Early–Late Heterobimetallic Alkoxides as Model Systems for Late-Transition-Metal Catalysts Supported on Titania

Facultad de Ciencias del Medio Ambiente, University of Castilla-La Mancha, Ciudad Real, Castille-La Mancha, Spain
Chemistry (Impact Factor: 5.73). 02/2003; 9(3):671-7. DOI: 10.1002/chem.200390075
Source: PubMed


Titanium complexes with chelating alkoxide ligands [TiCp*(O(2)Bz)(OBzOH)] (1) and [TiCp*(Me)((OCH(2))(2)Py)] (2) were synthesised by reaction of [TiCp*Me(3)] (Cp*=eta(5)-C(5)Me(5)) with 2-hydroxybenzyl alcohol ((HO)(2)Bz) and 2,6-pyridinedimethanol ((HOCH(2))(2)Py), respectively. Complex 1 reacts with [(M(mu-OH)(cod))(2)] (M=Rh, Ir) to yield the early-late heterobimetallic complexes [TiCp*(O(2)Bz)(2)M(cod)] [M=Rh (3), Ir (4)]. Carbon monoxide readily replaces the COD ligand in 3 to give the rhodium dicarbonyl derivative [TiCp*(O(2)Bz)(2)Rh(CO)(2)] (5). Compound 2 reacts with [(M(mu-OH)(cod))(2)] (M=Rh, Ir) with protonolysis of a Tibond;Me bond to give [TiCp*((OCH(2))(2)Py)(mu-O)M(cod)] [M=Rh (6), Ir (7)]. The molecular structures of complexes 3, 5 and 7 were established by single-crystal X-ray diffraction studies.

1 Read
  • [Show abstract] [Hide abstract]
    ABSTRACT: The early–late heterometallic complexes [TiCp∗((OCH2)2Py)(μ-O)M(COD)] (M = Rh, Ir) behave as four-electron donor ligands yielding the polynuclear cationic complexes [TiCp∗(OCH2)2 Py(μ-O){M(COD)}2]OTf (M = Rh (1), Ir (2)). The molecular structure of complex 1 has been established through an X-ray diffraction study.
    Journal of Organometallic Chemistry 08/2004; 689(16):2641. DOI:10.1016/j.jorganchem.2004.05.025 · 2.17 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The new tantalum dialkoxide complexes Cp*TaCl2(OCH2)2py (1), trans-Cp*TaMe2(OCH2)2py (2), and cis-Cp*TaMe2(OCH2)2py (3) (Cp* = η5-C5Me5; (OCH2)2py = 2,6-pyridinedimethoxide) have been synthesized. The molecular structures of complexes 1 and 2 have been studied by X-ray diffraction methods. The reaction of complex 3 with carbon monoxide renders Cp*Ta(η2-Me2CO)(OCH2)2py (4), while with isocyanides yields the respective azatantalacyclopropanes Cp*Ta(η2-Me2CNxylyl)(OCH2)2py (6) (xylyl = 2,6-dimethylphenyl) and Cp*Ta(η2-Me2CNtBu)(OCH2)2py (7). The molecular structure of complex 4 has been established by X-ray diffraction. The coordinated ketone in 4 can be reduced to 2-propanol in the presence of water. On the other hand, compound 3 reacts with triflic acid (HOTf) to render the corresponding cationic derivative [Cp*TaMe(OCH2)2py]OTf (8).
    Organometallics 10/2004; 23(21):5030. DOI:10.1021/om049582+ · 4.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A novel heteroditopic macrocyclic ligand system for selective coordination of two different transition metal ions has been obtained in the form of monometallic salen complexes of NiII (LNi, 1) and uranyl (LUO2, 2). The system is characterized by the presence of a dianionic, tetradentate salen donor system (N2O2) derived from cis-1,2-diaminocyclohexane and of a neutral, tridentate 2,6-bis(alkylthiomethyl)pyridine group (NS2). The two binding sites are connected by two oxyethyl chains. The synthetic procedure involves the coupling of the disodium salt of 2,6-bis(mercaptomethyl)pyridine with two equivalents of 3-(2-bromoethoxy)-2-(2-propenyloxy)benzaldehyde. Removal of the protecting allyl groups from the reaction product (I) by palladium catalysis yields the ligand synthon 2,6-bis[2-(3-formyl-2-hydroxyphenyl)oxyethyl]thiomethylpyridine (II). The monometallic macrocyclic complexes 1 and 2, obtained by metal-templated synthesis from cis-1,2-diaminocyclohexane, ligson II, and the corresponding NiII or uranyl acetate salts, respectively, in the presence of barium bis(trifluoroacetate), have been fully characterized by spectroscopic techniques in solution and by X-ray diffraction analyses in the solid state. Both complexes react readily at room temperature with [Rh(CO)2Cl]2 in methanol to form the bimetallic cationic carbonyl complexes [LNiIIRh(CO)]PF6 (3) and [LUO2Rh(CO)]PF6 (4) upon addition of NH4PF6. Two conformers of complex 3 are observed in solution by IR and NMR spectroscopy, in a 5:1 ratio in [D2]dichloromethane, which exhibit a fluxional behavior and are shown to interconvert above room temperature in [D3]acetonitrile. The carbonylrhodium group in the bimetallic systems reacts further with methyl iodide in dichloromethane solution to form oxidative-addition products. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
    Berichte der deutschen chemischen Gesellschaft 03/2006; 2006(5):914 - 925. DOI:10.1002/ejic.200500703 · 2.94 Impact Factor
Show more

Similar Publications