Electride Characteristics of Some Binuclear Sandwich Complexes of Alkaline Earth Metals, M₂(η⁵-L)₂(M = Be, Mg; L = C₅H₅^–, N₅^–, P₅^–, As₅^–)

Abstract

Ab initio calculations have been performed for a series of binuclear sandwich complexes, M 2 (η 5 -L) 2 . It has been observed that the eclipsed and staggered conformations have almost equal amount of energies. The M−M bond lengths are comparable with those in the free M 2 molecules (M = Be, Mg). The nuclear-independent chemical shift (NICS) values indicate the aromaticity of these complexes. The stability of Be 2 (η 5 -L) 2 complexes is higher than that of the Mg 2 (η 5 -L) 2 complexes. The natural bond orbital (NBO) analysis and electron density descriptors proved the existence of a single covalent M−M bond in an M 2 2+ fragment. It has been observed that each M−M bond contains a non-nuclear attractor (NNA) at the center of the respective bond. The Laplacian of electron density [∇ 2 ρ(r)] is negative at the NNAs. The energy decomposition analysis (EDA) showed that M 2 2+ and 2L − represent the bonding interaction in the complexes. All of the designed binuclear sandwich complexes behave as electrides.

CB6Al0/+: Planar hexacoordinate boron (phB) in the global minimum structure

“…Although there are many methods to ascertain the aromaticity of a molecular motif, nucleus independent chemical shift (NICS), harmonic oscillator model of aromaticity (HOMA), multicenter bond index (MCI), and electron localization function (ELF) are mostly used. 69–73 In this work, the NICS values of the designed systems are discussed. The concept of NICS was first given by Schleyer et al NICS(0) and NICS(1) correspond to the NICS values at the center of a ring and 1 Å above the ring, respectively.…”

New kind of electride sandwich complexes based on the cyclooctatetraene ligand M12(η8-C8H8)2M22(M1= Na, K and M2= Ca, Mg): a theoretical study

“…The computed value of our system also agrees with the ELF values of electride sandwich complexes reported previously (Table S3, ESI†). 38…”

“…The BP86 functional is chosen for the study as it was previously used for studying the aromaticity of the sandwich complexes. 38,73 Herein, both the NICS (0) and NICS (1) are calculated for the studied complex using the optimized structure, putting the ghost atom at the ring and 1 Å above the ring. Natural population analysis is performed by natural bond orbital analysis (NBO) 74 to comprehend the charge distribution on the atoms of the studied complexes.…”

Molecular Electrides: An In Silico Perspective

“…Four isoelectronic ligands (L) C 5 H 5 − , N 5 − , P 5 − , As 5 − were taken to bind with the alkaline earth metals (M=Be and Mg) through the most stable η 5 modes, and the complexes are denoted as M 2 ( η 5 ‐L) 2 [192] . The M 2 (C 5 H 5 ) 2 as the representative of this series is shown in Figure 5(h).…”