ORGANOMETALLIC OXO CHEMISTRY .4. REACTIVITY OF CP-ASTERISK-W(O)2(CH2SIME3) TOWARD PARA-TOLYL ISOCYANATE - CYCLOADDITION REACTIONS OF TUNGSTEN-OXO AND TUNGSTEN-IMIDO LINKAGES

{Treatment of CP*W(O)2(CH2SiMe3) with p-tolyl isocyanate under appropriate experimental conditions leads to the formation of Cp*W(O)(NC6H4-p-Me)(CH2SiMe3) (1), Cp*W(NC6H4-p-Me)2(CH2SiMe3) (2), or Cp*W(NC6H4-P-Me)[N(C6H4-P-Me)C(O)N(C6H4-P-Me)](CH2SiMe3) (3). Each of the complexes 1-3 is derived in a sequential manner from its precursor by incorporation of an additional p-tolyl isocyanate fragment or molecule. The spectroscopic properties of these organometallic imido complexes are consistent with their possessing three-legged (1 and 2) and four-legged (3) piano-stool molecular structures. These conclusions have been confirmed by single-crystal X-ray crystallographic analyses of 2 and 3. Crystal data for 2: triclinic