On the Reduction of NC Chelated Organoantimony(III) Chlorides

The conversion of organolithium compound LLi, for which L = [o‐C6H4(CH=NC6H3iPr2‐2,6)]–, with antimony chloride gave the molecular chlorides LSbCl2 (1) and L2SbCl (2) depending on the molar ratio used (either 1:1 or 2:1). Bothcompounds were characterized by using 1H and 13C NMR spectroscopy, elemental analysis and single‐crystal X‐ray diffraction. The reaction of 1 with two molar equivalents of K[B(sBu)3H] led to smooth formation of compound L4Sb4 (3) as a result of hydrogen elimination from the unstable hydrido compound. On the contrary, a similar reaction between 2 and K[B(sBu)3H] (1:1) did not result in hydrogen elimination and the formation of expected distibine L2SbSbL2, but an addition of an in situ generated L2Sb–H bond across the C=N functionality in the pendant arm of one of the ligands was observed. The reduction of compound 2 with an excess amount of magnesium was strongly dependent on the reaction time. The distibine L2SbSbL2 (5) could be isolated after 4–5 h from this reaction mixture. Elongation of the reaction time to 1 d (and more) gave a more complicated reaction mixture, in which three products, distibine 5, compound 3 and organomagnesium compound L2Mg(THF) (6), were characterized by single‐crystal X‐ray diffraction in addition to other unidentified products. These results can be rationalized by a migration of the ligand L from the antimony atom to the magnesium, thus explaining formation of both L4Sb4 (3) compound and L2Mg(THF) (6).