Tricarbonylrhenium(I) and -technetium(I) complexes with bis(2-pyridyl)phenylphosphine and tris(2-pyridyl)phosphine

Article abstract of DOI:10.1016/j.poly.2008.09.001

(NEt₄)₂[Re(CO)₃Br₃] or (NEt₄)₂[Tc(CO)₃Cl₃] react with bis(2-pyridyl)phenylphosphine (PPhpy₂) or tris(2-pyridyl)phosphine (Ppy₃) under formation of neutral tricarbonyl complexes of the composition [M(CO)₃X(L)] (M = Re, X = Br; M = Tc, X = Cl; L = PPhpy₂ or Ppy₃). In all isolated products, the ligands coordinate solely via two of their nitrogen atoms. All attempts to force a tripodal coordination of the phosphinopyridines failed. Removal of the bromo ligands from (NEt₄)₂[Re(CO)₃Br₃] by the addition of AgNO₃ in THF/water, and subsequent reaction of the resulting [Re(CO)₃(THF)₃](NO₃)with Ppy₃ yielded the complex [Re(CO)₃(NO₃)(Ppy₃-N,N′)] with a monodentate coordinated nitrato ligand. The products have been characterized spectroscopically and by X-ray structure analyses.

Full text of DOI:10.1016/j.poly.2008.09.001

Polyhedron 27 (2008) 3587–3592
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Tricarbonylrhenium(I) and -technetium(I) complexes with
bis(2-pyridyl)phenylphosphine and tris(2-pyridyl)phosphine
*
Sonia A. Saucedo Anaya, Adelheid Hagenbach, Ulrich Abram
Institut für Chemie und Biochemie, Freie Universität Berlin, Fabeckstr. 34-36, D-14195 Berlin, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
(NEt4)2[Re(CO)3Br3] or (NEt4)2[Tc(CO)3Cl3] react with bis(2-pyridyl)phenylphosphine (PPhpy2) or tris(2-
pyridyl)phosphine (Ppy3) under formation of neutral tricarbonyl complexes of the composition
[M(CO)3X(L)] (M = Re, X = Br; M = Tc, X = Cl; L = PPhpy2 or Ppy3). In all isolated products, the ligands coor-
dinate solely via two of their nitrogen atoms. All attempts to force a tripodal coordination of the phosph-
inopyridines failed. Removal of the bromo ligands from (NEt4)2[Re(CO)3Br3] by the addition of AgNO3 in
THF/water, and subsequent reaction of the resulting [Re(CO)3(THF)3](NO3)with Ppy3 yielded the complex
[Re(CO)3(NO3)(Ppy3-N,N0)] with a monodentate coordinated nitrato ligand. The products have been char-
acterized spectroscopically and by X-ray structure analyses.
Received 12 August 2008
Accepted 2 September 2008
Available online 28 October 2008
Keywords:
Technetium
Rhenium
Carbonyls
Polypyridylphosphines
Ó 2008 Elsevier Ltd. All rights reserved.
1. Introduction
states, and surprisingly less is known about transition metal com-
plexes with PPhpy2 and Ppy3. Some complexes have been reported
Technetium and rhenium coordination chemistry is of particu-
with low-valent metal ions such as Co2+, Ru2+ or Rh+ [3c,5]. PPhpy2
and Ppy3 can coordinate as N,N-chelates, in a P,N,N-bridging mode
or as tripodal ligands. Additionally they form homobinuclear
[4,5c,5f,5g] or heterobinuclear [6] complexes with soft metal ions.
The less favorable tripodal (N,N0,N00) coordination mode of Ppy3
has been reported for complexes of the type [M(Ppy3)2]2+
(M = Mn, Fe, Ru, Co, Ni, Cu, Zn) and [M(CO)n(NO)3ꢀn(Ppy3)](3ꢀn)+
(M = Mo, Cr, W) [7].
There are only a few examples of technetium and rhenium com-
pounds with this kind of ligands. The first synthesized rhenium
complexes contain PPh2py as bridging ligand [8]. Mononuclear
rhenium or technetium complexes with PPh2py were obtained
with nitrosyl, carbonyl, oxo and nitrido cores [9–11]. Compounds
of the type [M(CO)3X(PPh2py-P)2] and [M(CO)3X2(PPh2py-P)]ꢀ
(M = Tc, X = Cl; M = Re; X = Br) were prepared from (NEt4)2[Tc-
(CO)3Cl3] and (NEt4)2[Re(CO)3Br3], respectively [9]. The nitrosyl
complexes (NBu4)[Tc(NO)Cl4] and [Re(NO)Cl3(PPh3)(OPPh3)] were
reduced by the addition of PPh2py and complexes such as
[Tc(NO)Cl2(PPh2py-P,N)(PPh2py-P)] and [Re(NO)Cl2(PPh2py-P,N)-
(PPh3)] were isolated [10,11]. To the best of our knowledge, there
is only one report about a rhenium complex with a polypyridyl-
phosphine: the carbonyl complex [Re(CO)3Cl(Ppy3-N,N0)] was
prepared from [Re(CO)5Cl] and its structure as N,N-chelate was
predicted on the basis of spectroscopic data [12].
lar interest due to the favorable nuclear properties of 99mTc (E =
c
140 keV, t1/2 = 6.02 h), which is the workhorse in diagnostic nucle-
ar medicine [1], while the bꢀ-emitting rhenium nuclides 186Re and
188Re are under investigation for potential applications in radioim-
munotherapy [2].
The coordination chemistry of 2-pyridylphosphines, particularly
that of PPh2py, has been extensively reviewed since the early 1980s
[3]. A widespread flexibility in its coordination behavior (monoden-
tate versus bidentate, chelating versus bridging) makes this com-
pound interesting for catalytic applications and as building block
for the synthesis of homo- or heterobinuclear complexes [4].
N
P
P
P
N
N
N
N
N
PPh2py
PPhpy2
Ppy3
With a p-acceptor atom and up to three additional r-donor atoms,
2-pyridylphosphines can coordinate to metals in different oxidation
In the present paper, we report general trends in reactions of
(NEt4)2[Tc(CO)3Cl3] and (NEt4)2[Re(CO)3Br3] with PPhpy2 and
Ppy3 together with the structures of the products.
* Corresponding author. Tel.: +49 30 838 54002; fax: +49 30 838 52676.
E-mail address: abram@chemie.fu-berlin.de (U. Abram).
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.09.001

3588
S.A. Saucedo Anaya et al. / Polyhedron 27 (2008) 3587–3592
compounds are compared in Table 1. Main distortions from an
2. Results and discussion
ideal octahedron are mainly due to the restricting bite angle of
the chelating ligand. The mean values of the M-N, M-C and M-X
bond lengths are fully in agreement with the values of structurally
related compounds [9,17].
The reaction of (NEt4)2[Tc(CO)3Cl3] with 1 equiv. of Ppy3 in THF
at room temperature affords [Tc(CO)3Cl(Ppy3-N,N0)]. The complex
crystallizes directly from the mother liquor as colorless needles.
The air and moisture stable complex is moderately soluble in
THF, acetonitrile or CH2Cl2. Strong carbonyl bands at 2032, 1948
and 1882 cmꢀ1 are observed in the IR spectrum of the compound.
PPhpy2 and Ppy3 react with tricarbonyl complexes of rhe-
nium(I) or technetium(I) under coordination of two pyridyl rings.
Complexes of the composition [M(CO)3X(PPhpy2-N,N0)] were ob-
tained in moderate yields from reactions of (NEt4)2[M(CO)3X3]
(M = Tc, X = Cl; M = Re; X = Br) with 1 equiv. of PPhpy2 in acetoni-
trile at room temperature Eq. (1). The respective yields can be in-
creased by concentration of the mother liquors, the purity of the
resulting second crops of products, however, is lower and the sep-
aration from oily side-products causes is difficult.
X
OC
OC
acetonitrile
- 2 NEt4X
N
M
P
P
ð1Þ
(NEt4)2[M(CO)3X3]
+
N
N
N
CO
M = Tc, X = Cl,
M = Re, X = Br
[Re(CO)3Br(PPhpy2-N,N0)] crystallizes from a xylene solution in
form of yellow blocks, while [Tc(CO)3Cl(PPhpy2-N,N0)] was isolated
as colorless needles from the mother liquor. The air and moisture
stable compounds are readily soluble in organic solvents. Strong
bands in the infrared spectrum of the rhenium complex at 2021
and 1909 cmꢀ1 and in that of the technetium compound at 2033
C4
C5
C3
Cl
and 1925 cmꢀ1 can be assigned to the
m(C„O) stretches and confirm
O30
the retention of the fac-[M(CO)3]+ cores. The 99Tc NMR spectrum of
the technetium compound shows a signal at ꢀ990.06 ppm. This
corresponds to a to high-field shift of about 120 ppm with regard
to the resonance of the precursor, which appears at ꢀ868.16
ppm. The finding is in good agreement with the positions of the
99Tc NMR signals of the tricarbonyl complexes mer-[Tc(CO)3-
Br(py)2] (ꢀ946 ppm) and fac-[Tc(CO)3Br(bipy)] (ꢀ1078 ppm)
N2
C6
C30
C1
P
C22
C23
Tc
C21
C20
N12
C10
C11
C16
31
[13]. The P{1H} NMR spectra of [Re(CO)3Br(PPhpy2-N,N0)] and
O20
[Tc(CO)3Cl(PPhpy2-N,N0)] show signals at 1.04 ppm and ꢀ2.24
ppm, respectively. They belong to non-coordinated phosphorus
atoms, while signals of coordinated phosphines typically appear
at lower field in such complexes [5d]. Moreover, the detection of
H6 signals in the 1H NMR spectra at 9.52 ppm for the rhenium com-
plex and at 9.36 ppm for the technetium analog confirm the coor-
dination of two pyridyl rings. The signals of 6H protons, adjacent to
nitrogen in the pyridyl group, generally appear downfield from the
other protons in the phenyl region. For non-coordinated pyridyl-
phosphines, such signals appear as multiplets [14] in the range of
8.60–8.75 ppm (CDCl3) [7b,14,15]. The coordination of the nitrogen
atom, however, displaces the signal positions to 9–10 ppm
[5d,7b,16].
C13
O10
C24
C26
C14
C25
C15
Fig. 1. Ellipsoid representation [26] of [Tc(CO)3Cl(PPhpy2-N,N0)]. Thermal ellipsoids
represent 50% probability. H atoms have been omitted for clarity.
Table 1
Selected bond lengths (Å) and angles (°) in the [M(CO)3X(PPhpy2-N,N0)] complexes
(M = Tc, Re; X = Cl, Br)
[Re(CO)3Br(PPhpy2-N,N0)]
[Tc(CO)3Cl(PPhpy2-N,N0)]
M–C10
M–C20
M–C30
M–N2
M–N12
M–Br/Cl
1.90(1)
1.91(1)
1.91(1)
2.205(8)
2.223(9)
2.635(1)
1.904(4)
1.909(4)
1.906(4)
2.218(3)
2.202(3)
2.499(1)
[Tc(CO)3Cl(PPhpy2-N,N0)] as well as [Re(CO)3Br(PPhpy2-N,N0)]
have been also characterized by X-ray structure analysis. Their
structures are isotypic and the coordination environments of the
metal atoms are slightly distorted octahedra with the carbonyl li-
gands in facial configuration. PPhpy2 coordinates with the two
nitrogen atoms forming six-membered chelate rings. Chlorine or
bromine atoms occupy the remaining coordination sites. Fig. 1
shows an ellipsoid representation of the technetium complex.
The structure of the rhenium analog is virtually identical and the
same atomic labeling scheme has been applied. Therefore, it is
not shown separately. Selected bond lengths and angles of both
C30–M–C20
C30–M–N2
C20–M–N12
N2–M–N12
C10–M–X
89.1(5)
95.4(4)
91.6(4)
83.9(3)
175.6(4)
89.1(2)
91.8(1)
95.4(1)
83.7(1)
175.0(1)
The atomic labeling scheme of the technetium complex in Fig. 1 has also been
applied for the rhenium compound.

S.A. Saucedo Anaya et al. / Polyhedron 27 (2008) 3587–3592
3589
The latter two values refer to a broad, splitted
m
(C„O) band. The 99Tc
[M(CO)3]+ centers to bind to aromatic amines, which has been
demonstrated previously and finds application in the labeling of
histidine-rich protein sites [18,19]. A simple explanation for our
observation, that the formation of species of the composition
[M(CO)3(Ppy3-N,N0,N00)]+ (M = Re, Tc) is less favored, however, can-
not be given in the light that a number of transition metal com-
plexes with N3-tripodal Ppy3 ligands are reported, and also the
isotypic molybdenum(0) complex [Mo(CO)3(Ppy3-N,N0,N00)] has
been isolated and characterized by X-ray crystallography [7]. In
the case of the corresponding technetium and rhenium complexes,
obviously charge compensation by the coordination of an anionic
ligand is preferred. This assumption is supported by the results
of our attempt to support tripodal coordination by the removal
of all halide ligands from the metal atom.
NMR signal is observed at ꢀ988.42 ppm, which is almost perfectly
the value, which was observed for [Tc(CO)3Cl(PPhpy2-N,N0)] and
strongly suggests a bidentate N,N0 coordination mode also for
Ppy3 in the technetium complex under study. The 1H NMR signals
of the H6 protons appear at 9.36 and 8.99 ppm with a 2:1 ratio and,
thus, support this suggestion. [Tc(CO)3Cl(Ppy3-N,N0)] crystallizes as
a racemic twin in the orthorhombic space group Pna21 with two
molecules per asymmetric unit. The Flack parameter has a value
of 0.56(5). All attempts to refine the structure in the corresponding
centrosymmetric space group Pnma were not successful. A slightly
distorted octahedron with facial configuration of the carbonyl li-
gands represents the coordination environment of the technetium
atom as is shown in Fig. 2. Ppy3 coordinates solely via two nitrogen
atoms and the sixth coordination position is occupied by a chloro
ligand. Thus, the structure is isotypic with the [M(CO)3X(PPhpy2-
N,N0)] (M = Tc, Re; X = Cl, Br) complexes discussed above and in
agreement with the bonding mode, which was proposed for
analogous rhenium complex on the basis of spectroscopic data
[12]. There are only marginal differences in the bond lengths and
angles (Table 2). The position of the nitrogen atom of the non-coor-
dinated pyridyl ring was derived on the basis of the thermal
parameters.
In order to avoid the co-coordination of halide, we added
3 equiv. of the AgNO3 to a solution of (NEt4)2[Re(CO)3Br3] in
water/THF or water/MeOH mixtures. After removal of the precipi-
tated AgBr, the remaining solution, which mainly contains the
[Re(CO)3(OH2)3]+ cation, was brought to dryness. The resulting oil
was redissolved in THF and 1 equiv. PPy3 was added. The mixture
was stirred for 1 h at room temperature Eq. (2). Colorless crystals
of [Re(CO)3(NO3)(Ppy3-N,N0)] deposited from the yellow mother
liquor upon standing for 2 days. The compound is only sparingly
soluble in water or organic solvents. Its IR spectrum shows two
strong carbonyl bands at 2029 and 1913 cmꢀ1. The N–O frequency
In all our reactions of (NEt4)2[M(CO)3X3] complexes with
PPhpy2 and Ppy3, we never observed the coordination of the phos-
phine (i) as monodentate phosphorus donor as previously ob-
served in (NEt4)[Re(CO)3Br2(PPh2py-P)] [9], (ii) as P,N chelate, or
(iii) in a tripodal N,N0,N00 arrangement. The first two facts can be ex-
plained by the preferred formation of the more stable six-mem-
bered chelate rings and the well-known high tendency of
of the coordinated NO3 ligand appears at 1281 cmꢀ1 and is in
ꢀ
agreement with values of the similar nitrato complexes
(NEt4)[ReBr2(CO)2(NO3)NO] and (NMe4)[Re(CO)2(NO3)3NO] [20].
A single-crystal diffraction study on [Re(CO)3(NO3)(Ppy3-N,N0)]
confirms the coordination of a nitrato ligand and the role of Ppy3
THF
OH2
Re
Br
Re
CO
OC
OC
H2O/THF
OC
OC
OC
4 2 OC
THF
THF
THF
OH2
OH2
Br
Br
Re
(NO3)
(NEt )
(NO3)
- 3 AgBr
- 2 (NEt4)(NO3)
CO
CO
O
ð2Þ
N
O
O
THF
N
N
OC
OC
OC
OC
N
THF
THF
N
Re
P
Re
(NO3)
+
P
N
N
CO
CO
C4
as an N,N0 chelating ligand. An ellipsoid representation of the neu-
tral complex is shown in Fig. 3. Selected bond lengths and angles
are summarized in Table 3. The position of the nitrogen atom in
C5
C3
O30
Cl1
C30
C6
Table 2
N2
Selected bond lengths (Å) and angles (°) in [Tc(CO)3Cl(Ppy3-N,N0)] (values for two
independent species)
C1
Molecule 1
Molecule 2
Tc1
N22
C23
C20
Tc1–C10
Tc1–C20
Tc1–C30
Tc1–N2
Tc1–N12
Tc1–Cl1
1.886(8)
1.915(7)
1.933(6)
2.215(5)
2.204(5)
2.484(2)
Tc2–C40
Tc2–C50
Tc2–C60
Tc2–N32
Tc2–N42
Tc2–Cl2
1.922(9)
1.904(7)
1.916(8)
2.196(6)
2.198(6)
2.482(2)
P1
C21
C10
N12
O10
O20
C11
C24
C13
C26
C25
C16
C30–Tc1–C20
C30–Tc1–N2
C20–Tc1–N12
N2–Tc1–N12
C10–Tc1–Cl1
88.6(3)
94.8(2)
92.1(3)
84.1(2)
175.7(2)
C60–Tc2–C50
C60–Tc2–N32
C50–Tc2–N42
N32–Tc2–N42
C40–Tc2–Cl2
89.6(4)
94.8(3)
91.2(3)
84.4(2)
174.9(3)
C14
C15
Fig. 2. Ellipsoid representation [26] of [Tc(CO)3Cl(Ppy3-N,N0)]. Thermal ellipsoids
represent 50% probability. H atoms have been omitted for clarity.

3590
S.A. Saucedo Anaya et al. / Polyhedron 27 (2008) 3587–3592
netium compounds. Secondary X-rays (bremsstrahlung) play an
important role only when larger amounts of 99Tc are used. IR spec-
tra were measured as KBr pellets on a Shimadzu FTIR-spectrometer
8300. FAB+ mass spectra were recorded with a TSQ (Finnigan)
instrument using a nitrobenzyl alcohol matrix. Elemental analysis
of carbon, hydrogen and nitrogen were determined using a Herae-
us (vario EL) elemental analyzer. 1H, 13C, 31P{1H} and 99Tc NMR
spectra were taken with
spectrometer.
a
JEOL 400 MHz multinuclear
3.1. PPhpy2 and Ppy3
n-Butyllithium (50 ml of a 1.6 m solution in n-hexane) was
cooled to ꢀ70 °C under an atmosphere of dry argon. 2-Bromopyri-
dine (7.7 ml, 80 mmol) in 50 ml of dry diethylether was added drop-
wise with stirring. The resulting red-brown solution was diluted
with additional 20 ml of diethylether and stirred for 4 h. PPhCl2
(40 mmol) or PCl3 (27 mmol) were added dropwise in 10 ml dieth-
ylether, and an extra amount of 40 ml diethylether was added when
the addition of the phosphine was completed. The resulting turpid,
orange-brown suspension was vigorously stirred for 2 h at ꢀ70 °C
and slowly warmed to room temperature. The mixture was ex-
tracted with 100 ml of degassed 2 m sulfuric acid. The pH was ad-
justed to 8–9 by the addition of concentrated NaOH. The resulting
yellow solid was filtered off, washed with water and petrol ether,
and recrystallized from acetone/petrol ether. Yield about 50%.
PPhpy2: Anal. Calc. for C16H13N2P: N, 10.61; C, 72.70; H, 4.96.
Fig. 3. Ellipsoid representation [26] of [Re(CO)3(NO3)(Ppy3-N,N0)]. Thermal ellip-
soids represent 50% probability. H atoms have been omitted for clarity.
Table 3
Selected bond lengths (Å) and angles (°) in [Re(CO)3(NO3)(Ppy3-N,N0)]
Re–C10
Re–C30
Re–N12
O1–N
1.92(1)
1.92(1)
2.202(8)
1.30(1)
Re–C20
Re–N2
Re–O1
N–O2
1.92(1)
2.199(9)
2.175(7)
1.21(1)
N–O2
1.228(12)
Found: N, 10.54; C, 72.53; H, 4.63%. IR (m
max, cmꢀ1): 3036 (m),
C10–Re–C20
C10–Re–N2
C10–Re–O1
C20–Re–N2
C20–Re–O1
C30–Re–N12
N2–Re–N12
N12–Re–O1
O1–N–O3
87.3(5)
99.7(4)
173.3(4)
172.9(5)
92.5(4)
174.1(4)
84.6(3)
78.2(3)
115.3(9)
124.6(6)
C10–Re–C30
C10–Re–N12
C20–Re–C30
C20–Re–N12
C30–Re–N2
C30–Re–O1
N2–Re–O1
O1–N–O2
88.3(4)
95.2(4)
88.5(5)
96.4(4)
90.1(4)
98.4(4)
80.8(3)
120.9(9)
123.8(9)
2985 (w), 2916 (w), 1562 (vs), 1477 (w), 1442 (s), 1416 (s), 1273
(w), 1142 (w), 1092 (m), 1038 (w), 984 (m), 768 (s), 694 (s), 617
(w), 478 (s), 440 (m). 31P{1H} NMR (d, CDCl3): ꢀ2.05 ppm. 1H
NMR (d, CDCl3): 8.71 (m, 2H6-py); 7.60–7.17 (m, 11H, rest of aro-
matic protons) ppm.
Ppy3: Anal. Calc. for C15H12N3P: N, 15.85; C, 67.90; H, 4.56%.
Found: N, 15.64; C, 67,78; H, 4.58%. IR (m
max, cmꢀ1): 3035 (m),
O2–N–O3
Re–O1–N
2978 (w), 1566 (vs), 1450 (s), 1416 (s), 1276 (m), 1215 (w), 1050
(m), 1045 (m), 984 (m), 771 (s), 740 (m), 617 (w), 501 (s), 432
(m). 31P{1H} NMR (d, CDCl3): ꢀ0.17 ppm. 1H NMR (d, CDCl3): 8.70
(m, 3H6-py); 7.63-7.19 (m, 9H, rest of aromatic protons) ppm.
the non-coordinated pyridyl ring was derived from a comparison
of the thermal parameters of the corresponding atoms. Some dis-
tortions from an ideal octahedron are due to the small bite angle
of the Ppy3 and steric effects caused by the nitrato ligand, which
is bent away from the two pyridine rings. The Re–O1 bond length
of 2.175(7) Å is relatively long, but is in agreement with values
found in analogous complexes and the weakness of such bonds
[20,21]. This weakness is supported by a mass spectrometric study
on the complex, which shows in addition to the molecular ion a
peak at m/z = 552, which can be assigned to a deprotonation prod-
uct of [Re(CO)3(OH2)(Ppy3)].
Concluding it must stated, that PPhpy2 and Ppy3 in all the iso-
lated products coordinate to {M(CO)3]+ fragments (M = Re, Tc)
exclusively as N,N0 bidentate ligands under formation of six-mem-
bered chelate rings. The unoccupied P or P,N donor positions rec-
ommend such compounds for the synthesis of bimetallic
compounds.
3.2. [Tc(CO)3Cl(PPhpy2-N,N0)]
(NEt4)2[Tc(CO)3Cl3] (54.6 mg, 0.1 mmol) and PPhpy2 (26.4 mg,
0.1 mmol) were dissolved each in 1.5 ml acetonitrile and the phos-
phine solution was added dropwise to the technetium compound.
The solution was stirred for 2 h at room temperature. Colorless
crystals of [Tc(CO)3Cl(PPhpy-N,N0)] deposited from the light brown
solution upon standing overnight. The crystals were filtered off and
washed with methanol. Yield: 14 mg (30%). IR (m
max, cmꢀ1): 2033
(vs, CO), 1925 (vs, br, CO). 99Tc NMR (d, CDCl3): ꢀ990.06 ppm. 1H
NMR (d, CDCl3): 9.36 (m, 2H, H6- pyridine); 7.77–7.05 (m, 11H, rest
of the aromatic protons) ppm. 31P{1H} NMR (d, CDCl3): ꢀ2.24 ppm.
3.3. [Tc(CO)3Cl(Ppy3-N,N0)]
(NEt4)2[Tc(CO)3Cl3] (54.6 mg, 0.1 mmol) and Ppy3 (26.5 mg,
0.1 mmol) were dissolved each in 1.5 ml THF, and the phosphine
was added dropwise to the technetium complex. The solution
was stirred for 2 h at room temperature. Colorless crystals of
[Tc(CO)3Cl(Ppy3-N,N0)] deposited from the light brown solution
upon standing overnight. The crystals were filtered off and washed
3. Experimental
(NEt4)2[Tc(CO)3Cl3] [22] and (NEt4)2[Re(CO)3Br3] [23] were pre-
pared by literature procedures. PPhPy2 and PPy3 were synthesized
by a modification of a procedure previously reported by Kurtev
et al. [5e]. 99Tc is a weak bꢀ-emitter. All manipulations with this
isotope were performed in a laboratory approved for the handling
of low-level radioactive materials. Normal glassware provides ade-
quate protection against the low-energy beta emission of the tech-
with methanol. Yield: 20 mg (40%). IR (m
max, cmꢀ1): 2033 (vs, CO),
1948 (vs, br, CO), 1882 (vs, br, CO). 99Tc NMR (d, CDCl3):
ꢀ988.42 ppm. 1H NMR (d, CDCl3): 9.36 (m, 2H, H6 coordinated
py); 8.99 (m, 1H, H6 non-coordinated py); 8.15–6.91 (m, 9H, rest
of the aromatic protons) ppm.

S.A. Saucedo Anaya et al. / Polyhedron 27 (2008) 3587–3592
3591
Table 4
X-ray structure data collection and refinement parameters
[Re(CO)3Br(PPhpy2-N,N0)]
[Tc(CO)3Cl(PPhpy2-N,N0)]
[Tc(CO)3Cl(Ppy3-N,N0)]
[Re(CO)3(NO3)(Ppy3-N,N0)]
Formula
MW
C19H13BrN2O3PRe
614.39
C19H13ClN2O3PTc
481.73
C18H12ClN3O3PTc
482.73
C18H12N4O6PRe
597.49
Crystal system
a (Å)
b (Å)
monoclinic
14.363(3)
12.596(4)
20.798(4)
90
90.25(2)
90
3763.0(15)
C2/c
triclinic
9.547(1)
9.645(1)
10.687(1)
102.53(1)
100.88(1)
98.62(1)
orthorhombic
22.395(2)
10.649(1)
16.022(1)
90
triclinic
8.818(1)
10.992(1)
11.614(1)
110.79(1)
91.19(1)
c (Å)
a
(°)
b (°)
90
90
c
(°)
109.88(1)
976.8(2)
V (Å3)
924.5(2)
3820.9(5)
a
ꢀ
ꢀ
Space group
Z
P1
Pna21
P1
8
2
8
2
Dcalc (g cmꢀ3
)
2.169
8.690
1.731
1.035
1.678
1.001
2.032
6.347
l
(mmꢀ1
)
Number of reflections
Number of independent
Number of parameters
R1/wR2
4573
4082
244
0.0513/0.1013
1.045
7656
3848
244
0.0302/0.0658
0.825
17115
9084
488
0.0478/0.1152
0.932
8155
4121
271
0.0498/0.0967
1.000
Goodness-of-fit
Device/T (°K)
CAD4/293(2)
IPDS, STOE/200(2)
IPDS, STOE/200(2)
IPDS, STOE / 200(2)
a
Racemic twin, Flack parameter 0.56(5). All attempts to calculate the structure in a centrosymmetric space group were not successful.
3.4. [Re(CO)3Br(PPhpy2-N,N0)]
for idealized positions and treated with the ‘riding model’ option of
SHELXL. Crystal data and more details of the data collections and
refinements are contained in Table 4.
(NEt4)2[Re(CO)3Br3] (76.8 mg, 0.1 mmol) and PPhpy2 (26.4 mg,
0.1 mmol) were dissolved each in 1.5 ml acetonitrile, and the phos-
phine was added dropwise to the rhenium complex. The solution
was stirred for 1 h at room temperature. The color changed slowly
to yellow. Finally, 1 ml of xylene was added and NEt4Br precipi-
tated. The solution was filtered and the solvent was removed in
vacuum. The obtained oil was crystallized from xylene to give
yellow blocks. Yield: 25 mg (40%). Anal. Calc. for C19H13N2O3PBrRe:
N, 4.56; C, 37.14; H, 2.13. Found: N, 4.35; C, 36.59; H, 2.32%. IR
Supplementary data
CCDC 698149, 698150, 698151 and 698152 contain the supple-
mentary crystallographic data for [Tc(CO)3Cl(PPhpy2-N,N0)],
[Re(CO)3Br(PPhpy2-N,N0)], [Tc(CO)3Cl(Ppy3-N,N0)] and [Re(CO)3-
(NO3)(Ppy3-N,N0)]. These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
(m
max, cmꢀ1): 2021 (vs, CO), 1909 (vs, CO). 31P{1H} NMR (d, CDCl3):
1.04 ppm. 1H NMR (d, CDCl3): 9.54 (m, 2H6-Py); 7.77–7.05 (m, 11H,
rest of aromatic protons) ppm. FAB+ MS: m/z 614 ([Re(CO)3Br(PPh-
py2)]+); 535.0 ([Re(CO)3(PPhpy2)]+); 451.0 ([Re(PPhpy2)]+).
Acknowledgements
3.5. [Re(CO)3(NO3)(Ppy3-N,N0)]
We gratefully acknowledge financial support from CONACYT
(Mexico) and DAAD (Germany).
(NEt4)2[Re(CO)3Br3] (76.8 mg, 0.1 mmol) was dissolved in 10 ml
THF and ca. 1 ml H2O. AgNO3 (51.0 mg, 0.3 mmol) was added. The
mixture was stirred for 2 h at room temperature. AgBr was filtered
off and the mother liquor was brought to dryness under vacuum.
The resulting oil was redissolved in 1.5 ml THF and Ppy3
(26.5 mg, 0.1 mmol) was added in 1.5 ml THF. The solution was
stirred for 1 h at room temperature. A colorless solid of [Re(CO)3-
(NO3)(Ppy3-N,N0)] deposited from the light yellow solution upon
standing for 2 d. Single crystals were grown from MeOH. Yield:
25.4 mg (42.5%). Anal. Calc. for C18H12N4O6PRe: N, 9.37; C, 36.12;
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