Exchange reactions of R3Sb (R = 0-Tol, m-Tol, p-Tol) with SbC13 in a 1:2 molar ratio give RSbC12. Silylstibanes RSb(SiMe3)2 were obtained by reaction of RSbClz and Me,SiCl with Mg in THF. Slow access of air to solutions of RSb(SiMe3)2 afforded orange crystals of the composition (RSb),. Crystal structures were determined by X-ray crystallography for R = 0-To1 and m-To1 as stacks of (RSb)6 rings in the chair conformation with equatorial substituents. In the An intriguing aspect of the chemistry of those organoantimony rings (RSb), that are not protected by bulky substituents is the readiness to take part in ring-ring equilibria [']. In such labile systems the ring size may be different in the solid state and in solution and should be determined in both phases. Known ring systems have been precisely defined only in the solid state, e.g. (PhSb)&2,31, or only in solution, e.g. (EtSb),,,r4l, because the characterization in other phases was hindered for chemical or analytical reasons. In searching for organoantimony ring systems that can be characterized both in solution and in the solid state, we chose the tolylantimony system and report here on the multistep syntheses of o-, m-, and p-tolylantimony and on the results of NMR and X-Ray studies demonstrating the presence of pentamers and tetramers in solution and of hexamers in the solid state. In this context solutions of phenylantimony were also reexamined. Raman spectra and I3C-CP-MAS-NMR (CP-MAS: cross polarization -magic angle spinning) spectroscopy were employed for the characterization of crystals of phenyl-and p-tolylantimony. For preliminary communications see r e f~. [~,~] .
Syntheses, Properties, and Structures of (RSb), (R = 0-Tol,The syntheses of the tolylantimony ring compounds have been achieved by multistep reactions analogous to the syntheses of phenylantim~ny [~,~]. The preparations start with the exchange reactions of SbC13 and the respective tritolylstibanes in the absence of solvent giving RSbC12 (R = 0-Tol, m-tol, p-Tol) in almost quantitative yields as white crystalline solids. Addition of solutions of RSbC12 in THF to magnesium filings and Me3SiC1 in the same solvent gave MgC12 and RSb(SiMe3)2. The novel tolylbis(trimethylsily1)-stibanes are light yellow air sensitive liquids. They ignite spontaneously when they are exposed to the atmosphere on M-ToI, P-ToI) crystals of (rn-T~lSb)~ there are short intermolecular Sb-Sb distances of 420 pm. Solutions of (RSb), (R = Ph, 0-Tol, mTol, p-Tol) in C6Ds were analyzed by IH-NMR spectroscopy. They contain (RSb)5 and (RSb)4 in equilibria. Raman spectra of (PhSb)6 or (p-TolSb), show signals for Sb, at C = 151 or 153 cm-l. I3C-CP-MAS-NMR data of (p-TolSb), are reported.paper. When, however, the access of air to solutions in THF or other solvents (e.g. toluene, mesitylene, 1,4-dioxane, DMF) is very slow, orange crystals of o-, m-, or p-tolylantimony form.R3Sb + 2 SbC13RSbC12 + 2 Mg + 2 Me,SiC1 + RSb(SiMe3)2 + 2 MgCI2The novel rings are stable in the air only as crystals. They react in solution with traces of ai...