Preparation and characterization of [M^III(SeCH₂CH₂NH₂){N(CH₂CH₂NH₂)₃}]²⁺ (M^III = Co, Rh) and molecular structure of the perchlorate of the rhodium(III) complex

By reaction of [RhCl₂(tren)]⁺ (tren = tris(2-aminoethyl)amine) with CH₃SeCH₂CH₂NH₂ in water in the presence of NaBH₄, or in its absence in ethanol, only one of the two geometrical isomers of [Rh(SeCH₂CH₂NH₂)(tren)]²⁺ was formed. Both of the two geometrical isomers of the corresponding Co^III complex were formed by the reaction of Co^II-tren species with (NH₂CH₂CH₂Se-)₂. The structure of the Rh^III complex was determined by the X-ray method. Crystal data [Rh(C₂H₆NSe)(C₆H₁₈N₄)](ClO₄)₂, monoclinic, space group P2₁/c, a = 9.012(1), b = 14.438(1), c = 14.550(4) Å, β = 104.81(1)°, and Z = 4. The final R value was 0.026. The complex ion has a distorted octahedral structure with cis(tertiary amine nitrogen, Se) configuration. The RhN bond length for the amine nitrogen bonded trans to the selenium atom is longer by 0.039(6) Å than the average cis RhN distance for the two other primary amine nitrogen of the tren ligand, indicating rans influence of the selenium atom.