Syntheses and chemistry of hypervalent cyclo-R4Sb4, cyclo-(RSbE)n [R = 2-(Me2NCH2)C6H4, E = O, S] and precursors

Abstract

The cyclostibane R₄Sb₄ (1) (R = 2-(Me₂NCH₂)C₆H₄) was synthesized by reduction of RSbCl₂ with Mg in THF or with Na in liquid NH₃. The reaction of 1 with [W(CO)₅(THF)] gives the stibinidene complex RSb[W(CO)₅]₂ (2). RSbCl₂ and (RSbCl)₂E [E = O (6), E = S (8)] react with KOH or Na₂S in toluene/water to give the heterocycles (RSbE)_n [E = O, n = 3 (3); E = S, n = 2 (4)]. The chalcogeno-bridged compounds of the type (RSbCl)₂E [E = O (6), E = S (8)] were synthesized by reaction of RSbCl₂ with KOH or Na₂S in toluene/water, but also by reaction of RSbCl₂ with the heterocycles (RSbE)_n. The compounds (RSbI)₂O (7) and (RSbBr)₂S (9) were prepared via halogen-exchange reactions between (RSbCl)₂E and NaI (E = O) or KBr (E = S) or by reactions between RSbI₂ and KOH or RSbBr₂ and Na₂S. The reaction of cyclo-(RSbS)₂ with W(CO)₅(THF) in THF results in trapping of the cis isomer in cyclo-(RSbS)₂[W(CO)₅] (5). The solution behaviour of the compounds was investigated by ¹H and ¹³C NMR spectroscopy. The molecular structures of compounds 1–7 and 9 were determined by single-crystal X-ray diffraction.