The N,N-bis(terphenyl)aminophosphenium cation - A sensitive probe for interactions with different anions

Article abstract of DOI:10.1002/ejic.201100978

A series of salts that contain the terphenyl-substitutedbis(amino) phosphenium cation with different anions (F^-,Cl^-, [CF ₃CO₂]^-, [CF₃SO₃] ^-, [B(C₆F₅)₄]^-, [GaCl₄]^-, [SbF₆]^-, [Al{OCH(CF ₃)₂}₄]^- and [CHB₁₁H ₅Br₆]^-) has been prepared by different synthetic protocols. All of the products have been characterised spectroscopically and by single-crystal X-ray diffraction studies. A detailed analysis of the interionic interactions and their influence on the molecular structure of the phosphenium cation reveals a strong dependence on the capability of the anion to enter the pocket generated by the bulky terphenyl substituents. Copyright

Full text of DOI:10.1002/ejic.201100978

FULL PAPER
DOI: 10.1002/ejic.201100978
The N,N-Bis(terphenyl)aminophosphenium Cation – A Sensitive Probe for
Interactions with Different Anions
Fabian Reiß,[a] Axel Schulz,*[a,b] and Alexander Villinger[a]
Keywords: Sensors / Cations / Anions / Phosphorus / Weakly coordinating anions / Bonding
A series of salts that contain the terphenyl-substituted
bis(amino)phosphenium cation with different anions (F–,
Cl–, [CF3CO2]–, [CF3SO3]–, [B(C6F5)4]–, [GaCl4]–, [SbF6]–,
[Al{OCH(CF3)2}4]– and [CHB11H5Br6]–) has been prepared by
different synthetic protocols. All of the products have been
characterised spectroscopically and by single-crystal X-ray
diffraction studies. A detailed analysis of the interionic inter-
actions and their influence on the molecular structure of the
phosphenium cation reveals a strong dependence on the
capability of the anion to enter the pocket generated by the
bulky terphenyl substituents.
Niecke and Kröher showed that the electrophilic attack
of AlCl3 on the P=N double bond of the amino(imino)-
phosphane R2N–P=NR (R = Me3Si) generates the internal
salt R2N–P(+)– N(Al(–)Cl3)R with a formal positive charge
at the phosphorus atom and a negative charge at the alu-
minium atom.[7] This internal salt readily eliminates Me3Si–
Introduction
The first dicoordinate phosphorus cation, observed in
phosphamethine cyanines, was reported by Dimroth and
Hoffmann in 1964.[1] The term “phosphenium ion” was in-
troduced to indicate a positive charge at the two-coordinate
phosphorus centre with a formally vacant 3p orbital.[2] Pho-
sphenium cations are related to carbenes of the type R1–
C–R2 where electronically isovalent P+ replaces the central
carbon atom. Carbenes are best stabilised when R1 and R2
are atoms or groups such as NR2, which can serve as
π-electron donors to the carbon atom.[3] The same holds
true for electronically isovalent phosphenium analogs
(Scheme 1).
Parry et al. reported the first examples of acyclic phos-
phenium ions [(Me2N)2P]+ and [(Me2N)(Cl)P]+, which were
obtained by chloride abstraction from the corresponding
amino(chloro)phosphanes by employing Lewis acids such
as ECl3 (E = Fe, Al, Ga).[4] Structural data for acyclic phos-
phenium ions are still limited to only a few amino-substi-
tuted examples: [(iPr2N)2P]+[X]– (X = [AlCl4]–, [GaCl4]–,
[B(C6F5)4]–).[5,6]
Cl upon heating to give a four-membered (Cl2)Al(–)
–
N(Me3Si)–P(+)–N(SiMe3) heterocycle. Moreover, it was
shown that the reaction of the chloro(imino)phosphane
2,4,6-tBu3C6H2–N=P–Cl with AlCl3 led to the stable salt
[2,4,6-tBu3C6H2–NϵP]+[AlCl4]–, which bears a formal
PϵN triple bond,[8] instead of the expected phosphanylium
adduct, 2,4,6-tBu3C6H2–N(Al(–)Cl3)–P(+)–Cl.
The only known aryl-substituted bis(amino)phosphen-
ium cation 3 (E = Al, Scheme 2) was introduced by
Niecke[9] and coworkers and further studied by Burford
et al.[10] As shown in Scheme 2, the phosphadiazonium cat-
ion [Mes*NP]+ (2) reacts quantitatively with Mes*NH2
–
(Mes* = 2,4,6-tri-tert-butylphenyl) to yield ECl4 salts with
the bis(amino)phosphenium cation (Mes*3). The solid-state
structures of Mes*3[GaCl4] and Mes*3[AlCl4] have been
Scheme 1. Stabilisation of phosphenium ions by π-electron donors in [R2N–P–NR2]+.
confirmed by X-ray crystallography and the structural pa-
rameters of the cation are essentially identical.
[a] Institut für Chemie, Universität Rostock,
Albert-Einstein-Str. 3a, 18059 Rostock, Germany
Fax: +49-381-498-6381
Salts that contain a five-membered heterocyclic cation
with a formal bis(amino)phosphenium fragment (R2N–
P(+)–NR2) are called 1,3,2-diazaphospholenium ions.[11,12]
They are isoelectronic with imidazoyl carbenes,[13] stabilised
by similar electronic factors and can be obtained by chlo-
E-mail: axel.schulz@uni-rostock.de
[b] Leibniz Institut für Katalyse,
Albert-Einstein-Str. 29a, 18059 Rostock, Germany
Fax: +49-381/498-6381
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201100978.
Eur. J. Inorg. Chem. 2012, 261–271
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
261

F. Reiß, A. Schulz, A. Villinger
FULL PAPER
we report the anion influence that results in small differ-
ences in the solid-state structures but may have an influence
on physical properties such as melting points and NMR
chemical shifts.
Results and Discussion
Scheme 2. Synthesis of Mes*3[ECl4] (E = Al, Ga).[9,10]
Synthesis and Spectroscopic Studies
Convenient synthetic routes[2,3,5,6] to salts that bear Ter3
include salt-elimination reactions of (TerNH)2P–Cl with
Ag[X] (X = weakly coordinating anion,[20] Scheme 4), halo-
gen abstraction by a Lewis acid such as GaCl3 or SbCl5
(Scheme 5) or protonation of imino(amino)phosphane
(TerN(H)P=NTer, Scheme 6). A synthetic protocol analo-
gous to the generation of Mes*3 salts illustrated in
Scheme 2 cannot be applied to obtain Ter3 salts as the Ter–
N=P–Cl starting material is not accessible.
ride abstraction with Lewis acids in 2-chloro-1,3,2-diaza-
phospholenes (Scheme 3).[12] Chloride abstraction was also
successfully applied in the isolation of salts that bear cyclo-
1,3-diphospha-2,4-diazenium ions, which can also be re-
garded as carbene analogs (Scheme 3).[14]
Scheme 3. Synthesis of phosphorus carbene analogs by chloride ab-
straction. (i) X = (CH)2 1,3,2-diazaphospholenium ion (R = alkyl,
aryl, E = Al, Ga); (ii) X = P–Cl chlorocyclo-1,3-diphospha-2,4-
diazenium ions (R = Ter, E = Ga).[12,14]
Scheme 4. Synthesis of Ter3[X] by salt elimination (X = [CF3-
CO2]–, [CF3SO3]–, [B(C6F5)4]–, [Al{OCH(CF3)2}4]–, [CHB11H5-
Br6]– and [SbF6]–).
The structure and bonding of bis(amino)phosphenium
ions has been intensively studied.[2b,9,10] In solution, 31P
NMR spectroscopy is a powerful tool for the identification
of phosphenium ions. As might be anticipated from the low
coordination number and the presence of a formal positive
charge at phosphorus, the 31P chemical shifts of phosphen-
ium ions are rather deshielded and fall in the range 100–
520 ppm.[2b] For instance in [(Me2N)(tBu)P]+, a strongly de-
shielded 31P chemical shift is observed at 513 ppm,[15] which
can be ascribed to the inability of the tBu group to donate
π electrons. Steric effects also play a role in determining
the 31P chemical shifts. Interestingly, 31P chemical shifts of
bis(amido)-substituted cations increase with increasing li-
gand size.[2b] This trend has been interpreted on the basis
of progressive twisting of the R2N groups with respect to
the P+ centre, which reduces the N(2p)–P(3p) overlap with
increasing steric strain.[15]
Scheme 5. Synthesis of Ter3[X] by halide abstraction ([LA-Hal] =
[GaCl4]–).
Scheme 6. Synthesis of Ter3[X] salts by protonation of terphenyl-
substituted imino(amino)phosphane (X
=
Cl–, [CF3CO2]–,
[CF3SO3]–, [B(C6F5)4]–).[26]
Silver salts were usually used for the salt-elimination re-
actions, which were carried out either in toluene or CH2Cl2
Cation–anion interactions that involve phosphenium at ambient temperatures. The formation of Ter3 was easily
ions have previously been investigated in some detail.[3] Bur- followed by UV/Vis due to its prominent orange colour
ford et al. reported the anionic protection of phosphenium (Table 1). The application of this method was restricted to
ions in solution,[6] Kee et al. described phosphenium–tri- the synthesis of salts that contain the weakly coordinating
flate interactions[16] and Dahl investigated equilibria that anions [CF3CO2]–, [CF3SO3]–, [B(C6F5)4]–, [Al{OCH-
involve covalent and ionic phosphenium triflates.[17]
(CF3)2}4]– and [CHB11H5Br6]–. Interestingly, although this
To the best of our knowledge, the influence of the anion reaction works well with Ag[B(C6F5)4], no reaction was ob-
with respect to the cation structure and physical properties served with the nonfluorinated species, Ag[B(C6H5)4]. In
has not been studied comprehensively. As a model system, the cases of the fluoridometallate anions [SbF6]– and
we have chosen the N,N-bis[2,6-bis(2,4,6-trimethylphenyl)- [BF4]–, the synthesis was not successful even when tempera-
phenyl]aminophosphenium ion ([(TerNH)2P]+, Ter3, tures below –80 °C were applied. Initially, the formation of
Schemes 4–6) as its salts are usually easily obtained and al- Ter3 was indicated by an orange colour, which quickly di-
low hydrogen bonding despite the sterically demanding ter- minished when the temperature was raised to ambient tem-
phenyl group. To gain further insight into the influence of peratures. Only a few orange crystals of Ter3[SbF6] were
the anion we prepared Ter3 with the following formal isolated in addition to the major product, which was iden-
counterions: F–, Cl–, [CF3CO2]–,[18] [CF3SO3]–,[19] [B- tified as 2,6-bis(2,4,6-trimethylphenyl)anilinium hexafluo-
(C6F5)4]–,[20,21,22] [GaCl4]–,[10,20,23] [SbF6]–,[24] [Al{OCH- roantimonate, [TerNH3][SbF6].[27a] The synthesis of Ter3-
(CF3)2}4]– [20] and the carborate [CHB11H5Br6]–.[20,25] Here, [BF4] did not proceed due to a rapid Cl–F exchange reac-
262
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The N,N-Bis(terphenyl)aminophosphenium Cation
Table 1. Characterisation data [decomposition temperature (Tdec), 31P NMR, 1H NMR, IR (νNH and νPN) and UV/Vis spectroscopic
data] for Ter3[X] (X = F–, Cl–, [CF3CO2]–, [CF3SO3]–, [B(C6F5)4]–, [GaCl4]–, [SbF6]–, [Al{OCH(CF3)2}4]– and [CHB11H5Br6]–) with
TerN(H)PNTer and Mes*3[Y] (Y = [GaCl4]–, [CF3SO3]–) for comparison.
Tdec 31P{1H} NMR 1H (NH) NMR
νNH
νPN
Vis
[nm]
UV
[nm]
[°C]
[ppm]
[ppm]
[cm–1]
[cm–1]
TerN(H)PNTer
Ter3F
311
225
265[e]
190[f]
255
244
215
–
273
225
152
–
278.0
119.7[a]
129.9
116.7
261.0
249.1
250.0
249.0
249.0
249.6
272.0
279.7
6.34
3.79
4.08
4.38
9.67
7.31
7.38
7.39
7.2
3364
3289
3292
3285
3298
3234
3287
3261
–
3255
3173
3175
–
1412
1418
1419
1422
1426
1419
1416
–
1426
1428
1419
–
406
–
–
336
–
–
289
292
297
290
292
296
–
247
249
248
250
246
260
255
–
3334
3309
3314
3341
–
3333
–
3319
3330
–
Ter3Cl
Ter3[CF3CO2]
Ter3[CF3SO3]
Ter3[B(C6F5)4]
Ter3[GaCl4]
–
–
438
422
438
–
435
435
–
363
358
361
–
360
358
–
Ter3[SbF6][d]
–
Ter3[Al{OCH(CF3)2}4]
Ter3[CHB11H5Br6]
Mes*3[GaCl4][b]
Mes*3[CF3SO3][c]
297
296
–
246
245
–
7.41
9.94
11.6
–
–
–
–
–
[a] Doublet due to 31P,19F coupling. [b] Taken from ref.[11] [c] Taken from ref.[9e] [d] Characterised by X-ray and NMR spectroscopic
studies because of fast decomposition. [e] Tdec = m.p. [f] M.p. 177 °C.
tion (Scheme 7) even at low temperatures, although Ter3 strong excitation, which is not observed for the covalently
was observed initially. Ter3 is a stronger Lewis acid than bound species, several other πTerǞπ*Ter excitations were ob-
BF3, which is why fluoride-ion exchange was observed.
served. In the IR spectra, the P–N stretching mode, which
is influenced by the substituent, structural situation around
the NPN unit and the extent of hydrogen bonding, was typ-
ically found from 1400–1500 cm–1 (cf. [Mes*NP]+[GaCl4]–
1494, Mes*N=P–Cl 1437 cm–1).[28]
Scheme 7. Reaction of Ter3Cl with Ag[BF4].
Ter3[X] were all astonishingly thermally stable and
moisture sensitive but stable under an argon atmosphere
over a long period as solids and in solvents such as CH2Cl2,
benzene or toluene at ambient temperature. They could be
prepared in bulk and were stable when stored in sealed
tubes. Although covalently bound Ter3[X] (X = F–, Cl–,
[CF3CO2]–) could be handled in air for a short time, the
Ter3[X] salts all decomposed quickly as indicated by the
colour change from orange to colourless. For example, it
was shown that Ter3[Al{OCH(CF3)2}4] slowly hydrolysed
over a period of 7 d in the freezer (–25 °C) to yield the in-
ternal salt (TerNH)2P(+)(H)–O–Al(–)[OCH(CF3)2]3.[27b]
Apart from Ter3Cl and Ter3[CF3CO2], for which true
melting points were found (265 and 177 °C, respectively),
differential scanning calorimetry (DSC) displayed only de-
composition points ranging between 190 °C (Ter3-
[CF3CO2]) and 273 °C (Ter3[Al{OCH(CF3)2}4]). It is inter-
esting to note that Mes*3[GaCl4] is significantly less ther-
mally stable than its terphenyl-substituted counterpart (152
vs. 215 °C). It can be assumed that the terphenyl group pro-
vides better kinetic protection.
Halide abstraction was attempted with GaCl3 and SbCl5
starting from Ter3Cl as well as with SbF5 in the reaction
with Ter3F. Only the reaction with GaCl3 gave good yields
of the desired product, Ter3[GaCl4], whereas, for SbF5 and
SbCl5, only Ter–N(H)–PF2 and Ter–N(H)–PCl2, respec-
tively, were identified as the major products. The proton-
ation reaction of terphenyl-substituted imino(amino)phos-
phane was successfully applied to the preparation of
Ter3[X] (X = Cl–, [CF3CO2]–, [CF3SO3]–, [B(C6F5)4]–). A
large excess of acid during protonation or hydrolysis led to
the formation of the ammonium salts [TerNH3][X] for all
Ter3[X].
Very pure Ter3Cl was obtained in the silyl ether elimi-
nation reaction of Ter3[X] (X = [CF3CO2]– and [CF3SO3]–)
with Me3SiCl. Here the driving force was the formation of
Me3SiOC(O)CF3 and Me3SiOS(O2)CF3, respectively.
Ter3[Cl] is not directly accessible from TerNH2 and PCl3 in
the presence of bases, such as Et3N, 1,8-diazabicyclo[5.4.0]-
undec-7-ene and nBuLi, due to the formation of byproducts
(e.g. TerN(H)–PCl2, [TerN–PCl]2, TerN(H)–P=N–Ter).
Thus the best way to Ter3Cl was through TerN(H)–PCl2
X-ray studies (see below) and calculations revealed domi-
and 2 equiv. of Ter–NHLi, which led to TerN(H)–P=N–Ter nant polar-covalent bonding in Ter3[X] (X = F–, Cl–,
(60% yield). Protonation with HCl yielded Ter3[Cl] [CF3CO2]–) and ion-pair formation in the other species.
(Scheme 6).
Solution NMR spectroscopy displayed a similar picture. Al-
Ter3[X] were all characterised by elemental analysis, 31P though a strong upfield shift was observed for Ter3[X] (X =
and 1H NMR, IR and UV/Vis spectroscopy and single- F–, Cl–, [CF3CO2]–) in the H (3.8–4.4 ppm) and 31P NMR
1
crystal X-ray structure analysis. Table 1 summarises the spectra (117–130 ppm), for the other species, except
spectroscopic data.
Ter3[CF3SO3], the corresponding resonances are found in
According to UV/Vis spectroscopy, all of the ionic the downfield region expected for phosphenium ions[2b] at
1
31P
Ter3[X] species are orange at ambient temperatures, which
δ
= 249–250 and δ H = 7.2–7.4 ppm. As almost the same
is due to an nNPNǞπNPN* excitation. In addition to this chemical shifts are observed for all of the ionic species, it
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263

F. Reiß, A. Schulz, A. Villinger
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can be assumed that solvated ions are present in solution,
with the exception of Ter3[CF3SO3] for which ion pairing
1
was indicated. In the H NMR spectrum of Ter3[CF3SO3]
a signal is found at 9.67 ppm, which can be attributed to
strong NH···O(O2)SCF3 hydrogen bonds that are responsi-
ble for the ion pairing. In addition, the considerable down-
field shift in the 31P NMR spectrum (261 vs. 250 ppm,
Table 1) supports this argument along with the X-ray data
for the solid-state structure. In contrast to Ter3[GaCl4],
which forms separated ions in solution, analogous Mes*3-
[GaCl4] forms ion pairs as indicated by the 1H and 31P
NMR spectra (Table 1, δ1H = 7.38 vs. 9.94 ppm). As shown
below, stronger hydrogen bonds were observed in Mes*3-
[GaCl4] than Ter3[GaCl4]. In agreement with ion pairing
in Ter3[CF3SO3], Mes*3[CF3SO3] displays an even stronger
downfield shift (δ1H = 9.67 vs. 11.60 ppm).
Structural Elucidation
Crystals suitable for single-crystal X-ray diffraction stud-
ies of Ter3[X] ([X] = F–, Cl–, [CF3CO2]–, [CF3SO3]–,
[B(C6F5)4]–, [GaCl4]–, [SbF6]–, [Al{OCH(CF3)2}4]– and
[CHB11H5Br6]–), Mes*3[GaCl4] and (TerNH)2P(H)OAl-
[OCH(CF3)2]3.[27b] were obtained by crystallisation of satu-
rated solutions at low temperature. We have abstained from
a detailed discussion of the structure of TerN(H)PNTer due
to a strong disorder problem.
Although Ter3[B(C6F5)4] crystallised as a solvate with
one molecule of CH2Cl2 per formula unit, Ter3[Al-
{OCH(CF3)2}4] with 0.5 molecules of fluorobenzene and
Ter3[CHB11H5Br6] with 1.5 molecules of benzene, the other
Ter3[X] compounds crystallised without the inclusion of
solvent. The molecular structures of all Ter3[X] species and
Mes*3[GaCl4] and (TerNH)2P(H)OAl[OCH(CF3)2]3 are
shown in Figures 1, 2, 3 and S1 (see Supporting Infor-
mation). Selected bond lengths and angles are summarised
in Table 2 together with the previously reported data for
Mes*3[ECl4] (E = Al, Ga).[9,10] We have repeated the struc-
tural analysis of Mes*3[GaCl4] to get a consistent set of
data of comparable quality.
Figure 1. ORTEP drawing of covalently bound Ter3[X] species (X
= F–, Cl–, [CF3CO2]–). Thermal ellipsoids with 30% probability at
173 K (hydrogen atoms of the terphenyl group are omitted).
For all Ter3[X] species, the central phenyl rings of the
terphenyl group attached to the nitrogen atom try to form
an almost orthogonal arrangement (torsion angles between
54–90°, Table 2) that forms a pocket generated by four aryl
substituents (in 2- and 6-positions), in which the N(H)-
PN(H) moiety is embedded and sterically protected (Fig-
ure 2). Thus dimerisation of e.g. TerN(H)PNTer and the
formation of cyclodiphosphadiazanes is impossible. The
N(H)PN(H) moiety is not coplanar to the central aryl rings
of the terphenyl group located but twisted (e.g. the C1aryl
–
C2aryl–N–P dihedral angles in Ter3[GaCl4] are between 29
and 38°). Thus, delocalisation of the NPN π-electron den-
sity into the central aryl substituents is limited.
As displayed in Table 2 and Figure 1, the phosphorus
atom adopts a trigonal pyramidal environment in all of the
covalently bound Ter3[X] (X = F–, Cl–, [CF3CO2]–) species.
In all other species the structure consists of separated Figure 2. Hydrogen bonds in R3[X] (R = Ter, Mes*).
264 Eur. J. Inorg. Chem. 2012, 261–271
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The N,N-Bis(terphenyl)aminophosphenium Cation
1.628 Å) of the ionic Ter3[X] species indicate partial double
bond character and lie in the expected range for ami-
no(imino)phosphanes, for example P=N 1.545(6) and P–N
1.632(6) Å in MeN(H)–P=N–Mes* [Σrcov(P–N) = 1.82 and
Σrcov(P=N) = 1.62 Å, where rcov = covalent radii].[9d,29,30]
Partial P–N double bond character due to hyperconjuga-
tion can be discussed for the covalently bound Ter3[X] spe-
cies.[31] As expected for the covalently bound Ter3[X] spe-
cies, small N–P–N angles between 91 and 95° were ob-
served, whereas significantly larger N–P–N angles were
measured for the ionic Ter3[X] compounds (N–P–N 96–
100°), except for Ter3[CF3SO3] in which a larger angle was
measured (104.9°).
Three types of interaction were found between the formal
fragments [Ter3]+ and [X]– in Ter3[X]: (i) polar covalent
bonding with the phosphorus atom of [Ter3]+ was found
for small nucleophilic anions such as F–, Cl–, and [CF3-
CO2]– (Figure 1), (ii) NH···Y hydrogen bonding (Y = F, Cl,
O, where Y is the donor atom of [X]–) was found for me-
dium sized anions that are small enough to enter the pocket
generated by the terphenyl groups ([CF3SO3]–) and larger
complex anions ([B(C6F5)4]–, [GaCl4]–) that are capable of
partially entering the terphenyl pocket (Figure 2), (iii) weak
van der Waals interactions with peripheral H–Caryl atoms
were observed for large, weakly coordinating anions
([Al{OCH(CF3)2}4]–, [SbF6]– and [CHB11H5Br6]–), which
are simply too big to gain access to the terphenyl pocket
and thus the formation of hydrogen bonds is impossible
(Figure 3, Scheme 8).
Figure 3. Weak, interionic van der Waals interactions in Ter3[X].
Only the interactions of one ion pair are depicted.
[Ter3]+ and [X]– ions with several different interionic con-
As depicted in Scheme 8, the P–Y distances (where Y is
tacts (see below). Here, both the nitrogen atoms and the the atom of [X]– closest to P) are found in the range be-
dicoordinated phosphorus atom of the N(H)PN(H) moiety tween 1.634 (Y = F, Ter3F) and 2.008 Å (Y = Cl, Ter3Cl)
sit in a trigonal planar environment with P–N bond lengths for the covalent species with a typical P–Y single bond (cf.
ranging from 1.619–1.635 Å, which are significantly shorter d(P–F) = 1.634(3) vs. Σrcov = 1.66 Å; d(P–Cl) = 2.008(2) vs.
than those found in the covalently bound Ter3[X] species Σrcov = 2.04 Å; d(P–O1) = 1.789(2) vs. Σrcov = 1.72 Å),
[cf. Ter3[F], P–N 1.704(6) and 1.663(1) Å, Table 2]. In 3.833 (Y = F, Ter3[B(C6F5)4]) to 4.455 Å (Y = Cl, Ter3-
Ter3[CF3SO3], a slightly shorter P–N bond length was [GaCl4]) for species with strong NH···Y hydrogen bonds,
found [1.609(3) Å] along with a considerably larger N–P–N and 5.478 (Y = F, Ter3[SbF6]) and 6.445 (Y = Br,
angle, which can be attributed to strong NH···O hydrogen Ter3[CHB11H5Br6]) for weak van der Waals interaction
bonds (see below). The short P–N bond lengths (average with peripheral HTer atoms.
Table 2. Selected structural data for Ter3[X] (X = F–, Cl–, [CF3CO2]–, [CF3SO3]–, [B(C6F5)4]–, [GaCl4]–, [SbF6]–, [Al{OCH(CF3)2}4]– and
[CHB11H5Br6]–) and Mes*3[ECl4] (E = Ga, Al) and (TerNH)2P(H)OAl[OCH(CF3)2]3 for comparison.
N1–P [Å]
N2–P [Å]
N1–C1 [Å]
ЄN–P–N [°]
τaryl [°][c]
Ter3F
1.704(6)
1.697(2)
1.675(2)
1.623(3)
1.630(3)
1.635(1)
1.635(2)
1.628(3)
1.619(3)
1.625(3)
1.625(2)
1.601(3)
1.611
1.663(1)
1.591(2)
1.687(2)
1.609(3)
1.623(3)
1.626(1)
1.635(2)
1.635(3)
1.637(3)
1.630(3)
1.627(2)
1.601(3)
1.611
1.38(2)
91.6(4)
94.6(1)
94.84(9)
104.9(1)
99.6(2)
99.61(6)
98.0(2)
98.5(2)
96.9(2)
96.3(1)
115.09(9)
105.2(2)
103.7
54.3
56.3
65.4
89.3
87.4
74.5
79.3
89.9
89.9
69.4
35.3
37.0
–
Ter3Cl
1.412(2)
1.423(3)
1.443(4)
1.440(4)
1.428(2)
1.426(3)
1.431(4)
1.435(4)
1.426(4)
1.435(2)
1.469(4)
1.474
Ter3[CF3CO2]
Ter3[CF3SO3]
Ter3[B(C6F5)4]
Ter3[GaCl4]
Ter3[SbF6]
Ter3[Al{OCH(CF3)2}4][a]
Ter3[CHB11H5Br6]
(TerNH)2P(H)OAl[OCH(CF3)2]3
Mes*3[GaCl4]
[b]
Mes*3[AlCl4]
[a] Two independent molecules. [b] No standard deviations available, see ref.[9] [c] τaryl = torsion angle between the two planes composed
of the central aryl of the terphenyl or Mes* group.
Eur. J. Inorg. Chem. 2012, 261–271
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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265

F. Reiß, A. Schulz, A. Villinger
FULL PAPER
Scheme 8. Interactions between [Ter3]+ and [X]– fragments.
Although the PN distances exhibit only insignificant de- *3[GaCl4] two Cl atoms form one N–H···Cl bond each in
viations for all ionic Ter3[X] species (besides slightly smaller a bidentate fashion, which are identical due to symmetry
values for Ter3[CF3SO3]), the N–P–N angle is a sensitive (3.430 Å, Figure 2). The shorter N–H···Cl distances and the
measure for the magnitude of NH···Y hydrogen bonds (Y increase of the N–P–N angle (Table 2) indicate stronger hy-
= halogen, O). The stronger these hydrogen bonds, the drogen bonds in Mes*3[GaCl4]. In Ter3[GaCl4], the ter-
larger the N–P–N angle e.g. 96.3(1)° in Ter3[CHB11H5Br6] phenyl pocket provides less space compared to the situation
with no hydrogen bonds vs. 104.9(1)° in Ter3[CF3SO3] with in Mes*3[GaCl4] and only one Cl atom fits into the pocket.
the strongest hydrogen bond found in the series. The com- The strong N–H···Cl–GaCl3 hydrogen bond in Ter3[GaCl4]
parison between Ter3[GaCl4] (99.6°) and Mes*3[GaCl4] is also manifested by considerable Ga–Cl bond lengthening
(105.2°) supports this argument as significantly shorter for the Cl1 atom that is involved in the hydrogen bond [cf.
NH···Cl contacts are found in Mes*3[GaCl4] (see below, Ga1–Cl1 2.1928(4) vs. Ga1–Cl3 2.1632(5), Ga1–Cl4
Table 2, Figure 2), which might be the reason for their dif- 2.1652(4), Ga1–Cl2 2.1743(4) Å, Figure 2]. Also in Mes*3-
ferent behaviour in solution (ion paring vs. solvated ions, [GaCl4], two significantly different Ga–Cl bond lengths are
see above).
found for Ga1–Cl1 2.155(1) and Ga1–Cl2 2.1872(9) Å,
The hydrogen bond may be generally considered as a where Cl2 and Cl2Ј are also involved in hydrogen bonds.
three-centre four-electron interaction that stabilises and is The essence of this comparison is the fact that the Mes*
associated with spectroscopic and structure-defining ef- group provides more steric protection for the α-atom at-
fects.[32] Their classification into weak, strong and very tached to the Mes* group (e.g. a larger Tolman angle for
strong is somewhat subjective. However, it is their direction- Mes* 228° vs. Ter 206°),[33] whereas the terphenyl group
ality that makes hydrogen bonds important as crystal-struc- is capable of embedding a larger moiety and thus better
ture directors (Figure 2). In the three Ter3[X] species (X = protecting the β-atom such as in the N(H)PN(H) unit in
[CF3SO3]–, [B(C6F5)4]–, and [GaCl4]–) the NH···Y hydrogen R3[X] (R = Mes*, Ter) compounds.
bonds can be classified as strong as they dominate the in-
In addition to the interionic hydrogen bonds that have
terionic interaction. The strongest hydrogen bonds are been discussed, short O2···N1 (3.046) and O2···N2
found in Ter3[CF3SO3] with N···O distances of 2.746 (N1– (2.885 Å) distances are present in Ter3[CF3CO2], which
O3) and 2.830 Å (N2–O2), which result in other structural suggest intramolecular NH···O2 hydrogen bonds (Figure 1).
changes such as a larger N–P–N angle (see above). Espe-
Finally, Ter3[X] (X = [SbF6]–, [Al{OCH(CF3)2}4]– and
[34]
cially interesting are the hydrogen bonds in Ter3[B(C6F5)4] [CHB11H5Br6]–) are poorly crystalline,
which indicates
with N···F–Caryl distances of 3.075 (N1–F13) and 3.228 the presence of only very weak interionic interactions. It is
(N2–F12) Å as only one C6F5 ring of the anion is inside known that cations with C–H bonds in the presence of fluo-
the terphenyl pocket which is reminiscent of the key–lock rido-containing anions usually crystallise better, which is
principle known in biology. Due to the parallel arrange- likely to be through the formation of many assisting H–F
ment of this C6F5 ring with one aryl substituent of both contacts (e.g. [Ag(C2H4)][Al(ORF)4][35] and [H(OEt2)2]-
terphenyl groups, further weak van der Waals interactions [Al(ORF)4],[36] where RF = C(CF3)3). For all three Ter3[X]
between Caryl···F–Canion (shortest distance 3.547 Å) and species, many assisting Cmethyl–H···Y (Y = F, Br) contacts
Caryl···C–Fanion (shortest distance 3.457 Å) and weak were detected (Ͻ ΣrvdW(H···Y) = 2.9 for Y = F and 3.3 Å
C
methyl–H···F–Canion hydrogen bonds (shortest Cmethyl···F– for Y = Br, where rvdW = van der Waals radii),[37] of which
Canion 3.327 Å) can be assumed. In Ter3[GaCl4], it is inter- only a few (shortest contacts) are shown for the ion pairs
esting to compare the N–H···Cl–GaCl3 hydrogen bond and in Figure 3. However, these dispersive interactions are weak
with that in Mes*3[GaCl4] with respect to steric strain. Al- and not structure determining. Therefore, the structural pa-
though in Ter3[GaCl4] only one Cl atom forms two N– rameters of Ter3 within the framework of an ensemble of
H···Cl bonds (N1–Cl1 3.796 and N2–Cl1 3.505 Å), in Mes- large and weakly coordinating anions such as [SbF6]–,
266
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 261–271

The N,N-Bis(terphenyl)aminophosphenium Cation
[Al{OCH(CF3)2}4]– and [CHB11H5Br6]– are almost iden-
tical (Table 2).
[B(C6F5)4] and Ag[B(C6H5)4] were prepared according to modified
procedures.[43,44] 31P{1H}, 19F{1H}, 11B{1H}, 13C{1H}, 13C DEPT
and H NMR spectra were obtained with a Bruker AVANCE 250,
1
300 or 500 spectrometer and were referenced internally to the deu-
terated solvent (13C, CD2Cl2: δreference = 54 ppm, [D6]DMSO
δreference = 40 ppm) or to protic impurities in the deuterated solvent
(1H, CDHCl2: δreference = 5.31 ppm, [D5]DMSO = 2.5 ppm).
CD2Cl2 was dried with P4O10 and freshly distilled prior to use.
[D6]DMSO was dried with CaH2 and freshly distilled prior to use.
IR spectra were recorded with a Nicolet 6700 FTIR spectrometer
with a Smart Endurance ATR device. Raman spectra were re-
corded with a Bruker VERTEX 70 FTIR with RAM II FT-Raman
module equipped with a Nd:YAG laser (1064 nm). Elemental
analyses were measured with an Analysator Flash EA 1112 instru-
Conclusions
Different synthetic routes to salts that bear the N,N-bis-
(terphenyl)aminophosphenium cation (Ter3) have been
studied. Simple salt-elimination reactions of (TerNH)2P–Cl
with Ag[X] (X = weakly coordinating anion) or the proton-
ation of TerN(H)PNTer with strong acids offer a generally
applicable and economic access to Ter3[X] compounds with
a wide range of anions. Most Ter3[X] compounds were ob-
tained in good yields and purity and are suitable starting ment from Thermo Quest. MS were recorded with a Finnigan
MAT 95-XP instrument from Thermo Electron. Melting points
were measured on an EZ-Melt instrument from Stanford Research
Systems at a heating rate of 20 °C/min (clearing-points are re-
ported). DSC measurements were performed with a DSC 823e in-
strument from Mettler-Toledo (Heating rate 5 °C/min). UV/Vis
spectra were measured with a Lambda 19 instrument from Perkin–
Elmer with Lambda-SPX 1 software. Samples were measured in
CH2Cl2 at ambient temperature. Settings: Scan: 200–800 nm, Inter-
val 0.5 nm, Scan speed 120 nm/min, Smooth 1, Slit 1 nm.
materials for further synthesis.
Systematic single-crystal X-ray diffraction studies of
Ter3[X] with focus on the cation–anion interaction revealed
that, depending on the size of the anion, the pocket formed
by the terphenyl can be entered to some degree, which re-
sulted in strong, structure-defining interionic hydrogen
bonds ([X]– = [CF3SO3]–, [B(C6F5)4]– and [GaCl4]–). For the
ions ([SbF6]–, [Al{OCH(CF3)2}4]– and [CHB11H5Br6]–) that
are too big to fit into the terphenyl pocket, many Cmethyl
–
Ter3F: To
a stirred suspension of (TerNH)2PCl (0.500 g,
H···Y (Y = F, Br) contacts were detected, which can be
described as weak dispersive interactions that are not struc-
ture determining.
Solution NMR spectroscopic data suggest the dissoci-
ation of ionic Ter3[X] in contrast to analogous Mes* spe-
cies, in which ion pairing is observed. This different solution
behaviour can be attributed to the better steric protection
provided by the terphenyl substituent, which prevents
0.69 mmol) in CH2Cl2 (5 mL) was added AgBF4 powder (0.136 g,
0,70 mmol) in small portions at –80 °C over 20 min. The orange
solution was warmed to ambient temperature for 30 min, which
resulted in the precipitation of silver chloride. The mixture was
degassed three times by a freeze–pump–thaw procedure. The pre-
cipitate was removed by filtration (F4), and the solvent was re-
moved in vacuo. The resulting yellow residue was washed four
times with n-hexane (4 mL), dried in vacuo and dissolved in toluene
stronger hydrogen bonds. The only exception in the series (4 mL). The second fraction of a fractional crystallisation, with
storage at –25 °C over 12 h, was collected and washed with toluene
(0.5 mL). Removal of the solvent by syringe and drying in vacuo
yielded Ter3F as a colourless powder (0.098 g, 0.14 mmol, 20%);
m.p. 225 °C (dec.). C48H52FN2P (706.91): calcd. C 81.55, H 7.41,
N 3.96; found C 80.43, H 7.46, N 3.90. 31P{1H} NMR (121.5 MHz,
CD2Cl2, 25 °C): δ = 119.70 [d, 1J(19F,31P) = 1084 Hz] ppm. 19F{1H}
NMR (282.4 MHz, CD2Cl2, 25 °C): δ = –63.15 [d, 1J(19F,31P) =
1084 Hz] ppm. 1H NMR (300.13 MHz, CD2Cl2, 25 °C): δ = 1.57
(s, 12 H, o-CH3), 1.73 (s, 12 H, o-CH3), 2.28 (s, 12 H, p-CH3), 3.79
(br. s, 2 H, NH), 6.70–6.84 (m, 12 H, m-CH), 6.85–6.91 (m, 2 H,
p-CH) ppm. 13C{1H} NMR (62.9 MHz, CD2Cl2, 25 °C): δ = 20.0
(s, o-CH3), 20.43 (br. s, o-CH3), 21.56 (s, o-CH3), 122.0 (s, CH),
128.8 [d, J(13C,31P) = 10.1 Hz], 129.7 (s, CH), 130.9 (m, CH), 135.6
of ionic Ter3[X] species is Ter3[CF3SO3], for which ion pair-
ing in solution was found to be due to very strong hydrogen
bonding.
We have shown that Ter3 can be used as sensitive probe
for the examination of anion properties as well as the type
and degree of cation–anion interactions.
Experimental Section
General Information: All manipulations were carried out under
oxygen- and moisture-free conditions under argon using standard
Schlenk or drybox techniques.
(s, CH), 137.2–137.5 (m), 137.5 (s) ppm. IR (ATR, 25 °C): ν = 3334
˜
Dichloromethane was purified according to a literature pro-
cedure[38] by drying with P4O10 followed by CaH2 and was freshly
distilled and degassed prior to use. Diethyl ether, tetrahydrofuran
(THF), toluene and benzene were dried with Na/benzophenone, n-
hexane was dried with Na/benzophenone/tetraglyme. All solvents
were freshly distilled prior to use. nBuLi (Acros, 2.5 m), AgBF4
(m), 3292 (m), 3000 (m), 2945 (m), 2915 (m), 2853 (m), 2731 (w),
1611 (m), 1583 (m), 1553 (w), 1530 (w), 1513 (w), 1486 (m), 1418
(s), 1373 (s), 1305 (m), 1265 (m), 1225 (s), 1183 (m), 1097 (w), 1073
(m), 1031 (m), 1006 (m), 946 (m), 928 (m), 889 (s), 861 (m), 846
(s), 836 (s), 796 (m), 751 (s), 697 (s), 662 (m), 650 (m), 637 (m), 597
(m), 563 (m), 549 (m) cm–1. Raman (400 mW, 25 °C, 3 accumula-
(Acros, 99%), GaCl3 (abcr, 99.9%), SbF5 (Acros, 99%), SbCl5 tions): 3049 (1), 3012 (1), 2949 (1), 2917 (1), 2856 (1), 2732 (1),
(Acros, 99%), Na[B(C6H5)4] (Acros, 99.5%) and AgSbF6 (abcr,
98%) were used as received. PCl3 (Acros, 97%), CF3SO3H (Merck,
98%) and CF3CO2H (Solvay, 99%) were freshly distilled prior to
use. 2,6-Bis(2,4,6-trimethylphenyl)aniline (TerNH2), 2,6-bis(2,4,6-
trimethylphenyl)phenylamino(dichloro)phosphane (TerN(H)PCl2),
Ag[CHB11H5Br6], silver triflate Ag[CF3SO3], Ag[CF3CO2],
Ag[Al{OCH(CF3)2}4] and Ag(toluene)3[B(C6F5)4] were prepared
according to literature procedures.[39,40,41,42,22c] [(Et2O)2H]-
1613 (3), 1587 (3), 1484 (3), 1449 (3), 1379 (4), 1305 (5), 1288 (3),
1182 (3), 1165 (3), 1159 (3), 1078 (3), 1007 (3), 947 (3), 892 (2), 837
(3), 752 (3), 740 (3), 699 (3), 662 (3), 636 (3), 579 (4), 560 (3), 522
(3), 414 (3), 395 (3), 369 (3), 336 (3), 275 (3) cm–1. CI-MS: m/z (%)
= 329 (11) [TerNH2]+, 330 (60) [TerNH3]+, 705 (14) [M + F –
H]+, 706 (19) [M + F]+, 707 (100) [M + F + H]+. UV/Vis (25 °C,
CH2Cl2): λ = 292 (s), 249 (s) nm. Crystals suitable for X-ray crystal-
lographic analysis were obtained by concentration of a dichloro-
Eur. J. Inorg. Chem. 2012, 261–271
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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267

F. Reiß, A. Schulz, A. Villinger
FULL PAPER
methane solution of Ter3F to incipient crystallisation and storage
[d, m-CF, 1J(13C,19F) = 241 Hz], 125 (ipso-C) ppm. IR (ATR,
at –25 °C overnight.
25 °C): ν = 3287 (w), 2974 (w), 2919 (w), 2859 (w), 2738 (w), 1642
˜
(w), 1611 (w), 1558 (w), 1511 (s), 1461 (s), 1419 (m), 1379 (m), 1340
(m), 1308 (m), 1239 (s), 1203 (m), 1154 (m), 1081 (s), 1033 (m), 977
(s), 954 (s), 857 (m), 806 (m), 774 (m), 756 (s), 738 (s), 681 (m),
660 (s), 630 (m), 610 (m), 600 (m), 572 (m), 556 (m) cm–1. Raman
(1500 mW, 25 °C, 700 scans): 3065 (1), 3019 (1), 2922 (2), 2861 (1),
2739 (1), 1644 (1), 1611 (3), 1584 (3), 1480 (2), 1422 (3), 1381 (2),
1301 (3), 1260 (2), 1216 (4), 1187 (3), 1079 (3), 1009 (2), 968 (5),
843 (2), 732 (1), 658 (1), 598 (2), 583 (3), 556 (2), 521 (2), 491 (2),
448 (2), 267 (2) cm–1. MS (ESI-TOF): m/z (%) = 679 (100)
[B(C6F5)4]–. CI-MS: m/z (%) = 330 (100) [TerNH3]+, 526 (40)
[TerNP(C6F5)]+, 687 (41) [M]+, 855 (35) [M + C6F5]+. UV/Vis
(25 °C, CH2Cl2): λ = 422 (w), 358 (m), 296 (m), 260 (s) nm. Crystals
of Ter3[B(C6F5)4] suitable for X-ray crystallographic analysis were
obtained in moderate yield by prolonged storage of a saturated
dichloromethane solution at ambient temperature.
Ter3Cl: An excess of gaseous HCl was passed through a stirred
suspension of TerN(H)PNTer (1.31 g, 1.90 mmol) in Et2O (80 mL)
at 0 °C over one hour. The solution was warmed to ambient tem-
perature and stirred for one hour. The solvent was removed in
vacuo, and the yellow residue was extracted four times into toluene
(40 mL) and filtered (F4). The resulting light yellow solution was
concentrated to incipient crystallisation and stored at –1 °C for two
days, which resulted in the deposition of colourless crystals. Re-
moval of solvent by syringe and drying in vacuo yielded Ter3Cl as
a colourless crystalline solid (0.77 g, 1.10 mmol, 58%); m.p. 265 °C.
C48H52ClN2P (723.37): calcd. C 79.70, H 7.25, N 3.87; found C
79.26, H 6.84, N 4.07. 31P{1H} NMR (121.5 MHz, CD2Cl2, 25 °C):
1
δ = 129.9 ppm. H NMR (300.13 MHz, CD2Cl2, 25 °C): δ = 1.68
(s, 12 H, o-CH3), 1.85 (s, 12 H, o-CH3), 2.39 (s, 12 H, p-CH3), 4.08
[d, 2 H, NH, 2J(1H,31P) = 3.6 Hz], 6.80–6.94 (m, 12 H, m-CH),
6.95–7.01 (m, 2 H, p-CH) ppm. 13C{1H} NMR (75.5 MHz,
CD2Cl2, 25 °C): δ = 20.30 (s, o-CH3), 20.68 [d, o-CH3, J(13C,31P)
= 2.2 Hz], 21.61 (s, p-CH3), 122.68 [d, p-CH, J(13C,31P) = 2.2 Hz],
129.00 [d, m-CH-Mes, J(13C,31P) = 2.8 Hz], 131.64 [d, J(13C,31P) =
3.3 Hz], 135.08 (s), 137.34 [d, J(13C,31P) = 1.7 Hz], 137.25 [d,
J(13C,31P) = 3.9 Hz], 137.67 (s), 137.75 [d, J(13C,31P) = 2.2 Hz]
Ter3[CF3CO2]: To a stirred solution of TerN(H)PNTer (0.343 g,
0.50 mmol) in toluene (10 mL) was added a solution of trifluoro-
acetic acid (0.057 g, 0.50 mmol) in toluene (1 mL) dropwise at
–80 °C over five minutes. The solution was warmed to ambient
temperature and stirred for one hour. The solvent was removed in
vacuo, and the yellow residue was dissolved in dichloromethane
ppm. IR (ATR, 25 °C): ν = 3309 (m), 3285 (m), 2971 (w), 2945 (5 mL). The resulting yellow solution was concentrated to incipient
˜
(w), 2914 (m), 2853 (w), 2731 (w), 1610 (m), 1582 (w), 1486 (w),
crystallisation and stored at ambient temperature overnight, which
1419 (s), 1373 (s), 1303 (m), 1284 (m), 1260 (m), 1254 (m), 1242 resulted in the deposition of pale yellow crystals. The supernatant
(m), 1222 (s), 1183 (m), 1098 (w), 1073 (m), 1031 (m), 1006 (m), was removed, and the crystalline residue was washed with dichloro-
931 (m), 895 (s), 861 (m), 846 (s), 797 (m), 770 (s), 752 (s), 664 (m), methane (0.5 mL) and dried in vacuo to yield Ter3[CF3CO2]
639 (m), 597 (m), 563 (m), 549 (m) cm–1. Raman (500 mW, 25 °C,
750 scans): 3312 (1), 3286 (1), 3052 (2), 3015 (2), 2917 (3), 2857
(2), 2731 (1), 1613 (3), 1586 (2), 1482 (2), 1443 (2), 1380 (2), 1304
(3), 1232 (1), 1183 (2), 1162 (1), 1079 (2), 1007 (2), 948 (1), 838 (1), δ = 116.7 ppm. H NMR (300.13 MHz, CD2Cl2, 25 °C): δ = 1.75
741 (1), 664 (1), 579 (2), 561 (2), 523 (2), 415 (2), 386 (2), 336 (2), (m, 24 H, o-CH3), 2.36 (s, 12 H, p-CH3), 4.38 [d, 2 H, NH,
275 (2), 240 (2) cm–1. CI-MS: m/z (%) = 330 (15) [TerNH3]+, 687 2J(1H,31P) = 4.5 Hz], 6.78–6.92 (m, 12 H, m-CH), 6.93–7.00 (m, 2
(0.196 g, 0.24 mmol, 48%); m.p. 177 °C (dec. 190 °C).
C50H52F3N2O2P (800.93): calcd. C 74.98, H 6.54, N 3.50; found C
74.89, H 6.54, N 3.36. 31P{1H} NMR (121.5 MHz, CD2Cl2, 25 °C):
1
(100) [M – Cl]+, 743 (20) [isobutene + M]+. UV/Vis (25 °C,
CH2Cl2): λ = 297 (s), 248 (s) nm. Crystals of Ter3Cl suitable for
X-ray crystallographic analysis were obtained in moderate yield by
prolonged storage of dichloromethane solutions at –1 °C.
H, p-CH) ppm. 19F{1H} NMR (282.4 MHz, CD2Cl2, 25 °C): δ =
–75.25 (s) ppm. 13C{1H} NMR (75.5 MHz, CD2Cl2, 25 °C): δ =
20.35 (m, o-CH3), 21.56 (s, p-CH3), 122.52 (s, p-CH), 129.10 (s, m-
CH-Mes), 130.19 (m-CH), 130.81 (d), 135.24 (d), 137.17 (br. s),
137.58 (s), 137.67 (s), 137.93 (s) ppm. IR (ATR, 25 °C): ν = 3354
˜
Ter3[B(C6F5)4]: To a stirred solution of (TerNH)2PCl (0.180 g,
0.25 mmol) in toluene (15 mL) was added a solution of Ag[B-
(C6F5)4]·2toluene (0.243 g, 0.25 mmol) in toluene (15 mL) dropwise
at ambient temperature over 15 min. The orange solution was
stirred for 1 h. The solvent was removed in vacuo, and the orange
residue was dissolved in CH2Cl2 (10 mL) and filtered (F4). The
resulting orange solution was concentrated to incipient crystallisa-
tion and stored at –1 °C overnight, which resulted in the deposition
of orange crystals. Removal of solvent by syringe and drying in
vacuo yielded the dichloromethane solvate Ter3[B(C6F5)4] as an
orange crystalline solid (0.125 g, 0.092 mmol, 37%); m.p. 244 °C
(dec.). C73H54BCl2F20N2P (1451.88): calcd. C 60.39, H 3.75, N
1.93; found C 60.40, H 3.68, N 1.86. 31P{1H} NMR (121.5 MHz,
(w), 3314 (w), 3298 (w), 3250 (w), 2946 (w), 2917 (m), 2856 (w),
1875 (w), 1756 (m), 1611 (m), 1487 (w), 1434 (m), 1422 (s), 1368
(m), 1288 (w), 1264 (m), 1241 (w), 1209 (s), 1157 (s), 1142 (s), 1133
(s), 1075 (m), 1031 (m), 1007 (m), 949 (m), 933 (m), 899 (s), 848
(s), 798 (m), 777 (m), 754 (s), 731 (m), 704 (m), 696 (m), 661 (m),
648 (m), 629 (m), 614 (m), 596 (m), 550 (m) cm–1. Raman
(1500 mW, 25 °C, 700 scans): 3316 (1), 3300 (1), 3048 (3), 3011 (3),
2915 (3), 2859 (2), 2733 (2), 2550 (1), 1759 (1), 1611 (4), 1588 (3),
1484 (2), 1445 (2), 1381 (3), 1306 (5), 1229 (3), 1185 (1), 1164 (1),
1077 (2), 1007 (2), 949 (1), 824 (1), 739 (1), 662 (2), 577 (3), 554
(2), 521 (2), 489 (1), 415 (1), 330 (2), 276 (2), 249 (2), 234 (2) cm–1.
CI-MS m/z (%) = 330 (100) [TerNH3]+, 358 (26) [TerNP]+, 671 (15)
[M – CH4]+, 687 (77) [M]+, 705 (21) [M + F – H]+. UV/Vis (25 °C,
CH2Cl2): λ = 290 (s), 250 (s) nm. Crystals suitable for X-ray crystal-
lographic analysis were obtained by concentration of a dichloro-
methane solution of Ter3[CF3CO2] to incipient crystallisation and
storage at ambient temperature overnight.
1
CD2Cl2, 25 °C): δ = 249.1 ppm. H NMR (300.13 MHz, CD2Cl2,
25 °C): δ = 1.76 (s, 24 H, o-CH3), 2.25 (s, 12 H, p-CH3), 6.94 (s, 8
H, m-CH-Mes), 7.14 [d, 4 H, m-CH, 3J(1H,1H) = 7.74 Hz], 7.31 [d,
2 H, NH, 2J(1H,31P) = 12.3 Hz], 7.36–743 (m, 2 H, p-CH) ppm.
11B{1H} NMR (96.29 MHz, CD2Cl2, 25 °C): δ = –16.60 ppm.
19F{1H} NMR (282.38 MHz, CD2Cl2, 25 °C): δ = –132.78 (m),
Ter3[GaCl4]: To a stirred suspension of (TerNH)2PCl (0.180 g,
–163.75 (m), –167.49 (m) ppm. 13C{1H} NMR (75.5 MHz, CD2Cl2, 0.25 mmol) in dichloromethane (6 mL) was added a solution of
25 °C): δ = 20.65 (s, o-CH3), 21.32 (s, p-CH3), 129.08 (s, p-CH), GaCl3 (0.053 g, 0.30 mmol) in dichloromethane (2 mL) dropwise at
130.61 (s, m-CH-Mes), 131.08 (s, m-CH), 132.26 [d, J(13C,31P) =
3.3 Hz], 132.59 [d, J(13C,31P) = 4.4 Hz], 132.76 [d, J(13C,31P) =
3.0 Hz], 137.52 [d, J(13C,31P) = 6.0 Hz], 141.23 (s), 148.7 [d, o-CF,
ambient temperature over ten minutes. The pale yellow suspension
was stirred for one hour, which resulted in an orange solution. This
solution was concentrated to incipient crystallisation and stored at
–1 °C overnight, which resulted in the deposition of orange crystals.
1
1J(13C,19F) = 238 Hz], 138.8 [d, p-CF, J(13C,19F) = 240 Hz], 136.9
268
www.eurjic.org
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 261–271

The N,N-Bis(terphenyl)aminophosphenium Cation
The supernatant was removed, and the crystalline residue was
washed with dichloromethane (0.5 mL) and dried in vacuo to yield
Ter3[GaCl4] as a orange crystalline solid (0.105 g, 0.12 mmol,
UV/Vis (25 °C, CH2Cl2): λ = 438 (w), 363 (m), 292 (s), 246(s) nm.
Crystals suitable for X-ray crystallographic analysis were obtained
by concentration of a dichloromethane solution of Ter3[CF3SO3]
47%); m.p. 215 °C (dec.). C48H52Cl4GaN2P (899.45): calcd. C to incipient crystallisation and storage at –25 °C overnight.
64.10, H 5.92, N 3.11; found C (measured with lead oxide) 64.53,
Ter3[Al{OCH(CF3)2}4]: To a stirred solution of (TerNH)2PCl
(0.175 g, 0.24 mmol) in dichloromethane (4 mL) was added a solu-
tion of Ag[Al{OCH(CF3)2}4] (0.200 g, 0.25 mmol) in dichloro-
methane (2 mL) dropwise at ambient temperature over ten minutes.
H 5.92, N 3.14. 31P{1H} NMR (121.5 MHz, CD2Cl2, 25 °C): δ =
1
250 ppm. H NMR (300.13 MHz, CD2Cl2, 25 °C): δ = 1.80 (s, 24
H, o-CH3), 2.32 (s, 12 H, p-CH3), 7.04 (br. s, 8 H, m-CH-Mes), 7.15
[d, 4 H, m-CH, 3J(1H,1H) = 7.6 Hz], 7.38[d, 2 H, NH, 2J(1H,31P) =
The orange solution was stirred for 30 min and filtered (F4). The
12.5 Hz], 7.39–7.44 (m,
2
H, p-CH) ppm. 13C{1H} NMR
solvent was removed in vacuo, and the orange precipitate was
washed four times with n-hexane (4 mL). This precipitate was dis-
solved in dichloromethane (2 mL) and filtered (F4). Removal of
solvent by syringe and drying in vacuo yielded Ter3[Al{OCH-
(CF3)2}4] (0.232 g, 0.17 mmol, 70%) as a shiny orange mircocrys-
talline solid; m.p. 273 °C (dec.). C60H56AlF24N2O4P (1383.01):
calcd. C 52.11, H 4.08, 2.03; found C 52.74, H 4.08, N 1.97.
31P{1H} NMR (121.5 MHz, CD2Cl2, 25 °C): δ = 249 (br. s) ppm.
1H NMR (300.13 MHz, CD2Cl2, 25 °C): δ = 1.79 (s, 24 H, o-CH3),
2.31 (s, 12 H, p-CH3), 4.51 (m, 4 H, isopropoxy), 7.02 (s, 8 H, m-
(75.5 MHz, CD2Cl2, 25 °C): δ = 20.83 (br. s, o-CH3), 21.53 (s, p-
CH3), 129.12 (s, p-CH), 130.64 (s, m-CH-Mes), 131.14 (s, m-CH),
132.23 [d, J(13C,31P) = 3.3 Hz], 132.72 [d, J(13C,31P) = 4.4 Hz],
132.86 [d, J(13C,31P) = 2.8 Hz], 137.57 [d, J(13C,31P) = 3.9 Hz],
141.21 (s) ppm. IR (ATR, 25 °C): ν = 3333 (w), 3261 (m), 3052
˜
(w), 2975 (m), 2945 (m), 2916 (m), 2844 (m), 2737 (w), 1609 (m),
1573 (m), 1557 (m), 1478 (m), 1436 (s), 1416 (m), 1380 (m), 1342
(m), 1300 (m), 1292 (m), 1254 (m), 1201 (m), 1164 (m), 1129 (m),
1068 (m), 1032 (m), 1007 (m), 950 (s), 939 (s), 852 (s), 800 (s), 780
(m), 753 (s), 737 (m), 652 (m), 627 (m), 598 (m), 571 (m), 562 (m),
544 (m) cm–1. Raman (1500 mW, 25 °C, 669 scans): 3264 (1), 3057
(1), 3023 (1), 2917 (3), 2857 (1), 2737 (1), 1611 (3), 1582 (3), 1480
(2), 1420 (3), 1380 (2), 1310 (3), 1268 (2), 1216 (5), 1187 (3), 1073
(3), 1007 (2), 963 (4), 840 (2), 730 (2), 658 (2), 598 (2), 583 (3), 521
(2), 489 (2), 415 (2), 361 (2), 269 (2), 230 (1), 207 (1) cm–1. CI-MS:
m/z (%) = 358 (16) [TerNP]+, 671 (21) [M – CH4]+, 687 (100) [M]+.
UV/Vis (25 °C, CH2Cl2): λ = 438 (m), 361 (m), 255 (s) nm. Crystals
suitable for X-ray crystallographic analysis were obtained by con-
centration of a dichloromethane solution of Ter3[GaCl4] to incipi-
ent crystallisation and storage at ambient temperature overnight.
3
CH-Mes), 7.15 [d, 4 H, m-CH, J(1H,1H) = 7.7 Hz], 7.29 [br. d, 2
2
3
H, NH, J(1H,31P) = 12.3 Hz] ppm. 7.42 [t, 2 H, p-CH, J(1H,1H)
= 7.7 Hz]. 13C{1H} NMR (75.5 MHz, CD2Cl2, 25 °C): δ = 20.75
(s, o-CH3), 21.47 (s, p-CH3), 71.47 (m, isopropoxy), 121.71 (s, CF3),
125.51 (s, CF3) 129.16 (s, p-CH), 130.70 (s, m-CH-Mes), 131.14 (s,
m-CH), 132.25 [d, J(13C,31P) = 3.3 Hz], 132.52 46 [d, J(13C,31P) =
4.4 Hz], 132.90 [d, J(13C,31P) = 2.8 Hz], 137.60 [d, J(13C,31P) =
3.9 Hz], 141.33 (s) ppm. 19F{1H} NMR (282.38 MHz, CD2Cl2,
25 °C): δ = –77.38 (s) ppm. IR (ATR, 25 °C): ν = 3479 (w), 3378
˜
(w), 3319 (w), 3255 (w), 2948 (w), 2919 (w), 2860 (w), 2737 (w),
1610 (w), 1603 (w), 1574 (w), 1488 (w), 1441 (m), 1426 (m), 1375
(m), 1290 (m), 1261 (m), 1211 (s), 1178 (s), 1099 (s), 1034 (m), 1009
(m), 957 (m), 890 (m), 852 (s), 798 (m), 754 (m), 736 (m), 727 (m),
685 (s), 650 (m), 630 (m), 597 (m), 566 (m), 550 (m) cm–1. Raman
(1500 mW, 25 °C, 700 scans): 3067 (2), 3021 (1), 2920 (2), 2866 (2),
2743 (1), 1611 (3), 1586 (3), 1480 (2), 1428 (5), 1383 (2), 1380 (4),
1289 (3), 1270 (3), 1221 (5), 1185 (3), 1073 (3), 1009 (3), 978 (4),
842 (2), 784 (1), 759 (1), 730 (2), 658 (2), 597 (2), 577 (2), 556 (2),
519 (2), 489 (2), 415 (2), 361 (2), 330 (2), 271 (2), 236 (1) cm–1. CI-
MS m/z (%) = 329 (32) [TerNH2]+, 330 (20) [TerNH3]+, 705 (100)
[M + F – H]+. UV/Vis (25 °C, CH2Cl2): λ = 435 (w), 360 (m), 297
(m), 271 (s), 246 (s) nm. Crystals suitable for X-ray crystallographic
analysis were obtained by concentration of a fluorobenzene solu-
tion of Ter3[Al{OCH(CF3)2}4] to incipient crystallisation and stor-
age at –25 °C for two days. Longer storage also produced ad-
ditional crystals of (TerNH)2P(H)OAl[OCH(CF3)2]3 as a result of
hydrolysis.
Ter3[CF3SO3]: To a stirred solution of TerN(H)PNTer (0.342 g,
0.50 mmol) in toluene (22 mL) was added a solution of CF3SO3H
(0.075 g, 0.50 mmol) in toluene (4 mL) dropwise at –80 °C over ten
minutes. The resulting yellow solution was warmed to ambient tem-
perature and stirred for 30 min. The solvent was removed in vacuo,
and the yellow residue was dissolved in dichloromethane (5 mL).
This solution was concentrated to incipient crystallisation and
stored at –25 °C overnight, which resulted in the deposition of
orange crystals. The supernatant was removed, and the crystalline
residue was washed with dichloromethane (0.5 mL) and dried in
vacuo to yield Ter3[CF3SO3] as an orange crystalline solid (0.08 g,
0.10 mmol, 20%); m.p. 255 °C (dec.). C49H52F3N2O3PS (836.98):
calcd. C 70.31, H 6.26, N 3.35; found C 70.44, H 6.80, N 3.32.
31P{1H} NMR (121.5 MHz, CD2Cl2, 25 °C): δ = 261 (br. s) ppm.
1H NMR (300.13 MHz, CD2Cl2, 25 °C): δ = 1.74 (s, 24 H, o-CH3),
2.33 (s, 12 H, p-CH3), 6.94 (s, 8 H, m-CH-Mes), 7.01 [d, 4 H, m-
3
CH, J(1H,1H) = 7.7 Hz], 7.34 (m, 2 H, p-CH), 9.67 [d, 2 H, NH,
Ter3[CHB11H5Br6]: To a stirred suspension of (TerNH)2PCl
2J(1H,31P) = 12.3 Hz] ppm. 13C{1H} NMR (75.5 MHz, CD2Cl2,
25 °C): δ = 20.86 [d, o-CH3, J(13C,31P) = 2.2 Hz], 21.56 (s, p-CH3),
128.66 (s, p-CH), 129.66 (s, m-CH-Mes), 131.34 (s, m-CH), 132.90
[d, J(13C,31P) = 8.8 Hz], 133.64 (br. s), 135.46 [d, J(13C,31P) =
5.5 Hz], 137.55 [d, J(13C,31P) = 2.8 Hz], 139.60 (s) ppm. 19F{1H}
NMR (282.38 MHz, CD2Cl2, 25 °C): δ = –78.67 (s) ppm. IR (ATR,
(0.180 g, 0.25 mmol) in CH2Cl2 (5 mL) was added
Ag[CHB11H5Br6] powder (0.230 g, 0.32 mmol) in one portion at
ambient temperature. The orange suspension was stirred for one
hour and filtered (F4). The solvent was removed in vacuo, and the
resulting orange precipitate was washed four times with benzene
(2 mL). The resulting deep orange oil was covered with a layer of
25 °C): ν = 3341 (w), 3234 (w), 2917 (m), 2857 (w), 2734 (w), 1612 benzene and stored at ambient temperature overnight, which re-
˜
(w), 1575 (w), 1566 (w), 1506 (w), 1441 (m), 1426 (m), 1379 (m), sulted in the deposition of orange crystals. Removal of the solvent
1293 (m), 1269 (m), 1223 (s), 1168 (s), 1077 (w), 1024 (s), 1010 (s),
by syringe and drying in vacuo yielded Ter3[CHB11H5Br6] (0.129 g,
969 (m), 850 (s), 803 (m), 754 (m), 744 (m), 636 (s), 596 (m), 563 0.10 mmol, 40%); m.p. 225 °C (dec.). C49H58B11Br6N2P (1304.32):
(m), 551 (m), 541 (m) cm–1. Raman (400 mW, 25 °C, 750 scans): calcd. C 45.12, H 4.48, N 2.15; found C 45.65, H 4.61, N 1.84.
3055 (3), 3017 (2), 2919 (4), 2858 (2), 2733 (1), 1613 (4), 1682 (3),
1582 (3), 1484 (2), 1435 (3), 1378 (2), 1306 (1), 1214 (5), 1189 (2),
1083 (3), 1031 (2), 1009 (2), 982 (5), 855 (2), 797 (1), 739 (2), 654
31P{1H} NMR (121.5 MHz, CD2Cl2, 25 °C): δ = 249.6 (br. s) ppm.
1H NMR (300.13 MHz, CD2Cl2, 25 °C): δ = 1.80 (s, 24 H, o-CH3),
2.31 (s, 12 H, p-CH3), 1.00–3.50 (m, carboranate-BH/CH), 7.03 (s,
3
(2), 579 (2), 554 (2), 523 (2), 415 (2), 384 (2), 330 (2), 265 (2), 232 8 H, m-CH-Mes), 7.15 [d, 4 H, m-CH, J(1H,1H) = 7.74 Hz], 7.41
(2) cm–1. CI-MS: m/z (%) = 330 (100) [TerNH3]+, 687 (13) [M]+. (d, 2 H, NH), 7.42 [t, 2 H, p-CH, J(1H,1H) = 7.65 Hz] ppm. 11B
3
Eur. J. Inorg. Chem. 2012, 261–271
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
269

F. Reiß, A. Schulz, A. Villinger
FULL PAPER
[6]
[7]
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NMR (96.3 MHz, CD2Cl2, 25 °C): δ = –1.90 (s, 1B), –9.92 (s, 5B),
–20.1 [d, 5B, 1J(1H,11B)
=
167 Hz] ppm. 13C{1H} NMR
(75.5 MHz, CD2Cl2, 25 °C): δ = 20.82 (br. s, o-CH3), 21.55 (s, p-
CH3), 129.16 (s, p-CH), 130.68 (s, m-CH-Mes), 131.17 (s, m-CH),
132.25 [d, J(13C,31P) = 3.3 Hz], 132.55 [d, J(13C,31P) = 4.4 Hz],
132.90 [d, J(13C,31P) = 2.8 Hz], 137.58 [d, J(13C,31P) = 3.9 Hz],
141.26 (s) ppm. IR (ATR, 25 °C): ν = 3330 (w), 3173 (w), 3052 (w),
˜
2946 (w), 2916 (m), 2855 (w), 2601 (m), 1611 (m), 1556 (w), 1510
(m), 1435 (s), 1428 (m), 1378 (m), 1290 (w), 1240 (m), 1199 (m),
1176 (m), 1126 (m), 1076 (w), 1002 (s), 990 (s), 952 (s), 932 (s), 857
(s), 805 (s), 744 (s), 679 (m), 633 (s), 596 (m), 563 (m), 549 (m)
cm–1. A Raman spectrum was not measured because of fluores-
cence behaviour. CI-MS: m/z (%) = 330 (100) [TerNH3]+, 386 (15)
[isobutene + TerNH3]+. UV/Vis (25 °C, CH2Cl2): λ = 435 (w), 358
(m), 296 (w), 245 (s) nm. Crystals suitable for X-ray crystallo-
graphic analysis were obtained by concentration of a benzene solu-
tion of Ter3[CHB11H5Br6] to a deep orange oil and storage at am-
bient temperature overnight.
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[9]
[10]
[11]
[12]
Ter[SbF6]: To a stirred suspension of (TerNH)2PCl (0.180 g,
0.25 mmol) in CH2Cl2 (5 mL) was added a suspension of Ag[SbF6]
(0.103 g, 0.30 mmol) in dichloromethane (10 mL) over 20 min at
–80 °C. The orange solution was warmed to ambient temperature
for 30 min, which resulted in the precipitation of silver chloride.
The solvent was removed in vacuo, and the residue was dissolved
in CH2Cl2 (3 mL) and filtered (F4). The resulting solution was con-
centrated to incipient crystallisation and stored at –1 °C overnight,
which resulted in the deposition of colourless crystals and a few
orange crystals. The colourless crystals were identified as
[TerNH3][SbF6] and the orange crystals were identified as
Ter3[SbF6] by X-ray structure determinations.
[13]
[14]
[15]
[16]
CCDC-832970 (for Ter3F), -832971 (for Ter3Cl), -832972 (for
Ter3[CF3CO2]), -832973 (for Ter3[CF3SO3]), -832974 (for
Ter3[GaCl4]), -832975 (for Ter3[SbF6]), -832976 (for Ter3-
[B(C6F5)4]), -832977 (for Mes*3[GaCl4]), -832978 (for Ter3-
[Al(OCH(CF3)2)4]), -832979 (for (TerNH)2P(H)OAl(OCH-
(CF3)2)3), -832980 (for Ter3[CHB11H5Br6]), and -832981 (for
[TerNH3][SbF6]) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
[17]
[18]
[19]
[20]
[21]
Supporting Information (see footnote on the first page of this arti-
cle): Crystallographic and further details.
[22]
[23]
Acknowledgments
Financial support by the Deutsche Forschungsgemeinschaft
(DFG) (SCHU 1170/6-1) is gratefully acknowledged.
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Published Online: December 8, 2011
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