A novel reaction producing the rhodium(I) complexes with π-coordinated tetraphenylborate anion, (π-PhBPh3)-. X-ray study of [Rh(PPh3)2(π-PhBPh3)]

Article abstract of DOI:10.1016/j.jorganchem.2007.06.057

Treating the complexes [Rh(TFA)(PPh₃)₂], [Rh(HFA)(PPh₃)₂], and [Rh(TFA)(Cod)] (TFA - trifluoroacetylacetonate, HFA - hexafluoroacetylacetonate, Cod - 1,5 cyclooctadiene) with an excess of NaBPh₄ in acetonitrile yields the rhodium(I) complexes with coordinated [BPh₄]^- anion, [Rh(PPh₃)₂(π-PhBPh₃)] · 2MeCN (I) and [Rh(Cod)(π-PhBPh₃)] (II). The reactions present a new example of β-diketonate ligand replacement. The ¹H, ³¹P, and ¹¹B NMR spectra of I and II are discussed. [Rh(PPh₃)₂(π-PhBPh₃)] has been characterized by single crystal X-ray analysis.

Full text of DOI:10.1016/j.jorganchem.2007.06.057

Journal of Organometallic Chemistry 692 (2007) 4297–4302
www.elsevier.com/locate/jorganchem
A novel reaction producing the rhodium(I) complexes
with p-coordinated tetraphenylborate anion, (p-PhBPh3)ꢀ.
X-ray study of [Rh(PPh3)2(p-PhBPh3)]
a
a,
b
Elizaveta P. Shestakova , Yuri S. Varshavsky *, Viktor N. Khrustalev ,
a
Ivan S. Podkorytov
a
Institute of Chemistry, St. Petersburg State University, Petrodvorets, Universitetskii Pr., 26, 198504 St. Petersburg, Russia
b
Nesmeyanov Institute of Organoelement Compounds, Vavilova Str., 28, 117813 Moscow, Russia
Received 2 May 2007; received in revised form 21 June 2007; accepted 28 June 2007
Available online 4 July 2007
Abstract
Treating the complexes [Rh(TFA)(PPh3)2], [Rh(HFA)(PPh3)2], and [Rh(TFA)(Cod)] (TFA – trifluoroacetylacetonate, HFA – hexa-
fluoroacetylacetonate, Cod – 1,5 cyclooctadiene) with an excess of NaBPh4 in acetonitrile yields the rhodium(I) complexes with coordi-
nated [BPh4]ꢀ anion, [Rh(PPh3)2(p-PhBPh3)] Æ 2MeCN (I) and [Rh(Cod)(p-PhBPh3)] (II). The reactions present a new example of
1
b-diketonate ligand replacement. The H, 31P, and 11B NMR spectra of I and II are discussed. [Rh(PPh3)2(p-PhBPh3)] has been char-
acterized by single crystal X-ray analysis.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Rhodium; Tetraphenylborate coordination; 1H, 31P, 11B NMR; X-ray
1. Introduction
acetonate, Cod – 1,5 cyclooctadiene) with an excess of
NaBPh4 in acetonitrile, the known complexes with
coordinated phenyl ring of anion [BPh4]ꢀ, [Rh(PPh3)2-
(p-PhBPh3)] and [Rh(Cod)(p-PhBPh3)] [2], were formed.
Although rhodium complexes of this type are well docu-
mented [2–9] and widely studied in organic catalysis
[9–14], an uncommon way of their formation arrested
our attention. In the chemistry of [Rh(b-diket)(L)2] com-
plexes, a plethora of ligand L (CO, phosphines, arsines,
olefins) mutual substitutions is known, whereas the exam-
ples of b-diketonate ligand replacement are limited with
several reactions of bidentate r-donors, such as other
b-diketonate ligands, o-phenantroline, 2,20-bipyridyl and
Tetraphenylborate anion has been widely used as a
counterion for the isolation of cationic species from solution.
Recently, we succeeded in the isolation and characteriza-
tion of the cationic complexes cis-[Rh(b-diket)(PPh3)2-
(CH3)(MeCN)][BPh4] (b-diket is acetylacetonate or
benzoylacetonate) [1], which were obtained by CH3I oxida-
tive addition to the rhodium(I) complexes [Rh(b-diket)-
(PPh3)2] in acetonitrile in the presence of NaBPh4.
However, in attempting to prepare according to the same
procedure the cationic complexes containing b-diketonate
ligand with at least one CF3 group, we recognized, that,
immediately after mixing of the rhodium(I) complexes
[Rh(TFA)(PPh3)2], [Rh(HFA)(PPh3)2], or [Rh(TFA)(Cod)],
(TFA – trifluoroacetylacetonate, HFA – hexafluoroacetyl-
their
derivatives,
or bis(diphenylphosphino)ethane
[15–18]. Thus, the ability of the phenyl group of the
[BPh4]ꢀ anion to replace b-diketonate ligand forming com-
plexes of the p-arene type seems to be fairly unexpected.
In this paper, we report a new reaction of b-diketonate
ligand replacement in rhodium(I) complexes with tetraphe-
*
Corresponding author. Tel.: +7 812 428 4710; fax: +7 812 2743445.
E-mail address: yurel@peterlink.ru (Y.S. Varshavsky).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.06.057

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E.P. Shestakova et al. / Journal of Organometallic Chemistry 692 (2007) 4297–4302
1
3
nylborate anion in acetonitrile, H, 31P{1H}, and 11B{1H}
NMR spectra of [Rh(PPh3)2(p-PhBPh3)] Æ 2MeCN (I) and
[Rh(Cod)(p-PhBPh3)] (II), and the X-ray structure of
[Rh(PPh3)2(p-PhBPh3)].
7.08 (para-, triplet, J = 7.3 Hz, 3H). Resonances of coor-
dinated phenyl group are clearly resolved and located at
3
d (ppm) 6.76 (para-, triplet, J ꢁ 6 Hz, 1H), 6.63 (ortho-,
3
3
doublet, J ꢁ 6 Hz, 2H), 6.08 ppm (meta-, triplet, J ꢁ 6
Hz, 2H). Signals at d 4.23, 2.32, 1.99, and 1.96 ppm (poorly
1
2. Results and discussion
resolved multiplets) belong to Cod ligand. Similar Cod H
NMR patterns were observed in the spectra of initial
[Rh(TFA)(Cod)] (d 4.19, 2.51–2.47, 1.88, and 1.85 ppm)
and other complexes with Cod ligand [15,19,20]. We failed
to find in the literature the 1H NMR spectrum of
Stirring of the [Rh(TFA)(PPh3)2] or [Rh(HFA)(PPh3)2]
suspension with an excess of NaBPh4 in acetonitrile at
room temperature results in fast formation of yellow
microcrystalline solid. The product was isolated by filtra-
[Rh(Cod)(p-PhBPh3)],
but
the
related
complex
1
tion and characterized by elemental analysis and H and
[Rh(NBD)(p-PhBPh3)] [2] has close values of the spectral
parameters.
31P{1H} NMR spectra as [Rh(PPh3)2(p-PhBPh3)] Æ 2MeCN
1
(I). The H NMR spectrum of I (in CDCl3) contains the
The reported reactions run fast and with high yield when
b-diketonate ligand contains at least one CF3 group. In the
case of the acetylacetonate complex the reaction proceeds
to only a small extent. In our experiments, only ꢁ30% of
starting [Rh(Acac)(PPh3)2] was converted after 3.5 h
stirring.
well resolved signals from coordinated phenyl group at d
3
5.62 ppm (ortho-, doublet, J ꢁ 6 Hz, 2H) and 4.68 ppm
3
(meta-, triplet, J ꢁ 6 Hz, 2H); a triplet from para-proton
is masked by the assemblage of signals from PPh3 and
non-coordinated phenyl groups (BPh3) in the region d
6.9–7.5 ppm. A sharp singlet at d 2.02 ppm (6H) belongs
to free acetonitrile, 2MeCN per Rh, which passes into solu-
tion upon dissolving the solvated complex. The 31P{1H}
NMR spectrum of I (in CDCl3) shows one sharp doublet
It is worth noting that we observed weak signals corre-
sponding to [Rh(PPh3)2(p-PhBPh3)] in the 1H and 31P
NMR spectra of cis-[Rh(b-diket)(PPh3)2(CH3)(MeCN)]-
[BPh4] and trans-[Rh(b-diket)(PPh3)2(COCH3)][BPh4]
reported previously [21] when their solutions (in CH2Cl2
or CHCl3) were kept under an inert atmosphere for days.
Along with a few known complexes [Rh(L)2(p-PhBPh3)]
with one coordinated phenyl ring of anion [BPh4]ꢀ, exam-
ples of a tetraphenylborate anion bridging two and three
rhodium metal centers are documented in the literature,
namely the cationic complexes {[(C2H4)2Rh(p-Ph)]2BPh2}-
(O3SCF3) and {[(C2H4)2Rh(p-Ph)]3BPh)}(O3SCF3)2 [8]. In
order to examine whether I and II are able to form related
dirhodium cationic derivatives, we stirred the mixtures
{[Rh(PPh3)2(p-PhBPh3)] Æ 2MeCN + [Rh(TFA)(PPh3)2]}
and {[Rh(Cod)(p-PhBPh3)] + [Rh(TFA)(Cod)]} at room
temperature in the mixed methanol/toluene solvent. The
1H and 31P{1H} NMR spectra of the reaction mixtures
showed that in both cases the starting compounds
remained unchanged, and any indication of the presence
of dirhodium complexes with bridging tetraphenylborate
anion was absent. However, after stirring the mixture
{[Rh(PPh3)2(p-PhBPh3)] Æ 2MeCN + [Rh(TFA)(Cod)]}
under the same conditions, the complexes [Rh(TFA)-
(PPh3)2] and [Rh(Cod)(p-PhBPh3)] were distinctively
detected in the reaction mixture by 1H and 31P{1H}
NMR. We believe that formation of these complexes in this
case proceeded via a dirhodium intermediate contained
[Rh(PPh3)2Rh(Cod)((p-Ph)2BPh2)]+ cationic unit with
TFAꢀ as a counterion. Our assumption is based on the
results of authors [8,12] who reported the first example of
coordinated tetraphenylborate ion transfer between two
metal centers.
from
2
equivalent triphenylphosphine ligands (d
44.2 ppm, 1J(PRh) 207.1 Hz). The related complexes,
[Rh(diphos)(p-PhBPh3)]
[11]
and
[Rh{Fe(g5-
1
C5H4PPh2)2}(p-PhBPh3)] [7], have close values of the H
and 31P NMR parameters. The unsolvated complex
[Rh(PPh3)2(p-PhBPh3)] described previously [2] was pre-
pared as red-brown crystals whose low solubility prevented
recording of NMR spectra. We succeeded in recording
NMR spectra of the chloroform solution of the red-brown
form of [Rh(PPh3)2(p-PhBPh3)] obtained by recrystalliza-
tion of I from methylene chloride/diethyl ether solution.
1
Its H spectrum coincided with the spectrum of I except
the signal at d 2.02 ppm (free MeCN) was absent.
As already noted, formation of I proceeds fast. In
20 min, at room temperature, its yield amounts to about
98%. Additional stirring of the suspension results in
decrease of the yield (ꢁ50% after 50 min). We believe that
coordinating solvent MeCN gradually displaces the coordi-
nated tetraphenylborate anion, and this reaction is respon-
sible for the yield decreasing. Examples of coordinated
[BPh4]ꢀ replacement by coordinating solvents, such as
MeCN, DMF, THF, were described in literature
[8,11,12]. In the solid state, I is stable for a long time even
in the presence of air.
Stirring of [Rh(TFA)(Cod)] with an excess of NaBPh4 in
acetonitrile at room temperature results in the formation of
pale yellow [Rh(Cod)(p-PhBPh3)] (II). The complex was
characterized by elemental analysis and, despite its low sol-
1
ubility, we recorded its H NMR spectrum in CDCl3. In
this spectrum, signals from coordinated and three uncoor-
dinated phenyl groups of tetraphenylborate ion are sepa-
rated rather well. The signals from uncoordinated phenyl
groups (BPh3) appear at d (ppm) 7.42 (ortho-, doublet,
3J = 7.3 Hz, 6H); 7.20 (meta-, triplet, 3J = 7.3 Hz, 6H),
The 11B{1H} NMR spectra of I and II (in THF) show
singlets at d ꢀ7.50 and ꢀ7.60 ppm, respectively. The sig-
nals of the complexes are up-field shifted (Dd @ ꢀ1 ppm)
with respect to the 11B resonance of NaBPh4 (ꢀ6.50 ppm
in THF), and are significantly broadened (w1/2 = 22 Hz

E.P. Shestakova et al. / Journal of Organometallic Chemistry 692 (2007) 4297–4302
4299
(I), 15 Hz (II) vs. 1 Hz for NaBPh4). These findings are con-
sistent with the results published earlier [11]. The appear-
ance of a very week singlet at ꢀ6.50 ppm in the 11B
spectrum of I points to the partial detachment of [BPh4]ꢀ
anion under our experimental conditions.
Crystal of the complex [Rh(PPh3)2(p-PhBPh3)] for the
X-ray investigation was obtained by recrystallization of
the solvated complex, [Rh(PPh3)2(p-PhBPh3)] Æ 2MeCN
(I), from methylene chloride/diethyl ether solution. The
molecular structure of the complex is shown in Fig. 1.
Selected bond lengths and angles are listed in Table 1.
As shown in Fig. 1, the rhodium atom is coordinated to
the phosphorus atoms of two PPh3 ligands and to one of
the phenyl rings of a tetraphenylborate anion. In its
substantial structural patterns, [Rh(PPh3)2(p-PhBPh3)] is
closely similar to other rhodium complexes containing
(p-PhBPh3)ꢀ ligand [3,4,6–8,22]. As in other studied struc-
tures, the coordinated phenyl ring markedly deviates from
planarity, resulting in a boat conformation. Four carbon
atoms, C(38), C(39), C(41), C(42), form a quasi planar
˚
(within 0.01 A) rectangle R, whereas, ipso-C(37) and
para-C(40), are displaced from this plane pointing from
the metal. The dihedral angles between the R plane and
two planes deflected from the metal atom are 8.6ꢁ (ipso-car-
bon) and 5.5ꢁ (para-carbon). The Rh distance to the geo-
˚
metrical centroid of the rectangle R is 1.842 A.
The structural features of the first described com-
plex with coordinated tetraphenylborate anion, [Rh-
(P(OCH3)3)2(p-PhBPh3)], prompted authors [3,22] to
consider them as a quasi tetracoordinate rhodium(I) com-
plex with midpoints X and Y of two C–C bonds at the
opposite edges of R as ‘‘olefin like’’ ligands. This interpre-
tation has then been applied to the cationic toluene com-
plex [Rh(P(OPh)3)2(p-PhCH3)][ClO4] [23] which turned
out very close in its geometry to the complexes of rho-
dium(I) with (p-PhBPh3)ꢀ ligand. We believe that the
structure of [Rh(PPh3)2(p-PhBPh3)] can be analogously
treated from this viewpoint. Some geometrical parameters
of these three structures are collected in Table 2.
The similarity between complexes containing isoelec-
tronic ligands (p-PhBPh3)ꢀ and (p-PhCH3) suggests that
the boat like, partially ‘‘de-aromatized’’, conformation of
the coordinated phenyl ring is caused by intramolecular
bonding effects, primarily by electronic demand of metal
center which tends to achieve 16e configuration, the most
typical one for rhodium(I) complexes. However, it should
be emphasized, that coordination of rhodium atom in these
complexes is far from the ideal tetragonal planar mode.
For instance, in the complex reported here, the triangles
P(1)Rh(P(2) and XRhY are tilted at an angle of 7.2ꢁ to
each other (X and Y are midpoints of C(38)–C(39) and
C(41)–C(42) bonds, respectively, Fig. 1). The ‘‘coordina-
tion quadrangle’’ P(1)P(2)XY in these complexes is rather
a trapezium due to low value of XRhY angle (Table 2).
The 1H NMR data reported above may be considered in
terms of the preceding discussion on the ligand L electronic
effects in [Rh(L)2(p-PhBPh3)] complexes [8,9,11]. The data
collected in Table 3 show that proton chemical shifts of the
Fig. 1. The structure of [Rh(PPh3)2(p-PhBPh3)] (50% probability
ellipsoids).
Table 1
˚
Selected bond lengths (A) and angles (ꢁ) for the complex [Rh(PPh3)2
(p-PhBPh3)] with estimated standard deviations in parentheses
˚
Bond lengths (A)
Bond angles (ꢁ)
Rh–P(1)
Rh–P(2)
2.2458(10)
2.2731(10)
2.499(4)
2.294(4)
2.267(4)
2.340(4)
2.300(4)
2.364(4)
P(1) Rh(1) P(2)
95.15(4)
Rh–C(37)
Rh–C(38)
Rh–C(39)
Rh–C(40)
Rh–C(41)
Rh–C(42)
P(1) Rh(1) C(38)
P(1) Rh(1) C(39)
98.36(10)
95.27(10)
P(2) Rh(1) C(41)
P(2) Rh(1) C(42)
98.18(10)
103.25(10)
Table 2
Some geometrical parameters of the complexes [Rh(PPh3)2(p-PhBPh3)], [Rh(P(OCH3)3)2(p-PhBPh3)] [22], and [Rh(p-PhCH3)(P(OPh)3)2][ClO4] [23]
˚
Compound
Distances (A)
Angles (ꢁ)
XRhY
Rh-X
Rh-Y
Rh-P(1)
Rh-P(2)
P(1)RhP(2)
[Rh(PPh3)2(p-PhBPh3)]
2.169
2.19
2.194
2.222
2.20
2.202
2.246
2.19
2.180
2.273
2.18
2.188
65.9
66.6
64.1
95.15
90.4
90.07
[Rh(P(OCH3)3)2(p-PhBPh3)]
[Rh(P(OPh)3)2(p-PhCH3)]+
X and Y are midpoints of two C–C bonds at the opposite edges of a quasi planar rectangle R; in the case of [Rh(PPh3)2(p-PhBPh3)], R is the rectangle,
formed by four carbon atoms, C(38), C(39), C(41), C(42) (Fig. 1).

4300
E.P. Shestakova et al. / Journal of Organometallic Chemistry 692 (2007) 4297–4302
Table 3
1H NMR chemical shifts (d, ppm) for coordinated (p-Ph) and non-coordinated (BPh3) phenyl rings of tetraphenylborate anion in the complexes
[Rh(L)2(p-PhBPh3)] and free anion [BPh4]ꢀ in NaBPh4
Compound
Solvent
ortho-H
meta-H
para-H
Ref.
Coordinated phenyl ring
[Rh(dppf)(p-PhBPh3)]a
[Rh(PPh3)2(p-PhBPh3)]
[Rh(dppb)(p-PhBPh3)]b
[Rh(diphos)(p-PhBPh3)]
CDCl3
CDCl3
CD2Cl2
CDCl3
CD2Cl2
CD2Cl2
CDCl3
CD2Cl2
5.76
5.62
5.63
6.34
6.23
5.96
6.48
6.44
6.47
6.63
6.70
4.43
4.68
4.95
5.42
5.47
5.59
5.84
6.07
6.07
6.08
6.31
Masked
Masked
6.81
6.22
6.32
Masked
6.82
6.98
6.62
6.76
[7]
This work
[9]
[11]
[11]
[8]
[4]
[8]
[2]
[Rh(bpy)(p-PhBPh3)]
[Rh[P(OCH3)3]2(p-PhBPh3)]
[Rh(C2H4)2(p-PhBPh3)]
[Rh(NBD)(p-PhBPh3)]
[Rh(Cod)(p-PhBPh3)]
1,2-Dichloroethane
CDCl3
1,2-Dichloroethane
This work
[2]
[Rh(1,3-butadien)(p-PhBPh3)]
6.60
Non-coordinated phenyl rings
[Rh(diphos)(p-PhBPh3)]
[Rh(C2H4)2(p-PhBPh3)]
[Rh(Cod)(p-PhBPh3)]
Na+[BPh4]ꢀ
CDCl3
CD2Cl2
CDCl3
CD3CN
7.15
7.32
7.42
7.30
6.95
7.14
7.20
7.02
6.92
7.02
7.08
6.87
[11]
[8]
This work
This work
a
dppf = Fe(g5-C5H4PPh2)2.
dppb = 1,4-bis(diphenylphosphino)butan.
b
coordinated phenyl in the spectra of both complexes, I and
II, fall into the ranges of values for their close analogs.
It may be seen that the up-field shifts of proton reso-
nances of the coordinated phenyl group are much more sig-
nificant in [Rh(L)2(p-PhBPh3)] complexes with the
strongest r-donor ligands L, phosphines and bipyridyl,
whereas the lesser up-field shifts are associated with higher
p-acceptor and poorer r-donor abilities of L, olefins and
phosphite. Notice that the electron donating groups, for
instance in substituted aromatics, affect d1H values in a
similar manner. The presented data are consistent with
the previous idea [8,9] that the up-field shift of proton res-
onances upon phenyl coordination is due to the electron
density transfer from ligands L to the coordinated phenyl
ring through the metal center. The proton chemical shifts
of non-coordinated phenyls (BPh3) may imply some redis-
tribution of electron density between coordinated and non-
coordinated phenyl rings. It should be remarked that the
chemical shifts of meta-protons (in the case of I, protons
at C(39) and C(41)) are particularly sensitive to the
r-donor ability of ligands L, whereas the chemical shifts
of para-protons (at C(40)) are poorly influenced by it. This
difference may reflect the unequal role of corresponding
carbon atoms in phenyl to rhodium coordination.
The 1H chemical shifts were measured with solvent
(CDCl3) residual proton as internal standard,
d1H = 7.28 ppm. The 31P chemical shifts were measured
with 85% phosphoric acid as external standard,
d31P = 0.0 ppm. The 11B chemical shifts were measured
with BF3 Æ (C2H5)2O as external standard, d11B = 0.0 ppm.
3.1. Preparation of [Rh(PPh3)2(p-PhBPh3)] Æ 2MeCN (I)
Mixture of [Rh(TFA)(PPh3)2] (0.10 g, 0.13 mmol) and
NaBPh4 (0.13 g, 0.38 mmol) suspended in acetonitrile
(1 ml) was stirred for 20 min at 20 ꢁC. A yellow solid was
isolated by filtration, washed with acetonitrile and dried
in vacuo. Yield: 0.13 g (97.8%). Anal. Calc. for
C64H56BN2P2Rh: C, 74.72; H 5.49; N, 2.72. Found: C,
74.86; H, 5.49; N, 2.90%. The reaction with starting
[Rh(HFA)(PPh3)2] under the same conditions gave the
identical product. Anal. Found: C, 74.94; H, 5.63; N,
2.32%.
3.2. Preparation of [Rh(Cod)(p-PhBPh3)] (II)
Mixture of [Rh(TFA)(Cod)] (0.089 g, 0.24 mmol) and
NaBPh4 (0.26 g, 0.76 mmol) suspended in acetonitrile
(1 ml) was stirred for 1 h at 20 ꢁC. A pale yellow solid
was isolated by filtration, washed with acetonitrile and hex-
ane, and dried in vacuo. Yield: 0.096 g (74.1%). Anal. Calc.
for C32H32BRh: C, 72.46; H 6.09. Found: C, 72.11; H,
5.96%.
3. Experimental
All operations were performed under an atmosphere of
dry argon. The rhodium complexes [Rh(Acac)(PPh3)2],
[Rh(TFA)(Cod)], [Rh(TFA)(PPh3)2], and [Rh(HFA)-
(PPh3)2] were synthesized by published procedures
[24,25]. Elemental analyses were performed with a Hew-
3.3. The reaction between [Rh(Cod)(p-PhBPh3)](II) and
[Rh(TFA)(Cod)]
lett–Packard
185
microanalyzer.
NMR
spectra
1
(300.1 MHz H, 96.3 MHz 11B {1H}, and 121.5 MHz 31P
Methanol (3 ml) and toluene (1 ml) were added to a mix-
ture of [Rh(Cod)(p-PhBPh3)] (0.13 g, 0.24 mmol) and
{1H}) were measured on a Bruker DPX-300 spectrometer.

E.P. Shestakova et al. / Journal of Organometallic Chemistry 692 (2007) 4297–4302
4301
[Rh(TFA)(Cod)] (0.089 g, 0.24 mmol). The mixture was
1.47 (s, C–CH3) ([Rh(TFA)(PPh3)2]), 5.62 (d, o-H,
3
stirred for 2 h at 20 ꢁC. A yellow solid was removed by fil-
3J ꢁ 6 Hz), 4.68 (t, m-H, J ꢁ 6 Hz) (starting I). The sol-
1
tration, dried in vacuo (weight 0.13 g). H NMR (CDCl3):
vents were removed from dark-orange filtrate under
reduced pressure. NMR spectra of the residue (CDCl3):
31P{1H}: d 30.3 (s) (Ph3PO); 1H: d 7.8–7.0 (m, C6H5,
Ph3PO), 5.75 (s, CH), 4.19 (s), 2.5, 1.88–1.85 (poorly
resolved multiplets) (Cod), 2.09 (s, C–CH3) (starting
[Rh(TFA)(Cod)]).
3
d 7.8–7.0 (m, C6H5), 6.76 (t, p-H, J ꢁ 6 Hz), 6.63 (d, o-H,
3
3J ꢁ 6 Hz), 6.08 (t, m-H, J ꢁ 6 Hz), 4.23 (s), 2.32, 1.99,
1.96 (poorly resolved multiplets) (starting II). The solvents
were removed from filtrate under reduced pressure. 1H
NMR (CDCl3): d 5.75 (s, CH), 4.19 (s), 2.5, 1.88–1.85
(poorly resolved multiplets) (Cod), 2.09 (s, C–CH3) (start-
ing [Rh(TFA)(Cod)]).
3.5. X-ray structure determinations
3.4. The reaction between [Rh(PPh3)2
(p-PhBPh3)] Æ 2MeCN (I) and [Rh(TFA)(Cod)]
Data were collected on a Bruker three-circle diffractom-
eter equipped with an X8-APEX-II CCD detector and cor-
rected for absorption [26]. For details see Table 4.
The structure was solved by direct methods and refined
by full-matrix least-squares technique on F2 with aniso-
tropic thermal parameters for non-hydrogen atoms. The
hydrogen atoms were placed in calculated positions and
refined in the riding model with fixed thermal parameters.
All calculations were carried out by use of the SHELXTL pro-
gram (PC Version 6.12) [27].
Methanol (1 ml) and toluene (1 ml) were added to a mix-
ture of [Rh(PPh3)2(p-PhBPh3)] Æ 2MeCN (I) (0.08 g,
0.08 mmol) and [Rh(TFA)(Cod)] (0.03 g, 0.08 mmol). The
mixture was stirred for 2 h at 20 ꢁC. Yellow-orange solid
was isolated by filtration, dried in vacuo (weight 0.047 g).
31P{1H} NMR (CDCl3): d 57.9 (dd, 1J(PRh) 198.1 Hz,
2J(PP) 56.5 Hz), d 54.0 (dd, 1J(PRh) 193.3 Hz, 2J(PP)
1
56.5 Hz) ([Rh(TFA)(PPh3)2]); 44.2 (d, J(PRh) 207.1 Hz)
1
(starting I), 30.3(s) Ph3PO. H NMR (CDCl3): d 7.8–7.0
Acknowledgement
3
(group of signals, C6H5), 6.76 (t, p-H, J ꢁ 6 Hz), 6.63 (d,
3
3
o-H, J ꢁ 6 Hz), 6.08 (t, m-H, J ꢁ 6 Hz), 4.23 (s), 2.32,
1.99, 1.96 (poorly resolved multiplets) (II), 5.66 (s, CH),
Financial support from the Russian Foundation for Ba-
sic Research (Project No. 05-03-32463) is gratefully
acknowledged.
Appendix A. Supplementary material
Table 4
Crystallographic data for [Rh(PPh3)2(p-PhBPh3)]
CCDC 638558 contains the supplementary crystallo-
graphic data for [Rh(PPh3)2(p-PhBPh3)]. These data can
be obtained free of charge via http://www.ccdc.cam.
ac.uk/conts/retrieving.html, or from the Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2007.06.057.
Compound
[Rh(PPh3)2(p-PhBPh3)]
C60H50BP2Rh
946.66
100.0(2)
0.30 · 0.25 · 0.20
Triclinic
Empirical formula
Fw
Temperature (K)
Crystal size (mm)
Crystal system
Space group
ꢀ
P1
˚
a (A)
9.9184(7)
13.7097(10)
18.3991(13)
85.437(5)
75.271(5)
70.971(5)
2287.4(3)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
References
3
˚
V (A )
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F(000)
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980
0.484
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h Range (ꢁ)
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ꢀ126h 6 12
ꢀ17 6 k 6 17
ꢀ23 6 l 6 23
23625
9811 (0.0440)
8221
0.0515; 0.1174
0.0640; 0.1227
9811/0/577
1.038
Number of reflections collected
Number of unique reflections (Rint
Number of reflections with I > 2r(I)
R1; wR2 (I > 2r(I))
R1; wR2 (all data)
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ꢀ3
˚
)
0.717/ꢀ0.778
Absolute correlations Tmax; Tmin
0.909; 0.868

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