Reactivity studies of η6-arene ruthenium (II) dimers with polypyridyl ligands: Isolation of mono, binuclear p-cymene ruthenium (II) complexes and bisterpyridine ruthenium (II) complexes

Article abstract of DOI:10.1016/S0277-5387(03)00460-1

The complexes [(η⁶-p-cymene)RuCl(L₂)] ⁺ where L2=2,2′-biquinoline (biqui) (3), 2,9-dimethyl 4,7-diphenyl-1,10-phenanthroline (ddp) (4), and 2,3-bis(α-pyridyl) quinoxaline (bpq) (5) were obtained by halide bridge cleavage o

Full text of DOI:10.1016/S0277-5387(03)00460-1

Polyhedron 22 (2003) 3155–3160
www.elsevier.com/locate/poly
Reactivity studies of g6-arene ruthenium (II) dimers with
polypyridyl ligands: isolation of mono, binuclear p-cymene
ruthenium (II) complexes and bisterpyridine ruthenium
(II) complexes
*
R. Lalrempuia, Mohan Rao Kollipara
Department of Chemistry, North Eastern Hill University, Shillong 793 022, India
Received 16 May 2003; accepted 8 July 2003
Abstract
The complexes [(g6-p-cymene)RuCl(L2)]þ where L2 ¼ 2,20-biquinoline (biqui) (3), 2,9-dimethyl 4,7-diphenyl-1,10-phenanthroline
(ddp) (4), and 2,3-bis(a-pyridyl) quinoxaline (bpq) (5) were obtained by halide bridge cleavage of [{(g6-p-cymene)Ru(l-Cl)}2Cl2] (1)
with the corresponding ligands. The ligand bridged binuclear compound [{(g6-cymene)RuCl}2(bpq)]2þ (6) was also obtained by
treating 1 with stoichiometric amount of bpq in methanol. The reactions of [{(g6-arene)Ru(l-Cl)}2Cl2], {arene ¼ p-cymene (1),
hexamethylbenzene (2)} with substituted phenylterpyridines (x-phterpy, x ¼ H, CH3, OCH3) yielded bis terpyridine complexes of the
type [(x-phterpy)2Ru]2þ by the facile displacement of g6-arene ring as well as chloride ligands. These complexes were characterized
by FT-NMR, FT-IR spectroscopy, and analytical data. The molecular structures of [(g6-p-cymene)RuCl(biqui)]PF6 (3) and [(g6-p-
cymene)RuCl(bpq)]PF6 (5) have been determined by single crystal X-ray diffraction study.
Ó 2003 Elsevier Ltd. All rights reserved.
Keywords: p-Cymene; Hexamethylbenzene; Ruthenium; Terpyridine; 2,20-Biquinoline; 2,9-Dimethyl; 4,7-Diphenyl-1; 10-Phenanthroline; 2,3-Bis(a-
pyridyl)quinoxaline
1. Introduction
with the isolectronic halide bridged arene ruthenium
complexes of the type [{(g6-arene)Ru(l-Cl)}2Cl2], (are-
ne ¼ p-cymene, hexamethylbenzene), does not form the
expected [(g6-arene)RuCl(phterpy)]þ but instead irre-
spective of the solvents used gave only known bis ter-
pyridine ruthenium complexes [5]. This observation
prompted us to investigate the reactivity of [{(g6-are-
ne)Ru(l-Cl)}2Cl2], with more steric and bulkier chelat-
ing N,N0-heterocycles. Initial studies of these complexes
with 2,20-bipyridine and 1,10-phenanthroline have been
reported [6].
In this paper, we would like to report the formation
of [(g6-arene)RuCl(L2)]þ complexes and also the facile
displacement of g6-bonded arene as well as the chloride
ligands by phenylterpyridines from [{(g6-arene)Ru(l-
Cl)}2Cl2] forming known complexes of the type
[(phterpy)2Ru]2þ. In order to confirm the nature of
bonding, the structures of [(g6-p-cymene)RuCl(biqui)]
PF6 and [(g6-p-cymene)RuCl(bpq)]PF6 have been
solved by X-ray crystallography.
The arene ruthenium complexes played an important
role in organometallic chemistry. Synthesis of half
sandwich ruthenium (II) complexes received consider-
able attention owing to their catalytic properties [1] and
water-soluble half-sandwich arene ruthenium (II) com-
plexes have shown interesting anti-tumor activity [2].
It has been previously reported the reactivity of
terdenate polypyridyl ligands toward cyclopentadienyl,
indenyl, and pentamethylcyclopentadienyl ruthenium
systems where g5-bonded moieties remain intact and
thus forming [(g5-Ar)Ru(terpy)(PPh3)]þ, (Ar ¼ C5H5,
C9H7, C5Me5) [3] or [(g5-C5Me5)MCl(phterpy)]þ
(M ¼ Rh, Ir) [4], however, the reaction of these ligands
* Corresponding author. Tel.: +91-364-2551505; fax: +91-364-
2550076.
E-mail addresses: kmrao@nehu.ac.in, mrkollipara@rediffmail.com
(M. Rao Kollipara).
0277-5387/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0277-5387(03)00460-1

3156
R. Lalrempuia, M. Rao Kollipara / Polyhedron 22 (2003) 3155–3160
2. Experimental
mmol), and NH4PF6 (0.061 g, 0.376 mmol) was refluxed
in 10 ml of methanol under dry nitrogen atmosphere for 1
hour. The resulting solution was filtered to remove in-
soluble brown product. The filtrate was then evaporated
under vacuum on a rotary evaporator, the residue was
redissolved in CH2Cl2 and filtered, the volume was re-
duced to about 2 ml, then excess hexane was added which
gave an oily product. It was washed several times with
hexane to give orange-red microcrystalline solid. Suitable
crystals for X-ray structure determination were grown by
slow diffusion of hexane into acetone solution. Yield:
0.152 g, 66.6%. UV–Vis (CH3CN, 1 ꢁ 10ꢀ3 M): kmax 392
nm. Anal. Calc. for C28H26ClF6N4PRu: C, 48.04; H, 3.74;
N, 7.99. Found C, 48.14; H, 3.90; N, 8.04%. 1H NMR {d,
(CD3)2CO}: 9.55 (d, J ¼ 1:5 Hz), 8.99 (d, J ¼ 2:4 Hz),
8.67 (t, J ¼ 1:5 Hz) 8.42–8.15 (m), 8.02 (t, J ¼ 6 Hz),
7.80–7.70 (m), 7.3 (d, J ¼ 1:8 Hz), 6.44 (d, J ¼ 6:6 Hz),
6.28 (d, J ¼ 6:6 Hz), 6.12 (d, J ¼ 5:1 Hz), 2.60 (sept), 2.42
(s), 1.15 (d, J ¼ 7:2 Hz), 1.07 (d, J ¼ 6:9 Hz). IR (CsI,
cmꢀ1): 844 (s, mP–F), 557 (s), 304 (br, m, mRu–Cl).
All chemicals used were of reagent grade. All reac-
1
tions were carried out in purified and dried solvents. H
NMR spectra were recorded on a Bruker ACF 300
spectrometer. Infrared spectra were taken on a Perkin–
Elmer model 983 spectrophotometer using CsI pellets.
Elemental analysis was performed in Perkin–Elmer-
2400 CHN analyzer. [{(g6-arene)Ru(l-Cl)}2Cl2] [7],
2,3-bis(a-pyridyl) quinoxaline [8], 40-phenyl-2,20:60,200-
terpyridine (phterpy) [9], 40-p-methylphenyl-2,20:60,200-
terpyridine (Me-phterpy), and 40-p-methoxyphenyl-
2,20:60,200-terpyridine (OMe-phterpy) [10] were prepared
according to the procedure described in the literature.
2.1. Preparation of [(g6-cymene)Ru(biqui)Cl]PF6 (3)
The mixture of [{(g6-p-cymene)Ru(lCl)}2Cl2] (0.05
g, 0.081 mmol), 2,20-biquinoline (0.055 g, 0.214 mmol),
and NH4PF6 (0.080 g, 0.488 mmol) excess was stirred in
a mixture of methanol (10 ml) and CH2Cl2 (10 ml) at
room temperature for 1.5 h and the solvents were re-
moved under reduced pressure. The residue was redis-
solved in acetone and filtered to remove the insoluble
precipitated NH4Cl. The volume was reduced to about 2
ml; addition of excess hexane gave yellow compound.
Single crystals were grown by slow evaporation of ace-
tonitrile solution. Yield: 0.155 g, 70.76%. Anal. Calc. for
C28H26ClN2F6PRu: C, 50.04; H, 3.90; N, 4.16. Found
C, 50.10; H, 3.94; N, 4.19%. 1H NMR (d, CD3CN): 8.94
(d, J ¼ 8:7 Hz), 8.59 (d, J ¼ 8:4 Hz), 8.40 (d, J ¼ 8:4
Hz), 8.11 (m), 7.91 (t, J ¼ 7:5 Hz), 5.72 (d, J ¼ 6 Hz),
5.57 (d, J ¼ 6 Hz), 2.31 (s), 0.79 (d, J ¼ 6:9 Hz). IR
(CsI, cmꢀ1): 844 (s, mP–F), 557 (s), 310 (m, mRu–Cl).
2.4. Preparation of [{(g6-p-cymene)RuCl}2(bpq)]
(PF6)2 (6)
2.4.1. Method (i)
The brown insoluble product from the preparation of
complex 5 was dissolved in acetone to give a violet color
solution, which was reduced to a few ml and addition of
diethylether gave the complex 6.
2.4.2. Method (ii)
The mixture of [{(g6-p-cymene)Ru(lCl)}2Cl2] (0.1 g,
0.163 mmol), 2,3-bis(pyridyl)quinoxaline (0.046 g, 0.163
mmol), and NH4PF6 (0.06 g, 0.373 mmol) was refluxed in
methanol (10 ml). Violet color precipitate appears after 15
min and the whole reaction mixture was refluxed for 1 h.
The reaction mixture was cooled to room temperature
and filtered; the precipitate was washed several times with
water and then with methanol and then finally with di-
ethylether to give dark violet shiny product. It was air-
dried. Yield: 0.160 g, 87.91%. Anal. Calc. for
C38H40C12N4P2F12Ru2: C, 40.91; H, 3.58; N, 5.02. Found
C, 41.12; H, 3.60; N, 5.13%. UV–Vis (CH3CN, 1 ꢁ 10ꢀ3
M): kmax: 463 nm. 1H NMR {d, (CD3)2CO}: 9.44 (d, J ¼ 6
Hz), 8.88 (m), 8.48 (d, J ¼ 8:1 Hz), 8.41 (m), 8.15 (t,
J ¼ 8:1Hz), 7.90 (t, J ¼ 6:6 Hz), 6.19 (d, J ¼ 6:3Hz), 6.10
(d, J ¼ 6:3 Hz), 5.87 (t, J ¼ 5:7 Hz), 2.75 (sept), 2,23 (s),
1.20 (d, J ¼ 6:9 Hz), 1.09 (d, J ¼ 6:9 Hz). IR (CsI, cmꢀ1):
844 (s, mP–F), 557 (s), 306 (m, mRu–Cl).
2.2. Preparation of [(g6-p-cymene)Ru(ddp)Cl]PF6 (4)
The mixture of [{(g6-p-cymene)Ru(lCl)}2Cl2] (0.074
g, 0.122 mmol), 2,9-dimethyl, 4,7-diphenyl-l,10-phenan-
throline (ddp) (0.088 g, 0.244 mmol), and NH4PF6 (0.080
g, 0.488 mmol) in methanol (20 ml) was stirred at room
temperature for 2 h. Then the solvent was removed under
reduced pressure, the residue was redissolved in acetone,
and then filtered to remove the insoluble NH4Cl. The
volume was reduced to about 2 ml and addition of excess
hexane gave a yellow product. Yield: 0.150 g, 59.19%.
Anal. Calc. for C36H34N2Cl F6PRu: C, 61.90; H, 3.89; N,
1
3.60. Found C, 62.04; H, 3.90; N, 3.69%. H NMR (d,
CD3CN + CDCl3): 8.06 (s), 7.86 (s), 7.62 (m), 5.83–5.50
(m), 3.09 (s), 2.86 (sept), 2.24 (s), 1.32 (dd, J ¼ 3:6 Hz). IR
(CsI, cmꢀ1): 844 (s, mP –F), 558 (s), 306 (m, mRu–Cl).
2.5. Preparation of [{(g6-C6Me6) Ru(l-Cl)}2Cl2]
2.3. Preparation of [(g6-p-cymene)RuCl(bpq)]PF6 (5)
The mixture of [{(g6-p-cymene)Ru(l-Cl)}2Cl2] (0.13
g, 0.21 mmol) and hexamethylbenzene (1.3 g, 0.21
mmol) was refluxed in diglyme (18 ml) with stirring
under dry nitrogen atmosphere for around 9 h. The
The mixture of [{(g6-p-cymene)Ru(lCl)}2Cl2] (0.1 g,
0.163 mmol), 2,3-bis(a-pyridyl)quinoxaline (0.098g, 0.347

R. Lalrempuia, M. Rao Kollipara / Polyhedron 22 (2003) 3155–3160
3157
solution was cooled to room temperature and the red
brown product was filtered off, washed with hexane
(5 ꢁ 10 ml) to remove excess hexamethylbenzene and p-
cymene dimer and finally with diethylether. The com-
pound was recrystallized from chloroform/diethylether.
diffractometer with graphite monochromatized Mo Ka
(k ¼ 0:70930 A) radiation at a temperature of 293 K for
ꢀ
the cell determination and intensity data collection.
Crystal data collection parameters are summarized in
Table 1. All crystallographic calculations were per-
formed with the use of the Maxus [11] software. The
structure was solved by direct methods [12] (SHELXS
1997). Refinement was by full-matrix least squares based
on F 2 using SHELXL-93 [13]. Lorentz and polarization
corrections were applied. Non-hydrogen atoms were
refined anisotropically and hydrogen atoms were refined
using a ‘‘riding’’ model. Figs. 1 and 2 are the ORTEP
[14] representation of the molecules with 50% proba-
bility thermal ellipsoids displayed. Selected bond dis-
tances and angles are given in Tables 2 and 3 for
complexes 3 and 5, respectively.
1
Yield: 0.026 g, 18.5%. H NMR (CDCl3): d 2.02 (s) [lit
[7(b)]: 2.03]. 13C NMR (CDC13): d 89.61 (s), d 15.92 (s).
IR (CsI, cmꢀ1): 297 (s), 259 (s) [lit [7(b)]: 299, 258].
2.6. g6-Arene displacement reactions
The mixture of [{(g6-arene)Ru(l-Cl)}2Cl2] (arene ¼ p-
cymene, hexamethylbenzene) (0.163 mmol), phenylter-
pyridine ligands (0.407 mmol), and NH4BF4 (0.489
mmol) was stirred in dry methanol (15 ml) at room tem-
perature, the color of the solution immediately changed to
purple, stirred for 2 h whereby red brown compound was
precipitated out. The solvent was slowly removed in ro-
tary evaporator. The residue was redissolved in acetone
and filtered to remove any insoluble materials. Acetone
solution was reduced to about 2 ml and addition of excess
hexane precipitated out red brown compound.
3. Results and discussion
The cationic mono nuclear complexes with the gen-
eral formulation [(g6-p-cymene)RuCl(L2)]þ, L2 ¼ 2,2-
biqui, ddp and bpq were prepared by the reaction of
[{(g6-p-cymene)Ru(l-Cl)}2Cl2] with excess of L2 in
methanol however, addition of dichloromethane as a co-
solvent is necessary to prepare complex 3. These com-
plexes are soluble in acetone, acetonitrile, and DMSO
1. [(phterpy)2Ru](BF4)2. Yield: 0.120 g, 41.09% (from 1),
UV–Vis(1 ꢁ 10ꢀ3 M, CH3CN): kmax 489 nm. Anal.
Calc. for C42H30BF4N6Ru: C, 56.48; H, 3.35; N,
1
9.45. Found C, 56.52; H, 3.40; N, 9.49%. H NMR
{d, (CD3)2CO}: 9.46 (2H, s), 9.11 (2H, d, J ¼ 8:1
Hz), 8.36 (2H, dd, J ¼ 1:2 Hz), 8.14 (3H, dt,
J ¼ 1:2 Hz), 7.85–7.69 (4H, m), 7.38 (2H, dt, 1.2 Hz).
2. [(Me-phterpy)2Ru](BF4)2. Yield: 0.125 g, 41.66% (from
1), UV–Vis(1 ꢁ 10ꢀ3 M, CH3CN): kmax 480 nm. Anal.
Calc. for C44H34BF4N6Ru: C, 57.35; H, 3.68; N, 9.16.
Found C, 57.39; H, 3.72; N, 9.2%. 1H NMR {d, (CD3)2
CO}: 9.43 (2H, s), 9.08 (2H, d, J ¼ 8:1 Hz), 8.29 (2H, d,
J ¼ 8:7 Hz), 8.11 (2H, dt, J ¼ 1:2 Hz), 7.82 (2H, dd,
J ¼ 1:2 Hz), 7.58–7.36 (4H, m), 2.52 (3H, s).
½fðg6-p-cymeneÞRuðl-ClÞg2Cl2ꢂ
L2
!½ðg6-p-cymeneÞRuClðL2Þꢂþ
L2 ¼ 2,20-biquinoline (2,20-biqui) (3), 2,9-dimethyl 4,7-
diphenyl-phenanthroline (ddp) (4), 2,3-bis(a-pyr-
idyl)quinoxaline (bpq) (5).
The reaction of p-cymene dimer with two and half
fold excess of bpq in methanol in refluxing condition
1
yielded two compounds, the H NMR spectrum of the
3. [(OMe-phterpy)2Ru](BF4)2. Yield: 0.127 g, 40.83%
(from 1), UV–Vis(1 ꢁ 10ꢀ3 M, CH3CN): kmax 482
nm. Anal. Calc. for C40H34BF4N6O2Ru: C, 55.42;
H, 3.56; N, 8.85. Found C, 55.48; H, 3.60; N,
main product showed unsymmetrical splitting pattern
of the bpq ligand in aromatic region which suggests
the compound to be a mononuclear complex [(g6-p-
cymene)RuCl(bpq)]þ (5). The byproduct, which could
also be isolated from the reaction between p-cymene
dimer and bpq in 1:1 molar ratio, showed six distinct
peaks in the aromatic region apart from the charac-
teristic signals for the p-cymene moiety. The integra-
tion of the spectrum suggests the compound to
be binuclear ligand bridged compound of the formula
[{(g6-p-cymene)RuCl}2(bpq)](PF6)2 (6) as shown
below.
1
8.91%. H NMR {d, (CD3)2CO}: 9.40 (2H, s), 9.07
(2H, d, J ¼ 8:1 Hz), 8.36 (2H, d, J ¼ 8:7 Hz), 8.08
(2H, dt, 1.2 Hz), 7.82 (2H, dd, J ¼ 0:9 Hz), 7.36–
7.28 (4H, m), 3.99 (3H, s).
2.7. Crystal structure determination of 3 and 5
A suitable size crystal was mounted on the end of
the glass fiber and mounted on a Nonius MACH3

3158
R. Lalrempuia, M. Rao Kollipara / Polyhedron 22 (2003) 3155–3160
Table 1
Summary of structure determinations of compounds 3 and 5
Complex 3
28H26CIF6N2PRu
Complex 5
Empirical formula
Formula weight
Temperature (K)
C
C28H26CIF6N4PRu
700.02
293 (2)
671.99
293 (2)
0.70930
monoclinic,
P21/n
ꢀ
Wavelength (A)
0.70930
monoclinic,
P21/n
Crystal system,
space group
Unit cell dimensions
ꢀ
a (A)
ꢀ
12.47 (5)
15.22 (5)
13.96 (5)
94.3 (2)
9.9920 (11)
16.3600 (15)
17.6190 (12)
95.406 (7)
b (A)
ꢀ
c (A)
b (°)
3
ꢀ
Volume (A )
2641 (17)
4, 1.687
2867.4 (5)
4, 1.622
Z, Dcalc (M g/m3)
Absorption coefficient (mmꢀ1
F ð000Þ
)
0.820
1348
0.761
1408
Crystal size (mm)
0.4 ꢁ 0.35 ꢁ 0.35
1.98–24.92
0.35 ꢁ 0.20 ꢁ 0.15
1.70–24.93
h Range for data collection (°)
Index ranges
0 6 h 6 14, 0 6 k 6 18,
ꢀ16 6 l 6 16
0 6 h 6 11, 0 6 k 6 19,
ꢀ20 6 l 6 20
4272 / 4272 ½RðintÞ ¼ 0:0000ꢂ
24.93–81.7%
Psi-scan
Reflections collected/unique
Completeness to 2h ¼
4041/4041 ½RðintÞ ¼ 0:0000ꢂ
24.92–83.8%
Psi-scan
Absorption correction
Maximum and minimum transmission
Refinement method
1.000 and 0.797
full-matrix least-squares F 2
4041/0/352
1.000 and 0.904
Data/restraints/parameters
Goodness-of-fit on F 2a
4272/0/450
1.059
1.653
b
Final R indices ½I > 2rðIÞꢂ
R1 ¼ 0:1313, wR2 ¼ 0:3402
R1 ¼ 0:1444, wR2 ¼ 0:3600
4.278 and )2.858
R1 ¼ 0:0457, wR2 ¼ 0:1088
R1 ¼ 0:0618, wR2 ¼ 0:1203
0.659 and )0.558
R indices (all data)
Largest differential peak and hole (e A
ꢀ3
ꢀ
)
P
a GOF ¼ f wðFo2 ꢀ Fc2Þ =ðn ꢀ pÞg1=2, where n ¼ the number of reflections and p ¼ the number of parameters refined.
2
P
P
P
P
2
2 1=2
b R1 ¼ jjFoj ꢀ jFcjj= jFoj wR2 ¼ f wðFo2 ꢀ Fc2Þ = wðFo2Þ g
.
Fig. 1. ORTEP drawing of the compound 3 with 50% probability
thermal ellipsoids. Hydrogen atoms and PF6 omitted for clarity.
The 1H NMR spectra of the complexes 4 and 5
exhibited the resonance of the methyl protons of iso-
propyl group as two doublets at around 1.32 and 1.13
Fig. 2. ORTEP drawing of the compound 5 with 50% probability
thermal ellipsoids. Hydrogen atoms and PF6 omitted for clarity.

R. Lalrempuia, M. Rao Kollipara / Polyhedron 22 (2003) 3155–3160
3159
Table 2
stretching vibrations, these values are slightly higher
compared to the values observed for the closely related
complexes [6].
6
ꢀ
Bond lengths [A] and angles [°] for [(g -cymene)Ru(biqui)Cl]PF6 (3)
Bond lengths
Ru(1)–N(1)
Ru(1)–C(8)
Ru(1)–C(7)
Ru(1)–C(9)
Ru(1)–Cl(1)
C(4)–C(5)
C(6)–C(7)
C(8)–C(9)
2.101(12)
2.157(15)
2.193(14)
2.210(14)
2.388(8)
Ru(1)–N(2)
Ru(1)–C(6)
Ru(1)–C(5)
Ru(1)–C(4)
C(4)–C(9)
C(5)–C(6)
C(7)–C(8)
2.126(10)
2.174(13)
2.196(14)
2.243(14)
1.371(19)
1.395(18)
1.432(17)
It was observed that the MLCT band of complex
6 shows considerable red shift compared to the
mononuclear complex 5. The red shift in the position
of Ru ! bpq CT transition towards lower energy
may result from the stabilization of bpq pꢃ orbital
upon coordination to the second ruthenium center
[15].
1.392(18)
1.395(19)
1.412(17)
The complex [{(g6-C6Me6)Ru(l-Cl)}2Cl2] (2) was
also prepared by the arene displacement reaction start-
ing from p-cymene dimer with hexamethylbenzene in
refluxing diethylene glycol dimethyl ether (diglyme). The
literature method sometimes resulted in the decomposed
product. The desired compound was successfully iso-
lated but in unrepeatable low yield.
Terpyridines in principle can bind metals in bid-
entate fashion leaving one pyridyl ring uncoordinated
[3,4] and also as monodentate or tridentate or as
bridging ligand. The reaction of complex 1 with
stoichiometric or excess amount of para substituted
phenylterpyridines in different solvents viz, acetoni-
trile, benzene, chloroform, ethanol, methanol, and
diethylether at room temperature or refluxing
condition resulted only in the facile displacement of
the p-cymene ring as well as the chloride ligands. The
1H NMR data, far IR spectra suggested the absence
of p-cymene ring and halide ligand in these complexes
and analytical data indicated the products as a well
known dicationic complexes of the type [(x-phterpy)2
Ru]2þ. The reaction between these ligands and 2 also
resulted in the similar products.
Bond angles
N(1)–Ru(1)–N(2)
N(2)–Ru(1)–Cl(1)
N(1)–Ru(1)–Cl(1)
76.6(4)
86.4(3)
87.8(3)
Table 3
Selected bond lengths [A] and angles [°] for [(g6-cym-
ene)Ru(bpq)Cl]PF6 (5)
ꢀ
Bond lengths
Bond angles
Ru(1)–N(1)
Ru(1)–N(2)
Ru(1)–C(20)
Ru(1)–C(21)
Ru(1)–C(22)
Ru(1)–C(23)
Ru(1)–C(24)
Ru(1)–C(25)
Ru(1)–Cl(1)
C(20)–C(21)
C(20)–C(25)
C(21)–C(22)
C(22)–C(23)
C(23)–C(24)
C(24)–C(25)
2.059(4)
2.089(4)
2.239(6)
2.183(6)
2.184(6)
2.194(6)
2.165(6)
2.208(6)
2.3804(15)
1.423(9)
1.376(9)
1.395(9)
1.428(9)
1.391(9)
1.409(9)
N(1)–Ru(1)–N(2)
N(1)–Ru(1)–Cl(1)
N(2)–Ru(1)–Cl(1)
76.17(17)
84.61(13)
87.67(13)
ppm, respectively, and more than two sets of doublets
for the p-cymene ring protons at around 6 ppm which
could be due to loss of planarity of the cymene ring
because of steric ligands. This splitting pattern is solely
due to the nature of the incoming ligands. Complex 3
exhibited the resonance of methyl protons of the iso-
propyl group as a doublet at 0.79 ppm and p-cymene
ring protons appeared as two sets of doublet at 5.72
and 5.57 ppm, respectively. The far infrared spectra of
these complexes showed bands at around 304–310
3.1. Crystal structure
Single crystal X-ray structure determinations were
carried out for complexes 3 and 5 (Figs. 1 and 2) for
confirmation of the formulation. However, the low ac-
curacy of the result from 3 would render a discussion of
the metrical parameters meaningless. The data collection
parameters are listed in Table 1 and bond lengths and
bond angles are listed in Tables 2 and 3. The ruthenium
atom is bonded to the two nitrogen atoms of the ligand,
one chloride ligand and to a p-cymene group through the
cmꢀ1
,
which were assigned to terminal
m
ðRu–ClÞ

3160
R. Lalrempuia, M. Rao Kollipara / Polyhedron 22 (2003) 3155–3160
[2] (a) C.S. Allardyce, P.J. Dyson, D.J. Ellis, S.L. Heath, Chem.
Commun. (2001) 1396;
six carbon atoms. The geometry about the metal atom can
be regarded as distorted octahedral if the g6-cymene
group is assumed to occupy three facial coordinated po-
sitions. In complex 5, the average Ru–C bond length is
(b) H. Chen, J.A. Parkinson, S. Parsons, R.A. Coxall, R.O.
Gould, P.J. Sadler, J. Am. Chem. Soc. 124 (2002) 3064;
(c) R.E. Aird, J. Cummings, A.A. Ritchie, M. Muir, R.E. Morris,
H. Chen, P.J. Sadler, D.I. Jodrell, Br. J. Cancer 86 (2002)
1652;
ꢀ
2.195 A with Ru–C(20) and Ru–C(25) bond distances
slightly longer than the rest. The average C–C distance is
(d) R.E. Morris, R.E. Aird, P. del S. Murdoch, H. Chen, J.
Cummings, N.D. Hughes, S. Parsons, A. Parkin, G. Boyd, D.I.
Jodrell, P.J. Sadler, J. Med. Chem. 44 (2001) 3616.
[3] (a) K.M. Rao, E.K. Rymmai, Polyhedron 22 (2003) 307;
(b) K.M. Rao, C.R.K. Rao, P.S. Zacharias, Polyhedron 16 (1997)
2369.
ꢀ
1.399 A with alternate short and long bond length.
ꢀ
The Ru–Cl(1) bond length is 2.3804 A, which falls
within the usual range of Ru–Cl bond distance [16]. The
bite angle of the chelating ligand is 76.12°(17). The two
Ru–N bond lengths are slightly different (2.059 and
[4] H. Aneetha, P.S. Zacharias, B. Srinivas, G.H. Lee, Y. Wang,
Polyhedron 18 (1998) 299.
ꢀ
2.089 A). The bond angles of N(1)–Ru–Cl(1) and N(2)–
Ru–Cl(1) are 84.61(3)° and 87.67(3)°, respectively, in-
dicating the three legged piano stool type structure of
the compound.
[5] J.P. Sauvage, J.P. Collin, J.C. Chambron, S. Guillerez,
C. Coudret, V. Balzani, F. Barigelletti, L.D. Cola, L. Flamigni,
Chem. Rev. 94 (1994) 993, and the references cited
therein.
[6] (a) D.R. Robertson, I.W. Robertson, T.A. Stephenson, J.
Organomet. Chem. 202 (1980) 309;
4. Supplementary material
(b) H. Monjushiro, K. Harada, M. Nakaura, N. Kato, M.A.
Haga, M.F. Ryan, A.B.P. Lever, Mol. Cryst. Liq. Cryst. Sci.
Technol. A 15 (1997) 294.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre (CCDC), CCDC No. 196366 for complex 3
and 209301 for complex 5. Copies of this information
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
or www: http://www.ccdc.cam.ac.uk).
[7] (a) M.A. Bennett, T.N. Huang, T.W. Matheson, A.K. Smith,
Inorg. Synth. 21 (1985) 75;
(b) M.A. Bennett, T.W. Matheson, G.B. Robertson, A.K. Smith,
P.A. Tucker, Inorg. Chem. 10 (1980) 1014.
[8] H.A. Goodwin, F. Lions, J. Am. Chem. Soc. 81 (1959)
6415.
[9] E.C. Constable, J. Lewis, M.C. Liptrot, P.R. Raithby, Inorg.
Chim. Acta 178 (1990) 47.
[10] V.W. Spahni, G. Calzaferri, Helv. Chim. Acta 67 (1984) 450.
[11] R.A. Jacobsen, REQAB4, 1994, private communication.
[12] SIR 92: A. Altomare, M.C. Burla, M. Camalli, M. Cascarano, C.
Giacovazzo, A. Guagliardi, G. Polidoro, J. Appl. Cryst. 27 (1994)
435.
Acknowledgements
K.M.R. is grateful to DST (DST SERC:SP/S1/F-22/
98), New Delhi for financial support. We also thank the
Shaikh M. Mobin and Professor P. Mathur, National
Single Crystal X-ray facility, IIT Bombay, for their help
in solving the molecular structures.
[13] G.M. Sheldrick, SHELXL-93: Program for the Refinement
€
of Crystal Structures, University of Gottingen, Germany,
1993.
[14] C.K. Johnson, ORTEP-II: A Fortran Thermal Ellipsoid Plot
Program for Crystal Structure Illustrations, ORNL-5138,
1976.
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