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Synthesis, Spectral and Magnetic Properties, and Crystal Structures of Copper(II) Pyridinecarboxylate Adducts with N‐Heterocyclic Ligands
Author(s) -
Segl'a Peter,
Palicová Martina,
Miklos Dusan,
Koman Marian,
Melník Milan,
Korabik Maria,
Mrozinski Jerzy,
Glowiak Tadeusz,
Sundberg Markku R.,
Lönnecke Peter
Publication year - 2004
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200300365
Subject(s) - chemistry , crystallography , electron paramagnetic resonance , magnetic susceptibility , dimer , copper , pyridine , crystal structure , adduct , molecule , octahedron , infrared spectroscopy , tetragonal crystal system , ion , trigonal bipyramidal molecular geometry , stereochemistry , nuclear magnetic resonance , medicinal chemistry , physics , organic chemistry
Synthesis and characterization of seven new complexes [Cu(2‐MeSnic) 2 (CH 3 OH)] 2 (where 2‐MeSnic is 2‐methylthionicotinate), [Cu(2‐MeSnic) 2 L 2 ] 2 (where L is pyridine — py, ethylnicotinate — Etnic and butylnicotinate — Bunic), [Cu(2‐MeSnic) 2 L 2 (H 2 O) 2 ] (where L is py and nicotinamide — nia) and [Cu(2‐MeSnic) 2 (N‐Menia) 2 (H 2 O) 2 ]·2H 2 O (where N‐Menia is N‐methylnicotinamide) are reported. The characterization were based on elemental analysis, infrared, electronic and EPR spectra, and magnetic susceptibility measurements over a temperature range of 1.8 — 300 K or 70 — 300 K. Three complexes of different type were studied by X‐ray analysis. The molecule of [Cu(2‐MeSnic) 2 (CH 3 OH)] 2 has dimeric paddle‐wheel cage structure with a tetragonal pyramidal arrangement around Cu II . The dimer results from the fact that carboxyl groups of four 2‐MeSnic anions function as bridging in a syn‐syn arrangement. On the other hand [Cu(2‐MeSnic) 2 (py) 2 ] 2 forms dimers with hexacoordinated Cu II atoms in highly distorted coordination octahedra, each with two oxygen atoms of bridging carboxyl groups in an anti‐anti arrangement of two 2‐MeSnic anions, with two oxygen atoms of one asymmetrically chelating 2‐MeSnic anion and with two nitrogen atoms of two pyridine ligands. The temperature independent EPR spectrum for this complex exhibits an axial signal which corresponds to almost isolated S = 1 / 2 magnetic ions. Magnetic data for the dimer show a weak antiferromagnetic interaction between the two metal ions with J = —0.65 cm —1 . The Cu II atom in complex [Cu(2‐MeSnic) 2 (py) 2 (H 2 O) 2 ] is hexacoordinated in an elongated centrosymmetrical tetragonal‐bipyramidal arrangement (4 + 2). Based on the molecular structure the electronic, infrared, electron paramagnetic resonance spectra and magnetic properties are discussed and stereochemistry as well as the mode of ligand coordination in new solid complexes under study have been determined.