Shedding Light on Intermolecular Metal–Organic Ring Interactions by Theoretical Studies

Abstract

Metal–organic ring interactions (MORi) represent a kind of supramolecular interaction with a stacking character, which is formed between five and/or six‐membered chelated rings; the latter occur when a pseudopeptidic‐type of ligand (malonamide‐N,N′‐dicarboxylic acid) chelates to CuII which favors a square‐planar geometry. So far, a series of CuM compounds (M=Ca, Ln) with diverse structural characteristics have been isolated, varying from discrete coordination clusters to multidimensional polymers; their common feature is the presence of five and six‐membered chelated rings stacked together. In this study, the nature of MORi was investigated at the DFT level (B3LYP‐D/TZ2P) by using an energy decomposition analysis (EDA) of the interaction energy between the two CuII complexes in the dimeric monomer unit chosen. The EDA calculations showed that the intermolecular interactions in three heterometallic CuM compounds (M=Li, Na, Ca) arise from dispersion forces, electrostatic interactions, and hydrogen bonds.

Stacking Interactions between Square-Planar Metal Complexes with 2,2′-Bipyridine Ligands. Analysis of Crystal Structures and Quantum Chemical Calculations

“…Planar chelate rings can also form stacking interactions with other chelate rings. − We have found large number of chelate–chelate stacking interactions in the crystal structures from the CSD . The normal distances in chelate–chelate stacking interactions are similar to those found in stacking interactions between organic aromatic rings, while the offset of two interacting chelate rings can be different than between organic aromatic rings.…”

Chelated metal ions modulate the strength and geometry of stacking interactions: energies and potential energy surfaces for chelate–chelate stacking

“…[16][17][18][19][20][21] Moreover, it was shown that stacking interactions that involve nonaromatic rings or molecules have similar or even higher energies than aromatic stacking interactions. 20,[22][23][24] It has been shown that chelate rings of transition metals, which are of great interest to materials science [25][26][27] and crystal engineering, [28][29][30] can also form stacking interactions. 16,17,[31][32][33][34] Interactions of planar chelate rings with C 6 aromatic rings 16 and with other chelate rings 17 can be frequently found in crystal structures.…”

“…9 There were several studies that attempted to quantify the strength of intermolecular interactions of complexes with chelate rings, however, the interactions were not only stacking of chelate rings, but they involved simultaneously other interaction types, such as hydrogen bonds. 22,38 In this study, we provide the first report on isolated chelate-chelate stacking interaction energies calculated with CCSD(T) method at the complete basis set (CBS), which is considered the gold standard of quantum chemistry. 39,40 Preliminary data on potential energy surfaces for chelate-chelate stacking interactions were published in a recent review.…”

Electrochemical Oxidation of Glassy Carbon Provides Similar Electrochemical Response as Graphene Oxide Prepared by Tour or Hummers Routes

“…Many crystal structures of metal chelates are described18–28 and their interaction patterns with aromatic rings are generally known 21–25. It has been notoriously difficult to calculate the energies of the noncovalent interactions of metal chelates at high theoretical levels due to the overall size of the systems and due to presence of the metal ion 29. Our previous attempts resulted in energies of the stacking interaction of benzene with bis(acetylacetonato)nickel(II), determined at the local coupled cluster level [LCCSD(T)], which is less expensive than CCSD(T) 30…”