Bis(pyrazolyl)acetate and bis(3,5-dimethylpyrazolyl)acetate tris-acetonitrile ruthenium(II) complexes: Synthesis, properties, and structure

摘要

[(eta(6)-p-cymene) RuI2](2) (1) was reacted with the heteroscorpionate ligands, bis(pyrazolyl) acetic acid (BPAH) or bis(3,5-dimethylpyrazoly) acetic acid (BMPAH), in the presence of potassium carbonate under various conditions to yield cationic Ru(II) complexes: [(BPA) Ru(cymene)] I (2), [(BMPA) Ru(cymene)] I (3), [(BPA) Ru(NCMe)(3)] I (4), and [(BMPA) Ru(NCMe) 3)] I (5). The piano-stool, eta(6)-cymene ruthenium complexes (2 and 3) are isolated when the reaction was conducted at room temperature, whereas the tris-acetonitrile ruthenium(II) complexes were isolated at elevated reaction temperatures. The iodide anion of 4 or 5 was easily replaced with tetrakis(3,5-bis(trifluoromethyl) phenyl) borate (BArF') by reaction with silver tetrakis(3,5-bis(trifluoromethyl) phenyl) borate (Ag[BArF']) to yield [(BPA) Ru(NCMe) 3][BArF'] (6) and [(BMPA) Ru(NCMe)(3))][BArF'] (7), which demonstrate improved solubility in organic solvents as compared to 4 and 5. The acetonitrile ligands cis to the carboxylate group in 4 and 5 were significantly more labile than the trans acetonitrile ligand. The rate of acetonitrile dissociation for 4 and 5 was found to be statistically equivalent. These complexes were characterized by H-1, C-13, F-19 nuclear magnetic resonance spectroscopy, infrared spectroscopy, and elemental analyses. Compounds 2, 4, 5, and 7 were also characterized by single crystal X-ray crystallography. (C) 2017 Elsevier B.V. All rights reserved.