Synthesis and structure of heterometallic clusters of early transition metals

In continuation of our recent studies on the reactivity of [(Cp*Nb)(2)B4H10O], I with metal carbonyls, we have carried out its reactivity with [Fe-2(CO)(9)) that led to the formation of [(Cp*Nb)(2)B2H4O{H2Fe2(CO)(6)BH}], 1. Compound 1 is a heterometallic boride cluster in which [Nb2Fe2] core describes a butterfly framework with one boron atom lying in a semi -interstitial position. Further, in an attempt to isolate the heterometallic metallaboranes of group 4, we have performed the thermolysis reaction of [Cp2Hf(BH4)(2)] with [Cp*IrB3H9] that led to the formation of arachno-[(Cp2HO(Cp*Ir)B3H9], 2, analogous to [(Cp2Zr)(Cp*Ir)B3H9]. Compounds 1 and 2 have been characterized by mass spectrometry, H-1, B-11 and C-13 NMR spectroscopy and the structural types were unequivocally established by crystallographic analysis.