Aside from its use as an artificial sweetener, saccharin (Hsac) in its deprotonated form can act as a versatile ligand. With multiple donor atoms, the saccharinate anion (sac-) exhibits a wide range of coordination motifs including monodentate, bidentate, and multiple bridging modes. Surprisingly, in spite of its electronic similarity to bridging carboxylate, amidate, and amidinate ligands, only one example of a tetrabridged dimetal complex (Cr2(sac)4L2, L = pyridine, thf) has been isolated. We are interested in developing the chemistry of dirhodium saccharinate complexes in the expectation that the presence of the neighboring sulfonyl group may impart some unusual electronic behavior to the dimetal center compared to other dirhodium species. Reaction of rhodium acetate with excess saccharin in refluxing toluene resulted in the formation of Rh2(sac)4 in good yield. The reaction is in part driven by the removal of acetic acid through azeotropic distillation with toluene. Single crystals of Rh2(sac)4(DMF)2 were obtained by slow evaporation of a DMF solution of Rh2(sac)4. X-ray diffraction studies reveal that Rh2(sac)4(DMF)2 adopts a paddlewheel geometry with a Rh-Rh distance of 2.4689(6) Å. Treatment of Rh2(sac)4 with tetrafluoroboric acid dimethyl etherate in either acetonitrile or DMF results in the formation of [Rh2(sac)2(solv)6][BF4]2 (solv = MeCN, DMF). Details surrounding the synthesis, structure, and spectroscopic characterization of these new saccharinate complexes will be presented.

Synthesis and characterization of saccharinate complexes of dirhodium

253rd National Meeting (2017)

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