Synthesis, structure, and reactivity of ruthenium carboxylato and 2-oxocarboxylato complexes bearing the bis(3,5-dimethylpyrazol-1-yl)acetato ligand

A series of ruthenium(II) acetonitrile, pyridine (py), carbonyl, SO2, and nitrosyl complexes Ru(bdmpza)(O2CR)(L)(PPh3)] (L = NCMe, py, CO, SO2) and Ru(bdmpza)(O2CR)(L)(PPh3)]BF4 (L = NO) containing the bis(3,5-dimethylpyrazol-1-yl)acetato (bdmpza) ligand, a N,N,O heteroscorpionate ligand, have been prepared. Starting from ruthenium chlorido, carboxylato, or 2-oxocarboxylato complexes, a variety of acetonitrile complexes Ru(bdmpza)Cl(NCMe)(PPh3)] (4) and Ru(bdmpza)(O2CR)(NCMe)(PPh3)] (R = Me (5a), R = Ph (5b)), as well as the pyridine complexes Ru(bdmpza)Cl(PPh3)(py)] (6) and Ru(bdmpza)(O2CR)(PPh3)(py)] (R = Me (7a), R = Ph (7b), R = (CO)Me (8a), R = (CO)Et (8b), R = (CO)Ph) (8c)), have been synthesized. Treatment of various carboxylato complexes Ru(bdmpza)(O2CR)(PPh3)2] (R = Me (2a), Ph (2b)) with CO afforded carbonyl complexes Ru(bdmpza)(O2CR)(CO)(PPh3)] (9a, 9b). In the same way, the corresponding sulfur dioxide complexes Ru(bdmpza)(O2CMe)(PPh3)(SO2)] (10a) and Ru(bdmpza)(O2CPh)(PPh3)(SO2)] (10b) were formed in a reaction of the carboxylato complexes with gaseous SO2. None of the 2-oxocarboxylato complexes Ru(bdmpza)(O2C(CO)R)(PPh3)2] (R = Me (3a), Et (3b), Ph (3c)) showed any reactivity toward CO or SO2, whereas the nitrosyl complex cations Ru(bdmpza)(O2CMe)(NO)(PPh3)](+) (11) and Ru(bdmpza)(O2C(CO)Ph)(NO)(PPh3)](+) (12) were formed in a reaction of the acetato 2a or the benzoylformato complex 3c with an excess of nitric oxide. Similar cationic carboxylato nitrosyl complexes Ru(bdmpza)(O2CR)(NO)(PPh3)]BF4 (R = Me (13a), R = Ph (13b)) and 2-oxocarboxylato nitrosyl complexes Ru(bdmpza)(O2C(CO)R)(NO)(PPh3)]BF4 (R = Me (14a), R = Et (14b), R = Ph (14c)) are also accessible via a reaction with NOBF4]. X-ray crystal structures of the chlorido acetonitrile complex Ru(bdmpza)Cl(NCMe)(PPh3)] (4), the pyridine complexes Ru(bdmpza)(O2CMe)(PPh3)(py)] (7a) and Ru(bdmpza)(O2CC(O)Et)(PPh3)(py)] (8b), the carbonyl complex Ru(bdmpza)(O2CPh)(CO)(PPh3)] (9b), the sulfur dioxide complex Ru(bdmpza)(O2CPh)(PPh3)(SO2)] (10b), as well as the nitrosyl complex Ru(bdmpza)(O2C(CO)Me)(NO)(PPh3)]BF4 (14a), are reported. The molecular structure of the sulfur dioxide complex Ru(bdmpza)(O2CPh)(PPh3)(SO2)] (10b) revealed a rather unusual intramolecular SO2-O2CPh Lewis acid-base adduct.