Spectroscopic and electrochemical studies of ruthenium and osmium complexes of salicylideneimine-2-thiophenol Schiff base

https://doi.org/10.1016/j.saa.2004.03.015Get rights and content

Abstract

The reactions between [M3(CO)12], M=Ru and Os, and salicylideneimine-2-thiophenol Schiff base in THF under reflux gave [Ru(CO)4(satpH)] and [Os(CO)3(satpH2)] complexes. Structures of the two complexes were proposed on the basis of spectroscopic studies. Magnetic study of [Ru(CO)4(satpH)] suggested that a change in oxidation state of the ruthenium atom from zero to +1 was achieved via oxidative addition of the SH group with a proton displacement to give a low-spin d7 electronic configuration. UV-Vis spectra of the two complexes in different solvents exhibited visible bands due to metal-to-ligand charge transfer. Electrochemical investigation of the free ligand and complexes showed some cathodic and anodic irreversible peaks due to interconversions through electron transfer.

Introduction

A large number of Schiff bases and their complexes have been investigated for their interesting and important properties, such as their ability to reversibly bind oxygen [1], catalytic activity in the hydrogenation of olefines [2], photochromic properties [3], [4] and complexing ability towards some toxic metals [5]. Furthermore, complexes of Schiff bases showed promising applications in biological activity and biological modeling applications [6], [7], [8], [9]. Although metal complexes of Schiff bases containing the donor sites N2O2 and N4 have been widely investigated [10], [11], [12], [13], [14], [15], [16], [17], little studies were done for those including an ONS donor system [7], [8], [18]. For example, complexes of salicylideneimine-2-thiophenol (satpH2) with some divalent ions such as Co(II), Ni(II), Cu(II), Zn(II) and Ru(II) were investigated [19], [20], [21].

Reactions of salicylideneimine-2-anisole (salanH); a ligand similar to satpH2 with an OCH3 group instead of the SH group, with [M(CO)6], M=Cr, MO, W gave [Cr2O2(CO)2(salan)2], [M2O4(salan)2], and [W2O4(salan)2] [22]. Spectroscopic and magnetic studies of the complexes revealed that they were paramagnetic and the metal existed in an octahedral environment. The oxo metal complexes of group 6 stem their importance from their ability to catalyze epoxidation reactions [10]. In this paper, we report the reactions of satpH2 with [M3(CO)12], M=Ru and Os.

Section snippets

Reagents

[M3(CO)12], M=Ru and Os, were purchased from Aldrich. Salicylideneimine-2-thiophenol (satpH2) was supplied from TCI-Ace, Japan. It was used without further purification. All solvents were of analytical grade and were purified by standard methods prior their use.

Instruments

Infrared measurements (KBr pellets) were performed on a Unicam-Mattson 1000 -FTIR spectrometer. Nuclear magnetic resonance measurements were carried out on a Varian 300 MHz spectrometer. Samples were dissolved in (CD3)2SO with TMS as

IR and NMR studies

The infrared spectrum (KBr pellets) of the salicylideneimine-2-thiophenol (satpH2) ligand exhibited a strong sharp band at 3258 cm−1. This band was previously assigned as due to the stretching frequency of N+H group, which is expected in this region [20], [23]. The spectrum of satpH2 also displayed a band at 1619 cm−1, which could be due to ν C=N. Therefore, it is reasonable to conclude that satpH2 has a hydrogen bonding between the proton of the SH group and the nitrogen of the imine group.

References (31)

  • J. Zhao et al.

    Spectrochim. Acta

    (2001)
  • T. Katsuki

    Coord. Chem. Rev

    (1995)
  • A.A. Soliman et al.

    Thermochim. Acta

    (1999)
  • T. Dziembowska et al.

    J. Mol. Struct

    (2001)
  • C.M. Kepert et al.

    Inorg. Chim. Acta

    (2003)
  • L. Xu et al.

    J. Organomet. Chem

    (1999)
  • C.J. Kleverlaan et al.

    J. Photochem. Photobiol. A: Chem

    (1998)
  • M.M.H. Khalil et al.

    Spectrochim. Acta

    (2001)
  • D. Chen et al.

    Inorg. Chem

    (1987)
  • J. Collman, L.S. Hegedus, Principles and Application of Organotransition Metal Chemistry, University Science Book,...
  • M.Z. Zgierski et al.

    J. Chem. Phys

    (2000)
  • W.J. Sawodny et al.

    Agnew. Chem. Int. Edn. Engl

    (1977)
  • S. Ren et al.

    J. Med. Chem

    (2002)
  • M.T.H. Tarafder et al.

    Trans. Met. Chem

    (2000)
  • N. Raman et al.

    Synth. React. Inorg. Met.-Org. Chem

    (2001)

    • Cited by (0)

    1

    Present address: Chemistry Department, Faculty of Science, King Khalid University, Abha, P.O. Box 9004, Kingdom of Saudi Arabia.

    View full text
    Copyright © 2004 Elsevier B.V. All rights reserved.