Mononuclear (O,O′ or N,N′) and Heterodinuclear (O,O′ and N,N′) Transition-Metal Complexes of ortho-Quinoid Bis(pyrazol-1-yl)methane Ligands
摘要:
The ortho-hydroquinone-substituted bis(3,5-dimethylpyrazol-1-yl)methane ligand (HO)(2)C6H3-C(H)-(Pz(Me,Me))(2) (7) has been synthesized and fully characterized. Together with its bis(3-tert-butylpyrazol-1-yl)methane congener (HO)(2)C6H3-C(H)(pz(tBu))(2) (6), 7 was employed in oxidation and complexation studies. 6 has been oxidized with 2,3-dichloro-5,6-dicyano-para-benzoquinone to the corresponding ortho-benzoquinone form 9 on a preparative scale. Pure samples of 9 are stable for several hours in solution and for approximately one day in the solid state. Attempts at a N,N' coordination of [PdCl2] to 6 led to decomposition of the -C(H)(pz(tBu))(2) moiety, whereas an introduction of [PdCl2] exclusively at the N,N' site was possible in high yield for ligand 7. A selectively O,O'-chelated [(p-cym)Ru](2+) complex was accessible for ligand 6, but not for 7. In contrast, [(ppy)(2)Ir](+) and [(Cp*)Ir](2+) gave O,O' complexes with both donors 6 and 7 (Hppy = 2-phenylpyridine; HCp* = pentamethylcyclopentadiene). The heterodinuclear complex [(Cp*)Ir(O)(2)C6H3-C(H)(pz(Me,Me))(2)PdCl2] (16) was obtained from 14 and [(MeCN)(2)PdCl2].
Chemical behavior of ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands in the presence of palladium(II) chloride
摘要:
The synthesis, structural characterization, and coordination behavior of ditopic ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands (ortho-(OH)(2)C6H3-4-CHpz(2), ortho-(OH)(2)C6H3-4-CH(3-Phpz)(2), and ortho-(OH)(2)C6H3-4-CH(3-tBupz)(2)) with pyrazole, 3-phenylpyrazole, and 3-tert-butylpyrazole as donors are described. The reaction of a soluble PdCl2-source with ortho-(OH)(2)C6H3-4-CHpz(2) in acetonitrile yielded the related square-planar N,N-coordinated Pd(II) dichloride complex, whereas treatment of ortho-(OH)(2)C6H3-4-CH(3-Phpz)(2) or ortho-(OH)(2)C6H3-4-CH(3-tBupz)(2) with PdCl2 in acetonitrile resulted in degradation of these ligands. The Pd(II) complexes trans-(3-PhpzH)(2)PdCl2 and trans-(3-tBupzH)(2)PdCl2 were isolated and fully characterized including X-ray diffraction analyses. (C) 2011 Elsevier B.V. All rights reserved.
The synthesis, structural characterization, and coordination behavior of ditopic ortho-hydroquinone-based bis(pyrazol-1-yl)methane ligands (ortho-(OH)(2)C6H3-4-CHpz(2), ortho-(OH)(2)C6H3-4-CH(3-Phpz)(2), and ortho-(OH)(2)C6H3-4-CH(3-tBupz)(2)) with pyrazole, 3-phenylpyrazole, and 3-tert-butylpyrazole as donors are described. The reaction of a soluble PdCl2-source with ortho-(OH)(2)C6H3-4-CHpz(2) in acetonitrile yielded the related square-planar N,N-coordinated Pd(II) dichloride complex, whereas treatment of ortho-(OH)(2)C6H3-4-CH(3-Phpz)(2) or ortho-(OH)(2)C6H3-4-CH(3-tBupz)(2) with PdCl2 in acetonitrile resulted in degradation of these ligands. The Pd(II) complexes trans-(3-PhpzH)(2)PdCl2 and trans-(3-tBupzH)(2)PdCl2 were isolated and fully characterized including X-ray diffraction analyses. (C) 2011 Elsevier B.V. All rights reserved.
Mononuclear (<i>O</i>,<i>O</i>′ or <i>N</i>,<i>N</i>′) and Heterodinuclear (<i>O</i>,<i>O</i>′ and <i>N</i>,<i>N</i>′) Transition-Metal Complexes of <i>ortho</i>-Quinoid Bis(pyrazol-1-yl)methane Ligands
The ortho-hydroquinone-substituted bis(3,5-dimethylpyrazol-1-yl)methane ligand (HO)(2)C6H3-C(H)-(Pz(Me,Me))(2) (7) has been synthesized and fully characterized. Together with its bis(3-tert-butylpyrazol-1-yl)methane congener (HO)(2)C6H3-C(H)(pz(tBu))(2) (6), 7 was employed in oxidation and complexation studies. 6 has been oxidized with 2,3-dichloro-5,6-dicyano-para-benzoquinone to the corresponding ortho-benzoquinone form 9 on a preparative scale. Pure samples of 9 are stable for several hours in solution and for approximately one day in the solid state. Attempts at a N,N' coordination of [PdCl2] to 6 led to decomposition of the -C(H)(pz(tBu))(2) moiety, whereas an introduction of [PdCl2] exclusively at the N,N' site was possible in high yield for ligand 7. A selectively O,O'-chelated [(p-cym)Ru](2+) complex was accessible for ligand 6, but not for 7. In contrast, [(ppy)(2)Ir](+) and [(Cp*)Ir](2+) gave O,O' complexes with both donors 6 and 7 (Hppy = 2-phenylpyridine; HCp* = pentamethylcyclopentadiene). The heterodinuclear complex [(Cp*)Ir(O)(2)C6H3-C(H)(pz(Me,Me))(2)PdCl2] (16) was obtained from 14 and [(MeCN)(2)PdCl2].