The reaction of Li[Al(OR)4] R = OC(CF3) 2Ph, OC(CF3)3 with NO/NO2 giving NO[Al(OR)4], Li[NO3] and N2O. The synthesis of NO[Al(OR)4] from Li[Al(OR)4] and NO[SbF6] in sulfur dioxide solution

Article abstract of DOI:10.1039/b405715e

NO[Al(OC(CF₃)₂Ph)₄] 1 and NO[Al(OC(CF ₃)₃)₄] 2 were obtained by the metathesis reaction of NO[SbF₆] and the corresponding Li[Al(OR)₄] salts in liquid sulfur dioxide solution in ca 40% (1) and 85% (2) isolated yield. 1 and 2, as well as Li[NO₃] and N₂O, were also given by the reaction of an excess of mixture of (90 mol%) NO, (10 mol%) NO ₂ with Li[Al(OR)₄] followed by extraction with SO ₂. The unfavourable disproportionation reaction of 2NO₂(g) to [NO]³(g) and [NO₃]^-(g) [ΔH° = +616.2 kJ mol^-1] is more than compensated by the disproportionation energy of 3NO(g) to N₂O(g) and NO₂(g) [ΔH° = -155.4 kJ mol^-1] and the lattice energy of Li[NO₃] (s) [U_POT = 862 kJ mol^-1]. Evidence is presented that the reaction proceeds via a complex of [Li]⁺ with NO, NO₂ (or their dimers) and N₂O. NO₂ and Li[Al(OC(CF ₃)₃)₄] gave {NO₃(NO) ₃}[Al(OC(CF₃)₃)₄]₂, NO[Al(OC(CF₃)₃)₄] and (NO₂) [Al(OC(CF₃)₃)₄] products. The aluminium complex (Li[AlF(OC(CF₃)₂Ph)₃]}₂ 3 was prepared by the thermal decomposition of Li[Al(OC(CF₃) ₂Ph)₄], Compounds 1 and 3 were characterized by single crystal X-ray structural analyses, 1-3 by elemental analyses, NMR, IR, Raman and mass spectra. Solid 1 contains [Al(OC(CF₃)₂Ph) ₄]^- and [NO]⁺ weakly linked via donor acceptor interactions, while in the SO₂ solution there is an equilibrium between the associated [NO]^-[Al(OC(CF₃) ₂Ph)₄]^- and separated solvated ions. Solid 2 contains essentially ionic [NO]⁺ and [Al(OC(CF₃) ₃)₄]^-. Complex 3 consists of two {Li[AlF(OC(CF₃)₂Ph)₃]} units linked via fluorine lithium contacts. Compound 1 is unstable in the SO₂ solution and decomposes to yield [AlF(OC(CF₃)₂Ph) ₃]^-, [(PhC(CF₃)₂O) ₃Al(μ-F)Al(OC(CF₃)₂Ph)₃] ^- anions as well as (NO)C₆H₄C(CF ₃)₂OH, while compound 2 is stable in liquid SO ₂. The (NO^-) in 1 and [NO]⁺(toluene) [SbCl₆] are similar, implying similar basicities of [Al(OC(CF ₃)₂Ph)₄]^- and toluene.

Full text of DOI:10.1039/b405715e

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F U L L P A P E R
The reaction of Li[Al(OR)4] R = OC(CF3)2Ph, OC(CF3)3 with
NO/NO2 giving NO[Al(OR)4], Li[NO3] and N2O. The synthesis of
NO[Al(OR)4] from Li[Al(OR)4] and NO[SbF6] in sulfur dioxide
solution†
Andreas Decken,a H. Donald Brooke Jenkins,b Grigori B. Nikiforova and Jack Passmore*a
a
Chemistry Department, University of New Brunswick, Fredericton, N.B. E3B 6E2, Canada.
E-mail: passmore@unb.ca; Fax: +1 (506) 453 48 21; Tel: +1 (506) 453 48 21
Department of Chemistry, University of Warwick, Coventry, West Midlands, UK CV4 7AL
b
Received 16th April 2004, Accepted 21st June 2004
First published as an Advance Article on the web 23rd July 2004
NO[Al(OC(CF3)2Ph)4] 1 and NO[Al(OC(CF3)3)4] 2 were obtained by the metathesis reaction of NO[SbF6] and the
corresponding Li[Al(OR)4] salts in liquid sulfur dioxide solution in ca 40% (1) and 85% (2) isolated yield. 1 and 2, as
well as Li[NO3] and N2O, were also given by the reaction of an excess of mixture of (90 mol%) NO, (10 mol%) NO2
with Li[Al(OR)4] followed by extraction with SO2. The unfavourable disproportionation reaction of 2NO2(g) to [NO]+(g)
and [NO3]−(g) [H° = +616.2 kJ mol−1] is more than compensated by the disproportionation energy of 3NO(g) to N2O(g)
and NO2(g) [H° = −155.4 kJ mol−1] and the lattice energy of Li[NO3] (s) [UPOT = 862 kJ mol−1]. Evidence is presented
that the reaction proceeds via a complex of [Li]+ with NO, NO2 (or their dimers) and N2O. NO2 and Li[Al(OC(CF3)3)4]
gave {NO3(NO)3}[Al(OC(CF3)3)4]2, NO[Al(OC(CF3)3)4] and (NO2)[Al(OC(CF3)3)4] products. The aluminium complex
{Li[AlF(OC(CF3)2Ph)3]}2 3 was prepared by the thermal decomposition of Li[Al(OC(CF3)2Ph)4]. Compounds 1 and 3
were characterized by single crystal X-ray structural analyses, 1–3 by elemental analyses, NMR, IR, Raman and mass
spectra. Solid 1 contains [Al(OC(CF3)2Ph)4]− and [NO]+ weakly linked via donor acceptor interactions, while in the SO2
solution there is an equilibrium between the associated [NO]+[Al(OC(CF3)2Ph)4]− and separated solvated ions. Solid 2
contains essentially ionic [NO]+ and [Al(OC(CF3)3)4]−. Complex 3 consists of two {Li[AlF(OC(CF3)2Ph)3]} units linked
via fluorine lithium contacts. Compound 1 is unstable in the SO2 solution and decomposes to yield [AlF(OC(CF3)2Ph)3]−,
[(PhC(CF3)2O)3Al(-F)Al(OC(CF3)2Ph)3]− anions as well as (NO)C6H4C(CF3)2OH, while compound 2 is stable in liquid
SO2. The (NO+) in 1 and [NO]+(toluene)[SbCl6] are similar, implying similar basicities of [Al(OC(CF3)2Ph)4]− and toluene.
the structural determination of these substances. The nitrosonium
Introduction
cation [NO]+ is an electrophile12 and an effective oxidant in electron
Weakly coordinating anions (WCA) have been of considerable
transfer reactions,13 and thus the NO[Al(OR)4] salts are potential
interest in the last few decades.1 They have been used to enhance
reagents for the preparation of homopolyatomic cations and related
the catalytic activity of metal cations,2 to stabilize strongly acidic
species using SO2 as a solvent.
cations including homopolyatomic cations of the electronegative
1a,3
elements
and cations containing very weak donor bases coor-
Results and discussion
dinated to a Lewis acid center.4 The WCA have potential industrial
applications in the areas of electrochemistry,1e,5 as electrolytes for
lithium ion batteries,6 ionic liquids6a,7 and extraction of Ln(III) ions.8
A family of (polyfluoroalkoxy)aluminate WCA anions [Al(OR)4]−
have been recently developed.1d,e,2d,9,10 Salts of cations stabilized
by [Al(OR)4]− are commonly prepared using the metathesis reac-
tion employing the silver salts Ag[Al(OR)4]9 in the non aqueous
solvents CH2Cl2, CS2 and toluene. However, the [Ag]+ salts always
coordinate solvent molecules that can only be removed in a high
vacuum using non trivial and expensive procedures. As far as we
are aware there are only two previous reports of Li[Al(OR)4] used
as a precursor, i.e. to Cs[Al(OC(CF3)3)4], Tl[Al(O(CH)(CF3)2)4] and
{Tl3F2Al(O(CH)(CF3)2)3} [Al(O(CH)(CF3)2)4]6a,11 by reaction with
CsF and TlF in CH2Cl2.
Preparation and characterization of NO[Al(OC(CF3)2Ph)4] (1)
and NO[Al(OC(CF3)3)4] (2)
The metathesis reaction between the Li[Al(OR)4] and NO[SbF6]
in SO2 followed by removal of the insoluble Li[SbF6] afforded
NO[Al(OC(CF3)2Ph)4] 1 with an isolated yield of about 40% and
NO[Al(OC(CF3)3)4] 2 (85%) according to eqn. (1). We propose
that during the time of initial reaction the product 1 decomposed
as shown in Scheme 3 below [S.I., section—stability of 1 in SO2
solution]. The estimated enthalpy of reaction shows that the reac-
tion is marginally exothermic.14a Since metathetical reactions have
an entropy change close to zero (S ≈ 0)14b and hence H ≈ G for
such reactions, the H values cited in footnote14a correspond to G
changes.
We describe below the facile synthesis of NO[Al(OR)4]
R = C(CF3)2Ph and C(CF3)3 salts, either by metathesis reaction of
Li[Al(OR)4] and NOSbF6 or by the interaction of Li[Al(OR)4] with a
mixtureofNOandNO2.Wealsoreporttheinvestigationofthestabil-
ity of the starting and obtained compounds in the liquid SO2 solvent
used in this work. The [Al(OC(CF3)3)4]− and [Al(OC(CF3)2Ph)4]− an-
ions chosen for this research have the lowest basicity of the known
(polyfluoroalkoxy)aluminate anions of the type [Al(OR)4]−6a and
they are expected to form the most stable compounds. In addition,
the presence of the phenyl group in [Al(OC(CF3)2Ph)4]− can aid
crystallisation of the substances with this anion, thus facilitating
(1)
Red crystals of 1 suitable for X-ray analysis were grown from
CH2Cl2 at −24 °C. The nitrosonium moiety in 1 is sandwiched
betweenthetwophenylrings Ph1 [C4–C9]andPh2[C22–C27]from
two different [Al(OC(CF3)2Ph)4]− anions (Fig. 1), forming chains of
(NO[Al(OR)4])x. [NO]+ is also coordinated to the aryl rings in the
bis-diarene complexes [Ar2NO][SbCl6], Ar2 = toluene,15 mesity-
lene,15 MEA (octamethyl-9,10-dihydro-9,10-ethanoanthracene),
† Electronic supplementary information (ESI) available: Figs. 1–20, Table
1 and discussion. See http://www.rsc.org/suppdata/dt/b4/b405715e/
2 4 9 6
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4

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The [NO]+ stretching frequency of 1 occurred in the Raman and
IR spectra at 2036 cm−1,18 close to corresponding values of (NO+)
in NO(toluene)[PF6] 2037 cm−113 and, at slightly lower wavenum-
bers than the (NO+) in the ionic NO[AsF6] at 2340 cm−119. This is
consistent with observed interaction of [NO]+ with the phenyl rings
of the [Al(OC(CF3)2Ph)4]− neighbouring anions. Kochi established
a linear correlation of the N–O stretching frequency in [NO]+ com-
plexes with the ionization potential of the arene donors in 1:1 com-
plexes.13 The [NO]+ phenyl interaction of one ring is significantly
stronger than with the second, therefore the [NO]+ stretch in 1 can be
fitted into Kochi’s relationship by treating 1 as a 1:1 complex. This
yields a basicity of [Al(OC(CF3)2Ph)4]− close to that of toluene.
The Raman spectrum of 2 has a peak at 2340 cm−1 assigned
to the [NO]+ cation implying a non interacting [NO]+ cation and
[Al(OC(CF3)3)4]− anion in 2 (See ESI†, Figs. 5 and 8). The position
of the [NO]+ absorption band in the Raman spectra of 2 is similar
to that of NO[HSO4] 2340 cm−1, NO[AsF6] 2340 cm−1, NO[SbF6]
2345 cm−1.19
Table 1 Selected bond lengths (Å) and angles (°) for 1 and 2
complex 1
N–O
1.080(2)
C(1)–O(1)–Al
C(10)–O(2)–Al
C(19)–O(3)–Al
C(28)–O(4)–Al
163.68(18)
166.82(19)
158.94(16)
156.33(16)
Al–O(2)
Al–O(1)
Al–O(4)
Al–O(3)
1.7011(17)
1.7054(16)
1.7099(17)
1.7111(16)
complex 2
Li–F(1a)
Li–F(1)
Li–O(1a)
Al–O(2)
Al–O(3)
Al–O(1)
Al–F(1)
1.827(5)
2.393(6)
2.023(6)
1.6938(19)
1.7075(19)
1.7625(19)
1.7139(17)
F(1)–Li–O(1a)
F(1)–Li–F(1a)
F(1a)–Li–O(1a)
Li–F(1)–Li(a)
O(3)–Al–O(1)
F(1)–Al–O(1)
O(3)–Al–F(1)
128.5(3)
84.1(2)
69.53(18)
95.9(2)
114.44(10)
93.71(9)
110.05(9)
a Symmetry transformations used to generate equivalent atoms in
One broad resonance close to 0 ppm in the area of non coordi-
nated [NO]+20 was detected in the 14N NMR spectrum of 1 at room
temperature. Lowering the temperature leads to the broadening of
the 14N NMR resonance of 1. A broad signal with the maximum
at 110 ppm and a shoulder at −100 ppm appeared at −70 °C. It is
concluded, that the resonances of coordinated [NO]+ cation in the
ion pairs (NO)+[Al(OC(CF3)2Ph)4]− and separated cation [NO]+
were detected at low temperature and line broadening arises due
to exchange. The shape of 14N resonance of 1 resembles that of the
(NO(toluene))+[SbF6] complex at the same temperature (See ESI†,
Fig. 2), which has a maximum at 40 ppm and a shoulder at −20 ppm
due to the [NO(toluene)]+ ion pair and the separated ion [NO]+, in
agreement with the previous UV-vis studies of the solution behav-
iour of the [NO(toluene)]+ complex.13
2: −x + 1, −y + 2, −z.
ST1 = 2,3-bis-pentamethylphenyl-bicyclo[2.2.2]oct-2-ene,16
ST4 = 1,2-bis-pentamethylphenyl-1,2-bis-diethylethene.16
The
nearest distances between the N and the two aromatic rings are
not equal d (N–Ph1) 2.3 Å and d (N–Ph2) 2.6 Å indicating greater
interaction with the Ph1 ring. In some known diarene complexes
the two distances are also non-equivalent d = 2.15 and 3.10 Å
in [MEA,NO]+, d = 2.24 and 2.70 Å in [ST1,NO]+, d = 2.15 and
2.90 Å in [ST4,NO]+16, sum of the van der Waals’ radii of nitrogen
and carbon 3.25 Å.17 The [NO]+ cation is tilted 41.4° towards Ph1.
The second closest Ph2 ring is almost parallel with the [NO]+ cation
with a angle of 2.1°.
The chemical shift of the 14N NMR resonance of 2 in SO2 solu-
tion was the same at r.t. and at −70 °C [ca. 0 ppm] and attributable
to solvated [NO]+.20
The 19F, 27Al NMR spectra of SO2 solutions of 1 and 2 showed
a single resonance of the [Al(OR)4]− at low temperature and at
r.t. (Table 2) due to a rapid exchange of all fluorine atoms in the
anions.
Interaction of Li[Al(OR)4] R = OC(CF3)3, OC(CF3)2Ph with a
mixture of NO and NO2
We have established, that reaction of Li[Al(OR)4] with a mixture
of NO and NO2 followed by extraction of the resulting product (A)
with liquid SO2 yields NO[Al(OR)4] 1 and 2 as shown in Scheme 1.
The presence of N2O reaction product was established by an in situ
NMR experiment.
Fig. 1 Molecular structure of NO[Al(OC(CF3)2Ph)4] 1 with selected
atoms numbered.
The shortest N–F(19) contact of 2.971(3) Å is comparable with
the sum of the corresponding van der Waals’ radii of 3.02 Å and
the shortest O–F(19) 2.694 Å, O–F(12) 2.703 Å, O–F(21) 2.813 Å
contacts are slightly less than the sum of the corresponding van der
Waals’ radii of 2.99 Å.
Scheme 1 Coefficients: x = 3, y = 1, z = 1, k = 1 (reaction (2), Table 2) or
x = 3/2, y = 3/2, z = 1/2, k = 1 (reaction (3), Table 2).
Elemental analysis confirms the anticipated composition as
NO[Al(OC(CF3)2Ph)4] 1, NO[Al(OC(CF3)3)4] 2 and shows that
compounds 1 and 2 are solvent free and contain no lithium. Solu-
tions of 1 and 2 are sensitive to moisture but, the solid 1, 2 does
not change appearance on storage in sealed ampoules at −24 °C for
several months. The solid 2 readily reacts with organic substances,
forming a red oil with toluene and a grey solid with Nujol and per-
fluoropolyalkyl ether (Fluorolube).
Compounds 1 and 2 do not give the molecular ions [M]+ in the
EI-MS spectrum. The heavier cations (m/z = 400–1000) detected
in the EI-MS of 1 contained no [NO]+ and are formed by abstrac-
tion of F, CF3, as well as Ph, and C(CF3)2Ph, OC(CF3)2Ph from
[Al(OC(CF3)2Ph)4]− for 1 and F, CF3, C(CF3)n n = 1–3 and OC(CF3)3
moieties from the [Al(OC(CF3)3)4]− for 2.
The yield of the reaction products depends on the relative con-
centrations of the NO and NO2. Addition of N2O3 (1NO:1NO2) to
Li[Al(OC(CF3)3)4] followed by SO2 extraction afforded a mixture
of the NO[Al(OC(CF3)3)4] and (NO2)[Al(OC(CF3)3)4]21 (FT Raman,
eqns. (3) and (6), Table 2). Li[Al(OC(CF3)3)4] and liquid NO2 yields
a mixture of NO[Al(OC(CF3)3)4]2, {NO3(NO)3}[Al(OC(CF3)3)4]2,22
(NO2)[Al(OC(CF3)3)4] as well as Li[NO3] (FT Raman, eqns. (4) and
(5), Table 2). Although the reaction of NO(g) and Li[Al(OR)4] as
shown in eqns. (7) and (8), Table 2 is thermodynamically favour-
able, no reaction was observed by interaction of pure NO and
Li[Al(OR)4] in SO2. However, a brown solid was given on addition
of NO and neat Li[Al(OR)4] at low temperatures which may be
(Li(NO)x)[Al(OR)4].
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4
2 4 9 7

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Table 2 Enthalpies of the solid reactions of Li[Al(OR)4] with nitrogen oxides
Reactiona
H/kJ mol−1
S/J K−1 mol−1
G/kJ mol−1
Li[Al(OR)4] (s) + 3NO(g) + NO2 (g) = NO[Al(OR)4] (s) + Li[NO3] (s) + N2O (g),
Li[Al(OR)4] (s) + 3/2N2O3 (l) = NO[Al(OR)4] (s) + Li[NO3] (s) + 1/2N2O (g),
Li[Al(OR)4] (s) + N2O4 (l) = NO[Al(OR)4] (s) + Li[NO3] (s),
Li[Al(OR)4] (s) + 3/2N2O4 (l) = (NO2)[Al(OR)4] (s) + Li[NO3] (s) + NO (g),
Li[Al(OR)4] (s) + 2N2O3 (l) = (NO2)[Al(OR)4] (s) + Li[NO3] (s) + N2O (g),
Li[Al(OR)4] (s) + 4NO (g) = NO[Al(OR)4] (s) + Li[NO3] (s) + N2 (g),
Li[Al(OR)4] (s) + 6NO (g) = NO[Al(OR)4] (s) + Li[NO3] (s) + 2N2O (g),
(2)
(3)
(4)
(5)
(6)
(7)
(8)
− 400c − 401b
− 211c − 212b
− 159c − 160b
− 66c − 68b
− 552c − 554b
− 119c − 122b
− 108c − 111b
+ 14c + 11b
− 236c − 236b
− 176c − 176b
− 127c − 123b
− 70c − 71b
− 202c − 203b
− 539c − 540b
− 555c − 556b
− 103c − 106b
− 551c − 553b
− 724c − 727b
− 172c − 172b
− 375c − 375b
− 339c − 339b
a The given reactions are for those with the state of nitrogen oxide that is observed at N.T.P. b R = C(CF3)2Ph. c R = C(CF3)3.
The highest yield of the NO[Al(OR)4] was obtained by the reac-
tion of an excess of a mixture of 95–90 mol% NO and 5–10 mol%
NO2 (about 40 mol of NO per mol of Li[Al(OR)4]). The mixture
of nitrogen oxides reacted with Li[Al(OC(CF3)3)4] to yield a dark
brown solid A. The Raman spectrum of A measured at r.t. showed
a strong broad signal tentatively assigned to N2O, NO, N2O4, which
are shifted in comparison to the absorption bands of free gases,
presumably by coordination of these nitrogen oxides to the acidic
lithium centre, (see ESI† Table 1, Fig. 12). Therefore we propose
that the resulting solid A contains a mixture of complexes of NO,
NO2 (and/or their dimers) and N2O coordinated to lithium. As N2O
is a product of the reaction, it is reasonable to propose that the
key intermediate is a complex of NO, NO2 (and/or their dimers)
with Li[Al(OC(CF3)3)4]. The intense dark brown color of A may
be due to the dimer ONON23 or NO2. The observed absorp-
tion bands of the [NO]+ and the [NO3]− in the Raman spectrum of
A were assigned to the reaction products NO[Al(OC(CF3)3)4] and
Li[NO3].
[Li]+(g, 298.15 K) + [NO3]−(g, 298.15 K)
= Li[NO3](s, 298.15 K)
(9)
The observed reaction of Li[Al(OR)4] and a mixture of NO
and NO2 could proceed either by reaction (2) or (3) for which
G is strongly favourable. Reaction (2) is more thermody-
namically favourable than (3) as more NO disproportionates
(G = −104 kJ mol−1) as shown in eqn. (10).
3NO(g) = N2O(g) + NO2(g)
(10)
The experimental conditions for the best yield of NO[Al(OR)4]
and the greater thermodynamic favourability of this reaction implies
the reaction proceeds by eqn. (2) (Table 2). Both eqns. (2) and (3)
promote the disproportionation of NO as shown in eqn. (10) and
also the autoionisation of NO2 (eqn. (11)).
2NO2(g) = [NO]+(g) + [NO3]−(g)
(11)
Addition of SO2 or CH2Cl2 to A resulted in formation of the
green or blue solution (possibly due to presence of N2O3) at r.t.
as well as precipitation of a white insoluble solid that contained
Li[NO3] [Raman, 14N NMR24,25]. Removal of the solvent yielded
NO[Al(OR)4],1and2.TheRamanspectraoftheNO[Al(OC(CF3)3)4]
and NO[Al(OC(CF3)2Ph)4] obtained by this method are similar to
those of 1 and 2 given by the metathesis reaction of NO[SbF6] and
Li[Al(OC(CF3)3)4] in SO2.
This thermodynamically unfavourable reaction (H = +616.2 kJ
mol−1) is more than compensated for by the favourable dispropor-
tionation energy of 3NO (H = −155.4 kJ mol−1) and lattice energy
of Li[NO3] HLatt = 862 kJ mol−1.
The formation of both (NO)[Al(OC(CF3)3)4] (NO2)[Al(OC-
(CF3)3)4] by the reaction of N2O3 (1:1 mixture of NO and NO2)
implies that this reaction can proceed by reaction (6) as well as (2)
or (3). Reaction with NO2 (N2O4) may proceed either by reaction (4)
or (5). The enthalpy of reaction with NO(g) is strongly exothermic
in reactions (7) and (8). However, Li[Al(OC(CF3)3)4] and NO do not
react as shown in eqns. (7) and (8), presumably due to unfavour-
able kinetics. This implies that the intermediate in reactions (2) and
(3) is a [Li]+ complex containing both NO (and/or (NO)2) and NO2
(and/or N2O4).
Conversion of a mixture of NO and NO2 to N2O, [NO]+
(NO[Al(OR)4]), and [NO3]− (Li[NO3]) can be compared with the
disproportionation of the nitrogen oxides on the Y-type zeolites
NaY, CaY, where the reaction was promoted by a proposed interme-
diate M(NO)x(NO2)y complex giving N2O2, [NO]+, [NO2]+, [NO3]−
and N2O.30 Nitric oxide and nitrogen dioxide have been converted
to N2O and N2 using a variety of transition metal complexes at the
temperatures 100–150 °C,31 with metals that have partially popu-
lated d -orbitals and complex containing -acceptor ligands. Nitric
oxide can also be converted into N2O and N2 on mixed oxide cata-
lysts including alkali or alkaline earth metal oxides and aluminium
oxide (see ref. 31a, p. 66–69). It was proposed that all the reactions
proceeded via intermediate M(NO)x complexes which decompose
at high temperatures giving N2O, N2 and O2 gases.
The thermodynamics of the NO/NO2–LiAl(OR)4 reaction
The assignment of the ionic volumes of the [Al(OC(CF3)3)4]− and
[Al(OC(CF3)2Ph)4]− anions26 allowed us to establish the enthalpy of
reaction using a suitable Born–Fajans–Haber cycle (Scheme 2). The
reaction of Li[Al(OR)4] with the mixture of nitrogen oxides may
occur according to eqns. (1)–(7), Table 2.
Scheme 2 * R = C(CF3)2Ph, † R = C(CF3)3.
A Born–Fajans–Haber cycle is given below for reaction (2)
(Scheme 2). The cycles for reactions (3)–(8) are constructed
similarly.
where: HLatt(Li[Al(OR)4]) = ULatt(Li[Al(OR)4]) + 1/2RT;
HLatt(NO[Al(OR)4]) = ULatt(NO[Al(OR)4]) + 3/2RT;
HLatt((NO2)[Al(OC(CF3)3)4]) = ULatt((NO2)[Al(OC(CF3)3)4]) +
3/2RT;
The lattice energies ULatt of the M[Al(OR)4] salts M = [Li]+,
[NO]+, [NO2]+14,27 were calculated from equation 2 given in ref. 28a.
Enthalpies of formation of nitrogen oxides, [Li]+(g), [NO]+(g),
[NO2]+(g), [NO3]−(g) were taken from ref. 29], the lattice energy of
ULatt(Li[NO3]) was calculated from eqn. (9).
Stability of the Li[Al(OR)4] and NO[Al(OR)4] in the SO2.
Preparation and characterization of {Li[AlF(OC(CF3)2Ph)3]}2 3
Li[Al(OC(CF3)2Ph)4] and Li[Al(OC(CF3)3)4] readily dissolve in
SO2 forming clear solutions and some insoluble residue. The NMR
spectra of the solution of Li[Al(OR)4] shows the major resonance
attributable to Li[Al(OR)4] and a weak signal assigned to the de-
composition product {Li[AlF(OR)3]}, predicted by Krossing1e,32
[See ESI†, Section 6].
The red SO2 solution of 1 decolorizes at room temperature over
several hours due to decomposition of 1 in solution (Scheme 3). The
2 4 9 8
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4

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decomposition products were identified by means of NMR and IR
spectroscopy [See ESI†, Section 7]. NMR spectra of the solution
of 1, 1 and 2 h and 3 weeks after preparation showed resonances
assigned to [Al(OC(CF3)2Ph)4]−, [AlF(OC(CF3)2Ph)3]−, ortho-, para-
HOC(CF3)2PhNO, the fluoride bridged dimer [(PhC(CF3)2O)3Al(-
F)Al(OC(CF3)2Ph)3]−32a,33 and the polymeric aluminium complexes
with bridging fluoride ions and OC(CF3)2Ph ligands.39
Scheme 3
The 19F, 13C and 27Al NMR spectra of SO2 solutions of 2 are
identical after 1 month at +5 °C, therefore compound 2 is stable in
SO2 solution.
Fig. 3 Structure of {Li[AlF(OC(CF3)2Ph)3]}2 3, hydrogen atoms are omit-
ted for clarity.
The compound {Li[AlF(OC(CF3)2Ph)3]}2 3 was obtained by ther-
mal decomposition of Li[Al(OC(CF3)2Ph)4] in a dynamic vacuum
at 138–143 °C. Under these conditions the Li[Al(OC(CF3)2Ph)4]
sublimed in about 7% yield, but most of the complex decomposed
without sublimation to yield 3 as a major product as well as the
alcohol HOC(CF3)2Ph as a major product (NMR, EI-MS, IR) and
the alkene CF2C(CF3)Ph)3 (Scheme 4).34
1.7139(17) Å in the four membered rings Li(a)(-F1)(-O1)Al and
Li(-F(1a))(-O(1a))Al(a) are close to the Li–F and Al–F distances
in other complexes containing the Li(-F)Al unit. For comparison,
the Li–F = 1.852 Å and the average Al–F distance 1.688 Å in the
[Li(Me3Si)3CAlF3(THF)]4,38 the average Li–F bond length 1.84 Å,
the average Al–F distance 1.733 Å in the [((Me3Si)3CAlF2)2(-
O)Li2(THF)4].39 The distances between Li and fluorine atoms of
1,1,1,3,3,3-hexafluoro-2-phenyl-2-propoxide ligand 2.220(6)–
2.428(6) Å are close to those in the known complexes with the
lithium ion coordinated to the organofluorine ligand 2.25(1), 2.27(1)
and 2.710(7)–2.928(7) Å26,40–42 (See ESI†, Section 11).
Elemental analysis showed that complex 3 corresponds to
{Li[AlF(OC(CF3)2Ph)3]}. Compound 3 is thermally stable with a
m.p. in the range of 131–132 °C, and crystals of 3 did not change
appearance on storage in a glove box at r.t. for several months.
The absorption bands in the IR and Raman spectra at 745, 754,
794, 841 (IR), 854 (IR) cm−1 are assigned9d to the Al–O vibrations.
The Al–O absorption bands of 3 and Li[Al(OC(CF3)2Ph)4] are simi-
lar with differences that are not greater than 2 cm−1. Replacement
of one 1,1,1,3,3,3-hexafluoro-2-phenyl-2-propoxide ligand by a
fluorine leads to the appearance in the IR spectrum of a weak line
at 652 cm−1 assigned to the Al–F vibration43 and some changes in
the shape of the absorption band that has a maximum at 795 cm−1.
Previously it was reported that the [AlF4]− anion exhibits a charac-
teristic IR band at 783 cm−1.44
Scheme 4
Colorless crystals of 3, suitable for X-ray diffraction analysis,
were obtained by crystallization from toluene solution. Complex 3
consists of two {Li[AlF(OC(CF3)2Ph)3]} units,35 which are associ-
ated via fluorine lithium contacts to give a dimer containing a ladder
with transoid orientation (Figs. 2 and 3).36 The Li–F1 (0.06 v.u.),
Li–F14 (0.06 v.u.), Li–F3 (0.08 v.u.), Li–F5 (0.10 v.u.) and Li–F18
(0.07 v.u.)37 contacts between the {Li[AlF(OC(CF3)2Ph)3]} units
are substantially weaker than Li–F(1a) (0.28 v.u.) and Li–O(1a)
(0.22 v.u.) contacts within the moieties.
Analysis of the isotope distribution in the EI-MS of 3 showed
that the detected ions contained no lithium and are formed by sub-
traction from the dimeric ion of LiF, F, CF3, Ph, C(CF3)nPhm where
n = 1, 2, m = 0, 1 and OC(CF3)2Ph fragments.
At low and room temperatures, the 19F45,27Al, 7Li NMR spectra
of SO2 solutions of 3 showed a single resonance (Table 2), the 13
C
spectrum shows only one type of CF3 of phenyl and of carbon atom
connected to those groups (Table 2). The observed single fluorine
atom environment of –CF3 group, a single type of phenyl group,
absence of the fine structure of the 27Al and 7Li resonances indicates
that molecule 3 is definitely not rigid in SO2 solution and is therefore
involved in rapid exchange processes, rendering the uniqueAl–(F1)
undetected,45 presumably by line broadening even at −70 °C.
Conclusions
The NO[Al(OR)4], R = C(CF3)2Ph, C(CF3)3 salts were prepared in
good yield by the metathesis reactions of Li[Al(OR)4] and NO[SbF6]
in sulfur dioxide solution with precipitation of insoluble Li[SbF6](s).
This implies that other metathesis reactions with SO2 soluble [MF6]−
saltswillgiveawiderangeoftherelatedsaltsof[Al(OC(CF3)3)4]− and
[Al(OC(CF3)2Ph)4]−.WehaveestablishedthatLi[Al(OR)4]reactswith
amixtureofNOandNO2 toproduceNO[Al(OR)4], Li[NO3]andN2O.
This unusual reaction proceeds via an intermediate lithium complex
with NO, NO2 (and/or their dimers) and N2O stabilized by the large
[Al(OR)4]− anion. The experimental conditions and thermodynamic
calculations imply that this reaction proceeds according to eqn. (2)
(Table 2), H(reaction) −400 kJ mol−1 (R = C(CF3)3), −401 kJ mol−1
(R = C(CF3)2Ph) and G(reaction) −236 kJ mol−1 (R = C(CF3)3 and
R = C(CF3)2Ph). The driving force of this reaction, that enforces the
Fig. 2 A view of the core of 3 including the bond valencies (v.u.), the
protons, carbon atoms attached to CF3, fluorine atoms not interacting with Li
and phenyl groups are omitted for clarity, *-atoms of the ion pair B.
Six fluorine atoms and one oxygen atom form an unusual seven
coordinate environment around the lithium center with the short
Li–F(1a) (1.827(5) Å, 0.28 v.u.), Li–O(1a) (2.023(6) Å, 0.2 v.u.)
distances in addition to other substantially longer contacts 2.220(6)–
2.428(6) Å (0.06–0.10 v.u.) between lithium and F1 of the neigh-
boring ion pair {Li[AlF(OC(CF3)2Ph)3]} and with the F(3a), F(5a),
F14, F18 of CF3 groups of the 1,1,1,3,3,3-hexafluoro-2-phenyl-2-
propoxide ligand, (sum of the van der Waals’ radii of lithium and
fluorine 3.29 Å17). The bond lengths Li–F(1a) 1.827(5) Å andAl–F1
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4
2 4 9 9

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unfavourable autoionisation of 2NO2(g) to [NO3]−(g) and [NO]+(g)
(H = +616 kJ mol−1), is the high lattice energy of Li[NO3](s) (863.1
kJ mol−1) and the favourable disproportionation energy of 3NO(g)
to NO2(g) and N2O(g) (−155.4 kJ mol−1). Nitrogen dioxide and
Li[Al(OC(CF3)3)4] give a solid likely containing the [NO3(NO)3]2+
[FT-Raman] previously characterized in ref. 22. Preliminary
evidence suggests that complexes of type [Li(NO)x][Al(OC(CF3)3)4]
are formed at low temperature. Thus preliminary evidence has been
found for a rich coordination chemistry of the simple oxides of ni-
trogen towards [Li]+ in salts of WCAand will be the subject of future
exploration.
The [NO]+ cation in the solid 1 form the donor acceptor ad-
duct with the [Al(OC(CF3)2Ph)4]− anions (X-ray, IR, Raman). The
temperature dependent 14N NMR spectra of the SO2 solution of 1
shows an equilibrium between a coordinated [NO]+ and a separated
solvated [NO]+. The [NO]+ and [Al(OC(CF3)3)4]− ions in 2 are
eventually ionic, similar to the NO[AF6] where A = U, As, Sb and
NO[HSO4] salts.
valves (HP 6 K), was charged with Li[Al(OC(CF3)2Ph)4] (1.45 g,
1.4 mmol) and NO[SbF6] (0.43 g, 1.6 mmol). SO2 (15 ml) was
condensed onto the mixture of reagents at −196 °C. The resulting
mixture was stirred at r.t. for 1 h. A red solution was filtered from
a white insoluble solid (0.47 g, expected for the Li[SbF6] with the
excess of NO[SbF6] 0.43 g) and SO2 was slowly removed to give
a red crystalline solid covered with a red oil. Dichloromethane
(2–3 ml) was condensed onto the red crude product. The result-
ing mixture was carefully warmed to −20 °C with stirring and the
dichloromethane filtered off while cold to give a red solid 1. Yield
0.6 g, (40%, based on the Li[Al(OC(CF3)2Ph)4]). C36H20AlF24NO5:
calcd. C 42.00, H 1.96, N 1.36; found C 41.29, H 1.86, N 1.34.
M.p. 97–99 °C, EI-MS (30 eV, heating r.t.–170 °C): m/z (%) = 777
(2.7) [M+ − 2Ph–CF3–NO], 604 (8.0) [M+ − 2Ph–L–NO], 469 (5.7)
[M+ − Ph–2CF3–C(CF3)2Ph–NO], 400 (4.7) [M+–2C(CF3)2Ph–Ph–
CF3–NO], 244 (100) [L+], 224 (70) [L+ − HF] 205 (34) [M+ − HF2],
175 (100) [L+ − CF3], 127 (95) [L+ − C2HOF4], 105 (95) [L+ −
+
HC2F6], 77 [Ph+], 69 [CF3 ]. LHOC(CF3)2Ph, calculated theoreti-
The lithium salts Li[Al(OR)4] R = C(CF3)3, C(CF3)2Ph par-
tially decompose in SO2 solution giving Li[AlF(OR)3] (NMR).
NO[Al(OC(CF3)3)4] is stable in the SO2 solution at room tem-
peratures and lower. NO[Al(OC(CF3)2Ph)4] is unstable in SO2
solution giving [AlF(OC(CF3)2Ph)3]−, [(PhC(CF3)2O)3Al(-
F)Al(OC(CF3)2Ph)3]− as well as (NO)C6H4C(CF3)2OH decomposi-
tion products (NMR, IR). {Li[AlF(OC(CF3)2Ph)3]}2 3 was prepared
in good yield by the thermal decomposition of Li[Al(OC(CF3)2Ph)4]
under evacuation. 3 consists of two {Li[AlF(OC(CF3)2Ph)3]} units
weakly connected by Li–F contacts into a dimer.
cal isotopes distribution matched that experimentally observed for
all peaks. H NMR (400 MHz, SO2, r.t.), H (ppm) = 7.7 (br, 6H,
1
H2), 7.75 (m, 3H, H1), 7.9 (br), 8.05 (br), 8.3 (m, 6H, H3). 27Al
NMR (104.2 MHz, SO2, r.t.), Al (ppm) = 33.6. 19F NMR (376.3
MHz, SO2, r.t.), F (ppm) = −73.4; weak signals due to decomposi-
tion −74.5; −70.2. 14N NMR (28.9 MHz, SO2, r.t.), N (ppm) = 0 ±
15 ppm, broad resonance; (SO2, −70 °C), N (ppm) = 115 ppm,
shoulder −80 ppm, broad resonance. Signal to noise ratio of the 14
N
resonance of [NO]+ is low, probably due to exchange processes in
solution. IR (AgCl, cm−1, Nujol): 2954 (vs), 2924 (vs), 2853 (vs),
2035 (NO), 1466 (vs), 1462 (vs), 1458 (vs), 1453 (vs), 1451 (vs),
1447 (vs), 1437 (m), 1377 (vs), 1366 (m), 1355 (w), 1340 (w), 1333
(w), 1310 (m), 1269 (m), 1235 (m), 1213 (vs), 1207 (vs), 1192 (m),
1167 (vs), 1139 (m), 1133 (m), 1110 (w), 1102 (w), 1083 (w), 1077
(w), 1037 (w), 1020 (w), 1003 (w), 988 (w), 969 (vs), 939 (vs), 928
(m), 921 (m), 873 (w), 825 (w), 774 (w), 770 (w), 762 (w), 745 (m),
736 (w), 722 (vs), 720 (vs), 715 (vs), 713 (vs), 663 (m), 566 (w), 542
(w). Raman (solid, cm−1): 3129 (w), 3085 (vs), 3032 (w), 2784 (w),
2380 (m), 2272 (w), 2215 (vs), 2036 (vs, NO+), 1598 (m), 1577 (m),
1488 (w), 1447 (w), 1386 (w), 1336 (w), 1313 (w), 1292 (w), 1218
(m), 1172 (m), 1069 (m), 1035 (m), 1005 (m), 967 (w), 941 (m), 869
(w), 794 (w), 776 (w), 739 (w), 723 (w), 661 (w), 618 (m), 565 (w),
541 (w), 497 (w), 379 (w), 329 (vs), 302 (m), 237 (m), 180 (m). IR
and Raman spectrum are given (see ESI†, Figs. 3, 4 and 7).
Raman spectrum of the insoluble material was identical to that
of Li[SbF6].47
Experimental
General remarks
All operations were performed using standard Schlenk line tech-
niques under a purified nitrogen atmosphere. Solid reagents and
crystals were manipulated in a Vacuum Atmospheres Dri-Lab
equipped with a Dri-Train (HE-493) and 1 kg of 3 Å molecular
sieves contained in an internal circulating drying unit. Reactions in
SO2 were carried out in a joinless, single apparatus fitted with Teflon
in glass Rotoflo valves (HP 6 K) and consisting of two thick walled
round bottom bulbs (V = 50 ml) linked by a glass tube incorporated
a sintered fine-porosity glass frit. Nitric oxide NO (99%, Canadian
liquid air) and NO2 (99.5%, Matheson), NOSbF6 (98%, Syn Quest
Labs.) were used as received. The compounds Li[Al(OC(CF3)3)4]
and Li[Al(OC(CF3)2Ph)4] were prepared by literature methods.2c,d,46
1
7
The purity of Li[Al(OR)4] was verified by H, 19F, Li, 27Al, 13C
NMR spectra and FT Raman spectra. Sulfur dioxide was dried over
P2O5 and distilled prior to use, CH2Cl2 and CDCl3 were dried over
CaH2 and degassed. NMR spectra were recorded using a Varian 400
NMR spectrometer. Proton and 13C chemical shifts are reported in 
units downfield from Me4Si with the solvent as the reference signal.
CClF3 and MeNO2 were used as references for measuring 19F and
14N spectra and aqueous solutions ofAlCl3 and LiClO4 were used as
references for measuring 27Al and 7Li NMR spectra. NMR samples
were prepared in 10 mm and 5 mm thick walled NMR tubes fitted
with J. Young valves. Mass spectra were recorded using a KRATOS
ms 50 TC mass spectrometer equipped with the EI source, 30 eV,
from samples sealed in dried glass m.p.t. tubes by the direct inlet
method; FT-IR spectra were recorded using a Thermo Nicolet spec-
trometer (Nexus 470 FT-IR) and FT-Raman spectra were obtained
from neat samples, sealed under a nitrogen atmosphere in glass
capillaries, using an FT-IR spectrometer (Bruker IFS66) equipped
with an FT-Raman accessory (Bruker FRA106) incorporating a Nd-
YAG laser (emission wavelength: 1064 nm; maximum laser power:
300 mW). Melting points were measured in sealed capillary tubes
under nitrogen and are not corrected. Elemental analysis was car-
ried out by Galbraith laboratories, Inc. All Raman spectra reported
below are included in the ESI.†
Method 2. A 50-ml Schlenk flask fitted with a Rotoflo valve
was charged with Li[Al(OC(CF3)2Ph)4] (0.83 g, 0.8 mmol). The
mixture of (90 mol% NO, 10 mol% NO2, approximately 40 mol
of NO per 1 mol of Li[Al(OC(CF3)2Ph)4] (sufficient liquid oxides
of nitrogen to cover all the solid Li[Al(OC(CF3)2Ph)4] on melting)
was condensed on to Li[Al(OC(CF3)2Ph)4] at −196 °C. A dark red
solid formed at r.t. on warming and the pressure of the gas in the
Schlenk flask was maintained close to 1 atmosphere by condens-
ing the excess gas in to the trap at −196 °C. The resulting solid
was cooled to −196 °C and CH2Cl2 (20 ml) added via a vacuum
line. The resulting dark red solution was warmed to r.t., filtered,
concentrated to approximately 4–6 ml and left at −24 °C. The dark
red crystals of NO[Al(OC(CF3)2Ph)4] formed over a period of 1
week. The cold supernatant solution was removed by a syringe and
the remaining crystals were collected and carefully dried under a
dynamic vacuum (2–3 min). Yield of 1 0.25 g, 30%, based on the
Li[Al(OC(CF3)2Ph)4] following to eqn. (2), Table 2. M.p. 97–99 °C.
NMR, IR, Raman spectra of the red crystals are identical to those of
the red powder obtained by method 1.
The insoluble product contains red 1, according to the IR spectrum
and white solid Li[NO3] (Raman24,25). 14N NMR (28.9 MHz, D2O,
r.t.), N (ppm) = −5.5. IR of the white insoluble solid (Li[NO3])
(AgCl, cm−1, Fluorolube): 2444 (w), 1796 (m), 1381 (br, vs), 1200
(br, vs), 1124 (br, vs), 1401 (m), 968 (vs), 900 (vs), 840 (vs), 792 (w),
770 (w), 746 (m), 737 (m), 728 (m), 721 (m), 709 (m), 687 (w), 650
(vs), 604 (vs), 546 (m), 521 (m) is similar to that of pure Li[NO3].
Preparation of NO[Al(OC(CF3)2Ph)4]. Method 1. A dried two
bulb (50 ml) vessel equipped with Teflon in glass with Rotoflo
2 5 0 0
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4

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In situ experiment. A mixture of (90 mol% NO, 10 mol% NO2),
approximately 80 mol of NO per 1 mol of Li[Al(OC(CF3)2Ph)4]
(sufficient liquid oxides of nitrogen to cover all the solid Li[Al-
(OC(CF3)2Ph)4] on melting) was condensed on to Li[Al(OC-
(CF3)2Ph)4] (0.33 g, 0.33 mmol, 10 mm NMR tube) at −196 °C.
The liberated gas on warming was condensed into another trap.
The pressure of the gas in a NMR tube was maintained close to
1 atmosphere. SO2 was condensed on to the solid, giving a clear
red solution over a white precipitate. 14N NMR (28.9 MHz, SO2,
r.t.), N (ppm) = −153 (N2O), −236 (N2O); 19F NMR (376.3 MHz,
SO2, r.t.), F (ppm) = −73.0 ([Al(OC(CF3)2Ph)4]−); −69.4
((NO)C6H4C(CF3)2OH).
All volatiles were removed under dynamic vacuum and SO2
was added to give a red solution over a white precipitate. 14N
NMR (28.9 MHz, SO2, r.t.), N (ppm) = 30 ± 20 ppm (broad,
[NO]+); 19F NMR (376.3 MHz, SO2, r.t.), F (ppm) = −73.0; weak
signals −74.2, −73,7, −69.9; 27Al NMR (104.2 MHz, SO2, r.t.), Al
(ppm) = 33.2.
521 (m). The Raman and IR spectra of this powder are similar to that
of NaNO3, KNO324,25 and identical with that of LiNO3 (this work).
14N NMR (28.9 MHz, D2O, r.t.), N (ppm) = −5 ppm (broad, NO3−);
19F NMR (376.3 MHz, D2O, r.t.), F (ppm) = −76.1, −75.7, −74.8
main signal. 27Al NMR (104.2 MHz, D2O, r.t.), Al (ppm) = −1.8
(br), 32.8.
Raman spectral measurement of the reaction intermediate.
The dark brown solid A resulting from treatment of the solid
Li[Al(OC(CF3)3)4] with a mixture of NO and NO2 (procedure de-
scribed above) was transferred in a vessel to a glove box, where the
solid A was transferred into glass capillaries and sealed. The Raman
spectrum of the brown solid, glass capillary, r.t. (solid, cm−1): 2340
(w), 2156 (br, vs), 1933 (s), 1280 (s), 1070 (m), 812 (vs), 746 (w),
562 (w), 537 (w), 366 (w), 325 (w), 237 (br, vs) is shown in ESI†
(see Fig. 12) (including assignment).
In situ experiment. Mixture (90 mol% NO, 10 mol% NO2,
80 mol of NO per 1 mol of Li[Al(OC(CF3)2Ph)4]) was reacted
with Li[Al(OC(CF3)3)4] (0.3 g, 0.3 mmol, 10 mm NMR tube). A
green solution over a white precipitate was obtained. 14N NMR
(28.9 MHz, SO2, r.t.), N (ppm) = −153 (N2O), −236 (N2O);
19F NMR (376.3 MHz, SO2, r.t.), F (ppm) = −74.0. 27Al NMR
(104.2 MHz, SO2, r.t.), Al (ppm) = 36.5.
All volatiles were removed under dynamic vacuum and SO2
added at −196 °C to give a slightly yellow solution over a white
precipitate. 14N NMR (28.9 MHz, SO2, r.t.), N (ppm) = 5 ± 20 ppm
(broad, NO+). F (ppm) = −74.0. 27Al NMR (104.2 MHz, SO2, r.t.),
Preparation of NO[Al(OC(CF3)3)4]. Method 1. Method of
preparation of 2 is similar to that of 1. Reaction with rigorous
stirring for 3 days at +5 °C. Yield of 2 1.6 g 85% based on the
Li[Al(OC(CF3)3)4] and eqn. (3). C16AlF36NO5: calcd. C 19.26, N
1.40, F 68.6; found C 18.61, N 1.19, F 70.45. M.p. 142–143 °C, EI-
MS (30 eV, heating r.t.–170 °C): m/z (%) = 872 (0.5) [M+–NO–5F],
829 (1) [M+–NO–2CF3], 660 (0.5) [M+–NO–C(CF3)3–CF3–F],
656 (1) [M+–L–NO–4F], 555 (1) [M+–L–NO–2CF4], 539 (4)
[M+–L–NO–C2F8O], 523 (1) [M+–C(CF3)3–NO–3CF3–F], 513
(15) [M+–L–NO–C(CF3)3], 497 (15) [M+–2L–NO], 444(3)
[M+–L–C(CF3)3–NO–CF3], 413 (12) [M+–2L–NO–CF3O],
L = OC(CF3)3 calculated theoretical isotopes distribution matched
that experimentally observed for all peaks. 14N NMR (28.9 MHz,
SO2, r.t.), N (ppm) = −4 ± 10 ppm (broad, [NO]+); 19F NMR (376.3
MHz, SO2, r.t.), F (ppm) = −74.0; 27Al NMR (104.2 MHz, SO2, r.t.),
Al (ppm) = 36.5
Interaction of Li[Al(OC(CF3)3)4] with NO2
The NO2, (10 g, 217.4 mmol) was added to Li[Al(OC(CF3)3)4]
(1.16 g, 1.2 mmol) at −196 °C in a dried two bulb (50 ml) vessel
equipped with Teflon in glass with Rotoflo valves (HP 6 K). The
resulting solid was warmed to r.t. to give a brown liquid which was
filtered after 16 h from a white insoluble LiNO3 (0.12 g) (Raman)
(expected for complete reaction 0.08 g). The NO2 was slowly re-
moved under dynamic vacuum to give a yellow solid (0.96 g). The
obtained solid was placed in a glass capillary in the glove box at
r.t., which was then flame sealed. The Raman spectrum of the yel-
low solid (solid, cm−1): 2340 (w) (NO+), 2273 (vs) ([NO3(NO)3]2+),

Al (ppm) = 37.1. 13C NMR (100.6 MHz, SO2, r.t.), C (ppm) = 79.8
(br, C(CF3)3), 122.1 (q, C(CF3)3, J = 289 Hz). Raman spectrum
(solid, cm−1): 236 (m), 291 (m), 324 (vs), 368 (m), 537 (m), 562 (m),
572 (m), 746 (vs), 796 (vs), 977 (w), 1128 (w), 1275 (w), 1313 (w),
2340 (NO+). Raman spectrum is given in Figs. 5 and 8 in the ESI.†
The reaction product showed 7Li resonance due to
Li[Al(OC(CF3)3)4] 7Li NMR (155.4 MHz, SO2, r.t.), Li
(ppm) = −0.2. A comparison of the absolute intensities of 7Li
resonances in the spectrum of the reaction product and in the spec-
trum of the solution of Li[Al(OC(CF3)3)4] of known concentration
showed that the relative amount of Li[Al(OC(CF3)3)4] in the reac-
tion product was less than 2%.
+
1550 (br, w, N4O6 ) (NO2+), 1314 (br, w), 1272 (w, [NO3(NO)3]2+),
1005 (w, [NO3(NO)3]2+), 814 (w), 795 (s), 721 (s), 572 (m), 538
(m), 370 (m), 324 (s), 291 (m), 238 (m), 211 (w), 178 (w), 120 (w)
is shown in ESI† (see Fig. 11). 14N NMR (28.9 MHz, SO2, r.t.),
N (ppm) = −340 (br), 225 (br, w), 415 (br, w), F (ppm) = −75.5
([Al(OC(CF3)3)4]− anion). 27Al NMR (104.2 MHz, SO2, r.t.), Al
(ppm) = 35.6 ([Al(OC(CF3)3)4]− anion).
Method 2. A Li[Al(OC(CF3)3)4] (2.44 g, 2.1 mmol) was
loaded in a dried two bulb (50 ml) vessel equipped with Teflon
in glass with Rotoflo valves (HP 6 K). The mixture of (90 mol%
NO, 10 mol% NO2, approximately 40 mol of NO per 1 mol of
Li[Al(OC(CF3)3)4] (sufficient liquid oxides of nitrogen to cover
all the solid Li[Al(OC(CF3)2Ph)4] on melting) was condensed on
to Li[Al(OC(CF3)3)4] at −196 °C. The resulting solid melted and
formed a blue liquid that reacted with Li[Al(OC(CF3)3)4] to yield
a dark brown solid (A). The pressure of the gas in the vessel was
maintained near to 1 atmosphere. The SO2 was condensed on to
the solid at −196 °C, then held at +5 °C for 2 h. Then supernatant
solution was filtered from white insoluble solid (calcd. for Li[NO3]
0.17 g using eqn. (2), Table 2, obtained 0.27 g), and SO2 was
slowly condensed from the mixture into a second bulb of the ves-
sel held at 0 °C. The last portions of solvent were removed under
dynamic vacuum to give the white solid 1. Yield 2.1 g 85% based
on Li[Al(OC(CF3)3)4] assuming eqn. (2), Table 2. M.p. 142–143 °C.
NMR and Raman spectra of the reaction product are identical to
those for 2 obtained by method 1.
Interaction of Li[Al(OC(CF3)3)4] with NO
The NO, (10 g, 333.3 mmol) was added to Li[Al(OC(CF3)3)4]
(1.75 g, 1.8 mmol) at −196 °C in a dried two bulb (50 ml) vessel
equipped with Teflon in glass with Rotoflo valves (HP6 K). The NO
melted forming a colorless liquid over a brown solid which may be
an Li(NO)x[Al(OC(CF3)3)4] salt. On warming NO evaporated and
the color of the solid changed to green, pink and then white at r.t.
The SO2 was condensed on to the white solid at −196 °C. The result-
ing solution was filtered (amount of the insoluble solid is less than
0.03 g) and evaporated under dynamic vacuum to finally give 1.69 g
of a white SO2 soluble solid. The 7Li, 27Al, 19F NMR spectra of the
solid are similar to that of Li[Al(OC(CF3)3)4]. No resonance in the
14N NMR spectrum was detected.
Stability of Li[Al(OR)4] in SO2
The Raman spectrum of the white insoluble solid (solid, cm−1):
1383 (w), 1070 (vs), 735 (w), 235 (s). IR (AgCl, cm−1, Fluorolube):
2510 (w), 2444 (w), 1796 (m), 1381 (vs), 1194 (vs), 1124 (vs), 1041
(m), 968 (vs), 900 (vs), 840 (vs), 805 (w), 792 (w), 770 (w), 748
(m), 737 (m), 728 (m), 710 (w), 687 (w), 650 (s), 604 (s), 546 (m),
The Li[Al(OC(CF3)3)4] initially formed a transparent colorless
solution in SO2. Deposition of a small amount of the solid was
observed after several hours at +5 °C. However, the solution and
the solid did not change in appearance on keeping for several
weeks (NMR spectra are the same). 19F NMR (376.3 MHz, SO2,
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4
2 5 0 1

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Table 3 Chemical shifts of the Li[Al(OR)4], NO[Al(OR)4] and (R = C(CF3)2Ph, C(CF3)3), {LiFAl(OR)3}, NO[AlF(OC(CF3)2Ph)3] in SO2 solution at room
temperature
Compound

19F (ppm)

27Al (ppm)
 7Li (ppm)

14N (ppm)
Li[Al(OC(CF3)2Ph)4]
{Li[AlF(OC(CF3)2Ph)3]}
NO[Al(OC(CF3)2Ph)4]
NO[AlF(OC(CF3)2Ph)3]
Li[Al(OC(CF3)3)4]
−73.8
−72.8
−73.3
−74.5
−74.0
−73.3
−74.0
41.9
33.6
33.6
33.6
36.8
40.6
36.9
−0.12
−0.25
−10 ± 15
−15 ± 15
−0.36
−0.49
{Li[AlF(OC(CF3)3)3]}
NO[Al(OC(CF3)3)4]
−4 ± 15
Table 4 Crystallographic data and structure refinement details for 1 and 3
1
3
Formula
C36H20AlF24NO5 NO[Al(OC(CF3)2Ph)4]
C27H15AlF19LiO3 Li[AlF(OC(CF3)2Ph)3]
Mr
1029.51
782.31
Temp./K
198(1)
198(1)
Radiation Used, /Å
Crystal description
Crystal size/mm
Crystal system
Space group
a/Å
b/Å
c/Å
/°
Mo–K (0.71073)
Red, irregular
0.1 × 0.15 × 0.4
Monoclinic
Cc
19.5256(16)
11.1297(7)
19.5469(13)
90
Mo–K (0.71073)
Colorless, plate
0.15 × 0.35 × 0.4
Monoclinic
P2(1)/c
15.976(3)
17.319(3)
10.7970(19)
90
/°
112.289(2)
90
3930.4(5)
4
97.918(2)
90
2958.8(9)
4
/°
V/Å3
Z,
F (000)
2048
1.740
0.211
1552
1.756
0.220

calcd./g cm−3
/mm−1
Total reflections
Unique reflections
R(int)
9634
5276
0.0156
14373
4999
0.1041
Scan range /°
Completeness to max (%)
Index ranges
2.15 to 24.99
96.1
1.74 to 25.00
95.9
−22 ≤ h ≤ 20
−12 ≤ k ≤ 13
−23 ≤ l ≤ 21
5276/2/684
0.0244, 0.0587
0.0261, 0.0598
1.065
−18 ≤ h ≤ 18
−19 ≤ k ≤ 20
−12 ≤ l ≤ 12
4999/0/520
0.0492, 0.1213
0.0831, 0.1343
0.993
Data/restrains/parameters
R1, wR2 [I > 2(I)]
R1, wR2 (all data)
Goodness-of-fit on F2
Max./min. el. dens./e Å−3
Min./Max. transmission ratio
0.220 and −0.142
0.941
0.591, −0.270
0.643
4
2
wR2 = (∑[w(Fo2 − Fc2)2]/∑[Fo ])1/2, R1 = ∑||Fo| − |Fc||/ ∑ |Fo|, Weight = 1 / [2(Fo2) + (0.0745 * P)2]; where P = (max (Fo , 0) + 2 * Fc2)/3.
1 ml of colorless liquid condensed into the cold trap at −196 °C.
r.t.), F (ppm) = −73.3 (5–7% relative intensity), −74.0 (100%
relative intensity, Li[Al(OC(CF3)3)4]); 27Al NMR (104.2 MHz,
SO2, r.t.), Al (ppm) = 40.6, 36.8. 13C NMR (100.6 MHz, SO2, r.t.),
C (ppm) = 79.8 (br, C(CF3)3), 122.1 (q, C(CF3)3, J = 289 Hz), 7Li
NMR (155.4 MHz, SO2, r.t.), Li (ppm) = −0.36. NMR spectra of
solution after keeping 3 weeks at +5 °C are identical. Chemical
shifts are given in Table 3.
The black non-sublimed solid was recrystallized from toluene fol-
lowed by washing the resulting crystals with pentane. The operation
was repeated four times until the product became a white crystal-
line solid. Yield 11.6 g, (75%, based on the Li[Al(OC(CF3)2Ph)4]).
C27H15AlF19LiO3: calcd. C 41.45, H 1.93; found C 42.04, H
1.90. M.p. 131–132 °C, EI-MS (30 eV, heating r.t.–170 °C): m/z
(%) = 1054 (1.5) [M+ − 2LiF–L–2CF3–Ph] (L = OC(CF3)2Ph),
Li[Al(OC(CF3)2Ph)4] initially formed a transparent colorless so-
lution in SO2.ASmall amount of the solid was observed after several
hours at +5 °C. However the solution and the solid did not change ap-
pearance on keeping for several weeks (NMR spectra are the same).
19F NMR (376.3 MHz, SO2, r.t.), F (ppm) = −72.8 (5–7% relative
intensity), −73.8 (100% relative intensity Li[Al(OC(CF3)2Ph)4]);
27Al NMR (104.2 MHz, SO2, r.t.), Al (ppm) = 33.4 (2% relative
962 (4.9) [M+ − 2LiF–L–C(CF3)2Ph–CCF3], 950 (32.9) [M+
−
2LiF–2L–4F], 938 (89.8) [M+ − 2LiF–2L–CF4], 903 (2.9) [M+ −
LiF–2L–C4F6], 889 (23.4) [M+ − 2LiF–2L–2CF3], 876 (92.4)
[M+ − 2LiF–2L–C3F6], 738 (2.3) [M+ − 2LiF–2L–C11H4F8], 710
(2.5) [M+–2LiF–2L–C10F10H4], 695 (14.5) [M+–2LiF–3L–CF4], 682
(21.4) [M+ − 2LiF–3L–C2F4H], 668 (64.2) [M+ − 2LiF–3L–Ph–2F],
649 (4.2) [M+ − 2LiF–3L–Ph–3F], calculated theoretical isotopes
distribution matched that experimentally observed for all peaks, 1H
NMR (400 MHz, SO2, r.t.), H (ppm) = 8.4 (t, 6H, J = 7.4 Hz, H2),
8.5 (m, 3H, J = 7.2 Hz, H1), 9.1 (d, 6H, J = 7.5 Hz, H3); (hexane,
r.t.), H (ppm) = 7.6 (t, 6H, J = 8.0 Hz, H2), 7.7 (t, 3H, J = 7.4 Hz,
H1), 8.3 (d, 6H, J = 8.2 Hz, H3). 13C NMR (100.6 MHz, SO2, r.t.), C
(ppm) = 80.9 C(CF3)2Ph, 125.1 (q, C(CF3)2Ph, J = 291 Hz), 128.3
C(CF3)2Ph, 129.3 C(CF3)2Ph, 130.2 C(CF3)2Ph, 136.6 C(CF3)2Ph.
27Al NMR (104.2 MHz, SO2, r.t.), Al (ppm) = 33.7; (hexane, r.t.), Al
(ppm) = 31 (1/2 1690 Hz), 61 (1/2 5100 Hz); (hexane, −80 °C),
7
intensity), 41.9 (100% relative intensity). Li NMR (155.4 MHz,
SO2, r.t.), Li (ppm) = 0.12. For assignment see Table 3.
Preparation of {Li[AlF(OC(CF3)2Ph)3]}2
A Li[Al(OC(CF3)2Ph)4] (20 g, 19.9 mmol) was loaded into a
sublimation apparatus (100 ml). The apparatus was heated to
135–145 °C for 2 h under a dynamic vacuum. At this temperature
the white Li[Al(OC(CF3)2Ph)4] sublimed (1.4 g, 1.4 mmol, yield
7% based on the Li[Al(OC(CF3)2Ph)4]). During this time about
2 5 0 2
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4

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Al (ppm) = 61 (1/2 5010 Hz). 7Li NMR (155.4 MHz, SO2,
r.t.), Li (ppm) = −0.25; (hexane, r.t.), Li (ppm) = −1.9 (1/2
18 Hz), (hexane, −80 °C), Li (ppm) = −2.2 (1/2 18 Hz). 19F
NMR (376.3 MHz, SO2, r.t.), F (ppm) = −72.8; (hexane, r.t.), F
(ppm) = −75.2; (hexane, −80 °C), F (ppm) = −75.7, −76.2. IR
(AgCl, cm−1, Perfluoroalkyl ether, Fluorolube mull): 3130 (w), 3093
(w), 3069 (w), 3037 (w), 2963 (w), 1617 (w), 1503 (m), 1263 (vs),
1239 (vs), 1201 (vs), 1171 (vs), 1148 (vs), 1125 (vs), 1038 (w), 1024
(w), 965 (vs), 941 (vs), 920 (w), 902 (m), 885 (w), 839 (w), 795 (m),
767 (w), 761 (w), 746 (w), 734 (w), 714 (vs), 691 (w), 666 (m), 663
(m), 652 (w), 619 (w), 604 (m), 570 (w), 565 (w), 553 (w), 544 (w),
538 (w), 531 (w), 504 (w), 474 (w). Raman (solid, cm−1): 3177 (w),
3125 (w), 3085 (vs), 3049 (w), 3037 (w), 2988 (w), 2901 (w), 1606
(vs), 1589 (m), 1454 (w),1340 (w), 1285 (w), 1216 (w), 1182 (m),
1040 (m), 1006 (vs), 968 (w), 945 (m), 919 (w), 793 (m), 759 (m),
746 (m), 733 (m), 697 (m), 620 (m), 567 (w), 546 (w), 469 (w), 379
(w), 348 (m), 333 (m), 320 (m), 305 (m), 286 (m), 258 (m), 240 (w),
221 (m). The Raman spectrum is given (see ESI†, Fig. 9).
The colorless liquid collected in the cold trap: 1H NMR
(400 MHz, SO2, r.t.), H (ppm) = 5.1 (s, 1H, (CF3)2C(OH)Ph),
8.2, 8.3, 8.6 (br, H1 + H2 (CF3)2C(OH)Ph), 8.7, 8.8. (d, 6H,
J = 8.5 Hz, H3 (CF3)2C(OH)Ph). 19F NMR (376.3 MHz, SO2, r.t.),
F (ppm) = −108.0 (t, 2F, J = 10.7 Hz, CF2CPhCF3), −78.8 (t, 3F,
J = 10.7 Hz, CF2CPhCF3), −74.3 (s, 6F, (CF3)2C(OH)Ph). EI-MS
(30 eV, heating r.t.-170 °C): m/z (%) = 244 (88) [HOC(CF3)2Ph+],
205 (34) [M+ − HF2], 175 (100) [M+–CF3], 127 (95) [M+ − C2HOF4],
105 (88) [M+ − HC2F6], 77 [Ph+], 69 [CF3+]. IR (AgCl, cm−1, neat):
3604 (m), 1600 (w), 1503 (w), 1454 (m), 1366 (w), 1273 (vs), 1216
(vs), 1168 (vs), 1130 (s), 1103 (m), 1078 (s), 1037 (w), 1003 (w), 997
(w), 970 (s), 923 (s), 863 (w), 810 (w), 764 (m), 756 (m), 746 (w),
713 (vs), 701 (m), 696 (m), 683 (w), 668 (m), 546 (w), 538 (m).
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2003, 115, 1569; I. Krossing, A. Bihlmeier, I. Raabe and N. Trapp,
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Anderson and S. H. Strauss, Chem. Eur. J., 2001, 7, 503; (b) S. H.
Strauss, B. G. Nolan, B. P. Fauber, WO 00/53611, 2000; (c) F. Kita,
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H. Nagashima, J. Nie, N. V. Pavlenko and Y. Yagupolskii, J. Power
Sources, 2000, 90, 27.
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Angew. Chem., 2001, 113, 2769; A. Bösmann, G. Francio, E. Janssen,
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2697; (b) A. S. Larsen, J. D. Holbrey, F. S. Tham and C. A. Reed, J. Am.
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8 H. Suzuki, H. Naganawa and S. Tachimori, Phys. Chem. Chem. Phys.,
2003, 5, 726.
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7111; (e) T. S. Cameron, A. Decken, I. Dionne, M. Fang, I. Krossing
and J. Passmore, Chem. Eur. J., 2002, 8, 3386.
10 (a) T. S. Cameron, I. Dionne, H. D. B. Jenkins, S. Parsons, J. Passmore
and H. K. Roobottom, Inorg. Chem., 2000, 39, 2042.
11 M. Gonsior and I. Krossing, Z. Anorg. Allg. Chem., 2002, 628, 1821.
12 (a) D. L. H. Williams, Nitrosation; Cambridge University Press: New
York, 1988; (b) G. A. Olah, R. Malhotra, S. C. Narang, Nitration. Meth-
ods and Mechanisms; VCH: New York, 1989.
Crystal growth and X-ray crystallography
Crystals of 1 obtained by method 2 were grown by slowly cooling
a saturated solution in CH2Cl2 from r.t. to −24 C°. Crystals of 3
obtained from reaction (1) were grown by slowly cooling a saturated
solution in toluene from r.t. to +5 °C. Single crystals were coated
with Paratone-N oil, mounted using a glass fibre and frozen in cold
nitrogen while mounted on the goniometer. A hemisphere of data
was collected on a Bruker AXS P4/SMART 1000 diffractometer
using  and  scans with a scan width of 0.3° and 30 s exposure
times. The detector distance was 6 cm. The crystal of 3 was twinned
and the orientation matrices for two components determined
(RLATT, GEMINI).48,49 The data of the major component of 1 and 3
were reduced (SAINT)50 and corrected for absorption (SADABS).51
The structures were solved by direct methods and refined by full-
matrix least squares on F2 (SHELXTL).52 All non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were found in Fourier
difference maps and refined isotropically.
13 E. K. Kim and J. K. Kochi, J. Am. Chem. Soc., 1991, 113, 4962 and
references therein.
14 (a) H(reaction, R = C(CF3)2Ph) = −9 kJ mol−1, H(reaction, solid,
R = C(CF3)3) = −8 kJ mol−1 which are equal to the corresponding G
changes since S ≈ 0. The lattice energies used in calculation of the H
values are taken from ref. 14c or else calculated using the volume-based
equation28a,b:LiSbF6 560kJmol−1,NOSbF6 551kJmol−1,LiAl(OC(CF3)3)4
361 kJ mol−1, LiAl(OC(CF3)2Ph)4 340 kJ mol−1, NOAl(OC(CF3)3)4 360 kJ
mol−1, NOAl(OC(CF3)2Ph)4 340 kJ mol−1, NO2Al(OC(CF3)3)4 359 kJ
mol−1, NO2Al(OC(CF3)2Ph)4 339 kJ mol−1. Volumes of the salts were
obtained from the available crystallographic data, V(LiAl(OC(CF3)3)4) =
0.760 nm3, V(LiAl(OC(CF3)2Ph)4) = 0.977 nm3, V(NOAl(OC(CF3)3)4) =
0.768 nm3, V(NOAl(OC(CF3)2Ph)4) = 0.983 nm3 and those for
V(NO2Al(OC(CF3)3)4) = 0.780 nm3, V(NO2Al(OC(CF3)2Ph)4) =
0.995 nm3 obtained by subtraction of V(NO+) (= 0.010 nm3)25a and
Crystallographic data (excluding structure factors) for the
structures in this paper have been deposited with the Cambridge
Crystallographic Data Center as CCDC reference numbers 225258
and 225259. Copies of the data can be obtained, free of charge, on
application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(fax: +44-1223-336033 or deposit@ccdc.cam.ac.uk).
+
addition of V(NO2 ) (= 0.022 nm3)25a from the former values. The
lattice energies are estimated by the relationship of lattice energy to
the inverse cube root of the molecular volume28a may underestimate
the lattice energy of a substantial covalent interaction, i.e. the energy
of the NO+ Ph interaction in NOAl(OC(CF3)2Ph)4.This will increase the
enthalpy change of the metathesis reaction. The solvation energies of
the ions involved in the reaction were not determined; (b) Metathetical
reactions involving ionic materials as shown in Scheme 1 are such
that the volumes of the constituent ions (and hence for the formula
units involved) are identical for reactants and products. Since standard
See http://www.rsc.org/suppdata/dt/b4/b405715e/ for crystallo-
graphic data in CIF or other electronic format.
Acknowledgements
Acknowledgement is made to NSERC (Canada) and to the Donors
of The Petroleum Research Fund, administered by the American
Chemical Society, for partial support of this research.
14d,e
entropies of such materials are related to volume (S0 = kVm + c)
this implies that S = 0; (c) H. D. B. Jenkins, H. K. Roobottom and
J. Passmore, Inorg. Chem., 2003, 42, 2886; (d) H. D. B. Jenkins
and L. Glasser, Inorg. Chem., 2003, 42, 8702; (e) H. D. B. Jenkins
and L. Glasser, Thermochim. Acta, 2004, 414, 125.
Notes and references
1 (a) S. Brownridge, I. Krossing, J. Passmore, H. D. B. Jenkins and
H. K. Roobottom, Coord. Chem. Rev., 2000, 197, 397; (b) C. Reed,
Acc. Chem. Res., 1998, 31, 133; (c) S. H. Strauss, Chem. Rev., 1993,
93, 927; (d) E. Y.-X. Chen and T. J. Marks, Chem. Rev., 2000, 100,
15 S. V. Rosokha, S. V. Lindeman and J. K. Kochi, J. Chem. Soc., Perkin
Trans., 2002, 2, 1468.
16 S. V. Rosokha and J. K. Kochi, J. Am. Chem. Soc., 2002, 124, 5620.
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4
2 5 0 3

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17 A. J. Bondi, J. Phys. Chem., 1964, 68.
product of decomposition, characterized by X-ray, was dimeric anion
[(OC(CF3)3)3Al(-F)Al(OC(CF3)3)3]−.
18 The Raman spectrum of 1 has very intensive absorption band of the
[NO]+ due to the donor acceptor interactions of the [NO]+ and phenyl
rings of the [Al(OC(CF3)2Ph)4]−. The relative intensity of the [NO]+
absorption band in 2 of similar intensities to those of [Al(OC(CF3)3)4]−.
19 D. W. A. Sharp and J. Thorley, J. Chem. Soc., 1963, 3557.
33 The decomposition pathway of 2 involves formation [NO][PhC(CF3)2O]
(rearrangement products HOC(CF3)2PhNO (NMR, IR) are detected) and
neutral aluminium alkoxide Al(OC(CF3)2Ph)3.32c We have proposed that
[AlF(OC(CF3)2Ph)3]− and Al(OC(CF3)2Ph)3 reacts with formation of
[(PhC(CF3)2O)3Al(-F)Al(OC(CF3)2Ph)3]− and assigned weak 19F reso-
nance at −182.4 ppm, resonances  19F −74.8 and  27Al 40.2 ppm to the
fluoride bridged dimer [(PhC(CF3)2O)3Al(-F)Al(OC(CF3)2Ph)3]−. For
more details see ESI†, Stability of 1 in SO2 solution.
20 (a) J. Mason, Multinuclear NMR; Plenum Press, New York, 1987,
335–362. The 14N chemical shift of NO+ in the reference is close to
0 ppm; (b) L.-O. Andersson, J. Mason and W. van Bronswijk, J. Chem.
Soc. A, 1970, 296. The 14N resonance of [NO]+ is 347 ppm downfield to
resonance of [NH4]+ in aqueous solution. According to our data the 14
N
34 (a) 19F NMR spectrum of the volatile liquid product contains two 19F
resonances, triplet and quartet of the {Ph(CF3)C(CF2)} moiety. Accord-
ing to the proposed decomposition mechanism it could be alkene or
epoxide.1e,32a We propose that epoxide is more reactive in this environ-
ment, than the alkene (which is also very chemically active); therefore,
formation of alkene seems more feasible. The proposed decomposition
mechanism1e,32a involves formation of the aluminium alkoxide having a
strongly acidic aluminium center. It is known that fluorinated epoxides
rearranges in the presence of Lewis acids, for instance epoxides give al-
cohol in the presence of SnCl4 (see ref. 34b, p. 412), and epoxides are at-
tacked by trifluoroacetic anhydride with the formation of vicinal diols and
unsaturated allylic alcohols (see ref. 34b, p. 528, 529); (b) M. Hudlicky,
A. E. Pavlath, Chemistry of Organic Fluorine Compounds II. A Critical
Review, ACS Monograph 187, Washington, DC, 1995.
NMR resonance of [NO]+ is 366 ppm downfield of the [NH4]+ resonance
in SO2 solution.
21 J. C. Evans, H. W. Rinn, S. J. Kuhn and G. A. Olah, Inorg. Chem., 1964,
3, 857.
22 (a) C. C. Addison, Chem. Rev., 1980, 80, 21; (b) Crystal structure
of [(NO3)(NO)3)][Fe(NO3)4]2: L. J. Blackwell, E. K. Nunn and S. C.
Wallwork, J. Chem. Soc., Dalton Trans., 1975, 2068; (c) C. C. Addison,
L. J. Blackwell, B. Harrison, D. H. Jones, N. Logan, E. K. Nunn and
S. C. Wallwork, J. Chem. Soc., Chem. Commun., 1973, 347; (d) Vibra-
tional spectra of [(NO3)(NO)3)]2+: J. D. S. Goulden and D. J. Millen,
J. Chem. Soc., 1950, 2620; (e) D. J. Millen and D. Watson, J. Chem.
Soc., 1957, 1369.
23 (a) J. R. Ohlsen and J. Laane, J. Am. Chem. Soc., 1978, 100, 6948;
(b) R. D. Peacock and J. L. Wilson, J. Chem. Soc. A, 1969, 2030.
24 Raman data for NaNO3, KNO3: I. Nakagawa and J. L. Walter, J. Chem.
Phys., 1969, 51, 1389.
35 The hypothetical anion [AlF(OC(CF3)3)3]− was calculated by DFT meth-
ods. The obtained distances Al–F 1.69 Å, Al–O 1.77, 1.78 Å are close to
the corresponding distances in 3. I. Krossing and I. Raabe, Chem. Eur.
J., to be published.
36 A. Downard and T. Chivers, Eur. J. Inorg. Chem., 2001, 2193.
37 (a) I. D. Brown, Structure and Bonding in Crystals, ed. M. O’Keefe
and A. Navrotsky, Academic Press, London, 1981; (b) I. D. Brown
and D. Altermatt, Acta Crystallogr., 1985, B41, 244; (c) N. E. Brese
and M. O’Keefe, Acta Crystallogr., 1991, B41; (d) Values used:
Al(+3)–F(−1) Ro = 1.545, B = 0.37, Al(+3)–O(−2) Ro = 1.62, B = 0.37,
C(+4)–F(−1) Ro = 1.32, B = 0.37, Li(+1)–F(−1) Ro = 1.36, B = 0.37,
Li(+1)–O(−2) Ro = 1.466, B = 0.37.
38 A. G. Avent, W.-Y. Chen, C. Eaborn, I. B. Gorrel, P. B. Hitchcock and
J. D. Smith, Organometallics, 1996, 15, 4343.
39 H. Hatop, M. Schiefer, H. W. Roesky, R. Herbst-Irmer and T. Labahn,
Organometallics, 2001, 20, 2643.
40 H. Plenio and R. Diodone, J. Am. Chem. Soc., 1996, 118, 356.
41 D. Stalke and K. H. Whitmire, J. Chem. Soc., Chem. Commun., 1990,
833.
42 D. Stalke, U. Klingebiel and G. M. Sheldrick, Chem. Ber., 1988, 121,
1457.
25 IR spectrum of LiNO3 (this work) is identical to IR spectrum of our solid;
14N NMR spectrum of the product in D2O exhibit 14N resonance 14N
−5.3 ppm close to resonance of [NO3]− anion.
26 I. Krossing, H. Brands, R. Feuerhake and S. Koenig, J. Fluorine Chem.,
2001, 112, 83.
27 V((NO2)Al(OC(CF3)3)4) = 0.780 nm3, ULatt((NO2)Al(OC(CF3)3)4) =
359 kJ mol−1.
28 (a) H. D. B. Jenkins, H. K. Roobottom, J. Passmore and L. Glasser,
Inorg. Chem., 1999, 38, 3609; (b) H. D. B. Jenkins, H. K. Roobottom
and J. Passmore, Inorg. Chem., 2003, 42, 2886.
29 L. V. Gurvich, I. V. Veyts, C. B. Alcock, Thermodynamic Properties
of Individual Substances; Hemisphere Publishing Corporation, NY,
1989. The used values: H°ƒ298.15 (N2O3(g)) = 83.3 kJ mol−1, H°ƒ298.15
(N2O3(l)) = 49.4 kJ mol−1, H°ƒ298.15 (NO+(g)) = 990.3 kJ mol−1,
H°ƒ298.15 (N2O(g)) = 82.0 kJ mol−1, G°ƒ298.15(N2O (g)) = 104.20 kJ
−
−
mol−1, H°ƒ298.15 (NO3 (g)) = H°ƒ0(NO3 (g)) + RT = −307.1 kJ mol−1
−
and H°ƒ0 (NO3 (g)) = −309.6 kJ mol−1, H°ƒ298.15 (Li+(g)) = 685.7
kJ mol−1, H°ƒ298.15 (LiNO3 (s)) = −483.2 kJ mol−1, H°ƒ298.15
+
+
(NO2 (g)) = H°ƒ0 (NO2 (g)) + RT = 982.4 kJ mol−1, H°ƒ0
43 (a) B. Neumüller, Coord. Chem. Rev., 1997, 158, 69; (b) M. Ferbinteanu,
H. W. Roesky, F. Cimpoesu, M. Atanasov, S. Ko1pke and R. Herbst-
Irmer, Inorg. Chem., 2001, 40, 4947.
44 (a) N. Herron, R. L. Harlow and D. L. Thorn, Inorg. Chem., 1993, 32,
2985; (b) N. Herron, D. L. Thorn, R. L. Harlow and F. Davidson, J. Am.
Chem. Soc., 1993, 115, 3028.
+
(NO2 (g)) = 979.9 kJ mol−1, H°ƒ298.15 (NO2) = 33.5 kJ mol−1, H°ƒ298.15
(N2O4(l)) = −19.037 kJ mol−1, H°ƒ298.15 (N2O4(g)) = 9.6 kJ mol−1,
H°ƒ298.15 (NO(g)) = 90.3 kJ mol−1, G°ƒ298.15 (NO(g)) = 86.6 kJ
mol−1, H°ƒ298.15 (NO2(g)) = 33.5 kJ mol−1, G°ƒ298.15 (NO2(g)) =
51.31 kJ mol−1.
30 (a) C.-C. Chao and J. H. Lunsford, J. Am. Chem. Soc., 1971, 93, 71;
(b) C.-C. Chao and J. H. Lunsford, J. Am. Chem. Soc., 1971, 93, 6794.
31 (a) R. L. Klimisch, J. Larson, The Catalytic Chemistry of Nitrogen
Oxides; Plenum Press, New York, 1975; (b) S. Jagner and N.-G.
Vannerberg, Acta. Chem. Scand., 1967, 21, 1183; (c) J. A. Kaduk and
J. A. Ibers, Inorg. Chem., 1975, 14, 3070; (d) S. Bhaduri, B. F. G.
Johnson, A. Pickard, P. L. Raithby, G. M. Sheldrick and C. I. Zuccaro,
J. Chem. Soc., Chem. Commun., 1977, 354.
45 The 19F resonance of 3 was detected in the –CF3 group region. The
resonance of F1, located between two quadrupole nuclei Li and Al,
was undetected. For comparison, the 19F resonance (sextet) of [AlF4]−
was reported at −194.2 ppm43b or at −30 ppm.44b It was noticed that as
the concentration of the [AlF4]− was raised the 19F resonance began to
broaden due to fluorine ion exchange processes.
46 N. Kuhn, H. Lanfermann and P. Schmitz, Liebigs Ann. Chem., 1987,
727.
32 (a) I. Krossing, J. Chem. Soc., Dalton Trans., 2002, 500; (b) I. Krossing
and I. Raabe, Angew. Chem., 2001, 113, 4544; I. Krossing and I. Raabe,
Angew. Chem. Int. Ed. Engl., 2001, 40, 4406; (c) The proposed32a de-
composition mechanism of the salt of (P5)[Al(OC(CF3)3)4] involved the
formation of a tight ion pair (P5)[Al(OC(CF3)3)4] followed by liberation
of (P5)+[OC(CF3)3]− and the very strong Lewis acidAl(OC(CF3)3)3 which
reacted with the anion [Al(OC(CF3)3)4]− with fluoride ion abstraction
giving [AlF(OC(CF3)3)3]− and (C4F8O)Al(OC(CF3)3)3. The final
47 G. M. Begun and A. C. Rutexberg, Inorg. Chem., 1967, 6, 2212.
48 GEMINI 1.0, 1999, Bruker AXS, Inc., Madison, WI, USA.
49 RLATT 2.72, 1999, Bruker AXS, Inc., Madison, WI, USA.
50 SAINT 6.02, 1997–1999, Bruker AXS, Inc., Madison, WI, USA.
51 SADABS George Sheldrick, 1999, Bruker AXS, Inc., Madison, WI,
USA.
52 SHELXTL 5.1, George Sheldrick, 1997, BrukerAXS, Inc., Madison, WI,
USA.
2 5 0 4
D a l t o n T r a n s . , 2 0 0 4 , 2 4 9 6 – 2 5 0 4