Synthesis and Characterization of Bis(guanidinate) Zirconium Complexes

Addition of one equivalent of LiN( i ‐Pr) 2 or LiN(CH 2 ) 5 to carbodiimides, RNCNR [R=cyclohexyl (Cy), isopropyl ( i ‐Pr)], generated the corresponding lithium of tetrasubstituted guanidinates {Li[RNC(N R 2 ′ )NR](THF)} 2 [R= i ‐Pr, N R 2 ′ =N( i ‐Pr) 2 ( 1 ), N(CH 2 ) 5 ( 2 ); R=Cy, N R 2 ′ =N( i ‐Pr) 2 ( 3 ), N(CH 2 ) 5 ( 4 )]. Treatment of ZrCl 4 with freshly prepared solutions of their lithium guanidinates provided a series of bis(guanidinate) complexes of Zr with the general formula Zr[RNC(N R 2 ′ )NR] 2 Cl 2 [R= i ‐Pr, NR 2 ′ =N( i ‐Pr) 2 ( 5 ), N(CH 2 ) 5 ( 6 ); R=Cy, N R 2 ′ =N( i ‐Pr) 2 ( 7 ), N(CH 2 ) 5 ( 8 )]. Complexes 1 , 2 , 5 – 8 were characterized by elemental analysis, IR and 1 H NMR spectra. The molecular structures of complexes 1 , 7 and 8 were further determined by X‐ray diffraction studies.