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The Synthesis, Crystal and Molecular Structure, and Oxidation State of Iron Complex from Pyridoxal Isonicotinoyl Hydrazone and Ferrous Sulphate
Author(s) -
AvramoviciGrisaru Schely,
Sarel Shalom,
Cohen Shmuel,
Bauminger Rivka E.
Publication year - 1985
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.198500045
Subject(s) - chemistry , pyridoxal , protonation , imidazole , octahedron , monoclinic crystal system , oxidation state , crystal structure , crystallography , pyridine , ferrous , metal , mössbauer spectroscopy , ligand (biochemistry) , hydroxymethyl , stereochemistry , medicinal chemistry , organic chemistry , ion , phosphate , biochemistry , receptor
Abstract The reaction of isonicotinoyl hydrazone of pyridoxal (PIH), a biologically active iron‐carrier, with FeSO 4 ‐7H 2 0 at pH ∼ 6 generates the delta, lamda species of the N,N‐ trans ‐O,O‐ cis‐cis coordination isomer of an iron(III) complex with iron‐to‐ligand ratio of 1:2. The dark red‐brown crystals are monoclinic, space group C2/ c , with unit‐cell dimensions a = 14.487(2), b = 18.586(2), c = 27.508(4) Å, β = 102.76(3)°, and Z = 8. The coordination around the metal is distorted octahedral and involves the protonated organic ligands, which are chelated through the phenolic oxygen [Fe‐O1 1.941(6), Fe‐O1′ 1.938(6)], an enolic form of the carbonyl oxygen [Fe‐O3 2.017(6), Fe‐O3′ 2.018(6)] and the azomethinic nitrogen [Fe‐N2 2.133(8), Fe‐N2′ 2.133(8)]. Packing is determined by systems of N‐H….O and O‐H….O hydrogen bonds involving the protonated pyridoxal nitrogens, the pyridoxal hydroxymethyl group, and the [SO 4 ] 2− group. The Mössbauer spectra at different temperatures (300 K, 88 K and 4.1 K) clearly prove that the iron atom in the complex is in a high‐spin trivalent state.