Y. Miyashita et al., Synthesis, characterization and reactivity of linear-type S-bridged trinuclear complexes containing vanadium(III) ion. Crystal structures of [V-III{M(aet)(3)}(2)](ClO4)(3) (M = Rh-III, Ir-III; aet=2-aminoethanethiolate), J CHEM S DA, (14), 2001, pp. 2089-2094
Citations number
30
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Inorganic & Nuclear Chemistry
Journal title
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
Reactions of fac(S)-[M(aet)(3)] (M=Rh-III, Ir-III; aet=2-aminoethanethiolat
e) with an excess of VCl3 gave linear-type S-bridged trinuclear complexes [
V-III{M(aet)(3)}(2)](3+) (M=Rh-III 1, Ir-III 2). The Delta Lambda isomers (
1a(ClO4)(3) and 2a(ClO4)(3)) were selectively crystallized and their struct
ures were determined by X-ray diffraction. Both the complex cations consist
of two terminal fac(S)-[M(aet)(3)] units and a central vanadium atom, whic
h is situated in an octahedral environment with a (VS6)-S-III chromophore.
The Ir complex 2a was also formed by using (VOCl2)-O-IV instead of (VCl3)-C
l-III in a redox reaction, whereas the Rh complex 1a was not formed by a si
milar method. The optically active isomer (Lambda Lambda -1b) of the Rh com
plex was selectively obtained by using Lambda -fac(S)-[Rh(aet)(3)], and cha
racterized by IR, UV-VIS absorption and CD spectra. All the obtained comple
xes exhibit a unique strong absorption band at ca. 18x10(3) cm(-1). Stabili
ty and reactivity relating to V-S bond cleavage for the complexes were inve
stigated using UV-VIS absorption spectroscopic methods. These studies show
first order decomposition or metal exchange. While 2a has weaker V-S bonds
than 1a (from the X-ray analyses), the former is considerably more stable i
n water than the latter. Cyclic voltammograms of 1a and 2a in water show on
ly irreversible oxidation and reduction waves including V-IV/III and V-III/
II processes. The V(III) ions in the S-bridged trinuclear structures exhibi
t a lower magnetic moment (2.59 mu (B) for 1a and 2.27 mu (B) for 2a) at ro
om temperature than the spin-only value for a d(2) electronic configuration
.