Synthesis and reactivity of ruthenium tridentate bis-phosphinite ligand complexes

Abstract

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 η⁶-arene complexes RuH(E(CH₂CH₂OPiPr₂)₂)₂(η⁶-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.