Synthesis, molecular and crystal structure of a new dicarbonylruthenium(II) complex containing a xantphos dioxide chelating ligand

Article abstract of DOI:10.1016/j.poly.2009.04.004

The reaction of xantphos dioxide (O∩O) with the polynuclear precursor [Ru(CO)₂Cl₂]_n to give the mononuclear complex [Ru(CO)₂Cl₂(O∩O)](1) is reported together with single crystal X-ray structure analys

Full text of DOI:10.1016/j.poly.2009.04.004

Polyhedron 28 (2009) 2258–2262
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Synthesis, molecular and crystal structure of a new dicarbonylruthenium(II)
complex containing a xantphos dioxide chelating ligand
*
Biswajit Deb, Dipak Kumar Dutta
Materials Science Division, North-East Institute of Science and Technology (CSIR), Jorhat-785 006, Assam, India
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of xantphos dioxide (O\O) with the polynuclear precursor [Ru(CO)2Cl2]n to give the mono-
nuclear complex [Ru(CO)2Cl2(O\O)](1) is reported together with single crystal X-ray structure analyses of
both the free ligand and the ruthenium complex. The synthesized compounds have also been character-
ized by elemental analyses, IR and NMR (1H, 31P and 13C) spectroscopy. The ligand O\O crystallizes with
Received 3 March 2009
Accepted 3 April 2009
Available online 11 April 2009
ꢀ
lattice water molecules in a triclinic system with space group P1 whereas the complex 1 crystallizes in an
Keywords:
Crystal structure
Ruthenium
Carbonyl complex
Xantphos dioxide
Chelating ligand
orthorhombic system with space group P212121. Each mononuclear unit of O\O and 1 is stabilized in
their solid state through non-covalent (C–HꢀꢀꢀO, C–HꢀꢀꢀCl and C–Hꢀꢀꢀ
p) interactions to develop an extended
three-dimensional network structure. The complex 1 exhibits an interesting intramolecular OꢀꢀꢀO interac-
tion between one of the P@O groups and backbone O leading to different electron donacity of two P@O
groups to the metal centre.
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
molecular glue’ resulting in polymeric network. As a part of our
continuing research activity [22–26], herein we report the synthe-
The assembly of mononuclear and polynuclear organometallic
complexes in the solid state is governed by a balance between non-
directional close packing forces and directional interactions be-
tween metal atoms or charged groups [1]. The intermolecular
interactions acting among the molecules in their solid state plays
an important role to understand the solid state properties of orga-
nometallic compounds as both physical (conductivity, diffusion,
magnetic susceptibility, reorientation and second harmonic gener-
ation) and chemical (solid state reactivity, racemisation, resolu-
tion) properties of a compound depend on the ways in which the
molecules are organized in the crystal and on the forces which hold
them together [2]. The two major types of interactions employed
by chemists to engineer supramolecules with predefined dimen-
sions (1D, 2D and 3D), are metal ligand bonding and hydrogen
bonding. In addition to strong (O–HꢀꢀꢀO) and weak (C–HꢀꢀꢀO) hydro-
sis, structure and self-aggregation of oxygen functionalised robust
backbone ditertiary phosphine like xantphos [9,9-dimethyl-4,5-
bis(diphenyl phosphino)xanthene] and its ruthenium(II) carbonyl
complex.
2. Results and discussion
The rigid backboned xantphos dioxide (O\O) reacts with the
polymeric precursor [Ru(CO)2Cl2]n in 1:1 molar ratio to afford
hexa-coordinated mononuclear complex [Ru(CO)2Cl2(O\O)] (1)
(Scheme 1). The IR spectra of 1 show two equally intense m(CO)
bands at around 1973 and 2049 cmꢁ1 attributing the presence of
two terminal carbonyl groups only (Fig. 1). The (P–O) band of 1
at 1187 cmꢁ1 is about 6 cmꢁ1 lower than that of the free ligand
m
(m
(P–O) = 1193 cmꢁ1) revealing the coordination to metal through
O-donor. The 13C NMR spectrum of 1 shows only one signal for the
two non-equivalent carbonyl carbons as broad singlet at around d
195 ppm. The 31P NMR spectra of 1 exhibit only one sharp signal
indicating the presence of a single isomer.
gen bonds; halogen bonds (C–XꢀꢀꢀO) and weak (C–Hꢀꢀꢀ
p) interac-
tions have also been well characterized and exploited to playing
an important role in crystal engineering and organometallic struc-
tures [3–7]. The metallosupramolecules thus generated have at-
tracted attention in recent years due to their applications in
diverse areas such as catalysis, optoelectronics, gas storage, ion ex-
change, molecular recognition and magnetism [8–21]. To develop
such extended network structures, an appropriate ligand should
be chosen, which on complexation with metal ions forms ‘supra-
The ligand O\O and its metal complex 1 have been structurally
characterized by single crystal X-ray diffraction. The crystal infor-
mation for the two compounds is summarized in Table 1. The li-
gand O\O crystallizes with lattice water molecules in a triclinic
ꢀ
system with space group P1. The asymmetric unit of O\O, shown
in Fig. 2 consists of three xantphos dioxide moieties along with
three disorder water molecules. The two P@O groups of each mol-
ecule form strong hydrogen bonds with one water molecule. The
* Corresponding author. Tel.: +91 376 2370081; fax: +91 376 2370011.
E-mail address: dipakkrdutta@yahoo.com (D.K. Dutta).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.04.004

B. Deb, D.K. Dutta / Polyhedron 28 (2009) 2258–2262
2259
Scheme 1. Synthesis of complex 1.
Ligand, O∩O
40
30
20
10
Complex 1
%T
1187.2
1193.3
1972.8
2049.2
2000
1800
1600
1400
1200
1000
Fig. 2. Asymmetric structure of the ligand xantphos dioxide (O\O). Hydrogen
Wavenumber (cm-1
)
atoms are omitted for clarity.
Fig. 1. IR spectra of the ligand (O\O) and complex 1.
three-dimensional network [O(3)ꢀꢀꢀO(11) 2.722(3); O(1)ꢀꢀꢀO(11)
2.776(2); H(49)ꢀꢀꢀO(11) 2.676(1); H(63)ꢀꢀꢀO(11) 2.708(2);
H(47A)ꢀꢀꢀO(11) 2.508(3) etc.] (Table 3). The compound loses water
molecule on activating the sample at 100 °C for 1 h and this solvent
loss is accompanied by the loss of transparency of the crystals. An
X-ray powder diffraction analysis revealed that the solvent loss is
accompanied by the loss of crystallinity, and indeed, no diffraction
peaks were observed for the bulk sample.
Table 1
Crystallographic data for O\O and 1.
O\O
C117H96O12P6
1879.76
293
1
Empirical formula
Formula weight
T (K)
C41H32Cl2O5P2Ru
838.64
293
k (Å)
0.71073
triclinic
0.71075
orthorhombic
P212121
8
9.7437(19)
19.395(4)
20.072(4)
90
90
90
1.377
7773
Cryst. Syst.
Space group
Z
a (Å)
b (Å)
The complex 1 crystallizes in an orthorhombic system with
space group P212121 where the Ru atom is situated at the centre
of an octahedral environment formed by two O donors, two CO
and two Cl atoms. The selected bond lengths and bond angles are
presented in Table 2. The X-ray crystal structure (Fig. 5) reveals
that the two Cl atoms are trans to each other, whereas the CO
groups which are cis to each other are situated at the positions
trans to two O donors. The two CO groups, two O donors and Ru
metal are located in the same plane. The ligand O\O forms a che-
late (bite angle O2–Ru1–O1, 85.39) through O, O donor and forms a
ten member distorted ring structure. The O1–Ru1–O2 plane is in-
clined by an angle 102° to the plane of the backbone of xantphos
ligand. As a result of this folded structure, there appears a close
intramolecular (O(1)ꢀꢀꢀO(5) [2.905(4) Å, Fig. 5] interaction between
the O atom of ligand backbone and one of the O atoms of P@O
group of the chelating ligand. This type of OꢀꢀꢀO interaction is not
commonly observed though the O–O short contact between two
carbonyl groups is documented in literature [3]. The effect of the
OꢀꢀꢀO interaction in 1 is reflected in CO bond order which is consis-
tent with their corresponding Ru–C bond lengths (Table 2). The
influence of O(1) trans to C(41) at the metal centre is less than that
ꢀ
P1
2
15.4027(5)
17.4463(6)
20.3994(7)
71.715(2)
70.483(2)
80.705(2)
0.174
c (Å)
a
(°)
b (°)
c
(°)
l(Mo K
a
) mmꢁ1
Reflections collected
Flack parameter
R1 (observed data)
wR2 (all data)
6675
0.01(3)
0.0461(7368)
0.1399(7773)
0.0575(4211)
0.1645(6675)
average value of P@O bond length is found to be 1.48 Å (Table 2).
The compound O\O forms a three-dimensional network structure
by extending infinitely via strong intermolecular C–HꢀꢀꢀO and
C–Hꢀꢀꢀ
p interactions as shown in Fig. 3. As indicated in both Figs.
3 and 4, water molecules are trapped into the network by the
ligand O\O through intermolecular hydrogen bonding by bridging
each molecule of xantphos dioxide generating solvent stabilized

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B. Deb, D.K. Dutta / Polyhedron 28 (2009) 2258–2262
Table 2
Selected bond distances (Å) and angles (°) for compounds O\O and 1.
Ligand O\O
P(1)–O(1)
P(6)–O(9)
1.476(4)
1.475(4)
P(2)–O(3)
P(4)–O(6)
1.479(4)
1.478(4)
P(5)–O(7)
P(3)–O(4)
1.484(4)
1.476(5)
Complex 1
P(1)–O(1)
O(2)–Ru(1)
Ru(1)–C(40)
C(41)–O(3)
1.491(3)
2.118(3)
1.833(7)
0.973(9)
O(1)– Ru(1)
Ru(1)– Cl(1)
C(40)– O(4)
2.118(3)
2.3796(17)
1.129(10)
P(2)–O(2)
Ru(1)–Cl(2)
Ru(1)–C(41)
1.487(3)
2.3739(13)
1.931(7)
Cl(1)–Ru(1)–Cl(2)
C(40)–Ru(1)–O(2)
C(40)–Ru(1)–C(41)
176.59(5)
176.7(2)
89.1(3)
O(1)–Ru(1)–O(2)
C(41)–Ru(1)–O(1)
85.39(12)
172.3(2)
indicates a weaker interaction in the former and is therefore likely
to dissociate more easily.
The complex 1 exhibit some interesting intermolecular interac-
tions involving shorter distances than the sum of van der Waals ra-
dii (Fig. 6). The interactions between these molecules are presented
by dotted lines and summarized in Table 4. The molecules are con-
nected by weak hydrogen bondings between H atoms of the phenyl
ring of xantphos ligand and O atom of CO group (C–HꢀꢀꢀOC) and Cl
atom (C–HꢀꢀꢀCl) of the adjacent molecules [C(23)–H(23)ꢀꢀꢀCl(2)
2.763(4) Å, C(36)–H(36)ꢀꢀꢀCl(2) 2.879(4) Å, C(12)–H(12)ꢀꢀꢀO(4)
2.582(7) Å and C(35)–H(35)ꢀꢀꢀO(3) 2.704(6) Å]. In addition to these
hydrogen bondings, intermolecular C–Hꢀꢀꢀ
p interactions between H
atoms of xantphos ligand and the phenyl ring of these molecules
[C(30)–H(30)ꢀꢀꢀC(33) 2.812(7) Å, C(8)–H(8)ꢀꢀꢀC(24) 2.822(5) Å, and
C(32)–H(32)ꢀꢀꢀC(11) 2.832(8) Å] are also observed in their solid
Table 3
Significant intermolecular interactions in the crystal O\O.
D–HꢀꢀꢀA
HꢀꢀꢀA/Å
DꢀꢀꢀA/Å
(D–HꢀꢀꢀA)/°
C(64)–H(64) ꢀꢀC(15)i
C(38)–H(38) ꢀꢀO(6)ii
C(47)–H(47A) ꢀꢀO(11)i
C(57)–H(57) ꢀꢀO(12)i
C(49)–H(49) ꢀꢀO(11)i
C(63)–H(63) ꢀꢀO(11)iii
O(1) ꢀꢀO(11)iv
2.749(8)
2.394(1)
2.508(3)
2.377(9)
2.676(1)
2.708(2)
3.670(1)
3.242(2)
3.463(9)
3.182(1)
3.532(7)
3.626(5)
2.776(2)
2.722(3)
2.692(1)
2.726(1)
2.869(6)
2.860(2)
170.2(1)
151.6(2)
174.1(2)
144.6(1)
153.5(7)
169.6(1)
Fig. 3. Intermolecular short contacts in the molecule O\O. All the hydrogen atoms
except those involved in hydrogen bonding have been omitted for clarity.
of O(2) trans to C(42), which may be due to O(1)ꢀꢀꢀO(5) interaction.
Because of the weak Ru–O interaction in the former, the electron
density increases on the metal centre in the latter case resulting
O(3) ꢀꢀO(11)iv
O(4) ꢀꢀO(12)v
O(6) ꢀꢀO(12)v
O(7) ꢀꢀO(10)i
in more dp
-electrons to the antibonding p* orbital of the CO and
O(9) ꢀꢀO(10)i
hence decreases the Ru–C bond length and consequently reduces
the C–O bond order (increases C–O bond length). The longer bond
length of Ru1–C41 (1.931(7) Å) than Ru1–C40 (1.833(7) Å)
Symmetry operators are (i) x, y, z (ii) 1ꢁx, 1ꢁy, 1ꢁx (iii) 1 + x, y, z (iv) 1ꢁx, y, (v) 1ꢁx,
ꢁy, 1ꢁz.
Fig. 4. 3-D network structure of O\O containing water molecules inside the network when viewed down the c-axis.

B. Deb, D.K. Dutta / Polyhedron 28 (2009) 2258–2262
2261
Fig. 7. 3D stacked structure of 1 stabilized by weak hydrogen bonding. Hydrogen
atoms are omitted for clarity.
Fig. 5. X-ray crystal structure of 1. Hydrogen atoms have been omitted for clarity.
3. Experimental
3.1. General
All operations were carried out under nitrogen atmosphere. All
solvents were distilled under N2 prior to use. RuCl3 ꢀ xH2O was pur-
chased from M/S Arrora Matthey Ltd., Kolkata, India. The ligand
xantphos was purchased from M/S Aldrich, USA and used without
further purification. H2O2 was obtained from Ranbaxy, New Delhi,
India and estimated before use.
Elemental analyses were performed on a Perkin–Elmer 2400
elemental analyzer. IR spectra (4000–400 cmꢁ1) were recorded
on KBr discs in a Perkin–Elmer system 2000 FT-IR spectrophotom-
eter. The 1H, 13C and 31P NMR spectra were recorded in CDCl3 solu-
tion on a Bruker DPX-300 Spectrometer and chemical shifts were
reported relative to SiMe4 and 85% H3PO4 as internal and external
standards, respectively. Thermal analyses of the complexes were
carried out using a thermal analyzer (TA instrument, Model STD
2960 simultaneous DTA–TGA) in presence of N2 atmosphere with
a heating rate of 10 °C/min.
Fig. 6. Intermolecular short contacts in 1. The atoms involved in short contact (only
a few selective interactions) from surrounding molecules have been designated by
dotted lines.
3.2. Synthesis of xantphos dioxide (O\O)
Table 4
The ligand xantphos dioxide was synthesized by oxidation of
xantphos with H2O2 following the literature protocol [27].
Significant intermolecular interactions in the complex 1.
IR (KBr, cmꢁ1): 1193 [ (P–O)]. 1H NMR (CDCl3, ppm): d 6.74–
m
D–H ꢀꢀA
H ꢀꢀA/Å
D ꢀꢀA/Å
(D–H ꢀꢀA)/°
7.74 (m, 30H, Ph), 2.17 (s, 6H, CH3). 13C NMR (CDCl3, ppm): d
153.10–124.1 (Ar), d 32.3, 34.9 (CH3). 31P{1H} NMR (CDCl3, ppm):
d 30.95 [s, P(v)]. Anal. Calc for C39H32O3P2: C, 74.40; H, 5.08. Found:
C, 73.98; H, 5.09%.
C(23)–H(23) ꢀꢀCl(2)i
C(36)–H(36) ꢀꢀCl(2)i
C(12)–H(12) ꢀꢀO(4)ii
C(35)–H(35) ꢀꢀO(3)ii
C(30)–H(30) ꢀꢀC(33)iii
C(8)–H(8) ꢀꢀC(24)iv
C(32)–H(32) ꢀꢀC(11)v
O(1) ꢀꢀO(5)vi
2.763(4)
2.879(4)
2.582(7)
2.704(6)
2.812(7)
2.822(5)
2.832(8)
3.519(4)
3.729(8)
3.369(9)
3.519(9)
3.740(8)
3.679(3)
3.633(9)
2.905(4)
138.9(4)
152.6(2)
142.8(1)
146.7(7)
175.6(2)
153.7(1)
149.9(5)
3.3. Synthesis of the starting complex [Ru(CO)2Cl2]n
The starting complex [Ru(CO)2Cl2]n was prepared by passing CO
through a refluxing solution of RuCl3ꢀ3H2O in ethanol for about
24 h [28–31].
Symmetry operators are (i) ꢁx, ꢁ1/2 + y, 1.5ꢁz (ii) ꢁ1 + x, y, z (iii) 1/2 + x, 1/2ꢁy,
2ꢁz (iv) ꢁx, 1/2 + y, 1.5ꢁz (v) ꢁ1/2ꢁx, 1ꢁy, 1/2 + z (vi) x, y, z.
3.4. Synthesis of [Ru(CO)2Cl2(O\O)] (1)
state. All these results demonstrate the extended three-dimen-
sional network structure as shown in Fig. 7 which exhibits high
thermal stability (>300 °C). This result infers that the intermolecu-
lar interactions of one mononuclear unit of 1 with the adjacent
members have a profound effect on overall thermal stability of
the network.
[Ru(CO)2Cl2]n (0.877 mmol, 200 mg) was dissolved in methanol
(10 cm3) and xantphos dioxide (0.877 mmol, 536 mg) was
dissolved in dichloromethane (10 cm3). Both the solutions were
mixed together and refluxed for 4 h. The solvent was removed
and washed with diethyl ether. The resulting reddish yellow

2262
B. Deb, D.K. Dutta / Polyhedron 28 (2009) 2258–2262
compound was recrystallised from dichloromethane/n-hexane to
give the complex ‘1’ (640 mg, 87%)
Appendix A. Supplementary data
IR (KBr, cmꢁ1): 2049, 1973 [ (P–O)]. 1H NMR
m(CO)]. 1187 [m
CCDC 683610 and 707430 contain the supplementary crystallo-
graphic data (O\O) and (1). These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; e-mail:
deposit@ccdc.cam.ac.uk.
(CDCl3, ppm): d 6.53–7.92 (m, 30H, Ph), 1.74 (s, 3H, CH3), 1.82 (s,
3H, CH3). 13C NMR (CDCl3, ppm): d 152.78–122.13 (Ar), d 33.59,
34.20 (CH3), 195.64 (CO). 31P{1H} NMR (CDCl3, ppm): d 41.96 [s,
P(v)]. Anal. Calc for C41H32Cl2O5P2Ru: C, 57.40; H, 3.73. Found: C,
56.85; H, 3.65%.
3.5. X-ray structural analysis
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Acknowledgement
The authors are grateful to Dr. P.G. Rao, Director, North-East
Institute of Science and Technology (CSIR), Jorhat, Assam, India,
for his kind permission to publish the work. Thanks are also due
to DST, New Delhi for a financial support (Grant: SR/S1/IC-05/
2006). The author B. Deb (JRF) is grateful to CSIR for providing
the fellowship.