A new fundamental type of conformational isomerism

作者：Canfield, Peter J.; Blake, Iain M.; Cai, Zheng-Li; Luck, Ian J.; Krausz, Elmars; Kobayashi, Rika; Reimers, Jeffrey R.^*; Crossley, Maxwell J.^*

来源：Nature Chemistry, 2018, 10(6): 615-624.

DOI：10.1038/s41557-018-0043-6

• DENSITY-FUNCTIONAL THEORY
• PORPHYRIN COMPLEXES
• ISOMERIZATION MECHANISM
• BINUCLEATING LIGAND
• DIBORON CORROLES
• CHARGE-TRANSFER
• PHASE ISOMERS
• STEREOCHEMISTRY
• ROTATION
• INVERSION

Isomerism is a fundamental chemical concept, reflecting the fact that the arrangement of atoms in a molecular entity has a profound influence on its chemical and physical properties. Here we describe a previously unclassified fundamental form of conformational isomerism through four resolved stereoisomers of a transoid (BF)O(BF)-quinoxalinoporphyrin. These comprise two pairs of enantiomers that manifest structural relationships not describable within existing IUPAC nomenclature and terminology. They undergo thermal diastereomeric interconversion over a barrier of 104 +/- 2 kJ mol(-1), which we term 'akamptisomerization'. Feasible interconversion processes between conceivable synthesis products and reaction intermediates were mapped out by density functional theory calculations, identifying bond-angle inversion (BAI) at a singly bonded atom as the reaction mechanism. We also introduce the necessary BAI stereodescriptors parvo and amplo. Based on an extended polytope formalism of molecular structure and stereoisomerization, BAI-driven akamptisomerization is shown to be the final fundamental type of conformational isomerization.

• 出版日期2018-6
• 单位上海大学