A simple and efficient synthesis of bisphosphine platinum(0) complexes with various P-Pt-P angles

Article abstract of DOI:10.1016/j.jorganchem.2006.11.051

Improved syntheses of a series of [(L)₂Pt(η²-nb)] (4)-(8) (L = PPh₃, 1/2 dpp(o-xyl), 1/2 dppb, 1/2 dppbe, 1/2 dppn) complexes are described. Complexes 4-8 have been characterized by ¹H, ³¹P NMR, IR spectroscopy as well as mass spectrometry and elemental analysis. The reaction of [(dppbe)Pt(Cl₂)] with sodium borohydride and tolan was investigated by ³¹P NMR spectroscopy. The complex [(dppbe)Pt(η²-tolan)] (11) has been isolated and characterized. The reactivity of [(dppn)Pt(η²-nb)] with the spirocyclohexyl-1,2,4-trithiolane 12 and the sterically hindered 2,2,4,4-tetramethyl-3-thioxocyclobutanone 13 was tested. The complex [(dppn)Pt(η²-13)] (14) has been isolated and characterized by ¹H, ³¹P NMR, IR spectroscopy as well as mass spectrometry and elemental analysis. X-ray crystal analyses have been performed on complex 8, 11 and 14.

Full text of DOI:10.1016/j.jorganchem.2006.11.051

Journal of Organometallic Chemistry 692 (2007) 2736–2742
www.elsevier.com/locate/jorganchem
A simple and efficient synthesis of bisphosphine platinum(0)
complexes with various P–Pt–P angles
*
Holm Petzold, Helmar Go¨rls, Wolfgang Weigand
Institut fu¨r Anorganische und Analytische Chemie, Friedrich-Schiller-Universita¨t Jena, August-Bebel-Str. 2, D-07743 Jena, Germany
Received 1 November 2006; received in revised form 29 November 2006; accepted 30 November 2006
Available online 9 December 2006
Abstract
Improved syntheses of a series of [(L)2Pt(g2-nb)] (4)–(8) (L = PPh3, 1/2 dpp(o-xyl), 1/2 dppb, 1/2 dppbe, 1/2 dppn) complexes are
described. Complexes 4–8 have been characterized by 1H, 31P NMR, IR spectroscopy as well as mass spectrometry and elemental anal-
ysis. The reaction of [(dppbe)Pt(Cl2)] with sodium borohydride and tolan was investigated by 31P NMR spectroscopy. The complex
[(dppbe)Pt(g2-tolan)] (11) has been isolated and characterized. The reactivity of [(dppn)Pt(g2-nb)] with the spirocyclohexyl-1,2,4-trithio-
lane 12 and the sterically hindered 2,2,4,4-tetramethyl-3-thioxocyclobutanone 13 was tested. The complex [(dppn)Pt(g2–13)] (14) has
1
been isolated and characterized by H, 31P NMR, IR spectroscopy as well as mass spectrometry and elemental analysis. X-ray crystal
analyses have been performed on complex 8, 11 and 14.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Platinum(0) complexes; Olefin complexes; Thioketone complex; Alkyne complex
1. Introduction
is [(Ph3P)2Pt(g2-C2H4)] (2), prepared by the reduction of
[(Ph3P)2Pt(II)Cl2] (1) with sodium borohydride under an
atmosphere of ethene [7] (Scheme 1). Various other reduc-
tion agents like sodium amalgam, sodium naphthalene,
superhydride, hydrazine have been used successfully for
syntheses of analogous derivatives [4,8,9]. Nevertheless
sodium borohydride seams to be the best chose for our pur-
poses, it is mild but enough reactive, not highly toxic, non-
flammable and moreover, rather cheap.
Here we report on the improved synthesis of
[(Ph3P)2Pt(g2-nb)] (4) (nb = norbornene) [9,10] as well as
preparation of complexes [(L)2Pt(g2-nb)] (5)–(8) with
bisphosphane ligands dppb (1,4-bisdiphenylphosphinobu-
tane), dpp(o-xyl) 1,2-bis[(diphenylphospino)methyl]-ben-
zene, dppbe (1,2-bisdiphenylphosphinobenzene) and dppn
(1,8-bisdiphenylphosphinonaphthalene).
[(Ph3P)2Pt(g2-C2H4)] (2) was prepared for the first time
by Cook and Jauhal in 1967 [1]. Since this time it has been
widely used as starting material: the complex is used for a
clean source of the 14 electron metal complex [(Ph3P)2-
Pt(0)] (3), which is used to trap unstable molecular species
by complexation [2]. The high ligand field stabilization
energy results in a high kinetic stability of the formed
adducts. The complex fragment with the general formula
(R3P)2Pt containing the two 31P nucleus and the 195Pt iso-
tope offers the possibility to investigate very easily the
products by 31P NMR spectroscopy determining the J(P,
2
1
P) and J(P, Pt) coupling constants. Also insertion reac-
tions into various bounds especially into sulfur–sulfur
bonds have been reported recently [3,4]. The high binding
tendency of such complex fragments to sulfur containing
species allows the isolation and determination of unstable
species [5,6]. The mostly used complex for this experiments
2. Results and discussion
The displacement of the ethene by norbornene (nb) does
not lead to significant changes in the reactivity of the
resulting complex 4. This displacement allows the synthesis
*
Corresponding author. Tel.: +49 3641 948160; fax: +49 3641 948102.
E-mail address: c8wewo@uni-jena.de (W. Weigand).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.11.051

H. Petzold et al. / Journal of Organometallic Chemistry 692 (2007) 2736–2742
2737
PPh3
Pt
Ph
P
Ph
Ph
Ph
P
Ph
H
Ph
Ph3P Cl
Pt
Ph3P
Ph3P
Na[BH4]
Ph
Ph
+2H-
-2Cl-
P
+tolan
-H2
Cl
+
Pt
+
Pt
Pt
Pt
Ph3P Cl
PPh3
H
Cl
P
P
P
Ph Ph
Ph Ph
Ph Ph
1
2
3
Scheme 1. Synthesis of (Ph3P)2Pt(g2-C2H4) (2).
9
10
11
Scheme 3. Preparation of tolan complex 11.
of 4 under a standard argon atmosphere. An excess of the
olefin is easily achieved by adding the solid nb instead of
working under ethene atmosphere. The olefin complexes
[(L)2Pt(g2-nb)] (4)–(8) are stable in nb containing solution,
they are not sensitive against water or bases. The workup
can be done by adding water to the reaction mixture fol-
lowed by extraction with a mixture of THF/diethylether
and adding some crystals of nb. Working with nb instead
of ethene allows to concentrate the solvent under reduced
pressure without decomposition of the complexes. Thus,
sodium borohydride by washing with water a broad singlet
at d = 60.9 with 195Pt-satellites and 1J(P, Pt) = 1858 Hz
was observed in the 31P NMR spectrum assignable to the
complex [(dppe)PtH2] (10). After adding diphenylacetylene
(tolan) complex [(dppbe)Pt(g2-tolan)] (11) has been quanti-
tatively formed within 30 min (Scheme 3). Crystals of the
slightly red colored complex 11 are yielded by slow diffu-
sion of pentane in a solution of 11 in THF. The result of
X-ray structure analysis is presented in Fig. 1. The P–Pt–
P angle is 86.56(4)ꢁ, the bond lengths are in the same range
of those reported for [(Ph3P)2Pt(g2-tolan)], the angle C1–
C2–C3 with 145.4(3)ꢁ is slightly larger than those in
[(Ph3P)2Pt(g2-tolan)] (140ꢁ) [15]. In contrast to the dichloro
complexes [(L)2PtCl2], the yielded complexes 4–8 and 11
are well soluble in CH2Cl2, THF or toluene. [(dppb)Pt-
(g2-nb)] (5) and [(dpp(o-xyl))Pt(g2-nb)] (6) are yielded as
colorless crystalline compounds whereas [(dppbe)Pt-
a
better separation from impurities like unreacted
[(Ph3P)2Pt(II)Cl2] (1) as well as sodium borohydride is pos-
sible. The crude products, which are pure enough for fur-
ther reactions, can be recrystallized from THF/pentane.
In the 31P NMR of 4 only one signal with platinum satel-
1
lites is found at d = 37.5 with J(P, Pt) = 3550 Hz, which
proves that nb is coordinated exclusive from only one of
the two possible sides. In the 1H NMR spectrum the olefin
protons are detected at d = 2.32 with platinum satellites
2
with a typical J(H, Pt) coupling constant of 64 Hz. The
latter data agree very well with that reported in the litera-
ture [9,10].
As mentioned above, the complex 2 is used as source for
14 electron complex [(Ph3P)2Pt(0)] (3), which has a linear
geometry. A fixation of the P–Pt–P angle by using a bis-
phosphine ligand leads to a dramatical increase of the reac-
tivity of the resulting 14 electron complex [11,12]. This
increase is caused by a decrease of the distance between
the HOMO and the LUMO of this complexes. Both orbi-
tals are directed to the binding side of the complex frag-
ment [12]. Keeping these facts in mind a significant
change in the reactivity is suspected by displacement of
the Ph3P ligand by bisphosphines with fixed small P–Pt–P
angles. Reduction of the platinum(II) complexes [(L)2-
PtCl2] with sodium borohydride in the presents of nb in
THF leads to the bisphosphine platinum(0) complexes
5–7 (Scheme 2).
The dihydrido complexes [(L)2PtH2] can be assumed as
intermediate for the reduction [14], in the case of the reduc-
tion of complex [(dppe)PtCl2] (9) the formation of such an
intermediate was proved by 31P NMR investigations. After
reduction in CD2Cl2 and decomposition the excess of
Fig. 1. ORTEP drawing of the molecular structure of complex 11.
Selected bond lengths (A) and angles (ꢁ) : Pt–P(2) 2.2604(10), Pt–P(1)
2.2664(10), Pt–C(1) 2.038(3); Pt–C(6) 2.041(3), C(1)–C(2) 1.301(4), P(2)–
˚
Pt–P(1) 86.56(4), C(1)–Pt–C(2) 37.19(12), C(1)–C(2)–C(3) 145.4(3).
Ph2
Ph3P
Ph3P
PPh2
Pt(η2-nb)
PPh2
PPh2
Pt(η2-nb)
PPh2
PPh2
P
Pt(η2-nb)
Pt(η2-nb)
Pt(η2-nb)
P
PPh2
Ph2
4
5
6
7
8
Scheme 2. Platinum(0) nb complexes.

2738
H. Petzold et al. / Journal of Organometallic Chemistry 692 (2007) 2736–2742
(g2-nb)] (7) is a yellow and [(dppn)Pt(g2-nb)] (8) a red col-
ored solid, respectively (see Table 1).
In the series of platinum(0) complexes 5–8 there is a
trend of the 1J(P, Pt) coupling constants. The values of this
coupling constants decreases with the P–Pt–P bit angle of
the phosphine ligand, in the range of 3550 Hz for complex
4 with P–Pt–P of 112ꢁ, 3459 Hz for complex 6 with 105ꢁ
[16] over 3159 Hz for complex 7 with P–Pt–P of round
1
87ꢁ down to 3027 Hz for complex 8. The small J(P, Pt)
coupling constant and the red color of complex 8 suggested
a small P–Pt–P angels as found in the red methylene
bridged bisphosphine complexes like (dtbpm)Pt(g2-olefin)
1
with J(P, P) < 3000 Hz and P–Pt–P < 80ꢁ [12,13,17].
The result of the X-ray structure analysis for [(dppn)-
Pt(g2-nb)] (8) is shown in Fig. 2. The P–Pt–P angle was
found to be 88.67(5)ꢁ slightly larger then expected from
the 1J(P, Pt) coupling constant. The P–P distance is
3.15 A, approximately 0.1 A longer then that reported for
the free ligand [18], therefore no additional repulsion
energy between the donating atoms has to be surmounted
for the coordination of the dppn-ligand to the metal center.
The energy, which is necessary for the abstraction of the
olefin, increases by decreasing the P–Pt–P angle, therefore
the complexes are no efficient source for forming the 14
electron complex fragments [(L)2Pt(0)].
Fig. 2. ORTEP drawing of the molecular structure of complex 8. Selected
bond lengths (A) and angles (ꢁ) : Pt–P(2) 2.2532(14), Pt–P(1) 2.2528(14),
Pt–C(1) 2.117(5); Pt–C(6) 2.109(5), C(6)–C(1) 1.469(8), P(2)–Pt–P(1)
˚
˚
˚
88.67(5), C(1)–Pt–C(6) 40.7(2).
In extension of our investigations concerning the reac-
tions of complex 2 with 1,2,4-trithiolanes [5,19], complex
8 was treaded with the spirocyclohexyl-1,2,4-trithiolane
12 in a NMR tube, even after two weeks at room temper-
ature the starting materials were found unreacted side by
Table 1
Crystallographic data for 8, 11 and 14
8
11
14
Empirical formula
Formula weight (g/mol)
Colour
C
893.88
Red
41H36P2Pt Æ 1.5 C4H8O
C44H34P2Pt
819.74
Orange
0.04 · 0.04 · 0.04
Triclinic
C42H38OP2PtS
847.81
Light yellow
0.05 · 0.05 · 0.04
Monoclinic
P21/n
13.2547(8)
15.3119(9)
17.0103(9)
–
98.701(4)
–
Crystal size (mm)
Crystal system
Space group
0.03 · 0.03 · 0.02
Monoclinic
P21/c
11.8301(4)
15.3119(9)
17.0103(9)
–
92.359(2)
–
3849.2(2)
4
ꢀ
P1
˚
a (A)
11.393(2)
11.505(2)
14.048(3)
82.34(3)
71.74(3)
88.09(3)
1733.0(6)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
3412.6(3)
4
Z
F(000)
qcalcd.
1800
1.543
37.66
812
1.571
41.72
1688
1.650
43.01
l (Mo Ka) (cmÀ1
Temperature (ꢁC)
)
À90
À90
À90
Reflections collected
27139
12175
15140
Absorption correction min/max transmission
Multi-scan 0.8158/0.8755
8803 (0.0699)
À15/14
Multi-scan 0.7515/0.8174
7852 (0.0250)
À14/14
Multi-scan 0.6490/0.7896
7935 (0.0757)
0/17
Independent reflections (Rint
)
h
k
À26/24
À14/14
À20/20
l
À20/20
À18/18
À22/21
H range (ꢁ)
Completeness to Hmax (%)
2.59 6 H P 27.50
99.5
3.08 6 H P 27.47
98.9
2.11 6 H P 27.85
97.7
Reflections with Fo > 4r(Fo)
6250
7084
4622
Number of parameters, restraints
R1, wR2 [Fo > 4r(Fo)]
R1, wR2 (all data)
Goodness-of-fit
Extrema of final difference Fourier synthesis (e/A )
419, 0
424, 0
424, 0
0.0437, 0.0934
0.0777, 0.1052
1.029
2.259/À2.149
0.0269, 0.0607
0.0329, 0.0631
1.026
0.877/À1.393
0.0456, 0.0869
0.1028, 0.1051
0.949
0.961/À2.060
3
˚

H. Petzold et al. / Journal of Organometallic Chemistry 692 (2007) 2736–2742
2739
Ph2
P
S
S
S
PPh2
S
PPh2
Pt(η -nb)
PPh2
Pt(η2-nb)
+
Pt
2
+
S
PPh2
P
Ph2
O
O
8
12
8
13
14
Scheme 4. Attempts for reaction of complex 8 with the 1,2,4-trithiolane
derivative 12.
Scheme 6. Preparation of a thioketone complex 14.
side. The same result was observed after additional heating
of this mixture for 3 h at 80 ꢁC (Scheme 4).
This is in contrast to the reaction of the [(Ph3P)2Pt(g2-
C2H4)] (2) or [(Ph3P)2Pt(g2-nb)] (4) with spirocyclohexyl-
1,2,4-trithiolane 12 [20] (Scheme 5). The substitution of
the nb by another strongly binding olefinic compound is
possible via an associative mechanism. The reaction of
the sterically hindered 2,2,4,4-tetramethyl-3-thioxocyclo-
butanon 13 quantitatively leads to a new complex 14
yielded as yellow crystals within two hours at room temper-
ature (Scheme 6).
In the 31P NMR spectrum of 14 an AB spin system was
2
1
found with J(P, P) of 28 Hz and J(P, Pt) = 3972 Hz and
2472 Hz, respectively. The elemental analysis as well as the
found molar peak at m/z = 847 confirmed to the formula
C42H38P2PtS. The result of the X-ray structure analysis is
shown in Fig. 3. The thioketone 13 substituted the nb
ligand and is now side on coordinated to the (dppn)Pt com-
plex fragment. The P–Pt–P angle was determined as
87.81(6)ꢁ and is comparable with those found in the nb
complex 8. Worth to notice is the high pyramidalization
of the thioketone carbon atom. The sum of the angles
C2–C1–C4/S1–C1–C2/S1–C1–C4 330ꢁ is slightly larger
than the sum of the angles in an ideal tetrahedron with
328.5ꢁ.
Fig. 3. ORTEP drawing of the molecular structure of complex 14.
Selected bond lengths (A) and angles (ꢁ) : Pt–P(2) 2.2468(15), Pt–P(1)
2.2713(16), Pt–S 2.2784(16), Pt–C(1) 2.134(6), S–C(1) 1.756(7), P(2)–Pt–
˚
P(1) 87.81(6), S–Pt–C(1) 46.77(17).
70 ꢁC into the corresponding thioketone and thiosulfine
[21], whereas the splitting of alkyl substituted 3,3,5,5-ter-
amethyl-1,2,4-trithiolane is observed at significantly higher
temperatures (boiling toluene, 48 h) [22].
In conclusion we succeeded in an improvement of the
syntheses of bisphosphine platinum(0) olefin complexes
[(L)2Pt(g2-olefin)]. The synthesized complexes especially
the complex 7, 8 and 11are not very air and moisture sen-
sitive. The reactivity for displacing the olefin by sulfur con-
taining compounds depends on the bisphosphine ligand
giving the possibility of tuning the reactivity of such com-
plexes [(L)2Pt(g2-nb)].
Complex 14 crystallized in the centrosymmetric space
1
group P21/n including a racemic mixture of 14. In the H
NMR spectrum only two signals each for two equivalent
methyl groups were found, hence the conformation of the
complex has to change very fast in terms of the NMR time
scale between two diastereoisomers having the platinum
atom below and above the plane of the naphthalene rings,
respectively.
The above mentioned result indicates that complex 8
shows a significantly reduced reactivity towards 1,2,4-tri-
thiolane 12, but is still reactive towards the sterically
crowded thioketone 13. This should give us the possibility
to trap selectively thiocarbonyl derivatives in the presents
of 1,2,4-trithiolanes. This is highly interesting having in
mind that 3,3,5,5-teraphenyl-1,2,4-trithiolane splits at
3. Experimental
All reactions were performed under argon, and solvents
are of commercial quality. Starting materials 1 [7], other
dichlorocomplexes [8,23], 13 [24] and 12 [25] are prepared
according to the literature procedure.
S
S
S
Pt
Ph3P
Ph3P
Ph3P
Ph3P
S
S
Ph3P
Pt(η2-nb)
+
2
Pt
+
S
Ph3P
4
12
Scheme 5. Reaction of complex 4 with 12 [20].

2740
H. Petzold et al. / Journal of Organometallic Chemistry 692 (2007) 2736–2742
3.1. X-ray measurements
and the mixture was stirred at room temperature over
night. The reduction is completed when the platinum com-
plex is dissolved in the THF/ethanol solution and only a
slight opaqueness (caused by the sodium borohydride) is
visible. Adding water (4 mL) and a mixture of ether/THF
(for the complexes with small P–Pt–P angle also CH2Cl2
can be used) to the reaction mixture resulted in separation
of two clear phases. The organic layer was washed with
water using a pipette, additional drying of the organic layer
is possible by stirring with sodium sulfate for a few min-
utes. Reducing of solvents to dryness yields the crude prod-
ucts in a yield of 60–80% which are pure enough for further
reactions. An additional purification can be achieved by
dissolving the crude product in a small volume of nb con-
taining THF. Filtration through celiteꢂ (for all complexes
except 4 also filtration over a short pad of silica gel is pos-
sible) and diffusion of pentane into this solution yields the
crystalline compounds of analytical grade.
The intensity data for the compounds were collected on
a Nonius KappaCCD diffractometer, using graphite-
monochromated Mo Ka radiation. Data were corrected
for Lorentz and polarization effects and for absorption
effects [26,27].
The structures were solved by direct methods (SHELXS
[27]) and refined by full-matrix least squares techniques
against |Fo|2 (SHELXL-97 [28]). All hydrogen atoms of the
structures were included at calculated positions with fixed
thermal parameters. All non-disordered, non-hydrogen
atoms were refined anisotropically [28]. XP (SIEMENS
Analytical X-ray Instruments Inc.) [28] and Ortep-3 for
Windows [29] were used for structure representations.
3.2. Spectroscopic measurements
Melting points were determined with an AXIOLAB
microscope with a TMHS 600 heating plate and are uncor-
3.3.1. [(Ph3P)2Pt(g2-nb)] (4)
rected. H (200 MHz), 31P (81 MHz) spectra were deter-
M.p. 138–143 ꢁC (decomp) (lit.: 140–145 ꢁC [9]). 1H
NMR (CD2Cl2): d 7.28 (m, 30H), 2.32 (s with 195Pt-sat.,
2J(H, Pt) = 64.5 Hz, 2H), 2,26 (s, 2H), 1.61-0.73 (m, 5H);
0.18 (d, J(H, H) = 8 Hz). 31P NMR (CD2Cl2): d 37.5 (s
with 195Pt-sat., 1J(P, Pt) = 3550 Hz (lit.: 3550 Hz) [10]).
IR (KBr) : m (cmÀ1) = 3054(w), 2946(s), 2861(w),
1635(bs), 1479(m), 1434(s), 1095(s), 743(m), 694(s),
517(m). Anal. Calc. for C43H40P2Pt: C, 63.46; H, 4.95.
Found: C, 63.53; H, 4.95%.
1
mined with or Brucker DPX 200 spectrometers at 25 ꢁC,
chemical shifts are referred to the protons of the solvent.
All 31P NMR and 13C NMR spectra are proton decoupled.
IR spectra were taken with a Perkin–Elmer System 2000
FT-IR spectrometer. Mass spectra were taken with a
FINNIGAN MAT SSQ 710 mass spectrometer. Elemental
analysis were performed with a LECO CHNS-932.
3.2.1. NMR investigation of synthesis of 11
[(dppbe)Pt(Cl2)] (9) (15 mg, 0.02 mmol) was suspended
in a mixture of CD2Cl2 (1 mL) and ethanol (0.1 mL).
Sodium borohydride (2 mg, 0.05 mmol) was added. After
stirring this suspension for 1 h the excess of sodium boro-
hydride was removed by the use of water. The organic layer
was separated and 31P NMR spectra was recorded. A
broad singlet at d = 60.9 with 195Pt-satellites and 1J(P,
Pt) = 1858 Hz was observed. After tolan was added to this
solution and additional stirring for 30 min, almost quanti-
tatively formation of 11 was observed in 31P NMR spectra.
3.3.2. [(dppb)Pt(g2-nb)] (5)
M.p. 180 ꢁC (decomp). 1H NMR (toluene-d8): d 7.55 (m,
8H), 7.00 (m, 12H), 2.68 (m, 3H), 2.51 (s, 2H), 2.28 (m,
4H), 1.60 (m, 4H); 1.28 (m, 4H); 0.41 (d, J(H, H) = 8 Hz,
1H). 31P NMR (toluene-d8): d 29.3 (s with 195Pt-sat.,
1J(P, Pt) = 3338 Hz). MS (DEI): m/z = 619 (M+-nb,
100%), 714 (M+, 3%). Anal. Calc. for C35H38P2Pt: C,
58.74; H, 5.65. Found: C, 58.91; H, 5.35%.
3.3.3. [(dpp(o-xyl))Pt(g2-nb)] (6)
M.p. 158 ꢁC. 1H NMR (toluene-d8): d 7.54 (m, 8H), 7.03
(m, 12H), 6.59 (m, 2H), 6.13 (m, 2H), 3.83 (m, 4H, P–CH2–
Ar), 2.67 (s, 2H), 2.42 (s with 195Pt-sat., 2J(H, Pt) = 62 Hz,
2H), 1.52 (m, 2H), 1.25 (m, 2H), 1.01 (m, 1H), 0.32
(bs, 1H). 31P NMR (toluene-d8): d 29.3 (s with 195Pt-sat.,
1J(P, Pt) = 3439 Hz). MS (DEI): m/z = 66 (100%), 668
(M+-nb, 25%), 762 (M+, 7%). IR (KBr): m (cmÀ1) =
3054(w), 2944(s), 2859(w), 1638(bs), 1435(s), 1098(s), 768
(m), 741(s), 695(s), 503(s). Anal. Calc. for C39-
H38P2Pt Æ 2THF: C, 62.17; H, 5.99. Found: C, 62.08; H,
6.05%.
3.2.2. NMR investigation of reaction of 8 with 12
In a NMR tube 8 (20 mg, 0.02 mmol) and a excess of 12
(20 mg, 0.075) were dissolved in toluene-d8 (0.7 mL). After
2 h only signals for 8 were found in the 31P NMR spectra.
After storing this probe for 2 weeks at room temperature
the same signals were observed. Additional heating this
probe at 80 ꢁC for 3 h leaded as well to no significant
change of the 31P NMR spectra.
3.3. Synthesis of the [(L)2Pt(g2-nb)] complexes
For the synthesis of the [(L)2Pt(g2-nb)] complexes 4–8
the following procedure was used. Under an argon atmo-
sphere 100–150 mg of the [(L)2Pt(Cl2)] complex and
250 mg nb were suspended in THF (8 mL) and ethanol
(2 mL). Solid sodium borohydride (20 mg) was added
3.3.4. [(dppbe)Pt(g2-nb)] (7)
M.p. >250 ꢁC. UV/Vis k (log(e)): 304 nm (3.95). 1H
NMR (toluene-d8): d 7.55 (m, 8H), 6.90 (m, 16H), 3.05 (s
2
with 195Pt-sat., J(H, Pt) = 66 Hz, 2H), 3.02 (s, 2H), 1.75
(m, 2H), 1.01 (m, 2H), 1.42 (m, 2H), 1.2-1.5 (m, 3H),

H. Petzold et al. / Journal of Organometallic Chemistry 692 (2007) 2736–2742
2741
0.55 (d, J(H, H) = 8 Hz, 1H). 31P NMR (toluene-d8): d 58.1
Pt) = 3972 Hz) and 9.5 (d with 195Pt-sat., 1J(P,
Pt) = 2472 Hz) 2J(P, P) = 28 Hz]. MS (DEI): m/z = 42
(100%), 776 (M+–Me2@C@O, 30%), 818 (M+–(CO),
1.5%), 847 (M+, 1%). IR (KBr): m (cmÀ1) = 1752(s,
C@O), 589(m), 524(m), 521(m), 500(m). Anal. Calc. for
C42H38OP2PtS: C, 59.50; H, 4.52; S, 3.78. Found: C,
59.11; H, 4.57; S, 3.46%.
1
(s with 195Pt-sat., J(P, Pt) = 3159 Hz). MS (DEI): m/z =
640 (M+-nb, 100%), 735 (M+, 15%). IR (KBr): m
(cmÀ1) = 3053(w), 2942(s), 2860(w), 1637(bs), 1435(s),
1119(s), 1100(s), 745(m), 694(s), 568(s), 539(m), 523(m),
506(m). Anal. Calc. for C37H34P2Pt: C, 60.41; H, 4.66.
Found: C, 60.11; H, 4.69%.
3.3.5. [(dppn)Pt(g2-nb)] (8)
Acknowledgement
M.p. 156–160 ꢁC. UV/Vis k (log(e)): 298 (4.2), 445 nm
(2.95). 1H NMR (toluene-d8): d 7.51 (m, 2H), 7.41 (m,
2H), 7.30 (m, 8H), 6.88 (m, 12H), 2.97 (s, 2H), 2,83 (s with
Financial support for this work was provided by the
Freistaat Thuringen (H.P.).
¨
2
195Pt-sat., J(H, Pt) = 64 Hz, 2H), 1.77 (m, 2H), 1.59 (m,
1H), 1.42 (m, 2H), 0.61 (d, J(H, H) = 8 Hz, 1H). 31P
Appendix A. Supplementary material
NMR (toluene-d8):
d
25.3 (s with 195Pt-sat., 1J(P,
Pt) = 3027 Hz). MS (DEI): m/z = 690 (M+-nb, 100%),
784 (M+, 40%). IR (KBr): m (cmÀ1) = 3052(w), 2942(s),
2858(w), 1630(bs), 1434(s), 1118(s), 1095(s), 771(m),
744(m), 693(s), 529(m), 517(m), 492(m). Anal. Calc. for
C41H36P2Pt Æ 1.5THF: C, 63.15; H, 5.41. Found: C, 62.98;
H, 5.38%.
CCDC 624774, 624775 and 624776 contain the supple-
mentary crystallographic data for 8, 11 and 14. These data
can be obtained free of charge via http://www.ccdc.cam.
ac.uk/conts/retrieving.html, or from the Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2006.11.051.
3.4. Synthesis of tolan and thioketone complexes
3.4.1. Synthesis of [(dppbe)Pt(g2-tolan)] (11)
[(dppbe)Pt(Cl2)] (9) (70 mg, 0.1 mmol) was suspended in
a mixture of CH2Cl2 (5 mL) and ethanol (1 mL). Sodium
borohydride (10 mg, 0.26 mmol) was added, the suspension
was stirred until an almost clear solution was formed.
Water (5 mL) was added to this mixture and the organic
layer was separated. To this solution tolan (35 mg,
0.2 mmol) was added. After stirring for 2 h the solution
was reduced to dryness, recrystallization of the crude prod-
uct from THF/pentane yielded 11 (60 mg, 0.07 mmol, 70%)
as light orange crystals.
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