Preparation of double decker {Li3(Cl-)(Hhp)}22- dianions and H2TPCor- monoanions by deprotonation of free-base trithiododecaazahexaphyrin (H3Hhp) and triphenylcorrole (H3TPCor) macrocycles

Deprotonation of free-base [30]trithia-2,3,5,10,12,13,15,20,22,23,25,30-dodecaazahexaphyrin (hemi-hexaphyrazine, H(3)Hhp) and 5, 10, 15-triphenylcorrole (H(3)TPCor) macrocycles by an excess of lithium diethylamide, LiNEt2, in the presence of three equivalents of cryptand[2.2.2] has been studied. Crystallization of the obtained products after the reaction allows the isolation of crystalline {Cryptand [2.2.2](Li)}(2){Li3Cl(Hhp)}2 center dot 6C(6)H(4)Cl(2) (1) and {Cryptand[2.2.2](Li)} {H(2)TPCor)similar to 0.5C(6)H(4)Cl(2) (2) salts. Compound 1 is the first example of lithium derivative of hemihexaphyrazine which additionally coordinates one Cl- anion per three lithium ions. There are five (Li+)center dot center dot center dot(Cl-) contacts of 2.389(4)-2.456(4) angstrom length for two independent {Li3Cl(Hhp)}(similar to) anions. However, one contact elongates to 2.557(4) angstrom due to shift of Cl- anions towards two hydrogen atoms of cryptand[2.2.2] providing the formation of weak hydrogen (Cl-)center dot center dot center dot H(cryptand) bonds. Two {Li3Cl(Hhp)}(-) anions are arranged in the double decker {Li3Cl (Hhp)}(2)(2) structure due to that the Cl- anion of one Li3Cl(Hhp) unit forms additional weak (Li+)center dot center dot center dot(Cl-) contacts of 2.586-2.617(4) angstrom with two lithium ions of the second {Li3Cl(Hhp)}(-) unit. In contrast to H(3)Hhp, H(3)TPCor splits only one hydrogen atom at deprotonation in the same experimental conditions forming a planar H(2)TPCor anion and, therefore, H(3)Hhp has higher acidity of central hydrogen atoms in comparison with H(3)TPCor. Deprotonation preserves diamagnetic state of pristine macrocycles in salts 1 and 2. Their optical properties are also discussed. DFT calculations were carried out for 1 to discuss aromaticity of the macrocycles, electronic structure and optical spectrum of 1. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Deprotonation of two macrocycles, H(3)Hhp and H(3)TPCor, using LiNEt2 and cryptand[2.2.2] resulted in the formation of salts containing lithium ions and chloride ions. Compound 1 is the first example of a lithium derivative of hemihexaphyrazine, with a unique crystal structure.