Synthesis, spectroscopic and structural characterizations of two new complexes of ruthenium with 2-(hydroxymethyl)benzimidazole and 1,10-phenanthroline ligands

Article abstract of DOI:10.1016/j.poly.2009.08.035

The complexes [RuCl(CO)(PPh₃)₂(HBIm)] and [RuH(CO)(PPh₃)₂(1,10-phen)]Cl·H₂O·(CH₃)₂O have been prepared and studied by IR and UV-Vis spectroscopy, and X-ray crystallography. The c

Full text of DOI:10.1016/j.poly.2009.08.035

Polyhedron 28 (2009) 3891–3898
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis, spectroscopic and structural characterizations of two new complexes
of ruthenium with 2-(hydroxymethyl)benzimidazole and 1,10-phenanthroline
ligands
b
c
J.G. Małecki a, , R. Kruszynski , Z. Mazurak
*
a Department of Inorganic and Coordination Chemistry, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
b
_
´
´
X-ray Crystallography Laboratory, Institute of General and Ecological Chemistry, Technical University of Łódz, 116 Zeromski St., 90-924 Łódz, Poland
c Polish Academy of Sciences, Centre of Polymer Chemistry, M. Sklodowskiej-Curie 34, Zabrze 41-819, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 July 2009
Accepted 31 August 2009
Available online 27 September 2009
The complexes [RuCl(CO)(PPh3)2(HBIm)] and [RuH(CO)(PPh3)2(1,10-phen)]ClꢀH2Oꢀ(CH3)2O have been
prepared and studied by IR and UV–Vis spectroscopy, and X-ray crystallography. The complexes were
prepared in the reactions of [RuHCl(CO)(PPh3)3] with 2-(hydroxymethyl)benzimidazole or 1,10-phenan-
throline two hydrate in acetone. The electronic spectra of the obtained compounds have been calculated
using the TDDFT method. The luminescence properties of these complexes were examined.
Ó 2009 Elsevier Ltd. All rights reserved.
Keywords:
Ruthenium hydride carbonyl complexes
2-(Hydroxymethyl)benzimidazole
1,10-Phenanthroline
X-ray structure
UV–Vis
Luminescence
DFT
TDFFT
1. Introduction
are relatively less studied but their moderate p-donor properties
are interesting. Its combination with other donor atoms should in
principle afford complexes with tuneable spectroscopic properties.
The studied compounds merge the benefits of ruthenium coor-
dination compounds and complexes containing 2-(hydroxy-
The study of spectroscopic (particularly UV–Vis) and lumines-
cence properties of Ru(II) complexes is an ongoing and active area
of research, mainly concerning applications of these compounds in
energy conversion and as sensors. In most of these complexes, the
ligands are N-heterocyclic imines involving imidazole and phenan-
throline. The wide interest is this field originates from a very rich
redox chemistry and photophysics of these compounds. Even a
small change in the coordination environment around ruthenium
plays a key role in altering the redox properties of the complexes.
Thus complexation of ruthenium by various ligands is very inter-
esting and widely studied [1–7].
methyl)benzimidazole or 8-hydroxyquinoline and
a carbonyl
group, thus their synthesis and determination of their properties
was undertaken. In this paper we present the synthesis, crystal,
molecular and electronic structures, including the luminescence,
and spectroscopy characterization, of some new carbonyl ruthe-
nium(II) complexes.
2. Experimental
The coordination compounds of transition and non-transition
metals containing 8-hydroxyquinoline complexes are also very
interesting due to their applications in OLED materials [8–9].
8-Hydroxyquinoline is also commonly used for analytical determi-
nation of metals such as Al3+, Ga3+, Pd2+ [10]. Due to its optoelec-
tronic efficiency, the interest in the synthesis and properties of
compounds containing 8-hydroxyquinoline and transition metals
lately is increasing [11–14]. Ligands containing an imidazole ring
All reagents were commercially available and were used with-
out further purification.
2.1. Synthesis of [RuCl(CO)(PPh3)2(HBIm)] (1) and [RuH(CO)(PPh3)2
(1,10-phen)]ClꢀH2Oꢀ(CH3)2O (2) (HBIm = 2-(hydroxymethyl)
benzimidazole)
Both complexes were synthesized in the reaction between
[RuHCl(CO)(PPh3)3] (0.95 g; 1 ꢁ 10ꢂ3 mol) and (0.15 g; 1 ꢁ 10ꢂ3 mol)
2-(hydroxymethyl)benzimidazole or (0.16 g; 1 ꢁ 10ꢂ3 mol) 1,10-
* Corresponding author.
E-mail addresses: gmalecki@us.edu.pl (J.G. Małecki), rafal.kruszynski@p.lodz.pl
(R. Kruszynski), mazurak@cchp-pan.zabrze.pl (Z. Mazurak).
0277-5387/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2009.08.035

3892
J.G. Małecki et al. / Polyhedron 28 (2009) 3891–3898
phenanthroline two hydrate in refluxing acetone (100 cmꢂ3). Crystals
suitable for X-ray crystal analysis were obtained by slow evaporation
of the reaction mixture.
sphere reflections were collected up to 2h = 50.06. The unit cell
parameters were determined from least-squares refinement of
the setting angles of 2771 (1) and 7998 (2) strongest reflections.
Details concerning crystal data and refinement are gathered in
Table 1. During the data reduction, the decay correction coefficient
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.
All the hydrogen atoms were found from difference Fourier synthe-
sis after four cycles of anisotropic refinement, and were 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 idealisation after
each cycle. SHELXS97 [21], SHELXL97 [22] and SHELXTL [23] programs
were used for all the calculations. Atomic scattering factors were
those incorporated in the computer programs.
2.2. [RuCl(CO)(PPh3)2(HBIm)] (1)
Yield: 71%. Colour: yellow. IR (KBr, cmꢂ1): 3056
CH–phenyl; 1927 C„O; 1622 CN; 1482 d(C–CH plane); 1436
Ph(P–Ph); 1272 C–O; 1062 d(C–CH in the plane); 742 d(C–C out of the plane)
31P NMR (d ppm, CDCl3): 42.087 (s, PPh3). UV–
mCH; 2961
m
m
m
m
in the
m
;
695 d(C–C in the plane)
.
Vis (acetonitrile, nm): 355.4 (2.72), 281.2 (5.22), 274.3 (5.26),
243.0 sh (5.31), 211.0 (5.83). Emission: excitation 355; lumines-
cence 450. Anal. Calc. for C45H37ClN2O2P2Ru: C, 64.90; H, 4.74; Cl,
4.16; N, 3.29; O, 3.76; P, 7.28; Ru, 11.87. Found: C, 64.81; H,
4.66; N, 3.31%.
2.3. [RuH(CO)(PPh3)2(1,10-phen)]ClꢀH2Oꢀ(CH3)2O (2)
Yield: 65%. Colour: yellow. IR (KBr, cmꢂ1): 3442
CH; 2903 CH–phenyl; 20 015–1923 mC Ru–H; 1626
d(C–CH in the plane); 1433 Ph(P–Ph); 1225 C–O; 1095 d(C–CH in the plane)
696 d(C–C
31P NMR (d ppm, CDCl3): 46.153 (s, PPh3).
UV–Vis (acetonitrile, nm): 395.9 (2.91), 330 (sh), 272.6 (3.07),
212.0 (3.62). Emission: excitation 330, 395; luminescence 465,
467. Anal. Calc. for C52H47ClN2O3P2Ru: C, 65.99; H, 5.01; Cl, 3.75;
N, 2.96; O, 5.07; P, 6.55; Ru, 10.68. Found: C, 65.93; H, 5.03; N, 2.99%.
m
OH; 3048
3. Results and discussion
m
m
„
m
+
m
mCN; 1481
O
m
;
The reactions of the ruthenium(II) carbonyl hydride complex
[RuHCl(CO)(PPh3)3] with 2-(hydroxymethyl)benzimidazole and
1,10-phenanthroline have been performed. Refluxing the [RuHCl-
(CO)(PPh3)3] complex with a small excess of the ligands in acetone
leads to the carbonyl complex [RuCl(CO)(PPh3)2(HBIm)] and the
cationic complex [RuH(CO)(PPh3)2(1,10-phen)]Cl with good yields.
Elemental analysis of the complexes is in a good agreement with
their formulas. Infrared spectra of the complexes exhibit character-
.
in the plane)
2.3.1. Physical measurements
Infrared spectra were recorded on a Nicolet Magna 560 spectro-
photometer in the spectral range 4000–400 cmꢂ1 with the sample
in the form of a KBr pellet. Electronic spectra were measured on a
Lab Alliance UV–Vis 8500 spectrophotometer in the range of 500–
180 nm in deoxygenated acetonitrile solution. Elemental analyses
(C, H, N) were performed on a Perkin–Elmer CHN-2400 analyzer.
The 31P NMR spectrum was obtained at room temperature in CDCl3
using an INOVA 300 spectrometer. Luminescence measurements
were made on a Jobin-Yvon (SPEX) FLUOROLOG-3.12 spectrofluo-
rometer at room temperature.
istic bands due to ligand rings vibrations. The mC
@ band in the
N
complexes appears around 1622 (1) and 1626 cmꢂ1 (2). The mC
@
O
bands in these compounds appear around 1927 (1) and 1923
(
mC„O + m
Ru–H) cmꢂ1 (2). The singlet at 42.087 and 46.153 ppm for
complexes (1) and (2), respectively, in the 31P NMR spectra indi-
Table 1
Crystal data and structure refinement details of [RuCl(CO)(PPh3)2(2-(HBIm)] (1) and
[RuH(CO)(PPh3)2(1,10-phen)]Cl (2).
1
2
Empirical formula
Formula weight
T (K)
Crystal system
Space group
Unit cell dimensions
a (Å)
C45H37ClN2O2P2Ru C52H47ClN2O3P2Ru
2.3.2. DFT calculations
836.23
946.38
293.0(2)
orthorhombic
Pnma
293.0(2)
triclinic
P1
The calculations were carried out using the GAUSSIAN03 [15] pro-
gram. The DFT/B3LYP [16,17] method was used for the geometry
optimization and electronic structure determination, and elec-
tronic spectra were calculated by the TDDFT [18] method. The cal-
culations were performed using the DZVP basis set [19] with f
functions with exponents 1.94722036 and 0.748930908 on the
ruthenium atom, and polarization functions for all other atoms:
6-31g(2d,p) – chlorine, 6-31g** – carbon, nitrogen and 6-31g(d,p)
– hydrogen. The PCM solvent model was used in the GAUSSIAN calcu-
lations with acetonitrile as the solvent. GaussSum 2.1 [20] was
used to calculate the group contributions to the molecular orbitals
and to prepare the partial density of states (PDOS) spectra. The
contribution of a group to a molecular orbital was calculated using
Mulliken population analysis. The PDOS spectra were created by
convoluting the molecular orbital information with Gaussian
curves of unit height and FWHM of 0.3 eV.
ꢀ
16.908(15)
23.845(2)
9.8420(9)
13.622(4)
13.675(6)
14.985(5)
102.824(3)
103.244(3)
116.323(4)
2261.8(14)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
3968.0(6)
4
Z
Calculated density (Mg/m3)
Absorption coefficient (mmꢂ1
F(0 0 0)
1.400
0.583
1712
1.390
0.522
976
)
Crystal dimensions (mm)
0.132 ꢁ 0.079 ꢁ 0.070
0.097 ꢁ 0.093 ꢁ 0.007
h Range for data collection (°)
1.71–25.03
ꢂ20 6 h 6 20
ꢂ28 6 k 6 28
ꢂ11 6 l 6 11
73 253
1.76–25.03
ꢂ16 6 h 6 16
ꢂ15 6 k 6 16
ꢂ16 6 l 6 17
23 194
Index ranges
2.4. Crystal structure determination and refinement
Reflections collected
Independent reflections [R(int)
Data/restraints/parameters
Goodness-of-fit (GOF) on F2
]
2771 [0.0881]
3603/0/262
0.961
R1 = 0.0398
wR2 = 0.0981
R1 = 0.0599
wR2 = 0.1039
1.753 and ꢂ0.970
7998 [0.0537]
7998/0/552
0.887
R1 = 0.0336
wR2 = 0.0715
R1 = 0.0631
wR2 = 0.0854
0.589 and ꢂ0.631
A yellow plate crystal of [RuCl(CO)(PPh3)2(HBIm)] (1) and a yel-
low prism of [RuH(CO)(PPh3)2(1,10-phen)]ClꢀH2Oꢀ(CH3)2O (2) were
Final R indices [I > 2
r
(I)]
mounted in turn on
a KM-4-CCD automatic diffractometer
equipped with a CCD detector, and used for data collection. X-ray
intensity data were collected with graphite monochromated Mo
R indices (all data)
Largest difference in peak and
hole (e Åꢂ3
K
the
a
radiation (k = 0.71073 Å) at temperature of 293.0(2) K, with
scan mode. Exposure times of 33 s were used and Ewald
)
x

J.G. Małecki et al. / Polyhedron 28 (2009) 3891–3898
3893
cated both the triphenylphosphine ligands in the studied com-
pounds are equivalent and are mutually trans disposed.
space group. The molecular structures of these compounds are
shown in Figs. 1 and 2 (structural drawings are presented in Figs.
3 and 4). Selected bond lengths and angles are listed in Tables 2
and 3. In both studied complexes the ruthenium atoms have a dis-
torted octahedral environment with trans triphenylphosphine li-
gands (angle P–Ru–P 176.51(4)° 1 and 166.36(3)° 2). The O and
N donor atoms of 2-(hydroxymethyl)benzimidazole in complex 1
are in trans positions to the carbonyl (C(27)–Ru(1)–O(1)
3.1. Crystal structure
The [RuCl(CO)(PPh3)2(HBIm)] (1) complex crystallises in the
orthorhombic space group Pnma, and the [RuH(CO)(PPh3)2(1,10-
ꢀ
phen)]ClꢀH2Oꢀ(CH3)2O (2) complex crystallises in the P1 triclinic
Fig. 1. ORTEP drawing of [RuCl(CO)(PPh3)2(HBIm)] with 50% probability thermal ellipsoids. Hydrogen atoms are omitted for clarity.
Fig. 2. ORTEP drawing of [RuH(CO)(PPh3)2(1,10-phen)]Cl with 50% probability thermal ellipsoids. Hydrogen atoms (except the Ru–H) and solvents are omitted for clarity.

3894
J.G. Małecki et al. / Polyhedron 28 (2009) 3891–3898
Table 3
Selected bond lengths (Å) and angles (°) for [RuH(CO)(PPh3)2(1,10-phen)]Cl (2) with
the optimized geometry values.
Exp.
Calc.
Bond lengths (Å)
Ru(1)–N(1)
Ru(1)–N(2)
Ru(1)–P(1)
2.174(3)
2.133(3)
2.359(9)
2.364(9)
1.828(4)
1.153(4)
1.513
2.255
2.183
2.451
2.451
1.870
1.161
1.611
Fig. 3. Structural drawing of [RuCl(CO)(PPh3)2(HBIm)].
Ru(1)–P(2)
Ru(1)–C(49)
C(49)–O(1)
Ru(1)–H(1Ru)
PPh3
Angles (°)
H
N
C(49)–Ru(1)–N(1)
C(49)–Ru(1)–N(2)
N(1)–Ru(1)–N(2)
C(49)–Ru(1)–P(1)
C(49)–Ru(1)–P(2)
N(1)–Ru(1)–P(1)
N(1)–Ru(1)–P(2)
N(2)–Ru(1)–P(1)
N(2)–Ru(1)–P(2)
P(1)–Ru(1)–P(2)
C(49)–Ru(1)–H(1RU)
N(2)–Ru(1)–H(1RU)
N(1)–Ru(1)–H(1RU)
P(1)–Ru(1)–H(1RU)
P(2)–Ru(1)–H(1RU)
101.45(13)
178.05(13)
76.60(11)
90.78(11)
90.26(11)
96.22(8)
96.90(8)
89.30(8)
90.11(7)
166.36(3)
85.7
103.97
179.33
75.36
88.39
88.38
95.07
95.07
91.67
91.68
169.83
88.70
91.98
167.34
85.15
85.14
Ru
OC
PPh3
Fig. 4. Structural drawing of [RuH(CO)(PPh3)2(1,10-phen)]Cl.
Table 2
96.3
172.2
80.4
86.2
Selected bond lengths (Å) and angles (°) for [RuCl(CO)(PPh3)2(HBIm)] (1) with the
optimized geometry values.
Exp.
Calc.
Bond lengths (Å)
Ru(1)–N(1)
Ru(1)–O(1)
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–Cl(1)
Ru(1)–C(27)
C(27)–O(1)
Ru(1)–O(1)
2.058(3)
2.107(3)
2.399(8)
2.399(8)
2.407(13)
1.845(6)
1.111(6)
2.107(3)
2.133
2.154
2.472
2.472
2.461
1.862
1.163
2.154
optimized geometric parameters are gathered in Tables 2 and 3.
In general, the predicted bond lengths and angles are in a 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 calculations.
The maximum differences between the optimized and experi-
mental geometries of the studied compounds are visible in the
Angles (°)
C(27)–Ru(1)–N(1)
C(27)–Ru(1)–O(1)
N(1)–Ru(1)–O(1)
C(27)–Ru(1)–P(1)
N(1)–Ru(1)–P(1)
O(1)–Ru(1)–P(1)
C(27)–Ru(1)–Cl(1)
N(1)–Ru(1)–Cl(1)
O(1)–Ru(1)–Cl(1)
P(1)–Ru(1)–Cl(1)
P(1)–Ru(1)–P(1A)
95.82(18)
174.38(17)
78.56(13)
90.70(2)
91.52(2)
89.46(2)
95.31(16)
168.87(10)
90.31(10)
88.34(2)
97.48
174.91
77.43
92.90
92.96
87.41
91.67
170.86
93.43
86.55
171.09
Ru(1)–N(1) distance (ꢃ0.075 Å) for complex
1 Ru(1)–P(1)
(ꢃ0.092 Å) for 2 and in the angle P(1)–Ru(1)–P(1A), 5.4° for 1,
and N(1)–Ru(1)–H(1RU), 4.9° for 2.
3.1.2. Electronic structure and NBO analysis
In the studied complexes, the occupied dxy and dxz ruthenium
orbitals participate in back-donation from the central ion to the
carbonyl ligand. The largest contribution of the pRu–CO bonding
interaction is visible in the H-3 and H-2 orbitals for compound 1,
and H-4 and H-3 for 2. The p*Ru–CO orbitals are also distributed
among several unoccupied molecular orbitals. Their contributions
are visible in the L + 11 and L + 15, and L + 12 and L + 15 orbitals
for complexes 1 and 2, respectively. The HOMO orbitals of the
studied complexes are composed of the dxz ruthenium orbital.
The LUMO orbitals are localised on the phosphine ligand in com-
plex 1 and on the phenanthroline ligand in complex 2. The dz2 orbi-
tal of the Ru atom makes the largest contribution into LUMO (1)
and L + 2 (2), whereas L + 9, L + 11 in compound 1 and L + 15 in
176.51(4)
174.38(17)°) and chloride (N(1)–Ru(1)–Cl(1) 168.87(10)°) ligands,
respectively. In complex 2, the nitrogen donors of 1,10-phenan-
throline are in trans positions to the carbonyl and hydride ligands.
The C(27)–O(1) bond in complex 1 shows some shortening in
comparison with typical distances in CO substituents, but similar
distances can be found in several compounds [24–41]. The
Ru(1)–N(1) bond distance is longer in complex 2 compared with
Ru(1)–N(2), due to the trans effect of the hydride ligand. All Ru–li-
gand distances in both studied compounds are normal and compa-
rable with distances in other ruthenium complexes containing the
heterocyclic ligands.
The conformation of molecule 1 is stabilised by two intramolec-
ular weak hydrogen bonds, linking coordinated O(1) and phenyl
C(12) (Dꢀ ꢀ ꢀA distance 3.067(5) Å and D–Hꢀ ꢀ ꢀA angle 152.6°) and
carbonyl oxygen O(2) and carbon C(24) from the benzimidazole li-
gand (Dꢀ ꢀ ꢀA distance 3.419(7) Å and D–Hꢀ ꢀ ꢀA angle 150.1°).
compounds 1 and 2 have dx2
character. The energy and character
ꢂy2
of the selected frontier molecular orbitals are gathered in Table 4.
In the frontier region, neighboring orbitals are often closely spaced.
In such cases, consideration of only the HOMO and LUMO may not
yield a realistic description of the frontier orbitals. For this reason,
partial density of states (PDOS) diagrams, which incorporate a de-
gree of overlap between the curves convoluted from neighboring
energy levels, can give a more representative picture of the nature
of the frontier orbitals. The PDOS diagrams obtained are shown in
Fig. 5. The HOMOꢂLUMO gaps are 4.06 and 3.62 eV for 1 and 2,
respectively.
3.1.1. Optimized geometries
The geometries of the studied complexes were optimized in sin-
glet states using the DFT method with the B3LYP functional. The
Basing on the NBO theory [42], occupancy and hybridization of
the calculated natural bond orbital between the ruthenium and

J.G. Małecki et al. / Polyhedron 28 (2009) 3891–3898
3895
Table 4
The energies and characters of selected molecular orbitals for complexes 1 and 2.
[RuCl(CO)(PPh3)2(2-(hydroxymetyl)benzimidazole)] (1)
[RuHCl(CO)(phen)(PPh3)2]+ (2)
E (eV)
Character
E (eV)
Character
phosphine(59); pphen(32)
pphosphine
pphen
pphen
pphosphine
pphen
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
HOMOꢂ19
HOMOꢂ18
HOMOꢂ17
HOMOꢂ16
HOMOꢂ15
HOMOꢂ14
HOMOꢂ13
HOMOꢂ12
HOMOꢂ11
HOMOꢂ10
HOMOꢂ9
HOMOꢂ8
HOMOꢂ7
HOMOꢂ6
HOMOꢂ5
HOMOꢂ4
HOMOꢂ3
HOMOꢂ2
HOMOꢂ1
HOMO
LUMO
LUMO +1
LUMO+2
LUMO+3
LUMO+4
LUMO+5
LUMO+6
LUMO+7
LUMO+8
ꢂ7.470
ꢂ7.172
ꢂ7.075
ꢂ7.000
ꢂ6.956
ꢂ6.900
ꢂ6.869
ꢂ6.830
ꢂ6.788
ꢂ6.777
ꢂ6.678
ꢂ6.647
ꢂ6.634
ꢂ6.560
ꢂ6.407
ꢂ6.252
ꢂ6.092
ꢂ5.682
ꢂ5.542
ꢂ5.153
ꢂ1.068
ꢂ0.629
ꢂ0.601
ꢂ0.546
ꢂ0.522
ꢂ0.364
ꢂ0.287
ꢂ0.282
ꢂ0.183
ꢂ0.121
0.041
dRu
dRu
;
;
pCl
pphosphine
ꢂ11.057
ꢂ10.277
ꢂ9.938
ꢂ9.701
ꢂ9.442
ꢂ9.346
ꢂ9.343
ꢂ9.231
ꢂ9.193
ꢂ9.151
ꢂ9.105
ꢂ9.099
ꢂ9.038
ꢂ8.945
ꢂ8.875
ꢂ8.830
ꢂ8.793
ꢂ8.777
ꢂ8.598
ꢂ8.207
ꢂ4.587
ꢂ4.464
ꢂ3.288
ꢂ3.227
ꢂ2.936
ꢂ2.857
ꢂ2.841
ꢂ2.803
ꢂ2.547
ꢂ2.528
ꢂ2.456
ꢂ2.440
ꢂ2.404
ꢂ2.262
ꢂ2.219
ꢂ2.150
p
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
pphosphine
pHMBI
;
pHMBI
;
;
pHMBI
pHMBI
pphosphine
pphosphine
pphosphine
;
pHMBI
;
pCl
pphosphine; dRu
pphosphine; dRu
pphosphine; dRu
pphosphine; dRu
;
;
pCO
pCO
nP; dRu; pCO
dRu
dRu
dRu
dRu
;
;
pCO
dRu
dRu
p*Cl
dRu
;
p*phosphine
p*phen
p*HMBI
pphen
p*phosphine
p*phosphine
p*phosphine
p*phosphine
p*phosphine
p*phosphine
p*phosphine
p*phen; dRu
p*phen
d; p*phosphine
p*phosphine
p*phosphine
p*phosphine
p*phosphine
p*phosphine
LUMO+9
dRu
;
p*phosphine
;
p*
CO
CO
LUMO+10
LUMO+11
LUMO+12
LUMO+13
LUMO+14
LUMO+15
p*phosphine p*
;
p*phosphine
p*phosphine
p*phosphine
p*phosphine
p*phosphine
;
p*phen
HMBI
0.057
0.183
0.189
0.189
dRu;
p*phosphine
;
p*
p*phosphine
p*phosphine
p*phosphine
;
p*CO
0.304
dRu;
p*phosphine
;
p*CO
dRu;
p*phosphine
;
p*CO
the hydrido ligand in the complex
2
is 1.923 and
tively charged (ꢂ0.505 (1), ꢂ0.482 (2)). The charge of hydride
ligand in complex 2 is calculated to be ꢂ0.064. The occupancies
of the ruthenium d orbitals, obtained from NBO analysis, are as fol-
0.734(sd)Ru + 0.679(s)H, respectively; occupancy of the antibonding
orbital of Ru–H is 0.328. The occupancies and hybridizations of the
Ru–CO bond are as follows: 1.970 (antibonding 0.325) and
lows: dxy – 1.92; dxz – 1.77; dyz – 1.72; dz2 – 0.96; dx2
– 0.99 and
ꢂy2
0.548(sd5.64
)
Ru + 0.836(sp0.54
)
C
for complex 1; 1.979 (antibonding
dxy – 1.79; dxz – 1.85; dyz – 1.10; dz2 – 1.67; dx2
respectively.
– 1.26 for 1 and 2,
ꢂy2
0.410) and 0.576(sd9.75
)
Ru + 0.817(sp0.54
)C for 2.
The stabilization energy1 calculated in these analyses has
shown that the lone pairs localized on the ruthenium atom in
complex 1 donate the charge to the ruthenium carbonyl bond,
3.1.3. Electronic spectra
The experimental and calculated (using TD–DFT theory) elec-
tronic spectra of [RuCl(CO)(PPh3)2(HOBIm)] (1) and [RuH(-
CO)(PPh3)2(1,10-phen)]Cl (2) are presented in Figs. 6 and 7. The
assignments of the calculated transitions to the experimental
bands are based on the criterion of energy and oscillator strength
of the calculated transitions. In the description of the electronic
transitions, only the main components of the molecular orbital
are taken into consideration.
In both the studied complexes, 120 electronic transitions were
calculated using the TDDFT method and they do not comprise all
the experimental absorption bands. The UV–Vis spectra were cal-
culated up to ꢃ220 nm, so considering that the solution spectra
of the PPh3 and N-heterocyclic ligands exhibit intense absorption
bands in the 260–200 nm region, some intraligand and interligand
transitions are expected to be found at higher energies in the
calculations.
and the stabilization energy (DEij) is 464.17 kcal/mol. The interac-
tion between the Ru–P bond and the ruthenium dz2 orbital has an
energy close to 135.46 kcal/mol. The stabilization energy calcu-
lated in this analysis for the complex has shown that the lone
pairs localized on the chlorine ligand donate the charge to the
ruthenium
d orbital, and the stabilization energy (DEij) is
112.25 kcal/mol. For complex 2, the donations of charge are
mainly visible between ruthenium–carbonyl and hydride ligand
bonds and Ru d orbitals; the stabilization energies are close to
505.91 and 297.20 kcal/mol, respectively.
In both studied complexes, ruthenium is formally +2, but the
calculated charges on the ruthenium atom are 0.284 in complex
1 and is close to zero with a negative sign (ꢂ0.067) in compound
2. The charges on the carbon atom of the carbonyl ligand are posi-
tive (0.569 (1), 0.568 (2)), whereas the oxygen atoms are nega-
The longest wavelength experimental bands, with a maximum
at 355.4 and 395.9 nm for complexes 1 and 2, respectively, are as-
signed to the transitions from HOMO, HOMOꢂ1 and HOMOꢂ2 to
LUMO and LUMO+1 orbitals. As the LUMO orbitals are composed
1
D
Eij (kcal/mol) associated with delocalization is estimated by the second-order
Eij = qi (F(i,j)2)/(ej
i) where qi is the donor orbital occupancy, ei, ej
perturbative as:
D
ꢂ
e
are diagonal elements (orbital energies) and F(i,j) is the off-diagonal NBO Fock or
Kohn–Sham matrix element.
of the p
* orbitals of phosphine (1) and phenanthroline (2), the tran-

3896
J.G. Małecki et al. / Polyhedron 28 (2009) 3891–3898
Fig. 5. PDOS diagrams for [RuCl(CO)(PPh3)2(HBIm)] (1) and [RuH(CO)(PPh3)2(1,10-phen)]Cl (2).
sition is of Metal–Ligand Charge Transfer type with a d ? d (Ligand
Field) contribution.
at 211.0 and 212.0 nm for complexes 1 and 2 are composed of the
transitions in PPh3 ligands and from
p* excitations in 2-
p
?
The next band, with maxima at 281.2 (5.22) and 274.3 nm for 1
and 330 (sh), 272.6 for 2 nm, is ascribed to metal–ligand charge
transfer transitions (d ! pꢄPPh =HMBI; d ? p*phen). In this region, the
transitions between HOMO, 3HOMOꢂ1, HOMOꢂ3 and HOMOꢂ4
to LUMO and LUMO+2/5/6 and LUMO+11 MOs were calculated.
The calculated transition attributed to experimental one at
243.6 nm for compound 1 proceeds mainly from d ruthenium orbi-
tals to p*Ph and p*CO orbitals with an admixture of Ligand–Ligand
(hydroxymethyl)benzimidazole and phenanthroline ligands. As it
was pointed out in the literature, the TDDFT method gives such
transitions at too small an energy [43–51] and we may expect also
that this is the case in our calculations.
The emission properties of the studied complexes have been
examined in acetonitrile solutions at room temperature. The lumi-
nescence spectra are presented in Fig. 8. For excitation at 355 nm,
the emission peak was observed at 450 nm for complex 1. Excita-
tion of complex 2 at 395 nm gave an emission with a maximum
at 465 nm. Additionally, excitation of compound 2 at 330 nm
(the absorption band has MLCT character) gave an emission at
Charge Transfer transitions (pPPh
!
pꢄCO).
3
The intraligand transitions pPPh
!
pꢄPPh were calculated to be
3
at about 220 nm and one may assume that 3the experimental bands

J.G. Małecki et al. / Polyhedron 28 (2009) 3891–3898
3897
80000
60000
40000
20000
200
300
400
500
[nm]
Fig. 6. UV–Vis spectra of [RuCl(CO)(PPh3)2(HBIm)] with calculated singlet excited
states in acetonitrile solution.
400
500
600
[nm]
Fig. 8. Emission spectra of [RuCl(CO)(PPh3)2(HBIm)] (solid line) and
[RuH(CO)(PPh3)2(1,10-phen)]Cl (dashed line).
Acknowledgements
The crystallographic part was financed by funds allocated by
the Ministry of Scientific Research and Information Technology to
the Institute of General and Ecological Chemistry, Technical Uni-
´
versity of Łódz. The GAUSSIAN03 calculations were carried out in
Wrocław Centre for Networking and Supercomputing, WCSS, Wro-
cław, Poland under calculational Grant No. 51/96.
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Supplementary data
CCDC 683037 and 683130 contains the supplementary crystal-
lographic data for [RuCl(CO)(PPh3)2(HOBIm)] and RuH(-
CO)(PPh3)2(1,10-phen)]ClꢀH2Oꢀ(CH3)2O. These data can be
obtained free of charge via http://www.ccdc.cam.ac.uk/conts/
retrieving.html, or from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-
033; or e-mail: deposit@ccdc.cam.ac.uk.

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