Introduction of Three Aryl Groups to Benzotriazinyl Radical by Suzuki–Miyaura Cross-coupling Reaction

Abstract

A new radical, 7-phenyl-1,3-bis(4-biphenylyl)-1,4-dihydro-1,2,4-benzotriazin-4-yl (2), was prepared from the iodo group-substituted benzotriazinyl radical 1 with phenyltriolborate salt by the Suzuki–Miyaura cross-coupling reaction at room temperature. An X-ray crystal structural analysis clarified its crystal structure. ESR measurements and DFT calculations revealed that its unpaired electron was more delocalized over the molecule than that of Blatter’s radical due to the substituent effect.

The Suppression of Columnar π-Stacking in 3-Adamantyl-1-phenyl-1,4-dihydrobenzo[e][1,2,4]triazin-4-yl

“…The redox behavior of radical 4 is typical of 1,2,4-benzotriazinyls exhibiting two fully reversible waves corresponding to the −1/0 and 0/+1 processes (Figure 2, left) [11,12,13,14,15,16,17,18,19,20,21,22]. Worthy of note is that the oxidation potential of E 1/2 0/+1 = 0.08 V vs Fc/Fc + couple makes radical 4 the best 1,2,4-benzotriazinyl donor reported to date.…”

“…The first 1,2,4-benzotriazinyl radical was reported by Blatter in 1968 (Blatter radical 1 , Chart 1) [1], and, aside from electrochemical studies by Neugebauer [2,3,4,5], this stable radical remained relatively obscure. Nevertheless, the recent development of improved syntheses of 1,2,4-benzotriazinyls [6,7,8,9,10] have led to numerous new derivatives, some of which display a range of low dimensional magnetic properties [11,12,13,14,15,16,17,18,19,20,21,22], while others have been used as radical initiators in polymer chemistry [23,24,25], and as sensors of picric acid [18].…”

“…The extensive delocalization of the singly occupied molecular orbital (SOMO) orbital density over the benzo-fused hydrazonyl and the N1-Ph (Figure 1), indicates that positive orbital overlap and π-stacking, can be achieved in a variety of different association modes, and a number of different solid-state packing motifs have been reported [11,12,13,14,15,16,17,18,19,20,21,22]. In the majority of crystals structures reported to date, 1,2,4-benzotriazinyls π stack to form 1-D columns.…”

Verdazyl Radical Building Blocks: Synthesis, Structure, and Sonogashira Cross‐Coupling Reactions

“…Pd‐catalyzed cross‐coupling reactions provide a much more versatile toolbox for the fine tuning of structure and properties of π‐conjugated radicals. Indeed, the Suzuki–Miyaura cross‐coupling reactions of both ortho ‐ and meta ‐iodophenyl‐nitronylnitroxide radicals were first demonstrated by Stroh et al and later applied for benzotriazinyl radicals by Yoshioka . Moreover, Heck and Sonogashira cross‐coupling reactions have been demonstrated for benzotriazinyls .…”

Magnetostructural Investigation of Orthogonal 1‐Aryl‐3‐Phenyl‐1,4‐Dihydrobenzo[e][1,2,4]triazin‐4‐yl Derivatives

“…Less attention has been paid to the modification of the N(1) substituent (Ar, Figure ) and its impact on crystal packing and magnetic properties. The N(1)−Ph ring has been substituted with a halogen and a Ph group in the para position . In the former case, the 4‐chloro substituent improved intermolecular contact in the stacks and resulted in significant antiferromagnetic exchange interactions.…”