Synthesis, crystal and molecular structure of a binuclear, double-bridged hexacarbonyl tungsten derivative of 4-pyridyldiphenylphosphane

Article abstract of DOI:10.1016/S0022-328X(01)01005-1

4-Pyridyldiphenylphosphane is used as a bridging ligand for the first time. The ligand forms a double-bridged bimetallic complex with hexacarbonyl tungsten. Characterization is performed by X-ray analysis and NMR spectroscopy. The crystal structure of the complex shows π-stacking interaction between the pyridyl rings, and structurally the complex is an organometallic analogue of [2.2]-paracyclophanes.

Full text of DOI:10.1016/S0022-328X(01)01005-1

Journal of Organometallic Chemistry 633 (2001) 66–68
www.elsevier.com/locate/jorganchem
Synthesis, crystal and molecular structure of a binuclear,
double-bridged hexacarbonyl tungsten derivative of
4
-pyridyldiphenylphosphane
a,
b
a
Leeni Hirsivaara *, Matti Haukka , Jouni Pursiainen
a
Department of Chemistry, Uni6ersity of Oulu, PO Box 3000, FIN-90014 Oulu, Finland
b
Department of Chemistry, Uni6ersity of Joensuu, PO Box 111, FIN-80101 Joensuu, Finland
Received 7 March 2001; accepted 26 April 2001
Abstract
-Pyridyldiphenylphosphane is used as a bridging ligand for the first time. The ligand forms a double-bridged bimetallic
4
complex with hexacarbonyl tungsten. Characterization is performed by X-ray analysis and NMR spectroscopy. The crystal
structure of the complex shows p-stacking interaction between the pyridyl rings, and structurally the complex is an organometallic
analogue of [2.2]-paracyclophanes. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Binuclear; Complex; Crystal structure; NMR spectra; Phosphane; Tungsten
1
. Introduction
ands that are used as the 4-pyridylphosphane-type
bridge are the diphenylphosphino-terpyridines in
trimetallic systems [6]. However, Cu(I) and Cd(II)
derivatives of ligand 4-thiomethyl-6-(3-pyridyl)-2,2%-
bipyridine, which are structurally closely related to
Bimetallic transition metal complexes usually have
the metal centers close to each other, often with direct
metal-to-metal interactions. Bridging ligands, like chlo-
ride or 2-pyridyldiphenylphosphane [1], are typically
used to enhance the stability of the structures. To
combine two distant metal atoms together, ligands like
semiquinones [2], bipyridines [3] or some ladder-like
ligands [4] are used. Such ligands can, for example, also
be used in self-organizing structures in supramolecular
chemistry [5].
[
W(CO) (P(4-py)Ph )] , have been reported [7].
4
2 2
2
. Experimental
2
.1. Synthesis of [W(CO) (P(4-py)Ph )]
4 2 2
In this paper, we report the use of 4-
pyridyldiphenylphosphane as a novel type of bridging
phosphane ligand between two metal centers in a dou-
ble-bridged structure of [W(CO) (P(4-py)Ph )] with p-
[
W(CO) (py) ] (504 mg, 1.11 mmol) was partly dis-
4 2
solved in benzene (40 ml). 4-Pyridyldiphenylphosphane
585 mg, 2.22 mmol) was added and the mixture was
(
4
2 2,
stirred for 24 h at 40–45 °C temperature. The reaction
was carried out in nitrogen atmosphere. Purification
was performed by column chromatography using first a
dichloromethane:hexane (2:1) mixture, and then
dichloromethane as eluent. Yield 160 mg (17%). Crys-
tals were grown by slow evaporation of
stacked pyridine rings. Complex [W(CO) (P(4-py)-
4
Ph )] , in which both tungsten atoms occupy one WꢀN
2
2
and one WꢀP bond, is prepared and characterized with
X-ray analysis and NMR spectrometry. This complex is
the first 4-pyridylphosphane-bridged binuclear transi-
tion metal complex reported. The only phosphane lig-
1
dichloromethane–hexane mixture. H-NMR lH (see
Fig. 1 for numbering): H6,10,12,16: 7.76 (m); H7–9,13–15:
*
Corresponding author. Tel.: +358-8-5531647; fax: +358-8-
13
1
7
.48 (m); H18,22: 6.65 (dd); H19,21 8.23 (d). C-{ H}-
5
0
531603.
2
E-mail address: leeni.hirsivaara@oulu.fi (L. Hirsivaara).
NMR l (Fig. 1 for numbering): C : 203.65 (d, JCP=
C 1
022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01005-1

L. Hirsi6aara et al. / Journal of Organometallic Chemistry 633 (2001) 66–68
67
7
.3 Hz); C : 198.85 (s); C : 208.5 (d); C5,11: 132.38 (d,
clear single quantum correlation (HSQC) spectra and
2
,3
4
1
2
31
1
JCꢀP=41.9 Hz); C
C7,9,13,15: 129.16 (d, JCꢀP=10.2 Hz); C8,14: 131.25 (s);
: 133.93 (d, JCꢀP=12.9 Hz);
P-{ H}-NMR spectra (162 MHz, ext. stand. 85%
H PO ) were recorded on a Bruker DPX 400 spectrom-
6,10,12,16
3
3
4
1
C : 145.93 (d, JCꢀP=22.3 Hz); C18,22: 128.89 (d,
eter in CDCl (CIL, D 99.8%, 0.03% Me Si). IR spectra
1
7
3
4
2
31
1
JCꢀP=9.2 Hz); C19,21: 154.40 (d, 6.7 Hz). P-{ H}-
were measured on a Bruker IFS 66 spectrometer in
dichloromethane (99.8%).
1
NMR: l 35.1 ppm ( J
=240 Hz). IR (CH Cl )
P
WꢀP
2 2
−
1
cm 2012 (s), 1893 (vs, wide), 1857 (s) (CꢁO). Elemen-
tal analysis could not be obtained because of gradual
decomposition of the complex when dried.
2.4. Crystal structure determination
C H NO PW,
M=559.15,
, b=9.1862(2) A, c=12.7328(3) A
0.4810(10)°, i=89.2110(10)°,
V=989.67(4) A
Z=2, D =1.876 g cm , v(MoK )=5.943 mm ,
triclinic,
a=
, h=
21
14
4
2
.2. Synthesis of P(4-py)Ph ligand
8.6451(2) A
,
,
,
2
8
k=82.9380(10)°,
, T=150 K, space group P1 (no. 2),
3
The ligand P(4-py)Ph2 is known previously from
,
(
−
3
–1
literature [8,9]. In this work, the ligand was prepared by
the method used previously for the preparation of
c
a
11 555 reflection collected, 3578 unique (R =0.0175).
int
2
2
-pyridylphosphanes [10]. The starting material, 4-bro-
mopyridine, was obtained by dissolving 4-bromopy-
ridine hydrochloride (Aldrich) in distilled,
The final R was 0.0201 (all data) and wR (F )=0.0468
1
2
(all data). Data were collected with a Nonius Kap-
paCCD diffractometer using MoKa radiation (u=
deoxygenated water. NaOH (10%) was added until the
solution became basic. The resulting 4-bromopyridine
was extracted with diethyl ether and dried in vacuum.
Synthesis was continued as described elsewhere [10].
The resulting ligand was not pure enough after purifica-
tion by extraction, and was further purified by column
0.710 73 A). Hydrogen atoms were placed on calculated
,
positions and constrained to ride with the parent atom.
One of the phenyl rings in the asymmetric unit was
disordered in two positions, having population parame-
ters of 0.70 and 0.30. In the latter position the carbon–
carbon bond lengths were fixed to 1.39 A and the
,
chromatography using first dichloromethane, and then
anisotropic displacement parameters were constrained
to be equal for all carbon atoms. The carbon atoms in
the ring of higher population were refined anisotropi-
cally with equal anisotropic displacement parameters.
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC 158094 for compound
[W(CO) (P(4-py)Ph )]
1
3
:1 dichloromethane:acetonitrile as eluent. H-NMR lH
(
see Fig. 1 for numbering): H6
: 7.32–7.41;
–10,12–16
1
1
3
H18,22: 7.11 (m); H19,21 8.51 (m). C-{ H}-NMR l
(
C
1
Fig. 1 for numbering): C5 : 134.90 (d, JCꢀP=10 Hz);
,11
2
C
: 134.16 (d, JCꢀP=20 Hz); C7,9,13,15: 128.80 (d,
,10,12,16
6
3
1
JCꢀP=8 Hz); C8,14: 129.51 (s); C : 134.90 (d, JCꢀP=
17
2
1
(
0 Hz); C1 : 127.20 (d, JCꢀP=15 Hz); C19,21: 149.25
8,22
3
4
2 2.
1
1
d, 4 Hz). Pꢀ{ H}-NMR: l −5.3 ppm.
P
2.3. Spectroscopy
3. Results and discussion
1
13
1
H-NMR spectra (400 MHz, Me Si), C-{ H}-NMR
Complex [W(CO) (P(4-py)Ph )] was synthesized by
4
4
2 2
spectra (100 MHz, Me Si), two-dimensional heteronu-
an overnight reaction between [W(CO) (py) ] and 4-
4
4 2
pyridyldiphenylphosphane ligand in benzene solution at
0–45 °C [11], and purified by column chromatogra-
4
phy. The product was not particularly air sensitive, but
slowly decomposed in the course of time. Single crystals
of the complex disassembled easily if they were allowed
to dry in air.
The X-ray structure of the complex [W(CO) (P(4-
4
py)Ph )] is presented in Fig. 1, and the bond lengths
2
2
and angles around the metal centers are presented in
Table 1. The octahedral environment around the metal
centers is slightly distorted: the NꢀWꢀP angle is
8
8.46(7)°, and the carbonyl groups are pushed away
from the phosphane ligand. The carbonyl group trans
to phosphorus has slightly shortened CꢀW and CꢀO
bonds compared with cis carbonyl groups, and the
carbonyl group trans to the nitrogen atom has them
clearly shortened, reflecting the differences in the rela-
tive trans effects of the N, P and CO donors.
Fig. 1. X-ray structure of complex [W(CO) (P(4-py)Ph )] .
4
2 2

68
L. Hirsi6aara et al. / Journal of Organometallic Chemistry 633 (2001) 66–68
1
3
Table 1
Bond lengths (A
W(CO) (P(4-py)Ph )]
2 2
increased. In the C-NMR spectroscopy, the chemical
shifts of the pyridyl carbon atoms are increased,
whereas the chemical shifts of the phenyl carbon atoms
are not remarkably affected by coordination.
,
) and angles (°) around the metal center for complex
[
4
Bond lengths
WꢀP(1)
2.5488(9)
2.268(3)
1.950(4)
2.040(4)
2.019(3)
2.005(4)
C(1)ꢀO(1)
C(2)ꢀO(2)
C(3)ꢀO(3)
C(4)ꢀO(4)
1.167(5)
1.138(4)
1.145(4)
1.143(4)
Interestingly, the complex [W(CO) (P(4-py)Ph )] is
structurally an organometallic analogue of [2.2]-paracy-
clophanes, particularly of pyridinophanes [15]. On the
other hand, the ability of the ligand P(4-py)Ph to form
bridges makes it
4
2 2
WꢀN(1)
WꢀC(1)
WꢀC(2)
WꢀC(3)
WꢀC(4)
2
a
possible building unit for
organometallic polymers.
Bond angles
P(1)ꢀWꢀC(1)
P(1)ꢀWꢀC(2)
P(1)ꢀWꢀC(3)
P(1)ꢀWꢀC(4)
P(1)ꢀWꢀN(1)
N(1)ꢀWꢀC(1)
N(1)ꢀWꢀC(3)
N(1)ꢀWꢀC(4)
P(1)ꢀWꢀC(1)
P(1)ꢀWꢀC(2)
P(1)ꢀWꢀC(3)
P(1)ꢀWꢀC(4)
92.04(12)
96.43(10)
86.76(9)
174.71(11)
88.46(7)
178.74(12)
96.44(12)
89.43(13)
92.04(12)
96.43(10)
86.76(9)
P(1)ꢀWꢀN(1)
N(1)ꢀWꢀC(1)
N(1)ꢀWꢀC(2)
N(1)ꢀWꢀC(3)
N(1)ꢀWꢀC(4)
C(1)ꢀWꢀC(2)
C(1)ꢀWꢀC(3)
C(1)ꢀWꢀC(4)
C(2)ꢀWꢀC(3)
C(2)ꢀWꢀC(4)
C(3)ꢀWꢀC(4)
88.46(7)
178.74(12)
96.76(12)
96.44(12)
89.43(13)
84.34(15)
82.44(15)
89.97(16)
166.50(15)
88.64(14)
88.65(13)
Acknowledgements
Financial support by the Neste Foundation is grate-
fully acknowledged.
References
174.71(11)
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(
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4
2 2
[
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(
(
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2 2
[
[
N atoms are in adjacent positions.
1
13
1
31
1
H-, C-{ H}- and P-{ H}-NMR data for both the
complex and the free ligand are presented in the Section
1
13
1
2
. The interpretation of the H- and C-{ H}-NMR
[
[
spectra was performed with the help of two-dimen-
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5
525.
[
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