A new series of iodocarbonyl ruthenium (II) complexes with unsymmetrical phosphine-phosphine sulfide ligands of the type Ph2P(CH 2)nP(S)Ph2, n = 1-4: Isolation and structural investigation

Article abstract of DOI:10.1016/j.ica.2005.06.051

Hexa-coordinated chelate complex cis-[Ru(CO)₂I ₂(P∩S)] (1a) {P∩S = η²-(P,S)-coordinated} and penta-coordinated non-chelate complexes cis-[Ru(CO)₂I ₂(P～S)] (1b-d) {P～S = η¹-(P)-coordinated} are produced by the reaction of polymeric [Ru(CO)₂I₂] _n with equimolar quantity of the ligands Ph₂P(CH ₂)_nP(S)Ph₂ {n = 1(a), 2(b), 3(c), 4(d)} in dichloromethane at room temperature. The bidentate nature of the ligand a in the complex 1a leads to the formation of five-membered chelate ring which confers extra stability to the complex. On the other hand, 1:2 (Ru:L) molar ratio reaction affords the hexa-coordinated non-chelate complexes cis,cis,trans- [Ru(CO)₂I₂(P～S)₂] (2a-d) irrespective of the ligands. All the complexes show two equally intense terminal ν(CO) bands in the range 2028-2103 cm^-1. The ν(PS) band of complex 1a occurs 23 cm^-1 lower region compared to the corresponding free ligand suggesting chelation via metal-sulfur bond formation. X-ray crystallography reveals that the Ru(II) atom occupies the center of a slightly distorted octahedral geometry. The complexes have also been characterized by elemental analysis, ¹H, ¹³C and ³¹P NMR spectroscopy.

Full text of DOI:10.1016/j.ica.2005.06.051

Inorganica Chimica Acta 359 (2006) 877–882
www.elsevier.com/locate/ica
A new series of iodocarbonyl ruthenium (II) complexes
with unsymmetrical phosphine–phosphine sulfide ligands
of the type Ph2P(CH2)nP(S)Ph2, n = 1–4:
Isolation and structural investigation
a,
a
b
b
Dipak Kumar Dutta *, Pratap Chutia , J. Derek Woollins , Alexandra M.Z. Slawin
a
Material Science Division, Regional Research Laboratory (CSIR), Jorhat 785006, Assam, India
b
Department of Chemistry, University of St. Andrews, St. Andrews, KY 16 9ST, UK
Received 6 April 2005; received in revised form 21 June 2005; accepted 28 June 2005
Available online 8 August 2005
Ruthenium and Osmium Chemistry Topical Issue
Abstract
Hexa-coordinated chelate complex cis-[Ru(CO)2I2(P\S)] (1a) {P\S = g2-(P,S)-coordinated} and penta-coordinated non-chelate
complexes cis-[Ru(CO)2I2(PꢀS)] (1b–d) {PꢀS = g1-(P)-coordinated} are produced by the reaction of polymeric [Ru(CO)2I2]n with
equimolar quantity of the ligands Ph2P(CH2)nP(S)Ph2 {n = 1(a),2(b),3(c),4(d)} in dichloromethane at room temperature. The
bidentate nature of the ligand a in the complex 1a leads to the formation of five-membered chelate ring which confers extra stability
to the complex. On the other hand, 1:2 (Ru:L) molar ratio reaction affords the hexa-coordinated non-chelate complexes cis,cis,trans-
[Ru(CO)2I2(PꢀS)2] (2a–d) irrespective of the ligands. All the complexes show two equally intense terminal m(CO) bands in the range
2028–2103 cmꢁ1. The m(PS) band of complex 1a occurs 23 cmꢁ1 lower region compared to the corresponding free ligand suggesting
chelation via metal–sulfur bond formation. X-ray crystallography reveals that the Ru(II) atom occupies the center of a slightly dis-
torted octahedral geometry. The complexes have also been characterized by elemental analysis, 1H, 13C and 31P NMR spectroscopy.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Ruthenium (II) carbonyl complexes; Unsymmetrical phosphine–phosphine sulfide; Single crystal X-ray structure; Distorted octahedral
geometry; Steric effect; IR and NMR spectroscopy
1. Introduction
been mainly concentrated on the complexes with X =
O,S,Se and n = 1–2. Rhodium and ruthenium metal
carbonyl complexes of bis-diphenylphosphino monoch-
alcogenides, Ph2P(CH2)nP(X)Ph2; X = O,S,Se; n = 1–2
are of special interest because of their versatile applica-
tion in homogeneous catalysis [1–3]. These type of li-
gands have become of increasing interest because of
their dual nature in coordination with the metal
center. They exhibit [P]-bonded unidentate coordination
or [P,X]-bonded chelating coordination mode, depend-
ing on the metal center and its environments. They have
the potential for strong bonding between the soft
There is currently much interest in the synthesis,
characterization and structural investigation of transi-
tion metal complexes containing different types of phos-
phine based mono- and di-chalcogenide ligands like
Ph2P(CH2)nP(X)Ph2, Ph2As(CH2)nP(X)Ph2, Ph2PNHP-
(X)Ph2 and Ph2As(X)(CH2)nP(X)Ph2 [1–12]. Work has
*
Corresponding author. Tel.: +91 376 2370081/2370147; fax: +91
376 2370011.
E-mail address: dipakkrdutta@yahoo.com (D.K. Dutta).
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.06.051

878
D.K. Dutta et al. / Inorganica Chimica Acta 359 (2006) 877–882
phosphorus atom and a soft metal atom and weaker
bonding between the metal and the chalcogen atom
and chelate formation gives the extra stability to the me-
tal complex. The relatively labile metal–chalcogen bond
can be cleaved reversibly to generate a free coordination
site for incoming stronger binding ligands or substrates
[13] which facilitates catalytic activity of the catalyst. As
for example, the P,O chelate complex, [RhCl(CO)-
{Ph2PCH2CH2P(O)Ph2}], catalyses carbonylation of
methanol [1]. The mechanism for this catalytic process
may involve opening–closing system. Recently, there
have been a few reports on some ruthenium chloro-car-
bonyl complexes derived from [Ru(CO)2Cl2]n and
Ph2P(CH2)nP(S)Ph2, n = 1–4 [14–16], but to the best of
our knowledge, no ruthenium iodo-carbonyl complex
has so far been reported with these types of unsymmet-
rical phosphine–phosphine monochalcogenide ligands
despite the chemistry of such complexes being as poten-
tially important and interesting as that of chloro-
complexes.
tive to SiMe4 and 85% H3PO4 as internal and external
standard, respectively, using CDCl3 and d6-acetone as
solvent.
2.3. Synthesis of complexes [Ru(CO)2I2(P\S)] (1a)
and [Ru(CO)2I2(PꢀS)] (1b–d)
0.024 mmol of [Ru(CO)2I2]n was dissolved in 10 cm3
dichloromethane and to this 0.024 mmol of correspond-
ing ligands a–d in 10 cm3 dichloromethane was added.
The reaction mixture was stirred at room temperature
for about 3 h and the solvent was evaporated under vac-
uum to produce a yellow compound. The compound
was washed with diethyl ether and recrystallized from
dichloromethane solution.
2.4. Synthesis of complexes [Ru(CO)2 I2(PꢀS)2]
(2a–d)
To a 10 cm3 dichloromethane solution of [Ru
(CO)2I2]n (0.024 mmol), 0.049 mmol of corresponding li-
gands a–d in 10 cm3 dichloromethane was added. A yel-
low compound was obtained following the same
reaction condition used for the complexes 1a–d. After
washing with diethyl ether the complexes were recrystal-
lized from dichloromethane solution.
In this paper, we present the synthetic details, charac-
terization data and structural investigation of some new
ruthenium (II) iodo-carbonyl complexes containing the
ligands Ph2P(CH2)nP(S)Ph2, n = 1–4. The molecular
structure of one of the synthesized complexes [Ru(CO)2-
I2(P\S)] (P\S = g2-P,S-coordinated Ph2PCH2P(S)Ph2)
established by single crystal X-ray diffraction study is
also reported.
2.5. Single crystal X-ray crystallographic data collection
and refinements of the structure
2. Experimental
A crystal of the complex 1a suitable for X-ray crystal-
lographic analysis was developed from a CH2Cl2–hex-
ane solution. Data collection was performed using a
Bruker SMART diffractometer, full sphere of data with
0.3ꢁ slices, room temperature, Mo Ka radiation and
empirical absorption corrections. All non-hydrogen
atoms were refined anisotropically with the hydrogen
atoms being refined in idealized geometries. The struc-
ture refinements were done by full matrix least square
on F2 using SHELXTL 97 computer program [20]. The
crystal data and structure refinement for the complex
are listed in Table 1.
2.1. Materials
All the solvents used were distilled under nitrogen
prior to use. Iodides were analyzed by standard analyt-
ical method [17]. RuCl3 Æ3H2O was purchased from M/s
Arrora Matthey Ltd., Kolkata, India. Analytically pure
Ph2P(CH2)nPPh2 (n = 1–4) and elemental sulfur were
purchased from M/s Aldrich, USA and used without
further purification. The ligands, Ph2P(CH2)nP(S)Ph2
were prepared by refluxing a solution of Ph2P(CH2)n-
PPh2 in benzene with one molar equivalent of elemental
sulfur for 3 h under nitrogen and purified by chromato-
graphic techniques [15]. The starting complex [Ru(CO)2-
I2]n was prepared by the literature methods [18,19].
3. Results and discussion
The polymeric complex [Ru(CO)2I2]n reacts with
equimolar quantity of the ligand a by cleavage of the
iodo bridge to afford a hexa-coordinated g2-P,S bonded
complex [Ru(CO)2I2(P\S)] (1a) (Scheme 1). This molec-
ular composition of the complex is well supported by the
elemental analysis data (Table 2). The complex was iso-
lated as stable crystalline solid. The solid-state IR spec-
tra of the complex 1a in KBr plates show two equally
intense m(CO) bands at 2098 and 2030 cmꢁ1 attributing
the two terminal carbonyl groups are cis to one another
2.2. Instrumentation
FT-IR spectra of range 4000–400 and 400–200 cmꢁ1
were recorded using Perkin–Elmer 2000 and Perkin–El-
mer 883 spectrophotometer, respectively, in KBr disc.
Carbon and hydrogen analyses were done on a Per-
kin–Elmer 2400 elemental analyzer. NMR data were
recorded on a Bruker DPX 300 MHz spectrometer and
1
the H and 31P NMR chemical shifts were quoted rela-

D.K. Dutta et al. / Inorganica Chimica Acta 359 (2006) 877–882
879
Table 1
equivalent because in the five-membered chelate ring
methylene protons are expected to be above and below
the plane containing the metal ion and the two phospho-
rus atoms [23]. Each of the methylene protons appear
separately as doublet of double doublet (ddd) centered
at 3.89 and 4.77 ppm due to coupling with two phospho-
rus atoms and the other H which are matching well with
the related complexes of the same ligand reported by
Gonsalvi et al. [24]. The 31P NMR spectra (Table 3)
exhibit two distinct doublet resonances corresponding
to the two different phosphorus atoms. The pentavalent
phosphorus atom (PB) bonded to the sulfur resonates at
high field (d 53.6 ppm) than the tertiary phosphorus (PA)
bonded to the metal (d 61.6 ppm) [25]. As compared to
the free ligand, the PA and PB atom show a down field
shift of 84.3 and 8.4 ppm, respectively, which further
corroborates the chelation in complex 1a. In the 13C
spectra, only one signal for the two inequivalent car-
bonyl carbons is appeared as broad singlet at d
186 ppm (Table 4), which indicates that the other CO
peak is merged and therefore does not appear sepa-
rately. One doublet of doublet peak is observed at d
34.0 ppm for the methylene carbon due to coupling with
the two non-equivalent phosphorus atoms. The phenyl
carbons are found in the range d 128.61–135.25 ppm.
Unlike to the ligand a, the reaction of the ligands b–d
with [Ru(CO)2I2]n in one molar equivalent ratio gives
five-coordinate g1-P bonded complexes of the type
[Ru(CO)2I2(PꢀS)] (1b–d) (Scheme 1). The non-chelating
mode of the ligands b–d in these complexes is favoured
over chelating mode because chelation leads to forma-
tion of six, seven and eight member ring which are
unfavourable due to high ring strain. Similar to the com-
plex 1a, the m(CO) bands for the two cis terminal
carbonyl groups are observed in the range 2033–
2103 cmꢁ1 (Table 3). The m(PS) band occurs almost in
the same position as that of corresponding free ligands
which is good agreement with the g1-P coordination
nature of the ligands. The 1H NMR spectra of the com-
plexes 1b–d show the characteristic resonances for the
methylene and phenylic protons. As the complex 1a,
Crystal data and structure refinement of the complex 1a
Empirical formula
Formula weight
Temperature (K)
Wave length (A)
Crystal system
Space group
C27H22I2O2P2RuS
827.32
125(2)
0.71073
monoclinic
P2(1)/n
10.9589(14)
14.0386(18)
18.711(2)
90
100.953(2)
90
2826.2(6)
4
1.944
˚
˚
a (A)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
Volume (A )
Z
Dcalc (Mg/m3)
Absorption coefficient (mmꢁ1
F(000)
)
2.950
1584
Crystal size (mm3)
0.13 · 0.1 · 0.1
1.83–25.44
ꢁ12 6 h 6 13,
ꢁ16 6 k 6 16,
ꢁ22 6 l 6 17
17849
5125 (Rint = 0.0506)
98.0%
multiscan
1.00000 and 0.854096
h range for data collection (ꢁ)
Index ranges
Reflections collected
Independent reflections
Completeness to h = 25.44ꢁ
Absorption correction
Maximum and minimum
transmission
Refinement method
full-matrix least-squares on F2
5125/0/3175
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2r(I)]
R indices (all data)
Extinction coefficient
Largest difference peak
0.626
RI = 0.0321, wR2 = 0.0608
RI = 0.0570, wR2 = 0.0664
0.00049 (8)
0.679 and ꢁ0.914S
3
˚
and hole (e/A )
[21,22]. The m(PS) band at 583 cmꢁ1 (Table 3) is about
23 cmꢁ1 lower than that of the free ligand
[m(PS) = 606 cmꢁ1] suggesting chelate formation via me-
1
tal–sulfur bonding [9]. The H NMR spectra (Table 3)
of 1a show two multiplet resonances in the ranges d
7.18–7.59 and d 7.67–8.13 ppm which is attributable to
the two non-equivalent phenylic protons. The two meth-
ylene protons in the chelate ligand do not seem to be
[Ru(CO)2I2]n
n mol a
n molb-d
n mol
2
I
Ru
I
I
Ru
I
I
CO
a-d
CO
CO
CO
I
I
S
I
OC
OC
P~S
Ru
Ru
S~P
P
S~P
OC
1b-d
a
I
CO
1a
monomer
dimer
b-d
CO
CO
S~P
S~P
Ru
P~S = 1- (P)coordinated;
η
Ph2P(CH2)nP(S)Ph2;
I
P S =η2 - (P, S)coordinated.
2a-d
n = 1(a), 2(b), 3(c), 4(d)
Scheme 1.

880
D.K. Dutta et al. / Inorganica Chimica Acta 359 (2006) 877–882
Table 2
Analytical data of the complexes
Complex
Yield (%)
Elemental analysis found (calc.) in %
C
H
I
1a
1b
1c
1d
2a
2b
2c
2d
95
98
93
92
96
94
91
95
39.20 (39.17)
39.91 (39.94)
40.70 (40.69)
41.39 (41.41)
50.19 (50.17)
50.93 (50.95)
51.68 (51.70)
52.40 (52.42)
2.64 (2.66)
2.83 (2.85)
3.07 (3.04)
3.20 (3.22)
3.52 (3.54)
3.77 (3.78)
4.03 (4.00)
4.24 (4.22)
30.65 (30.68)
30.20 (30.17)
29.64 (29.68)
29.20 (29.19)
20.39 (20.41)
19.93 (19.96)
19.50 (19.53)
19.09 (19.11)
Table 3
IR, 31P–{H} and 1H values (d in ppm; JP–P in Hz) of the complexes
Complex
IR (cmꢁ1
)
31P–{H} NMR
1H NMR
C6H5
m(CO)
m(PS)
dP
dP@S
JP–P
–(CH2)n–
1a
1b
1c
1d
2a
2b
2c
2d
2098
2030
583
61.60d
53.63d
77.4
68.6
65.8
50.2
70.9
65.3
51.2
78.1
7.18–7.59m
7.67–8.13m
3.89ddd
4.77ddd
2036
2103
610
610
609
599
609
610
610
54.93d
56.62d
52.34d
61.52d
54.31d
56.44d
52.53d
45.14d
52.33d
43.81d
49.22d
45.13d
52.34d
44.0d
7.28–7.56m
7.64–7.96m
2.65m
3.08m
2033
2101
7.29–7.56m
7.63–7.81m
2.05m
2.58m
2033
2102
7.37–7.53m
7.71–7.88m
2.45m
2.10m
2028
2096
7.10–7.56m
7.67–7.88m
3.63dd
2034
2102
7.32–7.54m
7.62–7.77m
2.65m
3.08m
2032
2100
7.29–7.43m
7.58–7.84m
1.93m
2.58m
2033
2100
7.24–7.44m
7.58–7.87m
2.56m
2.20m
Free ligands (a–d). IR: m(PS): 606(a), 614(b), 612(c), 614(d); 31P NMR: dP and dP@S: ꢁ22.7, 45.2d {2JP–P = 90 Hz}(a); ꢁ16.8, 42.6d {3JP–P
=
17 Hz}(b); ꢁ13.2, 47.1d {4JP–P = 167 Hz}(c); ꢁ15.5, 43.1d {5JP–P = 25 Hz}(d); 1H NMR: –(CH2)n–: 3.35dd(a); 2.62m, 2.90m(b); 2.52m, 1.35m(c);
2.40m, 2.00m(d).
d, doublet; m, multiplet; dd, doublet of doublet; ddd, doublet of double doublet.
the 31P NMR spectra of 1b–d also exhibit two doublet
Table 4
13C NMR data of the complexes (d in ppm)
resonances, one relatively low field at
d 52.34–
Complex
CO
–(CH2)n–
C6H5
56.62 ppm for the PA atom and other high field at d
43.81–52.33 ppm for the PB atom. The observed large
down field shift of about 67–72 ppm compared to the
free ligands for the PA phosphorus atom supports the
monodentate nature of the ligands. The 13C NMR spec-
tra of the complexes 1b–d consist of all characteristic sig-
nals for carbonyl carbons, methylene carbons and
phenylic carbons (Table 4). The complexes 1b–d have
equivalent CO ligands, which is corroborated by the
appearance of a single peak for the two carbonyl
carbons.
1a
1b
1c
1d
2a
2b
2c
2d
185.9
186.6
186.7
186.4
186.7
186.6
186.4
186.7
34.0dd
24.34m
33.23m
32.72m
34.51dd
26.40m
33.35m
33.11m
128.61–135.25m
128.10–134.0m
128.94–132.23m
128.61–131.14m
128.63–133.15m
129.0–132.22m
128.91–133.42m
128.64–133.83m
ing [Ru(CO)2I2]n directly with two molar equivalent of
the ligands a–d. The m(PS) band of the complexes 2a–d
appears almost in the same position as that of the corre-
sponding free ligands suggesting the coordination with
the metal center through the tertiary phosphorus atom.
As for the complexes 1a–d, the position and nature of
Further reaction of 1a–d with one molar equivalent
of the ligands a–d produces hexa-coordinated g1-P
bonded complexes [Ru(CO)2I2(PꢀS)2] (2a–d) (Scheme
1). The same complexes can also be synthesized by treat-

D.K. Dutta et al. / Inorganica Chimica Acta 359 (2006) 877–882
881
Table 5
the m(CO) bands (Table 3) are consistent with the cis dis-
position of the two terminal carbonyl groups. The H
˚
1
Selected bond lengths (A) and bond angles (ꢁ) of the complex 1a
Bond lengths
NMR spectra of 2a–d consist of two characteristics mul-
tiplet resonances for phenyl ring protons in the ranges d
7.10–7.56 and d 7.58–7.88 ppm along with usual signals
for methylene protons. The 31P NMR data of the com-
plexes are in accord with the g1-P coordination mode of
the ligands. Two distinct doublet resonances are ob-
served at d 52.53–61.52 and d 44.0–52.34 ppm for ter-
tiary phosphorus and pentavalent phosphorus atom,
respectively, which are consistent with equivalent P
atoms in the complexes. The low JP–P values indicate
that the two coordinating phosphorus atoms (PA and
PB) are mutually cis to one another. The 13C spectra
show only one singlet at around d 186 ppm for the
two carbonyl carbons, which accounts for the equiva-
lency of the CO groups in the complexes. The character-
istics signals for methylene and phenylic carbons are
also identified in the complexes. Thus, on the basis of
IR and NMR data, the structures of the complexes
2a–d are proposed to be cis, cis, trans with iodide ligands
trans. In trans disposition to each other, the iodide li-
gands can form strong bond to Ru because of their elec-
tronegative and relatively poor r-donor characters [26].
Careful spectroscopic investigations reveal that the
complexes 1b–d exhibit one additional broad (weak)
IR bands at around 590 cmꢁ1 which are about
25 cmꢁ1 lower than the corresponding free m(PS) ligand
bands suggesting the formation of metal–sulfur bonds.
Therefore, possible equilibrium may exist between mono
and bimetallic complexes (PS bridging) as shown in the
Scheme 1. In case of complexes 2a–d, no spectroscopic
evidence is found for the formation of such bimetallic
complexes.
Ru–C(27)
Ru–C(26)
Ru–P(2)
Ru–S(1)
Ru–I(2)
1.880(6)
1.903(6)
2.3212(12)
2.4615(13)
2.7451(6)
2.7626(6)
2.0103(17)
1.811(4)
1.835(5)
1.112(6)
1.129(6)
Ru–I(1)
S(1)–P(1)
P(1)–C(25)
P(2)–C(25)
C(26)–O(26)
C(27)–O(27)
Bond angles
C(27)–Ru–C(26)
C(27)–Ru–P(2)
C(26)–Ru–P(2)
C(27)–Ru–S(1)
C(26)–Ru–S(1)
P(2)–Ru–S(1)
C(27)–Ru–I(2)
C(26)–Ru–I(2)
P(2)–Ru–I(2)
S(1)–Ru–I(2)
C(27)–Ru–l(1)
C(26)–Ru–l(1)
P(2)–Ru–I(1)
S(1)–Ru–l(1)
93.2(2)
96.49(15)
93.54(13)
86.89(16)
175.83(13)
90.60(4)
175.32(15)
90.15(15)
86.60(3)
89.57(3)
86.23(14)
90.69(13)
174.83(4)
85.14(3)
90.427(15)
105.01(6)
107.55(14)
I(2)–Ru–I(1)
P(1)–Ru–S(1)
C(25)–Ru(1)–P(2)
In order to obtain unambiguous characterization of
the complexes 1a–d and 2a–d, an X-ray diffraction study
was undertaken. Fortunately, a good crystal suitable for
X-ray analysis was developed for the complex 1a,
[Ru(CO)2I2(P\S)]. The IR and NMR data are well
agreed with this molecular structure of the complex.
Table 5 lists the relevant bond lengths and bond angles.
Fig. 1 shows the arrangements and numbering of atoms
in the crystal. The crystal contains a metal occupying the
center of a slightly distorted octahedron with two cis
carbonyl, two cis iodides and one bis phosphine sulfide
ligand bonding via P and S atom to the metal complet-
ing the coordination sphere. This atomic arrangements
is sterically less hindered and energetically most
favoured because the carbon monoxide is a very
strongly double bonding ligand and prefers not to be
in a trans position to another carbon monoxide [27].
The CO is a strong p-acceptor and hence any trans
ligand competing for electron density from the metal
center will weaken the M–CO bond. The trans influence
of the ligands falls in the sequence CO > P > I. Thus, the
complex containing iodide ligand trans to CO group will
Fig. 1. The structure of
(1a). Hydrogen
[Ru( CO)2I2(Ph2PCH2P(S)Ph2]
atoms are omitted for clarity.
be most stable than isomers with either a P or a CO
trans to a carbonyl group [28]. The Ru–P bond length
is some what shorter than the reported complex
[Ru(CO)Cl(P\S)2] [14]. This shortening of the Ru–P
bond length is due to the strong p-acceptor property
of the two carbonyl groups as a result of which a strong

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D.K. Dutta et al. / Inorganica Chimica Acta 359 (2006) 877–882
dp–pp bonding is formed between the Ru and the P
atom. The Ru–CO and Ru–S bond lengths are not
significantly different from those observed for similar
complexes [Ru(CO)2(BzIPPh2)Cl2] and [g6-MeC6H4-
PriRu{g3-(SPPh2)2CMe–C,S,S0}]PF6 [29,30]. The ob-
served deviation from usual bond angles (180ꢁ and
90ꢁ) of a regular octahedral geometry is probably due
to steric requirement to get a most stable structure,
where the uncoordinated phenyl rings are oriented away
from the plane containing the all bonding groups and
atoms to the metal [31]. The deviations of bond angles
resemble with the deviations of related complexes
involving the same ligands [3,24]. Although, we success-
fully grew crystals for [Ru(CO)2I2(P\S)] (1a), no crystal
was developed for the same type of complex
[Ru(CO)2Cl2(P\S)] [14]. The soft Ru metal will prefer
to bind with the softest I atom rather than Cl.
Moreover, in the absence of the other interaction
between the halide and the metal, iodide would be
expected to form the strongest bond due to the r-inter-
action with the metal. Conversely, we can explain the
decarbonylation reaction taking place in the
complex [Ru(CO)2Cl2(PꢀS)2](PꢀS = g1-P-coordinated
Ph2PCH2P(S)Ph2) to give a new chelate complex
[Ru(CO)2Cl(P\S)2]Cl. The molecular structure of this
new complex was established by a single crystal X-ray
study [14] but, no such decarbonylation was observed
in our present complex [Ru(CO)2I2(PꢀS)2] (2a). We
have reacted the complex 1a under vigorous reaction
condition with various r-donor ligands such as Ph3P,
Ph3As, Ph3Sb and Ph3PX; X = O,S,Se in order to inves-
tigate the lability of the Ru–S bond in the molecule.
Interestingly, these ligands were not able to break the
relatively labile metal–sulfur bond as expected.
The Department of Science and Technology (DST),
New Delhi is acknowledged for the partial financial
grant. The author PC thanks CSIR, New Delhi, for
the award of Senior Research Fellowship (SRF).
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4. Supplementary material
Supplementary data are available from the CCDC, 12
Union Road, Cambridge CB2 1EZ, UK on request.
CCDC deposition no. 265528. Copies of this informa-
tion may be obtained free of charge from the Director,
CCDC, 12 Union Road Cambridge, CB2 1EZ, UK
(fax: +44 1223-336033; e-mail: deposit@ccdc.cam.ac.uk
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for his kind permission to publish the work. The authors
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