Organometallic−Polyoxometalate Hybrid Compounds: Metallosalen Compounds Modified by Keggin Type Polyoxometalates
Author(s):
Itsik Bar-Nahum, Hagai Cohen, Ronny Neumann
Journal:
Inorganic Chemistry
Year:
2003
Volume:
42
Pages
3677–3684
DOI:
10.1021/ic034095s
Abstract:
Hybrid compounds with two functional centers consisting of a metallosalen moiety (M−salen; M = Mn, Co, Ni, and Pd) connected by an alkylene bridging group to a lacunary Keggin type polyoxometalate were synthesized and characterized. In these metallosalen−polyoxometalate compounds (M−salen−POM) it was shown by the use of a combination of UV−vis, 1H NMR, EPR, XPS, and cyclic voltammetry measurements that the polyoxometalate exerts a significant intramolecular electronic effect on the metallosalen moiety leading to formation of an oxidized metallosalen moiety. For the Mn−salen−POM, the metallosalen center is best described as a metal−salen cation radical species; that is, a localized “hole” is formed on the salen ligand. For the other M−salen−POM compounds, the metallosalen moiety can be described as a hybrid of a metal−salen cation radical species and an oxidized metal−salen species, that is, a delocalized “hole” is formed at the metallosalen center. It is proposed that these oxidized metallosalen centers are best characterized as stabilized charge transfer (metallosalen donor−polyoxometalate acceptor) complexes despite the relatively large distance between the two functional centers.