A Theoretical Study on Interaction of Cyclopentadienyl Ligand with Alkali and Alkaline Earth Metals

Abstract

Ab initio and density functional theory calculations are performed on half-sandwich (M-Cp) and sandwich (Cp-M-Cp) complexes of alkali and alkaline earth metals (M = Li, Na, K, Mg, and Ca) with cyclopentadienyl ligand (Cp). A comparison of dissociation energies demonstrates the ease of dissociation of the complex as ions in solvent phase and preference for dissociation as radicals in gas phase. Atoms in molecules analysis is used to characterize this cation-π interaction based on electron density values obtained at the cage critical point. The contribution of various components to the complex energy is estimated using reduced variational space analysis confirming maximum contribution from the coulomb exchange followed by contributions from polarization and charge transfer components of cyclopentadienyl ligand.

A first-principles investigation of histidine and its ionic counterparts

“…Recent studies on the cooperativity of non-covalent interactions reveal that the manifestation of cooperativity is essential to understand various phenomena such as formation of supramolecular assemblies, catalysis and biological functions [1,[21][22][23][24]. His is an important model for the understanding of cation-π interactions due to its imidazole side chain [25][26][27][28][29][30][31][32][33][34][35][36]. Recently, the conformational analysis of neutral His [37] and its tautomers [38] has been reported in the gas phase using first-principles calculations.…”

Probing the selective separation of potassium ion from sodium ion with cyclopentadienyl anion as receptor: a computational study

“…Again we calculated the binding energies and Gibbs free energies at MP2/6-31+G* level of theory in aqueous phase. Higher basis set 6-311++G(d,p) was also used with M06-2X and MP2 level of theory to calculate the binding energies in this study [53]. The binding energy ΔE (in kcal mol −1 ) for each complex is calculated as shown below.…”

“…DFT calculation has also been performed with alkali metal cyclopentadienyl complexes to study its vibrational spectra, electronic and structural properties [27]. The theoretical study has been adopted on half sandwich and sandwich complexes of alkali and alkali earth metals (Li, Na, K, Mg, and Ca) with cyclopentadienyl ligand to measure the role of solvent molecules for the dissociation of these complexes [53]. The calculated results showed the preferential dissociation of the complexes in solvent phase compared to the gas phase [53].…”

“…The theoretical study has been adopted on half sandwich and sandwich complexes of alkali and alkali earth metals (Li, Na, K, Mg, and Ca) with cyclopentadienyl ligand to measure the role of solvent molecules for the dissociation of these complexes [53]. The calculated results showed the preferential dissociation of the complexes in solvent phase compared to the gas phase [53]. Theoretical studies have been reported on the geometries, metal-ligand bond dissociation energies and the heats of formation of 20 sandwich and half sandwich complexes of the main group elements of group 1, 2, 13, 14, and Zn [54].…”

Induced Aromaticity and Electron-Count Rules for Bipyramidal and Sandwich Complexes of s- and d-Metals

“…In accordance with the principle of isolobal analogy [9] an apical irontricabonyl group in 4 can be replaced without loss of aromatic stability in the formed isostructural compound by other isolobal groups with two skeletal electrons to form, for example, stable pyramidal ( 4 C 4 H 4 )Be -complex 5 [10]. Analogously, stabilization of the three-dimensional *Address correspondence to this author at the Institute of Physical and Organic Chemistry at Southern Federal University, 344090 Rostov-on-Don, Russian Federation, Russian; Tel: +7(863)2434700; Fax: +7 8632 434 667; E-mail: minkin@ipoc.sfedu.ru aromatic cyclopentadiene-based pyramidal complex 6 is achieved via capping the five-membered ring with a tricarbonylmanganese group [6,11] with one skeletal electron and in the complex 7 with the univalent alkali-metal atoms [10,12,13]. At the same time, the replacement of the basal C n H n rings in sandwich and pyramidal systems with isolobal B n H 2n borane fragments results in metalloboranes [6,14,15], which are isostructural and isoelectronic to the hydrocarbon analogues.…”