Synthesis and characterization of square-planar iron(II) complexes with dianionic tetraaza macrocyclic ligands and their novel derivatives

Journal Article · Wed Feb 02 04:00:00 EST 1977 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00445a018· OSTI ID:7305429

Riley, D P; Stone, J A; Busch, D H

A series of square-planar iron (II) complexes has been prepared with synthetic dianionic unsaturated tetraaza macrocyclic ligands that are devoid of functional substituents and vary in ring size from 14 to 16 members. The temperature dependence of the magnetic susceptibility confirms the unusual intermediate spin (S = 1) ground state for these square-planar derivatives. In addition, dicationic iron (II) complexes of these ligands have been prepared by protonation of the neutral square-planar complexes. Two types of protonation products have been obtained, including the complexes of tetradentate bis-..beta..-diimine macrocyclic ligands and two novel derivatives in which acetonitrile molecules have added to the apical ..gamma..-carbon of the charged six-membered chelate rings. Ring size effects appear most dramatically in the reactions of the planar complexes with acetonitrile, in which case ring size determines the nature of the product. However, it is also evident both in electronic and Moessbauer spectral data that ring size exerts a great influence on ligand field strengths. The six-coordinate complexes Fe(macrocycle)-(pyridine)/sub 2//sup 2 +/ containing 14- and 15-membered ring macrocyclic ligands have low-spin ground states, while a 16-membered ring derivative exhibits a spin-state equilibrium.

• Research Organization: Ohio State Univ., Columbus
• OSTI ID: 7305429
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 99:3; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
ABSORPTION SPECTRA
CHEMICAL PREPARATION
CHEMICAL PROPERTIES
CHEMICAL REACTION KINETICS
COMPLEXES
ELECTRONIC STRUCTURE
INFRARED SPECTRA
IRON COMPLEXES
KINETICS
LIGANDS
MAGNETIC PROPERTIES
MAGNETIC RESONANCE
MAGNETIC SUSCEPTIBILITY
MOESSBAUER EFFECT
NUCLEAR MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
RESONANCE
SPECTRA
SYNTHESIS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPLEXES