Atomically precise rhodium nanoclusters: synthesis and characterization of the heterometallic [Rh18Sn3Cl2(CO)33]4− and [Rh7Sn4Cl10(CO)14]5− carbonyl compounds

This paper presents a deepening on the investigation of the Rh-Sn system of heterometallic carbonyl clusters. More specifically, we herein report the synthesis and isolation of the new [Rh7Sn4Cl10(CO)14]5− (1) compound and the atomically precise [Rh18Sn3Cl2(CO)33]4− (2) nanocluster. Cluster 1 can be obtained by reacting the [Rh7(CO)16]3− homometallic cluster with hydrated Sn(II) chloride, in acetone; conversely, cluster 2 derives from the previously known [Rh12Sn(CO)23Cl2]4− precursor after controlled addition of diluted sulphuric acid. Notably, only 2 has retained the recurrent Sn-centred icosahedral structural feature, while 1 shows a molecular structure based on two Rh4 tetrahedra joint by one vertex and stabilized by SnCl2 and [SnCl3]− fragments. Both species have been characterized by infrared (IR) analysis in solution, single-crystal X-ray diffraction and Electrospray Ionization Mass Spectrometry (ESI-MS).