Phenazine 5,10-dioxide complexes with 3 d metal perchlorates

Abstract

The syntheses and characterization of two series (i.e. prepared 1) in the absence of any dehydrating agent and 2) by treating ligand and salt solutions with moleucular sieve 4A prior to their interaction) of 3d metal perchlorate complexes with phenazine 5,10-dioxide (L) are reported. With metal(II) perchlorates, use of molecular sieve predrying leads to the precipitation of complexes involving higher L to metal ratios and a lower degree of hydration, relative to the compounds obtained in the absence of dehydrating agents. In contrast, with metal(III) perchlorates, when predrying with molecular sieve was employed, lower L to metal ratios (and in one occasion (Fe 3+) a higher degree of hydration) were observed. Most likely formulations for the new metal complexes, based on spectral and magnetic studies, are: Monomeric complexes: Hexacoordinated: [CrL 2L 2(OH 2) n (OClO 3) m ](ClO 4) 3− m ·(12- n)H 2O ( m = 1 or 2; n = 3 or 2); [ML 2(OH 2) 4](ClO 4) 2·2H 2O (M = Mn, Co, Ni, Zn); [ML 3(OH 2) 2(OClO 3)](ClO 4) (M = Mn, Fe); [FeL 3(OH 2) 2(OClO 3](ClO 4) 2; [ML 3(OH 2) 2(OClO 3)](ClO 4)·4H 2O (M = Co,Ni); [ZnL 3(OH 2) 2(OClO 3)](ClO 4)·3H 2O. Square-planar: [CuL 3(OClO 3)](ClO 4)·H 2O. Binuclear, hexacoordinated: [(O 3ClO) x (H 2O) y MLM(OH 2) y ∗(OClO 3) x ](ClO 4) 6−2 x ·zH 2O (M = Cr, Fe; x =2 or 1; y = 3 or 4; z = 18 or 16); [(H 2O 4LFeLFeL(OH 2) 4](ClO 4) 4·16H 2O. The presence of two bulky and sterically hindered L ligands at cis-positions (relative to one another) in the inner coordination sphere of the central metal ion would result in severe steric interference and is, therefore, not favored. Consequently, among the preceding complexes, those containing two L groups per metal ion involve trans-[MX 4L 2] n+ (X = H 2O or OClO 3) complex cations. However, in the case of [MX 3L 3] n+ or [CuXL 3] 2+ cationic complexes, at leastt one L ligand is, of necessity, at a cis-position relative to each of the other two L groups; the steric interactions imposed by such an arrangement of the ligands result in the presence of chemically non-equivalent sets of L ligands in the 3:1 complexes, as suggested by the IR evidence. The two new ferric complexes are magnetically subnormal, apparently involving spin-state equilibria, whilst the rest of the new metal complexes show normal magnetic properties for high-spin d 3 or d 5− d 8 compounds or the d 9 configuration.