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Hydrogencyanamide‐Bridged One‐Dimensional Polymers Built on Mn III –Schiff Base Fragments: Synthesis, Structure, and Magnetism
Author(s) -
Yuan Mei,
Zhao Fei,
Zhang Wen,
Pan Feng,
Wang ZheMing,
Gao Song
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200601174
Subject(s) - schiff base , crystallography , antiferromagnetism , chemistry , magnetism , spin canting , manganese , ligand (biochemistry) , hydrogen bond , polymer , stereochemistry , polymer chemistry , molecule , magnetization , physics , biochemistry , receptor , organic chemistry , quantum mechanics , magnetic field , condensed matter physics
The ability of NCNH − to construct transition metal coordination polymers and to transmit magnetic coupling was investigated. By introduction of various tetradentate Schiff base ligands (L) and different solvents (S), nine NCNH − ‐bridged manganese(III) coordination complexes were obtained. Their structures can be divided into three types: I) NCNH‐bridged chains built on mononuclear [Mn III (L)] units, [Mn III (L)(μ 1,3 ‐NCNH)] n (L=5‐Brsalen ( 1 ), 5‐Clsalen ( 2 )); II) NCNH‐bridged chains built on dinuclear [Mn III 2 (L) 2 ] units, complexes 3 – 8 , [Mn III 2 (L) 2 (μ 1,3 ‐NCNH)]ClO 4 ⋅S (L=salen, 5‐Fsalen, 5‐Clsalen, 5‐OCH 3 salen; S=CH 3 OH or C 2 H 5 OH); III) NCNH‐bridged Mn III dimers linked by hydrogen bonds into a 1D polymer, {[Mn III (3‐OCH 3 salen)(H 2 O)] 2 (μ 1,3 ‐NCNH)}ClO 4 ⋅0.5 H 2 O ( 9 , salen= N , N ′‐bis(salicylidene)‐1,2‐diaminoethane). In these complexes, the NCNH − resonance structure dominates the bonding mode of the NCNH − ligand adopting the μ 1,3 ‐bridging mode. Magnetic characterization shows that the asymmetric NCNH − bridge transmits antiferromagnetic interaction between Mn III ions and often favors the weak ferromagnetism caused by spin canting in these one‐dimensional chains. However, these complexes exhibit different magnetic behaviors at low temperatures.