Cobalt bis(dicarbollides)(1-) covalently attached to the calyx[4]arene platform: the first combination of organic bowl-shaped matrices and inorganic metallaborane cluster anions

Bohumír Grüner, Libor Mikulasek, Jirí Baca, Ivana Cisarova, Volker Böhmer, Crenguta Danila, M.M. Reinoso garcia, Willem Verboom, David Reinhoudt, Alessandro Casnati, Rocco Ungaro

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Abstract

Various calix[4]arene and resorc[4]arene ionic compounds substituted by cobalt bis(dicarbollide) anions (1) have been prepared for the first time. From tBu-calix[4]arene (A) the complete series of mono-, di-, tri- and tetrasubstituted derivatives bearing one to four cluster anions on the lower rim (3-6) have been obtained in the form of their alkali-metal salts by O-alkylation with the 1-dioxane derivative [8-O(CH2CH2)2O(+)-1,2-C2B9H10)-(1',2'-C2B9H11)-3,3'-Co] (2), all of which are syn or cone isomers. In contrast, disubstitution of the dipropyl ether of tBu-calix[4]arene (B) led to a mixture of the cone and 1,3-alternate conformers 7a and 7b, respectively. Starting from tetrapropoxy-calix[4]arene functionalised at the upper rim by carboxylic acid groups in distal positions (C) and an amino-bridged derivative [8,8'--H2N<(1,2-C2B9H10)2-3,3'-Co] (8), calix[4]arene 9, disubstituted at the upper rim, was obtained as the main product along with the monosubstituted species 10. Di- and tetrasubstituted ionic products (11-15) were also obtained from resorcarene-based cavitands by O-alkylation with the 1-dioxane derivative 2. A pair of regioisomeric disubstitution products, 11a,b, was isolated in the case of the hydroxy cavitand D, while E, functionalised by hydroxymethyl groups on the wide rim, and F, bearing hydroxy groups on the alkylidene bridges, gave the 1,3-di- (12 and 14) and the tetrasubstituted compounds (13 and 15), respectively. The molecular structure of the electroneutral dicaesium complex of the dianion 4 was determined by single-crystal X-ray diffraction analysis. The two Cs+ cations are found in different coordination spheres in the structure of Cs24. Coordination of the Na+ cation by the diethylene glycol chain and one calixarene lower rim oxygen atom was found in the crystal structure of the Na complex of the monoanion 3.
Original languageUndefined
Pages (from-to)2022-2039
JournalEuropean journal of organic chemistry
Volume2005
Issue number10
DOIs
Publication statusPublished - 2005

Keywords

  • IR-53100
  • METIS-225401

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