Borole derivatives. 23. Reversible carbonylation and Lewis base degradation of the heterocubane [Rh(μ3-I)(C4H4BPh)]4 and of the bis(borole) complex RhI(C4H4BPh)2 and synthesis and structure of the dinuclear complex Cp*Rh(μ-I)3Rh(C4H4BPh)1

Article abstract of DOI:10.1021/om9704410

The heterocubane [Rh(μ₃-I)(C₄H₄BPh)]₄ (2a) readily adds Lewis bases to form the mononuclear products RhI(py)₂(C₄H₄BPh) (4), and RhI(bpy)(C₄H₄BPh) (7), the labile solution species RhI(NCMe)₂(C₄H₄BPh) (8) and RhI(CO)₂(C₄H₄BPh) (9), RhI(PPh₃)₂(C₄H₄BPh) (11), the 1,1′-bis(diphenylphosphino)ferrocene complex RhI(dppf)(C₄H₄BPh) (13), and the norbornadiene complex RhI(nbd)(C₄H₄BPh) (14) as well as the dinuclear products [Rh(μ-I)(py)-(C₄H₄BPh)]₂ (5), [Rh(μ-I)(CO)(C₄H₄BPh)]₂ (10), and the bis(diphenylphosphino)methane complex [Rh₂(μ-I)₂(μ-dppm)(C₄H ₄BPh)₂] (12). The complexes 5 and 10 exist as mixtures of cis and trans isomers; the isomeric carbonyls 10 interconvert slowly at ambient temperature, while the isomeric pyridine complexes 5 show fast interchange on the NMR time scale at 20 °C and low-temperature limiting spectra at -80 °C. The heterocubane also adds (RhI₂-Cp*)₂ (which acts as a Lewis base and as a Lewis acid) to produce the novel unsymmetrical dinuclear complex Cp*Rh(μ-I)3Rh(C₄H₄BPh) (15). Complex 15 was shown by crystal structure analysis to possess a central trigonal-bipyramidal Rh₂I₃ core, capped with the Cp* and the borole ligands, respectively. The bis(ligand) complex RhI(C₄H₄BPh)₂ (3a) reacts with excess pyridine at 20 °C to give RhI(py)₂(C₄H₄BPh) (4) and the borole-pyridine adduct C₄H₄BPh·py (6). With CO it reacts at elevated temperature (in toluene, 80 °C, 7 h) to give the dicarbonyl 9 with loss of one borole ligand.

Full text of DOI:10.1021/om9704410

4800
Organometallics 1997, 16, 4800-4806
Bor ole Der iva tives. 23. Rever sible Ca r bon yla tion a n d
Lew is Ba se Degr a d a tion of th e Heter ocu ba n e
[Rh (µ3-I)(C4H4BP h )]4 a n d of th e Bis(bor ole) Com p lex
Rh I(C4H4BP h )2 a n d Syn th esis a n d Str u ctu r e of th e
Din u clea r Com p lex Cp *Rh (µ-I)3Rh (C4H4BP h )1
Gerhard E. Herberich,* Hartmut J . Eckenrath,3 and Ulli Englert
Institut fu¨r Anorganische Chemie, Technische Hochschule Aachen, D-52056 Aachen, Germany
Received May 28, 1997X
The heterocubane [Rh(µ3-I)(C4H4BPh)]4 (2a ) readily adds Lewis bases to form the
mononuclear products RhI(py)2(C4H4BPh) (4), and RhI(bpy)(C4H4BPh) (7), the labile solution
species RhI(NCMe)2(C4H4BPh) (8) and RhI(CO)2(C4H4BPh) (9), RhI(PPh3)2(C4H4BPh) (11),
the 1,1′-bis(diphenylphosphino)ferrocene complex RhI(dppf)(C4H4BPh) (13), and the nor-
bornadiene complex RhI(nbd)(C4H4BPh) (14) as well as the dinuclear products [Rh(µ-I)(py)-
(C4H4BPh)]2 (5), [Rh(µ-I)(CO)(C4H4BPh)]2 (10), and the bis(diphenylphosphino)methane
complex [Rh2(µ-I)2(µ-dppm)(C4H4BPh)2] (12). The complexes 5 and 10 exist as mixtures of
cis and trans isomers; the isomeric carbonyls 10 interconvert slowly at ambient temperature,
while the isomeric pyridine complexes 5 show fast interchange on the NMR time scale at 20
°C and low-temperature limiting spectra at -80 °C. The heterocubane also adds (RhI2-
Cp*)2 (which acts as a Lewis base and as a Lewis acid) to produce the novel unsymmetrical
dinuclear complex Cp*Rh(µ-I)3Rh(C4H4BPh) (15). Complex 15 was shown by crystal structure
analysis to possess a central trigonal-bipyramidal Rh2I3 core, capped with the Cp* and the
borole ligands, respectively. The bis(ligand) complex RhI(C4H4BPh)2 (3a ) reacts with excess
pyridine at 20 °C to give RhI(py)2(C4H4BPh) (4) and the borole-pyridine adduct C4H4BPh‚py
(6). With CO it reacts at elevated temperature (in toluene, 80 °C, 7 h) to give the dicarbonyl
9 with loss of one borole ligand.
In tr od u ction
products.2 The complexes 2 in turn readily add ligands
such as CO and PPh3, and this addition may be
reversible or irreversible, depending on the ligands
involved. In this paper we wish to describe the role of
auxiliary ligands in the synthesis of the heterocubanes
2 and the use of 2a as the most versatile source of
(borole)rhodium fragments Rh(C4H4BPh).
In the previous paper of this series we have shown
that the triple-decker complexes 1a ,b4 (a , R ) Ph; b, R
) Me) undergo an oxidative degradation when treated
with elemental iodine in toluene or CH2Cl2.2 The
products are the heterocubanes [Rh(µ3-I)(C4H4BR)]4 (2)
and the bis(borole)iodorhodium compounds RhI(C4H4-
BR)2 (3).2,5
Resu lts a n d Discu ssion
Ad d ition of Nitr ogen Ba ses. The heterocubane 2a
adds nitrogen bases such as pyridine (py) at ambient
temperature within seconds. With py/Rh ratios g2 the
orange crystalline bis(pyridine) complex RhI(py)2(C4H4-
BPh) (4) can be isolated. When only 1 equivalent of
pyridine per Rh is used, the dark orange material [Rh-
(µ-I)(py)(C4H4BPh)]2 (5) is obtained. Molecular weight
measurements in CH2Cl2 show that 5 is dinuclear and
also seem to indicate that 5 tends to dissociate at low
concentrations. The dinuclearity of 5 implies the exist-
ence of configurational isomers cis-5 and trans-5.
The outcome of the oxidative degradation of 1 is
influenced by the presence of auxiliary ligands and can
be steered to give the heterocubanes 2 as the sole
Crystals of complex 4 tend to lose pyridine under
vacuum. The same tendency is observed in solution,
where the chemical shifts are markedly different at -80
and 20 °C, respectively, indicating a reversible dissocia-
tion of pyridine. When pyridine is added to solutions
of pure bis(pyridine) complex 4, only one set of pyridine
signals is seen at ambient temperature, while at low
temperature (1H NMR, 500 MHz, CD2Cl2, -80 °C) a
slow-exchange regime with two sets of pyridine signals
for 4 and free pyridine is observed. The low-tempera-
X Abstract published in Advance ACS Abstracts, September 15, 1997.
(1) Part 22: See ref 2.
(2) Herberich, G. E.; Eckenrath, H. J .; Englert, U. Organometallics
1997, 16, 4292.
(3) Eckenrath, H. J . Doctoral Dissertation, Technische Hochschule
Aachen, Aachen, Germany, 1997.
(4) (a) Herberich, G. E.; Hessner, B.; Boveleth, W.; Lu¨the, H.; Saive,
R.; Zelenka, L. Angew. Chem., Int. Ed. Engl. 1983, 22, 996; Angew.
Chem. Suppl. 1983, 1503. (b) Herberich, G. E.; Bu¨schges, U.; Hessner,
B.; Lu¨the, H. J . Organomet. Chem. 1986, 312, 13.
(5) In solution the complexes 3 exhibit
a dynamic equilibrium
between two conformational isomers. Only the major isomer of Cs
symmetry is shown.
S0276-7333(97)00441-X CCC: $14.00 © 1997 American Chemical Society

Borole Derivatives
Organometallics, Vol. 16, No. 22, 1997 4801
situation. Thus, the NMR spectra show chemical shifts
that are somewhat concentration dependent, but indi-
vidual species cannot be identified. Molecular weight
measurements show that the predominant solution
species is mononuclear, presumably the bis(acetonitrile)
complex RhI(NCMe)2(C4H4BPh) (8).
ture NMR spectra of 4 show lateral symmetry. This
would be consistent with effective lateral symmetry due
to a low barrier to internal rotation and also with a
symmetric preferential conformation such as that found
previously in the complex RhCl(PPh3)2(C4H4BPh),6 where
the Rh-Cl bond is in the pseudoaxial position of a
distorted tetragonal pyramid with the boron eclipsed
with this bond. Unfortunately, the spectral data ob-
tained do not allow us to clarify this issue.
Low-temperature NMR spectra of 5 show the presence
of two very similar isomers of almost identical energy,
and both isomers show effective mirror symmetry for
the (borole)rhodium fragments with two kinds of protons
and two kinds of carbon nuclei. At 20 °C only averaged
spectra are seen. We interpret these observations as
due to the interconversion of cis-5 and trans-5. As a
consequence of the fast interconversion the two isomers
can only be handled as an inseparable mixture.
Ca r bon yla tion . When a solution of 2a in CH2Cl2 is
stirred under an atmosphere of carbon monoxide, the
color changes from dark red to light orange within a
few seconds. A CDCl3 solution displays two ν(CO) bands
of equal intensity at 2108 and 2080 cm-1. These bands
are assigned to the mononuclear dicarbonyl RhI(CO)2-
(C4H4BPh) (9). The homologous cobalt complex CoI-
(CO)2(C4H4BPh) shows CO bands at 2086 and 2058 cm-1
in CH2Cl2.9
The bis(ligand) complex 3a is readily attacked by
excess pyridine at ambient temperature to give complex
4 and the labile borole-pyridine adduct 6 (δ(11B) 2 ppm).
Lewis base adducts of boroles have been described in
several instances.4b,7,8 When the solvent is removed
under vacuum, the adduct 6 decomposes and, after
addition of a small amount of pyridine, the oily residue
can be crystallized from toluene to give 4.
The substitution-labile bis(pyridine) complex 4 reacts
with 2,2′-bipyridine (bpy) to form the robust yellow
complex RhI(bpy)(C4H4BPh) (7) within a few seconds.
This compound can be made equally well from 2a and
2,2′-bipyridine in CH2Cl2 or CHCl3 solutions. No fur-
ther compound appears when 2a is treated with less
than 1 equiv of 2,2′-bipyridine (Rh/bpy > 1); part of the
heterocubane 2a simply remains unreacted.
Acetonitrile adds to the heterocubane 2a reversibly,
and 2a possesses an enhanced solubility in this solvent.
Removal of the solvent regenerates 2a . The solutions
contain several species which are in a fast exchange
The dicarbonyl complex 9 only exists under an
atmosphere of CO. When the solvent is removed under
vacuum, an orange material is obtained as a residue.
Solution NMR spectra of this residue at ambient tem-
perature disclose the presence of two species with
effective mirror symmetry and marginally different
spectral data. We assign the observed spectra to cis/
trans isomeric, dinuclear species [Rh(µ-I)(CO)(C4H4-
BPh)]2 (10). The isomers cis-10 and trans-10 are labile,
but less so than the pyridine analogs 5 and, in contrast
to cis-5 and trans-5, interconvert slowly on the NMR
time scale at ambient temperature.10 This interpreta-
(6) Herberich, G. E.; Boveleth, W.; Hessner, B.; Hostalek, M.; Ko¨ffer,
D. P. J .; Negele, M. J . Organomet. Chem. 1987, 319, 311.
(7) (a) Eisch, J . J .; Hota, N. K.; Kozima, S. J . Am. Chem. Soc. 1969,
91, 4575. (b) Grisdale, P. J .; Walters, J . L. R. J . Organomet. Chem.
1970, 22, C19.
(8) Herberich, G. E.; Negele, M. J . Organomet. Chem. 1988, 350,
81.
(9) Herberich, G. E.; Hessner, B.; Saive, R. J . Organomet. Chem.
1987, 319, 9.
(10) The barrier could not be determined, since decarbonylation
takes place at elevated temperatures; ∆Gq > 65 kJ /mol, estimated from
Tc > 20 °C.

4802 Organometallics, Vol. 16, No. 22, 1997
Herberich et al.
tion is in accord with the IR spectrum in hexane, which
shows three ν(CO) bands at 2068, 2060, and 2054 cm-1
with relative intensities of 9/10/9. The rather small
separations between these bands can be understood as
the consequence of rather weak coupling between the
CO ligands across the two µ-I bridges.
Iod in e Degr a d a tion of 1a Revisited . When the
oxidative degradation of 1a ,b is effected by elemental
iodine in toluene or CH2Cl2, the reaction cleanly follows
Scheme 1.2 If, however, coordinating solvents are
present, the solvent may participate and react with any
of the reactands. We discuss this aspect for the phenyl
series only.
(dppm) affords the robust dinuclear compound [Rh2(µ-
I)2(µ-dppm)(C4H4BPh)2] (12). This complex is remark-
ably stable; even in the presence of a large excess of
dppm it remains the major species in the solution.
Structurally, complex 12 is related to the dinuclear
species cis-5 and cis-10 and displays effective C2v
symmetry. The central Rh2(µ-I)2(µ-dppm) core is rec-
ognized in the 31P NMR spectrum, which shows the AA′
part of an AA′XX′ type spectrum with six lines. The
very flexible 1,1′-bis(diphenylphosphino)ferrocene11 (dppf)
adds to 2a to produce the chelate complex RhI(dppf)-
(C4H4BPh) (13). Note that this compound shows effec-
tive mirror symmetry in solution at ambient tempera-
ture, with two types of P-phenyl groups and four types
of CH groups for the cyclopentadienyl rings. This
implies high ligand flexibility but also inert Rh-P and
Rh-I bonds.
Sch em e 1
(µ-C4H4Br)[Rh(C4H4BR)2]2 + I2 f
1a ,b
1/4[Rh(µ3-I)(C4H4Br)]4 RhI(C4H4BR)2
+
2a ,b
3a ,b
When acetonitrile is used as solvent, the heterocubane
2a is solubilized as the solution species 8, while 3a is
stable at ambient temperature in accord with the low
nucleophilicity of acetonitrile. Similarly, when the
oxidation is performed in toluene under an atmosphere
of CO, the heterocubane is solubilized as the dicarbonyl
9, while the less soluble bis(ligand) species 3a is almost
inert against CO at ambient temperature. At elevated
temperature (in toluene, 80 °C, 7 h) 3a reacts with CO
to give more of the dicarbonyl 9; one borole ligand is
lost and destroyed. In a previous paper we have already
described how this situation can be used to isolate either
3a (by crystallization from the mixture at low temper-
ature) or alternatively 2a (by thermolysis of the solution
of 9 under a stream of dinitrogen).2
A rather different situation ensues if pyridine or
pyridine/THF mixtures are used as solvent. The frag-
ment RhI(C4H4BPh), which in an inert solvent gives rise
to the formation of 2a , is stabilized as the bis(pyridine)
adduct 4. The second product 3a , undergoes further
degradation to give 1 equiv more of 4 and the borole-
pyridine adduct 6 (Scheme 2).
Rea ction w ith Nor bor n a d ien e. The heterocubane
2a shows very low affinity with unsaturated hydrocar-
bons. It reacts with norbornadiene (in CH2Cl2, 20 °C,
1 h) to produce the mononuclear complex RhI(nbd)(C4H4-
BPh) (14), which can be isolated as orange crystals. This
is the only positive result we can report in this context;
e.g. neither 1,3-cyclohexadiene nor 1,5-cyclooctadiene
reacts with 2a . The 1H and 13C NMR spectra of 14 could
be assigned completely with the help of (1H,1H)-COSY,
(1H,13C)-HETCOR, and NOE difference spectra. The
norbornadiene ligand displays two widely separated
signals for the bridgehead CH groups and two equiva-
lent protons in the CH2 group. The olefinic endo-CH
groups are close to the borole protons. Thus, the olefinic
bonds of the norbornadiene are parallel to the Rh-I
bond.
Sch em e 2
(µ-C4H4BPh)[Rh(C4H4BPh)2]2 + I2 f
1a
C H BPh‚py
2RhI(py)2(C4H4BPh) +
4
4
6
4
Ad d ition of P h osp h in es. The heterocubane 2a
readily adds phosphines, and the products obtained are
generally less labile then those formed with nitrogen
bases. We give three examples which stand for three
different structural types of products.
With 2 equiv of triphenylphosphine per rhodium, the
mononuclear bis(phosphine) complex RhI(PPh3)2(C4H4-
BPh) (11) is formed. Complex 11 is a robust analog of
4 and 9. The homologous chloride has been character-
ized structurally and possesses a roughly tetragonal-
pyramidal structure, with the halogen in the axial
position and the boron eclipsed with the Rh-Cl bond.6
Reaction of 2a with bis(diphenylphosphino)methane
Solutions of analytically pure complex 14 in CDCl3
show a reversible dissociation of the norbornadiene (e.g.
(11) Gan, K.-S.; Hor, T. S. A. 1,1′-Bis(diphenylphosphino)ferrocene-
Coordination Chemistry, Organic Syntheses, and Catalysis; In Fer-
rocenes; Togni, A., Hayashi, T., Eds.; VCH: Weinheim, Germany, 1995.

Borole Derivatives
Organometallics, Vol. 16, No. 22, 1997 4803
0.5% at -30 °C and 5% at 20 °C, NMR tube experiment).
1H NMR spectra show the signals of nbd in addition to
those of 14; no further signals were observed which
could tell the fate of the liberated fragment RhI(C4H4-
BPh). Complexes of the type [RhCl(diene)]2 react with
dienes at ambient temperature and exchange the di-
ene.12 Addition of a diene could be demonstrated in
solution at low temperature, e.g. in the case of RhCl-
(nbd)2.12 We note that complex 14 is the missing link
between the bis(norbornadiene) complex mentioned and
the bis(borole) compound 3a .
Ad d ition of a n Or ga n om eta llic Ha lid e a n d Syn -
th esis of th e Un sym m etr ica l Din u clea r Com p lex
Cp *Rh (µ-I)3Rh (C4H4BP h ) (15). The heterocubanes 2
exchange fragments RhI(C4H4BR) at rates which are
fast on the NMR time scale at ambient temperature.2
This observation suggests that these fragments should
also easily combine with other organometallic metal
halides. As an example we chose the reaction of 2a with
F igu r e 1. Thermal ellipsoid plot (PLATON)14 of the
molecule 15. Ellipsoids are scaled to 30% probability.
13
(RhI2Cp*)2 (Scheme 3). Note that in the present
context the fragment RhI2Cp* can be considered as a
bidentate Lewis base with an additional Lewis acid
center.
Ta ble 1. Selected Bon d Dista n ces a n d An gles
for 15
(a) Bond Distances (pm)
I1-Rh1
I2-Rh1
275.48(6)
273.46(9)
I1-Rh2
I2-Rh2
272.30(6)
271.14(9)
Sch em e 3
Rh1-C2
Rh1-C3
Rh1-B
214.7(6)
211.7(6)
229.6(9)
Rh2-C10
Rh2-C11
Rh2-C12
217(1)
213.4(7)
216.1(6)
[Rh(µ3-I)(C4H4BPh)]4 + 2[RhI2Cp*]2 f
2a
C2-C3
C2-B
142.1(9)
154.4(9)
C3-C3′
C4-B
141(1)
154(1)
4Cp*Rh(µ-I)3Rh(C4H4BPh)
(b) Bond Angles (deg)
15
Rh1-I1-Rh2
I1-Rh1-I1′
I1-Rh2-I1′
77.42(2)
84.19(2)
85.40(3)
Rh1-I2-Rh2
I1-Rh1-I2
I1-Rh2-I2
77.96(2)
84.42(2)
85.48(2)
Since the reactants are only slightly soluble, the two
starting compounds were stirred as a suspension in CH2-
Cl2 to form (20 °C, 6 h) the mixed complex 15 as dark
C3-C2-B
C2-B-C2′
108.7(6)
101.5(8)
C2-C3-C3′
C2-B-C4
110.3(4)
129.2(4)
red microcrystals. The H and 13C NMR spectra show
1
(c) Distances from Least-Squares Planes (pm)
chemical shift values which are markedly different from
those of the single components. There are no indications
of dynamic processes, as the signals are sharp and
remain unchanged when the sample is cooled to -80
°C. These observations indicate that 15 is a stable
solution species which is formed through thermody-
namic control in the reaction of Scheme 3. In contrast
to the case of 2a , the µ-I bridges in 15 are not cleaved
when the complex is dissolved in acetonitrile. However,
better ligands such as pyridine and CO (1 bar) readily
react with 16 to form mononuclear degradation prod-
ucts.
Cr ysta l Str u ctu r e of 15. Complex 15 crystallizes
in space group P21/m (Figure 1, Table 1), and the
molecule of 15 possesses crystallographic Cs symmetry.
It consists of a central trigonal-bipyramidal Rh2I3 core
which is capped with Cp* and the borole ligand. The
three best planes C5 of Cp*, (µ-I)3, and C4B are coplanar
(only the interplanar angle of 4.1(2.9)° between the
planes C5 and C4B differs from zero, though this is
barely significant).
Rh1-(C4B)
Rh1-(I3)
176.83(6)
173.59(6)
Rh2-(C5)
Rh2-(I3)
178.77(6)
168.98(6)
lengths to the Rh(C4H4B) fragment are somewhat longer
than those to the RhCp* fragment, reflecting the
stronger metal-ligand interaction with the borole ring.
The angles centered at Rh1 average 84.34° and those
centered at Rh2 average 85.45°, while those centered
at iodine average 77.60°.
The borole ring shows the usual characteristics.
There is a slight folding along the line C2,C2′ which
moves the B atom away from the metal; the vertical
distance of the boron to the plane C4 of the borole ring
amounts to 12.3(9) pm, and the less well defined folding
angle is 7.2(3.3)°. The Rh atom is shifted toward the
C4 part of the borole ring, and the resulting slip
distortion16 amounts to 9.7 pm. The C-C distances in
the borole ring are not different. This observation
indicates strong back-donation from the Rh atom into
the π3 orbital of the borole ring. Formally the three
bridging iodo ligands place half a negative charge onto
the (borole)rhodium fragment and half a positive charge
onto the Cp*Rh fragment; this situation favors the back-
bonding interaction just mentioned.
The Rh-I bond lengths (271.14(9)-275.48(6) pm) are
in the expected range.15 Note that the Rh-I bond
(12) Volger, H. C.; Gaasbeek, M. M. P.; Hogeveen, H.; Vrieze, K.
Inorg. Chim. Acta 1969, 3, 145.
(13) (a) Kang, J . W.; Moseley, K.; Maitlis, P. M. J . Am. Chem. Soc.
1969, 91, 5970. (b) Booth, B. L.; Hazeldine, R. N.; Hill, M. J . Chem.
Soc. A 1969, 1299.
Con clu d in g Rem a r k s. It was the aim of this paper
to show that the heterocubane [Rh(µ3-I)(C4H4BPh)]4 (2a )
(14) Spek, A. L. Acta Crystallogr. 1990, A46, C34.
(15) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson,
D. G.; Taylor, R. J . Chem. Soc., Dalton Trans. 1989, S1.
(16) The slip distortion is the distance between the geometric center
of the C4B ring and the projection of the metal atom onto the C4B best
plane.

4804 Organometallics, Vol. 16, No. 22, 1997
Herberich et al.
Ad d ition of P yr id in e to 2a in a 1/1 Ra tio. Complex 2a
(250 mg, 0.169 mmol) and pyridine (53.8 mg, 0.680 mmol) were
combined in CH2Cl2 (5 mL). After removal of the volatiles the
residue was washed with ether (1 mL) to give 5 (295 mg, 97%)
as a dark orange powder: mp 158 °C; in solution somewhat
air-sensitive; soluble in CH2Cl2 and toluene, moderately soluble
in ether, insoluble in hexane. Anal. Calcd for C30H28B2I2N2-
Rh2: C, 40.13; H, 3.14; N, 3.12. Found: C, 40.45; H, 3.06; N,
3.06. Molar mass Mcalc 897.81 g mol-1; in CH2Cl2 Mobs
(molarity (g/L)) 817 (39.64), 736 (20.70), 683 (9.98). SIMS
(NBA): positive ions, m/ z (Irel) 983 (100, [Rh3I2(C4H4BPh)3]+).
Data for 5 are as follows. 1H NMR (500 MHz, CD2Cl2): δ
py 8.92 (br, 4 Ho), 7.44 (br, 2 Hp), 6.91 (br, 4 Hm), BPh 7.37
(m, 4 Ho), 7.16 (m, 2 Hp), 7.07 (m, 4 Hm), borole 5.22 (br, 3-/
4-H), 3.84 (br, 2-/5-H); the broad borole signals appear as
multiplets with N ) 5.2 Hz at 80 MHz. 1H NMR (500 MHz,
CD2Cl2, -80 °C): isomer 1 (50%), δ py 9.04 (m, 4 Ho), 7.62 (m,
2 Hp), 7.14 (m, 4 Hm), Ph 7.33 (m, 4 Ho), 7.08 (m, 2 Hp), 7.02
(m, 4 Hm), borole 4.93 (m, N ) 4.9 Hz, 3-/4-H), 3.55 (m, N )
4.9 Hz, 2-/5-H); isomer 2 (50%), δ py 8.53 (m, 4 Ho), 7.04 (m,
2 Hp), 6.48 (m, 4 Hm), BPh 7.28 (m, 4 Ho), 7.12 (m, 2 Hp), 7.02
(m, 4 Hm, as in isomer 1), borole 5.31 (m, 3-/4-H), 3.73 (m, N
) 5.2 Hz, 2-/5-H). 13C{1H} NMR (126 MHz, CDCl3): δ py
156.15 (Co), 136.04 (Cp), 123.97 (Cm), BPh 138.20 (br, Ci),
135.13 (Co), 127.96 (Cp), 127.11 (Cm), borole 88.48 (br, C-3,4),
70.82 (br, C-2,5). 13C{1H} NMR (126 MHz, CD2Cl2, -80 °C),
signals of Ph groups of isomers not resolved, δ BPh 137.74
(Ci), 134.65 (Co), 127.48 and 127.41 (Cp), 126.58 (Cm); isomer
1 (50%), py 156.23 (Co), 136.43 (Cp), 124.13 (Cm), borole 87.94
(C-3,4), 67.86 (C-2,5); isomer 2 (50%) py 155.25 (Co), 135.48
(Cp), 123.40 (Cm), borole 87.94 (C-3,4), 68.22 (C-2,5). At -40
°C the isomer ratio is 45/55; this allows us to decompose the
1H NMR spectrum into separate spectra of the isomers.
Protons in the ortho positions of the BPh and pyridine groups
are assigned by analogy; further assignments are based on
(1H,1H)-COSY and (1H,13C)-HETCOR spectra. 11B{1H} NMR
displays a rich reaction chemistry. On the basis of the
reactions described, we were able to explain the oxida-
tive degradation of the triple-decker complexes (µ-C4H4-
BR)[Rh(C4H4BR)]2 (1) in more detail.2
All the new compounds described here show lateral
symmetry. Internal rotation of the borole ring could
create less symmetric rotamers. Barriers to internal
rotation of borole rings have already been observed in
a number of cases.8,17 It may have been noted that it is
not always clear whether the observed lateral symmetry
reflects the preferential conformation of the complexes
or is an effective symmetry due to a low barrier.
We have emphasized that the heterocubanes 2 have
little tendency to react with unsaturated hydrocarbons.
However, they can be activated by halide abstraction.
This aspect will be presented in a later paper.18
Exp er im en ta l Section
Gen er a l P r oced u r es. Reactions were carried out under
an atmosphere of dinitrogen by means of conventional Schlenk
techniques. Hexane was distilled from potassium, CH2Cl2,
chlorobenzene, and pyridine were distilled from CaH2, and
Et2O was distilled from sodium benzophenone ketyl. Aceto-
nitrile was filtered through a column with activated alumina
and distilled under dinitrogen. Carbon monoxide was dried
with concentrated sulfuric acid.
NMR spectra were recorded on a Varian Unity 500 spec-
trometer (1H, 500 MHz; 13C{1H}, 125.7 MHz; 11B{1H}, 160.4
MHz; 31P{1H}, 202.4 MHz) and a Bruker WP-80 PFT (1H, 80
MHz) spectrometer. Chemical shifts are given in ppm; if not
stated otherwise, they were measured at ambient temperature
and are relative to internal TMS for 1H and 13C, relative to
BF3‚Et2O as an external reference for 11B, and relative to 85%
phosphoric acid as an external reference for 31P.
(CDCl3): δ 20. IR (KBr): ν(CdN) 1599 cm-1
.
Syn th esis of Rh I(bp y)(C4H4BP h ) (7). 2,2′-Bipyridine (68
mg, 0.436 mmol) was added to a solution of 4 (230 mg, 0.436
mmol) in THF (4 mL) to produce a yellow precipitate within
seconds. After the mixture was stirred for 30 min, the volatiles
were removed under vacuum. The residue was washed with
hexane (2 × 1 mL) and dried under vacuum to give 7 (225
mg, 98%) as a light yellow powder: darkens above 190 °C, no
mp < 250 °C; moderately soluble in CH2Cl2 and THF, insoluble
in toluene and ether. Anal. Calcd for C20H17BIN2Rh: C, 45.67;
H, 3.26; N, 5.33; I, 24.13. Found: C, 45.55; H, 3.34; N, 5.23;
I, 24.1.
Secondary ion mass spectra (SIMS) were recorded on a
Finnigan MAT-95 spectrometer. Elemental analyses and
determinations of molecular masses were performed by Mik-
roanalytisches Labor Pascher, D-53424 Remagen-Bandorf,
Germany. Melting points were determined in sealed capil-
laries on
a Bu¨chi 510 melting point apparatus and are
uncorrected.
Ad d ition of P yr id in e to 2a in a 2/1 Ra tio. Pyridine (65
mg, 0.82 mmol) was added to a solution of 2a (150 mg, 0.101
mmol) in CH2Cl2 (5 mL). The color changed from dark red to
orange within 30 s. After removal of the volatiles the oily
residue was triturated with hexane (5 mL). The orange
powder formed was collected, washed with hexane (2 × 2 mL),
and shortly dried under vacuum to give 4 (210 mg, 98%): mp
138 °C; in solution somewhat air-sensitive; slowly gives off
pyridine under vacuum; soluble in CH2Cl2, toluene, and ether;
insoluble in hexane. Anal. Calcd for C20H19BIN2Rh: C, 45.50;
H, 3.63; N, 5.31. Found: C, 45.03; H, 3.61; N, 5.23.
Data for 7 are as follows. 1H NMR (500 MHz, CD2Cl2): δ
9.01 (m, 2 6-/6′-H, bpy), 7.92 (m, 2 H), 7.74 (m, 2 H), 7.43 (m,
2 H), 7.21-7.09 (m, 2 H + 2 Hm + Hp), borole 5.68 (m, 3-/4-H),
4.00 (m, 2-/5-H). 13C{1H} NMR (126 MHz, CD2Cl2): δ bpy 155.50
(C-6,6′), 153.64 (C-2,2′), 137.01 (C-4,4′), 125.47 and 121.61 (C-
3,3′ and C5,5′), BPh 135.04 (Co), 128.06 (Cp), 127.40 (Cm), borole
91.81 [d, 1J (Rh-C) ) 8.6 Hz, C-3,4], 68.35 (br, C-2,5). 11B-
{1H} NMR (CDCl3): δ 21. IR (KBr): ν(CdN) 1599 cm-1
.
Data for 4 are as follows. 1H NMR (500 MHz, CD2Cl2, -80
Aceton itr ile Solu tion s of 2a : molar mass Mcalc 369.80 g
mol-1 for RhI(C4H4BPh); in acetonitrile Mobs (molarity (g/L))
391 (5.548), 445 (11.77), 464 g/mol (13.05). 1H NMR (500 MHz,
CD3CN): δ BPh 7.70 (m, 2 Ho), 7.34-7.30 (m, 2 Hm + Hp),
borole 5.42 (br, 3-/4-H), 4.06 (m, N ) 5.9 Hz, 2-/5-H). 1H NMR
(80 MHz) 5.43 (m, N ) 5.8 Hz, 3-/4-H), 4.07 (m, N ) 5.5 Hz,
2-/5-H). 13C{1H} NMR (126 MHz, CD3CN): δ BPh 136.44 (Co),
129.39 (Cp), 128.48 (Cm), borole 90.24 (br, C-3,4), 69.58 (br,
C-2,5). 11B{1H} NMR (CD3CN): δ 21.
P r ep a r a tion of 9 in CDCl3. A suspension of 2a (30 mg)
in CD2Cl2 or CDCl3 (1 mL) was stirred under CO (1 bar) for
10 min while a slow stream of dry CO was passed through
the flask. The yellow solution was then transferred into an
NMR tube that had been purged with dry CO.
Data for 9 are as follows. 1H NMR (500 MHz, CD2Cl2): δ
BPh 7.76 (m, 2 Ho), 7.43-7.36 (m, 2 Hm + Hp), borole 6.32 (m,
oC): δ py 8.49 (m, 4 Ho), 7.53 (m, 2 Hp), 6.97-7.02 (m, 4 Hm
+
Hp of BPh), BPh 7.22 (m, 2 Ho), 6.88 (m, 2 Hm), borole 5.69 (m,
3-/4-H), 3.92 (m, 2-/5-H). 13C{1H} NMR (126 MHz, CD2Cl2):
δ py 154.83 (br, Co), 136.91 (Cp), 124.80 (br, Cm), BPh 135.25
(Co), 128.12 (Cp), 127.37 (Cm), borole 90.60 (br, C-3,4), 67 (br,
C-2,5). 13C{1H} NMR (126 MHz, CD2Cl2, -80 °C): δ py 154.53
(Co), 136.57 (Cp), 124.41 (Cm), BPh 137.47 (Ci), 134.17 (Co),
1
127.31 (Cp), 126.57 (Cm), borole 90.89 [d, J (Rh-C) ) 8.3 Hz,
C-3,4], 65.65 (C-2,5). 11B{1H} NMR (CD2Cl2): δ 21. IR
(KBr): ν(CdN) 1599 cm-1
.
(17) (a) Herberich, G. E.; Negele, M.; Ohst, H. Chem. Ber. 1991, 124,
25. (b) Herberich, G. E.; Englert, U.; Hostalek, M.; Laven, R. Chem.
Ber. 1991, 124, 17.
(18) Herberich, G. E.; Eckenrath, H. J .; Englert, U. Manuscript in
preparation.

Borole Derivatives
Organometallics, Vol. 16, No. 22, 1997 4805
N ) 5.5 Hz, 3-/4-H), 4.81 (m, N ) 5.2 Hz, 2-/5-H). 13C{1H}
(m, N ) 9.9 Hz, Cm), 35.16 [t, 1J (P-C) ) 12.6 Hz, CH2], borole
96.14 [d, 1J (Rh-C) ) 6.6 Hz, C-3,4], 77.42 (br, C-2,5). 31P-
1
NMR (126 MHz, CD2Cl2): δ 182.82 [d, J (Rh-C) ) 66.9 Hz,
1
CO], BPh 135.85 (Co), 130.75 (Cp), 128.40 (Cm), borole 104.34
[d, 1J (Rh-C) ) 5.5 Hz, C-3,4], 80.07 (br, C-2,5). 11B{1H} NMR
(CDCl3): δ 25. IR (CDCl3): ν(CO)as ) 2108, ν(CO)s ) 2080
{1H} NMR (CDCl3): δ 16.76 (AA′XX′ system, “dt”, J (Rh-P)
2
3
2
) 153.2, J (P-P) ) 15.9, J (Rh-P) ) 1.4, | J (Rh-Rh)| < 0.2
Hz). 11B{1H} NMR (CDCl3): δ 21.
cm-1
.
Syn th esis of Rh I(d p p f)(C4H4BP h ) (13). A solution of 2a
(230 mg, 0.155 mmol) and Fe(C5H4PPPh2)2 (dppf; 345 mg,
Syn th esis of [Rh (µ-I)(CO)(C4H4BP h )]2 (10). A suspen-
sion of 2a (280 mg, 0.189 mmol) in CH2Cl2 (10 mL) was stirred
under CO (1 bar) for 10 min while a slow stream of dry CO
was passed through the reaction vessel. The volatiles were
then removed under vacuum. The foamy residue was tritu-
rated with hexane (5 mL) for 30 min, collected on a frit, washed
with hexane (2 mL), and dried under vacuum to give 10 (230
mg, 76%) as an orange powder: retains traces of solvent and
slowly decomposes under vacuum; mp 87 °C with partial
decomposition; in solution somewhat air-sensitive; rather
soluble in CH2Cl2, toluene, and acetone, moderately soluble
in ether, slightly soluble in hexane.
0.622 mmol) in CH
2Cl2 (10 mL) was stirred for 1 h. The
solution was concentrated to 5 mL, and hexane (25 mL) was
added to precipitate a light yellow powder, which was collected,
washed with hexane (2 × 5 mL), and dried under vacuum at
60 °C to give 13 (545 mg, 95%): no mp <250 °C; in solution
somewhat air-sensitive; soluble in CH
2Cl2, slightly soluble in
benzene and acetone, insoluble in ether and hexane. Recrys-
tallization from CH2Cl2 after layering with hexane gave
crystals with CH2Cl2. Anal. Calcd for C44H37BFeIP2Rh‚CH2-
Cl2: C, 53.56; H, 3.90. Found: C, 53.50; H, 3.92. SIMS
(NBA): positive ions, m/ z (I
rel) 797 (100, [Rh(dppf)(C4H4-
BPh)]+).
Data for 10 are as follows. 1H NMR (500 MHz, CD2Cl2): δ
BPh, signals of isomers not resolved, 7.64 (m, 4 Ho), 7.35-
7.29 (m, 4 Hm + 2 Hp); isomer 1 (55%), borole 5.86 (m, 3-/4-H),
4.56 (m, 2-/5-H); isomer 2 (45%), borole 5.82 (m, 3-/4-H), 4.56
(m, 2-/5-H). 13C{1H} NMR (126 MHz, CD2Cl2): δ BPh, signals
of isomers not resolved, 136.36 (Co), 135.3 (Ci), 130.02 (Cp),
Data for 13 are as follows. 1H NMR (500 MHz, CDCl3): δ
BPh 7.73 (m, 2 Ho), 7.34 (m, 2 Hm), 7.27 (m, Hp), PPh 7.58 (m,
4 Ho), 7.49 (m, 2 Hp), 7.23 (m, 4 Hm), PPh′ 7.47 (m, 4 Ho′), 7.39
(m, 4 Hm′), 7.28 (m, 2 Hp′), C5H4 5.65 (m, 2 5-H), 4.34 (m, 2
2-H), 4.31 (m, 2 4-H), 4.06 (m, 2 3-H), borole 4.71 (m, 3-/4-H),
3.59 (m, 2-/5-H). 13C{1H} NMR (126 MHz, CDCl3): δ BPh
136.95 (Co), 128.48 (Cp), 126.88 (Cm), PPh 138.50 (m, N ) 41.1
Hz, Ci or Ci′), 137.97 (m, N ) 41.1 Hz, Ci or Ci′), 134.73 (“t”, N
) 10.4 Hz, Co), 134.29 (“t”, N ) 11.5 Hz, Co′), 130.08 (Cp),
129.38 (Cp′), 127.63 (“t”, N ) 9.3 Hz, Cm′), 127.24 (“t”, N ) 9.9
Hz, Cm), C5H4 87.88 (m, N ) 48.8 Hz, C-1), 77.91 (“t”, N )
10.4 Hz, C-5), 73.56 (C-2), 71.74 (C-4), 67.95 (C-3), borole 96.14
[d, 1J (Rh-C) ) 7.1 Hz, C-3,4], 78.20 (br, C-2,5). For ferrocenes
1
127.89 (Cm); isomer 1 (55%), 187.30 [d, J (Rh-C) ) 71.3 Hz,
CO], borole 100.13 [d, 1J (Rh-C) ) 6.6 Hz, C-3,4], 77.40 (br,
1
C-2,5); isomer 2 (45%), 186.96 [d, J (Rh-C) ) 71.3 Hz, CO],
1
borole 99.96 [d, J (Rh-C) ) 7.1 Hz, C-3,4], 77.80 (br, C-2,5).
11B{1H} NMR (CD2Cl2): δ 25. IR (hexane): ν(CO) 2054, 2060,
2068 cm-1
.
Ad d ition of P P h 3 to 2a in a 2/1 Ra tio. A solution of 2a
(260 mg, 0.176 mmol) and PPh3 (369 mg, 1.406 mmol) in CH2-
Cl2 (10 mL) was stirred at ambient temperature for 30 min.
The orange solution was then concentrated to 5 mL and
layered with ether (20 mL). Orange needles formed slowly.
After 3 days the mother liquor was removed; the crystals were
washed with ether (2 × 5 mL) and dried under vacuum to give
11 (560 mg, 89%) as orange needles: mp 244 °C; in solution
somewhat air-sensitive; soluble in CH2Cl2, slightly soluble
in ether and acetone, insoluble in hexane. Anal. Calcd for
4
3J (H-H) ≈ 2 × J (H-H); the 1H{31P} NMR spectrum shows
the protons 2-/5-H as a multiplet of five lines with intensities
1/2/2/2/1 and the protons 3-/4-H as a multiplet of six lines with
intensities 1/1/2/2/1/1. Further assignments were made on the
basis of (1H,1H)-COSY, (1H,13C)-HETCOR, and NOE difference
spectra. 31P{1H} NMR (CD2Cl2): δ 33.06 [d, 1J (Rh-P) ) 148.3
Hz]. 11B{1H} NMR (CD2Cl2): δ 27.
Syn th esis of Rh I(n bd )(C4H4BP h ) (14). A solution of 2a
(260 mg, 0.176 mmol) and nbd (65 mg, 0.71 mmol) in CH2Cl2
(20 mL) was stirred for 1 h, then concentrated to 3 mL, and
cooled to -30 °C for 16 h. The orange-red crystals that formed
were collected, washed with ether (2 × 2 mL), and dried under
vacuum to give 14 (250 mg, 77%) as dark orange crystals: mp
167 °C dec; in solution somewhat air-sensitive; soluble in CH2-
Cl2 and acetone, moderately soluble in ether, slightly soluble
in hexane. Anal. Calcd for C17H17BIRh: C, 44.20; H, 3.71.
Found: C, 44.02; H, 3.73. SIMS (NBA): positive ions, m/ z
(Irel) 335 (100, [Rh(nbd)(C4H4BPh)]+).
C
46H39BIP2Rh: C, 61.77; H, 4.40. Found: C, 61.82; H, 4.38.
SIMS (NBA): positive ions, m/ z (Irel) 768 (85, [RhH(PPh3)2(C4H4-
BPh)]+), 505 (100, [Rh(PPh3)(C4H4BPh)]+).
Data for 11 are as follows. 1H NMR (500 MHz, CDCl3): δ
BPh 7.75 (m, 2 Ho), 7.36-7.30 (m, 2 Hm + Hp + 12 Ho of PPh3),
PPh3 7.28 (m, 6 Hp), 7.15 (m, 12 Hm), borole 4.61 (m, N ) 5.8
Hz, 3-/4-H), 3.70 (m, 2-/5-H). 13C{1H} NMR (126 MHz,
CDCl3): δ BPh 137.60 (Ci), 137.32 (Co), 128.65 (Cp), 126.92
(Cm), PPh3 135.51 (“t”, N ) 41.3 Hz, Ci), 134.40 (“t”, N ) 8.8
Hz, Co), 129.46 (Cp), 127.65 (“t”, N ) 8.3 Hz, Cm), borole 97.01
[d, 1J (Rh-C) ) 7.1 Hz, C-3,4], 79.71 (br, C-2,5). 31P{1H} NMR
(CDCl3): δ 20.29 [d, 1J (Rh-P) ) 142.6 Hz]. 11B{1H} NMR
(CDCl3) δ 27.
Data for 14 are as follows. 1H NMR (500 MHz, CDCl3): δ
BPh 7.88 (M, 2 Ho), 7.47-7.42 (m, Hp + 2 Hm), nbd 5.18 (m, 2
exo-CHd), 4.75 (m, 2 endo-CHd), 3.67 (m, exo-CH), 2.79 (m,
endo-CH), 1.13 (“t”, N ) 1.5 Hz, CH2), borole 5.73 (m, N ) 6.4
Hz, 3-/4-H), 4.65 (m, N ) 6.7 Hz, 2-/5-H). 13C{1H} NMR (126
MHz, CDCl3): δ BPh 135.19 (Co), 129.43 (Cp), 128.28 (Cm), nbd
78.35 [d, 1J (Rh-C) ) 5.4 Hz, exo-CHd], 63.41 [d, 3J (Rh-C) )
Syn th esis of Rh 2(µ-I)2(µ-d p p m )(C4H4BP h )2 (12). A solu-
tion of 2a (240 mg, 0.162 mmol) and CH2(PPh2)2 (dppm; 125
mg, 0.325 mmol) in CH2Cl2 (10 mL) was stirred for 1 h, then
concentrated to 3 mL, and cooled to -30 °C for 16 h. The
orange crystals that formed were collected, washed with
hexane (2 × 5 mL), and dried under vacuum to give 12 (300
mg, 82%); no mp <250 °C; in solution somewhat air-sensitive;
soluble in CH2Cl2, slightly soluble in ether and acetone,
insoluble in hexane. Anal. Calcd for C45H40B2I2P2Rh2: C,
48.09; H, 3.59. Found: C, 48.12; H, 3.61. SIMS (NBA):
positive ions, m/ z (Irel) 1124 (5, [Rh2I2(dppm)(C4H4BPh)2]+),
627 (53, [Rh(dppm)(C4H4BPh)]+), 307 (100, CH2P2Ph3+).
Data for 12 are as follows. 1H NMR (500 MHz, CDCl3): δ
BPh 7.62 (m, 4 Ho), 7.32-7.29 (m, 4 Hm + 2 Hp), PPh2 7.41
1
3.8 Hz, CH2], 59.93 [d, J (Rh-C) ) 6.0 Hz, endo-CH)], 50.17
(exo-CH), 44.49 [d, 2J (Rh-C) ) 2.2 Hz, endo-CH], borole 100.53
1
[d, J (Rh-C) ) 6.1 Hz, C-3,4], 89.05 (br, C-2,5). Atoms that
are closer to the borole ligand are designated as endo. 11B-
{1H} NMR (CDCl3) δ 22.
Syn th esis of Cp *Rh (µ-I)3Rh (C4H4BP h ) (15). A suspen-
13
sion of 2a (730 mg, 0.494 mmol) and [RhI2Cp*]2 (972 mg,
0.988 mmol) in CH2Cl2 (60 mL) was stirred at 20 °C for 6 h.
The volume was then reduced to 5 mL. The solid was collected
on a frit, washed with ether (2 × 5 mL), and dried under
vacuum to afford 15 (1.61 g, 95%) as blackish red crystals: no
mp up to 250 °C; moderately soluble in CH2Cl2 and CHCl3,
slightly soluble in toluene, insoluble in acetonitrile and ether.
Anal. Calcd for C20H24BI3Rh2: C, 27.88; H, 2.81. Found: C,
27.76; H. 2.73.
2
(m, 8 Ho), 7.24 (m, 4 Hp), 7.14 (m, 8 Hm), 4.44 [t, J (P-H) )
11.9 Hz, CH2], borole 4.61 (m, N ) 4.9 Hz, 3-/4-H), 3.94 (m, N
) 5.2 Hz, 2-/5-H). 13C{1H} NMR (126 MHz, CDCl3): δ BPh
136.75 (Co), 128.83 (Cp), 127.52 (Cm), PPh2 134.68 (virtual d,
N ) 47.2 Hz, Ci), 133.64 (m, N ) 11 Hz, Co), 130.42 (Cp), 128.26

4806 Organometallics, Vol. 16, No. 22, 1997
Herberich et al.
Ta ble 2. Cr ysta l Da ta , Da ta Collection
P a r a m eter s, a n d Con ver gen ce Resu lts for 15
temperature to give suitable crystals. The data collection was
performed on an ENRAF-Nonius CAD4 diffractometer with
Mo KR radiation (graphite monochromator). Crystal data,
data collection parameters, and convergence results are given
in Table 2. An empirical absorption correction19 based on
azimuthal scans was applied to the intensity data before
averaging over symmetry-equivalent reflections. The struc-
ture was solved by direct methods;20 refinement on structure
factors with the help of the SDP program system21 included
all non-hydrogen atoms with anisotropic displacement param-
eters, while hydrogen atoms were treated as riding in idealized
geometry (C-H ) 98 pm, Uiso(H) ) 1.3Uiso(C) for Cp*, one
groupwise refined isotropic displacement parameter for the
hydrogen atoms of the borole ring).22
formula
system
space group (No.)
a, pm
b, pm
c, pm
C20H24BI3Rh2
monoclinic
P21/m (11)
887.8(3)
1253.9(2)
1124.7(5)
110.61(3)
1.1718(6)
2
â, deg
V, nm3
Z
d
T, K
calc, g cm-3
2.442
203
53.03
71.073 (Mo KR)
26
0.24 × 0.24 × 0.10
empirical
0.703
0.999
2579
µ, cm-1
λ, pm (radiation)
θ
max, deg
cryst dimens, mm3
abs cor
Ack n ow led gm en t. This work was generously sup-
ported by the Fonds der Chemischen Industrie.
min transmissn
max transmissn
no. of reflns
Su p p or tin g In for m a tion Ava ila ble: Tables of fractional
coordinates of all atoms, anisotropic displacement parameters,
and bond distances and angles for 15 (5 pages). Ordering
information is given on any current masthead page.
no. of indep obs rflns, I > σ(I)
no. of vars
2016
132
Ra
Rw
0.032
b
0.035
0.9
residual electron dens, e nm-6
OM9704410
a
b
2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2
.
(19) North, A. C. T.; Phillips, D. C.; Mathews, F. S. Acta Crystallogr.
1968, A24, 351.
Data for 15 are as follows. 1H NMR (500 MHz, CDCl3): δ
BPh 7.77 (m, 2 Ho), 7.31-7.28 (m, 2 Hm + Hp), borole 5.43 (m,
3-/4-H), 4.28 (m, 2-/5-H), 1.90 (s, Cp*). 13C{1H} NMR (126
MHz, CDCl3): δ BPh 136.00 (Co), 128.58 (Cp), 127.34 (Cm), Cp*
95.82 [d, 1J (Rh-C) ) 8.2 Hz, C5Me5] and 10.93 (C5Me5), borole
87.54 [d, 1J (Rh-C) ) 9.3 Hz, C-3,4], 71.44 (C-2,5). 11B{1H}
NMR (CD2Cl2): δ 20.
(20) Sheldrick, G. M. SHELXS-86, Program for Crystal Structure
Solution; University of Go¨ttingen: Go¨ttingen, Germany, 1986.
(21) Frenz, B. A. ENRAF-Nonius SDP Version 5.0; ENRAF-Non-
ius: Delft, The Netherlands, 1989, and local programs.
(22) Further details of the crystal structure investigation are
available on request from the Fachinformationszentrum Karlsruhe,
Gesellschaft fu¨r wissenschaftlich-technische Information mbH, D-76344
Eggenstein-Leopoldshafen, Germany, on quoting the depository num-
ber CSD-407353 for 15, the names of the authors, and this journal
citation.
Cr ysta l Str u ctu r e Deter m in a tion of 15. A hot saturated
solution of 15 in chlorobenzene was slowly cooled to ambient