Syntheses and reactivity of molybdenum complexes containing the diphenylphosphinodithioformato ligand

Article abstract of DOI:10.1016/S0022-328X(98)01039-0

Treatment of [Et₄N][Mo(CO)5(PPh₂)] (1) with CS₂ afforded [Et₄N][Mo(CO)₅(PPh₂CS₂)] (3) which was also synthesized from the reaction of Mo(CO)₅(CH₃CN) with [E

Full text of DOI:10.1016/S0022-328X(98)01039-0

Journal of Organometallic Chemistry 577 (1999) 134–139
Syntheses and reactivity of molybdenum complexes containing the
diphenylphosphinodithioformato ligand
Kuang-Hway Yih a, Ying-Chih Lin b,*
a Department of Applied Cosmetology, Hung Kuang Institute of Technology, Sahlu, Taichung, Taiwan 433, Taiwan, ROC
b Department of Chemistry, National Taiwan Uni6ersity, Taipei, Taiwan 106, Taiwan, ROC
Received 3 August 1998; received in revised form 12 October 1998
Abstract
Treatment of [Et4N][Mo(CO)5(PPh2)] (1) with CS2 afforded [Et4N][Mo(CO)5(PPh2CS2)] (3) which was also synthesized from the
reaction of Mo(CO)5(CH3CN) with [Et4N][PPh2CS2] (2). In complex 3, the diphenylphosphinodithioformato ligand, PPh2CS2−
,
coordinated to the molybdenum through the phosphorus atom. The reactions of 3 with various alkyl halides yielded the neutral
complexes Mo(CO)5[PPh2(CS2R)] (R=C2H5, C2H4OH, C3H5, 4–6). Acylation of 3 with 1-naphthoyl chloride [C10H7C(O)Cl]
gave the complex Mo(CO)5[PPh2(CS2COC10H7)] (7) with moderate yield. Alkylation and acylation reactions occurred at the sulfur
atom. Complex 3 reacted with CH2I2 to give the dinuclear complex [Mo(CO)5(PPh2CS2)]2(v-CH2) (8) in which the two metal
atoms are bridged by the bidentate phosphorus ligand. Decarbonylation of 3 in CH3CN produced an anionic product which was
identified as [Et4N][Mo(CO)4(PPh2CS2)] (9). The PPh2CS2− ligand of 9 bound to the metal center through both the phosphorus
and one of the sulfur atoms. All of the complexes are identified by spectroscopic methods. © 1999 Elsevier Science S.A. All rights
reserved.
Keywords: Diphenylphosphinodithioformato ligand; Molybdenum complex; Alkylation, acylation and decarbonylation reactions
intermolecular cyclization forming 6a-thiathiophthen
[3d]. In the context of our previous studies, we extended
1. Introduction
Although the dithiocarbamato ligands [1], R2NCS2−,
have attracted considerable attention, little effort has
been directed toward investigating the analogous di-
alkylphosphinodithioformato ligands, R2PCS2−. Until
now, only a few well-characterized Ph2PCS2− complexes
of early transition metals such as Zr [2] and W [3] were
reported, of which, this ligand coordinates to metal
centers through the two S atoms or the P and S atoms
by chelation, or the simple P-coordination. We were
interested in the Ph2PCS2− and Ph2PCS2R complexes of
W(0) which brought about some novel chemistry such
as unprecedented monodentate P-coordination mode
[3a], sulfur-assisted cyclization reaction [3b], phosphine
transfer reaction, CꢀS y-coordination in Pd [3c] and
the research to the syntheses and reactivity of molybde-
num complexes with the Ph2PCS2− ligand.
2. Experimental
2.1. Materials
All manipulations were performed under nitrogen
using vacuum-line, drybox, and standard Schlenk tech-
niques. NMR spectra were recorded on a Bruker AC-
200, or on
a
Bruker AM-300 WB FT-NMR
spectrometer and are reported in units of l with resid-
ual protons in the solvent as an internal standard
(CDCl3, l 7.24; CD3CN, l 1.93; C6D6, l 7.15;
C2D6CO, l 2.04). IR spectra were measured on a
* Corresponding author.
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01039-0

K.-H. Yih, Y.-C. Lin / Journal of Organometallic Chemistry 577 (1999) 134–139
135
Perkin–Elmer 983 instrument and were referenced to
polystyrene standard, using cells equipped with calcium
fluoride windows. Mass spectra were recorded on a Jeol
SX-102A spectrometer. Solvents were dried and deoxy-
genated by refluxing over the appropriate reagents be-
fore use. n-Hexane, diethyl ether, THF and benzene
were distilled from sodium-benzophenone. Acetonitrile
and dichloromethane were distilled from calcium hy-
dride, and methanol from magnesium. All other sol-
vents and reagents were of reagent grade and were used
as received. Mo(CO)6, allyl bromide and KPPh2 were
purchased from Strem, Merck and Aldrich, respec-
tively. CS2, n-BuLi, Et4NBr, C2H5I, IC2H4OH, C3H5Br
and CH2I2 were purchased from Janssen. The com-
pound [Et4N][PPh2(CS2)] [3e] and Mo(CO)5(PPh2H) [3f]
were prepared according to the literature method. Ele-
mental analyses were carried out at the Regional Center
of Analytical Instrument located at the National Tai-
wan University.
84%). Method B: to a THF solution of 1 (0.551 g, 1.0
mmol), CS2 (0.1 ml, 1.6 mmol) was added at room
temperature. The color changed from bright yellow to
red immediately accompanied with the formation of
some red precipitates. The solution was filtered and the
precipitates were washed with n-hexane (2×10 ml) to
give a red powder 3 (0.55 g) in 87% yield. Spectroscopic
data for 3: IR (KBr): wCO 2065(s), 1979(m), 1949(vs),
1909 (vs) cm−1
,
31P-NMR (CDCl3): l 69.8; H-NMR
(CDCl3): l 1.18 (tt, 12H, CH3, JN–H=1.87 Hz, JH–H
=
7.30 Hz), 3.15 (q, 8H, CH2, JH–H=7.30 Hz), 7.35 (m,
6H, Ph), 7.66 (m, 4H, Ph); 13C-NMR (CD3CN): 0 7.6
(s, CH3), 52.9 (s, CH2), 128.3 (d, meta-C of Ph, JP–C
=
9.8 Hz), 129.9 (s, para-C of Ph), 134.4 (d, ortho-C of
Ph, JP–C=9.8 Hz), 141.0 (d, ipso-C of Ph, JP–C=34.2
2
Hz), 204.8 (d, cis-CO, JP–C=7.5 Hz), 209.7 (d, trans-
CO, JP–C=25.5 Hz), 235.7 (s, CS2); MS (FAB, NBA):
m/z 759 (M+ +Et4N), 703 (M+ +Et4N–2CO); Anal.
Calc. for C26H30NO5PS2Mo (627.56) C: 49.76, H: 4.82,
N: 2.23. Found C: 49.74, H: 4.85, N: 2.22.
2.2. Preparation of [Et4N][Mo(CO)5(PPh2)] (1)
2.4. Preparation of Mo(CO)5[PPh2(CS2C2H5)] (4)
To a flask containing Mo(CO)5(PPh2H) (0.633 g, 1.5
mmol) and Et4NBr (0.315 g, 1.5 mmol) in THF, n-BuLi
(1 ml, 1.6 mmol) was added at 0°C. The solution was
stirred for 5 min and the solvent was removed under
vacuum. MeOH (15 ml) was added to the flask and the
solution was stored at −18°C for 12 h to give yellow
precipitates. These precipitates were filtered, washed
with diethyl ether (2×10 ml) and then dried under
vacuum to give 1 (0.77 g) as yellow powder in 93%
yield. Spectroscopic data for 1: IR (CH2CI2): wCO
C2H5I (0.01 ml, 1.0 mmol) was added to a solution of
3 (0.627 g, 1.0 mmol) in CH2Cl2 (20 ml) and the
mixture was stirred at room temperature for 1 min. The
solvent was removed under vacuum and the residue was
extracted with n-hexane (2×10 ml), and the extracts
were filtered through celite. The filtrate was concen-
trated to ca. 5 ml and cooled to −18°C for 12 h to give
the red crystalline product Mo(CO)5[PPh2(CS2C2H5)]
(4) (0.45 g, 85%). Spectroscopic data for 4: IR
1
2070(m), 1910(vs) cm−1; H-NMR (CDCl3): l 1.18 (tt,
(CH2Cl2): wCO 2074(m), 1940(vs) cm−1
;
31P-NMR
12H, CH3, JN–H=1.87 Hz, JH–H=7.30 Hz), 3.18 (q,
8H, CH2, JH–H=7.30 Hz), 7.47 (m, 6H, Ph), 7.67 (m,
4H, Ph); 13C-NMR (CD3CN): l 7.6 (s, CH3), 52.9 (s,
CH2), 128.2 (d, meta-C of Ph, JP–C=9.0 Hz), 131.5 (s,
para-C of Ph), 133.0(d, ortho-C of Ph, JP–C=9.7 Hz),
134.6 (d, ipso-C of Ph, JP–C=34.6 Hz), 205.7 (d,
cis-CO, JP–C=9.8 Hz), 210.0 (d, JP–C=25.8 Hz, trans-
CO); MS (FAB, NBA): m/z 681 (M+ +Et4N); Anal.
Calc. for C25H30NO5PMo (551.41) C: 54.45, H: 5.48, N:
2.54. Found C: 54.35, H: 5.42, N: 2.25.
(CDCl3): l 75.6; 1H-NMR (CDCl3): l 1.32 (t, 3H, CH3,
J
H–H=7.50 Hz), 3.29 (q, 2H, CH2 JH–H=7.50 Hz), 7
47 (m, 6H, Ph), 7.67 (m, 4H, Ph); 13C-NMR (CDCl3):
l 11.8 (s, CH3), 32.0 (s, CH2), 128.4 (d, meta-C of Ph,
3JP–C=9.6 Hz), 130.8 (s, para-C of Ph), 133.6 (d,
2
ortho-C of Ph, JP–C=12.4 Hz), 134.1 (d, ipso-C of Ph,
J
P–C=31.9 Hz), 205.4 (d, cis-CO, JP–C=8.3 Hz), 210.1
(d, trans-CO, JP–C=26.3 Hz), 238.9 (d, JP–C=4.8 Hz,
CS2); MS (FAB, NBA): m/z 528 (M+), 499 (M+
C2H5), 471 (M+ −C2H5−CO), 443 (M+ −C2H5−
−
2CO),
415
(M+ −C2H5−3CO),
387
2.3. Preparation of [Et4N][Mo(CO)5(PPh2CS2)] (3)
(M+ −C2H5−4CO), 359 (M+ −C2H5−5CO). Anal.
Calc. for C20H15O5PS2Mo (526.37) C: 45.63, H: 2.87.
Found C: 45.60, H: 2.85.
Method A:
a
CH2Cl2 solution (5 ml) of
Mo(CO)5(CH3CN) (0.277 g, 1.0 mmol) was added
slowly at room temperature to a CH2Cl2 solution (20
ml) of [Et4N][PPh2CS2] (2) (0.391 g, 1.0 mmol). The
solution was stirred for 1 h. The reaction was moni-
tored by 31P-NMR. After complete disappearance of
the 31P resonance of 2, dichloromethane was removed
under vacuum to give red–brown powder. The crude
product was recrystallized from a 1:1 CH2CI2/MeOH
solution to give a microcrystalline complex 3 (0.53 g,
2.5. Preparation of Mo(CO)5[PPh2(CS2C2H4OH)] (5)
The synthesis and work-up were similar to those used
in the preparation of complex 4. The pure complex
Mo(CO)5[PPh2(CS2C2H4OH)] (5) as the red microcrys-
talline solid was isolated in 90% yield. Spectroscopic
data for 5: IR (CH2CI2): nCO 2073(m), 1984(m),
1
1943(vs) cm−1
;
31P-NMR (CDCl3): l 77.4; H-NMR

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K.-H. Yih, Y.-C. Lin / Journal of Organometallic Chemistry 577 (1999) 134–139
(CDCl3): l 3.30 (t, 2H, SCH2, JH–H=6.12 Hz), 3.53 (t,
2H, CH2OH, JH–H=6.12 Hz), 7.46 (m, 6H, Ph), 7.64
(m, 4H, Ph); 13C-NMR (CDCl3): l 39.9 (s, SCH2), 59.8
(s, CH2OH), 128.5 (d, meta-C of Ph, JP–C=13.5 Hz),
131.1 (s, para-C of Ph), 133.8 (d, ortho-C of Ph,
the extract was filtered through celite. The filtrate was
concentrated to 5 ml and stored at −18°C for 12 h to
give
the
red–brown
crystalline
product
[Mo(CO)5(PPh2CS2)]2(m-CH2) (8) (0.41 g, 82%). Spec-
troscopic data for 8: IR (CH2Cl2): wCO 2074(m),
JP–C=17.3 Hz), 134.3 (d, ipso-C of Ph, JP–C=38.8
1985(m), 1945(vs) cm−1 31P-NMR (CDCl3): l 77.0;
;
Hz), 205.4 (d, cis-CO, JP–C=9.1 Hz); 239.7 (s, CS2);
MS (FAB, NBA): m/z 544 (M+), 516 (M+ −CO), 460
(M+ −3CO), 432 (M+ −4CO), 404 (M+ −5CO).
Anal. Calc. for C20H15O6PS2Mo (542.37) C: 44.29, H:
2.79. Found C: 44.25, H: 2.85.
1H-NMR (CDCl3): l 4.99 (s, 2H, CH2), 7.40–7.66 (m,
20H, Ph); 13C-NMR (CDCl3): l 42.4 (s, CH2), 128.5 (d,
meta-C of Ph, JP–C=8.3 Hz), 131.3 (s, para-C of Ph),
133.6 (d, ortho-C of Ph, JP–C=11.8 Hz), 134.3 (d,
ipso-C of Ph, JP–C=46.0 Hz), 205.2 (d, cis-CO, JP–C
=
6.5 Hz), 209.2 (d, trans-CO, JP–C=25.5 Hz), 237.6 (s,
CS2); MS (FBA, NBA): m/z 1010 (M+), 786 (M+
−8CO), 758 (M+ −9CO), 730 (M+ −10CO); Anal.
Calc. for C37H22O10P2S4Mo2 (1008 65) C: 44.06, H:
2.20. Found C: 44.00, H 2.27.
2.6. Preparation of Mo(CO)5[PPh2(CS2C3H5)] (6)
The synthesis and work-up were similar to those used
in the preparation of complex 4. The pure complex
Mo(CO)5[PPh2(CS2C3H5)] (6) as the red microcrys-
talline solid was isolated in 85% yield. Spectroscopic
2.9. Preparation of [Et4N][Mo(CO)4(PPh2CS2)] (9)
data for 6: IR (CH2CI2): wCO 2073(m), 1985(m),
1
1946(vs) cm−1
;
31P-NMR (CDCl3): l 76.0; H-NMR
Compound 3 (0.627 g, 1.0 mmol) was dissolved in 10
ml of CH3CN. The solution was stirred at room tem-
perature and the reaction monitored by IR spectra.
After stirring for 10 min, and IR spectrum indicated
that the starting material was completely consumed.
The solution was cooled and the solvent was removed
in vacuum. Recrystallization using a cold 1:1 n-hexane/
CH2CI2 to give the red crystalline product 9 (0.42 g,
70%). Spectroscopic data for 9: IR (CH2Cl2): wCO
(CDCl3): l 3.93 (d, 2H, SCH2, JH–H=6 99 Hz), 5.18,
5.28 (d, 2H, ꢀCH2, JH–H=9 99 Hz), 5.78 (m, 1H,
CHꢀ), 7.46 (m, 6H, Ph), 7.67 (m, 4H, Ph); 13C-NMR
(CDCl3): 0 41.5 (s, SCH2), 120.5 (s, CHꢀ), 128.5 (d,
meta-C of Ph, JP–C=9.8 Hz), 129.6 (s, =CH2), 130.8
(s, para-C of Ph), 133.7 (d, ortho-C of Ph, JP–C=12.4
Hz), 134.9 (d, ipso-C of Ph, JP–C=38.8 Hz), 205.4 (d,
cis-CO, JP–C=8.4 Hz), 210.0 (d, trans-CO, JP–C=25.5
Hz), 238.2 (s, CS2); MS (FAB, NBA): m/z 540 (M+),
512 (M+ −CO), 456 (M+ −3CO), 428 (M+ −4CO),
400 (M+ −SCO), 359 (M+ −5CO−C3H5). Anal.
Calc. for C21H15O5PS2Mo (538.38) C: 46.85, H: 2.81.
Found C: 46.82, H: 2.87.
2009(m), 1893(vs), 1865(sh), 1827(s) cm−1
;
31P-NMR
1
(CDCl3): l 38.9; H-NMR (CDCl3): l 1.18 (tt, 12H,
CH3, JN–H=1.87, JH–H=7.30 Hz), 3.15 (q, 8H,
NCH2, JH–H=7.30 Hz), 7.47 (m, 6H, Ph), 7.69 (m, 4H,
Ph); 13C-NMR (CDCl3): l 7.6 (s, CH3), 52.9 (s, NCH2),
129.0 (d, meta-C of Ph, JP–C=8.3 Hz), 130.9 (s, para-C
of Ph), 133.8 (d, ortho-C of Ph, JP–C=14.6 Hz), 136.5
(d, ipso-C of Ph, JP–C=21.8 Hz), 211.0, 212.2 (cis-
CO), 222.7 (d, trans-CO, JP–C=28.9 Hz), 238.1 (s,
CS2); MS (FAB, NBA): m/z 731 (M+ +Et4N), 703
(M+ +Et4N−CO); Anal. Calc. for C25H30NO4PS2Mo
(599.55) C: 50.08, H: 5.04, N: 2.34. Found C: 50.15, H:
5.20, N: 2.14.
2.7. Preparation of Mo(CO)5[PPh2(CS2OCC10H7)] (7)
The synthesis and work-up were similar to those used
in the preparation of complex 4. The pure complex
Mo(CO)5[PPh2(CS2OCC10H7)] (7) as the red microcrys-
talline solid was isolated in 46% yield. Complex 7 is air
and moisture sensitive and elemental analysis was not
obtained. Spectroscopic data for 7: IR (CH2Cl2): wCO
2073(m), 1976(m), 1943(vs), 1726(vs) cm−1 13P-NMR
;
(CDCl3): l 775; 1H-NMR (CDCl3): l 7.46–7.67 (m,
17H, Ph); 13C-NMR (CDCl3): l 128.5–134.9 (m, C of
Ph), 170.0 (s, SCO), 207.4 (d, cis-CO, JP–C=8.4 Hz),
211.0 (d, trans-CO, JP–C=25.5 Hz), 238.4 (s, CS2); MS
(FAB, NBA): m/z 654 (M+).
3. Results and discussion
3.1. Synthesis of the anionic complex
[Et4N][Mo(CO)5(PPh2CS2)] (3)
2.8. Preparation of [Mo(CO)5(PPh2CS2)]2(v-CH2) (8)
Abstraction of a proton from the metal coordinated
phosphine has been reported for the synthesis of the
phosphorus derivatives [4]. Interestingly, up to now,
only a few examples are known for dialkylphos-
phinodithioformato ligand, R2PCS2−. These R2PCS2−
ligands are probably air-sensitive and oxidized easily to
give R2P(X)CS2 (X=O, S).
CH2I2 (0.1 ml, 3.0 mmol) was added slowly to a
solution of 3 (0.627 g, 1.0 mmol) in 20 ml of CH2Cl2 at
room temperature and the solution was stirred for 5
min. The solvent was removed under vacuum and the
residue was extracted with n-hexane (2×10 ml), and

K.-H. Yih, Y.-C. Lin / Journal of Organometallic Chemistry 577 (1999) 134–139
137
Scheme 1.
Complex [Et4N][Mo(CO)5(PPh2)] (1) was produced in
high yield by the reaction of Mo(CO)5(HPPh2) with
n-BuLi in diethyl ether (−78°C) in the presence of
Et4NBr. The slightly air-sensitive yellow compound 1 is
soluble in CH2Cl2 and CH3CN and insoluble in n-hex-
ane and diethyl ether. The 13C-NMR of 1 reveals two
resonances at l 205.7 and 210.0 with a 4:1 ratio, which
are assigned to the carbon atoms of the cis and trans
carbonyl groups, respectively. Complex [Et4N][Mo-
(CO)5(PPh2CS2)] (3) can be obtained by two routes
(Scheme 1). Both treatment of 1 with CS2 and the
reaction of Mo(CO)5(CH3CN) with [Et4N][PPh2CS2] (2)
lead to the formation of 3 in 87 and 84% yield, respec-
tively. The red complex 3 is stable in solid-state and
undergoes decarbonylation reaction in solution (de-
scribed below). The analytical data of 3 are in agree-
ment with the formula. FAB mass spectrum of 3 shows
a base peak with a typical Mo isotope pattern corre-
sponding to the [M+ +Et4N] molecular mass. The IR
spectrum of 3 shows three terminal carbonyl stretchings
(2A1+E) that reveal a typical pattern for a LM(CO)5
unit with an octahedral geometry. Down-field shift of
the 31P resonance of 3 (l 69.8) relative to that of 1
indicates formation of the Ph2PCS2− ligand and transfer
of electron density from the phosphorus atom to the
CS2 portion. The 13C-NMR of 3 reveals three reso-
nances at l 204.8 (JP–C=7.5 Hz), 209.3 (JP–C=25.5
Hz) and 235.7 assignable to the carbon atoms of the cis
carbonyl groups and the trans carbonyl group and the
carbon disulfide, respectively.
Kunze, Ambrosius and co-workers [5] have synthe-
sized the anionic heteroallyl ligands containing phos-
phorus such as R2P(X)C(Y)NR− or R2PC(Y)NR−
(X=O or S, Y=O or S). Notably, all of these anionic
heteroallyl ligands bound to transition metals through
O and S [5a], N and S [5c,d], S and S [5e], P and S
[5b,d, f–i] and no mono-dentate phosphorus coordina-
tion has been observed. Obviously, 3 is formed via
abstraction of a proton by n-BuLi, followed by the
addition of the resulting phosphido unit onto the car-
bon atom of CS2. In 1987, Hey and co-workers re-
ported the insertion reaction of CS2 into a Zr–P [2]
bond, forming the dialkylphosphinodithioformato lig-
and, R2PCS2−. The bis(trimethylsily)phosphino zirco-
nium complex [Zr(h5-C5H5)2{h2-S2CP(SiMe3)2}Cl],
obtained from the reaction of [Zr(h5-C5H5)2(PR2)X]X
(R=SiMe3, X=Cl or Me) with CS2, contains a
R2PCS2− ligand chelating through the two sulfur atoms
of the CS2 moiety. No insertion of CS2 into the metal–
phosphine bond was observed for our tungsten- and
molybdenum complexes. Instead, the dithiocarbamato
ligand, R2NCS2− was synthesized by the insertion reac-

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K.-H. Yih, Y.-C. Lin / Journal of Organometallic Chemistry 577 (1999) 134–139
tion of CS2 into the M–N bond (M=Cr, Mo, W) [6b].
The fact that the formation of 3 was observed in two
different synthetic routes clearly indicates that 3 is a
thermodynamic product and the P-coordination seems
to be more favorable than the S-coordination for the
Ph2PCS2− ligand.
This alkylation reaction was extended for CH2I2 in
order to synthesize dinuclear complex. The reaction of
3 with excess CH2I2 in CH2Cl2 gave the dinuclear
complex [Mo(CO)5(PPh2CS2)]2(m-CH2) (8). The pro-
posed monomeric complex Mo(CO)5[PPh2(CS2CH2I)]
1
was not detected in the reaction. The H-NMR spec-
trum of 8 exhibits a resonance at l 4.99 assignable to the
CH2 group and the corresponding 13C-NMR signal is at
l 42.4. The 31P-NMR spectrum of 8 shows a resonance
at l 77.0. The FAB mass spectrum of 8 shows a base
peak at m/z 730 corresponding to [Mo(PPh2CS2)]2(m-
CH2), formed by loss of ten CO groups from 8 and this
phenomenon was also observed for the complex
[W(Co)5(PPh2CS2)]2(m-CH2) [3e]. On the basis of these
data, it is clear that the two metal centers are connected
by the (Ph2PCS2)2CH2 bridge.
3.2. Alkylation and acylation of
[Et4N][Mo(CO)5(PPh2CS2)] (3)
To explore the reactivity of complex 3, we carried out
the reactions of 3 with several alkyl halides and acyl
halide. The reaction of 3 with C2H5I in CH2Cl2 gave the
neutral complex Mo(CO)5[PPh2(CS2C2H5)] (4). This red
powder was isolated in 85% yield. Extraction with
n-hexane followed by removal of the solvent gave the
analytically pure product 4. Complex 4 is stable in
refluxing CH3CN or C6H6 under N2. The FAB mass
spectrum of 4 shows a base peak in agreement with the
3.3. Decarbonylation of [Et4N][Mo(CO)5(PPh2CS2)] (3)
1
[M+] ion fragment. The H-NMR spectrum of 4 ex-
When the CH3CN solution of 3 was stirred, decar-
bonylation occurred affording a stable compound which
can be formulated as [Et4N][Mo(CO)4(PPh2CS2)] (9)
based on its analytical and spectroscopic data (Scheme
1). The IR spectrum of 9 shows a pattern different from
that of M(CO)5L. The four IR absorptions at 2009,
1893, 1865, 1827 cm−1, are typical for a M(CO)4 [6] unit
with a pseudooctahedral geometry. The 31P-NMR spec-
trum of 9 shows a resonance at l 38.9. The significant
up-field shift of the 31P resonance of 9 relative to that of
3 (l 69.8) suggests a distinctively different chemical and
electronic environment for the R2PCS2− ligand which
supports its structure depicted in Scheme 1. Kunze and
Cotton have reported complexes with similar coordina-
tion via the P and S atoms in the hetero-allylic
Ph2PCSNR− ligands [5]. Notably, the decarbonylation
reaction of 3 occurred in acetonitrile instantly but very
slowly in dichloromethane. The phenomenon probably
caused by better donor ability of CH3CN than CH2Cl2.
The acylation and alkylation reaction of 3 can also be
carried out in CH2Cl2 and the alkylated products can be
obtained in higher yield.
hibits two resonances at l 1.32 and 3.29 with a 3:2 ratio
attributed to the ethyl protons and the corresponding
resonances in the 13C-NMR spectrum appear at l 11.8
and 32.0, respectively. The 31P-NMR spectrum of 4
shows a resonance at l 75.6, close to that of 3. On the
basis of these spectroscopic data, it is likely that the
alkylation takes place at one of the sulfur atom. This
result is consistent with that of the analogue complex
W(CO)5[PPh2(CS2Me)] [3c], which was structurally
confirmed by an X-ray diffraction analysis. The other
alkylated complexes Mo(CO)5[PPh2(CS2R)] (R=
C2H4OH, 5; C3H5; 6) have been prepared in a similar
way. In the mass spectra of 5 and 6, the molecular ion
along with the [M+ −CO] peak are detected. The
13C-NMR spectra of 5 and 6 both reveal singlet reso-
nances at l 39.9 and 59.9 for 5 and l 41.5, 120.5 and
129.6 for 6, which are assigned to the carbon atoms of
the SCH2CH2OH and SCH2CHꢀCH2 groups, respec-
tively. By comparing the spectroscopic data of the
alkylated molybdenum complexes with that of the cor-
responding alkylated tungsten complexes [3e], it is clear
that the organic segments have the same chemical envi-
ronment, namely, S-alkylation.
In the reaction of 3 with 1-naphthoyl chloride
[C10H7C(O)Cl], complex 7 was obtained. The lower
yield of this green complex relative to the higher yields
of the alkylation products may result from its air- and
moisture-sensitive character. The IR absorption of the
acyl group of 7 appears at 1726 cm−1 and the 13C-NMR
resonance at l 170.0. Interestingly, chemical shifts of the
31P resonances of all the alkylated and acylated com-
plexes all fall within the region of l 75–78, indicating
similar structure for all these complexes. Although the
differences are small, 31P chemical shift moves toward
down-field region as the group attached to the phos-
phine ligand becoming more electron-withdrawing.
4. Concluding remarks
This study describes the chemical behavior of the
anionic diphenylphosphinodithioformato Mo(0) com-
plex [Et4N][Mo(CO)5(PPh2CS2)] (3) toward alkylation,
acylation and decarbonylation reactions. By comparing
with our previous study of the W analogues, significant
differences between the Mo and W complexes in solubil-
ity, stability and nucleophilicity are observed. Notably,
the decarbonylation reaction is spontaneous for Mo but
requires heating for the W complex. The molybdenum
complexes with the Ph2PCS2− ligand are more soluble in
common organic solvents than the corresponding tung-

K.-H. Yih, Y.-C. Lin / Journal of Organometallic Chemistry 577 (1999) 134–139
139
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plexes are lower and with weaker nucleophilicity.
Acknowledgements
We thank the National Science Council of Taiwan,
ROC for support.
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