Carbolithiations of N,N'-Di-tert-butyl-1,4-diazabuta-1,3-diene

Michael G. Gardiner, Colin L. Raston

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Dimeric (E)-4-lithio-1,4-diazabut-1-ene and N,N’-dilithioethylenediamine complexes [cis-{Li[μ-N(t-Bu)CH(t-Bu)CHN-t-Bu]}2] (1) and [{Li[rac-N(t-Bu)CH(Me)CH(Me)N-t-Bu]Li}2] (2) have been prepared by carbolithiations of the l,4-diazabuta-l,3-diene precursor using t-BuLi in pentane or MeLi in Et2O. Hydrolysis of 1 and 2 yields the substituted (E?)1,4-diazabut-1-ene HN(t-Bu)CH(t-Bu)CHNt-Bu (3) and the racemic 2,3-dimethylethylenediamine rac-HN(t-Bu)CH(Me)CH(Me)N(H)t-Bu (4). Crystals of 1 are monoclinic, space group C2/c (No. 15), a = 10.507(5), b = 15.419(2), and c = 20.075(9) å, ß = 92.13(2)°, V = 3250(2) å3, Z = 4. Crystals of 2 are orthorhombic, space group Fddd (No. 70), a = 9.562(6), b = 18.36(1), and c = 33.04(2) Å, V = 5799(6) Å3, Z = 8. Ab initio calculations on the dimerization of the unsubstituted analogue of 1 (E)-4-lithio-1,4-diazabut-1-ene give relative stabilization energies of 31.91 and 31.99 kcal mol−1 for the amido nitrogen-bridged dimers of Ci, and C2 symmetry, respectively, relative to the monomer of Cs symmetry containing a planar five-membered chelate ring.

Original languageEnglish
Pages (from-to)4206-4212
Number of pages7
JournalInorganic Chemistry
Volume34
Issue number16
DOIs
Publication statusPublished - 1 Aug 1995
Externally publishedYes

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