Molecular and spectroscopic properties of chloride and thiocyanate hydridecarbonyl ruthenium(II) complexes with pyridine derivative ligands

Article abstract of DOI:10.1016/j.poly.2011.01.035

[RuH(CO)(dpa)(PPh₃)₂]X and [RuHX(CO)(pyCHPh)(PPh ₃)₂] (X = Cl, NCS) complexes (where dpa = 2,2′-dipyridylamine, pyCHPh = 4-(3-phenylpropyl)pyridine) have been prepared and studied using IR, NMR, UV-Vis spectroscopies and X-ray crystallography. The electronic structures and bonding of the obtained complexes were defined on the basis of the DFT method. The electronic spectra of the complexes were calculated and associated with the structure of the molecular orbitals of the complexes. The luminescence properties of the complexes were determined.

Full text of DOI:10.1016/j.poly.2011.01.035

Polyhedron 30 (2011) 1225–1232
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Molecular and spectroscopic properties of chloride and thiocyanate
hydridecarbonyl ruthenium(II) complexes with pyridine derivative ligands
⇑
´
J.G. Małecki , A. Maron
Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
a r t i c l e i n f o
a b s t r a c t
[RuH(CO)(dpa)(PPh3)2]X and [RuHX(CO)(pyCHPh)(PPh3)2] (X = Cl, NCS) complexes (where dpa = 2,20-
dipyridylamine, pyCHPh = 4-(3-phenylpropyl)pyridine) have been prepared and studied using IR, NMR,
UV–Vis spectroscopies and X-ray crystallography. The electronic structures and bonding of the obtained
complexes were defined on the basis of the DFT method. The electronic spectra of the complexes were
calculated and associated with the structure of the molecular orbitals of the complexes. The lumines-
cence properties of the complexes were determined.
Article history:
Received 26 December 2010
Accepted 28 January 2011
Available online 7 March 2011
Keywords:
Ruthenium hydrido-carbonyl complexes
Ruthenium thiocyanate complexes
2,20-Dipyridylamine
4-(3-Phenylpropyl)pyridine
X-ray structure
Ó 2011 Elsevier Ltd. All rights reserved.
UV–Vis
Luminescence
DFT
TD-DFT
1. Introduction
Here, we present the synthesis, crystal, molecular and elec-
tronic structures, and spectroscopy characterization of two pairs
Pyridine type ligands have energetically low lying
p
-antibond-
of hydrido-carbonyl complexes of ruthenium(II) with 2,20-dipyri-
dylamine (dpa) (1), and 4-(3-phenylpropyl)pyridine (pyCHPh) (2)
ligands. The complexes are synthesized as the chloride and thiocy-
anate derivatives. The luminescent properties of the complexes
were examined. The experimental studies on the thiocyanate and
chloride complexes have been accompanied computationally by
density functional theory (DFT) calculations. Currently, DFT is com-
monly used to examine the electronic structure of transition metal
complexes. It meets with the requirements of being accurate, easy
to use and fast enough to render studies of relatively large mole-
cules of transition metal complexes possible. DFT and TDDFT calcu-
lations were performed to establish the nature of the orbitals
involved in the transition processes and to correlate the structural
parameters with the spectroscopic properties of the complexes. It
is known that thiocyanate ligands tune the t2g ruthenium orbital
by distributing 4dRu energy levels over a wide energy range due
to mixing with orbitals centered on the NCS ligand (2pN, 2pC and
3pS) [13]. The calculated density of states showed that intermolec-
ular as well as intramolecular interactions are important and
significantly influence the orbital composition in the frontier elec-
tronic structure. Thus, studies of the electronic structures of com-
plexes are an important area of chemistry. The complexes reported
in this paper combine our interest in ruthenium coordination com-
pounds and complexes containing pyridine derivatives ligands
[14–17].
ing orbitals, which can accept electrons from filled d orbitals of me-
tal atoms. As a consequence, they can exhibit charge transfer bands
with interesting spectroscopic properties in the visible region [1].
Ligands containing a pyridine ring are wide studied and their
-donor properties are interesting. Their combination with other
donor atoms should in principle afford complexes with tunable
spectroscopic properties [2]. The hydride ligand, powerful
-donor, is found to be very efficient at compensating for electron
deficiency at the metal central ion in complexes. The ‘‘trans effect’’
of the Hꢀ ligand and the interaction between CO and N-donor
ligands in trans positions to one another are stabilizing factors
which explain the stability of these complexes [3]. They are inter-
esting because of their properties. Additionally, luminescent metal
complexes are a fascinating class of molecules that have found
applications in many areas. Luminescent ruthenium(II) complexes,
especially with bipyridyl type ligands, have been extensively
studied [4–7]. Furthermore, phosphine hydride carbonyl ruthe-
nium(II) complexes with N-donor ligands are still of interest for
their potential applications [8–12]. Hence, the synthesis and spec-
tral characterization of new ruthenium complexes containing tri-
phenylphosphine are of great importance.
p
a
r
⇑
Corresponding author.
E-mail address: gmalecki@us.edu.pl (J.G. Małecki).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.01.035

´
J.G. Małecki, A. Maron / Polyhedron 30 (2011) 1225–1232
1226
2: Yield 62%. IR (KBr, cmꢀ1): 3052 mArH; 2928, 2854
(Ru–H); 1925 (CO); 1642 (C@N); 1616 (C@C); 1479 d(C–CH in the plane)
1432 ; 1092 d(C–CH in the plane); 746 d(C–C out of the plane); 694 d(C–C
in the plane); 510
(1.46), 256.2 (2.56), 210.6 (5.02). 1H NMR (d, CDCl3): 8.262 (d, H2/
mCH; 2000
2. Experimental
m
m
m
m
;
m
All reagents used for the synthesis of the complexes are com-
mercially available and have been used without further purifica-
tion. The [RuHCl(CO)(PPh3)3] complex was synthesized according
to the literature method [18].
Ph(P–Ph)
m
(P–Ph + P–Ru). UV–Vis (methanol, nm) (log e): 332.0
6
py), 7.604–7.222 (m, Ph/PPh3), 6.495 (s, H3/5py), 2.586, (CH2),
2.193 (CH2), 1.113 (CH2), ꢀ13.517 (t, HRu, J = 19.69 Hz). 31P NMR
(d, CDCl3): 45.666 (s, PPh3), 43.247 (s, PPh3).
2a: Yield 65%. IR (KBr, cmꢀ1): 3051 mArH; 2938, 2856
m
CH; 2091
(C@C); 1480
Ph(P–Ph); 1093 d(C–CH in the plane); 797 d(SC)
746 d(C–C out of the plane); 694 d(C–C in the plane); 519 d(SC); 512 m(P–Ph
2.1. The synthesis of [RuH(CO)(dpa)(PPh3)2]ClꢁdpaꢁCH3OH (1),
[RuH(CO)(dpa)(PPh3)2]SCNꢁH2OꢁCH3OH (1a) and [RuHCl(CO)
(pyCHPh)(PPh3)2] (2), [RuH(SCN)(CO)(pyCHPh)(PPh3)2] (2a)
mSCN; 2001
m(Ru–H); 1934 m(CO); 1617 m(C@N); 1586 m
d(C–CH in the plane); 1433
m
;
P–Ru). UV–Vis (methanol, nm) (log e): 328.4 (1.19), 276.2 (1.37),
The complexes were synthesized in the reaction between
[RuHCl(CO)(PPh3)3] (1 ꢂ 10ꢀ4 mol) and 2,20-dipyridylamine (dpa)
(1), 4-(3-phenylpropyl)pyridine (pyCHPh) (2) (1.2 ꢂ 10ꢀ4 mol)
and NH4SCN (1a and 2a) in methanol solutions (50 cmꢀ3). The mix-
ture of reagents was refluxed in methanol for 3 h. After this time, it
was cooled and filtered. Crystals suitable for X-ray crystal analysis
were obtained by slow evaporation of the reaction mixture.
+
252.1 (2.96), 211.0 (4.98). 1H NMR (d, CDCl3): 8.523 (d, H2/6py),
7.542–7.186 (m, Ph/PPh3), 6.506 (s, H3/5py), 2.611, 2.450, 2.326
(CH2), 1.846, 1761 (CH2), 1.580, 1.284 (CH2), ꢀ12.619 (td, HRu
,
J = 19.35 Hz). 31P NMR (d, CDCl3): 46.794 (s, PPh3), 44.874 (s, PPh3).
2.2. Physical measurements
1: Yield 50%. IR (KBr, cmꢀ1): 3400
m
NH/OH; 3060, 3014 mArH/CH
;
Infrared spectra were recorded on a Perkin–Elmer spectropho-
tometer in the spectral range 4000–450 cmꢀ1 using KBr pellets.
Electronic spectra were measured on a Lab Alliance UV–VIS 8500
spectrophotometer in the range 500–180 nm in methanol solution.
1H and 31P NMR spectra were obtained at room temperature in
CDCl3 using a Bruker 400 spectrometer. Luminescence measure-
ments were made in methanolic solutions on an F-2500 FL spectro-
photometer at room temperature.
1994
m(C@C)
d(C–CH
m(Ru–H); 1922 m(CO); 1639 m(C@N); 1590 m(C@N) dpa; 1520
free
dpa; 1476, 1310 d(C–CH
plane); 774 d(C–C
plane); 1434
plane); 696 d(C–C
m
Ph(P–Ph); 1091
;
in the plane)
free
in the
in the
out of the
511 m(P–Ph P–Ru).UV–Vis (methanol, nm) (log e): 360.5 (1.23),
+
310.4 (1.90), 260.1 (2.86), 213.3 (5.12). 1H NMR (d, CDCl3):
11.392 (s, NH), 8.281–6.868 (m, dpa/PPh3), 3.501 (CH3OH),
ꢀ12.231 (t, HRu, J = 19.19 Hz). 31P NMR (d, CDCl3): 48.424 (s, PPh3).
1a: Yield 50%. IR (KBr, cmꢀ1): 3410
m
NH/OH; 2918
(C@N); 1580
Ph(P–Ph); 1090 d(C–CH in the plane); 816 d(SC)
plane); 695 d(C–C plane); 517 d(NCS). UV–Vis
m
ArH; 2057
m
SCN; 1971
d(C–CH in the plane); 1432
772 d(C–C
m
(Ru–H); 1923
m
(CO); 1641
m
m(C@C); 1477
m
;
2.3. DFT calculations
out of the
in the
(methanol, nm) (log
e
): 362.0 (1.31), 327.0 (1.79), 308.0 (2.10),
The calculations were carried out using the GAUSSIAN09 [19] pro-
gram. The DFT/B3LYP/CAM-B3LYP [20,21] method was used for the
geometry optimization and electronic structure determination,
and electronic spectra were calculated by the TD-DFT [22] method.
255.5 (4.66), 211.5 (5.02). 1H NMR (d, CDCl3): 10.305 (s, NH),
7.804–6.194 (m, dpa/PPh3), 3.501 (CH3OH), 1.613 (H2O), ꢀ12.217
(t, HRu, J = 19.69 Hz). 31P NMR (d, CDCl3): 47.996 (s, PPh3).
Table 1
Crystal data and structure refinement details of the complexes [RuH(CO)(dpa)(PPh3)2]ClꢁdpaꢁCH3OH (1), [RuH(CO)(dpa)(PPh3)2]SCNꢁH2OꢁCH3OH (1a), [RuHCl(CO)
(pyCHPh)(PPh3)2] (2) and [RuH(SCN)(CO)(pyCHPh)(PPh3)2] (2a).
1
1a
2
2a
Empirical formula
Formula weight
T (K)
C
58H53ClN6O2P2Ru
C49H46N4O3P2RuS
933.97
295(2)
C51H46ClNOP2Ru
887.35
295(2)
C52H46N2OP2RuS
909.98
295(2)
1064.52
295(2)
Crystal system
Space group
Unit cell dimensions
a (Å)
b (Å)
c (Å)
triclinic
P1
monoclinic
P21/c
triclinic
P1
monoclinic
P21/n
ꢀ
ꢀ
13.679(3)
14.347(4)
15.156(5)
98.077(3)
116.474(4)
97.915(3)
2567.75(16)
2
9.866(3)
13.009(3)
13.276(4)
13.276(3)
76.064(2)
75.894(2)
87.776(19)
2157.71(9)
2
13.269(9)
14.930(10)
23.967(13)
90
100.736(6)
90
4664.7(5)
4
1.296
14.252(4)
31.797(10)
90
97.230(3)
90
4435.3(2)
4
1.399
a
(°)
b (°)
c
(°)
V [Å3]
Z
Dcalc (Mg/m3)
1.377
0.469
1100
1.366
0.538
916
Absorption coefficient (mmꢀ1
F(0 0 0)
)
0.519
1928
0.488
1880
Crystal dimensions (mm)
h range for data collection (°)
Index ranges
0.18 ꢂ 0.15 ꢂ 0.05
3.36 to 25.05
ꢀ16 6 h 6 16
ꢀ17 6 k 6 16
ꢀ13 6 l 6 18
18 677
0.32 ꢂ 0.18 ꢂ 0.09
3.45 to 25.05
ꢀ11 6 h 6 11
ꢀ16 6 k 6 16
ꢀ30 6 l 6 37
29 457
0.38 ꢂ 0.27 ꢂ 0.10
3.47 to 25.05
ꢀ15 6 h 6 15
ꢀ15 6 k 6 15
ꢀ15 6 l 6 15
39 769
0.35 ꢂ 0.26 ꢂ 0.19
3.37 to 25.05
ꢀ12 6 h 6 15
ꢀ17 6 k 6 12
ꢀ28 6 l 6 28
15 767
Reflections collected
Independent reflections (Rint
Data/restraints/parameters
Goodness-of-fit on F2
)
9008 (0.0295)
9008/0/636
0.939
7804 (0.0349)
7804/0/555
1.177
7632 (0.0316)
7632/0/518
1.058
8232 (0.0355)
8232/0/536
1.038
Final R indices [I > 2
r
(I)]
R1 = 0.0309
wR2 = 0.0688
R1 = 0.0475
wR2 = 0.0713
0.571 and ꢀ0.606
R1 = 0.0468
wR2 = 0.0921
R1 = 0.0560
wR2 = 0.0943
0.460 and ꢀ0.624
R1 = 0.0275
wR2 = 0.0719
R1 = 0.0392
wR2 = 0.0753
0.396 and ꢀ0.257
R1 = 0.0363
wR2 = 0.0762
R1 = 0.0531
wR2 = 0.1187
1.192 and ꢀ1.450
R indices (all data)
Largest difference in peak and hole (e Åꢀ3
)

´
1227
J.G. Małecki, A. Maron / Polyhedron 30 (2011) 1225–1232
The calculations were performed using a DZVP basis set [23] with f
2.4. Crystal structure determinations and refinements
functions having exponents of 1.94722036 and 0.748930908 for
the ruthenium atom, and polarization functions for all other
atoms: 6-31g⁄⁄ – sulfur, carbon, nitrogen and 6-31g – hydrogen.
The PCM (Polarizable Continuum Model) solvent model was used
in the Gaussian calculations, with methanol as the solvent. Natural
bond orbital (NBO) calculations were performed with the NBO
code [24] included in GAUSSIAN09. The contribution of a group to a
molecular orbital was calculated using Mulliken population analy-
sis. GAUSSSUM 2.2 [25] was used to calculate group contributions to
molecular orbitals and to prepare partial density of states (DOS)
spectra. The DOS spectra were created by convoluting the molecu-
lar orbital information with Gaussian curves of unit height and a
FWHM (Full Width at Half Maximum) of 0.3 eV. Mayer bond orders
were calculated with use of the QMFORGE program [26].
Pale yellow plate crystals of [RuH(CO)(dpa)(PPh3)2]Clꢁdpa.-
CH3OH (1), [RuH(CO)(dpa)(PPh3)2]SCNꢁH2OꢁCH3OH (1a), [RuHCl
(CO)(pyCHPh)(PPh3)2] (2) and [RuH(SCN)(CO)(pyCHPh)(PPh3)2]
(2a) were mounted in turn on an Xcalibur, Atlas, Gemini Ultra Ox-
ford Diffraction automatic diffractometer equipped with a CCD
detector, and were used for data collection. X-ray intensity data
were collected with graphite monochromated Mo K
(k = 0.71073 Å) at a temperature of 295(2) K, with the
a
radiation
scan
x
mode. Ewald sphere reflections were collected up to 2h = 50.10°.
The unit cell parameters were determined from least-squares
refinement of the setting angles of 11 167, 16 717, 23 955 and
6472 strongest reflections for complexes 1, 1a, 2 and 2a respec-
tively. Details concerning crystal data and refinement are gathered
Fig. 1. IR spectra of the complexes [RuH(CO)(dpa)(PPh3)2]Cl.dpa.CH3OH (1) and [RuH(SCN)(CO)(pyCHPh)(PPh3)2] (2a).

´
J.G. Małecki, A. Maron / Polyhedron 30 (2011) 1225–1232
1228
in Table 1. During the data reduction, the decay correction coeffi-
cient was taken into account. Lorentz, polarization and numerical
absorption corrections were applied. The structures were solved
by the Patterson method. All the non-hydrogen atoms were refined
anisotropically using the full-matrix, least-squares technique on F2.
The Ru–H hydrogen atoms were found from difference Fourier syn-
thesis after four cycles of anisotropic refinement, and refined as
‘‘riding’’ on the adjacent atom with an individual isotropic temper-
ature factor equal to 1.2 times the value of the equivalent temper-
ature factor of the parent atom, with geometry idealization after
each cycle. The OLEX2 [27] and SHELXS97, SHELXL97 [28] programs were
used for all the calculations. Atomic scattering factors were those
incorporated in the computer programs.
[RuH(SCN)(CO)(pyCHPh)(PPh3)2] (2a) were synthesized using
NH4SCN in the reactions. The 1H NMR spectra of the complexes dis-
played sets of signals, given in the experimental section, that were
ascribed to the N-heteroaromatic and triphenylphosphine ligands.
The triplets at ꢀ12.231, ꢀ12.217, ꢀ13.517 and ꢀ12.619 ppm indi-
cate a hydride ligand in the complexes 1, 1a, 2 and 2a respectively.
Singlets in the 31P NMR spectra of complexes 1 and 1a at 48.424
and 47.996 ppm indicate both triphenylphosphine ligands in the
compounds are equivalent and they are mutually trans disposed.
In the 31P NMR spectra of complexes 2 and 2a, two singlets at
45.666, 43.247 and 46.794, 44.874 ppm indicate that the PPh3 li-
gands are not exactly trans disposed.
IR spectra of the complexes present ring C@N stretching modes
of the pyridine derivative ligands at 1639 and 1642 cmꢀ1 for the
chloride complexes 1 and 2, and at 1641 and 1617 cmꢀ1 in the iso-
thiocyanate derivatives 1a and 2a, respectively. In the spectrum of
complex 1, C@N and C@C stretches of a free ligand are observed at
1590 and 1520 cmꢀ1. NH and OH (methanol) groups are indicated
by a broad band with a maximum at 3400 cmꢀ1. The intense bands
with maxima near 2000 cmꢀ1 in the IR spectra indicate the pres-
ence of hydride ligands in the complexes, and stretching modes
3. Results and discussion
[RuH(CO)(dpa)(PPh3)2]Cl.dpa.CH3OH (1) and [RuHCl(CO)
(pyCHPh)(PPh3)2] (2) complexes were obtained by the reaction of
[RuHCl(CO)(PPh3)3] with 2,20-dipyridylamine (dpa) and 4-(3-
phenylpropyl)pyridine (pyCHPh) in methanol solutions. Isothiocy-
anate analogs [RuH(CO)(dpa)(PPh3)2]SCNꢁH2OꢁCH3OH (1a) and
Fig. 2. ORTEP drawing of the complexes [RuH(CO)(dpa)(PPh3)2]Clꢁdpa.CH3OH (1), [RuH(CO)(dpa)(PPh3)2]SCNꢁH2OꢁCH3OH (1a), [RuHCl(CO)(pyCHPh)(PPh3)2] (2) and
[RuH(SCN)(CO)(pyCHPh)(PPh3)2] (2a) with 50% probability displacement ellipsoids. Hydrogen atoms (except for Ru–H) are omitted for clarity.

´
1229
J.G. Małecki, A. Maron / Polyhedron 30 (2011) 1225–1232
of the carbonyl group are observed at 1922, 1923, 1925 and
1934 cmꢀ1 for complexes 1, 1a, 2 and 2a, respectively. Three char-
acteristic bands are observed at 2057, 816 and 517 cmꢀ1 in the IR
spectrum of 1a, and at 2091, 797 and 519 cmꢀ1 for 2a, ascribed to
C78). The coordinated molecule of dpa shows also a sign of disor-
der, but it is rather dynamical in character.
3.1. Electronic structure
m(CN), m(CS) and d(NCS) respectively. Fig. 1 presents the IR spectra of
complexes 1 and 2a. For N-bonded complexes, generally the C–N
stretching band is in a lower region, around 2050 cmꢀ1, compared
to that of 2100 cmꢀ1 for S-bonded complexes. However, the fre-
quencies of the bands are sensitive to other factors like coexisting
ligands, and the structure of the compounds were determined
using X-ray analysis. While M–S–C angles of S-bonded thiocyanato
ligands in complexes are bent, at around 110°, M–N–C angles of
N-bonded isothiocyanato ligands are close to linear. The Ru(1)–
N(2)–C(52) angle in complex 2a is 169.2(8)°, indicating an isothio-
cyanato ligand. The trans effect of the Hꢀ ligand results in an
elongation of the Ru(1)–N(3) bond in complexes 1 and 1a by about
0.05 Å compared to the Ru(1)–N(1) bond distances. The chloride
To obtain an insight into the electronic structures and bonding
properties of the complexes, calculations using the density func-
tional theory (DFT) method were carried out. Before the calcula-
tions, their geometries were optimized in singlet states using the
DFT method with the B3LYP functional. In general, the predicted
bond lengths and angles are in good agreement with the values
based on the X-ray crystal structure data, and the general trends
observed in the experimental data are well reproduced in the cal-
culations (Table 2). As an example, the calculated IR frequencies of
1 are presented in Fig. 1.
The densities of states (DOS) in terms of Mulliken population
analysis were calculated using the GAUSSSUM program, and Fig. 3 pre-
sents the composition of the fragment orbitals contributing to the
molecular orbitals. As can be seen from Fig. 3, the dRu orbitals play
a significant role in the frontier Homo orbitals of the complexes.
The contributions of d orbitals of the ruthenium central ions in
occupied molecular orbitals are in the range 45–60% (Homo–
Homo ꢀ 3) in the cationic complex 1, and 25–50% (Homo–
Homo ꢀ 6) in complex 2. In the thiocyanate analogs, the values
vary from 30% to 48% in 1a and 13% to 71% in neutral complex
2a. In these molecular orbitals, the triphenylphosphine ligands
play a significant role. As can be seen from the DOS diagrams,
the 2,20-dipyridylamine ligand contributes in a wider range of
ꢀ
complexes crystallize in the triclinic space group P1 and the isoth-
iocyanato analogs – in the monoclinic P21/c and P21/n space
groups. The molecular structures of the complexes are shown in
Fig. 2. Selected bond lengths and angles are listed in Table 2. In
the complexes, the ruthenium atoms have a disordered octahedral
environment. The triphenylphosphine ligands in complexes 2 and
2a are not in perfect trans positions, which coincides with the 31P
NMR data. In the case of complex 1, the solvent (methanol) mole-
cule is better modeled as disordered, but the differences in R
factors are very small (3.09 and 3.04 with disorder). A similar sit-
uation occurs in the case of a free dpa molecule (for atoms C76–
Table 2
Selected bond lengths (Å) and angles (°) for the complexes [RuH(CO)(dpa)(PPh3)2]ClꢁdpaꢁCH3OH (1), [RuH(CO)(dpa)(PPh3)2]SCNꢁH2OꢁCH3OH (1a), [RuHCl(CO)(pyCHPh)(PPh3)2] (2)
and [RuH(SCN)(CO)(pyCHPh)(PPh3)2] (2a).
1
1a
2
2a
exp
calc
exp
exp
calc
exp
Bond lengths [Å]
Ru(1)–C(1)
Ru(1)–N(1)
Ru(1)–N(3)/N(2)
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–Cl(1)
Ru–H1(Ru)
C(1)–O(1)
1.828(2)
2.150(18)
2.197(18)
2.384(6)
2.369(6)
1.852
2.181
2.252
2.428
2.408
1.837(4)
2.156(3)
2.219(3)
2.385(9)
2.366(10)
1.823(3)
2.203(19)
1.858
2.274
1.829(9)
2.191(6)
2.169(9)
2.360(18)
2.348(17)
2.362(5)
2.352(5)
2.537(6)
1.56(2)
2.436
2.424
2.605
1.60
1.55(2)
1.157(3)
1.59
1.159
1.55(4)
1.62(5)
1.152(5)
1.143(8)
1.599(7)
1.154(3)
1.162
1.156(12)
1.110(11)
1.630(12)
N–C(S)
S–C(N)
Angles (°)
P(1)–Ru(1)–P(2)
C(1)–Ru(1)–N(3)/N(2)
P(1)–Ru(1)–N(1)
P(1)–Ru(1)–C(1)
N(1)–Ru(1)–N(3)/N(2)
P(2)–Ru(1)–N(1)
P(2)–Ru(1)–C(1)
P(2)–Ru(1)–N(3) /N(2)
P(1)–Ru(1)–N(3) /N(2)
N(1)–Ru(1)–C(1)
P(2)–Ru(1)–H(1)
N(3)/N(2)–Ru(1)–H(1)
N(1)–Ru(1)–H(1)
C(1)–Ru(1)–H(1)
P(1)–Ru(1)–H(1)
C(1)–Ru(1)–Cl(1)
N(1)–Ru(1)–Cl(1)
P(1)–Ru(1)–Cl(1)
P(2)–Ru(1)–Cl(1)
H(1)–Ru(1)–Cl(1)
Ru(1)–C(1)–O(1)
Ru(1)–N(2)–C(52)
N–C–S
170.77(2)
97.71(8)
90.76(5)
89.18(7)
88.14(7)
89.50(5)
89.63(7)
97.93(5)
91.29(5)
174.15(8)
85.20(8)
173.60(8)
86.30(8)
87.80(8)
85.60(8)
169.22
99.93
91.38
89.42
85.95
91.33
86.83
97.63
92.96
174.02
83.00
174.00
88.00
86.00
87.00
172.55(3)
172.83(14)
92.06(8)
89.74(12)
86.51(11)
95.33(8)
89.76(12)
89.02(8)
90.56(8)
100.64(14)
83.00(15)
89.20(14)
175.40(14)
83.60(14)
89.60(15)
176.39(19)
175.66
169.64(8)
97.80(3)
92.33(14)
86.50(2)
87.20(3)
89.83(14)
90.40(2)
90.09(5)
90.57(7)
89.61
88.56
91.34(5)
87.44(7)
92.72
88.59
97.90(2)
92.30(2)
169.63(9)
87.90(8)
171.15
88.00
174.90(3)
80.80(17)
170.60(17)
86.80(17)
88.10(18)
89.20(17)
80.70(8)
89.00(8)
89.10(8)
102.12(8)
88.17(5)
93.01(19)
90.34(19)
168.70(8)
174.50(2)
169.20(8)
85.00
86.00
89.00
100.08
88.66
92.92
90.81
174.00
176.37
176.90(2)
177.08
175.60(4)
178.20(7)
176.80(8)
169.20(8)
177.30(12)

´
1230
J.G. Małecki, A. Maron / Polyhedron 30 (2011) 1225–1232
Fig. 3. The density of states (DOS) diagrams for the complexes.
Homo orbitals than the 4-(3-phenylpropyl)pyridine ligand. In the
complexes, the Lumo orbitals are mainly localized on the pyridine
derivative ligands. The d orbitals of the ruthenium central ions con-
tribute in Lumo + 1 (neutral complexes 2 and 2a) and Lumo + 3/+5
in the cationic complexes 1 and 1a. Furthermore, the dRu orbitals
are diffused in energy scope, corresponding to Lumo + 16 to
Lumo + 20 levels. In these unoccupied orbitals, the carbonyl ligand
plays a significant role. In Fig. 3, the dashed lines represent the
orbitals of the chloride and thiocyanate anions in complexes 1
and 1a respectively. It can be seen that thiocyanate is better
matched in terms of energy to the molecular orbitals of the com-
plex. In complexes 2 and 2a, in which chloride and isothiocyanate
ligands are in the coordination sphere, noticeable increases in the
energy levels of Homo orbitals with respect to the chloride com-
plex occur. This change in energy levels of the molecular orbitals
refers to the luminescent properties of the complexes.
The Mayer bond orders of the Ru–P, Ru–CO and Ru–H bonds are
similar in the complexes and are close to 1.4, 2.6 and 1.7 respec-
tively. The values of the bond orders between the ruthenium cen-
tral ions and the N-donor ligands are also similar, and these are
lower than 1 (close to 0.7), indicating the participation of ionic
character in the bonds. The Ru–NCS bond order (0.9) is slightly
lower than that of Ru–Cl (1.1) in complexes 2a and 2 respectively.
In order to compare the donor–acceptor properties of 2,20-dipyri-
dylamine and 4-(3-phenylpropyl)pyridine, NBO calculations were
performed. The NBO analyses show that the donations from the
ruthenium central ions to the pyridine derivative ligands have val-
ues 51.23 (53.26) and 24.23 (25.13) kcal/mol, and the back dona-
tions are 150.46 (163.45) and 52.97 (55.16) kcal/mol in the
complexes 1 (1a) and 2 (2a) respectively. The data show the
stronger donor–acceptor properties of 2,20-dipyridylamine than
4-(3-phenylpropyl)pyridine.
3.2. Electronic spectra
The UV–Vis spectra of the studied chloride and thiocyanate
complexes are similar and the maxima are located at 360.5,
310.4, 260.1, 213.3 and 327.0, 308.0, 255.5, 211.5 nm for com-
plexes 1 and 1a and 332.0, 256.2, 210.6 and 328.4, 276.2, 252.1,
211.0 nm for 2 and 2a respectively. Assignments of the calculated
transitions to the experimental bands are based on the criteria of
energy and oscillator strength of the calculated transitions. In the
description of the electronic transitions, only the main components
of the molecular orbitals are taken into consideration. The elec-
tronic transitions were calculated with the application of the
CAM-B3LYP functional, using the Coulomb-attenuating method.
The first transitions (above 300 nm) in the spectra have Homo/
Homo ꢀ 1 ? Lumo and Homo ? Lumo + 1/+3 character in the cat-
ionic and neutral complexes. The Homo is localized on the d ruthe-
nium orbitals with an admixture of p-PPh3/dpa in 1, 1a and p-Cl/
SCN in 2, 2a complexes. The Lumos are localized on the pyridine
derivatives and triphenylphosphine ligands, with a contribution
of dRu, and Metal–Ligand Charge Transfer transitions are associated
with these. The bands observed at 260, 255, 256 and 276 nm have
been attributed to Metal–Ligand Charge Transfer transitions
(d ! pꢃPPh =dpa=pyCHPh=Cl=SCN). In this energy region, the transitions
3

´
1231
J.G. Małecki, A. Maron / Polyhedron 30 (2011) 1225–1232
between the Homo ? Lumo + 8, Homo ꢀ 7/ꢀ4/ꢀ3 ? Lumo + 2/+3
were calculated. The highest energy bands with maxima at 212
and 211 nm are attributed to transitions of Ligand–Ligand Charge
ligand, its presence is only indicated for the lower Homo orbitals
(Homo ꢀ 4 and below in energy). In the Lumo orbitals, the partici-
pation of the N-heteroaromatic ligands in all complexes is similar.
Therefore an emission originating from the lowest energy metal
to ligand charge transfer (MLCT) state, derived from the excitation
Transfer type (
p
!
pꢃC@ ).
N
The emission characteristics of the complexes have been exam-
ined in methanol solutions (with concentration of 5 ꢂ 10ꢀ4 mol/
dm3) at room temperature. The excitations were executed at wave-
lengths corresponding to the maxima of the first electronic absorp-
tions, i.e. at 360 nm for 1 and 1a, and 330 nm for 2 and 2a. The
emission spectra are shown in Fig. 4. As can be seen in Fig. 4, the cat-
ionic complexes 1 and 1a give stronger luminescence than the
neutral complexes 2 and 2a. It is associated with the participation
of the pyridine derivative ligand orbitals in the frontier Homo orbi-
tals of the complexes. The DOS diagrams show that 2,20-dipyridyl-
amine plays a role in the energy range adequate to frontier
occupied orbitals, and in the case of the 4-(3-phenylpropyl)pyridine
involving a d
? pligand transition, is observed. The assignment is
p
also supported by the analysis of the frontier orbitals of the corre-
sponding complexes showing a contribution of ligand nature. The
complicated structure of the luminescence spectra suggests that
more than one state is involved in the luminescence processes.
Replacement of the chloride ligand with a thiocyanate ligand signif-
icantly increases the emission intensity, especially in the case of the
cationic complex 1a. In Fig. 3, the chloride and thiocyanate anions
in complexes 1 and 1a are presented by dashed lines. As one can
see, the energies of the
to the levels of the molecular orbitals of the complex in contrast to
p
-orbitals of the NCSꢀ ligands are well tuned
Fig. 4. The emissions spectra of the complexes 1, 1a and 2, 2a in methanolic solutions (c = 5 ꢂ 10ꢀ4 mol/dm3).

´
J.G. Małecki, A. Maron / Polyhedron 30 (2011) 1225–1232
1232
the energy of the p orbitals of Clꢀ. In the case of neutral complex 2a,
the isothiocyanate ligand shifts the Homo and Homo ꢀ 1 orbitals to
a higher energy.
[2] A.K. Singh, P. Kumar, M. Yadav, D.S. Pandey, J. Organomet. Chem. 695 (2010)
567.
[3] B.J. Coe, S.J. Glenwright, Coord. Chem. Rev. 203 (2000) 5.
[4] M.U. Raja, N. Gowri, R. Ramesh, Polyhedron 29 (2010) 1175.
[5] R. Sivakumar, A.T.M. Marcelis, S. Anandan, J. Photochem. Photobiol. A: Chem.
208 (2009) 154.
[6] T. Funaki, M. Yanagida, N. Onozawa-Komatsuzaki, Kaługa Kasuga, Y.
Kawanishi, M. Kurashige, K. Sayama, H. Sugihara, Inorg. Chem. Commun. 12
(2009) 842.
[7] N. Onozawa-Komatsuzaki, M. Yanagida, T. Funaki, K. Kasuga, K. Sayama, H.
Sugihara, Inorg. Chem. Commun. 12 (2009) 1212.
[8] S. Kannan, M. Sivagamasundari, R. Ramesh, Yu Liu, J. Organomet. Chem. 693
(2008) 2251.
[9] M. Sivagamasundari, R. Ramesh, Spectrochim. Acta, Part A 67 (2007) 256.
[10] M. Sivagamasundari, R. Ramesh, Spectrochim. Acta, Part A 66 (2007) 427.
[11] M.V. Kaveri, R. Prabhakaran, R. Karvembu, K. Natarajan, Spectrochim. Acta,
Part A 61 (2005) 2915.
[12] M. Ulaganatha Raja, N. Gowri, R. Ramesh, Polyhedron 29 (2010) 1175.
[13] E.M.J. Johansson, M. Odelius, M. Gorgoi, O. Karis, R. Ovsyannikov, F. Schäfers, S.
Svensson, H. Siegbahn, H. Rensmo, Chem. Phys. Lett. 464 (2008) 192.
[14] J.G. Małecki, Polyhedron 29 (2010) 1237.
4. Conclusion
Summarizing, new ruthenium(II) complexes with pyridine
derivative ligands have been synthesized. The molecular structures
of the complexes were determined by X-ray crystallography, and
the spectroscopic properties were studied using infrared, 1H and
31P NMR spectra. Based on the crystal structures, computational
studies were carried out in order to determine the electronic
structures of the complexes. The results were used to compare
the
p-donor/acceptor properties of the pyridine type ligands.
Electronic spectra were calculated with use of the TD-DFT method
and the transitions characters were discussed in connection with
structure of the molecular orbitals of the complexes. The emission
properties of the complexes have been examined. Emissions origi-
nating from the lowest energy metal to ligand charge transfer
[15] J.G. Małecki, Polyhedron 29 (2010) 1973.
[16] J.G. Małecki, Polyhedron 29 (2010) 2489.
[17] J.G. Małecki, Polyhedron 29 (2011) 79.
[18] N. Ahmad, J.J. Levinson, S.D. Robinson, M.F. Uttely, Inorg. Synth. 15 (1974) 48.
[19] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M.
Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y.
Honda, O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery Jr., J.E. Peralta, F. Ogliaro,
M. Bearpark, J.J. Heyd, E. Brothers, K.N. Kudin, V.N. Staroverov, R. Kobayashi, J.
Normand, K. Raghavachari, A. Rendell, J.C. Burant, S.S. Iyengar, J. Tomasi, M.
Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, 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, R.L. Martin, K. Morokuma, V.G. Zakrzewski, G.A. Voth,
P. Salvador, J.J. Dannenberg, S. Dapprich, A.D. Daniels, O. Farkas, J.B. Foresman,
J.V. Ortiz, J. Cioslowski, D.J. Fox, Gaussian 09, Revision A.1, Gaussian Inc.,
Wallingford, CT, 2009.
(MLCT) state, derived from an excitation involving a d
? pligand
p
transition, are observed. The assignment is supported by the
analysis of the frontier orbitals of the corresponding complexes
showing a partial contribution of ligands nature. The thiocyanate
derivative of the cationic complex with the 2,20-dipyridylamine
ligand exhibits a very intense luminescence compared to the chlo-
ride analog.
Appendix A. Supplementary data
[20] A.D. Becke, J. Chem. Phys. 98 (1993) 5648;
CCDC 784657, 792144, 794419 and 798323 contain the supple-
mentary crystallographic data for [RuH(CO)(dpa)(PPh3)2]Cl.dpa.
C. Lee, W. Yang, R.G. Parr, Phys. Rev. B 37 (1988) 785.
[21] T. Yanai, D. Tew, N. Handy, Chem. Phys. Lett. 393 (2004) 51.
[22] M.E. Casida, in: J.M. Seminario (Ed.), Recent Developments and Applications of
Modern Density Functional Theory, Theoretical and Computational Chemistry,
vol. 4, Elsevier, Amsterdam, 1996, p. 391.
[23] K. Eichkorn, F. Weigend, O. Treutler, R. Ahlrichs, Theor. Chim. Acc. 97 (1997)
119.
[24] E.D. Glendening, A.E. Reed, J.E. Carpenter, F. Weinhold, NBO (version 3.1).
[25] N.M. O’Boyle, A.L. Tenderholt, k.M. Langner, J. Comp. Chem. 29 (2008) 839.
[26] Adam L. Tenderholt, QMForge, Version 2.1, Stanford University, Stanford, CA,
USA.
[27] O.V. Dolomanov, L.J. Bourhis, R.J. Gildea, J.A.K. Howard, H. Puschmann, J. Appl.
Crystallogr. 42 (2009) 339.
CH3OH,
[RuH(CO)(dpa)(PPh3)2]SCN.H2O.CH3OH,
[RuHCl(CO)
(pyCHPh)(PPh3)2] and [RuH(SCN)(CO)(pyCHPh)(PPh3)2]. These data
can be obtained free of charge via http://www.ccdc.cam.ac.uk/
conts/retrieving.html, or from the Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44)
1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk. Calculations
have been carried out in the Wroclaw Centre for Networking and
Supercomputing (http://www.wcss.wroc.pl)
[28] G.M. Sheldrick, Acta Crystallogr., Sect. A 64 (2008) 112.
References
[1] M. Chandra, A.N. Sahay, D.S. Pandey, M.C. Puerta, P. Valerga, J. Organomet.
Chem. 648 (2002) 39.