Infrared studies of coordination compounds containing low-oxidation-state metals. I. Tris(2,2'-bipyridine) and tris(1,10-phenanthroline) complexes

Abstract

Infrared Studies of Coordination Compounds Containing Low-Oxidation-State Metals. I. Tris(2,2'-bipyridine) and Tris(l, 10-phenanthroline) Complexes

An investigation of the 1H nmr isotropic shifts for some methyl-substituted bipyridine complexes with Ni(II) and Co(II)

“…However, a n-spin transfer mechanism was reported to predominate in the 'H nmr isotropic shifts of some octahedral Schiff base Ni(I1) complexes (26)(27)(28)(29). The charge transfer from metal to ligand via a n-mechanism in the divalent tris(2,2'-bipyridine) metal complexes of the first transition metals was also confirmed by Torii and co-workers (30), by Felix et al (31), and by Nakamoto and co-workers (32). The isotropic proton chemical shifts of 2,2'-bipy ridine and its symmetrical methyl-substituted Ni(I1) complexes have been investigated by Wicholas and Drago (33).…”

“…The o-mechanism results in cationic character being attributed to the ligand, while the n-mechanism imparts anionic character to the ligand. These o-donations and n -back-donations have been well documented by measurement of infrared stretching bands (30) and by electronic absorptions (32). In this work, the INDO method has been used to calculate the electron spin density at each nucleus in both o-and n-orbitals of the ligand, for a model free ligand cation (representing unpaired electron density on the o-orbitals of the ligand) and a model free ligand anion (representing unpaired electron density on the n*-bonding orbital of the ligand).…”

A Novel Salt Formed by Mixed-Valence Vanadium(IV, V) [(VO)2O(bpy)2(C2O4)2] Anions and Ferromagnetic [Cu2(bpy)4(C2O4)] Cations: Structure, Spectroscopic Characterization and Magnetic Properties

“…[25] The equal prominent peak at 383 cm Ϫ1 is assigned to the VϪN(bpy) stretching vibrations. [26] The weaker peak at 355 cm Ϫ1 is considered as being due to combinations of VϪO(oxalate) stretching vibrations with V-oxalate chelate ring deformation vibrations. [27] The rather weak absorption at 287 cm Ϫ1 is due to the symmetric stretching mode ν CuϪN of the CuϪN(bpy) moieties.…”

Pressure effects on the rate of electron transfer between tris(1,10-phenanthroline)iron(II) and -(III) in aqueous solution and in acetonitrile

“…If the Ovchinnikova condition (19,26) [18] [AGIR4/(AGIR* + A G~~* ) ] '~~u~~ exp (-AGI~*/RT) > 7L-l is satisfied, the pre-exponential part of eq. [5] becomes solvent dependent; for reaction [l] in water at 3°C and acetonitrile at 25"C, this requires AGIR4 5 200 and 100 J mol-' respectively, and these conditions could be met, in view of the insensitivity of the Fe-N bond lengths and stretching frequencies to the oxidation state of the iron (12,23 A solvent-dynamical treatment of pressure effects on k (in the case where AGIR* is negligible) involves the replacement of eq. PI by…”