Synthesis, characterizations and catalytic applications of hydridecarbonyl ruthenium(II) complexes with imidazole carboxylic acid derivative ligands

Article abstract of DOI:10.1016/j.poly.2012.09.051

The hydridecarbonyl ruthenium(II) [RuH(CO)(MeImCOO)(PPh₃) ₂]·CH₃OH 1 and [RuH(CO)(BImCOO)(PPh ₃)₂] 2 complexes were synthesized and characterized by IR, ¹H, ³¹P NMR, UV-Vis spectroscopy and X-ray crystallography. The experimental studies were completed by quantum chemical calculations which were used to identify the nature of the interactions between the ligands and the central ion and the orbital compositions in the frontier electronic structures. Based on a molecular orbital scheme, the calculated results allowed the interpretation of the UV-Vis spectra obtained at an experimental level. The luminescence properties of the complexes were determined. The catalytic activity for both of the complexes was tested in the reaction of the double bond migration in O-allyl systems. Complex 1 was significantly more active than complex 2, because of the longer Ru-H bond distance in complex 1 in comparison with complex 2.

Full text of DOI:10.1016/j.poly.2012.09.051

Polyhedron 49 (2013) 190–199
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis, characterizations and catalytic applications of hydridecarbonyl
ruthenium(II) complexes with imidazole carboxylic acid derivative ligands
a
b,
b
b
b
J.G. Małecki a, , A. Maron , S. Krompiec , M. Filapek , M. Penkala , B. Marcol
⇑
⇑
´
a Department of Crystallography, Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice, Poland
b Department of Inorganic, Organometallic Chemistry and Catalysis, Institute of Chemistry, University of Silesia, ul. Szkolna 9, 40-006 Katowice, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
The hydridecarbonyl ruthenium(II) [RuH(CO)(MeImCOO)(PPh3)2]ÁCH3OH 1 and [RuH(CO)(BImCOO)(PPh3)2]
2 complexes were synthesized and characterized by IR, 1H, 31P NMR, UV–Vis spectroscopy and X-ray crys-
tallography. The experimental studies were completed by quantum chemical calculations which were used
to identify the nature of the interactions between the ligands and the central ion and the orbital composi-
tions in the frontier electronic structures. Based on a molecular orbital scheme, the calculated results
allowed the interpretation of the UV–Vis spectra obtained at an experimental level. The luminescence prop-
erties of the complexes were determined. The catalytic activity for both of the complexes was tested in the
reaction of the double bond migration in O-allyl systems. Complex 1 was significantly more active than
complex 2, because of the longer Ru–H bond distance in complex 1 in comparison with complex 2.
Ó 2012 Elsevier Ltd. All rights reserved.
Received 25 April 2012
Accepted 26 September 2012
Available online 17 October 2012
Keywords:
Ruthenium hydridocarbonyl complexes
Imidazole derivatives carboxylic acids
Absorptions and emissions electronic
spectra
DFT
Electrochemistry
Catalysts for double bond migration
1. Introduction
The hydride ligand – a powerful r-donor – is found to be very
efficient at compensating the electron deficiency at the metal
central ion in complexes. The ‘‘trans effect’’ of HÀ ligand and the
interaction between carbonyl and donor ligands (such as carboxyl
or chloride) in trans positions to one another, which are stabilizing
factors explaining stability of these complexes [12], are also inter-
esting due to their properties.
The ruthenium hydride complexes containing carbonyl and
triarylphosphine ligands are interesting due to their reactivity
and efficiency as catalysts in a wide spectrum of reactions [1–6].
On the other hand, complexes of ruthenium containing p-acceptor
nitrogen-bearing ligands, especially N-heteroaromatic, have been
widely studied as systems for the conversion of energy. The studies
on synthesis and characterization of ruthenium complexes con-
taining N-heteroaromatic ligands have received considerable
attention recently, owing to their interesting photophysical and
photochemical properties. The azine ligands have energetically
Here is reported an experimental and quantum chemical study of
ruthenium hydridocarbonyl complexes with imidazole derivatives
carboxylic acid ligands. In the experimental part of the report except
the synthesis and spectroscopic (1H, 31P NMR, IR) characterization
the X-ray crystal structures, electrochemistry and photophysical
properties of the ruthenium(II) hydride-carbonyl complexes with
imidazole derivative carboxylic acids ligands complexes are pre-
sented. The quantum chemical study included a characterization
of the molecular and electronic structures of the complexes by anal-
ysis of optimized molecular geometries, electronic populations by
using the natural bond orbitals scheme. The latter was used to iden-
tify the nature of the interactions between the ligands and the cen-
tral ion. The calculated density of states showed the interactions and
influences the orbital composition in the frontier electronic struc-
ture. The time dependent density functional theory (TD-DFT) was
finally used to calculate the electronic absorption spectra. Based
on a molecular orbital scheme, these results allowed for the inter-
pretation of the UV–Vis spectra obtained at an experimental level.
From the application point of view catalytic activity in the
reaction of the double bond migration in allyl phenyl ether and
4-allyloxybutan-1-ol for both of the complexes was tested.
low lying p-antibonding orbitals, which can accept electrons from
filled metal d orbitals. In consequence, they can exhibit charge
transfer bands with interesting spectroscopic properties in the
visible region [7]. N-heterocyclic carboxylic acids like pyridine-,
pyrazine-2-carboxylic acids and derivatives of imidazole 2-carbox-
ylic acid are recognized as efficient N,O-donors exhibiting diverse
mode of coordination. The pyridine ring as a good
to stabilize the ruthenium(II) acceptor center and the imidazole
and its derivatives exhibit moderate -donor properties. Imidazole
p-acceptor tends
p
and its derivatives have seen widespread application in coordina-
tion chemistry [8–11] but are relatively less studied despite the
fact that their moderate p-donor properties are interesting.
⇑
Corresponding authors. Tel.: +48 323591513 (J.G. Małecki)
E-mail addresses: gmalecki@us.edu.pl (J.G. Małecki), stanislaw.krompiec@us.
edu.pl (S. Krompiec).
0277-5387/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.09.051

J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
191
was carried out, verifying that the optimized molecular structure
obtained corresponds to an energy minimum, thus only positive
frequencies were expected. The DZVP basis set [17] with f func-
tions 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, P, H) was 6-31G with a set of ‘‘d’’ and ‘‘p’’ polariza-
tion functions. The TD-DFT (time dependent density functional
theory) method [18] was employed to calculate the electronic
absorption spectra of the complexes in the solvent PCM (Polariz-
able Continuum Model) model. In this work 90 singlet excited
states was calculated as vertical transitions for the complexes. A
natural bond orbital (NBO) analysis was also made for all the com-
plexes using the NBO 5.0 package [19] 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 orthonor-
mal set of localized orbitals of maximum occupancy. NBO analysis
2. Experimental
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 [13].
2.1. Synthesis of [RuH(CO)(MeImCOO)(PPh3)2]ÁCH3OH (1) and
[RuH(CO)(BimCOO)(PPh3)2] (2)
The complexes (1) and (2) were synthesized in a reaction
between [RuHCl(CO)(PPh3)3] (0.1 g, 1 Â 10À4 mol) and 1-methyl-
1H-imidazole-2-carboxylic acid (MeImCOO), 1H-benzimidazole-
2-carboxylic acid (BImCOO) in methanol solutions (100 cm3). The
mixture of the compounds was refluxed in methanol by 4 h. After
this time, it was cooled and filtered. The crystals suitable for X-ray
crystal analysis were obtained by slow evaporation of the reaction
mixtures.
provides the contribution of atomic orbitals (s, p, d) to the NBO
r
and hybrid orbitals for bonded atom pairs. In this scheme, three
p
1: Yield 52% (0.04 g). IR (KBr): 3413
m
OH; 3057
m
ArH; 2955 mCH
;
NBO hybrid orbitals are defined, bonding orbital (BD), lone pair
(LP), and core (CR), which were analyzed on the atoms directly
bonded to or presenting some kind of interaction with the ruthe-
nium atom. The contribution of a group (ligands, central ion) to a
molecular orbital was calculated using Mulliken population analy-
sis. GAUSSSUM 2.2 [20] 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 information with Gaussian curves of unit height
and FWHM (Full Width at Half Maximum) of 0.3 eV.
1973 (CO); 1922 (Ru–H); 1650, 1633m(C@N; C@C); 1587 mas(COO)
m
m
;
1479 d(C–CH in the plane); 1433
m
Ph(P–Ph); 1325
plane); 695 d(C–C plane); 517, 493
in the
m
s(COO); 1093 d(C–CH in
plane); 743 d(C–C
the
out of the
m(N;O;P–Ru)
.
Anal. Calc. for C42H36N2O3P2Ru,CH4O: C, 63.62; H, 4.97; N, 3.45;
O, 7.88; P, 7.63; Ru, 12.45%. Found: C, 63.47; H, 4.85; N, 3.49%.
UV–Vis (methanol; log e) [nm]: 360 (1.22), 268 (2.46), 245
(2.91), 215 (4.82). 1H NMR (400 MHz, CDCl3) d 7.80–7.30 (m,
PPh3, Im), 6.51 (s, Im), 6.43 (s, Im), 3.49 (s, CH3(Im)), 3.39 (s, metha-
nol), À10.36 (t, J = 20.4 Hz, H(Ru)). 31P NMR (162 MHz, CDCl3) d
41.10 (d, J = 26.8 Hz), 37.28 (d, J = 26.6 Hz).
2: Yield 53% (0.04 g). IR (KBr): 3056
1634 (C@N; C@C); 1587 as(COO); 1468 d(C–CH in the plane); 1433 mPh(P–
Ph); 1327 s(COO); 1093 d(C–CH plane); 742 d(C–C
693 d(C–C in the plane); 518 m(N/O/P–Ru)
Anal. Calc. for C45H36N2O3P2Ru: C, 66.25; H, 4.45; N, 3.43; O,
5.88; P, 7.59; Ru, 12.39%. Found: C, 66.29; H, 4.39; N, 3.39%.
mArH, 1932 m(CO)/m(Ru–H);
m
m
2.4. Crystal structures determination and refinement
m
;
out of the plane)
in the
.
The pale yellow crystals of [RuH(CO)(MeImCOO)(PPh3)2]ÁCH3OH
(1) and [RuH(CO)(BImCOO)(PPh3)2] (2) were mounted in turn on an
Xcalibur, Atlas, Gemini Ultra Oxford Diffraction automatic diffrac-
tometer equipped with a CCD detector, and used for data collection.
X-ray intensity data were collected with graphite monochromated
UV–Vis (methanol; log e) [nm]: 340 (1.26), 291 (2.09), 269
(1.81), 208 (4.92). 1H NMR (400 MHz, CDCl3) d 8.12 (s, NH) 7.87–
6.81 (m, PPh3, BIm), À10.11 (t, J = 20.0 Hz, H(Ru)). 31P NMR (CDCl3)
d 40.30 (d, J = 26.5 Hz), 37.48 (d, J = 26.2 Hz).
Mo Ka radiation (k = 0.71073 Å) at temperature 295.0(2) K, with x
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 11355 and 9268
strongest reflections for complexes 1 and 2 respectively. Details
concerning crystal data and refinement are gathered in Table 1.
Lorentz, polarization and empirical absorption correction using
spherical harmonics implemented in SCALE3 ABSPACK scaling algo-
rithm [21] were applied. The structure was solved by the Patterson
method and subsequently completed by the difference Fourier
recycling. All the non-hydrogen atoms were refined anisotropically
using full-matrix, least-squares technique. The Ru–H hydrogen
atoms were found from difference Fourier synthesis after four
cycles of anisotropic refinement, and refined as ‘‘riding’’ on the
adjacent carbon atom with individual isotropic temperature factor
equal 1.2 times the value of equivalent temperature factor of the
parent atom. The OLEX2 [22] and SHELXS97, SHELXL97 [23] programs
were used for all the calculations. Atomic scattering factors were
incorporated in the computer programs.
2.2. Physical measurements
Infrared spectra were recorded on a Perkin Elmer spectrophot-
ometer in the spectral range 4000–450 cmÀ1 using KBr pellets.
Elemental analyses (C, H, N) were performed on a Perkin-Elmer
CHN-2400 analyzer. Electronic spectra were measured on a Lab
Alliance UV–Vis 8500 spectrophotometer in the range of 600–
180 nm in methanol solution. The 1H and 31P NMR spectra were
obtained at room temperature in CDCl3 using Bruker 400 MHz
spectrometer. Luminescence measurements were made in metha-
nolic solutions on an F-2500 FL spectrophotometer at room
temperature.
Voltammetric investigations of the complexes were carried out
using an Autolab potentiostat (Eco Chemie). Complexes were dis-
solved in 0.1 M acetonitrile solution of Bu4NPF6. The measure-
ments were performed using a platinum working electrode and
referenced against Cp2Fe+/0 couple.
2.3. Computational methods
2.5. Application studies
The calculations were carried out using GAUSSIAN09 [14] program.
Molecular geometries of the singlet ground state of complexes 1
and 2 were fully optimized in the gas phase at the B3LYP/DZVP
level of theory [15,16]. For each compound a frequency calculation
2.5.1. Allyl substrates
Allyl phenyl ether was purchased from Aldrich, and 4-allyloxyb-
utan-1-ol was prepared according to the procedure described in
the literature [24].

192
J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
Table 1
imidazole aromatic protons in the spectrum of complex 1 are vis-
ible as singlets at 6.51 and 6.43 ppm. The signals are shifted com-
pared with free ligand (7.01, 6.86 ppm) due to the shielding effect
of the ruthenium central ion. The signals at 3.49 and 3.39 ppm
indicate the methyl group in position 1 in imidazole ring and the
methanol, which occurs as solvent in the structure of the complex.
The spectrum of complex 2 presents the signal at 8.12 ppm attrib-
uted to NH group of benzimidazole. The 1H NMR spectra of the
complexes present signals at high field (À10.36 and À10.11 ppm)
which indicates the presence of the hydride coordinated with the
metal. The shifts of the signals are due to the shielding effect of
the metal and to the charge of the hydrogen atom. The Ru–H sig-
nals are triplets due to coupling with the two trans phosphorus
atoms (JHP ꢀ 20 Hz). The 31P NMR spectra of the complexes show
two doublets in the range 41–37 ppm. The presence of magneti-
cally unequivalent phosphorus atoms suggesting the presence of
two triphenylphosphine groups not in perfect trans positions. The
doublets in the 31P NMR spectra are in accordance with the struc-
tures confirmed by X-ray especially given the electronic interac-
Crystal data and structure refinement details of [RuH(CO)(MeImCOO)(PPh3)2]ÁCH3OH
(1), [RuH(CO)(BImCOO)(PPh3)2] (2) complexes.
1
2
Empirical formula
Formula weight
T (K)
Crystal system
Space group
Unit cell dimensions
a (Å)
C
42H36N2O3P2Ru,CH4O C45H36N2O3P2Ru
811.78
295.0(2)
triclinic
P1
815.77
295.0(2)
triclinic
P1
ꢀ
ꢀ
12.1574(5)
16.5534(4)
19.5382(9)
92.527(3)
97.790(4)
90.006(3)
3891.8(3)
4
10.6695(7)
12.1113(7)
31.2754(14)
83.049(4)
88.330(4)
86.166(5)
4001.9(4)
4
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
Calculated density (mg/m3)
Absorption coefficient
1.385
0.529
1.354
0.513
(mmÀ1
F(000)
)
1672
1672
Crystal dimensions (mm)
h range for data collection (°)
Index ranges
0.28 Â 0.19 Â 0.08
3.38–25.05
À14 6 h 6 14
À19 6 k 6 19
À23 6 l 6 22
35256
0.37 Â 0.32 Â 0.06
3.38–25.05
À12 6 h 6 12
À14 6 k 6 14
À37 6 l 6 36
36636
tions (p–p stacking) between PPh3 phenyl and imidazole rings.
The IR spectra of the complexes 1 and 2 display strong C„O
bands at 1973 and 1932 cmÀ1 and the Ru–H stretching bands are
displayed at 1922 cmÀ1 in spectrum of complexes 1 and in the case
of 2 the band is combined with the Ru–CO band. The mCO and mRu–H
Reflections collected
Independent reflections
13747
14157
stretching bands in the parent [RuHCl(CO)(PPh3)3] complex are at
2020 and 1922 cmÀ1 respectively and the decreasing of carbonyl
stretches are clearly visible in the studied complexes. The elec-
tron–donor hydride ligand at Ru(II) ion delivers electron density
via backbonding to the anti-bonding orbitals of the CO and pro-
duces a decrease in the vibration frequency of the CO bond. The
electronic effect is supported by theoretically determined charge
values which indicate the negative charges of Ru(II) central ion
(À0.74) in both complexes. Besides the charges on the hydride ions
are close to zero (0.07) with positive sign. Additionally the decreas-
ing of the CO vibration frequencies from 1973 to 1932 cmÀ1 in the
complexes 1 and 2 respectively indicates the differences in the
acceptor properties of 1-methyl-1H-imidazole-2-carboxylic acid
and 1H-benzimidazole-2-carboxylic acid. In fact, by reducing the
electron density on the metal the carbonyl ligand will receive the
[R(int) = 0.0447]
13747/0/951
1.066
R1 = 0.0507
wR2 = 0.1095
R1 = 0.0766
wR2 = 0.1186
[R(int) = 0.0672]
14157/0/963
1.142
R1 = 0.0691
wR2 = 0.1128
R1 = 0.0886
wR2 = 0.1291
1.332 and À1.781
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2
r(I)]
R indices (all data)
Largest difference in peak and 0.747 and À0.889
hole
2.5.2. Isomerization of allyl compounds
Allyl compound (2 mmol) and [Ru]–H (0.01 mmol) were stirred
with magnetic stirrer and heated in 120, 130 or 140 °C during
3–24 h under argon atmosphere (see Table 5). The post-reaction
mixture was analyzed using 1H NMR technique.
electron density via dp ?
p⁄ interaction, which would increases
the bond order in turn increasing the vibration frequency of the
CO bond. So it can be said that the 1H-benzimidazole-2-carboxylic
acid ligand behaves as stronger acceptor with respect to the
1-methyl-1H-imidazole-2-carboxylic acid derivative. Stretching
vibrations for C@C and C@N are observed in the 1650–1633 cmÀ1
range. The asymmetric and symmetric stretches of COO groups
gave the bands with maxima at 1587 cmÀ1 and 1325 and
1327 cmÀ1 respectively. The carboxyl group stretches in the free
2.5.3. Isolation of pure 1-propenyl derivatives (only when conversion
of the allyl substrate was practically quantitative)
The post-reaction mixture was diluted with 10 cm3 of hexane, fil-
tered and then 20 mg of activated carbon (Norit CN-1, Acros; 1 g/
10 mg Ru) was added. The suspension was stirred for 2 h, filtered
and volatile residues were evaporated on rotary evaporator. Isomer-
ization products, practically ruthenium-free (<0.1 ppm Ru) were
obtained with 95% yield. Spectroscopic data of obtained products
were in good agreement with literature data for (E)- and
(Z)-PhOCH@CHCH3 [25], (E)-and(Z)-HOCH2CH2CH2CH2OCH@CHMe.
1H NMR (400 MHz, C6D6) d = 1.40–1.59 (m, 8H), 1.45 (dd, 3H,
J = 1.6 Hz, J = 6.7 Hz), 1.69 (dd, 3H, J = 1.7 Hz, J = 6.8 Hz) 2.29–2.37
(m, 2H), 3.37–3.45 (m, 8H), 4.37 (dq, 1H, J = 6.7 Hz, J = 13.1 Hz),
4.72 (dq, 1H, J = 6.7 Hz, J = 12.6 Hz), 5.80 (dq, 1H, J = 1.7 Hz,
J = 6.2 Hz), 6.18 (dq, 1H, J = 1.5 Hz, J = 12.6 Hz) ppm.
ligands are observed at 1668 and 1367 cmÀ1
.
3.2. Molecular structures
Crystals of the complexes suitable for single crystal X-ray anal-
yses were obtained by slow evaporation of the reaction mixtures.
ꢀ
The complexes 1 and 2 crystallize in triclinic P1 space group and
in their molecular structures two independent molecules in the
asymmetric unit exist. The complex 1 crystallizes as solvate with
one methanol molecule. Fig. 1 presents the molecular structures
of the complexes and the selected bond distances and angles are
collected in Table 2. The Ru–H bond lengths in complex 1 are
longer than that in 2 which is connected with the differences in
acceptor properties of the MeImCOO and BImCOO ligands. In the
case of complex 2 the Ru(1)–H(1) bond length is abnormally short
but ruthenium(II) hydridecarbonyl complexes in which Ru–H dis-
tances near 1.3 Å (Ru(2)–H(2) 1.26(6) Å) are known [26–29].
13C NMR (100 MHz, C6D6): d = 9.5, 12.7, 26.2, 26.7, 29.5, 29.7,
62.2, 68.9, 71.9, 98.2, 100.7, 146.1, 147.2 ppm.
3. Results and discussion
3.1. Spectroscopic characterization of the complexes
The 1H NMR spectra of the complexes show a set of signals
corresponding to the PPh3 and imidazole derivative ligands. The

J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
193
The structures of the complexes can be considered as a distorted
octahedral with the largest deviation from the expected 90° bond
angles coming from the bite angle of imidazole carboxylic acid. It
equals to 75.59(18)°, 75.38(18)° and 74.9(3)°, 75.1(2)° for N–Ru–O
angles in complexes (1) and (2) respectively. The P–Ru–P angles
are lower than 180° vary in the 166.84(9)–174.05(6)° range. As
shown in Fig. 1, the CO groups are in the trans positions to the
carboxyl groups of imidazole type ligands in the complexes. This
Fig. 1. ORTEP drawings of [RuH(CO)(MeImCOO)(PPh3)2]ÁCH3OH 1 and [RuH(CO)(BImCOO)(PPh3)2] 2 and complexes with 30% probability displacement ellipsoids. Hydrogen
atoms (except Ru–H) and solvent are omitted for clarity.

194
J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
Table 2
Selected bond lengths (Å) and angles (°) for [RuH(CO)(MeImCOO)(PPh3)2]ÁCH3OH (1) and [RuH(CO)(BImCOO)(PPh3)2] (2) complexes.
Exp.
Exp.
Calc.
1
Bond lengths (Å)
Ru(1)–C(1)
Ru(1)–N(1)
Ru(1)–O(2)
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–H1(Ru)
C(1)–O(1)
1.825(7)
2.198(5)
2.172(4)
2.343(16)
2.3596(16)
1.63(6)
Ru(2)–C(43)
Ru(2)–N(3)
Ru(2)–O(5)
Ru(2)–P(1)
Ru(2)–P(2)
Ru(2)–H2(Ru)
C(2)–O(4)
1.818(7)
2.188(5)
2.170(5)
2.358(16)
2.347(16)
1.52(7)
1.855
2.265
2.177
2.422
2.438
1.610
1.164
1.158(9)
1.153(8)
Angles (°)
C(1)–Ru(1)–O(2)
C(1)–Ru(1)–N(1)
O(2)–Ru(1)–N(1)
C(1)–Ru(1)–P(2)
O(2)–Ru(1)–P(2)
P(2)–Ru(1)–N(1)
P(1)–Ru(1)–C(1)
P(1)–Ru(1)–O(2)
P(1)–Ru(1)–N(1)
P(1)–Ru(1)–P(2)
C(1)–Ru(1)–H(1)
O(2)–Ru(1)–H(1)
N(1)–Ru(1)–H(1)
P(2)–Ru(1)–H(1)
P(1)–Ru(1)–H(1)
Ru(1)–C(1)–O(1)
177.8(3)
104.2(3)
75.59(18)
88.1(2)
94.06(12)
90.17(14)
93.1(2)
84.77(12)
95.17(14)
174.05(6)
85.0(2)
96.0(2)
170.0(2)
87.0(2)
87.0(2)
178.4(7)
C(43)–Ru(1)–O(5)
C(43)–Ru(1)–N(3)
O(5)–Ru(1)–N(3)
C(43)–Ru(1)–P(4)
O(5)–Ru(1)–P(4)
P(4)–Ru(1)–N(3)
P(3)–Ru(1)–C(43)
P(3)–Ru(1)–O(5)
P(3)–Ru(1)–N(3)
P(3)–Ru(1)–P(4)
C(43)–Ru(1)–H(2)
O(5)–Ru(1)–H(2)
N(3)–Ru(1)–H(2)
P(4)–Ru(1)–H(2)
P(3)–Ru(1)–H(2)
Ru(2)–C(1)–O(2)
177.9(2)
102.7(3)
75.38(18)
94.1(2)
85.34(12)
95.56(14)
87.4(2)
93.47(12)
92.75(14)
171.02(6)
90.0(3)
92.0(3)
167.0(3)
82.0(3)
90.0(3)
178.2(7)
177.58
103.09
74.61
90.36
90.58
94.64
94.06
85.49
96.05
167.20
89.00
93.00
168.00
86.00
82.00
178.66
2
Bond lengths (Å)
Ru(1)–C(1)
Ru(1)–N(1)
Ru(1)–O(2)
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–H(1)
C(1)–O(1)
1.798(11)
2.203(7)
2.180(6)
2.346(3)
2.348(3)
1.06(6)
Ru(2)–C(46)
Ru(2)–N(3)
Ru(2)–O(5)
Ru(2)–P(3)
Ru(2)–P(4)
Ru(2)–H(2)
C(46)–O(4)
1.811(10)
2.182(7)
2.179(6)
2.329(3)
2.357(3)
1.26(6)
1.851
2.261
2.209
2.429
2.429
1.620
1.164
1.179(13)
1.152(12)
Angles (°)
C(1)–Ru(1)–O(2)
C(1)–Ru(1)–N(1)
O(2)–Ru(1)–N(1)
C(1)–Ru(1)–P(2)
O(2)–Ru(1)–P(2)
N(1)–Ru(1)–P(2)
C(1)–Ru(1)–P(1)
O(2)–Ru(1)–P(1)
N(1)–Ru(1)–P(1)
P(2)–Ru(1)–P(1)
C(1)–Ru(1)–H(1)
O(2)–Ru(1)–H(1)
N(1)–Ru(1)–H(1)
P(2)–Ru(1)–H(1)
P(1)–Ru(1)–H(1)
Ru(1)–C(1)–O(1)
175.6(4)
100.7(4)
74.9(3)
91.7(4)
89.40(19)
95.2(2)
90.1(4)
89.72(19)
96.5(2)
167.56(10)
91.0(3)
94.0(3)
C(46)–Ru(1)–O(5)
C(46)–Ru(1)–N(3)
O(5)–Ru(1)–N(3)
C(46)–Ru(1)–P(4)
O(5)–Ru(1)–P(4)
N(3)–Ru(1)–P(4)
C(46)–Ru(1)–P(3)
O(5)–Ru(1)–P(3)
N(3)–Ru(1)–P(3)
P(4)–Ru(1)–P(3)
C(46)–Ru(2)–H(2)
O(5)–Ru(2)–H(2)
N(3)–Ru(2)–H(2)
P(3)–Ru(2)–H(2)
P(4)–Ru(2)–H(2)
Ru(1)–C(46)–O(4)
175.3(4)
100.3(4)
75.1(2)
91.0(3)
90.51(16)
97.4(2)
91.3(3)
88.25(16)
95.0(2)
166.84(9)
92.0(3)
93.0(3)
173.77
98.71
75.06
92.76
88.00
96.32
92.76
88.00
96.32
165.28
91.00
96.00
171.00
83.00
83.00
175.84
168.0(3)
82.0(3)
86.0(3)
168.0(3)
83.0(3)
84.0(3)
177.9(11)
176.5(11)
configuration is preferred because of the donor/acceptor properties
of the carboxyl and carbonyl groups.
3.3. Optimized geometries, hybrid and molecular orbitals description
In the molecular structures of the complexes several inter- and
intra-molecular hydrogen bonds [30] exist collected in Table 3.
Additionally in the structure of the complexes some electronic
The ground states geometries of the complexes were optimized
in singlet states using the DFT method with the B3LYP functional.
The calculations were carried out for gas phase molecules and in
general, the predicted bond lengths and angles are in an agreement
with the values based on the X-ray crystal structure data, and the
general trends observed in the experimental data are reproduced
in the calculations. The calculated IR frequencies of complexes 1
confirm calculated structures with experimental ones and the dif-
ferences in calculated and experimental spectra mainly result from
the negligence of intermolecular interactions for the gas phase.
From the data collected in Table 2, one may see that the major of
differences between the experimental and calculated geometries
interactions (p–p stacking) between PPh3 phenyl and imidazole
rings are visible. The plane-to-plane distances between the
phosphine phenyl centroids, determined by C(7)–C(12) and
C(79)–C(84) carbons, and imidazole rings are equal to 3.74 and
3.79 Å in complex 1 indicating p–p stacking interactions. A similar
arrangement between phosphine phenyl and imidazole rings
occurs in the structures of the complex 2, where the distances
between phenyl rings C(28)–C(33) and C(67)–C(72) and Im
centroids are 3.77 and 3.59 Å.

J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
195
GAUSSSUM program and Fig. 2 presents the composition of the frag-
ment orbitals contributing to the molecular orbitals for complexes
1 and 2. The HOMOs are mainly localized on the ruthenium atoms
(ꢀ66% and 61% in 1 and 2) with contribution from triphenylphos-
phine (ꢀ25%) and imidazole derivative ligands (ꢀ14%). The HOMO,
HOMOÀ1 and HOMOÀ2 in the complexes are localized on the d
ruthenium orbitals (53–71%) with contribution of imidazole deriv-
atives ligands. The dz2 ruthenium orbital plays role in LUMO and
LUMO+1 in complexes 1 and 2 respectively. LUMO orbital in com-
plex 2 is mainly localized on the 1H-benzimidazole-2-carboxylic
Table 3
Hydrogen bonds for [RuH(CO)(MeImCOO)(PPh3)2]ÁCH3OH (1) and [RuH(CO)(BIm-
COO)(PPh3)2] (2) complexes (Å and °).
D–HÁ Á ÁA
1
d(D–H)
d(HÁ Á ÁA)
d(DÁ Á ÁA)
<(DHA)
O(98)–H(98). . .O(3)
O(99)–H(99). . .O(6)
C(5)–H(5B). . .O(99) #1
C(5)–H(5C). . .O(3)
C(18)–H(18). . .O(2)
C(21)–H(21). . .O(4) #2
C(27)–H(27). . .O(4)
C(42)–H(42). . .O(2)
C(47)–H(47B). . .O(98)
C(60)–H(60). . .O(5)
C(68)–H(68). . .O(5)
0.82
0.82
0.96
0.96
0.93
0.93
0.93
0.93
0.96
0.93
0.93
1.93
1.89
2.29
2.49
2.45
2.51
2.46
2.52
2.38
2.54
2.40
2.702(10)
2.706(11)
3.237(13)
2.947(11)
3.178(8)
3.401(12)
3.288(12)
3.068(8)
3.295(12)
3.037(8)
3.149(9)
157.3
171.6
169.3
108.8
135.0
160.5
147.6
118.3
160.2
113.9
137.9
acid ligand. The dx2
orbitals participate in the Lumo+9/+13/+14
Ày2
in the case of complex 1 and LUMO+11/14/16 in complex 2. The
carbonyl ligands play significant role in the HOMOÀ1, HOMOÀ2
orbitals and LUMO+14/16 in the complexes.
In Fig. 3, there are presented the interactions between ruthe-
nium central ions and imidazole derivative ligands and hydride
ions in the studied complexes. As one can see the p-acceptor inter-
2
N(2)–H(2). . .O(3) #3
N(4)–H(4A). . .O(6) #4
C(5)–H(5). . .O(4) #5
C(17)–H(17). . .O(2)
C(35)–H(35). . .O(2)
C(50)–H(50). . .O(1)
C(60)–H(60). . .O(5)
C(78)–H(78). . .O(5)
0.86
0.86
0.93
0.93
0.93
0.93
0.93
0.93
1.92
1.91
2.48
2.46
2.40
2.50
2.47
2.35
2.751(10)
2.740(9)
162.6
162.5
150.5
140.5
139.8
152.0
131.5
150.5
3.324(14)
3.236(13)
3.163(14)
3.352(14)
3.163(12)
3.196(13)
action of 1H-benzimidazole-2-carboxylic acid is stronger than 1-
methyl-1H-imidazole-2-carboxylic acid with ruthenium central
ion. At the same time, considerable differences in the interaction
of hydride ions with ruthenium have been visible there. In complex
1 interaction between HÀ towards ruthenium(II) is smaller com-
pared with Ru(II)–H interactions in complex 2. The stronger trans-
fer of electron density to the acceptor dp⁄ ruthenium orbitals is
compensated by p⁄ orbitals of carbonyl ligand and acceptor prop-
erties of BImCOO ligand. The electronic effect explains the differ-
ences in bond lengths of the carbonyl group (average distance:
1.156 Å 1 and 1.166 Å 2) as well as the differences in the stretching
mode maxima in the IR spectra.
Symmetry transformations used to generate equivalent atoms: #1 x, 1 + y, z; #2
1 À x, Ày, 1 À z; #3 Àx, 1 À y, 2 À z; #4 1 À x, 2 À y, 1 À z; #5 À1 + x, y, z.
are found in the Ru–P distance (ꢀ0.09 Å) (not including the length
of the Ru–H bond in the complex 2) and the differences between
angles do not exceed 5.5°.
The NBO analyses were performed for the complexes which
allowed knowing the nature of the coordination between ruthe-
nium and the atoms of the ligands directly interacting with it. This
methodology also gave a better understanding of the optimized
molecular structures. In the analysis was found that the N,O-donor
ligands do not show covalent bonding with ruthenium. The
Coulomb-type interactions between the ruthenium central ions
and imidazole derivatives ligands are clearly visible in the calcu-
lated Wiberg bond indices whose values are considerably lower
than one. The Ru–N and Ru–O bond indices are similar and close
to 0.37 and 0.39 in the complexes. The Ru–P bond orders are also
smaller than 1 (0.7). For the carbonyl groups of the complexes,
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
towards the carbon atom, and the C–O bond orbitals are polarized
towards the oxygen end. The oxygen atom of the carbonyl ligand
has one lone pair (LP) orbital. The charge of CO ligands can be
easily calculated by summing the individual charges on the carbon
and oxygen atoms and has the same value equal to 0.19 in both of
these complexes. The value shows that there is some charge trans-
fer between CO and the Ru fragment. The Wiberg indexes of the CO
bonds in the complexes are reduced (by about 0.22) with respect to
free CO (WCO = 2.23). These weak values are in agreement with the
elongation of the C–O bond in complexes and charge distribution
in the terminal bonding carbonyl group to ruthenium central ion.
The bonding can be described as the result of two electron trans-
3.4. Experimental and theoretical electronic spectra
The UV–Vis spectra of the complexes 1 and 2 are similar and the
maxima close to 360, 268, 245 nm and 340, 291, 269 nm were mea-
sured. Based on the pseudooctahedral geometry of the complexes
and taking into account the d–d transitions assigned to 1A1 ? 1T1
and 1A1 ? 1T2 in octahedron (or 1A1 ? 1A2/B1/E in lower symmetry
fields), the ligand field parameter 10 Dq can be estimated to 26545
and 28463 cm-1 for the complexes (1) and (2) respectively.
Adequately Racah’s parameters are B = 596 and 310 cmÀ1 and the
nepheloauxetic parameters have values b55 = 0.83 and 0.43. The
bands observed in the vicinity of 40000 cmÀ1 (250 nm) have been
attributed to intra- and interligand
(
pbC ? 3dphosphorus and
6H6
p
?
pà ) transitions with admixture of Metal-Ligand Charge
C@C
Transfer transitions (dRu
?
pÃN-ligand and dRu
?
pÃPh). The highest
experimental bands close to 210.0 nm may result from transitions
in the PPh3 ligands and from
type ligands.
p ?
p⁄ excitations in the imidazole
The electronic spectra of the complexes were calculated with
the TDDFT method with methanol as solvent in the polarizable
continuum model (PCM). In Table 4, some calculated electronic
transitions of complex 2 are collected. The first bands have
HOMO ? LUMO character. As the HOMOs are localized on the d
ruthenium orbitals with the admixture of
p-PPh3 and the LUMOs
are localized on the imidazole derivative ligands with the admix-
ture of dz2 ruthenium orbital the Metal–Ligand Charge Transfer
and Ligand Field transitions are associated with these. The next
bands at 268 and 291 nm in complexes 1 and 2, respectively, have
fers. First this binding mode involves a
r-donation from the CO
lone pair orbital to the LUMO orbital of complex. On the other
hand, the highest occupied orbitals of the metallic fragment,
the same character (d ? d and dRu
?
pÃL). The bands with maxima
mainly 4dRu orbitals, are involved in a
p back-bonding from the
metal to the CO p⁄ orbitals.
near 250 nm have also MLCT character with some contribution of
Ligand–Ligand Charge Transfer transitions.
Analysis of the frontier molecular orbitals is useful for under-
standing the spectroscopic properties such as electronic absorption
and emission spectra of organometallic complexes. The electronic
structure of complexes 1 and 2 are similar because of similar com-
position of their coordination sphere. The densities of states (DOS)
in terms of Mulliken population analysis were calculated using the
The emission characteristics of the complexes have been exam-
ined in the dichloromethane solutions (with concentration of
1 Â 10À3 mol/dm3) at room temperature. Fig. 4 presents the excita-
tion and emission spectra for both complexes. The excitations at
314 and 301 nm for complexes 1 and 2 respectively result in the

196
J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
Fig. 2. The density of states (DOS) diagrams for the complexes 1 and 2.
emissions with maxima at 432 and 400 nm. There are also excita-
tions at 391 and 370 nm resulted in weak emissions bands with
maxima at 444 and 419 nm (see inset in Fig. 4). The excitations de-
3.5. Electrochemistry
The electrochemical properties of both of the complexes were
studied in an acetonitrile solution by cyclic voltammetry, and dif-
ferential pulse voltammetry using NBu4PF6 as the supporting elec-
trolyte and referenced against Cp2Fe+/0 couple. In the potential
range 0–1.7 [V] both complexes (1) and (2) revealed redox pro-
cesses, with anodic peak potential at 0.42 [V] and 0.4 [V] respec-
rived from d
?
pÃligand transition, so the emissions are associated
p
with the lowest energy metal to ligand charge transfer (MLCT)
states. The assignments are supported by the analyses of the fron-
tier virtual orbitals (LUMO, LUMO+1) of the complexes showing
contributions of ligands nature. As can be seen in Fig. 4, the com-
plex 2 gives stronger luminescence than the complex 1 which is
related with differences in theirs electronic structures, particularly
with the contribution of imidazole derivatives ligands to formation
the lowest unoccupied molecular orbitals.
tively (see Fig. 5). This is
a typical value for Ru(III)/Ru(II)
oxidation [31]. Nearly identical values are attributed to almost
identical coordination environment of ruthenium atom in these
two complexes. The response is irreversible in nature, and does

J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
197
phosphine ligand (23%). Its position is also in agreement with the
value provide theoretically to be as high as 0.5 [V] (according to
the equation EHOMO = À4.8 À Eox) (see Fig. 2). This peak is an ErCi
process, which means that a soon after a short-lived, oxidized state
is formed, it is followed by irreversible chemical transformation
(probably dimerization, similarly to Rh complexes described by
Bond et al. [32]). The confirmation of this hypothesis is the appear-
ance of an additional peak at the potential of À0.35 [V] after the
former oxidation 2A as one can see in Fig. 5. Shortly after the first
peak is formed, another one can be observed, however much less
intense (2B). Charge ratio for these two processes, namely 2A:2B
is equal to about 6:1 and may be related to the presence of the
complex in two isomeric forms. Further enhance of the potential
produces another pair of peaks 2C and 2D (at potentials 0.86 and
0.99 V, respectively), occurring also in a ratio of about 6:1. What
is worth noting, the charge value ratio (abb. 2A:2C) is approxi-
mately equal to 1:1, suggesting that 2C is an oxidation process of
the ErCi reaction product. In addition, processes 2C and 2D are
reversible (peak-to-peak separation = 60 mV). The 2E appears to
be the further oxidation of the resulting compound. The reduction
for the 2 occurs at the potential À1.82 V and is reversible.
Fig. 3. The overlap partial density of states diagrams (OPDOS) for the 1 and 2
complexes.
For the complex 1 oxidation is also an ErCi process – again, there
is a new peak at the potential of À0.40 [V] after the aforemen-
tioned oxidation 1A. However, along with the further oxidation
of the complex peaks cannot be isolated, which makes the inter-
pretation of the curves impossible. On the other hand, a possible
degradation of the MeImCOO ligand may occur after the oxidation
(contrary to BimCOO), probably due to the lack of stabilizing effect
of the phenyl ring at the oxidized state. Also, reduction, following
the potential À1.55 [V] was found to be irreversible.
Table 4
The calculated electronic transitions for [RuH(CO)(BImCOO)(PPh3)2] complex.
(nm)
f
Transitions
Charter
360.3 0.1035 HOMO ? LUMO (82%)
341.8 0.0237 HOMO ? LUMO (97%)
307.6 0.0084 HÀ1 ? L+1 (71%)
288.1 0.0116 HÀ2 ? LUMO (43%), HOMO ? L+3
(47%)
281.7 0.0234 HOMO ? L+5 (76%)
273.5 0.0151 HÀ3 ? LUMO (82%), HÀ2 ? LUMO
(10%)
dRu
dRu
?
?
pÃBImCOO
pÃBImCOO
d
dRu
Ru ? dRu
?
pÃBImCOO
dRu
?
pÃBImCOO
dRu(II)
/
3.6. Catalytic activity
pBImCOO
pÃPPh3
pBImCOO
?
pÃBImCOO
271.5 0.025
267.5 0.1486 HÀ4 ? LUMO (83%)
265.4 0.233
HOMO ? L+6 (95%)
dRu ?
d
?
pÃBImCOO
The synthesized hydride complexes turned out to be active cat-
alysts of double bond migration in two selected O-allyl compounds
– Scheme 1 and Table 5. In the literature, a large number of hydride
ruthenium complexes, useful as catalysts for a double bond migra-
tion in allylic systems, including O-allylic systems, have been
described [33–35]. Usually the complexes, which contained beside
hydride ligands in their coordination sphere ligands such as:
carbonyl, phosphines (PPh3 particularly), arenes (benzene or
p-cymene), dienes (COD or NBD) or Cl. In particular, many papers
HÀ3 ? L+1 (26%), HÀ2 ? L+1 (14%), dRu(II)
/
HOMO ? L+7 (42%)
pBImCOO ? dRu/
pÃPPh3
not change with the increase of the scan rate (in range 0.1–5.0 V/s).
As revealed in DFT calculations, this transition for 2, involves orbi-
tal located mainly on Ru (66%) with a small contribution of the
Fig. 4. The fluorescence spectra of the 1 and 2 complexes in the dichloromethane solutions (c = 1 Â 10À3 mol/dm3).

198
J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
0.010
0.009
0.008
0.007
0.006
0.005
0.004
0.003
0.002
0.001
0.000
-0.001
0.05
(a)
(b)
1D
0.04
[RuH(CO)(MeImCOO)(PPh3)2]
1A
2E
[RuH(CO)(BimCOO)(PPh3)2]
2A
0.03
0.02
0.01
0.00
-0.01
1C
2D
2C
1B
2B
-0.6
0.0
0.6
1.2
1.8
-0.5
0.0
0.5
1.0
1.5
2.0
potential (vs. Fc/Fc+) / V
Potential (vs. Fc/Fc+) / V
0.08
0.06
0.04
0.02
0.00
-0.02
(c)
(d)
[RuH(CO)(BimCOO)(PPh3)2]
[RuH(CO)(BimCOO)(PPh3)2]
1 scan
2 scan
[RuH(CO)(MeImCOO)(PPh3)2]
-1.0 -0.8 -0.6 -0.4 -0.2 0.0
0.2
0.4
0.6
0.8
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
potential (vs. Fc/Fc+) / V
Potential (vs. Fc/Fc+) / V
Fig. 5. Cyclic voltammograms (CV, black lines) of 1 (a) and 2 (b) in acetonitrile solutions containing 0.1 M NBu4PF6 at a scan rate of 100 mV/s. The red lines are differential
pulse voltammograms with a step potential of 2.5 mV and an amplitude of 50 mV; (c) cyclic voltammograms (CV) of 2 in acetonitrile containing 0.1 M NBu4PF6 at a scan rate
of 100 mV/s (range from À1 to 0.8 [V]); (d) cyclic voltammograms (CV) of 1 (at the bottom) and 2 (top) in acetonitrile solutions containing 0.1 M NBu4PF6 at a scan rate of
100 mV/s. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)
were devoted to: [RuClH(CO)(PPh3)3] [33–39], [RuH2(CO)(PPh3)3]
[34–36], [RuH2(PPh3)4] [33–35] and complexes generated in situ
from non-hydride precursors (e.g. {[RuCl2(COD)]x}) and hydride
ligand donors [33–38]. However, according to our best knowledge,
hydride Ru(II) complexes with N,O-donor ligands, were not tested
as a catalysts for isomerization of allyl compounds so far.
5 show that the conversion of allyl substrate was practically quan-
titative (at 120°, after 24 h) for complex 1. In these cases pure,
practically ruthenium-free 1-propenyl products were obtained
using method previously described by us, i.e. adsorption of Ru
compounds and impurities on activated carbon [41]. The rise of
the isomerization reaction temperature in the case of complex 2
(up to 130 or 140 °C) probably caused decomposition of the
complex – there was not any significant raise of allyl substrate
conversions over those presented in Table 5. It is noteworthy, that
the advantage of complex 1 is its selectivity. It neither catalyzes
cyclization of 4-allyloxybutan-1-ol to cyclic acetal nor polymeriza-
tion – which could be expected. Thus, it is suitable to obtain
HO–(CH2)n–OCH@CHCH3 via isomerization of appropriate allyl
hydroxyalkyl ethers. According to our results, hydride complexes
containing chloride ligand or simple RuCl3Á3H2O, catalyze subse-
quent cyclization or polymerization of double bond migration
product [42]. It is a result (described in the literature) of HCl
generation from the reaction between precursor and ROH [42].
Generated HCl catalyzes subsequent OH group addition to the
double bond from vinyl ethers, even at room temperature. We
also checked, that HO(CH2)4OCH@CHCH3 cyclization occurs
rapidly in the NMR tube, even if CDCl3 contains trace amounts of
HCl.
Results presented in Table 5 shows, that both of the examined
complexes are active as catalysts of the double bond migration in
O-allylic systems, moreover complex 1 is much more active than
complex 2. In complex 2, Ru–H bond distance (1.53 Å) is shorter
than in complex 1 (1.64 Å) as a result of carboxybenzimidazole
ligand effect, which is more electron acceptor than carboxyimidaz-
ole ligand (see Section 3.1). Decrease of Ru–H bond length is asso-
ciated with increase of its strength, which is crucial for catalytic
activity of complexes in double bond migration reaction, according
to hydride mechanism [33–35,40]. The key-step of this reaction
runs through alkene insertion into Ru–H bond. Decrease of the
Ru–H bond distance certainly impedes this isomerization step;
therefore complex 2 is less active than complex 1. Moreover, it is
very unlikely that during catalytic reaction, O,N-donor ligand dis-
sociates (triphenylphosphine ligand dissociation occurs, what is
well known [40]). O,N-carboxyimidazole-ligand interacts on cata-
lytic reaction center in all of its steps. Results presented in Table

J.G. Małecki et al. / Polyhedron 49 (2013) 190–199
199
Table 5
(BImCOO)(PPh3)2] complexes, respectively. 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.
Isomerization of selected allyl compounds to their 1-propenyl derivatives catalyzed
by ruthenium-hydride complexes.a
Q
[Ru]
t (°C);
s
(h)
Conv. (%)b,c; Z/Ec
PhO
(1)
120; 3
120; 24
120; 3
82; 61/39
100; 62/38
18; 79/21
34; 78/22
(2)
References
120; 24
HO(CH2)4O
(1)
(2)
120; 3
120; 24
120; 3
120; 24
55; 49/51
100; 57/43
22; 68/32
37; 74/26
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b
c
Qallyl/Ru = 200; without solvent; argon atmosphere.
Only 1-propenyl derivatives were detected as the products.
Determined by 1H NMR.
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[Ru]-H
Q = PhO- or HO-(CH2)4-O-
Me
Q
Q
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Scheme 1. Isomerization of selected O-allyl compounds catalyzed by Ru–H
complexes.
4. Conclusion
Two new hydride-carbonyl ruthenium(II) complexes with imid-
azole carboxylic acid ligands were synthesized and characterized
by infra red, proton and phosphorus nuclear magnetic resonance,
electronic absorption and emission spectroscopy and X-ray crystal-
lography. Based on the crystal structures, computational studies
were carried out in order to determine the electronic structure of
the complexes. The theoretical results obtained from NBO and
analysis of the interactions between ruthenium central ions and
imidazole derivative, carbonyl and hydride ligands were used to
explain the differences in bond lengths as well as the differences
in the stretching mode maxima in the IR spectra of the complexes.
The electronic structures of these complexes, presented in particu-
lar by the density of states diagrams, have been correlated with
their ability to fluoresce and used to analyze the UV-Vis spectra
as well as their electrochemical properties.
The catalytic activity in the reaction of the double bond migra-
tion in allyl phenyl ether and 4-allyloxybutan-1-ol for both of the
complexes was tested. Complex 1 was much more active than
complex 2. According to us, it is a result of the longer Ru–H bond
distance in complex 1 in comparison with complex 2. In complex
2, Ru–H bond is shorter and stronger, which makes difficult the
key step of the isomerization, i.e. alkene insertion to the double
bond.
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Acknowledgments
This work was supported by The State Committee for Scientific
Research, Project No. N N204 272237 and The National Science
Centre, Project No. 2011/01/B/ST5/06309. Mateusz Penkala and
Michal Filapek are grateful for scholarship from the UPGOW pro-
ject co-financed by the European Social Fund. Calculations have
been carried out in Wroclaw Centre for Networking and Supercom-
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Appendix A. Supplementary data
CCDC 854203 and 854210 contain the supplementary crystallo-
graphicdata for [RuH(CO)(MeImCOO)(PPh3)2]ÁCH3OH and [RuH(CO)