Influences of the substituents on the M–M bonding in Cp₄Al₄ and Cp₂M₂X₂ (M = B, Al, Ga; Cp = C₅H₅, X = halogen)

Abstract

Although the geometries of CpAl4 (Cp* = C5Me5) and Cp4Al4 (Cp = C5H5) are similar, CpAl4 is more stable than Cp4Al4. CpAl2I2 is the first complex involving an Al(ii)-Al(ii) bond to be supported by Cp-type ligands. In this work, the stability of CpAl4 and Cp4Al4 (Cp = C5H5), the nature of M-M bonding in Cp2M2X2 (M = B, Al, and Ga), and the influences of the X atom on the M-M bonds have been analyzed and compared within the framework of the atoms in molecules (AIM) theory, electron localization function (ELF), energy decomposition analysis (EDA), and natural bond orbital (NBO) analysis. The calculated results show that CpAl4 is more stable than Cp4Al4 because of HH interactions between the methyl groups on the same and different Cp rings and not because of the Al-Al bonds. In Cp2M2X2, the B-B bond is stronger than the Al-Al and Ga-Ga bonds. The B-B bond is most consistent with covalent bonding, whereas the Al-Al and Ga-Ga bonds are more consistent with metallic bonding. The strengths of the B-B bond increase in the sequence X = F, Cl, Br, and I, whereas the Al-Al and Ga-Ga bonds decrease in the sequence X = F, Cl, Br, and I. The different change tendencies arise from the different M-M bonds and the orbital interactions between atoms X and M.

Intriguing E…E' bonding in [Nap(EPh)(E'Ph)]•+(E, E'=O, S, Se, Te)

“…Topological approaches such as the AIM theory and ELF analysis have emerged and enabled investigation of chemical bonding . The AIM theory uses novel descriptors such as the electron density distributions at the bond critical point (BCP) to provide deeper insight into the nature of a chemical bond.…”

“…Topological approaches such as the AIM theory [27,28] and ELF [35][36][37] analysis have emerged and enabled investigation of chemical bonding. [38][39][40] The AIM theory uses novel descriptors such as the electron density distributions at the bond critical point (BCP) to provide deeper insight into the nature of a chemical bond. ELF is a robust descriptor of chemical bonding based on topological analyses of local quantum mechanical functions related to the Pauli exclusion principle.…”

Stress-energy tensor of the quantized massive fields in Friedman-Robertson-Walker spacetimes

“…Moreover, by construction, it depends functionally on the metric tensor allowing, in principle, to solve the semiclassical Einstein field equations in a self-consistent way. (10) and treating them as free parameters one arrives at the action functional considered by Lu and Wise [22] in the black hole context 1 On the other hand, by retaining only α 9 term in (10) one obtains the Goroff-Sagnotti effective action [23] studied by Dobato and Maroto [24].…”

“…The scalar case is slightly more complicated because of the coupling constant ξ. Indeed, inspection of (22) shows that it is positive for ξ < ξ crit = 0.1023 and hence there is no solution for the conformally coupled scalar field. The temporal evolution of the model is governed by (20).…”

Theoretical assessing on the coordination mode and bonding in heteronuclear group‐13 dimetallocene

“…In our previous work, the geometries and the influences of the substituents on the MM bonding in the homonuclear group‐13 dimetallocenes Cp 2 M 2 X 2 (M = B, Al, Ga; Cp = C 5 H 5 , X = halogen) have been discussed . It is found that the Cp 2 M 2 X 2 (M = B, Al, Ga; X = F, Cl, Br, I) possess the C 2 symmetry.…”