Synthesis and characterization of a monomeric octahedral C2-symmetric titanium complex bearing two 3,3′-diphenyl-2,2′-biphenol ligands

Abstract

The 3,3'-diphenyl-2,2'-biphenol (dpbpolH(2)) ligand is shown to react with Ti(OPr(i))(4) in a 2:1 ratio to yield a novel C(2)-symmetric mononuclear octahedral Ti(IV) bis-biphenolate complex, cis-Ti(dpbpol)(2)(HOPr(i))(2).

A Remarkable Solvent Effect on the Nuclearity of Neutral Titanium(IV)‐Based Helicate Assemblies

“…The solid‐state NMR spectrum for Ti3 (Figure 5 b) is analogous to that for the previously reported Ti1 complex25 and indicates that each Ti IV center of the triangular structure is complexed to isopropanol and phenolate ligands only. Indeed, the three regions of the spectrum that correspond to the resonance of the aromatic carbon atoms and the tertiary and primary carbons that belong to the isopropanol ligands for Ti3 are rather complex.…”

“…A complete characterization of the Ti3 complex in the solid state, gaseous phase, and liquid phase is reported. The analytical data of Ti3 are discussed with respect to those obtained for the previously reported double‐stranded helicate and a related monomeric complex formed with two 3,3‐diphenyl‐2,2′‐biphenolate ligands Ti1 25. We also highlight the complete reorganization of the trinuclear species into the double‐stranded helicate in solution.…”

“…Table 1 presents the TiO (Ph) and TiO ( i Pr) bond lengths for H 6 [Ti 3 L 3 ( i PrO) 6 ]. The values obtained will be discussed and compared to the model complex Ti1 , the monomeric octahedral C 2 ‐symmetric titanium(IV) complex bearing two 3,3′‐diphenyl‐2,2′‐biphenol ligands, and two isopropanol molecules coordinated to the metal center in a cis arrangement (the structure presented in the Supporting Information) 25. In this model complex, distances between 1.818 and 1.900 Å were measured for the TiO (Ph) bonds, whereas distances averaging 2.17 Å were determined for the TiO ( i PrOH) bonds.…”

“…Owing to the very large NMR signals observed, we turned first to diffusion‐ordered spectroscopy (DOSY), which allows estimation of the hydrodynamic radii in solution from calculations of the diffusion coefficients. As we had already established the partial de‐coordination of the isopropanol ligands for Ti1 25 at room temperature, all the analysis was performed at low temperature to minimize the exchange processes. Basically, for a solute species that diffuses in a solvent with a viscosity η (mPa s) at temperature T (K) with a diffusion coefficient D (μm 2 s −1 ), its hydrodynamic radius R h (Å) may be computed from the Stoke–Einstein relationship: R h =7.32457 ( T / ηD ).…”

“…The values obtained will be discussed and compared to the model complex Ti1, the monomeric octahedral C 2 -symmetric titanium(IV) complex bearing two 3,3'-diphenyl-2,2'-biphenol ligands, and two isopropanol molecules coordinated to the metal center in a cis arrangement (the structure presented in the Supporting Information). [25] In this model complex, distances between 1.818 and 1.900 were measured for the TiÀO (Ph) bonds, whereas distances averaging 2.17 were determined for the TiÀO (iPrOH) bonds. These values agree well with the average distances found in the cyclic helicate structure H 6 [Ti 3 (L 3 )(iPrO) 6 ]: 1.868 (s = 0.035) for TiÀO (Ph) and 2.174 (s = 0.007) for TiÀO (iPr) .…”