The structural and solution characterization of no
vel Fe(II) compounds of the general formula [Fe(bzt
pen)X]PF
6and [Fe(bzt
pen)CH
3CN](PF
6)
2 is presented, where bzt
pen is the
pentadentate ligand
N-benzyl-
N,
N',
N'-tris(2-methylpyridyl)ethylenediamine and X
- is a monodentate ligand. All complexes were characterized in solution andin the solid state, employing the usual techniques and single-crystal X-ray diffraction. The results obtained arediscussed in terms of the existing information for some pre
viously reported analogous compounds to arri
ve at arationalization regarding the influence of a
variation in the coordination en
vironment of all compounds and to e
valuatetheir relati
ve stability. The obser
ved magnetic response in the solid state is paramagnetic in the entire tem
peraturerange for the Cl
-, Br
-, I
-, OCN
-, and SCN
- deri
vati
ves, while the N(CN)
2-, CH
3CN, and CN
- deri
vati
ves arediamagnetic. The diamagnetic character of these last two compounds is confirmed in acetonitrile solution, while aspin transition step is obser
ved for the N(CN)
2- deri
vati
ve. Diffraction data for all compounds as hexafluorophosphatesshows that the I
-, Br
-, and OCN
- deri
vati
ves crystallize in the orthorhombic space group
Pbca, while the CN
-,SCN
-, and CH
3CN compounds crystallize in the triclinic space group
P. A
verage bond lengths and the trigonaldistortion parameter can be correlated to the obser
ved magnetic susceptibility de
pending on the coordinatedmonodentate ligand. Solution measurements of electronic pro
perties for the compounds follow the trend establishedby the s
pectrochemical series. The relati
ve stability of the Fe(II) complexes can be established in terms of the
percentage of dissociation from the
voltammetry and conducti
vity results, which are consistent with those obtaineds
pectrophotometrically, mainly, the larger stability for the CN
- deri
vati
ve and the lower for the I
- deri
vati
ve. Theredox potential and
percentage of dissociation
values allow for the estimation of the relati
ve stability constants forthe Fe(II) and Fe(III) complexes.