Dipotassium and sodium/potassium crystalline picrate complexes with the crown ether 6,7,9,10,12,13,20,21,23,24,26,27-dodecahydrodibenzo[b,n][1,4,7,10,13,16,19,22]octaoxacyclotetracosin (dibenzo-24-crown-8)

Abstract

The crystal structures of the dipotassium and the mixed sodium/potassium picrate complexes with the crown ether dibenzo-24-crown-8 (DB24C8) were solved and found to be nearly identical. (I): NaKpicz(DB24C8), [NaK(C6H2N307)2(C24H3208)], Mr = 966.8, triclinic, P1, a = 8-164 (2), b = 9.960 (2), c= 13. structure. Na + is able to occupy an environment similar to that of K + under the conditions of these crystals, a situation not previously observed in the chemistry of crown ethers or macrocylic multidentates.

Unusual Two-Dimensional Sheet Structure of the Solvent-Free Cesium Aryloxide Complex CsO-2,6-i-Pr2C6H3

“…In addition, the 1 H NMR resonances of the meta and para protons of the aromatic ring were noticeably upfield shifted as compared to their chemical shift in typical transition metal complexes. Similar upfield shifting of resonances has been observed previously for arene rings coordinated to cesium cations. ,11h This observation, together with the lack of solvent molecules within the formulation of 1 , led us to undertake an X-ray diffraction study in order to determine the nature of the coordination environment about the cesium metal center.…”

“…Cs−C distances within the primary cesium−η 6 -arene interaction lie in the range 3.375(6)−3.622(6) Å, while interchain Cs−C contacts of 3.716(6) Å are made by the para carbon atoms of the aryloxide ring. These Cs−C distances lie within the range of 3.35(4)−4.12(1) Å found in other structurally characterized complexes containing Cs−arene interactions. 2g,5a,,,11h,i, The Cs−ring centroid distance of 3.24 Å in 1 is among the shortest yet reported, being comparable to the Cs−ring centroid distances of 3.21−3.34 Å found for the multiple Cs−η 6 -arene interactions in Cs 2 [La(O-2,6- i -Pr 2 C 6 H 3 ) 5 ] 9 and to the 3.24 Å observed in the cesium alkyl complex [Cs(MeOCH 2 CH 2 OCH 2 CH 2 OMe)] 2 [Ph 2 CCPh 2 ] 2g. This strong Cs−π-arene interaction presumably reflects the partial anionic character of the arene ring, since the Cs−ring centroid distance is considerably shorter than interactions that have been reported between cesium cations and neutral arene solvent molecules. 20g-i…”

“…Cs−O distances to the aryloxide ligands are 2.875(4) and 2.898(5) Å. These Cs−O distances are comparable to those observed in cesium picrate complexes, 11h,j,12h, and also to the Cs−O distance in tetrameric [Cs(O- t -Bu)] 4 (2.924 Å) . The Cs−arene interaction is quite asymmetric, with the cesium metal center being offset toward the para carbon (C(4)), away from the sterically demanding isopropyl groups in the 2,6-positions.…”

Laser spectroscopic study on (dibenzo-24-crown-8-ether)–water and –methanol complexes in supersonic jets

“…1,6,7 CEs also show other types of encapsulation, in which a guest species is enclosed by two CE molecules, 8,9 or two guests are held by one CE molecule. 10,11 The preferential capture of K + by 18C6 was originally observed in condensed phase. 12,13 However, in condensed phase, it is difficult to distinguish the dominant intermolecular interaction that controls the encapsulation.…”

Water-mediated conformer optimization in benzo-18-crown-6-ether/water system

“…1,6,7 Crown ethers also show the type of encapsulation in which a guest species is enclosed by two crown ethers, 8,9 or two guests are held by one crown ether. 10,11 Compared with the encapsulation of atomic guests such as alkali metal ions, the encapsulation of polyatomic molecular guests is much more complicated because of a variety of intermolecular interactions. The investigation of molecular guest encapsulation by crown ethers has been extensively performed in the condensed phase using several methods such as X-ray diffraction, IR spectroscopy, and Raman spectroscopy.…”