Structural difference due to intramolecular stacking interactions in dinuclear rhodium(III) complexes [{Rh(η5-C5Me5)(L)}2]n+ containing pyrimidine-2-thionate and related ligands

Abstract

Self-assembling reactions between [Rh(η⁵-C₅Me₅)(H₂O)₃]²⁺ and pyrimidine-2-thionate (pymt) or related ligands [L; mpymt = 4-methyl-pyrimidine-2-thionate(1−), dmpymt = 4,6-dimethylpyrimidine-2-thionate(1−), apymt = 4-aminopyrimidine-2-thionate(1−), dapymt = 4,6-diaminopyrimidine-2-thionate(1−), or mpol = 2-sulfanyl-3-pyridinolate(2−)] were carried out and the products characterized by UV/vis, NMR spectroscopy, electrospray ionization mass spectrometry, and crystal structure analysis. All products are dinuclear rhodium(III) complexes of [{Rh(η⁵-C₅Me₅)(L)}₂]ⁿ⁺: three crystal structures with mpymt, dmpymt and mpol were determined. The mpymt and dmpymt ligands co-ordinate through a 1κ²N,S∶2κS mode and the two pyrimidine rings are located in cis position, whereas mpol adopts a five-membered chelating mode with 1κ²S,O∶2κS and the two pyrimidine rings are located in trans position. Such structural difference can reasonably be explained by the intramolecular stacking interaction between the two bridging ligands.