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 [tBu-calix[4](OR)2(O)2]2– are reported. Reaction of tBu-calix[4](OMe)2(OH)2 with NaH, K, Rb or Cs gave dimeric [M2{tBu-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 endobound within the calix[4]arene cavities. Reaction of tBu-calix[4](OMe)2(OH)2 with nBuLi (2 equiv.) gave a mixture of dimeric and monomeric compounds. Complex 1 is cleaved by 15-crown-5 forming [Na2{tBu-calix[4](OMe)2(O)2}(15-crown-5)]. The complexes 2-4 are cleaved by dibenzo-18-crown-6 forming [M2{tBu-calix[4](OMe)2(O)2}(dibenzo-18-crown-6)]. Reactions of tBu-calix[4](OR)2(OH)2(R = CH2Ph or SiMe3) with Li or Na reagents gave monomeric [M2{tBu-calix[4](OR)2(O)2}]. The reaction of 1 with CsCl gave [NaCs{tBucalix[4](OMe)2(O)2}]213 in which the two Cs+ ions are endo-bound. Reaction of 1 with CaCl2 formed [Na2Ca{tBu-calix[4](OMe)2(O)2} 2].