Metallic monoboronyl compounds: Prediction of their structure and comparison with the cyanide analogues

Abstract

A theoretical study of monoboronyls of different metals has been carried out. We have chosen Mg as representative of s-block elements, Al for the p-block, and Group 11 metals (Cu, Ag, and Au) for the d-block. Different behaviors are observed: bonding through the oxygen atom is preferred in the case of Al, for all Group 11 monoboronyls bonding through the boron atom prevails and both interactions give rise to almost isoenergetic compounds in the case of Mg. Predictions for the spectroscopic parameters relevant for rotational and vibrational spectroscopy of the different competitive species are provided. Al and Group 11 boronyls have relatively high dissociation energies, whereas Mg boronyl has moderate dissociation energy. The molecular structure of metal boronyls has been rationalized through an analysis of the bonding. The similarities and differences between metal boronyls and their isoelectronic cyanide analogues have been discussed. © 2017 Wiley Periodicals, Inc.

Structural Trends in Monoboronyl Compounds: Analysis of the Interaction of Second-Row Elements with BO

“…70 The low values of the electronic charge density, ρ(r), and positive values of its Laplacian, ∇ 2 ρ(r), are indicative of a closed-shell interaction, whereas the negative value of the total energy density, H(r), suggests a certain character of covalent interaction. Therefore, as in previous studies, 29,70 the B−O bonds in the present case of second-row monoboronyls can be classified as mixed covalent/ionic interactions. As pointed out in a previous study, 29 this behavior is in contrast with that observed for the C−N bonds in cyanide/isocyanide compounds, which exhibits clear characteristics of mainly shared (covalent) interaction: high values of ρ(r), negative values of ∇ 2 ρ(r), negative values of H(r), and also relationships between the potential energy density and the kinetic energy density, V(r)/G(r), greater than 2.…”

“…Therefore, as in previous studies, 29,70 the B−O bonds in the present case of second-row monoboronyls can be classified as mixed covalent/ionic interactions. As pointed out in a previous study, 29 this behavior is in contrast with that observed for the C−N bonds in cyanide/isocyanide compounds, which exhibits clear characteristics of mainly shared (covalent) interaction: high values of ρ(r), negative values of ∇ 2 ρ(r), negative values of H(r), and also relationships between the potential energy density and the kinetic energy density, V(r)/G(r), greater than 2. Thus, although isoelectronic, CN and BO species show important differences in nature.…”

“…It is also worth pointing out that non-negligible values for the X–B bond indices in XOB compounds are observed, especially for the XOB isomers of sulfur and chlorine (0.10 and 0.16, respectively). These bond indices for nonadjacent atoms reflect through-atom antibonding interactions ,, and are observed for triatomic systems usually when the central atom is more electronegative than the other two atoms.…”

“…In fact, for the only species observed experimentally, ClBO, the agreement between the theoretical rotational constant (5202.2 MH) (including core−valence and relativistic corrections) and the experimental value (5202.3960 MHz) is very good. 29 Neglecting core−valence and relativistic corrections leads to a deviation of more than 20 MHz from the experimental value. Therefore, we think that it is worthwhile to include these corrections to obtain more reliable predictions.…”

Observation of π-Backbonding in a Boronyl-Coordinated Transition Metal Complex TaBO–

“…The chemical reactivities of the BO radical with organic molecules have also been investigated in crossed molecular beam experiments under single collision conditions. − The first boronyl metal complex to be synthesized in the bulk involved a BO ligand coordinated to a Pt atom, which was also protected by other bulky ligands . This landmark work has stimulated significant further interests in boronyl chemistry. − …”