Covalent lanthanide(iii) macrocyclic complexes: the bonding nature and optical properties of a promising single antenna molecule

Abstract

The present work is focused on the elucidation of the electronic structure, bonding nature and optical properties of a series of low symmetry (C2) coordination compounds of type [Ln(III)HAM](3+), where "Ln(III)" are the trivalent lanthanide ions: La(3+), Ce(3+), Eu(3+) and Lu(3+), while "HAM" is the neutral six-nitrogen donor macrocyclic ligand [C22N6H26]. This systematic study has been performed in the framework of the Relativistic Density Functional Theory (R-DFT) and also using a multi-reference approach via the Complete Active Space (CAS) wavefunction treatment with the aim of analyzing their ground state and excited state electronic structures as well as electronic correlation. Furthermore, the use of the energy decomposition scheme proposed by Morokuma-Ziegler and the electron localization function (ELF) allows us to characterize the bonding between the lanthanide ions and the macrocyclic ligand, obtaining as a result a dative-covalent interaction. Due to a great deal of lanthanide optical properties and their technological applications, the absorption spectra of this set of coordination compounds were calculated using the time-dependent density functional theory (TD-DFT), where the presence of the intense Ligand to Metal Charge Transfer (LMCT) bands in the ultraviolet and visible region and the inherent f-f electronic transitions in the Near-Infra Red (NIR) region for some lanthanide ions allow us to propose these systems as "single antenna molecules" with potential applications in NIR technologies.

Crystal Field in Rare‐Earth Complexes: From Electrostatics to Bonding

“…A purely electrostatic approach has been proposed to determine the direction of the magnetic moment, by minimizing the potential energy; the ligands are modeled by fractional charges determined by valence‐bond resonance hybrids . First‐principles calculations are regularly used to quantify the degree of covalency in metal–ligand bonding . CFPs may be deduced from first‐principles methods and the contribution of covalency to CFPs was recently confirmed to be non‐negligible …”

“…It is shownt hat am odel with three layers of charges reproduces the electrostatic field generated by the ligands and that the covalency plays aqualitative role. [15][16][17][18][19] CFPs may be deduced from first-principles methods and the contributiono fc ovalency to CFPs was recently confirmedt ob enon-negligible. This permits ar eductiono ft he many-electron problem to ad iscussion of the energy of the seven 4f orbitals.…”

“…[13] Ap urely electrostatic approach has been proposed to determinet he direction of the magnetic moment, by minimizing the potentiale nergy;t he ligandsa re modeled by fractional charges determined by valence-bond resonance hybrids. [15][16][17][18][19] CFPs may be deduced from first-principles methods and the contributiono fc ovalency to CFPs was recently confirmedt ob enon-negligible. [15][16][17][18][19] CFPs may be deduced from first-principles methods and the contributiono fc ovalency to CFPs was recently confirmedt ob enon-negligible.…”

Advances in bonding and properties of inorganic systems from relativistic calculations in Latin America

“…Moreover, the antenna effect in a covalent lanthanide (III) macrocyclic complex was discussed . On the other hand, the antenna effect induced by organometallic chromophores in bimetallic d‐f complexes has been well developed by Ferraro and Cantero‐Lopez, where an effective direction of the electron transfer between the Re → Ac or Os→Th centers of the d‐f complexes allows to propose [Cp 2 ReAcCp 2 ] and [Cp 2 OsThCp 2 ] species as ideal candidates for near‐infrared (NIR) technologies since their absorption spectra show some transitions beyond 600 nm.…”

“…[132] with permission from the Centre National de la Recherche Scientifique (CNRS) and The Royal Society of Chemistry Moreover, the antenna effect in a covalent lanthanide (III) macrocyclic complex was discussed. [115] On the other hand, the antenna effect induced by organometallic chromophores in bimetallic d-f complexes has been well developed by Ferraro and Cantero-Lopez, [143,144]…”