Synthesis and reactivity of ruthenium tridentate bis-phosphinite ligand complexes.

The tridentate ligands E(CH2CH2OPiPr2)2 (E = NH 1, E = S 2) were employed in the synthesis of a number of ruthenium complexes. Reaction of these ligands with (Ph3P)3RuCl2 afforded the dimers [Ru(HN(CH2CH2OPiPr2)2)Cl(μ-Cl)]2 (3) and [(Ru(E(CH2CH2OPiPr2)2))2(μ-Cl)3][X] (E = NH, X = PF64, E = S, X = Cl 5), respectively. Using (Ph3P)3RuHCl in reactions with 1 gave Ru(NH(CH2CH2OPiPr2)2)(PPh3)HCl (6) while addition of pyridine and 2, gave Ru(S(CH2CH2OPiPr2)2)(py)HCl (7). Treatment of 6 or 7 with NaBPh4 resulted in the formation of the η(6)-arene complexes RuH(E(CH2CH2OPiPr2)2)2(η(6)-C6H5BPh3) (E = NH 8, E = S 9) while reactions with K[B(C6F5)4] gave the salts [RuH(E(CH2CH2OPiPr2)2)(L)][B(C6F5)4] (E = NH, L = PPh310, E = S, L = py 12). Compounds 6 and 7 react with CO giving RuH(HN(CH2CH2OPiPr2)2)(CO)Cl (15) and [RuH(S(CH2CH2OPiPr2)2(py)(CO)]Cl (16) respectively, while reaction of 6, 10 or 12 with dihydrogen gave RuH(HN(CH2CH2OPiPr2)2)(H2)Cl (18) and RuH(E(CH2CH2OPiPr2)2)(L)(H2)][B(C6F5)4] (E = NH, L = PPh319, E = S, L = py 20). The complexes 4-12, 15 and 16 are shown to catalyze the dehydrogenation of HMe2NBH3.