A catalytic pathway for the conversion of tungsten-silanes into tungsten-silanols

Article abstract of DOI:10.1016/S0022-328X(98)00727-X

Tungsten substituted silanes C₅H₅(OC)₂(Ph₃P)W-SiMe₂H (3a), C₅Me₅(OC)₂(Me₃P)W-SiMe₂H (3b) and C₅Me₅(OC)₂(Me₃P)W-SiH₃ (6) are converted with urea hydrogenperoxide in the presence of catalytic amounts of MeReO₃ to the corresponding metallo-silanols C₅H₅(OC)₂(Ph₃P)W-SiMe₂OH (4a), C₅Me₅(OC)₂(Me₃P)W-SiMe₂OH (4b) and C₅Me₅(OC)₂(Me₃P)W-Si(OH)₃ (7). Condensation of 4b with R₃SiCl yields the tungsten-substituted disiloxanes C₅Me₅(OC)₂(Me₃P)W-SiMe ₂OSiR₃ (SiR₃=SiMe₂H (5a), SiCl₃ (5b)).

Full text of DOI:10.1016/S0022-328X(98)00727-X

Journal of Organometallic Chemistry 566 (1998) 259–262
A catalytic pathway for the conversion of tungsten-silanes into
tungsten-silanols1
Wolfgang Malisch a,*, Heinrich Jehle a, Catherine Mitchel b, Waldemar Adam b
a Institut fu¨r Anorganische Chemie der Uni6ersita¨t Wu¨rzburg, Am Hubland, 97074 Wu¨rzburg, Germany
b Institut fu¨r Organische Chemie der Uni6ersita¨t Wu¨rzburg, Am Hubland, 97074 Wu¨rzburg, Germany
Received 28 April 1998
Abstract
Tungsten
C5Me5(OC)2(Me3P)W–SiH3 (6) are converted with urea hydrogenperoxide in the presence of catalytic amounts of MeReO3 to the
corresponding metallo-silanols C5H5(OC)2(Ph3P)W–SiMe2OH (4a), C5Me5(OC)2(Me3P)W–SiMe2OH (4b) and
substituted
silanes
C5H5(OC)2(Ph3P)W–SiMe2H
(3a),
C5Me5(OC)2(Me3P)W–SiMe2H
(3b)
and
C5Me5(OC)2(Me3P)W–Si(OH)3 (7). Condensation of 4b with R3SiCl yields the tungsten-substituted disiloxanes
C5Me5(OC)2(Me3P)W–SiMe2OSiR3 (SiR3=SiMe2H (5a), SiCl3 (5b)). © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Metallo-silanes; Metallo-silanols; Oxofunctionalization; MeReO3–UHP
units, creating the conditions for electrophilic oxygena-
tion via oxygen insertion with dimethyldioxirane [3].
This method offers for the first time access to
Cp(OC)2Fe(Ru)-, or C5Me5(OC)2(Me3P)Mo(W)-substi-
tuted silanols [4]. In order to enlarge this class of
compounds we have looked for possibilities to avoid
the time consuming and lavish preparation of dimethyl-
dioxirane. Moreover, the use of a common oxidation
reagent should be realized in a catalytic procedure. In
this context methylrheniumtrioxide (MTO) was prefer-
entially taken into account, whose catalytic activity in
diverse oxygenation processes has been impressively
demonstrated by Herrmann and others [5]. This com-
munication reports about an efficient catalytic pathway
for the oxidation of tungsten-substituted silanes using
urea-hydrogenperoxide in the presence of MTO.
1. Introduction
Metallo-silanoles represent
a
special class of
silanoles, which are characterized by a remarkably high
stability with respect to self condensation. This prop-
erty, which is even valid for silanetriole derivatives [1],
and the generally stable metal–silicon bond makes
these compounds useful precursors towards controlled
condensation with chlorosilanes to build up unusual
arrangements of functionalized siloxanes at metal cen-
tres. Studies concerning the synthesis of metal-frag-
ment-substituted silanols have shown that the usual
access via hydrolysis of the corresponding metallo-
chlorosilanes is strongly limited due to the reduced
electrophilicity of the silicon caused by the electron
releasing transition metal [2]. On the other hand the
metal fragment is responsible for highly hydridic Si–H
* Corresponding author. Tel.: +49 931 8885277; fax: +49 931
8884618; e-mail: Wolfgang.Malisch@mail.uni-wuerzburg.de
2. Results
1 Preliminary communications: Synthesis and reactivity of silicon
transition metal complexes, 45 (part 44); Metallo-silanoles and
metallo-siloxanes, 18 (part 17). W. Malisch, H. Jehle, S. Mo¨ller, Ch.
Saha-Mo¨ller, W. Adam, Eur. J. Inorg. Chem. 1998, in press.
To provide the utmost clear conditions in context
with a catalytic procedure we synthesized model com-
pounds bearing only one Si–H-unit. We focused on
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00727-X

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W. Malisch et al. / Journal of Organometallic Chemistry 566 (1998) 259–262
In addition, chemical proof is obtained for the for-
mation of a Si-bonded hydroxyl group by treatment of
4b, dissolved in toluene, with dimethylchlorosilane and
silicontetrachloride, respectively, in the presence of
Et3N as an auxiliary base. After a reaction period of 48
h the corresponding metallo-siloxanes 5a,b are isolated
in excellent yields as pale yellow microcrystalline pow-
ders (Eq. 3).
tungsten-silanes, since these species have shown high
reactivity with respect to oxygen insertion. Metallo-
dimethylsilanes of this type were obtained by the reac-
tion
of
the
alkaline
metalates
1a,b
with
dimethylchlorosilane 2 in cyclohexane at room temper-
ature in the absence of light. Nucleophilic ligand ex-
change at the silicon [6] generates 3a,b, isolated as beige
microcrystalline solids in good yields after 16 h (Eq. 1).
5a,b represent further interesting examples of
metallo-disiloxanes with
atom, offering the
derivatizations.
a
functionalized k-silicon
The influence of the metal fragment is established by
the low-field 29Si chemical shift [l=1.7 ppm (3a), 7.4
ppm (3b)], as well as by the reduced value of the
1J(SiH) coupling constant [179.6 Hz (3a), 173.7 Hz
(3b)]. In addition the w(Si–H) stretching band is shifted
considerably to lower wavenumbers [2026 (3a), 2031
cm−1(3b)] compared to Me2Si(H)Cl (2278 cm−1).
Treatment of 3a,b with urea-hydrogenperoxide in the
presence of (3–4 mol%) MeReO3 in acetone at −78°C
leads to the formation of the metallo-silanols 4a,b
within 12–14 h (Eq. 2). Completeness of oxygenation is
monitored by the disappearence of the w(Si–H) band at
2026/2031 cm−1. In order to establish the catalytic
activity of MTO, an analogous experiment was run
with 3a using exclusively urea hydrogen peroxide. Be-
sides decomposition of 3a after 12 h no formation of 4a
was observed.
possibility for various
The catalytic oxygenation procedure used in Eq. (2)
is also efficient for Si–H tungsten species having more
than one hydrogen at the silicon. Cp*(OC)2(Me3P)W–
SiH3 (6) is converted in an analogous manner using
MTO/UHP after 14 h into the tungsten-silanetriol 7.
This compound is now obtained in higher yield (94%)
compared to the dioxirane oxidation applied by us to
prepare 7 for the first time (71%) [1].
This paper presents an attractive catalytic pathway
for the oxygenation of metallo-silanes. Characteristic of
this type of process are the extremely mild conditions
(oxidation starts at −78°C) and the good yields.
Forthcoming publications will present further examples
of the application of the catalytic system MeReO3/UHP
for the formation of metallo-silanols as well as for the
oxofunctionalization of other transition metal substi-
tuted element–hydrogen bonding systems.
The metallo-silanols are isolated in good yields [71%
(4a), 78% (4b)] as yellow microcrystalline solids, which
are air stable for a short period of time and can be
stored under nitrogen at room temperature without
decomposition. 4a,b exhibit rather good solubility in
acetone and toluene.
3. Experimental section
All operations were performed under an atmosphere
of purified and dried nitrogen using Schlenk-type tech-
nique. Solvents were dried according to conventional
procedures, distilled and saturated with N2 prior to use.
1H-, 13C{1H}- and 29Si{1H}-NMR spectra were ob-
tained with Bruker AMX 400, Jeol LA 300, Jeol FX
90Q or Bruker AMX 200 spectrometers. l(1H)/(13C)
The 29Si-NMR resonance of the OH substituted sili-
con atoms shows a typical downfield shift of 49.6 ppm
(4a) and 51.5 (4b) ppm compared with 3a (1.7 ppm)
and 3b (7.4 ppm).

W. Malisch et al. / Journal of Organometallic Chemistry 566 (1998) 259–262
261
chemical shifts are reported downfield from Si(CH3)4,
3.2. 1-[Dicarbonyl(p5-cyclopentadienyl)(triphenylphos-
phane)tungsten]-dimethylsilanole (4a)
referenced to the residual proton signal (1H) or natural
abundance carbon signal (13C) of the deuterated sol-
vent. l(29Si) chemical shifts are measured relative to
external Si(CH3)4. IR spectra were recorded on a
Perkin-Elmer 283 grating spectrometer in NaCl cells of
A
solution of 432 mg (0.68 mmol) of
Cp(OC)2(Ph3P)W–SiMe2H (3a) in 10 ml of acetone is
combined with 5.1 mg (0.020 mmol) of MeReO3 and 65
mg (0.69 mmol) of urea-hydrogenperoxide at –78°C.
After stirring for 3 h, the reaction mixture is warmed
up to room temperature and stirred for another 12 h.
Insoluble material is separated and the filtrate evapo-
rated to dryness in vacuo. Remaining 4a is washed with
5 ml of n-pentane and dried in vacuo. Yield: 314 mg
(71%). Yellow microcrystalline powder. M.p.: 78°C.
C27H27O3PSiW (642.41): calc. C 50.48, H 4.23; found C
50.26, H 4.17. 1H-NMR (400.1 MHz, [D6]-benzene):
0.1
mm
path
length.
Starting
materials:
K[W(PPh3)(CO)2Cp] [7], Li[W(PMe3)(CO)2C5R5] (R=
H, Me] [7].
3.1. 1-[Dicarbonyl(p5-cyclopentadienyl)(triphenylphos-
phane)tungsten]-dimethylsilane (3a)/1-[Dicarbonyl-
(p5-pentamethylcyclopentadienyl-(trimethylphos-
phane)tungsten]-dimethylsilane (3b)
4
To a suspension of finely powdered 1a (300 mg (0.51
mmol))/1b (515 mg (1.33 mmol)) in 40 ml of cyclohex-
ane Me2Si(H)Cl (180 mg (1.94 mmol)/366 mg (3.87
mmol)) is added dropwise and the reaction mixture
stirred at room temperature for 18 h/2 h. After removal
of the solvent and excessive silane in vacuo, the residue
is treated three times with 5 ml toluene till the extract
shows no IR-spectroscopic evidence for the presence of
3a/3b. The toluene extracts were combined in vacuo,
evaporated to dryness, the remaining 3a/3b washed at
−30°C with petrolether and dried in vacuo. Yield: 204
mg (64%) (3a)/280 mg (48%) (3b). Ochre microcrys-
talline powders. M.p. 73°C/73°C. 3a: C27H27O2PSiW
(626.41): calc. C 51.77, H 4.34; found C 51.38, H 4.13.
1H-NMR (400.1 MHz, [D6]-benzene): l=7.78 (m, 15
H, phenyl), 5.35 [septd, 3J(HCSiH)=3.6 Hz,
3J(PWSiH)=1.0 Hz, 1J(SiH)=179.6 Hz, 1H, HSi],
4.55 [d, 3J(PWCH)=0.9 Hz, 5 H, H5C5], 0.95 [d,
3J(HSiCH)=3.6 Hz, 6H, (H3C)2Si]. 13C-NMR (100.6
l=7.81 (m, 15 H, phenyl), 4.64 [d, J(PWCH)=0.5
Hz, 5 H, H5C5] 2.2 (s, br, 1 H, OH), 1.08 [s, (H3C)2Si].
13C-NMR (100.6 MHz, [D6]-benzene): l=227.9 [d,
2J(PWC)=18.2 Hz, CO], 143.7−125.6 [(H5C6)3P],
88.7 (s, C5H5), 2.0 ppm [s, (H3C)2Si]. 31P-NMR (162
MHz [D6]-benzene): l=41.8 ppm [s, 1J(WP)=285.3
Hz]. 29Si-NMR (79.5 MHz, [D6]-benzene): l=49.6
2
ppm [d, J(PWSi)=14.2 Hz]. IR (pentane): w(OH)=
3665 (w) cm−1; w(CO)=1898 (s), 1821 (vs) cm−1
.
3.3. Treatment of 3a with urea-hydrogenperoxide (in
the absence of MTO)
A
solution of 216 mg (0.34 mmol) of
Cp(OC)2(Ph3P)W–SiMe2H (3a) in 13 ml of acetone is
combined with 33 mg (0.35 mmol) of urea-hydrogen-
peroxide at −78°C. After stirring for 3 h, the reaction
mixture is warmed up to room temperature and stirred
for another 9 h. After this time no generation of 4a was
observed in the reaction mixture by IR- and NMR-
spectroscopy.
2
MHz, [D6]-benzene): l=228.3 [d, J(PWC)=18.9 Hz,
CO], 143.6−125.5 [(H5C6)3P], 88.3 (s, C5H5), 1.9 ppm
[s, (H3C)2Si]. 31P-NMR (162 MHz [D6]-benzene): l=
41.9 ppm [s, 1J(WP)=288.1 Hz]. 29Si-NMR (79.5
3.4. 1-[Dicarbonyl(p5-pentamethylcyclopenta-
dienyl(trimethylphosphane)tungsten]-dimethylsilanole
(4b)
2
MHz, [D6]-benzene): l=1.7 ppm [d, J(PWSi)=12.3
Hz].-IR (pentane): w(SiH)=2026 (w) cm−1; w(CO)=
1933 (s), 1842 (vs) cm−1. 3b: C17H31O2PSiW (510.34):
1
calc. C 40.01, H 6.27; found C 39.86, H 6.15. H-NMR
According to Section 3.2 from 280 mg (0.55 mol) of
C5Me5(OC)2(Me3P)W–SiMe2H (3b), 5.5 mg (0.022
mmol) of MeReO3 and 51.6 mg (0.55 mmol) of urea-
hydrogenperoxide after 12 h. Yield: 225 mg (78%).
Yellow microcrystalline powder. M.p.: 121°C.
C17H31O3PSiW (526.32): calc. C 38.79, H 5.93; found C
38.53, H 5.79. 1H-NMR (400.1 MHz, [D6]-benzene):
l=2.65 (s, br, 1 H, HO), 1.89 [s, 15 H, (H3C)5C5], 1.29
(200
MHz,
[D6]-benzene):
l=4.76
[septd,
3J(HCSiH)=3.6Hz, 3J(PWSiH)=2.0 Hz, 1J(SiH)=
173.7 Hz, 1 H, HSi], 1.74 [s, 15 H, (H3C)5C5], 1.26 [d,
2J(PCH)=8.9 Hz, 9 H, (H3C)3P], 0.89 ppm [d,
3J(HSiCH)=3.6 Hz, 6 H, (H3C)2Si]. 31P-NMR (36
MHz, [D6]-benzene): l= −13.45 ppm [s, 1J(WP)=
294.9 Hz]. 13C-NMR (50 MHz, [D6]-benzene): l=
231.10 [d, 2J(PWC)=20.0 Hz, 1J(WC)=152.9 Hz,
[d, J (PCH)=9.1 Hz, 9H, (H3C)3P], 0.97 ppm [s, 6 H,
2
1
CO], 100.40 [s, (H3C)5C5
6
], 20.42 [d, J(PC)=33.4 Hz,
(H3C)2Si]. 13C-NMR (100.6 MHz, [D6]-benzene): l=
2
1
(H3C)3P], 11.12 [s, (H3C
6
)5C5], 1.83 ppm [s, (H3C)2Si].
231.8 [d, J(PWC)=21.0 Hz, J(WC)=154.1 Hz, CO],
29Si-NMR (18 MHz, [D6]-benzene): l=7.40 ppm [d,
101.1 [s, (H3C)5C5
6
], 20.0 [d, 1J(PC)=33.8 Hz,
)5C5], 9.5 ppm [s, J(SiC)=51.5
2J(PWSi)=11.7 Hz, J(WSi)=41.8 Hz]. IR (cyclohex-
(H3C)3P], 11.5 [s, (H3C
6
1
1
ane): w(SiH)=2031 (vw) cm−1; w(CO)=1893 (s), 1821
Hz, (H3C)2Si]. 31P-NMR (162 MHz [D6]-benzene): l=
−12.7 ppm [s, 1J(WP)=290.6 Hz]. 29Si-NMR (79.5
(vs) cm−1
.

262
W. Malisch et al. / Journal of Organometallic Chemistry 566 (1998) 259–262
2
1
MHz, [D6]-benzene): l=51.5 ppm [d, J(PWSi)=13.6
CO], 101.48 [s, (H3C)5C5), 19.59 (d, J(PC)=34.4Hz,
1
1
Hz, J(WSi)=42.5 Hz]. IR (THF): w(OH)=3676 (vw),
(H3C)3P), 11.37 (s, (H3C
6
)5C5], 9.50 ppm [s, J(SiC)=
3640 (w, br) cm−1; w(CO)=1895 (s), 1809 (vs) cm−1
.
50.5 Hz, (H3C)2Si]. 29Si-NMR (79 MHz, [D6]-benzene):
2
1
l=63.47 ppm [d, J(PWSi)=14.3 Hz, J(WSi)=56.7
Hz, (H3C)2SiCl3 not observed]. IR (toluene): w(CO)=
3.5. 1-[Dicarbonyl(p5-pentamethylcyclopentadienyl)
(trimethylphosphane)tungsten]-1,1,3,3-tetramethyl-
disiloxane (5a)
1903 (s), 1824 (vs) cm−1
.
3.7. 1-[Dicarbonyl(p5pentamethylcyclopentad-
A solution of 85 mg (0.16 mmol) Cp*(OC)2(Me3P)W-
SiMe2OH (4a) in 8 ml of toluene is combined with 73
mg (0.72 mmol) of Et3N and 85 mg (0.90 mmol) of
Me2Si(H)Cl and the reaction mixture stirred for 2 days
at room temperature. Volatile material is removed in
vacuo and the residue extracted with 20 ml of n-pen-
tane. 5a is isolated after crystallization at −78°C.
Yield: 87 mg (92%). Pale yellow microcrystalline pow-
der. M.p.: 114°C. C19H37O3PSi2W (584.49): calc. C
ienyl)(trimethylphosphane)tungsten]-silanetriol) (4c)
According to Section 3.2 from 50 mg (0.12 mmol) of
C5Me5(OC)2(Me3P)W–SiH3 3c, 3.6 mg (0.014 mmol) of
MeReO3 and 34 mg (0.36 mmol) of urea-hydrogenper-
oxide after 14 h. Yield: 52 mg (94%). Pale yellow
microcrystalline powder. M.p. 103°C. C15H27O5PSiW
(530.29): calc. C 33.98, H 5.13; found C 33.58, H 4.91.
4c was characterized by comparison with authentic
material [1].
1
39.04, H 6.38; found C 38.58, H 6.40. H-NMR (60
MHz, [D6]-benzene): l=5.30 [sept, 3J(HCSiH)=2.8
Hz, 1J(SiH)=200.0 Hz, 1 H, HSi], 1.74 [s, 15 H,
2
(H3C)5C5], 1.15 [d, J(PCH)=9.3 Hz, 9 H, (H3C)3P],
Acknowledgements
0.85 [s, 6 H, (H3C)2SiW], 0.25 ppm [d, 3J(HSiCH)=2.8
Hz, 6 H, (H3C)2Si]. 31P-NMR (162 MHz, [D6]-ben-
zene): l= −12.46 ppm [s, 1J(WP)=285.1 Hz]. 13C-
NMR (100.6 MHz, [D6]-benzene): l=233.01 [d,
We gratefully acknowledge financial support from
the Deutsche Forschungsgemeinschaft (Sonder-
forschungsbereich 347: ‘Selective Reactions of Metal-
Activated Molecules’) as well as from the Fonds der
Chemischen Industrie.
2J(PWC)=20.4 Hz, CO], 101.12 [s, (H3C)5C5
6
], 19.85 [d,
1J(PC)=33.9 Hz, (H3C)3P], 11.47 [s, (H3C
6 )5C5], 9.67 [s,
1J(SiC)=51.5 Hz, (H3C)2SiW], 1.50 ppm [s, (H3C)2Si].
29Si-NMR (18 MHz, [D6]-benzene): l=46.48 [d,
2J(PWSi)=13.9 Hz, 1J(WSi)=46.9 Hz, (H3C)2SiW],
−9.88 ppm [s, (H3C)2Si]. IR (cyclohexane): w(SiH)=
2106 (w) cm−1; w(CO)=1896 (s), 1823 (vs) cm−1. IR
(benzene): w(SiH)=2100 (w) cm−1; w(CO)=1889 (s),
References
[1] W. Malisch, R. Lankat, S. Schmitzer, J. Reising, Inorg. Chem.
34 (1995) 5702.
[2] W. Malisch, S. Schmitzer, G. Kaupp, K. Hindahl, H. Ka¨b, U.
Wachtler, in: N. Auner, J. Weis (Eds), Organosilicon Chemistry,
VCH, Weinheim, 1994, p. 185.
1811 (vs) cm−1; w(SiMe)=1284 (w), 1248 (m) cm−1
w(SiOSi)=1025 (s, br), 591 (w) cm−1
;
.
[3] (a) W. Adam, U. Azzena, F. Prechtl, K. Hindahl, W. Malisch,
Chem. Ber. 125 (1992) 1409. (b) W. Malisch, K. Hindahl, H.
Ka¨b, J. Reising, W. Adam, F. Prechtl, Chem. Ber. 128 (1995)
963. (c) S. Mo¨ller, H. Jehle, W. Malisch, W Seelbach, in: N.
Auner, J. Weis (Eds), Organosilicon Chemistry III: From
Molecules to Materials, VCH, Weinheim, 1998, p. 267.
[4] (a) S. Mo¨ller, O. Fey, W. Malisch, W. Seelbach, J. Organomet.
Chem. 507 (1996) 239. (b) W. Malisch, S. Schmitzer, R. Lankat,
M. Neumayer, F. Prechtl, W. Adam, Chem. Ber. 128 (1995)
1251.
[5] (a) W.A. Herrmann, F.E. Ku¨hn, Acc. Chem. Res. 13 (1997) 169.
(b) A.M. Al-Ajlouni, J.H. Espenson, J. Am. Chem. Soc. 117
(1995) 9243. (c) J. Rudolph, K.L. Reddy, J.P. Chiang, K.B.
Sharpless, J. Am. Chem. Soc. 119 (1997) 6189. (d) F.G.A. Stone,
R. West, Adv. Organomet. Chem. 41 (1997) 127.
3.6. 1-[Dicarbonyl(p5-pentamethylcyclopentadie-
nyl)(trimethylphosphane)tungsten]-1,1-dimethyl-3,3,3-
trichlorodisiloxane (5b)
According to Section 3.5 from 147 mg (0.28 mmol) of
C5Me5(OC)2(Me3P)W–SiMe2OH (4a), 85 mg (0.84
mmol) of Et3N and 60 mg (0.35 mmol) of SiCl4 after 30
min. Yield: 168 mg (91%). Pale yellow microcrystalline
powder. M.p.: 76°C. C17H30Cl3O3PSi2W (659.78): calc.
1
C 30.95, H 4.85; found C 31.10, H 4.87. H-NMR (400
MHz, [D6]-benzene): l=1.65 [d, 4J(PWCCH)=0.5
2
Hz, 15 H, (H3C)5C5], 1.08 [d, J(PCH)=9.1 Hz, 9 H,
[6] S. Schmitzer, U. Weis, H. Ka¨b, W. Buchner, W. Malisch, T.
Polzer, U. Posset, W. Kiefer, Inorg. Chem. 32 (1993) 303.
[7] K[W(PPh3)(CO)2Cp] is prepared via K/benzophenone reduction
of Cp(OC)2(Ph3P)W–Cl according to the method described in:
T.A. George, R.A. Kovar, Inorg. Chem. 20 (1981) 285.
(H3C)3P), 0.93 ppm (s, 6 H, (H3C)2Si]. 31P-NMR (162
MHz, [D6]-benzene): l= −13.58 ppm [s, 1J(WP)=
277.0 Hz]. 13C-NMR (100.6 MHz, [D6]-benzene): l=
232.21 [d, 2J(PWC)=21.0 Hz, 1J(WC)=148.8 Hz,