Stereoisomerism in Lanthanide Complexes: Enumeration, Chirality, Identification, Random Coordination Ratios

Abstract

The concept of random coordination ratios, RCRs, is advanced for lanthanide complexes. RCRs describe the relative probabilities of occurrence of subsets of stereoisomers of same-symmetry point groups in the limiting situation when energetic effects are equivalent. We then introduce a method to uniquely identify the stereoisomer of the coordination polyhedron of a given crystallographic structure and introduce a notation that fully characterizes its stereochemistry in an unambiguous manner, from which absolute configuration naturally follows. De facto, the coordination chirality in lanthanide complexes is a frequently overlooked property, even though these compounds often exhibit, when luminescent, high dissymmetry factors. With our methodology, we even managed to recognize a known dilanthanide complex as a meso compound, with both metal ions functioning as stereogenic centers. To achieve these results, we enumerate all possible stereoisomers of lanthanide complexes with coordination numbers from 4 to 9 for all combinations of monodentate, symmetric and asymmetric bidentate ligands, and for several shapes of coordination polyhedra. We confirmed the number of stereoisomers for each case by means of Pólya's theorem. We further classified all stereoisomers according to their symmetry point groups and generated their Cartesian coordinates. This collection of all coordination polyhedra stereoisomer geometries, which is made available in the Supporting Information , can also be used to easily build starting-point geometries for theoretical calculations of metal complexes.

Ab initio molecular dynamics study of the structure and supramolecular organization in mesogenic lanthanum(III) complexes with β‐diketones and Lewis bases

“…The optimized structures of complexes are shown in Figure 2. Analysis of the optimized structures by SHAPE program revealed that coordination polyhedron of the La(CPDK 3‐5 ) 3 Bpy 17‐17 complex is slightly distorted square antiprism and triangular dodecahedron for La(CPDK 5‐Th ) 3 Bpy 17‐17 and La(CPDK 5‐Th ) 3 Phen which are frequent shapes for Ln(III) complexes with a coordination number of 8 [38]. This is in agreement with common expectations [51, 52].…”

“…There are many other stereoisomers of the coordination polyhedra of the studied La(III) complexes [38] but due to the high computational costs only one isomer for each La(III) complex with the energetically most advantageous arrangement of the ligands was considered. Therefore, three exemplary La(III) complexes were studied.…”

SEQCROW: AChimeraXbundle to facilitate quantum chemical applications to complex molecular systems

“…Multiple structures can be edited simultaneously, allowing, for example, derivatives of all stationary points along a reaction pathway to be generated. SEQCROW can also automatically construct all unique coordination complexes (up to 7-coordinate) with any combination of mono-or bidentate ligands (with and without C 2 -symmetry) based on structural templates from Simas et al 16 Finally, users can rotate entire molecules or selected atoms about any defined centroid and axis (including the axis normal to a set of atoms) using the Rotate Atoms tool.…”

Terras Raras: Tabela Periódica, Descobrimento, Exploração No Brasil E Aplicações

“…Além disso, a utilização de ferramentas teóricas para a descrição da luminescência de lantanídeos é extremamente útil para o aprimoramento e adaptação das propriedades observadas. [117][118][119][120][121] O número crescente de aplicações industriais com elementos de terras raras despertou o interesse em novas tecnologias de extração via fontes alternativas. [122][123][124][125][126][127][128] Embora as propriedades luminescentes dos compostos de TR fossem conhecidas desde o final do século XIX e início do século XIX, o primeiro composto usado contendo terras raras foi o vanadato de ítrio dopado com európio(III), emissor vermelho.…”