ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Preparation and magnetic behavior of [Fe(phen)2X2] complexes

K. Madeja

Ernst Mortiz Arndt Univ., Greifswald, Germany.

Abstract: The [Fe-(phen)₃]X₂ salts, (phen) = 1,10 phenanthroline, X = other ion, react in abs. pyridine, dimethylformamide, or picoline at room temp. to form [Fe(phen)₂X₂] complexes. A series of these complexes with various X units was prepd. and found to be either violet with 4 unpaired electrons or red with partial or complete spin pairing. When X = Br^-, Cl^-, F^-, HCOO-, and SCN^-, the complexes are violet, while mal₂^-, NO₂^-, CN^-, and phen- are red. The high-spin complexes have the cis structure and the low-spin type have a trans placement of the X ligands. The former have π interaction with all 3 d orbitals involved in bonding, while the latter use only the dxz and dyz orbitals. When both phen groups are in a plane, the ortho H atoms can sterically interfere with each other below a certain metal-H distance, and this causes complexes with a Dq value in the vicinity of the term inversion value. This was also the case for [Fe(4,7-dmphen)₂-mal2].5H₂O (4,7-dmphen = 4,7-dimethyl-1,10-phenanthroline), and a blue compd., μeff = 5.35 Bohr magnetons (μB), and a red compd., μeff = 3.87 μB were found, and similarly for the [Fe-(dipy)₂(NCS)₂] complex (dipy is dipyridyl, and mal-2 is malonate).

Full paper in Portable Document Format: 193a186.pdf (in German)

Chemical Papers 19 (3) 186–191 (1965)