Geometrical and optical benchmarking of copper(II) guanidine–quinoline complexes: Insights from TD‐DFT and many‐body perturbation theory (part II)

Abstract

Ground- and excited-state properties of copper(II) charge-transfer systems have been investigated starting from density-functional calculations with particular emphasis on the role of (i) the exchange and correlation functional, (ii) the basis set, (iii) solvent effects, and (iv) the treatment of dispersive interactions. Furthermore (v), the applicability of TD-DFT to excitations of copper(II) bis(chelate) charge-transfer systems is explored by performing many-body perturbation theory (GW + BSE), independent-particle approximation and ΔSCF calculations for a small model system that contains simple guanidine and imine groups. These results show that DFT and TD-DFT in particular in combination with hybrid functionals are well suited for the description of the structural and optical properties, respectively, of copper(II) bis(chelate) complexes. Furthermore, it is found an accurate theoretical geometrical description requires the use of dispersion correction with Becke-Johnson damping and triple-zeta basis sets while solvent effects are small. The hybrid functionals B3LYP and TPSSh yielded best performance. The optical description is best with B3LYP, whereby heavily mixed molecular transitions of MLCT and LLCT character are obtained which can be more easily understood using natural transition orbitals. An natural bond orbital analysis sheds light on the donor properties of the different donor functions and the intraguanidine stabilization during coordination to copper(I) and (II).

Theoretical studies of organotin(IV) complexes derived from ONO-donor type schiff base ligands

“…Chemical hardness is a derivative of chemical potential, and Bmeasures resistance to flow of electrons at a constant external potential as driven by chemical potential^ [62]. This can be given with a finite difference formula [72]:…”

“…B3LYP, TPSSTPSS, and CAM-B3LYP optimized structures were further refined with the D3 version of Grimme's dispersion with Becke-Johnson damping (GD3BJ) to investigate the quality improvements quantitatively. GD3BJ is one of the latest empirical dispersion correction schemes, and has been used in many studies [60][61][62][63] to take dispersion interactions into account. 1 H-NMR and 13 C-NMR chemical shifts were calculated via using DFT …”

Guanidine Metal Complexes for Bioinorganic Chemistry and Polymerisation Catalysis

“…Raman spectroscopy helped to identify the resonance and the crucial vibrations which connect the two states. The chargetransfer behaviour of these complexes has been intensively studied by density functional theory and many-body perturbation theory, and TD-DFT was found to reproduce the experimental spectra faithfully when using triple-zeta basis sets and hybrid functionals [78][79][80]. DMEGqu is even able to stabilise tin(IV) complexes (Fig.…”

Science gateways - leveraging modeling and simulations in HPC infrastructures via increased usability

“…With this optimized structure, different functionals can be used to evaluate the functional dependency of the optical transitions (atomic WFs: TD-B3LYP WF, TD-PW91 WF, TD-TPSSh-WF, TD-PBE WF) using time-dependent DFT (TD-DFT). Charge-transfer transitions are very sensitive towards the choice of the functional [37][38][39] and the results can largely deviate from the experimental spectrum. Hence, for a new transition metal system, one always needs to perform a socalled optical benchmarking and find a suited functional to describe measured spectra correctly.…”

“…Moreover, for every step, metadata are annotated and stored facilitating the organization of the computational chemists work. In principle, this optical benchmarking workflow can be conceptualized in a broader way when more functionals are required to describe a complicated electronic behavior [37][38][39].…”