Cyano-bridged Fe-CN-Pt-NC-Fe chain complexes: Structural and spectroscopic characterization of four isomers of [{η5-(1-phenylborole)Fe(CO)2(μ-CN)} 2Pt(PEt3)2]

Article abstract of DOI:10.1016/S0022-328X(98)01089-4

The cyanometalate [η⁵-(1-phenylborole)Fe(CO)₂CN]^- is used as a building block for the synthesis of heterometallic complexes. It reacts with platinum(II) precursors with formation of cyanide-bridged Fe/Pt complexes and various isomeric structures are observed depending upon the orientation of the CN ligand (linkage isomers Fe-(μ-CN)-Pt or Fe-(μ-NC)-Pt) and the cis or trans geometry around the platinum centre. Complex 7 with a Fe-(μ-NC)-Pt-(μ-CN)-Fe chain was obtained from the reaction of trans-[Pt(CN)₂(PEt₃)₂] with [η⁵-(1-phenylborole)Fe(CO)₂(OEt₂)]. The crystal structure of cis-[{η⁵-(1-phenylborole)Fe(CO)₂(μ-CN)} ₂Pt(PEt₃)₂] (2) which contains a Fe-(μ-CN)-Pt-(μ-NC)-Fe chain has been determined by X-ray diffraction.

Full text of DOI:10.1016/S0022-328X(98)01089-4

Journal of Organometallic Chemistry 580 (1999) 66–71
Cyano-bridged Fe–CN–Pt–NC–Fe chain complexes: structural and
spectroscopic characterization of four isomers of
[{h5-(1-phenylborole)Fe(CO)2(m-CN)}2Pt(PEt3)2]ꢀ
Pierre Braunstein a,*, Gerhard E. Herberich b,1, Mark Neuschu¨tz a,b, Martin U. Schmidt b
a Laboratoire de Chimie de Coordination, UMR 7513 CNRS, Uni6ersite´ Louis Pasteur, F-67070 Strasbourg Cedex, France
b Institut fu¨r Anorganische Chemie der Rheinisch–Westfa¨lischen, Technischen Hochschule Aachen, Prof. Pirlet Str. 1, D-52074 Aachen, Germany
Received 21 September 1998
Abstract
The cyanometalate [h5-(1-phenylborole)Fe(CO)2CN]− is used as a building block for the synthesis of heterometallic complexes.
It reacts with platinum(II) precursors with formation of cyanide-bridged Fe/Pt complexes and various isomeric structures are
observed depending upon the orientation of the CN ligand (linkage isomers Fe–(m-CN)–Pt or Fe-(m-NC)–Pt) and the cis or trans
geometry around the platinum centre. Complex 7 with a Fe–(m-NC)–Pt–(m-CN)–Fe chain was obtained from the reaction of
trans-[Pt(CN)2(PEt3)2] with [h5-(1-phenylborole)Fe(CO)2(OEt2)]. The crystal structure of cis-[{h5-(1-phenylborole)Fe(CO)2(m-
CN)}2Pt(PEt3)2] (2) which contains a Fe–(m-CN)–Pt–(m-NC)–Fe chain has been determined by X-ray diffraction. © 1998
Elsevier Science S.A. All rights reserved.
Keywords: Heterometallic complexes; Iron; Platinum; Cyanide ligand; Borole ligand; Linkage isomerism
We have previously used the cyanomanganate anion
[(MeCp)Mn(CO)2CN]− for the synthesis of het-
erometallic complexes containing cyanide bridges, in-
cluding a unique double-helix-type Pd4Mn4 cluster [2].
This led us to consider the possibility of using the
1. Introduction
The synthesis and reactivity of oligonuclear transi-
tion metal complexes with cyanide bridges is gaining
increasing interest owing to their often remarkable
structural, physical and chemical properties. These have
been discussed in recent review articles [1]. In contrast
to its isoelectronic analogue CO, the cyanide ion dis-
plays good donor properties at both its C and N atoms.
This implies that controlling the orientation of the
M–CN–M% link (with M and M% being different metals
or the same metal in different oxidation states) and the
cyanide–isocyanide isomerism will represent important
synthetic challenges on which many properties will
depend.
isoelectronic
reagent
[h5-(1-phenylborole)Fe(CO)2
CN]− as a building block for the synthesis of het-
erometallic complexes that could display interesting
features.
2. Results and discussion
The reaction of cis-[PtCl2(PEt3)2] in dichloromethane
with the cyanoferrate [h5-(1-phenylborole)Fe(CO)2-
CN]− (1), obtained by treating [h5-(1-phenylborole)-
Fe(CO)3] with lithium-bis(trimethylsilyl)amid [3], af-
forded via halide substitution the cyano-bridged iron-
platinum complex cis-[{[Fe](m-CN)}2Pt(PEt3)2] (2) ([Fe]
represents the h5-(1-phenylborole)Fe(CO)2 fragment).
ꢀ This work is based on the PhD thesis of M.N.
* Corresponding author. Fax: +33-3-88-41-6030.
E-mail address: braunst@chimie.u-strasbg.fr (P. Braunstein)
1 Also corresponding author.
0022-328X/99/$ - see front matter © 1998 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(98)01089-4

P. Braunstein et al. / Journal of Organometallic Chemistry 580 (1999) 66–71
67
This complex is soluble in dichloromethane but only
slightly soluble in hexane Eq. (1).
(1)
Single-crystals of 2 were grown from dichloromethane/
hexane as light yellow, not very air-sensitive needles.
An X-ray crystal structure determination showed this
compound to have C2-symmetry with the Pt atom on
the 2-fold crystallographic axis (Fig. 1). Selected inter-
atomic distances and angles are given in Tables 1 and 2,
respectively. The [Fe]CN-fragments of 2 show no un-
usual structural features. The ‘slip-distortion’ [4] of the
Fig. 1. PLATON-plot [16] of cis-[{[Fe](m-CN)}2Pt(PEt3)2] (2). Dis-
placement ellipsoids are drawn at 30% probability.
˚
borole ligand is of 0.048 A and the distance between the
boron atom and the best plane defined by the four
5
˚
carbon atoms is 0.079 A, supporting a h -coordination
of the borole ligand. The bridging cyano ligand is
almost linearly coordinated to the iron fragment, while
the coordination to the platinum atom deviates from
linearity by about 12(2)°, causing the cyano group to
protrude from the Pt-coordination plane. This distor-
tion appears to result, at least in part, from steric
hindrance as indicated by the opening of the P–Pt–P-
angle from the ideal value of 90 to 97.2(3)°. Accord-
ingly, the N–Pt–N-angle is reduced to 84.6(8)°. The
separation between the metal centres Pt···Fe is 5.025(3)
˚
A.
In principle, the two phosphine ligands could be
either cis or trans with respect to each other and the
two bridging cyano ligands could bind to platinum
either through carbon or nitrogen. The resulting six
possible isomers are presented in Scheme 1. Terminal
cyano groups are usually bound to transition metals by
the carbon atom [1,5]. Therefore the synthesis of the
Fe–CN–Pt-isomers 2 and 3 has to start from cyanofer-
rate reagents while the Fe–NC–Pt-isomers 6 and 7
should be accessible starting from cyanoplatinum com-
pounds (Scheme 2). However, since [Pt(CN)2(PEt3)2] is
known only as the trans-isomer, the cis-[Fe]–NC–[Pt]
isomer 6 cannot be obtained in this way. The mixed
cyano/isocyano complexes 4 and 5 are not accessible by
the direct syntheses presented in Scheme 2. The tricar-
bonyl complex [Fe]CO was irradiated in ether as sol-
vent to give the highly reactive ether complex
[Fe](OEt2). When trans-[Pt(CN)2(PEt3)2] was added
subsequently, smooth formation of the trinuclear com-
plex trans-[{[Fe]NC}2Pt(PEt3)2] (7) took place.
Scheme 1.
Table 1
˚
Selected interatomic distances in cis-[{[Fe](m-CN)}2Pt(PEt3)2 (2) (A)
Pt–P
Pt–N
2.259(5)
2.02(1)
1.12(2)
1.77(2)
1.76(2)
1.90(2)
1.13(2)
1.11(2)
2.21(2)
2.12(2)
Fe–C(22)
Fe–C(23)
Fe–C(24)
B–C(21)
C(21)–C(22)
C(22)–C(23)
C(23)–C(24)
C(24)–B
2.09(2)
2.06(2)
2.12(2)
1.55(2)
1.43(2)
1.43(2)
1.41(3)
1.51(2)
1.58(2)
N–C(3)
Fe–C(1)
Fe–C(2)
Fe–C(3)
C(1)–O(1)
C(2)–O(2)
Fe–B
B–C(31)
1
The H- and 13C-NMR signals of the borole ligands
Fe–C(21)
in the cyanoferrates differ significantly from the signals

68
P. Braunstein et al. / Journal of Organometallic Chemistry 580 (1999) 66–71
Table 2
Selected bond angles in cis-[{[Fe](m-CN)}2Pt(PEt3)2 (2) (°)
P–Pt–P%
P–Pt–N%
N–Pt–N%
Pt–P–C(11)
Pt–P–C(13)
Pt–P–C(15)
Pt–N–C(3)
N–C(3)–Fe
Fe–C(1)–O(1)
97.2(3)
89.8(4)
84.6(8)
115.4(6)
115.8(6)
109.3(6)
169(1)
Fe–C(2)–O(2)
C(1)–Fe–C(2)
C(1)–Fe–C(3)
C(2)–Fe–C(3)
C(22)–C(21)–B
C(21)–C(22)–C(23)
C(22)–C(23)–C(24)
C(23)–C(24)–B
C(21)–B–C(24)
179(2)
96.4(9)
94.7(9)
91.8(7)
108(1)
109(2)
111(2)
108(2)
104(2)
177(1)
178(2)
Scheme 3.
of the isocyanoferrates. The cyanoferrates show differ-
ences in the chemical shifts of the 2,5- and 3,4-borole
protons and carbons of approximately 1.8 and 20 ppm,
respectively, while these values are 2.3 and 27 ppm for
the isocyanoferrates, respectively (see Table 3). In the
IR spectra the difference between these bonding modes
is even more striking since the cyanoferrates have wCN
bands of high intensity while these bands are missing or
only very weak in the spectra of the isocyanoferrates.
The wavenumbers of the wCN bands of the cyanoferrate
precursor and corresponding product are identical. The
isocyanoferrates show higher wavenumbers for the wCN
bands. The 31P{1H}-NMR spectra of all compounds
show 195Pt satellites which allow to distinguish between
cis and trans isomers [6], although the chemical shift
alone of these signals is less characteristic and therefore
only used as fingerprints. The 195Pt-NMR signal of
compound 2 is significantly broadened by the adjacent
nitrogen atom of the cyano-ligand. In the case of
compound 7 with the carbon atom of the cyano groups
bound to platinum, the lines are much sharper as the
quadrupole relaxation is considerably less efficient. The
‘hard’ or ‘soft’ character of the ligands at the platinum
atom influences the 195Pt-NMR chemical shift [7]. The
spectroscopic data for the starting materials, the prod-
ucts and of two reference compounds are presented in
Tables 3 and 4.
The cis–trans isomerization of square-planar com-
plexes of the type [PtX2L2] usually proceeds via an
associative–dissociative mechanism and can therefore
be catalyzed by nucleophiles [8,9]. In the case of 2, even
THF is sufficient to catalyse the isomerization. Thus,
keeping a solution of this compound in THF for 3 days
at 50°C afforded a mixture of three trans isomers with
some starting material. The respective proportions were
estimated by integration of the 31P{1H}-NMR signals
to approximately 20% of cis-[([Fe](m-CN)2Pt(PEt3)2] (2),
5% of trans-[{[Fe](m-CN)}2Pt(PEt3)2] (3) and less than
1% of trans-[{[Fe](m-NC)}2Pt(PEt3)2] (7). The main iso-
mer (75%) was identified as the cyano–isocyano species
5 on the basis of spectroscopic data (Scheme 3). Thus,
the NMR signals of the two different borole ligands in
5 show chemical shifts typical for [Fe]–CN–Pt and
[Fe]–NC–Pt units, respectively. There seems to be no
influence of the trans ligand, which is consistent with
the two [Fe]-groups being far enough from each other
to constitute electronically and sterically independent
units in the same molecule.
Keeping a solution of trans-{[Fe]CN}2Pt(PEt3)2 (3)
in THF at 50°C for several days also led to isomeriza-
tion, although it was less advanced than the isomeriza-
tion of the cis isomer under similar conditions.
Addition of triethylphosphine did not appear to accel-
erate the reaction significantly. However, keeping a
melt of 3 at 100°C for a few hours afforded the
expected trans isomers as well as some decomposition
products that were not further investigated. No metal
formation was observed.
Attempts to isomerize trans-([Fe]NC)2Pt(PEt3)2 (7) in
THF at 50°C or as a melt at 100°C failed. Complex 7
therefore appears to be the thermodynamically more
stable isomer.
Scheme 2.

P. Braunstein et al. / Journal of Organometallic Chemistry 580 (1999) 66–71
69
Table 3
1H- and 13C{1H}-NMR signals of the borole ligands (l in ppm)
Compound
H3,4–borole
H2,5-borole
C3,4-borole
92.2
C2,5-borole
72.3
[Fe]CN− (1)a,b
5.04
5.26
5.25
5.12
3.15
3.47
3.37
3.29
[Fe]CNtBuc
cis-([Fe]CN)2Pt(PEt3)2 (2)
trans-([Fe]CN)2Pt(PEt3)2 (3)
92.41
91.69
72.34
72.34
[Fe]NCMec
trans-([Fe]NC)2Pt(PEt3)2 (7)
5.40
5.42
3.20
3.12
95.41
68.49
trans-([Fe]NC)([Fe]CN)Pt(PEt3)2 (5)
[Fe]–CN–Pt
[Fe]–NC–Pt
5.14
5.43
3.32
3.12
91.65
96.55
72.11
69.61
a [Fe] stands for {h5-(1-phenylborole)}Fe(CO)2.
b Ref. [3].
c Ref. [15].
Table 4
wCN-absorptions (in cm−1) and 31P{1H}- and 195Pt{1H}-NMR data (l in ppm)
Compound
wCN
31P{1H}
195Pt{1H}
1JPPt (Hz)
[Fe]CN− (1)a,b
2108 (m)
2155 (s)
2121 (s)
2124 (s)
[Fe]CNtBuc
cis-([Fe]CN)2Pt(PEt3)2 (2)
trans-([Fe]CN)2Pt(PEt3)2 (3)
0.24
15.77
125
3286
2232
[Fe]NCMec
trans-[Pt(CN)2(PEt3)2]
trans-([Fe]NC)2Pt(PEt3)2] (7)
–
2123d
13.19
15.59
−394
−388
2163
2065
2137 (vw)
trans-([Fe]NC)([Fe]CN)Pt(PEt3)2 (5)
[Fe]–CN–Pt
[Fe]–NC–Pt
17.25
2140
2123 (s)
2174 (w)
cis-PtCl2(PEt3)2
trans-PtCl2(PEt3)2
9.0e
32f
3502e
2394e
12.1e
584f
a [Fe] stands for {h5-(1-phenylborole)}Fe(CO)2.
b Ref. [3].
c Ref. [15].
d Ref. [12].
e Ref. [6].
f Ref. [7].
Labor Pascher, Remagen (Germany). The cyanoferrate
[h5-(1-phenylborole)Fe(CO)2(CN)]− (1) was prepared
as described previously [3]. The complex [h5-(1-phenyl-
borole)Fe(CO)2(OEt2)] was obtained by UV-irradiation
of [h5-(1-phenylborole)Fe(CO)3] in diethylether at −
35°C for 3 h. The complex cis-[PtCl2(NCPh)2] was
obtained by treating PtCl2 with PhCN [11] and cis-
[PtCl2(PEt3)2] by substitution of PhCN with PEt3. The
cyano complex trans-[Pt(CN)2(PEt3)2] was obtained by
heating cis-[PtCl2(PEt3)2] with KCN in EtOH [12].
3. Experimental
Reactions were carried out under purified nitrogen,
using standard Schlenk-type techniques. Solvents were
distilled under nitrogen and traces of water were re-
moved by usual methods. Infrared spectra were
recorded on FT-IR Perkin-Elmer 1720 X and FT-IR
Bruker IFS 66/113 spectrometers. NMR spectra were
recorded on Varian VXR 500 (1H, 500 MHz, relative to
TMS, 13C, 125.70 MHz, relative to TMS, 31P, 202.33
MHz, relative to H3PO4) and Bruker WP 80 SY (195Pt,
3.1. Preparation of cis-[{[Fe](v-CN)}2Pt(PEt3)2] (2)
17.15 MHz, relative to external TMS [10] i.e. l(PtCl62−
)
=4522 ppm) spectrometers. The mass spectrum was
obtained with a FAB Fisons ZAB-HF spectrometer.
Elemental analyses were carried out by the Analytisches
A solution of Li(THF)2[{[Fe]CN}] (1) (340 mg, 0.8
mmol) in CH2Cl2 (4 ml) was added to a cooled (−
70°C) solution of cis-[PtCl2(PEt3)2] (200 mg, 0.4 mmol)

70
P. Braunstein et al. / Journal of Organometallic Chemistry 580 (1999) 66–71
Table 5
evaporated to dryness, the residue was dissolved in
dichloromethane (5 ml) and the solution layered with
pentane (5 ml). After 1 day at room temperature the
solution was filtered and the filtrate evaporated to
dryness. The solid was extracted with diethylether (10
ml). Evaporation of this extract to dryness afforded
trans-[{[Fe]CN}2Pt(PEt3)2] (3) as an oily, yellow mass
Crystal data, data collection parameters, and convergence results
for 2
Empirical formula
Crystal colour and shape
Crystal size (mm)
Crystal system
C38H48B2Fe2N2O4P2Pt
Yellow translucent rod
0.10×0.08×0.05
Monoclinic
Space group
C2/c
1
(84 mg, purity ca. 75%, determined by H-NMR). IR
Unit cell dimensions
(CH2Cl2): w(CN) 2124(s), w(CO) 1999(s), 1947(s) cm−1
.
˚
a (A)
20.26(1)
˚
b (A)
11.355(9)
18.949(9)
105.45(5)
4203(5)
1H-NMR (CD2Cl2): l 7.59, 7.22 (m, 10 H, phenyl), 5.12
(m, 4 H, N=5.8 Hz, 3,4-borole), 3.29 (m, 4 H, N=6.1
Hz, 2,5-borole), 1.89 (m, 12 H, CH2), 1.16 (m, 18 H,
CH3). 13C{1H}-NMR (CD2Cl2): l 217.4 (s, 4 C, CO),
134.84 (s, 4 C, ortho-phenyl), 127.69 (s, 4 C, meta-
phenyl), 124.48 (s, 2 C, para-phenyl), 91.69 (s, 4 C,
3,4-borole), 72.34 (s br, 4 C, 2,5-borole), 14.98 (dd, 6 C,
1JCP=3JCP=19 Hz, CH2), 8.03 (s, 6 C, CH3). 31P{1H}-
NMR (CD2Cl2): l 15.77 (s with Pt satellites, 2 P,
1JPPt=2232 Hz).
˚
c (A)
i(°)
3
˚
V (A )
Z
4
Dcalc. (g cm−3
)
z=1.56
v=41.5
1968
Mo–Ka, u=0.7107
(graphite)
253
ꢀ, 3BqB25°
4511
Absorption coefficient (cm−1
)
F(000)
˚
Wavelength (monochromator) (A)
Data collection temperature (K)
Scan type and range
Reflections collected
Independent reflections
Independent reflections observed
Variables refined on F
Agreement factors for observed
data
3722
2120 with I\|(I)
201
3.3. Preparation of trans-[{[Fe]NC}2Pt(PEt3)2] (7)
An excess of [Fe]CO in diethylether (80 ml) was
irradiated at −35°C with the UV-light from a high
pressure Hg vapor lamp. The irradiation was stopped
after 3 h and a slurry of trans-[Pt(CN)2(PEt3)2] in
diethylether was added. While the temperature was
allowed to rise to ambient, a light brown precipitate
formed. The 31P{1H} and 195Pt{1H}-NMR spectra
showed complete conversion of the Pt compound. The
reaction mixture was evaporated to dryness and the
residue extracted with dichloromethane/hexane (1:3).
The extract was evaporated to dryness. The resulting
solid, trans-[{[Fe]NC}2Pt(PEt3)2] (7), contaminated
with some [Fe]CO, was washed with hexane (yield not
determined).
R=0.082, Rw=0.062,
w
−1=|2(Fo)
−3
˚
˚
at 1 A from Pt
Residual electron density
1.7 e A
in CH2Cl2 (4 ml). The reaction mixture was layered
with 15 ml of hexane, thus affording cis-[{[Fe](m-
CN)}2Pt(PEt3)2] (2) (243 mg, 0.25 mmol, 62%) as pale
yellow needles. Anal. Calc. for C38H48B2Fe2N2O4P2Pt:
C, 46.24; H, 4.90; N, 2.84. Found: C, 45.83; H, 4.97; N,
2.93. IR (CH2Cl2): w(CN) 2121(s), w(CO) 1997(s),
1
1945(s) cm−1. H-NMR (CD2Cl2): l 7.64, 7.26 (m, 10
H, phenyl), 5.25 (m, 4 H, N=6.1 Hz, 3,4-borole), 3.37
(m, 4 H, N=6.1 Hz, 2,5-borole), 1.87 (m, 12 H, CH2),
1.19 (m, 18 H, CH3). 13C{1H}-NMR (CD2Cl2): l 217.4
(s, 4 C, CO), 134.95 (s, 4 C, ortho-phenyl), 127.63 (s, 4
C, meta-phenyl), 124.48 (s, 2 C, para-phenyl), 92.41 (s,
4 C, 3,4-borole), 72.34 (s br, 4 C, 2,5-borole), 16.71 (d,
Spectroscopic data for trans-[Pt(CN)2(PEt3)2]: IR
(CH2Cl2): w(CN) 2124(s) cm−1; (KBr): w(CN) 2121(s)
1
cm−1. H-NMR (CD2Cl2): l 2.16 (m, 12 H, CH2), 1.17
(m, 18 H, CH3). 31P{1H}-NMR (CD2Cl2): l 13.2 (s with
Pt satellites, 2 P, 1JPPt=2163 Hz). 195Pt-NMR (CH2Cl2/
1
6 C, JCP=40 Hz, CH2), 8.41 (s, 6 C, CH3). 31P{1H}-
1
CD2Cl2): l −394 (t, 1 Pt, JPPt=2176 Hz).
NMR (CD2Cl2): l 0.24 (s with Pt satellites, 2 P, 1JPPt
=
Spectroscopic data for trans-[{[Fe](m-NC)}2Pt(PEt3)2]
3286 Hz). 195Pt{1H}-NMR (CH2Cl2/CD2Cl2): l 125 (t
(7): IR (CH2Cl2): w(CN) 2135(w), w(CO) 1999(s),
1
br, Pt, JPtP=3300 Hz, Dw1/2=390 Hz). MS (FAB+,
1
1940(s) cm−1. H-NMR (CD2Cl2): l 7.56, 7.25 (m, 10
NBA): m/z=987 (M+/MH+, 1/1.9, 1.5%), 931
H, phenyl), 5.42 (m, 4 H, N=6.1 Hz, 3,4-borole), 3.12
(m, 4 H, N=6.1 Hz, 2,5-borole), 2.00 (m, 12 H, CH2),
1.15 (m, 18 H, CH3). 13C{1H}-NMR (CD2Cl2): l 218.20
(s, 4 C, CO), 167.89 (s, 2 C, CN), 134.77 (s, 4 C,
ortho-phenyl), 128.01 (s, 2 C, para-phenyl), 127.53 (s, 4
C, meta-phenyl), 117.27 (s br, 2 C, ipso-phenyl), 96.51
(s, 4 C, 3,4-borole), 69.59 (s br, 4 C, 2,5-borole), 17.78
(dd, 6 C, 1JCP=3JCP=17.8 Hz, CH2), 8.36 (s, 6 C,
CH3). 31P{1H}-NMR (CD2Cl2): l 15.6 (s with Pt satel-
(M+ −2CO, 7%), 875 (M+ −4CO, 17%), 679 (M+
[Fe]−2CO, 2.8%).
−
3.2. Preparation of trans-[{[Fe](v-CN)}2Pt(PEt3)2] (3)
To a solution of [Fe]CO (100 mg, 0.36 mmol) in
THF (5 ml) was added LiN(SiMe3)2 in small portions
until the IR spectrum showed no bands of the starting
material. Solid trans-[PtCl2(PEt3)2] (90 mg, 0.18 mmol)
was added to this mixture. The yellow solution was
1
lites, 2 P, JPPt=2065 Hz). 195Pt{1H}-NMR (CH2Cl2/
1
CD2Cl2): l −388 (t, Pt, JPtP=2066 Hz).

P. Braunstein et al. / Journal of Organometallic Chemistry 580 (1999) 66–71
71
3.4. Isomerization of (2)
1EZ, UK (fax: +44-1223-336-033; e-mail: de-
posit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk).
A solution of 2 (122 mg, 0.12 mmol) in THF (20 ml)
was kept at 50°C for 3 days. The 31P{1H}-NMR spec-
trum showed the presence of 2 (20%), 3 (5%), trans-
[{[Fe](m-CN)}{[Fe](m-NC)}Pt(PEt3)2] (5) (75%) and 7
(B1%).
Acknowledgements
Spectroscopic data for (5): IR (CH2Cl2): w(NC)
We are grateful to the DAAD for a grant to M.
Neuschu¨tz and to the Centre National de la Recherche
Scientifique (Paris) for financial support.
2174(w), w(CN) 2123(s), w(CO) 1999(s), 1945(s) cm−1
.
1H-NMR (CD2Cl2): l 7.60, 7.24 (m, 5 H, phenyl[Fe]–CN),
7.56, 7.26 (m, 5 H, phenyl[Fe]–NC), 5.43 (m, 2 H, 3,4-
borole[Fe]–NC), 5.14 (m, 2 H, 3,4-borole[Fe]–CN), 3.32 (m,
2 H, 2,5-borole[Fe]–CN), 3.12 (m, 2 H, 2,5-borole[Fe]–NC),
1.95 (m, 12 H, CH2), 1.19 (m, 18 H, CH3). 13C{1H}-
NMR (CD2Cl2): l 218.41 (s, 2 C, CO[Fe]–NC), 217.11 (s,
2 C, CO[Fe]–CN), 134.93, 134.82 (s, 4 C, ortho-phenyl),
127.66, 127.62, 127.56, 127.46 (s, 6 C, meta- and para-
phenyl), 96.55 (s, 2 C, 3,4-borole[Fe]–NC), 91.65 (s, 2 C,
3,4-borole[Fe]–CN), 72.11 (s (br), 2 C, 2,5-borole[Fe]–CN),
69.61 (s br, 2 C, 2,5-borole[Fe]–NC), 16.31 (dd, 6 C,
1JCP=3JCP=17 Hz, CH2), 8.22 (s, 6 C, CH3). 31P{1H}-
NMR (CD2Cl2): l 17.25 (s with Pt satellites, 2 P,
1JPPt=2140 Hz).
References
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4. Crystallography
The X-ray structure determination was performed on
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structure was solved by Patterson methods and refined
on structure factors with the SDP [14] program system.
The carbon atoms of the phenyl ring were refined with
isotropic displacement parameters, other nonhydrogen
atoms with anisotropic displacement parameters, hy-
drogen atoms were included as riding on their carbon
atoms with C–H=98 pm, Uiso(H)=1.3 Ueq(C).
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5. Supplementary material
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Sect. A 24 (1968) 351.
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Crystallographic data (excluding structure factors)
for the structure of 2 have been deposited with the
Cambridge Crystallographic Data Centre as supple-
mentary publication no. CCDC-102988. Copies of the
data can be obtained free of charge on application to
The Director, CCDC, 12 Union Road, Cambridge CB2
[16] A.L. Spek, Program PLATON, University of Utrecht, Utrecht,
The Netherlands, 1994.
.
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