Preparation of carbonyltungsten(0) complexes of 2-pyridylphosphines showing a stepwise coordination pattern by way of monodentate to chelate mode

Article abstract of DOI:10.1016/S0022-328X(03)00698-3

2-Pyridylphosphines, R₂PyP (R=Ph, NMe₂; Py=2-pyridyl), were allowed to react with W(CO)₅(thf) to afford the monocoordinated tungsten(0) complexes on the phosphorus [R₂PyP][W(CO)₅] and their structures were confirmed by X-ray crystallography. No ligation of the 2-pyridyl groups was found but a considerable p-donating effect of the dimethylamino groups in (Me₂N)₂PyP was observed. The monocoordinated complexes were irradiated with light to afford the chelate complexes [R₂PyP][W(CO)₄] by loss of one CO from the pentacarbonyls. X-ray structural analysis and spectroscopic data of [R₂PyP][W(CO)₄] indicated that the electron-donating effect of the nitrogen atom in the 2-pyridyl group upon the carbonyls is slightly larger than that of the phosphorus atom in spite of the reluctant coordination at the early stage of ligation.

Full text of DOI:10.1016/S0022-328X(03)00698-3

Journal of Organometallic Chemistry 682 (2003) 79Á84
/
www.elsevier.com/locate/jorganchem
Preparation of carbonyltungsten(0) complexes of 2-pyridylphosphines
showing a stepwise coordination pattern by way of monodentate to
chelate mode
Katsunori Nishide, Shigekazu Ito, Masaaki Yoshifuji *
Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Sendai, 980-8578, Japan
Received 28 May 2003; received in revised form 4 July 2003; accepted 15 July 2003
Abstract
2-Pyridylphosphines, R2PyP (Rꢀ
/
Ph, NMe2; Pyꢀ2-pyridyl), were allowed to react with W(CO)5(thf) to afford the
/
monocoordinated tungsten(0) complexes on the phosphorus [R2PyP][W(CO)5] and their structures were confirmed by X-ray
crystallography. No ligation of the 2-pyridyl groups was found but a considerable p-donating effect of the dimethylamino groups in
(Me2N)2PyP was observed. The monocoordinated complexes were irradiated with light to afford the chelate complexes
[R2PyP][W(CO)4] by loss of one CO from the pentacarbonyls. X-ray structural analysis and spectroscopic data of [R2PyP][W(CO)4]
indicated that the electron-donating effect of the nitrogen atom in the 2-pyridyl group upon the carbonyls is slightly larger than that
of the phosphorus atom in spite of the reluctant coordination at the early stage of ligation.
# 2003 Elsevier B.V. All rights reserved.
Keywords: 2-Pyridylphosphines; Tungsten; Coordination; X-ray crystallography
1. Introduction
preparation of synthetic catalysts [6]. Thus, diami-
no(pyridyl)phosphines are attractive, but the derivatives
have not been reported so far.
Diphenyl(2-pyridyl)phosphine (1) has been used for
ligands of metal complexes analogously to triphenylpho-
sphine [1]. Basically 1 behaves as a phosphorus-mono-
dentate ligand for transition metal complexes and
indeed more than one equivalent of 1 coordinate on
one metal even if 1 possesses competitive coordinating
sites at P and N [1,2]. Compound 1, however, may act as
a chelating ligand to afford the four-membered ring
structure [3], but the studies on conversion of the
coordination mode from monodentate to chelate have
been limited so far [4]. In addition to triarylphosphines,
such phosphines as bis(dimethylamino)phenylphosphine
bearing amino group(s) are expected to display some
unique properties due to the effect of additional nitro-
gen-containing moieties [5] and may be utilized for
We have previously reported coordination properties
of 2-chloro-3,3-diphenyl-1-(2,4,6-tri-t-butylphenyl)-1,3-
diphosphapropene (2) which possesses low-coordinated
sp2 phosphorus atom and a normal sp3-phosphino
phosphorus atom within a molecule and is considered
to be a congener of 1 [7]. Both of the monodentate and
chelate coordinations of 2 on the tungsten metal were
found indicating the stepwise coordinating nature due to
the difference of basicity of the two different phospho-
rus atoms. Moreover, we have recently reported a 3,3-
diamino-1,3-diphosphapropene to utilize it for novel
low-coordinated phosphorus compounds.[8]
Here we report structural elucidation of a monoden-
tate tungsten(0) complex of 1 and conversion to the
corresponding chelate derivative. Moreover, we report a
complex formation reaction of bis(dimethylamino)(2-
pyridyl)phosphine (3) with a carbonyltungsten(0) re-
agent.
* Corresponding author. Tel.: ꢁ81-22-217-6558.
E-mail address: yoshifj@mail.tains.tohoku.ac.jp (M. Yoshifuji).
/
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00698-3

80
K. Nishide et al. / Journal of Organometallic Chemistry 682 (2003) 79Á84
/
Table 1
Bond lengths (A) and bond angles (8) around the tungsten metal for
compounds 4Á
˚
/7
4
5
6
7
2. Results and discussion
WÁ
WÁ
WÁ
WÁ
WÁ
WÁ
WÁ
C1Á
C2Á
C3Á
C4Á
C5Á
/
P
2.529(2)
2.540(1)
2.543(2)
2.256(5)
1.947(7)
1.985(8)
2.049(8)
2.049(8)
2.507(2)
2.273(7)
1.94(1)
1.99(1)
2.03(1)
2.05(1)
/N
Á/
Á/
/
C1
C2
C3
C4
C5
2.053(8)
2.034(8)
2.061(9)
2.071(8)
2.016(8)
1.11(1)
2.057(5)
2.049(6)
2.059(6)
2.049(6)
1.997(5)
1.121(6)
1.131(7)
1.119(6)
1.134(6)
1.145(6)
1.837(5)
1.671(4)
1.682(4)
1.339(6)
107.6(1)
2.1. Preparation and characterization of monodentate
tungsten(0) complexes
/
/
/
Complex 4 was prepared from 1 and W(CO)5(thf) as a
pale yellow solid almost quantitatively. The most
spectroscopic data of 4 were identical with the reported
data by Zhang et al. [9].1 The molecular structure was
unambiguously characterized by X-ray crystallography
and an ORTEP drawing is displayed in Fig. 1 [10]. As
displayed in Table 1, the PÁW distance is shorter
compared with the corresponding values in
[Ph3P][W(CO)5] (2.545(1) A) [11] or [Mes*Pꢀ
˚
C(Cl)PPh2][W(CO)5] (2.540(1) A) [7], probably due to
/
Á/
Á/
/
O
O
O
O
O
1.160(8)
1.137(10)
1.126(9)
1.126(9)
1.17(2)
1.13(1)
1.11(1)
1.10(2)
/
1.15(1)
/
1.12(1)
/
1.09(1)
/
1.129(9)
1.840(7)
1.838(6)
1.821(6)
1.408(9)
111.5(2)
Á/
Á/
PÁ/Py
1.831(6)
1.823(5)
1.823(5)
1.338(10)
83.7(3)
1.840(9)
1.636(9)
1.689(7)
1.35(1)
PÁ/R
/
CÁ
WÁ
PÁWÁ
WÁ
PÁCÁ
RÁP-Py
/N(Py)
˚
/
/PÁ
/
C
84.8(3)
63.6(2)
/
/N
Á/
Á/
Á/
Á/
63.2(1)
the greater p-accepting ability of 3 rather than that of
triphenylphosphine as well as 2. On the other hand, the
/NÁ
/
C
108.6(4)
104.6(5)
108.1(2)
108.1(2)
104.8(3)
107.7(5)
103.8(6)
109.7(4)
102.0(4)
102.0(5)
/
/
N
114.0(5)
103.2(3)
102.6(3)
102.5(3)
114.8(3)
102.0(2)
100.7(2)
113.0(2)
/
WÁ
/
Cax (WÁ
/
C5) distance in 4 is slightly longer than that
˚
in [Ph3P][W(CO)5] (2.006(5) A) [11] as well as
RÁ/PÁR
/
˚
[2][W(CO)5] (1.996(4) A) [7], which corresponds to the
˚
O) distances: [Ph3P][W(CO)5]: 1.125(6) A
CÁ
/
Oax (C5Á
/
˚
[2]; [W(CO)5]: 1.156(5) A. The average WÁ
/
Ceq and the
respectively, which are comparable to the corresponding
˚
data of [Ph3P][W(CO)5] (2.033(5), 1.135(6) A) [11]. The
˚
Oeq distances in 4 are 2.06(1) A and 1.1(1) A,
˚
CÁ
/
distance between the nitrogen atom and the tungsten
˚
metal in 4 is 3.86 A, indicating that there is no bonding
nature, and moreover the torsion angle of NÁ
/
C1Á
/
PÁW
/
was 54.8(6)8.
Similarly diamino(pyridyl)phosphine (3), prepared
from the reaction of 2-bromopyridine with butyllithium
and then with chlorobis(dimethylamino)phosphine [12],2
was allowed to react with W(CO)5(thf) to afford the
corresponding complex 5. Complex 5 was stable in the
air and purified by column chromatography on silica
gel. Molecular structure of 5 is described in Fig. 2. The
phosphorus atom solely coordinates on the tungsten
metal and is less pyramidalized judging from the sum of
the angles of 3168, compared with that of 4 (3088),
probably due to the p-donating effect of the nitrogen
atoms.
Fig. 1. Molecular structure of 4 with 30% probability ellipsoids.
2
Compound 3 was allowed to react with four equivalents of HCl to
afford 2-pyridylphosphonous dichloride (PyPCl2: dP 139) and was
converted to 2-pyridylphosphine (PyPH2) by reduction with LiAlH4.
1
The JPW value in this article was described as the half value.

K. Nishide et al. / Journal of Organometallic Chemistry 682 (2003) 79Á
/84
81
2.2. Chelate carbonyltungsten(0) complexes
The monodentate complex 4 in THF was irradiated
with a mercury lamp (100 W) at 0 8C and the color of
the solution turned red from pale yellow. After the
solvent having been removed in vacuo, the residue was
purified by silica-gel column chromatography to afford
the chelate complex 6 almost quantitatively. The struc-
ture of 6 was confirmed by X-ray crystallography and
Fig. 3 displays its molecular structure. The four-
membered chelate ring is planar. The WÁ/C1 bond is
shorter than the WÁC2 distance, indicating that the
/
electron-donating effect of the nitrogen atom in the
pyridyl group upon the CO group is larger than that of
the phosphino group. On the other hand, in the reaction
of 1 with W(CO)5(thf), the nitrogen atom in the 2-
pyridyl group might first permit the phosphorus atom to
ligate the metal. The angle PÁ
/
CÁN is 104.6(5)8 indicat-
/
Fig. 2. Molecular structure of 5 with 30% probability ellipsoids.
ing a large deformation due to the formation of the four-
membered ring. Similarly chelate complex 7 was ob-
tained from 5 and its molecular structure is shown in
Fig. 4.
Some selected 13C-NMR data for 4 and 5 are listed in
Table 2. There are observed almost the same chemical
shifts as well as the coupling constants JPC found in the
CO ligands and the 2-pyridyl groups. The typical s
coordination on the metal was indicated from the 31P-
NMR data including the 1JPW satellite peaks and the IR
data also supported this ligating mode in 4 and 5 (Table
3).
In the 13C-NMR spectoroscopy of 6 and 7, the large
2JPC values were observed for the COeq carbon atom at
the trans position to the phosphorus atom, respectively
(Table 2). Almost the same 13C-NMR spectroscopic
properties were clarified for both 6 and 7 as well as
[Ph3P][Py][W(CO)4] [2]. The 31P-NMR signals of 6 and 7
were observed at a higher field compared to 4 and 5,
respectively (Table 3). The IR spectroscopic patterns of
Table 2
Selected 13C-NMR data (dC and JPC
a
)
for compounds 4Á
/
7
4
5
6
7
dC
JPC/HZ
dC
JPC/HZ
dC
JPC/HZ
dC
JPC/HZ
COax
COeq
COeq
C2
200.3
197.8
22.7
7.1
200.5
197.7
26.5
8.0
206.5
212.8
212.3
169.2
128.3
137.0
127.7
153.0
6.5
6.6
30.1
46.2
0 c
207.2
213.6
212.7 b
173.0
124.8
136.1
127.2
152.9
7.9
7.3
b
Á/
Á/
Á/
Á/
35.2
52.1
2.8
0 c
0 c
25.1
160.3
127.3
136.5
124.0
150.5
65.9
18.2
5.9
0 c
162.1
125.9
136.1
125.0
150.4
85.0
19.0
6.6
0 c
C3
C4
0 c
C5
C6
0 c
21.5
17.5
16.9
a
Measured at 101 MHz, in CD2Cl2.
CO trans to the atom.
Appeared as a singlet.
b
c

82
K. Nishide et al. / Journal of Organometallic Chemistry 682 (2003) 79Á84
/
Table 3
1
a
b
31P-NMR data (dP and JPW
)
and IR data (nCO
)
for compounds 4Á7
/
4
5
6
7
nCO (cmꢂ1
)
dP
1JPW (Hz)
nCO (cmꢂ1
)
dP
1JPW (Hz)
nCO (cmꢂ1
)
nCO (cmꢂ1
)
1
dP JPW (Hz)
1
dP JPW (Hz)
25 245
2050 c
1980 c
1920 c
111 289
2071
1936
1920
ꢂ
/
11 196
2017
1890
1870
1826
85 245
2002
1890
1871
1840
a
Measured at 162 MHz in CD2Cl2.
Measured as a KBr pellet.
Data taken from Ref. [9].
b
c
the chelate complexes, 6 and 7, changed from those of
the monodentate derivatives.
3. Conclusion
We described preparation and characterization of
monodentate carbonyltungsten(0) complexes of 2-pyr-
idylphosphines revealing that the phosphorus atom
solely coordinated on the metal. These monodentate
complexes were converted to the chelate derivatives by
irradiation of light. Electronic properties of substituents,
2-pyridyl and dimethylamino groups, were character-
ized. This study will prompt further investigation
concerning coordination chemistry as well as develop-
ment of synthetic catalysts. Attempts to replace the
carbonyl groups in 4Á7 with other ligand such as
/
isocyanides to afford novel transition metal complexes
are in progress.
Fig. 3. Molecular structure of 6 with 30% probability ellipsoids.
4. Experimental
4.1. General
All manipulations were carried out under an argon
atmosphere by means of the standard Schlenk techni-
ques or in a glove box. All solvents employed were dried
1
by appropriate methods. H-, 13C{1H}- and 31P{1H}-
NMR spectra were recorded on a Bruker AVANCE400
spectrometer in CDCl3 with Me4Si (1H, 13C) and H3PO4
(31P), respectively, as internal or external standard. IR
spectra were measured on a Horiba FT-300 spectro-
meter as KBr pellets. Melting points were measured on a
Yanagimoto MP-J3 apparatus without correction. Ele-
mental analyses were performed in the Instrumental
Analysis Center for Chemistry, Graduate School of
Science, Tohoku University. MARDI-TOF Mass spec-
tra were recorded on a Bruker autoflex spectrometer.
Compound 1 was prepared by the procedures described
in the literature [13].
Fig. 4. Molecular structure of 7 with 30% probability ellipsoids.

K. Nishide et al. / Journal of Organometallic Chemistry 682 (2003) 79Á
/84
83
4.2. Preparation of 3
4.5. X-ray crystallography
Butyllithium (1.0 mmol, 1.6 M solution in hexane, 1
X-ray diffraction data were collected on a Rigaku
RAXIS-IV imaging plate diffractometer. The structure
was solved by direct methods (SIR-92) [14], expanded
using Fourier techniques (DIRDIF-94) [15]. A symmetry-
related absorption correction using the program AB-
SCOR [16] was applied. The non-hydrogen atoms were
refined anisotropically. The hydrogen atoms were found
Mꢀ
bromopyridine (0.16 g, 1.0 mmol) in THF (20 ml) at
78 8C and was followed by the addition of chloro-
/
1 mol dmꢂ3) was added to a solution of 2-
ꢂ
/
bis(dimethylamino)phosphine (1.0 mmol). The reaction
mixture was warmed to room temperature (r.t.) and
stirred for 2 h. The solvent was removed in vacuo and
the residue was purified by silica-gel column chromato-
graphy (hexane) to afford PyP(NMe2)2 as a colorless oil
containing a small amount of the starting 2-bromopyr-
idine; 31P{1H}-NMR (162 MHz, CD2Cl2) d 99. The
crude material 3 was employed for the preparation of 5.
by the difference Fourier synthesis for 4Á6 but for 7 the
/
hydrogen atoms were generated at the calculated posi-
tions. They were refined isotropically for 5 but not
refined for 4, 6 and 7. Structure solution, refinement,
and graphical representation were carried out using the
TEXSAN package [17].
Compound 4: C22H14NO5PW, Mꢀ587.18, triclinic,
/
˚
9.455(1) A,
¯
4.3. Preparation of 5
P1 (no. 2), aꢀ
aꢀ90.625(3), bꢀ
1064.9(2) A , Zꢀ
1.831 g cmꢂ1, mꢀ5.538 mmꢂ1, F(000)ꢀ
collected reflections, 4455 unique reflections (Rint
0.095), R1ꢀ0.041 (I ꢀ2s(I)), Rwꢀ0.063 (all data),
Sꢀ1.42 (271 parameters).
Compound 5: C14H16N3O5PW, Mꢀ
clinic, P21/n (no. 14), aꢀ7.2042(5), bꢀ16.6954(7), cꢀ
96.874(2)8, Vꢀ1832.7(2) A , Zꢀ
223 K, rꢀ 6.425
1.889 g cmꢂ1, mꢀ
1000.00, 8457 collected reflections,
4163 unique reflections (Rint 0.088), R1ꢀ0.031 (I ꢀ
2s(I)), Rwꢀ0.044 (all data), Sꢀ0.94 (281 parameters).
Compound 6: C21H14NO4PW, Mꢀ559.17, ortho-
rhombic, Pnma (no. 62), aꢀ16.7705(4), bꢀ
/
9.6201(8), bꢀ
95.370(5), gꢀ
2, 2umax 55.08, Tꢀ
/
12.196(1), cꢀ
74.655(2)8, Vꢀ
296 K, rꢀ
564.00, 8535
/
/
/
/
/
3
˚
A THF solution of the crude PyP(NMe2)2, prepared
by the procedure described in Section 4.2, was stirred for
24 h with an excess amount of W(CO)5(thf) (prepared
from W(CO)6 in THF by irradiation for 12 h with a
medium-pressure 100 W Hg lamp at 0 8C). Purification
/
ꢀ
/
/
/
/
/
ꢀ
/
/
/
/
/
by column chromatography (hexaneÁAcOEt, 19:1) gave
[PyP(NMe2)2][W(CO)5] (94 mg, 18% yield based on 2-
/
/
521.12, mono-
/
/
/
3
˚
˚
bromopyridine). Compound 5: yellow crystals, m.p. 87Á
/
15.3474(6) A, bꢀ
2umax 55.08, Tꢀ
mmꢂ1, F(000)ꢀ
/
/
/4,
89 8C; 13C{1H}-NMR (101 MHz, CD2Cl2) d 41.0 (d,
ꢀ
/
/
/
/
2JPC 4.2 Hz, NMe2). H-NMR (400 MHz, CD2Cl2) d
/
1
2.84 (d, 3JPH 10.8 Hz, NMe2). Anal. Found: C, 31.84; H,
3.81; N, 6.23. Calc. for C14H16N3O5PW: C, 32.27; H,
3.09; N, 8.06%. HRMS (MARDI-TOF-MS) Found:
ꢀ
/
/
/
/
/
/
493.105. Calc. for C14H16N3O5PWÁ
/
CO: 493.039.
/
/
3
˚
˚
12.6363(5), cꢀ
2umax 55.08, Tꢀ
mmꢂ1, F(000)ꢀ
1072.00, 16 369 collected reflections,
2384 unique reflections (Rint 0.084), R1ꢀ0.030 (I ꢀ
2s(I)), Rwꢀ0.044 (all data), Sꢀ0.91 (145 parameters).
Compound 7: C13H16N3O4PW, Mꢀ493.11, triclinic,
/
9.4942(4) A, Vꢀ
/
2012.0(1) A , Zꢀ
/
4,
ꢀ
/
/
296 K, rꢀ
/
1.846 g cmꢂ1, mꢀ
/5.854
4.4. Preparation of 6 and 7
/
ꢀ
/
/
/
A THF (0.4 ml) solution of 4 (25 mg, 0.043 mmol)
was irradiated with a medium-pressure 100 W Hg lamp
at 0 8C for 30 h. The solvent was removed in vacuo and
the residue was purified by silica-gel column chromato-
/
/
/
˚
7.0926(6) A,
¯
P1 (no. 2), aꢀ
aꢀ97.282(9), bꢀ
851.1(2) A , Zꢀ
1.924 g cmꢂ1, mꢀ
collected reflections, 3478 unique reflections (Rint
0.150), R1ꢀ0.055 (I ꢀ2s(I)), Rwꢀ0.088 (all data),
Sꢀ1.31 (199 parameters).
/
8.576(1), bꢀ
108.758(9), g
2, 2umax 55.08, Tꢀ
6.907 mmꢂ1, F(000)ꢀ
/
15.399(2), cꢀ
101.364(3)8, Vꢀ
296 K, rꢀ
472.00, 6523
/
/
/
ꢀ
/
/
3
˚
graphy (hexaneÁ/AcOEt, 4:1) to afford 17 mg of 6 (70%
/
ꢀ
/
/
/
yield). Compound 6: yellow crystals, m.p. 183Á
/
185 8C;
/
/
13C{1H}-NMR (101 MHz, CD2Cl2) d 133.6 (d, JPC
ꢀ
/
2
2
14.2 Hz, o-Ph), 131.7 (s, p-Ph), 130.3 (d, JPC 37.7 Hz,
/
/
/
3
ipso-Ph), 129.5 (d, JPC 10.4 Hz, m-Ph), 128.0). Anal.
/
Found: C, 46.57; H, 3.79; N, 2.28. Calc. for
C21H14NO4PW: C, 45.11; H, 2.52; N, 2.50%. HRMS
(MARDI-TOF-MS) Found: 559.031. Calc. for
C14H16N3O5PW: 559.017. Similarly 5 (25 mg, 0.048
mmol) was irradiated in THF (0.4 ml) for 24 h at 0 8C to
afford 16 mg of 7 (68% yield). Compound 7: yellow
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 210859, 210860, 210858 and
210857 for compounds 4, 5, 6 and 7, respectively. Copies
of this information may be obtained free of charge
from The Director, CCDC, 12 Union Road, Cambridge
crystals, m.p. 164Á
/
166 8C; 13C{1H}-NMR (101 MHz,
2 1
CD2Cl2) d 39.3 (d, JPC 9.6 Hz, NMe2); H-NMR (400
3
MHz, CD2Cl2) d 2.75 (d, JPH 10.9 Hz, NMe2). Anal.
Found: C, 31.57; H, 3.39; N, 8.14. Calc. for
C13H16N3O4PW: C, 31.66; H, 3.27; N, 8.52%.
CB2 1EZ, UK (Fax:
ꢁ44-1223-336066; e-mail:
/

84
K. Nishide et al. / Journal of Organometallic Chemistry 682 (2003) 79Á84
/
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Acknowledgements
This work was supported in part by grants-in-aid for
scientific research (nos. 13303039 and 14044012) from
the Ministry of Education, Culture, Sports, Science and
Technology, Japan.
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