Synthesis of heterobimetallic metal derivatives: A carbene complex as chelate ligand

Article abstract of DOI:10.1002/zaac.200300078

The carbene complex (4-hydroxybenzoxazol-2-ylidene)-pentacarbonyl tungsten (2b) has been synthesized from [(CO)₅W-C≡N-C₆H ₃(OSiMe₃)₂-2,6] by Si-O bond cleavage and subsequent intramolecular cyclization. Compared to 2-aminophenol the acidity of the NH/OH protons is inverted in 2b. Consequently, the stepwise monodeprotonation/methylation of 2b yields exclusively the N-alkylated complex 3. A second deprotonation/methylation gives the N- and O-alkylated complex 4. Complex 4 can be obtained directly from 2b by treatment of with two equivalents of base and two equivalents of MeI. In the presents of one equivalent of base 2b reacts with [Cp₂MoCl₂] under formation of the heterobimetallic chelate complex μ ²-N,O-molybdocene-4-oxobenzoxazol-2-ylidene)-pentacarbonyl tungsten 5. Complexes 2b, 3, 4 and 5 were characterized by X-ray crystallography.

Full text of DOI:10.1002/zaac.200300078

Synthesis of Heterobimetallic Metal Derivatives: a Carbene Complex as Chelate
Ligand
F. Ekkehardt Hahn*, Peter Hein, and Thomas Lügger
Münster, Westfälische Wilhelms-Universität, Institut für Anorganische und Analytische Chemie
Received March 14th, 2003.
Dedicated to Professor Heinrich Nöth on the Occasion of his 75th Birthday
Abstract. The carbene complex (4-hydroxybenzoxazol-2-ylidene)-
pentacarbonyl tungsten (2b) has been synthesized from [(CO)5W-
CϵN-C6H3(OSiMe3)2-2,6] by Si-O bond cleavage and subsequent
intramolecular cyclization. Compared to 2-aminophenol the acid-
ity of the NH/OH protons is inverted in 2b. Consequently, the step-
wise monodeprotonation/methylation of 2b yields exclusively the
N-alkylated complex 3. A second deprotonation/methylation gives
the N- and O-alkylated complex 4. Complex 4 can be obtained
directly from 2b by treatment of with two equivalents of base and
two equivalents of MeI. In the presents of one equivalent of base
2b reacts with [Cp2MoCl2] under formation of the heterobimetallic
chelate complex µ2-N,O-molybdocene-4-oxobenzoxazol-2-ylidene)-
pentacarbonyl tungsten 5. Complexes 2b, 3, 4 and 5 were charac-
terized by X-ray crystallography.
Keywords: Isocyanides; 2,6-Bis(trimethylsiloxy)phenyl isocyanide;
Carbene complexes; Heterobimetallic complexes; Molybdenum;
Tungsten
Synthese von heterobimetallischen Metallderivaten: Ein Carben-Komplex als Chelat-
Ligand
Inhaltsübersicht. Der Carben-Komplex (4-Hydroxybenzoxazol-2-
yliden)pentacarbonylwolfram (2b) wurde aus [(CO)5W-CϵN-
C6H3(OSiMe3)2-2,6] durch Si-O-Bindungsspaltung und nachfol-
gender intramolekularer Zyklisierung erhalten. Die Acidität der
NH/OH Protonen in 2b ist im Vergleich zu 2-Aminophenol inver-
tiert. Daher führt die Monodeprotonierung/Methylierung von 2b
ausschliesslich zum N-alkylierten Komplex 3. Die zweite Deprot-
onierung/Methylierung ergibt den N- and O-alkylierten Komplex
4. Komplex 4 kann direkt durch Reaktion von 2 mit zwei Äquiva-
lenten Base und zwei Äquivalenten MeI erhalten werden. In der
Gegenwart von einem Equivalent Base reagiert 2 mit [Cp2MoCl2]
unter Bildung des heterobimetallischen Chelatkomplexes µ2-N,O-
Molybdocen-4-oxobenzoxazol-2-yliden)pentacarbonylwolfram 5.
Die Komplexe 2b, 3, 4 and 5 wurden durch Röntgenbeugung an
Einkristallen strukturell gesichert.
Introduction
ample, Fehlhammer et al. have introduced readily available
and stable 2-hydroxyalkyl isocyanides such as
CNCH2CH2OH, in which the nucleophile and the isocyano
group are already linked before coordination to the metal
atom. If suitably activated by coordination to transition me-
tals in higher oxidation states these ligands spontaneously
cyclize to form oxazolidin-2-ylidenes [5Ϫ9] allowing even
the isolation of homoleptic tetra [10] and hexacarbene com-
plexes [11].
In β-functional aryl isocyanides the electrophilic isocyan-
ide and the nucleophilic substiutent are not only linked, but
also suitably oriented in one plane for an intramolecular
cycloaddition reaction. This arrangement together with the
aromaticity of the resulting carbene ligand leads to an even
greater tendency to form heterocyclic ylidenes. Si-O bond
cleavage in complexes with the 2-(trimethylsiloxy)phenyl
isocyanide ligand A gives the complex with the 2-hydroxy-
phenyl isocyanide ligand B which, depending on the elec-
tronic situation at the metal atom, exists in an equilibrium
with the ylidene complex C (Scheme 1) [12]. We have stud-
ied the cyclization reaction BǞC at various metal atoms
like B [13], W [14], Cr [15], Re [16], Pd [17,18], Pt [18],
Isocyanides which are coordinated to metal atoms in higher
oxidation states may undergo nucleophilic attack at the ter-
minal carbon atom by a variety of reagents [1Ϫ3]. In par-
ticular with protic nucleophiles, such as alcohols or primary
and secondary amines, the reaction yields metal carbene
complexes [4]. Whereas the addition of nucleophiles HX to
coordinated isocyanides usually leads to the formation of
acyclic carbene complexes, the employment of functional
isocyanides, which contain both the isocyanide group and
the nucleophile in the same molecule, gives access to com-
plexes with heterocyclic carbene ligands through an intra-
molecular 1,2-addition across the CϵN triple bond. For ex-
* Prof. Dr. F. E. Hahn
Institut für Anorganische und Analytische Chemie
Westfälische Wilhelms-Universität Münster
Wilhelm-Klemm-Straße 8
D-41849 Münster, Germany
Fax: ϩ(49-251) 8333108
E-mail: fehahn@uni-muenster.de
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DOI: 10.1002/zaac.200300078
Z. Anorg. Allg. Chem. 2003, 629, 1316Ϫ1321

Synthesis of Heterobimetallic Metal Derivatives
Scheme 1 Equilibrium between complexes with a 2-hydroxyphe-
nyl isocyanide ligand (B) and a benzimidazol-2-ylidene ligand (C).
and Fe [19]. More recently, the cyclization reaction of 2-
aminophenyl isocyanide, leading to NH,NH substituted N-
heterocyclic carbene ligands has been described [20]. In this
contribution we report on the cyclization reaction of tung-
sten-coordinated 2,6-bis(trimethylsiloxyphenyl) isocyanide
after Si-O bond cleavage to give the 4-hydroxybenzoxazol-
2-ylidene ligand, on the N- and O-alkylation of this carbene
ligand and on the use of the carbene complex as a chelate
ligand for the (C5H5)Mo-moiety.
Scheme 2 Synthesis of the complex mixture 2a/2b.
Results and Discussion
The ligand 2,6-bis(trimethylsiloxy)phenyl isocyanide was
obtained as previously described [15]. It can be coordinated
to the W(CO)5 complex fragment to yield the isocyanide
complex 1 in good yield (Scheme 2). Cleavage of the Si-O
bonds in 1 results in the formation of a product mixture
composed of the isocyanide complex 2a and the carbene
complex 2b. Both components of the mixture can be ident-
1
ified by H NMR spectroscopy. The phenolic protons of
the isocyanide complex 2a are observed at δ ϭ 5.59, while
the ylidic NH proton in 2b causes a resonance at δ ϭ 10.46
(in CD2Cl2). By integration of these well separated reson-
ances the ratio of 2a:2b was determined to be to be approxi-
mately 1:3. The analogous chromium complexes have been
prepared previously [15]. Here the equilibrium between the
isocyanide and the carbene complex resides on the side of
the isocyanide derivative (59 %) and the intramolecular
cyclization reaction is more strongly hampered by (dǞπ*)
backbonding from the chromium atom.
Figure 1 ORTEP plot of one of the two independent molecules
of 2b·H2O in the asymmetric unit of 2b·H2O·0.5 DMSO. The disor-
dered DMSO molecule in the asymmetric and the hydrogen atoms
are omitted for clarity. Selected bond lengths/A and bond angles/°
for molecule 1 [molecule 2]:
˚
The main product 2b could be separated from 2a by frac-
tional crystallization. Complex 2b was characterized by sin-
gle crystal X-ray diffraction (Figure 1). The asymmetric
unit contains two essentially similar molecules of 2b, two
water molecules and one disordered molecule of DMSO.
The water molecules are hydrogen bonded to the NH and
OH protons of the carbene ligand (Figure1). The bonding
parameters of 2b do not differ significantly from those re-
ported for other benzimidazol-2-ylidene complexes of type
C (Scheme1) with MLx equals W(CO)5 [14].
We reported previously than an equilibrium like the one
between 2a and 2b can be shifted to either side by a change
in the electronic properties of the metal atom [12]. Coordi-
nated hydroxyphenyl isocyanides which do not spontaneous
cyclize owing to deactivation of the isocyanide for nucleo-
W1-C1 2.183(13) [2.172(13)], O1-C1 1.352(14) [1.354(14)], O1-C7 1.383(14)
[1.383(14)], N1-C1 1.346(15) [1.347(15)], N1-C2 1.399(14)[1.372(14)], C2-C7
1.366(17), [1.366(17)], C3-O2 1.368(15) [1.374(17)], O2···O20 2.923(14)
[3.122(13)], N1···O20 2.765(15) [2.857(14)], W1-C1-O1 124.5(9) [127.8(10)],
W1-C1-N1 129.3(10) [127.6(11), O1-C1-N1 106.2(11) [104.6(11)].
philic attack by backbonding from the metal atom can al-
most always be converted into ylidenes by deprotonation of
the hydroxyl group. This enhances the nucleophilicity of the
oxygen atom. The N-alkylation after the cyclization pre-
vents the reopening of the ylidene and the backreaction to
the isocyanide.
Complexes of type 2b have two acidic protons and there-
fore two sites for an alkylation after cyclization. The acidity
for N-H and O-H protons is different and the values for 2-
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F. E. Hahn, P. Hein, T. Lügger
Scheme 3 Regioselective methylation of 2b.
Figure 2 ORTEP plots of 3 and 4. Starred atoms represent posi-
aminophenol (pKa1 ϭ 4.74, pKa2 ϭ 9.87 [21]) show, that
the O-H protons are more acidic. However, the H NMR
tions transformed by a crystallographically mirror plane. Hydrogen
1
˚
atoms are omitted for clarity. Selected bond lengths/A and bond
spectrum indicates, that the acidity of N-H and O-H pro-
tons is inverted for 2b (δOH ϭ 5.59, δNH ϭ 10.46) compared
to 2-aminophenol. This assumption was confirmed by
thechemical behaviour observed. Treatment of a mixture 2a/
2b Ϫ the mixture is reestablished even if crystalline 2b is
dissolved Ϫ with one equivalent of KOtBu and sub-
sequently with one equivalent of methyliodide leads regiose-
lectively to the N-methylated complex 3 (Scheme 3). The
formation of a phenoxymethylether is not observed. In ad-
dition, the equilibrium between isocyanide and carbene (2a/
2b) shifts completely to the side of the carbene complex 3.
The second deprotonation/alkylation sequence gives the O-
methylated complex 4. Complex 4 can also be obtained di-
rectly from the mixture 2a/2b and two equivalents base fol-
lowed by treatment with two equivalents of CH3I.
angles/° 3:
W-C1 2.192(7), O1-C1 1.377(8), O1-C7 1.379(8), N-C1 1.333(8), N-C2
1.407(7), N-C8 1.478(8), C2-C7 1.378(9), C3-O2 1.352(9), W-C1-O1 119.1(5),
W-C1-N 135.7(5), O1-C1-N 105.2(6), C1-O1-C7 109.9(5), C1-N-C2 112.5(5),
C1-N-C8 124.8(6), C2-N-C8 122.7(6); 4: W-C1 2.203(4), O1-C1 1.374(5),
O1-C7 1.377(5), N-C1 1.329(5), N-C2 1.405(5), N-C9 1.466(5), C2-C7
1.360(5), C3-O2 1.347(5), C8-O2 1.425(6), W-C1-O1 118.4(3), W-C1-N
135.1(3), O1-C1-N 106.5(3), C1-O1-C7 108.7(3), C1-N-C2 111.0(3), C1-N-
C9 124.9(4), C2-N-C9 124.1(3), C3-O2-C8 118.0(4).
The results of the X-ray structure determination of 3 and
4 are shown in Figure 2. As expected neither N- nor O-
alkylation leads to a significant change of bonding param-
eters obtained for both carbene complexes. Form the crystal
structure of 3 and 4 it becomes evident, that the intramol-
ecular carbene formation leads to an inversion of the acidity
of N-H and O-H protons compared to 2-aminophenol. The
higher acidity and hence better reactivity of the N-H group
in 2b can be explained by the incorporation of the nitrogen
atom in the aromatic five-membered ring. Upon depro-
tonation the delocalized π-system of the five-membered ring
allows a much better stabilization of the resulting negative
charge, than possible in a non-conjugated system like
R-NH2.
Scheme 4 Proposed mechanism for the formation of the heterobi-
metallic complex 5 from 2b.
Due to the facile deprotonation of 2b and its similarity
to 2-aminophenol regarding the arrangement of O- and N-
donors it appeared possible, to utilize the whole complex
2b as a bidentate chelate ligand. A suitable metal ion could
react with fully deprotonated 2b under formation of a het-
erobimetallic metal complex, that incorporates a five-mem-
bered chelate ring. Our experiments showed that even mo-
nodeprotonated 2a/2b reacts with one equivalent of
[Cp2MoCl2] giving a heterobimetallic complex. As shown
in Scheme 4 an intermediate is formed from monodepro-
tonated 2b by loss of one equivalent KCl. This intermediate
reacts very fast via an internal loss of HCl to form complex
5. We were not able to isolate the intermediate. Obviously
the reaction is driven by the high tendency towards chelate-
ring formation.
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Synthesis of Heterobimetallic Metal Derivatives
IR data were obtained with a Perkin Elmer 983 spectrometer. The
ligand 2,6-bis(trimethylsiloxy)phenyl isocyanide was
synthesized by a described procedure [15].
Preparation of the mixture 2,6-dihydroxyphenyl-
isocyanidepentacarbonyl tungsten 2a/4-hydroxybenzo-
xazol-2-ylidene)pentacarbonyl tungsten 2b
To a solution of [(THF)W(CO)5], obtained in an UV reactor [22]
from W(CO)6 (5 g, 14.2 mmol) in THF (150 mL) was added drop-
wise 2,6-bis(trimethylsiloxy)phenyl isocyanide (3.97 g, 14.2 mmol).
The reaction mixture was stirring overnight. Removal of the solvent
yielded crude complex 1, which was not further purified. The crude
1 was was taken up in methanol (50 mL) and an aliquot of KF
(20 mg) was added. After stirring at room temperature for 3 d the
mixture was brought to dryness and the brown residue was purified
by column chromatography (Al2O3, 3 % H2O, MeOH/Et2O, 1:1,
v:v) to give 3.8 g (58 %) of a mixture of 2a/2b (1:3).
Figure 3 ORTEP plot of 5 in 5·CHCl3. Hydrogen atoms are omit-
ted for clarity. Selected bond lengths/A and bond angles/°:
W-C1 2.217(5), Mo-O2 2.136(4), Mo-N 2.179(4), O1-C1 1.413(6), O1-C2
1.374(6), N-C1 1.323(6), N-C3 1.395(6), C3-C2 1.344(7), O2-C4 1.327(6), W-
C1-O1 115.1(3), W-C1-N 137.2(3), O1-C1-N 107.6(4), C1-O1-C2 108.3(4),
Mo-N-C1 145.5(3), Mo-N-C3 106.8(3), C1-N-C3 107.7(4), C4-O2-Mo
113.9(3), O2-Mo-N 79.00(14).
˚
Selected data for crude 1: 1H NMR (250 MHz, CDCl3): δ ϭ 7.08 (t, 1 H,
Ar-H); 6.49 (d, 2 H, Ar-H); 0.32 (s, 18 H, SiCH3). IR (CCl4): ν(NC) ϭ
2145 cmϪ1
.
Data for the mixture 2a/2b: 1H NMR (250 MHz, CD2Cl2): δ ϭ 10.46 (s, 1
H, N-H of 2b); 7.16 (d, 2 H, Ar-H of 2b); 7.05 (t, 1 H, Ar-H of 2a); 6.74 (t,
1 H, Ar-H of 2b); 6.48 (d, 2 H, Ar-H of 2a), 5.59 (s, 3 H, OH of 2a/2b). 13
C
NMR (62.90 MHz, CD2Cl2): δ ϭ 212.4 (carbene-C of 2b); 201.8 (trans-CO
of 2b); 197.3 (d, 1J(W,C) ϭ 126 Hz, cis-CO of 2b); 196.9 (trans-CO of 2a),
194.4 (d, 1J(W,C) ϭ 126 Hz, cis-CO of 2a); 154.7, 130.6, 108.6 (Ar-C of 2a);
153.1, 141.3, 126.4, 119.6, 111.9, 104.2 (Ar-C of 2b); both resonances Ar-C-
NϵC for 2a could not be observed. IR (KBr): ν(OH) 3522 cmϪ1 2a/2b,
ν(NH) 3384 cmϪ1 2b, ν(NC) 2131 cmϪ1 2a. MS (70 eV): m/z ϭ 459 (Mϩ,
9.9 %).
Complex 5 was obtained after column chromatography
and recrystallization from chloroform as ruby-red prisms
5·CHCl3. The crystal structure analysis of 5 (Figure 3) re-
vealed a (CO)5W(carbene) moiety, which is virtually un-
changed in comparison to those found in 3 and 4. However,
the chelate ring formation leads to a severe distortion of the
angles around the nitrogen atom. The carbene complexes 3
and 4 exhibit C-N-C angles within the five-membered ring
of 112.5(5)° (3) and 111.0(3)° (4) and C-N-CMe angles of
122.7(6)° and 124.8(6)° for 3 and 124.1(3)° and 124.9(4)°
for 4. The inner-ring C-N-C angle in complex 5 measures
only 107.7(4)°. The angle C1-N-Mo is enlarged to 145.5(3)°
while the angle C3-N-Mo shrinked to 106.8(3)°. This dis-
tortion is essential to accomodate the molybdenum atom
in a chelating fashion. The Mo-O2 and Mo-N distances
(2.136(4) A and 2.179(4) A) are similar in length. The angle
distortion explains, why only metal ions with large ionic
radii can be coordinated in a chelating fashion by 2b. Coor-
dination of a metal ion with a smaller ionic radius as mol-
ybdenum would lead to even shorter M-O and M-N dis-
tances and to an even larger, hence structurally more disad-
vantageous C1-N-Mo angle. In agreement with this obser-
vation we found that 2b does not form a chelate complex
with [Cp2TiCl2].
Preparation of (N-methyl-4-hydroxybenzoxazol-2-
ylidene)pentacarbonyl tungsten (3)
A sample of mixture 2a/2b (918 mg, 2.0 mmol) was dissolved in
DMF (25 mL) at Ϫ40 °C. To this was added KOtBU (112 mg,
1.0 mmol) and the reaction mixture was allowed to warm to room
temperature. After 3 h stirring at ambient temperature the mixture
was treated with MeI (142 mg, 1.0 mmol) and stirred for another
3 h. The DMF was removed in vacuo. Column chromatography
(Al2O3 3 % H2O, CHCl2/n-hexane, 1:2, v:v) yielded 3 (260 mg,
37 %). Recrystallization from CHCl3 gave 3 as colorless needles.
1H NMR (400 MHz, D6-acetone): δ ϭ 7.25 (t, 1 H, Ar-H); 7.19 (d, 1 H, Ar-
H); 6.92 (d, 1 H, Ar-H); 4.32 (s, 3 H, NCH3); the OH resonance was not
observed. IR (KBr): ν(OH) 3573 cmϪ1. MS (70 eV): m/z ϭ 473 (Mϩ, 58 %),
361 (Mϩ-4CO, 100 %).
˚
˚
Preparation of (N-methyl-4-methoxybenzoxazol-2-
ylidene)pentacarbonyl tungsten (4)
The double methylation of 2a/2b to yield 4 was carried out as de-
scribed for the preparation of 3 from 2a/2b using 2 equivalents
(4 mmol) of base and MeI. Yield 584 mg (60 %).
1H NMR (250 MHz, CDCl3): δ ϭ 7.27 (t, 1 H, Ar-H); 7.17 (d, 1 H, Ar-H);
6.80 (d, 1 H, Ar-H); 4.23 (s, 3 H, NCH3); 3.99 (s, 3 H, OCH3). 13C NMR
(62.90 MHz, D6-acetone): δ ϭ 212.7 (carbene-C), 202.1 (trans-CO), 197.9
(cis-CO), 155.2, 148.0, 127.6, 122.2, 108.4, 104.4 (Ar-C), 56.9 (OCH3), 38.7
(NCH3). MS (70 eV): m/z ϭ 487 (Mϩ, 64 %), 375 (Mϩ-4CO, 100 %).
Experimental
All experiments were carried out in an argon atmosphere using
standard Schlenk techniques. Solvents were dried by routine pro-
cedures and distilled prior to use. Correct elemental analyses were
obtained for all reported compounds using a Vario EL elemental
analyzer. NMR spectra were recorded at room temperature on
Bruker AM 250 and Joel λ 400 instruments. Mass spectra were
measured with Finnigan MAT 112 and MAT 711 spectrometers.
Preparation of (µ2-N,O-molybdocene-4-
oxobenzoxazol-2-ylidene)pentacarbonyl tungsten (5)
A sample of mixture 2a/2b (918 mg, 2.0 mmol) was dissolved in
DMF (20 mL) and KOtBu (225 mg, 2.0 mmol) were added at
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F. E. Hahn, P. Hein, T. Lügger
Table 1 Selected Crystal and Data Collection Details for 2b·H2O·0.5 DMSO, 3, 4 and 5·CHCl3.
2b·H2O·0.5 DMSO
3
4
5·CHCl3
crystal size, mm
formula
0.42 x 0.38 x 0.15
0.45 x 0.35 x 0.25
C13H7NO7W
473.05
9.1310(2)
20.536(5)
7.650(2)
90.0
90.0
90.0
1434.6(5)
2.190
Pbcm
0.62 x 0.32 x 0.28
C14H9NO7W
487.07
6.886(2)
14.150(3)
15.909(5)
90.0
100.0(2)
90.0
1526.5(7)
2.119
0.42 x 0.30 x 0.28
C23H14Cl3NMoO7W
802.49
10.128(2)
10.831(3)
11.889(5)
82.86(3)
86.28(2)
75.65(2)
1252.9(7)
2.127
¯
P1
C14H13NO8S0.5
516.10
W
fw, amu
˚
a, A
7.222(5)
˚
b, A
15.386(5)
16.190(5)
106.50(3)
91.72(4)
˚
c, A
α, deg
β, deg
γ,deg
101.23(4)
1685.0(14)
2.034
3
˚
V, A
dcalc, g cmϪ1
space group
¯
P1
P 21/n
Z
4
4
4
2
µ, mmϪ1
6.960
4377
2762
4.14, wR1 ϭ 7.43
11.34, wR2 ϭ 8.98
1.007
8.086
1017
881
2.04, wR1 ϭ 4.90
2.69, wR2 ϭ 5.11
1.023
7.603
3478
2850
2.80, wR1 ϭ 6.06
4.41, wR2 ϭ 6.49
1.077
5.542
3267
3110
2.27, wR1 ϭ 5.89
2.50, wR2 ϭ 5.99
1.138
unique data
observed data {I > 2σ(I)}
R1 (observed data), %
R2 (all data), %
GOF (all data)
no. of variables
445
124
210
332
3
˚
res. electr. dens., e/A
0.751 / Ϫ0.770
0.419 / Ϫ0.448
0.650 / Ϫ0.891
0.748 / Ϫ0.619
Ϫ40 °C. The solution was stirred for 3 h while warming to room
temperature. A solution of molybdocenedichloride (2.2 mmol in
10 mL of DMF) was added dropwise. The reaction mixture was
stirred for 16 h at room temperature and then brought to dryness.
Column chromatography (SiO2, MeOH) yielded 5 (600 mg, 44 %)
as a brown solid. Recrystallization from chloroform gave ruby-red
crystals of 5·CHCl3.
plate Directed Chemical Synthesis” in Münster and the Fonds der
Chemischen Industrie is gratefully acknowledged.
References
[1] a) K. H. Dötz, H. Fischer, P. Hofmann, F. R. Kreissl, U. Schu-
bert, K. Weiss, Transition Metal Carbene Complexes, Verlag
Chemie, Weinheim, 1983; b) B. Crociani, in: Reactions of Co-
ordinated Ligands, P. S. Braterman (ed), Plenum, New York,
1986, Vol. 1, p. 553.
1H NMR (250 MHz, CDCl3): δ ϭ6.86 (t, 1 H, Ar-H); 6.59 (d, 1 H, Ar-H);
6.26(d, 1 H, Ar-H); 5.64 (s, 10 H, C5H5). MS (70 eV): m/z ϭ 683 (Mϩ,
3.2 %).
[2] Reviews on the coordination chemistry of isocyanides: a) E.
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Crystal structure determinations
Suitable crystals were selected and mounted on a CAD-4 dif-
fractometer equipped with a sealed Mo X-ray tube (λ ϭ 0.71073 A)
˚
and a scintillation detector. Diffraction was measured at room tem-
perature in a 2 Θ range from 2 to 55°. An empirical absorption
correction (ψ-scans) was applied on all data sets. The structures
were solved and refined by standard Patterson- and Fourier-tech-
niques [23]. All non hydrogen atoms were refined with anisotropic
thermal parameters, hydrogen atoms reside on calculated positions.
2b crystallizes with two independent molecules, 2 water molecules
and one disordered DMSO molecule in the asymmetric unit. Crys-
tals of 5 contain one molecule of CHCl3 per formula unit. Selected
crystal, data collection and refinement details are summarized in
Table 1. ORTEP [24] was used for the generation of molecular
plots. Thermal ellipsoids represent a 50 % probability level.
[8] U. Kernbach, W. P. Fehlhammer, Inorg. Chim. Acta 1995,
235, 299.
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Ber. 1985, 118, 2220.
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Soc. 1985, 107, 2171.
[12] For a review on the reactivity of β-functional phenyl isocyan-
ides see: M. Tamm, F. E. Hahn, Coord. Chem. Rev. 1999,
182, 175.
Supplementary Material. Crystallographic data (excluding structure
factors) for the structures reported in this paper have been deposited
with the Cambridge Crystallographic Data Centre as supplemental
publication CCDC-205511 for 2b, CCDC-205512 for 3, CCDC-
205513 for 4, and CCDC-205514 for 5. Copies of the data can be ob-
tained free of charge on application to the Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (Fax: int.codeϩ(1223)336-033;
e-mail for inquiry: filserv@ccdc.cam.ac.uk.
Acknowledgment. Financial support from the Deutsche For-
schungsgemeinschaft, the International Graduate College “Tem-
[13] M. Tamm, T. Lügger, F. E. Hahn, Organometallics 1996, 15,
1251.
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zaac.wiley-vch.de
Z. Anorg. Allg. Chem. 2003, 629, 1316Ϫ1321

Synthesis of Heterobimetallic Metal Derivatives
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C11; b) F. E. Hahn, M. Tamm, Organometallics 1995, 14,
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Organomet. Chem. 1997, 541, 51.
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Langenhahn, D. Le Van, M. Tamm, L. Wittenbecher, T.
Lügger, Heteroatom Chem. 2002, 13, 540.
[21] P. Dasgupta, R. B. Jordan, Inorg. Chem. 1985, 24, 2717.
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D. Lentz, Chem. Ber. 1984, 117, 415.
[23] G. M. Sheldrick, 1997, SHELXS-97, SHELXL-97, Programs
for Solution and Refinement of Crystal Structures, University
of Göttingen, Germany.
[24] L. Zsolnai, H. Pritzkow, 1995, ZORTEP, ORTEP Program for
Personalcomputer, University of Heidelberg, Germany.
[19] a) F. E. Hahn, M. Tamm, J. Chem. Soc. Chem. Commun. 1993,
842; b) F. E. Hahn, M. Tamm, J. Chem. Soc. Chem. Commun.
1995, 569.
Z. Anorg. Allg. Chem. 2003, 629, 1316Ϫ1321
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