Structure and spectra of a series of eight-co-ordinate complexes of lanthanoids(III) with diethyldithiocarbamate of general formula Na[Ln(Et2NCS2)4](Ln = La to Yb, except Pm)

Abstract

A series of diethyldithiocarbamates (Et₂dtc) of all the lanthanoids from La to Yb. except Pm, of general formula Na[Ln(Et₂dtc)₄] have been prepared. The X-ray crystal and molecular structure of the lanthanum complex has been determined from diffractometer data. Crystals are monoclinic, space group P2₁, with a= 21.154(13). b= 21,445(15), c= 15.584(9)Å, β= 101.56(4)°, Z= 8. The structure was refined by least-squares techniques to R 0.089 for 4 412 observed reflections. The structure consists of Na⁺ and [La(Et₂dtc)₄]- ions: in the anion the lanthanum atom is co-ordinated by eight sulphur atoms forming a distorted dodecahedron. Conductance and spectral measurements show that the eight-co-ordinate structure persists in methyl cyanide solutions. The electronic spectra have been investigated for methyl cyanide solutions in the spectral range 5–39 kK, and bands attributed to electronic transitions of intraligand, charge-transfer, and f–f type. With the cerium(III) complex, intense bands at ca. 23 kK are attributed to f–d or inverted electron transitions.