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Variable‐temperature X‐ray crystal structure determinations of {Fe[tren(6‐Mepy) 3 ]}(ClO 4 ) 2 and {Zn[tren(6‐Mepy) 3 ]}(ClO 4 ) 2 compounds: correlation of the structural data with magnetic and Mössbauer spectroscopy data
Author(s) -
Seredyuk Maksym,
Gaspar Ana B.,
Kusz Joachim,
Bednarek Gabriela,
Gütlich Philipp
Publication year - 2007
Publication title -
journal of applied crystallography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.429
H-Index - 162
ISSN - 1600-5767
DOI - 10.1107/s0021889807048571
Subject(s) - crystallography , chemistry , monoclinic crystal system , octahedron , crystal structure , bond length , pyridine , x ray crystallography , diffraction , physics , medicinal chemistry , optics
Variable‐temperature X‐ray crystal structure determinations (80–330 K) on compounds {Fe[tren(6‐Mepy) 3 ]}(ClO 4 ) 2 (1‐Fe) {tren(6‐Mepy) 3 is tris[3‐aza‐4‐(6‐methyl‐2‐pyridyl)but‐3‐enyl]amine} and {Zn[tren(6‐Mepy) 3 ]}(ClO 4 ) 2 (1‐Zn) {tren(6‐Mepy) 3 is tris[3‐aza‐4‐(6‐methyl‐2‐pyridyl)but‐3‐enyl]amine} were carried out together with a detailed analysis of the unit‐cell volume and parameters in the spin transition region for (1‐Fe). Both compounds crystallize in the monoclinic system and retained the space group P 2 1 / c at all measured temperatures. The Fe and Zn atoms are surrounded by six N atoms belonging to imine groups and pyridine groups of the trifurcated ligand, adopting a pseudo‐octahedral symmetry. The average Fe—N bond lengths of 2.013 (1) Å (80 K) and 2.216 (2) Å (330 K) are consistent with a low‐spin (LS) and a high‐spin (HS) state for the iron(II) ions. In contrast to (1‐Fe), the structures of (1‐Zn) at low and high temperatures are similar and repeat the structural features of the high‐spin structure of (1‐Fe). The volume of the unit cell increases on heating from 80 to 330 K for (1‐Fe) and (1‐Zn). On the other hand, while the a , b and c cell parameters increase for (1‐Fe), they show less variation for (1‐Zn). For (1‐Fe), variation of the unit‐cell volume with temperature recalculated per Fe atom shows a change Δ V = 27.16 Å 3 during the spin crossover process. Magnetic susceptibility and Mössbauer spectroscopy studies performed on (1‐Fe) reveal an inversion temperature, T 1/2 of 233 K, where the molar fractions of LS and HS sites are both equal to 0.5. The variation in metal–ligand bond lengths, the distortion parameters and the cell parameters are very close to the character of the magnetic curve and the curve of γ HS (the molar fraction of HS molecules) derived from the Mössbauer data; this result shows the correlation between structure and physical properties in (1‐Fe).