Insertion of a phospholide unit into a metal-metal bond: Synthesis and X-ray structure of [Ru3(CO)9(μ:η1: η5-PC4H2Me2)(η1- C6H5)]

Article abstract of DOI:10.1016/j.ica.2012.01.033

The reaction of [Ru₃(CO)₁₂] with 3,4-dimethyl-1- phenylphosphole under mild conditions affords three derivatives which were identified by means of spectroscopic methods as the substitution compounds [Ru₃(CO)_12-x(PhPC₄H ₂Me₂)_x] (x = 1, 2, 3) in which the phosphole ligand acts as a tertiary phosphine bonded through the phosphorus atom. Thermolysis of the monosubstituted [Ru₃(CO)₁₁(PhPC ₄H₂Me₂)] in cyclohexane affords two new clusters, characterised as [Ru₃(CO)₉(μ³: η²:η²:η²-PhPC₄H ₂Me₂)] and [Ru₃(CO)₉(μ: η¹:η⁵-PC₄H₂Me ₂)(η¹-C₆H₅)], where the phosphole ring behaves as a six- and seven-electron donor ligand respectively. The reaction with [Os₃H₂(CO)₁₀] gives the new species [Os₃(μ-H)(CO)₉(μ³: η¹:η¹:η²-PhPC₄H ₃Me₂)] in which the ligand behaves as a five-electron donor.

Full text of DOI:10.1016/j.ica.2012.01.033

Inorganica Chimica Acta 392 (2012) 241–245
Contents lists available at SciVerse ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
Insertion of a phospholide unit into a metal–metal bond: Synthesis and X-ray
structure of [Ru3(CO)9(l: :g g
g1 5-PC4H2Me2)( 1-C6H5)]
⇑
Alejandro J. Arce, Ysaura De Sanctis, María Cristina Goite, Ruben Machado, Yomaira Otero , Teresa Gonzalez
Centro de Química, Instituto Venezolano de Investigaciones Científicas (IVIC), Apartado 21827, Caracas 1020-A, Venezuela
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of [Ru3(CO)12] with 3,4-dimethyl-1-phenylphosphole under mild conditions affords three
derivatives which were identified by means of spectroscopic methods as the substitution compounds
[Ru3(CO)12Àx(PhPC4H2Me2)x] (x = 1, 2, 3) in which the phosphole ligand acts as a tertiary phosphine
bonded through the phosphorus atom. Thermolysis of the monosubstituted [Ru3(CO)11(PhPC4H2Me2)]
Received 31 October 2011
Received in revised form 13 January 2012
Accepted 18 January 2012
Available online 2 February 2012
in cyclohexane affords two new clusters, characterised as [Ru3(CO)9(l3
:
g2
:
g2
:
g
2-PhPC4H2Me2)]
and [Ru3(CO)9(
l
:
g1
:
g
5-PC4H2Me2)(
g
1-C6H5)], where the phosphole ring behaves as a six- and seven-
Keywords:
electron donor ligand respectively. The reaction with [Os3H2(CO)10
] gives the new species
Triruthenium clusters
Triosmium clusters
Phospholes
[Os3(l
-H)(CO)9(l3
:
g1
:
g1
:
g
2-PhPC4H3Me2)] in which the ligand behaves as a five-electron donor.
Ó 2012 Elsevier B.V. All rights reserved.
Phospholide
1. Introduction
2. Experimental
Five-membered rings containing phosphorus atoms have been
synthesised since 1959, however nearly 75% of all known rings of
this kind were prepared in the last 20 years. Regarding organome-
tallic chemistry, phospholes offer a wide versatility of coordination
modes and reactivity patterns [1]. Structural diversity of their tran-
sition metal complexes has been facilitated by the ability of the
2.1. Ruthenium
A solution of [Ru3(CO)12] (250 mg, 0.391 mmol) and 3,4-dim-
ethylphenylphosphole [4] (73.5 mg, 0.391 mmol) in dried cyclo-
hexane (40 mL) was taken to reflux under nitrogen for 40 min.
After evaporation of the solvent, TLC (SiO2) of the orange-yellow
residue (eluant pentane:dichloromethane, 4:1 v:v) gave five main
bands: [Ru3(CO)11(PhPC4H2Me2)] (1) was obtained as pale-yellow
crystals from n-hexane (25% yield); [Ru3(CO)10(PhPC4H2Me2)2]
(2) was isolated as
(PhPC4H2Me2)3] (3) (12% yield) was obtained as orange crystals
from cyclohexane; [Ru3(CO)9(l3 2-PhPC4H2Me2)] (4) (7%
yield) and [Ru3(CO)9(
5-PC4H2Me2)( 1-C6H5)] (5) (7% yield)
were both isolated as yellow solids.
Thermolysis of 1 (75 mg) in 50 mL of dried cyclohexane under
reflux under nitrogen for 3 h gave two yellow bands (eluant pen-
tane:dichloromethane, 10:1 v:v). The first one gave unreacted 1
(35% yield), an the other one gave compound 5 (60% yield), from
which pale yellow crystals were obtained from slow evaporation
of a cyclohexane solution.
phospholyls to coordinate metals in
r, p, and mixed bonding
modes. The coordination chemistry of phosphole is still a fertile
area for further research and many of the complexes now known
have obvious potential as catalytic systems and multifunctional
materials for OLEDs [2].
In an earlier work we have shown that phospholes react with
triosmium carbonyl clusters [3] giving rise not only to simple sub-
stitution complexes but also to a series of derivatives containing
ring-opened ligands. In this paper we describe the synthesis and
spectroscopic characterisation of the products from the reaction
of ruthenium and osmium carbonyl clusters with 3,4-dimethyl-1-
phenylphosphole and to the best of our knowledge, the first exam-
ple of the insertion of a phospholide unit into a Ru–Ru bond is
reported.
a yellow solid (18% yield); [Ru3(CO)9
: : :g
g2 g2
l:
g1
:g
g
2.2. Osmium
A solution of [Os3(l-H)2(CO)10] (250 mg, 0.293 mmol) and 3,4-
dimethylphenylphosphole (55.1 mg, 0.293 mmol) in dried cyclo-
hexane (40 mL) was taken to reflux under nitrogen for 6 h.
After evaporation of the solvent, TLC (SiO2) of the yellow residue
⇑
Corresponding author.
E-mail address: ysantis@ivic.gob.ve (Y. De Sanctis).
0020-1693/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2012.01.033

242
A.J. Arce et al. / Inorganica Chimica Acta 392 (2012) 241–245
(eluant pentane) gave one main band: [Os3(CO)9(
H)(l3 2-PhPC4H3Me2)] (6) was obtained as yellow crystals
from n-hexane (35% yield).
l
-
and as shown by X-ray crystal structure determinations [7] the
phosphole ligand is coordinated only through the phosphorus
atom. As in the case of other tertiary phosphine analogues,
only one isomer of the decacarbonyl cluster is formed, the 1,2-
[Ru3(CO)10(PhPC4H2Me2)2] (2), as no evidence for the 1,1-isomer
was obtained. The 31P NMR sprectrum of 2 shows two equal-inten-
sity singlets for the unsymmetrycal isomer with non-equivalent
phosphole ligands at d = 26.4 and 26.1 ppm (Table 1). The trisubsti-
tuted derivative 3 shows only one singlet in the 31P NMR sprec-
trum as expected for three equivalent phosphorus atoms.
A single crystal X-ray structure determination was carried out
for cluster 3, its ORTEP diagram is shown in Fig. 1 and selected
bond lengths and angles are shown in Table 2. The structure con-
sists of a triangular Ru3 core with three nearly equal Ru–Ru bonds
showing an average length of 2.858 Å as observed for [Ru3(-
CO)9(PPh3)3] [8], in which the three phosphole ligands take up
:
g1 g1
: :g
1H, 13C and 31P NMR spectra were recorded on Bruker Avance
300 and 500 MHz spectrometers and IR spectra were recorded on
a Nicolet 5DXC.
3. Results and discussion
The substitution compounds [Ru3(CO)12Àx(PhPC4H2Me2)x]
(x = 1, 2 or 3; 1, 2 and 3, respectively) are obtained under very mild
reaction conditions as well as minor quantities of [Ru3(-
CO)9(l3
PC4H2Me2)(
: : :g l: : -
g2 g2 2-PhPC4H2Me2)] (4) and [Ru3(CO)9( g1 g5
g
1-C6H5)] (5) (Scheme 1), easily separated by thin layer
chromatography on SiO2. Compounds 1–3 are closely related spec-
troscopically to their known tertiary phosphine analogues [5,6]
Table 1
Spectroscopic data for compounds 1–6.
Compound
m
(CO)a (cmÀ1
)
NMRb (d, ppm)
J (Hz)
31P{1H}
13C{1H}
1H
[Ru3(CO)11(PhPC4H2Me2)] (1)
2095 s
2042 s
2028 s
2012 s
1995 w
1985 m
1960 w
25.8 s
150.2 d, C2
132.8 d, C4
130.4 d, C5
130.3 s, C7
128.9 d, C6
127.6 d, C1
17.3 d, C3
7.49 m, H5
7.41 m, H6, H7
6.54 d, H1
P–H1 36.5
P–C1 48.7
P–C2 10.2
P–C3 12.5
P–C4 48.7
P–C5 10.7
P–C6 10.7
2.07 s, Me
[Ru3(CO)10(PhPC4H2Me2)2] (2)
2071 w
2018 s
2002 w
1990 m
1973 w
26.4 s
26.1 s
149.3 d, C2
130.4 d, C5
129.8 d, C4
128.7 s, C6
128.6 s, C7
128.3 d, C1
17.2 d, C3
7.50 m, H5
7.37 m, H6, H7
6.50 d, H1
P–H1 36.2
P–Me 5.5
P–C1 47.0
P–C2 10.1
P–C3 12.1
P–C4 10.0
P–C5 10.6
2.04 d, Me
[Ru3(CO)9(PhPC4H2Me2)3] (3)
2043 w
1983 s
1971 s
1949 m
26.8 s
28.9 s
88.6 s
148.4 d, C2
134.4 d, C4
130.5 d, C5
129.3 s, C7
129.0 d, C1
128.4 d, C6
17.2 d, C3
142.6 d, C4
130.3 s, C7
129.1 d, C6
127.3 d, C5
92.7 d, C2
32.6 d, C1
15.4 d, C3
145.5 d, C5
142.8 d, C4
127.8 s, C6
123.9 s, C7
102.0 d, C2a
100.6 d, C2b
60.0 d, C1a
57.7 d, C1b
15.6 d, C3a
15.4 d, C3b
7.48 m, H5
7.32 m, H6, H7
6.41 d, H1
P–H1 35.7
P–C1 45.3
P–C2 9.8
P–C4 44.9
P–C5 10.7
P–C6 10.5
1.99 s, Me
P–C3 12.1
[Ru3(CO)9(l3
:
g2
:
g2
:g
2-PhPC4H2Me2)] (4)
2062 w
2022 s
1996 m
1980 m
1924 w
7.56 m, Ph
2.34 s, Me
2.07 d, H1
P–H1 31.2
P–C1 52.4
P–C2 10.2
P–C3 6.2
P–C4 9.2
P–C5 14.4
P–C6 10.6
[Ru3(CO)9(
l:
g1
:
g
5-PC4H2Me2)(
g
1-C6H5)] (5)
2108 s
2068 s
2042 s
2026 s
2019 m
1998 m
1986 w
1950 s
1918 w
7.38 d, H5
6.86 dd, H6
6.79 d, H7
2.95 d, H1a
2.79 d, H1b
2.42 s, Mea
2.41 s, Meb
H5–H6 7.3
H6–H7 7.2
P–H1a 30.7
P–H1b 33.9
P–C1a 17.4
P–C1b 19.5
P–C2a 4.3
P–C2b 5.6
P–C3a 6.3
P– C3b 6.6
P–C4 13.2
P–C5 5.9
[Os3(CO)9(
l
-H)(l3
:
g1
:
g1
:
g
2-PhPC4H3Me2)] (6)
2082 s
2053 s
2023 s
2011 m
1986 m
1975 w
1965 w
1949 w
À23.5 s
139.5 d, C4
131.0 d, C7
129.1 d, C6
128.1 d, C5
123.0 d, C2a
66.1 d, C2b
39.4 d, C1a
29.4 s, C3a
18.8 d, C3b
À12.5 d, C1b
7.44 m, H6, H7
7.34 m, H5
3.73 dq, H1b
3.57 d, H1a
2.41 s, Mea
2.33 s, H2
H1b–Meb 6.8
P–H1a 23.9
P–H1b 37.9
P–H(Os) 12.7
P–C1a 48.0
P–C1b 14.8
P–C2a 16.2
P–C2b 4.3
P–C3b 6.8
P–C4 6.0
P–C5 11.3
P–C6 9.0
P–C7 2.4
0.79 d, Meb
À17.9 d, OsH
a
C6H12
CDCl3.
.
b

A.J. Arce et al. / Inorganica Chimica Acta 392 (2012) 241–245
243
H3C
C6H12, ref.
40 min.
[Ru3(CO)12
]
+
P
H3C
[Ru3(CO)11(PhPC4H2Me2)] [Ru3(CO)10(PhPC4H2Me2)2] [Ru3(CO)9(PhPC4H2Me2)3]
1
2
3
C6H12, ref.
3 h
H3C
H3C
H3C
P
P
Ru(CO)3
H3C
Ru
(CO)3
+
2
-
(CO)2 Ru
(CO)
Ru
(CO)
3Ru
Ru(CO)4
3
4
5
Scheme 1.
Fig. 1. Molecular structure of the cluster [Ru3(CO)9(PhPC4H2Me2)3] (3).
positions that are as far apart as possible, each equatorially bonded
to one ruthenium atom. The nine carbonyl ligands are terminal, six
occupying axial positions while the other three are alternated with
the phosphole ligands in one of the two equatorial positions for
each ruthenium atom. The Ru–P distances are similar to the ones
found for analogue triruthenium derivatives [8] with an average
bond length of 2.321 Å.
Table 2
Selected bond lengths (Å) and angles (°) for compound 3.
Ru1–Ru2
Ru1–Ru3
Ru2–Ru3
2.8599 (5)
2.8680 (6)
2.8448 (6)
Ru1–P1
Ru2–P2
Ru3–P3
2.3226 (11)
2.3160 (10)
2.3233 (12)
Ru2–Ru1–Ru3
59.557 (14)
174.60 (18)
91.1 (2)
93.2 (2)
60.363 (15)
172.17 (19)
C21A–Ru2–C23A
C22A–Ru2–C23A
Ru1–Ru3–Ru2
C31A–Ru3–C32A
C31A–Ru3–C33A
C32A–Ru3–C33A
95.08 (19)
92.50 (18)
60.079 (14)
95.05 (18)
171.62 (18)
93.07 (18)
C11A–Ru1–C12A
C13A–Ru1–C12A
C11A–Ru1–C13A
Ru1–Ru2–Ru3
Two new species were also obtained in low yields, for which
their IR spectra in the carbonyl stretching region indicate the pres-
ence of nonacarbonyl compounds (Table 1). These clusters were
C21A–Ru2–C22A
characterised as [Ru3(CO)9(l3 g2 g2 2-PhPC4H2Me2)] (4), show-
: : :g

244
A.J. Arce et al. / Inorganica Chimica Acta 392 (2012) 241–245
Fig. 2. Molecular structure of the cluster [Ru3(CO)9(l: :g g
g1 5-PC4H2Me2)( 1-C6H5)] (5).
ing an IR similar to the one found for [Os3(CO)9(C6H6)] [9] and
[Ru3(CO)9(
5-PC4H2Me2)( 1-C6H5)] (5) for which was ob-
served an IR pattern resembling the one for [Ru3(CO)10(l: : -
g1 g5
l:
g1
:g
g
Table 3
Selected bond lengths (Å) and angles (°) for compound 5.
C5H4)], obtained from the reaction of [Ru3(CO)12] and diazocyclo-
pentadiene (C5H4N2) [10].
Ru1–Ru2
Ru2–Ru3
Ru1–P1
Ru3–P1
Ru1–C1
Ru1–C2
Ru1–C3
2.9365 (9)
2.9855 (8)
2.4864 (13)
2.2749 (13)
2.244 (4)
Ru1–C4
P1–C1
P1–C4
C1–C2
C2–C3
C3–C4
2.243 (4)
1.777 (4)
1.769 (5)
1.422 (6)
1.432 (6)
1.411 (6)
The 1H NMR spectrum of 4 (Table 1) is similar to that of the rhe-
nium nonacarbonyl [Re3(CO)9(PhPC4H2Me2)] isolated from the
reaction of [Re2(CO)8(MeCN2)] and 3,4-dimethyl-1-phenylphosp-
hole [7], where in both cases the ligand acts as a six-electron do-
nor. We were unable to obtain suitable crystals for the X-ray
diffraction analysis of 4, however based on the spectroscopic evi-
dence and comparison with its osmium analogue [Os3(CO)9
(PhPC4H2Me2)] [7] the structure shown for 4 in Scheme 1 is the
most likely.
2.225 (4)
2.234 (4)
Ru2–Ru1–P1
Ru1–Ru2–Ru3
Ru2–Ru3–P1
P1–Ru3–C7
P1–Ru3–C31
Ru1–P1–Ru3
Ru1–P1–C1
56.67 (3)
100.73 (2)
55.93 (3)
88.38 (11)
159.08 (17)
146.59 (5)
60.83 (13)
Ru1–P1–C4
Ru3–P1–C4
C1–P1–C4
P1–C1–C2
P1–C4–C3
C1–C2–C3
C2–C3–C4
60.87 (15)
131.89 (16)
89.3 (2)
112.8 (3)
113.6 (3)
112.1 (4)
111.9 (4)
Thermal treatment of [Ru3(CO)11(PhPC4H2Me2)] (1) for 3 h in
cyclohexane leads in very high yield to cluster 5 (60%). Its single
crystal X-ray structure determination (Fig. 2, Table 3) revealed
the structural type of an open Ru3 cluster with two metal–metal
cies as expected for an anionic Ru3 species was not observed for 5,
so an eight-electron donating ligand can not be considered in this
case, which makes compound 5 a 50-electron cluster. The Ru3-P
bonds bridged by a (g1 5-PC4H2Me2) unit, obtained by double
:g
decarbonylation of 1, cleavage of a Ru–Ru bond and insertion of
a Ru(CO)3 unit into the P-Aryl bond, where the PhPC4H2Me2 moiety
is coordinated as a phospholide to two metal atoms acting as a se-
ven-electron donor. Shift to higher values of the IR v(CO) frequen-
bond length in 5 is sligthly shorter than that of the Ru–P(g1
-
phosphole) bond for 3 (2.275 Å versus 2.321 Å, respectively); the
Ru–phosphole
p
-interaction involved in the
g
5-coordination in 5
H3C
P
H3C
H3C
C6H12, ref.
6 h
[Os3(µ-H)2(CO)10
]
+
P
-
H
Os
H3C
-
(CO)3
(CO)
Os
3
Os
(CO)3
6
Scheme 2.

A.J. Arce et al. / Inorganica Chimica Acta 392 (2012) 241–245
245
mean Ru–Cn bond distance (n = 2–5) of 2.231(7) Å for the cyclopen-
tadienyl derivative.
The reaction of the unsaturated triosmium cluster [Os3(
H)2(CO)10 with 3,4-dimethyl-1-phenylphosphole gave one
main compound characterised as [Os3(CO)9(
-H)(l3
l-
]
l
: : : -
g1 g1 g2
PhPC4H3Me2)] (6) (Scheme 2) where the phosphole ligand lies over
the plane of the metal skeleton in a partially hydrogenated form,
behaving as a five-electron donor. The compound was character-
ised by IR, 31P, 1H and 13C NMR and X-ray studies, and its structure
is shown in Fig. 3. The C3–C4 bond distance of 1.535(13) Å (Table 4)
is characteristic of a simple bond while C1–C2 = 1.396(1) Å, corre-
sponds to a C–C double bond distance.
In conclusion we have found that [Ru3(CO)9(
l: : -
g1 g5
PC4H2Me2)(
g
1-C6H5)] (5) is the first example of a phospholide unit
inserted into a metal–metal bond. This procedure opens up the
possibility for a facile access to new ruthenium and maybe other
metal complexes with (l: :g
g1 5-PC4R4) units as bridging ligands.
Acknowledgements
We thank FONACIT for Project G-20050000447.
Fig. 3. Molecular structure of the cluster [Os3(CO)9(
PhPC4H3Me2)] (6).
l : : : -
-H)(l3 g1 g1 g2
Appendix A. Supplementary material
CCDC 7308, 10908 and 13908 contain the supplementary crys-
tallographic data for compounds 3, 5 and 6, respectively. These
data can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.ica.2012.01.033.
Table 4
Selected bond lengths (Å) and angles (°) for compound 6.
Os1–Os2
Os1–Os3
Os2–Os3
Os2–P1
Os1–C4
Os3–C1
2.9767 (14)
2.8517 (11)
2.9053 (16)
2.338 (2)
2.207 (8)
2.331 (8)
Os3–C2
P1–C1
P1–C4
C1–C2
C2–C3
C3–C4
2.544 (9)
1.776 (9)
1.810 (10)
1.396 (13)
1.507 (14)
1.535 (13)
References
Os2–Os1–Os3
Os3–Os1–C4
Os1–Os2–Os3
Os1–Os2–P1
Os3–Os2– P1
Os1–Os3–Os2
Os1–Os3–C1
59.75 (3)
78.9 (2)
Os2–Os3–C1
Os2–Os3–C2
C1–P1–C4
P1–C1–C2
P1–C4–C3
C1–C2–C3
C2–C3–C4
76.4(2)
[1] F. Mathey (ed.), Phosphorus–carbon heterocyclic chemistry: the rise of a new
domain, Pergamon, 2001.
[2] J. Crassous, R. Réau, Dalton Trans. (2008) 6865.
[3] A.J. Deeming, N.I. Powell, A.J. Arce, Y. De Sanctis, J. Manzur, J. Chem. Soc.,
Dalton Trans. (1991) 3381.
[4] A. Breque, F. Mathey, P. Savignac, Synthesis (1981) 983.
[5] A.J. Deeming, Adv. Organomet. Chem. 26 (1986) 1.
[6] A.J. Deeming, B.F.G. Johnson, J. Lewis, J. Chem. Soc. A (1970) 987.
[7] A. Arce, Y. De Sanctis, R. Machado, Y. Otero, unpublished results.
[8] Z.R. Bell, R.H. Laye, M.D. Ward, Acta Crystallogr., Sect. E58 (2002) m165.
[9] M.D. Gómez-Sal, B.F.G. Johnson, J. Lewis, P.R. Raithby, A.H. Wright, Chem.
Commun. (1985) 1682.
101.3(2)
93.9 (4)
110.1 (7)
105.3 (6)
114.6 (8)
106.8 (7)
57.99 (2)
70.27 (6)
69.65 (6)
62.26 (3)
93.6 (2)
is similar to the one observed for the C5H4N2 derivative [Ru3(-
CO)10
5-C5H4)] [10] as are the values obtained for the mean
Ru–Cn(phosphole) bond lengths in 5 (2.237(4) Å) compared to the
(l: :g
g1
[10] A.J. Arce, Y. De Sanctis, J. Manzur, M.V. Capparelli, Angew. Chem., Int. Ed. Engl.
33 (1994) 2193.