Synthesis and Characterization of Aza-Trimetalla Tetrahedranes

Article abstract of DOI:10.1515/znb-1996-1116

The sulfimide complex Fe₂(CO)₆(μ-SNH) (1) reacts with Co₂(CO)₈ to form a 1:1 mixture of the known clusters FeCo₂(CO)₉(μ₃-S) (2) and FeCo₂(CO)₉(μ₃-NH) (3). The aza-tetrahedrane 3 may be used as a precursor for the synthesis of the new aza-trimetalla tetrahedranes Fe₂Co(CO)₉(μ-H)(μ₃-NH) (5), CpMoFeCo(CO)₈(μ₃-NH) (6). CpNiFeCo(CO)₆(μ₃-NH) (7) and (CpNi)₂Fe(CO)₃(μ₃-NH) (8) which were obtained from exchange reactions of 3 with Na₂[Fe(CO)₄], Na[CpMo(CO)₃] and [CpNi(CO)]₂. However, the reactions of 3 with Na₂[Fe(CO)₄] and Fe₃(CO)₁₂ gave Fe₃(CO)₉(μ-H)₂(μ₃-NH) (9) only as a minor product in addition to large amounts of Fe₃(CO)₉(μ-H)₂(μ₃-S) (10). The ¹H NMR spectra of 3 and 5 -9 show a broadened triplet for the NH proton between δ(¹H) 8.21 and 9.53. Chemical shifts δ(¹⁴N) were determined most efficiently by heteronuclear ¹H{¹⁴N} double resonance experiments. The δ(¹⁴N) values for aza-trimetalla tetrahedranes (-180 to -202) indicate delocalized bonding between the μ₃-bridging nitrogen atom and the metal triangle.

Full text of DOI:10.1515/znb-1996-1116

Synthesis and Characterization of Aza-Trimetalla Tetrahedranes
Max Herberhold*, Uwe Bertholdt, Bernd W rackmeyer
Laboratorium für Anorganische Chemie der Universität, Postfach 101251, D-95440 Bayreuth
Z. Naturforsch. 51 b, 1621-1626 (1996); received June 14, 1996
Cluster, NMR Spectra
The sulfimide complex Fe2(CO)6(^-SNH) (1) reacts with Co2(CO)s to form a 1:1 mix-
ture of the known clusters FeCo2(CO)9(/x3-S) (2) and FeCo2(CO)9(/U3-NH) (3). The aza-
tetrahedrane 3 may be used as a precursor for the synthesis of the new aza-trimetalla tetra-
hedranes Fe2Co(CO)9(Ai-H)(jX3-NH) (5), CpMoFeCo(CO)8(/i3-NH) (6), CpNiFeCo(CO)6(/i3-
NH) (7) and (CpNi)2Fe(CO)3(/.<3-NH) (8) which were obtained from exchange reactions of
3 with Na2[Fe(CO)4], Na[CpMo(CO)3] and [CpNi(CO)]2. However, the reactions of 3 with
Na2[Fe(CO)4] and Fe3(CO)i2 gave Fe.^COM/u-HM^-NH) (9) only as a minor product in
addition to large amounts of Fe3(CO)9(/v-H)2(/t3-S) (10). The 'H NMR spectra of 3 and 5 -
9 show a broadened triplet for the NH proton between <5('H) 8.21 and 9.53. Chemical shifts
<5(14N) were determined most efficiently by heteronuclear 'H {14N} double resonance experi-
ments. The <5(I4N) values for aza-trimetalla tetrahedranes (-180 to -202) indicate delocalized
bonding between the /^-bridging nitrogen atom and the metal triangle.
Introduction
Results and Discussion
Synthesis
Aza-trimetalla [1, 2] as well as trimetalla-thia
tetrahedranes [3,4] are known since the mid-sixties.
There are numerous methods of preparation which,
however, often lead only to certain trimetalla tetra-
hedrane species, and are not generally applicable.
In contrast, trimetalla-thia tetrahedranes may be ob-
tained systematically by metal exchange reactions
[5], In continuing our investigations of the reactiv-
ity o fF e2(CO)6(^-SN H) (1) [6], we report on a new
route to FeCo2(CO)9(/i3-NH) (3) and the syntheses
of similar aza-trimetalla tetrahedranes.
The cluster Fe2(CO)60»-SNH) (1) reacts with
two equivalents of Co2(CO)g within 24 h in boil-
ing toluene to form a mixture of the trimet-
alla tetrahedranes FeCo2(CO)9(/i3-S) (2) [3] and
FeCo2(CO)9(^ 3-NH) (3) [1] (Scheme 1). For-
mally the reaction may be explained by the cleav-
age of
1 into the fragments Fe(CO)3(S) and
Fe(CO)3(NH), respectively, and subsequent trap-
ping with Co2(CO)g. The separation of the two clus-
ters was achieved by column chromatography but,
unfortunately, several runs with small amounts of
the mixture are necessary because the elution rates
are very similar. Compound 2 may be obtained in
better yield by other methods [3]. In the case of
the aza-trimetalla tetrahedrane 3, this new route af-
forded the highest yield (48%) compared with liter-
ature procedures [1].
H
The analogous reaction of
1
with other
dimetallic precursors such as [CpNi(CO)]2,
[Cp*Cr(CO)2]2 and [CpM o(CO)3]2 failed to give
aza-trimetalla tetrahedranes. From the reaction of
Fe2(CO)6(^-SNH) (1) with [CpNi(CO)]2, only
(CpNi)2Fe(CO)3(/t3-S) (4) [7] (see Experimental)
and [CpFe(CO)2]2 could be isolated (Scheme 2),
wheras no reaction took place between 1 (decom-
position) and the group 6 dimetallic clusters (recov-
ered unchanged).
1
4
Scheme 2
* Reprint requests to Prof. Dr. M. Herberhold.
0939-5075/96/1 100-1621 $ 06.00
©
1996 Verlag der Zeitschrift für Naturforschung. All rights reserved.
K
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1622
M. Herberhold et al. ■Synthesis and Characterization of Aza-Trimetalla Tetrahedranes
Since the systematic preparation of tetrahedral
The aza-trimetalla tetrahedranes 6 and 7 are chi-
ral; no attempts were made to separate the enan-
tiomers. The aza-triferra tetrahedrane Fe3(CO)9(/i-
H)2(/x3-NH) (9) was identified in the presence of a
large exess (1:20) of Fe3(CO)9(^-H )2(^-S) (10) [3b]
as a minor product of the reaction of Fe2(CO)6(/i-
SNH) (1) with Na2[Fe(CO)4]/Fe3(CO)i2 (Scheme
4). This reaction was originally planned to induce
oxidative addition of the tetracarbonylferrate to the
S-N bond of 1. Attempts to separate 9 and 10 by
column chromatography on silica failed because of
decomposition. The molar ratio of 9 and 10(1:20),
as well as the exclusive formation of 4 during the re-
action of Fe2(CO)6(^-SNH) (1) with [CpNi(CO)]2
suggest that nitrogen-metal intermediates are less
stable then the sulfur-metal fragments. This, in turn,
may be the reason for the less effective formation
of aza-trimetalla tetrahedranes as compared to their
sulfur analogues.
aza-trimetalla clusters starting from Fe2(CO)6(//-
SNH) (1) was unsuccessful, we tried to obtain com-
plexes of this type starting with FeCo2(CO)9(/^3-
NH) (3) via metal fragment substitution. This
method had proven to be effective in the synthe-
ses of trimetalla-thia tetrahedranes [5].
The reaction of 3 with two equivalents of
tetracarbonylferrate in boiling THF gave, after
acidic hydrolysis, Fe2Co(CO)9(/i-H )(/j3-NH) (5)
(Scheme 3). While the first exchange of a Co(CO)3
fragment to give 5 takes place readily, the forma-
tion of Fe3(CO)9(^-H )2(/i3-NH) (9) could not be
observerd.
(OC)3Fe
■M oCp(CO)2
BuLi, [CpM o(CO)i]’, H+
'-C o(C O )4\ -Li+, -C4H,()
N
N — - S
+ 2 [Fe(CO)4l2-
+2/3 Fe,(CO),
N
S
/
r./^ü^tFe(CO), +
(OC)3Fec^\Fe(CO);
CTAI
(OChFe -------------FelCOh + 4 H *
FclCO l
>Fe(CO)}
[CpNi(CO)]2
-"Co(CO)4"
Scheme 4
NMR spectroscopic results
The ‘H, 13C, 14N and 59Co NMR data are listed
in Table I. The 'H(NH) resonances are broadened
1:1:1 triplets except for Fe2Co(CO)9(/i-H )(/i3-NH)
(5) where the triplet is well resolved (Fig. 1). This
indicates reduced quadrupolar relaxation rates of the
l4N nuclei in these clusters. Generally the triplets
cover a range of about 150 Hz. Therefore and be-
cause of the inherent low solubility of the aza-
trimetalla tetrahedranes, the recording of 'H NMR
spectra requires prolonged accumulation times. The
1H NMR signals of the hydridic and the NH protons
in 5 reveal a small unresolved coupling, detected by
the slight decrease of the line width of the hydridic
'H resonance in a homonuclear decoupling exper-
iment at -20°C. Satellites due to '/(^ F e .'H ) could
not be resolved at the bottom of the 'H (^-H ) reso-
nance signal.
A
n,cp
/ V
(O C),Fe C T \ J
Cp
NiCp
'» jF e C T 'A I
+
Scheme 3
Similarly, only one of the Co(CO )3 fragments
of 3 could be replaced in the reaction with
[CpMo(CO)3]~ to form CpM oFeCo(CO)8(^ 3-NH)
(6) (Scheme 3). The yield of 6 was markedly in-
creased if the starting tetrahedrane FeCo2(CO)9(//-3-
NH) (3) was deprotonated prior to the reaction.
Again, there was no evidence for exchange of the
second Co(CO)3 unit of 3.
Using the dimeric nickel complex [CpNi(CO)]2,
which is powerful in exchanging Co(CO)3
groups in FeCo2(CO)9(/L/3-S) (2) [5], two
Table II contains literature data of both 6('H )
and '7 (14N ,'H ) of ^ 3-NH groups. The <5>(NH) values
cover a range of at least 6.5 ppm. The changes in the
chemical shift of the //3-NH proton are apparently
Co(CO)3 fragments of
3 were replaced step-
wise leading to CpNiFeCo(CO)ö(^3-NH) (7)
and (CpNi)2Fe(CO)3(//3-NH) (8), respectively
(Scheme 3).
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M. Herberhold et al. • Synthesis and Characterization of Aza-Trimetalla Tetrahedranes
Table I. 1H, l3C, l4N and 59Co NMR data 6[J] of the aza-trimetalla tetrahedranes 3 and 5 to 9.
1623
Aza-trimetalla tetrahedrane
'H NMR
l4N NMR|al
59Co NMR|b|
13C NMR
Co2Fe(CO)9(^3-NH) (3)
CoFe2(CO)9(ju-H)0*3-NH) (5)
9.28 [58.1 ]|cl
8.78 [57.6] (NH);
-20.11 (M3H)
8.87 [50]
202.4 (br.)
206.7
-180
-202
-2068(8200)
-2322(6600)
-194
-2454(4300)
94.1 (Cp);
200.9; 209.8;
230.3; 232.7
(CO)
CpMoCoFe(CO)8(At3-NH) (6 )
9.53 [52]
9.28 [50]
88.8 (Cp);
211.7 (CO)
87.1 (Cp);
212.8 (CO)
206.4
-184
-194
-2062(5000)
CpNiCoFe(CO)6(A*3-NH) (7)
(CpNi)2Fe(CO)3(//3-NH) (8)
Fe3(CO)9(^-H)2(^3-NH) (9)
"
“
8.21 [51] (NH);
-23.33 (Fe3H2)
not
measured
Ia]: <5(I4N) from !H{I4N} experiments ± lppm; [bj: Widths at half height (hi/2) in Hz are given in parentheses; [c]:
7[I4N'H] ±1.5 Hz are given in square brackets.
Table II. !H NMR data of aza-trimetalla
tetrahedranes.
Aza-trimetalla tetrahedrane
<ü(NH) 1y [l4N1H] [Hz]
Fe,(CO)9(^-C O )(^-N H ) [2a]
FeCoo(CO)9(^-N H ) [2b]
FeRu^(COM ^-CO)(^-NH) [2b]
9.4
10.6[a]
6.5
57
[a]: Our value: 9.28ppm.
54
43
FeRu2(CO)8[P(OM eh](^-CO)(^-NH) [2b] 6.7
Ru3(CO)9(/i3-CO)(^i-NH) [2b]
RuiH2(CO)9(//tN H ) [2e]
Os3H2(CO)9(/X3-NH) [2d]
Os3H4(CO)8(a/3-NH) [2d]
5.7
54
55.2
6.36
4.06
4.42
W3(0 ,Pr)6(^2-0 lPr)3(^3-0 'Pr)(^3-NH) [2g] 9.87
(b)
(a)
lower frequencies if heavy metals form the tri-
angle. The only exception so far is the W 3(/i3-
NH) cluster which, however, possesses a com-
pletely different ligand sphere. The <5(NH) val-
ues of the tetrahedranes 5 to 9 are found in the
area typical of Fe3(CO)9(^ 3-C O )(^3-NH) [2a] and
Co2Fe(CO)9(^ 3-NH) [2b]. The single molybdenum
atom in the framework of 6 obviously has a negli-
gible influence.
'NiCp
___
( c o )3
A
n
(OC)3Fe<^:\c|o
(OC)3F e < ^ \ |
■A-
• Co(CO)3
xI^Fe(CO)3
(V
(5)
The magnitude of ’/( ^ N ,1H) of the tetrahedranes
5 to 9 as well as the data cited in Table II fall in the
range which has also been found for ammonium
ions [8].
10. 0
The 6( 14N) data could be obtained most effi-
ciently by selective heteronuclear double resonance
'H { I4N} experiments; 'H-detected (inverse) 2D
1H /15N nuclear shift correlations (Fig. 2) require
a lot of spectrometer time, and a single experiment
may not be reliable if the <5(15N) value is unknown.
Suprisingly, the <5(N) values of aza-trimetalla tetra-
8('H)
Fig. 1. 250.13 MHz 1H NMR spectra of the aza-trimetalla
tetrahedranes 5 (a) and 7 (b).
dominated by the composition of the metal trian-
gle. Usually the /^/3-NH resonances are shifted to
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1624
M. Herberhold et al. ■Synthesis and Characterization of Aza-Trimetalla Tetrahedranes
-182
Mj-N-a-bond
Fig. 3. Qualitative description of N-M3 a and n bonding
- -180
in aza-trimetalla tetrahedranes.
-
-178
CoiFe(COh(nj,-NH) (3)
■
s 15N
A solution of 392 mg (1.2 mmol) of Fe2(CO)ö(^-SNH)
(1) and 821 mg (2.4 mmol) of Co2 (CO)s in 150 ml of
toluene was heated for 2 d at 100°C. A small amount of
metal was deposited from the brown to black solution as a
metallic mirror. Silica was added to the reaction mixture;
the solvent was then removed in vacuo and the material
thereby adsorbed on silica. Separation of the products was
achieved in several portions by column chromatography
(2 x 40 cm, silica/pentane) each time with about a fifth
part of the mixture.
100
50
0
-50
-100
1H IHzl
Fig. 2. 500.13 MHz 'H-detected (inverse) 2D 'H /I5N
(HMQC) [11]) shift correlation of FeCo2(CO)9(^3-NH)
(3) (saturated in CöDö, 24 hours spectrometer time).
hedranes were found between 6 = -180 and -202,
shifted to higher frequencies when compared with
Fe2(CO)6(/i-SNH) (1) [6b]. This nitrogen nuclear
deshielding indicates strong delocalization of the
bonding between NH and the metal triangle. Ac-
cording to extended Hiickel MO calculations, the
frontier orbitals of M 3(CO)9 fragments always con-
sist of contributions from more than one metal [9].
The bonding orbitals of the a and ir type in M 3NH
tetrahedranes are shown qualitatively in Fig. 3, il-
lustrating this delocalization. The 13C(CH) nucleus
in Co3(CO)9(m3-CH), isoelectronic with 3, is also
deshielded (<513C = 263 [10]), most likely for the
same reason.
Zone 1: Co2Fe(CO)9 (jU3-S) (2) [3], yield 48%.
Zone 2: Co2Fe(CO)9(^3-NH) (3) [1]: brown to black crys-
tals, yield 48%. - IR (Csl): v(NH) 3357w, IR (hexane):
//(CO) 2101 vw, 2059s, 2045m, 2036m, 1981vw, 1973vw.
EI-MS: 441 (30%, M+), 189(100%, M+-9CO), 130(65%,
CoFeNH+).
(CpNi)2Fe(COh(fi -S) (4)
3
A solution of 392 mg (1.2 mmol) of Fe2(CO)ö(|U-SNH)
(1) and 725 mg (2.4 mmol) of [CpNi(CO)]2 in 150 ml of
toluene was heated for 2 d at 100°C. The solution turned
black, and the deposition of a metal mirror was observed.
The solvent was removed in vacuo, and silica was added to
transform the oily residue into a solid material. Separation
of the products was achieved by column chromatography
(2 x 40 cm, silica/pentane) in small portions.
Experimental
All starting materials were obtained from commer-
cial sources. The synthesis of the starting tetrahedrane
complex, Fe2(CO)6(/u-SNH) (1) [6a], has been described
earlier. The reactions were carried out under argon using
standard Schlenk techniques. Bruker AM 500 and Bruker
ARX 250 spectrometers were used to record the NMR
spectra. Chemical shifts <5'H, <5I3C and <5I4N are given
with respect to Me.;Si [6'H(C6DsH) = 7.15, ^ ’’QCftDö)
= 128.0] and external neat MeNCb.
Zone 1: Cp2Ni2Fe(COb(/i3-S) (4) [7], brown to black
crystals, yield 18%. - IR (hexane): //(CO) 2028s, 1962m,
1954m. EI-MS: 418 (10%, M+), 334 (28%, M+- 3CO),
269 (25%, CpNi2FeS+), 186 (100%, Cp2Fe+). 'H NMR
(C6D6): 6 = 4.91; 13C NMR (C6D6): 6 = 87.7(Cp),
212.9(CO).
Zone 2: [CpFe(CO)2]2: red crystals, yield 30%.
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M. Herberhold et al. • Synthesis and Characterization of Aza-Trimetalla Tetrahedranes
1625
CoFe (COk(p-H)(p^-NH) (5)
2
ml of toluene was heated for 3 d at 90°C (partial metal
separation). Silica was added to the reaction mixture, the
solvent then removed in vacuo and the product mixture
thereby adsorbed on silica. Separation of the products
was achieved by column chromatography (2 x 40 cm,
silica/pentane).
Zone 1: Cp2Ni2Fe(CO)3(^3-NH) (7), brown to black crys-
tals, yield 15%. - IR(CsI): t^(NH) 3383w, IR (hexane):
u{CO) 2073m, 2029s, 2018m, 2010m, 1969w, 1965m. EI-
MS: 401 (25%, M+), 317 (100%, M+-3CO), 251 (20%,
CpNi2FeN+), 186 (30%,Ni2FeN+),
A solution of 176 mg (0.4 mmol) of Co2Fe(CO)9(/i3-
NH) (3) and 171 mg (0.8 mmol) of Na2[Fe(CO)4] in 40
ml of THF was heated for 4 d at 65°C (partial metal
Separation). The solvent was removed in vacuo, and the
residue treated with about 50 ml of degassed water and 50
ml of hexane. The solvent mixture was acidified to pH =
1 by HC1 and the product transferred to the hexane layer
by shaking. Compound 5 was isolated after separation of
the layers, drying (Na2SC>4) and removing the solvent.
CoFe2H(CO)9(/i3-NH) (5), brown to black crystals, yield
37%. - IR(CsI): i/(NH) 3397w, IR (hexane): u(CO)
2101 vw, 2062m, 2055s, 2047m, 2036w, 2025m, 1980w.
EI-MS: 339 (1%, M+), 187 (15%, M+-9CO), 130 (20%,
FeCoNH+).
Zone 2: CpNiCoFe(CO)6(£<3-NH) (8), brown to black
crystals, yield 48%. IR(CsI): t/(NH) 3376w, IR (hexane):
j/(CO) 2031s, 1970s. EI-MS: 421 (15%, M+), 253 (100%,
M+-6CO), 187(15%, CoNiFeN+).
Mixture of Fey(COh(p-H)
H)2(P 3 -s )m
2
(ps-NH) (9) and Fe^COhip-
CpMoCoFe(CO)%(pi-NH)
(6)
A
solution containing 132 mg (0.3 mmol) of
A solution of 147 mg (0.45 mmol) of Fe2(CO)6(SNH)
(1), 193 mg (0.9 mmol) of Na2[Fe(CO)4] and 151 mg
(0.3 mmol) of Fe3(CO)i2 in 40 ml of THF was heated
for 2 d at 65°C (partial metal separation). 0.14 ml (1.8
mmol) of CF3COOH were added and the solvent was
removed in vacuo. The residue was extracted with hexane
(3 x 30 ml). Chromatographic workup failed because of
decomposition of the products on silica.
Co2Fe(CO)9(^3-NH) (3), 0.19 ml of a 1.6 molar so-
lution of BuLi in hexane and 160 mg (0.6 mmol) of
Na[CpMo(CO)3] in 100 ml of toluene was heated for
3 d at 90°C (partial metal separation). 42 p\ (0.9 mmol)
of CF3COOH were added, the solvent removed in vacuo,
and the product purified by column chromatography (2 x
40 cm, silica/ pentane).
CpMoCoFe(CO)n(//3-NH) (6), brown to black crystals,
yield 34%. - IR(CsI): //(NH) 3355w, IR (hexane): u(CO)
2071m, 2025s, 2009s, 1971m, 1963w, 1854w. EI-MS:
517 (20%, M+), 291 (100%, M+-8CO), 235 (30%,
CpMoCoNH+).
Acknowledgements
(CpNi)iFe(CO)s(p^-NH) (1) and CpNiCoFe(CO)t(pi-
NH) (&)
Support of this work by the Deutsche Forschungsge-
meinschaft and the Fonds der Chemischen Industrie is
gratefully acknowledged.
A solution of 220 mg (0.5 mmol) of Co2Fe(CO)9(//3-
NH) (3) and 302 mg (1.0 mmol) of [CpNi(CO)]2 in 100
d) J. A. Smieja, W. L. Gladfelter, J. Organomet.
Chem. 297, 349(1985);
[1] D. E. Fjare, D. G. Keyes, W. L. Gladfelter, J.
Organomet. Chem. 250, 383 (1983).
e) J. A. Smieja, R. E. Stevens, D. E. Fjare, W. L.
Gladfelter, Inorg. Chem. 24, 3206 (1985);
f) M. L. Blohm, D. E. Fjare, W. L. Gladfelter, J. Am.
Chem. Soc. 108, 2301(1986);
[2] S. A. Khattab, L. Marko, G. Bor, B. Marko, J.
Organomet. Chem. 1, 373 (1964).
[3] a) D. E. Fjare, W. L. Gladfelter, Inorg. Chem. 20,
3533 (1981);
g) M. H. Chisholm, D. M. Hoffman, J. C. Huffman,
Inorg. Chem. 24, 796 (1985);
b) M. L. Blohm, D. E. Fjare, W. L. Gladfelter, J. Am.
Chem. Soc. 108, 2301 (1986);
h) A. Gourdon, Y. Jeannin, Organometallics 5, 2406
(1986).
c) P. Legzdins, G. R. Nurse, S. R. Rettig, J. Am.
Chem. Soc. 105, 3727 (1983);
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M. Herberhold et al. • Synthesis and Characterization of Aza-Trimetalla Tetrahedranes
1626
[4] a) G. Natile, G. Bor, J. Organomet. Chem. 35, 185
(1972);
b) B. Wrackmeyer, E. Kupce, B. Distier, K. Dirn-
berger, M. Herberhold, Z. Naturforsch. 46b, 1679
(1991);
c) M. Herberhold, U. Bertholdt, W. Milius, Z. Natur-
forsch. 50b, 1252 (1995);
d) M. Herberhold, U. Bertholdt, W. Milius, A.
Glöckle, B. Wrackmeyer, J. Chem. Soc. Chem.
Commun. 1219(1996);
b) L. Marko, J. Takacs, S. Papp, B. Marko-
Monostory, Inorg. Chim. Acta 45, LI 89 (1980);
c) A. J. Deeming, R. Ettorre, B. F. G. Johnson, J.
Lewis, J. Chem. Soc. (A) 1797 (1971);
d) E. Sappa, O. Gambino, G. Cetini, J. Organomet.
Chem. 35, 375 (1972);
e) A. J. Deeming, M. Underhill, J. Organomet.
Chem. 42, C60 (1972);
f) B. F. G. Johnson, J. Lewis, D. Pippard, P. R.
Raithby, G. M. Sheldrick, K. D. Rouse, J. Chem.
Soc. Dalton Trans. 616 (1979);
e) M. Herberhold, U. Bertholdt, B. Wrackmeyer, Z.
Naturforsch 51b. (1996) in press;
f) M. Herberhold, U. Bertholdt, J. Organomet.
Chem. (1996) in press.
[7] P Braunstein, E. Sappa, A. Tiripicchio, M.
Tiripicchio-Camellini, Inorg. Chim. Acta 45, LI91
(1980).
[8] G. J. Martin, M. L. Martin, J.-P Gouesnard, “l5N-
NMR Spectroscopy”, Springer- Verlag, Berlin, Hei-
delberg, New York (1981).
[9] B. E. R. Schilling, R. Hoffmann, J. Am. Chem. Soc.
101, 3456(1979).
[10] S. Aime, L. Milone, M. Valle, Inorg. Chim. Acta 18,
9 (1976).
[11] a) T. J. Norwood, J. Boyd, J. Heritage, N. Scoffe, I.
D. Campbell, J. Magn. Reson. 87, 488 (1990);
b) A. Bax, M. Ikura, L. E. Kay, D. A. Torchia, R.
Tschudin, J. Magn. Reson. 86, 304 (1990);
c) L. Müller, J. Am. Chem. Soc. 101, 4481 (1979).
g) L. Marko, J. Organomet. Chem. 213, 271 (1981).
[5] a) K. Fischer, W. Deck, M. Schwarz, H.
Vahrenkamp, Chem. Ber. 118, 4946 (1985);
b) K. Fischer, M. Müller, H. Vahrenkamp, Angew.
Chem. 96,138 (1984); Angew. Chem.; Int. Ed. Engl.
23,140(1984);
c) H. Vahrenkamp, Comments Inorg. Chem. 4, 253
(1985);
d) L.-C. Song, J.-Y. Shen, Q.-M. Hu, X.-Y. Huang,
Organometallics 14, 98 (1995);
e) U. Honrath, H. Vahrenkamp, Z. Naturforsch. 39b,
559 (1984);
f) W.-H. Sun, S.-Y. Yang, H.-Q. Wang, Q.-F. Zhou,
K.-B. Yu, J. Organomet. Chem. 465, 263 (1994).
[6] a) M. Herberhold, W. Bühlmeyer, Angew. Chem.
96, 64 (1984); Angew. Chem., Int. Ed. Engl. 23, 80
(1984);
Unauthenticated
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