SYNTHESIS AND CHARACTERIZATION OF LITHIUM, ZIRCONIUM, AND HAFNIUM DERIVATIVES OF N-ISOPROPYL-2-(ISOPROPYLAMINO)TROPONIMINATE

The reaction of N-isopropyl-2-(isopropylamino)troponimine, [(i-Pr)(2)A TI]H, with n-BuLi in Et(2)O-THF gave [(i-Pr)(2)ATI]Li(THF)(2) in excel lent yield. The [(i-Pr)(2)ATI]2ZrCl2 and [(i-Pr)(2)ATI]2HfCl2 complexe s were prepared by treating the respective metal tetrachlorides with 2 equiv of the lithium adduct. These metal complexes were characterized by NMR spectroscopy and X-ray crystallography. X-ray crystallographic data of the lithium, zirconium, and hafnium complexes show monomeric structures in the solid state. The lithium complex has a tetrahedral l ithium ion and a slightly twisted C7N2Li framework. The zirconium and hafnium metal centers in [(i-Pr)(2)ATI]2ZrCl2 and [(i-Pr)(2)ATI]2HfCl2 show pseudooctahedral geometry with chlorides occupying the cis posit ions. The dialkyl derivative [(i-Pr)(2)ATI]Zr-2(CH(2)SiMe(3))(2) was p repared by treating Zr(CH(2)SiMe(3))(4) with 2 equiv of the free ligan d [(i-Pr)(2)ATI]H. Crystal data with Mo K alpha (lambda = 0.710 73 Ang strom) at 193 K: [(i-Pr)(2)ATI]Li(THF)(2), C21H35LiN2O2, a = 9.2318(8) Angstrom, b = 14.624(2) Angstrom, c = 16.071(2) Angstrom, beta = 94.9 54(5)degrees, V = 2661.3(5) Angstrom(3), monoclinic, space group P2(1) /n, Z = 4, R = 0.0607; [(i-Pr)(2)ATI]2ZrCl2, C26H38Cl2N4Zr, a = 9.569( 3) Angstrom, b = 15.877(4) Angstrom, c = 18.241(6) Angstrom, beta = 94 .480(10)degrees, V = 2763.0(14) Angstrom(3), monoclinic, space group P 2(1)/n, Z = 4, R = 0.0401; [(i-Pr)(2)ATI]2HfCl2, C26H38Cl2HfN4, a = 9. 540(1) Angstrom, b = 15.813(2) Angstrom, c = 18.118(3) Angstrom, beta = 94.546(11)degrees, V = 2724.8(7) Angstrom(3), monoclinic, space grou p P2(1)/n, Z = 4, R = 0.0313.