Molybdenum S-bonded mono-thiocarboxylate complexes CpMo(CO)3SCOR: Structure of CpMo(CO)3SCOPh

Article abstract of DOI:10.1016/j.poly.2006.06.021

Monothiocarboxylate complexes of molybdenum of the type CpMo(CO)₃SCOR [R = Me (1), CH₂Cl (2), Ph (3), 4-C₆H₄NO₂ (4), 3,5-C₆H₃(NO₂)₂ (5)] have been obtained

Full text of DOI:10.1016/j.poly.2006.06.021

Polyhedron 25 (2006) 3413–3416
www.elsevier.com/locate/poly
Molybdenum S-bonded mono-thiocarboxylate complexes
CpMo(CO)3SCOR: Structure of CpMo(CO)3SCOPh
a,
b
b
Mohammad El-khateeb *, Tobias Ruffer , Heinrich Lang
¨
a
Chemistry Department, Jordan University of Science and Technology, Irbid 22110, Jordan
Institut fu¨r Chemie, Technische Universita¨t Chemnitz, Strasse der Nationen 62, Chemnitz D-09107, Germany
b
Received 12 March 2006; accepted 13 June 2006
Available online 3 July 2006
Abstract
Monothiocarboxylate complexes of molybdenum of the type CpMo(CO)3SCOR [R = Me (1), CH2Cl (2), Ph (3), 4-C6H4NO2 (4),
3,5-C6H3(NO2)2 (5)] have been obtained by the reaction of the hydrosulfido complex, CpMo(CO)3SH, with acid chlorides. Complexes
1
1–5 have been characterized by IR and H-NMR spectroscopy, elemental analyses and by the single crystal X-ray diffraction of 3.
ꢀ 2006 Elsevier Ltd. All rights reserved.
Keywords: Molybdenum; Cyclopentadienyl; X-ray structure; Thiocarboxylate; Sulfur; Carbonyl
1. Introduction
Mo(CO)2(PPh3)2Br(SCOR) have been prepared from the
reaction of Mo(CO)2(PPh3)2Br2 with thiocarboxylate
anions [20].
Transition metal chalcogeno complexes have attracted
considerable attention due to their structural diversity
[1–6], relevance to catalysis [7–12] and biological applica-
tions as models for metalloenzymes [13–16]. An interesting
class of metal–chalcogeno complexes is that containing
thiocarboxylate ligands, which have been known for a long
time [17–29]. They have been prepared by two main routes:
the first one includes the substitution of an uninegative
labile ligand on the transition metal by thiocarboxylate
anions [20,21], while the second method is represented by
modifying a sulfur-containing metal complex featuring sul-
fides (S2xꢀ) or hydrosulfido (SHꢀ) ligands [17–19,26].
The first route has been applicable for a wide range of
metal–thiocarboxylate complexes. For example, the salts,
Ph4P[M(SCOPh)2] (M = Cu, Ag) and Et3HN[Ag(SCOPh)2]
were synthesized from the appropriate metal salts and the
benzoyl thiocarboxylate anion, PhCOSꢀ [16]. The palla-
dium thioacetate complexes P2Pd(SCOMe)2 (P = PPh3, 1/
2 dppf) were also made by the reaction of P2PdCl2 with
the thioacetate anion [17]. The Cp-free complexes
As far as the second route is concerned, the reaction of
the iron sulfides (l-Sx)[CpFe(CO)2]2 (x = 2, 3), with acid
chlorides has been reported to give the thiocarboxylate
complexes, CpFe(CO)2SCOR [22,23]. This chemistry was
also extended to include the Cp-substituted species Cp0Fe-
(CO)2SCOR (Cp0 = C5H4But, 1,3-C5H3(But)2; R = alkyl,
aryl) [24]. The photolytic reaction of these thiocarboxylate
complexes with EPh3 (E = P, As, Sb) produced the substi-
tuted complexes Cp0Fe(CO)(EPh3)SCOR [30]. An exten-
sion of this approach to include the reaction of the
ruthenium sulfide (l-S5)[CpRu(CO)2]2 with acid chlorides
to give the ruthenium thiocarboxylate complexes CpRu-
(CO)2SCOR has been reported [25]. However, the mixed
phosphine–carbonyl
ruthenium
complexes
CpRu-
(CO)(PPh3)SCOR were prepared from the reaction of
CpRu(CO)(PPh3)SH with acid chlorides at low tempera-
ture [26]. The later reaction was also applied successfully
to the preparation of CpRu(L)(L0)SCOR (L = L0 = PPh3,
1/2Ph2PCH2PPh2, 1/2Ph2PCH2CH2PPh2) [26].
The importance of Mo–thiocarboxylate complexes in
biochemistry [31,32] prompted us to extend our studies on
the synthesis and characterization of metal thiocarboxylate
*
Corresponding author. Tel.: +962 2 7201000; fax: +962 2 7095014.
E-mail address: kateeb@just.edu.jo (M. El-khateeb).
0277-5387/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.06.021

3414
M. El-khateeb et al. / Polyhedron 25 (2006) 3413–3416
complexes to include molybdenum. The reaction between
CpMo(CO)3SH and acid chlorides which gives the expected
thiocarboxylate complexes CpMo(CO)3SCOR is discussed
in this report.
2. Results and discussion
2.1. Synthesis and characterization
Treatment of the molybdenum hydrosulfido complex
CpMo(CO)3SH with acid chlorides gave the thiocarboxy-
late complexes CpMo(CO)3SCOR, 1–5 as shown in the fol-
lowing equation:
O
O
+
+
HCl
Mo
Mo
R
Cl
Fig. 1. ORTEP drawing of CpMo(CO)3SCOC6H5 (3).
SH
OC
OC
OC
S
R
CO
OC CO
1 - 5
R= Me (1), CH2Cl (2), Ph (3), 4-C6H4NO2 (4), 3,5-C6H3(NO2)2 (5)
and angles (ꢁ) of 3 are presented in Table 1. The crystal lat-
tice of 3 contains two crystallographically independent
molecules. The Cp-ring is bonded to the molybdenum
atom in a g5-fashion with Mo–C bond distances ranging
ð1Þ
The resulting dark-red thiocarboxylate complexes, 1–5,
˚
˚
from 2.295(4) A to 2.355(4) A. The Mo–S bond distance
are air stable as solids. In solution, these complexes are
quite unstable and they decompose to brown insoluble
materials. In some experiments small amounts of the chlo-
ride complex CpMo(CO)3Cl were also obtained. Com-
2
˚
2.5191(10) A is similar to that reported for Mo(j C,S-
i
˚
SCOPr )(jS-SCOMe)(CO)2(PMe3)2, 2.511(4) A [28]. The
Mo–CCO bond distances (average of 1.986 A) are in agree-
˚
ment with those found in CpMo(CO)3-containing com-
1
plexes 1–5 have been fully characterized by IR, H NMR
plexes. The C@O bond distance of the thiocarboxylate
spectra, elemental analysis and by the single crystal X-ray
structure determination of 3. The IR spectra of 1–5 display
three absorption bands in the range of 2048–2042, 1980–
1971, and 1936–1942 cmꢀ1, respectively, for the terminal
carbonyl ligands. These bands are lower than those
observed for CpMo(CO)3SH (2039, 1963 cmꢀ1) [33,34],
but similar to those observed for CpMo(CO)3S2CSR
(2050–2046, 1976, and 1951–1952 cmꢀ1) [35]. An addi-
tional distinctive absorption appears between 1644 and
1736 cmꢀ1, corresponding to the ketonic carbonyl group
of the thiocarboxylate ligand. This value is higher than
those observed for the analogous iron thiocarboxylates
CpFe(CO)2SCOR (1590–1630 cmꢀ1), suggesting less elec-
tron density around the Mo center compared to that of Fe.
˚
ligand of 1.214(5) A is similar to that reported for Mo-
(j2C,S-SCOPri)(jS-SCOMe)(CO)2(PMe3)2 of 1.19(2) A
˚
[28] and to that found in other complexes containing thio-
carboxylate groups [22,26].
Table 1
˚
Selected bond lengths (A) and angles (ꢁ) of CpMo(CO)3SCOC6H5 (3)
Mo1–S1
2.5191(10)
2.355(4)
2.345(4)
2.304(4)
2.295(4)
2.312(4)
1.973(5)
1.989(4)
1.995(4)
1.753(3)
1.214(5)
1.153(5)
1.143(5)
1.128(5)
76.71(17)
77.96(17)
111.39(18)
133.10(14)
76.57(12)
76.93(11)
107.45(12)
123.8(3)
Mo1–C1
Mo1–C2
Mo1–C3
Mo1–C4
Mo1–C5
Mo1–C6
Mo1–C7
Mo1–C8
S1–C9
C9–O4
C6–O1
C7–O2
C8–O3
C6–Mo1–C7
C7–Mo1–C8
C6–Mo1–C8
C6–Mo1–S1
C7–Mo1–S1
C8–Mo1–S1
Mo1–S1–C9
O4–C9–S1
1
The H NMR spectra of 1–5 show the expected signals
of the Cp protons in the range 5.55–5.66 ppm. These reso-
nances are found at lower field than the peak for CpMo-
(CO)3SH (4.55 ppm) and CpMo(CO)3(S2CSR) (4.32 ppm),
suggesting that the thiocarboxylate group is a stronger
p-acceptor (or weaker r-donor) ligand compared to the thi-
oxanthate unit [35]. The peaks for the R-group of the thio-
carboxylate ligands are shown in the expected ranges with
the expected multiplicities.
2.2. Crystal structure
The molecular structure of 3 with the atom numbering
scheme is shown in Fig. 1. Selected bond distances (A)
˚

M. El-khateeb et al. / Polyhedron 25 (2006) 3413–3416
3415
3. Experimental
8.30 (m, 2H, C6H5). Anal. Calc. for C15H10MoO4S: C,
47.13; H, 2.64; S, 8.39. Found: C, 46.83; H, 2.28; S, 7.98%.
3.1. General
3.2.4. CpMo(CO)3SCO-4-C6H4NO2 (4)
Yield: 87%. M.p.: 134–135 ꢁC. IR (CH2Cl2, cmꢀ1): 2045
Synthetic work was carried out under a dinitrogen
atmosphere using Schlenk techniques. Tetrahydrofuran,
diethyl ether, hexane, and dichloromethane were dried, dis-
tilled and stored under nitrogen. The reagent CpMo(CO)3SH
was prepared as described previously [34,35]. Acid chlo-
rides, molybdenum hexacarbonyl and sulfur were obtained
commercially and were used as received.
1
(s), 1977 (s), 1942 (s) (m(C„O)), 1707 (m) (m(C@O)). H-
NMR (CDCl3): 5.64 (s, 5H, C5H5), 8.32 (2d, 4H,
C6H4NO2, Jo = 9.1 Hz). Anal. Calc. for C15H9MoNO6S:
C, 42.17; H, 2.12; N, 3.29; S, 7.50. Found: C, 41.86; H,
1.87; N, 2.95; S, 7.02%.
Nuclear magnetic resonance (NMR) spectra were
obtained on a Bruker spectrometer operating at 200 MHz
with chemical shifts reported in ppm downfield from
TMS, using the solvent residual peak as an internal refer-
ence. Infrared (IR) spectra were recorded on a Nicolet-
Impact 410 FT-IR spectrometer in CH2Cl2 solutions.
Elemental analyses were done at Laboratoire D’Analyse
3.2.5. CpMo(CO)3SCO-4-C6H3(NO2)2 (5)
Yield: 87%. M.p.: 162–163 ꢁC. IR (CH2Cl2, cmꢀ1): 2046
1
(s), 1977 (s), 1941 (s) (m(C„O)), 1710 (m) (m(C@O)). H-
NMR (CDCl3): 5.66 (s, 5H, C5H5), 8.33 (d, 2H,
C6H3(NO2)2, Jm = 3.1 Hz), 8.67 (t, 1H, C6H3(NO2)2,
Jm = 3.1 Hz). Anal. Calc. for C15H9MoN2O8S: C, 38.23;
H, 1.50; N, 5.94; S, 6.80. Found: C, 37.75; H, 1.37; N,
5.45; S, 6.38%.
´
´
´
´
Elementaire, Universite de Montreal, Montreal, Quebec,
Canada. Melting points were reported on a Staurt Melting
point apparatus (SMP3) and are uncorrected.
3.3. X-ray structure analysis
3.2. General procedure for the preparation of
CpMo(CO)3SCOR, 1–5
X-ray data of a dark red crystal of CpMo(CO)3SCOPh
(3) were collected with an Oxford Gemini S diffractomer
˚
with a graphite monochromator k(Mo Ka) = 0.71073 A.
A diethyl ether solution of CpMo(CO)3SH (0.28 g,
1.00 mmol) was cooled to ꢀ78 ꢁC. The respective acid chlo-
ride (1.10 mmol) was added as one portion. The cooling
bath was removed and the solution was stirred for 2 h at
room temperature. The volatiles were removed under vac-
uum and the resulting solid was redissolved in a minimum
amount of dichloromethane and introduced onto a silica
gel column made up with hexane. Elution with hexane
removes the excess acid chlorides and with a 1:1 v:v ratio
of diethyl ether:hexane gives an orange band. This band
was collected and the volatiles were removed under vac-
uum. The resulting red solid was recrystallized from dichlo-
romethane/hexane at 0 ꢁC.
The crystallographic data are presented in Table 2. The
structure was solved by direct methods using SHELXS-97
[36] and refined by full-matrix least-square procedures on
Table 2
Selected crystal data and refinement parameters for CpMo(CO)3
SCOC6H5 (3)
Empirical formula
Formula weight
Crystal size (mm)
Crystal system
Space group
Unit cell dimension
C15H10MoO4S
382.23
0.3 · 0.3 · 0.2
Orthorhombic
Pca2(1)
˚
a (A)
33.833 (3)
7.6070 (5)
11.7042 (9)
90
90
90
˚
b (A)
3.2.1. CpMo(CO)3SCOMe (1)
Yield: 70%. M.p.: 193–194 ꢁC. IR (CH2Cl2, cmꢀ1): 2044
˚
c (A)
1
a (ꢁ)
b (ꢁ)
c (ꢁ)
(s), 1971 (s), 1936 (s) (m(C„O)), 1644 (m) (m(C@O)). H-
NMR (CDCl3): d 2.49 (s, 3H, CH3), 5.55 (s, 5H, C5H5).
Anal. Calc. for C10H8MoO4S: C, 37.51; H, 2.52; S, 10.01.
Found: C, 37.08; H, 2.32; S, 9.74%.
3
˚
V (A )
3012.3 (4)
8
Z
Index ranges
ꢀ40 6 h 6 40
ꢀ9 6 k 6 9
ꢀ13 6 l 6 14
19510/5385 [0.0321]
5385/1/379
1.062
3.2.2. CpMo(CO)3SCOCH2Cl (2)
Yield: 75%. M.p.: 150–151 ꢁC. IR (CH2Cl2, cmꢀ1): 2048
(s), 1980 (s), 1957 (m(C„O)), 1736 (m) (m(C@O)). 1H-NMR
(CDCl3): d 4.15 (s, 2H, CH2Cl), 5.59 (s, 5H, C5H5). Anal.
Calc. for C10H7ClMoO4S: C, 33.87; H, 1.99; S, 9.04.
Found: C, 33.17; H, 1.89; S, 8.33%.
Refections collected/unique [Rint
Data/restrains/parameters
GooF
]
Dcalc (Mg mꢀ3
l (mmꢀ1
)
1.686
1.020
)
h Range (ꢁ)
R[F2 > 2r(F2)]
xR(F2)a
2.94–25.20
0.0279
0.0501
3.2.3. CpMo(CO)3SCOPh (3)
Yield: 65%. M.p.: 108–110 ꢁC. IR (CH2Cl2, cmꢀ1): 2042
Flack x parameterb
0.02(3)
1
2
a
x ¼ 1=½r2ðF o2Þ þ ð0:0186PÞ þ 1:5711Pꢁ where P ¼ ðF o2 þ 2F 2cÞ=3.
(s), 1976 (s), 1941 (s) (m(C„O)), 1685 (m) (m(C@O)). H-
b
H.D. Flack, Acta Crystallogr., Sect. A (39) (1983) 876.
NMR (CDCl3): 5.63 (s, 5H, C5H5), 7.40 (m, 3H, C6H5),

3416
M. El-khateeb et al. / Polyhedron 25 (2006) 3413–3416
F2, using SHELXTL-97 [37]. All non-hydrogen atoms are
refined anisotropically and the hydrogen atom positions
have been refined using the riding model. The absolute
structure was determined by the refinement of the Flack
x parameter. The asymmetric unit comprises two indepen-
dent molecules.
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The authors thank the Deanship of Research, Jordan
University of Science and Technology and Shoman Foun-
dation for financial support.
Appendix A. Supplementary data
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic Data
Centre, CCDC No. 600973 for compound 3. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK (fax: +44 1233 336 033; e-mail: deposit@ccdc.cam.ac.uk
or www: http://www.ccdc.cam.ac.uk). Supplementary data
associated with this article can be found, in the online ver-
sion, at doi:10.1016/j.poly.2006.06.021.
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