The syntheses, crystal, molecular and electronic structures of two polymorphs of [ReCl2(N2COPh)(C3N 2H4)(PPh3)2] and [ReCl 2(N2COPh)(py)(PPh3)<su

Article abstract of DOI:10.1016/j.poly.2003.07.010

The [ReCl₂(η²-N₂COPh-N′,O) (PPh₃)₂] complex reacts with pyridine and pyrazole to give [ReCl₂(N₂COPh)(py)(PPh₃)₂] and [ReCl₂(N₂COPh)(C<

Full text of DOI:10.1016/j.poly.2003.07.010

Polyhedron 22 (2003) 3307–3313
www.elsevier.com/locate/poly
The syntheses, crystal, molecular and electronic structures of two
polymorphs of [ReCl2(N2COPh)(C3N2H4)(PPh3)2]
and [ReCl2(N2COPh)(py)(PPh3)2] complexes
a,
a
b
c
Jan O. Dziꢀegielewski *, S. Michalik , R. Kruszynski b,1, T.J. Bartczak , J. Kusz
a
Department of Inorganic and Radiation Chemistry, Institute of Chemistry, University of Silesia, 9th Szkolna St., 40-006 Katowice, Poland
b
X-ray Crystallography Laboratory, Institute of General and Ecological Chemistry, Technical University of Łoꢀdꢀz,
_
116 Zeromski St., 90-924 Łoꢀdꢀz, Poland
Institute of Physics, University of Silesia, 4th Uniwersytecka St., 40-006 Katowice, Poland
c
Received 22 April 2003; accepted 28 July 2003
Abstract
The [ReCl2(g2-N2COPh–N0 ,O)(PPh3)2] complex reacts with pyridine and pyrazole to give [ReCl2(N2COPh)(py)(PPh3)2]
and [ReCl2(N2COPh)(C3N2H4)(PPh3)2], respectively. Two monoclinic polymers of [ReCl2(N2COPh)(C3N2H4)(PPh3)2] and
1
[ReCl2(N2COPh)(py)(PPh3)2] have been characterized by IR, UV–Vis, H NMR, magnetic measurements and X-ray structure.
Ó 2003 Elsevier Ltd. All rights reserved.
Keywords: Rhenium; Organodiazenido; X-ray structures; Electronic structures
1. Introduction
arsine ligands in boiling methanol leads to the neutral
dinitrogen rhenium complexes [5,6].
Organodiazenido ligands, as well as other ligands
which form metal–nitrogen multiple bonds, have been of
great interest in recent years because of their amphoteric
nature and close relationship to dinitrogen and nitrosyl
ligands. Similarly to the nitrosyl group, the organodia-
zenido ligand (–NNR) displays a variety of geometries:
singly bent, doubly bent and bridging. Structural and
synthetic studies of organodiazenido transition metal
complexes have shown that the chemistry of these
compounds is varied and interesting [1–3].
Considering that the pyrazole-type ligands are an
important group in organometallic chemistry, and pyr-
azolate or pyrazole metal complexes have attracted
substantial interest considering their catalytic activity,
we have decided to investigate the reactivity of [Re-
Cl2(g2-N2COPh–N0 ,O)(PPh3)2] towards pyrazole. In
this paper, we report the synthesis, spectroscopic char-
acterization and structural determination of two poly-
morphs of [ReCl2(N2COPh)(C3N2H4)(PPh3)2] (1 and
2). In order to compare [ReCl2(N2COPh)(py)(PPh3)2]
(3) with the pyrazole complexes, we have determined its
X-ray and electronic structure.
The [ReCl2(g2-N2COPh–N0 ,O)(PPh3)2] complex is a
precursor to a variety of organodiazenido and dinitro-
gen complexes. [ReCl2(g2-N2COPh–N0 ,O)(PPh3)2] re-
acts with neutral donor ligands L, such as acetonitrile
and pyridine in benzene, giving organodiazenido species
[ReCl2(N2COPh)L(PPh3)2] [4], whereas refluxing of
[ReCl2(g2-N2COPh–N0 ,O)(PPh3)2] with phosphine and
2. Experimental
2.1. General procedure
The syntheses were carried out under argon atmo-
sphere. All solvents were of reagent grade and were used
as received. Ammonium perrhenate, triphenylphosphine
and pyrazole were purchased from Aldrich and used as
* Corresponding author. Tel.: +48-32-258-2441; fax: +32-259-9978.
E-mail addresses: jod@tc3.ich.us.edu.pl (J.O. Dziegielewski), ta-
dekbar@ck-sg.p.lodz.pl (T.J. Bartczak).
1
A holder of the Foundation for Polish Science (FNP) scholarship.
0277-5387/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2003.07.010

3308
J.O. Dziꢀegielewski et al. / Polyhedron 22 (2003) 3307–3313
received. The [ReCl2(g2-N2COPh–N0 ,O)(PPh3)2] and
[ReCl2(N2COPh)(py)(PPh3)2] (3) complexes were pre-
pared according to the literature methods [4].
x–2h scan mode (compounds 1 and 2) and on a KM-4-
CCD automatic diffractometer equipped with a CCD
detector and with the x scan mode (compound 3). For
compound (3) 49 s exposure time was used, all of Ewald
sphere was collected up to 2h ¼ 50:21° and the unit cell
parameters were determined from least-squares refine-
ment of the setting angles of the 2297 strongest reflec-
tions. Graphite monochromated Mo Ka radiation
Infrared spectra were recorded on a Nicolet Magna
560 spectrophotometer in the spectral range 4000–400
cmꢀ1 with the samples in the form of potassium bromide
pellets. Electronic spectra were measured on a Lab Al-
liance UV–Vis 8500 spectrophotometer in the range
800–220 nm in deoxygenated dichloromethane solution.
The magnetic susceptibility was determined using a su-
perconducting quantum interference device (SQUID,
Quantum Design) magnetometer.
ꢁ
(k ¼ 0:71073 A) was used and the measurements were
carried out at room temperature 293.0(2) K. Details
concerning crystal data and refinement for 1, 2 and 3 are
given in Table 1.
Lorentz, polarization, decay and absorption correc-
tions were applied for the determined compounds (em-
pirical absorption [7] for 1, 2 and numerical absorption
[8] for 3). The structures were solved by the Patterson
superposition method and subsequently completed by
difference Fourier synthesis. All the non-hydrogen at-
oms were refined anisotropically using full-matrix, least-
squares technique. The hydrogen atom positions were
found from difference Fourier syntheses, and they were
treated as ‘‘riding’’ on the adjacent atom and refined
with as individual isotropic temperature factor equal 1.2
times the value of the equivalent temperature factor of
the parent atom. SHELXS97 [9], SHELXL97 [10] and
SHELXTL [11] programs were used for all the calcula-
tions. Atomic scattering factors were incorporated in the
computer programs.
2.2. Preparation of (1)
[ReCl2(g2-N2COPh–N0 ,O)(PPh3)2] (1 g, 1.1 mmol)
was added to pyrazole (0.5 g, 7.2 mmol) in methanol (50
ml) and the reaction mixture was refluxed for 48 h. The
green crystalline precipitate of 1 was collected by fil-
tration and crystals suitable for X-ray structure deter-
mination were obtained by recrystallization from a
mixture of chloroform and methanol.
1
Yield 70%: H HNMR (CD2Cl2 293 K): 13.2 (1H, s
N–H) 6.8–7.72 (m, 38H, CH of ArH and CH in pyraz-
ole) 31P NMR: )4.37 ppm. IR of 1 (KBr, cmꢀ1) 3338 (s),
3066 (m), 1648 (w), 1592 (s), 1566 (s), 1556 (s), 1483 (s),
1465 (s), 1434 (s), 1313 (m), 1261 (vs), 1172 (m), 1091 (s),
1062 (m), 858 (m), 743 (m), 693 (s), 645 (s), 602 (s), 520
(s), 493 (s). Anal. Calc. for C46H39N4OCl2P2Re (1): C
56.21; H 4.00; Cl 7.21; N 5.70; O 1.63; P 6.30; Re 18.94.
Found: C 56.5; H 4.0; N 5.55%.
3. Results and discussion
The reaction of [ReCl2(g2-N2COPh–N0 ,O)(PPh3)2]
with pyrazole and pyridine results in the opening
of the chelate ring through displacement of the coor-
2.3. Preparation of (2)
A solution of pyrazole (0.25 g, 3.6 mmol) in acetone
(10 ml) was added to [ReCl2(g2-N2COPh–N0 ,O)
(PPh3)2] (0.5 g, 0.55 mmol) suspended in acetone (30
ml) and stirred at room temperature for 48 h. The
green precipitate of 2 was filtered and crystals suitable
for X-ray structure determination were obtained by
recrystallization from a mixture of chloroform and
methanol.
dinated carbonyl group by the
N donar ligand
(Eq. (1)) and leads to the [ReCl2(C3N2H4)(N2COPh)
(PPh3)2] and [ReCl2(py)(N2COPh)(PPh3)2] complexes,
respectively.
1
Yield 75%: H HNMR (CD2Cl2 293 K): 13.2 (1H, s
N–H) 6.8–7.7 (m, 38H, CH of ArH and CH in pyrazole)
31P NMR: )4.38 ppm. IR of 2 (KBr, cmꢀ1) 3338 (s), 3066
(m), 1648 (w), 1592 (s), 1566 (s), 1556 (s), 1483 (s), 1465
(s), 1434 (s), 1313 (m), 1261 (vs), 1172 (m), 1091 (s), 1062
(m), 858 (m), 743 (m), 693 (s), 645 (s), 602 (s), 520 (s), 493
(s). Anal. Calc. for C46H39N4OCl2P2Re (1): C 56.21; H
4.00; Cl 7.21; N 5.70; O 1.63; P 6.30; Re 18.94%. Found:
C 56.5; H 4.0; N 5.5%
ð1Þ
Refluxing of [ReCl2(g2-N2COPh–N0 ,O)(PPh3)2] with
pyrazole in methanol leads to the polymorph 1, whereas
the reaction of [ReCl2(N2COPh)(PPh3)2] with pyrazole in
acetone at room temperature gives the polymorph 2. The
overall molecular geometry of 2 is similar to that of 1.
The weighted r.m.s. (root mean square) deviation for all
2.4. Crystal structure determination and refinement
ꢁ
The three-dimensional X-ray intensity data were
collected on a Kuma KM-4 diffractometer with the
atoms of superpositioned molecules is 1.280 A. The main
difference between the polymorphs is the arrangement of

J.O. Dziꢀegielewski et al. / Polyhedron 22 (2003) 3307–3313
3309
Table 1
Crystal data and structure refinement details for 1, 2 and 3
1
2
3
Empirical formula
Formula weight
Temperature (K)
Crystal system
C
982.85
46H39N4OCl2P2Re
C46H39N4OCl2P2Re
982.85
293(2)
C48H40Cl2N3OP2Re
993.87
293(2)
293(2)
monoclinic
P21=c
monoclinic
P21=c
triclinic
ꢂ
Space group
Unit cell dimensions
P1
ꢁ
a (A)
11.756(2)
12.292(2)
29.219(6)
90
12.754(3)
17.249(3)
19.318(4)
90
11.2949(9)
13.4638(12)
14.9011(14)
84.435(7)
ꢁ
b (A)
ꢁ
c (A)
a (°)
b (°)
c (°)
100.87(3)
90
99.90
90
88.809(7
71.828(8)
2142.8(3)
3
ꢁ
Volume (A )
4146.5(13)
4
1.574
4186.6(15)
4
1.559
Z
2
1.540
Density (calc., Mg/m3)
Absorption coefficient (mmꢀ1
F ð000Þ
)
3.178
1960
3.147
1960
3.075
992
Crystal dimensions (mm)
0.13 ꢂ 0.13 ꢂ 0.05
1.42–23.51
ꢀ12 6 h 6 13
0 6 k 6 13
ꢀ31 6 l 6 0
5955
0.16 ꢂ 0.16 ꢂ 0.39
2.01–25.05
0 6 h 6 15
ꢀ20 6 k 6 0
ꢀ22 6 l 6 22
7763
0.28 ꢂ 0.07 ꢂ 0.01
3.32–25.10
ꢀ13 6 h 6 13
ꢀ16 6 k 6 16
ꢀ17 6 l 6 17
24 434
h range for data collection (°)
Index ranges
Reflections collected
Completeness to 2h (%)
Absorption correction
89.9
96.1
99.8
empirical
0.8573 and 0.6828
5817 (Rint ¼ 0:0428)
5817/0/506
1.079
empirical
0.6329 and 0.3733
7391 (Rint ¼ 0:0302)
7391/0/505
1.215
numerical
0.9582 and 0.4819
7610 (Rint ¼ 0:0874)
7610/0/514
1.153
Maximum and minimum transmission
Independent reflections
Data/restraints/parameters
Goodness-of-fit on F 2
Final R indices [I > 2rðIÞ]
R1 ¼ 0:0601
wR2 ¼ 0:1306
R1 ¼ 0:1096
wR2 ¼ 0:1749
1.941 and )0.981
R1 ¼ 0:0488
wR2 ¼ 0:1023
R1 ¼ 0:0798
wR2 ¼ 0:1289
0.733 and )1.558
R1 ¼ 0:0582
wR2 ¼ 0:1096
R1 ¼ 0:0672
wR2 ¼ 0:1139
1.570 and )0.821
R indices (all data)
ꢀ3
ꢁ
Largest difference peak and hole (e A
)
the PPh3 substituents. Molecule 2, in comparison to 1,
has rotated PPh3 substituents around the P–Re bond by
about 41° and 16° for Pð1Þ and Pð2Þ, respectively, thus
weighted r.m.s. deviation for all atoms of superposi-
ꢁ
tioned molecules except Ph substituents is 0.205 A.
The r.m.s deviation of the superpositioned Re envi-
ꢁ
ronment is 0.093 A, which suggests that differences in
structure are caused rather by packing effects than
electronic properties. The unit cell parameters, crystal
data and details concerning the refinement of structures
1, 2 and 3 are given in Table 1. The perspective view of 1
and 2 together with the atom numbering scheme is
shown in Figs. 1 and 2 presents the perspective drawing
of 3. The structures of 1, 2 and 3 are stabilized by
multiple weak intramolecular hydrogen bonds whose
geometries are given in Table 2. The intramolecular
hydrogen bonding scheme, as expected, is different in
every structure. In each structure one intermolecular
weak C–H ꢁ ꢁ ꢁ Cl hydrogen bond can be found [12–14]
Fig. 1. ORTEP view of the structure of 1 and 2 showing 50% thermal
ellipsoids.
which creates infinite hydrogen bonded chains with zig-
zag geometry along y-axis in 1, linear geometry along
the x-axis in 2 and hydrogen bonded dimers in 3. The
packing diagrams of 1, 2 and 3 are depicted in Figs. 3–5,
respectively.
ꢁ
(C ꢁ ꢁ ꢁ Cl distance in the range 3.24–3.74 A and C–
H ꢁ ꢁ ꢁ Cl angle 123.6°–1154.5°) but in 1 it links C(32) ꢁ ꢁ ꢁ
Cl(2# ꢀx; y ꢀ 1=2; ꢀz þ 1=2) atoms, in 2 C(45) ꢁ ꢁ ꢁ Cl(2#
x ꢀ 1; y; z) atoms and in 3 C(45) ꢁ ꢁ ꢁ Cl(2# ꢀx; ꢀy; ꢀz)

3310
J.O. Dziꢀegielewski et al. / Polyhedron 22 (2003) 3307–3313
Fig. 2. ORTEP view of the structure 3 showing 50% thermal ellipsoids.
Fig. 3. The packing diagram of 1.
The coordination geometry about the rhenium centre
in 1, 2 and 3 exhibits mutually trans triphenylphosphine
molecules, minimizing steric congestion, and chloride
donors trans to the monodentate organodiazenido ligand
and to the pyrazole or pyridine molecule which has dis-
placed the carbonyl oxygen of the diazenido substituent.
The selected bond lengths and angles for 1, 2 and 3 are
summarized in Table 3. The angular distortions from an
ideal octahedron in 1, 2 and 3 are caused by the presence
of the multiply bonding ligand (–NNR) in the cis posi-
tion to the N-heterocycle ring. The Re(1)–N(1)–N(2)
angles are essentially linear and the N(1)–N(2)–C(40)
are near 120°, indicating that 1, 2 and 3 are Ôsingly bentÕ
benzoyldiazenido complexes. The bond valences were
computed as mij ¼ exp½ðRij ꢀ dijÞ=Bꢃ [15–17], where Rij
is the bond-valence parameter (in the formal sense Rij is
the single-bond length between i and j atoms) [18]. The
Fig. 4. The packing diagram of 2.
R
ReꢀN, RRe–P, RRe–Cl values were taken as 2.06, 2.46 and
pounds 1, 2 and 3, which means that rhenium substitu-
ents in compound 1 are more weakly bonded than in
compound 2 and more strongly bonded than in com-
pound 3. The short Re–N(1) and N(1)–N(2) distances
2.23 [15] respectively and the value of B was taken as 0.37
[16]. The computed bond valences of the rhenium vRe-j are
gathered in Table 4. The total valence of Re(1) is 6.36,
6.44 and 6.24 v.u. (valence units), respectively for com-
Table 2
ꢁ
Hydrogen-bonding geometry for 1, 2 and 3 (A, °)
1
2
3
D–HꢁꢁꢁA
HꢁꢁꢁA DꢁꢁꢁA
D–HꢁꢁꢁA D–HꢁꢁꢁA
HꢁꢁꢁA DꢁꢁꢁA
D–HꢁꢁꢁA D–HꢁꢁꢁA
HꢁꢁꢁA DꢁꢁꢁA
2.61 3.463(9) 152.1
3.512(11) 137.3
D–HꢁꢁꢁA
N4–H4AꢁꢁꢁO1
N4–H4AꢁꢁꢁN1
C2–H2BꢁꢁꢁC11
C8–H8AꢁꢁꢁN3
C8–H8AꢁꢁꢁN4
1.81
2.56
2.66
2.60
2.55
2.707(15) 172.0
N4–H4NꢁꢁꢁO1
1.74
2.62
2.75
2.700(13) 177.7
C8–H8AꢁꢁꢁC12
2.977(15) 109.2
3.481(15) 144.4
3.173(19) 118.9
3.41(2) 148.2
3.74(3) 154.5
3.418(14) 123.6
3.474(15) 132.4
3.244(16) 112.3
3.632(14) 143.0
N4–H4NꢁꢁꢁN1
C2–H2AꢁꢁꢁC12
3.035(10) 106.8
3.630(11) 152.2
3.274(12) 138.6
3.336(13) 142.8
3.554(11) 146.3
3.534(10) 145.1
3.502(10) 153.2
3.170(12) 153.2
C26–H26AꢁꢁꢁC11 2.77
C48–H37AꢁꢁꢁOl 2.60
C48–H37AꢁꢁꢁN1 2.55
C44–H41AꢁꢁꢁCll 2.57
C43–H48AꢁꢁꢁN2 2.46
3.152(10) 118.9
3.039(9) 113.1
3.169(7) 122.6
2.788(10) 100.7
C18–H18AꢁꢁꢁN1 2.49
C18–H18AꢁꢁꢁN2 2.52
C24–H24AꢁꢁꢁC12 2.72
C33–H33AꢁꢁꢁC12 2.70
C36–H36AꢁꢁꢁC12 2.62
C39–H39AꢁꢁꢁC11 2.70
C24–H24AꢁꢁꢁC12 2.85
C36–H36AꢁꢁꢁC11 2.79
C36–H36AꢁꢁꢁC12 2.75
C39–H39AꢁꢁꢁC11 1.76
C45–H45AꢁꢁꢁC12 2.82

J.O. Dziꢀegielewski et al. / Polyhedron 22 (2003) 3307–3313
3311
Table 4
Rhenium bond valences mRe-j (v.u.)
Bond
Re(1)–Cl(1)
1
2
3
0.60
0.64
0.59
0.99
0.94
2.52
0.76
0.56
0.56
0.95
0.97
2.41
0.79
Re(1)–Cl(2)
Re(1)–P(1)
Re(1)–P(2)
Re(1)–N(1)
Re(1)–N(3)
0.59
0.96
0.96
2.47
0.78
bond lengths and N(1)–N(2)–C(37), M–N(1)–N(2) an-
gles in 1, 2 and 3 are in good accordance with values
found by others for Ôsingly bentÕ organodiazenido com-
plexes, which are shown in Table 5. The Re–Cl(1) adn
Re–Cl(2) bond lengths of 1, 2 and 3 are considerable
longer in comparison with the Re–Cl distances of trans-
ꢁ
[ReCl4(PPh3)2] [2.3203(8) and 2.3300(8) A] [25] The sig-
nificant lengthening of Re–Cl results from the trans lo-
cation of chloride donors to the strongly p-interacting
benzoyldiazenido group and pyrazole or pyridine ligand.
The Re–Cl(1) distance trans to the NNR ligand is shorter
than the Re–Cl(2) distance in the trans position to the
pyrazole or pyridine molecule, which indicates the
stronger trans influence of the heterocycle molecules in
comparison with the benzoyldiazenido group in 1, 2 and
3. According to the calculated valences, the Re–Cl bonds
are the weakest in the Re coordination sphere. the Re–
Fig. 5. The packing diagram of 3.
Table 3
ꢁ
The selected bond lengths (A) and angles (°) for 1, 2 and 3
1
2
3
Bond lengths
Re(1)–Cl(1)
Re(1)–Cl(2)
Re(1)–P(1)
Re(1)–P(2)
Re(1)–N(1)
Re(1)–N(3)
2.416(3)
2.426(3)
2.475(3)
2.461(4)
1.725(11)
2.150(10)
2.397(2)
2.424(2)
2.465(2)
2.484(2)
1.717(6)
2.159(7)
2.4268(18)
2.4457(19)
2.4800(19)
2.4873(19)
1.735(6)
ꢁ
N(3) bond lengths in 1, 2 and 3 (2.068–2.151 A) are in
good accordance with appropriate values found previ-
ously in similar rhenium compounds containing coordi-
nated pyrazole and pyridine [19,20], and these bonds are
slightly stronger than Re–Cl bonds. The Re–P bonds are
also unexceptional, and from a formal point of view may
be consider as single bonds, weaker than Re(1)–N(1), and
stronger than the other bonds.
2.174(5)
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)–P(1)
N(3)–Re(1)–P(1)
Cl(1)–Re(1)–P(1)
Cl(2)–Re(1)–P(1)
N(1)–Re(1)–P(2)
N(3)–Re(1)–P(2)
Cl(1)–Re(1)–P(2)
Cl(2)–Re(1)–P(2)
P(1)–Re(1)–P(2)
N(2)–N(1)–Re(1)
C(39)–N(3)–Re(1)
N(4)–N(3)–Re(1)
92.7(4)
94.0(3)
92.9(2)
178.3(4)
85.6(3)
89.4(4)
177.5(2)
84.1(2)
94.2(2)
178.77(19)
88.30(15)
90.14(19)
176.69(15)
88.63(7)
92.9(2)
In contrast to the starting [ReCl2 (g2-N2COPh–N0,O)
(PPh2)3] complex, the infrared spectra of 1, 2 and 3 show
several bands in the range of 1550–1650 cmꢀ1 range.
These bands are assigned to m(N@N), m(C@N) and
m(C@O), confirming the opening of the chelate ligand and
the presence of a pyrazole or pyridine molecule [3]. All the
complexes contain triphenylphosphine ligands and thus
they show the charecteristics pair of bands at approxi-
mately 1430 and 1480 cmꢀ1, and typically the lower fre-
quency band is the more intensive one. The strong band at
3338 cmꢀ1 for 1 and 2 assignable to N–H vibrations, and
the 1H NMR specturm for 1 and 2 exhibiting a singlet at
13.2 ppm, confirm the presence of a terminal pyrazole
molecule in the coordination spheres of these compounds
[23,24]. 1 and 2 dissolved in dichloromethane give iden-
tical UV–Vis spectra, So the electronic structures of both
polymorphs are the same. Table 6 presents the positions,
molar absorption coefficients of electronic bands and the
electronic transitions assigned to the bands of 1 and 3.
Considering the diamagnetism of complexes 1 and 3
and the linear Re@N@NAPh bond systems, it may be
177.3(3)
92.28(13)
94.5(4)
171.6(2)
87.70(8)
92.6(2)
91.7(3)
90.10(19)
89.15(8)
87.89(8)
91.7(2)
88.34(16)
87.25(7)
90.27(7)
90.0(2)
85.28(12)
89.70(12)
93.4(4)
88.3(3)
89.67(19)
86.60(8)
87.88(8)
175.75(7)
171.6(6)
133.1(7)
132.2(7)
91.53(16)
89.93(7)
89.71(7)
177.18(7)
170.7(5)
86.84(12)
90.02(14)
172.10(13)
168.3(9)
134.7(10)
120.5(8)
suggest extensive delocalization and multiple bonding
throughout the N2COPh unit. This observation is con-
firmed by virtual planarity of the entire Re–N–NCOPh
grouping, by linearity of Re–N–N unit and by the value
of the valence parameter being larger than 2 for the
Re(1)–N(1) bond. These groups are the stronger bonded
Re substituents. The Re–N(1), N(1)–N(2) and N(2)–C

3312
J.O. Dziꢀegielewski et al. / Polyhedron 22 (2003) 3307–3313
Table 5
Bond distances and angles for complexes with Ôsingly bentÕ organodiazenido ligands
ꢁ
M–N (A)
ꢁ
N–N (A)
ꢁ
N–C (A)
ꢁ
N–N–C (A)
ꢁ
M–N–N (A)
Complex
Ref.
[ReCl2(N2COPh)(PPhMe2)3]
1.74(2)
1.756(7)
1.72(2)
1.22(3)
1.25(1)
1.28(2)
1.25(1)
1.255(10)
1.42(1)
1.40(1)
1.44(2)
1.40(1)
1.369(12)
124(2)
170(2)
[21]
[3]
[ReCl2(PPh3)2(N2COPh)(NCCH3)]
[ReCl2(PPh3)2(NNCO2CH3)(C6H5N)]
[ReCl2(PPh3)2(NNC6H4ꢀ-o-Br)(NH3)]
[MoCl2(N2COPh)(dpe)2]
120.5(7)
123.8(11)
119.9(6)
116.7(7)
172.1(6)
166.9(12)
167.1(12)
172.1(6)
[3]
[3]
1.755(7)
1.813(7)
[22]
Table 6
Positions, molar absorption coefficients of electronic bands and the electronic transitions assigned to the bands for 1 and 3
2
3
Band position (cmꢀ1
)
e
Assignment
Band position (cmꢀ1
)
e
Assignment
3
16 299
26 990
199
1A1 ! T1
16 299
26 990
199
5d ! pꢄpyridine
1
1
10 205
1A1 ! T1
10 205
1A1 ! T1
5d ! pꢄpyrazole
5d ! pꢄN@NAC
5d ! pꢄpyridine
1
26 212
36 231
8734
5d ! pꢄN@NAC
5d ! pꢄpyrazole
26 212
36 231
8734
1A1 ! T2
p ! pꢄC
6H5–N
p ! pꢄpyridine
1
33 984
1A1 ! T2
33 984
p ! pꢄpyrazole
6H5–N
p ! pꢄC
6H5–N
p ! pꢄpyrazole
42 918
54 107
pCb
! 3d
42 918
54 107
pCb
! 3d
6H5–N
assumed that the N@NAPh ligand is a donor of four
electrons, and the central ion has a d6 electron config-
uration [1]. Taking into consideration the possible d–d
transitions in the pseudo-octahedral ligand field, the
transition connected with charge transfer and internal
electron transitions in the ligands, in spite of superim-
posing of these bands, were attributed qualitatively,
according to the literature data. Charge transfer transi-
tions may only be MLCT ones (d6), and pyridine has a
higher p-acceptor ability than pyrazole, because pyri-
dine weakens the Re–Cl bond in the trans position to a
higher degree than pyrazole.
Scientific Research to the Institute of General and
ꢀ
Ecological Chemistry, Technical University of Łodz´.
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4. Supplementary data
Supplementary data can be obtained free of charge
from The Director, CCDC, 12 Union Road, Cambridge
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