Reactivity studies of η5- indenyl and η5- Cp* ruthenium(II) complexes towards some polypyridyl ligands

Article abstract of DOI:10.1002/zaac.200500301

The reaction of [(η⁵-L³)Ru(PPh₃) ₂Cl], where; L³ = C₉H₇ (1), C ₅Me₅ (Cp*) (2) with acetonitrile in the presence of [NH₄][PF₆] yielded

Full text of DOI:10.1002/zaac.200500301

DOI: 10.1002/zaac.200500301
Reactivity Studies of η5- Indenyl and η5-Cp* Ruthenium(II) Complexes towards
some Polypyridyl Ligands
Keisham Sarjit Singha, Yurij A. Mozharivskyjb, and Mohan Rao Kolliparaa,*
a Shillong / India, North-Eastern Hill University, Department of Chemistry
b Ames, IA / USA, Iowa State University of Science and Technology, Ames Laboratory
Received July 9th, 2005.
Abstract. The reaction of [(η5-L3)Ru(PPh3)2Cl], where; L3 ϭ C9H7
(1), C5Me5 (Cp*) (2) with acetonitrile in the presence of [NH4][PF6]
yielded cationic complexes [(η5-L3)Ru(PPh3)2(CH3CN)][PF6]; L3ϭ
C9H7 ([3]PF6) and L3 ϭ C5Me5 ([4]PF6), respectively. Complexes
[3]PF6 and [4]PF6 reacts with some polypyridyl ligands viz, 2,3-
bis (α-pyridyl) pyrazine (bpp), 2,3-bis (α-pyridyl) quinoxaline (bpq)
(tptz) or tetra-2-pyridyl-1,4-pyrazine (tppz) leads to the formation
of unexpected complexes [Ru(PPh3)2(L2)(CH3CN)][PF6]2; L2
ϭ
tppz ([9](PF6)2), tptz ([11](PF6)2) and [Ru(PPh3)2(L2)Cl][PF6];
L2 ϭ tppz ([10]PF6), tptz ([12]PF6). The complexes were isolated
as their hexafluorophosphate salts. They have been characterized
on the basis of micro analytical and spectroscopic data. The crystal
structures of the representative complexes were established by X-
ray crystallography.
yielding
the
complexes
of
the
formulation
[(η5-
L3)Ru(PPh3)(L2)]PF6 where; L3 ϭ C9H7, L2 ϭ bpp, ([5]PF6), L3 ϭ
C9H7, L2 ϭ bpq, ([6]PF6); L3 ϭ C5Me5, L2 ϭ bpp, ([7]PF6) and
bpq, ([8]PF6), respectively. However reaction of [(η5-
C9H7)Ru(PPh3)2(CH3CN)][PF6] ([3]PF6) with the sterically de-
manding polypyridyl ligands, viz. 2,4,6-tris(2-pyridyl)-1,3,5-triazine
Keywords: Ruthenium; Indenyl; Crystal structure; Triazine; Pyra-
zine
1 Introduction
We had earlier reported the syntheses of indenyl, penta-
methylcyclopentadienyl ruthenium complexes containing N,
N donor Schiff’s base [10] and azine ligands [11]. In con-
tinuation of our study, here we wish to report the reaction
of [(η5-C9H7)Ru(PPh3)2(CH3CN)][PF6] ([3]PF6) and [(η5-
C5Me5)Ru(PPh3)2(CH3CN)][PF6] ([4]PF6) with some poly-
pyridyl ligands viz, 3-bis (α-pyridyl) pyrazine (bpp), 2,3-bis
(α-pyridyl) quinoxaline (bpq), 2,4,6-tris(2-pyridyl)-1,3,5-
triazine (tptz), tetra-2-pyridyl-1,4-pyrazine (tppz). The li-
gands involve in the study are shown in scheme 1. In the
case of reaction of [η5-CpRu(PPh3)2Cl] with tppz and tptz,
we obtained the complexes of the type [CpRu(PPh3)(L2)]ϩ;
(L2 ϭ tppz or tptz ligand), where the Cp ligand remain
intact to metal [12]. In contrast, in this present study the
reaction of [(η5-C9H7)Ru(PPh3)2(CH3CN)][PF6] ([3]PF6)
with tppz or tptz ligand, we isolated unexpected complexes
Cyclopentadienyl ruthenium(II) bisphosphine complexes
[CpЈRu(PPh3)2Cl] (CpЈ ϭ Cp, Cp*, indenyl) have been im-
mense interest owing to their high reactivity [1], catalytic
activity [2] and interesting reactions towards some terminal
alkynes [3, 4]. An extensive studied have been carried out
on the cyclopentadienyl bisphosphine ruthenium complexes
[5Ϫ7]. In contrast, the analogous indenyl and Cp* com-
plexes have not been much studied. Literature survey re-
veals that most of the reaction on indenyl and Cp*ru-
thenium(II) phosphine complexes [(η5-C9H7)Ru(L)2Cl]
(where, L ϭ PPh3, PMe2Ph, PMePh2) are centered on the
reactions towards terminal acetylenes [3, 4]. However, the
reaction of the complex [(η5-L3)Ru(PPh3)2Cl] with N-base
ligands are virtually unknown except a few report of such
complexes appeared in the recent years [8]. It is noteworthy
that complexes of indenyl and Cp* are differ from the anal-
ogous cyclopentadienyl complexes in certain aspects such
as higher reactivity and labile nature of the organic moieties.
The higher reactivity of indenyl complexes is attributed to
the ring slippage nature from η5- to η3- and back to η5 of
the indenyl ligand [9].
[Ru(PPh3)2(L3)(CH3CN)]2ϩ
and
[Ru(PPh3)2(L3)(Cl)]ϩ
(L3 ϭ tppz or tptz). The complexes were fully characterized
by elemental analyses, 1H, 31P{1H} NMR spectroscopy.
The molecular structures of the compound ([9](PF6)2)
and ([12]PF6) have been determined by X-ray crystallogra-
phy.
2 Results and Discussion
2.1 Reaction of ([3]PF6) or ([4]PF6) with bpp and
bpq
* Dr. Mohan Rao Kollipara
Department of Chemistry, North-Eastern Hill University
Shillong-793022 / India
Tel. No. ϩ91 364 272 2620; Fax no. ϩ91 364 2550076
e-mail: kmrao@nehu.ac.in
mohanraokollipara@yahoo.com
The reaction of ([3]PF6) or ([4]PF6) with excess of bpp or
bpq ligand in refluxing methanol affords the complexes
[(η5-L3)Ru(PPh3)(L2)][PF6] (scheme 2) as the only product
172
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Reactivity Studies of η5- Indenyl and η5-Cp* Ruthenium(II) Complexes
1.33 in the complexes ([6]PF6) and ([8]PF6) corresponding
to the protons of Cp* ligand. The resonances for the coor-
dinated ligand and triphenylphosphine appeared in the
range of δ 9.64-6.29. The 31P{1H} NMR of the indenyl
complexes were resonate at a lower field at δ 56.25 as com-
pared to the analogous Cp* complexes where the signal ap-
peared at δ 45.19. A septet observed at δ-142 (JP-F
ϭ
712 Hz) is assignable to the [PF6]Ϫ ion.
2.2 Reaction of ([3]PF6) with tppz and tptz
The reaction of [(η5-C9H7)Ru(PPh3)2(CH3CN)][PF6]
([3]PF6) with terakis-2- pyridyl-1,4- pyrazine (tppz) and
2,4,6-Tris(2-pyridyl)-1,3,5-triazine (tptz) are solvent depen-
dent. The reaction of ([3]PF6) with tppz or tptz in re-
fluxing methanol for 4 to 5 h afforded a coordination com-
pound of formulation [Ru(PPh3)2(tppz)(CH3CN)]2ϩ
Scheme 1
([9](PF6)2)
and
[Ru(PPh3)2(tptz)(CH3CN)]2ϩ
([11](PF6)2), respectively as depicted in scheme 3. Under
similar condition, reaction of ([4]PF6) with tppz or tptz
did not obtained any characterizable product. Because of
the ill resolved NMR data of these products we are unable
to precise interpretation of the different signals in these
complexes. However, a similar type of complexes as shown
in scheme 3 seems to be obtained in this case also as evident
from the pattern of NMR spectrum. The complexes
([9](PF6)2) and ([11](PF6)2) were obtained as a result of
displacement of indenyl group by tppz or tptz ligands.
There are some reports available on such displacement of
organic moiety in half sandwich complexes. The most
prominent example is Berke and coworkers work, where
chelating diphosphines displaced cyclopentadienyl ligand
[13]. It is notable that indenyl ligands are more prone to
such displacement by sterically demanding ligands than the
Cp ligand due to the known indenyl effect, that is partial
decoordination to an η3-mode due to the gain of aromatic
resonance energy of the adjacent six membered ring. Inter-
estingly, use of dichloromethane and toluene mixture in-
stead of methanol as reaction medium afforded a chlori-
nation products [Ru(PPh3)2(tppz)Cl]ϩ ([10]PF6) and
[Ru(PPh3)2(tptz)Cl]ϩ ([12]PF6) where the indenyl group
have been displaced by the incoming ligand and sub-
sequently chlorination of the product by the chlorine gener-
ated from the dichloromethane. It is possible that a coord-
inatively unsaturated or coordinatively labile complex may
readily abstract a chlorine atom from dichloromethane to
give chlorinated complex. It is also known that 16 valence
electron complex [RuCl(dppe)2]ϩ revert to the correspond-
ing dichloride [RuCl2(dppe)2] when kept in CH2Cl2 and the
acetonitrile complex, [Ru(dppm)2Cl(CH3CN)]ϩ when re-
duced in CH2Cl2 gives the cis and trans dichloride cis
[Ru(dppm)2Cl2] and trans [Ru(dppm)2Cl2] [14].
in quantitative yield. The complexes can also be prepared
in dichloromethane:benzene mixture (1:10 v/v). The com-
plexes are air stable in solid state and soluble in chlorinated
solvents such as dichloromethane, chloroform, etc. The
electronic spectra of the complexes in dichloromethane (ca
10Ϫ4) show absorption bands in the region 490-510 nm.
This low energy transition is assignable to metal to ligand
{Ru (dπǞ(Lπ)} charge transfer transition (MLCT). The
compounds were characterized on the basis of microanaly-
ses and NMR spectroscopy. The microanalytical data of the
complexes are well consistent with the proposed structures.
The proton NMR spectra of the complexes exhibit reson-
ance for aromatic protons and ligands apart from indenyl
and Cp* protons which are consistent with the proposed
structures.
The proton NMR of the complexes ([5]PF6) and
([7]PF6) display a triplet at δ 4.75 and δ 5.07 and a doublet
at δ 4.54 and 4.97 for the proton of H-2 (JHH ϭ 2.74-
3.42 Hz) and H-1,3 (JHH ϭ 2.16-2.84 Hz) of the indenyl
ligand, respectively. A single resonance was observed at d
Notably in our previous studies, we had described the
reaction of [CpRu(PPh3)2Cl] with tppz and tptz lignad to
gave complex of the type [CpRu(PPh3)(L2)]ϩ; L2 ϭ tppz or
tptz ligand, where the Cp ligand remain intact to the metal
atom [12]. In contrast, in the present case our attempt to
Scheme 2
Z. Anorg. Allg. Chem. 2006, 172Ϫ179
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zaac.wiley-vch.de
173

K. S. Singh, Y. A. Mozharivskyj, M. R. Kollipara
syntheses
corresponding
indenyl
complex
[(η5-
ind)Ru(PPh3)(L2)]ϩ, by reacting complex ([3]PF6) with
tppz or tptz were unsuccessful instead we isolated com-
plexes without the organic moiety ([9](PF6)2)
Ϫ
([12]PF6). This suggests a more labile nature of indenyl as
compared to analogous cyclopentadienyl ligand that steri-
cally demanding tppz or tptz ligand readily displaced it
from the complex. However, our recent studies on the reac-
tion of ([3]PF6) or ([4]PF6) with less steric N-base ligands
such as bipyridine, phenanthroline [8] and NN/ donor schiff
base [10] and azine ligands [11] yielded corresponding N-
chelated η5-indenyl and η5-Cp* ruthenium complexes. This
observation showed that steric factor of the ligand could
play an important role in the stability of the indenyl moiety.
It can be conclude that reaction of ([3]PF6) with less steric
ligand does not displaced the indenyl group while with
sterically demanding ligand displace indenyl group from the
complex. The complexes ([9](PF6)2)-([12]PF6) were sol-
uble in chlorinated solvents and they were isolated by col-
umn chromatography technique in fairly good yield as a
major product. In each case a comparatively less quantity
of minor product obtained were not characterized. The
compounds were spectroscopically characterized and the
structures of ([9](PF6)2) and ([12]PF6) were confirmed by
X-ray analyses. In the proton NMR spectra of the com-
plexes the characteristic indenyl protons H2 and H1,3 does
not found indicating the absence of the indenyl ligand in
the complex. Further, the proton NMR spectrum suggests
the symmetrical coordination of this ligand to the metal
atom i.e. three nitrogen chelate to the ruthenium atom. The
resonance for the protons of the coordinated ligand and
triphenylphosphine appeared in the range of δ 7.41-9.16.
The 31P{1H} NMR spectra of the compounds showed a
single resonance at δ 24.84 ([9](PF6)2), 24.98 ([10]PF6),
28.62 ([11](PF6)2) and 13.80 ([12]PF6), respectively. The
most remarkable feature of the 31P{1H} NMR spectra is
the upfield shift of the resonance relative to the starting
complexes ([3]PF6) where the peak resonate at δ 48.29. The
upfield shift could be due to the substitution of the indenyl
ligand by the electron rich tppz or tptz ligands.
Scheme 3
of crystallographic data collection parameters are summar-
ized in Table 1. In this manuscript we present only the per-
spective view of the complex ([8]PF6) (figure 1) to support
the structure proposed by the spectroscopic data. In this
molecule the unit cell contains two molecules, which are
mirror images to each other. The centroid of Cp* ligand to
˚
ruthenium in the molecules are 1.849 and 1.864 A, respec-
The electronic spectra of the complexes displayed three
distinct peaks in the range of 430-495, 345-354 and 315-
318 nm. The low energy bands at 430-495 nm has been as-
signed to MLCT transition {Ru (dπǞ(Lπ))} while the ab-
sorption bands below 400 nm were composed of second
MLCT, ligand field or intra-ligand transitions (πǞπ*). The
analytical and spectroscopic data are well consisted with
the formulation of these compounds. The electrochemical
study of complex ([12]PF6) was carried out in dry aceto-
nitrile. The acetonitrile solution of ([12]PF6) showed a
quasireversible wave at Ϫ0.841 V (∆E ϭ 101.8 mv) is as-
signed to the RuII-RuIII couple [15].
tively. Due to not well defined of the atoms and poor qual-
ity of the crystals there is considerable error in the data and
the refined R value is above 10 %, so the discussion about
the crystal structure of this molecule ([8]PF6) in the manu-
script have been excluded.
3.1 Complex
[Ru(PPh3)2(tppz)(CH3CN)][PF6]2([9](PF6)2)
A perspective (ORTEP) [16] view of the complex cation
along with the atoms numbering scheme is shown in figure
2. Selected bond lengths and angles are presented in Table
2. The compound ([9](PF6)2) crystallize in P212121 space
group in orthorhombic unit cell. The coordination of the
ruthenium ion can be regarded as a distorted octahedron
formed by the coordination of tppz in η3-fashion in a plane
while the remaining coordination sites by the two tri-
3 Crystal Structures
Crystal structure determinations for the compound
([9](PF6)2) and ([12]PF6) have been carried out. Details
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Reactivity Studies of η5- Indenyl and η5-Cp* Ruthenium(II) Complexes
Figure 1 Molecular structure of complex (8[PF6])
phenylphosphine and acetonitrile ligand. It is notable that
the uncoordinated pyridyl rings are slightly twisted out of
the plane. The Ru-NCCH3 bond distance Ru-N(1)
Figure 2 Molecular structure of the compound [Ru(PPh3)2(tppz)
(CH3CN)][PF6]2, ([9](PF6)2) showing with 50 % probable thermal
ellipsoids. Phenyl rings of triphenylphosphine, hydrogen atoms and
PF6 ion have been omitted for clarity
˚
(2.071(3) A) is comparable to that of the other Ru-NCCH3
bond length [10a]. The ruthenium to coordinated nitrogen
˚
bond distances Ru-N(22) ((2.0884) A) and Ru-N(32)
˚
((2.0717) A), are comparable to those reported for Ru-nitro-
3.2 Complex [Ru(PPh3)2(tptz)Cl][PF6] ([12]PF6)
gen bond distances of tppz ligand [12]. The coordinated
tppz ligand formed two five member metallacycle rings. The
angle subtended by N(11)-Ru-N(22) and N(11)-Ru-N(32)
are 78° and 79.9°, respectively. The Ru-PPh3 bond dis-
The complex crystallizes in Pca21 space group. There are
two molecules (molecule A and molecule B) per unit cell. A
perspective view of the cationic part of the molecule B with
the atoms labeling scheme is shown in figure 3. Selected
bond lengths and angles for both the molecules are listed
˚
tances, Ru-P(1) and Ru-P(2) is 2.4494(9) and 2.4185(9) A
which are in the usual range of Ru-P bond distance [17].
Table 1 Summary of structure determination for complex ([9](PF6)2) and ([12]PF6)
Complex [9](PF6)2
Complex [12]PF6
Empirical formula
Formula weight
Temperature
C62H49F12N7P4Ru
1345.03
C54 H42 Cl F6 N6 P3 Ru
1118.37
293(2) K
183(2) K
˚
˚
Wavelength
0.71073 A
0.71073 A
Space group
Crystal system
Unit Cell dimension
P212121
orthorhombic
a ϭ 11.2994(7) A
b ϭ 23.1226(13) A
c ϭ 23.4581(13) A
6128.9(6) A
Pca21
orthorhombic
a ϭ 31.886(6) A
b ϭ 17.505(3) A
c ϭ 18.145(3) A
10128(3) A
˚
˚
˚
˚
˚
˚
3
3
˚
˚
Volume
Z
4
8
Density (calculated)
Absorption coefficient
F(000)
Crystal size
Theta range for data collection
Index ranges
1.458 Mg/m3
1.467 Mg/m3
0.442 mmϪ1
2728
0.523
4544
0.1 x 0.06 x 0.025 mm3
1.74 to 28.31°
Ϫ15<ϭh<ϭ14
Ϫ30<ϭk<ϭ30
Ϫ30<ϭl<ϭ31
53671
0.04 x 0.03 x 0.03
1.16 to 16.05°
Ϫ24<ϭh<ϭ24
Ϫ13<ϭk<ϭ13
Ϫ14<ϭl<ϭ13
20324
Reflections collected
Independent reflections
Completeness to theta
Absorption correction
Refinement method
Data / restraints / parameters
Goodness-of-fit on F2
Final R indices [I>2sigma(I)]
R indices (all data)
14481 [R(int) ϭ 0.0305]
ϭ 28.31°-96.9 %
Empirical
4906 [R(int) ϭ 0.0575
ϭ 16.05° to 98.5 %
Empirical
Full-matrix least-squares on F2
14481 / 12 / 590
1.006
Full-matrix least-squares on F2
4906 / 13 / 342
1.073
R1 ϭ 0.0496, wR2 ϭ 0.1300
R1 ϭ 0.0555, wR2 ϭ 0.1349
Ϫ0.01(3)
R1 ϭ 0.0857, wR2 ϭ 0.2096,
R1 ϭ 0.0996, wR2 ϭ 0.2228
0.45(11)
Absolute structure parameter
Largest diff. peak and hole
Ϫ3
Ϫ3
˚
˚
0.855 and Ϫ0.526 e.A
1.654 and Ϫ0.590 e.A
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175

K. S. Singh, Y. A. Mozharivskyj, M. R. Kollipara
in Table 3 The molecule A and Molecule B differ in the
orientation of the phenyl rings attached to the ruthenium
atom arises due to twisted in different direction with respect
to the rest part of the complex and also in the orientation
of the pyridine ring. The pyridine rings in molecule B is
twisted clockwise but in molecule A, it is twisted in counter
clockwise as nitrogen atom is concerned. The ruthenium
atom is hexa-coordinated with three coordination sites are
occupied by the tptz ligand in η3-mode, while two sites by
the P-atoms of the two triphenylphosphine and the remain-
ing one by the chlorine atom. The basal plane is formed
by three nitrogen atoms N(11B), N(21B), N(31B) and one
chlorine atom Cl(1B) which are coordinated to the ru-
thenium atom. Ru-N bond distances, Ru-N(31B) (2.145(5)),
˚
Ru-N(11B) (1.924(5)) A are in close agreement with those
of the related compound [18]. The Ru-P bond length, Ru-
˚
P(1), (2.440(6)) and Ru-P(2), (2.402(6)) A are similar with
Figure
3 Molecular structure of the compound [Ru(PPh3)2
that of complex ([9](PF6)2). The Ru-Cl bond length
2.453(6) A is in usual range of Ru-Cl bond length [19]. The
(tptz)Cl][PF6] ([12]PF6) showing with 50 % probable thermal ellip-
soids. Hydrogen atoms and PF6 ion have been omitted for clarity.
˚
coordinated tptz ligand forms two five member metallacycle
ring in a plane with bite angles of N (31B)-RuB-N (11B)
and N (21B)-RuB-N (11B) are 79.36(19)° and 77.53(19)°,
respectively.
4.1 Preparation of [(η5-
C9H7)Ru(PPh3)2(CH3CN)][PF6], ([3]PF6)
The complex [(η5-C9H7)Ru(PPh3)2Cl] (1) (100 mg,
0.128 mmol) and NH4PF6 (26 mg, 0.24 mmol) were re-
fluxed in 30 ml of acetonitrile for 2 hrs. Within a few mi-
nutes, the solution turned yellow and white solid was ap-
peared. The solution was filtered to remove the white solid
and the filtrate was rotary evaporated to dryness. The resi-
due was dissolved in dichloromethane and filtered into
50 ml of hexane, whereby the product precipitated out as a
yellow crystalline solid.
4 Experimental Section
The solvents were purified and dried by standard methods [20] and
reactions were carried out under dry nitrogen atmosphere. The
NMR spectra were recorded on Bruker ACF-300 and AMX-
400 MHz spectrometer reference to external SiMe4. The chemical
shift for 31P{1H} NMR were recorded reference to H3PO4 (85 %).
Coupling constants are given in hertz. UV-visible was recorded on
Hitachi-U-2300 spectrophotometer and Micro analytical data were
obtained from SAIF NEHU, Shillong, using a Perkin Elmer 2400
CHN/S analyzer. The CV was recorded on CHI 6208 instruments
Electrochemical analyzer in de-aerated acetonitrile in the presence
of 0.1 M tetrabutyl ammonium perchlorate (TBAP) as supporting
electrolyte, using three electrode assembly platinum working and
counter electrodes and Ag/AgCl as reference electrode. The ligands
2,3-bis(α-pyridyl)pyrazine (bpp), 2,3-bis(α-pyridyl)quinoxaline
(bpq), bis-pyridyl quinoxaline (bpq) and terakis pyridyl-1,4- pyra-
zine (tppz) were prepared by following a literature method [21]
while the ligand 2,4,6-Tris(2-pyridyl)-1,3,5-triazine (tptz) was pur-
chased from Loba Chemie (P) Ltd. and used as received. The start-
ing materials, [(η5-C9H7)Ru(PPh3)2Cl] (1) [22] and [(η5-
C5Me5)Ru(PPh3)2Cl] (2) [4] were prepared following the literature
methods while the precursor complexes [(η5-C9H7)Ru(PPh3)2
(CH3CN)]PF6 ([3]PF6) [22] and [(η5-C5Me5)Ru(PPh3)2(CH3CN)]
PF6 ([4]PF6) [23] were prepared by minor modifications of the
literature procedures as described below.
1H NMR (CDCl3, δ): 2.3 (s, 3H), 4.3 (d, 2H, indenyl),
4.8 (t, 1H, indenyl), 6.9 -7.8 (m, 34H). 31P{1H} NMR
(CDCl3, δ): 54.03 (s, PPh3); Ϫ142 (septet, PF6Ϫ, JPϪF
ϭ
711.39)
4.2 Preparation of [(η5-
C5Me5)Ru(PPh3)2(CH3CN)][PF6], ([4]PF6)
The complex [Cp*Ru(PPh3)2Cl] (0.1 g, 0.125 mmol) and NH4PF6
(0.041 g, 0.250 mmol) were refluxed in CH3CN (30 ml) for 2 hrs.
During this time the orange red suspension turned yellow and
white solid was appeared. The white solid was filtered off and the
˚
Table 3 Selected bond lengths /A and angles /° of the molecules A
and B for the complex ([12]PF6)
Molecule A
1.812(5)
2.106(5)
2.377(6)
2.166(5)
2.387(6)
2.434(6)
78.42(19)
77.42(19)
175.2(2)
90.1(2)
Molecule B
1.924(5)
2.145(5)
2.402(6)
2.116(5)
2.440(6)
2.453(6)
77.53(19)
79.36(19)
174.0(2)
85.7(2)
RuϪN(11)
RuϪN(31)
Ru-P(2)
Ru-N(21)
Ru-P(1)
˚
Table 2 Selected bond lengths /A and angles /° for the complex
([9](PF6)2)
Ru-N(1)
Ru-P(1)
Ru-N(32)
1.9285
2.4494(9)
2.0717
Ru-N(22)
Ru-P(2)
Ru-N(11)
2.0884
2.4185(9)
1.9285
Ru-Cl
N(11)-Ru-N(21)
N(11)-Ru-N(31)
P(1)-Ru-P(2)
P(1)-Ru-Cl
P(2)-Ru-Cl
N(1)-C(2)
C(2)-C(3)
N(11)-Ru-N(32)
N(32)-Ru-N(1)
1.480(6)
79.9
100.67(8)
N(22)-Ru-N(11)
N(22)-Ru-N(1)
P(1)-Ru-P(2)
78.8
100.74(8)
174.21(3)
86.7(2)
89.3(2)
176
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Reactivity Studies of η5- Indenyl and η5-Cp* Ruthenium(II) Complexes
4.3.4 Preparation of [(η5-
C5Me5)Ru(PPh3)(bpq)][PF6], ([8]PF6)
filtrate was rotary evaporated. The yellow residue was dissolved in
dichloromethane (5 ml) and filtered to remove NH4Cl and excess
NH4PF6. The filtrate on concentration to ca 5 ml and addition of
excess hexane gave yellow crystalline solid. The yellow solid was
collected and washed with hexane to afford 83 % yield of the com-
plex.
This complex was prepared in the same manner as described in
([7]PF6) using the complex ([4]PF6) instead of ([3]PF6). Yield:
82 mg, (84 %).
1H NMR (CDCl3, δ): 1.32 (s, 15 H, Cp*), 2.17 (s, 3H, CH3CN), 6.78 -7.83
(m, 30H).
31P{1H} NMR (CDCl3, δ): 45.28 (s, PPh3), Ϫ143 (septet, PF6Ϫ).
Anal. Calc. for C46H42N4P2F6Ru: C, 59.54; H, 4.53; N, 6.04 %.
Found: C, 59.23; H, 4.18; N, 5.84 %.
1H NMR (δ, CDCl3): 8.67 (d, 1H, JHH ϭ 5.66), 8.58 (d, 1H, JHH ϭ 4.68),
8.41 (d, 1H, JHH ϭ 8.36), 8.07 (t, 2H, JHH ϭ 4.92), 7.80 (t, 2H, JHH ϭ 7.04),
7.70 (m, 1H), 7.55 (t, 1H, JHH ϭ 8.16), 7.48-6.88 (m, 18H), 1.37 (s, 15H,
Cp*). Ϫ 31P{1H} NMR (δ, CDCl3): 44.76, Ϫ142.83, PF6, (JP-F ϭ 712). Ϫ
UV-vis (λmax, nm): 510.
4.3 Preparation ofcomplexes
4.3.1 Preparation of [(η5-
C9H7)Ru(PPh3)(bpp)][PF6], ([5]PF6)
The complex [(η5-C9H7)Ru(PPh3)2(CH3CN)]PF6, ([3]PF6)
4.3.5 Preparation of
[Ru(PPh3)2(tppz)CH3CN)][PF6]2, ([9](PF6)2)
(100 mg, 0.107 mmol), the ligand bpp (30 mg, 0.129 mmol) and
[(η5-
40 ml of methanol were mixed in round bottom flask. The resulting
mixture was heated to reflux for 4 h. The yellow orange suspension
turned into red brown color as the reaction progress. After refluxed
for 4 hrs the solution was cooled to room temperature then the
solvent was removed under reduced pressure. The brown residue
was extracted with dichloromethane and filtered through a short
column of silica gel. The filtrate on subsequent concentration to ca
5 ml and addition of excess hexane afforded red brown solid. Yield:
75 mg (81 %)
A
round
bottom
flask
was
charged
with
C9H7)Ru(PPh3)2(CH3CN)]PF6, ([3]PF6) (100 mg, 0.107 mmol),
tppz (0.202 mmol) and methanol (40 ml). The mixture was then
heated to reflux for 5 h under nitrogen atmosphere. The color of
the solution progressively changed from yellow orange to dark
brown as the reaction proceeded. The solution was cooled to room
temperature, and then the solvent was removed by rotary evapor-
ator. The residue was extracted with dichloromethane and poured
onto silica gel column. A dark brown color band collected using
dichloromethane/acetone mixture 1:5 (v/v) as an eluent. The solu-
tion was concentrated to ca. 5 ml and excess of hexane was added
whereby the compound precipitated out as dark brown solid. The
solid was washed with hexane 2x20 ml and dried under vacuum.
Yield: 84 mg (58 %).
Anal. Calc. for C41H32N4P2F6Ru: C, 57.40; H, 3.73; N, 6.53 %.
Found: C, 56.78; H, 3.98; N, 6.22 %.
1H NMR (δ, CDCl3): 9.64 (d, 1H, JHH ϭ 3.08), 9.52 (d, 1H, JHH ϭ 4.26),
8.62 (d, 1H, JHH ϭ 5.83), 8.34 (d, 1H, JHH ϭ 3.08), 7.93 (s, 1H), 7.71 (m,
2H), 7.69 (t, 1H, JHH ϭ 7.52), 7.68 (d, 1H, JHH ϭ 6.92), 7.55 (d, 1H, JHH ϭ
2.44), 6.91-7.51 (m, 17H), 6.56 (d, 2H, JHH ϭ 3.44), 4.75 (t, 1H, JHH
ϭ
3.42), 4.54 (d, 2H, JHH ϭ 2.84). Ϫ 31P{1H} NMR (δ, CDCl3): 56.68, Ϫ140.73
(sept., PF6, JP-F ϭ 716). Ϫ UV-vis (λmax, nm): 495.
Anal. Calc. for C62H49F12N7P4Ru: C, 55.31; H, 3.64; N, 7.28 %.
Found: C, 54.93; H, 3.86; N, 6.78 %.
1H NMR (δ, CDCl3): 9.28 (d, 1H, JHH ϭ 8.24), 8.95 (d, 1H, JHH ϭ 7.36),
8.69 (d, 1H, JHH ϭ 3.21), 8.66 (d, 1H, JHH ϭ 5.26), 8.59 (d, 1H, JHH
5.34), 8.42 (d, 1H, JHH ϭ 3.86), 8.36 (d, 1H, JHH ϭ 7.56), 8.28 (d, 1H,
HH ϭ 6.24), 8.08 (t, 2H, 7.64), 8.02 (t, 2H, JHH ϭ 5.43), 7.96 (m, 2H), 7.78-
6.73 (m, 28H), 6.75 (d, 1H, JHH ϭ 3.6), 6.73 (t, 1H, JHH ϭ 4.8), 6.57 (m,
1H), 6.49 (d, 1H, JHH ϭ 10.82), 2.75 (s, 3H). Ϫ 31P{1H} NMR (δ, CDCl3):
24.98, Ϫ140.19, PF6, (sept., JP-F ϭ 712). Ϫ UV-vis (λmax, nm): 435, 375,
345, 318.
ϭ
4.3.2 Preparation of [(η5-
C5Me5)Ru(PPh3)(bpp)][PF6], ([6]PF6)
J
This complex was prepared in analogy to ([5]PF6) using the com-
plex ([4]PF6) instead of complex ([3]PF6).
Yield: 76 mg (82 %).
Anal. Calc. for C42H40N4P2F6Ru: C, 57.46; H, 4.56; N, 6.38 %.
Found: C, 58.32; H, 4.22; N, 5.87 %.
1H NMR (δ, CDCl3): 8.90 (d, 1H, JHH ϭ 5.28), 8.61 (d, 1H, JHH ϭ 4.40),
8.57 (t, 1H, JHH ϭ 3.92), 8.47(s, 1H), 8.20 (t, 1H, JHH ϭ 7.60), 7.91-7.12
(m, 20H; 1.33 (s, 15H, Cp*). Ϫ 31P{1H} NMR 45.19, Ϫ142.71 (sept., PF6,
JP-F ϭ 712). Ϫ UV-vis (λmax, nm): 498.
4.3.6 Preparation of [Ru(PPh3)2(tppz)Cl][PF6],
([10]PF6)
The compound [(η5-C9H7)Ru(PPh3)2(CH3CN)]PF6, ([3]PF6)
(100 mg, 0.107 mmol) was initially dissolved in minimum amount
of dichloromethane and 40 ml of toluene was added. To this solu-
tion tppz (49 mg, 0.126 mmol) was added and the resulting mixture
was heated to reflux under nitrogen atmosphere for 5h. The reac-
tion mixture was cooled to room temperature and the solvent was
removed under reduce pressure. The residue was extracted with di-
chloromethane and chromatograph on silica gel column. A light
brown band was collected using dichloromethane: acetone mixture
(2:5 v/v) as eluent. A comparatively less amount of second band
collected by using methanol, as eluent was not characterized.
4.3.3 Preparation of [(η5-C9H7)
Ru(PPh3)(bpq)][PF6], ([7]PF6)
The complex was prepared in the same manner as described in
([5]PF6) using the ligand bpq (36 mg, 0.129 mmol) instead of bpp.
Yield: 77 mg (79 %).
Anal. Calc. for C45H34N4P2F6Ru: C, 59.40; H, 3.96; N, 6.16 %.
Found: C, 58.83; H, 4.12; N, 5.78 %.
Yield: 72 mg (56 %). Analytical Calc. for: C60H46F6N6P3Ru: C,
60.32; H, 3.85; N, 7.03 %.
1H NMR (δ, CDCl3): 9.51 (t, 1H, JHH ϭ 3.89), 9.03 (d, 1H, JHH ϭ 8.68),
8.64 (d, 1H, JHH ϭ 4.61), 8.02 (d, 1H, JHH ϭ 8.2), 7.91 (t, 1H, JHH ϭ 5.85),
7.80 (m, 2H), 7.61 (m, 1H), 7.20-7.55 (m, 17H), 6.95 (t, 2H, JHH ϭ 7.83),
6.74 (t, 2H, JHH ϭ 8.13), 6.49 (t, 1H, JHH ϭ 7.08), 6.29 (d, 1H, JHH ϭ 8.63),
5.07 (t, 1H, JHH ϭ 2.74), 4.97 (d, 2H, JHH ϭ 2.16). Ϫ 31P{1H} NMR (δ,
CDCl3): 56.25, Ϫ143, PF6, (sept., JP-F ϭ 712). Ϫ UV-vis (λmax, nm): 490.
Found: C, 59.27; H, 3.15; N, 6.82 %.
1H NMR (δ, CDCl3): 9.46 (d, 1H, JHH ϭ 4.8), 9.10 (d, 1H, JHH ϭ 15.32),
8.95 (d, 1H, JHH ϭ 5.08), 8.66 (d, 1H, JHH ϭ 4.24), 8.04 (t, 1H, JHH
1.76), 7.77 (d, 1H, JHH ϭ 7.72), 7.67 (d, 1H, JHH ϭ 8.32), 7.64 (d, 1H,
ϭ
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 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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177

K. S. Singh, Y. A. Mozharivskyj, M. R. Kollipara
JHH ϭ 6.96), 7.57 (t, 2H, JHH ϭ 6.74), 7.53 (t, 2H, JHH ϭ 7.52), 7.40 (m,
2H), 7.31(m, 2H), 7.29-6.74 (m, 28H), 6.22 (d, 2H, JHH ϭ 7.88). Ϫ 31P{1H}
5 Concluding Remarks
NMR (δ, CDCl3): 24.98, Ϫ142, (sept., PF6, JP-F ϭ 712). Ϫ UV-vis (λmax
nm): 430, 370, 354, 315.
,
Four new mononuclear indenyl and pentamethylcyclopen-
tadienyl ruthenium complexes and four coordination com-
plexes of some polypyridyl ligands have been prepared and
fully characterized. The study highlight the more labile nat-
ure of indenyl ligand as compared to analogous cyclopen-
tadienyl ligand that indenyl ligand is readily substituted by
sterically demanding tridentate N- base ligands such tppz
or tptz whereas under similar condition Cp ligand does not.
Further, with less steric N base ligand such as bpp or bpq
the indenyl group remains intact to the metal and forming
corresponding nitrogen chelated indenyl ruthenium com-
plexes. It can be concluded that reaction of complex
([3]PF6) with less steric ligand does not displaced the inde-
nyl group while with sterically demanding ligand displaced
indenyl group from the complex. Thus, the stabilty of inde-
nyl ligand is largely depend on the steric nature of the in-
coming ligand, sterically demanding N-base ligand dis-
placed it from the complexes while less sterically demanding
ligand, resulted N-chelated indenyl complexes.
4.3.7 [Ru(PPh3)2(tptz)CH3CN)][PF6]2,
([11](PF6)2)
This compound was prepared in analogy to that of compound
([9](PF6)2) using the ligand tptz instead of tppz. The compound
was obtained by column chromatography on silica gel column col-
lecting the red band using dichloromethane: acetone (2:6, v/v) as
eluent, the second purple band eluted with methanol was not
characterized.
Yield: 79 mg (58 %). Analytical Calc. for: C56H45F12N7P4Ru: C,
52.96; H, 3.54; N, 7.72 %.
Found: C, 53.28; H, 3.17, N, 7.34 %.
1H NMR (δ, CDCl3): 9.82 (d, 2H, JHH ϭ 5.7), 9.54 (d, 2H, JHH ϭ 4.2), 9.13
(d, 1H, JHH ϭ 5.5), 9.01(d, 2H, JHH ϭ 3.9), 8.94(m, 2H), 8.84 (m, 2H),
8.73(d, 1H, JHH ϭ 7.8), 8.55(d, 1H, JHH ϭ 11.6), 8.22 (d, 1H, JHH ϭ 8.9),
8.17-6.99 (m, 26H), 6.91 (d, 2H, JHH ϭ 6.2), 2.79 (s, 3H, CH3CN). 31P{1H}
NMR (δ, CDCl3): 28.62, Ϫ144.40 (sept., PF6, JP-F ϭ 713). Ϫ UV-vis (λmax
,
nm): 495, 354, 318.
Supplementary material: Crystallographic data for the structural
analysis have been deposited at the Cambridge Crystallographic
Data Centre (CCDC), CCDC No. 268654 for complex ([9](PF6)2)
and CCDC No. 268655 for complex ([12]PF6). Copies of this in-
formation may be obtained free of charge from the director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK (fax: ϩ44-
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
4.3.8 [Ru(PPh3)2(tptz)Cl)][PF6], ([12]PF6)
This complex was prepared by following a procedure as ([10]PF6)
using the ligand tptz instead of tppz. Following a work up as
([10]PF6), a brown color compound was collected using dichloro-
methane: acetone 2:5(v/v) as eluent. A comparatively less quantity
of purple color compound was isolated as the second band by using
methanol, as eluent was not characterized.
Acknowledgements. We thank the Sophisticated Instruments Fa-
cility, Indian Institute of Science, Bangalore for providing NMR
facility. We are grateful to R. F. Winter for his helpful discussions.
Yield: 74 mg (62 %). Analytical Calc. for: C54H42ClF6N6P3Ru:
57.94; H, 3.75; N, 7.51
Found: C, 57.28; H, 3.96; N, 7.24 %.
1H NMR (δ, CDCl3): 9.15 (d, 2H, JHH ϭ 5.3), 8.94 (d, 2H, JHH ϭ 4.3), 8.80
(d, 1H, JHH ϭ 5.2), 8.58 (d, 2H, JHH ϭ 7.2), 8.16 (m, 1H), 7.98(d, 1H,
JHH ϭ 7.3), 7.94 (t, 2H, JHH ϭ 7.3), 7.62 (m, 2H), 7.41(d, 2H, JHH ϭ 5.8),
7.39-6.93 (m, 27H). Ϫ 31P{1H} NMR (δ, CDCl3): 13.80, Ϫ142 (sept., PF6,
JP-F ϭ 711). Ϫ UV-vis (λmax, nm): 480, 328, 315.
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