Monatshefte fu Èr Chemie 129, 769±776 (1998) Mono- and Binuclear Complexes of Iron(III) with 1,2-Bis(2-hydroxybenzamido)ethane Zdene Ïk Sme Âkal ,Zdene Ï k Sindela Âr, and Roman Kli cka Department of Inorganic and Physical Chemistry, Palacky University, CZ-77147 Olomouc, Czech Republic Summary. Complexes of the type [(Fe(L)) 2 O] H 2 O (H 2 L  1,2-bis(2-hydroxybenzamido)ethane), [(Fe(L)) 2 ter] 5H 2 O H 2 ter  terephthalic acid), [Fe(L)bpy]BPh 4 (bpy  2,2 0 -bipyridyl), and [Fe(L)phen]ClO 4 H 2 O (phen  o-phenanthroline) were prepared and studied by elemental analysis, magnetochemical measurements, and spectroscopic methods. [(Fe(L)) 2 O] H 2 O and [(Fe(L)) 2 ter] 5H 2 O are probably binuclear, and the weak antiferromagnetic exchange interaction, ( eff per one atom ofiron(III) was found to be 3.59 BM/77 Kÿ4.91 BM/290 K (J  ÿ7 cm ÿ1 , H  ÿ2JS 1 S 2 , S 1  S 2  5/2) for the -oxo complex and 4.21 BM/82 Kÿ5.35 BM/297 K (J  ÿ5 cm ÿ1 ) for the - terephthalato complex. The iron(III) complexes with bpy or phen are probably mononuclear; their anomalous eff values (3.51 BM/80 Kÿ3.68 BM/297 K for (Fe(L)bpy]BPh 4 and 4.93 BM/259 K for [Fe(L)phen]ClO 4 H 2 O, respectively) agree neither with high spin (5.7±6.1 BM) nor with low spin (2.1±2.5 BM) con®gurations. Keywords. Iron(III) complexes; Magnetic properties, Antiferromagnetism; 1,2-Bis(2-hydroxybenz- amido)ethane. Mono- und binukleare Eisen(II)-Komplexe mit 1,2-Bis(2-hydroxybenzamido)ethan Zusammenfassung. Komplexe des Typs [(Fe(L)) 2 O] H 2 O (H 2 L  1,2-Bis(2-hydroxybenzamido)- ethan), [(Fe(L)) 2 ter] 5H 2 O (H 2 ter  Terephthalsa Èure),[Fe(L)bpy]BPh 4 (bpy  2,2 0 -Bipyridyl)und [Fe(L)phen]ClO 4 H 2 O (phen  o-Phenanthrolin) wurden hergestellt und mittels Elementaranalyse, magnetochemischer Messungen und spektroskopischer Methoden untersucht. [(Fe(L)) 2 O] H 2 O und [(Fe(L)) 2 ter] 5H 2 O sind wahrscheinlichbinuklear,unddieschwacheantiferromagnetische Austauschwechselwirkung ( eff pro Eisen(III)-Atom) wurde fu Èr den -oxo-Komplex zu 3.59 BM/ 77 Kÿ4.91 BM/290 K (J  ÿ7 cm ÿ1 , H  ÿ2JS 1 S 2 ,S 1  S 2  5/2) und fu Èr den -terephthalato- Komplex zu 4.21 BM/82 Kÿ5.35 BM/297 K (J  ÿ5 cm ÿ1 ) ermittelt. Die Eisen(III)-Komplexe mit bpy bzw. phen sind wahrscheinlichmononuklear; ihre anomalen eff -Werte (3.41 BM/ 80 Kÿ3.68 BM/297 K fu Èr [Fe(L)bpy]BPh 4 und 4.93 BM/259 K fu Èr [Fe(L)phen]ClO 4 H 2 O sind wedermit high-spin- (5.7±6.1 BM) noch mitlow-spin-Zusta Ènden (2.1±2.5 BM) in Einklang zu bringen. Introduction The aim of this work was the preparation and physicochemical investigation of new complexes of iron(III) with tetradentate amides derived from salicylic acid and Corresponding author