[Br2B(η5-C5H4)Mn(CO) 3] - A versatile precursor for boron-based ligands

Article abstract of DOI:10.1002/zaac.200700207

A range of potential boron-based ligand precursors has been synthesized starting from [{Br₂B(η⁵-C₅H₄)) Mn(CO)₃] (1) via salt elimination reactions. These comprise ligand precursors suitable for the preparation of i) amja-metallocenes such as [CymB(η¹-C₅H₅)J (2), [CymB(l-C ₉H₇)₂[ (3a), and [CymB(3C₉H ₂)₂[ (3b), ii) constrained geometry complexes such as [CymB(Br)N(H)tBu] (5) as well as iii) ansa-diamido complexes such as [CymB{N(H)Ph}₂[ (4) and [CymB{N(H)/Bu}₂] (6) (Cym = cymantrenyl, C₅H₅ = cyclopentadienyl, C₉H ₇ = indenyl). Furthermore, we present the hydrolysis of 1, leading to the three-fold cymantrenyl-substituted boroxine [(OB(η⁵-C ₅H₄)(Mn(CO)₃]₃ (7). All new compounds have been characterized by multinuclear NMR spectroscopic techniques and in the case of 1 and 7 by X-ray diffraction analyses.

Full text of DOI:10.1002/zaac.200700207

DOI: 10.1002/zaac.200700207
[{Br2B(η5-C5H4)}Mn(CO)3] ؊ A versatile Precursor for Boron-based Ligands
Holger Braunschweig*, Holger Bera, Sascha Stellwag, Sylvia Schwarz, Yasmin Hemberger,
and Krzysztof Radacki
Würzburg, Institut für Anorganische Chemie der Universität
Received April 16th, 2007.
Dedicated to Professor Dieter Fenske on the Occasion of his 65th Birthday
Abstract. A range of potential boron-based ligand precursors has
been synthesized starting from [{Br2B(η5-C5H4)}Mn(CO)3] (1) via
salt elimination reactions. These comprise ligand precursors
suitable for the preparation of i) ansa-metallocenes such as
[CymB(η1-C5H5)2] (2), [CymB(1-C9H7)2] (3a), and [CymB(3-
C9H7)2] (3b), ii) constrained geometry complexes such as
[CymB(Br)N(H)tBu] (5) as well as iii) ansa-diamido complexes
such as [CymB{N(H)Ph}2] (4) and [CymB{N(H)tBu}2] (6) (Cym ϭ
cymantrenyl, C5H5 ϭ cyclopentadienyl, C9H7 ϭ indenyl). Further-
more, we present the hydrolysis of 1, leading to the three-fold cy-
mantrenyl-substituted boroxine [{OB(η5-C5H4)}Mn(CO)3]3 (7). All
new compounds have been characterized by multinuclear NMR
spectroscopic techniques and in the case of 1 and 7 by X-ray dif-
fraction analyses.
Keywords: Boron; Boranes; Cymantrene; Ligand; ansa-Complexes
Introduction
constrained geometry complexes (CGCs, IV) [9, 10] as well
as ansa-diamido complexes (V) [11].
Recently, we presented the molecular structure of
[{Br2B(η5-C5H3Me)}Mn(CO)3] and emphasized the poten-
tial of its parent compound [{Br2B(η5-C5H4)}Mn(CO)3] for
the synthesis of complexes of the type [LxMϪB(Br)Cym]
(Cym ϭ [(η5-C5H4)}Mn(CO)3]) [1]. Our interest in these
both long-known half-sandwich complexes [2a] and their
derivatives arose from recent investigations on the related
boryl substituted metallocenes [{R2B(η5-C5H4)}Fe(η5-
C5H5)], which established a correlation between the elec-
tronic stabilization of the boron atom provided by the iron
atom and the structure of the molecule, i.e. bending of the
exo-BR2 group toward the iron atom [2]. This led to the
question as to whether the metal atom in corresponding
half-sandwich complexes, derived from [{Br2B(η5-
C5H4)}Mn(CO)3] or [{Br2B(η5-C5H3Me)}Mn(CO)3], exhib-
its a similar stabilizing effect on Cp-bound BR2 groups.
Apart from investigations concerning the nature of the
metalϪboron interactions, [{Br2B(η5-C5H4)}Mn(CO)3]
should own potential as precursor for boron-bridged
ligands, suitable for the synthesis of a range of ansa-com-
plexes, as we have already shown for [FcBBr2] (Fc ϭ ferro-
cenyl) [3]. Such boron-bridged ligands have already
attracted great attention as building blocks in strained (I)
[4, 5] and unstrained (II, III) [6Ϫ8] metallocenophanes,
Complexes derived from such boron-containing ligands
play an important role in areas such as the synthesis of
novel organometallic polymers and the homogeneous
Ziegler-Natta type polymerization of olefins. The incorpor-
ation of a boron bridge has been associated with a number
of beneficial characteristics, e.g. an improved catalytic ac-
tivity of [n]bora-metallocenophanes (n ϭ 1, 2) [6e]. Further-
more, the potential of a Lewis-acidic boron atom in ansa-
metallocenes to activate the pendant transition metal center
without the need for added Lewis-acidic co-catalysts has
been envisaged [10a]. However, the Lewis-acidity of the
boron atom in currently known boron-bridged ansa-metal-
locenes of the types II and III is attenuated either by π-
* Prof. Dr. H. Braunschweig
Institut für Anorganische Chemie der Universität
Am Hubland
D-97074 Würzburg / Deutschland
E-mail: h.braunschweig@mail.uni-wuerzburg.de
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[{Br2B(η5-C5H4)}Mn(CO)3]
donation from an amino group or by the formation of
base adducts.
Consequently, we attempted to synthesize corresponding
complexes with more pronounced Lewis-acidic boron
bridges, i.e. less electronic stabilization of the electron de-
ficient boron atoms. Ligands based on substituted ferro-
cenyl or cymantrenylboranes appeared to be a suitable
starting point since both transition-metal fragments are
known to provide only a moderate stabilization of the
boron atom [1, 12]. Based on the versatile chemistry of
ferrocenyldibromoborane, [FcBBr2], we now focused on the
related cymantrenyl system.
In the present paper, we describe the structural charac-
terization of the precursor [{Br2B(η5-C5H4)}Mn(CO)3] and
present a series of substitution reactions as well as its be-
haviour towards hydrolysis, leading to an unusual three-fold
cymantrenyl-substituted boroxine, which could also be
structurally characterized. The cymantrenylboranediyl-
bridged ligand precursors thus obtained may find appli-
cation in the preparation of new ansa-metallocenes, CGCs
and ansa-diamido complexes.
Fig. 1 Molecular structure of [{Br2B(η5-C5H4)}Mn(CO)3] (1) in
the solid state with the atom-numbering scheme. Displacement el-
lipsoids are drawn at the 50 % probability level and the hydrogen
atoms have been omitted for clarity.
˚
Selected bond lengths /A, bond and torsion angles /°: Br1ϪB1 1.928(4),
B1ϪC11 1.520(5), B1ϪBr2 1.901(4), C11ϪB1ϪBr2 121.7(2), C11ϪB1ϪBr1
120.5(3), Br2ϪB1ϪBr1 117.79(19), C15ϪC11ϪB1 126.2(3), C12ϪC11ϪB1
126.2(3), B1ϪC11ϪMn1 111.7(2).
The molecular structure of 1 is very similar to that of the
methyl derivative [{Br2B(η5-C5H3Me)}Mn(CO)3], and like-
wise displays the characteristic bending of the exo-boryl
group toward the manganese atom which can be regarded
as the most important structural feature of both com-
pounds. With a dip angle of 11.71°, the deviation from
planarity is less pronounced than that in [{Br2B(η5-
C5H3Me)}Mn(CO)3] or [FcBBr2] (12.3° and 17.7, 18.9°,
respectively) but still significant. The greater value of α* for
[{Br2B(η5-C5H3Me)}Mn(CO)3] in comparison to 1 is sup-
posed to be due to the presence of the cyclopentadienyl-
bound methyl group in the latter, which slightly increases
the electron density at the manganese atom, thus leading to
a more pronounced Mn···B interaction. As a consequence,
the Mn···B distance in [{Br2B(η5-C5H3Me)}Mn(CO)3]
Results and Discussion
Synthesis and structure of
cymantrenyl(dibromo)borane
According to equation (1), cymantrenyl(dibromo)borane
(1) was obtained similarly to procedures already described
30 years ago by Siebert and co-workers and isolated as a
low-melting product of oily appearance [2a]. Due to the
toxicity of CS2, we replaced this solvent by hexane, leading
to 1 in 66 % yield, which is just slightly lower than the yield
obtained from CS2 (76 %). From such an oily sample, ex-
tremely air- and moisture-sensitive single crystals Ϫ suitable
for diffraction analysis Ϫ were obtained after storage at
Ϫ30 °C over the period of months.
˚
˚
(2.992 A) is slightly shorter than that in 1 (3.028 A).
Table 1 Comparison of selected structural parameters, bond
˚
lengths /A, and bond angles /°
[CymBBr2]
[CymЈBBr2] [1]
[FcBBr2] [2]
X1 Ϫ [M]
B Ϫ [M]
Cipso Ϫ B
Br1 Ϫ B
1.767
3.028
1.764
2.992
1.504(5)
1.920(4)
1.915(4)
167.7
1.642, 1.644
2.840, 2.856
1.474, 1.484
1.945, 1.947
1.921, 1.916
162.3, 161.1
17.7 , 18.9
121.8, 123.25
121.8, 120.77
116.3, 115.96
(1)
1.520(5)
1.928(4)
1.901(4)
168.29
11.71
121.7(2)
120.5(3)
117.8(2)
Br2 Ϫ B
α ϭ X1 Ϫ Cipso Ϫ B
α* ϭ 180 Ϫ α
Cipso Ϫ B Ϫ Br2
Cipso Ϫ B Ϫ Br1
Br2 Ϫ B Ϫ Br1
12.3
120.9(3)
122.3(2)
116.8(2)
[{Br2B(η5-C5H4)}Mn(CO)3] (1) crystallizes in the ortho-
rhombic space group Pbca and is presented in figure 1.
Selected bond distances and angles are listed below and
crystal data and refinement parameters in table 2 in the
experimental section. For a better comparison, some
selected data are listed in table 1 together with those
of [{Br2B(η5-C5H4)}FeCp] and [{Br2B(η5-C5H3Me)}-
Mn(CO)3].
CymЈ ϭ [(η5-C5H3Me)}Mn(CO)3]
X1 ϭ centroid of corresponding compound.
ansa-Metallocene ligand precursor
The reaction of [{Br2B(η5-C5H4)}Mn(CO)3] (1) and two
equivalents of Na[C5H5] (C5H5 ϭ cyclopentadienyl) or
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H. Braunschweig, H. Bera, S. Stellwag, S. Schwarz, Y. Hemberger, K. Radacki
Li[C9H7] (C9H7 ϭ indenyl) in toluene leads to the forma-
an 11B NMR signal at δ ϭ 60.2, which is shifted by about
8 ppm with respect to that of 3a.
tion of the cymantrenylboranes 2 and 3, according to equa-
tion (2). Both compounds were obtained in almost quanti-
tative yields as orange oils, and identified by mass spec-
trometry and multinuclear NMR spectroscopy. The latter
reveals the formation of one symmetrical major isomer (i.e.
va/va or vh/vh [13]) but the question remains open whether
the va/va or vh/vh isomer was generated. This finding dif-
fers from the analogous ferrocenyl compound, which con-
(3)
1
sists of two isomers [3]. In the H and 13C NMR spectra,
this symmetric isomer exhibits only one resonance corre-
sponding to the methylene groups of the cyclopentadienyl
rings at δ ϭ 3.19 and 47.53, respectively. The 13C NMR
resonance corresponding to the boron bound carbon atom
could not be detected due to quadrupolar 13C-11B coupling
[14]. In the 11B NMR spectrum of 2, a single resonance at
δ ϭ 52.2 is observed, which is shifted to low field by 4 ppm
compared to the corresponding signal of 1.
Synthesis of phenylamino-substituted
cymantrenylboranes
The alkali salt elimination reaction of 1 and one equivalent
of Li[NHPh] in toluene leads to the formation of the di-
phenylamino-substituted cymantrenylborane 4 (Eq. (4)). 4
was obtained as an orange powder in 60 % yield. The 11B
NMR spectrum displays a singular resonance at δ ϭ 28.1
which is significantly high-field shifted relative to the corre-
sponding signal for 1. This value resembles that of the anal-
ogous ferrocene compound (31.5 ppm) [3], and the signifi-
cant high-field shift of about 20 ppm with respect to 1 and
[FcBBr2] is the result of π donation from the nitrogen lone
pair into the empty p orbital on the Lewis-acidic boron
atom. Ambient temperature 1H and 13C NMR spectra of 4
exhibit only one set of signals corresponding to the target
compound, consistent with facile rotation about the BϪN
bonds, whose bond orders are expected to be 1.5 at most
[3].
The cymantrenyl(diindenyl)borane 3a is obtained as the
kinetically favoured product, in which the boron atom is
linked to the sp3 hybridized carbon atoms of the indenyl
substituents, i.e. in 1-position, thus resulting in two chirali-
ties in the molecule [13]. Hence, 3a is consisting of a mixture
of two diastereomers with the possible RR, SS and RS con-
1
figurations and the interpretation of the H and 13C NMR
spectroscopic data proved difficult. The 11B NMR spectrum
reveals a singlet at δ ϭ 68.2, i.e. low field shifted by about
20 ppm relative to that of 1.
(2a)
(2b)
(4)
Synthesis of tert-butylamino-substituted
cymantrenylboranes
As recently reported for the analogous ferrocenyl(diind-
enyl)borane [3], 3a can be isomerized in the presence of
catalytic amounts of NEt3 to the thermodynamically more
stable 3-indenyl isomer 3b, i.e. the isomer in that the boron
atom is bound to an sp2 hybridized carbon atom (Eq. (3)).
The isomerization was carried out in toluene and finished
after 6 hours at ambient temperature, leading to a single
Precursor 1 was reacted with one and two equivalents of
Li[NHtBu] in toluene to give the tert-butylamino- and di-
tert-butylamino substituted cymantrenylboranes 5 and 6 via
salt elimination (Eq. (5)). Both compounds are obtained
after work up as orange solids in moderate yields of 30
(5) and 45 % (6). As already found for the phenylamino-
1
substituted cymantrenyl derivative, the H and 13C NMR
1
isomer without any chirality in 60 % yield. The H and 13C
spectra of 5 and 6 display each only one set of signals corre-
sponding to the target compounds. In the proton NMR
spectrum, the signals for the tert-butyl groups are detected
at δ ϭ 1.21 (5) and 1.13 (6). The 11B NMR resonances are
found at δ ϭ 32.6 (5) and 27.0 (6), which are very similar
NMR spectra are significantly simplified when compared
to the corresponding spectra of the starting compound, and
all observed signals can be assigned. The isomerization re-
sults in a shielding of the boron atom that is reflected by
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[{Br2B(η5-C5H4)}Mn(CO)3]
to the value of the phenylamino derivative 4. The observed
values are significantly high-field shifted (mean: 17 ppm)
relative to the corresponding signal for 1.
arrangement and the fact that all angles around boron and
oxygen atoms lie very close to 120° (from 117.6 to 122.4°)
confirm the expected sp2 hybridization of the respective
atoms. The boronϪCCp distances ranges from 1.540
˚
(B3ϪC51) to 1.547 A (C11ϪB1) and the boronϪoxygen
˚
bond lengths from 1.371 (O1ϪB3) up to 1.383 A (O3ϪB3),
(5a)
˚
with an average of 1.378 A. All these values agree very well
with the data of the analogue triferrocenylboroxine [16].
The most characteristic feature of the structure is the orien-
tation of the three cymantrenyl fragments, which occupy all
the same side of the central six-membered boroxine ring.
The cymantrenyl fragment with Mn3 is slightly bent out of
the planarity of the whole system [6.7(5)°] which is reflected
by the torsion angle O3ϪB3ϪC51ϪC55 and is supposedly
due to sterical reasons or packing effects.
(5b)
Synthesis and structure of tricymantrenylboroxine
In the past we reported on the synthesis and structure of
the first half-sandwich-substituted borazine compound
showing two η1-coordinated [CpFe(CO)3] fragments [15].
Borazines with such boronϪtransition metal bond substi-
tution patterns are believed to play an important role in the
Rh-catalyzed hydroboration of acetylenes with (HBNH)3.
In addition, polynuclear aggregates of transition metals are
of great current interest [17]. In this context, following in-
vestigations were undertaken.
When a toluene solution of 1 is treated with water, the
exclusive formation of the tri-cymantrenyl-substituted
boroxine [{OB(η5-C5H4)}Mn(CO)3]3 (7) can be observed
(Eq. (6)). 7 was obtained as an almost white solid in quanti-
tative yield.
Fig. 2 Molecular structure of [{OB(η5-C5H4)}Mn(CO)3]3 (7) in
the solid state with the atom-numbering scheme. Displacement el-
lipsoids are drawn at the 50 % probability level and the hydrogen
atoms have been omitted for clarity.
Selected bond lengths /A, bond and torsion angles /°: O1ϪB3 1.371(4),
O1ϪB1 1.380(4), B1ϪO2 1.375(4), B1ϪC11 1.547(5), O2ϪB2 1.377(4),
B2ϪO3 1.382(4), B2ϪC31 1.540(5), O3ϪB3 1.383(4), B3ϪC51 1.540(5),
O2ϪB1ϪO1 119.7(3), O2ϪB1ϪC11 120.2(3), O1ϪB1ϪC11 120.1(3),
B1ϪO2ϪB2 120.5(3), O2ϪB2ϪO3 119.6(3), O2ϪB2ϪC31 119.5(3),
O3ϪB2ϪC31 120.9(3), B2ϪO3ϪB3 119.9(3), O1ϪB3ϪO3 120.0(3),
O1ϪB3ϪC51 122.4(3), O3ϪB3ϪC51 117.6(3), O3ϪB3ϪC51ϪC55 6.7(5).
(6)
Conclusions
Suitable single crystals have been obtained from slow
evaporation of a saturated CDCl3 solution of 7. The result
of the X-ray diffraction analysis is depicted in figure 2.
[{OB(η5-C5H4)}Mn(CO)3]3 (7) crystallizes in the triclinic
space group P1. Selected bond distances and angles are
listed below, and crystal data and refinement parameters in
table 2 in the experimental section.
We presented the X-ray structure of [{Br2B(η5-
C5H4)}Mn(CO)3] (1) and demonstrated that this compound
is a very versatile precursor for boron-based ligands, which
can be readily modified with respect to the aromatic groups
being attached to boron as well as the organo groups of
the amines.
Thus, the work reported in this paper opens the door to
a range of new ansa-metallocenes, CGCs and ansa-diamido
complexes, which are currently under investigation.
¯
The boroxine framework is planar and interestingly the
aromatic cyclopentadienyl rings lie in the same plane. This
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H. Braunschweig, H. Bera, S. Stellwag, S. Schwarz, Y. Hemberger, K. Radacki
1H NMR (C6D6, 500 MHz): δ ϭ 4.01, 4.30 (m, 4H, CpCym); 5.09 (m, 2H,
NH); 6.77-7.01 (kB, 10H, CHPh). Ϫ 11B NMR (C6D6, 160 MHz): δ ϭ 28.1.
Experimental Section
Ϫ
13C NMR (C6D6, 125 MHz): δ ϭ 84.70, 91.04 (CH, Cp); 123.01, 123.20,
General considerations
129.84 (CHPh); 143.75 (Cipso, Ph); 225.93 (CO). Ϫ MS m/z (%): 204 (26)
[Cymϩ]; 148 (24) [MnCpCOϩ]; 120 (100) [MnCpϩ]; 93 (19) [NH2C6H5ϩ].
All manipulations were carried out under a dry argon atmosphere
with common Schlenk techniques. Solvents were dried with a sol-
vent purification system (SPS) from M. Braun and stored under
argon over molecular sieves; reagents were dried and purified by
standard procedures. [CymBBr2](1) [2a] and Na[C5H5] [18] were
obtained according to literature procedures. Lithium indenide and
lithium amides were prepared by deprotonation of indene and cor-
responding amines, respectively, utilising butyl lithium. NMR spec-
tra were recorded on either a Bruker 200 Avance spectrometer at
200.1 (1H, internal standard TMS) and 64.2 MHz (11B, BF3·OEt2
in C6D6 as external standard), a Bruker 400 Avance spectrometer
at 400.13 (1H, internal standard TMS) and 100.61 MHz (13C{1H},
[CymBBr(NHt-C4H9)] (5)
1.00 g (2.68 mmol) [CymBBr2] (1) was dissolved in 15 mL toluene,
cooled to Ϫ80 °C and a suspension of 0.21 g (2.68 mmol) Li[NHt-
C4H9] in 15 mL toluene was added. After stirring the mixture for
a few minutes, it was allowed to warm up to ambient temperature
and stirred for further 16 h. The pale yellow precipitate was re-
moved by centrifugation. All volatiles were then removed in vacuo
to yield after recrystallization from hexane at Ϫ30 °C 5 0.29 g
(30 %) as a yellow solid. C12H14BBrMnNO3 (365.90): C 39.57 (calc.
39.39); H 4.46 (calc. 3.86); N 2.88 (calc. 3.83) %.
1H NMR (C6D6, 400 MHz): δ ϭ 1.21 (9H, CH3); 4.09 (2H, CpCym); 4.45
(1H, NH); 4.48 (2H, CpCym). Ϫ 11B NMR (C6D6, 64 MHz): δ ϭ 32.6. Ϫ 13C
NMR (C6D6, 100 MHz): δ ϭ 31.89 (CH3, t-Bu); 52.37 (C, t-Bu); 85.47, 91.10
(CH, Cp); 225.28 (CO). Ϫ MS m/z (%): 204 (12) [Cymϩ]; 120 (34) [MnCpϩ];
71 (1) [NC4H9ϩ]; 58 (100) [C4H10ϩ].
APT, internal standard TMS) or
a Bruker Avance 500 at
500.13 MHz (1H, internal standard TMS), 125.77 MHz (13C{1H},
APT, internal standard TMS) and 160.46 MHz (11B, BF3·OEt2 as
external standard).
Elemental analyses (C, H, N) were obtained from a Vario Micro
(Elementar Analysensysteme).
[CymB(NHt-Bu)2] (6)
[CymB(η1-C5H5)2] (2)
Following essentially the same procedure as for the synthesis of 5,
1.00 g (2.68 mmol) [CymBBr2] (1) was reacted with 0.43 g
(5.44 mmol) Li[NHt-C4H9]. After work-up, 6 0.85 g (89 %) was ob-
tained as an orange solid. C16H24BMnN2O3 (358.12): C 53.57 (calc.
53.90); H 6.23 (calc. 6.19); N 6.67 (calc. 6.84) %.
1H NMR (C6D6, 400 MHz): δ ϭ 1.13 (18H, CH3 t-Bu); 3.09 (2H, NH) 3.99,
4.58 (4H, CpCym). Ϫ 11B NMR (C6D6, 64 MHz): δ ϭ 26.99. Ϫ 13C NMR
(C6D6, 100 MHz): δ ϭ 33.39 (CH3, t-Bu); 49.41 (C, t-Bu); 82.05, 92.61 (CH,
Cp); 226.48 (CO). Ϫ MS m/z (%): 204 (14) [Mϩ Ϫ BN2C8H20]; 148 (14) [Mϩ
Ϫ BN2C8H20 Ϫ 2CO]; 120 (58) [MnCpϩ]; 58 (100) [C4H10ϩ].
A solution of 1.00 g (2.68 mmol) [CymBBr2] (1) in 20 mL toluene
was added at 0 °C to a suspension of 0.50 g (5.68 mmol) Na[C5H5]
in 20 mL toluene. After stirring the mixture for 16 h, insoluble ma-
terial was removed by centrifugation and all volatiles were removed
in vacuo to yield 2 0.90 g (98 %) as an orange oil. 1H an 13C NMR
spectra showed to sets of signals corresponding to an isomeric mix-
ture, the data refer to the main isomer.
1H NMR (C6D6, 500 MHz): δ ϭ 3.19 (4H, CH2Cp); 4.26 (m, 2H, CH,
CpCym); 4.75-4.93 (kB, 2H, CH, CpCym); 6.65-7.20 (kB, 6H, CH, CpCp). Ϫ
11B NMR (C6D6, 160 MHz): δ ϭ 52.2. Ϫ 13C NMR (C6D6, 125 MHz): δ ϭ
47.53 (CH2, Cp); 86.79, 94.33 (CH, CpCy); 134.17, 141.96, 149.90 (CH, Cp);
225.20 (CO). Ϫ MS m/z (%): 344 (2) [Mϩ]; 260 (14) [Mϩ Ϫ 3 CO]; 55
(20) [Mnϩ].
[CymBO]3 (7)
3.00 g (8.04 mmol) [CymBBr2] (1) was dissolved in 20 mL toluene
and treated with an excess of water at 0 °C, immediately a light
grey solid appeared. After stirring the mixture for a few more mi-
nutes, the solid was filtered and washed twice with 10 mL of tolu-
ene. Yielding 7 3.7 g (67 %) as a white Powder.
1H NMR (CDCl3, 200 MHz): δ ϭ 5.29; (2H, CpCym) 4.95 (2H, CpCym). Ϫ
11B NMR (CDCl3, 64 MHz): δ ϭ 28.05. Ϫ 13C NMR (D8-THF, 500 MHz):
δ ϭ 88.58 (CH, Cp); 94.36 (CH, Cp); 227.28 (CO). Ϫ MS m/z (%): 690 (21)
[Mϩ]; 606 (91) [Mϩ Ϫ 3 CO]; 438 (100) [Mϩ Ϫ 9 CO].
[CymB(η1-C9H6)2] (3a,b)
In analogy to the synthesis of 2, 1.00 g (2.68 mmol) [CymBBr2] (1)
was dissolved in 20 mL tolueneand added at 0 °C to a suspension
of 0.70 g (5.73 mmol) Li[C9H6] in 20 mL toluene. After stirring the
mixture for 16 h, a catalytic amount of NEt3 was added to the
suspension to form only one isomer. After another 16 h all insol-
uble material was removed by centrifugation and all volatiles were
removed in vacuo to yield 3a 0.71 g (60 %) as a yellow solid.
1H NMR (C6D6, 500 MHz): δ ϭ 3.26 (d, 3J ϭ 1.89 Hz, 4H, CH2 Ind); 4.21,
4.85 (m, 4H, CpCym); 6.97 (t, 3J ϭ 1.89 Hz, 2H, CHαInd); 6.98 Ϫ 7.15 (kB,
8H, CHInd); 7.32 (m, 2H, CHInd); 7.42 (m, 2H, CHInd). Ϫ 11B NMR (C6D6,
64 MHz): δ ϭ 60.2. Ϫ 13C NMR (C6D6, 100 MHz): δ ϭ 41.53 (CH2 Ind);
87.70, 95.43 (CH, CpCym); 123.70, 124.50, 125.50, 127.02 (CHInd); 144.88
Crystal structure determination
The crystal data of 1 and 7 were collected with a Bruker A2
diffractometer with a CCD area detector and multi-layer mirror
monochromated MoKα radiation. The structures were solved using
direct methods, refined with the Shelx software package
(G. M. Sheldrick, University of Göttingen 1997) and expanded
using Fourier techniques. All non-hydrogen atoms were refined an-
isotropically. Hydrogen atoms were assigned idealized position and
were included in structure factor calculations.
(CInd); 145.27 (CHInd); 148.30 (CInd
) ppm. Ϫ MS m/z (%): 148 (8)
[MnCpCOϩ]; 120 (44) [MnCpϩ]; 115 (100) [Indϩ]; 55 (56) [Mnϩ].
[CymB(NHC6H5)2] (4)
Following essentially the same procedure as for the synthesis of 2,
1.00 g (2.68 mmol) [CymBBr2] (1) was reacted with 0.53 g
(5.35 mmol) Li[NHC6H5]. After work-up, 4 0.64 g (60 %) was ob-
tained as an orange solid.
Crystallographic data have been deposited with the Cambridge
Crystallographic Data Center as supplementary publication CCDC
nos 642883 (1) and 642884 (7). Copies of the data can be obtained
free of charge on application to CCDC, 12 Union Road,
2318
www.zaac.wiley-vch.de
 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2007, 2314Ϫ2320

[{Br2B(η5-C5H4)}Mn(CO)3]
Cambridge CB21EZ, UK (fax: ϩ44 1223Ϫ336Ϫ033, e-mail:
deposit@ccdc.cam.ac.uk).
5765; c) H. Braunschweig, M. Homberger, C. Hu, X. Zheng,
E. Gullo, G. Clentsmith, M. Lutz, Organometallics 2004, 23,
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Chem. 2005, 117, 5792; Angew. Chem. Int. Ed. 2005, 117, 5647;
H. Braunschweig, M. Lutz, K. Radacki, A. Schaumlöffel,
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Braunschweig, T. Kupfer, K. Radacki, Angew. Chem. 2007,
119, 1658; Angew. Chem. Int. Ed. 2007, 46, 1630.
Table 2 Crystal data and refinement parameters for the com-
pounds 1 and 7.
Compound
1
7
Empirical formula
Formula weight /g·molϪ1
Temperature /K
Radiation, λ /A
Crystal system
Space group
C8H4BBr2MnO3
373.68
100(2)
MoKα 0.71073
orthorhombic
Pbca
C16H20B2Br4Mn2O6
759.46
100(2)
MoKα 0.71073
triclinic
¯
P1
[5] M. Herberhold, U. Dörfler, B. Wrackmeyer, J. Organomet.
Chem. 1997, 530, 117.
˚
[6] a) H. Braunschweig, C. von Koblinski, R. Wang, Eur. J. Inorg.
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18, 2288; b) A. J. Ashe, III, X. Fang, A. Hokky, J. W. Kampf,
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ganometallics 1997, 16, 4546; b) C. T. Burns, D. S. Stelck, P. J.
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Unit cell dimensions
˚
a /A
13.5414(13)
11.9003(12)
13.7776(13)
7.2244(10)
12.4316(18)
15.719(2)
107.670(7)
92.889(7)
99.896(7)
1317.2(3)
2
˚
b /A
˚
c /A
α /°
β /°
γ /°
3
˚
Volume /A
2220.2(4)
8
2.236
8.366
1408
Z
Calculated density /Mg·mϪ3
Absorbtion coefficient /mmϪ1
F(000)
1.915
7.052
728
Theta range for collection
Reflections collected
Independent reflections
Minimum/maximum transmision 0.2029/0.5366
Refinement method
2.72 to 28.45°
104645
2789
1.75 to 29.36°
61027
6825
0.3328/0.5694
Full-matrix
Full-matrix
last-squares on F2 last-squares on F2
Data / parameters / restrains
Goodness-of-fit on F2
Final R indices [I>2σ(I)]
2789 / 136 / 0
1.122
R1 ϭ 0.0319,
wR2 ϭ 0.0749
R2 ϭ 0.0450,
wR2 ϭ 0.0831
1.124 / Ϫ0.962
6825 / 379 / 0
1.026
R1 ϭ 0.0455,
wR2 ϭ 0.0908
R2 ϭ 0.1060,
wR2 ϭ 0.1075
0.690 / Ϫ0.627
R indices (all data)
Maximum/minimum residual
Ϫ3
˚
electron density /e·A
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Acknowledgements. We thank DFG and the Fonds der Chemischen
Industrie for financial support.
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Z. Anorg. Allg. Chem. 2007, 2314Ϫ2320