The volume-based thermodynamics (VBT) and attempted preparation of an isomeric salt, nitryl chlorate: [NO2][ClO3]

Article abstract of DOI:10.1002/zaac.200500518

Nitrosyl perchlorate, [NO][ClO₄], is a known and stable salt. In this contribution we describe the attempt to synthesize the isomeric compound nitryl chlorate, [NO₂][ClO₃]. The results are discussed on the basis of volume-based thermodynamics (VBT).

Full text of DOI:10.1002/zaac.200500518

DOI: 10.1002/zaac.200500518
The Volume-Based Thermodynamics (VBT) and Attempted Preparation of an
Isomeric Salt, Nitryl Chlorate: [NO2][ClO3]
Kuldip K. Bhasina, Margaret-Jane Crawfordb, H. Donald Brooke Jenkins*,c, Thomas M. Klapötke*,b, and
Joel F. Liebmand
a Chandigarh Ϫ 160 014 / India, Panjyb University, Department of Chemistry and Centre of Advanced Studies in Chemistry
b Munich / Germany, Ludwig-Maximilians Universität, Department of Chemistry and Biochemistry
c Coventry, West Midlands / U.K., University of Warwick, Department of Chemistry
d Baltimore, MD /USA,University of Maryland, Department of Chemistry
Received December 6th, 2005.
Abstract. Nitrosyl perchlorate, [NO][ClO4], is a known and stable
salt. In this contribution we describe the attempt to synthesize the
isomeric compound nitryl chlorate, [NO2][ClO3]. The results are
discussed on the basis of volume-based thermodynamics (VBT).
Keywords: Isomeric salts; Nitrosyl perchlorate; Nitryl chlorate;
Volume based thermodynamics
Silver Chlorate Reaction with Nitryl Hexafluoro-
antimonate
Reaction Chemistry
[NO2][SbF6] ϩ H2O
HNO3 ϩ Ag[ClO3]
HNO2 ϩ Ag[ClO3]
HNO
Ǟ
Ǟ
Ǟ
Ǟ
Ǟ
HNO3 ϩ “HSbF6”
Ag[ClO4] ϩ HNO2
Ag[ClO4] ϩ HNO
1/2 H2N2O2
(3a)
(3b)
(3b)
(3d)
(3e)
1
1/2 H2N2O2
1/2 H2O ϩ /2 N2O
Since nitrosyl perchlorate, [NO][ClO4], is a known and
stable salt, we attempted the preparation of the isomeric
compound nitryl chlorate, [NO2][ClO3].Silver chlorate (Ald-
rich, analytical grade), Ag[ClO3] was reacted with nitryl
hexafluoroantimonate (prepared at LMU), [NO2][SbF6] in
nitromethane (Aldrich, analytical grade) at room tempera-
ture in order to prepare [NO2][ClO3] (eq.(1)).
1
2 Ag[ClO3] ϩ [NO2][SbF6] ϩ /2 H2O
1
Ǟ 2 Ag[ClO4] ϩ /2 N2O ϩ “HSbF6” (3)
Scheme 1 Possible reaction mechanism for the reaction between
Ag[ClO3] and [NO2][SbF6] in “wet” nitromethane.
Ag[ClO3](s) ϩ [NO2][SbF6] (s) Ǟ Ag[SbF6] (s) ϩ [NO2][ClO3] (s)
Thermodynamics of reactions (1) and (2) using the
VBT approach
(1)
Although silver hexafluoroantimonate was identified as
one of the reaction products (Raman, 19F NMR), no
[NO2][ClO3] could be detected.In addition, silver perchlor-
ate (Raman), nitrous oxide (N2O) (mass spectrometry) and
nitric acid (14N NMR) were unambiguously identified as
further reaction products. The formation of HNO3 as a side
product was possibly caused by the presence of traces of
water in the nitromethane solvent. The reaction actually ob-
served is shown in eq. (2).
If the metathetical reaction (1) is made part of a Born Fa-
jans Haber cycle by incorporating lattice potential energies
for reactants and products, the gaseous ions produced in
the lattice energy steps are identical and the loop is
closed. Accordingly:
∆H(1) ϭ UPOT(Ag[ClO3]) ϩ UPOT([NO2][SbF6])
Ϫ UPOT(Ag[SbF6]) Ϫ UPOT([NO2][ClO3]) (4)
We can estimate ∆H(1) for reaction (1) by assigning
these lattice energy terms1) (table 1) and adopting the vol-
ume-based thermodynamics (VBT) approach [1].
1
2 Ag[ClO3](s) ϩ [NO2][SbF6](s) ϩ /2 H2O(l)
1
Ǟ Ag[SbF6](s) ϩ Ag[ClO4](s) ϩ HClO4(l) ϩ /2 N2O(g) (2)
A possible mechanism to explain the products of eq. (2)
is given in scheme 1.
giving: ∆H(1) ϭ ϩ17 ( 25) kJ molϪ1
(5)
1) Using the equation: UPOT ϭ 2I (α VϪ1/3 ϩ β) where α ϭ 117.3 kJ
molϪ1 nm3, β ϭ 51.9 kJ molϪ1 we can evaluate lattice energy using
either volumes from crystal structure data or estimated using from
our database [1b] of ion volumes. If the crystal structure data is
available this is chosen. Table 1 gives details of the lattice energy
calculations.
* Prof. Dr. T. M. Klapötke
Department Chemie und Biochemie der Universität
Butenandtstr. 5Ϫ13
D-81377 München
E-mail: tmk@cup.uni-muenchen.de
Z. Anorg. Allg. Chem. 2006, 632, 897Ϫ900
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
897

K. K. Bhasin, M.-J. Crawford, H. D. B. Jenkins, T. M. Klapötke, J. F. Liebman
Table 1 Formula Unit Volumes, Vm /nm3, Lattice Potential Energy, UPOT/kJ molϪ1 andStandard Entropy, S0298/J KϪ1 molϪ1
.
Ag[ClO3]
[NO2][SbF6]
Ag[SbF6]
0.1195 [5]
[NO2][ClO3]
Ag[ClO4]
[NO][ClO4]
a)
d)
d)
a, h)
V(salt) / nm3
0.0711
0.143 0.014
0.143 0.014
0.0832
0.0861
0.0924 [6]
0.092 0.006
b)
b)
a, h)
b)
0.079 0.006
0.1444
b)
0.0880 ϩ 0.013
641[1]
UPOT(salt) / kJ molϪ1
ρ (salt) / g cmϪ3
670 [1]
651 14 [1]
550 10 [1]
511[1]
580 [1]
618 18 [1]
623 [1]
624 18 [1]
635[1]1
631 23 [1]
2.806 [2]
4.37 [2]
4.43 [3]
191.319
M (salt)
207.319
UPOT(salt) / kJ molϪ1
666
668
576
c)
c)
c)
Average UPOT(salt) / kJ molϪ1
664 ( 6)
152 [3]
551 10
211
580
176
618 18
144
621 23
162 [3]
623
140
S0 / J KϪ1 molϪ1
e)
e)
e)
e)
298
a) Crystal structure data (ref. [2]). b) Ion additivity (see footnote 1)). c) Calculated using the density based equation (footnote 2), [4]). d) Estima-
ted by taking the alkali metal (M) salts, V(MSbF6) from ref. [5] and estimating V([NO2][SbF6]) from V(MSbF6) Ϫ V(Mϩ) ϩ V(NO2
using V(NO2ϩ) ϭ 0.022 0.011 nm3. e) Estimated from equation: S0298/JKϪ1 molϪ1 ϭ kVm ϩ c, k ϭ 1360 JKϪ1 molϪ1 nm3.
)
ϩ
The large error stems from the uncertainty in the volume
data, which itself arises because of the nature of the salts
themselves and the experimental difficulties in their hand-
ling. The corresponding entropy change for reaction (1),
∆S(1) is given by the difference in their standard entropies:
Using the lattice energy data in table 1 and thermo-
chemical data [9] and values of ∆fH0(ClO3Ϫ, g)3) and
∆fH0(ClO4Ϫ, g)4) from reference [9] we estimate that:
∆H(2) ഠ ϩ49 ( 82) kJ molϪ1
(10)
∆S(1) ϭ S0 (Ag[SbF6]) ϩ S0 ([NO2][ClO3])
298
298
3) ∆fH0(ClO3Ϫg) Ϫ this value is estmated using a thermochemical
cycle involving latticeenergies of alkali metal chlorates, MClO3
(estimated from crystal structure volumes and using the volume-
based equation (1), their standard enthalpies of formation and the
enthalpy of formation of the gaseous alkali metal ion, Mϩ.
Ϫ S0 (Ag[ClO3]) Ϫ S0 ([NO2][SbF6]) (6)
298
298
Invoking our isomegethic rule [7] and the relationship be-
tween entropy and volume2) we conclude that:
∆S(1) ഠ 0 J KϪ1 molϪ1
(7)
∆fH0(ClO3Ϫ, g) ϭ UPOT(MClO3)ϩ /2 RT ϩ ∆fH0(MClO3, s)
1
Ϫ ∆fH0(Mϩ, g)
and therefore, that
∆G(1) ഠ ∆H(1) ഠ ϩ17 ( 25) kJ molϪ1
(8)
1
Salt
UPOT(MClO3)
/
RT
∆fH0(MClO3Ϫ, s) ∆fH0(Mϩ, g) ∆fH0(ClO3Ϫ, g)
2
kJ molϪ1
kJ molϪ1 kJ molϪ1
kJ molϪ1
kJ molϪ1
The borderline nature of this result (with its considerable
uncertainty) spans into the thermodynamically favourable
regime and makes an attempt at this preparation of the tar-
get nitryl chlorate, [NO2][ClO3] entirely warranted. The fact
that no [NO2][ClO3] could be detected accords though with
the prediction made by VBT in (8) however.
∆H(2) can be estimated for reaction (2) by incorporating
the reaction into a thermochemical cycle involving the lat-
tice energies of the salts Ag[ClO3], [NO2][SbF6], Ag[SbF6]
and Ag[ClO4] and the standard states of the elements.
∆H(2) can be written:
NaClO3 655
KClO3 642
RbClO3 634
CsClO3 624
1.2
1.2
1.2
1.2
Ϫ365.8
Ϫ397.7
Ϫ402.9
Ϫ411.7
609.0
514.3
490.0
458.0
Ϫ319
Ϫ269
Ϫ258
Ϫ245
The value of ∆fH0(ClO3Ϫ, g) / kJ molϪ1 is far from consistent
averaging to Ϫ 275 ( 44) and differs from the value assigned by
Marcus [10] (Ϫ 200 kJ molϪ1) but is similar to that given by the
WebBook [11] (Ϫ 285 ( 26) kJ molϪ1). If this average value is
used then ∆H(2) ഠ Ϫ 236 ( 67) kJ molϪ1. These salts are difficult
to handle experimentally and have always provided a range of
values for their (constant) properties [12].
4) ∆fH0(ClO4Ϫ, g) Ϫ this value is estmated using a thermochemical
cycle involving latticeenergies of alkali metal perchlorates, MClO4
(estimated from crystal structure volumes and using the volume-
based equation (1), their standard enthalpies of formation and the
enthalpy of formation of the gaseous alkali metal ion, Mϩ.
∆H(2) ϭ 2 UPOT(Ag[ClO3]) ϩ UPOT([NO2][SbF6])
Ϫ UPOT(Ag[SbF6]) Ϫ UPOT(Ag[ClO4]) ϩ 2 RT
1
Ϫ 2 ∆fH0(ClO3Ϫ, g) Ϫ ∆fH0(NO2ϩ, g) Ϫ /2 ∆fH0(H2O, l)
1
ϩ ∆fH0(ClO4Ϫ, g) ϩ ∆fH0(HClO4, l) ϩ /2 ∆fH0(N2O, g) (9)
∆fH0(ClO4Ϫ, g) ϭ UPOT(MClO3)ϩ /2 RT ϩ ∆fH0(MClO4, s)
1
Ϫ ∆fH0(Mϩ, g)
1
Salt
UPOT(MClO4)
/
RT
∆fH0(MClO4Ϫ, s) ∆fH0(Mϩ, g) ∆fH0(ClO4Ϫ, g)
2
2) Recent work has shown a direct proportionality [8a] between
kJ molϪ1
kJ molϪ1 kJ molϪ1
kJ molϪ1
kJ molϪ1
standard entropy, S0 and molecular (formula unit) volume, Vm
298
of the form: S0 ϭ k Vm ϩ c, where k ϭ 1360 JKϪ1 molϪ1 nm3
NaClO4 635
KclO4 624
RbClO4 616
CsClO4 608
1.2
1.2
1.2
1.2
Ϫ383.3
Ϫ432.8
Ϫ437.2
Ϫ443.1
609.0
514.3
490.0
458.0
Ϫ356
Ϫ382
Ϫ310
Ϫ292
298
and c ϭ 15 J KϪ1 molϪ1. A similar form is valid for organic materi-
als [8b]. Thus for any metathetical reaction such as (1) since the
ions are identical on both sides, the overall volume change for the
reaction, ∆V(1) ϭ 0 nm3 and hence correspondingly using the
equation above, ∆S(1) ഠ 0 JKϪ1molϪ1 and hence for reaction (1):
∆H(1) ഠ ∆G(1)
The value of ∆fH0(ClO4Ϫ, g) / kJ molϪ1 is far from consistent
averaging to Ϫ 335 ( 47). This value is close to that assigned by
Marcus [10] and Jenkins and Pratt [13] (Ϫ344 kJ molϪ1).
898
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Z. Anorg. Allg. Chem. 2006, 897Ϫ900

Nitryl Chlorate: [NO2][ClO3]
In the absence of entries for S0298(HClO4, l) in standard
thermochemical tables (paper and electronic) we estimate a
value (see footnote5)):
Ag[ClO3] ϩ [NO2][SbF6]
[NO2][ClO3]
[NO][ClO4] ϩ Ag[ClO3]
[NO][ClO3]
NO2 ϩ ClO2
O2NOClO
NO3 ϩ ClO
O2NOOCl
O2NOO
NO2 ϩ Cl
Ǟ
Ǟ
Ǟ
Ǟ
Ǟ
Ǟ
Ǟ
Ǟ
Ǟ
Ǟ
Ag[SbF6] ϩ [NO2][ClO3] (14a)
[NO][ClO4]
(14b)
(14c)
(14d)
(14e)
(14f)
(14g)
(14h)
(14i)
(14j)
Ag[ClO4] ϩ [NO][ClO3]
NO2ϩClO2
O2NOClO
∆S(2) ഠ S0298(Ag[SbF6], s) ϩ S0298(Ag[ClO4], s)
1
ϩ S0298(HClO4, l) ϩ /2 S0298(N2O, g) Ϫ 2 S0298(Ag[ClO3], s)
NO3 ϩ ClO
O2NOOCl
1
Ϫ S0298([NO2][SbF6], s) Ϫ /2 S0298(H2O, l) (11)
O2 NOO ϩ Cl
NO2 ϩ O2
and accordingly estimate6) ∆S(2) to be:
NO2Cl
∆S(2) ഠ ϩ 68 J KϪ1 molϪ1
leading to:
(12)
2 Ag[ClO3] (s) ϩ [NO2][SbF6] (s)
Ǟ Ag[ClO4] (s) ϩ Ag[SbF6] (s) ϩ NO2Cl (g) ϩ O2 (g) (14)
Scheme 2 Possible reaction mechanism for the reaction between
Ag[ClO3] and [NO2][SbF6].
∆G(2) ഠ ϩ 29 ( 82) kJ molϪ1
(13)
This result suggests that reaction (2) may be similarly
thermodynamically borderline.
cycle involving the lattice energies of the salts Ag[ClO3],
[NO2][SbF6], Ag[SbF6] and Ag[ClO4] and the standard
states of the elements. ∆H(14) can be written:
Reaction Chemistry
In another reaction carried out under argon and using thor-
oughly dried (over P4O10) nitromethane, again silver chlor-
ate (Raman), nitryl chloride, NO2Cl (mass spectrometry)
and traces of dioxygen (mass spectrometry) but no [NO2][-
ClO3] were observed as the reaction products (eq. (3)).
∆H(14) ϭ 2 UPOT(Ag[ClO3]) ϩ UPOT([NO2][SbF6])
Ϫ UPOT(Ag[SbF6]) Ϫ UPOT(Ag[ClO4]) ϩ 2 RT Ϫ 2 ∆fH0(ClO3Ϫ, g)
Ϫ ∆fH0(NO2ϩ, g) ϩ ∆fH0(ClO4Ϫ, g) ϩ ϩ ∆fH0(NO2Cl , g)
(15)
whereupon we estimate that:
∆H(14) ϭϪ 46 ( 149) kJ molϪ1
(16)
2 Ag[ClO3](s) ϩ [NO2][SbF6] (s)
Ǟ Ag[ClO4](s) ϩ Ag[SbF6](s) ϩ NO2Cl (g) ϩ O2 (g) (14)
the corresponding entropy change, ∆S(14) can be written:
This finding (eq. (3)) may well indicate that initially
[NO2][ClO3] was formed in a metathetical reaction but de-
composed according to scheme 2.
∆S(14) ഠ S0298(Ag[SbF6], s) ϩ S0298(Ag[ClO4], s)
ϩ S0298(NOCl2, g) Ϫ 2 S0298(Ag[ClO3], s)
Ϫ S0298([NO2][SbF6], s) ഠ ϩ 300 J KϪ1 molϪ1
(17)
Thermodynamics of reaction (14)
leading to:
If the reaction (14) is made part of a Born Fajans Haber
cycle by incorporating the reaction into a thermochemical
∆G(14) ഠ Ϫ160 ( 82) kJ molϪ1
(18)
This latter result tends to confirm the qualitative expla-
nation given above that [NO2][ClO3] is formed but then de-
composes. Although the transformation of [NO2][ClO3]
into [NO][ClO4]
156.9 J KϪ1 molϪ1; S0298(NaHSO4, s) ϭ 113 J KϪ1 molϪ1
[NO2][ClO3] Ǟ [NO][ClO4]
(19)
(for which ∆H(19) ϭ UPOT([NO2][ClO3]) Ϫ UPOT([NO]-
[ClO4]) ഠ Ϫ5 kJ molϪ1; ∆S(19) ϭ S0298([NO][ClO4]) Ϫ
ϩ
S0298([NO2][ClO3]) ഠ k (V{NOϩ) ϩ V(ClO4Ϫ) Ϫ V(NO2
)
Ϫ V(ClO4Ϫ)] ഠ Ϫ4 J KϪ1 molϪ1 and hence ∆G(19) ഠ
Ϫ4 kJ molϪ1) is only on the borderline of thermodynamic
favourability it is likely that this transformation is driven by
the overall value of ∆G (15).
s) are estimated using the corresponding volumes, Vm(Ag[SbF6],
s) and Vm([NO2][SbF6], s)from table 1 with the Jenkins-Glasser ent-
ropy Ϫ volume correlation [8] S ϭ kV ϩ c, where k ϭ 1360 J
Reaction Chemistry
K
Ϫ1molϪ1 nmϪ3 and c ϭ 15 J KϪ1 molϪ1. Thus S0298(Ag[SbF6],
s) ഠ 1360(0.1195) ϩ 15 ϭ 176 J KϪ1 molϪ1 and S0298([NO2][SbF6],
s) ഠ 1360(0.1444) ϩ 15 ϭ 211 J KϪ1 molϪ1
A third attempt was carried out repeating the reaction at
Ϫ25 °C, however, qualitatively the same products were ob-
.
Z. Anorg. Allg. Chem. 2006, 897Ϫ900
 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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899

K. K. Bhasin, M.-J. Crawford, H. D. B. Jenkins, T. M. Klapötke, J. F. Liebman
of Commerce, N.B.S. and Joint Committee on Powder Diffrac-
tion Studies, 1973.
[3] Handbook of Chemistry Physics, D. R. Lide, Ed. C. R. C.
Press, 83rd edn., Boca Raton, FL., 2002Ϫ2003.
[4] H. D. B. Jenkins, D. Tudela, L. Glasser, Inorg. Chem. 2002,
41, 2364.
[5] H. D. B. Jenkins, H. K. Roobottom, J. Passmore, Inorg. Chem.
2003, 42, 2886.
[6] (a) L. J. Klinkenberg, Rec. Trav. Chim, Pays-Bas 1937, 56, 749.
(b) H. J. Berthold, H.-G. Bäthge, B. G. Hölscher, H.-J. Kienert,
W. Ludwig, J. M. Molepo, R. Wartchow, Ber.Bunsen-Gesell-
schaft 1983, 87, 245.
served as were identified from the room temperature reac-
tion (eq. (3)).Since the melting point of nitromethane
(Ϫ29 °C) does not permit a lower reaction temperature, the
reaction was carried out in thoroughly dried acetonitrile,
however [NO2][SbF6] was found, in this instance, to react
with the solvent.In neat Ag[ClO3] and [NO2][SbF6] (when
mixed as solids in the dry box) no reaction was observed at
room temperature.An attempted reaction in liquid SO2 at
room temperature did not result in a chemical reaction,
probably due to the almost insolubility of the silver salt in
this solvent.
[7] H. D. B. Jenkins, L. Glasser, T. M. Klapötke, M.-J. Crawford,
J. Lee, G. J. Schrobilgen, J. F. Liebman, L. S. Sunderlin, Inorg.
Chem. 2004, 43, 6238.
[8] (a) H. D. B. Jenkins, L. Glasser, Inorg. Chem. 2003, 42, 8702.
(b) L. Glasser, H. D. B. Jenkins, Thermochim. Acta 2004,
414, 125.
Acknowledgement. Professor K. K. Bhasin is indebted to and thanks
the Deutsche Akademische Austauschdienst (DAAD) for a re-
search scholarship to stay at LMU in Munich in 2003. Professor
J. F. Liebman thanks the LMU and his hosts for the recent invi-
tation to visit LMU.
[9] D. D. Wagman, W. H. Evans, V. B. Parker, R. H. Schumm, I.
Harlow, S. M. Bailey, K. L. Churney, R. L. Nutall, J. Phys.
Chem. Ref. Data. 1982, 11, Supplement No 2.
[10] Y. Marcus, Ion Properties, Marcel Dekker, N.Y. 1997.
[11] NIST Chemistry WebBook, NIST Standard Reference Data-
base Number 69, Eds. P. J. Linstrom and W. G. Mallard, June
2005, National Institute of Standards and Technology,
Gaithersburg MD, 20899 (http://webbook.nist.gov).
[12] P. Herzig, H. D. B. Jenkins, K. F. Pratt, J. Phys. Chem. Solids
1979, 40, 85.
References
[1] (a) H. D. B. Jenkins, L. Glasser, Chem. Rev. 2005, 34, 866 and
associated supplementary material. (b) H. D. B. Jenkins, H.
K. Roobottom, J. Passmore, L. Glasser, Inorg. Chem. 1999, 38,
3609. (c) S. Brownridge, I. Krossing, J. Passmore, H. D. B.
Jenkins, H. K. Roobottom, Coord. Chem. Rev. 2000, 197, 397.
(d) H. D. B. Jenkins, J. F. Liebman, Inorg. Chem>. 2005, 44,
6359.
[2] Crystal Structure Determinative Tables. Inorganic Compounds,
[13] H. D. B. Jenkins, K. F. Pratt, J. Chem. Soc., Faraday Trans. II
1978, 74, 968.
3rd Ed. Vol. 3. J. D. H. Donnay, H. Ondik, U S Department
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