Synthesis of organophosphorus compounds containing different Y,C,Y-chelating ligands. Crystal structure of P ← N intramolecularly coordinated diselenoxophosphorane

Article abstract of DOI:10.1016/j.ica.2010.06.008

The reactions of L^1-3Li salts containing different Y,C,Y-chelating ligands L¹ = 2,6-(t-BuOCH₂) ₂C₆H3-1, L² = 2,6-(MesOCH₂) ₂C₆H3-1 and L³ = 2,6-(

Full text of DOI:10.1016/j.ica.2010.06.008

Inorganica Chimica Acta 363 (2010) 3302–3307
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Synthesis of organophosphorus compounds containing different Y,C,Y-chelating
ligands. Crystal structure of P N intramolecularly coordinated
diselenoxophosphorane
Tomáš Reznícek a,1, Libor Dostál a,1, Aleš Ru˚ zicka a,1, Robert Jirásko b, Roman Jambor a,
*
ˇ
ˇ
ˇ ˇ
a Department of General and Inorganic Chemistry, University of Pardubice, Studentská 95, CZ-532 10, Pardubice, Czech Republic
b Department of Analytical Chemistry, University of Pardubice, Czech Republic
a r t i c l e i n f o
a b s t r a c t
The reactions of L1–3Li salts containing different Y,C,Y-chelating ligands L1 = 2,6-(t-BuOCH2)2C6H3
,
ꢀ1
Article history:
Received 1 April 2010
Received in revised form 26 May 2010
Accepted 8 June 2010
Available online 15 June 2010
L2 = 2,6-(MesOCH2)2C6H3 and L3 = 2,6-(Me2NCH2)2C6H3 with PCl3 is reported. While the presence of
ligands L2,3 afforded the synthesis of dichlorophosphines L2PCl2 (2) and L3PCl2 (3), the use of ligand L1
resulted to the isolation of O ? P coordinated 1-chloro-7-(t-butoxymethyl)-3H-2,1-benzoxaphosphole
(1) as the result of the cyclization type reaction of dichlorophosphines L1PCl2. The hydrolysis of com-
pounds 1–3 as well as the preparation of phosphanes L2PH2 (7), L3PH2 (8), L2PH(SnMe3) (9) and
L3PH(SnMe3) (10) is also discussed. The presence of N ? P coordination enabled the isolation of N ? P
coordinated diselenoxophosphorane L3PSe2 (11). Compounds 1–11 were characterized by the help of
multinuclear NMR spectroscopy, ESI mass spectrometry and the structure of compound 11 was estab-
lished by X-ray diffraction analysis.
ꢀ1
ꢀ1
Keywords:
Organophosphorus compounds
Y,C,Y-chelating ligand
NMR spectroscopy
X-ray structure determination
Ó 2010 Published by Elsevier B.V.
1. Introduction
O ? P coordinated monoorganophosphorus compounds are even
more rare and showed low stability of prepared compounds due to
The interaction of electron donor atom Y with the phosphorus
atom makes the phosphorus center more electron-rich. Due to this
reason, the chemistry of an intramolecularly N ? P and O ? P coor-
dinated phosphines has been explored and these compounds were
mainly used as bidentate ligands in transition metal chemistry. Cor-
riu and co-workers have shown that the tridentate pincer ligand 2,6-
bis(dimethylaminomethyl)phenyl (hereafter assigned to L3, see
Chart 1), is very useful for the stabilization of N ? P coordinated
phosphanes [1], and the synthesis of phosphenium ions with a
[L3PR]+ Xꢀ bond (R = Ph or H, X = C1, H, Br) [2]. Later on, ligands, such
as the 2,4-di-t-butyl-6-(dimethylamino)phenyl group (abbreviated
as Mx) [3], the 2,4-di-t-butyl-6-(dimethylaminomethyl)phenyl
group (abbreviated as Mamx) [4], the 2,4-di-t-butyl-6-(piperidi-
no)phenyl group (abbreviated as Pix) [5] and the 2,4-di-t-butyl-6-
[1,1-dimethyl-2-(dimethylamino)ethyl]phenyl group (abbreviated
as Maar) [6] containing a bulky t-butyl group together with the
nitrogen donor atom were prepared. These ligands were used for
the preparation of various types of multiple bonded phosphorus
compounds, dithioxophosphorane (thioxophosphine sulfide), and
diselenoxophosphorane (selenoxophosphine selenide) that were
stabilized by N ? P coordination [3–7]. The studies dealing with
a presence of O ? P intramolecular interaction within the
molecules. Ligands 2,4-di-t-butyl-6-methoxyphenyl group (abbre-
viated as Mox) [8], the 2,4-di-t-butyl-6-(methoxymethyl)phenyl
group (abbreviated as Momx) [9], and 4-t-butyl-2,6-bis(meth-
oxyalkyl)phenyl groups [10] were synthesized for this purpose.
Recently, we have reported the synthesis of an intramolecularly
coordinated compounds of heavier main-group elements M (M is
Sn, Sb or Bi) containing O,C,O- or N,C,N-chelating ligands L1–3
(Chart 1) and demonstrated a possible stabilization of species as
distannyne L3SnSnL3 [11] or L3SbSe by above mentioned pincer
ligands [12].
As a part of our studies on main-group elements containing
pincer type ligands, we discuss here a different reactivity of the
Y,C,Y-chelating ligands L1–3 with PCl3, with the aim to synthesize
an intramolecularly coordinated monoorganophosphorus com-
pounds. While the presence of ligands L2,3 afforded the synthesis
of dichlorophosphines L2PCl2 (2) and L3PCl2 (3), the cyclization
type reaction of dichlorophosphines L1PCl2 resulted to the isolation
of O ? P coordinated 1-chloro-7-(t-butoxymethyl)-3H-2,1-benz-
oxaphosphole (1), in the case of ligand L1. Compounds 1–3 are
air and moisture sensitive compounds producing compounds 4–6
as the only hydrolytic products (Chart 2). The synthesis and char-
acterization of phosphanes L2PH2 (7), L3PH2 (8), L2PH(SnMe3) (9)
and L3PH(SnMe3) (10) is also reported. We have also found out that
the presence of N ? P coordination is crucial for the isolation of
* Corresponding author. Fax: +420 466037068.
E-mail address: roman.jambor@upce.cz (R. Jambor).
1
Fax: +420 466037068.
0020-1693/$ - see front matter Ó 2010 Published by Elsevier B.V.
doi:10.1016/j.ica.2010.06.008

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3303
CH2O); 5.04 (AB spin system, 2H, CH2OP, da 4.92 ppm, db
5.16 ppm); 6.83 (d, 1H, ArH); 6.95 (d, 1H, ArH); 7.14 (dd, 1H,
ArH); 13C NMR (C6D6, 90 MHz) d (ppm): 28.1 (CH3); 64.6 (CH2Ot-
Bu); 75.4 (OC(CH3)3); 77.8 (CH2OP; 3J(13C, 31P) = 18.1 Hz); 125.4
(C(3,5); 3J(13C, 31P) = 2.7 Hz); 131.1 (C(4)); 137.1 (C(1); 1J(13C,
31P) = 751.6 Hz); 141.8 (C(2); 2J(13C, 31P) = 9.9 Hz); 144.2 (C(6);
2J(13C, 31P) = 4.5 Hz); 31P NMR (C6D6, 145 MHz) d (ppm): 172.6.
+
(ESI+) MS: m/z 503 [2 (MꢀHCl+H2O)+Na] (18%); m/z 481
*
[2 (MꢀHCl+H2O)+H] (100%); m/z 241 [(MꢀHCl+H2O)+H]+ (45%);
+
*
m/z 185 [(MꢀHCl+H2O)+HꢀC4H8]+ (95%); m/z 167 [MꢀHClꢀC4H8
+H]+ (10%). Anal. Calc. for C12H16ClO2P (258.69): C, 55.72; H, 6.23.
Found: C, 55.42; H, 6.13%.
Chart 1.
2.2. Preparation of {2,6-bis[(mesithyloxy)methyl]phenyl}phosphorus
dichloride (2)
The 1.74 mL of 1.6 M nBuLi was added to a hexane solution
(15 mL) of L2 (1.01 g; 2.7 mmol) and the solution was stirred for
2 days. Resulting suspension was filtered and solid was washed
with hexane (5 mL) to give L2Li (0.85 g; 2.3 mmol). The L2Li was
dissolved in toluene (15 mL) and added dropwise to the hexane
solution (10 mL) of PCl3 (0.2 mL; 2.3 mmol) at 0 °C and stirred for
48 h at RT. The suspension was filtered and solvent evaporated to
give yellow-green oil, washed with hexane (5 mL) to form white
solid that was identified as 2. Yield: 0.77 g (80%). Mp
128.3–130.5 °C; 1H NMR (C6D6, 360 MHz) d (ppm): 2.22 (s, 6H,
CH3); 2.31 (s, 12H, CH3); 5.44 (s, 4H, CH2O); 6.94 (s, 4H, CH);
7.08–7.92 (m, 3H, ArH); 13C NMR (C6D6, 125 MHz) d (ppm): 17.0
(CH3); 21.0 (CH3); 71.9 (CH2O; 3J(13C, 31P) = 19.9 Hz); 129.4
Chart 2.
N ? P coordinated diselenoxophosphorane L3PSe2 (11). Com-
pounds 1–11 were characterized by the help of multinuclear
NMR spectroscopy, ESI mass spectrometry and the structure of
compound 11 was established by X-ray diffraction analysis.
31
(C(3,5); 3J(13C, P) = 3.6 Hz); 130.2 (C(30,50)); 130.9 (C(20,60));
31
133.5 (C(4)); 133.8 (C(40)); 135.2 (C(1); 1J(13C, P) = 68.80Hz);
143.9 (C(2,6); 2J(13C, 31P) = 23.7 Hz); 154.5 (C(10)); 31P NMR
+
*
(C6D6, 145 MHz) d (ppm): 157.9. (ESI ) MS: m/z 877 [2 (Mꢀ2HCl
+2H2O)+H]+ (6%); m/z 439 [(Mꢀ2HCl+2H2O)+H]+ (100%). Anal. Calc.
for C26H29Cl2O2P (460.35): C, 65.69; H, 6.15. Found: C, 65.57; H,
6.13%.
2. Experimental
General methods: The starting compounds L1–3, L3PCl2 (3) and
L3PH2 (8) were prepared according to literature [1]. Starting n-BuLi,
PCl3, LiAlH4 and Li[HB(C2H5)3] were purchase from Sigma Aldrich.
All reactions were carried out under argon atmosphere, using stan-
dard Schlenk techniques. Solvents were dried by standard methods
and distilled prior to use. The 1H, 13C, 31P and 119Sn NMR spectra
were acquired with Bruker Avance500 spectrometer in CDCl3 or
C6D6. Appropriate chemical shifts were calibrated on: 1H-residual
peak of CHCl3 (d = 7.25 ppm), 13C-residual peak of CHCl3
(d = 77.23 ppm), 31P-external H3PO4 (d = 0.00 ppm), 119Sn-external
tetramethylstannane (d = 0.00 ppm). The positive-ion and nega-
tive-ion electrospray ionization (ESI) mass spectra were measured
on an ion trap analyzer Esquire 3000 (Bruker Daltonics, Bremen,
Germany) in the range m/z 50–1000. The samples were dissolved
in acetonitrile and analyzed by direct infusion at the flow rate
2.3. Preparation of 1-hydrido-7-(tert-butoxymethyl)-3H-2,1-
benzoxaphosphole 1-oxide (4)
The THF solution (10 mL) of 1 (0.40 g; 1.5 mmol) was stirred in
air for 3 h. The solvent was evaporated to give colorless oil that was
identified as compound 4. Yield: 0.33 g (90%). 1H NMR (C6D6,
360 MHz) d (ppm): 1.30 (s, 9H, CH3); 4.59 (AX spin system, 2H,
CH2OtBu, da 4.44 ppm, db 4.77 ppm); 5.25 (AB spin system, 2H,
CH2OP, da0 5.13 ppm, db0 5.37 ppm); 7.12–7.45 (m, 3H, ArH); 8.15
(d, 1H, PH; 1J(1H, 31P) = 637.4 Hz); 13C NMR (C6D6, 90 MHz) d
(ppm): 27.5 (CH3); 62.6 (CH2OtBu); 72.0 (OC(CH3)3); 75.4 (CH2OP);
120.9 (C(5); 3J(13C, 31P) = 11.8 Hz); 126.2 (C(3); 3J(13C,
31P) = 18.1 Hz); 126.1 (C(1); 1J(13C, 31P) = 279.6 Hz); 133.2 (C(4));
143.3 (C(6); 2J(13C, 31P) = 8.7 Hz); 145.6 (C(2); 2J(13C, 31P) = 21.6
Hz); 31P NMR (C6D6, 145 MHz)
d
(ppm): 39.4 (d; 1J(31P,
(cmꢀ1): 1236 (P@O). (ESI+) MS: m/z 503
5 lL/min. The ion source temperature was 300 °C, the tuning
parameter compound stability was 100%, the flow rate and the
pressure of nitrogen were 4 l/min and 10 psi, respectively.
1H) = 637.2 Hz); IR
m
[2M+Na]+ (8%); m/z 481 [2M+H]+ (57%); m/z 241 [M+H]+ (31%);
m/z 185 [M+HꢀC4H8]+ (100%); m/z 167 [M+HꢀC4H8ꢀH2O]+ (8%).
Anal. Calc. for C12H17O3P (240.24): C, 60.00; H, 7.13. Found: C,
59.90; H, 7.05%.
2.1. Preparation of 1-chloro-7-(tert-butoxymethyl)-3H-2,1-
benzoxaphosphole (1)
The 1.35 mL of 1.6 M nBuLi was added to a hexane solution
(15 mL) of L1 (0.54 g; 2.2 mmol) and solution was stirred for 16 h
and was added dropwise to the hexane solution (10 mL) of PCl3
(0.19 mL, 2.2 mmol) at ꢀ80 °C. This mixture was stirred for 7 h at
ꢀ80 °C and was warmed to RT. The suspension was filtered and so-
lid was extracted again with hexane (5 mL). Joined hexane extracts
were evaporated to give light yellow oil 1. Yield: 0.50 g (90%). 1H
NMR (C6D6, 360 MHz) d (ppm): 1.13 (s, 9H, CH3); 4.34 (s, 2H,
2.4. Preparation of {2,6-bis[(mesithyloxy)methyl]phenyl}phosphorous
acid (5)
The toluene solution (10 mL) of 2 (0.50 g; 1.1 mmol) was stirred
in air for 4 h. The solvent was evaporated spontaneously to form
white solid material that was identified as compound 5. Yield:
0.45 g (95%). Mp 192–195 °C; 1H NMR (C6D6, 360 MHz) d (ppm):
2.18 (s, 12H, CH3); 2.23 (s, 6H, CH3); 3.63 (s, 1H, OH); 5.17 (s, 4H,

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CH2O); 6.79 (s, 4H, CH); 7.60–7.73 (3m, 3H, ArH); 8.08 (d, 1H, PH;
1J(1H, 31P) = 612.0 Hz); 13C NMR (C6D6, 125 MHz) d (ppm): 16.7
(CH3); 29.9 (CH3); 71.9 (CH2O; 3J(13C, 31P) = 8.1 Hz); 127.8 (C(1);
1J(13C, 31P) = 103.9 Hz); 128.4 (C(3,5); 3J(13C, 31P) = 10.9 Hz); 129.
7 (C(30,50)); 130.8 (C(20,60)); 132.9 (C(4)); 133.7 (C(40)); 141.6
(C(2,6); 2J(13C, 31P) = 9.0 Hz); 153.8 (C(10)); d(31P) (C6D6,
ppm, db 3.78 ppm); 3.81 (d, 1H, PH; 1J(1H, 31P) = 191.5 Hz; 2J(1H,
119Sn) = 45.0 Hz); 7.07–7.25 (m, 3H, ArH); 13C NMR (C6D6,
125 MHz) d (ppm): ꢀ6.4 (SnCH3; 1J(13C, 119Sn) = 301.8 Hz; 2J(13C,
31P) = 4.6 Hz); 45.1 (NCH3); 65.6 (CH2N; 3J(13C, 31P) = 7.4 Hz);
125.4 (C(3,5); 3J(13C, 31P) = 24.7 Hz)); 129.3 (C(4); 4J(13C, 31P)
= 2.7 Hz); 139.1 (C(1); 1J(13C, 31P) = 137.5 Hz); 142.3 (C(2,6);
2J(13C, 31P) = 9.2 Hz); d31P NMR (C6D6, 202 MHz) d (ppm): ꢀ171.0
(d; 1J(31P, 1H) = 196.4 Hz; 2J(31P, 119Sn) = 506.1 Hz); d119Sn NMR
(C6D6, 186 MHz) d (ppm): 5.9 (d; 1J(119Sn, 31P) = 505.9 Hz). Anal.
Calc. for C15H29N2PSn (387.07): C, 46.55; H, 7.55. Found: C,
46.50; H, 7.38%.
145 MHz ppm): 22.3; IR
877 [2M+H]+ (31%); m/z 439 [M+H]+ (100%). Anal. Calc. for
26H31O4P (438.51): C, 71.22; H, 7.13. Found: C, 71.12; H, 7.08%.
m
(cmꢀ1): 1217 (P@O); (ESI+) MS: m/z
C
2.5. Preparation of {2,6-bis[(mesithyloxy)methyl]phenyl}phosphane
(7)
2.8. Preparation of {2,6-bis[(N,N-dimethylamino)methyl]phenyl}
diselenoxophosphorane (11)
The THF solution (15 mL) of 2 (1 g; 2.5 mmol) was added drop-
wise to the THF solution (10 mL) of LiAlH4 (0.10 g; 2.7 mmol) and
reaction mixture was stirred for 2 days at RT. The solid was filtered
and the solvent was evaporated to give yellow residuum. This
residuum was extracted with toluene (20 mL), solid was filtered
again and solvent evaporated to give white solid material of 7.
Yield: 0.89 g (90%). Mp 150.3–152.5 °C; 1H NMR (C6D6, 360 MHz)
d (ppm): 2.24 (s, 6H, CH3); 2.33 (s, 12H, CH3); 3.73 (d, 2H, PH;
1J(1H, 31P) = 207 Hz); 4.96 (s, 4H, CH2O); 6.85 (s, 4H, CH);
7.31–7.73 (m, 7H, ArH); 13C NMR (C6D6, 125 MHz) d (ppm): 20.6
(CH3); 21.2 (CH3); 73.6 (CH2O; 3J(13C, 31P) = 10.1 Hz); 128.1
(C(3,5)); 129.1 (C(30,50)); 129.7 (C(20,60)); 130.5 (C(4)); 133.0
(C(40)); 137.7 (C(2,6); 2J(13C, 31P) = 12.6 Hz); 141.8 (C(1); 1J(13C,
31P) = 25.1 Hz); 154.2 (C(10)); d31P NMR (C6D6, 145 MHz) d (ppm):
ꢀ159.9 (t; 1J(31P, 1H) = 207 Hz). Anal. Calc. for C26H31O2P (406.51):
C, 76.82; H, 7.69. Found: C, 76.80; H, 7.68%.
To the THF (10 mL) suspension of selenium (0.08 g; 1.1 mmol)
was added dropwise 1.0 M Super hydrideÒ (Li[HB(C2H5)3])
(2.22 mL; 2.2 mmol) and suspension was stirred for 2.5 h at RT.
The CH2Cl2 solution (15 mL) of 3 (0.33 g; 1.1 mmol) was added
dropwise to Li2Se and solution was stirred for additional 1 h and
the sulfur (0.04 g; 1.1 mmol) was added afterwards. The suspen-
sion was stirred for additional 20 h. The resulting suspension was
filtered, the solvent was evaporated and yellow residuum was ex-
tracted with toluene (15 mL). Extract was filtered and evaporated
to 7 mL. Orange crystals of 11 have grown from toluene/hexane
after 7 days at 4 °C. Yield: 0.23 g (46%). Mp 150.0–152.1; 1H NMR
(C6D6, 500 MHz) d (ppm): 2.23 (s, 12H, NCH3); 3.58 (AB spin sys-
tem, 2H, CH2NP, da 3.53 ppm, db 3.63 ppm); 3.59 (s, 2H, CH2N);
6.86–7.01 (m, 3H, ArH); 13C NMR (C6D6, 100 MHz) d (ppm): 44.3
(CH3N); 59.5 (CH2N; 3J(13C, 31P) = 5.0 Hz); 59.8 (CH2NP; 3J(13C,
31P) = 6.0 Hz); 125.9 (C(3,5); 3J(13C, 31P) = 14.1 Hz); 129.8 (C(4));
137.8 (C(2,6); 2J(13C, 31P) = 16.1 Hz); 138.2 (C(1); 1J(13C, 31P) =
70.4 Hz); d31P NMR (C6D6, 162 MHz) d (ppm): 114.3 (1J(31P,
77Se) = 818.3 Hz). Anal. Calc. for C12H19N2PSe2 (380.19): C, 37.91;
H, 5.04. Found: C, 37.83; H, 5.00%.
2.6. Preparation of {2,6-bis[(mesithyloxy)methyl]phenyl}
trimethylstannylphosphane (9)
To the toluene (10 mL) solution of 7 (0.24 g; 0.6 mmol) was
added dropwise 0.38 mL of 1.6 M nBuLi at 0 °C. The solution was
stirred for 2 h at RT. The Me3SnCl (0.12 g; 0.6 mmol) was added
in one portion to the solution at 0 °C and suspension was stirred
for additional 20 h at RT. The suspension was filtered and solution
evaporated to form white sticky oil of 9. Yield: 0.29 g (85%). 1H
NMR (C6D6, 360 MHz) d (ppm): 0.17 (s, 9H, SnCH3; 1J(1H, 119Sn)
= 72.0 Hz); 2.29 (s, 6H, CH3); 2.41 (s, 12H, CH3); 3.66 (d, 1H, PH;
1J(1H, 31P) = 194.4 Hz; 2J(1H, 119Sn) = 43.2 Hz); 5.06 (AB spin sys-
tem, 4H, CH2O, da 4.88 ppm, db 5.20 ppm); 6.86 (s, 4H, CH);
6.97–7.75 (m, 3H, ArH); 13C NMR (C6D6, 90 MHz) d (ppm): 0.89
(SnCH3; 1J(13C, 119Sn) = 74.2 Hz); 16.4 (CH3); 20.3 (CH3); 74.1
Crystallographic study: Yellowish crystals were obtained at 4 °C
from saturated toluene solution of 11. The intensity data for single
crystals were measured on four-circle diffractometer KappaCCD
with CCD area detector by monochromatized Mo K
a radiation
(k = 0.71073 Å) at 150(2)K. C12H19N2PSe2, M = 380.18, orthorhom-
bic, space group Pna21, a = 16.2781(4), b = 11.9609(4), c =
7.5662(11),
cmꢀ3 = 5.110 mmꢀ1, 10957 reflections collected, of which 3292
a = b = c q = 1.714 g
= 90°, U = 1473.1(2) Å3, Z = 4,
,
l
were independent [Rint = 0.0448]. Final R indices [I > 2sigma(I)]:
R1 = 0.0349, wR2 = 0.0789. Flack parameter = 0.025(12). Treatment
31
(CH2O; 3J(13C, P) = 8.1 Hz); 128.9 (C(30,50)); 129.4 (C(3,5); 3J(13C,
P
P
P
2
data: Rint
¼
jFo2 ꢀ F2o;meanj= Fo2, bS ¼ ½ ðwðF2o ꢀ F2Þ Þ=ðNdiffrs
ꢀ
c
31P) = 2.7 Hz); 130.3 (C(20,60)); 132.8 (C(4)); 133.3 (C(40)); 134.8
(C(1); 1J(13C, 31P) = 64.5 Hz); 140.7 (C(2,6); 2J(13C, 31P) = 9.9 Hz);
154.0 (C(10)); d31P NMR (C6D6, 145 MHz) d (ppm): ꢀ177.8 (d;
1J(31P, 1H) = 195.3 Hz; 2J(31P, 119Sn) = 526.2 Hz); d119Sn NMR (C6
D6, 186 MHz) d (ppm): 14.3 (d; 1J(119Sn, 31P) = 525.5 Hz). Anal. Calc.
for C29H39O2PSn (569.30): C, 61.18; H, 6.91. Found: C, 61.30; H,
6.88%.
1=2
NparamsÞꢁ
,
Weighting scheme: w = [
r
2(Fo2) + (w1P)2 + w2P]ꢀ1
,
where P ¼ ½maxðF2oÞ þ 2Fc2ꢁ, R(F) =
R
||Fo| ꢀ |Fc||/
R
|Fo|, wRðF2Þ ¼
P
P
2
2
½
ðwðF2o ꢀ Fc2Þ Þ=ð wðFo2Þ Þꢁ1=2. The structure was solved by the di-
rect methods (SIR97) and refined by a full-matrix least-squares
procedure based on F2
(
SHELXL97). Hydrogen atoms were fixed into
idealized positions (riding model) and assigned temperature fac-
tors Hiso(H) = 1.2 Ueq (pivot atom) or of 1.5 Ueq for the methyl
moiety.
2.7. Preparation of {2,6-bis[(N,N-dimethylamino)methyl]phenyl}
trimethylstannylphosphane (10)
3. Results and discussion
To the toluene (10 mL) solution of 8 (0.17 g; 0.8 mmol) was
added dropwise 0.48 mL of 1.6 M nBuLi at ꢀ40 °C. The solution
was stirred for 0.5 h at RT. The Me3SnCl (0.15 g; 0.8 mmol) was
added in one portion to the solution at ꢀ40 °C and suspension
was stirred for additional 20 h at RT. The resulting suspension
was filtered and solution evaporated to form gray oil which was
identified as compound 10. Yield: 0.24 g (80%). 1H NMR (C6D6,
500 MHz) d (ppm): 0.24 (s, 9H, SnCH3; 1J(1H, 119Sn) = 51.5 Hz);
2.15 (s, 12H, NCH3); 3.49 (AB spin system, 4H, CH2N, da 3.19
The treatment of L1Li with PCl3 yielded compound 1 in high
yield (90%). The 31P{1H} NMR spectrum showed the presence of
the sharp signal at 172.6 ppm. The 1H NMR spectrum of 1 revealed
singlet (d 4.34 ppm) and AB spin system (5.04 ppm) for the CH2O
t
groups and one signal for the Bu group in 2:2:9 integral ratio as
well as the non-equivalence of all three aromatic protons in
1:1:1 integral ratio. The structure of 1 was also proved by 13C
NMR spectrum where six signals in aromatic region were found.

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Scheme 1. Schematic formation of compound 1.
The proposed product of the reaction was the highly symmetric
compound L1PCl2 (Scheme 1) that should revealed one signal for
the CH2O groups and one signal for the methyl groups with 4:18
integral ratios in 1H NMR spectrum together with one set of the
CH2O groups and four signals in the aromatic region in 13C NMR
spectrum. This difference can be explained that the suggested
product L1PCl2 is formed in the first step of the reaction but the
presence of the Lewis acid phosphorus center caused the cleavage
of the CH2O—Csp3 ðCH3Þ3 bond of the ligand L1 that is accompanied
with the formation of new covalent O ? P bond in 1. The com-
pound 1 is thus formed as the final product along with the elimina-
31P) = 637 Hz. This was further confirmed by the 31P NMR spec-
trum, where the doublet with 1J(31P, 1H) = 637 Hz was found. Addi-
t
tion of the BuCl.
The formation of new covalent O ? P bond resulted to the cycli-
zation of the five-member C3PO heterocyclic ring in 1. The sug-
gested structure of 1 is in accordance with the measured NMR
data (non-symmetrical character with two different CH2 groups
and one methyl group with 2:2:9 integral ratio and six non-equiv-
alent aromatic carbon atoms). Moreover, similar cyclization reac-
tion of dichlorophosphines with O ? P coordination has recently
been reported [7b,9,13].
Armed with this knowledge, we used a different O,C,O-chelating
ligand L2 (Scheme 2) containing O—Csp2 covalent bond and the
treatment of L2Li with PCl3 at 0 °C yielded compound L2PCl2 (2).
The 31P{1H} NMR spectrum of 2 revealed signal at 157.9 ppm. This
value is, however, comparable to the PhPCl2 (d31P) = 158.0 ppm)
and suggests that oxygen donor atoms of L2 does not coordinate
to the central phosphorous atom and acts as sterically hindered
ligand rather than a pincer type ligand. The 1H and 13C NMR spec-
tra of 2 are in accordance with symmetrical character of 2 (one set
of signals was observed only with integral intensities in accordance
with the suggested structure of 2). Compound 3 was prepared by
the reaction of L3Li with PCl3 according to the literature procedure
[1].
Prepared compounds 1–3 are moisture sensitive and their expo-
sition to the air yielded the hydrolytic products 4–6 (Chart 2), as
the only products in high yields.
Compound 4 was characterized by the help of 1H, 13C and 31P
NMR, IR spectroscopy and ESI-MS spectrometry. The31P{1H} NMR
spectrum of 4 shoved one signal at 39.4 ppm that is shifted upfield
as compared to 1 (d 172.6 ppm). The 1H NMR spectrum of 4
showed two AB spin systems for methylene groups at 4.59 and
5.25 ppm and one signal of methyl groups in 2:2:9 integral ratios.
The 13C NMR spectrum also revealed two CH2O groups (signals at
62.6 and 75.4 ppm) and six signals in the aromatic area suggesting
an unsymmetrical structure of 4. The 1H NMR spectrum suggests
the presence of P–H bond in 4 as doublet at 8.15 ppm with 1J(1H,
Scheme 2. Formation of compounds 2 and 3.
Fig. 1. The (ESI+) MS and MS/MS spectra of the hydrolytic compounds 4 and 5.

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tionally, the IR spectroscopy showed the characteristic vibration at
1236 cmꢀ1 that was assigned to the P@O functional group. More-
over, ions at m/z 241, 481 and 503 providing information on MW
together with their fragment ions at m/z 185 and 167 were ob-
served in the full scan positive-ion ESI mass spectrum (see
Fig. 1A). The dimeric character of ion at m/z 481 was confirmed
based on the tandem mass spectra measurement (Fig. 1B). All these
data suggest the formation of 4 as the only product of hydrolysis of
compound 1.
(doublet at 3.81 ppm with 1J(1H, 31P) = 192 Hz for 10). The
31P{1H} NMR spectrum revealed one signal at ꢀ177.8 ppm that is
shifted upfield as compare to 7 (d ꢀ159.9 ppm) with tin satellites
1J(31P, 119Sn) = 526 Hz as well as one signal in 31P{1H} NMR spec-
trum at ꢀ171.0 ppm in 10 that is shifted upfield as compare to 8
(d ꢀ148.6 ppm) with tin satellites 1J(31P, 119Sn) = 506 Hz. The 31P
NMR spectrum of 9 showed the doublet with 1J(31P, 1H) = 195 Hz
(196 Hz for 10). All these data proved the presence of Sn–P–H frag-
ment in 9 and 10. In addition, the 119Sn NMR spectrum of 9 showed
the doublet at 14.3 ppm with 1J(119Sn, 31P) = 526 Hz (doublet at
5.9 ppm with 1J(119Sn, 31P) = 506 Hz for 10).
The dichlorophosphines 2 and 3 were also used as the starting
material for the synthesis of an intramolecularly coordinated disel-
enoxophosphoranes. The chemistry of compounds containing P–Se
functional groups is studied intensively thanks to their potential
applications of new selenides in semiconducting devices [14] or
as the reagents for organic transformations [15]. The treatment
of 2 with Li2Se resulted to the precipitation of the black material
and no phosphorus signal was detected in 31P NMR spectrum of
the crude reaction mixture. The reaction of 3 and Li2Se gave the
yellow solution without any decomposition. The following addi-
tion of the stoichiometric amount of the sulfur as the oxidizing
agent resulted to the isolation of diselenoxophosphoranes L3PSe2
(11) as the only isolable product of the reaction (Scheme 4).
Compound 11 was characterized by the help of the 1H, 13C, 31P
NMR spectroscopy and molecular structure was clarified by X-ray
structural analysis. The 31P{1H} NMR spectrum revealed one signal
Compound 5 was characterized by 1H, 13C and 31P NMR, IR spec-
troscopy and ESI-MS spectrometry. The 31P{1H} NMR spectrum of 5
revealed the sharp signal at 22.3 ppm that is shifted upfield as
compare to 2 (d 157.9 ppm). The 1H NMR spectrum revealed the
doublet at 8.08 ppm with 1J(1H, 31P) = 612 Hz suggesting the exis-
tence of P–H bond and the broad signal at 3.63 ppm indicating the
presence of P–OH group [1]. Additionally, the IR spectroscopy
showed the characteristic vibration at 1217 cmꢀ1 that was as-
signed to the P@O functional group. All these data suggest the for-
mation of 5 as the only hydrolytic product of 2. The hydrolysis
pathway is thus similar to the compound 3 which provided com-
pound 6, where the leaving HCl coordinated CH2NMe2 groups
(Chart 2) [1]. The full scan positive-ion ESI mass spectrum of 5
showed protonated molecule [M+H]+ at m/z 439 and its dimeric
analog [2M+H]+ at m/z 877 (see Fig. 1C). The presence of mesithyl-
oxy and hydroxylic group was confirmed by neutral losses ob-
served in tandem mass spectrum of m/z 439 (Fig. 1D).
The reactions of 2 and 3 with LiAlH4 provided compounds L2PH2
(7) and L3PH2 (8) as the result of substitution of P–Cl bonds
(Scheme 3). This substitution was not achieved, however, in the
case of 1.
Compound 7 was characterized by the help of the 1H, 13C and
31P NMR spectroscopy. The 31P{1H} NMR spectrum revealed one
signal at ꢀ159.9 ppm that is shifted upfield as compare to 2
(d 157.9 ppm). The 31P NMR spectrum showed the triplet at
ꢀ159.9 ppm with 1J(31P, 1H) = 207 Hz and proved the presence of
PH2 fragment in 7. The similar result was achieved in the 1H
NMR spectrum of 7 where the doublet at 3.73 ppm with 1J(1H,
31P) = 207 Hz demonstrated the presence of PH2 group as well.
Compound 8 was prepared and characterized according to the lit-
erature procedure [1].
The treatment of 7 and 8 with nBuLi and following addition of
Me3SnCl resulted to the preparation of L2PH(SnMe3) (9) and
L3PH(SnMe3) (10) as white and gray oil (see Scheme 3). Both com-
pounds are soluble in aliphatic and aromatic solvents and showed
similar behavior in the solution. The 1H NMR spectrum revealed
the AB spin system at 5.06 ppm for CH2O group in 9 (AB spin sys-
tem at 3.49 ppm for CH2N group in 10) and doublet at 3.66 ppm
with 1J(1H, 31P) = 194 Hz defining the presence of P–H bond in 9
Fig. 2. General view (ORTEP) of a molecule showing 50% probability displacement
ellipsoids and the atom-numbering scheme for 11. The hydrogen atoms are omitted
for clarity. Selected bond lengths [Å] and angles [°] for 11. Se1–P1 2.1039(11), Se2–
P1 2.0770(12), P1–C1 1.806(4), P1–N1 1.964(4), N1–P1–Se2 104.87(12), C1–P1–Se1
109.31(14), N1–P1–Se1 105.68(12), Se2–P1–Se1 122.32(5).
Scheme 3. The studied reactivity of 2 and 3.
Scheme 4. The preparation of diselenoxophosphorane 11.

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at 114.3 ppm with 1J(31P, 77Se) = 818 Hz and both values are com-
Appendix A. Supplementary material
parable to those found in the other intramolecularly coordinated
diselenoxophosphoranes, MxPSe2 (dP 149.6 ppm) [3a], MamxPSe2
(dP 123.6 ppm) [4], MaarPSe2 (dP 108.7 ppm) [6], PixPSe2 (dP
147.7 ppm) [5], and the value of the 31P chemical shift is shifted
upfield compared with sterically protected diselenoxophosphora-
ne ArPSe2 (where Ar is 2,4,6-tri-t-butylphenyl group, dP
273.0 ppm) [16]. The monitoring of the reaction also showed the
presence of the signals at 143.1 ppm [1J(31P, 77Se) = 832 Hz] and
at 52.1 ppm, which were tentatively assigned to L3PSeS and L3PS2
(see Scheme 4). These complexes could not be isolated, however.
The 1H NMR spectrum of 11 showed the presence of AB spin sys-
tem at 3.58 ppm and singlet at 3.59 ppm for CH2 groups defining
the non-equivalence of methylene groups. The isolation of disele-
noxophosphoranes 11 was unambiguously established by X-ray
diffraction analysis and the molecular structure of 11 is depicted
in Fig. 2. The P@Se bond lengths for 11 (P(1)–Se(1)
= 2.1039(12) Å and P(1)–Se(2) = 2.0771(12) Å) are similar to those
found for the other diselenoxophosphoranes (range of 2.079–
2.102 Å) [5,17]. The value is much more shorter then the P–Se sin-
gle bonds in 1,3-diselenadiphosphetane 2,4-diselenide [17c] and
related compounds (range of 2.232–2.284 Å) [18]. The value of
bond angle Se(1)–P(1)–Se(2) is 122.32° and is similar to the value
found in related N ? P coordinated diselenoxophosphorane Pix-
PSe2 (121.8°) [5]. The value of the P(1)–N(1) distance being
1.964(4) Å shows the presence of a strong N ? P intramolecular
coordination in 11 that is shorter to that found in N ? P coordi-
nated diselenoxophosphorane PixPSe2 (2.039(5) Å) [5]. On con-
trary, the value of P(1)–N(2) distance being 3.156(4) Å is
comparable to the sum of the van der Waals radii of P and N atom
(3.4 Å) and defines the second nitrogen atom N(2) remains non-
coordinated to central P(1) atom in 11.
CCDC 740283; contains 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. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.ica.2010.06.008.
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In summary, we have prepared organophosphorus compounds
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chemical properties of the prepared compound strongly depends
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bond by Lewis acidic phosphorous atom was observed in the case
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rupture and allowed the synthesis of monoorganophosphorus
compounds 2, 5 and 7. While the presence of the oxygen lone pair
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Acknowledgment
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The authors wish to thank the Grant Agency of the Czech
Republic (project Nos. GA370468 and GA106/10/0443) and The
Ministry of Education of the Czech Republic (projects Nos.
MSM0021627501, MSM0021627502) for financial support.
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