Synthesis of Quinoline-Based Rh-Sb Complexes: Inhibition of Halide Transfer to Access a Rh→Sb Z‑Type Interaction.

We report the synthesis of Rh-Sb complexes using high valent Sb ligands, QSbCl (, Q = 8-quinolinyl) and QSbF (), from the low valent Rh precursor [(CO)Rh-(μ-Cl)] to afford the complexes [(κ-QSbCl)-Rh-(CO)-Cl]-[(CO)RhCl] () and (κ-QSbF)-Rh-(CO)Cl (), respectively. The reaction of with [(CO)Rh-(μ-Cl)] results in the transfer of chloride from Sb to Rh to give the ion pair with a Rh-Sb bond for the cation that, according to computational analysis, has some covalent character. Replacing Sb-Cl with Sb-F bonds (, compound ) inhibited halide transfer and allowed formation of with a Rh→Sb interaction that has more Z-type character than the Rh-Sb bond for complex . Molecular orbital and localized orbital bonding analyses are consistent with the proposed Rh→Sb interaction of being more Z-type in character.