Synthesis and structural characterization of Rh(III) complexes containing diamino ligands of types {D(C6H4NH2)2} and {D(C6H4CH2NHEt)2} (D = O, S) bearing different spacers

The reaction of the diamino ligands of general formula {D(C6H4NH2)2} [D = O (L1); S (L2)] and {D(C6H4CH2NHEt)2} [D = O (L3); S (L4)] with RhCl3·3H2O yielded neutral coordination complexes [RhIII(Ln)Cl3] [n = 1 (1); n = 2 (2); n = 3 (4); n = 4 (5)]. Compound 1 in N,N-dimethylformamide solution promoted the formation of the neutral complex [RhIII(L1)(dmf)Cl3] (3). A zwitterionic complex [RhIII(HL4)Cl4] (6) was obtained from the reaction of L4 with RhCl3·3H2O as a minor compound. All complexes were characterized in solution by NMR and by vibrational spectroscopy in solid state. Crystal structures of the chlorohydrates [H2L3]Cl2·H2O, [H2L4]Cl2, and the complexes 2–6 were identified by X-ray diffraction studies. Molecular structures of the complexes revealed different coordination patterns of the diamino ligands Ln as well as the formation of chelate rings of five-, six-, and eight members. The presence of N–H groups in the title compounds enhanced the formation of hydrogen bond networks that were analyzed on the basis of a graph set analysis approach, displaying rings at the first to third level.

The synthesis and structural characterization of rhodium(III) complexes of general formula [Rh(Ln)Cl3] derived from {D(C6H4NH2)2} [D = O (L1); S (L2)], and {D(C6H4CH2NHEt)2} [D = O (L3); S (L4)] ligands are described. Molecular structures of octahedral complexes fac-2·DMF, fac-3, mer-4, mer-5, and 6·MeCN is reported. X-ray diffraction data showed that the ligands Ln yielded chelate rings of different sizes and coordination modes towards the rhodium(III) ion. In solid state, the crystal structures of complexes fac-2·DMF, fac-3, and 6·MeCN are stabilized by N–H⋯Cl interactions; for complexes mer-4 and mer-5 solely C–H⋯Cl and C–H⋯pi interactions were found.Figure optionsDownload as PowerPoint slide