Rh → Sb Interactions Supported by Tris(8-quinolyl)antimony Ligands.

The ligands tris(8-quinolyl)stibine and tris(6-methyl-8-quinolyl)stibine have been synthesized and complexed to rhodium using (MeCN)RhCl. The resulting complexes feature an unusual [RhSb] core as a result of the formal insertion of the antimony center into one of the Rh-Cl bonds. Computational analysis using density functional theory (DFT) methods reveals that the resulting Rh-Sb σ bond is polarized toward the Rh atom, suggesting a description of this linkage as a Rh → Sb Z-type interaction.

Pnictogen bonding at the service of gold catalysis: the case of a phosphinostiborane gold complex.

The search for alternative gold catalyst activators has led us to consider the design of platforms in which a phosphine gold chloride moiety could be activated formation of a pnictogen bond with a neighboring antimony unit. Here, we describe that such a system can be accessed from 4-(diphenylphosphino)-5-(diphenylstibino)-2,7-di--butyl-9,9-dimethylxanthene, by oxidation of the stibine with 3,5-di--butyl--benzoquinone and by coordination of an AuCl unit to the phosphine. This strategy affords a complex in which a Lewis acidic or pnictogen-bond donor catecholatostiborane unit flanks the adjacent gold chloride moiety.