Heterotrinuclear complexes containing a hexaselenolato-zinc(II), -cadmium(II), -nickel(II) or -iron(II) core: crystal structures of [(OC)3Fe(µ-SePh)3M(µ-SePh)3Fe(CO)3] (M = Zn, Cd, Ni or Fe) and [Fe(CO)2(phen)(SePh)2] (phen = 1,10-phenanthroline)

Abstract

A series of linear trinuclear selenolate complexes of the general type [(OC)₃Fe(µ-SePh)₃M(µ-SePh)₃Fe(CO)₃] (M = Zn^II 1, Cd^II 2, Ni^II 3 or Fe^II 4) has been synthesized by reaction of the appropriate [M(H₂O)_n]²⁺ with the chelating metalloligand fac-[N(PPh₃)₂][Fe(CO)₃(SePh)₃] in acetonitrile. Their structures were elucidated on the basis of IR, UV/VIS, NMR spectra and X-ray crystallography. Compounds 1–4 are structurally related, each containing two tridentate metalloligands resulting in a MSe₆ co-ordination environment of virtual O_h symmetry. Further reaction of 4 with 3 equivalents of 1,10-phenanthroline (phen) initially afforded the intermediate [Fe(phen)₃][Fe(CO)₃(SePh)₃]₂ but eventually neutral [Fe(CO)₂(phen)(SePh)₂] 5 was formed as the sole product. Its crystal structure has been determined. This investigation shows that fac-[Fe(CO)₃(SePh)₃]^– serves as a tridentate chelating metalloligand and selenolate ligand-transfer reagent.