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First Homoleptic Complexes of the Tridentate Pyridine‐2,6‐ditetrazolate Ligand
Author(s) -
Klein Axel,
Krest Alexander,
Nitsche Sara,
Stirnat Kathrin,
Valldor Martin
Publication year - 2013
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201201473
Subject(s) - homoleptic , chemistry , electron paramagnetic resonance , ligand (biochemistry) , pyridine , crystallography , terpyridine , spectrochemical series , crystal structure , metal , ion , stereochemistry , inorganic chemistry , ligand field theory , medicinal chemistry , nuclear magnetic resonance , biochemistry , physics , receptor , organic chemistry
The synthesis and spectroscopic characterisation of a series of homoleptic complexes of the tridentate pyridine‐2,6‐di(5‐tetrazolate) ligand (pydtz 2– ) with Co II , Ni II , Cu II and Zn II are reported. Single‐crystal XRD data reveals the formation of octahedrally configured complexes [M(pydtz) 2 ] 2– for M = Zn or [M(Hpydtz)(pydtz)] – for M = Co or Ni, whereas for M = Cu a polymeric structure [Cu(pydtz)(EtOH)] n crystallised. In the latter, alternate short and long Cu ··· Cu distances were found. Magnetic measurements and electron paramagnetic resonance (EPR) spectroscopy reveal noncoupled S = 1/2 Cu II ions for [Cu(pydtz)(EtOH)] n , S = 1/2 low‐spin configuration for the Co II complex and an S = 1 ground state for the Ni II derivative. At T < 16 K the latter shows anomalies that resemble those of single‐ion molecular magnets. The ligand strength of pydtz 2– is markedly higher than that of the bioisosteric pyridine‐2,6‐dicarboxylate (pydic 2– ) ligand and is very similar to that of the well‐established 2,2′:6′,2″‐terpyridine (terpy) ligand as revealed by the ligand field bands of the Co, Ni and Cu complexes and the magnetism of the Co and Ni derivatives. Solution electrochemical investigations suggest that essentially ligand‐centred reduction at rather negative potentials and metal‐centred oxidation processes occur.