posted on 2024-02-24, 17:04authored byAlexander G. Morozov, Vladimir A. Dodonov, Elena A. Rychagova, Sergey Yu. Ketkov, Igor L. Fedushkin
A series
of the chlorido and alkoxychlorido titanium complexes
of the general formula (dpp-Bian)Ti(OiPr)nCl3–n, where dpp-Bian = 1,2-bis[(2,6-iPr2C6H3)imino]acenaphthene n = 0 (2), 1 (3), 2 (4), as well as (dpp-Bian)Ti(OiPr)2 (5) and (dpp-Bian)Ti(OiPr)Cl3 (3-Cl), were isolated and characterized
using single-crystal X-ray diffraction analysis and spectroscopic
studies combined with density functional theory (DFT) calculations.
In the solid state, compounds 2–4 reveal a square–pyramidal
geometry at the metal center supported with monoanionic dpp-Bian,
whereas 3-Cl with a neutral diimine ligand and 5 bearing a dianionic enebisamide dpp-Bian show, respectively,
an octahedral and tetrahedral coordination surrounding the metal ion.
Paramagnetic complexes 2–4 exhibit electron paramagnetic
resonance spectra in both toluene solution and solid state, confirming
the transfer of spin density from the metal ion to the dpp-Bian ligand
as the number of alkoxy groups increases. The increase in polarity
of the Ti–N bonds in the row 2 < 3 < 4 contributes to enhanced stability of the metal
complexes with respect to O-donor molecules. Thus, in tetrahydrofuran
(THF), compounds 2 and 3 undergo reversible
solvolysis, whereas complex 4 is stable. The charge and
spin density distributions as well as molecular orbital energies in 2–4 were analyzed on the basis of DFT calculations
which also provided information on the electronic transition energies,
absorption band assignments, and thermodynamic parameters of the reactions
between the complexes and THF.