X-ray and electronic structure of the [ReCl3(pzH) 2(PPh3)] and [ReCl3(3,5-Me2pzH) 2(PPh3)] complexes

Article abstract of DOI:10.1016/j.poly.2004.04.017

X-ray structures of new [ReCl₃(pzH)₂(PPh ₃)] and [ReCl₃(3,5-Me₂pzH)₂(PPh ₃)] complexes (pzH=pyrazole) have been determined, and the geometric parameters of [ReCl₃(pzH)

Full text of DOI:10.1016/j.poly.2004.04.017

Polyhedron 23 (2004) 1819–1827
www.elsevier.com/locate/poly
X-ray and electronic structure of the [ReCl3(pzH)2(PPh3)]
and [ReCl3(3,5-Me2pzH)2(PPh3)] complexes
a,
b
c,1
Barbara Machura *, M. Jaworska , Rafal Kruszynski
a
Department of Inorganic and Radiation Chemistry, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
b
Department of Theoretical Chemistry, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
c
Department of X-ray Crystallography and Crystal Chemistry, Institute of General and Ecological Chemistry,
_
Łꢀodꢀz University of Technology, 116 Zeromski St., 90-924 Łꢀodꢀz, Poland
Received 17 March 2004; accepted 13 April 2004
Available online 18 May 2004
Abstract
X-ray structures of new [ReCl3(pzH)2(PPh3)] and [ReCl3(3,5-Me2pzH)2(PPh3)] complexes (pzH ¼ pyrazole) have been deter-
mined, and the geometric parameters of [ReCl3(pzH)2(PPh3)] have been examined using density functional theory (DFT) method.
The UV–Vis spectra of the complexes have been discussed on the basis of the electronic transitions of [ReCl3(pzH)2(PPh3)] cal-
culated with time-dependent DFT method (TDDFT).
Ó 2004 Elsevier Ltd. All rights reserved.
Keywords: Rhenium complexes; Pyrazole ligand; X-ray structure; DFT calculations
1. Introduction
pyrazole and acetone and (ii) dinuclear Re(V) com-
pounds of types [{Re(O)X(PPh3)}2(l-O)(l-pz)2], [{Re(-
O)X2(3,5-Me2pzH)2}2(l-O)], [{Re(O)Br(3,5-Me2pzH)}2
The noticeable growth of interest in the rhenium co-
ordination chemistry is connected with the favourable
nuclear properties of 186Re and 188Re nuclides, which
make the radioisotopes useful for diagnostic nuclear
medicine and applications in radioimmunotherapy [1,2].
Although pyrazole and its derivatives have a special
place among N-donor ligands, the number of rhenium
complexes containing these ligands is limited [2–6].
Previously, we investigated the reactivity of oxorhe-
nium(V) species – [ReO(OEt)X2(PPh3)2], [ReOX3(PPh3)2]
and [ReOX3(AsPh3)(OAsPh3)] (X ¼ Cl or Br) – towards
pyrazole (pzH) and 3,5-dimethylopyrazole (3,5-Me2
pzH) under various reaction conditions. The products of
these syntheses include: (i) mononuclear [ReOX2{g2-
N2C3H3C(CH3)2O}(PPh3)] complexes with C3H3N2C
(CH3)2Oꢀ anion obtained in the addition reaction of
(l-O)(l-3,5-Me2pz)2],
[{Re(O)X(PPh3)}2(l-O)(l-3,5-
Me2pz)2] and [{Re(O)X(PPh3)}(l-O)(l-3,5-Me2pz)2{Re
(O)X(3,5-Me2pzH)}] (X ¼ Cl or Br) [7,8].
Here, we report the synthesis and X-ray structure of
the two mononuclear Re(III) [ReCl3(pzH)2(PPh3)] (1)
and [ReCl3(3,5-Me2pzH)2(PPh3)] (2) complexes and the
results of the density functional theory (DFT) calcula-
tions for 1. The UV–Vis spectra of 1 and 2 are discussed
basing on the electronic transitions of 1, calculated using
the time-dependent DFT method (TDDFT).
2. Experimental
2.1. General procedure
The reactions were carried out under argon atmo-
sphere. All solvents were of reagent grade and were used
as received. Ammonium perrhenate, Ph3P and pyrazole
(pzH) were purchased from Aldrich and used as
* Corresponding author. Tel.: +48322582441; fax: +48322599978.
E-mail addresses: basia@tc3.us.ich.edu.pl (B. Machura), mj@tc3.i-
ch.us.edu.pl (M. Jaworska).
1
A holder of the Foundation for Polish Science (FNP) scholarship.
0277-5387/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2004.04.017

1820
B. Machura et al. / Polyhedron 23 (2004) 1819–1827
received. [Re(MeCN)Cl3(PPh3)2] and [ReOCl3(PPh3)2]
complexes and 3,5-Me2pzH were prepared according to
the literature methods [9–11].
2.3. Preparation of [ReCl3(3,5- Me2pzH)2(PPh3)] (2)
[Re(MeCN)Cl3(PPh3)2] (1 g, 1.20 mmol) and 3,5-
Me2pzH (0.77 g, 8 mmol) in chloroform (80 cm3) were
refluxed for 4 h. The starting material gradually dissolved
and the colour of the reaction solution became dark red.
After 3 h, the reddish-orange microcrystalline solid
started to participate. The volume was condensed to 10
cm3, diethyl ether (100 cm3) was added and reddish-or-
ange microcrystalline solid was filtered. The product was
washed with EtOH and cold ether, and dried in vacuo.
The crystals of 2 suitable for X-ray investigation were
obtained by recrystallization from a mixture of acetoni-
trile and dichloromethane (yield 85%).
IR spectra were recorded on a Nicolet Magna 560
spectrophotometer in the spectral range 4000–400
cmꢀ1 with the samples in the form of KBr pellets.
Electronic spectra were measured on a spectropho-
tometer Lab Alliance UV–Vis 8500 in the range 800–
220 nm in deoxygenated dichloromethane solution.
The magnetic susceptibility was determined with a
superconducting quantum interference device (SQUID,
Quantum Design) magnetometer. Elemental analyses
(C, H and N) were performed on a Perkin–Elmer
CHN-2400 analyser.
IR(KBr, cmꢀ1) 3384 (s), 3354 (s) 3138 (w), 3055 (m),
2922 (m), 1567 (s) 1482 (m), 1465 (w), 1432 (s), 1395 (m),
1372 (m), 1275 (s) 1177 (m), 1149 (m), 1091 (s), 1031 (s),
999 (w), 813 (w), 800 (m), 744 (s), 694 (s), 650 (m), 644
(m), 555 (w), 524 (s), 511 (s), 497 (s), 448 (m). Anal. Calc.
for C28H31N4Cl3PRe: C, 45.01; H, 4.18; N, 7.50. Found:
C, 45.33; H, 4.29; N, 7.60%.
2.2. Preparation of [ReCl3(pzH)2(PPh3)] (1)
2.2.1. Method A (1a)
[ReOCl3(PPh3)2] (1 g, 1.20 mmol) and pzH (0.54 g, 8
mmol) in diisopropyl ketone (60 cm3) were refluxed for 2
h. The starting material gradually dissolved and the
colour of the reaction solution changed from green to
dark brown. The volume of the reaction solution was
condensed to 20 cm3 and reddish-orange microcrystal-
line solid was formed by an addition of 100 cm3 of di-
ethyl ether. The product was washed with EtOH and
cold ether, and dried in vacuo.
2.4. Crystal structures determination and refinement
The X-ray intensity data were collected on a KM-
4-CCD automatic diffractometer equipped with CCD
detector with 24, 32 and 40 s exposure time (for com-
pounds 1a, 1b and 2, respectively) was used and the whole
Ewald sphere (up to 2h ¼ 50°) was collected. The unit cell
parameters were determined from least-squares refine-
ment of the setting angles of 8345°, 6543° and 5421°
(respectively, as above) of strongest reflections. Details
concerning crystal data and refinement are given in Table
1. Lorentz, polarization and numerical absorption cor-
rections [12] were applied. The structures 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 hydrogen atoms of the phenyl
rings were treated as ‘‘riding’’ on their parent carbon
2.2.2. Method B (1b)
[Re(MeCN)Cl3(PPh3)2] (1 g, 1.20 mmol) and pzH
(0.54 g, 8 mmol) in chloroform (80 cm3) were refluxed
for 4 h. The starting material gradually dissolved and
the colour of the reaction solution became dark red.
After 3 h, the reddish-orange microcrystalline solid
started to participate. The volume was condensed to 10
cm3, diethyl ether (100 cm3) was added and reddish-
orange microcrystalline solid was filtered. The product
was washed with EtOH and cold ether, and dried
in vacuo.
ꢁ
The crystals of 1a and 1b suitable for X-ray investi-
gation were obtained by recrystallization from a mixture
of acetonitrile and dichloromethane (yield 80%).
The solvents used for the reactions and recrystalli-
zation were not dried, so some water was present in the
reaction systems and water molecule was found in 1b
structure.
IR(KBr, cmꢀ1) 3154 (s), 3134 (m) 3115 (w), 2939 (m),
2903 (m), 2840 (m), 2810 (w), 1610 (w) 1572 (w), 1497
(w), 1479 (m), 1458 (m), 1435 (s), 1400 (s), 1346 (w),
1317 (m), 1256 (m) 1192 (w), 1126 (s), 1093 (s), 1068 (w),
1050 (m), 1042 (s), 999 (w), 955 (w), 906 (w), 854 (w),
788 (m), 768 (m), 746 (s), 698 (s), 689 (s), 609 (w), 598
(w), 526 (s), 510 (s), 495 (m), 449 (w), 432 (w). Anal.
Calc for C24H23N4Cl3PRe: C, 41.72; H, 3.35; N, 8.11.
Found: C, 41.98; H, 3.56; N, 8.20%.
atoms [d(C–H) ¼ 0.96 A] and assigned isotropic temper-
ature factors equal 1.2 times the value of equivalent
temperature factor of the parent carbon atom. SHELXS
97 [13], SHELXL 97 [14] and SHELXTL [15] programs were
used for all the calculations. Atomic scattering factors
were those incorporated in the computer programs.
The crystals of 1a have the diffused electron density
originated from multipositional disordered solvent water
molecule around special position 0, 1/2 and 1/2. This ef-
fect was repeatable for all measured crystals in the sam-
ple. In the crystals of 1b it can be found slightly
dynamically disordered water molecule that is also stat-
ically disordered in two symmetry equivalent positions.
The N2/C21 and N4/C24 atoms in structure of 1 were
distinguished on the basis of anisotropic parameters.
Changing the carbon atoms to nitrogen and vice versa

B. Machura et al. / Polyhedron 23 (2004) 1819–1827
1821
Table 1
Crystal data and structure refinement for 1a, 1b and 2
1a
1b (1 ꢂ 1/2H2O)
C24H24Cl3N4O0:5PRe
2
Empirical formula
Formula weight
Temperature (K)
C24H23Cl3N4PRe
690.98
C28H31Cl3N4PRe
747.09
293(2)
699.99
293(2)
0.71073
291(2)
0.71073
ꢁ
Wavelength (A)
0.71073
ꢂ
Space group
Crystal system
Unit cell dimensions
P21=n
monoclinic
P21=n
monoclinic
P1
triclinic
ꢁ
a (A)
11.4910(9)
17.5839(15)
13.8284(12)
11.4101(6)
17.6808(9)
13.7198(9)
10.2682(8)
13.0183(15)
13.0572(14)
66.249(11)
76.127(8)
ꢁ
b (A)
ꢁ
c (A)
a (°)
b (°)
c (°)
108.030(7)
107.418(5)
68.374(9)
1476.6(3)
3
ꢁ
Volume (A )
2656.9(4)
4
1.727
2640.9(3)
4
1.761
Z
2
1.680
Dcalc (Mg mꢀ3
)
Absorption coefficient (mmꢀ1
F ð000Þ
)
4.955
1344
4.988
1364
4.465
736
Crystal size (mm)
h range for data collection (°)
Index ranges
0.69 ꢃ 0.26 ꢃ 0.06
3.61–25.16
ꢀ13 6 h 6 13
ꢀ20 6 k 6 20
ꢀ16 6 l 6 16
29 535
0.22 ꢃ 0.11 ꢃ 0.04
3.08–25.11
ꢀ13 6 h 6 13
ꢀ21 6 k 6 21
ꢀ16 6 l 6 16
27 515
0.26 ꢃ 0.12 ꢃ 0.10
3.19–25.10
ꢀ12 6 h 6 12
ꢀ15 6 k 6 15
ꢀ15 6 l 6 15
14 778
Reflections collected
Independent reflections
Completeness to 2h (%)
4740 ðRint ¼ 0:0691Þ
96.0
4703 ðRint ¼ 0:0566Þ
96.4
5249 ðRint ¼ 0:0770Þ
99.8
Maximum and minimum transmission
Data/restraints/parameters
Goodness-of-fit on F 2
0.769 and 0.130
4740/0/298
1.156
0.887 and 0.406
4703/0/307
1.096
0.770 and 359
5249/0/336
0.991
Final R indices ½I > 2rðIÞꢁ
R1 ¼ 0:0566
WR2 ¼ 0:1453
R1 ¼ 0:0580
WR2 ¼ 0:1465
2.887 and )1.123
R1 ¼ 0:0331
wR2 ¼ 0:0727
R1 ¼ 0:0482
wR2 ¼ 0:0782
1.029 and )0.791
R1 ¼ 0:0293
wR2 ¼ 0:0648
R1 ¼ 0:0353
wR2 ¼ 0:0667
1.355 and )0.833
R indices (all data)
ꢀ3
ꢁ
Largest difference peak and hole (e A
)
1a, data for the 1 complex obtained according to method A.
1b, data for the 1 complex obtained according to method B.
cause anisotropic displacement parameters to be
senseless.
erate yield. The well-known capacity of PPh3 to interact
with the ReBO bond in the rhenium(V) oxo-complexes
explains the course of the reaction between [Re-
OCl3(PPh3)2] and pyrazole:
2.5. Computational details
2½ReOCl3ðPPh3Þ ꢁ þ 2N2C3H4
2
GAUSSIAN 03 program [16] was used in the calcula-
tions. The geometry optimization was carried out using
the DFT method with the use of B3LYP functional
[17,18]. The electronic spectrum was calculated with the
TDDFT method [19].
LANL2DZ basis set [20] was used on the rhenium
atom, 6-31G(d) on the chlorine, nitrogen, phosphorus
and carbon atoms and 6-31G basis on the hydrogen
atoms in the calculations.
! ½ReCl3ðpzHÞ ðPPh3Þꢁ þ OPPh3
A higher yield of 1 has been reported for the substitution
reaction:
2
½ReCl3ðMeCNÞðPPh3Þ ꢁ þ 2pzH
2
! ½ReCl3ðpzHÞ ðPPh3Þꢁ þ MeCN þ PPh3:
2
The complex 2 has been obtained in the reaction of
[ReCl3(MeCN)(PPh3)2] with 3,5-Me2pzH. The excess of
pyrazole and 3,5-Me2pzH used in the reactions ensure
the maximum yield of the complexes.
3. Results and discussion
3.1. X-ray structure
Two different routes have been employed for the
preparation of 1. The refluxing of [ReOCl3(PPh3)2] with
pzH in diisopropyl ketone gives the complex 1 in mod-
A perspective drawings of 1 and 2 are given in Figs. 1
and 2, respectively. The rhenium atom of the both

1822
B. Machura et al. / Polyhedron 23 (2004) 1819–1827
Fig. 1. The molecular structure of 1.
Fig. 2. The molecular structure of 2.

B. Machura et al. / Polyhedron 23 (2004) 1819–1827
1823
complexes is in distorted octahedral environment with
3.3. Magnetochemical measurements
three chlorine ligands in mer geometry, two N-donor
ligands (pzH or 3,5-Me2pzH) in cis position to each
other and one PPh3 molecule occupying trans position
to N(3) atom. Table 1 presents crystal data and struc-
tural refinement for 1a, 1b and 2. The most important
bond lengths and angles for compounds 1a, 1b and 2 are
reported in Table 2. A notable trans influence of tri-
phenylphosphine ligand is observed in both complexes;
the Re–N(3) bond lengths are longer in comparison with
the corresponding Re–N(1) distances. The Re–N, Re–Cl
and Re–P bond lengths are unexceptional, they agree
well with appropriate values found previously in similar
rhenium compounds [7,8,21–23].
Magnetic susceptibilities of 1 were recorded over the
temperature range 5–300 K. Temperature dependence of
the molar magnetic susceptibility for 1 is presented in
Fig. 3. The observed room-temperature effective mag-
netic moment 1.2 BM is typical of the rhenium(III)
mononuclear complexes. It consistent with low-spin
rhenium(III) ðd4Þ ions in Oh field [27] and arises because
of the large spin–orbit coupling (n ¼ 2500 cmꢀ1) [28].
3.4. The optimized geometry and molecular orbitals of 1
The geometry of 1 was optimized in triplet and singlet
states using the DFT method with the B3LYP func-
tional. The energy of the singlet state is of 16.3 kcal
higher. The optimized geometric parameters of the
triplet state are gathered in Table 2. The optimized ge-
ometry of 1 is in good agreement with the experimental
one and the largest differences are found for Re–Cl bond
distances.
The selected HOMO and LUMO orbitals with a-spin
for 1 are depicted in Fig. 4. The following orientation of
the axes has been used for determination of the MO
characters: the z-axis goes along Cl(1)–Re–Cl(3) linkage
and x goes through the N(3)–Re–P(1) bonds. The rhe-
nium dp atomic orbital (dxz; dyz and dxy) and p orbitals
of chlorine ligands in anti-bonding arrangement make
main contributions into the HOMO-2, HOMO-1 and
The weak intramolecular and intermolecular hy-
drogen bonds [24–26] of 1 and 2 are presented in
Table 3.
3.2. Infrared data
The strong bands in the range assignable to N–H
vibrations (3400–3100 cmꢀ1) in the IR spectra of 1
and 2 confirm the coordination of pyrazoles ligands
in the neutral monodentate form. The characteristic
bands of the C@C and C@N stretching modes, ob-
served at 1640 and 1558 cmꢀ1 in uncomplexed pyr-
azole and at 1663 and 1595 cmꢀ1 in uncomplexed 3,5-
dimethylpyrazole, are shifted to considerable lower
frequencies.
Table 2
ꢁ
ꢁ
The experimental bond lengths (A) and angles (°) for 1a, 1b and 2 and the optimized bond lengths (A) and angles (°) for 1
Optimized
Experimental
Experimental
1a
1b
1
2
Bond lengths
Re(1)–Cl(1)
Re(1)–Cl(2)
Re(1)–Cl(3)
Re(1)–N(1)
Re(1)–N(3)
Re(1)–P(1)
2.345(2)
2.400(2)
2.357(2)
2.135(7)
2.167(8)
2.421(2)
2.3452(15)
2.448
2.489
2.407
2.166
2.164
2.487
2.3713(12)
2.3956(11)
2.4009(12)
2.135(3)
2.3993(15)
2.3614(15)
2.127(5)
2.194(5)
2.4296(14)
2.185(3)
2.4466(11)
Bond angles
N(1)–Re(1)–N(3)
N(1)–Re(1)–Cl(1)
N(3)–Re(1)–Cl(1)
N(1)–Re(1)–Cl(2)
N(3)–Re(1)–Cl(2)
Cl(1)–Re(1)–Cl(2)
N(1)–Re(1)–Cl(3)
N(3)–Re(1)–Cl(3)
Cl(1)–Re(1)–Cl(3)
Cl(2)–Re(1)–Cl(3)
N(1)–Re(1)–P(1)
N(3)–Re(1)–P(1)
Cl(1)–Re(1)–P(1)
Cl(2)–Re(1)–P(1)
Cl(3)–Re(1)–P(1)
85.8(3)
87.4(2)
87.1(2)
85.98(16)
86.75(13)
88.20(12)
173.97(12)
88.48(12)
90.71(6)
87.13
87.12
88.59
173.88
87.21
90.42
87.52
89.43
174.37
94.75
93.40
178.99
92.30
92.30
89.73
89.24(12)
92.87(9)
86.70(10)
174.36(9)
87.22(9)
91.31(4)
85.92(9)
88.26(10)
174.83(4)
89.58(4)
93.47(9)
172.08(10)
85.73(4)
90.61(4)
99.35(4)
173.80(19)
88.2(2)
90.43(9)
88.7(2)
87.7(2)
89.21(13)
87.38(12)
174.21(6)
92.90(6)
173.77(9)
92.89(9)
92.03(19)
177.2(2)
94.67(8)
93.94(8)
90.36(8)
91.40(12)
175.94(12)
94.75(5)
94.26(5)
89.49(5)

1824
B. Machura et al. / Polyhedron 23 (2004) 1819–1827
Table 3
Hydrogen bonds for 1a, 1b and 2
D
A
Hꢂ ꢂ ꢂA
1a
Dꢂ ꢂ ꢂA
1a
D–Hꢂ ꢂ ꢂA
1a
1b
1b
1b
N(4)
N(4)
N(2)
C(8)
C(8)
C(21)
C(14)
Cl(2)
Cl(2#1)
Cl(1)
Cl(2)
Cl(3)
Cl(3)
Cl(2)
2.60
2.55
2.65
2.77
2.83
2.58
2.57
2.58
2.63
3.114(8)
3.225(8)
3.148(12)
3.439(11)
3.507(11)
3.136(10)
3.102(6)
3.254(6)
3.112(7)
119.8
135.7
117.9
129.8
130.9
118.7
120.6
135.5
116.8
2.62
2.74
3.159(6)
3.425(6)
117.4
131.2
2
N(2)
N(4)
C(8)
Cl(3)
Cl(2)
Cl(2)
Cl(3)
Cl(2#2)
Cl(3)
2.71
2.79
2.68
2.54
2.81
2.68
3.105(4)
3.155(4)
3.526(6)
3.435(6)
3.629(5)
3.511(5)
111.7
111.5
151.8
160.4
147.1
144.9
C(18)
C(20)
C(28)
#1: 2 ꢀ x; ꢀy; 1 ꢀ z for 1a and ꢀx; ꢀy; ꢀz for 1b.
#2: x ꢀ 1; y; z.
Fig. 3. Temperature dependence of the molar susceptibility for 1.
HOMO with a-spin and HOMO, LUMO and
LUMO + 1 with b-spin. The HOMO orbitals have also
the antibonding contribution from the pyrazole ligands.
The lower lying orbitals are p orbitals of the phenyl
groups and pyrazole ligands. HOMO-11 and HOMO-5
with a-spin and HOMO-9 and HOMO-3 with b-spin

B. Machura et al. / Polyhedron 23 (2004) 1819–1827
1825
The energy and molar absorption coefficients of ex-
perimental absorption bands of 1 and 2 are presented
in Table 4. The spin-allowed triplet–triplet electronic
transitions of 1 calculated with the TDDFT method are
presented in Table 5. Except for the low energy part of
the spectrum, only transitions with oscillator strengths
larger than 0.01 are listed. The UV–Vis spectrum of 1
was calculated only to 260 nm. Nevertheless, on the
basis of the calculated transitions for PPh3 and [Re-
Cl3(pzH)3] [41], it can be assumed that the experimental
bands of 1 and 2 at energy below 240.0 nm corre-
spond to intraligand p ! pꢄ transitions in phosphine
and pyrazole ligands. The solution spectra of pyrazole
and PPh3 exhibit intense absorption band at 231.6
and 217.6 nm, respectively, which can support this
assignment.
The assignment of the calculated transitions to the
experimental bands was based on the criterion of the
energy and oscillator strength of the calculated transi-
tion. The long-wave experimental bands are of low
intensity and they are compared to the calculated long-
wave transitions with small oscillator strengths. The
remaining absorption experimental bands are of much
higher intensity and they are compared to the calculated
transitions with high oscillator strengths.
The longest wave experimental bands of 1 and 2 (at
507.3 and 547.8 nm, respectively) may be attributed to
the calculated transitions of pCl ! d and pPh ! d
character (at 407.4 and 401.0 nm) and d ! pꢄPh character
(at 404.5 nm) with small oscillator strengths. The tran-
sitions from pPh to metal d orbitals are mediated by
phosphorus.
Fig. 4. The selected HOMO and LUMO orbitals with a-spin for 1.
have a substantial contribution from the free electron
pairs on the phosphorus atom. The LUMO+6 with a-
spin and the LUMO+10 with b-spin are the antibonding
orbital of dz2 ꢀ rCl character. The LUMO+9 with a-
spin and the LUMO+11 with b-spin are the antibonding
orbital of dx2ꢀy2 ꢀ rCl ꢀ rN ꢀ rP character. LUMO,
LUMO + 3 and LUMO + 1 with a-spin, and LUMO+2
and LUMO+3 with b-spin have large participation of p
phosphorus orbitals.
The next experimental bands of 1 and 2 (at 390.8 and
379.6 nm, respectively) can be assigned to the calculated
transitions at 385.5 and 381.4 nm. They have MLCT
ðd ! pꢄpzHÞ character with small contribution of d–d
Table 4
The energy and molar absorption coefficients of experimental ab-
sorption bands for 1 and 2
Band position (nm)
Band position (eV)
e
3.5. UV–Vis spectra of 1 and 2 and electronic spectrum of
1 from the TDDFT calculations
1
507.3
390.8
331.1
263.8
238.0
200.1
2.44
3.17
3.74
4.70
5.21
6.20
350
1040
1620
2200
3900
7200
The complexes under investigation are high spin
systems. The calculations with TDDFT method for
open-shell organic, inorganic and organometallic mole-
cules are still limited but a few studies have already
appeared and supported the TDDFT method to be
applicable for such systems giving good assignment of
experimental spectra [29–33]. There are also several
works performed with this method for 5d-metal (in-
cluding rhenium complexes) in which good correlations
between experimental and calculated results have been
confirmed [34–40].
2
547.8
379.6
338.4
269.0
229.0
213.0
2.26
3.27
3.66
4.61
5.41
5.82
400
1220
3700
5470
8910
7330
e, molar absorption coefficient (dm3 molꢀ1 cmꢀ1).

1826
B. Machura et al. / Polyhedron 23 (2004) 1819–1827
Table 5
The most important electronic transitions calculated with the TDDFT method for 1
k (nm)
E (eV)
f
The most important orbital excitations
a-spin
b-spin
H-5ðpClÞ ! LðdÞ
H-2ðpPhÞ ! LðdÞ
Hðdxy Þ ! L þ 3ðpꢄ
407.4
404.5
3.04
3.06
0.0004
0.0028
Þ
Hðdxy Þ ! L þ 8ðpꢄPhÞ
H-3 ðnP þ pPhÞ !PLh ðdÞ
401.0
385.5
381.4
3.09
3.22
3.25
0.0080
0.0113
0.0046
Hðdxy Þ ! L þ 4ðpꢄpzH
Þ
HðdxyÞ ! L þ 6ðdz2Þ
Hðdxy Þ ! L þ 2ðpꢄPh
Þ
Hðdxy Þ ! L þ 10ðdz2Þ
H-1ðpPhÞ ! LðdxzÞ
H-4ðpPhÞ ! LðdxzÞ
376.1
355.3
352.7
351.2
3.30
3.49
3.52
3.53
0.0035
0.0039
0.0033
0.0194
HðdxyÞ ! LðpꢄPh
Þ
H-5ðpClÞ ! L þ 1ðdyzÞ
H-2ðpPhÞ ! L þ 1ðdyzÞ
HðdxyÞ ! L þ 1ðpꢄPh
Þ
314.7
305.6
283.7
3.94
4.06
4.37
0.0266
0.0491
0.0217
HðdxyÞ ! L þ 2ðpꢄpzH
Þ
H-10ðpCl þ ppzHÞ ! L þ 1ðdyzÞ
H-9ðpCl þ ppzH þ pPh þ npÞ ! L þ 1ðdyzÞ
H-9ðpCl þ ppzH þ pPh þ npÞ ! L þ 1ðdyzÞ
H-6ðpPhÞ ! L þ 1ðdyzÞ
280.9
277.0
4.41
4.48
0.0204
0.0253
H-2ðdxzÞ ! L þ 3ðpPꢄh
Þ
H-13ðppzHÞ ! LðdxzÞ
electronic transitions. Owing to the small oscillator
strengths, the three calculated transitions at 376.1, 355.3
and 352.7 nm of pPh ! d and d ! pꢄPh character do not
contribute significantly to the overall shape of the
spectrum. In the experimental spectrum such small
transitions are hidden under the more intense ones.
The experimental bands of 1 and 2 at 331.1 and 338.4
nm, respectively, are attributed to the calculated tran-
sitions at 351.2, 314.7 and 305.6 nm. The first one is a
pCl ! d(LMCT) transition, the two others have
d ! pꢄpzH(MLCT) character.
Acknowledgements
The GAUSSIAN 03 calculations were carried out in
the WrocŁaw Centre for Networking and Supercom-
puting, WCSS, WrocŁaw, Poland, under calculational
grant No. 51/96.
Crystallographic part was financed by funds allocated
by the Ministry of Scientific Research and Information
Technology to the Department of X-ray Crystallogra-
phy and Crystal Chemistry, Institute of General and
ꢀ ꢀ
Ecological Chemistry, Łodz University of Technology.
The authors thank G. Jakob from University of
Mainz for magnetic measurement.
The absorption bands recorded at 263.8 and 269.0
nm for 1 and 2, respectively, are assigned to the calcu-
lated transitions at 283.7, 280.9 and 277.0 nm with large
oscillator strengths. They are of LMCT (ppzH ! d;
pCl ! d and pPh ! d) character.
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