Role of trace amine in the metathesis of imines by CpTa(=NR)Cl-2

Tantalum imido compound CpTa(=NBut)Cl-2 (1) reacts with imines to give NR exchange (metathesis) products. Addition of < 5 mol % of compound I to a 1: 1 mixture of two different imines resulted in catalytic cross metathesis of the two imines to give an equilibrium mixture of imines. Kinetic studie...

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Bibliographic Details
Published inOrganometallics Vol. 21; no. 9; pp. 1933 - 1941
Main Authors Burland, MC, Pontz, TW, Meyer, TY
Format Journal Article
LanguageEnglish
Published WASHINGTON Amer Chemical Soc 29.04.2002
Subjects
Chemistry
Chemistry, Inorganic & Nuclear
Chemistry, Organic
Physical Sciences
Science & Technology
IMIDO COMPLEXES
NIOBIUM
OXO
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Summary:Tantalum imido compound CpTa(=NBut)Cl-2 (1) reacts with imines to give NR exchange (metathesis) products. Addition of < 5 mol % of compound I to a 1: 1 mixture of two different imines resulted in catalytic cross metathesis of the two imines to give an equilibrium mixture of imines. Kinetic studies of the reaction of I with excess imine (Bu-t)HC=N(p-tolyl) (2a) gave an average k(obs) of 1.29 x 10(-1) min(-1) (sigma 0.28). Pseudo-first-order behavior was observed for 1. The dependence of k(obs) on the concentration of 2a was found to be nonlinear and dependent on catalytic amounts of contaminant amine p-tolylamine (9). Reaction of 1 with tert-butylamine 6) results in the formation of the imide/amide CpTa(=NBut)(NHBut)Cl 7) and HCl. Compound 7 did not react with imines to give exchange products, so it is proposed that the reaction of 1 with imines is significantly accelerated by the presence of HCl.
ISSN:0276-7333
1520-6041
DOI:10.1021/om011085v