TY - JOUR
T1 - Synthesis, structure and DFT analysis of the THF solvate of 2-picolyllithium
T2 - a 2-picolyllithium solvate with significant carbanionic character
AU - Brouillet, Etienne V.
AU - Kennedy, Alan R.
AU - Krämer, Tobias
AU - Mulvey, Robert E.
AU - Robertson, Stuart D.
AU - Stewart, Alexander
AU - Towie, Stephen
PY - 2020/7/15
Y1 - 2020/7/15
N2 - Previous studies of different solvates of 2-methylpyridyllithium (2-picolyllithium) have uncovered electronic structures corresponding to aza-allyl and enamido resonance forms of the metallated pyridine-based compounds. Here, we report the synthesis and characterisation of [2-CH2Li (THF)2C5H4N], a new THF solvate. X-ray crystallographic studies reveal a dimeric arrangement featuring a non-planar eight-membered [NCCLi]2ring, in which the primary cation-anion interaction is between the Li centre and the C atom of the deprotonated methyl group [length, 2.285(2) Å], suggesting a new carbanionic resonance structure for this 2-picolyllithium series. The significant carbanionic character of [2-CH2Li (THF)2C5H4N] was confirmed by gas-phase DFT calculations [B3LYP/6-311+G(d)] with the calculated electron density interrogated by means of quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. For comparison these computational analyses were also performed on the literature structures of[2-CH2Li(2-Picoline) C5H4N] and [2-CH2Li (PMDETA)C5H4N]. In a reactivity study, [2-CH2Li (THF)2C5H4N] was found to undergo nucleophilic addition to pyridine to generate dipyridylmethane in a good yield.
AB - Previous studies of different solvates of 2-methylpyridyllithium (2-picolyllithium) have uncovered electronic structures corresponding to aza-allyl and enamido resonance forms of the metallated pyridine-based compounds. Here, we report the synthesis and characterisation of [2-CH2Li (THF)2C5H4N], a new THF solvate. X-ray crystallographic studies reveal a dimeric arrangement featuring a non-planar eight-membered [NCCLi]2ring, in which the primary cation-anion interaction is between the Li centre and the C atom of the deprotonated methyl group [length, 2.285(2) Å], suggesting a new carbanionic resonance structure for this 2-picolyllithium series. The significant carbanionic character of [2-CH2Li (THF)2C5H4N] was confirmed by gas-phase DFT calculations [B3LYP/6-311+G(d)] with the calculated electron density interrogated by means of quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. For comparison these computational analyses were also performed on the literature structures of[2-CH2Li(2-Picoline) C5H4N] and [2-CH2Li (PMDETA)C5H4N]. In a reactivity study, [2-CH2Li (THF)2C5H4N] was found to undergo nucleophilic addition to pyridine to generate dipyridylmethane in a good yield.
KW - crystallographic analysis
KW - pyridine based compounds
KW - pyridine scaffold stems
UR - https://onlinelibrary.wiley.com/journal/15213749
U2 - 10.1002/zaac.202000006
DO - 10.1002/zaac.202000006
M3 - Article
SN - 0044-2313
VL - 646
SP - 726
EP - 733
JO - Zeitschrift fur Anorganische und Allgemeine Chemie
JF - Zeitschrift fur Anorganische und Allgemeine Chemie
IS - 13
ER -