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)

A series of linear trinuclear selenolate complexes of the general type [(OC)(3)Fe(mu-SePh)(3)M(mu-SePh)(3)Fe(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 Sac-[Fe(CO)(3)(SePh)(3)](-) serves as a tridentate chelating metalloligand and selenolate ligand-transfer reagent.