Diphenyl(1-pyridyl)phosphine sulfide as a ligand in mono- and binuclear coinage metal complexes

Article abstract of DOI:10.1515/znb-1997-0314

Diphenyl(1-pyridyl)phosphine sulfide, Ph₂pyPS, 1, gives a 1:1 complex (2) with AuCl upon treatment with (C₄H₈S)AuCl. According to an X-ray diffraction analysis, this compound is isomorphous with the Ph₃PS complex. [Ph₃PAu]BF₄ and 1 give the cationic complex [Ph₃PAuSPPyPh₂]BF₄ (3). With two equivalents of the same reagent the binuclear complex 4 is generated, in which the metal atoms are S- and N-bonded. The reaction of 2 equivalents of 1 with [(tetrahydrothiophene)₂Au]ClO₄ affords the 2:1 complex 5 with the gold atom exclusively S-bonded. The analogous reaction with AgBF₄ gives the 2:1 complex 6, the structure of which has also been determined by X-ray diffraction. The silver atom is engaged in coordinative bonding with both sulfur and both nitrogen atoms in a quasi-tetrahedral environment. Addition of AgClO₄ to compound 5, and of [(MeCN)₄Cu]BF₄ to 6, gives mixed-metal complexes (7, 8) with head-to-head structures, the silver atoms being exclusively S-bonded.

Full text of DOI:10.1515/znb-1997-0314

Diphenyl(l-pyridyl)phosphine Sulfide as a Ligand in Mono- and Binuclear
Coinage Metal Complexes
M. Elena Olmos, Annette Schier, Hubert Schmidbaur*
Anorganisch-chemisches Institut der Technischen Universität München,
Lichtenbergstrasse 4, D-85748 Garching, Germany
Z. Naturforsch. 52 b, 385-390 (1997); received January 17, 1997
Copper(I), Silver(I), Gold(I) Coordination, D iphenyl(l-pyridyl)phosphine Sulfide,
Am bidentate Ligand
D iphenyl(l-pyridyl)phosphine sulfide, Ph2pyPS, 1, gives a 1:1 complex (2) with AuCl
upon treatment with (C4HsS)AuCl. According to an X-ray diffraction analysis, this com -
pound is isomorphous with the Ph^PS complex. [Ph3PAu]BF4 and 1 give the cationic complex
[Ph;?PAuSPpyPh2]BF4 (3 ). With two equivalents of the same reagent the binuclear complex 4
is generated, in which the metal atoms are S- and N-bonded. The reaction of 2 equivalents of 1
with [(tetrahydrothiophene)2Au]C104 affords the 2:1 complex 5 with the gold atom exclusively
S-bonded. The analogous reaction with AgBF4 gives the 2:1 complex 6, the structure of which
has also been determined by X-ray diffraction. The silver atom is engaged in coordinative
bonding with both sulfur and both nitrogen atoms in a quasi-tetrahedral environment. Addition
of AgC104 to compound 5, and of [(MeCN)4Cu]BF4 to 6, gives mixed-metal complexes (7, 8)
with head-to-head structures, the silver atoms being exclusively S-bonded.
Introduction
chloro(tetrahydrothiophene)gold(I) with displace-
ment of the weakly coordinated thioether ligand
to give the neutral complex [AuCKSPPhbpy)] (2 )
which contains ligand 1 coordinated to the metal
centre via the sulfur atom (Scheme 1). The product
has been identified by microanalysis, mass spec-
trometry and NMR spectroscopy (see Experimen-
tal), and its solid state structure has been established
by a single crystal X-ray diffraction study.
Sulfide and thiolate anions can serve as cluster-
ing centers for gold(I) cations. The sulfur atoms
may accommodate up to four gold atoms to form
aggregates with short intermetallic contacts which
contribute to the overall stability [1]. The sulfur
atoms of phosphine sulfides R3PS can be expected
to have similar acceptor qualities for gold atoms,
but the first systematic studies in this area have been
carried out only very recently [2 ].
The crystals are monoclinic, space group P2)/n,
with Z = 4 formula units in the unit cell. The lattice
contains monomeric molecules with the expected
linear coordination at the gold atom (Fig. 1). The
molecule has no crystallographically imposed sym-
metry. The structure is isomorphous with that of the
triphenylphosphine sulfide complex of AuCl [3, 4]
with virtually identical geometrical parameters (Fig.
3). It therefore appears that the pyridine function
plays no role in determining the molecular and crys-
tal structure. The pyridine ring is found to simply
replace one of the phenyl rings in Ph^PSAuCl with-
out any major changes in the crystallographic di-
mensions.
Any auxiliary donor group in the organic sub-
stituents R of the phosphine sulfides should be
helpful for the build-up of polynuclear complexes,
and therefore a study of complexes with 1-pyridyl-
phosphine sulfides as ligands for the coinage metals
was initiated. Diphenyl(l-pyridyl)-phosphine sul-
fide Ph2(l-C 5H4N)PS was chosen as the model lig-
and substrate because of its clear and simple substi-
tution pattern.
Results and Discussion
Diphenyl( 1-pyridyl)phosphine sulfide (SPPhb py)
When a freshly prepared solution of
1
reacts with an equimolecular amount of
[AuPPh3][BF4] is treated with ligand 1 in a 1:1
molar ratio, the cationic mononuclear complex
[Au(PPh3)(SPPh2py)][BF4] (3) is obtained as a
* Reprint requests to Prof. Dr. H. Schmidbaur.
0939-5075/97/0300-0385 $ 06.00
©
1997 Verlag der Zeitschrift für Naturforschung. All rights reserved.
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386
M. E. Qlmos et al. ■Diphenyl(l-pyridyl)phosphine Sulfide
2+
yS—Au—
PhjP
PPhz
1/2AgQ04
1/2
(CO^
2+
/ S - A g - S
PhjP
PPh2
PhjP
Ag
PPh2
1/2 [Cu(CNMe)4][BF4]
1/2
[BF4]2
1/2
[bf4-]
O-UÖ
CNMe
Scheme 1
corresponding to the phosphorus atoms of ligand 1
and triphenylphosphine, respectively.
In complex 3 there is still a nitrogen function
available, which can be used for further coordi-
nation of metal atoms. Such a dinuclear com-
plex is obtained, when ligand 1 is treated with
[AuPPh3][BF4] in a 1:2 molar ratio. The room
temperature 31P{ 1H} NMR spectrum of the prod-
uct in CDCI3 features three broad signals, which
are split into two doublets and a singlet as the
temperature is lowered to -60°C. This result is
in accordance with the formation of a complex
[(Ph3PAu)SPPh2{2-C5H4N(AuPPh3)}] [BF4]2 (4),
with S,N-coordination of ligand 1. A sulfonium salt
structure with the gold atoms solely S-coordinated
can thus be ruled out. The stoichiometry of the com-
plex is corroborated by elemental analysis data,
which differ clearly from those found for the 1:1
product 3 (see Experimental).
Fig. 1. M olecular structure of compound 2 in the crystal
with atomic numbering. (ORTEP. 50% probability ellip-
soids; H atoms omitted for clarity; Selected bond lengths
[A] and angles [°]: Au-S 2.263(2), Au-Cl 2.267(2), S-P
2.017(2); S-Au-Cl 174.49(5), P-S-Au 105.85(7).
Treatment of [Au(tht)2]C10 4 (tht = tetrahydro-
thiophene) with two equivalents of ligand 1 gives
the 1:2 complex 5, and the related silver derivative
[Ag(SPPh2py)2][BF4] (6 ) can also be prepared by
reacting Ag[BF4] with ligand 1 in the same molar
ratio (Scheme 1). The spectroscopic data are in-
dicative of the coordination of the ligands through
their sulfur atoms in the gold complex 5, but there
colorless solid, which also features S-coordination
of the phosphine sulfide. Its 3IP{'H } NMR spec-
trum shows two signals at b = 44.4 and 37.1 ppm.
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M. E. Qlmos et al. • Diphenyl(l-pyridyl)phosphine Sulfide
387
Fig. 2. M olecular structure of compound 6 in the crys-
tal with atomic numbering. (ORTEP, 50% probability el-
lipsoids; H atoms omitted for clarity; only one of the
two enantiomers is shown.) Selected bond lengths [A]
and angles [°]: A g-Sl 2.472(1), Ag-S2 2.545(1), Ag-
N1 2.482(3), Ag-N2 2.341(3), PI-SI 1.974(1), P2-S2
1.967(1); Sl-A g-S2 127.35(3), N l-A g-N 2 113.2(1), P l-
S 1-Ag 95.23(4), P2-S2-Ag 91.72(4).
Fig. 3. Superposition of the molecules of compound
2
(dotted lines) and of (triphenylphosphine)sulfide-
gold(I)chloride [3], showing the virtually identical ge-
ometric parameters of both complexes.
is no direct evidence for this in the silver species
6 , because in its 31P{'H } NMR spectrum no Ag-
P coupling is observed. Therefore a single crystal
X-ray structure analysis of 6 has been carried out.
Crystals of 6 are triclinic, space group P i, with Z =
2 formula units in the unit cell. The lattice is built of
independent BF4 anions and mononuclear cations.
These cations have no crystallographically imposed
symmetry. Two enantiomeric chiral cations are re-
lated by a crystallographic center of inversion. In the
cation the silver atom is coordinated to the ligands
mainly through the sulfur centers, but the cation
also features weak A g-N interactions, which lead
to a distortion of the linear environment of the silver
atom (Fig. 2).
The axis Sl-A g-S2 is strongly bent [127.35(3)°],
and together with an angle N l-A g-N 2 = 113.2(1)°
the coordination geometry at the metal atom is close
to tetrahedral. The silver atom thus is a spiro center
of two five-membered rings. The two Ag-S bond
lengths are almost equal [2.472(1) and 2.545(1)
A], more so than the two Ag-N distances [2.341(3)
and 2.482(3) A]. Owing to the integration into five-
membered rings, the P-S-Ag angles are compressed
to 95.23(4)° at SI and even 91.72(4)° at S2. In
the open chain complex 2 this angle Au-S-P is
105.85(7)°.
which is assumed to have a non-centrosymmetrical
"head-to-head" structure in solution (CDCI3), as
suggested by its 31P{ 1H} NMR spectrum (see Ex-
perimental), with the gold atom coordinated only to
the S-donor sites and the silver atoms exclusively
engaged in bonding with the N-donor ends.
Similarly, complex 6 reacts with equimolecular
amounts of [Cu(MeCN)4][BF4] in dichloromethane
to give the product
[AgCu(/i-SPPh2py)2(MeCN)][BF4]2 (8 ) as an air-
sensitive yellow solid. In this case all analytical and
spectroscopic data are also consistent with a "head-
to-head" structure, with the silver atom bonded to
the sulfur atoms and the copper atom coordinated to
both nitrogen atoms. One molecule of acetonitrile
appears to be strongly coordinated in the product,
most likely as an additional ligand for the copper
atom.
Experim ental
General: All experiments were carried out at room
temperature without special precautions against moisture,
except for the mixed metal complex 8. Silver complexes
must be protected against daylight. Warning: Perchlo-
rate salts may be explosive. [AuPPh3][BF4] was pre-
pared in situ by the reaction of AgBF4 with AuClPPhi
in THF. Diphenyl(l-pyridyl)phosphine sulfide was ob-
tained by reacting commercially available diphenyl(l-
pyridyl)phosphine with elemental sulfur. [AuCl(tht)],
[Au(tht)2]C104[5] and [Cu(CNM e)4]BF4[6] were pre-
Compounds 5 and 6 were used as precursors for
the synthesis of mixed metal (Ag/Au: 6 , Ag/Cu: 7)
complexes. Treatment of the gold complex 5 with
AgC104 in acetone leads to the colourless crys-
talline product [AgAu(/i-SPPh2py)2](C10 4)2 (7),
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388
Table I. Crystal data, data collection, and structure refinement for compounds 2 and 6 .
M. E. Olmos et al. • DiphenyK l-pyridyI)phosphine Sulfide
2
6
Crystal data
Formula
M r
C34H'>8AgBF4N-’P-’S-’
785.32
C ,7H ,4AuC1NPS
527.74
Crystal system
Space group
a (A)
H A )
c (A)
monoclinic
P2,/n [No. 14]
12.075(1)
9.285(1)
14.764(1)
90
96.48(1)
90
1645.0(2)
2.131
triclinic
PI [No. 2]
10.536(1)
12.460(1)
13.806(2)
78.05(1)
68.32(1)
81.33(1)
1642.3(3)
1.588
a ( ° )
ß O
7 (° )
V (A3)
Pcalc (gem 3)
Z
4
2
792
8.90
F(000)(e)
p (Mo Ka) (cm -1 )
1000
93.23
Data collection
Diffractometer
Radiation
Enraf Nonius CAD4
Mo Kq , 0.71073 A
Enraf Nonius CAD4
Mo Ka , 0.71073 A
-74
T (°C )
-68
Scan mode
a ;
U)
-13— + 1 3 ,0 ^ + 1 5 ,-1 6 — +17
hkl Range
-15— + 1 5 ,0 —h -1 1 ,0 —>+18
0.64
6784
6778
6758
none
- / -
0.64
3306
3306
3306
•//-scans
0.265/0.999
sin(6VA)max (A -1 )
M easured refl.
Unique refl.
Observed refl.
Absorption correction
Tmin/Tmax
Refinement
Refined parameters
H atoms (found/calcd.)
R 1[a]
461
0/28
0.0434
0.1139
<0.001
+3.210/-1.326
199
0/14
0.0307
0.0853
<0.001
+ 1.593/-2.021
w/?2lbl
(shift/error)max
„
/9fin(max/min) (eA -3 )
[al R = E (IF„l-IFcl)/V lF 0l; [b]wR2 =
- F2)2] / E N F o ) 2] } '/2;
w = l/[cr-(F“) + (ap)‘ + bp]; p = (F2 + 2F2)/3; a = 0.0560 (2), 0.0567 (6 ); b = 5.84 (2), 3.32 (6 ).
pared by following the literature procedures. MS: Varian
MAT 311A spectrometer; NMR: JEOL GX 400 spec-
trometer, CDCI3 or CD2CI2 (8) as solvents with TMS as
internal standard for 'H and aqueous H3PO4 (85%) as
external standard for 11P {1H}.
- MS (FAB): m/z (%) = 527.1 (1.41) [M]+; 492.1 (10.86)
[M-C1]+. -
C |7H ,4AuClNPS (527.76)
Calcd C 38.69 H 2.67 N 2.65 S 6.07%,
Found C 38.60 H 2.68 N 2.57 S 5.90%.
[AuCl(SPPh2py)] (2): To
a
solution of ligand
1
(0.4 mmol. 0.118 g) in dichloromethane was added
[AuCl(tht)] (0.4 mmol, 0.128 g) and the solution was
stirred for 30 min. The solution was then concentrated in
a vacuum and diethylether (15 ml) was added to precip-
itate complex 2 as a white solid, yield 0.190 g (90%). -
'H NMR: 6 = 7.51-8.01 (m. Ph, 10H + py, 2H), 8.63 (m.
py, 1H), 8.78 (m, py, 1H ).- 3,P{'H } NMR: 6 = 36.6 (s).
[(PlnPAu)SPPh2py][BF4] (3): To a freshly prepared
solution of (triphenylphosphine)gold(I) tetrafiuoroborate
(0.2 mmol, 0.109 g) in TH F was added ligand 1 (0.2 mmol,
0.059 g). After 1 h of stirring the solution was concen-
trated in a vacuum. Addition of 15 ml of diethylether led
to the precipitation of 3 as a white solid, yield 0.110 g
(66%). - 'H NMR: <5= 7.36-7.77 (m. Ph, 25H + py, 2H),
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389
M. E. Olmos et al. • Diphenyl(l-pyridyl)phosphine Sulfide
8.01 (m, py, 1H), 8.19 (m, py, 1H). - 31P {'H } NMR: b =
44.4 (broad, SPPh2py, 1P), 37.1 (broad, PPh3, 1P). - MS
(FAB): m/z (%) = 754.3 (100) [M-BF4]+; 492.1 (3.45)
[M-BF4-PPh3]+; 459.2 (43.16) [M -BF4-SPPh2py]+.
stirred at room temperature in the dark for 30 min. The
solution was concentrated in a vacuum and 20 ml of di-
ethylether was added to give 7 as a yellow solid, yield
0.160 g (73%). - 'H NMR: 6 = 7.60-7.70 (m, Ph, 20H +
py, 4 H), 8.01 (m, py, 2H), 8.51 (m, py, 2H). - 3,P{'H }
NMR: 6 = 45.0 (s). - MS (FAB): m/z (%) = 994.8 (4.75)
[M-C104]+; 786.9 (81.23) [M -2C104-Ag]+; 698.8 (100)
[M-2C104-Au]+.
C 35H29AuBF4NP2S (841.40)
Calcd C 49.96 H 3.47 N 1.67 S 3.81%,
Found C 49.66 H 3.33 N 1.42 S 4.39%.
[(PhiPAu)SPPh2{2-C 5H4N(AuPPhi)}][BF4]2 (4): To
a
freshly prepared solution of (triphenylphosphine)-
C34H28AgAuCl2N20 8P2S2 (1094.42)
gold(I) tetrafluoroborate (0.3 mmol, 0.164 g) in THF was
added ligand 1 (0.15 mmol, 0.044 g). The mixture was
stirred for 1 h and the solution was then concentrated in
a vacuum. Addition of diethylether leads to the precipita-
tion of complex 4 as a white solid, yield 0.100 g (48%).
- 'H NMR: 6 = 7.11-7.80 (m, Ph, 40H + py, 2H), 8.01
(m, py, 1H), 8.32 (m, py, 1H). - 3IP { 1H} NMR (22°C):
6 = 43.6 (broad, SPPh2py, IP), 36.5 (broad, Ph3P -Au-
S, IP), 31.5 (broad, Ph3P -Au-N); -60°C: 6 = 44.1 (d,
Vpp = 7.6 Hz, SPPh2py, IP), 36.6 (d, Ph3P -Au-S, IP),
32.4 (s, Ph3P -Au-N). - MS (FD): m/z (%) = 754.0 (100)
[Au(PPh3)(SPPh2py)]+.
Calcd C 36.31 H 2.58 N 2.57 S 5.86%,
Found C 36.91 H 2.88 N 2.47 S 5.86%.
[AgCu(p-SPPh2py)2(CNMe)][BF4]2 (8): To
a so-
lution of [Cu(NCM e)4]BF4 (0.2 mmol, 0.063 g) in
dichloromethane (15 ml) was added 6 (0.2 mmol, 0.157
g), and the reaction mixture was stirred in the dark for
1 h under nitrogen. The solution was concentrated in a
vacuum and diethylether was added to precipitate com-
plex 8 as a yellow solid, yield 0.141 g (72%). - 1H NMR:
8 = 4.05 (s, NCMe, 3H), 7.58-7.78 (m, Ph, 20H + py,
4H), 8.54 (m, py, 2H), 8.10 (m, py, 2H). - 31P {1H} NMR
(CD2C12): <5= 51.7 (s). - MS (FD): m/z (%) = 849.0 (3.36)
[M-BF4-NCM e]+; 740.1 (14.05) [M-2BF4-Cu]+; 699.1
(40.71) [Ag(SPPh2py)2]+; 653.1 (100) [Cu(SPPh2py)2]+.
C53H44A u ^ F 8NP3S (1387.47)
Calcd C 45.88 H 3.20 N 1.01 S 2.31%,
Found C 45.62 H 3.27 N 0.87 S 2.22%.
[AufSPPhipyhJClOi (5):To a solution of ligand 1(0.4
mmol, 0.118 g) in dichloromethane (20 ml) was added
[Au(tht)2]C104 (0.2 mmol, 0.095 g). After 1 h of stirring
at room temperature the solution was concentrated in a
vacuum. Addition of diethylether led to the precipitation
of 5 as a white solid. Yield 0.135 g (76%). - 'H NMR:
6 = 7.27-7.77 (m, Ph, 20H + py, 2 H), 7.91 (m, py, 2H),
8.00 (m, py, 2H), 8.73 (m, py, 2H). - 3iP {'H } NMR: 6 =
38.6 (s). - MS (FAB): m/z (%) = 787.2 (100) [M-C104]+;
492.0 (21.46) [Au(SPPh2py)]+.
C36H3,AgB2CuF8N3P2S2 (976.76)
Calcd C 44.27 H 3.20 N 4.32 S 6.56%,
Found C 44.64 H 3.56 N 4.41 S 5.69%.
Crystal structure determinations: Suitable single crys-
tals of compounds 2 and 6 were sealed into glass capil-
laries and used for measurement of precise cell constants
and intensity data collection. During data collection, three
standard reflections were measured periodically as a gen-
eral check of crystal and instrument stability. No signifi-
cant changes were observed for both compounds. Diffrac-
tion intensities were corrected for Lorentz and polariza-
tion effects. An absorption correction was applied for
compound 2. The structures were solved by Patterson
methods and refined by full matrix least-squares calcula-
tions against F2. The thermal motion of all non-hydrogen
atoms was treated anisotropically. The BF4~ anion of 6
showed disorder and was refined in split positions. All
hydrogen atoms were placed in idealized calculated po-
sitions and allowed to ride on their corresponding carbon
atoms with fixed isotropic contributions (UiSO(fix) = 1.5 •
Ueq of the attached C atom). As mentioned, compound
2 is isomorphous to the triphenyl phosphine analogue[4,
5]. In fact, a superposition of both compounds (Fig. 3)
showed no significant differences. Thus, the unambigu-
ous recognition of the nitrogen atom on the basis of con-
formational changes compared to the nitrogen-free ana-
logue, or by means of the temperature factors C versus
N, have failed. Further information on crystal data, data
C 34h .8AuC 1N ,04P^S2 (887.10)
Calcd C 46.03 H 3.18 N 3.16 S 7.23%,
Found C 45.70 H 3.09 N 3.10 S 7.31%.
[Ag(SPPh2pyh]B F 4 (6): To a solution of silver tetraflu-
oroborate (0.2 mmol, 0.039 g) in 20 ml of acetone was
added ligand 1 (0.4 mmol, 0.118 g), and the solution was
stirred for 1 h in the dark. The solution was then concen-
trated in a vacuum and 15 ml of diethylether was added
to precipitate 6 as a white solid, yield 0.108 g (69%). -
‘H NMR: 6 = 7.41 (m, py, 2H), 7.50 (m, py, 2H), 7.54-
7.70 (m, Ph, 20H), 7.80 (m, py, 2H), 7.91 (m, py, 2H). -
31P{'H } NMR: Ö= 47.8 (s).
C34H28AgBF4N2P2S2(785.36)
Calcd C 52.00 H 3.59 N 3.57 S 8.16% ,
Found C 51.15 H 3.78 N 3.43 S 8.63%.
[AgAu(p-SPPIi2py)2](C l04)2 (7): To an acetone solu-
tion (10 ml) of silver perchlorate (0.2 mmol, 0.041 g)
was added 5 (0.2 mmol, 0.177 g), and the mixture was
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390
M. E. Olmos et al. • Diphenyl(l-pyridyl)phosphine Sulfide
collection, and structure refinement are summarized in
Table I. Important interatomic distances and angles are
shown in the corresponding figure captions. Anisotropic
thermal parameters, tables of interatomic distances and
angles, and atomic coordinates have been deposited with
the Fachinformationszentrum Karlsruhe, Gesellschaft für
wissenschaftlich-technische Information mbH. D-76344
Eggenstein-Leopoldshafen. The data are available on re-
quest on quoting CSD-406397 (2) and CSD-406398 (6).
Acknowledgemen ts
This work was supported by Deutsche Forschungsge-
meinschaft, by Fonds der Chemischen Industrie and by
D.A.A.D. (through a fellowship to M. E. O.). The authors
are grateful to Mr. J. Riede for establishing the X-ray data
sets, to Prof. Dr. F. R. Kreissl for the mass spectrometric
measurements and to Degussa AG and Heraeus GmbH
for the donation of chemicals.
[5] R. Usön, A. Laguna, M. Laguna, J. Jimenez, M. P.
Gömez, A. Säinz, P. G. Jones;/. Chem. Soc., Dalton
Trans. 1990. 3457.
[6] D. F. Shriver, “Inorganic Syntheses” vol 19. p. 90,
W iley-Interscience, New York (1979).
[1] H. Schmidbaur, Chem. Soc. Rev. 24, 391 (1995).
[2] M. Preisenberger, A. Bauer, H. Schmidbaur, Chem.
Ber., in press (and references therein).
[3] P. G. Jones, E. Bembenek. J. Crystallogr. Spectrosc.
22. 397 (1992).
[4] M. Hussain, E. O. Schlemper. Acta Crystallogr. C
43. 450(1987).
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