Investigations on organoantimony compounds II. Preparation and configuration of organo(oxinato)antimony(V) compounds RnSbCl4−nOx (n = 1−4)

Organo(oxinato)antimony(V) compounds of the types RSbCl3Ox, R2SbCl2Ox, R3SbClOx and R4SbOx (R = alkyl and phenyl) have been synthesized and and investigated by spectroscopic (UV, PMR, IR) methods. All the compounds are monomeric in benzene. In all the compounds except R3SbClOx (R = alkyl), which contains penta-coordinate antimony, the oxinato group acts as a bidentate ligand in benzene solution. The compounds RSbCl3Ox and R2SbCl2Ox are also hexa-coordinate in ethanol (100%) and chloroform, but partial or complete rupture of the Sb---N coordinate bond in Ph3SbClOx and R4SbOx takes place in these polar solvents. The stability of the Sb---N coordinate bond in R4SbOx follows the order of the I-effect of the group R. Low-temperature PMR experiments show the occurence of rapid pseudorotation for hexa-coordinate Me4SbOx in toluene above − 70°. At − 100° two types of methyl groups can be distinguished, but even at this temperature a limiting spectrum is not obtained. In methylene dichloride rapid pseudo-rotation takes place even at − 100°. Similar results are obtained for the − 100° PMR spectra of Me4SbAcac in these solvents. The spectral results are used in discussions of the possible configurations of the organo(oxinato)antimony(V) compounds