NOE-DERIVED SOLUTION STRUCTURES OF A BENZYLBORATO-AZASILAZIRCONACYCLOBUTANE COMPLEX, SI)(2)N)ZR(CH2SIME2NSIME3)(ETA(6)-PHCH2B(C6F5)(3))

The benzylborato-azasilazirconacyclobutane complex 1 was formed by lig and cyclometalation upon reaction of {(Me3Si)(2)N}(2)Zr(CH2Ph)(2) with B(C6F5)(3). Quantitative analysis of the H-1 NOESY time course of 1 u sing the conformer population analysis method demonstrates that the do minant conformers in solution are rapidly exchanging benzyl berate rot amers, closely bound to the asymmetric zirconium. The ring rotates suc h that the benzylic methylene eclipses the metallocyclobutylmethylene in the majority of the population and the free amide nitrogen in the m inority of the population. A molecular dynamics approach was required to solve this solution structure because a mixture of static conformat ions does not satisfactorily explain the observed spectra.