TY - JOUR
T1 - Structures of Lithium Salts of 2, 3, 3-Trimethylindolenine and Its 5-Methoxy Derivative in Solution and the Solid State
AU - Jackman, L. M.
AU - Scarmoutzos, L. M.
AU - Smith, B. D.
AU - Williard, Paul G.
PY - 1988/8
Y1 - 1988/8
N2 - An X-ray crystal structure of lithium 2, 3, 3-trimethylindolenide etherate shows it to be a disolvated dimer having a η3-azaallyl-type structure. The structures of the salt in several solvents have been established by studies of 13C chemical shifts, 6Li, 15N spin-spin splitting, 7Li quadrupole splitting constants, and apparent degrees of aggregation determined by vapor pressure barometry. It is the η3-azaallyl dimer disolvate in diethyl ether, a tetrasolvated dimer in dioxolane, a mixture of monomer and tetrasolvated dimer in tetrahydrofuran, and a monomer in pyridine. The species are characterized by 7Li quadrupole splitting constants of 230, 156, 180–190 (0.27-0.75 M), and 217 kHz, respectively. In diethyl ether with 4 equiv of hexamethylphosphoric triamide, the salt is a mixture of monomeric and triple ion species. Lithium 5-methoxy-2, 3, 3-trimethylindolenide forms similar species except that, in tetrahydrofuran, the tendency for dimer formation is enhanced, which leads to a higher proportion of C- to N-methylation in its reaction with methyl chloride in that solvent.
AB - An X-ray crystal structure of lithium 2, 3, 3-trimethylindolenide etherate shows it to be a disolvated dimer having a η3-azaallyl-type structure. The structures of the salt in several solvents have been established by studies of 13C chemical shifts, 6Li, 15N spin-spin splitting, 7Li quadrupole splitting constants, and apparent degrees of aggregation determined by vapor pressure barometry. It is the η3-azaallyl dimer disolvate in diethyl ether, a tetrasolvated dimer in dioxolane, a mixture of monomer and tetrasolvated dimer in tetrahydrofuran, and a monomer in pyridine. The species are characterized by 7Li quadrupole splitting constants of 230, 156, 180–190 (0.27-0.75 M), and 217 kHz, respectively. In diethyl ether with 4 equiv of hexamethylphosphoric triamide, the salt is a mixture of monomeric and triple ion species. Lithium 5-methoxy-2, 3, 3-trimethylindolenide forms similar species except that, in tetrahydrofuran, the tendency for dimer formation is enhanced, which leads to a higher proportion of C- to N-methylation in its reaction with methyl chloride in that solvent.
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U2 - 10.1021/ja00226a021
DO - 10.1021/ja00226a021
M3 - Article
AN - SCOPUS:0000873439
SN - 0002-7863
VL - 110
SP - 6058
EP - 6063
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 18
ER -