TY - JOUR
T1 - Solid State Structures and Solution Dynamics of Unsolvated and Diethyl Ether Solvated Dilithium N,N'-Bis(trimethylsilyl)ethylenediamide Complexes
AU - Gardiner, Michael G.
AU - Raston, Colin L.
PY - 1996/12/1
Y1 - 1996/12/1
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0000700235&partnerID=8YFLogxK
U2 - 10.1021/ic9510425
DO - 10.1021/ic9510425
M3 - Article
AN - SCOPUS:0000700235
SN - 0020-1669
VL - 35
SP - 4162
EP - 4169
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 14
ER -