Synthesis and characterization of multiple and metallacyclic imido compounds of the early transition metals
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The University of Arizona.Rights
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The bis(imido) complex Nb(=NAr)₂Cl(py)₂(Ar=2,6-diisopropylphenyl) reacts with two equivalents of LiNHAr in THF to form [Li(THF)₄)][Nb(=NAr)₂(NHAr)₂] (2). Likewise [Nb(NEt₂)₂Cl₃]₂ reacts with excess LiNHAr in THF to form 2. A similar neutral bis(imide) bis(amide) compound (9) of molybdenum has been made. Experiments are presented that suggest the (tris)imido functional group (Nb(=NAr)₃) - arises via an intermolecular deprotonation of [Nb(=NR)₂(NHR)₂]⁻. Complex 2 reacts with 1 equivalent of ᵗBuLi to form the tris(imide) amide [Li₂(THF)₄][Nb(=NAr)₃(NAr)] (6). Ta(OR)₂Cl₃(OEt₂) (OR=2,6-diisopropylphenoxide) reacts with excess 6-methylquinoline (6MQ) to form (η¹-(N)-6MQ)Ta(OR)₂Cl₃ (10). Compound 10 cannot be reduced to the η²-(N,C) product; however, (η₆-C₆Me₆)Ta(OR)₂Cl reacts with excess 6MQ to form (η²-(N,C)-6MQ)Ta(OR)₂Cl(Et₂O) (11), a precursor to metallacyclic imides and a proposed HDN intermediate. Compound 10 can be reduced to afford an unusual Ta(IV) complex (ηˣ-6MQ)Ta(OR)₂Cl₂ (12).Type
textThesis-Reproduction (electronic)