Blue emissive amidinate-based tetra-coordinated boron compounds

Abstract

A series of novel amidinate ligated four-coordinate boron compounds, [(Ar)-C(tBuN)2BF2] (1BF2-6BF2) were synthesised and structurally characterised (Ar = 1-phenyl, 2-naphthyl, 2-anthryl, 9-anthryl, 9-phenanthryl and 1-pyrene). The increased π- conjugation of...

Boron Complexes with Propiolamidinato Ligands: Synthesis, Structure, and Photophysical Properties

“…The bite angles of the chelate ligands oscillate between 102° and 103°, and the N1–B1–N2 angle oscillates in the range of 78–80°, agreeing with those of the analogous reported compounds. 5 , 6 , 17 In complexes 4a – c , the methyl groups of the isopropyl point toward the boron sphere, whereas in complex 4e , one of the isopropyl groups points to the boron atom and the other is focused backward. The C–N bond distances are intermediate between those anticipated for single and double bonds, which is indicative of delocalization at the amidinate core (C–N, ∼1.3 Å; the sum of the bond angles around C1 is ∼360°).…”

“…In the very recent past and during the course of this work, Chandrasekhar et al have described a series of new luminescent boron compounds with amidinato ligands, of the type [Ar-C­(tBuN) 2 BF 2 ], in which the effect of increasing the level of π-conjugation for different polycyclic aromatic substituents has been studied. In all cases, the compounds were photoemissive only in the blue region …”

“…In all cases, the compounds were photoemissive only in the blue region. 17 Given the novelty and potential interest of these types of compounds, our intention was to develop procedures that allow for greater modification of the amidinato ligands and to study the effect on their luminescent properties. Here we report the use of either catalytically or stoichiometrically synthesized propiolamidines, as sustainable methods, to prepare and structurally characterize a certain number of new boron amidinato complexes, paying special attention to how amidinato ligands coordinate to the boron center depending on their nature, and finally, we explore their photophysical properties.…”

Diverse Reactivity of Amidinate-Supported Boron Centers with the Hypersilyl Anion and Access to a Monomeric Secondary Boron Hydride

“…Within the domain of p -block chemistry, group 13 and group 14 metal halide and metal–alkyl fragments have been well established using the amidinate ligand scaffold. For example, amidinate-supported silylenes have been reported for various small molecule activation and hydroboration reactions, ,− and amidinate-supported alkyl aluminum cations have been shown as active catalysts for olefin polymerization. , In addition, amidinate-based tetra-coordinated boron compounds have also been proven to act as photoluminescent materials and have been shown to activate gaseous CO and CO 2 , as well as carbonyl and nitrile functional groups . Surprisingly, a survey of known amidinate boron compounds reveals that the majority of amidinate boranes contain either halogen, ,, Ph, , or Me groups at the boron center (Scheme A).…”

“…For example, amidinate-supported silylenes have been reported for various small molecule activation and hydroboration reactions, ,− and amidinate-supported alkyl aluminum cations have been shown as active catalysts for olefin polymerization. , In addition, amidinate-based tetra-coordinated boron compounds have also been proven to act as photoluminescent materials and have been shown to activate gaseous CO and CO 2 , as well as carbonyl and nitrile functional groups . Surprisingly, a survey of known amidinate boron compounds reveals that the majority of amidinate boranes contain either halogen, ,, Ph, , or Me groups at the boron center (Scheme A). We hypothesize that alternative reactivity or catalytic activity of amidinate-supported boranes could be achieved by adding strong σ-donor ligands and effectively reducing the HOMO–LUMO gap .…”