Structure and properties of tetra-μ-ethanimidamidato-κN:κN′-dirhodium(1+) complexes

Rhodium complexes containing Rh25+ core with ethanimidamidato ligands [Rh2(μ-HN(HN)CCH3)4(H2O)2]Cl · H2O (1) and [Rh2(μ-HN(HN)CCH3)4(DMSO)2]Cl (2) have been obtained and characterized with IR, EPR and UV–Vis spectroscopic methods. X-ray structure of compound 2 reveals two independent dinuclear ions in which Rh–N bonds are slightly different. The Rh–Rh bond is longer than that in other amidine complexes with Rh25+ core. DFT calculations and EPR spectra showed that δRhRh∗ is SOMO orbital. Electronic and EPR spectra depend on the ligands coordinated along the Rh–Rh axis.

Reaction of Na4[Rh2(μ-CO3)4] with ethanimidamide hydrochloride leads to the [Rh2{μ-HN(HN)CCH3}4L2]Cl complexes. DFT calculations and EPR spectra indicate that δRhRh∗ is SOMO orbital. The rhodium atoms are equivalent in the [Rh2{μ-HN(HN)CCH3}4L2]+ compounds, and nonequivalent in [Rh2{μ-HN(HN)CCH3}4LL′]+ complexes. The intense bands in the electronic spectra in the range 13 000–19 000 cm−1 are caused by transitions with prevailing d–d character.Figure optionsDownload as PowerPoint slide