Stable N-phosphorylated 1,2,4-triazol-5-ylidenes: Novel ligands for metal complexes

Article abstract of DOI:10.1021/om300872g

Synthetic routes to novel N-phosphorylated 1,2,4-triazolium salts have been developed. Treatment of the specified salts with strong base produces new stable N-phosphorylated 1,2,4-triazol-5-ylidenes, which add Se in two stages (first at the carbene carbon

Full text of DOI:10.1021/om300872g

Article
pubs.acs.org/Organometallics
Stable N‑Phosphorylated 1,2,4-Triazol-5-ylidenes: Novel Ligands for
Metal Complexes
Anatoliy P. Marchenko,† Heorgiy N. Koidan,† Evgeniy V. Zarudnitskii,† Anastasiya N. Hurieva,†
Andrey A. Kirilchuk,† Aleksandr A. Yurchenko,† Andrea Biffis,‡ and Aleksandr N. Kostyuk*,†
†Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Murmanska Str. 5, Kyiv-94, 02094 Ukraine
‡Dipartimento di Scienze Chimiche, Universita
̀
di Padova, via Marzolo 1, I-35131 Padova, Italy
S
* Supporting Information
ABSTRACT: Synthetic routes to novel N-phosphorylated
1,2,4-triazolium salts have been developed. Treatment of the
specified salts with strong base produces new stable N-
phosphorylated 1,2,4-triazol-5-ylidenes, which add Se in two
stages (first at the carbene carbon and then at phosphorus)
and rearrange to C-phosphorylated triazoles with heating. The capacity of such N-phosphorylated triazol-5-ylidenes to act as
bidentate ligands toward transition-metal centers has also been demonstrated; in particular, the formation of two dinuclear silver
carbene complexes is described herein. The structures of one representative carbene and of one carbene complex were
determined by an X-ray study.
Another promising bis-carbene of the 1,2,4-triazole series,
namely 1,2,4-trimethyltriazol-3,5-diylidene (ditz), was reported
by Bertrand et al. as a building block for organometallic
polymer synthesis.16 Recently, coordination of ditz with a series
of transition metals was reported, which affords discrete homo-
and heterobinuclear complexes.17−22 Some of these complexes
proved to be active catalysts in three different tandem
processes.
Bitriazol-2-ylidene (bitz), which has a planar structure due to
a direct N−N bond linking the azole rings, has already been
proven to be a potential ligand for broad applications in
transition-metal chemistry.23,24
Additional dicarbene ligands were proposed, in which two
triazolylidene moieties were connected by a short linker, mainly
a methylene group (A). Ligands of this type were used for the
synthesis of complexes with Rh, Pd, Cr, and W.25−27
We have recently reported that the reaction of 1-
alkylimidazoles with phosphorus(III) halides produces unstable
halides of N-phosphorylated imidazolium.28 Triflate analogues
of such salts appeared to be stable and were isolated. On
treatment with strong bases the latter gave stable N-
phosphorylated and N,N′-diphosphorylated imidazol-2-yli-
denes, which were also isolated and characterized. The obtained
imidazol-2-ylidenes rearranged to 2-phosphorylated imidazoles
with heating.
INTRODUCTION
■
N-Heterocyclic carbenes (NHCs) have established themselves
as versatile and powerful ligands for homogeneous catalysis. In
addition to numerous reviews, a few books devoted to NHCs
have been published recently.1 Overwhelming attention has
been paid to imidazol-2-ylidenes and imidazolidin-2-ylidenes; in
these ligands, changing the wingtip substituents allows the fine
tuning of steric properties, whereas introducing substituents at
the 4- and/or 5-positions allows significant influence over the
basicity. Nevertheless, research toward alternative NHC ligand
scaffolds has also flourished in recent times, as well as research
toward multidentate ligands involving NHCs together with
other coordinating moieties.2
Although carbenes based on the 1,2,4-triazole scaffold, where
an additional nitrogen atom is present in the heterocyclic ring,
have received relatively little attention, some promising results
have been achieved (Figure 1). The most famous among the
1,2,4-triazolylidenes is 1,3,4-triphenyl-4,5-dihydro-1H-1,2,4-tri-
azol-5-ylidene (TPT), which was first prepared and studied by
Enders et al.3−7 The ubiquitous TPT was used for synthesis of a
series of complexes with Pd,8−10 Ru,11,12 Pt,13 Ir,14 and group 6
metals.15
Considering the probable generality of such a “carbene”
mechanism for the rearrangement of N-phosphorylated 1,3-
azoles, the investigation of intermediates of phosphorylation of
1,2,4-triazoles is of interest. Therefore, in continuing our
studies on the mechanism of phosphorylation of nitrogen-
containing heterocycles, we report here on the phosphorylation
Figure 1. The most popular 1,2,4-triazolylidenes (TPT, ditz, bitz, A)
and the subject of this study (B).
Received: September 12, 2012
© XXXX American Chemical Society
A
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Scheme 1. Synthesis of Triazolium Salts 4a−d
Table 1. Properties of Phosphorylated Triazol-5-ylidenes 5a−c and of Other Triazol-5-ylidenes 10−25 Reported in the
Literature
bond length, Å
substance no.
R3
R4
R5
δ(13C) C5, ppm
N1−C5−N4 angle, deg
N1−C5
N4−C5
5a
P(t-Bu)2
Me
Ph
Ph
Ph
Ph
Ph
220.44
220.20
220.57
214.6
206.6
208.6
206.2
209.2
210.7
210.6
212.7
210.1
203.8
203.8
201.8
204.2
204.7
207.4
206.1
5b
P(t-Bu)2
Et
5c
103
P(t-Bu)2
i-Pr
102.12
100.6
1.350
1.351
1.359
1.373
Ph
Ph
1130
1230
1331
1431
1532
1632
1732
1832
1933
2033
2133
2233
2333
2433
2533
t-Bu
4-F-C6H4−
4-F-C6H4−
t-Bu
2-Cl-C6H4−
Ph
a
1-Ad
4-R6-C6H4−
3-R6-C6H4−
1-naphthyl
4-Br-C6H4-
Ph
100.19
1.338
1.390
a
1-Ad
Ph
1-Ad
Ph
1-Ad
Ph
1-Ad
Ph
1-Ad
4-Br-C6H4−
4-Br-C6H4−
Me
−CHCHCHCH−
−CHCHCHCH−
−CHCHCHCMe−
−CHCHCHCH−
−CHCHCHCMe−
−CHCHCHCH−
−CHCHCHCMe−
Et
Et
Ph
Ph
2-(i-Pr)-C6H4−
2-(i-Pr)-C6H4−
a
of 1,2,4-triazoles and on the synthesis of a new type of triazol-5-
ylidene, B (Figure.1). Furthermore, we demonstrate here for
the first time that N-phosphorylated azolylidene ligands can act
as bidentate ligands toward metal centers, with NHC and
trivalent phosphorus as coodination sites.
butylphosphino)-3-phenyl-1H-1,2,4-triazole (2), a white crys-
talline compound that is sensitive to air. The 31P NMR shift of
triazole 2 at δ 98 ppm is in the usual range for phosphinous
amides, although it lies downfield compared to that of the
known 1-(diisopropylphosphino)-1H-1,2,4-triazole (δ 79
ppm).29 Treatment of compound 2 with i-PrOTf in CH2Cl2
gives triazolium salt 4c. In the 31P NMR spectrum of the
reaction mixture, two resonance signals appear (124 and 117
ppm, 1:1 ratio) which evidence that both N2 and N4 atoms are
alkylated in the process. The N2-alkylated isomer, characterized
RESULTS AND DISCUSSION
■
The desired triazolium salts 4 were obtained by two routes
(Scheme 1). The first includes transformation of 3-phenyl-4H-
1,2,4-triazole (1) to potassium 3-phenyl-4H-1,2,4-triazolide,
which is then phosphorylated by t-Bu2PBr to form 1-(di-tert-
B
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by a more upfield 31P NMR shift, was not isolated. The target
compound 4c was separated by extraction with ether.
The second route (Scheme 1) involves phosphorylation of 4-
alkyl-3-phenyl-4H-1,2,4-triazoles 3a,b by t-Bu2PBr/NaOTf or
(i-Pr2N)2POTf giving salts 4a,b,d. As evidenced by the 31P
NMR spectra of reaction mixtures, phosphorylation occurs at
either nitrogen atomN1 or N2. Two resonance signals are
observed (ca. 126 and 116 ppm (80:20) for 4a, 128 and 114
ppm (85:15) for 4b, only target compound for 4d), with the
peak representing the target compound lying downfield.
Crystallization allows the separation and isolation of the target
salts.
As is known, nonphosphorylated triazol-5-ylidenes often
dimerize slowly at room temperature to give enetetramines.33
However, such dimerization was not observed in the case of
carbenes 5a−d because of the availability of a more preferred
path, namely rearrangement to 3-phosphorylated triazoles 6a−
d (Scheme 2). The thermal stability of carbenes 5a−d toward
such a rearrangement decreases in the sequence 5c (R1 = i-Pr,
R2 = t-Bu) > 5a (R1 = Me, R2 = t-Bu) > 5b (R1 = Et, R2 = t-Bu)
> 5d (R1 = Et, R2 = N(i-Pr)2): for example, 5d rearranges in a
few hours at room temperature, which also accounts for the
difficulty in its isolation, whereas the rearrangement of 5b at the
same temperature takes several days (see the Experimental
Section for details). Furthermore, it is significant that N-
phosphorylated triazol-5-ylidenes are less stable than the
corresponding N-phosphorylated imidazol-2-ylidenes. Thus,
heating to 90 °C for 50 min is required for the complete
rearrangement 5a → 6a, whereas it takes 1 h at 150 °C for the
rearrangement 26 → 27 (Scheme 3) to proceed to
completion.28
It is important to remark that while it is well-known that
phosphorylation of 1,2,4-triazoles in the presence of a base
proceeds at the 3-position, no intermediates of this process
have been ever isolated. In this work, N-phosphorylated 1,2,4-
triazolium salts, N-phosphorylated triazolylidenes, and finally 3-
phosphorylated triazoles were all isolated and characterized,
and the interconversion between these species has been
demonstrated. This leads us to postulate N-phosphorylated
triazolylidenes as a likely intermediate in the phosphorylation
process. Furthermore, experimental evidence suggests that such
a carbene-mediated reaction of 1,2,4-triazoles with phosphorus-
(III) halides, and in particular the migration step of the
phosphorus group from N to C, proceeds with an
intermolecular reaction mechanism. We have in fact noted
that a concentration increase leads to an increase in the rate of
rearrangement. In addition, there is a well-studied migration of
silyl groups from N to C in 1,2,4-triazoles which proved to be
intermolecular in nature.34 An intermolecular mechanism may
also account for the observed difference in stability toward
rearrengement of imidazol-5-ylidenes and 1,2,4-triazol-5-
ylidenes: the former are more nucleophilic at carbon in
comparison to the latter but presumably also less electrophilic
at phosphorus; hence, the sum of these factors may result in
higher stability of N-phosphorylated imidazol-5-ylidenes.
3-Phosphorylated triazoles 6a−d were transformed into
selenium derivatives 7a−d (Scheme 2). On the other hand,
as in the case of most NHCs, compounds 5a−d add first
selenium to divalent carbon, forming selones 8a−d; subsequent
oxidation of phosphorus atom with Se takes place only under
prolonged (15−120 h) treatment of selones 8a−d with Se
(Scheme 2).28
Compounds 4a−d are light-colored, moisture-sensitive
solids, exhibiting doublets of C5 at δ ∼150−153 ppm with a
coupling constant of ∼30 Hz in their 13C NMR spectra. The
1
peak of proton H5 is, as expected, deshielded with a H NMR
shift of ∼10 ppm (J ≈ 3 Hz).
Salts 4a−d react with sodium bis(trimethylsilyl)amide in
THF, forming N-phosphorylated triazolylidenes 5a−d, which,
except for 5d (see below), could be isolated and characterized.
They are air-sensitive, crystalline compounds, which do not
1
show the H5 signal at δ ∼10 ppm in the H NMR spectra. In
the 13C NMR spectra, a highly deshielded signal, characteristic
of a carbene center, emerges at δ ∼220 ppm. This peak appears
in the range typical for nonphosphorylated (205−220 ppm)
and N-phosphorylated (219−224 ppm)28 imidazol-2-ylidenes.
However, the carbene atoms of compounds 5a−c have the
most downfield shift among the known triazol-5-ylidenes
(201−214 ppm) (cf. Table 1).
A single crystal of carbene 5c, suitable for X-ray diffraction
analysis, was grown from pentane. The X-ray crystal structure
of compound 5c is depicted in Figure 2. The N3−C1−N2 angle
Figure 2. Molecular structure of 5c. Selected bond lengths (Å) and
The structure of compounds 5a−d, exhibiting two strongly
σ-donating but chemically different coordinating groups at the
carbene carbon and at the trivalent phosphorus atom, makes
them very interesting bidentate ligands for transition metals.
Although coordination of these ligands in a chelating fashion is
not in principle precluded, the formation of a four-membered
ring obviously disfavors this coordination mode; consequently,
it is expected that such compounds should preferably act as
bridging ligands between two metal centers. Indeed, air-stable
silver(I) complexes 28b,c were obtained by reaction of silver
oxide with 2 equiv of 4b,c, respectively, in dichloromethane
(Scheme 4). After workup, complexes 28b,c were isolated as
highly thermally stable white crystals.
angles (deg): C1−N3 = 1.359(4), N3−C2 = 1.384(4), C2−N1
1.303(4), N1−N2 = 1.416(3), N2−C1 = 1.350(4); N2−C1−N3
102.1(2).
=
=
at the carbene center and the N2−C1 and N3−C1 bond lengths
are in the range typical for NHCs (cf. Table 1). Planes of C2-
phenyl and triazole rings make up an angle of ca. 60°, twice as
large as in the case of known triazol-5-ylidenes (ca. 30°).3,31
Steric hindrance causes the isopropyl and di-tert-butylphosphi-
no groups to twist out as well (corresponding torsion angles are
C1−N3−C3−C5 = −74.5(4)° and N1−N2−P1−C12
−73.7(2)°).
=
C
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Scheme 2. Chemical Properties of Carbenes 5
phosphine complexes previously reported.33,35 The Ag−Ag
Scheme 3. Rearrangement of Imidazol-2-ylidene 26
Scheme 4. Synthesis of Silver Complexes 28
distance (2.881 Å) is small and comparable to the convention-
ally tabulated covalent radius for silver (1.45
0.05 Å),
although estimates of this parameter in the case of two-
coordinate silver(I) compounds point instead to a value of 1.33
Å.36 A covalent bond formation cannot be postulated between
the two silver(I) centers, but it is likely that closed-shell d10−d10
interactions are present at such a short intermetallic distance.37
Triazole rings are planar; moreover, silver atoms and adjacent
phosphorus atoms all lie in the same plane. In comparison to a
related parent carbene (Table 2) the geometry of the triazole
ring is not subject to substantial changes, except for some
shortening of bond distances (ca. 0.01 Å).
Table 2. Comparison of the Properties of Triazol-5-ylidene
5c and Complex 28b
The molecular structure of 28b was determined by means of
single-crystal X-ray diffraction analysis (Figure 3). As expected,
the complex is dinuclear, with C−Ag−P angles of ca. 168°. Ag−
C and Ag−P bond lengths (Ag−C = 2.12 Å, Ag−P = 2.37 Å)
are in agreement with those of other silver(I) carbene and
bond length, Å
N1−C5−
substance
no.
δ(13C)
N4 angle,
deg
R3
R4
R5 C5, ppm
N1−C5 N4−C5
5c
P(t-
Bu)2
i-Pr Ph
220.57
102.12
1.350
1.359
28b
P(t-
Bu)2
Et Ph
174.10
103.23
1.335
1.353
In conclusion, synthetic routes to N-phosphorylated
triazolium triflates were developed. It was shown that the
obtained triazolium salts react with strong bases to form N-
phosphorylated triazol-5-ylidenes, which rearrange to C-
phosphorylated triazoles with heating. Triazolium salts react
with silver(I) oxide to give novel and highly stable dinuclear
phosphinocarbene complexes. Further investigations on the
properties of these complexes as well as on their use as
transmetalating reagents toward other metal centers are
currently underway.
EXPERIMENTAL SECTION
■
General Methods. All procedures with air- and moisture-sensitive
compounds were performed under an atmosphere of dry argon in
flame-dried glassware. Compounds 1 and 3 were dried before use by
distillation in vacuo over P2O5. Solvents were purified and dried by
standard methods. Melting points were determined with an electro-
́
Figure 3. Molecular structure of 28b. Selected bond lengths (Å) and
angles (deg): C1−N2 = 1.35(1), N2−C2 = 1.377(8), C2−N3 = 1.29(1),
N3−N1 = 1.410(9), N1−C1 = 1.335(9), P1−Ag2 = 2.398(2), C1−Ag1 =
2.146(6); N2−C1−N1 = 103.2(6), C1−Ag1−P2 = 166.9(2).
1
thermal capillary melting point apparatus and were uncorrected. H
NMR spectra were recorded on spectrometers working at 500.13 or
D
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299.94 MHz. 13C NMR spectra were recorded at 125.75 MHz. 31P
NMR spectra were recorded at 121.42 MHz. Chemical shifts (δ) are
reported in ppm downfield relative to internal TMS (for 1H, 13C) and
external 85% H3PO4 (for 31P). Chromatography was performed on
silica gel 60 (0.040−0.063 mm).
129.35, 129.76, 132.58, 120.72 (q, J = 320.5 Hz), 122.77, 150.30 (d, J
= 31.4 Hz), 156.12 (d, J = 2.5 Hz). 31P NMR (81 MHz, CDCl3): δ
127.4. 19F NMR (188 MHz, CDCl3): δ −79.9. Anal. Calcd for
C20H31F3N3O3PS (481.51): C, 49.89; H, 6.49; N, 8.73. Found: C,
49.67; H, 6.31; N, 8.55.
Crystallographic measurements were performed at 173(1) K on a
diffractometer operating in the ω and φ scan modes. The structure was
solved by direct methods refined by full-matrix least-squares
techniques in anisotropic approximation for non-hydrogen atoms
using SHELXS97 and SHELXL97 program packages. Hydrogen atoms
were located from Fourier synthesis and refined isotropically.
3-(Di-tert-butylphosphino)-5-phenyl-4H-1,2,4-triazole (2).
Solution of 1 (3.36 g, 23.1 mmol) in THF (20 mL) was added to
cooled solution of t-BuOK (3.10 g, 27.6 mmol) in THF (25 mL). The
precipitate that formed was filtered. Yield: 3.98 g (94%). A solution of
t-Bu2PBr (4.55 g, 20.2 mmol) in THF (17 mL) was added to a frozen
suspension of potassium 3-phenyl-1,2,4-triazolide (3.70 g, 20.2 mmol)
in THF (34 mL). The mixture was warmed to room temperature,
filtered from KBr precipitate, and evaporated. The obtained residue
was crystallized from pentane. Yield: 5.18 g (89%) of a light yellow
1-[Bis(diisopropylamino)phosphino]-4-ethyl-3-phenyl-4H-
1,2,4-triazol-1-ium Trifluoromethanesulfonate (4d). A solution
of 3b (1.33 g, 7.7 mmol) in CH2Cl2 (7.5 mL) was added to a solution
of bis(diisopropylamino)phosphonium trifluoromethanesulfonate (2.8
g, 7.3 mmol) in CH2Cl2 (7.5 mL) cooled to −30 °C. The solution was
warmed to room temperature, and solvent was evaporated. The
obtained residue was dissolved in Et2O at 40 °C and was cooled to
−15 °C for crystallization. The crystals that formed were washed with
cool ether and dried in vacuo. Yield: 3.80 g (94%) of a light yellow
powder. Mp: 103−105 °C. 1H NMR (300 MHz, CDCl3): δ 1.19 (d, J
= 6.9 Hz, 24H), 1.42 (t, J = 7.2 Hz, 3H), 3.67 (sept, J = 6.6 Hz, 4H),
4.43 (q, J = 7.2 Hz, 2H), 7.6 (m, 5H), 9.57 (s, 1H). 13C NMR (125
MHz, CDCl3): δ 15.69, 23.64 (d, J = 8.8 Hz), 43.00, 48.26 (d, J = 12.6
Hz), 120.76 (q, J = 320.6 Hz), 123.28, 129.01, 129.60, 132.10, 144.76,
154.57. 31P NMR (81 MHz, CDCl3): δ 120.7. 19F NMR (188 MHz,
CDCl3): δ −78.5. Anal. Calcd for C23H39F3N5O3PS (553.62): C,
49.90; H, 7.10; N, 12.65. Found: C, 49.73; H, 7.01; N, 12.43.
1-(Di-tert-butylphosphino)-4-methyl-3-phenyl-1,2,4-triazol-
5-ylidene (5a). Compound 4a (2.87 g, 6.30 mmol) was dissolved in
THF (11 mL) and cooled to −95 °C. Then a solution of NaHMDS
(1.16 g, 6.30 mmol) in THF (11 mL) was added over 10 min. The
mixture was warmed to room temperature, and 31P NMR was
unchanged throughout this time. Solvent was removed in vacuo, the
residue obtained was extracted with pentane (40 mL), and the extract
was held at −6 °C for 3 days for crystallization of the product. The
remainder from extraction was extracted with CH2Cl2 for isolation of
additional quantities of product. The crystals obtained were joined.
1
powder. Mp: 52−53 °C. Bp: 140−145 °C/0.05 mm. H NMR (500
MHz, CDCl3): δ 1.27 (d, J = 13 Hz, 18 H), 7.41 (br d, J = 7.5 Hz,
1H), 7.45 (br t, J = 7, 2H), 8.20 (d, J = 8, 2H), 8.34 (s, 1H). 13C NMR
(125 MHz, CDCl3): δ 28.81 (d, J = 15.1 Hz), 35.12 (d, J = 22.6 Hz),
126.56, 128.54, 129.26, 131.24, 153.60 (d, J = 3.6 Hz), 164.84. 31P
NMR (81 MHz, CDCl3): δ 98.0. Anal. Calcd for C16H24N3P (289.36):
C, 66.41; H, 8.36; N, 14.52. Found: C, 66.30; H, 8.49; N, 14.33.
1-(Di-tert-butylphosphino)-4-methyl-3-phenyl-4H-1,2,4-tria-
zol-1-ium Trifluoromethanesulfonate (4a). t-Bu2PBr (5.44 g, 24.2
mmol) was added to a solution of 3a (3.40 g, 21.3 mmol) and sodium
trifluoromethanesulfonate (7.17 g, 41.7 mmol) in THF (24 mL). The
resulting solution was stirred for 20 h at room temperature. Then
solvent was removed in vacuo, and the residue was washed with ether
and crystallized from CH2Cl2. Yield: 5.75 g (59%) of white crystals.
1
Overall yield: 1.34 g (70%) of yellow crystals. Mp: 101−103 °C. H
NMR (500 MHz, C6D6): δ 1.34 (d, J = 12 Hz, 18H), 3.49 (s, 3H), 7.0
(m, 3H), 7.34 (d, J = 7 Hz, 2H). 13C NMR (125 MHz, C6D6): δ 28.82
(d, J = 16.3 Hz), 34.60 (d, J = 26.4 Hz), 34.91, 127.1, 128.41, 128.69,
129.47, 153.39, 220.44 (d, J = 62.9 Hz). 31P NMR (81 MHz, C6D6): δ
101.1. Anal. Calcd for C17H26N3P (303.38): C, 67.30; H, 8.64; N,
13.85. Found: C, 67.19; H, 8.45; N, 13.71.
1
Mp: 108−111 °C. H NMR (300 MHz, CDCl3): δ 1.30 (d, J = 13.5
Hz, 18H), 4.15 (s, 3H), 7.52−7.76 (br m, 5H), 10.12 (d, J = 2.7 Hz,
1H). 13C NMR (125 MHz, CDCl3): δ 28.46 (d, J = 16.3 Hz), 35.25,
35.88 (d, J = 28.9 Hz), 122.40, 123.23 (q, J = 334,4 Hz), 128.93,
129.30, 129.53, 152.69 (d, J = 30.2 Hz), 156.70. 31P NMR (81 MHz,
CDCl3): δ 126.8. 19F NMR (188 MHz, CDCl3): δ −79.0. Anal. Calcd
for C18H27F3N3O3PS (453.46): C, 47.68; H, 6.00; N, 9.27. Found: C,
47.54; H, 6.17; N, 9.43.
1-(Di-tert-butylphosphino)-4-ethyl-3-phenyl-1H-1,2,4-tria-
zolyl-5-ylidene (5b). A solution of NaHMDS (0.79 g, 4.3 mmol) in
THF (9 mL) was added to a −90 °C solution of 4b (2.02 g, 4.30
mmol) in THF (14 mL) over 5 min. The reaction mixture was held for
15 min at 100 °C. Then the solvent was thoroughly evaporated in
vacuo and the residue that was obtained was extracted with pentane
(56 mL). The crude product was crystallized from pentane. Yield: 0.47
g (34%) of white crystals. Mp: 75−76 °C. 1H NMR (300 MHz,
C6D6): δ 1.21 (br t, 3H), 1.37 (d, J = 12.3 Hz, 18 H), 3.96 (q, J = 6.9
Hz, 3H), 7.02−7.10 (br m, 3H), 7.30−7.36 (br m, 2H). 13C NMR
(125 MHz, C6D6): δ 16.60, 28.85 (d, J = 15.1 Hz), 34.64 (d, J = 27.7
Hz), 42.32, 122.16, 128.49, 128.75, 129.46, 152.99, 220.20 (d, J = 62.9
Hz). 31P NMR (81 MHz, C6D6): δ 103.2. Anal. Calcd for C18H28N3P
(317.40): C, 68.11; H, 8.89; N, 13.24. Found: C, 68.33; H, 8.95; N,
13.39.
1-(Di-tert-butylphosphino)-4-ethyl-3-phenyl-4H-1,2,4-tria-
zol-1-ium Trifluoromethanesulfonate (4b). t-Bu2PBr (7.42 g, 33
mmol) was added to a solution of 3b (5.71 g, 33.0 mmol) and sodium
trifluoromethanesulfonate (5.67 g, 33.0 mmol) in THF (28 mL). The
resulting solution was stirred for 4 days at 16 °C. Then solvent was
removed in vacuo and the residue was extracted with CH2Cl2. The
solvent was evaporated, and the residue obtained after extraction was
carefully washed with ether and benzene (34 mL). Crystals were
filtered and dried in vacuo. Yield: 9.75 g (63%) of colorless crystals.
1
Mp: 121−123 °C. H NMR (300 MHz, CDCl3): δ 1.33 (d, J = 13.5
Hz, 18H), 1.52 (t, J = 7.5 Hz, 3H), 4.60 (q, J = 7.5 Hz, 2H), 7.61−7.73
(br m, 5H), 10.23 (d, J = 3 Hz, 1H). 13C NMR (125 MHz, CDCl3): δ
25.90, 28.46 (d, J = 16.3 Hz), 35.90 (d, J = 28.8 Hz), 44.01, 120.67 (q,
J = 319.4 Hz), 122.64, 129.16, 129.64, 132.54, 151.67 (d, J = 30 Hz),
156.30 (d, J = 2.5 Hz). 31P NMR (81 MHz, CDCl3): δ 128.6. 19F
NMR (188 MHz, CDCl3): δ −78.6. Anal. Calcd for C19H29F3N3O3PS
(467.49): C, 48.81; H, 6.25; N, 8.99. Found: C, 48.72; H, 6.11; N,
8.73.
1-(Di-tert-butylphosphino)-4-isopropyl-3-phenyl-1H-1,2,4-
triazolyl-5-ylidene (5c). A solution of NaHMDS (0.61 g, 3.3 mmol)
in THF (11 mL) was added at −95 °C over 10 min to a solution of 4c
(1.6 g, 3.3 mmol) in THF (11 mL). The mixture was warmed to room
temperature, and the solvent was evaporated in vacuo. The residue was
twice crystallized from degassed pentane (37 mL for the first time, 11
mL for the second). Yield: 0.35 g (32%) of a white powder. Mp: 91−
1-(Di-tert-butylphosphino)-4-isopropyl-3-phenyl-4H-1,2,4-
triazol-1-ium Trifluoromethanesulfonate (4c). A solution of
isopropyl trifluoromethanesulfonate (2.04 g, 10.6 mmol) in CH2Cl2
(8 mL) was added to a frozen solution of 2 (3.07 g, 10.6 mmol) in
CH2Cl2 (15 mL). After a day at room temperature the solvent was
evaporated and the residue was extracted with warm ether. Yield: 1.68
1
92 °C. H NMR (500 MHz, C6D6): δ 0.84 (m, 1H), 0.99 (d, J = 17
Hz, 6H), 1.34 (d, J = 12 Hz, 18 H), 7.5 (br m, 4H), 7.27 (t, J = 8 Hz,
1H). 13C NMR (125 MHz, C6D6): δ 26.00, 28.94 (d, J = 16.3 Hz),
34.68 (d, J = 27.7 Hz), 48.41, 128.56, 129.09, 129.45, 140.76, 152.59,
220.57 (d, J = 62.9 Hz). 31P NMR (81 MHz, C6D6): δ 101.0. Anal.
Calcd for C19H30N3P (331.43): C, 68.85; H, 9.12; N, 12.68. Found: C,
68.72; H, 9.33; N, 12.79.
1
g (33%) of light yellow crystals. Mp: 112−114 °C. H NMR (500
MHz, CDCl3): δ 1.35 (d, J = 13 Hz, 18 H) 1.67 (d, J = 7 Hz, 6H), 4.82
(m, 1H), 7.6−7.7 (br m, 5H), 10.37 (s, 1H). 13C NMR (125 MHz,
CDCl3): δ 22.64, 28.46 (d, J = 16.3 Hz,), 35.93 (d, J = 30.2 Hz), 52.92,
3-(Di-tert-butylphosphino)-4-methyl-5-phenyl-4H-1,2,4-tria-
zole (6a). Compound 5a (0.1 g., 0.3 mmol) was dissolved in benzene
E
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Article
(0.6 mL), and the solution was heated to 90 °C for 50 min. The
solvent was evaporated. and the residue was crystallized from pentane.
Quantitative yield (0.1 g) of light yellow crystals. Mp: 142−143 °C. 1H
NMR (400 MHz, CDCl3): δ 1.29 (d, J = 12.8 Hz, 18H), 3.79 (s, 3H),
7.53−7.62 (br m, 5H). 13C NMR δ 29.01 (d, J = 17.6 Hz), 35.44,
36.36 (d, J = 28.9 Hz), 125.78, 128.57, 129.16, 131.12, 153.60, 173.15
(d, J = 30.2 Hz). 31P NMR (81 MHz, CDCl3): δ 97.5. Anal. Calcd for
C17H26N3P (303.38): C, 67.30; H, 8.64; N, 13.85. Found: C, 67.51; H,
8.45; N, 13.91.
3-(Di-tert-butylphosphino)-4-ethyl-5-phenyl-4H-1,2,4-tria-
zole (6b). A solution of 5b (0.1 g in 0.5 mL of C6D6) was held for 4
days at 25 °C Then benzene was evaporated, and the residue was
crystallized from pentane (1.6 mL). Yield: 0.06 g (60%) of a white
powder. Mp: 94−97 °C. 1H NMR (500 MHz, C6D6): δ 1.20−1.32 (br
m, 21H), 3.96 (m, 2H), 7.11−7.19 (m, 3H), 7.56 (m, 2H). 13C NMR
(125 MHz, C6D6): δ 15.99, 22.34, 30.05 (d, J = 13.8 Hz), 33.22 (d, J =
15.1 Hz), 39.20 (d, J = 15.1 Hz), 128.54, 128.69, 129.20, 129.01,
154.33 (d, J = 1.2 Hz). 31P NMR (81 MHz, C6D6): δ 3.7. Anal. Calcd
for C18H28N3P (317.41): C, 68.11; H, 8.89; N, 13.24. Found: C, 68.17;
H, 8.76; N, 13.33.
3-(Di-tert-butylphosphino)-4-isopropyl-5-phenyl-4H-1,2,4-
triazole (6c). Carbene 5c (0.1 g, 0.3 mmol) was dissolved in benzene
(0.5 mL). The solution was heated for 1 h at 90 °C. Then the solvent
was evaporated and the residue was crystallized from pentane (1.6
mL). Yield: 0.09 g (90%) of a light yellow powder. Mp: 103−104 °C.
1H NMR (500 MHz, CDCl3): δ 1.19 (d, J = 6.5 Hz, 6H), 1.36 (d, J =
17.5 Hz, 18H), 4.04 (sept., J = 6.5 Hz, 1H), 7.31 (m, 3H), 7.56 (d, J =
7.5 Hz, 2H). 13C NMR (125 MHz, CDCl3): δ 23.60, 26.19, 38.60 (d, J
= 73.8 Hz), 48.52, 114.58 (d, J = 1.2 Hz), 127.87, 127.99, 128.57,
140.06 (d, J = 2.5 Hz), 156.42 (d, J = 8.8 Hz). 31P NMR (81 MHz,
CDCl3): δ 13.3 (m). Anal. Calcd for C19H30N3P (331.44): C, 68.85;
H, 9.12; N, 12.68. Found: C, 68.69; H, 9.21; N, 12.73.
3-[Bis(diisopropylamino)phosphino]-4-ethyl-5-phenyl-4H-
1,2,4-triazole (6d). A solution of NaHMDS (0.51 g, 2.8 mmol) in
THF (11 mL) was added over 10 min to a −90 °C solution of 4d
(1.53 g, 2.8 mmol) in THF (11 mL). The mixture was warmed to
room temperature and was held for 5 h. Then the solvent was
evaporated and the residue was crystallized from pentane. Yield: 0.98 g
(88%), colorless crystals. Mp: 126−127 °C. 1H NMR (500 MHz,
CDCl3): δ 1.12 (d, J = 6.5 Hz, 12H), 1.28 (d, J = 6.5 Hz, 12H), 1.31
(t, J = 7 Hz, 3H), 3.73 (sept, J = 6.5 Hz, 4H), 4.16 (q. d, J = 7 Hz, J = 2
Hz, 2H), 7.4 (m, 3H), 7.6 (m, 2H). 13C NMR (125 MHz, CDCl3): δ
16.15 (d, J = 5.0 Hz), 23.70 (d, J = 7.5 Hz), 23.90 (d, J = 5.0 Hz),
39.33 (d, J = 12.6 Hz), 48.18 (d, J = 11.3 Hz), 128.47, 128.70, 128.74,
129.47, 153.84 (d, J = 2.5 Hz), 158.04 (d, J = 13.8 Hz); 31P NMR (81
MHz, CDCl3): δ 25.3. Anal. Calcd for C22H38N5P (403.54): C, 65.48;
H, 9.49; N, 17.35. Found: C, 65.61; H, 9.63; N, 17.44.
(q, J = 6.9 Hz, 2H), 7.49−7.61 (br m, 5H). 13C NMR (125 MHz,
CDCl3): δ 17.32, 27.97 (d, J = 1.2 Hz), 40.74 (d, J = 40.0 Hz), 41.18,
127.34, 128.94, 129.22, 130.34, 142.22 (d, J = 125.7 Hz), 156.92 (d, J
= 5.0 Hz). 31P NMR (81 MHz, CDCl3): δ 64.0. Anal. Calcd for
C18H28N3PSe (396.37): C, 54.54; H, 7.12; N, 10.60. Found: C, 54.47;
H, 7.25; N, 10.41.
3-(Di-tert-butylphosphoroselenoyl)-4-isopropyl-5-phenyl-
4H-1,2,4-triazole (7c). Compound 6c (0.090 g., 0.27 mmol) was
dissolved in benzene (1 mL), and Se (0.050 g,6.3 mmol) was added.
The mixture was stirred for 20 h at 15 °C. Then the solvent was
evaporated and the residue obtained was purified by plate
chromatography on SiO2, eluent CH2Cl2. The fraction with Rf =
0.3−0.4 was isolated. Yield: 0.10 g (95%) of a light yellow powder.
1
Mp: 180−182 °C. H NMR (400 MHz, CDCl3): δ 1.34 (d, J = 16.4
Hz, 18 H) 1.39 (d, J = 6.4 Hz, 6H), 4.56 (br s, 1H), 7.25 (t, J = 3.6 Hz,
2H), 7.42 (t, J = 7.8 Hz, 2H), 7.50 (br t, .J = 8 Hz, 1H). 13C NMR
(125 MHz, CDCl3): δ 20.59, 27.84, 40.32 (d, J = 52.8 Hz), 48.67,
108.24, 127.96, 128.28, 129.16, 130.93, 164.01. 31P NMR (81 MHz,
CDCl3): δ 88.8. MS m/z (EI): 241.0, 309.0, 409.2, 410.2, 412.2. Anal.
Calcd for C19H30N3PSe (410.39): C, 55.61; H, 7.37; N, 10.24. Found:
C, 55.48; H, 7.51; N, 10.43.
3-[Bis(diisopropylamino)phosphoroselenoyl]-4-ethyl-5-phe-
nyl-4H-1,2,4-triazole (7d). Compound 6d (0.35 g, 0.87 mmol) was
dissolved in benzene (3.5 mL), and Se (0.30 g, 3.8 mmol) was added.
The mixture was stirred for 20 h at 19 °C. Then the precipitate was
filtered off and the filtrate was evaporated. The residue obtained was
purified by plate chromatography on SiO2, eluent CH2Cl2. The
fraction with Rf = 0.1−0.35 was separated and crystallized from
pentane. Yield: 0.21 g (50%) of a white powder. Mp: 147−148 °C. 1H
NMR (300 MHz, CDCl3): δ 1.23 (t, J = 7.3 Hz, 3H), 1.34 (d, J = 7.0
Hz, 12H), 1.44 (d, J = 7.0 Hz, 12H), 4.14 (sept, J = 6.8 Hz, 4H), 4.75
(q, J = 6.9 Hz, 2H), 7.5 (m, 3H), 7.6 (m, 2H). 13C NMR (125 MHz,
CDCl3): δ 15.73, 23.86 (d, J = 3.8 Hz), 23.97 (d, J = 2.5 Hz), 41.13,
48.62 (d, J = 6.3 Hz), 127.93, 128.86, 128.90, 130.11, 149.93 (d, J =
145.8 Hz), 156.76 (d, J = 7.5 Hz). 31P NMR (81 MHz, CDCl3): δ
44.8. MS m/z (EI): 174.2, 383.2, 440.2, 482.2, 484.2, 487.2. Anal.
Calcd for C22H38N5PSe (482.50): C, 54.76; H, 7.94; N, 14.51. Found:
C, 54.61; H, 7.81; N, 14.37.
2-(Di-tert-butylphosphino)-4-methyl-5-phenyl-2,4-dihydro-
3H-1,2,4-triazole-3-selone (8a). Selenium (0.28 g, 3.5 mmol) was
added to a solution of 5a (1.1 g, 3.6 mmol) in benzene (6 mL). The
mixture was held for 1 h at room temperature, the solvent was
removed in vacuo, and the residue obtained was extracted with
pentane (3 × 20 mL). Pentane was evaporated. Yield: 0.80 g (58%) of
1
colorless crystals. Mp: 153−154 °C. H NMR (400 MHz, CDCl3): δ
1.29 (d, J = 12.8 Hz, 18H), 3.79 (s, 3H), 7.52−7.61 (br m, 5H). 13C
NMR (125 MHz, CDCl3): δ 29.01 (d, J = 17.6 Hz), 35.44, 36.36 (d, J
= 28.9 Hz, 125.78, 128.57, 129.16, 131.12, 153.60 (d, J = 1.3 Hz),
173.15 (d, J = 30.2 Hz). 31P NMR (81 MHz, CDCl3) 97.5. Anal. Calcd
for C17H26N3PSe (382.34): C, 53.40; H, 6.85; N, 10.99. Found: C,
53.51; H, 6.73; N, 10.79.
3-(Di-tert-butylphosphoroselenoyl)-4-methyl-5-phenyl-4H-
1,2,4-triazole (7a). Compound 6a (0.1 g., 0.3 mmol) was dissolved
in benzene (1 mL), and Se (0.05 g, 0.63 mmol) was added. The
mixture was stirred for 20 h at 15 °C. Then the solvent was evaporated
and the residue was crystallized from pentane. The product was
purified by plate chromatography on SiO2, eluent CH2Cl2. The
fraction with Rf = 0.5−0.7 was separated. Yield: 0.09 g (90%). Mp:
2-(Di-tert-butylphosphino)-4-ethyl-5-phenyl-2,4-dihydro-
3H-1,2,4-triazole-3-selone (8b). Selenium (0.20 g, 2.5 mmol) was
added to a solution of 5b (0.79 g., 2.5 mmol) in benzene (6 mL). The
mixture was held for 2 h at 0 °C. Solvent was evaporated; the residue
obtained was extracted with pentane (2 × 32 mL) and crystallized
from pentane (16 mL). Yield: 0.56 g (57%) of light yellow crystals.
1
113−114 °C. H NMR (500 MHz, CDCl3): δ 1.53 (d, J = 17.0 Hz,
18H), 4.25 (s, 3H), 7.55 (br m, 3H), 7.66 (br m, 2H). 13C NMR (125
MHz, CDCl3): δ 27.97 (d, J = 2.5 Hz), 35.96, 40.76 (d, J = 33.9 Hz),
1256.66, 128.91, 129.43, 130.41, 157.44 (d, J = 5.0 Hz), 143.14 (d, J =
70.4 Hz). 31P NMR (81 MHz, CDCl3): δ 63.1.MS m/z (EI): 160.1,
328.0, 382.0, 384.1, 387.1. Anal. Calcd for C17H26N3PSe (382.34): C,
53.40; H, 6.85; N, 10.99. Found: C, 53.51; H, 6.71; N, 10.82.
1
Mp: 164−165 °C. H NMR (300 MHz, CDCl3): δ 1.3 (br m, 21H),
4.34 (quad, J = 7.2 Hz, 2H), 7.58 (br m, 5H). 13C NMR (125 MHz,
CDCl3): δ 14.05, 28.99 (d, J = 17.6 Hz), 36.32 (d, J = 28.9 Hz), 42.68,
125.97, 128.49, 129.20, 131.07, 153.48, 172.21 (d, J = 30.2 Hz). 31P
NMR (81 MHz, CDCl3): δ 99.08. Anal. Calcd for C18H28N3PSe
(396.37): C, 54.54; H, 7.12; N, 10.60. Found: C, 54.31; H, 7.01; N,
10.45.
3-(Di-tert-butylphosphoroselenoyl)-4-ethyl-5-phenyl-4H-
1,2,4-triazole (7b). Compound 6b (0.06 g., 0.19 mmol) was
dissolved in benzene (2 mL), and Se (0.015 g, 0.18 mmol) was
added. The mixture was stirred for 15 h at 15 °C. Then the mixture
was filtered off, the filtrate was evaporated, and the residue was purified
by plate chromatography on SiO2, eluent CH2Cl2. The fraction with Rf
= 0.05−0.15 was separated and crystallized from pentane. Yield: 0.06 g
(80%) of pale crystals. Mp: 112−113 °C. 1H NMR (300 MHz,
CDCl3): δ 1.23 (t, J = 6.9 Hz, 3H), 1.49 (d, J = 17.1 Hz, 18H), 4.91
2-(Di-tert-butylphosphino)-4-isopropyl-5-phenyl-2,4-dihy-
dro-3H-1,2,4-triazole-3-selone (8c). Se (0.18 g, 2.2 mmol) was
added to a solution of 5c (0.75 g, 2.3 mmol) in benzene (6 mL). The
suspension was stirred for 2 h at 15 °C, and then solvent was
evaporated. The residue was extracted with pentane (3 × 20 mL).
1
Yield: 0.68 g (75%) of a white powder. Mp: 130−131 °C. H NMR
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(500 MHz, CDCl3): δ 1.27 (d, J = 12.5 Hz, 18H), 1.40 (d, J = 6 Hz,
6H), 5.26 (br s, 1H), 7.44 (d, J = 6.5 Hz, 2H), 7.51 (t, J = 7.5 Hz, 2H),
7.56 (t, J = 7.5 Hz, 1H). 13C NMR (125 MHz, CDCl3): δ 20.96, 29.02
(d, J = 16.3 Hz), 36.36 (d, J = 28.9 Hz), 52.49, 127.37, 128.72, 129.74,
130.83, 153.77, 171.54 (d, J = 31.4 Hz). 31P NMR (81 MHz, CDCl3):
δ 96.0. Anal. Calcd for C19H30N3PSe (410.39): C, 55.61; H, 7.37; N,
10.24. Found: C, 55.43; H, 7.23; N, 10.11.
min to a −90 °C solution of 4d (2.2 g, 3.9 mmol) in THF (11 mL).
The mixture was stirred for 20 min at −85 °C. Then Se (0.86 g, 11
mmol) was added and the reaction mixture was stirred for 5 days at
room temperature. The solvent was evaporated, and the residue was
extracted with benzene (3 × 30 mL). Benzene was evaporated, and the
residue obtained was purified by plate chromatography on SiO2, eluent
CH2Cl2. The fraction with Rf = 0.2−0.4 was separated and crystallized
from pentane. Yield: 1.16 g (53%) of a light yellow powder. Mp: 118−
119 °C. 1H NMR (500 MHz, CDCl3): δ 1.33 (t, J = 7.5 Hz, 3H), 1.40
(d, J = 7 Hz, 12H), 1.47 (d, J = 7 Hz, 12H), 4.11 (sept., J = 7 Hz, 4H),
4.29 (q, J = 7 Hz, 2H), 7.5 (m, 5H). 13C NMR (125 MHz, CDCl3): δ
13.76, 23.79 (d, J = 5.0 Hz), 24.01 (d, J = 2.5 Hz), 41.61, 49.48, 49.52,
126.01, 128.66, 129.23, 131.06, 151.38 (d, J = 8.8 Hz), 166.19 (d, J =
17.6 Hz). 31P NMR (81 MHz, CDCl3): δ 64.3. MS m/z (EI): 102.2,
132.2, 231.2, 249.4, 309.2, 311.2, 312.2, 459.2, 562.2, 563.2, 568.2.
Anal. Calcd for C22H38N5PSe2 (561.46): C, 47.06; H, 6.82; N, 12.47.
Found: C, 47.24; H, 6.69; N, 12.33.
Bis[1-(di-tert-butylphosphino)-4-ethyl-3-phenyl-1,2,4-tria-
zol-5-ylidene]disilver(I) Bis(trifluoromethanesulfonate) (28b).
Silver(I) oxide (0.28 g, 1.2 mmol) was added to a solution of
compound 4b (0.87 g, 1.9 mmol) in DCM (40 mL). The mixture was
stirred for 2 h at 14 °C and then for 15 h at 29 °C. Then the
precipitate was filtered and dissolved in acetonitrile (20 mL) at 100 °C
(under a temperature higher than that stated, the complex undergoes
decomposition). The hot solution was filtered. After the solution was
cooled, the precipitate was filtered and washed with acetonitrile. Yield:
0.69 g (49%). Mp: 270 °C dec. 1H NMR (500 MHz, CD3CN): δ 1.54
(m, 42H), 4.42 (q, 4H), 7.65−7.80 (m, 10H). 13C NMR (125 MHz,
CD3CN): δ 16.14, 28.02, 37.90, 44.42, 117.32, 121.16 (q, J = 320.6
Hz), 124.32, 129.33, 129.38, 131.82, 157.11. 31P NMR (202 MHz,
2-[Bis(diisopropylamino)phosphino]-4-ethyl-5-phenyl-2,4-
dihydro-3H-1,2,4-triazole-3-selone (8d). A solution of NaHMDS
(0.78 g, 4.2 mmol) in THF (5.6 mL) was added over 10 min to a −90
°C solution of 4d (2.36 g, 4.26 mmol) in THF (9 mL). After 30 min of
stirring at −90 °C Se (0.34 g, 4.3 mmol) was added. The mixture was
warmed to 0 °C and was held for 15 h. The solvent was evaporated,
and the residue was extracted with pentane (3 × 10 g) and crystallized
1
from 5 g of pentane. Yield: 1.8 g (90%) of a light yellow powder. H
NMR (300 MHz, CDCl3): δ 1.18 (d, J = 6.9 Hz, 12H), 1.24 (d, J = 6.9
Hz, 12H), 1.28 (t, J = 7.2 Hz, 3H), 3.64 (sept., J = 6.5 Hz, 4H), 4.25
(q, J = 7.2 Hz, 2H), 7.5 (m, 5H). 13C NMR (125 MHz, CDCl3): δ
14.30, 23.56 (d, J = 8.8 Hz), 24.10 (d, J = 6.3 Hz), 41.26, 47.19 (d, J =
13.8 Hz), 126.85, 128.46, 129.12, 130.62, 152.44 (d, J = 1.2 Hz),
162.43 (d, J = 30.2 Hz). 31P NMR (81 MHz, CDCl3): δ 97.0. Anal.
Calcd for C22H38N5PSe (482.50): C, 54.76; H, 7.94; N, 14.51. Found:
C, 54.59; H, 7.73; N, 14.38.
2-(Di-tert-butylphosphoroselenoyl)-4-methyl-5-phenyl-2,4-
dihydro-3H-1,2,4-triazole-3-selone (9a). Compound 8a (0.58 g,
1.5 mmol) was dissolved in pyridine (2 mL), and Se (0.30 g, 3.8
mmol) was added. The mixture was stirred for 1 day at room
temperature. Pyridine was evaporated, and the residue was extracted
with benzene. Benzene was evaporated, and the residue was purified by
plate chromatography on SiO2, eluent CH2Cl2. The fraction with Rf =
0.3−0.5 was separated. Yield: 0.45 g (64%) of pale crystals. Mp: 158−
CD3CN):
δ 125.4 (d, J = 537 Hz). Anal. Calcd for
1
C38H56Ag2F6N6O6P2S2 (1148.69): C, 39.73; H, 4.91; N, 7.32.
Found: C, 39.65; H, 5.12; N, 7.06.
159 °C. H NMR (500 MHz, CDCl3): δ 1.55 (d, J = 17.5 Hz, 18H),
3.71 (s, 3H), 7.57 (s, 5H). 13C NMR (125 MHz, CDCl3): δ 28.76,
34.56, 45.07 (d, J = 35.2 Hz), 125.03, 128.71, 129.37, 131.58, 152.12
(d, J = 5.0 Hz), 170.47 (d, J = 7.5 Hz). 31P NMR (81 MHz, CDCl3): δ
120.3. MS m/z (EI): 160.0, 237.8, 380.0, 456.0, 461.0, 462.0, 464.0.
Anal. Calcd for C17H26N3PSe2 (461.30): C, 44.26; H, 5.68; N, 9.11.
Found: C, 44.42; H, 5.81; N 9.32.
Bis[1-(di-tert-butylphosphino)-4-isopropyl-3-phenyl-1,2,4-
triazol-5-ylidene]disilver(I) Bis(trifluoromethanesulfonate)
(28c). Silver(I) oxide (0.22 g, 0.95 mmol) was added to a solution
of compound 4c (0.90 g, 1.9 mmol) in DCM (20 mL). The mixture
was stirred for 20 h at 23 °C. The mixture was filtered, the filtrate
obtained was evaporated, and the residue was recrystallized from ether
(40 mL) and then acetonitrile (2 mL). Yield: 0.59 g (53%). Mp: 241−
2-(Di-tert-butylphosphoroselenoyl)-4-ethyl-5-phenyl-2,4-di-
hydro-3H-1,2,4-triazole-3-selone (9b). Compound 8b (0.2 g, 0.5
mmol) was dissolved in benzene (2.3 mL), and Se (0.06 g, 0.76 mmol)
was added. The mixture was stirred for 4 days at 16 °C. Then the
solvent was evaporated and the residue was purified by plate
chromatography on SiO2. The fraction with Rf = 0.2−0.6 was
separated and crystallized from hexane. Yield: 0.17 g (72%) of white
crystals. Mp: 193−195 °C. 1H NMR (300 MHz, CDCl3): δ 1.26 (t, J =
7.3 Hz, 3H), 1.57 (d, J = 18 Hz, 18H), 4.27 (quad, J = 6.9 Hz, 2H),
7.51 (br m, 3H), 7.65 (br m, 2H). 13C NMR (125 MHz, CDCl3): δ
15.52, 28.53 (d, J = 2.5 Hz), 41.13, 44.78 (d, J = 21.4 Hz), 127.90,
128.79, 128.82, 130.07, 140.38 (d, J = 6.3 Hz), 156.45. 31P NMR (81
MHz, CDCl3): δ 125.0 (m). MS m/z (EI): 174.0, 249.8, 470.0, 475.0,
476.0. Anal. Calcd for C18H28N3PSe2 (475.33): C, 45.48; H, 5.94; N,
8.84. Found: C, 45.65; H, 5.73; N, 8.67.
1
243 °C dec. H NMR (500 MHz, CD3CN): δ 1.55 (d, J = 17.5 Hz,
18H), 1.74 (d, J = 6.5 Hz, 6H), 4.78 (m, 1H), 7.6−7.8 (m, 5H). 13C
NMR (125 MHz, CD3CN): δ 24.56, 28.08 (d, J = 10 Hz), 38.09,
51.22, 117.28, 121.21 (q, J = 320 Hz), 124.25, 129.35, 129.83, 131.85,
157.49. 31P NMR (121 MHz, CD3CN): δ 129.5 (d, J = 528.2 Hz). 19
F
NMR (188 MHz, CD3CN):
C40H60Ag2F6N6O6P2S2 (1176.75): C, 40.83; H, 5.14; N, 7.14.
δ −78.0. Anal. Calcd for
Found: C, 40.52; H, 5.25; N, 7.33.
ASSOCIATED CONTENT
* Supporting Information
■
S
Figures giving 1H, 13C, and 13C APT NMR spectra for
compounds 2, 4a−d, 5a−c, 6a−d, 7a−d, 8a−d, 9a−d, 28b,c
and CIF files giving X-ray crystallographic data for 5c and 28b.
This material is available free of charge via the Internet at
http://pubs.acs.org.
2-(Di-tert-butylphosphoroselenoyl)-4-isopropyl-5-phenyl-
2,4-dihydro-3H-1,2,4-triazole-3-selone (9c). Se (0.1 g, 1.3 mmol)
was added to 0.23 g (0.56 mmol) of 8c, dissolved in pyridine (2 mL).
The mixture was held for 15 h at 15 °C. The solution obtained was
partitioned by plate chromatography on SiO2, eluent CH2Cl2. The
fraction with Rf = 0.2−0.4 was isolated. Yield: 0.2 g (73%) of a
AUTHOR INFORMATION
Corresponding Author
*E-mail: a.kostyuk@yahoo.com.
■
1
colorless powder. Mp: 148−149 °C. H NMR (500 MHz, CDCl3): δ
1.31 (s, 6H), 1.55 (d, J = 17.5 Hz, 18 H), 5.59 (s, 1H), 7.44 (d, J = 8
Hz, 2H), 7.55 (t, J = 7.5 Hz, 2H), 7.61 (t, J = 7 Hz, 1H). 13C NMR
(125 MHz, CDCl3): δ 21.06, 28.84, 45.25 (d, J = 35.2 Hz), 51.14,
127.01, 128.82, 129.72, 131.14, 152.06 (d, J = 6.3 Hz), 169.71. 31P
NMR (81 MHz, CDCl3): δ 120.2. Anal. Calcd for C19H30N3PSe2
(489.35): C, 46.63; H, 6.18; N, 8.59. Found: C, 46.48; H, 6.32; N,
8.41.
Notes
The authors declare no competing financial interest.
REFERENCES
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dx.doi.org/10.1021/om300872g | Organometallics XXXX, XXX, XXX−XXX