Boron and gallium esters derived from 2-(1,3,5-dithiazinan-5-yl)-ethanols

Compounds 2-(1,3,5-dithiazinan-5-yl) ethanol (1), 2-methyl-2-(1,3,5-dithiazinan-5-yl) ethanol (2) and 2- phenyl-2-(1,3,5-dithiazinan-5- yl) ethanol (3) reacted with BF3 center dot OEt2 and BCl3 center dot DMS, 1 and 2 with (Ph2B)O, and 2 and 3 with GaCl3 giving the corresponding chelates, bearing N -> BF2O, N -> BCl2O N -> BPh2O, and N -> GaCl2O groups. The internal coordination N -> M (M = B or Ga) afforded spiro-compounds, where nitrogen is the central atom. Compounds were mainly characterized by B-11, H-1 and C-13 NMR. The N -> B or N -> Ga coordination bond was detected in the H-1 spectra because coordination stops the ring inversion of the dithiazinane ring differentiating equatorial and axial protons. The presence of a sterogenic center at the ethanol arm (ligands 2 and 3), differentiates C4H(2) and C6H(2) upon coordination. Minimum energy structures for boron compounds were calculated [ab initio 6-31G(d,p)]. VT NMR experiments for diphenyl borinic esters were performed in order to estimate the N -> BPh2 coordination energy. X-ray diffraction analyses of the hydrochloride of ligand 1 and of the gallium compound prepared from 2 were obtained.