Chemistry of a new family of aryl ruthenium species incorporating α-diimine chelation and a pendant imine-phenol function

Article abstract of DOI:10.1016/S0022-328X(03)00211-0

The reaction of excess 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) with Ru(η²-RL) (PPh₃)₂(CO)Cl (1) has respectively furnished [Ru(η¹-RL)(PPh₃)₂(CO)(bpy)] (PF₆) (2) and [Ru(η¹-RL) (PPh₃)₂(CO)(phen)](PF₆) (3) in very good yield (η²-RL is C₆H₂O-2-CHNHC₆H₄R(p)-3-Me-5, η¹-RL is C₆H₂OH-2- CHNC₆H₄R(p)-3-Me-5 and R is H, Me, MeO, Cl). The chelation of bpy/phen is attended with the cleavage of Ru-0O and Ru-Cl bonds and iminium-phenolato→imine-phenol prototropic shift. The carbon monoxide ligand is located syn to the phenolic oxygen in 2 and 3 as opposed anti in 1. The crystal and molecular structures of [Ru(η¹-HL)(PPh₃)₂ (CO)(bpy)](PF₆)·CH₂Cl₂ (2(H)·CH₂Cl₂) and [Ru(η¹-ClL) (PPh₃)₂(CO)(phen)] (PF₆)·H₂O (3(Cl)·H₂O) are reported. In the lattice of 3(Cl)·H₂O, the water molecules form dimers (O·O, 2.617(8) A?). In the hydrogen bonded imine-phenol function the N·O distance is 2.550(9) A? in 2(H)·CH₂Cl₂ and 2.581(7) A? in 3(Cl)·H₂O. The Rubpy fragment in 2(H)·CH₂Cl₂ along with the CO ligand and the metallated carbon atom define an equitorial plane from which the metallated aldimine fragment (pendant Ph excluded) is rotated by 39.1° due to interligand repulsion and the two Ru-P distances (2.384(3) and 2.456(3) A?) become significantly different. The repulsion also counteracts the trans influence of the metallated carbanionic site, the Ru-N bond trans to the site being shorter. The behaviour of 3(Cl)·H₂O is similar. In dichloromethane solution 2 and 3 display a quasireversible Ru^III/ Ru^II cyclic voltammetric response with E_1/2 in the range 0.75-0.85 V versus SCE. The C≡O stretch in 2 and 3 is 30-40 cm^-1 higher than that in 1 due to the presence of dπ(Ru)-pπ(bpy/phen) back-bonding. The corresponding MLCT absorption (λ_max, ～470 nm) gives rise to fluorescence (λ_max, ～540 nm). The reaction of 2-(2-pyridyl)benzthiazole (pbt) with 1 has furnished [Ru(η¹-RL)(PPh₃)₂(CO)(pbt)] (PF₆) (8) in which pbt is (N,N) chelated. The properties of 8 are generally similar to those of 2 and 3.

Full text of DOI:10.1016/S0022-328X(03)00211-0

Journal of Organometallic Chemistry 674 (2003) 107Á115
/
www.elsevier.com/locate/jorganchem
Chemistry of a new family of aryl ruthenium species incorporating
a-diimine chelation and a pendant imine-phenol function
Bikash Kumar Panda a, Kaushik Ghosh a, Swarup Chattopadhyay a,
Animesh Chakravorty a,b,
*
a Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
b Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore 560 064, India
Received 26 January 2003; received in revised form 25 March 2003; accepted 27 March 2003
Abstract
The reaction of excess 2,2?-bipyridine (bpy) and 1,10-phenanthroline (phen) with Ru(h2-RL)(PPh3)2(CO)Cl (1) has respectively
furnished [Ru(h1-RL)(PPh3)2(CO)(bpy)](PF6) (2) and [Ru(h1-RL)(PPh3)2(CO)(phen)](PF6) (3) in very good yield (h2-RL is C6H2O-
2-CHNHC6H4R(p)-3-Me-5, h1-RL is C6H2OH-2-CHNC6H4R(p)-3-Me-5 and R is H, Me, MeO, Cl). The chelation of bpy/phen is
attended with the cleavage of Ruꢀ
monoxide ligand is located syn to the phenolic oxygen in 2 and 3 as opposed anti in 1. The crystal and molecular structures of
[Ru(h1-HL)(PPh3)2(CO)(bpy)](PF6)× CH2Cl2) and [Ru(h1-ClL)(PPh3)2(CO)(phen)](PF6)×
CH2Cl2 (2(H)× H2O (3(Cl)×H2O) are re-
ported. In the lattice of 3(Cl)×H2O, the water molecules form dimers (Oꢀ ꢀ ꢀO, 2.617(8) A). In the hydrogen bonded imine-phenol
function the Nꢀ ꢀ ꢀO distance is 2.550(9) A in 2(H)×
with the CO ligand and the metallated carbon atom define an equitorial plane from which the metallated aldimine fragment
/
O and Ruꢀ
/
Cl bonds and iminium-phenolato0/imine-phenol prototropic shift. The carbon
/
/
/
/
˚
/
˚
˚
/
CH2Cl2 and 2.581(7) A in 3(Cl)×
/
H2O. The Rubpy fragment in 2(H)×/CH2Cl2 along
˚
(pendant Ph excluded) is rotated by 39.18 due to interligand repulsion and the two Ruꢀ
significantly different. The repulsion also counteracts the trans influence of the metallated carbanionic site, the Ruꢀ
the site being shorter. The behaviour of 3(Cl)×
RuII cyclic voltammetric response with E1/2 in the range 0.75Á
than that in 1 due to the presence of dp(Ru)Á
gives rise to fluorescence (lmax, ꢀ
540 nm). The reaction of 2-(2-pyridyl)benzthiazole (pbt) with 1 has furnished [Ru(h1-
/P distances (2.384(3) and 2.456(3) A) become
/N bond trans to
/
H2O is similar. In dichloromethane solution 2 and 3 display a quasireversible RuIII
/
/
0.85 V versus SCE. The Cꢁ
/
O stretch in 2 and 3 is 30Á
/
40 cmꢀ1 higher
/
pp(bpy/phen) back-bonding. The corresponding MLCT absorption (lmax, ꢀ
/470 nm)
/
RL)(PPh3)2(CO)(pbt)](PF6) (8) in which pbt is (N,N) chelated. The properties of 8 are generally similar to those of 2 and 3.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Organoruthenium a-diimine species; Fluorescent ruthenium aryls; Schiff base prototropic shift
1. Introduction
The decarbonylative metallation of 4-methyl-2,6-di-
formylphenol by Ru(PPh3)3Cl2 in the presence of
primary aromatic amines (RC6H4NH2) has been shown
to furnish the novel organoruthenium system Ru(h2-
RL)(PPh3)2(CO)Cl (1) incorporating a four-membered
chelate ring juxtaposed to a hydrogen bonded iminium-
phenolato ring [1]. The reactivity of these compounds is
being investigated in this laboratory.
While alkynes and isonitriles have been found to
promote metallacycle expansion [2], bidentate mono-
anionic s-donor reagents such as acetate, nitrate, nitrite,
xanthate and pyridine-2-thiolate undergo four-mem-
bered chelation [3].
* Corresponding author. Tel.:
24732805.
E-mail address: icac@mahendra.iacs.res.in (A. Chakravorty).
ꢁ
/
91-33-24724436; fax:
ꢁ91-33-
/
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00211-0

108
B.K. Panda et al. / Journal of Organometallic Chemistry 674 (2003) 107Á115
/
Herein we explore the possible reaction of 1 with two
These protons as well as the 5-H proton are subject to
shielding by phosphine phenyl ring [1a,3a,6]. The 5-H
signal is observed near 6.8 ppm in 2 but in 3 it merges
with the complex aromatic multiplet due to PPh3 and
C6H4R protons. The bpy/phen protons resonate in the
electroneutral a-diimine ligands viz. 2,2?-bipyridine
(bpy) and 1,10-phenanthroline (phen), which have
both s-donor and p-acceptor abilities. A facile reaction
is indeed observed leading to five-membered a-diimine
chelation via displacement of Ruꢀ
/
O and Ruꢀ/Cl bonds.
region 7.7Á
/
9.2 ppm.
The process is attended with a change in the tautomeric
state of the Schiff base ligand. The structure and
properties of the new organometallics are scrutinized.
Organoruthenium compounds incorporating chelated
bpy/phen are relatively uncommon [4]. A point of
special interest is that such species are potentially
luminescent [5]. Preliminary examination has indeed
revealed that the present compounds are luminescent in
the visible region. Complex 1 also reacts with 2-(2-
pyridyl)benzthiazole (pbt) which is found to chelate as
an a-diimine.
The conversions 10
/
2 and 10/3 are attended with a
prototropic shift within the salicylaldimine function. In
1 the metal is coordinated to phenolato oxygen and the
schiff base function occurs in the zwitterionic iminium-
phenolato tautomeric form 4. Chelation of bpy/phen is
attended with cleavage of the Ruꢀ
base fragment becomes an imine-phenol 5. This is
consistent with spectroscopic data. Thus the Cꢂ
/O bond and the Schiff
/N
stretching frequency in 2 and 3 is significantly lower
(ꢀ
/
1600 cmꢀ1) than that in 1
2. Results and discussion
2.1. Reaction of 1 with bpy/phen: chelation and
prototropic shift
(ꢀ
/
1620 cmꢀ1) as expected [7,8]. Further, the aldimine
1
CH resonance in H-NMR in both 2 and 3 occur at
In MeOHÁ
CH2Cl2 solution Ru(h2-RL)(PPh3)2-
/
significantly lower field (ꢀ
in 1 (ꢀ7.5 ppm). The OꢀH resonance in both 2 and 3
occurs as a relatively sharp signal (width at half-height
30 Hz) near 13 ppm. On the other hand, the Nꢀ
resonance in 1 is broad (width at half-height 150 Hz) due
to the quadrupole moment of the nitrogen atom [1a].
/8.2 ppm) compared to that
(CO)Cl (1) reacts smoothly with excess bpy in the
presence of NH4PF6 according to Eq. (1) furnishing
the yellow crystalline salt [Ru(h1-RL)(PPh3)2(CO)(b-
py)](PF6) (2) in excellent yield. The use of phen in place
of bpy afforded the salt [Ru(h1-RL)(PPh3)2-
(CO)(phen)](PF6) (3). The R groups
/
/
/H
1ꢁbpyꢁPFꢀ6 0 2ꢁClꢀ
(1)
2.2. Structure
utilized in the present work are H, Me, OMe, Cl.
Specific compounds will be identified by putting R in
parenthesis: thus 2(Me) stands for [Ru(h1-MeL)(PPh3)2-
(CO)(bpy)](PF6).
Structure determination of [Ru(h1-HL)(PPh3)2(CO)-
(bpy)](PF6)×
/
CH2Cl2 (2(H)×
/
CH2Cl2) and [Ru(h1-ClL)-
/
(PPh3)2(CO)(phen)](PF6)×
/
H2O (3(Cl)×
H2O) has authen-
ticated the binding mode within the cation as in 2 and 3,
respectively. Perspective views are shown in Figs. 1 and
2 and selected bond parameters are listed in Table 1. In
the distorted RuC2P2N2 coordination spheres the bpy/
phen ligand is chelated and the schiff base ligand is
Both 2 and 3 are diamagnetic (idealized t62g) and
behave as 1:1 electrolytes in acetone solution (L, 115Á
/
1
140 Vꢀ1 cm2 molꢀ1). In H-NMR the 3-H and 4-Me
protons appear as sharp singlets near 6.70 and 1.90 ppm.

B.K. Panda et al. / Journal of Organometallic Chemistry 674 (2003) 107Á
/115
109
Table 1
Selected bond parameters (bond lengths in A; bond angles in (8)) for
2(H)×CH2Cl2 and 3(Cl)×H2O
˚
/
/
2(H)×/CH2Cl2
3(Cl)×H2O
/
Bond lengths
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
C(9)ꢀ
C(7)ꢀ
C(1)ꢀ
/
P(1)
P(2)
C(2)
C(9)
N(2)
N(3)
2.384(3)
2.456(3)
2.101(10)
1.813(9)
2.172(7)
2.155(7)
1.157(10)
1.268(12)
1.364(10)
2.550(9)
2.375(2)
2.409(2)
2.090(6)
1.813(6)
2.154(5)
2.133(5)
1.134(7)
1.257(9)
1.350(7)
2.581(7)
/
/
/
/
/
/
O(2)
N(1)
O(1)
/
/
N(1)ꢀ ꢀ ꢀO(1)
Bond angles
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(1)ꢀ
P(2)ꢀ
P(2)ꢀ
P(2)ꢀ
P(2)ꢀ
RuꢀC(9)ꢀ
C(2)ꢀRuꢀ
C(9)ꢀRuꢀ
C(9)ꢀRuꢀ
N(2)ꢀRuꢀ
C(9)ꢀRuꢀC(2)
/
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
/
P(2)
N(2)
N(3)
C(9)
C(2)
N(2)
N(3)
C(9)
C(2)
177.2(1)
91.5(2)
89.5(2)
85.5(3)
91.2(3)
86.1(2)
91.3(2)
97.0(3)
87.7(3)
175.6(8)
98.7(3)
94.8(4)
170.4(4)
76.0(3)
90.5(4)
177.3(1)
92.5(1)
88.1(1)
86.9(2)
89.6(2)
85.7(1)
89.6(1)
94.7(2)
92.6(2)
175.7(6)
98.2(2)
96.5(2)
173.2(2)
76.7(2)
88.6(2)
/
/
/
/
/
/
Fig. 1. Perspective view and atom-labeling scheme for the cation of
2(H)×CH2Cl2.
/
/
/
/
/
/
/
/
/
/
/
/
/
O(2)
N(2)
N(3)
N(2)
/
/
/
/
/
/
/
/N(3)
/
/
with the carbon monoxide ligand and the metallated
carbon atom C(2) define an equitorial plane (mean
˚
deviation, 0.04 A; plane A). The metallated aldimine
fragment defined by Ru, C(1) to C(8), N(1) and O(1) is
˚
also planar (mean deviation of 0.04 A; plane B). The
noncoplanarity of the two planes is highlighted in 6, the
dihedral angle between them being 39.18. The environ-
ment around P(2) is thus more
Fig. 2. Perspective view and atom-labeling scheme for the cation of
3(Cl)×H2O.
/
monodentate, bonded at the C(2) atom only. The
phenolic oxygen atom lie too far away (Ruꢀ ꢀ ꢀO(1),
˚
˚
3.220(7) A in 2(H)×
/
CH2Cl2 and 3.230(5) A in 3(Cl)×
/
H2O) for binding.
The solvent molecule is 2(H)×
in any significant nonbonded interaction in the lattice.
On the other hand in the lattice of 3(Cl)×H2O water
/CH2Cl2 is not involved
/
molecules form discrete centrosymmetric dimers (Oꢀ ꢀ ꢀO,
˚
2.617(8) A). The N(1)ꢀ ꢀ ꢀO(1) distance in the hydrogen
˚
bonded imine-phenol moiety is 2.550(9) A in 2(H)×
/
˚
CH2Cl2 and 2.581(7) A in 3(Cl)×
/
H2O. The correspond-
crowded than that around P(1). This is reflected in the
˚
ing distance in the iminium-phenolato group of 1 is
˚
unequal bond lengths: Ruꢀ
/
P(1), 2.384(3) A and Ruꢀ
/
longer, 2.665(12) A [1]. Thus the cleavage of the Ruꢀ
bond (102/3) is attended with prototropic shift as well
as a shortening of the N(1)ꢀ ꢀ ꢀO(1) length.
The Rubpy fragment in 2(H)×CH2Cl2 is excellently
/
O
˚
P(2), 2.456(3) A. The behaviour of 3(Cl)×
/
H2O complex
/
is qualitatively similar. In the precursor complex 1, the
/
Schiff base moiety lie on the equitorial plane and the
˚
˚
planar (mean deviation, 0.02 A). This fragment along
two Ruꢀ/P lengths are equal at 2.387(2) A [1].

110
B.K. Panda et al. / Journal of Organometallic Chemistry 674 (2003) 107Á115
/
The noncoplanarity of the two planes in 2(H)×
is believed to originate from repulsive nonbonded
interactions between the bpy and Schiff base ligands.
/
CH2Cl2
and N(2)ꢀ ꢀ ꢀO(1) distances in 7 are 2.589(7) and 2.885(7)
˚
A, respectively.
These are much lower than the corresponding van der
˚
˚
Waals sums (3.20 and 3.05 A). The C(16)ꢀ ꢀ ꢀO(1) and
In particular the C(16)ꢀ ꢀ ꢀC(3) distance, 3.246(6) A, falls
˚
below the sum of van der Waals radii (3.40 A) of the two
N(2)ꢀ ꢀ ꢀO(1) distances in the observed syn configuration
˚
are 5.326(7) and 4.904(6) A respectively. The behaviour
carbon atoms [9]. The interaction is thus repulsive, but
the repulsion would have been much more if A and B
were coplanar. The trans influence of the metallated
carbanionic site C(2) could be expected to lengthen the
of the Ru(CO)(bpy) fragment in 2(H)×
/CH2Cl2 is analo-
gous.
Ruꢀ
/
N(3) distance compared to Ruꢀ
/
N(2) distance. In
˚
N(2), 2.172(7) A
2.3. Metal redox
practice the reverse is observed: Ruꢀ
/
˚
In dichloromethane solution both 2 and 3 display a
and Ruꢀ
/
N(3) is 2.155(7) A. The lengthening of Ruꢀ
/
quasireversible (peak-to-peak separation, 100Á200 mV)
/
N(2) bond is believed to be due to the C(16)ꢀ ꢀ ꢀC(3)
one-electron response assigned to RuIII/RuII redox. The
E1/2 values (Table 2) shift marginally to higher potentials
as the R-substituent becomes progressively more elec-
repulsion. The behaviour of 3(Cl)×
analogous.
In the transformation 10
/H2O is entirely
/2/3 the Schiff base fragment
tron-withdrawing: OMeB
/
MeB
/
HB
/
Cl. The E1/2 values
undergoes a large rotation around the metalꢀ
bond. As a result the carbon monoxide molecule gets
located syn
/carbon
are 100Á200 mV higher than those in type 1 precursors.
/
The cationic nature of 2 and 3 as well as the presence of
back-bonding (vide infra) to bpy/phen are both expected
to contribute to this rise of E1/2
.
2.4. Spectra: back-bonding, charge transfer and
fluorescence
The Cꢁ
/
O strech in 2 and 3 occurs in the region 1950Á
/
1960 cmꢀ1. In the precursor complex 1 as well as in
acetate/nitrate/nitrite/xanthate derivatives the stretch
systematically lie around 1920 cmꢀ1 [3]. The increased
frequency in 2 and 3 is believed to be due to the
combined effect of cationic charge and significant
to the phenolic Cꢀ
C(1)ꢀ ꢀ ꢀC(9)ꢀO(2)) being 49.98 in 2(H)×
56.38 in 3(Cl)×H2O. In 1 the corresponding arrangement
is anti [1]. The later configuration is disfavoured in 2
and 3 due to steric repulsion between the phenolic and
the a-diimine functions as highlighted in the computer
generated hypothetical anti configuration 7 for the
Ru(CO)(phen) fragment. The estimated C(16)ꢀ ꢀ ꢀO(1)
/
O function, the torsion angle (O(1)ꢀ
/
/
/
CH2Cl2 and
/
dp(Ru)Á
In dichloromethane solution the complexes display
two allowed absorption bands in the region 380Á400
and 460Á480 nm. Selected UVÁvis spectral data are
given in Table 3. The solutions are also fluorescent, the
peak lying in the region 540Á550 nm, Table 3. Excita-
/
pp(bpy/phen) back-bonding.
/
/
/
/
tion spectral studies show that the fluorescence is
Table 2
Cyclic voltammetric reduction potentials a
Table 3
Complexes
M(III)ÁM(II)
/
UVÁ
/
vis and fluorescence spectral data
E1/2 a, V (DEp, mV)
Complexes UVÁ
/
vis data a
Fluorescence data a,c
lmax (nm)
lmax (nm) (o b, Mꢀ1 cmꢀ1
)
2(H)
0.78(194)
0.77(175)
0.76(131)
0.85(203)
0.79(200)
0.75(115)
0.84(185)
0.81(178)
0.77(119)
0.87(144)
2(Me)
2(OMe)
2(Cl)
2(H)
382(15 760), 466(3860)
380(12 140), 477(2230)
386(12 900), 475(2150)
389(14 600), 468(3400)
392(12 900), 474(3070)
387(12 760), 475(2540)
394(8040), 472(2000)
380(13 000), 500(2600)
386(16 000), 502(2300)
384(14 000), 499(2400)
541
543
540
545
540
531
560
586
581
588
2(Me)
2(OMe)
2(Cl)
3(Me)
3(OMe)
3(Cl)
3(Me)
3(OMe)
3(Cl)
8(Me)
8(OMe)
8(Cl)
8(Me)
8(OMe)
8(Cl)
a
Conditions solvent, dichloromethane; supporting electrolyte,
TEAP (0.1(M)); working electrode, platinum; reference electrode,
a
10ꢀ3(M); E1/2
ꢂ/
0.5 (EpaꢁEpc) at scan
/
Solvent is dichloromethane.
Extinction coefficient.
Excitation at the higher wavelength absorption peak.
SCE solute concentration, ꢀ
rate 50 mV sꢀ1, where Epa and Epc are the anodic and cathodic peak
potentials, respectively, DEpꢂEpa Epc
/
b
c
/
ꢀ/
.

B.K. Panda et al. / Journal of Organometallic Chemistry 674 (2003) 107Á
/115
111
lengths are grossly similar to those in the
bpy/phen complexes and the dihedral angle between the
Ru(pbt)(CO)C(aryl) plane and the plane of the metal-
lated aldimine fragment is ꢀ
/
428 resulting in unequal
Fig. 3. Absorption (*), fluorescence (---) and excitation (. . .) spectra
of 2(Cl) in dichloromethane solution.
/
RuꢀP lengths.
/
The complexes behave as 1:1 electrolytes and display
a quasireversible RuIII/RuII couple near 0.8 V versus
SCE (Table 2). Their spectroscopic behaviour is also
similar to those of 2 and 3 (Table 3).
3. Experimental
3.1. Materials
The compounds Ru(PPh3)3Cl2 [11], Ru(h2-
RL)(PPh3)2(CO)Cl [1a] and 2-(2-pyridyl)-benzthiazole
[10] were prepared by reported methods. The purifica-
tion of dichloromethane and the preparation of tetra-
ethylammonium perchlorate (TEAP) for electrochem-
ical work were done as described in previous work [12].
All other chemicals and solvents were of analytical grade
and were used as received.
Fig. 4. Perspective view and atom-labelling scheme for molecule 1
(cation only) of 8(Cl). Selected bond distances are Ru(1)ꢀ
2.414(7); Ru(1)ꢀP(2), 2.464(7); Ru(1)ꢀC(2), 2.10(2); Ru(1)ꢀC(9),
1.86(2); Ru(1)ꢀN(2), 2.20(2); Ru(1)ꢀN(3), 2.19(2). Corresponding
distances of molecule P(3), 2.427(7); Ru(2)ꢀP(4),
are Ru(2)ꢀ
2.474(7); Ru(2)ꢀC(65), 2.13(2); Ru(2)ꢀC(72), 1.83(2); Ru(2)ꢀN(5),
2.18(2); Ru(2)ꢀN(6), 2.18(2).
/P(1),
/
/
/
/
/
3.2. Physical measurements
2
/
/
/
/
/
/
Electronic, IR and fluorescence spectra were recorded
with Simadzu UV-1601PC spectrophotometer, PerkinÁ
/
associated with the absorption band near 470 nm which
is assigned to p(Ru)0p*(bpy/phen) MLCT excitation.
A representative case is shown in Fig. 3. The fluores-
cence is believed to originate from the 3MLCT state. We
note that the parent organometallics of type 1 do not
display any fluorescence in the visible region. Further
studies are in progress.
Elmer 783 IR spectrometer and PerkinÁElmer model LS
/
/
55 Luminescence spectrometer, respectively. A Bruker
300 MHz FT NMR spectrometer was used to record 1H
NMR spectra (Me4Si internal standard). The numbering
scheme used for 1H-NMR is the same as in crystal-
lography. SpinÁ
singlet; d, doublet; t, triplet; m, multiplet. Microanalyses
(C, H, N) were done using a PerkinÁElmer 240C
/
spin structures are abbreviated as: s,
/
2.5. The case of a pyridylbenzthiazole ligand
elemental analyzer. Solution electrical conductivity was
measured in a acetone with a Philips PR 9500 bridge
using a platinized electrode (cell constant of 1.05). The
magnetic behavior of the complexes was examined by
PAR 155 vibrating sample magnetometer. All electro-
chemical measurement were done under a nitrogen
atmosphere in dichloromethane solution using a CHI
model 620A electrochemical analyzer. The supporting
electrolyte was tetraethylammonium perchlorate, and
The concerned ligand [10] is 2-(2-pyridyl)benzthiazole
(pbt) which was found to react with 1 under conditions
similar to those used for bpy and phen furnishing the
salt [Ru(h1-RL)(PPh3)2(CO)(pbt)](PF6) (8). Here pbt is
chelated in the (N,N) mode like bpy/phen as opposed to
the possible alternative (N,S) mode. Structure solution
for 8(Cl) (Fig. 4) confirmed this. The observed bond

112
B.K. Panda et al. / Journal of Organometallic Chemistry 674 (2003) 107Á115
/
the reported potentials are referenced to the saturated
calomel electrode (SCE).
3.3.3. [Ru(h1-MeOL)(PPh3)2(CO)(bpy)](PF6)
(2(OMe))
Ru(h2-MeOL)(PPh3)2(CO)Cl (50 mg, 0.054 mmol)
and bpy (42 mg, 0.269 mmol) were employed. Yield: 56
mg (87%). Anal. Found: C, 62.25; H, 4.30; N, 3.58. Calc.
for C62H52F6N3O3P3Ru: C, 62.31; H, 4.39; N, 3.52%. IR
3.3. Synthesis of the complexes, [Ru(h1-
RL)(PPh3)2(CO)(bpy)](PF6) (2)
(KBr, cmꢀ1): 1609 (nCN), 1953 (nCO) and 842 (nPF ). 1H -
6
The [Ru(h1-RL)(PPh3)2(CO)(bpy)](PF6) (2) com-
MR (CDCl3, d): 8.18 (s, 1H, H(7)), 13.25 (s, 1H, Oꢀ
disappeared on shaking with D2O), 6.69 (s, 1H, H(3)),
6.75Á7.34 (m, 37H, 2PPh3, H(5), H(19), H(22), H(11),
/H,
plexes were synthesized in excellent yield (ꢀ90%) by
/
reacting Ru(h2-RL)(PPh3)2(CO)Cl (1) in MeOHÁ
/
/
CH2Cl2 (2:1) at room temperature, with excess bpy in
presence of NH4PF6. Details of a representative case are
given below. The other compounds were prepared
analogously.
H(12), H(14), H(15)), 1.91 (s, 3H, CH3), 3.84 (s, 3H,
OCH3), 8.76 (d, 1H, H(16), JHH 6.1), 8.19 (t, 1H, H(18),
JHH 6.6), 7.72 (t, 1H, H(24), JHH 7.5), 8.41 (d, 1H,
H(25), JHH 6.3), 8.05 (m, 2H, H(17), H(23)). LMꢂ
/
117
Vꢀ1 cm2 molꢀ1
.
3.3.1. [Ru(h1-HL)(PPh3)2(CO)(bpy)](PF6) (2(H))
To a vigorously stirred violet solution of Ru(h2-
HL)(PPh3)2(CO)Cl (50 mg, 0.056 mmol) in a mixture of
30 ml MeOH and 15 ml dichloromethane was added 43
mg (0.275 mmol) of bpy. The mixture was stirred for 3 h
when the colour of the solution changed from violet to
yellow. Then 14 mg (0.086 mmol) of NH4PF6 was added
to the yellow solution which was further stirred for 30
min. The solvent was then removed under reduced
pressure, and the yellow solid thus obtained was washed
thoroughly with water and finally with a little MeOH
followed by drying in vacuo. Yield: 59 mg (91%). Anal.
Found: C, 62.83; H, 4.38; N, 3.57. Calc. for
C61H50F6N3O2P3Ru: C, 62.89; H, 4.33; N, 3.61%. IR
3.3.4. [Ru(h1-ClL)(PPh3)2(CO)(bpy)](PF6) (2
(Cl))
Ru(h2-ClL)(PPh3)2(CO)Cl (50 mg, 0.054 mmol) and
bpy (42 mg, 0.269 mmol) were used. Yield: 58 mg (90%).
Anal. Found: C, 61.12; H, 4.07; N, 3.58. Calc. for
C61H49ClF6N3O2P3Ru: C, 61.08; H, 4.12; N, 3.50%. IR
(KBr, cmꢀ1): 1605 (nCN), 1955 (nCO) and 842 (nPF6). 1H-
NMR (CDCl3, d): 8.16 (s, 1H, 7(H)), 12.91 (s, 1H, Oꢀ
H, disappeared on shaking with D2O), 6.73 (s, 1H,
H(3)), 6.79Á7.35 (m, 37H, 2PPh3, H(5), H(19), H(22),
/
/
H(11), H(12), H(14), H(15)), 1.91 (s, 3H, CH3), 8.73 (d,
1H, H(16), JHH 6.0), 8.19 (t, 1H, H(18), JHH 6.3), 7.73 (t,
1H, H(24), JHH 7.5), 8.40 (d, 1H, H(25), JHH 6.1), 8.06
(m, 2H, H(17), H(23)). LMꢂ
/
124 Vꢀ1 cm2 molꢀ1
.
(KBr, cmꢀ1): 1604 (nCN), 1956 (nCO) and 842 (nPF ). 1H-
6
NMR (CDCl3, d): 8.18 (s, 1H, H(7)), 13.12 (s, 1H, Oꢀ
H; disappeared on shaking with D2O), 6.72 (s, 1H,
H(3)), 6.77Á7.41 (m, 38H, 2PPh3, H(5), H(19), H(22),
/
3.4. Synthesis of the complexes, [Ru(h1-
RL)(PPh3)2(CO)(phen)](PF6) (3)
/
H(11), H(12), H(13), H(14), H(15)), 1.91 (s, 3H, CH3),
8.75 (d, 1H, H(16), JHH 6), 8.19 (t, 1H, H(18), JHH 6.3),
7.73 (t, 1H, H(24), JHH 7.5), 8.41 (d, 1H, H(25), JHH
The [Ru(h1-RL)(PPh3)2(CO)(phen)](PF6) (3) com-
80%) by
reacting Ru(h2-RL)(PPh3)2(CO)Cl (1) with excess phen
for 4 h when the color of the solution changed from
violet to yellow. The general procedure for isolation is
similar to what is described for bpy.
plexes were synthesized in excellent yield (ꢀ
/
6.1), 8.06 (m, 2H, H(17), H(23)). LMꢂ
/
116 Vꢀ1 cm2
molꢀ1
.
3.3.2. [Ru(h1-MeL)(PPh3)2(CO)(bpy)](PF6)
(2(Me))
3.4.1. [Ru(h1-MeL)(PPh3)2(CO)(phen)](PF6) (3
(Me))
Ru(h2-MeL)(PPh3)2(CO)Cl (50 mg, 0.055 mmol) and
phen (87 mg, 0.439 mmol) were employed. Yield: 50 mg
(76%). Anal. Found: C, 63.82; H, 4.31; N, 3.44. Calc. for
C64H52F6N3O2P3Ru: C, 63.89; H, 4.36; N, 3.49%. IR
(KBr, cmꢀ1): 1593 (nCN), 1955 (nCO) and 842 (nPF6). 1H-
Ru(h2-MeL)(PPh3)2(CO)Cl (50 mg, 0.055 mmol) and
bpy (43 mg, 0.275 mmol) were used. Yield: 57 mg (88%).
Anal. Found: C, 63.23; H, 4.48; N, 3.49. Calc. for
C62H52F6N3O2P3Ru: C, 63.16; H, 4.45; N, 3.56%. IR
(KBr, cmꢀ1): 1604 (nCN), 1957 (nCO) and 841 (nPF ). 1H-
6
NMR (CDCl3, d): 8.18 (s, 1H, H(7)), 13.21 (s, 1H, Oꢀ
H, disappeared on shaking with D2O), 6.70 (s, 1H,
H(3)), 6.79Á7.47 (m, 37H, 2PPh3, H(5), H(19), H(22),
/
NMR (CDCl3, d): 8.21 (s, 1H, H(7)), 13.27 (s, 1H, Oꢀ
H, disappeared on shaking with D2O), 6.74 (s, 1H,
H(3)), 6.78 (s, 1H, H(5)), 6.62Á7.33 (m, 34H, 2PPh3,
/
/
H(11), H(12), H(14), H(15)), 1.90 and 2.37 (2s, 6H,
2CH3), 8.76 (d, 1H, H(16), JHH 6.3), 8.19 (t, 1H, H(18),
JHH 6.3), 7.73 (t, 1H, H(24), JHH 7.6), 8.41 (d, 1H,
/
H(11), H(12), H(14), H(15)), 1.94 and 2.37 (2s, 6H,
2CH3), 9.11 (d, 1H, H(16), JHH 6.0), 8.66 (d, 1H, H(18),
JHH 9), 8.05 (d, 1H, H(19), JHH 9.0), 7.94 (d, 1H, H(20),
JHH 9.1), 8.25 (d, 1H, H(21), JHH 6.3), 8.84 (d, 1H,
H(25), JHH 6.0), 8.06 (m, 2H, H(17), H(23)). LMꢂ
/
122
Vꢀ1 cm2 molꢀ1
.

B.K. Panda et al. / Journal of Organometallic Chemistry 674 (2003) 107Á
/115
113
H(23), JHH 6.0), 7.78 (m, 2H, H(17), H(22)). LMꢂ
/
139
H(3)), 6.77Á7.20 (m, 35H, 2PPh3, H(5), H(11), H(12),
/
Vꢀ1 cm2 molꢀ1
.
H(14), H(15)), 1.88 and 2.37 (2s, 6H, 2CH3), 8.86 (d, 1H,
H(16), JHH 6.1), 7.39 (t, 1H, H(17), JHH 7.5), 8.21 (t, 1H,
H(18), JHH 7.5), 7.82 (d, 1H, H(19), JHH 9.0), 8.14 (d,
1H, H(24), JHH 7.2), 7.51 (t, 1H, H(25), JHH 7.5), 7.58 (t,
3.4.2. [Ru(h1-MeOL)(PPh3)2(CO)(phen)](PF6) (3
(OMe))
Ru(h1-MeOL)(PPh3)2(CO)Cl (50 mg, 0.054 mmol)
and phen (85 mg, 0.429 mmol) were used. Yield: 49 mg
(75%). Anal. Found: C, 63.01; H, 4.23; N, 3.49. Calc. for
C64H52F6N3O3P3Ru: C, 63.05; H, 4.30; N, 3.45%. IR
1H, H(26), JHH 7.3), 7.94 (d, 1H, H(27), JHH 9.0). LMꢂ
/
127 Vꢀ1 cm2 molꢀ1
.
3.5.2. [Ru(h1-MeOL)(PPh3)2(CO)(pbt)](PF6) (8
(OMe))
(KBr, cmꢀ1): 1610 (nCN), 1952 (nCO) and 842 (nPF ). 1H-
6
NMR (CDCl3, d): 8.20 (s, 1H, H(7)), 13.29 (s, 1H, Oꢀ
H, disappeared on shaking with D2O), 6.73 (s, 1H,
H(3)), 6.78 (s, 1H, H(5)), 6.62Á7.32 (m, 34H, 2PPh3,
/
Ru(h2-MeOL)(PPh3)2(CO)Cl (50 mg, 0.054 mmol)
and pbt (57 mg, 0.268 mmol) were employed. Yield: 52
mg (77%). Anal. Found: C, 61.39; H, 4.23; N, 3.32. Calc.
for C64H52F6N3O3P3RuS: C, 61.44; H, 4.19; N, 3.36%.
/
H(11), H(12), H(14), H(15)), 1.94 (s, 3H, CH3), 3.84 (s,
3H, OCH3), 9.12 (d, 1H, H(16), JHH 6.0), 8.65 (d, 1H,
H(18), JHH 9.0), 8.04 (d, 1H, H(19), JHH 9.1), 7.94 (d,
1H, H(20), JHH 9.3), 8.25 (d, 1H, H(21), JHH 9.0), 8.84
(d, 1H, H(23), JHH 6.1), 7.77 (m, 2H, H(17), H(22)).
IR (KBr, cmꢀ1): 1610 (nCN), 1959 (nCO) and 841 (nPF ).
6
1H-NMR (CDCl3, d): 8.16 (s, 1H, H(7)), 13.36 (s, 1H,
Oꢀ
/
H, disappeared on shaking with D2O), 6.58 (s, 1H,
H(3)). 6.77Á
/7.17 (m, 35H, 2PPh3, H(5), H(11), H(12),
LMꢂ
/
137 Vꢀ1 cm2 molꢀ1
.
H(14), H(15)), 1.87 (s, 3H, CH3), 3.84 (s, 3H, OCH3),
8.85 (d, 1H, H(16), JHH 6.0), 7.39 (t, 1H, H(17), JHH
7.5), 8.22 (t, 1H, H(18), JHH 7.6), 7.80 (d, 1H, H(19),
JHH 9.1), 8.15 (d, 1H, H(24), JHH 7.3), 7.50 (t, 1H,
H(25), JHH 7.5), 7.55 (t, 1H, H(26), JHH 7.6), 7.96 (d,
3.4.3. [Ru(h1-ClL)(PPh3)2(CO)(phen)](PF6) (3
(Cl))
Ru(h2-ClL)(PPh3)2(CO)Cl (50 mg, 0.054 mmol) and
phen (85 mg, 0.429 mmol) were employed. Yield: 51 mg
(78%). Anal. Found: C, 61.79; H, 4.01; N, 3.37. Calc. for
C63H49ClF6N3O2P3Ru: C, 61.84; H, 4.04; N, 3.43%. IR
1H, H(27), JHH 9.0), LMꢂ
/
135 Vꢀ1 cm2 molꢀ1
.
3.5.3. [Ru(h1-ClL)(PPh3)2(CO)(pbt)](PF6) (8 (Cl))
Ru(h2-ClL)(PPh3)2(CO)Cl (50 mg, 0.054 mmol) and
pbt (57 mg, 0.268 mmol) were employed. Yield: 53 mg
(79%). Anal. Found: C, 60.22; H, 3.96; N, 3.30. Calc. for
C63H49ClF6N3O2P3RuS: C, 60.26; H, 3.93; N, 3.35%. IR
(KBr, cmꢀ1): 1604 (nCN), 1955 (nCO) and 841 (nPF ). 1H-
6
NMR (CDCl3, d): 8.19 (s, 1H, H(7)), 12.96 (s, 1H, Oꢀ
H, disappeared on shaking with D2O), 6.76 (s, 1H,
H(3)), 6.79 (s, 1H, H(5)), 6.61Á7.40 (m, 34H, 2PPh3,
/
/
H(11), H(12), H(14), H(15)), 1.94 (s, 3H, CH3), 9.09 (d,
1H, H(16), JHH 6.0), 8.65 (d, 1H, H(18), JHH 9.1), 8.04
(d, 1H, H(19), JHH 9.0), 7.93 (d, 1H, H(20), JHH 9.0),
8.28 (d, 1H, H(21), JHH 6.3), 8.85 (d, 1H, H(23), JHH
(KBr, cmꢀ1): 1603 (nCN), 1965 (nCO) and 842 (nPF ). 1H-
6
NMR (CDCl3, d): 8.13 (s, 1H, H(7)), 13.02 (s, 1H, Oꢀ
H, disappeared on shaking with D2O), 6.62 (s, 1H,
H(3)), 6.75Á7.18 (m, 35H, 2PPh3, H(5), H(11), H(12),
/
/
6.0), 7.79 (m, 2H, H(17), H(22)). LMꢂ
/
134 Vꢀ1 cm2
H(14), H(15)), 1.87 (s, 3H, CH3), 8.84 (d, 1H, H(16),
JHH 6.1), 7.36 (t, 1H, H(17), JHH 9.0), 8.21 (t, 1H, H(18),
JHH 7.5), 7.81 (d, 1H, H(19), JHH 9.0), 8.12 (d, 1H,
H(24), JHH 7.1), 7.51 (t, 1H, H(25), JHH 7.5), 7.58 (t, 1H,
molꢀ1
.
3.5. Synthesis of the complexes, [Ru(h1-
RL)(PPh3)2(CO)(pbt)](PF6) (8)
H(26), JHH 7.6), 7.95 (d, 1H, H(27), JHH 9.1). LMꢂ
/
123
Vꢀ1 cm2 molꢀ1
.
The [Ru(h1-RL)(PPh3)2(CO)(pbt)](PF6) (8) com-
80%) by
plexes were synthesized in excellent yield (ꢀ
/
3.6. X-ray structure determination
reacting Ru(h2-RL)(PPh3)2(CO)Cl (1) with excess pbt
for 4 h when the colour of the solution changed from
violet to orange. The general procedure for isolation is
similar to what is described for bpy.
Single crystals of [Ru(h1-HL)(PPh3)2(CO)(bpy)]-
(PF6)×CH2Cl2 (2(H)×CH2Cl2) (0.35ꢃ0.30ꢃ
0.20 mm3)
and [Ru(h1-ClL)(PPh3)2(CO)(phen)](PF6)×
H2O (3(Cl)×
H2O) (0.30ꢃ0.25ꢃ
0.20 mm3) were grown by slow
/
/
/
/
/
/
/
/
3.5.1. [Ru(h1-MeL)(PPh3)2(CO)(pbt)](PF6) (8
(Me))
diffusion of hexane into dichloromethane solutions at
room temperature. Cell parameters were determined by
a least-squares fit of 30 machine-centred reflections
Ru(h2-MeL)(PPh3)2(CO)Cl (50 mg, 0.055 mmol) and
pbt (58 mg, 0.273 mmol) were used. Yield: 50 mg (74%).
Anal. Found: C, 62.28; H, 4.21; N, 3.36. Calc. for
C64H52F6N3O2P3RuS: C, 62.23; H, 4.24; N, 3.40%. IR
(2uꢂ
technique on a Siemens R3m/V four-circle diffract-
ometer with graphite-monochromated MoÁKa radia-
0.71073 A). Two check reflections measured
/
14Á
/
288). Data were collected with the v-scan
/
(KBr, cmꢀ1): 1593 (nCN), 1949 (nCO) and 842 (nPF ). 1H-
tion (lꢂ
/
˚
6
NMR (CDCl3, d): 8.15 (s, 1H, H(7)), 13.33 (s, 1H, Oꢀ
/
after every 198 reflections showed no significant inten-
sity reduction in any case. All data were corrected for Lp
H, disappeared on shaking with D2O), 6.59 (s, 1H,

114
B.K. Panda et al. / Journal of Organometallic Chemistry 674 (2003) 107Á115
/
Table 4
Crystal data for 2(Me)×
/
CH2Cl2, 3(Cl)×
/
H2O and 8(Cl)
2(Me)×CH2Cl2
62H52Cl2F6N3O2P3Ru
Complexes
/
3(Cl)×/H2O
8(Cl)
Empirical formula
Formula weight
Crystal system
Space group
C
C63H51ClF6N3O3P3Ru
1241.51
C63H49ClF6N3O2P3SRu
1255.54
Triclinic
1249.95
Monoclinic
P21/c
Monoclinic
P21/n
¯
P1
/
˚
a (A)
19.552(12)
16.332(9)
17.694(8)
15.137(11)
21.549(6)
18.076(6)
13.852(10)
14.375(8)
16.522(8)
108.34(4)
109.94(5)
92.57(5)
2893(3)
˚
b (A)
˚
c (A)
a (8)
b (8)
96.93(4)
103.68(4)
g (8)
3
V (A )
˚
5609(5)
4
0.528
5729(5)
4
0.473
Z
2
0.503
m(MoÁ
Dcalc (g cmꢀ1
Total reflections
Independent reflections (Rint
/
Ka) (mmꢀ1
)
)
1.480
7525
1.441
8725
1.442
7484
)
7173 (0.0621)
0.0733, 0.1672
8356 (0.0219)
0.0580, 0.1526
7312 (0.0577)
0.0718, 0.1820
R1 a, wR2 [I ꢁ
2s(I)]
/
b
a
R1ꢂ
/
a jjFojꢀ
/
jFcjj/a jFoj.
b
/
wR2 ꢂ[a w(Fo2 ꢀFc2)2=a (Fo2)2]:
/
and an empirical absorption correction [13] was done on
the basis of azimuthal scan of six reflections for the
crystals.
4. Conclusion
It is demonstrated that metallacycles of type 1 react
smoothly with bpy/phen furnishing the aryl ruthenium
salts 2/3. The pbt ligand also binds as an a-diimine
yielding 8. The 10
cleavage of the Ruꢀ
chelation of bpy/phen/pbt, iminium-phenolato0
phenol tautomerization and rotameric anti 0syn iso-
merization of the phenolic CꢀO function with respect to
The metal atom was located from Patterson maps and
the rest of the non-hydrogen atoms emerged from
successive Fourier syntheses. The structures were refined
by full-matrix least-squares procedures. All non-hydro-
gen atoms were refined anisotropically and hydrogen
atoms were added at calculated positions. Calculations
were performed using the SHELXTL, Version 5.03 [14]
programme package. Significant crystal data are listed
in Table 4.
/
2/3/8 conversions are attended with
O and RuꢀCl bonds, (N,N)
imine-
/
/
/
/
/
coordinated carbon monoxide. In 2/3/8 the metallated
aryl ring is turned away from the a-diimine chelate plane
due to steric reasons and this results in significantly
Single crystals of [Ru(h1-RL)(PPh3)2(CO)(pbt)](PF6)
(0.30ꢃ
/
0.25ꢃ
/
0.25 mm3) grown in the same way as
¯
above belonged to the chiral space group P1 with Zꢂ2
different Ruꢀ
/
P lengths and an apparent suppression of
carbanionic trans influence. The RuIII/RuII reduction
potentials of 2/3/8 are systematically higher than those
/
(Table 4). The asymmetric unit generated from Patter-
son maps and successive Fourier synthesis consisted of a
nearly centrosymmetric pair of molecules. This vitiated
free least-squares refinement but the gross structure was
revealed with certainty. Only the coordination sphere,
the metallated ring and the pbt ligand could be refined
anisotropically. All the pendant aryl rings (7 per
molecule) were affixed as idealized hexagons.
of 1. The Ru0a-diimine MLCT absorption in the
visible region makes 2/3/8 fluorescent.
/
5. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
3.7. Computer generation of motif 7
Data Centre, CCDC nos. 202253Á202255 correspond-
/
ing to 2, 3 and 8 respectively. Copies of this information
may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
The relative positions of CO and the bpy/phen chelate
were retained as in the structures of 2(H)×
3(Cl)×H2O but the phenolic oxygen O(1) was shifted so
as to correspond to the relative position in 1(Me) [1], the
/CH2Cl2 and
/
(Fax:
ac.uk or www: http://www.ccdc.cam.ac.uk).
ꢁ44-1223-336033; e-mail: deposit@ccdc.cam.
/
˚
O length being set at 1.35 A.
Cꢀ
/

B.K. Panda et al. / Journal of Organometallic Chemistry 674 (2003) 107Á
/115
115
[4] (a) G.G.A. Balavoine, T. Boyer, Organometallics 11 (1992) 456;
(b) M. Haukka, P. Hirva, S. Luukkanen, M. Kallinen, M.
Ahlgren, T.A. Pakkanen, Inorg. Chem. 38 (1999) 3182.
[5] (a) V.W.W. Yam, B.W.K. Chu, C.C. Ko, K.K. Cheung, J. Chem.
Soc. Dalton Trans. (2001) 1911;
Acknowledgements
We thank the Department of Science and Technology,
the Council of Scientific and Industrial Research, New
Delhi, India, for financial support. The help of Dr S.G.
with the fluorescence studies is gratefully acknowledged.
(b) V.W.W. Yam, B.W.K. Chu, K.K. Cheung, J. Chem. Soc.
Chem. Commun. (1998) 2261.
[6] (a) G. Jia, D.W. Meek, J.C. Gallucci, Organometallics 9 (1990)
2549;
(b) A.K. Mahapatra, D. Bandyopadhyay, P. Bandyopadhyay, A.
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