Coordination chemistry of 2,5,8-trithia[9],(2,9)-1,10-phenanthrolinophane (L) toward rhodium(III) at the polarised water/1,2-dichloroethane interface. A new possible approach to the problem of separating Rh-III from chloride media

The coordination chemistry involved in the assisted transfer of RhIII by interfacial coordination with 2,5,8-trithia[9],(2,9)- 1,10-phenanthrolinophane (L) has been studied at the water/ 1,2-dichloroethane interface by cyclic voltammetry. The dependence of the half-wave transfer potential on the ligand and metal concentrations suggests the [Rh(L)Cl2]+ formulation for the complex cation involved in the assisted transfer. In contrast, from the reaction of L in refluxing MeCN/water solution the [Rh(L)Cl][BF4]2·2MeCN compound has been isolated and structurally characterised. In the [Rh(L)Cl]2+ complex cation L acts as an N2S3 donor encapsulating the metal centre within a cavity having a square-based pyramidal geometry. A chloride ligand completes the distorted octahedral coordination sphere around the RhIII ion.