Neutral and Cationic Group 4 Complexes Containing Bis(borylamide) Ligands, [R2BNCH2CH2NBR2]2- (R = 2,4,6-i-Pr3C6H2, M = Zr; R = Cyclohexyl, M = Ti, Zr, Hf)
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Reaction of Li2(TripBen)(THF)4 ([(2,4,6-i-Pr3C6H2)2BNCH2CH2NB(2,4,6-i-Pr3C6H2)2]2- = (TripBen)2-) with ZrCl4(THF)2 in toluene cleanly provides (TripBen)ZrCl2. (TripBen)ZrCl2 can be alkylated with Grignard reagents to yield the dimethyl (2), diethyl (3), and dibutyl (4) derivatives, (TripBen)ZrR2. The structure of (TripBen)Zr(CD3)2 reveals that π bonding between boron and nitrogen results in one Trip ring on each boron being oriented over the two alkyl groups. The reaction between (TripBen)ZrMe2 and B(C6F5)3 in pentane yields colorless crystals of {(TripBen)ZrMe}{MeB(C6F5)3} (5a). The dialkyl complexes 2−4 react with [HNMe2Ph][B(C6F5)4] in toluene to yield free dimethylaniline and species that are identical to 5a according to NMR spectra. (CyBen)M(CH2SiMe3)2 complexes ([(cyclohexyl)2BNCH2CH2NB(cyclohexyl)2]2- = (CyBen)2-) are prepared by the reaction between Li2(CyBen)(ether) and M(CH2SiMe3)2Cl2(ether)x (M = Ti, Zr, or Hf). (CyBen)MI2 complexes are formed upon treating (CyBen)M(CH2SiMe3)2 complexes with io...