C-P bond forming reactivity of N-heteropentacene: Isolation and characterization of a phospho-ylide complex of ruthenium(II)

Article abstract of DOI:10.1016/j.ica.2010.03.043

In an unusual reaction of H₂L² (H₂L ² = N-heteropentacene) with Ru(PPh₃)₃Cl ₂ a phospho-ylide ruthenium(II) complex (1) was obtained via unprecedented chemical transformations of

Full text of DOI:10.1016/j.ica.2010.03.043

Inorganica Chimica Acta 363 (2010) 2840–2847
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C–P bond forming reactivity of N-heteropentacene: Isolation and characterization
of a phospho-ylide complex of ruthenium(II)
Pradip Ghosh a, Subhas Samanta a, Alfonso Castiñeiras b, Sreebrata Goswami a,
*
a Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032, India
b Departamento de Química Inorgánica, Universidade de Santiago de Compostela, Campus Universitario Sur, 15782 Santiago de Compostela, Spain
a r t i c l e i n f o
a b s t r a c t
In an unusual reaction of H2L2 (H2L2 = N-heteropentacene) with Ru(PPh3)3Cl2 a phospho-ylide ruthe-
nium(II) complex (1) was obtained via unprecedented chemical transformations of the conjugate base
[L2]2À. A bidentated phospho-ylide ligand is formed with concomitant aromatic ring hydroxylation and
new C–P bond formation reactions. The new ligand, binds to RuII as a neutral N, O-donor. Crystal structure
determination by single crystal X-ray diffraction has been used to characterize the compound. The phos-
pho-ylide Ru(II) description of the complex was established based on 13C as well as 31P NMR studies. The
complex shows rich spectral and redox properties. UV–Vis–NIR spectrum consisted of multiple low-
energy transitions in the visible and near IR regions. Preliminary density functional theory calculations
were employed to understand the electronic structure and to assign the spectral transitions. Cyclic vol-
tammogram and EPR-spectrum of the electrogenerated oxidized compound are reported and used to
characterize the redox properties.
Article history:
Received 30 January 2010
Received in revised form 12 March 2010
Accepted 16 March 2010
Available online 27 March 2010
Dedicated to Prof. Animesh Chakravorty
Keywords:
Ruthenium complex
C–P bond formation
C–O bond formation
Phospho-ylide complex
X-ray structure
Redox
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
bond formation reactions are operative in the above transforma-
tion. Furthermore, it has been shown that HL1, upon deprotonation,
Formation of carbon–heteroatom bonds [1–6] by transition me-
tal as mediator has been the subject of intensive investigation in
recent years because these allow syntheses [7–9] of novel mole-
cules of acknowledged importance in pharmaceuticals and biology.
Many of these compounds otherwise are difficult to synthesize or
even inaccessible following the conventional synthetic protocols.
In this respect majority of the efforts have been focused on the for-
mation of carbon–nitrogen [10–18], –oxygen [19–22], and –sulfur
bonds [23–26]. In comparison, however, carbon–phosphorus bond
formation reactions are scanty in the literature [27–34]. It is rele-
vant to note here that phosphorus containing molecules are versa-
tile reagents in organic syntheses [35] and are useful hemilabile
ligands [36–38]. Hemilabile phosphorous containing ligands are
advantageous for their use in homogeneous metal catalyzed organ-
ic transformations since these can mask coordination site(s) effec-
tively and liberate during the course of chemical transformations.
We have long standing interest in the metal-promoted oxida-
tive carbon–nitrogen bond formation reactions of aromatic amines
using transition metal as the mediator [39–52]. For example, we
have described an unusual polymerization reaction of p-anisidine
to an N-substituted phenazine derivative (HL1) using hydrated
FeCl3 as the mediator [48]. Several new and regioselective C–N
acts as a bidentated ligand and undergoes fascinating chemical
transformations [52] including oxygenation and dimerization reac-
tions as depicted in Scheme 1.
Encouraged by the above results, we became curious to study
the coordination behaviour of polyheterocycles like phenazines.
Literature survey has revealed that there has been extensive cur-
rent literature on heteropentacene compounds because of their
versatile
p-functional material property [53] though their coordi-
nation behaviour remains unexplored. In this work, we present
our results on the reaction of Ru(PPh3)3Cl2 and N-heteropentacene
(H2L2). An unprecedented chemical transformation occurred with
the formation of a novel ruthenium complex (1) of a new phospho-
rous ylide ligand. Notably the chemistry of metal complexes with
ylide is a subject of considerable current interest [54] in the con-
text of their versatile coordinating behaviour. Successful isolation
and complete characterization of the aforesaid complex constitute
the primary concern of this work.
2. Results and discussion
2.1. Synthesis and characterization
The availability of the two nitrogen donor sites of the N-hetero-
pentacene, H2L2 for alkylation [55] prompted us to explore its
* Corresponding author. Tel.: +91 3324734971; fax: +91 3324732805.
E-mail address: icsg@iacs.res.in (S. Goswami).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.03.043

P. Ghosh et al. / Inorganica Chimica Acta 363 (2010) 2840–2847
2841
Ar
N
NH
MeO
N
N
Ar
Ar
HL1
M(II)-mediator
MeOH, moist air
Ar
N
Ar
Ar
O
OMe
N
N
N
M
M
+
N
N
MeO
N
N
Ar
Ar
Ar
N
N
Ar
M
N
N
MeO
M=Ru, Ar= -C6H4-OMe
Ar
Ar
Scheme 1.
coordination chemistry with transition metal ions. In alkaline con-
ditions, the two N–H protons of H2L2 are known to undergo depro-
tonation and the corresponding conjugate base remains in
equilibrium with its quinonoid form as shown in Scheme 2. In this
work we have chosen Ru(PPh3)3Cl2 as the starting complex to ex-
plore its coordination chemistry. Facile substitution reactions in
the starting Ru-complex have been well documented in the litera-
ture. It may be relevant to add here that RuII and OsII complexes of
planar nitrogen containing ligands like phenazine can intercalate
[56,57] DNA and RNA effectively and represent an important class
of molecular probes.
phospho-ylide ligand (L3) is formed from the N-heteropentacene
via (i) concomitant hydroxylation at C17 and (ii) a new C–P bond
formation at the C8 site (Scheme 3). The new ligand, thus formed,
binds to RuII as a neutral N, O-donor. The most striking part of the
reference chemical transformation is the formation of a new C–P
bond, which occurs via the migration of PPh3 from ruthenium to
C8 carbon to form a phospho-ylide ligand. The reaction occurs in
moist air as it happens in the metal mediated hydroxylation of
coordinated phenazines. Identical reaction sequences involving
oxidation of the metal centre followed by hydroxylation of the
polarized heteropentacene ring are operative in this transforma-
tion. The source of CO in this reaction is presumably methanol,
since the chemical transformations did not occur in methanol-free
solvent. The mixed ligand complex 1 was obtained in 20% yield.
The poor yield of the compound is consistent with its slow decom-
position in solution to a mixture of unidentified products even at a
room temperature. Notably, the phospho-ylide part in the mole-
cule is free which accounts for the instability/high reactivity of
the molecule. We are yet to obtain any other pure products from
the above chemical reaction due to serious overlap of bands on
the TLC plate.
The compound H2L2 reacts smoothly with Ru(PPh3)3Cl2 in
methanol–dichloromethane solvent mixture at 300 K yielding a
mixture of many products. TLC-purification of the mixture gave a
crystalline yellowish-brown compound 1 as one of the products.
The chemical reaction is shown in Scheme 3. The formation of
the compound 1 is associated with an unexpected chemical trans-
formation that occurred at the coordinated H2L2. A bidentated
H
N
N
N
The complex 1 gave satisfactory elemental analysis (cf., Section
4). Electrospray mass spectrum of the complex corroborate with its
formulation as shown in Scheme 3. For example, it showed an in-
N
H2L2
H
H L2,
2
DCM, MeOH(1:1),
II
moist air
Base
II
Ru(PPh3)Cl2(CO)(L3)
Ru(PPh3)3Cl2
_
N
N
N
R.T
1
N
O1
_
N1
N2
N3
17
_
N
L3
N
8
N4
2
P
N
_
N
[L2]2-
Scheme 2.
Scheme 3.

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P. Ghosh et al. / Inorganica Chimica Acta 363 (2010) 2840–2847
tense peak due to the molecular ion [1ÀClÀ]+ at m/z 985 amu.
Notably, the experimental spectral feature of the Ru-complex cor-
responds very well to the simulated isotopic pattern for the given
formulation (Fig. 1). The 1H NMR spectrum of the compound,
[Ru(PPh3)(CO)Cl2L2] contains several overlapping resonances in
the aromatic region, owing to the presence of a large number of
unique protons in the complex. However, 13C and 31P NMR spectra
of the complex are useful for its characterization. 31P and 13C NMR
signals at 15.08 and 69.16 ppm, respectively confirm the existence
of the ylidic P@C bond [54] in the molecule. 13C resonance due to
the quaternary carbons of C„O, and keto-carbonyl carbon, were
also observed at 212 and 182 ppm, respectively. The additional
peak in the 31P NMR spectrum due to the Ru-coordinated PPh3
was observed at 49.09 ppm. Segmented 13C and 31P NMR spectra
are displayed in Fig. 2. Full range spectra (1H, 13C) are submitted
as Supplementary material (Fig. S1). In the IR spectrum of the com-
plex, two characteristic stretching frequencies for the terminal CO
and keto-carbonyl function (>C@O) appeared at 1935 and
1740 cmÀ1, respectively.
2.2. Crystal structure
Suitable crystals for X-ray structure determination of 1 were
obtained by slow diffusion of a dichloromethane solution of the
compound into hexane. Structural analysis of it indeed confirmed
a novel Ru-mediated chemical transformation of the reference het-
eropentacene molecule. Its molecular view is shown in Fig. 3. OR-
TEP presentation and packing diagrams are submitted as
Supplementary Figs. S2 and S3, respectively. The selected bond
lengths and bond angles are collected in Table 1. The molecule 1
is hexa-coordinated and the coordination sphere has a distorted
octahedral geometry. Moreover, the bond between Ru and the me-
tal-coordinating atoms of the ylide ligand viz. Ru–N1 (2.185(4) Å)
Fig. 2. Segmented NMR spectra of the complex 1 in CDCl3: (A) 13C and (B) 31P.
Fig. 1. ESI-MS spectrum of the complex 1 in CH3CN; simulated spectrum is shown as an inset.

P. Ghosh et al. / Inorganica Chimica Acta 363 (2010) 2840–2847
2843
C8–C9 (1.428(7) Å) are single bonds, while the C8–P2 bond
(1.769(6) Å) is close to an ideal ylidic C@P bond length [54,59]
(Scheme 3 and Table 1). The two possible resonating forms [54]
of the complex are shown in Scheme 4.
2.3. Cyclic voltammetry and EPR
The redox behaviour of the complex 1 was studied by cyclic vol-
tammetry in dichloromethane (0.1 M TBAP) in the potential range
between +1.8 and À1.8 V and using a platinum disc as working
electrode. The potentials are referenced to the saturated Ag/AgCl
electrode. It shows two waves in the above potential range
(Fig. 4). A reversible oxidative response appeared near 0.42 V; the
second response is irreversible and occurs at a cathodic potential,
À1.0 V. One-electron stoichiometry of the reversible anodic wave
was confirmed by exhaustive electrolysis of 1 at 0.6 V. Oxidation
occurs at the metal centre while the redox process occurring at
the cathodic potential is due to the ligand reduction. These results
are corroborated by density functional theory (DFT) calculations,
which show that the HOMO and LUMO of the complex are primar-
ily metal and ligand centred, respectively (see below). One-elec-
tron oxidized complex 1+ showed
a rhombic EPR-spectrum
(Fig. 5) with characteristic splitting pattern of the g components
in frozen solution (cf. Section 4). Two close lying components g1,
g2 > 2 are complemented by g3 < 2. Taken together gav is >2 – a
typical [60] for a low-spin d5 situation (RuIII) with not-too-dis-
torted octahedral ligation. Thus the EPR-spectrum of the electro-
generated compound implies that the oxidation of 1 primarily
occurs at the ruthenium(II) centre.
Fig. 3. Molecular view of the complex 1.
2.4. UV–Vis spectra and DFT
The compound exhibits several low-energy absorptions in the
UV–Vis and near IR region of the spectrum with two broad bands
at 730 and 875 nm (Table 2, Fig. 6). The assignment of these bands
is guided by the results of Density Functional Theory (DFT) calcu-
lations. Before calculation of the excitation energies using time-
dependent DFT (TD-DFT) formalism, the molecular structure of 1
was fully optimized at the B3LYP level of theory. The calculated
bond lengths and angles can be compared well to the crystallo-
graphically established metrical parameters (Table 1). Overall
there is a good agreement with the two sets of numbers as bond
lengths and angles are predicted within 2 pm and 1°–4° from the
experimental values, respectively.
The calculated excitation energies for 1 are collected in Table 3.
The two peaks with transition maxima at 875 and 730 nm can be
readily assigned to 1A (HOMOÀ1 ? LUMO) and 1A (HOMO–2 ?
LUMO). These transitions are computationally predicted at 880
and 679 nm, respectively. Several possible transitions were found
to lie between 300 and 600 nm. However, calculated oscillator
strengths predict that transitions at 875, 730, 460, 405 and
330 nm should dominate the spectrum. Calculated spectrum is
shown in Supplementary Fig. S4 for comparison. The highest oscil-
lator strength is calculated for the 1A transition (predominately
HOMO ? LUMO+2 transition) at 305 nm which is in excellent
agreement with the experimentally observed band maximum at
330 nm.
Table 1
Selected experimental and calculated bond lengths (Å) of 1.
Bonds
Experimental
Calculated
Ru1–O1
Ru1–N1
N1–C1
C1–C2
C2–C3
C3–C4
C4–C5
C5–C6
C6–N4
N4–C7
C7–C8
C8–C9
C9–N3
N3–C10
C10–C11
C11–C12
C12–C13
C13–C14
C14–C15
C15–N2
N2–C16
C16–C17
C17–O1
C8–P2
2.111(4)
2.185(4)
1.352(6)
1.413(6)
1.349(8)
1.419(8)
1.344(7)
1.418(7)
1.338(6)
1.338(6)
1.436(7)
1.428(7)
1.353(6)
1.341(7)
1.420(7)
1.356(9)
1.400(9)
1.346(9)
1.418(9)
1.352(6)
1.338(7)
1.447(7)
1.256(6)
1.769(5)
2.130
2.210
1.371
1.422
1.377
1.425
1.377
1.424
1.357
1.349
1.435
1.430
1.357
1.359
1.424
1.379
1.428
1.378
1.423
1.361
1.337
1.455
1.275
1.777
An analysis of the MOs of the complex reveals that the highest
occupied orbitals, HOMO and HOMOÀ1 are centred on ruthenium
while the HOMOÀ2 is substantially localised (Fig. 7) on the carbon
bonded to PPh3 of the ylide ligand (L3). The lowest unoccupied
MOs, LUMO, LUMO+1 and LUMO+2 are primarily localised on the
ylide ligand. Thus the charge-transfer transition appearing at
875 nm is of MLCT type and the transition at 730 nm may best
be described as an intra-ligand charge-transfer (ILCT) transition.
and Ru–O1 (2.111(4) Å) are similar to those observed in a related
complex of a oxo-phenazine ligand [58]. The bond length C17–
O1 (1.256(6) Å) indicates a localized double bond and the ligand
coordinates as a neutral N,O- donor, which implies the bivalent
oxidation state of the central ruthenium metal. Interestingly, the
two C–C bonds around the C8 carbon, viz. C7–C8 (1.436(7) Å) and

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P. Ghosh et al. / Inorganica Chimica Acta 363 (2010) 2840–2847
N
N
N
N
N
N
Ph
P
Ph
Ph
Ph
_
Ph
O
+
Ph
P
O
II
RuCl2(PPh3)(CO)
II
RuCl2(PPh3)(CO)
N
N
Scheme 4.
pho-ylide ligand was isolated. X-ray structure determination of
the complex has confirmed the formation of a RuII-ylide complex
via a series of unprecedented chemical transformations including
hydroxylation as well as C–P bond formation at heteropentacene
ring. The ruthenium complex showed several low-energy transi-
tions in the visible and near IR region of the spectrum. These are
assigned to metal-to-ligand and intra-ligand charge-transfer tran-
sitions. Preliminary density functional theory calculations were
employed to overview the electronic structure, redox and spectro-
scopic assignments.
4. Experimental
4.1. Materials
The starting metal complex Ru(PPh3)3Cl2 was synthesized
according to the literature procedure [61]. 1,2-diaminobenzene
was purchased from Loba chemicals, (India). 2,5-Dihydroxy p-
benzoquinone was an Aldrich reagent and the solvents used were
obtained from Qualigens and MERCK (India). The ligands were syn-
thesized [53] following the literature procedure. Tetrabutylammo-
nium perchlorate (TBAP) was prepared and recrystallized as
reported before [62]. All other chemicals were of reagent grade
and used as received. Caution! perchlorate salts have to be handled
with care and with appropriate safety precautions.
Fig. 4. Cyclic voltammogram of the complex 1 in CH2Cl2.
4.2. Methods
UV–Vis–NIR absorption spectrum was recorded on a Perkin–El-
mer Lambda 950 UV/Vis spectrophotometer. NMR spectra were ta-
ken on a Bruker Avance DPX 300 spectrometer. Infrared spectra
were obtained using a Perkin–Elmer 783 spectrophotometer. Cyc-
lic voltammetry was carried out in 0.1 M Bu4NClO4 solutions using
a three-electrode configuration (platinum disc working electrode,
Pt counter electrode, Ag/AgCl reference electrode) and a PC-con-
trolled PAR model 273A electrochemistry system. The E1/2 for the
ferrocenium–ferrocene couple under our experimental condition
was 0.39 V. A Perkin–Elmer 240C elemental analyzer was used to
collect micro analytical data (C, H, N). ESI mass spectrum was re-
corded on a micro mass Q-TOF mass spectrometer (serial no. YA
263). EPR-spectrum in the X band was recorded with a JEOL JES-
FA200 spectrometer.
300
320
340
360
380
B/mT
Fig. 5. EPR-spectrum of the complex 1.
4.3. Synthesis
3. Conclusion
A mixture of 100 mg (0.10 mmol) of Ru(PPh3)3Cl2 and 30 mg
(0.106 mmol) of the ligand H2L2 was stirred for 36 h in 1:1 dichlo-
romethane-methanol solvent mixture. The initial bluish color
In an unusual chemical reaction of the N-heteropentacene com-
pound H2L2 and Ru(PPh3)3Cl2, a ruthenium(II) complex of phos-

P. Ghosh et al. / Inorganica Chimica Acta 363 (2010) 2840–2847
2845
Table 2
Experimental and TD-DFT calculated transitions of the complex 1.
Symmetry
Excitation energy (103 cmÀ1
)
oscillator strength
Dominant contributions (>5%)
Experimentally observed
transitions in nm (
e )
, molÀ1cmÀ1
1A
1A
1A
1A
1A
11.024
(907)a
14.618
(684)
19.858
(503)
22.678
(440)
25.277
(395)
0.0533
0.0371
0.0321
0.0355
0.0211
HOMO ? LUMO (10%)
HOMOÀ1 ? LUMO (74%)
HOMOÀ2 ? LUMO (82%)
875 (2939)
730 (2600)
460b
HOMOÀ1 ? LUMO+1 (92%)
HOMOÀ6 ? LUMO (34%)
HOMOÀ2 ? LUMO+1 (49%)
HOMOÀ11 ? LUMO (38%)
HOMOÀ9 ? LUMO (20%)
HOMOÀ1 ? LUMO+5 (11%)
HOMOÀ10 ? LUMO (7%)
HOMOÀ8 ? LUMO (5%)
1A
1A
26.417
(378)
28.001
(357)
0.036
HOMOÀ11 ? LUMO (74%)
HOMOÀ10 ? LUMO (64%)
HOMOÀ12 ? LUMO (48%)
HOMOÀ2 ? LUMO+2 (10%)
HOMOÀ1 ? LUMO+2 (26%)
HOMOÀ13 ? LUMO (22%)
HOMOÀ2 ? LUMO+2 (14%)
HOMOÀ1 ? LUMO+2 (50%)
HOMOÀ6 ? LUMO+1 (68%)
HOMOÀ1 ? LUMO+3 (18%)
HOMOÀ2 ? LUMO+2 (48%)
HOMOÀ13 ? LUMO (7%)
HOMOÀ1 ? LUMO (74%)
0.0444
1A
28.990
(344)
0.1068
405 (11 100)
330 (50 600)
1A
1A
31.840
(314)
32.849
(304)
0.0599
0.8712
a
Values in parentheses are in nm.
Broad shoulder.
b
Table 3
6
Crystallographic data of 1.
6
0.5
0.4
0.3
0.2
0.1
0.0
5
1
5
4
Empirical formula
Molecular mass
T (K)
Crystal system
Space group
a (Å)
C55H38Cl2N4O2P2Ru
3
1020.80
296
2
4
1
monoclinic
P21/n
0
300
400
500
700
800
900
1000
11.6531(5)
31.3838(14)
12.6550(6)
90
98.447(1)
90
4578.0(4)
4
1.481
Wavelength (nm)
Wavelength (nm)
3
2
1
0
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
Dcalcd (g cmÀ3
)
Crystal dimensions (mm)
h Range for data collection (°)
Goodness-of-fit (GOF)
0.15 Â 0.17 Â 0.22
1.3–27.5
1.03
300
400
500
600
700
800
900 1000 1100 1200
Wavelength (nm)
Reflections collected
10 464
Largest difference between peak and hole (e ÅÀ3
)
1.38, À1.29
Fig. 6. UV–Vis–NIR spectrum of the complex 1. Segmented spectra are shown as
insets using different absorbance scale.
Final R indices [I > 2r(I)]
0.0346, 0.0762
changed to brown. The mixture was evaporated on a rotary evap-
orator. The crude mass, thus obtained, was loaded on a preparative
silica TLC plate for purification using dichloromethane as the elu-
ent. A yellowish-brown band of the complex, 1 was collected and
crystallized from CH2Cl2–C6H14 solvent mixture. Several overlap-
ping bands of different colors follow the above brown band. We
are yet to isolate any other pure product from the above TLC-puri-
fication. The characterization data of the complex are as follows:
Yield: 20%. ESI-MS (in acetonitrile solvent): 985 m/z [MÀClÀ]+. IR
electrolyte): 0.42 V (reversible), À1.0 V (irreversible). Anal. Calc.
for C55H38Cl2N4O2P2Ru: C, 64.78; H, 3.82; N, 5.54 Found: C,
64.75; H, 3.79; N, 5.51%.
4.4. Crystallographic measurement
Crystallographic data of the compound 1 are collected in Table
3. Suitable X-ray quality crystals of it were obtained as noted
before.
(in KBr disk): 1935 m(C„O), 1740 m(C@O), 1585 m
(C@N). EPR [1]+ (in
dichloromethane glass at 77 K): 2.139(g1) 2.116(g2) 1.946(g3).
All data were collected on a Bruker SMART APEX-II diffractom-
CV (in dichloromethane at 298 K with TBAP as supporting
eter, equipped with graphite monochromatic Mo K
a radiation

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P. Ghosh et al. / Inorganica Chimica Acta 363 (2010) 2840–2847
Fig. 7. Frontier molecular orbitals of the complex 1 in 0.03 isosurface value.
(k = 0.71073 Å), and were corrected for Lorentz-polarization ef-
fects. The structure was solved by employing the SHELXS-97 program
package [63] and refined by full-matrix least-squares based on F2
like polarisable continuum model [71–73]. GAUSSSUM [74] was used
to calculate the fractional contributions of various molecular orbi-
tal in the optical spectral transition.
(SHELXL-97) [64]. All hydrogen atoms were added in calculated
positions.
Acknowledgements
4.5. Computational details
Financial support received from the Council of Scientific and
Industrial Research (CSIR), New Delhi (Project 01/2358/09/EMR-
II) is gratefully acknowledged. Crystallography was performed at
the DST-funded National Single Crystal Diffractometer Facility at
the Department of Inorganic Chemistry, IACS. We are thankful to
Dr. C.R. Sinha, Jadavpur University for his support in DFT calcula-
tion. P.G. and S.S. are thankful to the Council of Scientific and
Industrial Research, New Delhi for fellowship support.
Full geometry optimization was carried out using the density
functional theory method at the (R) B3LYP [65]. Calculations were
performed without any symmetry constraints. H, C and N were as-
signed the 6-31G(d) basis set. P and Cl were assigned as 6-31G(d,p)
basis set. The LanL2DZ basis set with effective core potential were
employed for the ruthenium atom [66]. The Ru-coordinated tri-
phenylphosphine (PPh3) was replaced by trimethylphosphine
(PMe3). The vibration frequency calculation was performed to en-
sure that the optimized geometries represent the local minima
and there are only positive Eigen values. All calculations were per-
formed with the GAUSSIAN03 programme package [67]. Vertical elec-
tronic excitation based on B3LYP optimized geometries were
computed using the time-dependent density functional theory
(TD-DFT) formalism [68–70] in dichloromethane using conductor
Appendix A. Supplementary material
CCDC 763983 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The
Cambridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this article

P. Ghosh et al. / Inorganica Chimica Acta 363 (2010) 2840–2847
2847
[42] K.N. Mitra, P. Majumder, S.-M. Peng, A. Castiñeiras, S. Goswami, Chem.
Commun. (1997) 1267.
can be found, in the online version, at doi:10.1016/j.ica.
2010.03.043.
[43] K.N. Mitra, S.-M. Peng, S. Goswami, Chem. Commun. (1998) 1685.
[44] P. Majumder, L.R. Falvello, M. Tomás, S. Goswami, Chem. Eur. J. 7 (2001) 5222.
[45] C. Das, S. Goswami, Comments Inorg. Chem. 24 (2003) 137.
[46] K.N. Mitra, S. Goswami, Inorg. Chem. 36 (1997) 1322.
[47] K.N. Mitra, S. Choudhury, A. Castiñeiras, S. Goswami, J. Chem. Soc., Dalton
Trans. (1998) 2901.
[48] A.K. Ghosh, K.N. Mitra, G. Mostafa, S. Goswami, Eur. J. Inorg. Chem. (2000)
1961.
[49] A. Saha, A.K. Ghosh, P. Majumdar, K.N. Mitra, S. Mondal, K.K. Rajak, L.R.
Falvello, S. Goswami, Organometallics 18 (1999) 3772.
[50] A.K. Ghosh, P. Majumdar, L.R. Falvello, G. Mostafa, S. Goswami,
Organometallics 18 (1999) 5086.
[51] C. Das, A. Saha, S.-M. Peng, G.-H. Lee, S. Goswami, Inorg. Chem. 42 (2003) 198.
[52] P. Banerjee, G. Mostafa, A. Castiñeiras, S. Goswami, Eur. J. Inorg. Chem. (2007)
412.
[53] U.H.F. Bunz, Chem. Eur. J. 15 (2009) 6780. and references therein.
[54] L.R. Falvello, J.C. Ginés, J.J. Carbó, A. Lledós, R. Navarro, T. Soler, E.P.
Urriolabeitia, Inorg. Chem. 45 (2006) 6803. and references therein.
[55] Q. Tang, J. Liu, H.S. Chan, Q. Miao, Chem. Eur. J. 15 (2009) 3965.
[56] A.E. Friedman, J.-C. Chambron, J.-P. Sauvage, N.J. Turro, J.K. Barton, J. Am. Chem.
Soc. 112 (1990) 4960.
[57] E. Rüba, J.R. Hart, J.K. Barton, Inorg. Chem. 43 (2004) 4570.
[58] P. Banerjee, A.D. Jana, G. Mostafa, S. Goswami, Eur. J. Inorg. Chem. (2008) 44.
[59] L.R. Falvello, S. Fernández, R. Navarro, E.P. Urriolabeitia, Inorg. Chem. 36 (1997)
1136.
References
[1] K. Godula, D. Sames, Science 312 (2006) 67.
[2] J.B. Fulton, A.W. Holland, D.J. Fox, R.G. Bergman, Acc. Chem. Res. 35 (2002) 44.
[3] K. Muñiz, Chem. Soc. Rev. 33 (2004) 166.
[4] N. Hazari, P. Mountford, Acc. Chem. Res. 38 (2005) 839.
[5] T.E. Müller, K.C. Hultzsch, M. Yus, F. Foubelo, Chem. Rev. 108 (2008) 3795.
[6] D.M. Roundhill, Chem. Rev. 92 (1992) 1.
[7] R. Hili, A.K. Yudin, Nat. Chem. Biol. 2 (2006) 284.
[8] A. Ricci (Ed.), Amino Group Chemistry, From Syntheses to the Life Science,
Wiley-VCH, Wienheim, 2007.
[9] J. Hassan, M. Sévignon, C. Gozzi, E. Schulz, M. Lemaire, Chem. Rev. 102 (2002)
1359.
[10] S.H. Cho, J.Y. Kim, S.Y. Lee, S. Chang, Angew. Chem., Int. Ed. 48 (2009) 9127.
[11] J.L. Brice, J.E. Harang, V.I. Timokhin, N.R. Anasthasi, S.S. Stahl, J. Am. Chem. Soc.
127 (2005) 2868.
[12] J.D. Soper, W. Kaminsky, J.M. Mayer, J. Am. Chem. Soc. 123 (2001) 5594.
[13] G. Bai, D.W. Stephan, Angew. Chem., Int. Ed. 46 (2007) 1856.
[14] J.P. Wolfe, S. Wagaw, J.-F. Marcoux, S.L. Buchwald, Acc. Chem. Res. 31 (1998)
805.
[15] A.R. Muci, S.L. Buchwald, Top. Curr. Chem. 219 (2002) 131.
[16] D.S. Surry, S.L. Buchwald, Angew. Chem., Int. Ed. 47 (2008) 6338.
[17] J.F. Hartwig, Angew. Chem., Int. Ed. 37 (1998) 2046.
[18] J.F. Hartwig, Acc. Chem. Res. 41 (2008) 1534.
[19] E.M. Beccalli, G. Broggini, M. Martinelli, S. Sottocornola, Chem. Rev. 107 (2007)
5318.
[20] Y. Peng, L. Cui, G. Zhang, L. Zhang, J. Am. Chem. Soc. 131 (2009) 5062.
[21] S. Protti, M. Fagnoni, A. Albini, J. Am. Chem. Soc. 128 (2006) 10670.
[22] Jiajia Niu, Hua Zhou, Zhigang Li, Jingwei Xu, Shaojing Hu, J. Org. Chem. 74
(2009) 950.
[23] T. Kondo, T. Mitsudo, Chem. Rev. 100 (2000) 3205.
[24] K. Matsumoto, H. Sugiyama, Acc. Chem. Res. 35 (2002) 915.
[25] R.Y.C. Shin, L.Y. Goh, Acc. Chem. Res. 39 (2006) 301.
[26] M. Arisawa, K. Fujimoto, S. Morinaka, M. Yamaguchi, J. Am. Chem. Soc. 127
(2005) 12226.
[60] J.A. Weil, J.R. Bolton, Electron Paramagnetic Resonance, second ed., Wiley
Interscience, New York, 2007.
[61] T.A. Stephenson, G. Wilkinson, J. Inorg. Nucl. Chem. (1996) 945.
[62] S. Goswami, R.N. Mukherjee, A. Chakravorty, Inorg. Chem. 22 (1983) 2825.
[63] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
[64] G.M. Sheldrick, SHELXL 97. Program for the Refinement of Crystal Structures,
University of Göttingen, Göttingen , Germany, 1997.
[65] C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785.
[66] D. Andrae, U. Haeussermann, M. Dolg, H. Stoll, H. Preuss, Theor. Chim. Acta 77
(1990) 123.
[67] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
J.A. Montgomery, Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A.
Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox,
H.P. Hratchian, J.B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R.E.
Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y.
Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S.
Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K.
Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J.
Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M.
Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A.
Pople, Inc. Gaussian, CT, Wallingford, 2004.
[27] D.J. Brauer, M. Hingst, K.W. Kottsieper, C. Liek, T. Nickel, M. Tepper, O. Stelzer,
W.S. Sheldrick, J. Organomet. Chem. 645 (2002) 14.
[28] A. Stadler, C.O. Kappe, Org. Lett. 4 (2002) 3541.
[29] H.-B. Kraatz, A. Pletsch, Tetrahedron: Asymmetry 11 (2000) 1617.
[30] D.E. Bergbreiter, Y.-S. Liu, S. Furyk, B.L. Case, Tetrahedron Lett. 39 (1998) 8799.
[31] P. Machnitzki, T. Nickel, O. Stelzer, C. Landgrafe, Eur. J. Inorg. Chem. (1998)
1029.
[32] O. Herd, A. Hesbler, M. Hingst, M. Trepper, O. Stelzer, J. Organomet. Chem. 522
(1996) 69.
[33] D. Cai, J.F. Payack, D.R. Bender, D.L. Hughes, T.R. Verhoeven, P.J. Reider, J. Org.
Chem. 59 (1994) 7180.
[34] D. Gelman, L. Jiang, S.L. Buchwald, Org. Lett. 5 (2003) 2315.
[35] For a review see: B.E. Maryanoff, A.B. Reitz, Chem. Rev. 89 (1989) 863.
[36] H. Grützmacher, Angew. Chem., Int. Ed. 47 (2008) 1814.
[37] P. Braunstein, J. Organomet. Chem. 689 (2004) 3953.
[38] P. Braunstein, F. Naud, Angew. Chem. 113 (2001) 702. Angew. Chem., Int. Ed.
40 (2001) 680.
[39] S. Samanta, S. Goswami, J. Am. Chem. Soc. 131 (2009) 924.
[40] S. Samanta, L. Adak, R. Jana, G. Mostafa, H.M. Tuononen, B.C. Ranu, S. Goswami,
Inorg. Chem. 47 (2008) 11062.
[68] R. Bauernschmitt, R. Ahlrichs, Chem. Phys. Lett. 256 (1996) 454.
[69] R.E. Stratmann, G.E. Scuseria, M.J. Frisch, J. Chem. Phys. 109 (1998) 8218.
[70] M.E. Casida, C. Jamorski, K.C. Casida, D.R. Salahub, J. Chem. Phys. 108 (1998)
4439.
[71] V. Barone, M. Cossi, J. Phys. Chem. A 102 (1998) 1995.
[72] M. Cossi, V. Barone, J. Chem. Phys. 115 (2001) 4708.
[73] M. Cossi, N. Rega, G. Scalmani, V. Barone, J. Comput. Chem. 24 (2003) 669.
[74] N.M. O’Boyle, A.L. Tenderholt, K.M. Langner, J. Comput. Chem. 29 (2008) 839.
[41] K.N. Mitra, S. Goswami, Chem. Commun. (1997) 49.