Synthesis and Coordination Chemistry of a Chelating P–Sn Ligand Based on Stanna‐ closo ‐dodecaborate

Substitution at a B–H unit of the heteroborate cluster stanna‐ closo ‐dodecaborate [SnB 11 H 11 ] 2– at the upper belt of the icosahedron by one of the triarylphosphine moieties of xantphos was carried out under the catalysis of palladium acetate. The resulting coupling product is a monoanion offering two coordination sites: a low‐valent tin‐cluster vertex and a triaryl phosphine moiety. The basicity and nucleophilicity of the anion were investigated in reactions with a strong acid or an alkylating agent. Transition‐metal electrophiles like platinum halide PtCl 2 or rhodium carbonyl [Rh(CO) 2 Cl] 2 react with the bidentate ligand, with the formation of cis ‐coordination products.