Aromatic Borataheterocycles: Surrogates for Cyclopentadienyl in Transition-Metal Complexes

Abstract

This review describes the syntheses and coordination chemistry of selected unsaturated borataheterocycles. These compounds are formally derived from common heteroaromatic rings by the isoelectronic substitution of an anionic BHgroup for a neutral CH group. Specifically included are the five-membered rings 1,2-and 1,3-thiaborolyls, derived from thiophene, 1,2-oxaborolyl, derived from furan, and 1,2-azaborolyl, derived from pyrrole. Also included is the six-membered ring 1,2-azaboratabenzene, derived from pyridine. These anionic rings can serve as surrogates for cyclopentadienyl in organometallic compounds.

2‐Chloro‐Azaborolyl Anion: A Source of 1,2‐Azaborole Isosteric to Cyclopentadienylidene

“…1,2‐Azaboroles have been of considerable interest, since their anions ( B in Scheme ) is considered to possess aromaticity and can be used as π ligands. Since the first syntheses of 3 H ‐1,2‐azaboroles were reported by Schmid in 1980s,2 their syntheses, reactions and applications in coordination chemistry and catalysis have been expanded significantly by Schmid, Ash, Fu and others 1a. 3 The related studies on the five‐membered BN heterocycles with a four‐coordinate boron atom by Wang et al.…”

Rhodium and Iridium Aminoborane Complexes: Coordination Chemistry of BN Alkene Analogues

“…boryl complexes in hydro-and diboration, and in C À H activation). [10,11] Such comparisons can also be exploited in a predictive capacity, as in the case of the ligating properties of alkanes/amineboranes, with structural data being widely available only for the latter class of donor. relative trans influences, comparative reactivity towards electrophiles/nucleophiles) [6] for isoelectronic carbon/boroncontaining ligand families, e.g.…”

“…[1][2][3][4][5] Such studies have also allowed comparative assays of ligand properties and reactivity (e.g. [10,11] Such comparisons can also be exploited in a predictive capacity, as in the case of the ligating properties of alkanes/amineboranes, with structural data being widely available only for the latter class of donor. N-heterocyclic carbene/ boryl, [7,8] vinylidene/aminoborylene, [1] CO/BF, [9] and cyclopentadienyl/azaborolyl pairs.…”

A DFT study on 1,4‐dihydro‐1,4‐azaborinine annulated linear polyacenes: Absorption spectra, singlet‐triplet energy gap, aromaticity, and HOMO–LUMO energy modulation

“…Very recently, a theoretical study on 1,4‐dihydropyrazine annulated LPA systems has been done by us showed the effective use of N centers for band gap tuning in LPA mimics . Boron anion is effectively demonstrated as a substitute for carbon in the case of 5‐membered cyclopentadienyl rings . Boron incorporated thiophene‐based conjugated polymers have been synthesized .…”