The infrared spectra of complexes of transition metal halides with substituted pyridines

1966 ◽  
Vol 19 (12) ◽  
pp. 2197 ◽  
Author(s):  
NS Gill ◽  
HJ Kingdon
Keyword(s):  
Transition Metal ◽  
Infrared Spectra ◽  
Metal Ion ◽  
Simple Relationship ◽  
Metal Halides ◽  
Pyridine Ligand ◽  
Substituted Pyridines ◽  
Vibrational Bands ◽  
Tetrahedral Complexes

The infrared spectra, in the region 1600-200 cm-1, of a series of complexes formed by transition metal halides with substituted pyridines have been recorded. The assignment of the vibrational bands of the ligands and their shifts in frequency on coordination with a metal ion are discussed. A study of the metal-nitrogen stretching frequencies of tetrahedral complexes of the type, MX2 L2, where the metal is cobalt or zinc, shows that no simple relationship exists between the magnitude of these frequencies and the nature of either the metal ion or the substituted pyridine ligand.

Di(imino)pyridine Complexes as Catalysts for Homogeneous Olefin Oligomerization Reactions

2020 ◽  
pp. 43-49
Keyword(s):  
Transition Metal ◽  
Transition Metals ◽  
Metal Halides ◽  
Substituted Anilines ◽  
Pyridine Ligand ◽  
Metal Centers ◽  
Pyridine Complexes ◽  
Condensation Reactions ◽  
Ligand Precursors ◽  
Olefin Oligomerization

The synthesis of bis(arylimino)pyridine complexes of seven different transition metals and their applications after activation with methylaluminoxane (MAO) in homogeneous olefin dimerization and oligomerization reactions is described. The synthesis of bis(arylimino)pyridine ligand precursors was achieved via condensation reactions of 2,6-diacetylpyridine with different substituted anilines. The bis(arylimino)pyridine compounds were reacted with 3d transition metal halides of the metals Ti, V, Cr, Mn, Fe, Ni and Co to give the corresponding mono-ligated complexes. Among a series of complexes with varying metal centers, but containing the same ligand, the bis(arylimino)pyridine iron(III) complex provided the best results for the dimerization of 1-hexene after activation with MAO. Beside linear products, methyl branched olefins were detected as well. For all product compositions, a marginal higher amount of hexene dimers was observed, e.g. the insertion of 1-hexene proceeds slightly faster than the insertion of 1-pentene.

Synthesis and infrared spectra of some transition metal complexes of α-amino acid esters

1967 ◽  
Vol 20 (4) ◽  
pp. 675 ◽  
Author(s):  
RW Hay ◽  
LJ Porter
Keyword(s):  
Amino Acid ◽  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Infrared Spectra ◽  
Metal Ion ◽  
Amino Acid Esters ◽  
Visible Spectra ◽  
Metal Ratio ◽  
Acid Esters

A variety of transition metal complexes of a-amino acid esters have been synthesized, and characterized by analysis, conductivity measurements, and infrared spectra. The complexes can be broadly divided into two groups: (a) complexes in which only a metal-nitrogen bond occurs with the α-amino group of the ester, and (b) complexes in which chelate ring formation occurs via secondary donor groups on the ligand. These latter complexes are found with methyl L-histidinate, methyl γ-glutamate, and methyl L-cysteinate. With the exception of a methyl tryptophanate complex, the infrared spectra show that there is no interaction between the carbonyl group of the ester and the metal ion. The visible spectra of aqueous solutions of the esters and copper(II) at a ligand/metal ratio of 5 : 1 have maxima in the 600-650 mμ range at pH 7 consistent with copper-nitrogen bonding only.

Transition Metal Ion Species in Glass: A Comparison of Optical Absorption and Luminescence Evidence

1985 ◽  
Vol 61 ◽  
Author(s):  
William B. White ◽  
Diane S. Knight
Keyword(s):  
Transition Metal ◽  
Optical Absorption ◽  
Crystal Field ◽  
Absorption Spectra ◽  
Metal Ion ◽  
Transition Metal Ions ◽  
Luminescence Spectra ◽  
Crystal Field Theory ◽  
Minority Species ◽  
Tetrahedral Complexes

ABSTRACTOptical absorption spectra of d-d transitions can be interpreted through crystal field theory as evidence for at least four kinds of species: traditional network modifier ions (Mn2+, Fe2+, and Ni2+), octahedral complexes (Cr3+, Mn3+), tetrahedral complexes (Co2+, Fe3+), and network-forming ions (Ti4+, Fe3+). Absorption spectra measure only majority species since crystal field bands are broad and overlapping. Luminescence spectra reveal minority species if these species happen to be efficient emitters under laser excitation. Doublet-quartet emission bands (Cr3+) are independent of crystal field but allow the distinction between species because of small differences in bonding which shifts the Racah B parameter. Quartet-sextet emission (Mn2+, Fe3+) is strongly dependent on coordination number and bond lengths. Qualitative, but not quantitative, changes in speciation can be followed as glass composition is varied. Conceptually, the complexation of transition metal ions in insulator glasses results from a competition between the transition metal and the glass-forming framework for p-orbital electrons of non-bridging oxygens. Complexation is further enhanced in clustered glasses where the ions segregate into the more depolymerized units.

Structure of the complexes of ethylenediphosphinetetraacetic acid in solution

1985 ◽  
Vol 50 (2) ◽  
pp. 445-453 ◽  
Author(s):  
Jana Podlahová ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Metal Ion ◽  
Carboxyl Groups ◽  
Complex Solution ◽  
Square Planar ◽  
Weak Complexes ◽  
Carboxylic Groups ◽  
Uv Visible ◽  
The Stability ◽  
Tetrahedral Complexes ◽  
Free Carboxyl

Ethylenediphosphinetetraacetic acid is bonded to metal ions in aqueous solutions in four ways, depending on the type of metal ion: 1) through an ionic bond of the carboxylic groups to form weak complexes with a metal:ligand ratio of 1 : 1 (Ca(II), Mn(II), Zn(II), Pb(II), La(III)); 2) through type 1) bond with contributions from weak interaction with the phosphorus (Cd(II)); 3) through coordination of the ligand as a monodentate P-donor with the free carboxyl groups with formation of 2 : 1 and 1 : 1 complexes (Cu(I), Ag(I)); 4) through formation of square planar or, for Hg(II), tetrahedral complexes with a ratio of 1 : 2 with the ligand as a bidentate PP-donor with the free carboxyl groups (Fe(II), Co(II), Ni(II), Pd(II), Pt(II)). On acidification of the complex solution, the first two protons are bonded to the carboxyl groups. The behaviour during further protonation depends on the type of complex: in complexes of types 1) and 2) phosphorus is protonated and the complex dissociates; in complexes of types 3) and 4) the free carboxyl groups are protonated and the phosphorus-metal bond remains intact. The results are based on correlation of the stability constants, UV-visible, infrared, 1H and 31P NMR spectra and magnetic susceptibilities of the complexes in aqueous solution.

Transition-metal ion-mediated morphological transformation of pyridine-based peptide nanostructures

2021 ◽  
Vol 45 (1) ◽  
pp. 153-161
Author(s):  
Narendra Singh ◽  
Ramesh Singh ◽  
Swati Sharma ◽  
Khushboo Kesharwani ◽  
Khashti Ballabh Joshi ◽  
...  
Keyword(s):  
Transition Metal ◽  
Metal Ion ◽  
Chemical Structure ◽  
Morphological Transformation ◽  
Transition Metal Ion

Pyridine-mediated constitutionally isomeric artificial metallopeptides possess remarkable advantages over the natural counterparts mainly due to their tailor-made chemical structure.

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