Crystal structure and magnetic behaviour of a five-coordinate iron(III) complex of pyridoxal-4-methylthiosemicarbazone

The crystal structure and magnetic properties of a penta-coordinate iron(III) complex of pyridoxal-4-methylthiosemicarbazone, [Fe(H(2)mthpy)Cl-2](CH3C6H4SO3), are reported. The synthesised ligand and the metal complex were characterised by spectroscopic methods (H-1 NMR, IR, and mass spectroscopy), elemental analysis, and single crystal X-ray diffraction. The complex crystallises as dark brown microcrystals. The crystal data determined at 100(l) K revealed a triclinic system, space group P (1) over bar (Z = 2). The ONSCl2, geometry around the iron(III) atom is intermediate between trigonal bipyramidal and square pyramidal (tau = 0.40). The temperature dependence of the magnetic susceptibility (5-300 K) is consistent with a high spin Fe(III) ion (S = 5/2) exhibiting zero-field splitting. Interpretation of these data yielded: D = 0.34(1) cm(-1) and g = 2.078(3). (c) 2007 Elsevier B.V. All rights reserved

Study of Neutral Fe(III) Complexes of Pyridoxal-N-Substituted Thiosemicarbazone with Desolvation-Induced Spin-State Transformation above Room Temperature

The preparation and characterization of two new neutral ferric complexes with desolvation-induced discontinuous spin-state transformation above room temperature are reported. The compounds, [Fe(Hthpy)(thpy)]·CH3OH·3H2O (1) and [Fe(Hmthpy)(mthpy)]·2H2O (2), are low-spin (LS) at room temperature and below, whereas their nonsolvated forms are high-spin (HS), exhibiting zero-field splitting. In these complexes, Hthpy, Hmthpy, and thpy, mthpy are the deprotonated forms of pyridoxal thiosemicarbazone and pyridoxal methylthiosemicarbazone, respectively; each is an O,N,S-tridentate ligand. The molecular structures have been determined at 100(1) K using single-crystal X-ray diffraction techniques and resulted in a triclinic system (space group P1¯) and monoclinic unit cell (space group P21/c) for 1 and 2, respectively. Structures were refined to the final error indices, where RF = 0.0560 for 1 and RF = 0.0522 for 2. The chemical inequivalence of the ligands was clearly established, for the “extra’’ hydrogen atom on the monodeprotonated ligands (Hthpy, Hmthpy) was found to be bound to the nitrogen of the pyridine ring. The ligands are all of the thiol form; the doubly deprotonated chelates (thpy, mthpy) have C-S bond lengths slightly longer than those of the singly deprotonated forms. There is a three-dimensional network of hydrogen bonds in both compounds. The discontinuous spin-state transformation is accompanied with liberation of solvate molecules. This is evidenced also from DSC analysis. Heat capacity data for the LS and HS phases are tabulated at selected temperatures, the values of the enthalpy and entropy changes connected with the change of spin state were reckoned at ΔH = 12.5 ± 0.3 kJ mol-1 and ΔS = 33.3 ± 0.8 J mol-1 K-1, respectively, for 1 and ΔH = 6.5 ± 0.3 kJ mol-1 and ΔS = 17.6 ± 0.8 J mol-1 K-1, respectively, for 2.

CCDC 628129: Experimental Crystal Structure Determination

Related Article: E.W.Y.Tido, A.J.M.Vertelman, A.Meetsma, P.J.van Koningsbruggen|2007|Inorg.Chim.Acta|360|3896|doi:10.1016/j.ica.2007.03.045,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 658153: Experimental Crystal Structure Determination

Related Article: E.W.Y.Tido, G.O.R.A.van Ekenstein, A.Meetsma, P.J.van Koningsbruggen|2008|Inorg.Chem.|47|143|doi:10.1021/ic701695b,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 732216: Experimental Crystal Structure Determination

Related Article: E.W.Y.Tido, C.Faulmann, R.Roswanda, A.Meetsma, P.J.van Koningsbruggen|2010|Dalton Trans.|39|1643|doi:10.1039/b911114j,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

CCDC 732214: Experimental Crystal Structure Determination

Related Article: E.W.Y.Tido, C.Faulmann, R.Roswanda, A.Meetsma, P.J.van Koningsbruggen|2010|Dalton Trans.|39|1643|doi:10.1039/b911114j,An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.