H-)(, AUPPH3+, AND HG(MO(CO)(3)CP)(+) SHOW DIFFERENT SITES OF ATTACHMENT TO [FE4C(CO)(12)](2)

The reaction of the PPN+ salt of [Fe4C(CO)(12)](2-) with ClHgM (M meta l fragment) in CH2Cl2 gives the new hexanuclear carbide clusters (PPN) [Fe4C(CO)(12){mu-HgM}] (M = Mo(CO)(3)Cp (1), W(CO)(3)Cp (2), Mn(CO)(5) (3), Fe(CO)(2)Cp (4), Co(CO)(4) (5)) in good yields. The X-ray crysta l structure of 1 is without precedent in that a mercury atom bridges o ne of the two edges defined by wingtip and hinge iron atoms of the Fe4 C butterfly, giving a new skeletal isomer of an MFe4C arrangement.