Studies of pendant-arm macrocyclic ligands. Part 5. Synthesis of two pyridine-containing penta-aza macrocycles with single pyrrolidinyl pendant arms and characterisation of their nickel(II) and copper(II) complexes. Crystal structure of perchlorato{7-[2′-(1″-pyrrolidinyl)ethyl]-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene}nickel(II) perchlorate

Reaction between 2,6-bis(2-formylphenoxymethyl)pyridine and N,N-bis(3-aminopropyl)methylamine or tris(2-aminoethyl)amine has been used as the starting point for the synthesis of seven oxa-aza macrocyclic ligands, five of them never reported previously. They all feature different pendant arms, which provide a wide range of coordination possibilities. The Schiff base macrocycles L1 and L4 and their reduced ligands L2 and L5 are derived from 2,6-bis(2-formylphenoxymethyl)pyridine and tris(2-aminoethyl)amine or N,N-bis(3-aminopropyl)methylamine, respectively. The reaction of L1 with salicylaldehyde forms L3, which features an imine bond in the pendant arm. The ligand L5 has been the precursor for the pendant-armed L6 and L7, by alkylation of the free NH groups with methyl-imidazole or methyl-indole. By a template or a nontemplate approach, we have synthesized different mono- and dinuclear complexes with Y(III), Ln(III), Zn(II), and Cd(II) cations. Both the free macrocyclic ligands and their corresponding metal complexes have been characterized by microanalysis, IR, UVvis, 1H and 13C NMR spectroscopy, FAB mass spectrometry, MS electrospray, and conductivity measurements.Key words: Schiff-base macrocycle, template synthesis, macrocyclic ligand complexes, lanthanide(III) complexes.

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Studies of pendant arm macrocyclic ligands. Part 7. Synthesis of two sexidentate macrocycles based upon a pyridine-containing tetra-aza macrocycle with either two 2-pyridylmethyl or two 1-pyrazolylmethyl pendant co-ordinating arms, and characterisation of their cobalt(II), nickel(II), copper(II), and zinc(II) complexes. Crystal structure of {3,11-di(2-pyridylmethyl)-3,7,11,17-tetra-azabicyclo[11.3.1]heptadeca-1(17),13,15-triene}nickel(II) perchlorate

Journal of the Chemical Society Dalton Transactions ◽

10.1039/dt9900002965 ◽

1990 ◽

pp. 2965 ◽

Cited By ~ 25

Author(s):

Karappulli P. Balakrishnan ◽

Hadi A. A. Omar ◽

Peter Moore ◽

Nathaniel W. Alcock ◽

Graham A. Pike

Keyword(s):

Crystal Structure ◽

Macrocyclic Ligands ◽

Pendant Arm

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Studies of pendant-arm macrocyclic ligands. Part 8. Synthesis of two pentaazamacrocycles based upon pyridine-containing tetraazamacrocycles with a single pendant co-ordinating 2-pyridylmethyl arm, and characterisation of their nickel(II), copper(II) and zinc(II) complexes. Crystal structure of 7-(2′-pyridylmethyl)-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15-trienezinc(II) tetrafluoroborate

Journal of the Chemical Society Dalton Transactions ◽

10.1039/dt9940000485 ◽

1994 ◽

pp. 485-489 ◽

Cited By ~ 18

Author(s):

Simon J. Grant ◽

Peter Moore ◽

Hadi A. A. Omar ◽

Nathaniel W. Alcock

Keyword(s):

Crystal Structure ◽

Macrocyclic Ligands ◽

Pendant Arm

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Magnetic Properties of Fe(II) Complexes of Cyclam Derivative with One p-Aminobenzyl Pendant Arm

Metals ◽

10.3390/met10030366 ◽

2020 ◽

Vol 10 (3) ◽

pp. 366

Author(s):

Bohuslav Drahoš ◽

Peter Antal ◽

Ivan Šalitroš ◽

Radovan Herchel

Keyword(s):

Crystal Structure ◽

Magnetic Properties ◽

High Spin ◽

Spin Crossover ◽

Crystal Packing ◽

Theoretical Calculations ◽

High Spin State ◽

Magnetic Data ◽

Pendant Arm ◽

Pendant Arms

In order to prepare an Fe(II) spin crossover (SCO) complex that could be consequently modified to a bimetallic coordination compound that possesses another magnetic property of interest, a specially designed ligand L-NH2 (1-(4-aminobenzyl)-4,11-bis(pyridine-2-ylmethyl)- 1,4,8,11-tetraazacyclotetradecane) was prepared. This ligand consists of a macrocyclic cyclam part containing two 2-pyridylmethyl pendant arms (expecting SCO upon Fe(II) complexation) and one p-aminobenzyl pendant arm with an NH2 group. The presence of this group enables the consequent transformation to various functional groups for the selective complexation of other transition metals or lanthanides (providing the second property of interest). Furthermore, the performed theoretical calculations (TPSSh/def2-TZVP) predicted SCO behavior for the Fe(II) complex of L-NH2. Thus, Fe(II) complexes [Fe(L-NH2)](ClO4)2 (1) and [Fe(L-NH2)]Cl2·6H2O (2) were synthesized and thoroughly characterized. Based on the crystal structure of an isostructural analogous Ni(II) complex [Ni(L-NH2)]Cl2·6H2O (3), the coordination number six was confirmed with an octahedral coordination sphere and a cis-arrangement of the pyridine pendant arms. The measured magnetic data confirmed the high-spin behavior of both compounds with large magnetic anisotropy (D = 17.8 for 1 and 20.9 cm−1 for 2 complemented in both cases also with large rhombicity), though unfortunately without any indication of the SCO behavior with decreasing temperature. The lack of SCO can be ascribed to the crystal packing and/or the non-covalent intermolecular interactions stabilizing the high-spin state in the solid state.

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