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EPR Spectroscopy of 4, 4′‐Bis(tert‐butyl)‐2, 2′‐bipyridine‐1, 2‐dithiolatocuprates(II) in Host Lattices with Different Coordination Geometries
Author(s) -
Jawad Awad Duha,
Koch Andreas,
Mickler Wulfhard,
Schilde Uwe,
Strauch Peter
Publication year - 2012
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.201100517
Subject(s) - electron paramagnetic resonance , chemistry , crystallography , isostructural , monoclinic crystal system , bipyridine , diamagnetism , copper , molecular orbital , stereochemistry , crystal structure , molecule , nuclear magnetic resonance , physics , organic chemistry , quantum mechanics , magnetic field
Abstract A series of new heteroleptic MN 2 S 2 transition metal complexes with M = Cu 2+ for EPR measurements and as diamagnetic hosts Ni 2+ , Zn 2+ , and Pd 2+ were synthesized and characterized. The ligands are N 2 = 4, 4′‐bis(tert‐butyl)‐2, 2′‐bipyridine ( t Bu 2 bpy) and S 2 =1, 2‐dithiooxalate, (dto), 1, 2‐dithiosquarate, (dtsq), maleonitrile‐1, 2‐dithiolate, or 1, 2‐dicyanoethene‐1, 2‐dithiolate, (mnt). The Cu II complexes were studied by EPR in solution and as powders, diamagnetically diluted in the isostructural planar [Ni II ( t Bu 2 bpy)( S 2 )] or[Pd II ( t Bu 2 bpy)( S 2 )] as well as in tetrahedrally coordinated[Zn II ( t Bu 2 bpy)( S 2 )] host structures to put steric stress on the coordination geometry of the central Cu N 2 S 2 unit. The spin density contributions for different geometries calculated from experimental parameters are compared with the electronic situation in the frontier orbital, namely in the semi‐occupied molecular orbital (SOMO) of the copper complex, derived from quantum chemical calculations on different levels (EHT and DFT). One of the hosts, [Ni II ( t Bu 2 bpy)(mnt)], is characterized by X‐ray structure analysis to prove the coordination geometry. The complex crystallizes in a square‐planar coordination mode in the monoclinic space group P 2 1 / a with Z = 4 and the unit cell parameters a = 10.4508(10) Å, b = 18.266(2) Å, c = 12.6566(12) Å, β = 112.095(7)°. Oxidation and reductions potentials of one of the host complexes, [Ni( t Bu 2 bpy)(mnt)], were obtained by cyclovoltammetric measurements.