A Tale of Two Stabilities: How One Boron Atom Affects a Switch in Bonding Motifs in CeO₂B_x^– (x = 2, 3) Complexes

Abstract

Boronyl (BO) ligands have garnered much attention as isoelectronic and isolobal analogues of CO and CN–, yet successful efforts in synthesizing metal boronyl complexes remain scarce. Anion photoelectron (PE) spectroscopy and density functional theory calculations were employed to investigate two small CeO2B x – (x = 2, 3) complexes generated from laser ablation of a mixed Ce/B pressed powder target. The spectra reveal markedly different bonding upon incorporation of an additional B atom. Most interestingly, CeO2B2 – was found to have a Ce­(I) center coordinated to two monoanionic boronyl ligands in a bent geometry. This result was unexpected as previous studies suggest electron-rich metals are most suitable for stabilizing such ligands; furthermore, it is one of the first examples of an experimental metal–polyboronyl complex. Introducing another boron atom, however, favors a much different geometry in which Ce­(II) coordinates an O2B3 3– unit through both the O and B atoms, which was evident in the markedly different PE spectra.

On the Linear Geometry of Lanthanide Hydroxide (Ln—OH, Ln=La-Lu)

“…26 Similar studies performed on AnC2 and AnCl3 have also implicated actinide 5f orbitals in bond formation. [26][27][28][29][30][31][32] Motivated by our lab's recent interest in metal oxide clusters, [33][34][35][36][37][38] we were intrigued by an apparent dearth of literature exploring the structure and bonding of lanthanide hydroxides. With the goal of exploring the full series, we note the inclusion of PmOH; while included here for completeness, Pm is unstable and thus PmOH is not likely to be experimentally studied.…”

Photoelectron Spectra of Gd2O2− and Non-Monotonic Photon-Energy Dependent Variations in Populations of Close-Lying Neutral States

“…Transitions in manifold I in the 3.495 eV PE spectrum: Based on previous work, [21][22][23][24][25][26][27][28][29] homo-and heteronuclear lanthanide oxide cluster anions with average metal oxidation state less than +3 exhibit photodetachment transitions around e − BE  1 eV. The transitions can be described as creating a hole in a 6s-based molecular orbital.…”

∆SCF Dyson Orbitals and Pole Strengths from Natural Ionization Orbitals

“…Work from our lab in collaboration with experimental colleagues considering such experiments, for example, has led to detailed understanding of a number of transition metal and inner-transition metal containing systems. [19][20][21][22][23][24][25] Particularly because electron number changes in electron detachment and electron attachment, the quality of electronic structure theory studies of such processes can be quite sensitive to electron correlation treatment. [26][27][28] Early approaches specifically designed to address this concern implemented wave function models beyond the Hartree-Fock (HF) self-consistent field (SCF) model.…”

“…As our own work has shown, access to these additional handles is critical for discriminating between spectral candidates and making definitive spectral assignments. [19][20][21][22][23][24] A particular advantage of EPT models in electron detachment/attachment studies has been their direct relationship to the Dyson orbital framework. Dyson orbitals, also referred to as generalized overlap amplitudes, are defined as the overlap between n el and n el = (n el −1) wave functions.…”

“…Indeed, over the last few years we have employed NIO analysis in studies of complicated photoelectron spectra of transition metal and lanthanide containing clusters. 20,21,[23][24][25]83,84 In this report, we develop a formal relationship between the NIO model and the Dyson orbital theory. Importantly, this work establishes a clear and concise connection between the 71,85 More recently, our lab proposed an orbital description for electron detachment processes studied with ΔSCF approaches based on a natural orbital transformation of the difference density from initial and final states, which we named the NIO model.…”