Synthesis of the first representatives of amino bis(picolyl) and amino bis(quinaldinyl) phosphines Dedicated to Professor Peter Klüfers on the occasion of his 65th birthday

Article abstract of DOI:10.1016/j.tet.2016.04.021

First amino bis(picolyl) and amino bis(quinaldinyl) phosphines were synthesized by reaction of the corresponding amino dichlorophosphines - the new carbazolyl dichlorophosphine (1) and diisopropylamino dichlorophosphine (2) with either picolylTMS (6), qui

Full text of DOI:10.1016/j.tet.2016.04.021

Tetrahedron 72 (2016) 3162e3170
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Synthesis of the first representatives of amino bis(picolyl) and
amino bis(quinaldinyl) phosphines
*
€
Christina Hettstedt, Pia Kostler, Erol Ceylan, Konstantin Karaghiosoff
Ludwig-Maximilians University, Butenandtstr. 5-13, 81377 Munich, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
First amino bis(picolyl) and amino bis(quinaldinyl) phosphines were synthesized by reaction of the
corresponding amino dichlorophosphines e the new carbazolyl dichlorophosphine (1) and diisopropy-
lamino dichlorophosphine (2) with either picolylTMS (6), quinaldinylTMS (15) or their respective lithium
derivatives 12 and 16. The deviation of the standard synthesis via the silyl route is necessary for the
synthesis of the diisopropylamino derivatives 11 and 14 due to the fact that compound 2 is not reacting
with 6 or 15 even at reflux conditions. All new compounds are extensively characterized by multinuclear
NMR spectroscopy and some also by single crystal X-ray diffraction. Also the molecular and crystal
structure of the new dichlorophosphine 1 was determined.
Received 16 February 2016
Received in revised form 5 April 2016
Accepted 6 April 2016
Available online 16 April 2016
€
Dedicated to Professor Peter Klufers on the
occasion of his 65th birthday
Ó 2016 Elsevier Ltd. All rights reserved.
Keywords:
Amino dichlorophosphine
Aminophosphine
Bis(picolyl) phosphine
Bis(quinaldinyl) phosphine
Dismutation
1. Introduction
substituents at phosphorus are attached to it by a covalent PeC
bond.
PN-Ligands are due to the soft phosphorus and hard nitrogen
coordination site interesting and highly desirable multidentate and
hemilable ligands that show a huge variety of coordination pat-
terns.1 Transition metal complexes of such ligands display catalytic
properties and can be potentially used for a great number of cata-
lyzed reactions.2 One possibility to design a molecule with this
structural motive is to attach one, two3 or three4 picolyl
(¼C5H4Ne2eCH2-) moieties to phosphorus. The picolyl sub-
stituent, with its methylene group as a spacer between the pyridine
ring and the phosphorus atom provides also geometrical flexibility
for this compound as a ligand. Currently only a hand full of de-
rivatives of bis(picolyl) phosphines are known in literature.3 In our
recent work on the synthesis and characterization of methox-
yphenyl substituted bis(picolyl) phosphines we presented a de-
tailed overview of the available bis(picolyl) phosphines and some of
their metal complexes and added our own work to the existing li-
brary of derivatives.3b In all available bis(picolyl) phosphines, all
Here we present the synthesis of first amino substituted
bis(picolyl) and bis(quinaldinyl) phosphines starting from the new
carbazolyl dichlorophosphine (1) and diisopropylamino dichlor-
ophosphine (2). In these compounds, the aminofunctionality at
phosphorus is anticipated to significantly influence the competing
PN coordination of the ligands. The synthesis of the hitherto un-
known carbazolyl dichlorophosphine (1) is also reported. All new
compounds are characterized by multinuclear (1H, 13C, 31P) NMR
spectroscopy and some of them also by single crystal X-ray
diffraction.
2. Results and discussion
2.1. Syntheses
2.1.1. Synthesis of the dichlorophosphines 1e4. The new carbazolyl
dichlorophosphine (1) was synthesized applying the literature
procedure for the preparation of iPr2NPCl2 (2),5 Ph2NPCl2 (3)5 and
Bn2NPCl2 (4).6 The reaction started from carbazole, which was
allowed to react with PCl3 and TEA to form the dichlorophosphine 1
in 53% yield (Scheme 1). Dichlorophosphines 2e4 were prepared
analogously. Dichlorophosphine 1 was isolated as a colorless to
* Corresponding author. Tel.: þ49 89 2180 77426; e-mail address: konstantin.
Karaghiosoff@cup.uni-muenchen.de (K. Karaghiosoff).
http://dx.doi.org/10.1016/j.tet.2016.04.021
0040-4020/Ó 2016 Elsevier Ltd. All rights reserved.

C. Hettstedt et al. / Tetrahedron 72 (2016) 3162e3170
3163
yellow crystalline solid which, due to similar solubility properties,
was always accompanied by traces of the starting material carba-
zole. Compound 1 is highly sensitive towards humidity and it is
highly soluble in polar solvents like DCM, THF and MeCN. It is
sparingly soluble in Et2O and pentane. The identity of dichlor-
ophosphine 1 was doubtlessly confirmed by multinuclear NMR
spectroscopy and single crystal X-ray diffraction. Also the crystal
structure of 3 was determined. The analytical data of 2e4 compare
well with those from the literature.5,6
yields in equilibrium the chlorophosphine 8 and PCl3. From all in
the reaction mixture present chlorophosphines, PCl3 as the most
reactive one preferentially undergoes substitution with PicTMS (6)
to give 9. Most probably 9 undergoes similar dismutation to give 7
and again PCl3 (Scheme 3).
To confirm this mechanism, the formation and dismutation
abilities of 9 were investigated separately. Dichlorophosphine 9
can quantitatively be synthesized according to eq. (2) Scheme 3 at
ꢀ78 ꢁC. Upon removal of the solvent (THF) at ambient tempera-
ture, almost quantitative dismutation occurs to form chlor-
ophosphine 10 and PCl3, which simultaneously was removed in
vacuo.
The fast and easy dismutation of PicPCl2 (9) is remarkable, as the
corresponding benzyldichlorophosphine BnPCl2 is a stable and
distillable (at 60 ꢁC) compound.9 This observation underlines the
special properties of the benzylic position in 2-picoline.
For the synthesis of diisopropylamino bis(picolyl) phosphine
(11) picolyl-lithium (12) which was obtained by metalation of 2-
picoline with nBuLi, was directly reacted with the dichlor-
ophosphine 2 (Scheme 4).
The separation of the LiCl formed during the reaction was not
trivial, due to the bad solubility of 11 in solvents that do not dissolve
the salt (pentane, toluene). Nevertheless, we were able to isolate 11
as yellow solid by extraction with pentane (32%). Phosphine 11 is
highly sensitive towards oxidation in air.
Scheme 1. Synthesis of the amino dichlorophosphines 1e4 starting from the corre-
sponding secondary amines.
2.1.2. Synthesis of the amino bis(picolyl) and amino bis(quinaldinyl)
phosphines. Carbazolyl bis(picolyl) phosphine (5) was synthesized
by the reaction of the dichlorophosphine 1 with the twofold
amount of PicTMS (6) (Pic¼C5H4Ne2eCH2) in THF following
a procedure described in the literature (Scheme 2).3b,7 Phosphine 5
was isolated as colorless to yellowish solid by extraction of the
crude product with dry Et2O in very good yield (92%). It was highly
soluble in Et2O and other polar and aprotic solvents like THF and
MeCN. Compound 5 is highly sensitive towards oxidation in air.
Carbazolyl bis(quinaldinyl) phosphine (13) and diisopropyla-
mino bis(quinaldinyl) phosphine (14) were synthesized as de-
Scheme 2. Synthesis of carbazolyl bis(picolyl) phosphine (5) by reaction of PicTMS (6) with dichlorophosphine 1.
In contrast to the reaction of carbazolyl dichlorophosphine (1)
with 2 equiv of PicTMS (6) the corresponding reaction of iPr2NPCl2
(2) and Bn2NPCl2 (4) with PicTMS (6) did not lead to the desired
amino bis(picolyl) phosphines. Even after refluxing the reaction
mixture for 20 h, amino dichlorophosphine 2 did not react with
PicTMS (6).
The reaction of Bn2NPCl2 (4) with 2 equiv of PicTMS (6) under
the same conditions resulted unexpectedly in the formation of
tris(picolyl) phosphine (7). It was clearly identified in the crude
reaction mixture by 31P NMR spectroscopy (7, dP¼ꢀ13.1,
2JPH¼1.5 Hz)4 (eq. (4) Scheme 3). Its formation is most probably due
to a dismutation of the dichlorophosphine 4. Such dismutations
have been described for dichlorophosphines and phosphines.8
Substituent exchange between two molecules of Bn2NPCl2 (4)
scribed for the bis(picolyl) derivatives 5 and 11, starting from the
respective amino dichlorophosphine 1 or 4 and QuinaldinylTMS
(15)10 in the case of 1 (Scheme 5) or quinaldinyl-lithium (16) in the
case of 4 (Scheme 6).
Compound 13 was isolated by removing the THF and washing
of the crude reaction mixture several times with Et2O. It was
obtained as a yellowish to orange solid in very good yield (89%).
Bis(quinaldinyl) phosphine 13 is highly sensitive towards oxida-
tion in air, as is also 14. Phosphine 14 was isolated by extraction
of the crude reaction mixture with toluene in very good yield
(94%) as a bright yellow crystalline solid. Phosphines 13 and 14
are soluble in Et2O, THF, DCM, MeCN and toluene. The identity of
both bis(quinaldinyl) phosphines is confirmed by 1H, 13C and 31P
NMR spectroscopy and in the case of 14, also by single crystal X-
ray diffraction.
2.2. Characterization
2.2.1. NMR properties. Tables 1e3 contain the 1H, 13C and 31P NMR
data of the new compounds 1, 5, 11, 13 and 14 presented here. The
phosphorus NMR chemical shift of 1 is with dP¼144.4 in the same
range as the corresponding signals of indolyl (143.8 ppm) and
pyrrolyl (148.4 ppm) dichlorophosphine.11 Worth mentioning are
the small values of most P,C-couplings in the carbazolyl substituent.
3
They have values between 1.3 and <0.5 Hz and only JPC is larger
(Table 1). This applies to all carbazolyl substituted phosphines re-
Scheme 3. Dismutation reaction of Bn2NPCl2 (4) in the presence of the twofold
amount of PicTMS (6) at reflux conditions for 20 h.
ported. The 31P NMR shifts of the bis(picolyl) and bis(quinaldinyl)

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C. Hettstedt et al. / Tetrahedron 72 (2016) 3162e3170
Scheme 4. Synthesis of diisopropylamino bis(picolyl) phosphine (11) by direct reaction of 2 equiv of picolyl-lithium (12) with diisopropylamino dichlorophosphine (2).
Scheme 5. Synthesis of carbazolyl bis(quinaldinyl) phosphine (13) by reaction of dichlorophosphine 1 with QuinTMS (15).
Scheme 6. Synthesis of diisopropylamino bis(quinaldinyl) phosphine (14) by reaction of dichlorophosphine 2 with quinaldinyl-lithium (16).
Table 1
1H, 13C and 31P NMR data of carbazolyl dichlorophosphine 1. Chemical shifts
ppm, coupling constants J in Hz
d in
dichlorophosphines 1 and 3 were obtained by storing a solution of
the compound at ꢀ18 ꢁC (Et2O (1), pentane (3)). Both compounds
crystallize in an orthorhombic space group with four (P212121 (1))
and eight (Pbca (3)) formula units per unit cell, respectively. In both
cases the asymmetric units consist of one molecule of the com-
pound (Fig. 1).
In the molecular structures of 1 and 3, all PeCl bond lengths are
ꢀ
ꢀ
ꢀ
ꢀ
different (2.086(8) A/2.056(8) A (1) and 2.046(1) A/2.105(1) A (3))
(Table 4). This is in contrast to the similar lengths of the PeCl bonds
in the crystal structures of the literature known Me2NPCl2 (2.095(1)
1
dC
dP
144.4
13
14
ꢀ
ꢀ
C1
139.6
<0.5
114.4
15.7
126.7
1.3
123.2
1.3
120.7
<0.5
123.5
<0.5
A) and Cy2NPCl2 (2.092(8) A). Reason for the largest deviation,
which occurs in the molecular structure of 3, is most probably
negative hyperconjugation15 of the lone pair of the nitrogen atom
2JPC
C2
dH
H2
8.02e7.99
7.52e7.48
7.41e7.37
8.05e8.00
3JPC
C3
to the anti bonding
s*-orbital of the P1eCl2 bond. Similar in-
H3
H4
H5
4JPC
C4
teraction in dichlorophosphines RPCl2 with suitable substituents R
have been reported in the literature.16
5JPC
C5
All four PeCl bonds are longer than the literature values for
a PeCl single bond (2.04 A, 2.008 A18) and the longest one is
longer than the corresponding bond in the structure of Me2NPCl2. It
is located under the longer bonds compared to those in other amino
dichlorophosphines with the R2NPCl2 structural motive (see Fig. 2).
The shorter PeCl bonds in the crystal structures of 1 and 3 are the
shortest PeCl bonds in the family of amino dichlorophosphines
R2NPCl2 (Fig. 2). They are in the range of PeCl bonds observed in the
molecular structures of amino bis(dichloro)phosphines RN(PCl2)2
(Fig. 2).
17
ꢀ
ꢀ
4JPC
C6
3JPC
phosphines are all four in the same region between 34.8 (13) and
42.4 (11) ppm and are typical for amino phosphines.12 The chemical
shift of the phosphorus atoms of the carbazolyl substituted phos-
phines are in both cases shifted to higher field, as compared to the
corresponding NMR signals of the isopropyl substituted derivatives.
In compounds 5, 11, 13 and 14 the CH2 protons are diaster-
eotopic. For all compounds except 13 the diastereotopy is clearly
visible in the 1H NMR spectra, where the typical AB part of an ABX
spectrum (X¼P) is observed. The signal of the CH2 protons of
compound 13 is just a broad singlet (The signals of the respective
CH2 protons are depicted next to Tables 2 and 3).
ꢀ
The two PeN bonds in the molecular structures of 1 (1.681(2) A)
13
ꢀ
and 3 (1.668(1) A) are longer than the PeN bonds in Me2NPCl2
and Cy2NPCl2.14 They are shorter than the literature value for
17
ꢀ
a PeN single bond (1.76 A). The bond angles around the phos-
phorus atoms are in both structures very similar and in the ex-
pected range.
In the molecular structure of 1, the phosphorus atom is not lo-
cated in the plane of the planar carbazolyl substituent. The
P1eN1eC1eC2 and the P1eN1eC12eC11 torsion angles are 7.5(3)ꢁ
and ꢀ5.9(3)ꢁ, respectively. The Cl1eP1eCl2 unit is twisted out of
2.2.2. Molecular and crystal structures of dichlorophosphines 1 and
3. Single crystals suitable for X-ray diffraction of the

C. Hettstedt et al. / Tetrahedron 72 (2016) 3162e3170
3165
Table 2
Table 3
1H, 13C and 31P NMR data of the amino bis(picolyl)phosphines 5 and 11. Chemical
1H, 13C and 31P NMR data of the amino bis(quinaldinyl) phosphines 13 and 14.
shifts
d
in ppm, coupling constants J in Hz
Chemical shifts d in ppm, coupling constants J in Hz
5
13
Signal of the CH2 protons in the 1H NMR
Signal of the CH2 protons in the 1H NMR spectrum
of 13.
spectrum of 5.
14
Signal of the CH2 protons in the 1H NMR spectrum of
11
Signal of the CH2 protons in the 1H NMR
14. The broad signal belongs to iPr-CH (H12).
spectrum of 11. The broad signal belongs to
iPr-CH
13
14
13
14
(H7).
dP
2JPH
dC
34.8
<2.0
39.8
5.5
dH
5
11
42.2
5.4
5
11
8.41
;
3JPH
H1
4.26
nH1A
nH1B
2JH1AH1B
2JPHA
2JPHB
H3
3.30
3.55
13.0
5.9
<0.1
7.40
8.6
dP
2JPH
37.6
4.4
dH
C1
38.2
21.4
157.65
10.5
121.8
5.0
136.5
126.7
1.7
127.5
0.9
126.0
<0.4
129.5
128.9
<0.4
148.0
<0.4
144.0
113.6
12.4
120.6
<0.4
110.8
120.3
125.9
0.5
41.5
21.8
159.6
9.2
122.4
6.6
135.7
126.5
1.4
127.5
0.7
125.5
0.7
129.2
128.8
0.4
148.0
0.9
d
H1
8.42e8.40
4.6
d
1JPC
C2
dC
3JH1H2
4JH1H3
5JH1H4
H2
4.4
1.9
0.9
6.96
7.7
1.1
7.46
6.8
7.20
3.02
3.21
6.2
C1
149.5
1.3
121.3
2.5
136.5
1.3
123.6
5.5
149.1
1.0
120.5
2.2
135.9
1.0
123.9
6.6
2JPC
C3
4JPC
C2
d
7.05
8.4
7.80
7.7
7.62
7.7
6.93
7.3
1.0
7.33e7.28
7.8
6.83
3.95
4.01
5.1
3JPC
C4
3JH3H4
H4
5JPC
CC3
4JPC
C4
3JH2H3
4JH2H4
H3
3JH3H4
H4
7.96
d
C5
3JH4H15
H6
5JPC
C6
7.69
8.1
1.3
7.44e7.40
7.3
7.61
8.5
7.99
3.42
6.7
3JH6H7
4JH6H8
H7
3JPC
C5
6JPC
C7
157.0
9.5
159.2
8.9
nH6A
7.43e7.38
2JPC
C6
nH6B
7JPC
C8
3JH7H8
H8
37.1
20.4
139.7
<0.5
113.3
12.2
125.9
1.1
120.5
<0.5
120.2
<0.5
124.8
5.2
40.2
21.0
45.5
<0.7
23.7
5.9
2JPH6A
2JPH6B
2JH6AH6B
H7
7.60e7.57
8.6
7.86
7.99
7.5
1JPC
C7
<0.5
13.7
d
<0.5
13.2
3.31
C9
3JH8H9
H9
5JPC
C10
4JPC
C11
C12
3JPC
C13
4JPC
C14
C15
C16
3JPC
2JPC
C8
H12
3JH7H8
H8
6.8
0.82
3JH12H13
3JPH12
H13
3JPC
C9
7.86
8.5
2.1
d
3JH8H9
4JPHS
H9
d
45.7
<0.5
23.7
5.3
7.30e7.24
7.43e7.38
8.04
0.88
d
4JPC
C10
2JPC
C11
4JPC
C12
3JPC
d
3.1
H14
H15
7.37
7.6
7.22
7.5
d
d
3JH9H10
H10
d
d
d
d
d
3JH10H11
H11
d
8.00
d
2.2.3. Molecular and crystal structures of the phosphines 5 and
14. Single crystals suitable for X-ray diffraction of carbazolyl bis(-
picolyl) phosphine (5) and diisopropylamino bis(quinaldinyl)
phosphine (14) were obtained by storing a solution of the com-
pound in toluene at 0 ꢁC (5) or ꢀ18 ꢁC (14), respectively. Compound
5 crystallizes in the monoclinic space group P21/n with four formula
units in the unit cell whereas 14 crystallizes in the orthorhombic
space group Pbca with eight formula units in the unit cell. In both
cases the asymmetric unit comprises one molecule of the com-
pound (Fig. 5). Table 5 contains selected bond lengths and angles
from both molecular structures.
the aromatic plane in a way that the chlorine atoms are almost
symmetrically located under and over the plane (Fig. 3). A similar
arrangement can be found in the molecular structure of Cy2NPCl2.14
In contrast to the symmetric alignment of the chlorine atoms dis-
cussed before, the substituents at phosphorus and nitrogen in 3 are
twisted relative to each other in the solid state (Fig. 1 middle and
right). The P1eCl2 bond and the N1eC7 bond are almost
perpendicular to each other and the respective torsion angle
Cl2eP1eN1eC7 is ꢀ92.2ꢁ (see Fig. 1).
In the crystal the molecules of compound 1 are arranged along
the a-axis by intermolecular
molecules in the crystal structure of 3 are connected along the b-
axis by non-classical CeH/ hydrogen bonds (Fig. 4).
p-stacking interactions (Fig. 3). The
ꢀ
The P1eN1 bond in 5 (1.744(1) A) is longer than the P1eN1 bond
ꢀ
in 14 (1.672(3) A) and also longer than the PeN bonds in the
p

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C. Hettstedt et al. / Tetrahedron 72 (2016) 3162e3170
Fig. 1. Asymmetric units of the dichlorophosphines 1 (left) and 3 (middle and right). Thermal ellipsoids are drawn at 50% probability level.
molecular structures of the dichlorophosphines discussed above,
whereas the bond in 14 is in the same range as the corresponding
bonds in 1 and 3. Both PeN bonds are shorter than the literature
Table 4
ꢁ
ꢀ
value for a PeN single bond (1.76 A).17 The two PeC bond lengths in
Selected bond lengths [A] and angles [ ] in the molecular structures of the amino-
dichloro phosphines 1 and 3
ꢀ
the respective structures are similar and those in 14 are longer than
the PeC bonds in 5 (Table 5). All four PeC bonds are in the range of
1
3
a PeC single bond (1.855 A)18 and comparable to the corresponding
ꢀ
P1eN1
P1eCl1
P1eCl2
N1eP1eCl1
N1eP1eCl2
Cl1eP1eCl2
1.681(2)
2.086(8)
2.056(8)
101.0(7)
102.1(6)
97.7(3)
1.668(1)
2.046(1)
2.105(1)
101.1(1)
104.5(2)
98.8(1)
bonds in the molecular structure of Pic3P.3b
The phosphorus atom in the molecular structure of 5 is sur-
rounded pyramidal by two carbon atoms and one nitrogen atom. The
sum of the angles at phosphorus is 303.6ꢁ. The nitrogen atom of the
carbazolyl substituent is not in a planar surrounding (Fig. 5 middle),
Fig. 2. Statistical distribution of PeCl bond lengths from crystal structures of the CSD (Cambridge Structural Database), 47 in total. R¼Aryl, Alkyl; Het¼Heteroatom, e.g. P, N, Si.
b
ꢀ
Fig. 3.
p
-stacking in the crystal structure of carbazolyl dichlorophosphine (1), d(Cg(2)/Cg(3) ¼3.738(1) A; Cg¼Center of gravity of the aromatic ring; Cg(2) is the ring C1eC6; Cg(3)
is the ring C7eC12. Symmetry codes: a (1þx, y, z), b (ꢀ1þx, y, z). Thermal ellipsoids are drawn at 50% probability level.

C. Hettstedt et al. / Tetrahedron 72 (2016) 3162e3170
3167
a
b
ꢀ
ꢀ
Fig. 4. Non-classical CeH/
p
hydrogen bonds in the crystal structure of diphenylamino dichlorophosphine (3). d(C8/Cg(2) )¼3.723(2) A, d(C11/Cg(2) )¼3.697(2) A. Cg(2) is the
center of gravity of the ring C7eC12. Symmetry codes: a (1ꢀx, 0.5þy, 1.5ꢀz), b (1.5ꢀx, ꢀ0.5þy, z). Thermal ellipsoids are drawn at 50% probability level.
Fig. 5. Left and middle: Asymmetric unit of 5. Right: Asymmetric unit of 14, H atoms are omitted for clarity. Thermal ellipsoids are drawn at 50% probability level.
Table 5
and as a consequence the phosphorus atom is not in the same plane
ꢁ
ꢀ
Selected bond lengths [A] and angles [ ] in the molecular structures of 5 and 14
as the carbazolyl substituent as it can be observed in the structure of
1. The corresponding torsion angles are with 31.2(2) ꢁ and ꢀ35.7(2) ꢁ
(Table 5) clearly larger than the respective torsion angles in 1.
5
14
P1eN1
P1eC13
P1eC19
N1eP1eC13
N1eP1eC19
C13eP1eC19
P1eN1eC1eC2
P1eN1eC12eC11
1.744(1)
P1eN1
P1eC7
P1eC17
N1eP1eC7
N1eP1eC17
C7eP1eC17
1.672(3)
1.862(3)
1.867(8)
104.4(1)
103.8(1)
98.5(1)
1.849(2)
1.856(2)
101.8(6)
99.4(6)
102.4(7)
ꢀ35.7(2)
31.2(2)
In the crystal, the molecules of 5 are interconnected by CeH$$$
p
hydrogen bonds to form a complex network (Fig. 6). In the crystal
structure of 14, the molecules are interconnected by C25eH25/N2
hydrogen bonds to form dimers. These dimers form chains parallel
to the b-axis by
p-stacking interactions between the quinaldinyl
substituents containing the hydrogen bond acceptor N2 (Fig. 7).
Fig. 6. Non classical CeH/
p
hydrogen bonds in the crystal structure of 5. The picolyl substituents, which do not participate in intermolecular hydrogen bonding are omitted for
b
a
ꢀ
ꢀ
clarity. d(C3/Cg(3) )¼3.894(2) A, d(C17/Cg(5) )¼3.569(2) A, Cg is the center of gravity of the aromatic ring, Cg(3) contains N3, Cg(5) is the ring C7eC12. Symmetry code: a (x, ꢀ1þy,
z), b (0.5þx, 0.5ꢀy, 0.5þz). Thermal ellipsoids are drawn at 50% probability level.

3168
C. Hettstedt et al. / Tetrahedron 72 (2016) 3162e3170
a
b
ꢀ
ꢀ
Fig. 7. C25eH25/N2 hydrogen bonds and
p
-stacking interactions in the crystal structure of 14. d(C25/N2 )¼3.501(1) A, d(Cg(1)/Cg(1) )¼3.723(1) A. Cg(1) contains N2. Symmetry
codes: a (1ꢀx, 1ꢀy, ꢀz), b (1ꢀx, ꢀy, ꢀz), c (x, 1þy, z). Thermal ellipsoids are drawn at 50% probability level.
3. Conclusion
40 mA) and a Kappa CCD detector with an X-ray radiation
wavelength of 0.71073 A was used. The data collection was per-
ꢀ
Two new amino bis(picolyl) (5 and 11) and amino bis(qui-
naldinyl) (13 and 14) substituted phosphines were synthesized and
isolated in acceptable to very good yields. The synthetic route via
the reaction of the respective dichlorophosphines 1 and 2 and the
trimethyl(silyl) derivatives of picoline or quinaldine is only appli-
cable for the carbazolyl substituted dichlorophosphine 1. Dichlor-
ophosphine 2 does not react with either 6 or 15. In this case the
lithiated derivatives of picoline and quinaldine 12 and 16 were
used.
The study shows once more the special properties of the ben-
zylic position in 2-picoline. In fact the PeC bond in PicPCl2 (9)
proves to be quite labile, as demonstrated by the easy dismutation
of PicPCl2 (9) observed.
formed with the CrysAlis CCD software19 and the data reduction
with the CrysAlis RED software.20 The structures were solved
with SIR-92, refined with SHELXL-97 and finally checked using
PLATON.21 The absorptions were corrected by SCALE3 ABSPACK
multiscan method.22 All relevant data and parameters of the X-
ray measurements and refinements are given in Table 6. Addi-
tional structural data like bond lengths and angles can be found
in the Supplementary data. Crystallographic data (excluding
structure factors) for the structures in this paper have been de-
posited with the Cambridge Crystallographic Data Centre, CCDC,
12 Union Road, Cambridge CB21EZ, UK. Copies of the data can be
obtained free of charge on quoting the depository numbers CCDC
1453459 (1), CCDC 1453462 (3), CCDC 1453460 (5) and CCDC
1453461 (14) (Fax: þ44 1223 336 033; Email: depos-
it@ccdc.cam.ac.uk, http://www.ccdc.cam.ac.uk).
The straightforward and easy access of the new amino bis(pi-
colyl) and amino bis(quinaldinyl) phosphines opens the way for
a systematic study of their complex chemistry in particular re-
garding their applicability as ligands in luminescent and catalyti-
cally active transition metal complexes.
4.2. Synthetic procedures
4.2.1. Carbazolyl dichlorophosphine (1). Carbazole (8.0 g,
47.8 mmol) was dissolved in 180 mL of dry THF and cooled to 0 ꢁC.
TEA (1.5 equiv, 10 mL, 71.7 mmol) and PCl3 (1.4 equiv, 6 mL,
68.8 mmol) were added dropwise while stirring. The reaction
mixture was allowed to reach ambient temperature over night. The
colorless precipitate was removed by filtration and the solvent re-
moved in vacuo. The crude product was extracted with 50 mL of dry
Et2O. The colorless precipitate was removed by filtration and the
solvent removed in vacuo. 9-(Dichloro)-9H-carbazole (1) was ob-
tained as colorless to yellow air and moisture sensitive voluminous
solid (54%, 6.9 g, 25.8 mmol).
4. Experimental procedures
4.1. General information
All chemicals were commercially available and were used as
received. NMR spectra were recorded with a JEOL EX 400 Eclipse
instrument operating at 400.128 MHz (1H) and 100.626 MHz
(
13C). Chemical shifts are referred to Me4Si (1H, 13C) and 85%
H3PO4 (
31P) as external standards. All spectra were measured, if
not mentioned otherwise, at 25 ꢁC. The assignment of the signals
in the 1H and 13C NMR spectra is based on 2D (1H,1HeCOSY45, 1H,
13CeHMQC and 1H, 13C-HMBC) experiments. For the HMBC NMR
spectra a sinebell window function and a zero filling in both di-
rections was applied resulting in a 4kꢂ4k matrix. Mass spectro-
EA: calcd for C12H8Cl2NP: C: 53.76%, H: 3.01%, N: 5.22%, found:
C: 54.92 (þ1.16) %, H: 3.66 (þ0.65) %, N: 5.03 (ꢀ0.19) %.
NMR: see Table 1.
metric data were obtained with
a
JEOL Mstation JMS 700
4.2.2. 2-((Trimethylsilyl)methyl)quinoline
(15).10 Quinaldine
spectrometer using the direct EI mode. Elemental analysis was
performed either on an Elementar Vario El analysator or an Ele-
mentar vario micro cube for C, H and N. The molecular structures
in the crystalline state were determined by single crystal X-ray
diffraction. For data collection an Xcalibur3 diffractometer
equipped with a Spellman generator (voltage 50 kV, current
(3.39 mL, 25 mmol) was dissolved in 50 mL of dry THF and cooled to
ꢀ78 ꢁC. nBuLi (1 equiv, 15.6 mL, 1.6 M in hexane) was added
dropwise while stirring. The reaction mixture was stirred for ad-
ditional 30 min and TMSCl (1.2 equiv, 3.5 mL, 30 mmol) was added
dropwise. The reaction mixture was allowed to reach room tem-
perature over night. The solvent was removed in vacuo and the

C. Hettstedt et al. / Tetrahedron 72 (2016) 3162e3170
3169
Table 6
Structural data of the compounds 1, 3, 5 and 14
1
3
5
14
Sum formula
Molar mass [g$molꢀ1
Crystal size [mm3]
T [K]
C
12H8Cl2NP
C12H10Cl2NP
270.08
C24H20N3P
381.40
C26H30N3P
415.50
]
268.06
0.20ꢂ0.15ꢂ0.05
0.26ꢂ0.22ꢂ0.16
0.32ꢂ0.28ꢂ0.26
0.40ꢂ0.20ꢂ0.20
173(2)
173(2)
173(2)
173(2)
Color, habitus
Crystal system
Space group
Colorless plate
Orthorhombic
P212121 (No. 19)
5.5020(2)
11.5270(4)
18.0370(6)
90
Colorless block
Orthorhombic
Pbca (No. 61)
13.5711(7)
7.0664(3)
25.2844(11)
90
Colorless block
Monoclinic
P21/n (No. 14)
14.1930(3)
8.6950(8)
16.8150(8)
90
113.052(6)
90
1909.4(2)
4
Colorless block
Orthorhombic
Pbca (No. 61)
21.5450(6)
8.8310(2)
25.2600(6)
90
ꢀ
a [A]
ꢀ
b [A]
ꢀ
c [A]
a
b
g
[ꢁ]
[ꢁ]
[ꢁ]
90
90
90
90
90
90
3
ꢀ
V [A ]
1143.93(7)
4
2424.74(2)
8
4806.1(2)
8
MoKa 0.71069
1.148
0.131
1776
Z
ꢀ
Wavelength [A]
rcalcd [g cmꢀ3
(MoKa) [cmꢀ1
MoKa
0.71069
MoK
a
0.71069
MoKa
0.71069
]
1.556
0.674
544
1.480
0.637
1104
1.327
0.159
800
m
]
F(000)
hkl range
ꢀ7ꢃhꢃ7
ꢀ14ꢃkꢃ15
ꢀ23ꢃlꢃ24
10599
2827
2538
ꢀ18ꢃhꢃ16
ꢀ8ꢃkꢃ9
ꢀ33ꢃlꢃ33
2072
2996
2150
ꢀ18ꢃhꢃ18
ꢀ9ꢃkꢃ11
ꢀ16ꢃlꢃ22
17,490
4725
3917
0.0297
271
ꢀ24ꢃhꢃ26
ꢀ11ꢃkꢃ11
ꢀ31ꢃlꢃ31
7851
4883
3796
Refl.collected
Refl. independent
Refl. observed
Rint
0.0407
153
0.0641
155
0.0463
291
Parameter
q
-range [ꢁ]
4.20ꢃ
q
ꢃ28.27
4.16ꢃ
q
ꢃ28.28
4.25ꢃ
q
ꢃ28.28
4.29ꢃ ꢃ28.99
q
R1, wR2 [I>2
R1, wR2 (all data)
s(I)]
0.0324, 0.0719
0.0395, 0.0758
1.064
0.0396, 0.0815
0.0668, 0.0946
1.060
0.0387, 0.0917
0.0503, 0.0988
1.035
0.0420, 0.0992
0.0582, 0.1084
1.026
GooF
ꢀꢀ3
pmin [e$A
d
pmax
,
d
]
0.253, ꢀ0.210
0.359, ꢀ0.338
0.376, ꢀ0.277
0.220, ꢀ0.266
crude product was extracted with 25 mL of dry pentane. The col-
orless precipitate was removed by filtration and the solvent re-
moved in vacuo. The crude product was purified by vacuum
distillation (65 ꢁC, 2.6$10ꢀ2 mbar, 80 ꢁC oilbath) and obtained as
a colorless liquid (77%, 4.16 g, 17.3 mmol).
To this solution the dark read solution of Picolyl-Lithium (12) was
added dropwise via a cannula. The reaction mixture was allowed to
reach room temperature over night and the solvent was removed in
vacuo. The crude product was extracted with 20 mL of dry pentane
and the colorless precipitate was removed by filtration. The solvent
was removed in vacuo to yield 10 as a yellowish air and moisture
sensitive solid (32%, 1.01 g, 3.2 mmol).
29Si{1H} NMR (79.43 MHz, CDCl3):
(100.6 MHz, CDCl3):
d
¼3.4. 13C{1H} NMR
d
¼162.0 (CAr), 148.2, (CAr), 135.7 (CAr), 129.2
(CAr), 128.5 (CAr), 127.5 (CAr), 125.9 (CAr), 125.0 (CAr), 121.8 (CAr), 31.6
NMR: see Table 2.
(CH2), ꢀ1.4 (CH3).
H NMR (270.17 MHz, CDCl3):
d¼8.00e7.91 (m, 2H, HAr), 7.72e7.68
4.2.5. Carbazolyl bis(quinaldinyl) phosphine (13). Carbazolyl
dichlorophosphine (1) (1 equiv, 2.19 g, 8.17 mmol) was dissolved in
40 mL of dry THF and cooled to 0 ꢁC. QuinTMS (15) (2 equiv, 3.52 g,
16.34 mmol) was added dropwise while stirring. The reaction
mixture was allowed to reach room temperature over night and the
solvent was removed in vacuo. The crude product was washed
three times with 20 mL of dry Et2O to yield 13 as a yellow to orange
air and moisture sensitive solid (89%, 3.49 g, 7.25 mmol).
EA: calcd for C32H24N3P: C: 79.82%, H: 5.02%, N: 8.73%, found: C:
77.76 (ꢀ2.06) %, H: 5.26 (þ0.24) %, N: 8.27 (ꢀ0.46) %.
HRMS (DEI): Mass calcd for C32H24N3P: 481.1708, measured:
481.1689 (Mþ, 78.5%).
(m, 1H, HAr), 7.65e7.59 (m, 1H, HAr), 7.43e7.36 (m, 1H, HAr), 7.07
(d, 1H, J¼8.4 Hz, HAr), 2.54 (s, 2H, CH2), ꢀ0.04 (s, 9H, SiCH3).
4.2.3. Carbazolyl bis(picolyl)phosphan (5). Carbazolyl dichlor-
ophosphine (1) (5.36 g, 20 mmol) was dissolved in 30 mL of dry THF
and cooled to 0 ꢁC. PicTMS (6) (2 equiv, 6.61 g, 40 mmol) was added
dropwise while stirring. The reaction mixture was allowed to reach
room temperature over night and the solvent was removed in
vacuo. The crude product was extracted with 25 mL of dry Et2O and
the precipitate was removed by filtration and the solvent removed
in vacuo. Phosphine 5 was obtained as a colorless to yellowish solid
that is highly sensitive towards oxidation (92%, 7.02 g, 18.4 mmol).
EA: calcd for C24H20N3P: C: 75.58%, H: 5.29%, N: 11.02%, found:
C: 75.57 (ꢀ0.01) %, H: 5.35 (þ0.06) %, N: 10.88 (ꢀ0.14) %.
HRMS (DEI): Mass calcd for C24H20N3P: 381.1395, measured:
381.1399 (Mþ, 100%).
NMR: see Table 3.
4.2.6. N,N-diisopropylamino
bis(quinaldinyl)
phosphine
(14). Quinaldine (2 equiv, 2.71 g, 20 mmol) was dissolved in 25 mL
of dry THF and cooled to ꢀ78 ꢁC. nBuLi (2 equiv, 12.5 mL, 1.6 M in
hexane) was added dropwise while stirring. The dark red reaction
mixture was stirred for another hour. In a second schlenk flask,
iPr2NPCl2 (1 equiv, 2.02 g, 10 mmol) was dissolved in 10 mL of dry
THF at ꢀ78 ꢁC. To this solution the dark read solution of quinaldinyl-
lithium (16) was added dropwise via a cannula. The reaction mixture
was allowed to reach room temperature over night and the solvent
was removed in vacuo. The crude product was extracted with 50 mL
of dry toluene and the colorless precipitate was removed by
NMR: see Table 2.
4.2.4. N,N-diisopropylamino bis(picolyl) phosphine (11). Picoline
(2 equiv, 0.99 mL, 10 mmol) was dissolved in 10 mL of dry THF and
cooled to ꢀ78 ꢁC. nBuLi (2 equiv, 6.25 mL, 1.6 M in hexane) was
added dropwise while stirring. The dark red reaction mixture was
stirred for another hour. In a second schlenk flask, iPr2NPCl2
(1 equiv, 1.01 g, 5 mmol) was dissolved in 5 mL of dry THF at ꢀ78 ꢁC.

3170
C. Hettstedt et al. / Tetrahedron 72 (2016) 3162e3170
328, 232; (g) Jansen, A.; Pitter, S. Monatsh. Chem. 1999, 130, 783; (h) Tsuda, T.;
Morikawa, S.; Saegusa, T. J. Chem. Soc., Chem. Commun. 1989, 1, 9; (i) Yang, H.;
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filtration. The solvent was removed in vacuo to yield 13 as a yel-
lowish air and moisture sensitive solid (94%, 3.91 g, 9.42 mmol).
EA: calcd for C26H30N3P: C: 75.16%, H: 7.28%, N: 10.11%, found: C:
74.36 (ꢀ0.80) %, H: 7.34 (þ0.06) %, N: 9.89 (ꢀ0.22) %.
HRMS (DEI): Mass calcd for C26H30N3P: 415.2177, measured:
415.2199 (Mþ, 100%).
4. Whiteoak, C. J.; Nobbs, J. D.; Kiryushchenkov, E.; Pagano, S.; White, A. J. P.;
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4.2.7. Picolyldichlorophosphine
(9)/Bis(picolyl)chlorophosphine
6. (a) Ruiz-Gomez, G.; Lopez-Ortiz, F. Synlett 2002, 781; (b) Imbery, D.; Friebolin,
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(10). PicTMS (6) (1 mmol, 165.1 mg) was dissolved in a 1:1 mixture
of dry THF and Et2O (5 mL) and added dropwise to a solution of PCl3
(1 equiv, 0.087 mL, 1 mmol) at ꢀ78 ꢁC. The reaction mixture was
allowed to reach ambient temperature over night and the solvent
was removed in vacuo. The 31P NMR spectrum after this step re-
veals a 1.3:1 mixture of 10 and 9, respectively.
7. Kermagoret, A.; Tomicki, F.; Braunstein, P. Dalton Trans. 2008, 2901.
8. (a) Horner, L.; Beck, P.; Toscano, V. G. Chem. Ber. 1961, 94, 2122; (b) Lischewski,
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ꢁ
10. Lukevics, E.; Liepin¸ s, E.; Segal, I.; Fleisher, M. J. Organomet. Chem. 1991, 406, 283.
NMR: 9: 31P NMR (161.99 MHz, THF):
d
¼183.3 (t, 2JPH¼12.2 Hz),
11. (a) Chaikovskaya, A. A.; Dmytriv, Y. V.; Shevchuk, N. V.; Smaliy, R. V.; Pinchuk,
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40%. 10: 31P NMR (161.99 MHz, CDCl3):
d
¼96.4, (quint, 2JPH¼8.9 Hz),
53%.
€
ꢂ
12. (a) Wrackmeyer, B.; Kohler, C.; Milius, W.; Grevy, J. M.; García-Hernandez, Z.;
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Acknowledgments
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Financial support by the Department of Chemistry, Ludwig-
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€
€
Ber. 1995, 128, 379.
€
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Chem. Soc. Perkin Trans. II 1987, S1.
Supplementary data
19. CrysAlis CCD, version 1.171.27p5 beta (release 01e04e2005 CrysAlis171.NET;
compiled Apr 1 2005, 17:53:34); Oxford Diffraction Ltd.: Oxfordshire, U.K.
20. CrysAlis RED, version 1.171.27p5 beta (release 01e04e2005 CrysAlis171.NET;
compiled Apr 1 2005, 17:53:34); Oxford Diffraction Ltd.: Oxfordshire, U.K.
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Supplementary data associated with this article can be found in
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