Substituent effects in aromatic ligands the substituted pyridines |
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| Affiliation: | 1. Department of Man-Made Fibers, Technical University of Lodz, Zeromskiego 116, 90-924 Lodz, Poland;2. Department of Rare Earths, Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-614 Poznan, Poland;1. Department of Technology and Biotechnology of Drugs, Faculty of Pharmacy, Jagiellonian University Medical College, Medyczna 9, Kraków 30-688, Poland;2. Institute of Pharmaceutical Chemistry, Biozentrun, ZAFES, Frankfurt/Main 60438, Germany;3. Institute of General and Ecological Chemistry, Technical University of Łódź, Żeromskiego 116 str., Łódź 90-924, Poland;4. Institute of Pharmaceutical and Medicinal Chemistry, Heinrich-Heine-University, Universitaetsstr. 1, Düsseldorf 40225, Germany;1. Department of Physics and Astronomy, University of Texas at San Antonio, San Antonio, TX 78249, United States;2. Department of Atomic and Molecular Spectroscopy, Manipal University, Manipal 576104, India;3. Northwest Vista College, 3535 N Ellison Dr, San Antonio, TX 78251, United States;4. Instituto Politécnico Nacional (IPN), Av. Luis Enrique Erro S/N, Unidad Profesional Adolfo López Mateos, Zacatenco, Delegación Gustavo A. Madero, C.P. 07738, Ciudad de México 2009-2010, Mexico;1. Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India;2. Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar, 388 120, Gujarat, India;3. Center for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India |
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| Abstract: | Blue paramagnetic (μ = ∼3·2 B.M.) complexes having formulas [Ni(X-py)4(ClO4)2], where X is H, 3-CH3, 3-Br, 4-C2H5, 3,5-(CH3)2, and 4-i-C3H7, are reported. Also, yellow diamagnetic [Ni(X-py)4](ClO4)2 complexes, where X is 4-CH3 and 4-NH2, and the slightly paramagnetic yellow [Ni(3-pic)4](ClO4)2 complex are reported. Characterization of the complexes include studies of the infrared, near-infrared, and visible spectra of the solid complexes and their solutions in the component pyridine base and in acetone. Near-infra-red and visible absorption bands are assigned in agreement with either regular or distorted octahedral stereochemistries for the blue complexes and solutions and in agreement with square-planar stereochemistry for the yellow complexes. The co-ordination of the perchlorate ion to the nickel ion in the blue complexes is confirmed from the splitting of the degenerate modes and the activation of the symmetric modes of the perchlorate ion in the infra-red spectrum. The ability of two of the complexes to form clathrates with aromatic guests is observed. Inductive, steric, and resonance effects of the substituents are considered as possible explanations of the observed substituent effects. The influence of the resonance effect on the possibility of synergic bonding between the nickel and the pyridine base is considered to be the most important factor in determining the stereochemistries of the complexes. The value of Δ for the 3- and 4-substituted pyridines is judged relatively insensitive to the substituent group. |
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