Anion-π interactions in five-membered rings: a combined crystallographic and ab initio study (original) (raw)
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Theoretical ab initio study of anion–π interactions in inorganic rings
Chemical Physics Letters, 2012
Complexes of anions with several six-membered inorganic rings with more or less aromatic character have been optimized at the RI-MP2/aug-cc-pVDZ level of theory. The rings studied are hexazine (N 6), boroxine (B 3 O 3 H 3), borazine (B 3 N 3 H 6), 1,3,5,2,4,6-triazatriborinine (B 3 N 3) ring, and borthiin (B 3 S 3 H 3). The anion-p complexes are energetically favorable and the interaction has been characterized by means of the Bader's theory of 'atoms-in-molecules' and partitioning the energy using the SAPT method. Experimental evidence of the importance of this interaction in some inorganic rings has been obtained from the Cambridge Structural Database.
Anion-π Interactions Involving [MX n ] m − Anions: A Comprehensive Theoretical Study
ChemPhysChem, 2013
In this manuscript we perform a systematic study on the geometric and energetic features of anion-π complexes, wherein the anion is a metal complex of variable shapes and charges. Such a study is lacking in the literature. For the calculations we used the ab initio RI-MP2/def2-TZVPP level of theory. A search in the Cambridge Structural Database (CSD) provides the experimental starting point that inspired the subsequent theoretical study. The influence of [MX(n)](m-) on the anion-π interaction was analyzed in terms of energetic, geometric, and charge transfer properties and Bader's theory of "atom-in-molecules" (AIM). The binding energy depends on the coordination index, geometric features and different orientations adopted by the metallic anion. The binding mode resembling a stacking interaction for linear, trigonal planar and square-planar anions is the most favorable. For tetrahedral and octahedral anions the most favorable orientation is the one with three halogen atoms pointing to the ring.
Anion Binding Involving π-Acidic Heteroaromatic Rings
Accounts of Chemical Research, 2007
Anions are essential species in biological systems and, particularly, in enzyme-substrate recognition. Therefore, the design and preparation of anion receptors is a topical field of supramolecular chemistry. Most host-guest systems successfully developed are based on noncovalent (ionic and hydrogen-bonded) interactions between anions and ammonium-type functionalities or Lewis acid groups. However, since the past 5 years, an alternative route toward the synthesis of efficient anion hosts has emerged, namely, the use of "anion-π" interactions involving nitrogen-containing electrondeficient aromatic rings, as the result of several favorable theoretical investigations. In this Account, the state of the (new) art in this growing area of anion-binding research is presented and several selected examples from our work and that of other groups will be discussed.
Chemical Physics Letters, 2004
Several complexes of benzene with cations and hexafluorobenzene with anions have been optimized at the MP2/6-31++G**, B3LYP/6-31++G** and HF/6-31++G** levels of theory. Different aspects of the cation-p interaction have been compared to those of anion-p, including changes in the aromaticity of the ring upon complexation, charge-transfer effects using the Merz-Kollman charges and the contribution of dispersion energies by comparing the complexation energies computed at the B3LYP and MP2 levels of theory.
Crystallographic evidence of theoretically novel anion–π interactions
New J. Chem., 2006
The reaction of Cu(NO 3) 2 Á 3H 2 O with the multidentate ligand N,N 0 ,N 00 ,N 0 0 0-tetrakis{2,4-bis (di-2-pyridylamino)-1,3,5-triazin-6-yl} triethylenetetramine (dpatta) in acetonitrile at high temperature and pressure results in the formation of the tetranuclear coordination compound [Cu 4 (dpatta)(NO 3) 4 ](NO 3) 4 Á 12H 2 O (1), whose crystal structure exhibits remarkable anion-p interactions which have been calculated, considering the unexpected position of the anion toward the aromatic ring.
Towards understanding π-stacking interactions between non-aromatic rings
IUCrJ
The first systematic study of π interactions between non-aromatic rings, based on the authors' own results from an experimental X-ray charge-density analysis assisted by quantum chemical calculations, is presented. The landmark (non-aromatic) examples include quinoid rings, planar radicals and metal-chelate rings. The results can be summarized as: (i) non-aromatic planar polyenic rings can be stacked, (ii) interactions are more pronounced between systems or rings with little or no π-electron delocalization (e.g. quinones) than those involving delocalized systems (e.g. aromatics), and (iii) the main component of the interaction is electrostatic/multipolar between closed-shell rings, whereas (iv) interactions between radicals involve a significant covalent contribution (multicentric bonding). Thus, stacking covers a wide range of interactions and energies, ranging from weak dispersion to unlocalized two-electron multicentric covalent bonding (`pancake bonding'), allowing a fac...
Chem. Soc. Rev., 2008
This tutorial review provides an overview of the theoretical and experimental investigations that resulted in the recognition of anion-p interactions, i.e., non-covalent forces between electron deficient aromatic systems and anions. Several pioneering theoretical studies revealed that these interactions are energetically favorable (y20-50 kJ mol 21). Anion-p interactions are gaining significant recognition, and their pivotal role in many key chemical and biological processes is being increasingly appreciated. The design of highly selective anion receptors and channels represent important advances in this nascent field of supramolecular chemistry.