A ruthenium(II) hydride carbonyl complex with 4-phenylpyrimidine as co-ligand

Article abstract of DOI:10.1007/s11243-012-9644-x

The reaction of [RuHCl(CO)(PPh₃)₃] with 4-phenylpyrimidine gave a new ruthenium(II) complex, namely [RuHCl(CO)(PPh ₃)₂(pyrim-4-Ph)]. The complex has been studied by IR and UV-vis spectroscopy and by X-ray crystallography. The molecular orbitals of the complex have been calculated by density functional theory. The spin-allowed singlet-singlet electronic transitions of the complex have been calculated by time-dependent DFT, and the UV-vis spectrum of the compound has been discussed on this basis. The emission properties of the complex were also studied. The Author(s) 2012.

Full text of DOI:10.1007/s11243-012-9644-x

Transition Met Chem
DOI 10.1007/s11243-012-9644-x
A ruthenium(II) hydride carbonyl complex
with 4-phenylpyrimidine as co-ligand
•
J. G. Małecki A. Maron
´
Received: 12 July 2012 / Accepted: 23 August 2012
Ó The Author(s) 2012. This article is published with open access at Springerlink.com
Abstract The reaction of [RuHCl(CO)(PPh3)3] with
4-phenylpyrimidine gave a new ruthenium(II) complex,
namely [RuHCl(CO)(PPh3)2(pyrim-4-Ph)]. The complex
has been studied by IR and UV–vis spectroscopy and by
X-ray crystallography. The molecular orbitals of the
complex have been calculated by density functional theory.
The spin-allowed singlet–singlet electronic transitions of
the complex have been calculated by time-dependent DFT,
and the UV–vis spectrum of the compound has been
discussed on this basis. The emission properties of the
complex were also studied.
filled metal d orbitals. In consequence, they can ex hibit
charge transfer bands with interesting spectroscopic prop-
erties in the visible region [7]. Ligands containing pyrim-
idine rings are widely studied and their p-donor properties
are interesting. Their combination with other donor atoms
should in principle afford complexes with tunable spec-
troscopic properties [8–10]. The hydride ligand as a pow-
erful r-donor is very efficient at compensating the electron
deficiency at the metal center in hydride complexes. The
‘‘trans effect’’ of hydride and the interactions between
carbonyl and donor ligands in mutually trans positions are
factors, which explain the stability of these complexes [11].
Here, we report an experimental and quantum chemical
study of a ruthenium hydridocarbonyl complex with a
pyrimidine derivative as co-ligand. The quantum chemical
study included a characterization of the molecular and
electronic structures of the complex by analysis of the
optimized molecular geometry and the electronic popula-
tion by using the natural bond orbitals scheme. The latter
was used to identify the nature of the interactions between
the ligands and the central metal. Finally, time-dependent
density functional theory (TD-DFT) was used to calculate
the electronic absorption spectrum. These results allowed
for the interpretation of the experimental UV–vis spectrum.
The complex reported in this paper combines our interests
in ruthenium hydride carbonyl coordination compounds
and complexes containing nitrogen heterocyclic ligands
[12–20].
Introduction
Ruthenium hydride complexes of carbonyl and triarylphosphine
ligands are interesting due to their reactivity and efficiency as
catalysts in a wide variety of reactions [1–6]. The synthesis and
characterization of ruthenium complexes containing nitrogen
heteroaromatic ligands have also received considerable recent
attention, owing to their interesting photophysical and photo-
chemical properties. Pyrimidine and its derivatives as well as
other 1,4-diazines, including compounds with partial pyrazine
structures (e.g., quinoxaline, phenazine, pteridine, flavin and
their derivatives), demonstrate distinctive physico-chemical
properties that are caused by a low lying unoccupied p-molec-
ular orbital and by their ability to act as bridging ligands.
Azine ligands generally have energetically low lying
p-antibonding orbitals, which can accept electrons from
Experimental
´
J. G. Małecki (&) ꢀ A. Maron
Department of Inorganic and Coordination Chemistry,
Institute of Chemistry, University of Silesia, 9th Szkolna St.,
40-006 Katowice, Poland
All reagents used to the synthesis of the complex are
commercially available and were used without further
purification.
e-mail: gmalecki@us.edu.pl
123

Transition Met Chem
Synthesis of [RuHCl(CO)(PPh3)2(pyrim-4-Ph)]
of the complex using the solvent PCM (Polarizable Con-
tinuum Model) model. In this work, 100 singlet excited
states were calculated as vertical transitions for the com-
plex. A natural bond orbital (NBO) analysis was also made
for the complex using the NBO 5.0 package [26] included
in Gaussian09. Natural bond orbitals are orbitals localized
on one or two atomic centers that describe molecular
bonding in a manner similar to a Lewis electron pair
structure, and they correspond to an orthonormal set of
localized orbitals of maximum occupancy. NBO analysis
provides the contribution of atomic orbitals (s, p, d) to the
NBO r and p hybrid orbitals for bonded atom pairs. In this
scheme, three NBO hybrid orbitals are defined, namely
bonding orbital (BD), lone pair (LP) and core (CR), which
were analyzed on the atoms directly bonded to or pre-
senting some kind of interaction with the ruthenium atom.
The contribution of a group (ligands, metal atom) to a
A suspension of [RuHCl(CO)(PPh3)3] (0.2 g, 0.2 mmol)
and 4-phenylpyrimidine (0.03 g, 0.2 mmol) in methanol
was refluxed until the solid dissolved and then for an
additional 2 h, then cooled and filtered. Yellow crystals
suitable for X-ray crystal analysis were obtained by slow
evaporation the reaction mixture. Yield (0.17 g) 86 %.
Anal. calc. for C47H39ClN2OP2Ru: C 66.70 %, H 4.64 %,
Cl 4.19 %, N 3.31 %, O 1.89 %, P 7.32 %, Ru 11.94 %.
Found: C 66.62 %, H 4.67 %, N 3.28 %.
IR (KBr) (cm-1): 3,047 (m) mCH–pyrimidine; 2,039
(w) mRu–H; 1,943 (s) mCO; 1,602 (m) mCN; 1,566 (m) mC=C
;
1,474 (m) d(C–CH in the plane); 1,434 (m) mPh(P–Ph); 1,092
(m) d(C–CH in the plane); 997 (w) d(C–C out of the plane); 742
(m) d(C–C out of the plane); 697 (s) d(C–C in the plane); 520
(m) mRu–P/Ru–N 1H NMR (400 MHz, CDCl3) d 9.34 (s, H(2)
pyrimidine), 8.81 (d, J = 6.3 Hz, H(5) pyrimidine),
8.05–7.05 (m, PPh3; pyrimidine; phenyl), -4.44 (t, J =
19.2 Hz, Ru–H(1)). 31P NMR (162 MHz, CDCl3) d 31.22
(s, PPh3).
Table 1 Crystal data and structure refinement details of [RuHCl
(CO)(pyrim-4-Ph)(PPh3)2]
Empirical formula
Formula weight
Temperature (K)
Crystal system
C47H39ClN2OP2Ru
846.26
UV–vis (methanol) (nm) (loge): 370 (1.01), 328 (1.93),
268 (2.68), 232 (3.06), 212 (4.27).
295.0(2) K
Triclinic
Physical measurements
Space group
P-1
Unit cell dimensions
Infrared spectra were recorded on a Perkin-Elmer spec-
trophotometer in the spectral range 4,000–400 cm-1 using
˚
a (A)
12.4438(8)
12.5485(9)
15.3801(10)
100.835(6)
109.725(5)
106.384(6)
2,059.5(2)
1
KBr pellets. H and 31P NMR spectra were obtained at
˚
b (A)
˚
c (A)
room temperature in CDCl3 using a Bruker 400 spec-
trometer. Electronic spectra were measured on a spectro-
photometer Lab Alliance UV–VIS 8500 in the range
800–200 nm in methanol solution. Luminescence mea-
surements were made in methanolic solution on an F-2500
FL spectrophotometer at room temperature. Elemental
analyses (C, H, N) were obtained on a Perkin-Elmer CHN-
2400 analyser.
a (°)
b (°)
c (°)
3
˚
Volume (A )
Z
2
Calculated density (mg/m3)
Absorption coefficient (mm-1
F(000)
1.365
)
0.561
868
Computational methods
Crystal dimensions (mm)
h range for data collection (°)
Index ranges
0.13 9 0.09 9 0.03
3.35–25.05
-14 \=h \=14
-14 \=k \=14
-18 \=l \=18
26,406
The calculations were carried out using the Gaussian09
[21] program. The molecular geometry of the singlet
ground state of the complex was fully optimized in the gas
phase using the B3LYP functional [22, 23]. For the com-
plex, a frequency calculation was carried out, verifying that
the optimized molecular structure corresponds to energy
minimum; thus, only positive frequencies were expected.
The DZVP basis set [24] with f functions with exponents
1.94722036 and 0.748930908 was used to describe the
ruthenium atom, and the basis set used for the lighter
atoms (C, N, O, Cl, P, H) was 6-31G with a set of ‘‘d’’ and
‘‘p’’ polarization functions. The TD-DFT method [25] was
employed to calculate the electronic absorption spectrum
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I [ 2r(I)]
7,268 (R(int) = 0.0447)
7,268/0/491
1.058
R1 = 0.0484
wR2 = 0.1234
R1 = 0.0657
wR2 = 0.1331
R indices (all data)
.
-3
˚
0.586 and -0.327 e A
Largest diff. Peak and hole
123

Transition Met Chem
molecular orbital was calculated using Mulliken population
analysis. GaussSum 2.2 [27] was used to calculate group
contributions to the molecular orbitals and to prepare the
partial density of states (DOS) spectra. The DOS spectra
were created by convoluting the molecular orbital infor-
mation with Gaussian curves of unit height and full width
at half maximum of 0.3 eV.
techniques. Bearing in mind the limitations of Fourier syn-
thesis and the problems in recognizing artifacts in the
immediate neighborhood of heavy atoms, it is doubtful if a
reliable position for the hydrogen atom bound to the Ru
atom can be found in the difference Fourier map, avoiding
the danger of mistaking the effects of the series termination
errors for a true atomic position. In this complex, the Ru–H
˚
bond length of 1.86(4) A is normal. The Olex2 [29] and
Crystal structure determination and refinement
SHELXS97, SHELXL97 [30] programs were used for all
the calculations. Atomic scattering factors were used as
incorporated in the programs.
A pale yellow plate shaped crystal of the complex was
mounted in turn on an Xcalibur, Atlas, Gemini Ultra Oxford
Diffraction automatic diffractometer equipped with a CCD
detector and used for data collection. X-ray intensity data
were collected with graphite monochromated MoKa radia-
Results and discussion
˚
tion (k = 0.71073 A) at temperature 295.0(2) K, with x
Spectroscopic characterization
scan 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 10,270
strongest reflections. Details concerning crystal data and
refinement are gathered in Table 1. Lorentz, polarization
and empirical absorption correction using spherical har-
monics implemented in the SCALE3 ABSPACK scaling
algorithm [28] were applied. The structure was solved
by Patterson methods and subsequently completed by
difference Fourier recycling. All the non-hydrogen atoms
were refined anisotropically using full-matrix, least-squares
The reaction of [RuHCl(CO)(PPh3)3] with 4-phenylpyr-
imidine gave the complex [RuHCl(CO)(PPh3)2(pyrim-4-
1
Ph)] as a pale yellow crystalline solid. In the H NMR
spectrum, signals at 9.34 and 8.81 ppm are assigned to the
pyrimidine protons. In the range of 8.05–7.05 ppm, the
PPh3 phenyl and 4-pyrimidinepheny protons are observed
but the various signals in this region are difficult to resolve.
A signal at high field (-4.44 ppm) indicates the presence
of the hydride ligand. The Ru–H signal is a triplet,
due to coupling with the two trans phosphorus atoms
Fig. 1 The ORTEP plot of the
[RuHCl(CO)(pyrim-4-
Ph)(PPh3)2] complex. The
displacement ellipsoids are
drawn with 30 % probability.
The hydrogen atoms, except
Ru(1)–H(1) are omitted for
clarity
123

Transition Met Chem
˚
Ru–H bond order. Stretching vibrations for the C=C and
C=N bonds of the 4-pyrrolidinephenyl ligand are observed
in the 1,566–1,602 cm-1 range.
Table 2 Selected bond lengths (A) and angles (°) for [RuHCl
(CO)(pyrim-4-Ph)(PPh3)2]
˚
Bond lengths (A)
Experimental
Calculated
1.86
Crystal structure
Ru(1)–C(1)
1.838(5)
Ru(1)–N(1)
2.213(3)
2.26
This complex crystallizes in the triclinic P-1 group. The
molecular structure of the complex is displayed as an ORTEP
representation in Fig. 1, and selected bond distances and
angles are collected in Table 2. The Ru(1)–N(1) bond length
in the complex is normal and comparable with other ruthe-
nium hydride complexes with pyrimidine derivative ligands
[16]. The structure of the complex can be considered as
distorted octahedral, with the largest deviation from the
expected 90° bond angles for P(1)–Ru(1)–H(1) at 85.1(12)°
and N(1)–Ru(1)–H(1) at 83.8(12)°. The angles between the
carbonyl and pyrimidine C(1)–Ru(1)–N(1) ligands and
chloride and hydide Cl(1)–Ru(1)–H(1) differ by about 9°
from a right angle. The P–Ru–P angle is slightly lower than
180° with a value of 177.67(3)°.
Ru(1)–P(1)
2.3520(10)
2.3522(10)
2.4992(11)
1.86(4)
2.43
Ru(1)–P(2)
2.43
Ru(1)–Cl(1)
2.59
Ru(1)–H(1)
1.61
C(41)–O(1)
1.151(5)
1.16
Angles (°)
C(1)–Ru(1)–N(1)
C(1)–Ru(1)–P(1)
N(1)–Ru(1)–P(1)
C(1)–Ru(1)–P(2)
N(1)–Ru(1)–P(2)
P(1)–Ru(1–P(2)
C(1)–Ru(1)–Cl(1)
N(1)–Ru(1)–Cl(1)
P(1)–Ru(1)–Cl(1)
P(2)–Ru(1)–Cl(1)
C(1)–Ru(1)–H(1)
P(1)–Ru(1)–H(1)
P(2)–Ru(1)–H(1)
N(1)–Ru(1)–H(1)
Cl(1)–Ru(1)–H(1)
171.41(15)
90.14(13)
92.09(8)
87.81(13)
89.78(8)
177.67(3)
100.72(14)
87.54(9)
90.89(4)
90.58(4)
88.1(12)
85.1(12)
93.7(12)
83.8(12)
170.3(12)
169.6
89.3
90.3
88.5
90.3
177.7
102.1
88.3
89.6
91.7
85.1
88.1
90.7
84.8
172.7
As shown in Fig. 1, the CO group is trans to the 4-phe-
nylpyrimidine ligand and the chloride and hydride ligands are
mutually trans. In the parent complex with formula [Ru-
HCl(CO)(PPh3)3], the chloride ligand is trans to the carbonyl,
and the hydride and one PPh3 ligand are also mutually trans
[31]. In spite of the changes in the coordination sphere in the
studied complex, the Ru–Cl and Ru–CO bond lengths are
almost unchanged compared with the parent complex.
Moreover, the C:O bond lengths are also similar in both
˚
complexes (1.151(5) A in [RuHCl(CO)(PPh3)2(pyrim-4-Ph)]
˚
and 1.141 A in [RuHCl(CO)(PPh3)3]). Based on the data and
(JHP * 19 Hz). The 31P NMR spectrum of the complex
shows a singlet at 31.22 ppm, which suggests that the two
triphenylphosphine groups are in equivalent trans posi-
tions. The molecular structure of the complex as deter-
mined by X-ray crystallography shows that the angle
between triphenylphosphine ligands is not linear but this
may be due to the crystal packing interactions.
taking into account the IR shifts discussed above, the
4-phenylpyrimidine can be considered as a rather strong
r-donor.
In the molecular structure of the complex, several inter-
and intra- molecular hydrogen bonds [32] are observed and
are collected in Table 3. Additionally, some electronic
interactions (p–p stacking) between the PPh3 phenyl and
pyrimidine rings are visible, as shown in Fig. 2. The plane-
to-plane distances between the phosphine phenyl centroids,
determined by C(12) to C(17) and C(30) to C(35) carbons,
The IR spectrum displays Ru–H and C:O stretching
bands at 2,039 and 1,943 cm-1, respectively. The mRu–H and
mCO stretching bands in the parent [RuHCl(CO)(PPh3)3]
complex are at 2,020 and 1,922 cm-1, respectively, hence a
decrease in the carbonyl stretch is clearly seen for the
studied complex. The inclusion of electron-acceptor ligands
such as chloride or 4-pyrimidinephenyl in the coordination
sphere should decrease the electron density on the metal,
therefore increasing the bond order of the CO bond and
increasing the vibration frequency. However, the electron-
donor hydride ligand delivers electron density via backb-
onding to the antibonding orbitals of the CO, which will
decrease the vibration frequency of the CO bond. Overall,
the changing of the positions of mRu–H and mRu–CO indicates a
decrease in the metal—carbonyl carbon interaction and the
Table 3 Hydrogen bonds for [RuHCl(CO)(pyrim-4-Ph)(PPh3)2]
˚
complex (A and °)
D–HꢀꢀꢀA
d(D–H) d(HꢀꢀꢀA) d(DꢀꢀꢀA) \(DHA)
C(4)–H(4)ꢀꢀꢀCl(1) #1
C(5)–H(5)ꢀꢀꢀCl(1)
C(11)–H(11)ꢀꢀꢀN(2)
0.93
0.93
0.93
2.80
2.53
2.44
2.62
3.430(5) 126.3
3.196(5) 129.0
2.783(7) 102.0
3.443(6) 148.4
C(45)–H(45)ꢀꢀꢀN(2) #2 0.93
Symmetry transformations used to generate equivalent atoms: #1 -x,
1 - y, -z; #2 1 - x, 2 - y, 1 - z
123

Transition Met Chem
˚
and the pyrimidine ring are 3.708 and 3.660 A, respec-
that the pir-4-P ligand does not show covalent bonding
with ruthenium; the Coulomb-type interaction between the
ruthenium center and the 4-phenylpyrimidine ligand is
clearly visible in the calculated Wiberg bond index, which
is considerably lower than one and close to 0.38. The Ru–P
bond orders are also smaller than 1 (0.7).
tively, indicating weak p–p stacking interactions.
Quantum calculations
The ground state geometry of the complex was optimized
in the singlet state, using the B3LYP functional. The cal-
culation was carried out for the gas phase molecule, and in
general, the predicted bond lengths and angles are over-
For the carbonyl ligand, three natural bond orbitals were
detected for the C–O bond, and one for the Ru–C bond. The
Ru–C bond orbitals are polarized toward the carbon atom,
while the C–O bond orbitals are polarized toward the oxy-
gen. The carbonyl oxygen has one lone pair (LP) orbital.
The Wiberg index of the CO bond in the complex is reduced
(by 0.21) with respect to free CO (WCO = 2.23). The charge
on the carbonyl group calculated simply by summing the
individual charges on the carbon and oxygen atoms is
?0.205. The charges on the hydride and chloride ligands are
?0.05 and -0.53, respectively. The Wiberg indices of the
Ru–H, Ru–C(O) and Ru–Cl bonds are equal to 0.79, 1.32
and 0.57, respectively. The nitrogen atoms in the pyrimidine
ring have similar natural charges, equal to -0.44 for N(1)
and -0.49 for N(2). The natural charge on the ruthenium is
-0.92, which confirms the strong donor property of
4-phenylpyrimidine and also provides supporting evidence
o
˚
estimated by about 0.1 A and 3 , respectively. Neverthe-
less, the general trends observed in the experimental data
are reproduced in the calculations, as can be seen from the
Table 2. The calculated IR frequencies of the complex
show good agreement with the experimental spectrum; the
differences can be explained by the neglect of intermo-
lecular interactions for the gas phase. From the data col-
lected in Table 2, one may see that the major differences
between the experimental and calculated geometries are
found in the Ru(1)–H(1) and Ru(1)–Cl(1) distances (0.25
˚
and 0.1 A, respectively). Based on the optimized geometry
of the complex, a NBO analysis was performed in order to
reveal the nature of the coordination between ruthenium
and the donor atoms of the ligands. This analysis showed
Fig. 2 p-stacking interactions
in the molecule of
[RuHCl(CO)(pyrim-4-Ph)
(PPh3)2] complex
123

Transition Met Chem
Analysis of the frontier molecular orbitals is useful for
understanding the spectroscopic properties such as elec-
tronic absorption and emission spectra. The density of
states (DOS) in terms of Mulliken population analysis was
calculated using the GaussSum program [27], and Fig. 3
presents the composition of the fragment orbitals contrib-
uting to the molecular orbitals of the complex. The HOMO
is localized on the ruthenium atom (49 %) with a signifi-
cant contribution from the chloride ligand (43 % Cl), while
the LUMO is composed of p* orbitals of 4-phenylpyrim-
idine (97 %). The ruthenium d orbitals contribute to the
HOMO-1 and HOMO-2 (42 and 44 %) while in the
HOMO-1 the carbonyl (10 %) and chloride (45 %) ligands
are also engaged, and the HOMO-2 has a contribution from
the PPh3 ligands (43 %). The d2z (*16 %) ruthenium
Fig. 3 DOS diagram for [RuHCl(CO)(pyrim-4-Ph)(PPh3)2] complex
orbital is a component of the LUMO?2, along with the p*
22
x-y
triphenylphosphine orbitals, and the d
role in the higher virtual orbital LUMO ? 15 along with
the p* carbonyl and PPh3 orbitals.
orbital plays a
for ligand to dRu electron transfer. The data suggest that
donation from the ligands to the dRu orbitals plays a role in
the electronic structure of the complex, and in order to
determine the extent of donation, the stabilization energies
were calculated. DEij (kcal/mol) associated with delocal-
ization is estimated by second-order perturbation as:
DEij = qi (F(i, j)2)/(ej - ei) where qi is the donor orbital
occupancy, ei, ej are diagonal elements (orbital energies),
and F(i, j) is the off-diagonal NBO Fock or Kohn–Sham
matrix element.
Experimental and theoretical electronic spectra
The UV–vis spectrum of the complex shows maxima at
370, 328, 268, 232 and 212 nm. The electronic spectrum
was calculated with the TD-DFT method with methanol as
solvent in the polarizable continuum model (PCM). Com-
putation of 100 excited states of the complex allowed the
interpretation of the experimental spectrum down to
*230 nm. The assignment of the calculated orbital exci-
tations to the experimental bands was based on an over-
view of the composition and relative energies of the
HOMO and LUMO. As one can see from the data collected
in Table 4, the Charge Transfer transitions have Metal-to-
Ligand Charge Transfer character. These transitions mainly
involve the HOMO and LUMO, LUMO?1/?2. The bands
The stabilization energies show that the pyrimidine
ligand in this complex donates charge to ruthenium, with a
stabilization energy (DEij) of 53.5 kcal/mol. The back
donation to 4-phenylpyrimidine provides 24.5 kcal/mol,
and the data highlight the higher r-donor than p-acceptor
properties of the ligand. For comparison, the stabilization
energy for donation from chloride to ruthenium is 44.6 kcal/
mol, and the back donation Ru ? Cl only 6.0 kcal/mol.
Table 4 The calculated electronic transitions for [RuHCl(CO)(pyrim-4-Ph)(PPh3)2] complex
(nm)
f
Transitions
Charakter
393.4
366.6
356.6
338.2
319.0
312.6
301.4
300.8
297.1
270.0
263.7
232.6
0.0002
0.0051
0.0168
0.1819
0.0031
0.0014
0.0036
0.0895
0.1629
0.1017
0.0138
0.0477
HOMO ? LUMO (99 %)
dRu=pCl ! pꢁpyr-4-Ph
dRu=pCl=CO ! pꢁpyr-4-Ph
dRu=pCl ! d/pꢁPPh3
H-1 ? LUMO (99 %)
HOMO ? L ? 2 (65 %)
H-2 ? LUMO (98 %)
dRu=pPPh3 ! pꢁpyr-4Ph
dRu=pCl ! pꢁpyr-4-Ph
dRu=pCl ! d/pꢁPPh3
HOMO ? L ? 1 (90 %)
HOMO ? L ? 2 (13 %), HOMO ? L ? 3 (20 %), HOMO ? L ? 5 (26 %)
H-1 ? L ? 1 (91 %)
dRu=pCl=CO ! pꢁpyr-4-Ph
dRu=pCl=PPh3 ! pꢁpyr-4-Ph
dRu=pCl=PPh3 ! d/pPꢁPh3
pCl=CO=PPh3 ! ppꢁyr-4-Ph
pPPh3 ! pꢁpyr-4-Ph
H-3 ? LUMO (89 %)
H-2 ? L ? 2 (56 %); H-3 ? L ? 2 (13 %)
H-11 ? LUMO (26 %), H-9 ? LUMO (31 %)
H-14 ? LUMO (65 %), H-12 ? LUMO (16 %)
H-14-[L?1 (17 %), H-12-[L?1 (40 %)
pPPh3 ! pꢁpyr-4-Ph
123

Transition Met Chem
Open Access This article is distributed under the terms of the
Creative Commons Attribution License which permits any use, dis-
tribution, and reproduction in any medium, provided the original
author(s) and the source are credited.
Appendix: supplementary data
CCDC 891199 contains the supplementary crystallographic
data for [RuHCl(CO)(pyrim-4-Ph)(PPh3)2] complex. This
data can be obtained free of charge from 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.
Fig. 4 Fluorescence spectrum of [RuHCl(CO)(pyrim-4-Ph)(PPh3)2]
complex solution in methanol
References
with maxima at 268 and 232 nm have Ligand-to-Ligand
Charge Transfer character. The highest experimental band
close to 212 nm may result from transitions based on the
PPh3 ligands and from p ? p* excitations in the pyrimi-
dine ligand.
1. Salvi L, Salvini A, Micoli F, Bianchini C, Oberhauser W (2007) J
Organomet Chem 692:1442
2. Po Lau C, Man Ng S, Jia G, Lin Z (2007) Coord Chem Rev
251:2223
3. Jun Yue C, Liu Y, He R (2006) J Mol Catal A: Chem 259:17
4. Nipa Haque F, Lough AJ, Morris RH (2008) Inorg Chim Acta
361:3149
5. Buskens P, Giunta D, Leitner W (2004) Inorg Chim Acta
357:1969
6. Bravo J, Castro J, Garcia-Fontana S, Rodriguez-Martinez MC,
Albertin G, Antoniutti S, Manera A (2007) J Organomet Chem
692:5481
7. Chandra M, Sahay AN, Pandey DS, Puerta MC, Valerga P (2002)
J Organomet Chem 648:39
The emission characteristics of the complex were
examined in methanol solution (concentration of 1 9 10-3
mol/dm3) at room temperature. Excitation at 303 nm gave
fluorescence with a maximum at 425 nm, as shown Fig. 4.
The red shift of the emission maximum is typical of
ruthenium(II) complexes, and the emission originates from
excitation involving a dp ! pꢁligand MLCT transition. This
´
8. Małecki JG, Maron A (2011) Trans Met Chem 36:297
assignment is supported by the analysis of the frontier
orbitals of the complex. Moreover, the transition between
the HOMO-1 and LUMO?1 was calculated to lie in this
region. The LUMO?1 is localized on the 4-phenylpyrim-
idine ligand, while the HOMO-1 has a significant contri-
bution from the carbonyl ligand, whose presence is
associated with the fluorescence of the complex.
9. Małecki JG (2010) Trans Met Chem 35:801
10. Michalik S, Machura B, Kruszynski R, Kusz J, Krompiec M
(2010) Polyhedron 29:2629
11. Coe BJ, Glenwright SJ (2000) Coord Chem Rev 203:5
´
12. Małecki JG, Maron A (2011) Polyhedron 30:1225
13. Małecki JG (2011) Polyhedron 30:79
14. Małecki JG (2010) Polyhedron 29:2489
´
15. Małecki JG, Kruszynski R, Mazurak Z (2009) Polyhedron
28:3891
16. Małecki JG, Kruszynski R, Mazurak Z (2008) J Coord Chem
´
61:2186
17. Małecki JG, Kruszynski R, Tabak D, Kusz J (2007) Polyhedron
Conclusion
´
26:5120
18. Małecki JG, Kruszynski R, Mazurak Z (2007) Polyhedron
26:4201
A new ruthenium(II) hydride carbonyl complex with
4-phenylpyrimidine as co-ligand has been synthesized and
characterized. In the crystal structure of the complex, some
non-covalent interactions between the aromatic rings have
been found. The electronic structure of the complex,
characterized in particular by the density of states diagram,
has been correlated with its fluorescence properties.
´
19. Małecki JG, Kruszynski R (2007) Polyhedron 26:2686
´
20. Małecki JG, Kruszynski R (2007) J Coord Chem 60:2085
21. Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb,MA
Cheeseman JR, Scalmani G, Barone V, Mennucci B, Petersson
GA, Nakatsuji H, Caricato M, Li X, Hratchian HP, Izmaylov AF,
Bloino J, Zheng G, Sonnenberg JL, Hada M, Ehara M, Toyota K,
Fukuda R, Hasegawa J, Ishida M, Nakajima T, Honda Y, Kitao
O, Nakai H, Vreven T, Montgomery JA Jr, Peralta JE, Ogliaro F,
Bearpark M, Heyd JJ, Brothers E, Kudin KN, Staroverov VN,
Kobayashi R, Normand J, Raghavachari K, Rendell A, Burant JC,
Iyengar SS, Tomasi J, Cossi M, Rega N, Millam JM, Klene M,
Acknowledgments Calculations have been carried out in Wroclaw
Centre for Networking and Supercomputing (http://www.wcss.
wroc.pl).
123

Transition Met Chem
Knox JE, Cross JB, Bakken V, Adamo C, Jaramillo J, Gomperts
R, Stratmann RE, Yazyev O, Austin AJ, Cammi R, Pomelli C,
Ochterski JW, Martin RL, Morokuma K, Zakrzewski VG, Voth
GA, Salvador P, Dannenberg JJ, Dapprich S, Daniels AD, Farkas
O, Foresman JB, Ortiz JV, Cioslowski J, Fox DJ (2009) Gaussian
09, revision A.1. Gaussian Inc., Wallingford
26. Glendening ED, Reed AE, Carpenter JE, Weinhold F, NBO
(version 3.1)
27. O’Boyle NM, Tenderholt AL, Langner KM (2008) J Comp Chem
29:839
28. CrysAlis RED, Oxford Diffraction Ltd., Version 1.171.29.2
29. Dolomanov OV, Bourhis LJ, Gildea RJ, Howard JAK, Pusch-
mann H (2009) J Appl Cryst 42:339
22. Becke D (1993) J Chem Phys 98:5648
23. Lee C, Yang W, Parr RG (1988) Phys Rev B 37:785
24. Eichkorn K, Weigend F, Treutler O, Ahlrichs R (1997) Theor
Chim Acc 97:119
30. Sheldrick GM (2008) Acta Cryst A64:112
31. Seetharaman SK, Chung M-C, Englich U, Ruhlandt-Senge K,
Sponsler MB (2007) Inorg Chem 46:561
25. Casida ME (1996) In: Seminario JM (ed) Recent developments
and applications of modern density functional theory, theoretical
and computational chemistry, vol 4. Elsevier, Amsterdam, p 391
32. Desiraju GR, Steiner T (1999) The weak hydrogen bond in
structural chemistry and biology. Oxford University Press, Oxford
123