Preparation and coordinating properties of {CH2(o-C6H4CH2SbMe2)}2, a novel wide-angle cis-chelating distibine

The unique wide-angle distibine, {CH2(o-C6H4CH2SbMe2)}2, has been prepared indirectly by reaction of Me2SbCl with the di-Grignard formed unexpectedly by coupling of o-C6H4(CH2MgCl)2 in concentrated thf solution, and directly by treatment of the {CH2(o-C6H4CH2MgCl)}2 with Me2SbCl. The very oxygen-sensitive distibine has been characterised by 1H and 13C{1H} NMR spectroscopy and high-resolution EIMS. Oxidation of with Br2 gives the air-stable tetrabromide {CH2(o-C6H4CH2SbMe2Br2)}2. Surprisingly, shows a very strong tendency to function as a cis-chelate, e.g. to Pt(IV) in the complex PtMe3I], forming an 11-membered ring and providing a stable Pt(IV) stibine complex, the crystal structure of which shows the Sb-Pt-Sb angle to be 95.96(1) degrees. The yellow Pt(II) complex PtCl2] is obtained from reaction of PtCl2(MeCN)2] with and IR spectroscopic data and a crystal structure determination confirm the Cl ligands are mutually cis in this species. Reaction of W(CO)4(piperidine)2] with in refluxing EtOH gives W(CO)4], the IR spectrum of which shows four nu(CO) bands, also consistent with cis-Sb2 coordination. The cis-chelation is also confirmed by single-crystal X-ray structure determinations of two polymorphs of W(CO)4].