The [ICNI]+ cation: a combined experimental and theoretical
study. Reaction of [ICNI]+[AsF6]-
with CsN3
Abstract
(Iodocyano)iodine hexafluoroarsenate,
[ICNI]
+
[AsF
6
]
-
, containing the
linear 22-valence-electron [ICNI]
+
cation was synthesized
either by the reaction of iodine cyanide with
[I
3
]
+
[AsF
6
]
-
or
directly from ICN, I
2
and AsF
5
and characterized
by chemical analysis, IR, Raman and
19
F NMR data. A combined
vibrational (IR, Raman) and theoretical study revealed the
[ICNI]
+
cation to be linear. The preference of the linear
over the bent structure can easily be understood in terms of
hyperconjugative interactions in the cationic species [natural bond
order (NBO) analysis]. The molecular structure of the [ICNI]
+
cation was computed semiempirically (Austin Model 1, AM1;
reparameterization of AM1, PM3) and ab initio at the
Hartree–Fock (HF/6-31G*) and correlated RMP2 (RMP, restricted
Møller–Plesset) and RMP4(SDQ) levels of theory using
quasi-relativistic pseudo-potentials (LANL2DZ) for the iodine atoms. The
computed structural parameters at the highest level applied are:
C
∞v
symmetry, RMP4(SDQ),
d(I–C) = 2.001,
d(C![[triple bond, length as m-dash]](https://www.rsc.org/images/entities/char_e002.gif)
N) = 1.167,
d(N–I) = 2.021 Å. The
N–I bond dissociation enthalpy for [ICN–I]
+
was
calculated ab initio at the electron-correlated RMP2 level of
theory as 207.4 kJ mol
-1
. The metathetical reaction
of [ICNI]
+
[AsF
6
]
-
with
CsN
3
in SO
2
ClF afforded IN
3
,
Cs
+
[AsF
6
]
-
and ICN.
N) = 1.167,
d(N–I) = 2.021 Å. The
N–I bond dissociation enthalpy for [ICN–I]
+
was
calculated ab initio at the electron-correlated RMP2 level of
theory as 207.4 kJ mol
-1
. The metathetical reaction
of [ICNI]
+
[AsF
6
]
-
with
CsN
3
in SO
2
ClF afforded IN
3
,
Cs
+
[AsF
6
]
-
and ICN.
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