Crystalline bis(η⁵-cyclopentadienyl)bis(benzoato/carboxylato)titanium(IV) precursor-directed route to functional titanium dioxide nanomaterials

Abstract

Five titanocene(IV) carboxylates of the general formula Cp2Ti(O2CR)2 viz., [Ti( 5-C5H5)2(O2CC6H5-4-CH3)2] (1), [Ti( 5-C5H5)2(O2CC4H3-2-O)2] (2), [Ti( 5-C5H5)2(O2CC4H3-3-O)2] (3), [Ti( 5-C5H5)2(O2CC(CH3)3)2] (4) and [Ti( 5-C5H5)2(O2C(CH)C(CH3)3)2] (5) have been synthesized. All the titanocene(IV) carboxylates have been characterized by IR, 1 H and 13 C NMR spectroscopic techniques, and the crystal and molecular structures of 1-5 have been determined by single crystal X-ray crystallography. The structures present similar features with monodentate carboxylate ligands and tetrahedral Ti centres, assuming the each Cp ring occupies one position only. The differences in the structures relate primarily to the relative orientations of the carboxylate ligands. In the molecular packing, non-conventional Cp-C-H … O(carbonyl) hydrogen bonds are observed in each case and lead to supramolecular chains in each of 1, 4 and 5. In 2, the 2-furyl-O atoms also participate in C-H … O interactions leading to a two-dimensional array. Finally, in 3, a two-dimensional array arises as a result of Cp-C-H … O(carbonyl) and 3-furyl-C-H … O(carbonyl) interactions. As representative example, compound 3 was used as starting material for the synthesis of TiO2 nanoparticles. 2 An effective and simple wet-chemical method involving calcination and ultrasonication route has been suggested for obtaining pure anatase TiO2 NPs, which were confirmed from the powder XRD and imaging techniques such as SEM, TEM and EDS.

Mono- and di-anionic coordination modes of arylazosalicylates in their bis(η5-cyclopentadienyl)titanium(IV) complexes: Syntheses and crystal structures

“…10.60 (10) and 7.23(7)°. As discussed in a recent contribution [59], the structural motif observed for 3 and 4…”

“…In view of the above technical difficulties and on the basis of previous success with the synthesis and structure determination of titanocene carboxylates of the type Cp 2 Ti(O 2 CR) 2 [59], the present work aimed to synthesise a series of bis(η 5 -cyclopentadienyl)titanium(IV) substituted salicylates using a straightforward and reproducible synthetic methodology. For this purpose, 5-…”

New Titanocene (IV) Dicarboxylates with Potential Cytotoxicity: Synthesis, Structure, Stability and Electrochemistry

“…The most common method for preparing various titanocene derivatives from titanocene dichloride is the nucleophilic displacement of chloride anions with a suitable nucleophilic reagent. Several methods have been described in the literature for the introduction of certain carboxylate anions to titanocene [ 17 , 18 , 20 , 21 ], but our attempts to reproduce them only partially lead to satisfactory results because the products obtained by these methods were always isolated from the solution together with resinous impurities, the separation from which requires long-term purification using repeated reprecipitation.…”

“…Thus, sodium salts that are sufficiently pure and dry for organometallic reactions of any carboxylic acids strong enough to react with sodium bicarbonate can be successfully prepared by the described method. The use of sodium hydride salts (tested in the framework of this work), sodium ethoxide in ethanol, sodium methoxide in methanol [ 20 ], or solutions of sodium hydroxide in water [ 22 ] for the preparation of the required salts leads to side processes when sodium salt interacts with titanocene dichloride, even in the case of the preliminary purification of the obtained salts by recrystallization.…”

“…The synthesis of titanocene dicarboxylates 2 was carried out according to Scheme 2 . The best yields of target compounds were obtained using absolute benzene as a solvent [ 20 ], while our attempts to use methanol, aqueous methanol, chloroform, and acetone did not lead to yields of target compounds greater than 10–15%.…”