REACTIONS OF (ETA3-FORMALDEHYDE)ZIRCONOCENE DIMER WITH HETEROCUMULENES

The (η2-formaldehyde)zirconocene dimer (Cp2ZrOCH2)2 (7) inserts CO2 into the zirconium to carbon bond of the metallaoxirane moiety to give [(Cp2ZrOCH2)(Cp2ZrOCH2OCO)] (8). Reaction with diphenylketene 7 gives the cyclodimeric 1 : 1 addition product (Cp2ZrOCH2OCCPh2)2 (10) via the mono-insertion product 9. Similarly, treatment of 7 with t-butylisocyanate yields the intermediate complex [(Cp2ZrOCH2)(Cp2ZrOCH2OCNCMe3)] (11) which gives the final product (Cp2ZrOCH2OCNCMe3)2 (12). Here two five-membered metallacycles are joined together by oxygen bridges via a central four-membered Zr2O2 metallacycle. Complex 12 was characterized by X-ray diffraction. It crystallizes in space group P21/n with cell parameters a 10.142(1), b 17.949(2), c 12.001(1) Å, β = 114.27(1)°; Z = 2, R = 0.055, Rw = 0.054. © 1990.