| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1335355 | Polyhedron | 2007 | 8 Pages |
The preparation and crystal structure of two iron(II) complexes of formula PPh4-mer-[Fe(tppz)(CN)3] · 7H2O (1) and [Fe(tppz)2][Fe(NCS)4] (2) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine; PPh4+=tetraphenylphosphonium cation] are reported here. The structure of 1 consists of mononuclear mer-tricyano[2,3,5,6-tetrakis(2-pyridyl)pyrazine]ferrate(II) anions, tetraphenylphosphonium cations and crystallization water molecules. Three carbon atoms from three cyanide groups in a mer arrangement and three nitrogen atoms from a tridentate tppz ligand build a somewhat distorted octahedral surrounding around the iron atom in 1. The values of the Fe–C [1.925(6)–1.947(5) Å] and Fe–N [1.870(4)–1.978(4) Å] bond lengths in 1 are consistent with a low-spin iron(II) species, a fact which is corroborated by its diamagnetic character at room temperature. Compound 2 is an ionic salt which is made up of low-[Fe(1)(tppz)2]2+ and high-spin [Fe(2)(NCS)4]2− iron(II) units. The Fe(1) and Fe(2) iron atoms in 2 are six- and four-coordinated, respectively, six nitrogen atoms from two tridentate tppz ligands building a distorted octahedral environment at Fe(1) [Fe(1)–N = 1.874(4)–1.970(5) Å] and four thiocyanate-nitrogen atoms from terminally bound thiocyanate groups forming a tetrahedral surrounding at Fe(2) [Fe(2)–N = 1.966(8)–1.986(7) Å]. The versatility as a ligand of tppz toward transition metal ions is analyzed and discussed in the light of the available structures.
Graphical abstractThe preparation and crystal structure of two iron(II) complexes of formula PPh4-mer-[Fe(tppz)(CN)3] · 7H2O (1) and [Fe(tppz)2][Fe(NCS)4] (2) [tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine; PPh4+=tetraphenylphosphonium cation] are reported here. The structure of 1 consists of mononuclear mer-tricyano[2,3,5,6-tetrakis(2-pyridyl)pyrazine]ferrate(II) anions, tetraphenylphosphonium cations and crystallization water molecules. Compound 2 is an ionic salt which is made up of low-[Fe(1)(tppz)2]2+ six-coordinated and high-spin [Fe(2)(NCS)4]2− four-coordinated iron(II) units. It is the first structurally characterized example containing the tetrahedral iron(II) unit [Fe(NCS)4]2−.Figure optionsDownload full-size imageDownload as PowerPoint slide
