10.1021/om000630+.s001
Jae E. Park
Jae E.
Park
Byoung-Jae Bae
Byoung-Jae
Bae
Kwangyeol Lee
Kwangyeol
Lee
Joon T. Park
Joon T.
Park
Hong Young Chang
Hong Young
Chang
Moon-Gun Choi
Moon-Gun
Choi
Reaction of GaMe<sub>3</sub> with H<sub>2</sub>NCH<sub>2</sub>CH<sub>2</sub>NMe<sub>2</sub>: Synthesis and
Characterization of Adducts and Imidogallane
American Chemical Society
2000
GaMe 3
C 2 axis
mol
tran
1 H NMR spectroscopy
inequivalent GaMe 3 moieties
Å.
NMe 2 end
cis isomer equilibrates
C 2 symmetry
CH
Ga 2 N 2 ring
DMEDA
kJ
NCH
2000-10-25 00:00:00
Dataset
https://acs.figshare.com/articles/dataset/Reaction_of_GaMe_sub_3_sub_with_H_sub_2_sub_NCH_sub_2_sub_CH_sub_2_sub_NMe_sub_2_sub_Synthesis_and_Characterization_of_Adducts_and_Imidogallane/3763791
Reaction of GaMe<sub>3</sub> with <i>N,N</i>-dimethylethylenediamine (DMEDA) produces adducts,
Me<sub>3</sub>Ga:NH<sub>2</sub>C<sub>2</sub>H<sub>4</sub>NMe<sub>2</sub> (1:1, <b>1</b>) and Me<sub>3</sub>Ga:NH<sub>2</sub>C<sub>2</sub>H<sub>4</sub>NMe<sub>2</sub>:GaMe<sub>3</sub> (2:1, <b>2</b>). A fast concerted
intermolecular exchange of the two inequivalent GaMe<sub>3</sub> moieties occurs in <b>2</b> at room
temperature. Thermolysis of <b>2</b> at 210 °C in a sealed ampule produces a mixture of cis and
trans isomers of tetrametallic imidogallane, (<b>3</b>). Slow
recrystallization of <b>3</b> affords only the cis isomer as colorless crystals, but in solution the cis
isomer equilibrates with the trans isomer. The cis → trans isomerization of <b>3</b> has been studied
by <sup>1</sup>H NMR spectroscopy. The equilibrium has been observed to follow reversible first-order
kinetics with Δ<i>H</i>° = − 3.35 ± 1.70 kJ mol<sup>-1</sup> and Δ<i>S</i>° = − 10.4 ± 1.7 J mol<sup>-1</sup> K<sup>-1</sup>. The
activation parameters for the cis → trans conversion are Δ
= 144.6 ± 6.2 kJ mol<sup>-1</sup> and Δ
= 105.6 ± 1.5 J mol<sup>-1</sup> K<sup>-1</sup>, and those for the reverse process are Δ
= 147.6 ± 6.4 kJ
mol<sup>-1</sup> and Δ
= 115.4 ± 1.5 J mol<sup>-1</sup> K<sup>-1</sup>. The isomerization process has been proposed to
be assisted by the NMe<sub>2</sub> end of DMEDA as an internal Lewis base. The molecular structures
of <b>2</b> and <i>cis</i>-<b>3</b> have been determined by single-crystal X-ray diffraction studies. The geometry
about the gallium atom of <b>2</b> is distorted tetrahedral with a Ga−C (av) distance of 1.98(1) Å
and a Ga−N distance of 2.16(1) Å. The molecular geometry of <i>cis</i>-<b>3</b> involves one four-membered Ga<sub>2</sub>N<sub>2</sub> ring and two five-membered GaN<sub>2</sub>C<sub>2</sub> rings of cis conformation, and it has
approximate <i>C</i><sub>2</sub> symmetry with the <i>C</i><sub>2</sub> axis going through the center of the Ga<sub>2</sub>N<sub>2</sub> ring.