Are Hetero‐metallapentalenes Aromatic or Not? A DFT Investigation

Abstract

Aromaticity is one of the most basic concepts in organic chemistry.T he planar Mçbiusa romatic metallapentalynes and metallapentalenes have attracted considerable attention in the past few years.H owever,t he aromaticity of metallapentalenes containing heteroatoms (such as B, N, and O), termed as hetero-metallapentalenes, is rarely studied. Herein, the stability and aromaticity of as eries of hetero-metallapentalenesa re theoretically investigated. The results reveal lower aromaticity in metallaborapentalene, comparable aromaticity in metallazapentalene, and nonaromaticity in metalloxapentalene relative to that of metallapentalene. Moreover,t he effect of Lewis bases on the aromaticity and stability of metallaborapentalene is discussed. These results provide useful information for experimental chemists to realize more hetero-metallapentalenes.Supporting information and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.Scheme1.ISE valuesofh etero-metallapentalenes. The values are given in kcal mol À1 .Scheme3.ISE valuesofN HC-, dimethylaminopyridine-,pyridine-, and acetone-coordinated osmaborapentalene.The values are given in kcal mol À1 .

Controlled Activation of Dipicolinyl-Substituted Propargylic Alcohol by Ru(II) and Os(II) for Unprecedented Indolizine-Fused Metallafuran Complexes

“…Notably, complexes 1f and 2f represent new family members of the metallafuran family. In the last three decades, metallaaromatic compounds have been subjected to intensive synthetic, reactivity and theoretical studies by pioneers including Roper, Bleeke, Wright, Jia, Xia, and Zhu. , Monocyclic metallafurans, being one of the main classes of metallaaromatics, are commonly synthesized via insertion of alkyne into metal–acyl complexes, C–H activation of α,β-unsaturated ketones, esters, aldehydes, or insertion of alkynone, alkynoate, allenoate, and alkynol into complexes with metal–hydride or metal–carbon double-/triple-bonded functionalities . Fused-ring metallafuran complexes are relatively less explored and are dominated by complexes with metal fragments as bridgeheads; representative examples are metallabenzofurans prepared from the postmodification of metallacyclopentadiene and metallapentalyne. , Complexes 1f and 2f not only are the first indolizine-fused metallafuran complexes but also represent rare examples of fused-ring metallafurans prepared in a one-pot manner.…”

Assembly of a Dihydrideborate and Two Aryl Nitriles to Form a C,N,N′-Pincer Ligand Coordinated to Osmium

“… 6 Furthermore, the disposition of their donor atoms at the metal coordination sphere allows them to develop a noticeable ability to form uncommon coordination polyhedra and favor unusual metal oxidation states. As a consequence, rare compounds have been recently discovered, such as the mer -tris(boryl) derivative Ir(Bcat) 3 {κ 3 - P , O , P -[xant(P i Pr 2 ) 2 ]} (xant(P i Pr 2 ) 2 = 9,9-dimethyl-4,5-bis(diisoproylphosphino)xanthene), which challenges the concept of trans influence, 7 and families of metallapentalenes, heterometallapentalenes, 8 and metallapentalynes, 9 with planar Möbius aromaticity.…”

“…Osmapentalenes and osmapentalynes are known. , However, pincer complexes of this element are scarce in comparison with the number of known compounds for the rest of the platinum-group metals. The pincer ligands coordinated to this element mainly involve neutral or monoanionic , moieties, which result from the simple coordination of tridentate molecules or the coordination of bidentate groups along with the σ-bond activation of one of their substituents, whereas osmium complexes bearing dianionic pincer ligands are very rare.…”