density functional calculations

Antiaromaticity-Promoted Activation of Dihydrogen with Borole Fused Cyclooctatetraene Frustrated Lewis Pairs: A Density Functional Theory Study

Aromaticity and frustrated Lewis pairs (FLP), two important concepts in chemistry, have attracted considerable attention from theoretical and experimental chemists. However, combining these two concepts together for H2 activation is less developed. Herein, we report a density functional theory study on antiaromaticity-promoted H2 splitting. The antiaromatic borole (as Lewis acid) and aromatic pyridine (as Lewis base) were introduced into the cyclooctetraene skeleton. Due to the geometric constraints, such systems can be classified as FLPs.

Probing the origin of adaptive aromaticity in 16‐valence‐electron metallapentalenes

Species with adaptive aromaticity are aromatic in the ground and lowest‐lying triplet excited states and they have normally intermediate singlet‐triplet gaps. Few examples of compounds with adaptive aromaticity are known to date, including 16‐valence‐electron (16e) metallapentalenes. A sweeping search could be conducted to discover new members of this group, but efficient designs with an explicit strategy would facilitate the quest for new members of this elusive family.

Cu-Catalyzed Aromatic Metamorphosis of 3-Aminoindazoles

We present a novel Cu-catalyzed aromatic metamorphosis of 3-aminoindazoles via oxidative cleavage of two C–N bonds of 3-aminoindazoles. This unprecedented reactivity of 3-aminoindazoles allows one to forge diverse nitrile-containing triphenylenes in decent yields via generation of the cyano group in situ. The current study reveals that 3-aminoindazoles could be harnessed as radical precursors via oxidative denitrogenation, the reaction mechanism of which was supported by density functional theory calculations.

Reaction Mechanisms on Unusual 1,2‐Migrations of N‐Heterocyclic Carbene‐Ligated Transition Metal Complexes

Unusual 1,2‐migration reactions of N‐heterocyclic carbene (NHC) on transition metals were investigated using density functional theory calculations. Our results reveal that the electronic properties, ring strain of the four‐membered ring, and aromaticity of NHC play crucial roles in the thermodynamics of such a 1,2‐migration.

Unconventional Aromaticity in Organometallics: The Power of Transition Metals

Aromaticity, one of the most fundamental concepts in chemistry, has attracted considerable attention from both theoreticians and experimentalists. Much effort on aromaticity in organometallics has been devoted to metallabenzene and derivatives. In comparison, aromaticity in other organometallics is less developed. This Account describes how our group has performed quantum chemical calculations to examine aromaticity in recently synthesized novel organometallic complexes.

Rational Design of a Carbon–Boron Frustrated Lewis Pair for Metal‐free Dinitrogen Activation

Molecular nitrogen (N2) is abundant in the atmosphere and nitrogen, found in many biomolecules, is an essential element of life. The Haber–Bosch process, developed over 100 years ago, requires relatively harsh conditions to activate N2 on the iron surface and generate ammonia for use as fertilizer or to produce other chemicals, leading to consumption of more than 2% of the world’s annual energy supply. Thus, developing approaches for N2 activation under mild conditions is particularly important and urgent.

Predicting an unconventional facile route to metallaanthracenes

Metallaaromatics have attracted considerable interest from both experimentalists and theoreticians since the first prediction of metallabenzenes, in which a CH group is replaced by a transition metal fragment. In comparison with monocyclic metallabenzenes and bicyclic metallanaphthalenes, tricyclic metallaanthracenes are quite less developed. Thus, it is urgent to explore synthetic methods for this rare system. Here we report a thorough investigation on the formation of metallaanthracenes from transition metal fluorenyl complexes via density functional theory calculations.

Rational Design and Synthesis of Unsaturated Se‐Containing Osmacycles with σ‐Aromaticity

Isolation of the simplest 4π three‐membered heterocycles (1H‐azirine, oxirene, thiirene, and selenirene) remains a big challenge due to their π‐antiaromaticity and significant ring strain. Here we demonstrate that the incorporation of a transition‐metal fragment could stabilize the antiaromatic selenirene and pentalene frameworks simultaneously by density functional theory (DFT) calculations. Experimental verification leads to the Se‐containing metallapolycycles, osmapentaloselenirenes, with remarkable thermal stability.

A theoretical study on the mechanism of ruthenium(II)-catalyzed phosphoryl-directed ortho-selective C–H bond activations: the phosphoryl hydroxy group triggered Ru(II)/Ru(0) catalytic cycle

Using density functional theory (DFT) calculations, the present study explores the mechanisms of two ruthenium(II)-catalyzed phosphoryl-directed ortho-selective C–H bond activation reactions. Depending on the nature of the phosphoryl groups, namely R2P(O) versus RP(O)OH, two different products could be selectively synthesized. For R2P(O), the overall catalytic cycle includes three basic steps: C–H bond activation, alkyne insertion, and protonation. The oxidation state of the Ru center does not change during this catalytic process.

Metallapentalenofurans and Lactone-Fused Metallapentalynes

Metalla-aromatics are attractive species because they exhibit the properties of both organometallics and aromatics. Reported metal-bridged polycyclic aromatic complexes, as well as Möbius aromatic species, are still rare. Herein, we present the construction of two new metal-bridged polycyclic aromatic frameworks, α-metallapentalenofurans and lactone-fused metallapentalynes, by the reactions of osmapentalyne with terminal aryl alkynes in the presence of H2O or HBF4/H2O, respectively.