Synthesis and structures of tetranuclear rhenium-cobalt mixed metal sulfide clusters [Re3CoS4Cl6(PMe2Ph) 4]

Article abstract of DOI:10.1016/j.poly.2004.06.028

An isomeric pair of rhenium-cobalt sulfide clusters [Re₃CoS ₄Cl₆(PMe₂Ph)₄] was synthesized by the reaction of [(Ph₃P)₂N][Re₃S ₄Cl₆(PMe₂Ph)₃] with CoCl₂ in the presence of PMe₂Ph and their crystal structures were determined. The isomers differ in the orientation of the dimethylphenylphosphine ligands, which controls the coordination of three μ-S atoms in the starting cluster to the cobalt atom. An isomeric pair of the title compounds have been prepared and characterized by NMR spectroscopy and X-ray crystallography. The major isomer contains three dimethylphenylphoshine ligands coordinated to rhenium atoms in the direction of the μ₃-S atom in the starting trinuclear rhenium cluster complex, whereas the minor isomer has a dimethylphenylphosphine ligand in the opposite direction. The temperature of the preparative reactions controls the orientation of the phosphine ligands.

Full text of DOI:10.1016/j.poly.2004.06.028

Polyhedron 23 (2004) 2611–2614
www.elsevier.com/locate/poly
Synthesis and structures of tetranuclear rhenium–cobalt mixed metal
sulfide clusters [Re3CoS4Cl6(PMe2Ph)4]
*
Nobuaki Sakai, Taro Saito
Department of Chemistry, Faculty of Science and Hightech Research Center, Kanagawa University, Hiratsuka, Kanagawa 259-1293, Japan
Received 23 March 2004; accepted 23 June 2004
Available online 12 August 2004
Abstract
An isomeric pair of the title compounds have been prepared and characterized by NMR spectroscopy and X-ray crystallography.
The major isomer contains three dimethylphenylphoshine ligands coordinated to rhenium atoms in the direction of the l3-S atom in
the starting trinuclear rhenium cluster complex, whereas the minor isomer has a dimethylphenylphosphine ligand in the opposite
direction. The temperature of the preparative reactions controls the orientation of the phosphine ligands.
ꢀ 2004 Elsevier Ltd. All rights reserved.
Keywords: Rhenium cluster
1. Introduction
tetranuclear rhenium–cobalt mixed metal sulfide cluster
complexes coordinated by dimethylphenylphosphine.
Recent development of the chemistry of sulfide and
selenide cluster compounds of rhenium has been limited
mostly to hexanuclear compounds [1,2]. Only a few tri-
nuclear and tetranuclear rhenium chalcogenide cluster
compounds are known [3,4] and mixed metal clusters
are even rarer, a single example being a rhenium–nickel
complex [Re3NiS4Cl6(PEt3)4] [5]. Rhenium is a group 7
metal and its cations are isoelectronic with those of
group 6 molybdenum or tungsten in one-electron lower
oxidation states [3]. Since there are a number of mixed-
metal sulfide clusters of Mo(IV) or W(IV) [6–8], it is
anticipated that similar rhenium derivatives can be pre-
pared using Re(V). The starting compounds to prepare
rhenium cluster sulfide complexes are rare and Re3S7Cl7
[9], isoelectronic with Mo3S7Cl4 [10], is useful as a start-
ing compound to lead to either trinuclear [11–13] or
higher nuclear mixed-metal cluster compounds [5]. The
present paper, describes the preparation of the first
2. Experimental
2.1. Materials and methods
All experiments were performed under dinitrogen
atmosphere. Solvents were dried and distilled by the re-
ported methods. Electronic spectra were recorded on a
JASCO Ubest-570 UV–Vis spectrometer. 1H and 31P
NMR spectra were measured in CDCl3 with a JEOL
GX-400 spectrometer.
Rhenium metal, PMe2Ph and (PPh3)2NCl were pur-
chased from Aldrich, while CoCl2 was from WAKO
chemicals. These materials were used without further
purification. Re3S7Cl7 was prepared according to a liter-
ature method [9].
2.1.1. [Re3CoS4Cl6(PMe2Ph)4] Æ (C2H5)2O, 1
[(PPh3)2N][Re3S4Cl6(PMe2Ph)3] Æ 3CH2Cl2 [14]: Re3-
S7Cl7 (1.03 g, 0.99 mmol) and PMe2Ph (0.97 g, 7.02
mmol) in dichloromethane (30 mL) were reacted for 3
*
Corresponding author. Tel.: +81 46 359 4111; fax: +81 46 358
9684.
E-mail address: saito-tr@chem.kanagawa-u.ac.jp (T. Saito).
0277-5387/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2004.06.028

2612
N. Sakai, T. Saito / Polyhedron 23 (2004) 2611–2614
Table 1
Crystallographic data for 1 and 2
days at room temperature. The mixture was filtered and
the solvent was removed by evaporation. The residue
was washed twice with diethylether and dried. The prod-
uct was dissolved in dichloromethane (10 mL), and
(PPh3)2NCl (0.70 g, 1.21 mmol) was added to the solu-
tion. The dichloromethane solution was layered with
diethylether (30 mL) and then left to stand for 3 days.
The crystalline product was obtained by filtration.
1
2
Formula
C36H54Cl6-
C32H44Cl6-
CoP4Re3S4
1511.02
a
CoOP4Re3S4
1585.14
black
Formule weight (g molꢁ1
Crystallographic color
)
black
0.12 · 0.04 · 0.02
P21/c
Crystallographic size (mm3) 0.40 · 0.10 · 0.10
Space group
Unit cell dimensions
P21/c
A
solution of ½ðPP3Þ Nꢀ½Re3S4Cl6ðPMe2ꢁPhÞ ꢀꢂ
3
3CH2Cl2 ð0:35 g; 0:16 mmolÞ2 in dichloromethane (20
mL) was treated with CoCl2 (0.045 g, 0.34 mmol) and
PMe2Ph (0.1 g, 0.72 mmol) and stirred for 7 days at
room temperature and then refluxed for 90 min. The
solution was filtered, the solvent was evaporated and
the residue was washed with diethylether. The product
was dissolved in dichloromethane (10 mL), and diethyl-
ether (30 mL) was layered on the solution which was left
for 7 days. A black crystalline compound was obtained
in 38% yield. Anal. Calc. for C32H44CoCl6P4Re3S4 Æ
0.4C4H10O: C, 25.95; H, 3.16. Found: C, 26.06; H,
3.29%. UV–Vis (CH2Cl2): 522 nm (e 1123 Mꢁ1 cmꢁ1),
˚
a (A)
17.7793(7)
11.5586(5)
25.6951(11)
90
18.5585(8)
11.4916(5)
20.6682(8)
90
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
102.943(1)
90
96.476(1)
90
3
˚
V (A )
5146.3(4)
4
4379.7(3)
4
Z
T (ꢁC)
ꢁ100
ꢁ100
˚
Radiation (Mo Ka) (A)
qcalc (g cmꢁ3
l (mmꢁ1
h Range (ꢁ)
0.71069
2.046
7.977
0.71069
2.292
9.365
)
)
1.18–28.32
ꢁ20/23
1.10–28.28
ꢁ24/19
hkl Index ranges
ꢁ15/15
ꢁ15/12
1
771 nm (e 456 Mꢁ1 cmꢁ1). H NMR (d, CDCl3): 1.71
ꢁ34/23
ꢁ23/27
Goodness-of-fit on F2
R indices [I > 2r(I)]
1.055
1.039
(d, Re–P(CH3)2(C6H5)), 2.10 (dd, Co–P(CH3)2(C6H5)),
2.28 (d, Re–P(CH3)2(C6H5)), 7.22–7.87 (m, P(CH3)2
(C6H5)). 31P NMR (d, CDCl3, 15% H3PO4): ꢁ24.69
(Re–P(CH3)2(C6H5)), 38.77 (Co–P(CH3)2(C6H5).
R1 = 0.0283,
wR2 = 0.0807
R1 = 0.0345,
wR2 = 0.0859
R1 = 0.0396,
wR2 = 0.0744
R1 = 0.0505,
wR2 = 0.0790
R (all data)
Largest differential peak
ꢁ3
3.207 and ꢁ0.858 1.847 and ꢁ0.929
2.1.2. [Re3CoS4Cl6(PMe2Ph)4] 2
solution of [(PPh3)2N][Re3S4Cl6(PMe2Ph)3] Æ
˚
and hole (e A
)
A
a
Including a solvate molecule.
3CH2Cl2 (0.52 g, 0.24 mmol) in dichloromethane (20
mL) was stirred with CoCl2 (0.067 g, 0.56 mmol) for 4
days, following which PMe2Ph (0.072 g, 0.53 mmol)
was added and the mixture was stirred for 3 days at
room temperature. The solution was filtered, the solvent
was evaporated and the residue was washed with dieth-
ylether. The product was dissolved in dichloromethane
(10 mL) and chromatographed on a silica gel column
with dichloromethane and acetone as eluents. Crystals
obtained from the dichloromethane eluate were identical
with the cluster 1 and those from the acetone eluate were
crystallized from dichloromethane/diethylether to give
black crystals 2 in 19% yield. Anal. Calc. for C32H44
CoCl6P4Re3S4: C, 25.43; H, 2.93. Found: C, 25.36; H,
2.95%. UV–Vis (CH2Cl2): 520 nm (e 1259 Mꢁ1 cmꢁ1),
mator. Crystals were transferred to the goniostat where
they were cooled to ꢁ100 ꢁC for data collection. The
data were collected using 15 s frames with an omega
scan of 0.30ꢁ and corrected for Lorentz and polarization
effects. Data were treated by the Bruker SAINT soft-
ware and the structures were solved using SHELXTL
[15] and Fourier techniques. All hydrogen atoms were
placed in calculated positions and included in the final
cycles of refinement. Four solvent (C2H5)2O molecules
were found in a unit cell of 1. The final R1(wR2) indices
for 1 are 0.0345(0.0859) using 12,778 independent reflec-
tions. The final R1(wR2) indices for 2 are 0.0505(0.0790)
using 10,854 independent reflections. Crystallographic
data are given in Table 1.
1
768 nm (e 452 Mꢁ1 cmꢁ1). H NMR (d, CDCl3): 1.85,
1.87, 2.37 (d, Re–P(CH3)2(C6H5)), 1.92 (d, Co–P(CH3)2-
(C6H5)), 7.34–8.06 (m, P(CH3)2(C6H5)). 31P NMR (d,
CDCl3, 15% H3PO4): ꢁ24.80, ꢁ26.89, ꢁ30.92 (Re–
P(CH3)2(C6H5)), 33.10 (Co–P(CH3)2(C6H5)).
3. Results and discussion
3.1. Synthesis
2.1.3. Crystal structures of 1 and 2
Crystals suitable for X-ray crystallography were ob-
tained by recrystallization of the products from dichlo-
romethane and diethylether over a week. Data were
collected on a Bruker Smart APEX CCD system with
a sealed molybdenum source and graphite monochro-
Treatment of [(PPh3)2N][Re3(l3-S)(l-S)3Cl6(PMe2-
Ph)3] with anhydrous cobalt(II) chloride in dichloro-
methane in the presence of dimethylphenylphosphine
formed isomeric rhenium–cobalt mixed metal cluster
complexes, [Re3Co(l3-S)4Cl6(PMe2Ph)4] 1 and 2. 1H

N. Sakai, T. Saito / Polyhedron 23 (2004) 2611–2614
2613
and 31P NMR spectra showed the presence of two types
of cluster compounds in the products obtained from the
reaction at room temperature which were isolated by sil-
ica-gel column chromatography using dichloromethane
(compound 1) and acetone (compound 2) as eluents.
Only the isomer 1 was obtained from the reaction at
room temperature followed by reflux. Single crystals
were obtained by slow diffusion of diethyl ether onto
the dichloromethane solutions. Although coordination
of three bridging sulfurs in the trinuclear rhenium com-
plex to a hetero metal seems to be a facile reaction, only
nickel [5] and copper [16] derivatives have been prepared
and the present synthesis of the cobalt derivatives gives
some clue to the difficulty of the preparation.
P4
Co1
S1
Cl5
S2
S3
Cl3
Cl1
Re3
Re1
Re2
P3
Cl4
Cl6
3.2. Structures
P1
S4
P2
Cl2
3.2.1. NMR spectra
1H NMR spectra of 1 show methyl bands at 1.71 (d,
Re–P(CH3)2(C6H5)), 2.10 (dd, Co–P(CH3)2(C6H5)) and
2.28 (d, Re–P(CH3)2(C6H5)) ppm with the intensity ra-
tio of 3:2:3. The dimethylphenylphosphine coordinated
to three rhenium atoms gives two kinds of methyl sig-
nals due to different conformations of the groups. The
double doublet signals are assigned to the two methyl
groups of dimethylphenylphosphine coordinated to a
cobalt atom with slight difference of conformation.
31P NMR spectra of 1 show a band at ꢁ24.69 ppm
assignable to dimethylphenylphosphine coordinated to
rhenium and at 38.77 ppm assignable to the one coor-
Fig. 1. ORTEP representation of [Re3CoS4Cl6(PMe2Ph)4] 1 at the
50% probability level.
1
dinated to cobalt. H NMR spectra of 2 show methyl
bands at 1.85 (d, Re–P(CH3)2(C6H5)), 1.95 (dd, Re–
P(CH3)2(C6H5)), 2.00 (d, Co–P(CH3)2(C6H5)) and
2.45 (d, Re–P(CH3)2(C6H5)) with the intensity ratio
of 1:1:1:1. 31P NMR spectra of 2 show three bands
at ꢁ30.92, ꢁ26.89 and ꢁ24.80 ppm assignable to
dimethylphenylphosphine coordinated to rhenium and
a band at 33.10 ppm assignable to the one coordinated
P4
Cl1
Co1
P3
Cl3
Re1
1
to cobalt. H and 31P NMR spectra indicate the differ-
P1
ent conformations of the methyl groups of the dimeth-
ylphenylphosphine ligands with respect to the Re3
plane and l3-S atom. The structures (vide infra) of
the isomers indicate that the major isomer has three
phosphines directed opposite to l3-S and the minor
isomer contains a dimethylphenylphosphine in the
direction of l3-S.
Re3
Cl2
Re2
P2
Cl6
Cl4
Cl5
3.2.2. X-ray structures
The crystal of 1 contains a diethylether molecule as a
solvate molecule. Both the major product (compound 1)
and minor product (compound 2) have tetranuclear me-
tal frameworks with three rhenium and one cobalt atom
bonded together by four l3-S atoms (Figs. 1 and 2).
The Re–Re, Re–Co, Re–S and Co–S interatomic dis-
tances in the two isomers are not appreciably different
(Table 2).
Fig. 2. ORTEP representation of [Re3CoS4Cl6(PMe2Ph)4] 2 at the
50% probability level.
As the Re–Re distances are larger than Re–Co dis-
tances, the shapes of the cluster frameworks are flat-
tened tetrahedra. The tetranuclear cluster compounds

2614
N. Sakai, T. Saito / Polyhedron 23 (2004) 2611–2614
Table 2
nylphosphine ligand. Thus the rhenium atoms are
hexa-coordinate and cobalt tetra-coordinate if metal-
metal bonds are not taken into account.
˚
Selected interatomic distances (A) and bond angles (ꢁ) for 1 and 2
1
2
The present synthesis of mixed metal Re3Co sulfide
cluster complexes indicates that the conformation of
coordinated phosphines in the trinuclear rhenium clus-
ter complex is important to facilitate coordination of
l-S atoms to a hetero atom like cobalt. The fact that
the major product 1 contains three dimethylphenylphos-
phines in the opposite orientation to that in the starting
cluster compound necessitates the change of the confor-
mation of chlorine and phosphine ligands during the
reaction. It is conceivable that 1, obtained under reflux,
is thermodynamically more stable than 2.
Interatomic distances
Re(1)–Re(2)
Re(1)–Re(3)
Re(2)–Re(3)
Re(1)–Co(1)
Re(2)–Co(1)
Re(3)–Co(1)
Re–S (av)
2.7720(3)
2.7683(3)
2.7679(3)
2.5970(6)
2.5992(6)
2.6014(7)
2.324
2.7711(3)
2.7647(4)
2.7738(3)
2.5954(8)
2.5990(8)
2.6045(8)
2.322
Co–S (av)
Re–P (av)
2.148
2.553
2.144
2.550
Co–P
Re–Cl (av)
2.185
2.438
2.187
2.437
Bond angles
Re(3)–Re(1)–Re(2)
Co(1)–Re(2)–Re(3)
Re(1)–Co(1)–Re(3)
Co(1)–S(1)–Re(1)
Re(2)–S(1)–Re(1)
Re(1)–S(4)–Re(2)
P(1)–Re(1)–Re(3)
P(1)–Re(1)–Re(2)
P(4)–Co(1)–Re(3)
P(4)–Co(1)–Re(1)
Cl(1)–Re(1)–Cl(2)
P(1)–Re(1)–Cl(1)
P(1)–Re(1)–Cl(2)
59.947(6)
57.882(15)
64.353(15)
70.68(4)
60.140(9)
57.884(19)
64.238(19)
71.14(5)
4. Supplementary material
73.22(4)
73.01(3)
73.25(4)
73.24(4)
All the crystallographic data of 1 and 2 have been
deposited at the Cambridge Crystallographic Data Cen-
tre as supplementary publication Nos. CCDC 232748
and 232749 for 1 and 2, respectively. These data can
be obtained free of charge via www.ccdc.cam.ac.uk/
101.32(3)
143.04(3)
141.69(5)
136.27(4)
83.96(4)
146.48(4)
101.79(4)
145.96(6)
137.94(6)
84.83(8)
conts/retrieving.html,
by
emailing
data_re-
78.41(4)
79.70(4)
78.53(6)
80.20(5)
quest@ccdc.cam.ac.uk, or by contacting The Cambridge
Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: +44-1223-336-033.
1 and 2 have 60 valence electrons counted on the basis of
neutral atoms (Re7, Co9, S4, Cl1, P2) and the number is
common among tetrahedral cluster compounds [17].
References
˚
˚
The average Re–Re (2.769 A) and Re–Co (2.599 A) dis-
tances are close enough to invoke Re–Re and Re–Co
metal–metal bonding interactions. They are a little
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˚
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