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Mononuclear Complexes of Iron(II) Based on Symmetrical Tripodand Ligands: Novel Parent Systems for the Development of New Spin Crossover Metallomesogens
Author(s) -
Seredyuk Maksym,
Gaspar Ana B.,
Kusz Joachim,
Gütlich Philipp
Publication year - 2011
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.201100034
Subject(s) - chemistry , octahedron , crystallography , imidazole , spin crossover , ligand (biochemistry) , spin states , spectrochemical series , stereochemistry , trigonal prismatic molecular geometry , metal , tripodal ligand , ligand field theory , crystal structure , inorganic chemistry , ion , organic chemistry , biochemistry , receptor
The synthesis and characterization of a series of mononuclear tripodand‐based Fe II complexes by means of Mössbauer andUV/Vis spectroscopic as well as magnetic methods is reported. The complexes were obtained from the reactions of Fe II salt with heterocyclic aldehydes (imd = imidazole‐4(5)‐carboxaldehyde, py = picolinaldehyde, or 6‐Mepy = 6‐methylpicolinaldehyde) and a symmetric triamine [tren = tris(2‐aminoethyl)amine, tame = 2,2,2‐tris(aminomethyl)ethane, or tach = 1,3,5‐ cis , cis ‐cyclohexanetriamin]. Because of extreme rigidity of the capping triamine tach, the molecular structure of {Fe[tach(imd) 3 ](BF 4 ) 2 } ( 1 ) features an unprecedented tapered trigonal prismatic FeN 6 polyhedron. The molecular structures of the complexes {Fe[tach(py) 3 ](ClO 4 ) 2 } ( 2 ), {Fe[tame(imd) 3 ](ClO 4 ) 2 } ( 3 ), {Fe[tame(py) 3 ](ClO 4 ) 2 } ( 4 ) and {Fe[tame(6‐Mepy) 3 ](ClO 4 ) 2 } ( 5 ) are quite similar and exhibit pseudo‐octahedral arrangements of the coordination polyhedron. Compound 1 is in the high spin state, whereas compounds 2 – 5 are in the low spin state at all investigated temperatures (10–400 K). Chemical modification of the ligands in 2 – 5 to introduce liquid crystalline properties is expected to decrease the ligand field strength sufficiently to transform the electronic LS ground state to spin crossover behavior in the room temperature region.