Solid State Structures and Solution Dynamics of Unsolvated and Diethyl Ether Solvated Dilithium N,N'-Bis(trimethylsilyl)ethylenediamide Complexes

Michael G. Gardiner, Colin L. Raston

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

The lithiation of N,N'-bis(trimethylsilyl)ethylenediamine, 1, by 2 equiv of methyllithium in diethyl ether yields the dimeric diethyl ether adduct [{Li[N(SiMe3)CH2CH2NSiMe 3]Li·OEt2}2], 2. Recrystallization of 2 from benzene gives quantitatively the unsolvated trimer [{Li[N(SiMe3)CH2CH2NSiMe3]Li} 3], 3. The solution dynamics of 2 and 3 in toluene have been investigated using variable temperature multinuclear NMR spectroscopy. In solution, 2 is undergoing a rapid exchange process involving an equilibrium between unsolvated and diethyl ether solvated dimers, whereas compound 3 exists in a temperature dependent equilibrium of dimeric and trimeric species, of which the trimer is fluxional and exchanges inequivalent ligands by an intramolecular distortion of the Li6N6 cage structure. Crystals of 2 are monoclinic, of space group P21/n (No. 14), with a = 10.692(9) Å, b= 16.192(2) Å, c = 24.04(4) Å, β= 101.16(5)°, V = 4083(8) Å3, and Z = 4. Crystals of 3 are trigonal, of space group R3̄m (No. 166), a = 17.765(1) Å, c = 13.394(1) Å, V = 3660.5(5) Å3, Z = 3.

Original languageEnglish
Pages (from-to)4162-4169
Number of pages8
JournalInorganic Chemistry
Volume35
Issue number14
DOIs
Publication statusPublished - 1 Dec 1996
Externally publishedYes

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