Gj. Grant et al., CROWN THIOETHER COMPLEXES OF TRIVALENT TRANSITION-METAL IONS - THE CRYSTAL-STRUCTURE OF [CR(18S6)CL-3], Inorganica Chimica Acta, 234(1-2), 1995, pp. 35-45
The structure of the macrocyclic complex, [Cr(18S6)Cl-3] (18S6 = 1,4,7
,10,13,16-hexathiacyclooctadecane), has been determined by single-crys
tal X-ray diffraction, the first Cr(III)-thioether coordination comple
x to be structurally characterized. An octahedral environment of three
sulfur atoms and three chlorine atoms around the Cr(III) center is ob
served in the complex, and the stereoisomer obtained in our case is th
e one in which only three adjacent sulfur atoms in the 18S6 ligand are
bonded to the CrCl3 moiety. This is also the first reported structure
of this atypical coordination mode for the 18S6 ligand which typicall
y coordinates in hexadentate fashion or as a bridging ligand. The synt
heses, characterization, and electronic spectra of a series of eleven
additional thioether complexes of Cr(III) are described. All twelve Cr
complexes have the general formula CrLCl(3) and potentially tetra-, p
enta- and hexadentate thioether ligands all function as tridentate lig
ands coordinating to a single metal center. The electronic spectra for
the Cr complexes are all similar and enable ligand field parameters r
eadily to be calculated. The thioethers function as weak field ligands
, and there is a substantial reordering in their spectrochemical serie
s when compared to the series obtained with softer metal ions such as
Ni(II) or Fe(II). In addition, the synthesis and characterization of t
wo novel V(III) complexes with the general formula VLCl(3) where L = 1
,4,7-trithiacyclononane (9S3) or 1,4,7-trithiacyclodecane (10S3) are d
escribed. These are the first two reported examples of thioether compl
exes of vanadium(III). The reaction between 9S3 and the anion [Re2Cl8]
(2-) has also been investigated.