Synthesis and characterization of a tert-butyl ester-substituted titanocene dichloride: t-BuOOCCp2TiCl2.

Jackson S Mccarthy,Colin D Mcmillen,Paul S Wagenknecht,Jared A Pienkos

doi:10.1107/s2056989020011834

Abstract

Bis[η5-(tert-butoxyca-rbonyl)-cyclo-penta-dien-yl]di-chlorido-titanium(IV), [Ti(C10H13O2)2Cl2], was synthesized from LiCpCOOt-Bu using TiCl4, and was characterized by single-crystal X-ray diffraction and 1H NMR spectroscopy. The distorted tetra-hedral geometry about the central titanium atom is relatively unchanged compared to Cp2TiCl2. The complex exhibits elongation of the titanium-cyclo-penta-dienyl centroid distances [2.074 (3) and 2.070 (3) Å] and a contraction of the titanium-chlorine bond lengths [2.3222 (10) Å and 2.3423 (10) Å] relative to Cp2TiCl2. The dihedral angle formed by the planes of the Cp rings [52.56 (13)°] is smaller than seen in Cp2TiCl2. Both ester groups extend from the same side of the Cp rings, and occur on the same side of the complex as the chlorido ligands. The complex may serve as a convenient synthon for titanocene complexes with carboxyl-ate anchoring groups for binding to metal oxide substrates.

Highlights

Bis[5-(tert-butoxycarbonyl)cyclopentadienyl]dichloridotitanium(IV), [Ti(C10H13O2)2Cl2], was synthesized from LiCpCOOt-Bu using TiCl4, and was characterized by single-crystal X-ray diffraction and 1H NMR spectroscopy
The complex may serve as a convenient synthon for titanocene complexes with carboxylate anchoring groups for binding to metal oxide substrates
Molecules exhibiting charge-separated excited states have been shown to be useful in photocatalysis (Prier et al, 2013), dye-sensitized photoelectrochemical cells (Hammarstrom, 2015; Kalyanasundaram & Gratzel, 1998) and dye-sensitized solar cells (DSSCs) (Ji et al, 2018; Kalyanasundaram & Gratzel, 1998)

Summary

Chemical context

Molecules exhibiting charge-separated excited states have been shown to be useful in photocatalysis (Prier et al, 2013), dye-sensitized photoelectrochemical cells (Hammarstrom, 2015; Kalyanasundaram & Gratzel, 1998) and dye-sensitized solar cells (DSSCs) (Ji et al, 2018; Kalyanasundaram & Gratzel, 1998). Tution at the Cp ring results in a decrease of the dihedral angle formed between the planes of the two Cp rings This angle is 58.5 in titanocene dichloride (Clearfield et al, 1975), but is 52.56 (13) in this titanocene and 52.2 in the alkyl substituted titanocene (Ceballos-Torres et al, 2019). The appended esters in t-BuOOCCp2TiCl2 extend from the same sides of both Cp rings, and occur on the same side of the complex as the chlorido ligands (Fig. 2) This is a similar arrangement to what occurs in EtOOCCp2NbBr2 and MeOOCCp2NbBr2ÁCH2Cl2, but differs from PhOOCCp2VCl2, PhOOCCp2NbCl2, and MeOOCCp2NbBr2, where the substituting esters are on opposing sides of their respective Cp rings, and do not overlap with the halides (Klepalova et al, 2013)

Structural commentary

Supramolecular features

Database survey

Synthesis and crystallization

Refinement

C16 C17 C18 H18A H18B H18C C19 H19A H19B H19C C20 H20A H20B H20C