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Arene ruthenium bis-saccharinato complexes: Synthesis, molecular structure and catalytic oxidation properties in aqueous solution
Arene ruthenium complexes [(η6-arene)Ru(sacc)2(OH2)] (arene = para-cymeme, benzene) containing an aqua and two saccharinato ligands have been synthesized from [(η6-arene)RuCl2]2 and sodium saccharinate in a water-ethanol mixture (1:1). The aqua complex [(η6-MeC6H4Pri)Ru(sacc)2(OH2)] reacts with acetonitrile to give the acetonitrile complex [(η6-MeC6H4Pri)Ru(sacc)2(NCMe)]. The corresponding benzene derivative [(η6-C6H6)Ru(sacc)2(NCMe)] was obtained from [(η6-C6H6)RuCl2]2 and saccNa in an acetonitrile-methanol mixture (1:1). All new complexes show a piano-stool geometry with two mono-hapto nitrogen-bonded saccharinato ligands in addition to a H2O or MeCN ligand. All complexes of the type [(η6-arene)Ru(sacc)2(OH2)] and [(η6-arene)Ru(sacc)2(NCMe)] were found to catalyze the oxidation of secondary alcohols with tert-butyl hydroperoxide (ButOOH) to give the corresponding ketones in aqueous solution.
Study of novel η5-cyclopentadienyl and η6-arene platinum group metal complexes containing a N4-type ligand and their structural characterization
The mononuclear η5-cyclopentadienyl complexes [(η5-C5H5)Ru(PPh3)2Cl], [(η5-C5H5)Os(PPh3)2Br] and pentamethylcyclopentadienyl complex [(η5-C5Me5)Ru(PPh3)2Cl] react in the presence of 1 eq. of the tetradentate N,N′-chelating ligand 3,5-bis(2-pyridyl)pyrazole (bpp-H) and 1 eq. of NH4PF6 in methanol to afford the mononuclear complexes [(η5-C5H5)Ru(PPh3)(bpp-H)]PF6 ([1]PF6), [(η5-C5H5)Os(PPh3)(bpp-H)]PF6 ([2]PF6) and [(η5-C5Me5)Ru(PPh3)(bpp-H)]PF6 ([3]PF6), respectively. The dinuclear η5-pentamethylcyclopentadienyl complexes [(η5-C5Me5)Rh(μ-Cl)Cl]2 and [(η5-C5Me5)Ir(μ-Cl)Cl]2 as well as the dinuclear η6-arene ruthenium complexes [(η6-C6H6)Ru(μ-Cl)Cl]2 and [(η6-p-iPrC6H4Me)Ru(μ-Cl)Cl]2 react with 2 eq. of bpp-H in the presence of NH4PF6 or NH4BF4 to afford the corresponding mononuclear complexes [(η5-C5Me5)Rh(bpp-H)Cl]PF6 ([4]PF6), [(η5-C5Me5)Ir(bpp-H)Cl]PF6 ([5]PF6), [(η6-C6H6)Ru(bpp-H)Cl]BF4 ([6]BF4) and [(η6-p-iPrC6H4Me)Ru(bpp-H)Cl]BF4 ([7]BF4). However, in the presence of 1 eq. of bpp-H and NH4BF4 the reaction with the same η6-arene ruthenium complexes affords the dinuclear salts [(η6-C6H6)2Ru2 (bpp)Cl2]BF4 ([8]BF4) and [(η6-p-iPrC6H4Me)2Ru2 (bpp)Cl2]BF4 ([9]BF4), respectively. These compounds have been characterized by IR, NMR and mass spectrometry, as well as by elemental analysis. The molecular structures of [1]PF6, [5]PF6 and [8]BF4 have been established by single crystal X-ray diffraction studies and some representative complexes have been studied by UV–vis spectroscopy.
Half sandwich platinum group metal complexes containing tetradentate N-donor ligand bearing two pyrazolyl-pyridine units linked by an aromatic spacer
Reaction of the bis-bidentate ligand, 1,3-bis((3-(pyridin-2-yl)-1H-pyrazol-1-yl)methyl)benzene (NN∩NN), containing two chelating pyrazolyl-pyridine units connected by an aromatic spacer with platinum group metal complexes results in a series of cationic binuclear complexes, [(η6-arene)2Ru2(NN∩NN)Cl2]2+ (arene = C6H6, 1; p-iPrC6H4Me, 2; C6Me6, 3), [(η5-C5Me5)2M2(NN∩NN)Cl2]2+ (M = Rh, 4; Ir, 5), [(η5-C5H5)2M2(NN∩NN)(PPh3)2]2+ (M = Ru, 6; Os, 7), [(η5-C5Me5)2Ru2(NN∩NN)(PPh3)2]2+ (8) and [(η5-C9H7)2Ru2(NN∩NN)(PPh3)2]2+ (9). All these complexes have been isolated as their hexafluorophosphate salts and fully characterized by use of a combination of NMR spectroscopy, IR spectroscopy and mass spectrometry. The solid state structures of three complexes, [2][PF6]2, [4][PF6]2 and [6][PF6]2, has been determined by X-ray crystallographic studies.
Arene ruthenium oxinato complexes: Synthesis, molecular structure and catalytic activity for the hydrogenation of carbon dioxide in aqueous solution
Two families of arene ruthenium oxinato complexes of the types [(η6-arene)Ru(η2-N,O-L)Cl] and [(η6-arene)Ru(η2-N,O-L)(OH2)]+ have been synthesized from the dinuclear precursors [(η6-arene)RuCl2]2 (arene = para-cymeme or hexamethylbenzene) and the corresponding oxine LH (LH = 8-hydroxyquinoline, 5-chloro-8-hydroxyquinoline, 5,7-dichloro-8-hydroxyquinoline, 5-nitro-8-hydroxyquinoline, 5,7-dimethyl-8-hydroxyquinoline, 5,7-dichloro-2-methyl-8-hydroxyquinoline). The molecular structures of the neutral chloro complexes [(η6-C6Me6)Ru(η2-N,O-L)Cl] (LH = 8-hydroxyquinoline, 5,7-dichloro-2-methyl-8-hydroxyquinoline) and [(η6-MeC6H4Pri)Ru(η2-N,O-L)Cl] (LH = 5,7-dichloro-2-methyl-8-hydroxyquinoline) as well as those of the cationic aqua derivatives [(η6-MeC6H4Pri)Ru(η2-N,O-L)(OH2)]+ (LH = 8-hydroxyquinoline, 5,7-dimethyl-8-hydroxyquinoline), isolated as the tetrafluoroborate salts, show in all cases a piano-stool arrangement with the arene ligand, the chelating oxinato ligand and the chloro or the aqua ligand surrounding the ruthenium center in a pseudo-tetrahedral fashion. The analogous reaction of [(η6-MeC6H4Pri)RuCl2]2 with other N,O-chelating ligands such as 2-pyridinemethanol or tetrahydrofurfurylamine did not give the expected analogs but resulted in the formation of the complexes [(η6-MeC6H4Pri)Ru(η2-NC5H4CH2OH)Cl]+ and [(η6-MeC6H4Pri)Ru(η1-NHCH2C4H3O)Cl2]. The neutral and cationic complexes of the types [(η6-arene)Ru(η2-N,O-L)Cl] and [(η6-arene)Ru(η2-N,O-L)(OH2)]+ have been found to catalyze the hydrogenation of carbon dioxide to give formate in alkaline aqueous solution with catalytic turnovers up to 400.
Mono and dinuclear half-sandwich platinum group metal complexes bearing pyrazolyl-pyrimidine ligands: Syntheses and structural studies
Reactions of 0.5 eq. of the dinuclear complexes [(η6-arene)Ru(μ-Cl)Cl]2 (arene = η6-C6H6, η6-p-iPrC6H4Me) and [(Cp∗)M(μ-Cl)Cl]2 (M = Rh, Ir; Cp∗ = η5-C5Me5) with 4,6-disubstituted pyrazolyl-pyrimidine ligands (L) viz. 4,6-bis(pyrazolyl)pyrimidine (L1), 4,6-bis(3-methyl-pyrazolyl)pyrimidine (L2), 4,6-bis(3,5-dimethyl-pyrazolyl)pyrimidine (L3) lead to the formation of the cationic mononuclear complexes [(η6-C6H6)Ru(L)Cl]+ (L = L1, 1; L2, 2; L3, 3), [(η6-piPrC6H4Me)Ru(L)Cl]+ (L = L1, 4; L2, 5; L3, 6), [(Cp∗)Rh(L)Cl]+ (L = L1, 7; L2, 8; L3, 9) and [(Cp∗)Ir(L)Cl]+ (L = L1, 10; L2, 11; L3, 12), while reactions with 1.0 eq. of the dinuclear complexes [(η6-arene)Ru(μ-Cl)Cl]2 and [(Cp∗)M(μ-Cl)Cl]2 give rise to the dicationic dinuclear complexes [{(η6-C6H6)RuCl}2(L)]2+ (L = L1, 13; L2, 14; L3, 15), [{(η6-p-iPrC6H4Me)RuCl}2(L)]2+ (L = L1, 16; L2, 17; L3, 18), [{(Cp∗)RhCl}2(L)]2+ (L = L1, 19; L2, 20; L3, 21) and [{(Cp∗)IrCl}2 (L)]2+ (L = L1 22; L2, 23; L3 24). The molecular structures of [3]PF6, [6]PF6, [7]PF6 and [18](PF6)2 have been established by single crystal X-ray structure analysis.