Synthesis and spectroscopic properties of cationic Ru(II) arene complexes [Ru(η6-arene)(P)Cl(L)]+. (P=PPh3, PEt3, MePPri2 and L=4-cyanopyridine or 1,4-dicyanobenzene)

Article abstract of DOI:10.1016/S0022-328X(00)00258-8

Reactions of [Ru(η⁶-arene)(P)Cl₂] (P=PPh₃, PEt₃ or MePPrⁱ₂) with organonitriles 4-cyanopyridine or 1,4-dicyanobenzene (referred hereafter as CNPy or DCB) in methanol, in the presence of NH₄PF₆, gives the cationic arene complexes [Ru(η⁶-arene)(P)Cl(L)]⁺ (L=CNPy or DCB). The reaction products have been characterized by physico-chemical methods viz., elemental analyses, IR, ¹H-, ¹³C-, ³¹P-NMR, electronic and FAB mass spectra. The spectral data of the complexes revealed the presence of a pendant nitrile group. These could behave as potential metallo-ligands and could find wide application in the syntheses of homo- or heterobimetallic mixed valence bridged complexes.

Full text of DOI:10.1016/S0022-328X(00)00258-8

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 605 (2000) 74–81
Synthesis and spectroscopic properties of cationic Ru(II) arene
complexes [Ru(h6-arene)(P)Cl(L)]+. (P=PPh3, PEt3, MePPri2 and
L=4-cyanopyridine or 1,4-dicyanobenzene)
Anupam Singh a, Abhaya Nand Sahay a, Daya Shankar Pandey a,*,
M. Carmen Puerta b, P. Valerga b
a Department of Chemistry, A.P.S. Uni6ersity, Rewa 486003, India
b Departamento de Quimica Inorganica, Uni6ersidad de Cadiz, Apartado 40, Puerto Real 11510, Spain
Received 21 January 2000; accepted 20 April 2000
Abstract
Reactions of [Ru(h6-arene)(P)Cl2] (P=PPh3, PEt3 or MePPri2) with organonitriles 4-cyanopyridine or 1,4-dicyanobenzene
(referred hereafter as CNPy or DCB) in methanol, in the presence of NH4PF6, gives the cationic arene complexes [Ru(h6-
arene)(P)Cl(L)]+ (L=CNPy or DCB). The reaction products have been characterized by physico-chemical methods viz.,
1
elemental analyses, IR, H-, 13C-, 31P-NMR, electronic and FAB mass spectra. The spectral data of the complexes revealed the
presence of a pendant nitrile group. These could behave as potential metallo-ligands and could find wide application in the
syntheses of homo- or heterobimetallic mixed valence bridged complexes. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Ruthenium arene complexes; 4-Cyanopyridine; 1,4-Dicyanobenzene; Metallo-ligands; Synthon
lations [Ru(h6-arene)Cl2(L)] and [{Ru(h6-arene)Cl2}2(m-
1. Introduction
L)], whereas its reaction with dicyano trans-2-butene
gives only binuclear complexes [{Ru(h6-arene)Cl2}2(m-
Recently, considerable attention has been paid to the
synthesis and characterization of homo- and hetero-
polynuclear complexes owing to their potential use in
photochemical molecular devices and as light sensitive
DCBT)] [5]. Reactions of these organonitriles with
closely related phosphine containing complexes [Ru(h6-
arene)Cl2(L)] (L=PPh3, AsPh3, PMe3 or MeP(Pri)2]
have not been studied. Because of our continuing inter-
probes in biological systems [1–3]. In this regard,
est in this area, we decided to carry out a detailed study
organonitriles viz., 4-cyanopyridine (CNPy), 1,4-di-
of the reactivity of [Ru(h6-arene)Cl2(L)] (L=PPh3,
cyanobenzene (DCB), 1,4-dicyano-trans-2-butene, 1,4-
AsPh3, PMe3 or MeP(Pri)2) with the organonitriles like
dicyanopiperazinedicarbonitrile, etc., have received
CNPy and DCB. Our prime concern in undertaking
special attention [4]. Interest in these ligands stems from
this study was: (a) to investigate the stretching fre-
the presence of the two donor sites, which raises the
quency of the nitrile group of the organonitrile when it
possibility of formation of mono- and binuclear com-
is bound to electron rich metal centres in mononuclear
plexes. Recently, we have shown that the reaction of
and binuclear complexes; (b) to investigate how bridg-
dimeric chloro-bridged Ru(II) complexes [{Ru(h6-
ing affects the electronic and photophysical properties
of the spectator ligand and (c) to investigate the effect
arene)CI2}2] (h6-arene=benzene, p-cymene or hexam-
ethylbenzene) with CNPy, DCB or 1,4-piperazine-
on bonding properties of the second functional group
dicarbonitrile, in dichloromethane, gives neutral
remote from the coordinated site in the mononuclear
mononuclear and binuclear complexes with the formu-
complexes. In this paper we describe and discuss the
spectral properties of the complexes resulting from the
* Corresponding author. Tel.: +91-76-6240740.
reactions of [Ru(h6-arene)Cl2(L)] with CNPy and DCB.
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00258-8

A. Singh et al. / Journal of Organometallic Chemistry 605 (2000) 74–81
75
2. Results and discussion
corresponding peak is present at m/z 497 (Calc.497). In
the next step, loss of the h6-arene ligand takes place to
form [Ru(PPh3)]2+, which is evident from the presence
of a peak at m/z 363 (Calc. 363). This step suggested
that RuꢀP bond is stronger than the Ruꢀarene bond.
Finally, the coordinated triphenylphosphine molecule
is given out in phases. The overall fragmentation pat-
tern may be given as:
The phosphine containing arene complexes [Ru(h6-
arene)Cl2(P)] (P=PPh3, PEt3 or MePPri2) react with
organonitriles, CNPy or DCB in the presence of
NH4PF6 in methanol to from the mononuclear cationic
arene complexes with the general formulation [Ru(h6-
arene)(P)Cl(L)]PF6 (L=CNPy or DCB).
[Ru(h6-C6H6)Cl2(P)]
+LꢀMꢀꢀeOꢀHꢀꢁ[Ru(h6-C6H6)Cl(P)(L)]PF6
NH PF
4
6
Bright-yellow to orange cationic complexes are high
melting, non-hygroscopic, air-stable, shiny crystalline
solids. These are sparingly soluble in methanol, benzene,
soluble in dichloromethane, chloroform, methanol, ace-
tone, acetonitrile, dimethylformamide, dimethylsulfox-
ide and insoluble in petroleum ether and diethyl ether.
Analytical data of the complexes are consistent with
our formulations. Conductance behavior of the com-
plexes under study show that all these are ionic in nature
and their conductances are in good agreement with
those of similar electrolyte types under identical condi-
tions.
The above fragmentation pattern conforms well to our
formulation for these complexes. Further, the bonding
mode in the complexes and their tentative structures
have been deduced from following spectral studies (Fig.
2).
2.1. IR spectra
Information about the composition of the complexes
has also been obtained from fast atom bombardment
spectroscopy. FAB mass spectra of the complexes (Fig.
1(a, b)) [Ru(h6-C10H14)Cl(PPh3)(CNPy)]PF6 (4) and
[Ru(h6-C10H14)Cl(PPh3)(DCB)]PF6 (11) exhibit analo-
gous fragmentation patterns. Molecular ion peaks ap-
peared at m/z 637(Calc. 637) and m/z 661(Calc. 662), re-
spectively, in the FAB mass spectra of these complexes
corresponding to [Ru(h6-C10H14)Cl(PPh3)(CNPy)]+ and
[Ru(h6-C10H14)(PPh3)Cl(DCB)]+. In step II, the coordi-
nated organonitrile (CNPy or DCB) is given out to form
[Ru(h6-C10H14)Cl(PPh3)]+. It is evident from the pres-
ence of a peak at m/z 533 (Calc. 533). Step III of the
fragmentation pattern involves loss of the chloro ligand
to give dicationic species [Ru(h6-C10H14)(PPh3)]2+, a
The ligand CNPy can bind a metal centre through its
nitrile nitrogen, pyridine nitrogen or both the nitrogen
atoms as in the bridged complexes. Coordination
through the nitrile nitrogen is expected to lead a shift in
the position of nitrile stretching frequency, while coordi-
nation through the pyridine ring nitrogen should lead to
shifts in the position of pyridine ring vibrations (1543,
1493, 1410,1199, 1109, 1072 and 585 cm−1) without a
significant shift in the position of the nitrile stretching
frequency w(CꢂN). The site of coordination of the lig-
and CNPy in the complexes have been elucidated from
the shifts in the position of w(CꢂN) and pyridine ring vi-
brations.
IR spectra of complexes 1–7 under study exhibited
strong vibrations around 2240 cm−1, assignable to the
Fig. 1. FAB mass spectra of complexes 4a and 11b.

76
A. Singh et al. / Journal of Organometallic Chemistry 605 (2000) 74–81
Fig. 2. A PLUTO representation of complex 4 based on 2000 reflections.
to the nitrogen of the nitrile group and (ii) poor back-
bonding from the Ru(II) centre. This observation is
consistent with the conclusions drawn from 13C-NMR
spectral data of the complexes (vide infra).
nitrile stretching frequency w(CꢂN). The position of the
w(CꢂN) band in the complexes is essentially unaffected,
implying non-coordination of the nitrile group. An
insignificant change of (ꢀ3–5 cm−1) in the position of
the w(CꢂN) band could arise from resonance and elec-
tronic effects (p-back bonding) due to the linkage of
CNPy with the metal centre. It is therefore presumed
that the ligand binds with the metal centre through its
pyridine ring nitrogen atom. This observation is consis-
tent with earlier reports [6]. The bonding through the
pyridine ring nitrogen is further supported by the shifts
in the position of the bands having contribution from
w(CꢀC) and w(CꢀN) of the pyridine molecule in the
region 1600–1400 cm−1, towards higher wave number
side [6a, h,7].
The infrared spectra of free 1,4-dicyanobenzene
molecules displays an intense sharp band at 2232 cm−1
corresponding to w(CꢂN) [4a]. IR spectra of the 1,4-di-
cyanobenzene complexes 8–14, exhibited two sharp
bands in the region ꢀ2230 and ꢀ2260 cm−1
assignable to w(CꢂN). The presence of two sharp bands
in the nitrile frequency region suggested that only one
of the nitrile groups of the DCB ligand is involved in
coordination with the ruthenium(II) centre. The shift in
the position of the band at 2232 cm−1 towards a higher
wave number as compared with that in the free ligand
reflects: (i) direct coordination of the metal ion Ru(II)
The characteristic bands due to h6-arene, coordi-
nated phosphines PPh3, PEt3, MePPri2 and the counter
ion PF−6 are also exhibited in the IR spectra of the
respective complexes.
1
2.2. H-NMR spectra
1
The H-NMR spectral data along with their assign-
ments are summarized with the selected data of the
complexes. The 1H-NMR spectra of the complexes
[Ru(h6-C6H6)Cl(P)(CNPy)]+ with PPh3, PEt3, or
MePPri2 as co-ligands 1–3 showed sharp singlets (PPh3,
l 5.99 ppm; PEt3, 6.17 ppm; MePPri2, 6.21 ppm) char-
acteristic for the coordinated h6-C6H6 ligand. The arene
protons exhibited a downfield shift as compared with
that in the precursor complex. Similar downfield shifts
were observed for aromatic proton resonance of h6-
C10H14 and C6Me6 in their respective complexes
[Ru(h6-C10H14)Cl(P)(CNPy]+ and [Ru(h6-C6Me6)Cl-
(PPh3)(CNPy)]+ (4–7). The arene protons in all the
complexes undergoes a downfield shift as compared
with that in the [{Ru(h6-arene)Cl2}2] (h6-arene=ben-
zene, p-cymene or hexamethylbenzene), and in the pre-

A. Singh et al. / Journal of Organometallic Chemistry 605 (2000) 74–81
77
cursor complexes [Ru(h6-arene)Cl2(P)] or closely re-
lated complexes [Ru(h6-arene)Cl2(CNPy)] [5,8]. This
observation is consistent with earlier reports. The shift-
ing of the h6-arene proton resonance towards the low-
field side may result from the change of electron density
on the metal due to bonding of the pyridine ring
nitrogen with the Ru(II) centre. Furthermore, the nitrile
group ꢀCN, substituted in the para position of the
pyridine ring pulls electron density away from the
pyridine nucleus towards itself, which in turn affects
electron density on the Ru(II) centre. It may conse-
quently lead to a pull of more electron density from
h6-arene towards Ru(II), resulting in deshielding of the
h6-arene protons. a and b protons of the ligand CNPy
resonated in the range l 9.45–8.82 ppm and l 7.93–
7.71 ppm, respectively. In the majority of the complexes
these exhibited upfield shift as compared with those in
the free ligand [9a–c,10]. One may tentatively attribute
these shifts to the p-backbonding from Ru(II) to the
CNPy ligand.
Cl(PEt3)(CNPy)]+. The 13C-NMR spectra of complexes
[Ru(h6-C10H14)Cl(P)(CNPy)]+ and [Ru(h6-C6Me6)-
Cl(PPh3)(CNPy)]+ (4–7) followed the similar trends.
The phosphine carbons in all these complexes resonated
in their usual positions.
An interesting aspect of the 13C-NMR spectra of the
dicyanobenzene complexes [Ru(h6-C6H6)Cl(P)(DCB)]+
(8), [Ru(h6-C10H14)Cl(P)(DCB)]+ (9) are the presence
of two resonance in the nitrile carbon region. 13C-NMR
spectra of all the complexes under study exhibited one
resonance at l 117.1 ppm characteristic of the uncoor-
dinated nitrile carbon of the ligands, in addition to it
another signal exhibiting an upfield shift is observable
at around l 115.74 ppm. The carbon at l 115.7 ppm
has assigned to coordinated CꢂN carbon, while one at
l ꢀ117 ppm has been assigned to pendant CꢂN group.
It suggested that the dicyanobenzene molecule in these
complexes is coordinated with the Ru(II) centre
through one of its nitrile group. Although the shift is
not very large, it may be that upon coordination of the
nitrile nitrogen with the ruthenium, electron density on
the carbon atom of the CꢂN group is polarized towards
the nitrogen atom. It results in deshielding of the
carbon atom through the ‘s’ bond, but the back dona-
tion of the electron density from the ruthenium to the
p* orbital of CN group more than compensates the
deshielding effect, so that only a small amount of net
shielding of the carbon nucleus occurs. This supports
the back donation of p-electrons from ruthenium to the
p* orbitals of DCB. The carbon atoms (ꢃCꢀCN) of
the benzene ring of DCB underwent deshielding due to
strong electron attracting inductive effect of CN group.
This resonated at l ꢀ123 ppm in these complexes
compared with the values reported for the free ligand.
The ortho and meta carbon atoms of the benzene ring
appeared in the region characteristic for phenyl carbon
resonances of other collegians present in the column in
the region 120–136 ppm as multiplets.
The 1H-NMR spectra of the [Ru(h6-C6H6)Cl(P)-
(DCB)]+ complexes 8–10 displayed sharp singlets
(PPh3; 6.14, PEt3; 6.62, MePPri2; 6.37) characteristic for
coordinated h6-C6H6 ligands. These, as well as proton
resonance corresponding to h6-arene in the complexes
[Ru(h6-C10H14)Cl(P)(DCB)]+ and [Ru(h6-C6Me6)-
(EPh3)Cl(P)(DCB)]+ (11–14), also exhibited downfield
shift as compared with those in the arene complexes
[Ru(h6-C10H14)Cl2}2] and the precursor complexes
[{Ru(h6-arene)Cl2(P)] [5,8]. It suggests that the CN
moiety in DCB complexes affect the electronic environ-
ment of h6-arene protons. The signals of the phenyl
protons of the DCB resonated in the range l 7.8–8.4
ppm. These also exhibited a downfield shifts as com-
pared with those in the free ligand (l 7.8 ppm) [4a].
Signals due to phosphine protons are found in their
1
usual positions in the H-NMR spectra of the respec-
tive complexes.
2.3. 13C{1H}-NMR spectra
2.4. 31P-NMR spectra
The 13C-NMR spectral data of the complexes are
consistent with the conclusions drawn from H-NMR
The 31P-NMR spectra of the complexes [Ru(h6-
C6H6)Cl(P)(CNPy)]+ consisted of singlets (PPh3, l
37.47; PEt3, 27.58; MePPir2, 32.95 ppm) corresponding
to coordinated phosphine 31P nuclei. In the p-cymene
complexes [Ru(h6-C10H14)Cl(P)(CNPy)]+ these are ob-
servable at l 36.85; 30.00 and 24.06 ppm, respectively,
corresponding to coordinated PPh3, PEt3 and MePPir2
ligand. Similarly, all the DCB complexes under study
exhibited sharp singlets. In all these complexes 31P
nuclei exhibited a downfield shift as compared with
those in the free ligands. The deshielding may be caused
by relatively less donation of electron density from the
Ru(II) centre to phosphorous through back bonding,
suggesting that the degree of dp–pp back bonding
influences the chemical shift of the phosphorous atoms.
1
data. The h6-C6H6 carbons in the complexes [Ru(h6-
C6H6)Cl(P)CNPy]+ appeared at l 90.93 (in PPh3 com-
plex), 93.21 (in PEt3 complex) and 93.60 ppm in the
MePPri2 complex. It exhibited a downfield shift side
as compared with precursor complexes [Ru(h6-
arene)Cl2(P)]. The nitrile carbon (CN) of the CNPy
ligand also displayed a downfield shift (PPh3, l 121.06
ppm; PEt3, l 119.6 ppm; MePPri2, l 120.2 ppm) in the
complexes 1–3 as compared with those in the free
ligand (l 117.6 ppm). The a, b and g carbons of CNPy
resonated at l 157.56, 128.6 and 126.77 ppm, respec-
tively, in [Ru(h6-C6H6)Cl(PPh3)(CNPy)]+ and at l
150.72, 128.27 and 125.58 ppm in [Ru(h6-C6H6)-

78
A. Singh et al. / Journal of Organometallic Chemistry 605 (2000) 74–81
The 31P nuclei of the counter ion PF−6 resonated at l
ꢀ103 ppm in all these complexes in its septet pattern.
hetero bimetallic mixed valence bridged complexes. An
attempt was made to confirm the structure of one of
the representative complex [Ru(h6-C10H14)Cl(PPh3)-
(CNPy)]PF6 by single-crystal X-ray analysis. A single
crystal of this complex showed decay after 2000 reflec-
tions. However, structure of the complex based on these
2000 reflections revealed the coordination of CNPy
through the pyridine ring nitrogen and presence of a
pendant donor nitrile group. Overall single crystal data
is not worth publication.
2.5. Electronic spectra
The interaction of filled dp(t2g) orbitals on Ru(II)
with low lying p* orbitals on the CNPy ligand should
provide a metal-to-ligand charge transfer (MLCT) tran-
sition (t2g“p*) in the electronic spectra of these com-
plexes, with the transition energy of these bands
varying with the nature of the ligands acting as p-accep-
tors. The presence of an electron withdrawing group
(CN) in the para position of the pyridine molecule
should decrease the energy of transition causing a red
shift in the MLCT maxima, while an electron donating
group should increase the transition energy [6a,b,7b,9].
The electronic spectra of 4-cyanopyridine complexes
with the formulations [Ru(h6-arene)Cl(P)(CNPy)]+ dis-
played bands ꢀ450, ꢀ330 and ꢀ260–265 nm. The
bands around 450 nm has been assigned to a MLCT
transition [t2g(Ru(II)“p*(CNPy)]. The umax and Emax
values of this band is consistent with those of the
pyridine bound CNPy complexes of Ru (II) [10a, b].
Further support for the bonding is provided by the fact
that the aromatic nitrogen bonded complexes always
absorb at a larger wavelength compared with nitrile
(CN) bound complexes [6a,7b]. The bands around 350
nm are assigned to the MLCT transition arising from
Ru (II) to p* orbitals of the h6-arene ligand. The
possibility of these bands arising from other MLCT
transitions may be ruled out since the likelihood of
transitions appearing from Ru(II) to phosphines in the
near UV region is obscured. The intra ligand p“p*
transitions are observed in the region 250–256 nm.
Electronic spectra of dicyanobenzene complexes with
the formulations [Ru(h6-arene)Cl(P)(DCB)]+ displayed
bands in the region ꢀ450, 340–360 and ꢀ260 nm.
The broad to medium intensity bands centred around
450 nm have been assigned to MLCT bands arising
from drift of electron density from filled Ru(II)“
dp(t2g) orbitals to the low lying p* orbitals of the ꢀCN
group of the DCB ligand. The position of this band is
consistent with those in other nitrile complexes. The
band around 450 nm did not show any solvatochromic
effect in common organic solvents, indicating no
change is the dipole moments of the molecule in the
ground state and excited state. It further supported our
charge transfer assignment. The band around 330 nm
has been assigned to an MLCT transition [Ru (II)“p*
on the arene ring].
3. Experimental
The chemicals used for the reaction were Analar or
chemically pure grade. Solvents were dried prior to use.
4-Cyanopyridine, 1,4-dicyanobenzene, triphenylphos-
phine or triethylphosphine were used as received with-
out further purification. The precursor complexes
[Ru(h6-arene)Cl2(L)] and methyldiisopropylphoshine
were prepared following the literature procedure [8].
The elemental analyses were performed by microanalyt-
ical division of RSIC, Central Drug Research Institute,
Lucknow. IR spectra were recorded in Nujol mulls on
Perkin–Elmer 577 and Perkin–Elmer 881 spectropho-
tometers. NMR spectra were recorded on a Varian
unity 400 MHz or Varian Gemini 200 MHz or Bruker
DRX 300 MHz instruments. The chemical shifts are
given in ppm relative to tetramethylsilane (1H,
13C{1H}), 85% H3PO4 (31P{1H}). Electronic spectra
were obtained on a Shimadzu UV-160 spectrophoto-
meter. FAB mass spectra were recorded on a JEOL SX
102DA 6000 mass spectrometer using Xenon (6 kV, 10
mA) as the FAB gas. The accelerating voltage was 10
kV and the spectra were recorded at room temperature
(r.t.) with m-nitrobenzyl alcohol as the matrix.
3.1. Procedure
3.1.1. Preparation of
[Ru(p6-C6H6)(PPh3)Cl(CNPy)]PF6 (1)
A suspension of [Ru(h6-C6H6)Cl2(PPh3)] (512 mg, 1
mmol) and CNPy (104 mg, 1 mmol) in methanol (25
ml) was stirred for ꢀ4.0 h at r.t. and filtered through
Celite to remove any solid impurity. To the filtrate
NH4PF6 (163 mg, 1 mmol) dissolved in methanol (10
ml) was added and left for slow crystallization. After
2–3 days a fine microcrystalline product separated out.
It was filtered washed twice with methanol, diethyl
ether and dried under vacuo. Yield 580 mg (80%).
Anal. Calc. for C30H25ClF6N2P2Ru: C, 49.62; H, 3.44;
N, 3.85. Found; C, 49.50; H, 3.45; N, 3.82%. IR
Analytical and spectral data of the complexes are in
excellent agreement with our formulation of the com-
plexes [Ru(h6-arene)Cl(P)(L)]+, it suggested the pres-
ence of a pendant donor nitrile group. The presence of
this group offers unique opportunity for behaving as
metallo-ligand or as synthon in the synthesis of homo–
1
(Nujol) 2241 cm−1, w(CꢂN); H-NMR (CDCl3, TMS,
1
ppm); H: l 9.00 (d, 2H, 6.2 Hz, aHꢀCNPy); 7.70 (d,
2H, 6.4 Hz, bH-CNPy); 7.56–7.17 (br. m., 15H, PPh3);
5.99 (sharp singlet, 6H, h6-C6H6); 13C{1H}: l 157.56

A. Singh et al. / Journal of Organometallic Chemistry 605 (2000) 74–81
79
(aCꢀCNPy); 135–128.8 (PPh3); 128.611 (bCꢀCNPy);
126.77 (gCꢀCNPy); 121.063 (CꢂN, CNPy); 90.95
(C6H6); 31P{1H}: l 37.47 (PPh3), 103.32 (PF−6 ); UV–
vis (acetone, umax, nm) 450, 330 and 265.
Yield 78%. Anal. Calc. for C22H33ClF6N2P2Ru: C,
41.41; H, 5.17; N, 4.39. Found: C, 41.21; H, 5.18; N,
4.40%. IR (Nujol) 2242 cm−1, w(CꢂN); 1H-NMR
(CDCl3, TMS, ppm); 1H: l 8.82 (d, 2H, 2.4 Hz,
aHꢀCNPy); 7.84 (d, 2H, 2.4 Hz, bH-CNPy); 5.89–5.83
(dd, 4H, 2.8 Hz, C6H4); 2.65 (sp., 1H, 3.4 Hz, CHMe2),
2.49 (m, CH2 of PEt3), 1.86 (s, 3H, CꢀCH3), 1.36 (d,
6H, 2.6 Hz, CH(CH3)2); 1.18 (m, CH3 of PEt3);
13C{1H}: l 150.72 (aCꢀCNPy); 127.43 (bCꢀCNPy);
125.58 (gCꢀCNPy); 121.64 (CꢂN, CNPy); 104.45
(CꢀCHMe2); 95.39 (CꢀCH3); 90.17–90.02 (C6H4);
30.76 (CHMe2), 21.54 (CH(CH3)2); 18.132 (CꢀCH3),
17.40 (CH2 protons of PEt3), 7.55 (CH3 protons of
PEt3), 31P{1H}: l 30.00 (PEt3), 103.32 (PF−6 ); UV–vis
(acetone, umax, nm) 445, 320, 265.
3.1.2. Preparation of [Ru(p6-C6H6)(PEt3)Cl(CNPy)]PF6
(2)
It was prepared following the above procedure start-
ing from [Ru(h6-C6H6)Cl2(PEt3)] with CNPy in
methanol. Yield 60%. Anal. Calc. for C18H25ClF6-
N2P2Ru: C, 37.14; H, 4.29; N, 4.81. Found: C, 37.10;
H, 4.12; N, 4.65%. IR (Nujol) 2242 cm−1, w(CꢂN);
1
1H-NMR (CDCl3, TMS, ppm); H: l 9.43 (d, 2H, 6.4
Hz, aHꢀCNPy); 7.96 (d, 2H, 6.8 Hz, bHꢀCNPy); 6.17
(sh. s., 6H, C6H6); 2.03 (m, 6H, CH2, PEt3), 1.08 (m,
9H, CH3, PEt3); 13C{1H}: l 150.72 (aCꢀCNPy); 128.27
(bCꢀCNPy); 125.58 (gCꢀCNPy); 119.6 (CꢂN, CNPy);
93.21 (C6H6); 29.41 (CH2 of PEt3); 18.25 (CH3 of
PEt3); 31P{1H}: l 27.58 (PEt3), 103 (PF−6 ); UV–vis
(acetone, umax, nm) 445, 300 and 240.
3.1.6. Preparation of
[Ru(p6-C10H14)(MePPr2i )Cl(CNPy)]PF6 (6)
It was prepared following the above procedure start-
ing from [Ru(h6-C10H14)Cl2(MePPri2)] with CNPy in
methanol. Yield 80%. Anal. Calc. for C22H33ClF6-
N2P2Ru: C, 41.41; H, 5.17; N, 4.39. Found: C, 41.17;
H, 5.12; N, 4.28%. IR (Nujol) 2224 cm−1, w(CꢂN);
3.1.3. Preparation of
[Ru(p6-C6H6)(MePPri2)Cl(CNPy)]PF (3)
This complex was prepared from the reaction of
[Ru(h6-C6H6)Cl2(MePPri2)] with CNPy in methanol.
Yield 65%. Anal. Calc. for C19H27ClF6N2P2Ru: C,
38.28; H, 4.53; N, 4.70. Found: C, 38.08; H, 4.58; N,
4.78%. IR (Nujol) 2245 cm−1, w(CꢂN); 1H-NMR
(CDCl3, TMS, ppm); 1H: l 9.45 (d, 2H, 6.8 Hz,
aHꢀCNPy); 7.93 (d, 2H, 6.8 Hz, bHꢀCNPy); 6.21 (sh s,
6H, C6H6); 2.78 (m, CH(CH3)2); 2.48 (CH(CH3)2); 2.12
(CH3PPri2); 31P{1H}: l 32.95 (MePPr2i ), 103.31 (PF6−);
UV–vis (acetone, umax, nm) 435, 290, 260.
1
1H-NMR (CDCl3, TMS, ppm); H: l 8.82 (d, 2H, 4.4
Hz, aHꢀCNPy); 7.84 (d, 2H, 4.8 Hz, bHꢀCNPy); 6.00,
6.07 (dd, 4H, 5.6 Hz, C6H4); 2.70 (sp., 1H, 6.4 Hz,
CHMe2), 2.14 (s, 3H, CꢀCH3), 2.04 (m, CH(CH3)2,
MePPri2); 1.28 (dd, 6.4 Hz, CHCH3), 0.98 (m,
CH(CH3)2 of MePPri2; 31P{1H} (H3PO4): l 24.06
(MePPri2), 103.26 (PF−6 ).
3.1.7. Preparation of
3.1.4. Preparation of
[Ru(p6-C6Me6)(PPh3)Cl(CNPy)]PF6 (7)
[Ru(p6-C10H14)(PPh3)Cl(CNPy)]PF6 (4)
This complex was prepared from the reaction of
[Ru(h6-C6Me6)Cl2(PPh3)] with CNPy in methanol.
Yield 70%. Anal. Calc. for C36H37ClF6N2P2Ru: C,
53.36; H, 4.57; N, 3.45. Found: C, 53.48; H, 4.63; N,
3.50%. IR: (Nujol): 2238 cm−1, w(CꢂN); 1H-NMR
(CDCl3, TMS, ppm): 9.02 (d, 2H, 6.2 Hz, aHꢀCNPy);
7.82 (d, 2H, 6.2 Hz, bHꢀ CNPy); 7.8–7.2 (br. m.
P(C6H5)3), 2.12 (s, C6(CH3)3); 31P{1H}: 38.6 (PPh3),
103.25 (PF−6 ).
It was prepared following the above procedure start-
ing from [Ru(h6-C10H14)Cl2(PPh3)] with CNPy. Yield
80%. Anal. Calc. for C34H33ClF6N2P2Ru: C, 52.20; H,
4.22; N, 3.58. Found: C, 51.86; H, 4.19; N, 3.51%. IR
(Nujol) 2239 cm−1, w(CꢂN); H-NMR (CDCl3, TMS,
1
1
ppm); H: l 9.13 (d, 2H, 5.8 Hz, aHꢀCNPy); 7.71 (d,
2H, 6.6 Hz, bHꢀCNPy); 7.65–7.16 (br. m., 15H,
P(C6H5)3); 6.16, 6.41 (dd, 4H, 6.6 Hz, C6H4); 2.84 (sp.,
1H, 2.4 Hz, CHMe2), 1.96 (s, 3H, CꢀCH3), 1.33 (d, 6H,
2.4 Hz, CH(CH3)2); 13C{1H}: l 158.38 (aCꢀCNPy);
135.14–129.35 (P(C6H5)3), 128.00 (bCꢀCNPy); 124.35
(gCꢀCNPy); 120.68 (CꢂN, CNPy); 106.06 (CꢀCHMe2),
95.98 (CꢀCH3); 88.22 and 89.15 (C6H4), 30.66
(CHMe2), 21.47 (CH(CH3)2), 18.20 (CꢀCH3); UV–vis
(acetone, umax, nm) 456, 425, 260.
3.1.8. Preparation of [Ru(p6-C6H6)(PPh3)Cl(DCB)]PF6
(8)
This complex was prepared from the reaction of
[Ru(h6-C6H6)Cl2(PPh3)] with DCB in methanol. Yield
70%. Anal. Calc. for C32H25ClF6N2P2Ru: C, 51.23; H,
3.33; N, 3.73. Found: C, 50.28; H, 3.25; N, 3.71%. IR
1
3.1.5. Preparation of
(Nujol) 2268, 2230 cm−1, w(CꢂN); H-NMR (CDCl3,
[Ru(p6-C10H14)(PEt3)Cl(CNPy)]PF6 (5)
It was prepared following the above method starting
from [Ru(h6-C10H14)Cl2(PEt3)] with CNPy in methanol.
TMS, ppm); H: l 8.06 (s, 4H, DCB); 7.8–7.2 (br. m.,
1
15H), P(C6H5)3), 6.148 (sh. s, 6H, h6-C6H6); 31P{1H}: l
28.46 (PPh3), 103.3 (PF−6 ).

80
A. Singh et al. / Journal of Organometallic Chemistry 605 (2000) 74–81
3.1.9. Preparation of [Ru(p6-C6H6)(PEt3)Cl(DCB)]PF6
(9)
P2Ru: C, 43.53; H, 4.98; N, 4.23. Found: C, 43.58; H,
4.92; N, 4.20%. IR (Nujol) 2240, 2266 cm−1, w(CꢂN).
It was prepared following the above procedure start-
ing from [Ru(h6-C6H6)Cl2(PEt3)] and DCB in
methanol. Yield 68%. Anal. Calc. for C20H25ClF6N2-
P2Ru: C, 39.63; H, 4.12; N, 4.62. Found: C, 39.71; H,
4.06; N, 4.59%. IR (Nujol) 2242, 2270 cm−1, w(CꢂN);
1H-NMR (CDCl3, TMS, ppm); 1H: l 8.06 (s, 4H,
DCB); 6.32 (sh. s., 6H, C6H6); 2.06 (6H, CH2 protons
of PEt3); 1.03 (m, 9H, CH3 protons of PEt3); 13C{1H}:
l 133.18 (aCꢀC6H4); 128.28 (bCꢀC6H4); 117.51 (coor-
dinated CꢂN of DCB); 115.69 (uncoordinated CꢂN of
DCB); 93.79 (C6H6); 17.299 and 8.612 (carbons of
PEt3); 31P{1H}: l 43.80 (PEt3), 103.31 (PF−6 ); UV–vis
(acetone, umax, nm) 435, 290, 240.
3.2.2. Preparation of
[Ru(p6-C10H14)(MePPr2i )Cl(DCB)]PF6 (13)
It was prepared following the above procedure (a)
starting from [Ru(h6-C6H14)Cl2(MePPri2)] with DCB in
methanol. Yield 80%. Anal. Calc. for C25H35ClF6N2-
P2Ru: C, 44.41; H, 5.18; N, 4.14. Found: C, 44.45; H,
5.09; N, 4.10%. IR (Nujol) 2239, 2270 cm−1, w(CꢂN).
3.2.3. Preparation of
[Ru(p6-C6Me6)(PPh3)Cl(DCB)]PF6 (14)
It was prepared following the above procedure (a)
starting from [Ru(h6-C6Me6)Cl2(PPh3)] with DCB in
methanol. Yield 80%. Anal. Calc. for C38H37ClF6N2P2-
Ru: C, 54.70; H, 4.43; N, 3.35. Found: C, 44.45; H,
5.09; N, 4.10%. IR: (Nujol): 2245, 2260 cm−1, w(CꢂN);
1H-NMR (l, ppm): 8.74 (d, 2H, 5.82 Hz, aHꢀDCB);
7.92 (d, 2H, 6.0 Hz, bHꢀDCB); 7.72–7.18 (br. m.
P(C6H5)3), 2.12 (s, C6(CH3)3).
3.1.10. Preparation of
[Ru(p6-C6H6)(MePPr2i )Cl(DCB)]PF6 (10)
It was prepared following the above procedure start-
ing from [Ru(h6-C6H6)Cl2(MePPri2)] and DCB in
methanol. Yield 65%. Anal. Calc. for C21H27ClF6N2-
P2Ru: C, 40.67; H, 4.35; N, 4.51. Found: C, 40.02; H,
4.31; N, 4.50%. IR (Nujol) 2240, 2272 cm−1, w(CꢂN);
1
1H-NMR (CDCl3, TMS, ppm); H: l 8.8 (d, 2H, 6.0
Hz, DCB); 7.84 (d, 2H, 6.4 Hz, DCB); 6.37 (s., 6H,
C6H6); 2.802 (m, 2H, 6.8 Hz, CH(CH3)2); 2.49 (d, 12H,
4 Hz, CH(CH3)2); 2.07(s, 3H, CH3PPri2); 31P{1H}: l
Acknowledgements
Thanks are due to CSIR New Delhi for financial
assistance [HRDG 01(1375)/95/EMR-II]. Thanks are
also due to the Head, RSIC Central Drug Research
Institute, Lucknow, for extending analytical and spec-
tral facilities and the Head Department of Chemistry,
A.P.S. University, Rewa, for extending laboratory
facilities.
43.80 (MePPr2i ), 103.3 (PF6−); UV–vis (acetone, umax
,
nm) 445, 290, 239.
3.2. Preparation of [Ru(p6-C10H14)(PPh3)Cl(DCB)]PF6
(11)
It was prepared following the above procedure start-
ing from [Ru(h6-C6H14)Cl2(PPh3)] with DCB in
methanol. Yield 80%. Anal. Calc. for C36H33ClF6N2-
P2Ru: C, 53.63; H, 4.09; N, 3.47. Found: C, 53.59; H,
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4.11; N, 3.41%. IR (Nujol) 2266 cm−1, w(CꢁN); H-
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[Ru(p6-C10H14)(PEt3)Cl(DCB)]PF6 (12)
It was prepared following the above procedure start-
ing from [Ru(h6-C10H14)Cl2(PEt3)] with DCB in
methanol. Yield (80%). Anal. Calc. for C24H33ClF6N2-

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