Group 1 and mixed Group 1 and 2 metal complexes of dianionic p-tert-butylcalix[4]arenes

Group 1 and related complexes of 1,3-O,O'-disubstituted p-tert-butylcalix[4] arene dianions [Bu-t-calix[4](OR)(2)(O)(2)](2-) are reported. Reaction of Bu-t-calix[4](OMe)(2)(OH)(2) with NaH, K, Rb or Cs gave dimeric [M-2{Bu-t-calix[4](OMe)(2)(O)(2)}](2) (M = Na 1, K 2, Rb 3 or Cs 4). The X-ray structure of 1 shows that two Na+ ions are exo-bound between the two calix[4] arene ligands while the other two are endo-bound within the calix[4] arene cavities. Reaction of Bu-t-calix[4](OMe)(2)(OH)(2) with (BuLi)-Bu-n (2 equiv.) gave a mixture of dimeric and monomeric compounds. Complex 1 is cleaved by 15-crown-5 forming [Na-2{Bu-t-calix[4](OMe)(2)(O) 2}(15-crown-5)]. The complexes 2-4 are cleaved by dibenzo-18-crown-6 forming [M-2{Bu-t-calix[4](OMe)(2)(O)(2)}(dibenzo-18-crown-6)]. Reactions of Bu-t-calix[4](OR)(2)(OH)(2) (R = CH2Ph or SiMe3) with Li or Na reagents gave monomeric [M-2{Bu-t-calix[4](OR)(2)(O)(2)}]. The reaction of 1 with CsCl gave [NaCs{Bu-t-calix[4](OMe)(2)(O)(2)}](2) 13 in which the two Cs+ ions are endo-bound. Reaction of 1 with CaCl2 formed [Na2Ca{Bu-t-calix[4](OMe)(2)(O)(2)}(2)].