P.A. Poltarak et al.
Inorganica Chimica Acta 488 (2019) 285–291
2
. Experimental
Table 1
Crystal data and structural refinement for Ti
4
Se
I
9 6.
2.1. Materials and methods
Empirical formula
4 9 6
Ti Se I
Formula weight
1663.64
298
Titanium powder (−60 + 100 mesh, 99.5% (metals basis)) was
Temperature/K
purchased from Alfa Aesar, powder selenium (99.99%, particles size
Crystal system
triclinic
P-1
5
0 μm) was purchased from Ural Mining and Metallurgical Company
Space group
(
Russia), and iodine (99%) was obtained from Scientific and production
a/Å
b/Å
c/Å
α/°
β/°
γ/°
7.9652(10)
association “Iodobrom” (Russia). Glass tubes from Simax company was
used for preparation of ampoules.
10.3390(15)
15.692(2)
79.116(7)
75.861(7)
71.437(7)
1179.2(3)
2
X-ray powder diffraction patterns for solids were collected with a
Philips PW 1830/1710 automated diffractometer (Cu Kα radiation,
graphite monochromator, silicon plate as an external standard). Raman
spectra were recorded with a labRAM HR Evolution spectrometer
3
Volume/Å
Z
3
−
1
ρcalcg/cm
4.685
(
HORIBA Scientific) in the region 15–500 cm . Far infra-red spectra
−
1
μ/mm
23.034
were recorded with a FTIR spectrometer VERTEX 80 (Bruker). Energy-
dispersive spectroscopy was performed with a Hitachi TM3000 device.
Thermogravimetric analysis was carried out with NETZSCH TG 209 F1
Iris Thermo Microbalance instrument.
F(0 0 0)
1424.0
3
Crystal size/mm
Radiation
0.102 × 0.054 × 0.026
MoKα (λ = 0.71073)
4.186 to 52.738
2
Θ range for data collection/°
Index ranges
−9 ≤ h ≤ 9, −12 ≤ k ≤ 12, −19 ≤ l ≤ 19
8034
Reflections collected
Independent reflections
Data/restraints/parameters
4819 [Rint = 0.0456, R
4819/0/172
σ
= 0.0801]
2
.2. Synthesis of Ti
4
Se I
9 6
2
Goodness-of-fit on F
0.925
Ti powder (0.144 g, 3.0 mmol) was placed into a small open top
Final R indexes [I > = 2σ (I)]
Final R indexes [all data]
R
R
1
1
= 0.0397, wR
= 0.0714, wR
2
2
= 0.0590
= 0.0645
glass tube. Se powder (0.427 g, 5.4 mmol) and I powder (0.763 g,
2
−
3
Largest diff. peak/hole/e Å
1.36/−1.38
3
.0 mmol) was put to a glass ampule (V = 10 ml) and then the tube
with Ti powder was placed to the mixture of selenium and iodine.
Ampule was evacuated and sealed, then heated up to 250 °C during 2 h,
and kept at this temperature 200 h. The black shiny bars formed at the
ampule walls. The crystals were washed with ethanol and dried on air.
Yield of the product 82% based on selenium load.
2
.4. Details of computational study
Quantum chemical spin-restricted calculations of Ti
4
Se
9
I bulk have
6
−
1
been carried out with DFT method implemented in the BAND 2017
code [23–27]. The density functional was chosen to include the local
density approximation (LDA) with the PW92 parameterization for local
exchange correlations [28] and the generalized gradient approximation
Element ratio: Ti4.0Se8.2I5.2 (EDAX). Raman (cm ): 343 w, 314 m,
2
4
1
60 s, 224 m, 192 vs, 157 w, 145 m, 127 m, 94 m, 79 vs, 63 s, 56 m ,
−1
4 s, 21 vs. IR (cm ): 338 m, 320 sh, 295 w, 269 w, 232 m, 198 s,
53 s, 138 s, 121 s, 94 w (See Figs. S1–S3).
(
GGA) functional PBEsol (PBEsolx and PBEsolc) [29] with the disper-
The X-ray powder diffraction pattern (Fig. S4) of the bulk sample
sion corrections (D3(BJ)) [30]. The standard all electron Slater-type
orbital basis set with core double-ξ valence triple-ξ quality plus two
polarization function (TZ2P) was used for all atoms [31]. Scalar re-
lativistic effects were calculated with ZORA approach [32–36].
Quantum theory of atoms in molecules QTAIM [37–40] was carried
was in good agreement with the pattern calculated on the basis of the
single-crystal structure.
2
.3. X-ray single-crystal experimental details
out to determine the binding nature of atoms in Ti
4
Se
9
I . The Bader's
6
The diffraction data were collected at room temperature on Bruker
types of interatomic interactions (shared, closed shells, etc.) are de-
termined by the following parameters calculated in the bond critical
points (bcp’s): the electron density ρ; the laplacian of electron density
APEX Duo diffractometer with CCD detector using graphite-mono-
chromated MoKα radiation (λ = 0.71073 Å). Preliminary diffraction
experiments carried out on 5 samples, all they have revealed strong
tendency to twinning. The sample with apparent prevalence of one
domain was selected for the diffraction data collection, the data col-
lection was carried out using 0.5° ω- and φ-scanning. Data reduction
was performed via APEX-II suite [20]. Visual analysis of reciprocal
space in RLATT showed the selected sample to be consist of two crystal
domains, non-merohedrally twinned by 180° rotation around direction
with (1 1 1) reciprocal space indices. Integration of reflection intensities
was carried out over two domains using SAINT [20] program, absorp-
tion correction was applied empirically using TWINABS [20] program
2
∇ ρ; the kinetic (G) and potential (U) energy densities, and the total
energy density (E = U + G). The following ratios |U|/G characterize
interactions between atoms: |U|/G < 1 for interactions of atom closed
shells, |U|/G > 2 for covalent interactions, and 1 < |U|/G < 2 for
intermediate type interaction.
3. Result and discussion
3.1. Synthesis of Ti
4
Se
9
I
6
(
domain fractions 0.75/0.25). The structure was solved by direct
method and refined by the full-matrix least-squares method against the
Titanium selenoiodide Ti
4
Se
9
I
6
formed as black crystals at 250 °C in
= 5:9:5, ti-
stoichio-
2
major domain HKL4 |F| data with anisotropic atomic displacements
ampule synthesis from the elements in molar ratio Ti:Se:I
2
using SHELXTL program pack [21] supported with Olex2 GUI [22].
Attempted refinement using HKLF5 data gave slightly higher value of
R-factor and did not improved the structure model. Crystallographic
data for the structural analysis have been deposited with the Cambridge
Crystallographic Data Centre, CCDC No. 1855072. Copies of the data
can be obtained free of charge from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44-1223-
tanium and iodine were taken in some excess to the Ti
4
Se
9 6
I
metry. When simple mixture of titanium, selenium and iodine powders
was heated in ampule, the surface of titanium powder turned out to be
covered by reaction products which significantly decreased reaction
rate; also, this product did not match to the Ti
4
Se
9
I according to
6
powder XRD. In order to separate titanium and selenium in the ampule,
titanium powder was put into a narrow glass tube, which in turn was
placed to the mixture of selenium and iodine. This approach provided in
3
36-033; e-mail:deposit@ccdc.cam.ac.uk). Crystal data and structural
Se are summarized in Table 1.
refinement for Ti
4
I
9 6
situ generation of TiI vapors in the ampule volume, thus presenting
4
286