CYCLOADDITION REACTIONS OF TETRAAZA MACROCYCLE SUPPORTED GROUP-4 IMIDO COMPLEXES AND REVERSIBLE ADDITION OF ARYL ISOCYANATE TO A COORDINATED UREATE LIGAND

The first tetraaza macrocycle supported zirconium imido complex [Zr(tm taa)(NC6H3Pr2i-2,6)(py)] and the new titanium imido base-free analogue s [Ti(tmtaa)(NAr)] (Ar = Ph or C(6)H(4)Me-4) react with isocyanates to give N,N'-bound ureate complexes; these can undergo exchange reaction s with excess aryl isocyanate via reversible insertion into the Ti-N(u reate) bond; the X-ray structure of [Zr(tmtaa)- {(NC2H3Pr2i-2,6)(CO)(N Bu(t))}] is described (H(2)tmtaa = tetramethyldibenzotetraaza[14]annul ene).