Group 3 and Lanthanide Boryl Compounds: Syntheses, Structures, and Bonding Analyses of Sc−B, Y−B, and Lu−B σ-Coordinated NHC Analogues

Abstract

Reaction of [Ln(CH(2)SiMe(3))(2)(THF)(n)][BPh(4)] (Ln = Sc, Y, Lu ; n = 3, 4) with Li{B(NArCH)(2)}(THF)(2) (Ar = 2,6-C(6)H(3)(i)Pr(2)) formed the first group 3 and lanthanide boryl compounds, Sc{B(NArCH)(2)}(CH(2)SiMe(3))(2)(THF) and Ln{B(NArCH)(2)}(CH(2)SiMe(3))(2)(THF)(2) (Ln = Y, Lu), which contain two-center, two-electron Ln-B σ bonds. All of these systems were crystallographically characterized. Density functional theory analysis of the Ln-B bonding found it to be predominantly ionic, with covalent character in the σ-bonding Ln-B HOMO.

An Alumanylyttrium Complex with an Absorption due to a Transition from the Al−Y Bond to an Unoccupied d‐Orbital

“…The Y−O and Y−C bonds in 2 are similar to those of previously reported five‐coordinated Y complexes (see the Supporting Information), which indicates that the structural factors around Al atom do not perturb the electronic structure of the Y atom. The C‐Al‐Y‐C torsion angles of 2 (7.4(1), 8.0(2)°) are close to zero, and stand thus in stark contrast to a previously reported (boryl)Y(CH 2 SiMe 3 ) 2 (thf) 2 complex ( 4 ), which exhibits an almost orthogonal torsion angle between the boron plane and the equatorial plane around the Y atom (−73.4(3)°).…”

“…In contrast, the LUMO consists of significantly overlapping vacant 3p‐ and 4d‐orbitals of the Al and Y atoms, respectively, due to the strong electron affinity of the Al atom. The HOMO level of 2 (−4.62 eV) is higher than that of 4 (−5.02 eV), when calculated at the same level of theory (Figure ; for details, see the Supporting Information) due to the stronger σ‐donor ability of the Al atom relative to that of the B atom, which is based on the difference in electronegativity of these atoms . The LUMO level (−1.176 eV) of 2 is lower than that of 4 (−0.461 eV) due to the effective overlapping of the vacant orbitals between the Al and Y atoms in 2 and π‐bonding interaction between the N and B atoms in 4 (Figure S4, Supporting Information).…”

“…To reveal the substituent effect of the dialkylalumanyl ligand in 2 , the UV/Vis spectrum of independently synthesized Y(CH 2 SiMe 3 ) 3 (thf) 3 was measured in cyclohexane, albeit that an absorption beyond 300 nm was not observed. Additionally, the HOMO–LUMO transition of the previously reported “pale yellow microcrystalline powder” of 4 was estimated to be at 304 nm based on time‐dependent (TD)‐DFT calculations (Figure S6, Table S4, Supporting Information). Thus, the introduction of the dialkylalumanyl ligand to the yttrium atom narrows the HOMO–LUMO gap of the d 0 ‐complex without π‐electrons and results in a visible absorption.…”

Computational study of An–X bonding (An = Th, U; X = p-block-based ligands) in pyrrolic macrocycle-supported complexes from the quantum theory of atoms in molecules and bond energy decomposition analysis

“…31 Finally for our pruposes, the delocalisation index between atoms A and B δ(A,B) gives the number of electrons shared between two atomic basins and is a measure of the bond order between two atoms. 32 The QTAIM has been previously applied to a range of actinide-ligand and other metal-ligand bonds 18,[33][34][35][36][37][38][39] and it has been concluded that while An bonding is predominantly ionic, covalency differences across the 5f series can be distinguished.…”

Organoaluminium‐Boryl‐Komplexe

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Metallvermittelte Borylierungen nehmen in vielen katalytischen organischen Prozessen eine Schlüsselrolle ein, weshalb isolierbare Metall-Boryl-Komplexe als besonders interessante Zielverbindungen in der experimentellen und mechanistischen Organometallchemie gelten. [5b, 8] Die Reihe der Metall-Boryl-Komplexe wurde kürzlich auf die Seltenerdmetalle erweitert, als Mountford et al und Hou et al unabhängig voneinander die ersten Boryl-Komplexe der Gruppe 3 und der Lanthanoide [Ln{B(NArCH) 2 }(CH 2 SiMe 3 ) 2 (THF) n ] (Ln = Sc, [10,11] Y, Lu, [10] Gd, [11] n = 1 (Sc), 2 (Y, Lu, Gd)) gemäß einer "Ladungsneutralisierungsreaktion" erhielten, indem sie [Ln(CH 2 SiMe 3 ) 2 (THF) n ] + [BPh 4 ] À -Salze als Ausgangsstoffe verwendeten und sich die Fällung von LiBPh 4[12] zunutze machten.Interessanterweise scheint (THF) 2 Li{B(NArCH) 2 } (1) bislang das einzige Reagens zu sein, das für weitere Umset-Schema 1. [2] Schließlich war es die bahnbrechende Entdeckung des Bor-zentrierten anionischen Nukleophils (THF) 2 Li{B(NArCH) 2 } (1, Ar = C 6 H 3 iPr 2 -2,6) [3] im Jahr 2006, welche seitdem eine faszinierende Metall-Boryl-Chemie eingeleitet hat.

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