Cyclopentadienyl-N,N-diethylcarbamato Derivatives of Zirconium(IV) and Hafnium(IV), MCp(O2CNEt2)3: Synthetic Procedures and Use as Precursors for the Chemical Implantation of Organometallic Fragments on a Silica Surface

Reaction of Mg(C5H5)2 with the homoleptic diethylcarbamato derivatives of zirconium(IV) or hafnium(IV), M(O2CNEt2)4, gave the mixed cyclopentadienyl–diethylcarbamato complexes [M(C5H5)(O2CNEt2)3]. These derivatives have also been obtained by reaction of Fe(O2CNEt2)2 with M(C5H5)4 in the appropriate stoichiometric ratio. The compound [Zr(C5H5)(O2CNEt2)3] crystallizes in the space group P1¯ , Z = 2, a = 9.734(4), b = 10.234(2), c = 12.948(6) Å; a = 83.41(4), b = 86.13(4) and g = 67.43(3)8. On reaction of [Zr(C5H5)(O2CNEt2)3] with dehydrated silica, 1 mol of CO2 per zirconium was evolved. The organometallic fragment Zr(C5H5)(O2CNEt2)2 grafted on silica has been characterized by analytical methods and by CP MAS 13C NMR spectroscopy.