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Inne
HS⇆LS transition in iron(II) two-dimensional coordination networks containing tris(tetrazol-1-ylmethyl)methane as triconnected building block.
Autorzy
Rok wydania
2012
Czasopismo
Numer woluminu
51
Strony
237-245
DOI
10.1021/ic201535x
Kolekcja
Język
Angielski
Typ publikacji
Artykuł
Novel tripodal ligand 1,1′,1″-tris(tetrazol-1-ylmethyl)methane (111tz) and products of its reactions with perchlorate as well as with tetrafluoroborate salts of iron(II) are presented. The isostructural complexes, [Fe(111tz)2](ClO4)2 and [Fe(111tz)2](BF4)2, were isolated as two-dimensional (2D) coordination networks revealing a honeycomb-like pattern with cages occupied by disordered anions. 111tz molecules act as a tridentate ligand bridging three adjacent Fe(II) ions, and the nitrogen N4 atom of six tetrazole rings (tz) is placed in octahedron vertices of FeN6 chromophores. The complexes, crystallizing in the P3̅ space group, were characterized by variable-temperature single-crystal X-ray diffraction and variable-temperature magnetic susceptibility measurements. Variable-temperature magnetic susceptibility measurements show that both systems undergo abrupt and complete spin transition with T1/2↑ = T1/2↓ = 176 K for perchlorate and T1/2↑ = 193.8 and T1/2↓ = 192.8 K for the tetrafluoroborate analogue. Change of spin state in both complexes is accompanied by a thermochromic effect. The HS→LS transition in [Fe(111tz)2](ClO4)2 involves shortening of the Fe–N4 bond lengths from 2.171(2) Å (293 K) to 2.002(1) Å (100 K). In [Fe(111tz)2](BF4)2, lowering of temperature from 293 to 100 K is accompanied by shortening of the Fe–N4 distances from 2.179(2) to 1.987(2) Å, respectively. Perchlorate in [Fe(111tz)2](ClO4)2 or tetrafluoroborate anions in [Fe(111tz)2](BF4)2 are engaged in the formation of intermolecular contacts within as well as with the neighboring 2D layer.
Adres publiczny
http://dx.doi.org/10.1021/ic201535x