Dinuclear Spin-Crossover Complexes Based on Tetradentate
and Bridging Cyanocarbanion Ligands
Eric Milin
Sabrina Belaïd
Véronique Patinec
Smail Triki
Guillaume Chastanet
Mathieu Marchivie
10.1021/acs.inorgchem.6b01542.s001
https://acs.figshare.com/articles/journal_contribution/Dinuclear_Spin-Crossover_Complexes_Based_on_Tetradentate_and_Bridging_Cyanocarbanion_Ligands/3581535
Spin-crossover (SCO)
Fe(II) dinuclear complexes of formula [Fe<sub>2</sub>(tmpa)<sub>2</sub>(μ<sub>2</sub>-tcpd)<sub>2</sub>]·0.8(CH<sub>3</sub>OH)
(<b>1·MeOH</b>) and [Fe<sub>2</sub>(andmpa)<sub>2</sub>(μ<sub>2</sub>-tcpd)<sub>2</sub>]·2CH<sub>3</sub>OH (<b>2·MeOH</b>) (tmpa = tris(2-pyridylmethyl)amine, andmpa =
bis(2-pyridylmethyl)aminomethyl)aniline, (tcpd)<sup>2–</sup> = 2-dicyanomethylene-1,1,3,3-tetracyanopropanediide) have been synthesized
and characterized by infrared spectroscopy, X-ray diffraction, and
magnetic measurements. The crystal structure determinations of the
two complexes (<b>1·MeOH</b> and <b>2·MeOH</b>) and the desolvated complex <b>1</b> (from <b>1·MeOH</b>) revealed a neutral centrosymmetrical dinuclear structure in which
the (tcpd)<sup>2–</sup> cyanocarbanion acts as a double μ<sub>2</sub>-bridging ligand between two [FeL]<sup>2+</sup> (L = tmpa
(<b>1</b>), andmpa (<b>2</b>)) units involving two free
coordination sites in the <i>cis</i> configuration. Examination
of the shortest intermolecular contacts in <b>1·MeOH</b> and <b>1</b> reveals no significant hydrogen bonding between
the dinuclear units, while in <b>2·MeOH</b> these units
are held together by significant hydrogen bonds between one of the
uncoordinated nitrile groups and the anilate function, giving rise
to 1D supramolecular structure. The three dinuclear complexes <b>1</b>, <b>2·MeOH</b>, and <b>2</b> exhibit SCO
behaviors which have been evidenced by the thermal evolutions of the
χ<sub>m</sub><i>T</i> product and by the average values
of the six Fe–N distances for <b>1</b> and <b>2·MeOH</b>, that reveal a gradual conversion with transition temperatures (<i>T</i><sub>1/2</sub>) at ca. 352 K (<b>1</b>), 196 K (<b>2</b>), and 180 K (<b>2·MeOH</b>). For the solvated <b>1·MeOH</b>, the sharp SCO transition observed around 365
K was induced by the desolvatation process above 330 K during the
magnetic measurements.
2016-08-15 18:48:42
OH
Bridging Cyanocarbanion Ligands Spin-crossover
Dinuclear Spin-Crossover Complexes
2 exhibit SCO behaviors
χ m T product
dinuclear complexes 1
1 D supramolecular structure
crystal structure determinations
tcpd
uncoordinated nitrile groups
Fe 2
CH
MeOH
centrosymmetrical dinuclear structure