byproducts (C5H5)2TiCl2 and (C5R5)2TiCl2 are suggested. The derivatives studied were (C5R5) = C5H4SiMe3, 1,2,4-trimethylcyclopentadienyl, (CH3)5C5, indenyl, 1,3-Ph2C5H3, and (CH3)C5H4. All of these complexes reacted with 1 equiv of (CH3)3Al to produce Cp2Ti(CH3)Cl·Al(CH3)2Cl which would react further with a second equivalent of (CH3)3Al to yield a Cp2TiCH2AlMe2Cl derivative. The isotope effect for the parent reaction was 2.9. Substituents on the ring slowed the rate of methylene formation. A mechanism for α-hydrogen abstraction from a Ti-(CH3)Cl unit by an aluminum alkyl is proposed in which the Lewis acidic aluminum alkyl activates the titanium methyl group by complexation with the chlorine. The resulting aluminate then serves as a strong Lewis base to abstract the α-hydrogen.
