Transformations of organoarsine-oxides and -sulfides on di- and tri-cobalt carbonyl centres

Article abstract of DOI:10.1016/S0022-328X(03)00584-9

Conversion of [Co₃(μ₃-CR′) {μ-(AsMe₂)₂O}(CO)₇] [R′=Cl, Me] and [Co₂{μ-C₂(CO₂Me)₂} {μ-(AsMe₂)₂O}(CO)₄] to the corresponding bis-dimethylarsinesulfide-bridged complexes [Co₃ (μ₃-CR′){μ-(AsMe₂)₂S} (CO)₇] [R′=Cl (1a), Me (1b)] and [Co₂ {μ-C₂(CO₂Me)₂}{μ-(AsMe ₂)₂S}(CO)₄] (2) can be achieved on their treatment with H₂S (with the elimination of H₂O); this process is reversible. The related bis-diphenylarsinesulfide-bridged complexes, [Co₃(μ₃-CR′){μ-(AsPh ₂)₂S}(CO)₇] [R′=Cl (3a), Me (3b)] and [Co₂(R′CCR′′){μ-(AsPh₂) ₂S}(CO)₄] [R′=R′′=CO₂ Me (4a), Ph (4b)] can be obtained in moderate yield by the direct reaction of (Ph₂As)₂S with [Co₃ (μ₃-CR′)(CO)₉] [R′=Cl, Me] and [Co₂(R′CCR′′)(CO)₆] [R′=R′′=CO₂Me, Ph], respectively. The triphenylarsine mono-substituted complex [Co₂ {μ-C₂(CO₂Me)₂}(CO)₅ (AsPh₃)] (5) is also isolated as a product in the reaction leading to 4a. Thermolysis of 3a yields [Co₃ (μ₃-S){μ-(AsPh₂)₂O} {μ-(AsPh₂S)}(CO)₇] (6) in low yield while the related thioxo-capped complexes [Co₃ (μ₃-S){μ-(AsMe₂)₂X} (μ-AsMe₂S)(CO)₅] [X=S (7), O (8)] can be obtained in higher yield by thermolysis of [Co₃(μ-CMe) {μ-(AsMe₂)₂O}(CO)₇] in the presence of H₂S. Single crystal X-ray diffraction studies have been performed on 2, 4a, 4b and 8.

Full text of DOI:10.1016/S0022-328X(03)00584-9

Journal of Organometallic Chemistry 681 (2003) 102ꢁ114
/
www.elsevier.com/locate/jorganchem
Transformations of organoarsine-oxides and -sulfides on di- and tri-
cobalt carbonyl centres
Jason D. King a, Martin J. Mays a,*, Mary McPartlin b, Gregory A. Solan c,
Caroline L. Stone a
a Department of Chemistry, Lensfield Road, Cambridge CB2 1EW, UK
b School of Applied Chemistry, University of North London, Holloway Road, London N7 8DB, UK
c Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH, UK
Received 22 April 2003; received in revised form 30 May 2003; accepted 30 May 2003
Abstract
Conversion of [Co3(m3-CR?){m-(AsMe2)2O}(CO)7] [R?ꢀ
corresponding bis-dimethylarsinesulfide-bridged complexes [Co3(m3-CR?){m-(AsMe2)2S}(CO)7] [R?ꢀ
[Co2{m-C2(CO2Me)2}{m-(AsMe2)2S}(CO)4] (2) can be achieved on their treatment with H2S (with the elimination of H2O); this
process is reversible. The related bis-diphenylarsinesulfide-bridged complexes, [Co3(m3-CR?){m-(AsPh2)2S}(CO)7] [R?ꢀCl (3a), Me
(3b)] and [Co2(R?CCR??){m-(AsPh2)2S}(CO)4] [R?ꢀR??ꢀCO2Me (4a), Ph (4b)] can be obtained in moderate yield by the direct
reaction of (Ph2As)2S with [Co3(m3-CR?)(CO)9] [R?ꢀCl, Me] and [Co2(R?CCR??)(CO)6] [R?ꢀR??ꢀCO2Me, Ph], respectively. The
/
Cl, Me] and [Co2{m-C2(CO2Me)2}{m-(AsMe2)2O}(CO)4] to the
/
Cl (1a), Me (1b)] and
/
/
/
/
/
/
triphenylarsine mono-substituted complex [Co2{m-C2(CO2Me)2}(CO)5(AsPh3)] (5) is also isolated as a product in the reaction
leading to 4a. Thermolysis of 3a yields [Co3(m3-S){m-(AsPh2)2O}{m-(AsPh2S)}(CO)7] (6) in low yield while the related thioxo-capped
complexes [Co3(m3-S){m-(AsMe2)2X}(m-AsMe2S)(CO)5] [XꢀS (7), O (8)] can be obtained in higher yield by thermolysis of [Co3(m-
/
CMe){m-(AsMe2)2O}(CO)7] in the presence of H2S. Single crystal X-ray diffraction studies have been performed on 2, 4a, 4b and 8.
# 2003 Elsevier B.V. All rights reserved.
Keywords: Cobalt; Bis-diarsinesulfide; Bis-diarsineoxide; Hydrogen sulfide; Alkylidyne; Alkyne
1. Introduction
The free bis-dialkylarsine- and bis-diarylarsine-sulfide
ligands themselves are readily accessible and have been
prepared by a number of routes [6,7] including a
metathesis approach in which the corresponding bis-
diarsineoxide can be converted directly with hydrogen
sulfide [8]. Interestingly, a related approach using
coordinated bis-diarsineoxide ligands has, however, to
the knowledge of the authors, not been reported.
While phosphorus(III) ligands of the type (R2P)2X
(Rꢀ
/
hydrocarbyl; XꢀS, O) are well documented in
/
transition metal chemistry [1,2], the related arsenic(III)
ligands (R2As)2O and, in particular (R2As)2S, have
received considerably less attention [3ꢁ5]. Indeed, only
/
a handful of complexes have been characterised crystal-
lographically to date that contains bis-diarsinesulfide
ligands [4a,5]. Nonetheless, the flexibility of this ligand
family has been demonstrated in its ability to adopt
monodentate, bidentate-chelating and bidentate-brid-
ging bonding modes.
In this paper, we describe a study conducted to
determine whether the coordinated (R2As)2O (RꢀMe,
/
Ph) ligand in a series of di- and tri-cobalt organometallic
complexes would react in the same way as the free
ligand, thereby generating a coordinated (R2As)2S
ligand. In addition, the synthesis of a series of
(R2As)2S-bridged cobalt complexes by direct reaction
of (R2As)2S with alkyne-dicobalt hexacarbonyl or
alkylidyne-tricobalt non-acarbonyl, along with an ex-
* Corresponding author. Tel.: ꢂ
336017.
E-mail address: mjm14@cam.ac.uk (M.J. Mays).
/
44-1223-336343; fax: ꢂ44-1223-
/
amination of the arsenicꢁ/sulfur bond lability in these
complexes, are reported.
0022-328X/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00584-9

J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ
/114
103
2. Results and discussion
further supported by the 13C-NMR spectra of 1a and
1b in which the corresponding methyl resonances are
seen at d 23.4 ppm and d 18.2 ppm (1a) and at d 21.6
ppm and d 19.6 ppm (1b). In contrast, only one signal
2.1. Metathesis of oxygen for sulfur in [Co3(m3-CR?){m-
(Me2As)2O}(CO)7] and [Co2{m-C2(CO2Me)2}{m-
(Me2As)2O}(CO)4]
1
for 2 is seen in both the H-and 13C-NMR spectra for
the methyl groups of the (Me2As)2S ligands. This is in
agreement with the corresponding data for the com-
plexes [Co2{C2(CO2Me)2}{m-(Me2As)O}(CO)4] [3a] and
[Co2{C2(CO2Me)2}(m-P2Ph4)(CO)4] [9] and has been
attributed to a fluxional process operating in solution.
It is likely that a similar process is occurring for 2.
Purging a benzene solution of [Co3(m3-CR?){m-
(Me2As)2O}(CO)7] [R?ꢀCl or Me] with H2S at ambient
/
temperature gave [Co3(m3-CR?){m-(Me2As)2S}(CO)7]
[R?ꢀCl (1a), Me (1b)] in good yield (ca. 48%; Scheme
/
1). Similarly, [Co2{m-C2(CO2Me)2}{m-(Me2As)2S}-
(CO)4] (2) can be obtained in good yield (56%) on
treatment of [Co2{m-C2(CO2Me)2}{m-(Me2As)2O}-
(CO)4] with H2S at room temperature. All the products
have been characterised by IR, 1H- and 13C-NMR
spectroscopy, mass spectrometry and microanalysis
(see Table 1). In addition, complex 2 has been the
subject of an X-ray diffraction study (Fig. 1); the
structure will be discussed later.
2.2. Reaction of [Co2(m-R?CCR??)(CO)6] and [Co3(m3-
CR?)(CO)9] with (Ph2As)2S
The reaction of [Co3(m3-CR?)(CO)9] (R?ꢀ
with (Ph2As)2S in toluene at 35 8C afforded greenish-
black [Co3(m3-CR?){m-(Ph2As)2S}(CO)7] [R?ꢀCl (3a),
Me (3b)] as the sole product in moderate to good yield
(54ꢁ65%). Conversely, treatment of [Co2(m-
R?CCR??)(CO)6] [R?ꢀR??ꢀCO2Me, Ph] with a three-
fold excess of (Ph2As)2S in toluene at 35ꢁ40 8C gave
[Co2(R?CCR??){m-(Ph2As)2S}(CO)4] [R?ꢀR??ꢀCO2Me
/Cl, Me)
/
/
The mass spectra of 1a, 1b and 2 show molecular ion
peaks consistent with the proposed formulae together
with peaks corresponding to the successive loss of up to
seven carbonyl groups for 1a and 1b and four carbonyl
groups for 2. For all three complexes, the molecular ion
peak occurs sixteen mass units higher than for the
corresponding dimethylarsineoxide complexes. In the IR
spectra for 1a, 1b and 2 a similar pattern of peaks is
observed to the (Me2As)2O analogues, [Co3(m3-CR?){m-
/
/
/
/
/
(4a), Ph (4b)] and [Co2{m-C2(CO2Me)2}(CO)5(AsPh3)]
(5) in moderate yield (32%) (Scheme 2). All the
complexes have been characterised by IR spectroscopy,
mass spectrometry, 1H- and 13C-NMR spectra and
microanalysis (see Table 1). In addition, complexes 4a
and 4b have been the subjects of single crystal X-ray
diffraction studies.
Complexes 3a and 3b show molecular ions peaks
along with peaks corresponding to the fragmentation
from the molecular ions of up to seven carbonyl groups.
In addition, the IR data for 3a and 3b display a similar
pattern of bands as compared to the corresponding bis-
diphenylarsineoxide-bridged complexes [3a].
The molecular structures of 4a and 4b along with the
structurally related 2 are shown in Figs. 2, 3 and 1,
respectively. They are similar and will be discussed
together; selected bond lengths and angles for all the
structures are presented in Table 2. Complex 4b crystal-
lises with two molecules in the asymmetric unit. Slight
differences in molecular geometry are apparent but none
is of great significance. Averaged values for bond
lengths and angles in both molecules are quoted for 4b
throughout the following discussion.
(Ph2As)2O}(CO)7] (R?ꢀCl, Me) and [Co2{C2(CO2-
/
Me)2}{m-(Me2As)O}(CO)4] [3a].
Two equal-intensity resonances, attributable to meth-
yl groups of the bridging (Me2As)2S ligand are observed
in the 1H-NMR spectra of both 1a and 1b, appearing at
d 1.87 ppm and d 1.80 ppm (1a) and at d 1.82 ppm and
d 1.76 ppm (1b). Each resonance integrates to six
protons, which indicates that two distinct methyl
environments are present in each complex. This is
In common with the unsubstituted parent complexes,
2, 4a and 4b have a Co2C2 tetrahedral core, derived from
a Co2(CO)4 unit and a bridging alkyne ligand (DMAD
in 2 and 4a, diphenylacetylene in 4b), which is coordi-
nated in the ‘side-on’ mode. In each complex, an
(R2As)2S [Rꢀ
/
Me (2); RꢀPh (4a and 4b)] ligand acts
/
as a bridging bidentate donor. Of the two carbonyl
ligands remaining on each cobalt atom, one is located
equatorially and the other occupies the axial position.
The (R2As)2S ligand coordinates to each cobalt atom at
Scheme 1. Reagents and conditions: (i) H2S, room temperature,
C6H5CH3; (ii) room temperature, C6H5CH3.

Table 1
Spectroscopic and analytical data for the new complexes 1ꢁ8
/
a
Compound n(CO) (cmꢃ1
)
1H-NMR, d (ppm) b
13C-NMR, d (ppm) c
FAB mass spectrum Microanalysis
(%) d
C
H
1a
1b
2
2072s, 2023vs, 2005w, 1992m, 1982m, 1.87 (s, 6H, Me), 1.80 (s, 6H, Me)
1968w
202.4 (s, CO), 23.4 (s, Me), 18.2 (s, Me)
662 [Mꢂ, Mꢂ Ã
CO] (nꢀ1ꢁ7)
642 [Mꢂ, Mꢂ Ã
CO] (nꢀ1ꢁ7)
Me) 200.9 (s, CO), 172.3 (s, CO2Me), 52.6 (s, CO2Me), 614 [Mꢂ, Mꢂ Ã
21.3 (s, AsÃMe) CO] (nꢀ1ꢁ4)
203.0 (s, CO), 145ꢁ
910 [Mꢂ, Mꢂ Ã
CO] (nꢀ1ꢁ7)
890 [Mꢂ, Mꢂ Ã
CO] (nꢀ1ꢁ7)
862 [Mꢂ, Mꢂ Ã
CO] (nꢀ1ꢁ4)
898 [Mꢂ, Mꢂ Ã
CO] (nꢀ1, 2, 4)
705 [Mꢂ, Mꢂ Ã
n-
CO] (nꢀ1ꢁ5)
/
n-
n-
n-
n-
n-
n-
n-
21.61
(21.76)
24.01
1.75
(1.83)
2.27
/
/
2065s, 2056w, 2050w, 2010vs, 1989m, 3.30 (s, 3H, CÃ
1981w, 1970w, 1957w, 1865w, 1837w 1.76 (s, 6H, AsÃ
/
Me), 1.82 (s, 6H, AsÃ
Me)
3.80 (s, 6H, CO2Me), 1.91 (s, 12H, AsÃ
/
Me),
208.1 (s, CO), 44.6 (s, CÃ
19.6 (s, AsÃMe)
/
Me), 21.6 (s, AsÃ
/Me),
/
/
/
/
/
(24.32)
27.47
(2.36)
2.91
2049m, 2023vs, 1196s
2071s, 2021s, 1979w
2052s, 2010s, 1978w
/
/
/
/
/
(27.38)
42.76
(2.95)
2.18
3a
3b
4a
4b
5
8.1ꢁ
/
6.6 (m, 20H, Ph)
/129 (Ph)
/
/
/
(42.21)
(2.21)
ꢁ/
ꢁ/
/
ꢁ/
ꢁ/
/
/
2085m, 2052m, 2028s, 2002m, 1707w 7.8ꢁ
/
7.2 (m, 20H, Ph), 3.61 (s, 6H, Me)
6.2 (m, 30H, Ph)
200.8 (s, CO), 171.7 (s, CO2Me), 142ꢁ
52.4 (s, CO2Me)
203 (s, CO), 142ꢁ
/129 (Ph),
/
49.18
(49.32)
56.16
2.95
(3.00)
3.31
/
/
2030m, 2003s, 1976m
7.9ꢁ
/
/
127 (Ph)
/
/
(56.15)
47.01
(3.37)
2.97
2089s, 2043sh, 1997w, 1706w
7.7ꢁ
/
7.3 (m, 15H, Ph), 3.60 (s, 6H, Me)
202.2 (s, CO), 198.0 (s, CO), 173.0 (s, CO2Me),
141ꢁ129 (Ph), 74.0 (s, C ÃCO2Me), 53.2 (s,
CO2Me)
146ꢁ128 (Ph)
/
/
/
/
/
(47.36)
(3.04)
6
7
8
2044s, 2003vs
7.9ꢁ
/
6.5 (m, 30H, Ph)
/
1084 [Mꢂ, Mꢂ Ã
CO] (nꢀ1ꢁ5)
728 [Mꢂ, Mꢂ Ã
CO] (nꢀ1ꢁ5)
712 [Mꢂ, Mꢂ Ã
CO] (nꢀ1ꢁ5)
/
n- 45.66
(45.41)
3.04
(2.79)
2.46
/
/
2038m, 1994m, 1733s
2083m, 1993s, 1732w
1.97 (s, 3H, Me),1.93 (s, 3H, Me), 1.75 (s, 3H, 24.9 (s, Me), 24.4 (s, Me), 22.2 (s, Me), 20.8 (s,
Me), 1.70 (s, 6H, Me), 1.58 (s, 3H, Me)
1.90 (s, 3H, Me), 1.81 (s, 3H, Me), 1.70 (s,
/
n-
n-
18.45
(18.15)
18.83
Me), 20.4 (s, Me), 19.5 (s, Me)
25.7 (s, Me), 24.9 (s, Me), 24.0 (s, Me), 23.0 (s,
/
/
(2.49)
2.57
/
6H, Me), 1.62 (s, 3H, Me), 1.60 (s, 3H, Me) Me), 22.4 (s, Me), 20.2 (s, Me)
/
/
(18.56)
(2.55)
a
b
c
Recorded in dichloromethane solution.
1H-NMR chemical shifts (d) in ppm relative to SiMe4 (0.0 ppm), coupling constants in Hz in CDCl3 at 293 K.
Chemical shifts in ppm relative to SiMe4 (0.0), in CDCl3 at 293 K.
Calculated values in parentheses.
d

J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ
/114
105
Fig. 1. Molecular structure of [Co2{m-C2(CO2Me)2}{m-(Me2As)2S}(CO)4] (2) including the atom numbering scheme. The hydrogen atoms have been
omitted for clarity.
Scheme 2. Reagents and conditions: (i) (Ph2As)2S, 35 8C, C6H5CH3.

106
J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ114
/
Fig. 2. Molecular structure of [Co2{m-C2(CO2Me)2}{m-(Ph2As)2S}(CO)4] (4a) including the atom numbering scheme. The hydrogen atoms have been
omitted for clarity.
the remaining equatorial site. In 2, the bridging AsÃ
As ligand and the bridged dicobalt edge form a
symmetric pentagonal ring with the CoÃAs bonds
[2.326(1) A and 2.327(1) A] and the AsÃS bonds
[2.227(2) A and 2.231(2) A] in each case being of equal
length. The molecule has an approximate plane of
/
SÃ
/
[Co2(m-PhCCH){m-(Ph2As)2O}(CO)4] [118.4(2)8] and
that the AsÃSÃAs angle in 2 [100.49(7)8] is smaller
than the AsÃOÃAs angle in [Co2{m-C2(CO2Me)2}{m-
/
/
/
/
/
˚
˚
/
(Me2As)2O}(CO)4] [117.7(3)8]. This effect would be
˚
˚
expected to bring the arsenic atoms closer together in
complexes 2 and 4 if it were not for the fact that the AsÃ
O bonds in complexes such
[Co2(m-PhCCH){m-(Ph2As)2O}(CO)4] [meanꢀ
/
symmetry passing though the midpoint of the metalꢁ
/
S bonds are longer than AsÃ
/
metal bond and containing both the acetylenic bond and
as
/
˚
the sulfur atom. Twisting of the alkyne does, however,
1.799(3)
A]
or
[Co2{m-C2(CO2Me)2}{m-(Me2A-
˚
1.803(5) A]. This actually results
mean that it is not perfectly perpendicular to the CoÃ
/Co
s)2O}(CO)4] [meanꢀ
in As. . .As separations of 3.373 A and 3.421 A for 4a
and 4b, respectively; both values are larger than the
/
˚
˚
vector. The Co2As2S rings of 4a and 4b do not exhibit
quite such a degree of regularity, probably an effect on
the crystal packing of accommodating the more bulky
phenyl rings of the arsine ligand.
˚
A
distance of 3.089
s)2O}(CO)4] [3a].
in [Co2(m-PhCCH){m-(Ph2A-
Comparing the structure of 2 with that of [Co2{m-
C2(CO2Me)2}{m-(Me2As)2O}(CO)4] [3a] and the struc-
tures of 4a and 4b with that of [Co2(m-PhCCH){m-
(Ph2As)2O}(CO)4] [3a] the major changes involve mod-
ifications of the bridging arsine ligand geometry. The
narrowing of bond angles subtended at chalcogen atoms
as the chalcogen group is descended is a well-documen-
The (R2As)2S-bridged complexes feature larger CoÃ
CoÃAs angles [meanꢀ101.56(4)8 (2); 100.74(5)8 (4a);
101.68(7)8 (4b)] and longer CoÃAs bonds [meanꢀ
/
/
/
/
/
˚
˚
˚
2.327(1) A (2); 2.338(1) A (4a); 2.338(2) A (4b)] than
in [Co2(m-PhCCH){m-(Ph2As)2O}(CO)4] [97.07(4)8,
˚
2.306(1) A] and [Co2{m-C2(CO2Me)2}{m-(Me2A-
˚
s)2O}(CO)4] [97.4(1)8, 2.319(1) A] which presumably
ted fact. The HÃ
but only 92.18 for Xꢀ
that the AsÃSÃAs angles in complexes 4 [97.02(8)8 in 4a;
100.3(1)8 in 4b] are smaller than the AsÃOÃAs angle in
/
XÃ
/
H angle in H2X is Â
/
1058 for Xꢀ
/
O
allow the longer As. . .As separation of the arsineꢁ
sulfide ligand to be accommodated by the dicobalt
/
/
S. It is, therefore, unsurprising
/
/
unit without introducing unnecessary strain or produ-
/
/
cing an unusually long CoÃ
/
Co bond. The mean metalꢁ
/

J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ
/114
107
Fig. 3. Molecular structure of [Co2(m-PhCCPh){m-(Ph2As)2S}(CO)4] (4b) (molecule 1 only) including the atom numbering scheme. The hydrogen
atoms have been omitted for clarity.
metal bond lengths for complexes 2, 4a and 4b are fairly
unremarkable for CoÃCo bonds in this type of complex
[3a,10] although as expected from the steric constraints
placed on it by the bridging ligand, the metalꢁmetal
The 13C-NMR spectrum also shows a number of lines
attributable to phenyl carbons of the AsPh3 ligand.
There are further sharp signals at d 173.0 ppm, d 74.0
/
ppm and d 53.2 ppm, assigned to the CO2Me, C Ã
/
/
˚
CO2Me and CO2Me groups. In the carbonyl region,
two resonances are noted at d 202.2 ppm and d 198.0
ppm, consistent with substitution of the axial carbonyl
at one cobalt atom. Fluxional processes in such systems
have been discussed previously [3a].
bond increases in length from 2.477(3) A in [Co2{m-
C2(CO2Me)2}(CO)6] [10] to 2.495(1) A in 2 and 2.498(2)
˚
˚
A in 4a.
The 13C-{1H}-NMR spectra of 4a and 4b recorded at
room temperature show, as with 2, only one signal in the
terminal carbonyl region. Accordingly, the singlet
resonance must signify that the molecules are fluxional,
since in a non-fluxional situation two equal-intensity
resonances would be expected, one corresponding to the
pseudo-axial and the other to the pseudo-equatorial
carbonyls. Possible mechanisms for this fluxional pro-
cess have been discussed elsewhere for [Co2{C2(CO2-
Me)2}{m-(Me2As)O}(CO)4] [3a] and [Co2{C2(CO2-
Me)2}(m-P2Ph4)(CO)4] [9].
2.3. Thermolytic reactions
Heating 3a in toluene at 70 8C for 15 h gave green
[Co3(m3-S){m-(Ph2As)2O}{m-(Ph2AsS)}(CO)7] (6) in low
yield (Scheme 3). Complex 6 has been characterised by
IR, 1H- and 13C-NMR spectroscopy, mass spectrometry
and microanalysis (see Table 1).
1
The H- and 13C-NMR spectra of 6 exhibit phenyl
By comparison with the spectrosopic data of other
mono-arsine substituted alkyne-bridged dicobalt com-
plexes [3a], 5 may be formulated as [Co2{m-C2(CO2-
Me)2}(CO)5(AsPh3)]. In the 1H-NMR spectrum of 5
phenyl resonances which integrate to 15H and a peak at
d 3.60 ppm are observed. This latter signal corresponds
to six protons and is assigned to the CO2Me groups.
resonances only. Six resonances attributable to the ipso-
carbons of the phenyls are clearly visible, indicating that
each of the six-phenyl groups in this molecule resides in
a chemically distinct environment as expected from the
proposed structures.
Reaction of [Co3(m3-CMe){m-(Me2As)2O}(CO)7] with
H2S in toluene at 70 8C generates [Co3(m3-S){m-

108
J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ114
/
Table 2
˚
Selected bond lengths (A) and angles (8) for 2, 4a and 4b
2
4a
4b
Molecule 1
Molecule 2
Bond lengths
Co(1)Ã
C(1)ÃC(2)
Co(1)Ã
Co(1)Ã
Co(2)Ã
Co(2)Ã
Co(1)Ã
Co(2)Ã
As(1)Ã
As(2)Ã
AsÃ
CoÃ
CÃ
/
Co(2)
2.495(1)
1.354(7)
1.940(5)
1.942(5)
1.944(5)
1.928(5)
2.326(1)
2.327(1)
2.227(2)
2.231(2)
2.498(2)
1.363(9)
1.937(6)
1.951(7)
1.928(6)
1.932(6)
2.343(1)
2.333(1)
2.245(2)
2.258(2)
2.476(2)
1.34(1)
1.98(1)
1.96(1)
1.96(1)
1.96(1)
2.327(2)
2.350(2)
2.227(3)
2.239(3)
2.461(2)
1.36(1)
2.02(1)
1.95(1)
1.99(1)
1.94(1)
2.327(2)
2.348(2)
2.240(3)
2.239(3)
/
/
C(1)
C(2)
C(1)
C(2)
As(1)
As(2)
/
/
/
/
/
/S(1)
/S(1)
/
C
1.946(5)ꢁ
1.775(6)ꢁ
1.135(7)ꢁ
/
1.954(6)
1.795(7)
1.148(6)
1.946(4)ꢁ
1.802(9)ꢁ
1.133(8)ꢁ
/
1.961(3)
1.813(9)
1.150(9)
1.965(6)ꢁ
1.76(1)ꢁ
1.13(1)ꢁ
/
1.981(5)
1.929(6)ꢁ1.948(5)
1.76(1)ꢁ
1.14(1)ꢁ
/
/
Ccarbonyl
/
/
/
1.83(1)
/
1.79(1)
/
O
/
/
/
1.15(1)
/
1.16(1)
Bond angles
C(1)ÃC(2)Ã
C(1)ÃC(2)Ã
C(2)ÃC(1)Ã
C(2)ÃC(1)Ã
Co(1)ÃC(2)Ã
Co(1)ÃC(1)Ã
C(1)ÃCo(1)Ã
C(2)ÃCo(1)Ã
C(1)ÃCo(2)Ã
C(2)ÃCo(2)Ã
C(2)ÃCo(2)Ã
C(1)ÃCo(1)Ã
As(1)Ã
As(2)Ã
Co(1)Ã
Co(2)Ã
As(1)ÃS(1)Ã
C(5)ÃCo(1)Ã
C(4)ÃCo(2)Ã
CoÃAsÃ
C(2)ÃC(1)Ã
C(1)ÃC(2)Ã
/
/
Co(2)
Co(1)
Co(1)
Co(2)
70.2(3)
69.5(3)
69.7(3)
69.1(4)
68.9(4)
70.0(4)
69.5(4)
80.1(3)
80.5(3)
49.6(2)
49.6(2)
49.9(2)
50.3(2)
41.4(3)
41.1(3)
99.69(6)
101.79(5)
113.44(7)
113.67(6)
97.02(8)
147.2(2)
147.2(2)
69.9(6)
70.8(6)
69.3(6)
70.0(6)
78.4(4)
77.9(4)
50.7(3)
50.8(3)
51.4(3)
50.8(3)
40.1(4)
39.9(4)
71.8(6)
72.8(6)
67.2(6)
67.8(6)
78.7(4)
75.8(4)
51.6(3)
50.5(3)
52.6(3)
50.8(3)
40.4(4)
40.0(4)
/
/
/
/
/
/
68.9(3)
/
/
Co(2)
Co(2)
Co(2)
Co(2)
Co(1)
Co(1)
C(1)
80.3(2)
79.9(2)
50.1(1)
/
/
/
/
/
/
49.6(2)
/
/
50.0(2)
/
/
50.1(2)
/
/
40.9(2)
/
/C(2)
40.8(2)
/
Co(1)Ã
Co(2)Ã
As(1)Ã
As(2)Ã
/
Co(2)
Co(1)
S(1)
101.74(4)
101.38(4)
114.78(6)
114.61(5)
100.49(7)
147.9(2)
146.0(2)
101.95(7)
100.87(7)
118.3(1)
117.5(1)
100.0(1)
149.2(4)
146.7(4)
103.22(7)
100.68(7)
117.02(9)
117.90(9)
100.5(1)
150.4(4)
149.0(4)
/
/
/
/
/
/
S(1)
/
/As(2)
/
/Co(2)
/
/Co(1)
/
/
Cphenyl
ꢁ/
ꢁ/
116.3(3)ꢁ
139.2(9)
142.0(1)
/121.3(3)
117.0(2)ꢁ
139.0(1)
141.0(1)
/122.0(3)
/
/C(11)
139.3(5)
131.7(6)
/
/C(21)
140.2(5)
134.4(6)
(Me2As)2S}{m-(Me2AsS)}(CO)5] (7) and [Co3(m3-S){m-
(Me2As)2O}{m-(Me2AsS)}(CO)5] (8) in moderate yields,
respectively (Scheme 3). Both products have been
capping sulfur is displaced toward Co(2) and away
from Co(1), giving Co(2)ÃS(1) and Co(1)ÃS(1) distances
of 2.164(7) A and 2.191(7) A, respectively.
/
/
˚
˚
1
characterised by IR, H- and 13C-NMR spectroscopy,
In the structurally characterised (Me2As)2O-bridged
alkyne and alkylidyne complexes [Co2{m-C2(CO2-
mass spectrometry and microanalysis (see Table 1).
Additionally, complex 8 has been the subject of a single
crystal X-ray diffraction study.
The molecular structure of 8 is shown in Fig. 4;
selected bond lengths and angles are presented in Table
3. The complex features a tetrahedral Co3S core with
Me)2}{m-(Me2As)2O}(CO)4]
and
[Co3(m3-CCl){m-
(Me2As)2O}(CO)7] [3a], the two bridged metal atoms
are electronically equivalent. In 8, this is not the case;
Co(3), surrounded by good s-donors but with only one
carbonyl ligand is more electron rich than Co(2).
one edge bridged by an Me2AsÃ
/
S ligand, which acts as a
Increased back-donation to As(2) from Co(3) may
˚
As(2) bond [2.264(4) A] is
three-electron donor, and with a second edge bridged by
an (Me2As)2O unit. Both ligands occupy pseudo-equa-
torial sites at cobalt. The geometry of the core deviates
from that of a regular tetrahedron since, although the
tricobalt triangle is approximately isosceles, the three
explain why the Co(3)Ã
/
˚
As(1) bond [2.304(4) A].
Five singlets attributable to methyl groups appear in
shorter than the Co(2)Ã
/
1
the H-NMR spectra of both 7 and 8. Four of these
signals have an intensity corresponding to three protons
but the remaining signal has twice this intensity. In the
cobaltꢁ/apical sulfur distances are all different. The

J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ
/114
109
Scheme 3. Reagents and conditions: (i) 70 8C, C6H5CH3; (ii) H2S, 70 8C, C6H5CH3.
13C-NMR spectra of the two complexes, six methyl
group signals of approximately equal intensity are
observed in each case. No further resonances are
discernible.
From Fig. 4, which displays the molecular structure
of 8, it can be seen that the six methyl groups occupy six
chemically distinct environments. Assuming that the
solid-state structure is maintained in solution, six methyl
Fig. 4. Molecular structure of [Co3(m3-S){m-(Me2As)2O}{m-(Me2AsS)}(CO)5] (8) including the atom numbering scheme.

110
J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ114
/
Table 3
˚
Selected bond lengths (A) and angles (8) for 8
Bond lengths
Co(1)Ã
Co(2)Ã
Co(3)Ã
Co(1)Ã
Co(3)Ã
As(3)Ã
As(2)Ã
AsÃ
Co(1)Ã
Co(2)Ã
Co(1)Ã
Co(2)Ã
Co(3)Ã
As(1)Ã
CoÃCcarbonyl
CÃ
/
Co(2)
Co(3)
As(2)
S(1)
2.535(4)
2.527(4)
2.264(4)
2.191(7)
2.157(7)
2.203(7)
1.79(2)
/
/
/
/S(1)
/S(2)
/O(6)
/
Cmethyl
1.91(2)ꢁ
2.482(4)
2.304(4)
2.295(4)
2.164(7)
2.334(7)
1.77(2)
/
1.98(2)
/
Co(3)
As(1)
As(3)
S(1)
/
/
/
/S(2)
/O(6)
/
1.71(3)ꢁ
1.13(3)ꢁ
/
1.80(3)
1.19(4)
/
O
/
Bond angles
Co(3)ÃCo(1)Ã
As(3)ÃCo(1)ÃCo(3)
S(1)ÃCo(1)Ã
S(1)ÃCo(2)Ã
S(1)ÃCo(2)Ã
S(2)ÃCo(3)Ã
As(2)ÃCo(3)Ã
S(1)ÃCo(3)ÃS(2)
O(6)ÃAs(2)Ã
Co(2)ÃS(1)Ã
Co(3)ÃS(1)Ã
As(1)ÃO(6)Ã
S(1)ÃCo(1)Ã
S(1)ÃCo(1)Ã
Co(3)Ã
As(1)Ã
S(1)ÃCo(3)Ã
Co(1)Ã
S(1)ÃCo(3)Ã
O(6)ÃAs(1)Ã
S(2)ÃAs(3)ÃCo(1)
Co(3)ÃS(1)ÃCo(1)
As(3)ÃS(2)ÃCo(3)
/
/
Co(2)
60.5(1)
78.5(1)
94.4(2)
54.9(2)
54.1(2)
94.2(2)
100.1(2)
100.7(3)
110.5(6)
71.2(2)
71.6(2)
120.0(1)
53.9(2)
54.5(2)
58.7(1)
93.7(1)
55.8(2)
60.8(1)
54.3(2)
114.4(6)
103.4(2)
69.6(2)
83.6(2)
/
/
Scheme 4. Proposed reversible bridge opening/closing on addition/
elimination of H2X [XꢀO, S].
/
/
As(3)
Co(1)
Co(3)
Co(1)
/
/
/
/
/
In effect, addition of H2S reverses the condensation
process to generate one R2AsOH ligand and a neigh-
bouring R2AsSH ligand. Condensation can then reoccur
to eliminate H2S, regenerating the starting material, or
to eliminate H2O, yielding the (R2As)2S derivative.
Whilst the H2S purge continues, solutions of the
(R2As)2O complexes can be converted quantitatively
to the sulfide derivative but, once purging ceases the
process begins to reverse either partially or, in some
cases, completely.
While it is clear that the bis-diarsine sulfide complexes
do form, they fairly readily reconvert to the bis-diarsine
oxide derivatives at room temperature. On carrying out
the reaction with H2S at higher temperature, however,
the initially generated (R2As)2S complex undergoes
/
/
/
/
Co(2)
/
/
/
/
Co(3)
Co(1)
Co(2)
/
/
/
/
/
/
As(2)
Co(2)
Co(3)
/
/
/
/
/
Co(2)ÃCo(1)
/
/
Co(2)Ã
/
Co(3)
/
/
Co(1)
/
Co(3)Ã
Co(2)
Co(2)
/
Co(2)
/
/
/
/
/
/
/
/
/
/
cleavage of one AsÃ
/
S bond giving new sulfur-containing
species. Formation of these species is not reversible even
when the H2S purge ceases.
Thermolysis of the complex, [Co3(m3-CMe){m-(Me2A-
s)2O}(CO)7] in the presence of H2S presumably pro-
signals would be expected in both the carbon and proton
NMR spectra. These are observed in the 13C-NMR
1
spectrum but in the H spectrum, two of the signals are
duces initially the arsineꢁsulfide analogue 1b via the
/
mechanism which has already been discussed for the
dinuclear complexes 1a and 1b (Scheme 4). The pathway
by which this complex is subsequently converted into
[Co3(m3-S){m-(Me2As)2O}{m-Me2AsS}(CO)5] must in-
presumably coincident. Since it is proposed that 6 shares
the same structure as complex 8, similar arguments
apply to an analysis of its NMR spectra.
volve arsenicꢁsulfur bond rupture and the excision of
/
an AsMe2 group but the precise mechanism is unclear.
As described in Section 2.2, the direct reaction of
(Ph2As)2S with the alkylidyne-tricobalt and alkyne-
dicobalt complexes yields the expected complexes 3
and 4 with bridging (Ph2As)2S ligands. More note-
worthy is the simultaneous formation of the mono-
Ph3As-substituted complex 5. We have also observed
this type of side-product in the reaction of other alkyne-
2.4. Reaction pathway
The proposed pathway for the reaction of the bound
(R2As)2O ligand with H2S to generate a coordinated
(R2As)2S molecule is based on the hydrolytic mechanism
previously proposed for the formation of bridged
(R2As)2O complexes from As2R4 bridged complexes
(Scheme 4) [3a].

J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ
/114
111
bridged dicobalt complexes with (Ph2As)2S although not
with [Co2(m-PhCCPh)(CO)6] [11]. Thermal modification
of the free (Ph2As)2S ligand to give free AsPh3 is not
known and it is possible that this is a metal-mediated
process, requiring coordination of (Ph2As)2S in a
the (Me2As)2O-bridged product 8 goes on to react with
H2S.
2.5. Conclusions
monodentate mode followed by AsÃ
and simultaneous AsÃC bond formation for the dico-
balt complexes (Scheme 5). The RÃAsÄS species
liberated belongs to the known group of thioarsenoso
compounds, which usually exist as oligomers (RÃAsÃ
S)n in solution [12].
/
S bond cleavage
The observation that reversible substitution of S for O
/
takes place in complexes with bridging AsÃ
ligands supports the mechanism previously published
As complexes from diarsines
/
OÃ/As
/
/
for formation of AsÃ
/
OÃ
/
via complexes with AsR2OH ligands [3a]. As expected,
direct reaction of bis-diphenylarsine sulfides with di-
/
/
and tri-cobalt complexes gives AsÃ
plexes in good yields without formation of complexes
with pendant ligands. Metal-mediated AsÃS bond
rupture in such complexes may explain the formation
of R3As-substituted derivatives. Thermally induced AsÃ
S bond rupture in AsÃSÃAs bridged tricobalt complexes
can lead to complexes that contain an AsR2ÃS unit.
/
SÃ
/
As bridged com-
Thermolysis of the (Ph2As)2S-bridged alkylidyne
tricobalt complex 3a yields [Co3(m3-S)(CO)5{m-(Ph2A-
s)2O}{m-(Ph2AsS)}] (6). This is not unexpected on the
basis of the reaction that generates 7 and 8 and the
synthetic pathway is, presumably, essentially the same.
It is notable, however, that in the present case, where
thermolysis does not take place in the presence of H2S,
only the product with an (Ph2As)2O bridge is formed;
there is no trace of the corresponding (Ph2As)2S-bridged
complex. It may be that this does not form during the
reaction or that it does form but is desulfurised under
the conditions employed. The implication is that the
(Me2As)2S-bridged product, 7, is obtained only because
/
/
/
/
/
3. Experimental
3.1. General techniques
All reactions were carried out under an atmosphere of
dry, oxygen-free nitrogen, using standard Schlenk
techniques. Solvents were distilled under nitrogen from
appropriate drying agents and degassed prior to use [13].
Preparative thin-layer chromatography was carried out
on 1 mm plates prepared at the Department of
Chemistry, Cambridge. Column chromatography was
performed on Kieselgel 60 (70ꢁ230 mesh). Products are
/
given in order of decreasing Rf values. Infrared spectra
were recorded in n-hexane or CH2Cl2 solution in 0.5
mm NaCl cells, using a Perkinꢁ/Elmer Paragon 1000
Fourier-Transform spectrometer or a Perkinꢁ
/Elmer
1600 series spectrometer. Fast atom bombardment
mass spectra were obtained on a Kratos MS890 instru-
ment. Fast ion bombardment mass spectra were ob-
tained on a Kratos MS50 instrument. Nitrobenzyl
alcohol was used as a matrix. 1H- and 13C-NMR spectra
were recorded on Bruker AM400 or WM250 spectro-
meter using the solvent resonance as an internal
standard. Microanalyses were performed by the Micro-
analytical Department, University of Cambridge.
Unless otherwise stated, all reagents were obtained
from commercial suppliers and used without further
purification. The compounds [Co2(m-R?CCR??)(CO)6]
(R?ꢀ
/
R??ꢀ
/
CO2Me, Ph) [14], [Co3(m3-CR?)(CO)9]
(R?ꢀ
/
Me or Cl) [15], were prepared by literature
methods. Complexes [Co2{m-C2(CO2Me)2}{m-(Me2A-
s)2O}(CO)4] and [Co3(m3-CR?){m-(Me2As)2O}(CO)7]
[R?ꢀCl, Me] were synthesised by the procedures
/
described previously [3a]. The oxide, (Ph2As)2O [16],
was synthesised by reaction of PhMgBr and As2O3.
Scheme 5. Possible pathway for the direct reaction of [Co2(m-
R?CCR??)(CO)6] with (Ph2As)2S.

112
J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ114
/
Treatment of this oxide with H2S generated (Ph2As)2S
[8].
ii) R?ꢀMe. [Co3(m3-CMe)(CO)9] (488 mg, 1.07 mmol)
/
and (Ph2As)2S (1.57 g, 3.2 mmol) were dissolved in
toluene (60 ml) and heated at 35 8C with stirring for
24 h. By employing a similar work-up to (i), but
using hexane/CH2Cl2 (9:1) as eluent, gave [Co3(m3-
CMe){m-(Ph2As)2S}(CO)7] (3b) (619 mg, 65%).
3.2. Reaction of [Co3(m-CR?){m-(Me2As)2O}(CO)7]
and H2S
i) R?ꢀCl. [Co3(m-CCl){m-(Me2As)2O}(CO)7] (386
/
mg, 0.60 mmol) was dissolved in benzene (70 ml)
and purged with H2S at room temperature for 10
min. After removal of all volatiles under reduced
pressure, the residue was dissolved in the minimum
quantity of CH2Cl2 and applied to the base of silica
TLC plates. Elution with hexane/CH2Cl2 (4:1) gave
bluish-black [Co3(m-CCl){m-(Me2As)2S}(CO)7] (1a)
(179 mg, 45%) and deep purple, crystalline [Co3(m-
CCl){m-(Me2As)2O}(CO)7] (185 mg, 48%).
3.5. Reaction of [Co2(m-R?CCR??)(CO)6] and
(Ph2As)2S
i) R?ꢀ
/
R??ꢀ/CO2Me.
[Co2{m-C2(CO2Me)2}(CO)6]
(238 mg, 0.56 mmol) and (Ph2As)2S (0.97 g, 1.98
mmol) were dissolved in toluene (60 ml) and heated
at 35 8C with stirring for 24 h. After removal of the
reaction solvent under vacuum, the residue was
dissolved in the minimum quantity of CH2Cl2 and
adsorbed onto silica. The silica was pumped dry and
transferred to the top of a silica chromatography
column. Elution with hexane/ethyl acetate (4:1) gave
unreacted [Co2{m-C2(CO2Me)2}(CO)6], [Co2{m-
C2(CO2Me)2}(CO)5(AsPh3)] (5) (170 mg, 43%) and
[Co2{m-C2(CO2Me)2}{m-(Ph2As)2S}(CO)4] (4a) (148
mg, 31%). Crystals of 4a suitable for X-ray diffrac-
tion were grown by slow evaporation at 0 8C of a
hexane/CH2Cl2 solution of the complex.
ii) R?ꢀMe. [Co3(m-CMe){m-(Me2As)2O}(CO)7] (307
/
mg, 0.49 mmol) was dissolved in benzene (70 ml)
and purged with H2S at room temperature for 10
min. By employing a similar work-up as in (i),
bluish-black
[Co3(m-CMe){m-(Me2As)2S}(CO)7]
(1b) (148 mg, 47%) and deep purple, crystalline
[Co3(m-CMe){m-(Me2As)2O}(CO)7] (150 mg, 49%)
were isolated.
ii) R?ꢀ
/
R??ꢀPh. [Co2(m-PhCCPh)(CO)6] (264 mg,
/
3.3. Reaction of [Co2{m-C2(CO2Me)2}{m-
(Me2As)2O}(CO)4] and H2S
0.57 mmol) and (Ph2As)2S (840 mg, 1.7 mmol)
were dissolved in toluene (60 ml) and heated at
35 8C with stirring for 24 h. By employing a similar
work-up to (i), but using hexane/CH2Cl2 (4:1) as
eluent, gave [Co2(m-PhCCPh){m-(Ph2As)2S}(CO)4]
(4b) (444 mg, 87%). Crystals of 4b suitable for X-ray
diffraction were grown by slow evaporation at 0 8C
of a hexane/CH2Cl2 solution of the complex.
[Co2{m-C2(CO2Me)2}{m-(Me2As)2O}(CO)4] (368 mg,
0.60 mmol) was dissolved in toluene (70 ml) and purged
with H2S at room temperature for 10 min. After removal
of the volatiles under reduced pressure, the residue was
dissolved in the minimum quantity of CH2Cl2 and
applied to the base of silica TLC plates. Elution with
hexane/ethyl acetate (4:1) gave red [Co2{m-C2(CO2-
Me)2}{m-(Me2As)2S}(CO)4] (2) (212 mg, 56%) and red,
crystalline [Co2{m-C2(CO2Me)2}{m-(Me2As)2O}(CO)4]
(140 mg, 38%). Crystals of 2 suitable for X-ray diffrac-
tion were grown by slow evaporation at 0 8C of a
hexane/CH2Cl2 solution of the complex.
3.6. Thermolysis of [Co3(m3-CCl){m-
(Ph2As)2S}(CO)7] (3a)
Complex 3a (2.00 g, 2.20 mmol) was dissolved in
toluene (50 ml) and heated with stirring at 70 8C for 15
h. After removal of all volatiles under reduced pressure,
the residue was dissolved in a minimum quantity of
CH2Cl2 and adsorbed onto silica. The silica was pumped
dry and transferred to the top of a silica chromatogra-
phy column. Elution with hexane/CH2Cl2 (1:1) gave
unreacted [Co3(m3-CCl){m-(Ph2As)2S}(CO)7] and green
[Co3(m3-S){m-(Ph2As)2O}{m-(Ph2AsS)}(CO)5] (6) (100
mg, 4%).
3.4. Reaction of [Co3(m3-CR?)(CO)9] and
(Ph2As)2S
i) R?ꢀCl. [Co3(m3-CCl)(CO)9] (571 mg, 1.20 mmol)
/
and (Ph2As)2S (1.76 g, 3.6 mmol) were dissolved in
toluene (60 ml) and heated at 35 8C with stirring for
20 h. After removal of the reaction solvent under
vacuum, the residue was dissolved in the minimum
quantity of CH2Cl2 and adsorbed onto silica. The
silica was pumped dry and transferred to the top of
a silica chromatography column. Elution with
hexane/CH2Cl2 (4:1) gave purple [Co3(m3-CCl){m-
(Ph2As)2S}(CO)7] (3a) (590 mg, 54%). Two other
brown products followed in very minor yield; these
were not collected.
3.7. Reaction of [Co3(m-CMe){m-(AsMe2)2O}(CO)7]
and H2S at 70 8C
Complex [Co3(m-CMe){m-(Me2As)2O}(CO)7] (326
mg, 0.52 mmol) was dissolved in toluene (70 ml). The
solution was heated to 70 8C and purged with H2S for 45
min. After removal of all volatiles under reduced

J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ
/114
113
Table 4
X-ray crystallographic and data processing parameters for complexes 2, 4a, 4b and 8
Complex
2
4a
4b
8
Empirical formula
Formula weight
Temperature (K)
Crystal system
C
614.04
14H18As2Co2O8S
C11H18As3Co3O6S2
711.92
293(2)
C42H30As2Co2O4S
898.42
293(2)
C34H26As2Co2O8S
862.31
295(2)
293(2)
Monoclinic
P21/n
Monoclinic
P21/c
Triclinic
¯
P1
Triclinic
¯
P1
Space group
/
/
Unit cell dimensions
˚
a (A)
˚
9.445(2)
14.476(3)
16.947(4)
12.757(2)
10.024(3)
18.918(4)
12.178(4)
18.256(4)
20.038(4)
115.261(11)
103.961(17)
93.46(2)
3842(2)
4
11.442(3)
12.726(3)
13.234(3)
78.16(2)
72.22(2)
73.76(2)
1746.6(7)
2
b (A)
˚
c (A)
a (8)
b (8)
g (8)
V (A )
Z
ꢁ/
ꢁ/
98.84(2)
100.06(2)
ꢁ/
ꢁ/
3
˚
2289.5(9)
4
4.442
2382(1)
4
6.396
m (Moꢁ
/
Ka) (mmꢃ1
)
2.668
2.938
Crystal size (mm3)
Reflections collected
Independent reflections
0.48ꢄ
8580
4038 [Rint
0.0435, wR2ꢀ
0.0950, wR2ꢀ
/0.34ꢄ
/
0.27
0.30ꢄ
3499
3328 [Rint
0.0695 R1ꢀ0.0795, wR2ꢀ
0.0810 R1ꢀ0.2040, wR2ꢀ
/
0.15ꢄ
/
0.10
0.48ꢄ/0.48ꢄ
/
0.44
0.40ꢄ
7153
6141 [Rint
0.1120 R1ꢀ0.0570, wR2ꢀ
0.1406 R1ꢀ0.1183, wR2ꢀ
/
0.32ꢄ
/
0.12
12438
ꢀ/
0.0517]
ꢀ/
0.06]
10658 [Rint
ꢀ
/
0.0559]
ꢀ0.0405]
/
Final R indices [I ꢀ
/
2s(I)] R1ꢀ
/
/
/
/
0.1833 R1ꢀ/0.0641, wR2ꢀ
/
/
/
0.1123
0.1352
R indices (all data)
R1ꢀ
/
/
/
/
0.3112 R1ꢀ/0.1711, wR2ꢀ
/
/
/
pressure, the residue was dissolved in a minimum
quantity of CH2Cl2 and adsorbed onto silica. The silica
was pumped dry and transferred to the top of a silica
chromatography column. Elution with hexane/CH2Cl2
with isotropic displacement parameters, empirical ab-
sorption corrections were applied to the data of 2 [19].
Anisotropic displacement parameters were assigned in
structures 2, 4a and 4b to all non-hydrogen atoms and in
8 to the cobalt, arsenic and sulfur atoms only.
(3:2)
gave
brown
[Co3(m3-S){m-(Me2As)2S}{m-
(Me2AsS)}(CO)5] (7) (68 mg, 18%) and purple [Co3(m3-
S){m-(Me2As)2O}{m-(Me2AsS)}(CO)5] (8) (81 mg, 22%).
Crystals of 8 were grown by evaporation at 0 8C of a
hexane/CH2Cl2 solution of the complex.
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
3.8. Crystal structure determinations of complexes 2, 4a,
4b and 8
Data Centre, CCDC Nos. 157608ꢁ157611 for com-
/
pounds 2, 4a, 4b and 8, respectively. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2 1EZ
For 2, 4a and 4b X-ray intensity data were collected
on a Siemens P4 four-circle diffractometer and for 8 on
a Rigaku AFC5R four-circle diffractometer. Table 4
lists details of data collection, refinement and crystal
data. The crystals of 8 diffracted very weakly, possibly
due to solvent loss. Data were corrected for Lorentz and
polarisation factors.
(Fax: ꢂ44-1223-336033; e-mail deposit@ccdc.cam.ac.
/
uk or www: http://www.ccdc.cam.ac.uk).
Acknowledgements
For all structures, the positions of the metal atoms
and most of the non-hydrogen atoms were located by
direct methods [17] and subsequent difference-Fourier
syntheses revealed the positions of the remaining non-
hydrogen atoms. Refinement [17] was based on F2.
Phenyl rings were refined with idealised geometries. The
phenyl and methyl hydrogen atoms were placed in
calculated positions with displacement parameters equal
to, respectively, 1.2 and 1.5 times Ueq of the parent
carbon atoms. There were two independent molecules
per equivalent position in the crystal structure of 4b.
Absorption corrections were applied to the data of 8, 4a
and 4b using c-scans [18] and after initial refinement
We thank Dstl (Fort Halstead) for financial support
to J.D.K. The help of Dr. G. Conole (North London),
Dr. J.E. Davies (Cambridge) and Professor P.R. Raith-
by (Bath) with the crystal structure determinations is
gratefully acknowledged.
References
[1] (a) F.A. Cotton, C.R. Falvello, M. Tomas, G.M. Gray, C.S.
Kraihanzel, Inorg. Chim. Acta 82 (1984) 129;
(b) H. Einspahr, J. Donohue, Inorg. Chem. 13 (1974) 1839;

114
J.D. King et al. / Journal of Organometallic Chemistry 681 (2003) 102ꢁ114
/
(c) S. Hoehne, E. Lindner, J.-P. Gumz, Chem. Ber. 111 (1978)
3818.
[5] E.W. Abel, M.A. Beckett, P.A. Bates, M.B. Hursthouse, J.
Organomet. Chem. 325 (1987) 261.
[6] R.A. Zingaro, K.J. Irgolic, D.H. O’Brien, L.J. Edmunson, Jr., J.
Am. Chem. Soc. 93 (1971) 5677.
[2] (a) E.H. Wong, L. Prasad, E.J. Gabe, F.C. Bradley, J. Organo-
met. Chem. 236 (1982) 321;
[7] (a) K. Sommer, Z. Anorg. Allg. Chem. 377 (1970) 120;
(b) K. Sommer, Z. Anorg. Allg. Chem. 383 (1971) 136.
[8] A. Michaelis, Liebigs Ann. Chem. 321 (1902) 141.
[9] A.J.M. Caffyn, M.J. Mays, G.A. Solan, D. Braga, P. Sabatino, G.
Conole, M. McPartlin, H.R. Powell, J. Chem. Soc. Dalton Trans.
(1991) 3103.
(b) E.H. Wong, F.C. Bradley, L. Prasad, E.J. Gabe, J. Organo-
met. Chem. 263 (1984) 167;
(c) C. Zeiher, J. Mohyla, I.-P. Lorenz, W. Hiller, J. Organomet.
Chem. 286 (1985) 159;
(d) R.E. Marsh, Acta Crystallogr. Sect. B 53 (1997) 317;
(e) F.C. Bradley, E.H. Wong, E.J. Gabe, F.L. Lee, Y. Lepage,
Polyhedron 6 (1987) 1103;
[10] D. Gregson, J.A.K. Howard, Acta Crystallogr. Sect. C 39 (1983)
1024.
(f) D.J. Irvine, D.J. Cole-Hamilton, J. Barnes, P.K.G. Hodgson,
Polyhedron 8 (1989) 1575;
[11] J.D. King, M.J. Mays, G.A. Solan, unpublished results.
[12] (a) R.A. Zingaro, R.E. McGlothin, R.M. Hedges, Trans. Faraday
Soc. 59 (1963) 798;
(g) D.J. Irvine, C. Glidewell, D.J. Cole-Hamiliton, J.C. Barnes, A.
Howie, J. Chem. Soc. Dalton Trans. (1991) 1765;
(h) G.A. Acum, M.J. Mays, P.R. Raithby, H.R. Powell, G.A.
Solan, J. Chem. Soc. Dalton Trans. (1997) 3427;
(i) E. Lindner, S. Hoehne, J.-P. Gumz, Z. Naturforsch. B 35
(1980) 937;
(b) L. Anschutz, H. Wirth, Chem. Ber. 89 (1956) 1530;
¨
(c) A.-J. Di Maio, A.L. Rheingold, Inorg. Chem. 29 (1990) 798.
[13] W.L.F. Armarego, D.D. Perrin, Purification of Laboratory
Chemicals, 4th ed., ButterworthꢁHeinemann, London, 1996.
/
[14] (a) H.W. Sternberg, R.A. Greenfield, J.H. Wotiz, R.A. Friedel, R.
Markby, I. Wender, J. Am. Chem. Soc. 76 (1954) 1457;
(b) R.A. Greenfield, H.W. Sternberg, R.A. Friedel, J.H. Wotiz, R.
Markby, I. Wender, J. Am. Chem. Soc. 78 (1956) 120;
(j) U. Florke, H.-J. Haupt, Z. Kristallogr. 192 (1990) 293;
(k) A.D. Burrows, M.F. Mahon, M.T. Palmer, M. Varrone,
Inorg. Chem. 41 (2002) 1695.
[3] (a) N. Choi, G. Conole, J.D. King, M.J. Mays, M. McPartlin,
C.L. Stone, J. Chem. Soc. Dalton Trans. (2000) 395;
(b) E.W. Abel, M.A. Beckett, Polyhedron 6 (1987) 1255;
(c) H. Beurich, H. Vahrenkamp, Chem. Ber. 114 (1981) 2542;
(d) H. Vahrenkamp, Chem. Ber. 105 (1972) 3574.
[4] (a) L.H. Doerrer, J.C. Green, M.L.H. Green, I. Haiduc, C.N.
Jardine, S.I. Pascu, L. Silaghi-Dumitrescu, D.J. Watkin, J. Chem.
Soc. Dalton Trans. (2000) 3347;
(c) U. Kruerke, W. Hubel, Chem. Ber. 94 (1961) 2829.
¨
[15] (a) D. Seyferth, J.E. Hallgren, P.L.K. Hung, J. Organomet.
Chem. 50 (1973) 265;
(b) J.J. Eisch, R.B. King (Eds.), Organometallic Syntheses, Vol. 1,
Academic Press, London, 1965.
[16] (a) F. Sachs, H. Kantoriwicz, Chem. Ber. 41 (1908) 2767;
(b) F.F. Blicke, F.D. Smith, J. Am. Chem. Soc. 51 (1929) 1558.
[17] SHELXTL, PC version 5.03, Siemens Analytical Instruments, Inc.,
Madison, WI, 1994.
(b) H. Vahrenkamp, Chem. Ber. 105 (1972) 3574;
(c) E.W. Ainscough, A.M. Brodie, G. Leng-Ward, J. Chem. Soc.
Dalton Trans. (1974) 2437;
[18] A.C.T. North, D.C. Philips, F.S. Matthews, Acta Crystallogr.
Sect. A 24 (1968) 351.
[19] N. Walker, D. Stuart, Acta Crystallogr. Sect. A 39 (1983) 158.
(d) L. Weber, D. Wewers, Organometallics 4 (1985) 841.