The unsupported early-late heterobimetallics HC(SiMe(2)NC(6)H(4)F-2>Zr
-3-M(CO)(2)(eta-C5H5) (M = Fe 1, Ru 2) undergo highly selective reacti
ons with X=C=Y heteroallenes to yield the insertion products HC(SiMe(2
)NC(6)H(4)F-2)(3)Zr(XYC)M(CO)(2)(eta-C5H5 (X = O, S; Y = O, S, NR); si
ngle-crystal X-ray structure analyses of HC(SiMe(2)NC(6)H(4)F-2)(3) Zr
(S2C)Fe(CO)2(eta -C5H5) 4 and iMe(2)NC(6)H(4)F-2)(3)Zr(SCNPh)Fe(CO)(2)
(eta-C5H5) 10 establish the mode of coordination of the substrates to
the two metal centres.