Tripodal molecules derived from ethanoldithiazinanes centered on boron and phosphorus atoms. Structural analyses by NMR and HF/6-31G(d) calculations

A series of boric esters, phosphites, phosphates, thiophosphates and selenophosphates derived from 2-(1,3,5-dithiazinan-5-yl)-ethanol (1), 2-(1,3,5-dithiazinan-5-yl)-1-methyl-ethanol (2), and 2-(1,3,5-dithiazinan-5-yl)-1-phenylethanol (3) are reported. Enantiopure compounds (C3 symmetry) were prepared from 2(−) and 3(−) of (R) configuration. The new tripodal molecules were viscous liquids which were mainly characterized by 1H, 13C, 11B, 31P, 77Se, NMR and VT-NMR experiments. BH3, BCl3, pyridine and PPh3O adducts of boric esters as well as the BH3 adducts of phosphites were synthesized. The molecular geometries were calculated by HF/6-31G(d). The modeled molecules indicated a preferred ligand conformation which led to the formation of cavities. The complex NMR spectra of isomers were interpreted by comparison with the calculated geometries.