5.3 Single Crystal X-ray Diffraction Analyses
131
5.3 Single Crystal X-ray Diffraction Analyses
Subsequently, we performed single-crystal XRD measurements on the crystalline
samples (Fig. 5.3). 3G/MeOH crystallizes in the acentric polar space group Pna2 1 ,
and molecules of the recrystallization solvent MeOH were included in the crystal
structure (Fig. 5.3 and Table 5.1). The
1 H NMR spectrum of 3G/MeOH indicated
the inclusion of MeOH in the crystal. The axial chirality of the biaryl moiety in 3
results in the formation of (R)-3 and (S)-3 conformers. These molecules adopt the
same dihedral angels between the phenyl and naphthyl rings of the biaryl moiety
(θ ph-naph ) of 60.0(3)° [(S)-3] and −60.0(3)° [(R)-3]. The dihedral angle between the
phenyl ring on the gold atom and that in the isocyanide ligand (θ ph-ph ) is 83.1(4)° in
both conformers (Fig. 5.3a). The (R)-3 and (S)-3 conformers form a dimer with no
inversion center, connected via an aurophilic interaction [Au…Au: 3.3096(5) Å] and
two CH-π interactions (H…phenyl ring: 2.794(12) and 2.771(12) Å) (Fig. 5.3a). As
illustrated in Fig. 5.3b, the dimer in 3G/MeOH also interacts with adjacent dimers
of the same conformation through aurophilic [Au…Au: 3.3096(5) Å] and CH-π
(H…phenyl ring: 2.771(12) Å) interactions, forming a column. It should be noted that
the dimers in the column are oriented in the same direction (Fig. 5.3b). The column
itself does not contain an inversion center, and neighboring columns (see light gray
and orange columns in Fig. 5.3c) are oriented in opposite directions, whereby the
absence of inversion centers confirms the aforementioned polar space group. The
included MeOH molecules ([3]/[MeOH] = 0.5, see Table 5.1) are located between
the columns, and neighboring MeOH molecules interact via hydrogen bonds (O…O:
2.64(2) and 2.634(18) Å). Clear interactions were not observed between molecules
of 3 in the columns and MeOH (Fig. 5.3c, d), implying that MeOH should be easily
released from this structure. Face index measurements revealed that the columns and
MeOH molecules extend along the long axis of the 3G/MeOH crystal (Fig. 5.3c, d).
In contrast to 3G/MeOH, the orange-emitting crystal 3O scsc , which was obtained
from cutting 3G/MeOH, crystallizes in the centrosymmetric space group P-1 and
does not include any solvent molecules.
1 H NMR spectroscopic, elemental, and
thermogravimetric (TGA) analyses of 3O obtained from recrystallization did not
support the inclusion of any solvent in the crystal (Fig. 5.15 and Table 5.2). The dimer
unit in 3O scsc contains (S)-3 and (R)-3 conformers arranged in an antiparallel manner
with an inversion center through aurophilic interactions [Au…Au: 3.2077(3) Å]
(Fig. 5.4a). The θ ph-naph dihedral angle of the (S)-3 conformer in 3O scsc is 67.86(7)°,
while the θ ph-ph angle in the conformers is 33.03°, which is smaller than that in
the 3G/MeOH crystal. Neighboring dimers are packed so as to form an inversion
center through π–π interactions [naphthyl…naphthyl rings: 3.470(4) Å] (Fig. 5.4b,
c). The crystallographic data thus indicate that the polar solvated 3G/MeOH crystal
is transformed upon exposure to mechanical stress into the centrosymmetric 3O scsc
crystal under concomitant release of the solvent molecules.
131
5.3 Single Crystal X-ray Diffraction Analyses
Subsequently, we performed single-crystal XRD measurements on the crystalline
samples (Fig. 5.3). 3G/MeOH crystallizes in the acentric polar space group Pna2 1 ,
and molecules of the recrystallization solvent MeOH were included in the crystal
structure (Fig. 5.3 and Table 5.1). The
1 H NMR spectrum of 3G/MeOH indicated
the inclusion of MeOH in the crystal. The axial chirality of the biaryl moiety in 3
results in the formation of (R)-3 and (S)-3 conformers. These molecules adopt the
same dihedral angels between the phenyl and naphthyl rings of the biaryl moiety
(θ ph-naph ) of 60.0(3)° [(S)-3] and −60.0(3)° [(R)-3]. The dihedral angle between the
phenyl ring on the gold atom and that in the isocyanide ligand (θ ph-ph ) is 83.1(4)° in
both conformers (Fig. 5.3a). The (R)-3 and (S)-3 conformers form a dimer with no
inversion center, connected via an aurophilic interaction [Au…Au: 3.3096(5) Å] and
two CH-π interactions (H…phenyl ring: 2.794(12) and 2.771(12) Å) (Fig. 5.3a). As
illustrated in Fig. 5.3b, the dimer in 3G/MeOH also interacts with adjacent dimers
of the same conformation through aurophilic [Au…Au: 3.3096(5) Å] and CH-π
(H…phenyl ring: 2.771(12) Å) interactions, forming a column. It should be noted that
the dimers in the column are oriented in the same direction (Fig. 5.3b). The column
itself does not contain an inversion center, and neighboring columns (see light gray
and orange columns in Fig. 5.3c) are oriented in opposite directions, whereby the
absence of inversion centers confirms the aforementioned polar space group. The
included MeOH molecules ([3]/[MeOH] = 0.5, see Table 5.1) are located between
the columns, and neighboring MeOH molecules interact via hydrogen bonds (O…O:
2.64(2) and 2.634(18) Å). Clear interactions were not observed between molecules
of 3 in the columns and MeOH (Fig. 5.3c, d), implying that MeOH should be easily
released from this structure. Face index measurements revealed that the columns and
MeOH molecules extend along the long axis of the 3G/MeOH crystal (Fig. 5.3c, d).
In contrast to 3G/MeOH, the orange-emitting crystal 3O scsc , which was obtained
from cutting 3G/MeOH, crystallizes in the centrosymmetric space group P-1 and
does not include any solvent molecules.
1 H NMR spectroscopic, elemental, and
thermogravimetric (TGA) analyses of 3O obtained from recrystallization did not
support the inclusion of any solvent in the crystal (Fig. 5.15 and Table 5.2). The dimer
unit in 3O scsc contains (S)-3 and (R)-3 conformers arranged in an antiparallel manner
with an inversion center through aurophilic interactions [Au…Au: 3.2077(3) Å]
(Fig. 5.4a). The θ ph-naph dihedral angle of the (S)-3 conformer in 3O scsc is 67.86(7)°,
while the θ ph-ph angle in the conformers is 33.03°, which is smaller than that in
the 3G/MeOH crystal. Neighboring dimers are packed so as to form an inversion
center through π–π interactions [naphthyl…naphthyl rings: 3.470(4) Å] (Fig. 5.4b,
c). The crystallographic data thus indicate that the polar solvated 3G/MeOH crystal
is transformed upon exposure to mechanical stress into the centrosymmetric 3O scsc
crystal under concomitant release of the solvent molecules.