SYNTHESIS AND CHARACTERIZATION OF DIMETALLACALIX[8]ARENE COMPLEXES

The one-pot synthesis of a variety of [4-tert-butylcalix[8]arene(MOR)2]-[M′ or R′NH3]+ (M = Ti, Zr, V, Sn; M′ = Li, Na, K) complexes is described. The 1H NMR spectra of these compounds possess several interesting features, including upfield shifts (by 0.5-2.0 ppm) of α or β protons on the alkoxide ligand and a phenol hydroxyl resonance at ca. 16 ppm. The upfield shift is due to shielding of the alkoxide ligand by the aryl rings of the calixarene macrocycle. The ligands are located in cavities, made up of three aryl rings of the macrocycle. Fast atom bombardment mass spectrometry (FABMS) and tandem mass spectrometry (MS/MS and MS/MS/MS) have been used to obtain molecular ion information as well as identify fragment ions from these complexes. Two-dimensional NMR experiments have established that the solution structure is the same as in the solid state and have also allowed assignment of all of the macrocycle protons in the 1H NMR spectrum. A difference NOE experiment has determined the location of the remaining phenol hydroxyl proton, which had not been located previously by X-ray crystallography. © 1990, American Chemical Society. All rights reserved.