Syntheses, structures and immobilization of arene-ruthenium complexes bearing phosphine ligands with methoxysilyl groups

Synthesis and reactivity of an iridium complex based on a tridentate aminophosphano ligand

The iridium(III) hydride compound [IrH{κ³C,P,P'-(SiNP-H)}(CN^tBu)₂][PF₆] (1PF₆) was obtained by reaction of [Ir(SiNP)(cod)][PF₆] with CN^tBu as the result of the intramolecular oxidative addition of the SiCH₂-H bond to iridium(I) [SiNP = Si(CH₃)₂{N(4-tolyl)PPh₂}₂, SiNP-H = CH₂Si(CH₃){N(4-tolyl)PPh₂}₂]. The mechanism of the reaction was investigated by NMR spectroscopy and DFT calculations showing that the pentacoordinated intermediate [Ir(SiNP)(cod)(CN^tBu)][PF₆] (2PF₆) forms in the first place and that further reacts with CN^tBu, affording the square planar intermediate [Ir(SiNP)(CN^tBu)₂][PF₆] (3PF₆) that finally undergoes the intramolecular oxidative addition of the SiCH₂-H bond. The reactivity of 1PF₆ was investigated. On one hand, the reaction of 1PF₆ with N-chlorosuccinimide or N-bromosuccinimide provides the haloderivatives [IrX{κ³C,P,P'-(SiNP-H)}(CN^tBu)₂][PF₆] (X = Cl, 4PF₆; Br, 5PF₆), and the reaction of 5PF₆ with AgPF₆ in the presence of acetonitrile affords the solvato species [Ir{κ³C,P,P'-(SiNP-H)}(CH₃CN)(CN^tBu)₂]²⁺ (6²⁺) isolated as the hexafluorophosphate salt. On the other hand, the reaction of 1PF₆ with HBF₄ gives the iridium(III) compound [IrH(CH₂SiF₂CH₃)(HNP)₂(CN^tBu)₂][BF₄] (7BF₄) as the result of the formal addition of hydrogen fluoride to the Si-N bonds of 1⁺ [HNP = HN(4-tolyl)PPh₂]. A similar outcome was observed in the reaction of 1PF₆ with CF₃COOH rendering 7PO₂F₂. In this case the intermediate [IrH{κ²C,P-CH₂SiMeFN(4-tolyl)PPh₂}(HNP)(CN^tBu)₂]⁺ (8⁺) was observed and characterised in situ by NMR spectroscopy. DFT calculations suggests that the reaction goes through the sequential protonation of the nitrogen atom of the Si-N-P moiety followed by the formal addition of fluoride ion to silicon. Also, the crystal structures of SiNP, 1PF₆, 4PF₆ and 7BF₄ have been determined by X-ray diffraction measurements.

Synthesis, structural characterization and catalytic activity of chlororuthenium(II) complexes with substituted Schiff base/phosphine ancillary ligands

Treatment of [(η 6-p-cymene)RuCl2]2 with one equivalent of chlorodiphenylphosphine in tetrahydrofuran at reflux afforded a neutral complex [(η 6-p-cymene)RuCl2(κ 1-P-PPh2OH)] (1). Similarly, the reaction of [Ru(bpy)2Cl2·2H2O] (bpy = 2,2′-bipyridine) and chlorodiphenylphosphine in methanol gave a cationic complex [Ru(bpy)2Cl(κ 1-P-PPh2OCH3)](PF6) (2), while treatment of [RuCl2(PPh3)3] with [2-(C5H4N)CH=N(CH2)2N(CH3)2] (L1) in tetrahydrofuran at room temperature afforded a ruthenium(II) complex [Ru(PPh3)Cl2(κ 3-N,N,N-L1)] (3). Interaction of the chloro-bridged complex [Ru(CO)2Cl2] n with one equivalent of [Ph2P(o-C6H4)CH=N(CH2)2N(CH3)2] (L2) led to the isolation of [Ru(CO)Cl2(κ 3-P,N,N-L2)] (4). The molecular structures of the ruthenium(II) complexes 1–4 have been determined by single-crystal X-ray crystallography. The properties of the ruthenium(II) complex 4 as a hydrogenation catalyst for acetophenone were also tested.