TY - JOUR
T1 - Polymorphism in lithium amides
T2 - A structural and theoretical study. Synthesis, mechanism, and NMR studies of the lithiation of N,N'-Di-tert-butylethylenediamine
AU - Gardiner, Michael G.
AU - Raston, Colin L.
PY - 1996/12/1
Y1 - 1996/12/1
N2 - The lithiation of N,N'-di-tert-butylethylenediamine by MeLi in benzene has been shown by 1H NMR spectroscopy to proceed via the partially lithiated species [cis-{Li[μ-N(t-Bu)CH2CH2N(H)t-Bu]}2], 2, and [{Li[N(t-Bu)CH2-CH2N(H)t-Bu]}2Li{N(t-Bu)CH 2CH2Nt-Bu}Li], 3, prior to the formation of the dilithiated species (Li[N(t-Bu)CH2CH2Nt-Bu]Li}, 4. The solid state structures of 2, 3, and a dimeric form of 4 (4a) have been determined. A sparingly soluble form of 4 (4b) has also been isolated which has a proposed polymeric ladder structure. These structures are discussed with respect to the alternatives available for the aggregation of the dilithiated species; stacking to form dimeric Li4N4 cages and laddering to form LinNn ladders. Ab initio molecular orbital calculations give insight into the energetics of these aggregates and the possible structures adopted by solvated and unsolvated dilithium ethylenediamide complexes. Crystals of 2 are monoclinic, of space group C2/c (No. 15), a = 19.222(7), b = 8.734(2), c = 17.149(5) Å, β= 119.40(1)°, Z = 4. Crystals of 3 are monoclinic, of space group P21/c (No. 14), a = 9.836(8), b = 17.821(3), c = 21.78(2) Å, β = 101.57(4)°, 2 = 4. Crystals of 4a are monoclinic, of space group P21/c (No. 14), a = 15.990(7), b = 10.0162(9), c = 16.42(1) Å, β = 104.49(2)°, Z = 4. Crystals of 6 are monoclinic, of space group P21/c (No. 14), a = 10.124(8), b = 17.861(3), c = 22.21(2) Å, β = 102.05(4)°, Z = 4.
AB - The lithiation of N,N'-di-tert-butylethylenediamine by MeLi in benzene has been shown by 1H NMR spectroscopy to proceed via the partially lithiated species [cis-{Li[μ-N(t-Bu)CH2CH2N(H)t-Bu]}2], 2, and [{Li[N(t-Bu)CH2-CH2N(H)t-Bu]}2Li{N(t-Bu)CH 2CH2Nt-Bu}Li], 3, prior to the formation of the dilithiated species (Li[N(t-Bu)CH2CH2Nt-Bu]Li}, 4. The solid state structures of 2, 3, and a dimeric form of 4 (4a) have been determined. A sparingly soluble form of 4 (4b) has also been isolated which has a proposed polymeric ladder structure. These structures are discussed with respect to the alternatives available for the aggregation of the dilithiated species; stacking to form dimeric Li4N4 cages and laddering to form LinNn ladders. Ab initio molecular orbital calculations give insight into the energetics of these aggregates and the possible structures adopted by solvated and unsolvated dilithium ethylenediamide complexes. Crystals of 2 are monoclinic, of space group C2/c (No. 15), a = 19.222(7), b = 8.734(2), c = 17.149(5) Å, β= 119.40(1)°, Z = 4. Crystals of 3 are monoclinic, of space group P21/c (No. 14), a = 9.836(8), b = 17.821(3), c = 21.78(2) Å, β = 101.57(4)°, 2 = 4. Crystals of 4a are monoclinic, of space group P21/c (No. 14), a = 15.990(7), b = 10.0162(9), c = 16.42(1) Å, β = 104.49(2)°, Z = 4. Crystals of 6 are monoclinic, of space group P21/c (No. 14), a = 10.124(8), b = 17.861(3), c = 22.21(2) Å, β = 102.05(4)°, Z = 4.
UR - http://www.scopus.com/inward/record.url?scp=0001749104&partnerID=8YFLogxK
U2 - 10.1021/ic951251p
DO - 10.1021/ic951251p
M3 - Article
AN - SCOPUS:0001749104
VL - 35
SP - 4047
EP - 4059
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 13
ER -