Accurate experimental and theoretical enthalpies of association of TiCl₄ with typical Lewis bases used in heterogeneous Ziegler–Natta catalysis

Abstract

Adducts of TiCl with Lewis bases used as internal or external donors in heterogeneous Ziegler-Natta (ZN) catalysis represent a fundamental interaction contributing to the final composition of MgCl supported ZN-catalysts. This study presents the accurate experimental evaluation, from titration calorimetry, of the formation enthalpy of TiCl adducts with 15 Lewis bases of industrial interest. In addition, we report the accurate energies of association of TiCl with the same Lewis bases from calculations at the DLPNO-CCSD(T) level of theory. These accurate experimental and theoretical association values are compared with selected methods based on density functional theory (DFT) in combination with popular continuum solvation models. Calculations suggest that the PBE-D3, and M06 functionals in combination with a triple-ζ plus polarization quality basis set provide the best performance when the basis set superposition error (BSSE) is not removed from the association energies. Cleaning the association energies with the BSSE with the counterpoise protocol suggests B3LYP-D3, TPSS-D3 and M06L as the best performing functionals. The introduction of solvent effects with the PCM and SMD continuum solvation models allows the DFT-based association enthalpies to be compared with the experimental values obtained from titration calorimetry. Both solvation models in combination with the PBE-D3, PBE0-D3, B3LYP-D3, TPSS-D3, M06L, and M06 functionals provide association enthalpies close to the experimental values with MUEs in the range of 10-15 kJ mol.

Intercalation Ability of Novel Monofunctional Platinum Anticancer Drugs: A Key Step in Their Biological Action

“… 61 Previous works showed that the B3LYP-D3 method provides reliable results for structures, thermochemistry, and kinetic activation parameters for Pt(II) complexes. 38 , 39 , 62 − 65 The Def2SVP basis set 66 , 67 for all atoms was employed with relative effective core potential for the platinum atom. The solvent has been introduced as polarizable continuum (PCM).…”

Insights into the Nature of Self‐Extinguishing External Donors for Ziegler‐Natta Catalysis: A Combined Experimental and DFT Study

“…For better accuracy, we have performed single point calculations using PBE0 functional, [66] TZVP basis set, [62] and dispersion correction (DFT‐D3) [63] . Our choice of the PBE‐D3/TZVP//PBE0‐D3/TZVP level of theory is based on benchmarking and computational studies [67,68,34] . For the calculations that we have performed, the energy convergence criteria was 10 −6 H, and the norm for the cartesian gradients was 10 −3 .…”

Roles of Salicylate Donors in Enhancement of Productivity and Isotacticity of Ziegler–Natta Catalyzed Propylene Polymerization

“…Adsorption energies were obtained using DFT calculations with the B3LYP-D3 functional [46]. This functional has been proven by Cavallo et al [47] to well reproduce the experimental association energies between TiCl4 of fifteen electron donors. The LANL2DZ effective core potentials (ECP) function and basis set were used for Ti atom [48], while the 6-31G(d,p) basis set was used for others.…”