Novel oxorhenium(V) complexes of 8-hydroxyquinoline derivatives-Synthesis, spectroscopic characterization, X-ray crystal structures and DFT calculations

Article abstract of DOI:10.1016/j.poly.2012.12.028

Two modifications of 8-hydroxyquinoline framework, namely 5,7-dichloro-2-[2-(2-chlorophenyl)vinyl]quinoline-8-ol (HL₁) and 2-[2-(3,4-dichlorophenyl)vinyl] quinoline-8-ol (HL₂) have been synthesized and their interaction with [ReOX₃(PPh₃) ₂] (X = Cl, Br) have been examined. HL₁ and HL₂ react with [ReOX₃(PPh₃)₂] to give [ReOCl ₂(L₁)(PPh₃)]₂·MeCN (1), [ReOBr₂(L₁)(PPh₃)] (2), [ReOCl ₂(L₂)(PPh₃)] (3) and [ReOBr₂(L ₂)(PPh₃)] (4). The complexes have been characterized spectroscopically and structurally. The experimental studies on 1 and 3 have been accompanied by DFT calculations, and additional information about binding between the rhenium atom and oxo ligand has been obtained by NBO analysis. The X-ray studies and NBO analysis confirm a triple bond between the rhenium and the terminal oxo ligand. The L₁ and L₂ ligands coordinate in a chelate way via N- and O-donor atoms, and the oxygen donor of the chelate ligand is located trans to the terminal oxo (O_t) group due to a strong trans-influence of O_t ligand. DFT and TD-DFT calculations applied to 1 and 3 resulted in appropriate prediction of the UV-Vis spectra and enabled a detailed assignment of the electronic transitions to the experimental absorptions.

Full text of DOI:10.1016/j.poly.2012.12.028

Polyhedron 51 (2013) 263–274
Contents lists available at SciVerse ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Novel oxorhenium(V) complexes of 8-hydroxyquinoline derivatives – Synthesis,
spectroscopic characterization, X-ray crystal structures and DFT calculations
⇑
B. Machura , M. Wolff, W. Cie s´ lik, R. Musioł
Department of Crystallography, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
Department of Organic Chemistry, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
a r t i c l e i n f o
a b s t r a c t
Article history:
Two modifications of 8-hydroxyquinoline framework, namely 5,7-dichloro-2-[2-(2-chloro-
Received 17 October 2012
Accepted 23 December 2012
Available online 17 January 2013
phenyl)vinyl]quinoline-8-ol (HL
synthesized and their interaction with [ReOX
1
) and 2-[2-(3,4-dichlorophenyl)vinyl] quinoline-8-ol (HL
(PPh ] (X = Cl, Br) have been examined. HL and HL
)] (L )(PPh )] (2), [ReOCl (L )(PPh
ꢀMeCN (1), [ReOBr
2
) have been
3
)
3 2
1
2
react
)] (3)
with [ReOX
and [ReOBr
3
(PPh
3
)
2
] to give [ReOCl
2
(L
1
)(PPh
3
2
2
1
3
2
2
3
2
(L )(PPh
2
3
)] (4). The complexes have been characterized spectroscopically and structurally.
Keywords:
Oxorhenium(V) complexes
The experimental studies on 1 and 3 have been accompanied by DFT calculations, and additional infor-
mation about binding between the rhenium atom and oxo ligand has been obtained by NBO analysis.
The X-ray studies and NBO analysis confirm a triple bond between the rhenium and the terminal oxo
8
-Hydroxyquinoline
X-ray crystal structure
Electronic structure
DFT and TDDFT calculations
NBO analysis
ligand. The L
1
and L
2
ligands coordinate in a chelate way via N- and O-donor atoms, and the oxygen donor
) group due to a strong trans-influence of O
of the chelate ligand is located trans to the terminal oxo (O
t
t
ligand. DFT and TD-DFT calculations applied to 1 and 3 resulted in appropriate prediction of the UV–Vis
spectra and enabled a detailed assignment of the electronic transitions to the experimental absorptions.
Ó 2013 Elsevier Ltd. All rights reserved.
1
. Introduction
Compounds containing a quinoline moiety constantly attract
obvious that promising contributions are expected from the coor-
dination chemistry and organometallic chemistry which supplies
novel methods and compounds for the radiopharmaceutical com-
munity [13–16]. In this context, the design, synthesis and reactiv-
ity of the rhenium complexes, especially oxocompounds, has
become the aim of several laboratories, including ours.
the interest of chemist and pharmacist because of their well known
and remarkable applications as complexing agents and biological
activity [1]. Quinoline is an important heterocyclic contained in
various classes of pharmacological agents that can play an impor-
tant role in biochemical processes [2,3]. A number of compounds
incorporating quinoline have been clinically used as antifungal,
antibacterial and antiprotozoic drugs [4–7] as well as antitubercul-
otic agents [8–10]. Some quinoline analogs showed also antineo-
plastics activity [11]. Styrylquinolines having therapeutic activity
against HIV integrase and FZ41 is an example of such a compound
The main aim of the current study was to obtain chloro substi-
tuted derivatives of 2-styrylquinoline and examine their reactivity
towards [ReOX
phenyl)vinyl]quinolin-8-ol (HL
of 5,7-dichloro-8-hydroxyquinaldine with 2-chorobenzaldehyde,
whereas 2-[2-(3,4-dichlorophenyl)vinyl]quinoline-8-ol (HL ) is a
3
3
(PPh )
2
] (X = Cl, Br). 5,7-Dichloro-2-[2-(2-chloro-
1
) was obtained by condensation
2
product of reaction of 8-hydroxyquinaldine with 3,4-dichlorobenz-
aldehyde in acetic acid anhydride. The compounds differ in num-
ber and location of chloro substituents (Scheme 1).
[
12].
Since biologically active compounds frequently act via chela-
tion, their interaction with metal ions is a subject of considerable
In the next stage, the reactions of 2-styrylquinoline derivatives
ꢁ
186
interest. The introduction of
1.07 MeV b-emitter, t1/2 = 90 h) and
1/2 = 17 h) in radiotherapy and success of the
b
emitting isotopes
Re
with [ReOX
oxocompounds [ReOCl
(2), [ReOCl (L )(PPh )] (3) and [ReOBr
3
(PPh
3
)
2
] (X = Cl, Br) were examined and four novel
(L )(PPh )] (L )(PPh )]
ꢀMeCN (1), [ReOBr
(L )(PPh )] (4) were
188
(
t
Re (2.12 MeV b-emitter,
2
1
3
2
2
1
3
186
Re(Sn)HEDP
2
2
3
2
2
3
radiopharmaceutical as a palliative of bone pain has reawakened
scientific interest in the coordination chemistry of rhenium. There
is a need for new approaches and new labeling procedures. It is
obtained. To determine molecular structures of the complexes X-
ray and spectroscopic (IR, NMR) studies were carried out. Density
functional theory (DFT) and time-dependent DFT (TD-DFT) calcula-
tions were performed for 1 and 3 to get detailed insight into the
electronic structure and spectroscopic properties of the rhenium
compounds. Recently, the DFT methods have successfully been ap-
plied to study very large systems due to their good compromise
⇑
Corresponding author at: Department of Crystallography, Institute of Chemis-
try, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland.
E-mail address: basia@ich.us.edu.pl (B. Machura).
0
277-5387/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2012.12.028

2
64
B. Machura et al. / Polyhedron 51 (2013) 263–274
Cl
134.81, 133.99, 133.57, 132.06, 131.14, 130.83, 130.44, 128.27,
28.17, 127.85, 124 37, 123.01, 119.63, 116.28 ppm.
1
Cl
N
2
(HL
.3. Preparation of 2-[2-(3,4-dichlorophenyl)vinyl]quinoline-8-ol
2
)
N
OH
Cl
Cl
OH
Cl
HL
1
HL
2
To a solution of 8-hydroxyquinaldine (2.5 mmol) in acetic anhy-
dride (10 ml) was added 2 equiv. of 3,4-dichlorobenzaldehyde. The
mixture was heated and stirred under inert gas atmosphere (N )
2
Scheme 1.
during 20 h at 120 °C, and then it was cooled down to 0 °C,
and the precipitate was filtered off. The solid was crystallized
between computational cost, coverage, and accuracy of results and
have significantly contributed to the characterization of transition
metal complexes. Gancheff and co-workers have performed ex-
tended tests of the ability of different DFT methods, including
B3LYP with LANL2DZ basis set, for rhenium compounds in a geom-
etry optimization and bond nature. Although LANL2DZ is not a very
extended basis set, its use with B3LYP has shown to be sufficient
for the geometry optimization and calculation of spectral proper-
ties. It gives good agreement with the experimental data and its
use is justified in the case of large molecules [17].
from ethanol. It gave yellow crystals. Yield: 96.9%, m.p. 140 °C,
+
m/z = 317.32 [M+2H] ; HPLC purity 98.48%; UV (nm), kmax/log
e
:
1
2
93.7/3.53. H NMR (400 MHz, DMSO-d
6
): d = 8.44 (d, J = 8.6 Hz,
1
H), 8.07 (d, J = 1.7 Hz, 1 H), 7.87 (d, J = 8.5 Hz, 2 H), 7.82–7.73
(
m, 2 H), 7.70 (d, J = 8.4 Hz, 1 H), 7.59 (d, J = 6.5 Hz, 1 H), 7.58–
.51 (m, 2 H). C NMR (100 MHz, DMSO-d ): d = 169.87, 155.25,
6
47.59, 140.85, 137.47, 137.31, 132.35, 132.17, 131.36, 131.22,
29.42, 128.80, 127.89, 126.65, 126.12, 122.28, 121.39.
1
3
7
1
1
2
.4. Preparation of [ReOCl
(L
2 1
)(PPh )]
3 2
MeCN (1)
Additional information about bonding between the rhenium
atom and oxo ligand in [ReOCl
has been obtained by NBO analysis [18].
2 1 3 2 2 3
(L )(PPh )] and [ReOCl (L )(PPh )]
A mixture of [ReOCl
0.23 g, 0.66 mmol) was refluxed in acetonitrile (80 ml) for 6 h.
3
(PPh
3 2 1
) ] (0.50 g, 0.60 mmol) and HL
(
The resulting red-brown solution was left to slow evaporation
and dark red crystals were obtained after few days. Yield 70%.
2
. Experimental
.1. General procedure
3 2
The [ReOX (PPh ) ] X = Cl, Br complexes were prepared accord-
51 3 4 2 2
Anal. Calc. C72H N O Cl10P Re : C, 47.75; H, 2.84; N, 2.32.
Found: C, 47.63; H, 2.90; N, 2.28%. IR (KBr): 1625(m), 1591(m),
2
ꢁ
1
1
1
(
548(m)
400 MHz, DMSO-d
J = 16.1 Hz, 1 H); 8.01 (t, J = 8.04 Hz, 1 H); 7.95 (d, J = 8.2 Hz,
H); 7.78 (s, 1 H), 7.65–7.53 (m, 17 H), 7.45–7.37 (m, 2 H) ppm.
m
(C@N) and
m
(C@C); 974(s) cm
m(Re@O). H NMR
6
): d = 8.51 (d, J = 8.6 Hz, 1 H); 8.38 (d,
3
ing to the literature methods [19]. Styrylquinolines were obtained
according to modified literature method [20], and reactions were
performed in a laboratory microwave reactor CEM Discovery or
on Magnetic stirrer MR Hei-Standard Heidolph. The other reagents
used to the synthesis were commercially available and used with-
out further purification. TLC experiments were performed on alu-
mina-backed silica gel 60 F254 plates (Merck, Darmstadt,
Germany). The plates were illuminated under UV (254 nm). Melt-
ing point was measured on a Thermo-scientific 9100 apparatus.
IR spectra were recorded on a Nicolet Magna 560 spectrophotom-
1
2 1 3
2.5. Preparation of [ReOBr (L )(PPh )] (2)
A procedure similar to that for 1 was used with [ReOBr
0.50 g, 0.52 mmol) and HL (0.198 g, 0.57 mmol). Crystalline pre-
cipitate of 2 was collected in 63% yield.
Anal. Calc. C35 PCl Br Re: C, 43.16; H, 2.48; N, 1.44.
Found: C, 42.98; H, 2.56; N, 1.32%. IR (KBr;
1626(m), 1593(m), 1549(m) (C@N) and
(Re@O). H NMR (400 MHz, DMSO-d
3 3 2
(PPh ) ]
(
1
H24NO
2
3
2
ꢁ
1
m
/cm ): IR (KBr):
ꢁ1
ꢁ1
m
m
(C@C); 972(s) cm
eter in the spectral range 4000–400 cm with the samples in the
form of KBr pellets. Electronic spectra were measured on a spectro-
photometer Lab Alliance UV–Vis 8500 in the range 1100–180 nm
1
m
6
): d = 8.52 (d, J = 8.8 Hz, 1
H); 8.37 (d, J = 16.1 Hz, 1 H); 8.00 (d, J = 8.8 Hz, 1 H); 7.95 (d,
J = 6.5 Hz, 1 H); 7.78 (s, 1 H); 7.65–7.53 (m, 17 H), 7.48–7.39 (m,
1
in methanol solution. H NMR spectra were recorded on a Bruker
3
ꢁ1
ꢁ1
AM-500 (500 MHz for 1H), and 13C NMR spectra were recorded
on a Bruker AM-400 (100 MHz) instrument (Bruker Bio-Spin Corp.,
Germany). Chemicals shifts are reported in ppm (d) with reference
2 H) ppm. UV–Vis (CH OH; k
max
[nm] (
e
; [dm mol cm ])):
3
6
72.2 (670); 443.6 (2750); 317.4 (21380); 208 (69550).
2 2 3
2.6. Preparation of [ReOCl (L )(PPh )] (3)
3 4
to internal Si(CH ) , when diffused easily exchangeable signals are
omitted. MS spectra were obtained on a mass spectrometer Varian
HPLC MS (ESI).
A procedure similar to that for 1 was used with [ReOCl
0.50 g, 0.60 mmol) and HL (0.21 g, 0.66 mmol). Crystalline pre-
cipitate of 3 was collected in 74% yield.
Anal. Calc. C35 NO PRe: C, 49.42; H, 2.96; N, 1.65%. Found:
C, 49.32; H, 2.99; N, 1.71%. IR (KBr): 1626(m), 1601(m), 1558(s)
3 3 2
(PPh ) ]
(
2
2.2. Preparation of 5,7-dichloro-2-[2-(2-chlorophenyl)vinyl]quinoline-
-ol (HL
H25Cl
4
2
8
1
)
ꢁ1
1
m(C@N) and
m(C@C); 965(s) cm
m(Re@O). H NMR (400 MHz,
5
,7-Dichloro-8-hydroxyquinaldine (1.0 mmol) was mixed thor-
6
DMSO-d ): d = 8.19 (d, J = 2.2 Hz, 2 H), 7.74 (d, J = 8.3 Hz, 1H),
oughly with 4 equiv. of 2-chorobenzaldehyde, put in an open ves-
sel and exposed to microwave irradiation for 10 min. at 180 °C and
7.71 (s, 1H), 7.67–7.59 (m, 2H), 7.57–7.53 (m, 2H), 7.51–7.40 (m,
2H), 7.37–7.29 (m, 8H), 7.28–7.19 (m, 7H) ppm.
5
0 W. The reaction mixture was cool down to 0 °C, and the precip-
itate was filtered off. The solid was crystallized from ethanol. It
2 2 3
2.7. Preparation of [ReOBr (L )(PPh )] (4)
gave beige crystals. Yield: 47%, m.p. 205-210 °C. m/z = 348.27
ꢁ
1
[
M] ; HPLC purity 98.74%; UV (nm), kmax/log
NMR (400 MHz, DMSO-d ): d = 8.48 (d, J = 8.7 Hz, 1 H); 8.36 (d,
J = 16.2 Hz, 1 H); 7.98 (d, J = 8.8 Hz, 1 H); 7.94 (dd, J = 7.6, 2.0 Hz,
H); 7.77 (s, 1 H); 7.58–7.50 (m, 2 H); 7.47–7.36 (m, 2 H) ppm.
e
: 319.9/3.61.
H
A procedure similar to that for [ReOCl
with [ReOBr (PPh (0.50 g, 0.52 mmol) and HL
0.57 mmol). Crystalline precipitate of 4 was collected in 69% yield.
Anal. Calc. C35 Cl NO PRe: C, 48.40; H, 2.90; N, 1.61%.
Found: C, 48.27; H, 2.95; N, 1.65%. IR (KBr): 1627(m), 1555(m)
2
(L
1
)(PPh
3
)
2
] was used
6
3
3
)
2
]
2
(0.18 g,
1
H
25Br
2
2
2
1
3
C
6
NMR (100 MHz, DMSO-d ): d = 155.17, 149.33, 139.39,

B. Machura et al. / Polyhedron 51 (2013) 263–274
265
(C@C); 968(s) cm 1
ꢁ
m
(Re@O). 1H NMR (400 MHz,
the B3LYP hybrid exchange–correlation functional [25,26]. The cal-
culations were performed using ECP LANL2DZ basis set with addi-
m
(C@N) and
m
DMSO-d
6
): d = 8.22 (d, J = 3.2 Hz, 2H), 7.74 (d, J = 2.1 Hz, 1 H),
7
.70 (d, J = 1.9 Hz, 1 H), 7.66–7.60 (m, 2H), 7.58–7.53 (m, 2H),
tional
d (with exponent a = 0.3811) and f (with exponent
7
.46–7.42 (m, 2H), 7.37–7.29 (m, 8H), 7.27–7.20 (m, 7H) ppm.
a
= 2.033) functions for the rhenium and the standard 6-31G basis
3
ꢁ1
ꢁ1
UV–Vis (CH
4
3
OH; kmax [nm] (e; [dm mol cm ])): 658.2 (310);
set for the other atoms. For chlorine, oxygen and nitrogen atoms,
diffuse and polarization functions were added [27–29]. All the cal-
culated vibrational frequencies are real and positive, indicating
that the optimized structure represents real minima of the ground
state potential energy surface.
34.0 (795); 343.8 (7190); 303.8 (9450); 207.0 (27490).
2.8. Crystal structure determination and refinement
The electronic spectra of [ReOCl
2 1 3 2 2
(L )(PPh )] and [ReOCl (L )
The X-ray intensity data of 1–4 were collected on a Gemini A Ul-
(
PPh )] were calculated with the TDDFT method and the solvent ef-
3
tra diffractometer equipped with Atlas CCD detector and graphite
monochromated Mo K radiation (k = 0.71073 Å) at room temper-
fect (methanol) was simulated using the polarizable continuum
model (PCM) [30]. For both complexes, 120 singlet–singlet spin-al-
lowed excitations in solution were taken into account.
Natural bond orbital (NBO) calculations were performed with
the NBO code [31] included in GAUSSIAN-09. Each natural bond
a
ature. Details concerning crystal data and refinement are given in
Table 1. Lorentz, polarization and empirical absorption correction
using spherical harmonics implemented in SCALE3 ABSPACK scal-
ing algorithm [21] were applied. The structures were solved by
the Patterson method and subsequently completed by the differ-
ence Fourier recycling. All the non-hydrogen atoms were refined
anisotropically using full-matrix, least-squares technique. The
hydrogen atoms were treated as riding on their parent carbon
atoms and assigned isotropic temperature factors equal 1.2 (non-
methyl) times the value of equivalent temperature factor of the
parent atom. SHELXS97 and SHELXL97 [22,23] programs were used
for all the calculations. Atomic scattering factors were those incor-
porated in the computer programs.
orbital (NBO)
hybrids (NHOs) h
r
AB can be written in terms of two directed valence
and h on atoms A and B:
A
B
a
AB ¼ c
A
h
A
þ c
B B
h
where
r
A
and r are polarization coefficients. Each valence
B
bonding NBO must in turn be paired with a corresponding valence
antibonding NBO:
ꢂ
a
¼ c
B
h
A
þ c
A B
h
AB
to complete the span of the valence space. The Lewis-type (do-
2
.9. Computational details
nor) NBOs are thereby complemented by the non-Lewis-type
acceptor) NBOs that are formally empty in an idealized Lewis pic-
(
´
The GAUSSIAN-09 program package was used for all the calcula-
ture. The interactions between´ filled (donor) Lewis-type NBOs and
empt y´ (acceptor) non-Lewis NBOs lead to loss of occupancy from
tions [24]. The gas phase geometries of [ReOCl
2 1 3
(L )(PPh )] and
´
[
ReOCl (L )(PPh )] were fully optimized without any symmetry
2
2
3
the localized NBOs of the idealized Lewis structure into the empty
non-Lewis orbitals, and they are referred to as ´delocalization´
restrictions in singlet ground-states with the DFT method using
Table 1
Crystal data and structure refinement for 1, 2, 3 and 4.
1
2
3
4
Empirical formula
Formula weight
T (K)
C
72
H
51
N
3
O
4
Cl10
P
2
Re
2
C
35
H
24NO
2
PCl
3
Br
2
Re
C
35
H
25Cl
4
2
NO PRe
C
35 2 2 2
H25Br Cl NO PRe
1811.00
295.0(2)
0.71073
973.89
295.0(2)
0.71073
850.53
295.0(2)
0.71073
939.45
295.0(2)
0.71073
k (Å)
Crystal system
Space group
Unit cell dimensions
a (Å)
b (Å)
c (Å)
triclinic
P1ꢀ
orthorhombic
Pbca
triclinic
P1ꢀ
monoclinic
P21/c
10.6143(3)
15.4252(4)
22.7233(6)
74.071(2)
77.602(2)
84.069(2)
3490.24(16)
2
1.723
3.945
1772
15.8184(3)
20.1611(6)
21.2396(5)
10.4506(3)
11.5613(4)
15.3803(6)
75.742(3)
87.451(3)
65.974(3)
1641.73(10)
2
11.2274(4)
18.9869(5)
15.9416(4)
90
102.878(3)
90
3312.87(18)
4
1.884
6.323
1808
a
(°)
b (°)
(°)
c
3
V (Å )
6773.7(3)
8
1.910
6.265
3744
Z
D
calc (Mg/m3)
1.721
4.108
832
Absorption coefficient (mmꢁ1)
F(000)
Crystal size (mm)
h (°)
Index ranges
0.180 ꢃ 0.110 ꢃ 0.016
0.302 ꢃ 0.152 ꢃ 0.015
3.37–25.00
ꢁ18 6 h 6 18
ꢁ23 6 k 6 23
ꢁ25 6 l 6 25
50407
0.156 ꢃ 0.072 ꢃ 0.028
3.37–25.00
ꢁ12 6 h 6 12
ꢁ13 6 k 6 13
ꢁ18 6 l 6 18
17258
0.160 ꢃ 0.082 ꢃ 0.038
3.39–25.00
ꢁ12 6 h 6 13
ꢁ22 6 k 6 22
ꢁ18 6 l 6 16
16033
3.41–25.00
ꢁ12 6 h 6 12,
ꢁ
ꢁ
18 6 k 6 18
27 6 l 6 24
Reflections collected
33647
Independent reflections (Rint
Completeness to 2h = 25.00°
)
12281 (0.0559)
99.7%
5947 (0.0903)
99.7%
5772 (0.0373)
99.8%
5820 (0.0566)
99.7%
Minimum and maximum transmission
Data/restraints/parameters
Goodness-of-fit (GOF) on F
0.616–1.000
12270/0/839
0.936
0.375–1.000
5947/0/406
1.059
0.700–1.000
5772/0/397
1.053
0.352–1.000
5820/0/397
0.927
2
Final R indices [I > 2
r
(I)]
R
1
= 0.0334
wR = 0.0538
= 0.0570
wR = 0.0581
0.773 and ꢁ0.730
R
1
= 0.0357
wR = 0.0827
= 0.0517
wR = 0.0895
1.077 and ꢁ0.982
R
1
= 0.0240
wR = 0.0562
= 0.0293
wR = 0.0580
0.899 and ꢁ0.621
R
1
= 0.0457
wR = 0.0974
= 0.0826
wR = 0.1079
1.423 and ꢁ1.182
2
2
2
2
R indices (all data)
R
1
R
1
R
1
R
1
2
2
2
2
Largest difference peak and hole (e Åꢁ3)

2
66
B. Machura et al. / Polyhedron 51 (2013) 263–274
O
X
PPh3
X
Re
Ph P
3
X
,
X = Cl Br
Cl
:
1
1
MeCN
Cl
Cl
N
N
Cl
Cl
OH
OH
O
O
Ph P
X
X
Ph P
X
X
3
3
Re
Re
N
N
O
O
-
, -
-
cis X X ReOX N O PPh
[
2( )(
3)]
2 1 3 2 2 3 3 3 2 1 2
Scheme 2. Formation of [ReOX (L )(PPh )] and [ReOX (L )(PPh )] complexes in the reactions of [ReOX (PPh ) ] with a suitable ligand HL or HL .
corrections to the zeroth-order natural Lewis structure. The stabil-
ization energy ij (kcal/mol) associated with delocalization is
i i j
where q is the donor orbital occupancy, e , e are diagonal elements
(orbital energies) and F(i,j) is the off-diagonal NBO Fock or Kohn–
D
E
estimated by the second-order perturbative as
Sham matrix element [18].
2
D
E
ij ¼ q ðFði; jÞ Þ=ð
e
i
ꢁ Þ
e
j
i
Table 2
Hydrogen bonds for 1, 2, 3 and 4.
D
A
D–H (Å)
Hꢀ ꢀ ꢀA (Å)
Dꢀ ꢀ ꢀA (Å)
D–Hꢀ ꢀ ꢀA (°)
1
C(2)–H(2)ꢀ ꢀ ꢀCl(1)
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
0.93
2.78
2.50
2.76
2.40
2.72
2.81
2.79
2.27
2.77
2.78
2.33
2.60
3.623(5)
3.124(6)
3.109(5)
2.794(5)
3.051(5)
3.724(4)
3.486(6)
3.071(6)
3.114(5)
3.505(5)
2.814(5)
2.995(5)
151.9
124.8
103.4
105.3
102.0
169.1
132.2
143.5
103.4
135.6
111.8
106.4
C(12)–H(12)ꢀ ꢀ ꢀO(2)
C(25)–H(25)ꢀ ꢀ ꢀCl(4)
C(28)–H(28)ꢀ ꢀ ꢀO(1)
C(29)–H(29)ꢀ ꢀ ꢀCl(5)
C(29)–H(29)ꢀ ꢀ ꢀCl(6)_#1
C(38)–H(38)ꢀ ꢀ ꢀCl(1)_#2
C(47)–H(47)ꢀ ꢀ ꢀO(4)
C(60)–H(60)ꢀ ꢀ ꢀCl(9)
C(61)–H(61)ꢀ ꢀ ꢀCl(7)_#3
C(63)–H(63)ꢀ ꢀ ꢀO(3)
C(64)–H(64)ꢀ ꢀ ꢀCl(10)
2
C(3)–H(3)ꢀ ꢀ ꢀCl(2)_$4
C(3)–H(3)ꢀ ꢀ ꢀO(1)_$5
C(12)–H(12)ꢀ ꢀ ꢀO(2)
C(25)–H(25)ꢀ ꢀ ꢀCl(2)
C(28)–H(28)ꢀ ꢀ ꢀO(1)
C(29)–H(29)ꢀ ꢀ ꢀCl(3)
0.93
0.93
0.93
0.93
0.93
0.93
2.79
2.47
2.35
2.79
2.37
2.67
3.429(6)
3.301(6)
3.129(8)
3.125(6)
2.773(6)
3.079(5)
126.4
148.2
140.8
102.8
105.8
107.1
3
C(5)–H(5)ꢀ ꢀ ꢀO(1)_$6
C(12)–H(12)ꢀ ꢀ ꢀO(2)
C(16)–H(16)ꢀ ꢀ ꢀCl(2)_$7
C(28)–H(28)ꢀ ꢀ ꢀO(1)
0.93
0.93
0.93
0.93
2.47
2.34
2.75
2.18
3.279(5)
3.127(4)
3.514(4)
2.860(4)
146.1
142.6
139.9
129.1
4
C(5)–H(5)ꢀ ꢀ ꢀO(1)_$8
C(12)–H(12)ꢀ ꢀ ꢀO(2)
C(28)–H(28)ꢀ ꢀ ꢀO(1)
0.93
0.93
0.93
2.54
2.21
2.30
3.346(9)
3.016(11)
2.824(10)
145.0
145.0
115.3
#
#
1: ꢁ1 + x, y, z; #2: x, 1 + y, z; #3: 2 ꢁ x, 1 ꢁ y, 1 ꢁ z; #4: 1/2 ꢁ x, ꢁy, ꢁ1/2 + z; #5: 1 ꢁ x, ꢁy, 1 ꢁ z; #6: 1 ꢁ x, 1 ꢁ y, 1 ꢁ z;
7: 1 + x, y, z; #8: 2 ꢁ x, 2 ꢁ y, 1 ꢁ z.

B. Machura et al. / Polyhedron 51 (2013) 263–274
267
Fig. 1. The asymmetric units of 1, 2, 3 and 4. Displacement ellipsoids are drawn at 50% probability.
3
. Results and discussion
organic solvents. They show high stability toward air and moisture
both in the solid state and in solution for several weeks at ambient
temperature.
3.1. Preparation and infrared spectra
The IR spectra of 1–4 were characterized by strong absorptions
ꢁ
1
ꢁ1
ꢁ1
ꢁ1
The styrylquinolines (5,7-dichloro-2-[2-(2-chlorophenyl)vinyl]-
at 974 cm for 1, 972 cm for 2, 965 cm for 3 and 968 cm for
4, assigned to the Re@O stretching frequencies. These values are in
the range typical of neutral six-coordinate monooxorhenium(V)
complexes with an anionic phenolate oxygen coordinated trans
quinolin-8-ol (HL
1
) and 2-[2-(3,4-dichlorophenyl)vinyl]quinoline-
8
-ol (HL )) were prepared in high yields according to well-known
2
method based on the condensation of 8-hydroxyquinaldine with
appropriate aldehyde in acetic acid anhydride [20]. The purity
to the oxo group [32]. A relatively high wavenumber of
suggests that the Re–hydroxy bond trans to the oxo ligand does
not compete effectively for the Re orbitals. The absorptions in
the region 1630–1540 cm were assigned to the m(C@N) modes
of the chelating ligands [33].
The H NMR spectra of 1–4 in DMSO-d
ence of the chelating N,O-donor ligand and triphenylphosphine
molecule in the coordination spheres of pseudo-octahedral Re(V)
m(Re@O)
and structures of HL
NMR and mass spectroscopy (Supplementary materials).
The complexes [ReOCl (L )(PPh )]
ꢀMeCN (1), [ReOBr
PPh )] (2), [ReOCl (L )(PPh )] (3) and [ReOBr (L )(PPh )] (4) were
obtained by ligand exchange reactions starting from [ReOX
PPh ] complexes and HL (Scheme 2). They were isolated as a
dark green microcrystalline solids, moderately soluble in common
1 2
and HL were determined by means of HPLC,
d
ꢁ1
2
1
3
2
(L
2 1
)
(
3
2
2
3
2
2
3
1
also confirm the pres-
3
6
(
3
)
2

2
68
B. Machura et al. / Polyhedron 51 (2013) 263–274
Table 3
The experimental and optimized bond lengths (Å) and angles (°) for 1 and 3.
Bond lengths
1
3
Bond angles
1
3
Experimental
Optimized
Experimental
Optimized
Experimental
Optimized
Experimental
Optimized
Re(1)–O(1)
Re(1)–O(2)
Re(1)–N(1)
Re(1)–Cl(1)
Re(1)–Cl(2)
Re(1)–P(1)
1.665(3)
2.020(3)
2.177(4)
2.3283(12)
2.3703(12)
2.4831(11)
1.679
2.034
2.204
2.398
2.437
2.559
1.675(2)
1.975(2)
2.188(3)
2.3401(9)
2.4041(9)
2.4814(9)
1.682
2.018
2.206
2.404
2.444
2.558
O(1)–Re(1)–O(2)
O(1)–Re(1)–N(1)
O(2)–Re(1)–N(1)
O(1)–Re(1)–Cl(1)
O(2)–Re(1)–Cl(1)
N(1)–Re(1)–Cl(1)
O(1)–Re(1)–Cl(2)
O(2)–Re(1)–Cl(2)
N(1)–Re(1)–Cl(2)
Cl(1)–Re(1)–Cl(2)
O(1)–Re(1)–P(1)
O(2)–Re(1)–P(1)
N(1)–Re(1)–P(1)
Cl(1)–Re(1)–P(1)
Cl(2)–Re(1)–P(1)
160.88(14)
92.03(14)
75.38(13)
101.73(11)
92.11(10)
165.78(10)
103.85(11)
89.59(9)
85.09(9)
88.12(5)
85.44(10)
81.07(8)
93.37(9)
159.88
91.34
75.01
103.60
91.32
164.56
102.13
91.32
84.25
88.74
85.70
81.32
96.45
88.66
172.13
162.99(11)
91.81(11)
75.80(10)
103.48(8)
89.65(7)
164.54(8)
98.00(9)
92.59(7)
85.14(7)
90.40(3)
84.48(9)
84.64(7)
93.28(7)
90.49(3)
177.09(3)
160.14
91.62
75.22
103.94
90.67
163.95
101.18
92.35
84.18
88.89
85.21
81.76
96.86
88.47
173.51
91.29(4)
170.62(5)
Re(2)–O(3)
Re(2)–O(4)
Re(2)–N(2)
Re(2)–Cl(6)
Re(2)–Cl(7)
Re(2)–P(2)
1.660(3)
1.999(3)
2.184(3)
2.3258(11)
2.3859(12)
2.4797(12)
O(3)–Re(2)–O(4)
O(3)–Re(2)–N(2)
O(4)–Re(2)–N(2)
O(3)–Re(2)–Cl(6)
O(4)–Re(2)–Cl(6)
N(2)–Re(2)–Cl(6)
O(3)–Re(2)–Cl(7)
O(4)–Re(2)–Cl(7)
N(2)–Re(2)–Cl(7)
Cl(6)–Re(2)–Cl(7)
O(3)–Re(2)–P(2)
O(4)–Re(2)–P(2)
N(2)–Re(2)–P(2)
Cl(6)–Re(2)–P(2)
Cl(7)–Re(2)–P(2)
162.56(13)
92.04(13)
75.12(12)
102.85(10)
90.66(8)
164.99(10)
101.16(11)
90.20(9)
87.50(9)
87.76(4)
85.58(11)
83.71(9)
94.31(9)
88.79(4)
172.96(4)
Table 4
The experimental bond lengths (Å) and angles (°) for 2 and 4.
Bond lengths
2
4
Bond angles
2
4
Re(1)–O(1)
Re(1)–O(2)
Re(1)–N(1)
Re(1)–Br(1)
Re(1)–Br(2)
Re(1)–P(1)
1.665(4)
2.014(3)
2.196(4)
2.4764(6)
2.4978(15)
2.5251(7)
1.683(5)
1.980(5)
2.205(6)
2.4777(9)
2.486(2)
2.5451(9)
O(1)–Re(1)–O(2)
159.55(15)
162.4(2)
91.2(2)
75.4(2)
O(1)–Re(1)–N(1)
O(2)–Re(1)–N(1)
O(1)–Re(1)–Br(1)
O(2)–Re(1)–Br(1)
N(1)–Re(1)–Br(1)
O(1)–Re(1)–P(1)
O(2)–Re(1)–P(1)
N(1)–Re(1)–P(1)
Br(1)–Re(1)–P(1)
O(1)–Re(1)–Br(2)
O(2)–Re(1)–Br(2)
N(1)–Re(1)–Br(2)
Br(1)–Re(1)–Br(2)
P(1)–Re(1)–Br(2)
89.35(15)
75.00(14)
100.57(11)
96.20(10)
169.28(10)
88.78(14)
80.03(11)
95.97(12)
88.37(4)
102.86(14)
89.22(11)
85.65(12)
88.15(2)
102.54(19)
91.54(15)
166.13(15)
85.60(19)
83.87(15)
93.53(16)
89.77(5)
100.08(18)
90.39(15)
85.45(15)
89.92(3)
168.28(3)
174.24(5)
Table 5
Atomic charges from the natural population analysis (NPA) for [ReOCl
ReOCl (L )(PPh )].
ligand. Triphenylphosphine protons of 3 and 4 exhibit as two mul-
tiplets in range 7.37–7.19 ppm. Unfortunately, complexes 1–4 ex-
hibit limited solubility in most common solvents which
prevented the recording of meaningful 3C NMR spectra.
2 1 3
(L )(PPh )] and
[
2
2
3
1
Atom
Charge
ReOCl
[
2
1
(L )(PPh
3
)]
2 2 3
[ReOCl (L )(PPh )]
Re(1)
O(1)
O(2)
N(1)
P(1)
+0.272
ꢁ0.334
ꢁ0.607
ꢁ0.409
+1.523
ꢁ0.214
ꢁ0.266
+0.276
ꢁ0.340
ꢁ0.610
ꢁ0.404
+1.519
ꢁ0.224
ꢁ0.279
3
.2. Crystal structures
A definite proof for the structures of 1–4 is provided by the X-
ray diffraction results. The crystallographic data of 1–4 are summa-
rized in Table 1.
Cl(1)
Cl(2)
The intra- and intermolecular contacts [34,35] detected in the
structures 1–4 are collected in Table 2. The structures 1–4 are sta-
bilized by some C–Hꢀ ꢀ ꢀO and C–Hꢀ ꢀ ꢀX short contacts classified as
weak hydrogen bonds. The classical hydrogen bonds are not found
in 1–4.
atom. For 1 and 2 the protons of PPh
range 7.65–7.50 ppm, which obscure some protons of the chelate
3
appear as multiplet in the

B. Machura et al. / Polyhedron 51 (2013) 263–274
269
π*PPh3(82%)
-1.00
-2.00
-3.00
-4.00
-5.00
-6.00
-7.00
L+6
L+5
L+6
π*PPh3(85%)
π*PPh3(84%)
π*PPh3(90%)
L+5
π*
L
(81%), π*PPh3(10%)
π*PPh3(32%), d 2
-y2(30%), π*
L+4
L+3
x
L
(20%),
L+4
L+3
(64%), d 2
-y2(16%)
d
x
2-y2(36%), π*PPh3(31%), π*
(12%)
L
π*
L
x
L+2
L+1
π*
L
(76%), dyz(17%), π
O
(5%)
L+2
L+1
π*
L
(74%), dyz(18%), π
O
(5%)
d
xz(64%), π (20%)
O
d
d
xz(63%), π (22%)
O
LUMO
L O
dyz(53%), π* (20%), π (18%)
LUMO
L O
yz(52%), π* (19%), π (19%)
HOMO
π
L
(57%), dxy(27%), πCl(7%)
HOMO
π
π
L
L
(55%), dxy(27%), πCl(10%)
H-1
H-2
(81%)
H-1
H-2
π
L
(90%)
d
L
xy(50%), πCl(23%), π (21%)
L
dxy(45%), π (25%), πCl(23%)
H-3
H-4
π
π
PPh3(77%)
H-3
H-4
π
π
PPh3(76%)
PPh3(87%)
L
(92%)
Fig. 2. The energy (eV), character an d some contours of the unoccupied molecular orbitals of [ReOCl
are represented in blue (0.04 au) and negative values – in yellow (ꢁ0.04 au) (colour online).
2 1 3 2 2 3
(L )(PPh )] and [ReOCl (L )(PPh )]. Positive values of the orbital contour
The perspective drawings of the asymmetric units of 1–4 are
presented in Fig. 1, and the selected bond distances and angles
are collected in Tables 3 and 4.
All complexes show octahedral geometry about the rhenium
atom defined by the terminal oxo-group, two halide ions in cis
terminal oxo group. This is due to a strong trans-influence of the
oxo group, forcing the harder oxygen atom of the N–O ligand into
trans position. Such stereochemistry is well documented in the lit-
erature and seems to be the most common structure type for
[ReOX
The Re–O
typical of mononuclear complexes of rhenium(V) having [ReO]
2
(N–O)(PPh
3
)] complexes.
arrangement, the phosphorus of PPh
3
molecule, and the bidentate
t
bond lengths of 1–4 fall in the range 1.639–1.760 Å,
3+
N,O donors of the L ligand. The multiple bonding ligand (terminal
oxo) and narrow bite angle of the chelating ligand contribute to
clear distortions of the pseudooctahedral environment of Re center
core, and indicate the presence of a triple bond Re„O [36]. The
interatomic distances between the rhenium atom and the oxygen
atom of L ligand are somewhat shorter than an ideal single Re–O
bond length. The single Re–O bond, predicted by the use of Paul-
ing’s covalent radius for oxygen and Cotton and Lippard’s value
for the octahedral covalent radius of rhenium(V), is equal ca.
2 n 3
in the [ReOX (HL )(PPh )] complexes. The high concentration of
electronic density along the Re–O axis strongly influences the posi-
tions of the adjacent halogen atoms, which are pushed away. In all
reported compounds, the oxygen donor of L is located trans to the

2
70
B. Machura et al. / Polyhedron 51 (2013) 263–274
Table 6
The occupancy of the calculated natural bond orbitals (NBOs) between the rhenium and the oxo ligand for[ReOCl
2
1
(L )(PPh
3
)] and [ReOCl
2
2 3
(L )(PPh )].
*
BD
ReOCl
Re(1)–O(1)
Re(1)–O(1)
Occupancy
Composition of NBO
BD
Occupancy
[
2
(L
1
)(PPh
3
)]
)]
1.99
1.98
0.561 (d)Re + 0.828 (p)
0.573 (d)Re + 0.819 (p)
O
O
0.828 (d)Re ꢁ 0.561 (p)
0.819 (d)Re ꢁ 0.573 (p)
O
O
0.22
0.23
[
2 2
ReOCl (L )(PPh
3
Re(1)–O(1)
Re(1)–O(1)
1.99
1.98
0.563 (d)Re + 0.827 (p)
0.574 (d)Re + 0.819 (p)
O
O
0.827 (d)Re ꢁ 0.563 (p)
0.819 (d)Re ꢁ 0.574 (p)
O
O
0.22
0.24
BD denotes 2-center bond.
*
Denotes antibond NBO.
Table 7
2 1 3 2 2 3
Stabilization energies associated with delocalisation from the lone pair orbitals of the terminal oxo ligand for [ReOCl (L )(PPh )] and [ReOCl (L )(PPh )].
Donor orbital
Occupancy of donor orbital
1.91
Acceptor orbital
D
E
ij (kcal/mol)
[
(
2 1 3
ReOCl (L )(PPh )]
0
.82
⁄
0.29 1.37
sp
)
O(1)
LP (2)Re(1) [(sp
d
)
)
Re(1)
]
]
12.07
17.72
51.17
10.34
183.87
24.45
52.13
LP (3)Re(1) [(sp d0.39
⁄
2.96
Re(1)
⁄
LP (4)Re(1) [(p)Re(1)
]
]
d
⁄
RY (1)Re(1) [(d)Re(1)
sp1.83
)
O(1)
1.58
LP (2)Re(1) [(sp
⁄
0.29 1.37
)
)
]
]
(
Re(1)
LP (3)Re(1) [(sp d0.39
⁄
2.96
Re(1)
⁄
LP (4)Re(1) [(p)Re(1)
]
[
(
2 2 3
ReOCl (L )(PPh )]
0
.84
⁄
0.30 1.39
sp
)
O(1)
1.91
1.59
LP (2)Re(1) [(sp
d
)
)
Re(1)
]
]
11.59
17.68
50.25
10.42
182.35
25.55
51.63
LP (3)Re(1) [(sp d0.39
⁄
2.88
Re(1)
⁄
LP (4)Re(1) [(p)Re(1)
]
⁄
RY (1)Re(1) [(d)Re(1)
]
sp1.79
)
LP (2)Re(1) [(sp
⁄
0.30 1.39
d
)
)
]
]
(
O(1)
Re(1)
LP (3)Re(1) [(sp d0.39
⁄
2.88
Re(1)
⁄
LP (4)Re(1) [(p)Re(1)
]
Table 8
The energy and molar absorption coefficients of experimental absorption bands and the electronic transitions calculated with the TDDFT method for [ReOCl
2 1 3
(L )(PPh )].
State
Excitations
E
cal (eV)
kcal, (nm)
ꢃc4cal
k
expt (nm)
Character
⁄
⁄
S
S
S
S
S
S
S
S
1
H?L
1.61
2.33
2.61
2.90
3.35
3.50
3.66
3.67
769.8
532.5
475.1
427.6
370.6
354.2
338.4
337.7
0.0114
0.0349
0.1332
0.0927
0.1726
0.2171
0.0637
0.0642
634.4
448.2
p
(L)/d/
p
p
p
p
(Cl)?d/
p
p
(L)
(L)
3
Hꢁ2?L
Hꢁ1?L
H?L+2
Hꢁ1?L+2
Hꢁ2?L+2
Hꢁ10?L
Hꢁ11?L
Hꢁ10?L
d/ (L)/
(Cl)?d/
⁄
4
p
p
p
(L)?d/
(L)/d/
(L)?
(L)/
(L)?d/
(Cl)?d/
(L)
⁄
6
p
p
(Cl)/
p
(PPh
3
)?
p
(L)/d
⁄
15
17
21
22
(L)/d
⁄
356.1
330.5
d/
p
p
(Cl)?
p
(L)/d
⁄
p
p
p
p
(L)
(L)
(L)
⁄
p
⁄
(L)?d/
p
⁄
⁄
S
25
S
26
S
42
H?L+4
3.81
3.82
4.37
325.9
325.0
283.7
0.2610
0.0760
0.0728
p
p
(L)/d/
(PPh
p
(Cl)?
p
(PPh
(PPh
3
)/d/
p
(L)
(L)
Hꢁ8?L+1
Hꢁ2?L+4
Hꢁ2?L+3
Hꢁ3?L+3
Hꢁ3?L+4
Hꢁ7?L+3
Hꢁ7?L+4
Hꢁ5?L+6
Hꢁ7?L+5
Hꢁ3?L+7
Hꢁ8?L+5
3
)?d
⁄
⁄
⁄
d/
d/
p(L)/
p
(Cl)?
p
3
)/d/
p
p(L)/
p
(Cl)?
p
p
p
(L)/d
⁄
S
50
60
4.61
4.83
269.2
256.7
0.0907
0.0627
p(PPh
p(PPh
p(PPh
p(PPh
3
3
3
3
)?
)?
)/
)/
(L)/d
(PPh
⁄
⁄
3
)/d/
p
(L)
⁄
S
p
p
(Cl)?
(Cl)?
p
p
(L)/d
⁄
⁄
(PPh
3
)/d/
p
(L)
⁄
S
107
S
108
S
115
5.45
5.47
5.56
227.7
226.8
222.8
0.0505
0.0552
0.0425
222.3
p
p
p
p
(L)/d?
p
(PPh
3
)
⁄
(PPh
(PPh
(PPh
3
3
3
)/
p
)?
)?
(Cl)?
p
(PPh
3
)
⁄
p
p
(L)
⁄
3
(PPh )
207.6
– Molar absorption coefficient (dm3 mol cm ); f – oscillator strength; H – highest occupied molecular orbital; L – lowest unoccupied molecular orbital.
ꢁ1
ꢁ1
e
2
.04 Å [37]. It indicates only small delocalization of electron den-
The Re(1)–X(1) distances trans to the phosphorus atom of PPh
molecule are slightly longer than the Re(1)–X(2) bonds trans to
the nitrogen atom of the HL ligand. It indicates structural trans ef-
fect of the PPh ligand.
3
sity in the O„Re–O unit in these compounds and seems to be
typical feature of cis-X,X isomers of [ReOCl (N–O)(PPh )] with an
anionic phenolate oxygen coordinated trans to the oxo group.
2
3
n
3

B. Machura et al. / Polyhedron 51 (2013) 263–274
271
Table 9
The energy and molar absorption coefficients of experimental absorption bands and the electronic transitions calculated with the TDDFT method for [ReOCl
2 2 3
(L )(PPh )].
State
Excitations
E
cal (eV)
k
cal (nm)
ꢃc4cal
k
expt (nm)
Character
(L)/d/ (Cl)?d/
d/ (Cl)/
(L)?d/
d/ (Cl)/
(L)?d/
(L)/d/
(Cl)/
⁄
⁄
S
S
1
H?L
Hꢁ2?L
Hꢁ1?L
Hꢁ2?L+1
Hꢁ1?L
H?L+2
1.63
2.33
762.9
531.8
0.0123
0.0310
636.6
p
p
p
p
p
(L)
(L)
3
p
(L)?d/
⁄
S
4
2.68
463.4
0.0578
432.2
p
p
p
p
p
(L)
p
(L)?d
⁄
S
S
5
2.71
2.91
456.9
425.8
0.0805
0.1679
p
p
(L)
⁄
3
(PPh )?p (L)/d
6
(Cl)/
p
⁄
S
13
Hꢁ2?L+2
Hꢁ1?L+2
Hꢁ1?L+2
Hꢁ2?L+2
Hꢁ10?L
H?L+4
3.41
363.4
0.0865
312.2
251.0
d/
p
p
(L)?
(L)/d
(L)/d
p
(L)/d
⁄
⁄
p
(L)?
p
p
S
16
3.55
349.4
0.4268
p(L)?
⁄
d/
p
(Cl)/
p
p
(Cl)?
(Cl)?
(L)?
(L)
p
(L)/d
⁄
S
20
S
24
S
25
3.75
3.86
3.87
330.2
321.4
320.6
0.1371
0.1325
0.2782
p
p
p
(L)?d/
(L)/d/
(L)/d/
⁄
⁄
⁄
⁄
p
p
⁄
p
p
(L)/
(L)/
p
p
(PPh
(PPh
3
)
)
H?L+4
3
⁄
S
S
S
S
S
S
S
S
45
Hꢁ1?L+4
H?L+7
4.44
4.69
4.70
4.93
5.23
5.37
5.47
5.49
279.0
264.2
264.0
251.7
237.2
231.0
226.8
225.7
0.0593
0.0685
0.1306
0.0289
0.0423
0.0367
0.0655
0.0597
p
p
p
p
p
p
p
p
p
p
(L)?
(L)/d/
(PPh
(PPh
(L)?d/
(PPh
(PPh
(PPh
(Cl)/
(Cl)?
p
(L)/
(Cl)?
p
(PPh
3
)
⁄
52
p
p
(L)
⁄
⁄
53
Hꢁ3?L+3
Hꢁ6?L+3
Hꢁ7?L+3
Hꢁ3?L+6
Hꢁ6?L+5
Hꢁ9?L+4
Hꢁ15?L+2
Hꢁ11?L+4
3
)?d/
p
(PPh
(Cl)?d/
3
)/
p
(L)
⁄
⁄
(L)
64
3
)/
p
p
p
p
)
(PPh
3
)/
p
⁄
⁄
84
(PPh
3
)/
(L)
⁄
96
3
)?
3
)/
3
)?
p
(PPh
3
⁄
106
107
p
(Cl)?
p
(PPh
3
)
)
⁄
⁄
(PPh
p
(L)/
p
3
⁄
p(L)?
p
(L)/d
(PPh )
3
⁄
⁄
S
118
5.69
218.1
0.0390
p
(L)/
p
205.4
– Molar absorption coefficient (dm3 mol cm ); f – oscillator strength; H – highest occupied molecular orbital; L – lowest unoccupied molecular orbital.
ꢁ1
ꢁ1
e
3.3. Geometry optimization, charge distribution, electronic structure,
2 1 3 2 2 3
The complexes [ReOCl (L )(PPh )] and [ReOCl (L )(PPh )] are
NBO analysis
closed-shell structures. Their partial molecular orbital diagrams
with several HOMO and LUMO contours are presented in Fig. 2.
For both complexes under study the HOMO–LUMO gaps equal to
The DFT calculations have been preformed to get an insight in
the electronic structures and explain bonding nature and spectral
2 1 3
2.72 eV. The HOMO and HOMO-2 of [ReOCl (L )(PPh )] and
properties of the complexes [ReOCl
(L
2 1
)(PPh
3
)] and [ReOCl (L
2 2
)
[ReOCl (L )(PPh )] are composed of rhenium dxy and p chloride
2
2
3
(
PPh )]. Before the calculations of the electronic structures of the
3
orbitals in antibonding arrangement to metal orbital as well as
contain admixture from L ligand orbitals. HOMOꢁ1 and some low-
er-energy occupied MOs of 1 and 3 correspond to orbitals of the
studied compounds, their geometries were optimized in singlet
states using the DFT method with the B3LYP functional. The opti-
mized geometric parameters of [ReOCl
)(PPh )] are given in Table 3.
In general, the predicted bond lengths and angles are in agree-
2
(L
1
)(PPh
3
)] and [ReOCl
2
3
chelate ligand or PPh . The LUMO and LUMO+1 of 1 and 3 are pre-
(
L
2
3
dominately localized on the rhenium atom (dxz and dyz orbitals)
⁄
with some contribution of p
p
oxygen orbitals and
p
-antibonding
ment with the values based upon the X-ray crystal structure data,
and the general trends observed in the experimental data are well
reproduced in the calculations. The B3LYP method in combination
orbitals of ligand L. To large extent these orbitals can be ascribed
as -antibonding rhenium–oxygen molecular orbitals. The
LUMO+3 and LUMO+4 orbitals of [ReOCl (L )(PPh )] and LUMO+3
of [ReOCl (L )(PPh )] are contributed by metal orbitals d
er-energy unoccupied MOs have
ger number of electron-withdrawing halide substituents in ligand
in comparison with L exerts an influence on energy level of
frontier orbitals of [ReOCl (L )(PPh )] and [ReOCl (L )(PPh )]. Li-
gand L decreases energy level of the highest occupied and the
p
2
1
3
with the LANL2DZ basis gives an excellent estimation of Re–O
bond length with deviation of +0.014 Å for [ReOCl (L )(PPh )]
and +0.007 Å for [ReOCl (L )(PPh )]. The Re–N and other Re–O dis-
t
2
2
3
x2ꢁy2
. High-
⁄
⁄
2
1
3
3
p (PPh ) and p (L) character. Lar-
2
2
3
tances are also well reproduced (deviations of the distances Re–N
are equal to 0.026 and 0.018 Å for 1 and 3, and deviations of the
Re–O bond lenghts are 0.014 for 1 and 0.043 Å for 3). Larger devi-
ations are noticed for Re–Cl and Re–P bond lengths, but they are
also satisfactory for this level of theory.
L
1
2
2
1
3
2
2
3
1
lowest unoccupied MOs in relation to complex 2.
For further understanding of the bond characteristics in re-
Table 5 presents the atomic charges from the natural population
analysis (NPA) for 1 and 3. The calculated charges on the rhenium
atoms in 1 and 3 are considerably lower than the formal charge of
2 1 3 2 2 3
ported complexes [ReOCl (L )(PPh )] and [ReOCl (L )(PPh )], natu-
ral bond orbital (NBO) studies have been performed. Table 6
presents the occupancies and hybridization of the calculated natu-
ral bond orbitals (NBOs) between the rhenium and the oxo ligands.
Table 7 shows the occupancies and atomic orbital compositions of
the lone pairs (LP) of the oxo ligands, as well as the character of the
+5, and the populations of the dxy, dxz, dyz, dx
2ꢁy2
and dz orbitals of
2
the central atoms are following: 1.097, 0.941, 1.271, 0.825 and
.376 for 1 and 1.119, 0.951, 1.098, 0.840 and 1.502 for 3. It con-
1
firms significant charge donation from the ligands. The P atom is
positively charged, and the charges on the terminal oxo, chloride
and oxygen atom of L are significantly smaller than ꢁ2, ꢁ1 and
acceptor orbital and stabilization energies (
sponding donor–acceptor interactions for [ReOCl
[ReOCl (L )(PPh )]. For both complexes the results of NBO point
to the existence of two Re–O natural bond orbitals, which result
from overlapping of the empty dxy and dyz rhenium orbitals with
the occupied p and p orbitals of terminal oxo ligand. Therefore
they are of character. Lack of Re–Ot natural orbital indicates a
conceivable predominant Coulomb-type Re–ligand interaction
D
E
ij) for the corre-
2
(L )(PPh )] and
1
3
2
2
3
ꢁ
1, respectively. The terminal oxo ions are less negative in com-
t
parison with the oxygen atoms of L ligand. It indicates the higher
electron density delocalization from the terminal ligands towards
the rhenium centres and corresponds to differences in the Re–
O(1) and Re–O(2) bond lengths.
x
z
p
r

2
72
B. Machura et al. / Polyhedron 51 (2013) 263–274
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0.00
200.00
400.00
600.00
800.00
1000.00
(
a)
1
.20
.00
.80
.60
.40
.20
.00
1
0
0
0
0
0
2
00.00
400.00
600.00
800.00
1000.00
(
b)
Fig. 3. The experimental (black) and calculated (red) electronic absorption spectra of [ReOCl
2 1
(L )(PPh
3
2 2 3
)] (a) and [ReOCl (L )(PPh )] (b) (colour online).
[
38]. The terminal oxo ligand of [ReOCl
(L
2 1
3
)(PPh )] and [ReOCl
2
t
(see Table 8). The nature of Re–O bonds is in agreement with the
(
L
2
)(PPh )] has two lone pair orbitals, and electron density from
3
results obtained in previous works regarding analysis of the bond-
ing nature of rhenium(V) oxocomplexes [39].
one of them is strongly delocalized into non-Lewis rhenium orbital

B. Machura et al. / Polyhedron 51 (2013) 263–274
273
3
.4. Electronic spectra
supported by a DoktoRIS fellowship. The GAUSSIAN09 calculations
were carried out in the Wrocław Centre for Networking and Super-
computing, WCSS, Wrocław, Poland. Grant No. 18.
The energies and characters of the selected singlet excited
states for complexes 1 and 3 are listed in Tables 8 and 9, together
with experimental data. The energy of each excited is vertical exci-
tation energy in eV from the ground state and for the high energy
part of the spectrum only excited states with the greatest oscillator
strengths are displayed in Tables 8 and 9. Assignment of the char-
acter of each excited state was based on the compositions of the
occupied and virtual MOs of the dominant configuration(s) for that
excited state. The experimental and calculated results are also
graphically compared in Fig. 3, presenting the experimental and
calculated electronic absorption spectra of 1 and 3. In Fig. 3 each
Appendix A. Supplementary material
CCDC 905844, 905845, 905846, 905847 contains the supple-
mentary crystallographic data for C72
H
51
N
3
O
4
Cl10
P
2
Re
Cl
2
(1), C35
H
24-
NO PCl Br Re (2), C35 25Cl NO PRe (3), C35
2
3
2
H
4
2
H25Br
2
2
NO PRe (4).
2
These data can be obtained free of charge via http://www.ccdc.ca-
m.ac.uk/conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK;
fax: +44 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk. Sup-
plementary data associated with this article can be found, in the
online version, at http://dx.doi.org/10.1016/j.poly.2012.12.028.
calculated transition is represented by
a
gaussian function
2
ꢁbx
y ¼ ce
with the height (c) equal to the oscillator strength and
ꢁ2
b equal to 0.04 nm
.
As shown in Fig. 3, the studied complexes have very similar
absorption character and TDDFT calculations well correlate with
the experimental absorptions. The longest wavelength experimen-
tal bands at 634.4 for 1 and 636.6 nm for 3 originate from the exci-
tations between HOMO or HOMOꢁ2 and the lowest unoccupied
MO. As it can be seen from the Fig. 2, the highest occupied molec-
ular orbital of 1 and 3 are composed of dxy rhenium atomic orbital,
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,7-Dichloro-2-[2-(2-chlorophenyl)vinyl]quinolin-8-ol
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(L )(PPh )]
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(L )(PPh
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