Relative reactivity of the metal-amido versus metal-imido bond in linked cp-amido and half-sandwich complexes of vanadium

Marco W. Bouwkamp, Aurora A. Batinas, Peter T. Witte, Ton Hubregtse, Jeroen Dam, Auke Meetsma, Jan H. Teuben, Bart Hessen*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

12 Citations (Scopus)
617 Downloads (Pure)

Abstract

Treatment of (eta(5)-C(5)H(4)C(2)H(4)NR)V(N-t-Bu)Me (R = Me, i-Pr) and CpV(N-p-Tol)(N-i-Pr(2))Me (Cp = eta(5)-C(5)H(5)) with B(C(6)F(5))(3) or [Ph(3)C][B(C(6)F(5))(4)] results in formation of the corresponding cations, [(eta(5)-C(5)H(4)C(2)H(4)NR)V(N-t-Bu)](+) and [CpV(N-p-Tol)(N-i-Pr(2))](+). The latter could also be generated as its N,N-dimethylaniline adduct by treatment of the methyl complex with [PhNMe(2)H][BAr(4)] (Ar = Ph, C(6)F(5)). Instead, the analogous reaction with the linked Cp-amido precursor results in protonation of the imido-nitrogen atom. Sequential cyclometalation of the amide substituents gave cationic imine complexes [(eta(5)-C(5)H(4)C(2)H(4)NCR'(2))V(NH-t-Bu)](+) (R'= H, Me) and methane. Reaction of cationic [(eta(5)-C(5)H(4)C(2)H(4)NR)V(N-t-Bu)](+) with olefins affords the corresponding olefin adducts, whereas treatment with 1 or 2 equiv of 2-butyne results in insertion of the alkyne into the vanadium-nitrogen single bond, affording the mono- and bis-insertion products [(eta(5)-C(5)H(4)C(2)H(4)N(i-Pr)C(2)Me(2))V(N-t-Bu)](+) and [(eta(5)-C(5)H(4)C(2)H(4)N(i-Pr)C(4)Me(4))V(N-t-Bu)](+). The same reaction with the half-sandwich compound [CpV(N-p-Tol)(N-i-Pr(2))](+) results in a paramagnetic compound that, upon alcoholysis, affords sec-butylidene-p-tolylamine, suggesting an initial [2+2] cycloaddition reaction. The difference in reactivity between the V-N bond versus the V=N bond was further studied using computational methods. Results were compared to the isoelectronic titanium system CpTi(NH)(NH(2)). These studies indicate that the kinetic product in each system is derived from a [2+2] cycloaddition reaction. For titanium, this was found as the thermodynamic product as well, whereas the insertion reaction was found to be thermodynamically more favorable in the case of vanadium.

Original languageEnglish
Pages (from-to)4071-4082
Number of pages12
JournalOrganometallics
Volume27
Issue number16
DOIs
Publication statusPublished - 25-Aug-2008

Keywords

  • ORGANOLANTHANIDE-CATALYZED HYDROAMINATION
  • UNPROTECTED AMINO OLEFINS
  • INTERMOLECULAR HYDROAMINATION
  • MOLECULAR-STRUCTURE
  • TRANSITION-METALS
  • ALKYNES
  • POLYMERIZATION
  • TANTALUM
  • LIGAND
  • D(0)

Cite this