2.4 Single-Crystal Structure Analyses
27
2.4 Single-Crystal Structure Analyses
To obtain precise structural information about the 3/solvent samples, we prepared
single crystals corresponding to their powder forms. After repeated trials, we obtained
eleven different single crystals of 3/solvent by recrystallization from eleven solvents
(Fig. 2.4a, and Table 2.1). Typical conditions to prepare single crystals of 3/solvent
are as follows: 3 was dissolved in a solvent to induce inclusion, and then stored for 12 h
in a freezer at −25 °C to give single crystals of 3/solvent. Emission colors (Fig. 2.37)
and excitation/emission spectra (Fig. 2.38) of the single crystals of 3/solvent are very
similar to those of the powders prepared by addition and evaporation of the same
solvents. In addition, simulated powder patterns derived from these single crystals
of 3/solvent match the XRD patterns of the powder forms (Fig. 2.39). These results
clearly indicate that the molecular arrangements of the single crystals correspond
to those of the powder forms of 3/solvent. All 3/solvent samples contain solvent
molecules used in the recrystallization (0.25–1 equiv; Table 2.1), which is consistent
with the NMR spectra of the powder forms of 3/solvent (Fig. 2.18). In addition, when
trichloroethene was used for recrystallization of 3, a single crystal of 3/none without
any solvent molecules formed (blue dotted squares in Fig. 2.8 and Table 2.1). The
powder pattern simulated from the single crystal of 3/none did not match the XRD
pattern of the powder of 3 obtained by the addition of trichloroethene. This indicates
that, different from the solvents used in 3/solvent, trichloroethene cannot effectively
induce crystal formation of 3 when trichloroethene is simply added to 3 ground . As
shown in Fig. 2.8b, the dozen single-crystal structures of 3, eleven 3/solvent and
one 3/none, are different from each other (crystallographic parameters are listed in
Table 2.5).
As a representative example of a single-crystal structure of 3/solvent, the singlecrystal structure of 3/CH 2 Cl 2 is shown in Fig. 2.9. We found that 3/CH 2 Cl 2 crystallized into monoclinic space group I2/a (Table 2.1). The simulated powder pattern
derived from the 3/CH 2 Cl 2 single crystal matches the experimental XRD pattern of
the powder form of this complex (Fig. 2.39). As illustrated in Fig. 2.9a, the gold
complexes in 3/CH 2 Cl 2 form a dimeric structure containing three intermolecular
Au···Au interactions with Au···Au distance of 3.164, 3.291, and 3.164 Å (Fig. 2.9a).
The two molecules in each dimer adopt the same conformational enantiomer, as
shown in Fig. 2.9a. The dimers in 3/CH 2 Cl 2 further interact with neighboring ones
through aurophilic and slipped π–π stacking interactions (Au···Au and π···π distances of 3.566 and 3.309 Å, respectively; Fig. 2.9b). Between the two gold atoms
of the dimers, there is an inversion center (denoted as a purple square in Fig. 2.9).
These intermolecular interactions between the dimers afford an infinite columnar
motif (Figs. 2.8b and 2.9c). Adjacent dimers always include molecules with the
opposite conformational enantiomers. Thus, the columns consist of an alternating
sequence of dimers with the opposite conformational enantiomers in which the chiral structures of complexes are ···RRSSRRSS··· (Fig. 2.9c). The neighboring columns
(see green and light-blue columns in Fig. 2.9d) align parallel to each other. Included
27
2.4 Single-Crystal Structure Analyses
To obtain precise structural information about the 3/solvent samples, we prepared
single crystals corresponding to their powder forms. After repeated trials, we obtained
eleven different single crystals of 3/solvent by recrystallization from eleven solvents
(Fig. 2.4a, and Table 2.1). Typical conditions to prepare single crystals of 3/solvent
are as follows: 3 was dissolved in a solvent to induce inclusion, and then stored for 12 h
in a freezer at −25 °C to give single crystals of 3/solvent. Emission colors (Fig. 2.37)
and excitation/emission spectra (Fig. 2.38) of the single crystals of 3/solvent are very
similar to those of the powders prepared by addition and evaporation of the same
solvents. In addition, simulated powder patterns derived from these single crystals
of 3/solvent match the XRD patterns of the powder forms (Fig. 2.39). These results
clearly indicate that the molecular arrangements of the single crystals correspond
to those of the powder forms of 3/solvent. All 3/solvent samples contain solvent
molecules used in the recrystallization (0.25–1 equiv; Table 2.1), which is consistent
with the NMR spectra of the powder forms of 3/solvent (Fig. 2.18). In addition, when
trichloroethene was used for recrystallization of 3, a single crystal of 3/none without
any solvent molecules formed (blue dotted squares in Fig. 2.8 and Table 2.1). The
powder pattern simulated from the single crystal of 3/none did not match the XRD
pattern of the powder of 3 obtained by the addition of trichloroethene. This indicates
that, different from the solvents used in 3/solvent, trichloroethene cannot effectively
induce crystal formation of 3 when trichloroethene is simply added to 3 ground . As
shown in Fig. 2.8b, the dozen single-crystal structures of 3, eleven 3/solvent and
one 3/none, are different from each other (crystallographic parameters are listed in
Table 2.5).
As a representative example of a single-crystal structure of 3/solvent, the singlecrystal structure of 3/CH 2 Cl 2 is shown in Fig. 2.9. We found that 3/CH 2 Cl 2 crystallized into monoclinic space group I2/a (Table 2.1). The simulated powder pattern
derived from the 3/CH 2 Cl 2 single crystal matches the experimental XRD pattern of
the powder form of this complex (Fig. 2.39). As illustrated in Fig. 2.9a, the gold
complexes in 3/CH 2 Cl 2 form a dimeric structure containing three intermolecular
Au···Au interactions with Au···Au distance of 3.164, 3.291, and 3.164 Å (Fig. 2.9a).
The two molecules in each dimer adopt the same conformational enantiomer, as
shown in Fig. 2.9a. The dimers in 3/CH 2 Cl 2 further interact with neighboring ones
through aurophilic and slipped π–π stacking interactions (Au···Au and π···π distances of 3.566 and 3.309 Å, respectively; Fig. 2.9b). Between the two gold atoms
of the dimers, there is an inversion center (denoted as a purple square in Fig. 2.9).
These intermolecular interactions between the dimers afford an infinite columnar
motif (Figs. 2.8b and 2.9c). Adjacent dimers always include molecules with the
opposite conformational enantiomers. Thus, the columns consist of an alternating
sequence of dimers with the opposite conformational enantiomers in which the chiral structures of complexes are ···RRSSRRSS··· (Fig. 2.9c). The neighboring columns
(see green and light-blue columns in Fig. 2.9d) align parallel to each other. Included