Synthesis, crystal, molecular, and electronic structures of hydride carbonyl ruthenium(II) complexes with pseudohalide ligands

Article abstract of DOI:10.1007/s11243-013-9707-7

Two pseudohalide hydride carbonyl ruthenium(II) complexes with formulae: [RuH(N₃)(CO)(PPh₃)₃] (1) and [RuH(NCO)(CO)(PPh₃)₃] (2) have been synthesized by the reactions of [RuHCl(CO)(PPh₃)

Full text of DOI:10.1007/s11243-013-9707-7

Transition Met Chem (2013) 38:419–428
DOI 10.1007/s11243-013-9707-7
Synthesis, crystal, molecular, and electronic structures of hydride
carbonyl ruthenium(II) complexes with pseudohalide ligands
•
Anna Maron Jan Grzegorz Małecki
´
Received: 15 January 2013 / Accepted: 18 February 2013 / Published online: 28 February 2013
ꢀ Springer Science+Business Media Dordrecht 2013
Abstract Two pseudohalide hydride carbonyl ruthe-
nium(II) complexes with formulae: [RuH(N3)(CO)(PPh3)3]
(1) and [RuH(NCO)(CO)(PPh3)3] (2) have been synthesized
by the reactions of [RuHCl(CO)(PPh3)3] with sodium azide
or sodium cyanate, respectively, and are compared with the
previously described thiocyanate analog [RuH(NCS)(CO)-
(PPh3)3]. The molecular structures of the new compounds
were determined by X-ray crystallography and their spec-
troscopic properties have been studied. Based on the crystal
structures, computational investigations have been carried
out in order to determine the electronic structures of the
complexes. The electronic spectra were calculated with the
use of time-dependent DFT methods, and the electronic
spectra of the transitions were correlated with the molecular
orbitals of the complexes.
[RuHCl(CO)(PPh3)3] is very interesting. To date, the
greatest attention has been paid to chloride analogs with
heteroaromatic ligands in contrast to pseudohalide deriva-
tives. The introduction of thiocyanate, cyanate, or azide
groups to the ruthenium coordination sphere modifies the
electronic structures of the resulting complexes sufficiently
to allow for tuning their spectroscopic and redox proper-
ties, as in the case of heteroaromatic ligands. It is well
known that pseudohalide ligands tune the spectral and
redox properties of ruthenium(II) complexes by destabi-
lizing the metal t2g orbital. Thus, understanding of the
differences in crystal, molecular, and electronic structures
of such complexes is of interest.
In this paper, we report the synthesis, crystal, molecular,
and electronic structures of new azide and cyanate analogs
of [RuHCl(CO)(PPh3)3], their spectroscopic characteriza-
tion, and discussion of their properties with respect to
[RuH(SCN)(CO)(PPh3)3], which was described in a recent
publication [7]. Based on the crystal structures, computa-
tional studies were carried out in order to determine the
electronic structures of the complexes by analysis of their
optimized molecular geometries and their electronic pop-
ulations using the natural bond orbitals scheme. In addi-
tion, time-dependent density functional theory (TD-DFT)
was used to calculate the electronic absorption spectra.
These results allowed for the interpretation of the experi-
mental UV–Vis spectra. The luminescence properties of
the complexes are also reported.
Introduction
Hydride carbonyl ruthenium(II) complexes containing tri-
phenylphosphine ligand are of growing interest for their
potential applications [1–5]. The hydride ligand, a power-
ful r-donor, is found to be very efficient for the compen-
sation of electron deficiency at the central metal in such
complexes. The ‘‘trans effect’’ of the H- ligand and the
interaction between CO and N-donor ligands in mutually
trans positions are factors which help to explain the sta-
bility of the complexes [6]. Hence, the synthesis and
spectral characterization of new hydride carbonyl ruthe-
nium(II) complexes derived from the parent complex
Experimental
´
A. Maron (&) ꢀ J. G. Małecki
The [RuHCl(CO)(PPh3)3] was synthesized by the literature
method [8]. All other reagents were commercial materials
and have been used without further purification.
Department of Crystallography, Institute of Chemistry,
University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
e-mail: ank806@wp.pl
123

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Transition Met Chem (2013) 38:419–428
Synthesis of the complexes [RuH(N3)(CO)(PPh3)3] (1),
[RuH(NCO)(CO)(PPh3)3] (2)
energy minimum, and thus, only positive frequencies were
expected. The DZVP basis set [12] 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, S, P, H) was 6-31G with a set of d
and p polarization functions. TD-DFT [13] was employed
to calculate the electronic absorption spectra of the com-
plexes. The solvent effect of methanol was included with
the polarizable continuum model. In this work, 100 singlet
excited states were calculated as vertical transitions for the
complexes. A natural bond orbital (NBO) analysis was also
made for all the complexes using the NBO 5.0 package
[14] included in Gaussian 09. NBO 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, specifically
bonding orbital, lone pair, and core. These were analyzed
on the atoms directly bonded to or presenting some kind of
interaction with the ruthenium atom. The contribution of
each group (ligands, central metal) to a given molecular
orbital was calculated using Mulliken population analysis.
GaussSum 2.2 [15] was used to calculate group contribu-
tions 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 of 0.3 eV.
The complexes [RuH(N3)(CO)(PPh3)3] (1) and [RuH(NCO)-
(CO)(PPh3)3] (2) were synthesized by the reactions of
[RuHCl(CO)(PPh3)3] (0.2 g; 2.0 9 10-4 mol) and sodium
azide or sodium cyanate (0.020 g; 2.2 9 10-4 mol). The
reaction mixtures were refluxed in methanol (60 mL) for
4 h, then were cooled and filtered. Crystals suitable for
X-ray crystal analysis were obtained by slow evaporation of
the reaction mixtures.
Complex 1 IR (KBr): 3,054 mArH,2,053mN3;1,924m(CO/Ru–H)
1,583, 1,570; 1,479 d(C–CH in the plane); 1,433 mPh(P–Ph); 1,090
(C–CH in the plane); 742 d(C–C out of the plane); 696 d(C–C in the plane)
517 d(Ru-(H)CO)
;
d
;
.
UV–Vis (methanol; loge): 342 (1.26), 259 (sh), 201
(4.92). 1H NMR (400 MHz, CDCl3) d: 7.87–6.01 (m, PPh3),
-4.44 (t, J = 19.3 Hz, H(Ru)). 31P NMR (162 MHz, CDCl3)
d: 40.11 (d, J = 15.9 Hz, PPh3), 39.13 (s, PPh3). 13C NMR
(CDCl3) d: 206.88 (s, C:O); 134.12, 133.12, 132.16,
132.07, 131.94, 131.92, 128.57, 128.44, 128.14 (PPh3).
Complex 2 IR (KBr): 3,055 mArH; 2,235 m(CN from NCO); 1,991
m
m
(Ru–H);1,928m(CO); 1,585, 1,570, 1,478 d(C–CH in the plane);1,432
Ph(P–Ph); 1,330 m(CO from NCO)1,091 d(C–CH in the plane); 741 d(C–C
out of the plane); 692 d(C–C in the plane); 601 d(NCS); 518 d(Ru-(H)CO)
.
UV–Vis (methanol; loge): 327 (1.54), 274 (3.77), 253 (3.87),
227 (4.18), 206 (4.65). 1H NMR (400 MHz, CDCl3) d:
7.77–6.94 (m, PPh3), -7.23, -6.97 (dt, J = 24.7 Hz, 24.6 Hz,
H
(Ru)). 31P NMR (162 MHz, CDCl3) d: 40.48 (s, PPh3), 40.28
(d, J = 15.5 Hz, PPh3). 13C NMR (CDCl3) d: 206.92 (C:O),
135.81, 135.44, 135.32, 135.12, 134.04, (PPh3), 133.11 (NCO),
132.02, 129.37, 129.05, 128.48, 127.80 (PPh3).
Crystal structure determination and refinement
Physical measurements
The crystals of [RuH(N3)(CO)(PPh3)3] (1), [RuH(NCO)-
(CO)(PPh3)3] (2) were mounted in turn on an Xcalibur,
Atlas, Gemini Ultra Oxford Diffraction automatic diffrac-
tometer equipped with a CCD detector. X-ray intensity data
were collected with graphite monochromated MoKa radi-
Infrared spectra were recorded on a Perkin–Elmer spec-
trophotometer in the range 4,000–450 cm-1 using KBr
pellets. Electronic spectra were measured on a Lab Alli-
ance UV–VIS 8500 spectrophotometer in the range of
˚
ation (k = 0.71073 A) at temperature 295.0(2) K, with x
600–180 nm in methanol solution. The H, 31P, and 13C
1
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
11,968 and 7,825 strongest reflections for complexes (1)
and (2), respectively. Details concerning crystal data and
refinement are gathered in Table 1. Lorentz, polarization
and empirical absorption corrections using spherical har-
monics implemented in the SCALE3 ABSPACK scaling
algorithm [16] were applied. The structures were solved by
the Patterson method and subsequently completed by dif-
ference Fourier recycling. All the non-hydrogen atoms
were refined anisotropically using full-matrix, least-squares
techniques. Bearing in mind the limits of Fourier synthesis
and the problems in recognizing artifacts in the immediate
NMR spectra were obtained at room temperature in CDCl3
using a Bruker Avance 400 MHz spectrometer. Lumines-
cence measurements were made in ethanolic solutions on
an F-7000 FL spectrophotometer at room temperature.
Computational methods
All calculations were carried out using the Gaussian09 [9]
program. Molecular geometries of the singlet ground states
of both complexes were fully optimized in the gas phase
using the B3LYP functional [10, 11]. For each compound,
a frequency calculation was carried out, verifying that the
obtained optimized molecular structure corresponded to an
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Transition Met Chem (2013) 38:419–428
421
neighborhood of heavy atoms, it is doubtful whether a
reliable position for the hydrogen atom bound to the Ru
atom can be found in the difference Fourier map while
avoiding the danger of mistaking the effects of the series
termination errors for a true atomic position. In both
given in Table 2. The differences in calculated and
experimental spectra mainly result from the neglect of
intermolecular interactions for the gas phase. The IR
spectrum of complex (2) shows a strong C:O band and
the Ru–H stretching band at 1,928 and 1,991 cm-1
,
˚
complexes, the Ru–H bond length close to 1.60 A is nor-
respectively. In the case of complex (1), these bands are
combined and they are observed at 1,924 cm-1. Mean-
while, the calculations predict mRu–H and mCO at 2,073
(2,063) and 1,994 (2,004) cm-1, respectively, for complex
(1), with the values for complex (2) given in parenthesis. In
contrast to [RuH(NCS)(CO)(PPh3)3] for which the shift of
mCO (from 1,922 to 1,947 cm-1) is clearly visible, the
experimental values of this stretching band for complexes
(1) and (2) are comparable with the position of this band
for the parent complex [RuHCl(CO)(PPh3)3], which shows
mal. The Olex2 [17] and SHELXS97, SHELXL97 [18]
programs were used for all the calculations. Atomic scat-
tering factors were incorporated in the computer programs.
Results and discussion
Spectroscopic characterization of the complexes
The experimental and calculated IR spectra of complexes
(1) and (2) are presented in Fig. 1, and calculated and
experimental IR transitions with their assignments are
m
CO and mRu–H at 1,922 and 2,020 cm-1. In the spectrum of
complex (2), three characteristic bands are observed at
2,235, 1,330, and 601 cm-1 assigned, respectively, as the
Table 1 Crystal data and
structure refinement details of
(1)
(2)
[RuH(N3)(CO)(PPh3)3] (1),
[RuH(NCO)(CO)(PPh3)3] (2)
complexes
Empirical formula
C55H46N3OP3Ru
958.93
C56H46NO2P3Ru
958.92
Formula weight
Temperature (K)
Crystal system
Space group
295.0(2)
295.0(2)
Monoclinic
P21/n
Monoclinic
P21/c
Unit cell dimensions
˚
a (A)
26.5946(8)
12.6847(4)
27.5047(11)
90.00
12.7705(3)
14.8409(4)
25.0460(8)
90.00
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
94.681(3)
91.478(3)
90.00
90.00
3
˚
Volume (A )
9,247.6(6)
4,745.3(2)
4
Z
8
Calculated density (Mg/m3)
1.378
1.342
Absorption coefficient (mm-1
)
0.486
0.474
F(000)
3,952
1,976
Crystal dimensions (mm)
h range for data collection (ꢁ)
Index ranges
0.14 9 0.09 9 0.07
3.27–25.05
-31 B h B 31,
-12 B k B 15,
-31 B l B 32
39,799
0.17 9 0.11 9 0.07
3.47–25.05
-15 B h B 12,
-17 B k B 17,
-29 B l B 29
22,764
Reflections collected
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I [ 2r(I)]
16,321 [R(int) = 0.0430]
16,321/0/1,143
1.006
8,381 [R(int) = 0.0335]
8,381/0/572
1.048
R1 = 0.0456,
wR2 = 0.0925
R1 = 0.0768,
wR2 = 0.1015
1.007/-0.509
R1 = 0.0471,
wR2 = 0.0842
R1 = 0.0711,
wR2 = 0.0909
0.542/-0.364
R indices (all data)
Largest diff. peak and hole
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Transition Met Chem (2013) 38:419–428
1
triphenylphosphine ligands are observed in the H NMR
m
(CN), m(CO), and d(NCO) modes of the isocyanate ligand.
The same m(CN) vibration was detected for [RuH(NCS)
(CO)(PPh3)3] but with decreased wavenumber character-
istic of N-bonded isothiocyanate ligand. The strong band at
2,053 cm-1 indicates the presence of an azide ligand in
complex (1). The calculated vibrational band at
2,184 cm-1 corresponds to this stretching mode. The
stretching modes of the Ar–H are observed at 3,054 and
3,055 cm-1, for complexes (1) and (2), respectively.
spectra of the complexes. Moreover, a doublet of triplets at
-7.23, -6.97 ppm for complex (2) indicates the presence of
a hydride ligand. In the spectrum of complex (1), the hydride
ligand gives a triplet at -4.44 ppm. In general, the NMR
spectra of complexes containing both hydride and triphen-
ylphosphine ligands give rise to a doublet of triplets due to
coupling with the phosphorus atoms. However, in practice,
many of these complexes show only a triplet, as is in the
case for complex (1). The 31P NMR spectra show doublets
and singlets close to 40 ppm, arising from non-equivalent
phosphorus atoms. The 13C NMR spectra of the complexes
1
The H, 31P, and 13C NMR spectra of the complexes
were obtained at room temperature in CDCl3 (see in the
‘‘Experimental’’ section). The expected signals of the
Fig. 1 The experimental and
calculated IR spectra of
[RuH(N3)(CO)(PPh3)3] (1),
[RuH(NCO)(CO)(PPh3)3] (2)
complexes
123

Transition Met Chem (2013) 38:419–428
423
ambidentate ligands [21]. Thus, the similarity in values of
these angles for the isothiocyanate and isocyanate complexes
results from the same mode of coordination. Taking into
account the fact that N and O atoms have very similar sizes
and electronic conditions, the N-coordination mode of cya-
nate ion was tested and verified, as this model refined to a
significantly lower R-value than the model with O-coordi-
nation. The azide and isocyanate groups are almost linear,
with angles near to 178ꢁ. The Ru–N distances are compa-
rable to those in other ruthenium complexes containing
pseudohalide N-donor ligands reported in the literature
[7, 19–26]. The conformations of the complexes are stabi-
lized by intra- and intermolecular hydrogen bonds, details of
which are collected in Table 4.
Table 2 Experimental and calculated IR transitions for [RuH(N3)-
(CO)(PPh3)3] (1), [RuH(NCO)(CO)(PPh3)3] (2) complexes
Vibrational
assignments
1
2
Wavenumbers (cm-1
)
Exp
Calc
Exp
Calc
mArH
3,054
2,053
1,924
3,180
2,184
2,073
1,994
1,535
1,479
–
3,055
2,235
1,991
1,928
1,585
1,432
1,330
1,091
741
3,182
2,325
2,063
2,004
1,529
1,478
1,368
1,110
766
mN3/CN from NCO
mRuH
mCO
dC–CH in the plane
mPh(P-Ph)
1,583
1,433
–
mCO from NCO
dC–CH in the plane
dC–C out of the plane
dC–C in the plane
dNCS
1,090
742
696
–
1,110
759
711
692
710
DFT calculations
–
601
608
dRu-(H)CO
517
528
518
516
To get an insight in the electronic structures and bonding
properties of these complexes, DFT calculations were
carried out. Initially, their geometries were optimized in
singlet states using the B3LYP functional. In general, the
predicted bond lengths and angles are in agreement with
the values from the X-ray crystal structure data, and the
general trends observed in the experimental data are
reproduced in the calculations (Table 3). The largest
differences between the experimental and calculated bond
lengths are found in the Ru(1)–P(3) distances, being 0.12
show signals attributed to both the PPh3 and CO ligands.
Additionally, the spectrum of complex (2) shows a signal at
133.11 ppm ascribed to cyanate carbon.
Molecular structures
Complex (1) crystallizes in monoclinic P21/n space group
and complex (2) in monoclinic P21/c space group. In the
molecular structure of complex (1), two independent
molecules exist in the asymmetric unit. The molecular
structures of the complexes are shown in Fig. 2. Selected
bond lengths and angles are listed in Table 3. In both of the
complexes, the ruthenium centers have an octahedral
environment with distortion arising from steric hindrance
of the PPh3 ligands. The angles between the phosphine
ligands depart from the expected values of 180ꢁ and 90ꢁ by
an average of 11.4 % for complex (1) and 13.2 % for
complex (2). This deviation was also visible in the same
range in the thiocyanate analog [7].
˚
and 0.16 A. The experimental and calculated angles
between ruthenium and the azide ligand in complex (1)
or isocyanate ligand in complex (2) differ by about 10ꢁ.
Based on the optimized geometries of the complexes, a
NBO analysis was performed in order to reveal the nat-
ure of coordination between ruthenium and the various
donor atoms of the ligands. This analysis showed that the
pseudohalide donor ligands do not show covalent bond-
ing with ruthenium; the Coulomb-type interactions
between the ruthenium center and these ligands are
clearly visible in the calculated Wiberg bond indexes,
which are considerably lower than one (0.55). The Ru–P
bond orders are also less than 1 and close to 0.70 for the
PPh3 ligands in mutually trans conformation and 0.55 for
the triphenylphosphines in cis positions. This low value
is connected with the trans effect exerted by the hydride
ligand. The NBO analysis (Second Order Perturbation
Theory Analysis of Fock Matrix in NBO Basis) also
shows that the contributions from the azide and isocya-
nate ligands to the ruthenium centers have similar values
close to 250 kcal/mol, while the back donations are equal
to 42.9 and 40.5 kcal/mol in complexes (1) and (2),
respectively. There are no significant differences in these
energy values compared to those calculated for the
thiocyanate analog.
Complexes (1) and (2), like [RuH(NCS)(CO)(PPh3)3], are
analogs of [RuHCl(CO)(PPh3)3] in which a chloride ligand
is replaced by one of the bulkier pseudohalide ligands. In
these complexes, the hydride ligand is trans to the equatorial
triphenylphosphine. The trans effect of the hydride ligand is
reflected in a slight elongation of the Ru(1)–P(3) bond
lengths in relation to the bonds Ru(1)–P(1), Ru(1)–P(2) in all
˚
of the studied complexes by an average of 0.12 A. The N–
N–Ru angles in the azide complex significantly deviate from
linearity, as observed previously for the other ruthenium(II)
azide complexes [19, 20]. The Ru–N–C angles for cyanate
analogs range between 150ꢁ and 170ꢁ, which indicates
that the mode of coordination is via nitrogen for these
123

424
Transition Met Chem (2013) 38:419–428
Fig. 2 Molecular structures of
[RuH(N3)(CO)(PPh3)3] (1),
[RuH(NCO)(CO)(PPh3)3] (2)
complexes. Hydrogen atoms
(bonding with carbons) are
omitted for clarity
123

Transition Met Chem (2013) 38:419–428
˚
425
Table 3 Selected bond lengths (A) and angles (ꢁ) for [RuH(N3)(CO)(PPh3)3] (1), [RuH(NCO)(CO)(PPh3)3] (2) complexes with the optimized
geometry values
[RuH(N3)(CO)(PPh3)3]
[RuH(NCO)(CO)(PPh3)3]
Exp
Exp
Exp
Calc
Calc
˚
Bond lenghts (A)
Ru(1)–C(1)
1.855(4)
Ru(2)–C(61)
Ru(2)–N(61)
Ru(2)–P(61)
Ru(2)–P(62)
Ru(2)–P(63)
Ru(2)–H(2)
O(61)–C(61)
N(61)–N(62)
N(62)–N(63)
1.896(4)
1.868
Ru(1)–C(1)
Ru(1)–N(1)
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–P(3)
Ru(1)–H(1)
O(1)–C(1)
N(1)–C(2)
O(2)–C(2)
1.834(4)
1.862
Ru(1)–N(1)
2.124(3)
2.3868(9)
2.3605(9)
2.5073(9)
1.48(3)
2.079(3)
2.3538(10)
2.4020(10)
2.4950(10)
1.63(3)
2.168
2.464
2.456
2.622
1.597
1.167
1.209
1.161
2.099(3)
2.3970(9)
2.3516(10)
2.4857(9)
1.57(3)
2.140
2.457
2.442
2.646
1.597
1.166
1.198
1.202
Ru(1)–P(1)
Ru(1)–P(2)
Ru(1)–P(3)
Ru(1)–H(1)
O(1)–C(1)
1.146(4)
1.187(4)
1.161(4)
1.127(4)
1.101(5)
1.248(7)
1.161(4)
1.140(5)
1.208(5)
N(1)–N(2)
N(2)–N(3)
Angles
O(1)–C(1)–Ru(1)
C(1)–Ru(1)–N(1)
C(1)–Ru(1)–P(1)
C(1)–Ru(1)–P(2)
C(1)–Ru(1)–P(3)
N(1)–Ru(1)–P(1)
N(1)–Ru(1)–P(2)
N(1)–Ru(1)–P(3)
P(2)–Ru(1)–P(1)
P(1)–Ru(1)–P(3)
P(2)–Ru(1)–P(3)
C(1)–Ru(1)–H(1)
N(1)–Ru(1)–H(1)
P(1)–Ru(1)–H(1)
P(2)–Ru(1)–H(1)
P(3)–Ru(1)–H(1)
N(2)–N(1)–Ru(1)
N(3)–N(2)–N(1)
171.9(3)
O(61)–C(61)–Ru(2)
C(61)–Ru(2)–N(61)
C(61)–Ru(2)–P(61)
C(61)–Ru(2)–P(62)
C(61)–Ru(2)–P(63)
N(61)–Ru(2)–P(61)
N(61)–Ru(2)–P(62)
N(61)–Ru(2)–P(63)
P(61)–Ru(2)–P(62)
P(61)–Ru(2)–P(63)
P(62)–Ru(2)–P(63)
C(61)–Ru(2)–H(2)
N(61)–Ru(2)–H(2)
P(61)–Ru(2)–H(2)
P(62)–Ru(2)–H(2)
P(63)–Ru(2)–H(2)
N(62)–N(61)–Ru(2)
N(61)–N(62)–N(63)
160.0(4)
176.06
176.53
85.40
88.08
99.97
93.99
91.18
83.50
156.74
101.78
101.33
90.40
86.13
79.27
78.49
169.62
122.30
177.07
O(1)–C(1)–Ru(1)
C(1)–Ru(1)–N(1)
C(1)–Ru(1)–P(1)
C(1)–Ru(1)–P(2)
C(1)–Ru(1)–P(3)
N(1)–Ru(1)–P(1)
N(1)–Ru(1)–P(2)
N(1)–Ru(1)–P(3)
P(2)–Ru(1)–P(1)
P(1)–Ru(1)–P(3)
P(2)–Ru(1)–P(3)
C(1)–Ru(1)–H(1)
N(1)–Ru(1)–H(1)
P(1)–Ru(1)–H(1)
P(2)–Ru(1)–H(1)
P(3)–Ru(1)–H(1)
C(2)–N(1)–Ru(1)
N(1)–C(2)–O(2)
176.9(3)
178.04
175.57
97.63
94.65
88.97
82.22
83.82
95.40
154.33
101.32
101.36
86.39
89.23
79.71
78.66
175.35
158.31
177.58
172.63(13)
85.08(11)
86.10(11)
100.89(11)
95.56(8)
90.76(8)
86.25(8)
158.43(3)
99.82(3)
101.16(3)
90.9(11)
81.9(11)
82.6(12)
77.9(12)
168.1(11)
123.2(2)
178.6(4)
174.04(17)
92.10(13)
100.05(12)
88.07(14)
85.22(10)
80.71(10)
97.67(9)
156.60(3)
101.37(3)
98.97(3)
86.6(11)
87.7(11)
80.5(11)
80.3(11)
174.4(11)
143.2(4)
167.0(6)
174.33(14)
98.66(11)
93.76(11)
89.47(11)
81.66(9)
83.52(9)
95.96(9)
151.18(3)
103.87(3)
102.14(3)
88.8(12)
85.7(12)
78.8(12)
75.5(12)
177.0(12)
167.3(3)
178.4(6)
Table 4 Hydrogen bonds for [RuH(N3)(CO)(PPh3)3] (1), [RuH(N-
˚
The interactions between the ligands and central metal
can be characterized by the calculated natural charges on the
metal, whose values are significantly lower than the formal
oxidation state. These natural charges are equal to -1.070
(1) and -1.076 (2), indicating that the donations from the
ligands to the metal are greater than the back donations from
the metal to ligands. The same situation was observed in the
case of [RuH(SCN)(CO)(PPh3)3] (natural charge on the
ruthenium was -1.088). The calculated natural charges of
the hydride ligands are both ?0.09, and the Wiberg indices of
the Ru–H bonds are close to 0.75. The charges on the car-
bonyl group, calculated by summing the individual charges
on the carbon and oxygen, are ?0.16 and ?0.19 for com-
plexes (1) and (2), respectively. The Wiberg indexes of the
CO bonds in the complexes are reduced by about 0.23 with
respect to free CO (WCO = 2.23).
CO)(CO)(PPh3)3] (2) complexes (A and ꢁ)
D-H…A
d(D–H) d(H…A) d(D…A) \(DHA)
[RuH(N3)(CO)(PPh3)3]
C(7)–H(7)…N(2)
C(43)–H(43)…N(1)
C(79)–H(79)–N(61)
0.93
0.93
0.93
2.49
2.36
2.49
2.49
3.241(5) 137.6
3.191(5) 148.1
3.223(5) 135.4
3.228(5) 136.0
C(111)–H(111)…N(61) 0.93
[RuH(NCO)(CO)(PPh3)3]
C(4)–H(4)…N(1)
0.93
0.93
0.93
0.93
2.58
2.53
2.49
2.57
3.278(5) 132.7
3.316(5) 142.9
3.154(6) 128.4
3.212(5) 126.5
C(34)–H(34)…N(1)
C(37)–H(37)…O(2)#1
C(50)–H(50)…N(1)
Symmetry transformations used to generate equivalent atoms: #1: -x,
-1/2 ? y, 1/2 - z
123

426
Transition Met Chem (2013) 38:419–428
Analysis of the frontier molecular orbitals is useful for
ligands (84, 79 %) with antibonding participation of
13–18 % dRu orbitals. In the case of the azide complex, the
contribution of the PPh3 orbitals to the LUMO is higher
compared to the isocyanate analog and the recently reported
complex [RuH(NCS)(CO)(PPh3)3]. At higher unoccupied
orbitals LUMO ? 18—LUMO ? 21 (0.38–1.18 eV for
complex (1) and 0.51–1.44 eV for complex (2)), the par-
ticipation of ruthenium d orbitals is in the range of 16–29
and 12–23 % for complexes (1) and (2), respectively. The p*
orbitals of the carbonyl groups have significant contributions
to LUMO ? 18—LUMO ? 21, in the range of 11–49 and
24–68 % for complexes (1) and (2), respectively. In the
OPDOS plots of the complexes, the antibonding interactions
between the pseudohalide ligands and ruthenium(II) center
in the HOMO and HOMO-1 orbitals are visible. The
understanding the spectroscopic properties such as elec-
tronic absorption and emission spectra. The DOS and
overlap population density-of-states (OPDOS) in term of
Mulliken population analysis were calculated using the
GaussSum program, and Fig. 3 presents the compositions
of the fragment orbitals contributing to the molecular
orbitals of the complexes. In the HOMO’s, the azide or
isocyanate ligands play a significant role, contributing with
73 and 51 %, respectively, and the contribution from the
dRu orbitals is 18 and 29 % in complexes (1) and (2),
respectively. For the thiocyanate analog, a greater share of
thiocyanate ligand with a decline in contribution of dRu
orbitals was found in the HOMO. For complexes (1) and
(2), the LUMOs are localized on the triphenylphosphine
Fig. 3 The density-of-states diagrams and overlap partial DOS for interactions between ruthenium central ions and ligands in the complex
[RuH(N3)(CO)(PPh3)3] (1), [RuH(NCO)(CO)(PPh3)3] (2)
123

Transition Met Chem (2013) 38:419–428
427
Table 5 The electronic transitions for the complexes calculated with B3LYP functional by the TD-DFT method
Wavelength (nm)
f
Transitions
Exp (nm)
1
377.15
336.63
292.09
262.03
256.74
250.72
245.69
2
0.1125
0.0346
0.0037
0.0191
0.0191
0.0024
0.0138
HOMO ? LUMO (62 %), HOMO ? L ? 1 (26 %)
H-2 ? LUMO (44 %), H-1 ? LUMO (14 %), HOMO ? L ? 1 (10 %)
HOMO ? L ? 8 (88 %)
342
259
HOMO ? L ? 15 (41 %), HOMO ? L ? 18 (25 %)
H-2 ? L ? 8 (59 %)
H-1 ? L ? 9 (64 %)
H-2 ? L ? 10 (54 %)
356.95
347.01
331.60
271.88
248.15
232.24
0.1214
0.0019
0.0012
0.1127
0.0146
0.0064
H-1 ? LUMO (70 %)
HOMO ? LUMO (82 %)
H-2 ? LUMO (73 %)
327
274
253
H-3 ? LUMO (43 %), H-2 ? L ? 2 (11 %), H-2 ? L ? 3 (13 %)
HOMO ? L ? 16 (42 %)
H-2 ? L ? 13 (11 %), H-2 ? L ? 14 (29 %)
strengths of the calculated transitions are presented in
Fig. 4. From the calculated electronic structures, it appears
that the HOMOs are localized on pseudohalide ligand p
orbitals with admixture of the ruthenium d orbitals. How-
ever, the phosphine ligands are the main contributors to the
LUMOs with addition of ruthenium orbitals. Taking into
account the electronic structures of the complexes, the
bands at 342 for complex (1) and at 327 nm for complex
(2) have been attributed to MLLCT with admixture of d–d
character. The bands observed at 259 and 274, 253 nm
have been assigned to intra- and interligand pCb 6H6
À
!
3dphosphorus and p ! pC¼CÞ transitions with admixture of
ꢀ
from transitions in the PPh3 ligands.
ꢁ
MLCT transitions dRu ! pꢁNꢂligand and dRu ! pPꢁh . The
highest experimental bands close to 210 nm may result
Fig. 4 Experimental and calculated electronic absorption spectra and
oscillator strength of calculated transitions for complex [RuH(N-
CO)(CO)(PPh3)3] (2)
Fluorescence spectra of the complexes have been mea-
sured at room temperature in ethanolic solutions with the
concentration of 1 9 10-3 mol/dm3. The solutions of the
complexes were excited at wavelengths corresponding to
the first transitions of the complexes. The complexes do not
show emission properties, in contrast to the isothiocyanate
analog. The lack of emissions in the isocyanate and azide
complexes is probably connected with the smaller impact
of NCO- and N3- on the frontier HOMOs than was found
for the isothiocyanate.
combination of the carbonyl ligands and ruthenium d orbi-
tals to the HOMO orbitals has positive value indicating the
bonding character of these interactions.
Experimental and theoretical electronic spectra
The theoretical absorption spectra of the complexes were
obtained from the calculations of the singlet excited states
by TD-DFT. Computation of 100 excited states allowed for
the interpretation of the experimental spectra. The selected
excited states assigned to the absorption bands are shown
in Table 5. Complex (1) shows experimental maxima at
342, 259, and 201 nm, while complex (2) has maxima
at 327, 274, 253, 227, and 206 nm. The experimental
and calculated spectra of complex (2) with the oscillator
Conclusions
Two new complexes of ruthenium with azide and isocya-
nate ligands were synthesized and characterized as a con-
tinuation of previous studies on pseudohalide hydride
123

428
Transition Met Chem (2013) 38:419–428
7. Małecki JG (2010) Polyhedron 29:2489
8. Ahmad N, Levinson JJ, Robinson SD, Uttely MF (1974) Inorg
Synth 15:48
carbonyl ruthenium(II) complexes. Electronic structures of
the complexes have been determined by DFT, allowing
analysis of the UV–Vis spectra. We conclude that the
differences in the electronic structures of the present
complexes and the previously reported isothiocyanate
analog have major influences on their spectroscopic prop-
erties and determine their ability of fluorescence. Hence,
variation of the pseudohalide ligands may allow for
intentional modification of the spectroscopic properties of
such complexes.
9. 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,
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
Supplementary data
CCDC 871975 and CCDC 910264 contain the supplemen-
tary crystallographic data for the complexes [RuH(N3)(-
CO)(PPh3)3] (1), [RuH(NCO)(CO)(PPh3)3] (2). These data
can be obtained free of charge via http://www.ccdc.cam.ac.
uk/conts/retrieving.html or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: ?44-1223-336033; or e-mail: deposit@ccdc.cam.
ac.uk.
10. Becke AD (1993) J Chem Phys 98:5648
11. Lee C, Yang W, Parr RG (1988) Phys Rev B 37:785
12. Eichkorn K, Weigend F, Treutler O, Ahlrichs R (1997) Theor
Chim Acc 97:119
13. 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
14. Glendening ED, Reed AE, Carpenter JE, Weinhold F NBO
(version 3.1)
15. O’Boyle NM, Tenderholt AL, Langner KM (2008) J Comp Chem
29:839
16. CrysAlis RED, Oxford Diffraction Ltd., Version 1.171.36.24
(2012)
17. Dolomanov OV, Bourhis LJ, Gildea RJ, Howard JAK, Pusch-
mann H (2009) J Appl Cryst 42:339
18. Sheldrick GM (2008) Acta Cryst A 64:112
Acknowledgments The GAUSSIAN-09 calculations were carried
out in the Wrocław Centre for Networking and Supercomputing,
WCSS, Wrocław, Poland, http://www.wcss.wroc.pl, under calcula-
tional Grant No. 18.
´
19. Małecki JG, Maron A (2012) Polyhedron 31:44
References
20. Singh KS, Kreisel KA, Yap GPA, Kollipara MR (2006) J Or-
ganomet Chem 691:3509
1. Kannan S, Sivagamasundari M, Ramesh R, Liu Yu (2008) J
Organomet Chem 693:2251
2. Sivagamasundari M, Ramesh R (2007) Spectrochim Acta, Part A
67:256
21. Nagao H, Ooyama D, Hirano T, Naoi H, Shimada M, Sasaki S,
Nagao N, Mukaida M, Oi T (2001) Inorg Chim Acta 320:60
22. Homanen P, Haukka M, Pakkanen TA, Pursiainen L, Laitinen RH
(1996) Organometallics 15:4081
3. Sivagamasundari M, Ramesh R (2007) Spectrochim Acta, Part A
66:427
4. Kaveri MV, Prabhakaran R, Karvembu R, Natarajan K (2005)
Spectrochim Acta, Part A 61:2915
5. Raja MU, Gowri N, Ramesh R (2010) Polyhedron 29:1175
6. Coe BJ, Glenwright SJ (2000) Coord Chem Rev 203:5
23. Yadav M, Singh AK, Maiti B, Pandey DS (2009) Inorg Chem
48:7593
24. Małecki JG (2010) Polyhedron 29:1973
25. Małecki JG (2010) Polyhedron 29:1237
´
26. Małecki JG, Maron A (2012) Trans Met Chem 37:727
123