Reactivity of bulky aminophosphanes towards small molecules: Activation of dihydrogen and carbon dioxide by aminophosphane/borane frustrated Lewis pairs

Article abstract of DOI:10.1016/j.poly.2020.114930

A series of mono- and bisaminophosphanes with formulas R₂NPR'R’’ and (R₂N)₂PR’ (R = iPr, Cy; R’ = Ph, Cy; R’’ = iPr) were characterized by X-ray analysis, NMR spectroscopy and computational methods. The common structural f

Full text of DOI:10.1016/j.poly.2020.114930

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Reactivity of bulky aminophosphanes towards small molecules: activation of
dihydrogen and carbon dioxide by aminophosphane/borane frustrated Lewis
pairs
Magdalena Siedzielnik, Kinga Kaniewska-Laskowska, Natalia Szynkiewicz,
Jarosław Chojnacki, Rafał Grubba
PII:
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DOI:
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https://doi.org/10.1016/j.poly.2020.114930
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Please cite this article as: M. Siedzielnik, K. Kaniewska-Laskowska, N. Szynkiewicz, J. Chojnacki, R. Grubba,
Reactivity of bulky aminophosphanes towards small molecules: activation of dihydrogen and carbon dioxide by
aminophosphane/borane frustrated Lewis pairs, Polyhedron (2020), doi: https://doi.org/10.1016/j.poly.
2020.114930
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Reactivity of bulky aminophosphanes towards small molecules: activation
of dihydrogen and carbon dioxide by aminophosphane/borane frustrated
Lewis pairs
Magdalena Siedzielnik,§ Kinga Kaniewska-Laskowska,§ Natalia Szynkiewicz, Jarosław
Chojnacki, Rafał Grubba*
Department of Inorganic Chemistry, Faculty of Chemistry, Gdańsk University of Technology,
G. Narutowicza St. 11/12. Pl-80-233 Gdańsk, Poland
* To whom correspondence should be addressed: Email: rafal.grubba@pg.edu.pl
§ These authors contributed equally.
Abstract
A series of mono- and bisaminophosphanes with formulas R2NPR’R’’ and (R2N)2PR’ (R = iPr,
Cy; R’ = Ph, Cy; R’’ = iPr) were structurally characterized by X-ray structural analysis, NMR
spectroscopy and computational methods. The common structural futures of these species are
short and polarized P-N bonds, a pyramidal geometry at the P atom and an almost planar
geometry at the N atoms. According to DFT calculations, these compounds are highly
nucleophilic, with nucleophilic centers located on the N and P atoms. Except for species
containing a PPh2 moiety, the obtained aminophosphanes are air-stable and do not react with
water. They form stable frustrated Lewis pairs with BPh3 or B(C6F5)3. Mono- and
bisaminophosphanes in the presence of B(C6F5)3 activate dihydrogen and carbon dioxide at
room temperature.
Keywords: main group chemistry; phosphanes; boranes; frustrated Lewis pairs; dihydrogen;
carbon dioxide.

Introduction
Aminophosphanes are a class of P-tricoordinate compounds containing one to three
polar P-N bonds and constitute a richly represented and widely studied family of
phosphanes.[1–3] Based on the number of amino groups bound to the P atom, they may be
classified as mono-, di- or trisaminophosphanes, and based on the number of hydrogen atoms
attached to the nitrogen atom, each group may be subdivided into dialkylamino- RxP(NR’R”)3-x,
monoalkylamino- RxP(NHR’)3-x and aminophosphanes RxP(NH2)3-x; mono-, bis- and
tris(dialkylamino)phosphanes are of the greatest interest because of their stability.[1,2,4,5]
Systems with N-H bonds tend to condense to form oligomers, and this process is enhanced as
the number of amino substituents increases and the steric bulk of these substituents
decreases.[4] Moreover, the N-H atom is labile and can easily migrate from the nitrogen atom
to the phosphorus atom, forming two isomers: R2P-N(H)R' and R2P(H)=NR’.[5]
Because their chirality, nucleophilicity, and reactivity towards metal complexes of
phosphanes strongly depend on the substituents, attaching amino groups to the P center
significantly broadens the scope of properties that can be tailored to specific applications. The
nitrogen atom may constitute the stereogenic center of the molecule itself or generate a P
stereogenic center as an amino substituent on phosphanes bearing three different groups,
yielding chiral phosphorus ligands for use in asymmetric catalysis.[6] The introduction of
nitrogen atoms as additional reactive sites increases their reactivity due to the presence of both
hard (N) and soft (P) Lewis basic centers in one molecule. Therefore, in reactions with Lewis
acids, aminophosphanes may behave as ambident reagents, with the P atoms being a basic
center when soft acids are used as reagent partners and conversely, with the nitrogen atoms
serving as bases when reacting with hard acids.[7] Despite the π-electron transfer from
neighboring nitrogen atoms, the nucleophilicity of aminophosphanes depends mainly on the
availability of the lone pair on the phosphorus atom; therefore, their nucleophilicity is similar
to that of tertiary alkyl amines and phosphanes.[8] This indicates that steric effects (steric
hindrance of the P and N substituents) rather than electronic effects are crucial in reactions with
electrophiles.[2]
The condensation reaction between a phosphorus(III) halide and the respective primary
or secondary amine(s) RR'NH is the most convenient method to synthesize
aminophosphanes.[1,2,9–14] This method is widely used because of its readily available and
inexpensive reagents, easy isolation process, and overall reaction yields ranging from

approximately 50 to 80%. To obtain mono- and bisaminophosphanes, the condensation reaction
should be preceded by the introduction of alkyl, aryl or alkoxy groups in the reaction of PCl3
with the respective organometallic reagent or alcohol due to the labile nature of the P–N
bonds.[2,10,14] Therefore, aminophosphanes are generally air- and moisture-sensitive, and
polar P-N bond(s) undergo hydrolysis.[5,15] Nevertheless, aminophosphanes are widely
applicable as catalysts in polymerization processes and peptide synthesis[2,16] or as versatile
ligands for the synthesis of transition metal complexes, which in turn supports a wide variety
of organic reactions.[1,17] They may also serve as synthons to obtain a variety of inorganic
heterocycles and as precursors for the synthesis of fire retardants, chemotherapeutic agents,
sterilizing agents, and effective insecticides.[2]
Although aminophosphanes have a long-standing history in main-group-element
chemistry, there are no reports on their reactivity as Lewis basic components in one of the most
attention-grabbing groups of nonmetallic catalysts, frustrated Lewis pairs (FLPs).[18–21]
These pairs are inter- or intramolecular combinations of Lewis acids and Lewis bases that,
because of steric encumbrance[22,23] or reduced electronic overlap[24–27] of the reactive
centers, do not form classic Lewis adducts. Such systems exhibit unusual reactivity towards
small molecules – for example, FLPs are capable of activating H2,[28–31] CO2,[32–34]
CO,[35] N2O,[36,37] NO,[38] or SO2[39–42]. Even simple combinations of Lewis acids
(mostly boranes) with amines,[31,41,43,44] imines[18,45] or phosphanes[40,45,46] can split
dihydrogen molecules heterolytically under ambient conditions to form salts that may serve as
effective catalysts in the hydrogenation of unsaturated organic compounds.[28–31] There are
only a few examples of nonmetallic compounds with P-N bonds that were proven to activate
small molecules. Among this class of compounds, superbases attract the most attention.[47,48]
Equimolar mixtures of Verkade superbase[49,50] or phosphazene[50], with weak Lewis acids
(BPh3 or HBMe2) form FLPs that split H2, while amidophosphoranes fix CO2 molecules
between the P-N bonds.[51] Interestingly, reactions of the classical adduct of Verkade
superbase and strong Lewis acid B(C6F5)3 with CO2, PhNCO, PhNSO, or PhCH2N3 led to the
insertion of these molecules into the P-B bond.[52]
One of the main interests of our group is the application of compounds containing p-
block elements and possessing polarized covalent bonds to the activation of small molecules.
Recently, we reported on the reactivity of (R2N)2P-PtBu2, unsymmetrical bis(dialkylamino)-
substituted diphosphanes[53] that, in combination with BPh3 acting as a catalyst, incorporated
CO2 molecules into the polar P-P bond to form (R2N)2P-O-C(O)-PtBu2.[54] Moreover, we

showed that diaminophosphinoboranes can act as intramolecular FLPs and react with CO2 or
SO2 via the insertion of these molecules into polarized P-B bonds[55][56] We decided to
include systems with polarized P-N bonds, such as aminophosphanes, in our research program.
Herein, we report the structures of a series of mono- and bisaminophosphanes with bulky
substituents and their reactivity towards small molecules.
Results and discussion
Syntheses and structures of mono- and bisaminophosphanes
For the reactivity studies, we selected a series of aminophosphanes bearing bulky iPr2N
(1-3) or Cy2N (4-6) amino groups (Chart 1). We assumed that these substituents would increase
the stability of the obtained compounds and facilitate the formation of crystalline products.
Moreover, in these species, the P atom bears phenyl (1, 2, 4-6), cyclohexyl (3), or isopropyl
substituents (6). In this group of compounds, three monoaminophosphanes (2, 5, 6) and three
bisaminophosphanes (1, 3, 4) were obtained. The syntheses of 1,[57] 2,[58] 4,[59] and 5[60]
were previously reported; however, solid-state structures for these aminophosphanes remained
unavailable.
Pr
i
i
Pr
i
Pr
Pr
i
i
N
P
N
N
P
N
N
P
Cy
Pr
Ph
Pr
Ph
Pr
i
Pr
i
i
Ph
Pr
i
Pr
i
2
3
1
Cy
Cy
Cy
Cy
Cy
Cy
N
P
N
N
P
N
P
Ph
Cy
Ph
Pr
i
Ph
Ph
Cy
5
6
4
Chart 1 Mono- and bisaminophosphanes selected for the reactivity studies.
The first step of the syntheses was the condensation of phosphorus trichloride with the
secondary amine iPr2NH or Cy2NH (Scheme 1). For the syntheses of mono- and
bisaminophosphanes, two- and four-fold excesses, respectively, of the secondary amine were
used. In the second step, the obtained amino(chloro)phosphanes reacted with the appropriate
organolithium or/and Grignard reagent. In the synthesis of 2, we used a modified literature

method[58] where commercially available Ph2PCl reacted with two equivalents of iPr2NH.
Notably, attempts to introduce bulkier alkyl groups such as tBu at the P atom were unsuccessful.
According to 31P NMR spectroscopy, reactions of the mentioned amino(chloro)phosphanes
with tBuLi or reactions of tert-butyl-substituted mono- and dichlorophosphanes with R2NH (R=
iPr, Cy) did not occur at all, or only very weak signals attributable to the desired products were
observed.
PhLi
(R N) PPh R = Pr (1) 71%
i
2
2
- LiCl
R = Cy (4) 38%
4 R2NH
(R2N)2PCl
PCl3
-2 R2NH·HCl
CyMgCl
- MgCl2
(R N) PCy R = Pr (3) 48%
i
2
2
2 Pr NH
i
2
Pr NPPh
(2) 62%
i
Ph2PCl
2
2
- Pr NH·HCl
i
2
2 PhLi
-2 LiCl
Cy2NPPh2
(5) 49%
2 Cy2NH
Cy2NPCl2
PCl3
- Cy2NH·HCl
PrMgCl
-MgCl2
i
Cy NP( Pr)Cl
i
2
- LiCl
PhLi
Cy NP( Pr)Ph (6) 68%
i
2
Scheme 1 Syntheses of mono- and bisaminophosphanes.
The 31P NMR chemical shifts of aminophosphanes were in the range of 37.9 ppm to 64.9 ppm
(Table 1). The signals of bisaminophosphanes (1, 3, 4) are more downfield shifted compared to
the signals of monoaminophosphanes (2, 5, 6). Analytically pure crystalline compounds 1-6
were obtained by extraction of the crude products with petroleum ether (1, 3) or toluene (2, 4-

6) followed by crystallization at -20°C (1, 2, 4-6) or +4°C (3). Although the syntheses of 1-6
were almost quantitative, the yields of the crystalline products varied from 38% to 71%.
Table 1 31P{1H} NMR data for the aminophosphanes (1-6) together with 31P{1H} NMR and 11B NMR
data for the products of the activation of H2 (1a-6a) and CO2 (1b, 3b, 4b, 6b) by
aminophosphane/borane FLPs.
No. δ 31P{1H}
1JP-H
δ 11B
1JB-H
[ppm]
[Hz]
[ppm]
[Hz]
1
59.5
37.9
57.7
64.9
41.3
41.7
17.0
15.5
28.2
19.0
16.1
33.9
36.4
50.2
39.9
39.1
2
3
4
5
6
1a
2a
3a
4a
5a
6a
1b
3b
4b
6b
534
519
519
539
521
495
-25.0
-24.7
-25.0
-24.9
-25.0
-24.7
-2.6
89
88
92
90
90
90
-2.8
-2.7
-2.1
Solid-state structures of all the isolated aminophosphanes were determined by single-
crystal X-ray structure analysis. The X-ray structures of 1-6 are presented in Figure 1.
Compounds 1-6 exhibit common structural features that are characteristic of the whole family
of aminophosphanes: planar geometry of the N atoms, pyramidal geometry of the P atoms, and
relatively short P-N distances (Table 2). Interestingly, in the case of bisaminophosphanes 1, 3,
and 4, the geometries around the P atoms are more flattened. The P-N bond lengths are in the
narrow range of 1.681(2) Å – 1.705(3) Å, in between the single and double covalent P-N bond

lengths of 1.820 Å[61] and 1.620 Å[62], respectively. The determined distances are within the
range of 1.661 Å – 1.723 Å reported previously for P-N bonds in aminophosphanes.[63–70]
Figure 1 X-ray structures of aminophosphanes 1-6 showing the atom-numbering scheme. H atoms
have been omitted for clarity.
Table 2 P-N bond distances and geometries at the P and N atoms in aminophosphanes 1-6.
No. P1-N1
[Å]
P1-N2
[Å]
ΣP1
ΣN1
ΣN2
[°]
[°]
[°]
1
2
3
4
5
6
1.696(3)
1.681(2)
1.705(3)
1.698(2)
1.690(2)
1.6933(9)
1.698(4)
317.02
310.91
314.49
313.60
310.76
308.07
359.17
357.34
359.90
359.68
357.54
358.82
359.40
1.712(3)
1.703(2)
359.89
359.37
The structural features of 1-6 were investigated by DFT methods (see the ESI for details). NBO
analysis indicates that the N atoms exhibit sp2 hybridization and lone pairs at these atoms
display an almost pure p character. Otherwise, the lone pairs at the P atoms have significant s
character (48-50%), whereas the p orbitals of the P atoms are involved mainly in the formation

of P-C and P-N bonds (s character contribution of only 16-17%). The NBO orbitals attributed
to the lone pairs on the N atoms for the representative aminophosphane 6 are presented in Figure
2. The decreased occupancies of NBO orbitals attributed to the lone pair orbitals of the N atoms
and increased occupancies of antibonding σ*(P) orbitals suggest significant π-interactions
between these orbitals (negative hyperconjugation). This is in accord with the structural features
of aminophosphanes, such as short P-N bonds and planar amino groups. According to Hirshfeld
population analysis, P-N bonds are polarized towards the N atom, where higher polarization is
observed for bisaminophosphanes (1, 3, 4) than for other compounds (Figures S91-S96). For
representative compound 1, the Hirshfeld charges on P and N atoms have values of +0.159 (P1),
-0.116 (N1), and -0,119 (N2). Fukui function analysis revealed that the values of the condensed
nucleophilic Fukui function for P and N atoms are very similar, which indicates that both
nitrogen and phosphorus atoms may constitute the nucleophilic center of aminophosphanes
when reacting with an electrophile (Table S4). Similarly, the HOMO orbitals of 1-6 are located
mainly at these atoms (Figures S85-S90).
Figure 2 The NBO orbitals of 6 associated with lone pairs on the nitrogen and phosphorus atoms.
Reactivity of mono- and bisaminophosphanes towards small molecules
Reactions of THF solutions of 1-6 with water under an ambient air atmosphere were
performed. Surprisingly, P-N bond hydrolysis was not observed. In the case of
aminophosphanes possessing PPh2 groups (2, 5), oxidation to the respective phosphane oxides
R2NP(=O)Ph2[71] occurred. The other aminophosphanes (1, 3, 4, 6) were stable under these
reaction conditions.

The structural features of aminophosphanes 1-6, where two or three Lewis basic centers
are surrounded by bulky substituents, encouraged us to test their reactivity as basic components
of FLPs in reactions with small molecules. Indeed, 1-6 formed “stable” FLPs with boranes such
as BPh3 or B(C6F5)3. According to 31P{1H} and 11B NMR spectroscopy, we did not observe the
formation of classic Lewis acid-base adducts or decomposition products in a benzene-d6
solution at room temperature. The FLPs of 1-6 with B(C6F5)3 were found to be active. Benzene-
d6 solutions containing each aminophosphane 1-6 and B(C6F5)3 were covered by a H2
atmosphere (1 atm) at room temperature. After overnight stirring, the formation of two phases
1
13
31
19
11
was observed, and their composition was determined by H, C, P{1H}, F{1H}, and B
spectroscopy. The upper phase consisted mainly of solvent and traces of unreacted
31
aminophosphane and borane. The P{1H} NMR spectrum of the lower oily phase contains
signals in the range of 15.5-33.9 ppm, which are significantly shifted upfield from the signals
1
from the parent aminophosphanes. Furthermore, the reaction products exhibited a large JP-H
value (495-534 Hz) characteristic of tetracoordinated P centers with P-H functions.[72] The 11B
NMR spectra of the lower oily phases displayed a doublet at approximately -25 ppm with a
19
1JB-H value of approximately 90 Hz, whereas the F{1H} spectrum contained three signals at
approximately -133 ppm, -164 ppm and -167 ppm. These NMR data are in agreement with
those reported for the [H-B(C6F5)3]- anion.[72] Collectively, the NMR spectroscopy data
indicated the formation of phosphonium borate salts with formulas [(R2N)2R’PH]+[HB(C6F5)3]-
(1a, 3a, 4a) or [(R2N)R’R’’PH]+[HB(C6F5)3]- (2a, 5a, 6a) as the main components of the lower
oily phases (Scheme 2). Notably, we did not observe the formation of the ammonium borate
salts [[(R2NH)(R2N)R’P]+[HB(C6F5)3]- or [(R2NH)R’R’’P]+[HB(C6F5)3]- similar to the
products of reactions of amine/borane FLPs with dihydrogen.[31] The observed reaction pattern
can be explained by better accessibility of the P lone pair than of the N lone pair (Figure 2) and
the fact that the latter pair is involved in π-interactions with phosphorus atoms.

H
P
N
R
R
H
R
R
N
N
P
N
R'
R
R'
R
H2
R
R
1 atm, 25 °C
B(C6F5)3
+
B(C6F5)3
1a (R= Pr, R'= Ph)
i
1 (R= Pr, R'= Ph)
i
3a (R= Pr, R'= Cy)
i
3 (R= Pr, R'= Cy)
i
4a (R= Cy, R'= Ph)
4 (R= Cy, R'= Ph)
R
H
P
R
R
N
P
H2
N
R''
R''
R
R'
R'
1 atm, 25 °C
+
H
B(C6F5)3
B(C6F5)3
2 (R= Pr, R'R''= Ph)
i
2a (R= Pr, R'R''= Ph)
i
5 (R= Cy, R'R''= Ph)
5a (R= Cy, R'R''= Ph)
6 (R= Cy, R'= Ph, R''= Pr)
i
6a (R= Cy, R'= Ph, R''= Pr)
i
Scheme 2 Activation of dihydrogen by aminophosphane/borane FLPs.
Generally, 1a-6a had a low tendency to crystallize; however, in the case of 1a, 3a, and
4a, small amounts of crystals suitable for X-ray analysis were obtained from pentane solution
at +4°C. The solid-state structures of 1a, 3a, and 4a are presented in Figure 3. X-ray analysis
confirmed the formation of phosphonium borate salts. Hydrogen atoms directly bound to
phosphorus and boron were found in the Fourier electron density map. In the structures of 1a
and 3a, the P-H and H-B functionalities face each other, with H···H distances of 3.44(3) Å and
2.53(5) Å, respectively. The H···H distances in 3a are significantly shorter than those observed
previously for [tBu3PH]+[HB(C6F5)3]- (2.75 Å).[72] The phosphonium cations 1a, 3a, and 4a
retain planar geometry at the nitrogen atoms but exhibit slightly shorter P-N bonds (1,625(2) Å
– 1.649(2) Å) than do the parent aminophosphanes (1.698(4) Å – 1.712(3) Å).

Figure 3 X-ray structures of the products of dihydrogen activation by aminophosphane/borane FLPs
(1a, 3a, and 4a) showing the atom-numbering scheme. All H atoms except for P-H and B-H have been
omitted for clarity.
FLPs 1-6 with B(C6F5)3 react with gaseous CO2 (1 atm) in benzene-d6 at room
temperature. The reactions involving 1, 3, 4 or 6 led to the formation of zwitterionic salts
(R2N)2R’PC(O)OB(C6F5)3 (1b, 3b, 4b) or (Cy2N)PhiPrPC(O)OB(C6F5)3 (6b) (Scheme 3).
Products 1b, 3b, and 4b precipitated from the reaction solution as a white solid. The mixture of
aminophosphanes containing PPh2 groups (2, 5) and B(C6F5)3 did not form stable adducts with
CO2. The products of these reactions decomposed rapidly to symmetrical Ph2P-PPh2 and a
complex mixture of unidentified compounds, which suggests that subsequent radical reactions
occurred in the reaction mixture. The identity of isolated CO2 activation products was
1
13
31
11
19
confirmed by means of H, C, P, B, F spectroscopy (1b, 3b, 4b, and 6b) and single-

crystal X-ray diffraction (1b). The 31P{1H} spectra of the mentioned products display singlets
11
in the range of 36.4 ppm – 50.2 ppm, whereas the B spectra show singlets between -3 ppm
and -2 ppm. Furthermore, characteristic downfield doublets attributed to the C=O group at
13
162.9 ppm – 163.9 ppm (1JC-P = 133.6 Hz – 178.4 Hz) are visible in the C spectra. These
spectroscopic data are in accord with the spectroscopic data of tBu3PC(O)OB(C6F5)3.[34]
R
O
O
N
P
N
C
P
N
B(C6F5)3
R
R
R'
R
CO2
R
N
R
R'
R
1 atm, 25 °C
R
+
B(C6F5)3
1b (R= Pr, R'= Ph)
i
1 (R= Pr, R'= Ph)
i
3b (R= Pr, R'= Cy)
i
3 (R= Pr, R'= Cy)
i
4b (R= Cy, R'= Ph)
4 (R= Cy, R'= Ph)
Cy
O
O
N
P
C
B(C6F5)3
Cy
Cy
CO2
Pr
i
Cy
Ph
N
P
1 atm, 25 °C
Pr
i
Ph
+
B(C6F5)3
6b
6
Scheme 3 Activation of carbon dioxide by aminophosphane/borane FLPs.
The X-ray structure of zwitterion 1b is depicted in Figure 4. The P1-C1 and B1-O1 distances,
with values of 1.899(2) Å and 1.535(3) Å, respectively, are very close to those observed for
zwitterionic species with the P-C(=O)O-B structural motif.[34] The P1 and B1 atoms exhibit
pseudotetrahedral geometries, whereas the geometries around the C1 atom of the CO2 moiety
and the N1 and N2 atoms of the amino groups are planar. Of note is that the FLPs of 1-6 with
BPh3 were found to be inactive towards hydrogen and carbon dioxide.

Figure 4 X-ray structures of the product of the activation of carbon dioxide by an
aminophosphane/borane FLP (1b) showing the atom-numbering scheme. H atoms have been omitted
for clarity.
Interestingly, despite the presence of highly polarized P-N in 1-6, the products of CO2
insertion into P-N bonds were not observed. The reactivity of aminophosphane/borane FLPs
towards CO2 is in strong contrast to the reactivity of diphosphane/borane FLPs, where CO2 was
inserted into a polarized P-P bond.[54] The reactions involving combinations of
aminophosphanes 1-6 and B(C6F5)3 with dihydrogen or carbon dioxide were not reversible. We
did not observe regeneration of the parent compounds even under vacuum or elevated
temperatures. It is worth mentioning that combinations of aminophosphanes with the weaker
Lewis acid BPh3 did not activate dihydrogen and carbon dioxide under the same mild
conditions.
Conclusions
Our studies reveal that aminophosphanes 1-6 possessing bulky substituents can be
successfully applied as basic components of frustrated Lewis pairs. These Lewis bases bearing
the P-N structural motif are relatively easy to synthesize and in contrast to the great majority of
aminophosphanes, they did not undergo oxidation or hydrolysis of the P-N bonds in ambient
air (except for 2 and 5 bearing the PPh2 group). These features make them attractive reagents
for the activation of small molecules. Indeed, the combinations of 1-6 and B(C6F5)3 form
“stable” FLPs that activate dihydrogen and carbon dioxide at room temperature and under 1
atm of gaseous reagents. The structural features of aminophosphanes such as the presence of
accessible lone pair at the P atom and the involvement of the lone pair at N atoms in π-
interactions with σ*(P) antibonding orbitals, explain their reactivity towards small molecules.
The reactions of FLPs containing aminophosphane as a basic component with H2 led to

phosphonium borate salts possessing P-H function, whereas reaction with CO2 led to the
formation of a new P-C bond. The less accessible lone pairs at N atoms did not interact with
small molecules, moreover, products of the insertion of small molecules into polarized P-N
bonds were not observed. The studies on the reactivity of products of H2 activation –
phosphonium borate salts with P-N structural motif – are currently in progress and will be
published due to course.
Materials and methods
All manipulations were performed under an Ar atmosphere in flame-dried Schlenk-type
glassware on a vacuum line or in a dry box. Solvents, tetrahydrofuran, and toluene were dried
over K/benzophenone and distilled under argon. Diethyl ether was dried over Na/benzophenone
and distilled under argon. Pentane and petroleum ether were dried over sodium-potassium alloy
and also distilled under argon. Solvents for NMR spectroscopy, C6D6, and CDCl3, were purified
with metallic sodium and P2O5, respectively. Literature methods were used for the synthesis of
(iPr2N)2PCl[73], (iPr2N)PCl2[74], (Cy2N)2PCl[75], Cy2N-PCl2[74]. B(C6F5)3, CyMgCl,
iPrMgCl, Ph2PCl, PhLi were purchased from commercial and used as received. NMR spectra
were recorded on a Bruker Avance III HD 400 MHz spectrometer at ambient temperature
(external standard TMS for 1H, 13C; H3PO4 for 31P, BF3·Et2O for 11B, CFCl3 for 19F). Data were
processed using Bruker's Topspin 3.5 software. For previously reported 1,[57] 2,[58] 4,[59] and
5[60] completed NMR data are provided.
Diffraction data of described compounds were collected on an IPDS 2T dual-beam
diffractometer (STOE&Cie GmbH, Darmstadt, Germany) at 120.0(2) K using MoKα radiation
of a microfocus X-ray source (GeniX 3D Mo HighFlux, Xenocs, Sassenage, France, 50 kV, 1.0
mA, λ = 0.71069 Å) for 1, 3, 5, 6, 1a, 3a, 4a, 1b) and CuKα radiation of a microfocus X-ray
source (GeniX 3D Cu HighFlux, Xenocs, 50 kV, 0.6 mA, λ = 1.54186 Å) for structures 2 and
5. Good quality single-crystal specimens of 1 – 6, 1a, 3a, 4a, and 1b were manually selected
for the X-ray diffraction experiments. The investigated crystal was thermostated in the nitrogen
stream at 120 K using CryoStream-800 device (Oxford CryoSystem, UK) during the entire
experiment. Data collection and data reduction were controlled by X-Area 1.75 program.[76]
The structures were solved with the Shelxt method[77,78] and refined using the program
packages Olex2[79,80] and SHELX-2014.[77,78] All non-hydrogen atoms were refined with
anisotropic displacement parameters. All H-atoms were refined with isotropic displacement

parameters. Hydrogen atoms were placed in idealized positions and refined with usual restraints
of the riding model, except P-H and B-H hydrogen atoms which were refined as an independent.
Specific details for individual structures: Structure 1 was refined with whole molecule
disordered over two positions with site occupation factors of 0.6103/0.3097(10). A similar
disorder was already reported for other aminophosphanes.[81] In order to stabilize positions of
chemically bonded atoms, restraints for N1-C and N2-C bond lengths were applied in both parts
to make them equal (SADI command). Similarly, restraints to make even bond lengths in C1-
C6 rings in both parts were added. Two structures, 2 and 4, were determined using the Cu X-
ray source (due to failure of Mo-lamp) and in those cases, absorption correction was performed,
being necessary. The structure of 2 was solved by SHELXT procedure and refined with the
SHELXL program with no special treatment. It just turned out to be necessary to omit two
reflections affected by beam stop holder shadow. The structure of 3 was also refined as
disordered with the whole molecule occupying two positions with a probability of
0.8154/0.1846(15). Similarly, as for 1, restraints for N-C and additionally on P-N bond lengths
in both parts of 3 were applied. Structure 4 turned out to contain two independent molecules in
the asymmetric unit, (Z = 8 in the space group P21/n) but required no special procedures for
determination (except omitting of two bad reflections). Structures of 5 and 6 were determined
using routine procedures. In the structure of 1a, we refined the structure with atom P1
disordered over two positions with site occupation factors of 0.8638/0.1362(18) to absorb a
relatively high electron density peak close to the atom. Due to the low occupation factor of the
second part, it would be speculative to determine the position of the rest light atoms in that part.
Hydrogen atoms in groups P1-H1 and B1-H1A were found in the Fourier electron density map
and refined without restraints. No disorder was found in structures 3a and 4a, and the same
procedure was applied for the determination of P-H and B-H hydrogen atom positions. Finally,
structure 1b was refined with a disorder of the isopropyl group C8-C9-C10 over two positions
with site occupation factors of 0.559/0.441(8).
For more crystallographic details see ESI. The crystal structure analyses were performed on an
STOE IPDS II diffractometer.
Elemental analysis was performed at the University of Gdańsk using a Vario El Cube CHNS
apparatus.
Synthesis procedures

Synthesis of (iPr2N)2PPh (1)
PhLi (2.15 mL, 4.0 mmol, 1.9 M in dibutyl ether) was added dropwise to a stirred solution of
(iPr2N)2PCl (1.080 g, 4.0 mmol) in Et2O (20 mL) at 0oC. The mixture was allowed to warm to
room temperature and stirred overnight. Filtration to remove the white precipitate, followed by
the removal of the solvent under reduced pressure, produced a light yellow residue. The crude
product was extracted with petroleum ether (6 mL) and filtered. Slow cooling of the resulting
solution to -20oC gave suitable crystals for X-ray diffraction. Yield: 0.890 g (71%).
Elemental analysis: Calc. for C18H33N2P: C: 70.09; H: 10.784; N: 9.08. Found: C: 70.05; H:
10.746; N: 9.04.
31P{1H} NMR (C6D6): δ 59.5 (s).
1H NMR (C6D6): δ 7.72 (tm, 3JH-H = 7.4 Hz, 2H, o-CH); 7.25 (td, 3JH-H= 7.4 Hz, 4JP-H = 2.2 Hz,
3
4
2H, m-CH); 7.10 (td, JH-H = 7.4 Hz, JH-H = 1.1 Hz, 1H, p-CH); 3.32 (dsept, 3JH-H = 6.6 Hz,
3JP-H = 2.2 Hz, 4H, CH(CH3)2); 1.24 (d, 3JH-H = 6.6 Hz, 12H, CH(CH3)2); 1.17 (d, 3JH-H = 6.6
Hz, 12H, CH(CH3)2).
13C{1H} NMR (C6D6): δ 145.1 (d, 1JC-P = 5.5 Hz, ipso-CP); 131.0 (d, 2JC-P = 21.1 Hz, o-CH);
3
4
2
127.6 (d, JC-P = 4.5 Hz, m-CH); 126.7 (d, JC-P = 1.8 Hz, p-CH); 47.7 (d, JC-P = 11.7 Hz,
CH(CH3)2); 24.2 (d, 3JC-P = 6.4 Hz, CH(CH3)2); 24.1 (d, 3JC-P = 7.9 Hz, CH(CH3)2).
Synthesis of (iPr2N)PPh2 (2)
Ph2PCl (3.14 mL, 17.5 mmol, 1.229 g/mL) in Et2O (5 mL) was added dropwise to a stirred
solution of iPr2NH (4.91 mL, 35.0 mmol, 0.722 g/mL) in Et2O (15 mL) at 0oC. The mixture
was allowed to warm to room temperature and stirred overnight. Filtration to remove the white
precipitate, followed by the removal of the solvent under reduced pressure, produced a light
yellow residue. The crude product was extracted with toluene (30 mL) and filtered. Slow
cooling of the resulting solution to -20oC gave suitable crystals for X-ray diffraction. Yield:
3.086 g (62%).
Elemental analysis: Calc. for C18H24NP: C: 75.76; H: 8.477; N: 4.91. Found: C: 75.47; H: 8.231;
N: 4.71.
31P{1H} NMR (C6D6): δ 37.9 (s).

1H NMR (C6D6): δ 7.58 (m, 4H, o-CH); 7.15 (m, 4H, m-CH, overlapped with solvent), 7.09
(m, 2H, p-CH); 3.29 (dsept, 3JH-H = 6.6 Hz, 3JP-H = 2.5 Hz, 2H, CH(CH3)2); 1.04 (d, 3JH-H = 6.6
Hz, 12H, CH(CH3)2).
13C{1H} NMR (C6D6): δ 141.0 (d, 1JC-P = 14.0 Hz, ipso-CP); 132.5 (d, 2JC-P = 20.5 Hz, o-CH);
128.0 (d, 3JC-P = 5.9 Hz, m-CH, overlapped with p-CH and solvent); 128.0 (s, p-CH, overlapped
2
3
with m-CH and solvent); 47.4 (d, JC-P = 9.1 Hz, CH(CH3)2); 23.6 ppm (d, JC-P = 6.7 Hz,
CH(CH3)2).
Synthesis of (iPr2N)2PCy (3)
CyMgCl (3.11 mL, 4.0 mmol, 1.3 M in THF) was added dropwise to a stirred solution of
(iPr2N)2PCl (1.080 g, 4.0 mmol) in THF (20 mL) at 0oC. The mixture was allowed to warm to
room temperature and stirred overnight. Filtration to remove the white precipitate, followed by
the removal of the solvent under reduced pressure, produced a light yellow residue. The crude
product was extracted with petroleum ether (20 mL) and filtered. Slow cooling of the resulting
solution to +4oC gave suitable crystals for X-ray diffraction. Yield: 0.608 g (48%).
Elemental analysis: Calc. for C18H39N2P: C: 68.74; H: 12.500; N: 8.91.Found: C: 68.51; H:
12.252; N: 8.83.
31P{1H} NMR (C6D6): δ 57.7 (s).
1H NMR (C6D6): δ 3.27 (dsept, 3JH-H = 6.6 Hz, 3JP-H = 3.4 Hz, 4H, CH(CH3)2); 2.02 – 1.66 (m,
6H, overlapped signals of CH or CH2 of Cy); 1.41 – 1.25 (m, 5H, overlapped signals of CH
3
3
and CH2 of Cy); 1.23 (d, JH-H = 6.6 Hz, 12H, CH(CH3)2); 12 (d, JH-H = 6.7 Hz, 12H,
CH(CH3)2).
13C{1H} NMR (C6D6): δ 46.9 (d, 2JC-P = 10.1 Hz, CH(CH3)2); 34.6 (s, CH of Cy); 30.6 (d, 2JC-
P = 21.5 Hz, CH2 of Cy); 27.4 (d, 3JC-P = 12.9 Hz, CH2 of Cy); 26.8 (bs, CH2 of Cy); 24.7 (d,
3JC-P = 6.6 Hz, CH(CH3)2); 24.2 (d, 3JC-P = 6.2 Hz, CH(CH3)2).
Synthesis of (Cy2N)2PPh (4)
PhLi (2.15 mL, 4.0 mmol, 1.9 M in dibutyl ether) was added dropwise to a stirred solution of
(Cy2N)2PCl (0.942 g, 4.0 mmol) in Et2O (15 mL) at 0oC. The mixture was allowed to warm to
room temperature and stirred overnight. Filtration to remove the white precipitate, followed by

the removal of the solvent under reduced pressure, produced a light yellow residue. The crude
product was extracted with toluene (15 mL) and filtered. Slow cooling of the resulting solution
to -20oC gave suitable crystals for X-ray diffraction. Yield: 0.704 g (38%).
Elemental analysis: Calc. for C30H49N2P: C: 76.88; H: 10.538; N: 5.98. Found: C: 76.62; H:
10.491; N: 5.90.
31P{1H} NMR (C6D6): δ 64.9 (s).
1H NMR (C6D6): δ 7.83 (tm, 3JH-H= 7.5 Hz, 2H, o-CH); 7.26 (td, 3JH-H= 7.5 Hz, 4JP-H= 1.9 Hz,
2H, m-CH); 7.09 (td, 3JH-H= 7.5 Hz, 4JH-H= 1.0 Hz, 1H, p-CH); 2.97 (m, 4H, overlapped signals
of CH of Cy); 2.00 – 0.95 (m, 40H, overlapped signals of CH2 of Cy).
13C{1H} NMR (C6D6): δ 145.7 (d, 1JC-P = 9.2 Hz, ipso-CP); 131.0 (d, 2JC-P = 21.9 Hz, o-CH);
3
4
2
127.5 (d, JC-P = 4.8 Hz, m-CH); 126.6 (d, JC-P = 1.3 Hz, p-CH); 57.7 (d, JC-P = 9.7 Hz,
4
overlapped signals of CH of Cy); 35.5 (d, JC-P = 6.3 Hz, overlapped signals of CH2 of Cy);
34.9 (d, 4JC-P = 7.5 Hz, overlapped signals of CH2 of Cy); 26.9 (d, 3JC-P = 17.5 Hz, overlapped
signals of CH2 of Cy); 25.8 (s, overlapped signals of CH2 of Cy).
Synthesis of (Cy2N)PPh2 (5)
PhLi (8.63 mL, 16.4 mmol, 1.9 M in dibutyl ether) was added dropwise to a stirred solution of
(Cy2N)PCl2 (2.31 g, 8.2 mmol) in Et2O (30 mL) at 0oC. The mixture was allowed to warm to
room temperature and stirred overnight. Filtration to remove the white precipitate, followed by
the removal of the solvent under reduced pressure, produced a light yellow residue. The crude
product was extracted with toluene (25 mL) and filtered. Slow cooling of the resulting solution
to -20oC gave suitable crystals for X-ray diffraction. Yield: 1.423 g (49%).
Elemental analysis: Calc. for C24H32NP: C: 78.87; H: 8.825; N: 3.83. Found: C: 79.07; H: 8.864;
N: 3.81.
31P{1H} NMR (C6D6): δ 41.3 (s).
1H NMR (C6D6): δ 7.66 (m, 4H, o-CH); 7.18 (m, 4H, m-CH, overlapped with solvent); 7.10 (m,
2H, p-CH, signals overlapped with solvent); 2.93 (m, 2H, overlapped signals of CH of Cy);
1.73 – 1.54 (m, 10H, overlapped signals of CH2 of Cy); 1.50 – 1.40 (bd, 2H, overlapped signals

of CH2 of Cy); 1.37 – 1.25 (m, 2H, overlapped signals of CH2 of Cy); 1.16 – 0.82 (m, 6H,
overlapped signals of CH2 of Cy).
13C{1H} NMR (C6D6): δ 141.5 (d, 1JC-P = 14.9 Hz, ipso-CP); 132.5 (d, 2JC-P = 20.5 Hz, o-CH);
128.0 (d, 3JC-P = 5.5 Hz, m-CH, overlapped p-CH and solvent); 128.0 (s, p-CH, overlapped with
m-CH and solvent); 57.0 (bs, CH of Cy); 34.9 (bs, CH2 of Cy); 26.5 (s, CH2 of Cy); 25.7 (s,
CH2 of Cy).
Synthesis of (Cy2N)P(iPr)Ph (6)
iPrMgCl (3.20 mL, 6.4 mmol, 2 M in Et2O) was added dropwise to a stirred solution of
(Cy2N)PCl2 (1.806 g, 6.4 mmol) in Et2O (35 mL) at 0oC. The mixture was allowed to warm to
room temperature and stirred overnight. Filtration to remove the white precipitate, followed by
the removal of the solvent under reduced pressure, produced a light yellow residue. The crude
product was extracted with toluene (15 mL) and filtered. Slow cooling of the resulting solution
to -20oC gave light yellow crystals of (Cy2N)P(iPr)Cl (1.254 g, 4.3 mmol, yield 67%). The
purity of the obtained product was confirmed by NMR spectroscopy. Thereafter, PhLi (2.26
mL, 4.3 mmol, 1.9 M in dibutyl ether) was added dropwise to a stirred solution of
(Cy2N)P(iPr)Cl (1.254 g, 4.3 mmol) in Et2O (25 mL) at 0oC. The mixture was allowed to warm
to room temperature and stirred overnight. Filtration to remove the white precipitate, followed
by the removal of the solvent under reduced pressure, produced a white residue. The crude
product was extracted with toluene (10 mL) and filtered. Slow cooling of the resulting solution
to -20oC gave suitable crystals for X-ray diffraction. Yield: 0.972 g (68%).
Elemental analysis: Calc. for C21H34NP: C: 76.09; H: 10.339; N: 4.23. Found: C: 76.09; H:
10.257; N: 4.20.
31P{1H} NMR (C6D6): δ 41.7 (s).
1H NMR (C6D6): δ 7.65 (tm, 3JH-H = 6.8 Hz, 2H, o-CH); 7.18 (m, 2H, m-CH, overlapped with
solvent); 7.11 (m, 1H, p-CH, overlapped with solvent); 2.79 (bs, 2H, overlapped signals of CH
of Cy); 2.35 (sept, 3JH-H = 6.8 Hz, 1H, CH(CH3)2), 1.78 – 1.44 (m, 10H, overlapped signals of
CH2 of Cy); 1.36 – 0.91 (m, 10H, overlapped signals of CH2 of Cy, overlapped with CH(CH3)2);
1.28 (dd, 3JP-H = 15.0 Hz, 3JH-H = 6.8 Hz, 3H, CH(CH3)2); 0.96 (dd, 3JP-H = 17.9 Hz, 3JH-H = 6.8
Hz, 3H, CH(CH3)2).

13C{1H} NMR (C6D6): δ 140.5 (d, 1JC-P = 22.4 Hz, ipso-CP); 132.8 (d, 2JC-P = 21.4 Hz, o-CH);
128.3 (bs, p-CH); 127.9 (d, 3JC-P = 6.2 Hz, m-CH); 34.9 (bs, CH of Cy); 26.7 (s, CH2 of Cy);
26.5 (s, CH2 of Cy); 25.7 (s, CH2 of Cy); 21.7 (d, 1JC-P = 6.36 Hz, CH(CH3)2); 19.8 (d, 2JC-P
19.8 Hz, CH(CH3)2); 18.2 (d, 2JC-P = 27.5 Hz, CH(CH3)2).
=
H2 activation
General procedure for H2 activation: appropriate aminophosphane (0.25 mmol) and B(C6F5)3
(0.128 g, 0.25 mmol) was dissolved in C6D6 (3 mL). The resulting reaction mixture was
subjected to a few freeze-pump-thaw cycles and subsequently exposed to 1 atm of H2 at 78 K.
The mixture was allowed to warm to room temperature and stirred overnight. After that time,
two phases could be seen.
The oil phase was separated and the volatiles were removed in vacuo. The residue was extracted
with pentane (3 mL). Slow cooling of resulting solution to +4oC gave small amount of crystals
of 1a, 3a, and 4a suitable for X-ray diffraction.
Samples, obtained by the dissolution of 1a – 6a oil phase (0.1 mL) in CDCl3 (0.6 mL), were
measured via NMR spectroscopy. Given yield refers to the amount of obtained oil phase.
Synthesis of [(iPr2N)2PhPH]+[HB(C6F5)3]- (1a)
Yield: 0.186 g (90%).
Elemental analysis: Calc. for C36H35BF15N2P: C: 52.57; H: 4.289; N: 3.41. Found: C: 52.10; H:
4.348; N: 3.45.
31P{1H} NMR (CDCl3): δ 17.0 (s) (1JP-H = 534.0 Hz).
11B NMR (CDCl3): δ -25.0 (bd, 1JB-H = 89.4 Hz).
1H NMR (CDCl3): δ 7.96 (d, 1JP-H = 534.0 Hz, 1H, PH); 7.91 – 7.70 (m, 5H, overlapped signals
of o-CH, m-CH, and p-CH); 4.15 (bd, 1JB-H = 89.4 Hz, 1H, BH); 3.78 (dsept, 3JH-H = 6.9 Hz,
3JP-H = 3.3 Hz, 4H, CH(CH3)2); 1.42 (d, 3JH-H = 6.9 Hz, 12H, CH(CH3)2); 1.29 (d, 3JH-H = 6.9
Hz, 12H, CH(CH3)2).
19F {1H} NMR (CDCl3): δ -133.1 (d, 3JF-F = 19.2 Hz, 6F, o-C6F5); -163.8 (t, 3JF-F = 20.4 Hz, 3F,
p-C6F5); -166.8 (td, 3JF-F = 22.3 Hz, 4JF-F = 7.0 Hz, 6F, m-C6F5 ).

13C{1H} NMR (CDCl3): δ 148.4 (dm, 1JC-F = 236.3 Hz, o-CF); 138.0 (dm, 1JC-F = 245.8 Hz, p-
CF); 136.6 (dm, 1JC-F = 246.5 Hz, m-CF); 135.8 (d,4JC-P = 3.25 Hz, p-CH); 131.5 (d, 3JC-P = 13.9
Hz, m-CH); 130.4 (d, 2JC-P = 14.9 Hz, o-CH); 125.4 (bs, ipso-CB); 123.0 (d, 1JC-P = 124.3 Hz,
ipso-CP); 48.3 (d, 2JC-P = 4.7 Hz, CH(CH3)2); 22.9 (d, 3JC-P = 2.7 Hz, CH(CH3)2); 22.0 (d, 3JC-P
= 3.1 Hz, CH(CH3)2).
Synthesis of [(iPr2N)Ph2PH]+[HB(C6F5)3]- (2a)
Yield: 0.178 g (89%).
Elemental analysis: Calc. for C36H26BF15NP: C: 54.09; H: 3.278; N: 1.75. Found: C: 54.17; H:
3.332; N: 1.59.
31P{1H} NMR (CDCl3): δ 15.5 (s) (1JP-H = 519.0 Hz).
11B NMR (CDCl3): δ -24.7 (bd, 1JB-H = 88.2 Hz).
1H NMR (CDCl3): δ 8.50 (d, 1JP-H = 519.0 Hz, 1H, PH); 7.95 – 7.88 (m, 2H overlapped signals
of o-CH, m-CH, and p-CH); 7.80 – 7.73 (m, 7H, overlapped signals of o-CH, m-CH, and p-
CH); 7.52 – 7.35 (m, 1H, overlapped signals of o-CH, m-CH, and p-CH); 4.09 (bd, 1JB-H = 88.2
Hz, 1H, BH); 3.73 (dsept, 3JH-H = 6.7 Hz, 3JP-H = 3.2 Hz, 2H, CH(CH3)2); 1.37 (d, 3JH-H = 6.7
Hz, 9H, CH(CH3)2).
19F {1H} NMR (CDCl3): δ -133.1 (d, 3JF-F = 19.7 Hz, 6F, o-C6F5); -163.3 (t, 3JF-F = 20.4 Hz, 3F,
p-C6F5); -166.4 (td, 3JF-F = 22.3 Hz, 4JF-F = 7.1 Hz, 6F, m-C6F5 ).
13C{1H} NMR (CDCl3): δ 148.3 (dm, 1JC-F = 234.3 Hz, o-CF); 138.1 (dm, 1JC-F = 243.9 Hz, p-
1
3
CF); 136.6 (dm, JC-F = 249.0 Hz, m-CF); 136.2 (s, p-CH); 133.1 (d, JC-P = 12.6 Hz, m-CH);
130.7 (d, 2JC-P = 13.9 Hz, o-CH); 124.9 (bs, ipso-CB); 117.8 (d, 1JC-P = 99.5 Hz, ipso-CP); 48.8
(s, CH(CH3)2); 22.4 (bs, CH(CH3)2); 19.1 (s, CH(CH3)2
Synthesis of [(iPr2N)2CyPH]+[HB(C6F5)3]- (3a)
Yield: 0.192 g (93%).
Elemental analysis: Calc. for C36H41BF15N2P: C: 52.19; H: 4.988; N: 3.38. Found: C: 51.63; H:
4.923; N: 3.30.
31P{1H} NMR (CDCl3): δ 28.2 (s) (1JP-H = 519.4 Hz).

11B NMR (CDCl3): δ -25.0 (bd, 1JB-H = 91.5 Hz).
1H NMR (CDCl3): δ 6.83 (dd, 1JP-H = 519.4 Hz, 3JH-H = 7.5 Hz, 1H, PH); 3.97 (bd, 1JB-H = 91.5
3
3
Hz, 1H, BH, overlapped with CH(CH3)2); 3.67 (dsept, JH-H = 6.8 Hz, JP-H = 1.9 Hz, 2H,
CH(CH3)2); 2.60 (bs, 1H, CH of Cy); 2.14 – 1.88 (m, 5H, overlapped signals of CH or CH2 of
Cy); 1.56 – 1.29 (m, 5H, overlapped signals of CH or CH2 of Cy, overlapped with CH(CH3)2);
1.43 (d, 3JH-H = 6.8 Hz, 12H, CH(CH3)2); 1.38 (d, 3JH-H = 6.8 Hz, 12H, CH(CH3)2).
19F {1H} NMR (CDCl3): δ -133.0 (d, 3JF-F = 19.6 Hz, 6F, o-C6F5); -163.9 (t, 3JF-F = 20.1 Hz, 3F,
p-C6F5); -166.8 (td, 3JF-F = 21.3 Hz, 4JF-F = 6.9 Hz, 6F, m-C6F5 ).
13C{1H} NMR (CDCl3): δ 148.5 (dm, 1JC-F = 237.5 Hz, o-CF); 138.0 (dm, 1JC-F = 243.2 Hz, p-
1
2
CF); 136.6 (dm, JC-F = 245.6 Hz, m-CF); 125.5 (bs, ipso-CB); 49.2 (d, JC-P = 2.8 Hz,
CH(CH3)2); 34.7 (d, 1JC-P = 82.3 Hz, PCH of Cy); 28.3 (s, CH2 of Cy); 26.3 (d, 2JC-P = 17.2 Hz,
CH2 of Cy); 25.0 (bs, CH2 of Cy); 23.2 (d, 3JC-P = 2.7 Hz, CH(CH3)2); 23.2 (d, 3JC-P = 2.0 Hz,
CH(CH3)2).
Synthesis of [(Cy2N)2PhPH]+[HB(C6F5)3]- (4a)
Yield: 0.205 g (84%).
31P{1H} NMR (CDCl3): δ 19.0 (s) (1JP-H = 538.7 Hz, 3JP-H = 14.7 Hz).
11B NMR (CDCl3): δ -24.9 (bd, 1JB-H = 89.7 Hz).
1H NMR (CDCl3): δ 8.12 (d, 1JP-H = 538.7 Hz, 1H, PH); 7.92 – 7.82 (m, 3H, overlapped signals
of m-CH, and p-CH); 7.73 (m, 2H, o-CH); 4.00 (bd, 1JB-H = 91.5 Hz, 1H, BH); 3.33 (m, 4H,
CH of Cy); 2.05 – 1.95 (m, 8H, overlapped signals of CH2 of Cy); 1.95 – 1.85 (m, 4H,
overlapped signals of CH2 of Cy); 1.81 – 1.66 (m, 12H, overlapped signals of CH2 of Cy); 1.66
– 1.52 (m, 4H, overlapped signals of CH2 of Cy); 1.47 – 1.23 (m, 8H, overlapped signals of
CH2 of Cy); 1.23 – 1.08 (m, 4H, overlapped signals of CH2 of Cy).
19F {1H} NMR (CDCl3): ): δ -132.9 (d, 3JF-F = 20.2 Hz, 6F, o-C6F5); -164.0 (t, 3JF-F = 20.4 Hz,
3F, p-C6F5); -166.8 (td, 3JF-F = 22.0 Hz, 4JF-F = 7.0 Hz, 6F, m-C6F5 ).
13C{1H} NMR (CDCl3): δ 148.4 (bd, 1JC-F = 242.8 Hz, o-CF); 138.0 (bd, 1JC-F = 243.8 Hz, p-
CF); 136.6 (bd, 1JC-F = 250.6 Hz, m-CF); 135.6 (d, 4JC-P = 2.8 Hz, p-CH); 131.5 (d, 3JC-P = 14.2
Hz, m-CH); 130.2 (d, 2JC-P = 15.2 Hz, p-CH); 125.6 (bs, ipso-CB); 123.8 (d, 1JC-P = 123.6 Hz,

ipso-CP); 57.6 (d, 2JC-P = 3.6 Hz, CH of Cy); 34.0 (bs, overlapped signals of CH2 of Cy); 33.1
(bs, overlapped signals of CH2 of Cy); 26.3 (s, overlapped signals of CH2 of Cy); 26.2 (s,
overlapped signals of CH2 of Cy); 24.8 (s, overlapped signals of CH2 of Cy).
Synthesis of [(Cy2N)Ph2PH]+[HB(C6F5)3]- (5a)
Yield: 0.198 g (90%).
Elemental analysis: Calc. for C42H34BF15NP: C: 57.36; H: 3.897; N: 1.59. Found: C: 57.29; H:
4.081; N: 1.21.
31P{1H} NMR (CDCl3): δ 16.1 (s) (1JP-H = 521.4 Hz).
11B NMR (CDCl3): δ -25.0 (bd, 1JB-H = 89.9 Hz).
1
1H NMR (CDCl3): δ 8.30 (d, JP-H = 521.4 Hz, 1H, PH); 7.64 – 7.40 (m, 10H, overlapped
signals of o-CH, m-CH, and p-CH); 3.69 (bd, 1JB-H = 89.9 Hz, 1H, BH); 2.99 (m, 2H, CH of
Cy); 1.70 – 1.31 (m, 14H, overlapped signals of CH2 of Cy); 1.12 – 0.80 (m, 6H, overlapped
signals of CH2 of Cy).
19F {1H} NMR (CDCl3): δ -133.3 (d, 3JF-F = 18.8 Hz, 6F, o-C6F5); -163.6 (t, 3JF-F = 20.1 Hz, 3F,
p-C6F5); -166.7 (td, 3JF-F = 22.3 Hz, 4JF-F = 7.3 Hz, 6F, m-C6F5).
13C{1H} NMR (CDCl3): δ 148.1 (dm, 1JC-F = 232.1 Hz, o-CF); 137.7 (dm, 1JC-F = 243.2 Hz, p-
CF); 136.4 (dm, 1JC-F = 247.5 Hz, m-CF); 135.8 (s, p-CH); 132.8 (d, 3JC-P = 12.4 Hz, m-CH);
130.2 (d, 2JC-P = 13.7 Hz, o-CH); 124.7 (bs, ipso-CB); 117.9 (d, 1JC-P = 99.5 Hz, ipso-CP); 57.3
(s, CH of Cy); 33.2 (s, overlapped signals of CH2 of Cy); 29.5 (s, overlapped signals of CH2 of
Cy); 25.6 (s, overlapped signals of CH2 of Cy); 24.4 (s, overlapped signals of CH2 of Cy); 23.9
(s, overlapped signals of CH2 of Cy).
Synthesis of [(Cy2N)(iPr)PhPH]+[HB(C6F5)3]- (6a)
Yield: 0.186 g (88%).
31P{1H} NMR (CDCl3): δ 33.9 (s) (1JP-H = 494.5 Hz).
11B NMR (CDCl3): δ -24.7 (bd, 1JB-H = 89.8 Hz).

1H NMR (CDCl3): δ 7.89 – 7.66 (m, 5H, overlapped signals of o-CH, m-CH, and p-CH); 7.37
(dd, 1JP-H = 494.5 Hz, 3JH-H = 9.4 Hz, 1H, PH); 3.97 (bd, 1JB-H = 89.8 Hz, 1H, BH); 3.38 – 2.91
(m, 3H, overlapped signals of CH of Cy, and CH(CH3)2); 2.02 – 1.01 (m, 26H, overlapped
signals of CH2 of Cy, and CH(CH3)2).
19F {1H} NMR (CDCl3): δ -133.1 (d, 3JF-F = 19.0 Hz, 6F, o-C6F5); -163.4 (t, 3JF-F = 20.3 Hz, 3F,
p-C6F5); -166.5 (td, 3JF-F = 22.6 Hz, 4JF-F = 7.2 Hz, 6F, m-C6F5 ).
13C{1H} NMR (CDCl3): δ 148.4 (dm, 1JC-F = 237.1 Hz, o-CF); 138.0 (dm, 1JC-F = 243.5 Hz, p-
CF); 136.7 (dm, 1JC-F = 247.8 Hz, m-CF); 135.8 (d, 4JC-P = 2.7 Hz, p-CH); 137.7 (d, 3JC-P = 10.5
2
1
Hz, m-CH); 130.7 (d, JC-P = 12.6 Hz, o-CH); 125.0 (bs, ipso-CB); 119.6 (d, JC-P = 85.8 Hz,
ipso-CP); 57.7 (d, 2JC-P = 1.7 Hz, CH of Cy); 33.6 (d, 3JC-P = 15.2 Hz, CH2 of Cy); 25.9 (s, CH2
2
3
of Cy); 24.6 (s, CH2 of Cy); 22.3 (d, JC-P = 60.6 Hz, CH(CH3)2); 16.8 (d, JC-P = 2.4 Hz,
CH(CH3)2); 16.4 (d, 3JC-P = 2.6 Hz, CH(CH3)2).
CO2 activation
General procedure for CO2 activation: appropriate aminophosphane (0.25 mmol) and
B(C6F5)3 (0.128 g, 0.25 mmol) was dissolved in C6D6 (3 mL). The resulting reaction mixture
was subjected to a few freeze-pump-thaw cycles and subsequently exposed to 1 atm of CO2 at
78 K. The mixture was allowed to warm to room temperature and stirred overnight. After that
time, in the case of the reaction of 1, 3, and 4 aminophosphane, white solid precipitated.
The solvent was evaporated and the volatiles were removed in vacuo. The residue was extracted
with petroleum ether (4 mL) and filtrated. The solvent was evaporated and the crude product
was extracted with CH2Cl2 (1 mL). Slow cooling of resulting solution to -30oC gave suitable
crystals of 1b for X-ray diffraction in a low yield.
Samples, obtained by the dissolution of 1b, 3b, and 4b white solid (0.020 g) in CDCl3 (0.7 mL)
and the sample of 6b fraction in C6D6, were measured via NMR spectroscopy. Given yield
refers to the amount of obtained white solid.
Synthesis of (iPr2N)2PhPC(O)OB(C6F5)3 (1b)
Yield: 0.121 g (56%).
31P{1H} NMR (CDCl3): δ 36.4 (s).

11B NMR (CDCl3): δ -2.6 (s).
1H NMR (CDCl3): δ 7.96 (dd, 3JP-H = 13.2 Hz, 3JH-H = 7.5 Hz, 2H, o-CH); 7.68 (tm, 3JH-H = 7.5
Hz, 1H, p-CH); 7.46 (td, 3JH-H= 7.5 Hz, 4JP-H = 3.8 Hz, 2H, m-CH); 2.50 (sept, 3JH-H= 6.8 Hz,
3
3
4H, CH(CH3)2); 1.24 (d, JH-H = 6.8 Hz, 12H, CH(CH3)2); 1.11 (d, JH-H = 6.8 Hz, 3H,
CH(CH3)2).
19F {1H} NMR (CDCl3): δ -135.6 (bd, 3JF-F = 22.3 Hz, 6F, o-C6F5); -159.9 (t, 3JF-F = 20.4 Hz,
3F, p-C6F5); -165.4 (btd, 3JF-F = 22.9 Hz, 4JF-F = 7.6 Hz, 6F, m-C6F5 ).
1
1
13C{1H} NMR (CDCl3): δ 163.9 (d, JC-P = 175.2 Hz, C=O); 147.8 (dm, JC-F = 242.4 Hz, o-
CF); 139.3 (dm, 1JC-F = 241.5 Hz, p-CF); 136.7 (dm, 1JC-F = 249.1 Hz, m-CF); 135.2 (d, 4JC-P
=
2.9 Hz, p-CH); 134.8 (d, 3JC-P = 11.7 Hz, o-CH); 128.8 (d, 2JC-P = 13.4 Hz, m-CH); 121.3 (d,
1JC-P = 107.7 Hz, ipso-CP); 119.5 (bs, ipso-CB); 50.0 (d, 2JC-P = 5.2 Hz, CH(CH3)2); 23.8 (d,
3JC-P = 3.2 Hz, CH(CH3)2); 23.7 (d, 3JC-P = 2.6 Hz, CH(CH3)2).
Synthesis of (iPr2N)2CyPC(O)OB(C6F5)3 (3b)
Yield: 0.149 g (68%).
31P{1H} NMR (CDCl3): δ 50.2 (s).
11B NMR (CDCl3): δ -2.8 (s).
1H NMR (CDCl3): δ 3.68 (dsept, 3JH-H = 6.8 Hz, 3JP-H = 2.6 Hz, 4H, CH(CH3)2); 2.23 (m, 1H,
CH of Cy); 2.09 (m, 2H, CH2 of Cy); 1.83 (m, 2H, CH2 of Cy); 1.68 (m, 2H, CH2 of Cy); 1.26
(m, 24H, CH(CH3)2); 1.22 – 1.06 (m, 4H, overlapped signals of CH2 of Cy);.
19F {1H} NMR (CDCl3): δ -133.5 (bd, 3JF-F = 22.8 Hz, 6F, o-C6F5); -159.9 (t, 3JF-F = 20.5 Hz,
3F, p-C6F5); -165.4 (btd, 3JF-F = 23.3 Hz, 4JF-F = 7.4 Hz, 6F, m-C6F5 ).
1
1
13C{1H} NMR (CDCl3): δ 163.6 (d, JC-P = 164.2 Hz, C=O); 147.8 (dm, JC-F = 238.8 Hz, o-
CF); 139.3 (dm, 1JC-F = 241.4 Hz, p-CF); 136.7 (dm, 1JC-F = 261.3 Hz, m-CF); 119.7 (bs, ipso-
CB); 49.7 (d, 2JC-P = 3.9 Hz, CH(CH3)2); 38.4 (d, 1JC-P = 61.3 Hz, PCH of Cy); 28.3 (s, CH2 of
Cy); 26.7 (d, 2JC-P = 14.4 Hz, CH2 of Cy); 26.1 (d, 2JC-P = 2.75 Hz, CH2 of Cy); 25.4 (d, 2JC-P
1.76 Hz, CH2 of Cy); 24.5 (d, 3JC-P = 2.9 Hz, CH(CH3)2); 24.4 (d, 3JC-P = 3.8 Hz, CH(CH3)2).
=
Synthesis of (Cy2N)2PhPC(O)OB(C6F5)3 (4b)

Yield: 0.164 g (64%).
31P{1H} NMR (CDCl3): δ 39.9 (s).
11B NMR (CDCl3): δ -2.7 (s).
1H NMR (CDCl3): δ 7.79 (dd, 3JP-H = 12.8 Hz, 3JH-H = 7.8 Hz, 2H, o-CH); 7.65 (bt, 3JH-H = 7.8
Hz, 1H, p-CH); 7.36 (td, 3JH-H= 7.8 Hz, 4JP-H = 3.7 Hz, 2H, m-CH); 3.27 (m, 4H, CH of Cy);
1.91 – 1.84 (m, 4H, overlapped signals of CH2 of Cy); 1.68 – 1.48 (m, 24H, overlapped signals
of CH2 of Cy); 1.07 – 0.92 (m, 12H, overlapped signals of CH2 of Cy).
19F {1H} NMR (CDCl3): δ -132.8 (bd, 3JF-F = 21.5 Hz, 6F, o-C6F5); -160.1 (t, 3JF-F = 20.5 Hz,
3F, p-C6F5); -165.3 (m, 6F, m-C6F5).
1
1
13C{1H} NMR (CDCl3): δ 162.9 (d, JC-P = 178.4 Hz, C=O); 147.8 (dm, JC-F = 245.9 Hz, o-
CF); 139.4 (dm, 1JC-F = 249.5 Hz, p-CF); 136.7 (dm, 1JC-F = 251.6 Hz, m-CF); 134.6 (d, 4JC-P
=
3
2
2.3 Hz, p-CH); 134.4 (d, JC-P = 11.2 Hz, o-CH); 128.5 (d, JC-P = 13.0 Hz, m-CH); 122.1 (d,
2
1JC-P = 106.6 Hz, ipso-CP); 119.3 (bs, ipso-CB); 59.2 (d, JC-P = 4.4 Hz, CH of Cy); 35.0 (d,
3JC-P = 2.7 Hz, overlapped signals of CH2 of Cy); 26.8 (d, 3JC-P = 5.0 Hz, overlapped signals of
CH2 of Cy); 25.2 (s, overlapped signals of CH2 of Cy).
Synthesis of (Cy2N)(iPr)PhPC(O)OB(C6F5)3 (6b)
31P{1H} NMR (C6D6): δ 39.1 (s).
11B NMR (C6D6): δ -2.1 (s).
1H NMR (C6D6): δ 7.41 (dd, 3JP-H = 11.9 Hz, 3JH-H = 7.4 Hz, 2H, o-CH); 7.02 (td, 3JH-H = 7.4
Hz, 4JH-H = 1.6 Hz, 1H, p-CH); 6.92 (td, 3JH-H= 7.4 Hz, 4JP-H = 3.5 Hz, 2H, m-CH); 2.80 (m, 2H,
CH of Cy); 2.50 (sept, 3JH-H = 6.9 Hz, 1H, CH(CH3)2); 1.78 – 1.63 (m, 2H, overlapped signals
of CH2 of Cy); 1.49 – 1.35 (m, 6H, overlapped signals of CH2 of Cy); 1.34 – 1.26 (m, 2H,
overlapped signals of CH2 of Cy); 1.10 – 0.81 (m, 8H, overlapped signals of CH2 of Cy,
overlapped with CH(CH3)2); 0.99 (dd, 3JP-H = 19.5 Hz, 3JH-H = 6.9 Hz, 3H, CH(CH3)2); 0.96 (dd,
3JP-H = 18.1 Hz, 3JH-H = 6.9 Hz, 3H, CH(CH3)2).
19F {1H} NMR (C6D6): δ -133.4 (bd, 3JF-F = 21.5 Hz, 6F, o-C6F5); -159.4 (t, 3JF-F = 20.7 Hz, 3F,
p-C6F5); -165.1 (btd, 3JF-F = 23.4 Hz, 4JF-F = 8.2 Hz, 6F, m-C6F5 ).

13C{1H} NMR (C6D6): δ 163.1 (d, 1JC-P = 133.6 Hz, C=O); 148.2 (dm, 1JC-F = 247.1 Hz, o-CF);
139.6 (dm, 1JC-F = 248.0 Hz, p-CF); 137.1 (dm, 1JC-F = 250.4 Hz, m-CF); 134.8 (d, 4JC-P = 2.6
Hz, p-CH); 133.4 (d, 3JC-P = 9.3 Hz, o-CH); 128.9 (d, 2JC-P = 11.8 Hz, m-CH); 119.9 (bs, ipso-
CB); 118.2 (d, 1JC-P = 84.1 Hz, ipso-CP); 60.3 (s, CH of Cy); 34.3 (s, overlapped signals of CH2
of Cy); 33.3 (s, overlapped signals of CH2 of Cy); 26.6 (d, 3JC-P = 20.6 Hz, overlapped signals
of CH2 of Cy); 26.2 (d, 3JC-P = 16.7 Hz, overlapped signals of CH2 of Cy); 25.5 (s, CH(CH3)2);
3
24.8 (s, overlapped signals of CH2 of Cy); 16.4 (d, JC-P = 2.6 Hz, CH(CH3)2); 15.7 (s,
CH(CH3)2).
Appendix A. Supplementary data
CCDC 2003084 – 2003093 contains the supplementary crystallographic data for 1-6, 1a, 3a,
4a,
and
6b.
These
data
can
be
obtained
free
of
charge
via
http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
Acknowledgments
R.G., K.K., and N.S. thank the National Science Centre NCN, Poland (Grant
2016/21/B/ST5/03088) for their financial support. The authors thank TASK Computational
Center for access to computational resources.
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