化学
酰胺
加合物
位阻效应
分子内力
氢键
超分子化学
脱质子化
二聚体
药物化学
分子
光化学
溶剂
立体化学
有机化学
离子
作者
Alvaro Calderón‐Díaz,Janet Arras,Ethan T. Miller,Nattamai Bhuvanesh,Colin D. McMillen,Michael Stollenz
标识
DOI:10.1002/ejoc.202000207
摘要
Sterically crowded tetradentate bis(amidines) encapsulate their N–H functionalities or unveil them to undergo inter‐ and intramolecular hydrogen bonding both in solid state and solution, depending on a subtle interplay between the amidine backbone substituents. X‐ray crystallography reveals for four distinct ZZ ( syn/syn ) and EE ( syn/syn ) bis(amidines) that bulky terminal N ‐Mes groups in combination with N 2 C‐ t Bu or N 2 C‐Ph substituents result in steric protection of the N–H moieties, whereas less crowded terminal p ‐ t Bu(C 6 H 4 ) groups either show encapsulation ( N 2 C‐ t Bu) or hydrogen bonding ( N 2 C‐Ph), the latter resulting in a bis(amidine) dimer formed by inter‐ and intramolecular hydrogen bonds. Moreover, a supramolecular solvent adduct consisting of one bis(amidine) and four ethanol molecules is presented. DFT calculations show that both the dimerization and formation of the solvent adduct is associated with a significant energy gain (dimerization: ΔE = –27.7 kcal/mol; formation of ethanol adduct: ΔE = –64.3 kcal/mol). The corresponding four Li bis(amidinates) are weakly blue to green‐emissive in THF solution. Overall, a new series of highly flexible bis(amidines) has been examined.
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