Electronic absorption and MCD spectra for octacyanometallate complexes M(CN)(8)(n-), M = Mo(IV), W(IV), n=4 and Mo(V), W(V), n=3

Isci H., Mason W.

INORGANICA CHIMICA ACTA, vol.357, no.14, pp.4065-4072, 2004 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 357 Issue: 14
  • Publication Date: 2004
  • Doi Number: 10.1016/j.ica.2003.10.024
  • Journal Name: INORGANICA CHIMICA ACTA
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.4065-4072
  • Keywords: electronic spectra, MCD spectra, molybdenum and tungsten cyano complexes, CIRCULAR-DICHROISM, OCTACYANOMOLYBDATE(IV), MOLECULE, KINETICS
  • Middle East Technical University Affiliated: No

Abstract

Electronic absorption and 8.0 T magnetic circular dichroism (MCD) spectra are reported for M(CN)(8)(4-), M = Mo(IV) and W(IV), in aqueous solution and M(CN)(8)(3-), M = Mo(V) and W(V), in acetonitrile solutions. In addition some absorption and MCD spectra are reported for the M(CN), 3- ions embedded in thin poly methyl methacrylate (PMMA) plastic films at temperatures from 295 to 10 K. The temperature dependence of the MCD spectra confirms the presence of C terms. The solution and PMMA spectra for the both Mo and W complexes in either the IV or V oxidation states are remarkably similar to each other for the same oxidation state and are interpreted within a D-2d structural framework for the isotropic environment. The weak bands below 3.0 mum(-1) (I mum(-1) = 10(4) cm(-1)) for the M(IV) complexes are assigned as metal-localized ligand field (LF) transitions. LF transitions are also suggested for weaker unresolved absorption between 3.0 and 3.6 mum(-1) for the M(V) ions. The intense bands above 3.6 mum(-1) for M(IV) and 4.6 mum(-1) for M(V) complexes are interpreted as metal to ligand charge transfer (MLCT) from the metal b(1)(x(2)-y(2)) HOMO to CN- -based pi * orbitals. The prominent intense bands observed below 4.5 mum(-1) for the M(V) complexes are assigned as ligand to metal charge transfer (LMCT) from occupied non-bonding or weakly pi bonding CN- orbitals to the half-filled b(1)(x(2)-y(2)) HOMO. (C) 2003 Elsevier B.V. All rights reserved.