Oxacalix[3]arene complexes with the ReI(CO)3 fragment

Oxacalix3]arenes p-methyloxacalix3]arene (L(1)), p-isopropyloxacalix3]arene (L2), and p-ethoxycarbonyloxacalix3]arene (L3) are able to bind the Re(I)(CO)3 moiety with two of their three phenol-O atoms and one of their ether-O atoms. The monoanionic complexes were isolated in the salts (DBUH)Re(CO)3(L1H-2)].L1 (1) and (NEt4)Re(CO)3(L2H-2)].L2.0.5 MeCN (2) (DBU = 1,8-diazabicyclo5.4.0]undec-7-ene). Over the course of its reaction with (NEt4)(2)Re(CO)3Br(3)] and DBU, p-ethoxycarbonyloxacalix3]arene decomposes to form {Re(CO)3(L4H-2)}2] (3) {L4 = 1-(5-ethoxycarbonyl-2-hydroxy-3-hydroxymethyl-benzyl)-2,3,4,6,7,8,9,10-octahydro-pyrimido1,2-a]azepin-1-ium. The expected monoanion Re(CO)3(L3H-2)]- (4) was identified by 13C NMR and mass spectra.