Preparations of Pure ISeCN, ISCN, and INCO

Article abstract of DOI:10.1021/ic030158v

Pure INCO, ISCN, and the hitherto unknown molecule ISeCN have been prepared in the HeI photoelectron spectrometer (PES) by the heterogeneous reactions of ICI gas with AgNCO, AgSCN at room temperature, and AgSeCN at -9 (±1) °C, respectively. They were characterized on line by PES experiments and OVGF calculations. The well-matched results between the PES experiments and OVGF calculations not only show that the new reaction is a good reaction to prepare pure INCO and pure ISCN, but also that the new compound prepared by passing the ICI gas over the freshly AgSeCN powder at -9(±1) °C is the hitherto unknown ISeCN.

Full text of DOI:10.1021/ic030158v

Inorg. Chem. 2003, 42, 8446−8448
Preparations of Pure ISeCN, ISCN, and INCO
,‡
,†
Li Yimin,†,‡ Qiao Zhimin,† Sun Qiao,† Zhao Jincai,† Li Haiyang,* and Wang Dianxun*
Center of Molecular Science, Institute of Chemistry, Chinese Academy of Science,
Beijing 100080, P. R. China, and Anhui Institute of Optics and Fine Mechanics,
Chinese Academy of Science, Hefei 230031, P. R. China
Received May 14, 2003
Pure INCO, ISCN, and the hitherto unknown molecule ISeCN have been prepared in the HeI photoelectron
spectrometer (PES) by the heterogeneous reactions of ICl gas with AgNCO, AgSCN at room temperature, and
AgSeCN at −9(±1) °C, respectively. They were characterized on line by PES experiments and OVGF calculations.
The well-matched results between the PES experiments and OVGF calculations not only show that the new reaction
is a good reaction to prepare pure INCO and pure ISCN, but also that the new compound prepared by passing the
ICl gas over the freshly AgSeCN powder at −9(±1) °C is the hitherto unknown ISeCN.
Introduction
unknown ISeCN, an improved preparation for the pure
compounds is needed, and this new reaction should easily
be performed.
It is well-known that XNCO, XSCN, and XSeCN (X )
Cl, Br) have been first prepared in the gas phase by
heterogeneous reactions of the chlorine gas and bromine
vapor with corresponding silver salts AgNCO, AgSCN, and
AgSeCN, respectively, and also characterized on line by their
respective PES in combination with sophisticated quantum
chemical calculations.1-3 That is, the PES technique can be
also used to prepare some short-lived compounds by a gas-
solid reaction.
By a procedure analogous to the preparation of BrNCO,
iodine isocyanate (INCO) was also prepared by passing I2
vapor at low pressure over heated and dried AgNCO at ∼190
°C, and its PE spectrum was recorded, but it was also pointed
out that “Spectra completely free of I2 were never obtained”.1
Similarly, gaseous iodine thiocyanate (ISCN) was prepared
at 140 °C, and its PE spectra were also reported,4 but there
are some byproducts in the PE spectrum. No further reports
on either INCO or ISCN have been published, and there is
no previous report on the preparation of selenocyanate
(ISeCN).
Our laboratory has demonstrated the ability to generate a
continuous flowing beam of radicals via the pyrolysis of well-
selected compounds, allowing us to perform PES studies on
short-lived species.5-10 Recently, pure XN3 (X ) F, Cl, Br,
I) compounds have been prepared in the gas phase by
heterogeneous reactions of solid NaN3/AgN3 with gaseous
F2, Cl2, Br2, and I2, respectively, and were characterized on
line by the PES technique combined with the outer valence
green function (OVGF) calculations.11 In this paper, a new
reaction to prepare pure gas-phase INCO, ISCN, and the
hitherto unknown ISeCN is reported. The compounds are
also characterized by the PES technique in combination with
OVGF calculations.
Experimental Section
The precursor ICl was synthesized according to a previously
reported method,12 and its PE spectrum is identical with that
In order to investigate extensively both the physical and
chemical properties of INCO, ISCN, and the hitherto
(5) Zhu, X. J.; Ge, M. F.; Wang, J.; Sun, Z.; Wang, D. X. Angew. Chem.,
Int. Ed. 2000, 112, 2016.
(6) Ge, M. F.; Wang, J.; Zhu, X. J.; Sun, Z.; Yang, X. J.; Wang, D. X. J.
Chem. Phys. 2000, 113 (5), 1866.
(7) Ge, M. F.; Wang, J.; Sun, Z.; Zhu, X. J.; Wang, D. X. J. Chem. Phys.
2001, 114 (7), 3051.
(8) Sun, Z.; Wang, J.; Zhu, X. J.; Ge, M. F.; Wang, D. X. Chem. Eur. J.
2001, 14, 2995.
(9) Wang, J.; Sun, Z.; Zhu, X. J.; Yang, X. J.; Ge, M. F.; Wang, D. X.
Angew. Chem., Int. Ed. 2001, 40, 3055.
(10) Yang, X. J.; Sun, Z.; Ge, M. F.; Zheng, S. J.; Meng, L. P.; Wang, D.
X. ChemPhysChem 2002, 3 (11), 963.
(11) Che, H. J.; Bi, H. M.; Zeng, Y. L.; Meng, L. P.; Zheng, S. J.; Wang,
D. X. ChemPhysChem 2003, 3, 300.
* To whom correspondence should be addressed. E-mail: wangdx@
infoc3.icas.ac.cn (W.D.); hli@aiofm.ac.cn (L.H.).
† Center of Molecular Science, Institute of Chemistry.
‡ Anhui Institute of Optics and Fine Mechanics.
(1) Frost, D. C.; MacDonald, C. B.; McDowell, C. A.; Westwood, N. P.
C. Chem. Phys. 1980, 47, 111.
(2) Frost, D. C.; Macdonald, C. B.; McDowell, C. A.; Westwood, N. P.
C. J. Am. Chem. Soc. 1981, 103, 4423.
(3) Jonkers, G.; Mooyman, R.; De hange, C. A. Mol. Phys. 1981, 43,
655.
(4) Leung, H.; Suffolk, R. J.; Watts, J. D. Chem. Phys. 1986, 109, 289.
8446 Inorganic Chemistry, Vol. 42, No. 25, 2003
10.1021/ic030158v CCC: $25.00 © 2003 American Chemical Society
Published on Web 11/18/2003

Preparations of Pure ISeCN, ISCN, and INCO
Table 1. Optimized Geometrical Structures of ISeCN, ISCN, and
INCO at 6-311++G(2df,pd) Basis Set Level with Four Different
Methods
species
ISeCN
B3P86
B3LYP
B3PW91
MP2
R
R
R
I-Se/Å
Se-C/Å
C-N/Å
ISeC/°
2.4757
1.8272
1.1548
97.7
2.5056
1.8390
1.1550
98.0
2.4798
1.8299
1.1555
97.7
2.4593
1.8233
1.1759
96.7
SeCN/°
ISeCN/°
I-S/Å
S-C/Å
C-N/Å
ISC/deg
SCN/deg
ISCN/deg
I-N/Å
N-C/Å
C-O/Å
177.2
180.0
2.3589
1.6790
1.1561
100.9
175.9
180.0
1.9639
1.2111
1.1601
130.5
173.6
180.0
177.0
180.0
2.3876
1.6867
1.1563
101.3
175.9
180.0
1.9813
1.2124
1.1628
130.2
173.7
180.0
177.1
180.0
2.3619
1.6811
1.1568
100.9
175.9
180.0
1.9663
1.2122
1.1607
130.4
173.6
180.0
177.6
180.0
2.3460
1.6853
1.1766
99.3
176.4
180.0
1.9644
1.2231
1.1698
128.4
173.0
180.0
ISCN
INCO
R
R
R
R
R
R
INC/deg
NCO/deg
INCO/deg
recorded previously.13 AgNCO and AgSCN were bought from the
ACROS Company, and their purity was better than 99%.
AgSeCN, prepared by the reaction between AgNO3 and KSeCN
in aqueous solution, was filtered, washed, dried under vacuum, and
stored in the dark in a desiccator over P2O5.
The AgNCO, AgSCN, and freshly prepared AgSeCN powders
were loosely filled into the quartz inlet tube and supported on quartz
wool. The unstable INCO, ISCN, and ISeCN molecules are prepared
by passing the ICl gas over AgNCO, AgSCN at room temperature,
and freshly prepared AgSeCN at -9 ((1) °C, respectively.
The PE spectra of the INCO, ISCN, and ISeCN molecules were
recorded on a double-chamber UPS machine, which was built
specifically to detect transient species as described elsewhere14 at
Figure 1. PE spectra of ISeCN (a), ISCN (b), and INCO (c).
This fact shows that pure INCO can easily be prepared at
room temperature by the following reaction:
AgNCO(s) + ICl(g) f INCO(g) + AgCl(s)
(1)
a resolution of about 30 meV, as indicated by the Ar+ (2P3/2
)
Furthermore, an X-ray diffraction analysis showed that the
solid residue in the reactor inlet tube was AgCl.15
Pure ISCN is also prepared at room temperature by a
reaction analogous to that described above for INCO:
photoelectron band. Experimental vertical ionization energies (Iv
in eV) are calibrated by simultaneous addition of a small amount
of argon and methyl iodide to the sample.
Outer Valence Green Functional (IVGF) Calculations. In
order to assign the PES bands of the INCO, ISCN, and ISeCN
molecules, outer valence green functional (OVGF) calculations have
been performed. The geometries of INCO, ISCN, and ISeCN
molecules were optimized at 6-311++G (2df,pd) basis set level
with four different methods (see Table 1). The calculations of the
ionization energies used the geometries optimized by B3lYP
method, because no experimental geometries have been reported
until now, and the agreement of the results in the geometry
optimization using the four different methods is good for INCO,
ISCN, and ISeCN. The calculations of the OVGF method are all
at the 6-311++G (2df,pd) level.
AgSCN(s) + ICl(g) f ISCN(g) + AgCl(s)
(2)
Figure 1b gives the PE spectrum of ISCN, which is of
much better quality than the one reported,4 because there
are no signals of impurities and it exhibits a much better
signal-to-noise ratio. This fact again shows that ICl is a good
precursor to prepare pure INCO and ISCN by the hetero-
geneous reaction of ICl(g) with AgNCO and AgSCN,
respectively. ICl is also a good precursor for the preparation
of the hitherto unknown molecule ISeCN by a reaction
analogous to that discussed for INCO and ISCN
Results and Discussion
AgSeCN(s) + ICl(g) f ISeCN(g) + AgCl(s)
(3)
The PE spectrum of the product obtained by the hetero-
geneous reaction of ICl gas with solid AgNCO at room
temperature is given in Figure 1c, which is in accord with
the previously reported PE spectrum of the INCO1 as far as
positions and structures of the PES bands are concerned,
except for the signals of the I2 impurity in the latter spectrum.
but the reaction temperature is -9 ((1) °C, because the
thermal stability of ISeCN is lower than those of INCO and
ISCN.
Figure 1a gives the PE spectrum of the ISeCN generated
by the heterogeneous reaction of ICl gas with solid AgSeCN.
Furthermore, an X-ray diffraction analysis showed that the
solid residue in the reactor inlet tube is AgCl(s).15
(12) Brauer, G. Handbook of preparatiVe inorganic chemistry, 2nd ed.;
Academic Press: New York, 1963; p 290.
(13) Potts, A. W.; Price, W. C. J. Chem. Soc., Faraday Trans. 1971, 67,
1242.
(14) Zhao, H. Q.; Wang, D. X.; Xu, G. Z. J. Anal. Strum. 2002, 4, 23.
(15) Li, Y. M. Ph.D. Thesis, Anhui Institute of Optics and Fine Mechanics,
Chinese Academy of Science, Hefei, China, 2002.
Inorganic Chemistry, Vol. 42, No. 25, 2003 8447

Yimin et al.
Table 2. Observed and Calculated PES Vertical Ionization Energies (Iv
energies for INCO and ISCN are also listed in Table 2. From
Table 2, it can clearly be seen that the PES ionization
energies of INCO, ISCN, and ISeCN match very well with
the corresponding values calculated by the OVGF method.
This demonstrates that pure INCO and ISCN can be prepared
by the new reactions and that the PE spectrum given in
Figure 1a is that of ISeCN.
Further support for the PES assignment of ISeCN is
derived from the comparison with the PE spectra of ClSeCN
and BrSeCN,3 because they exhibit similar band structures
and a regular reduction of their ionization energies.
In summary, ICl is a good precursor to prepare pure INCO,
ISCN, and the hitherto unknown molecule ISeCN by the
heterogeneous reactions of ICl with AgNCO(s), AgSCN(s)
at room temperature, and prepared AgSeCN(s) at -9((1)
°C. The ionization energies of ISeCN, ISCN, and INCO are
assigned from the PES experiment and the OVGF calcula-
tions. The agreement between the PES experiments and the
OVGF calculations for INCO, ISCN, and ISeCN show that
the new reaction is a good preparative method for not only
pure INCO and pure ISCN, but also for the new compound
ISeCN. The discovery of this new reaction can promote the
investigations of these compounds and also might be
extended to the preparation of similar compounds.
in eV) and Ionization Energies (Ev in eV) for ISeCN, ISCN, and INCOa
IV (eV) this work Ev(eV) by OVGF
ISeCN
MO
character reference
9.58
10.80
11.27
12.36
12.62
12.85
13.80
15.44
9.739
10.909
11.593
12.379
13.577
13.602
14.043
16.519
14a′′(50) πI-Se
36a′(49) nI
13a′′(48) πI-Se
35a′(47)
πI-Se πC-N
34a′(46) nI σSe-C
12a′′(45) πSe-C-N
33a′(44) πI-Se-C-N
32a′(43) σI-Se
ISCN
9.74
11.10
11.34
12.55
13.36
15.26
9.907
11.024
11.785
12.396
13.736
14.069
14.523
17.044
11a′′(41) πI-S
30a′(40) nI
10a′′(39) πI-S
29a′(38) σI-S
9a′′(37)
9.75b
11.48b
11.86b
11.98b
12.79b
nI πS-C-N
28a′(36) σS-C
27a′(35) πS-C-N
26a′(34) nS nI σS-C
INCO
10a"(37) nI πN-C
27a′(36) nI
9.87
10.57
12.17
12.55
15.68
16.41
17.63
10.113
10.380
12.691
12.823
16.540
16.663
16.682
9.89 c
10.58c
12.16c
12.53c
15.60c
16.39c
17.55c
9a′′(35)
σI-N
26a′(34) π I-N
25a′(33) nI σI-N
8a′′(32)
πN-C-O
24a′(31) πN-C-O
a The geometries were optimized at the B3LYP/6-311++G (2df,pd) level,
and the calculation of OVGF method was done with a 6-311++G (2df,pd)
basis set. b Reference 4. c Reference 1.
Acknowledgment. This project was supported by the
National Natural Science Foundation of China (Contracts
29973051 and 20073052) and the Basic Bureau of Chinese
Academy of Sciences (Contract KJCXZ-H2-01). L.Y., Q.Z.
and S.Q. thank the Chinese Academy of Sciences for a
scholarship during the period of this work.
The assignment of the observed PE spectrum of the
unstable species ISeCN is supported by the OVGF calcula-
tions. Table 2 gives the PES vertical ionization energies (Iv
in eV) and the ionization energies (Ev in eV) calculated by
the OVGF method for the ISeCN molecule. For comparison,
the PES experimental and the OVGF calculated ionization
IC030158V
8448 Inorganic Chemistry, Vol. 42, No. 25, 2003