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Tetranuclear Copper Azido Complex of 4,5‐Diazafluoren‐9‐one
Author(s) -
Babu B. Kishore,
Biju A. R.,
Sunkari Sailaja,
Rajasekharan M. V.,
Tuchagues J. P.
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.201201057
Subject(s) - chemistry , tetramer , crystallography , azide , copper , ferromagnetism , jahn–teller effect , magnetic susceptibility , electron paramagnetic resonance , molecule , crystal structure , ion , stereochemistry , condensed matter physics , nuclear magnetic resonance , biochemistry , physics , organic chemistry , enzyme
Abstract A tetranuclear Cu II complex, Cu 4 (dafone) 4 (N 3 ) 8 ( 1 , dafone = 4,5‐diazafluoren‐9‐one) is described. The propensity of dafone to chelate through one short and one long bond is readily accommodated by the tendency of Cu II to undergo Jahn–Teller elongation in its six‐coordinate complexes. The crystal structure of 1 consists of two distortion isomers of the tetranuclear complex molecule. In each isomer, there are four μ 1,1 ‐azido bridges and two μ 1,1,1 ‐azido bridges as well as two terminally coordinated azide ions. The isomers, both of which are centrosymmetric, differ in the way the Jahn–Teller axes of the different Cu II sites are aligned. Magnetic susceptibility measurements show an overall ferromagnetic interaction, which could be fitted with a two parameter model ( J 1 = 22.8 cm –1 , J 3 = –8.2 cm –1 ). The magnetic interaction was modelled by using DFT calculations, which showed that the two isomers are magnetically quite different; one is a ferromagnetically coupled tetramer, and the other may be viewed as two ferromagnetic dimers. The X‐band EPR spectra are in broad agreement with this model.