Cationic derivatives of RhCl[P(η2-C7H7)3]. An intramolecular Diels - Alder rearrangement in the tripodal ligand tri(1-cyclohepta-2,4,6-trienyl)phosphane, P(C7H7)3

Article abstract of DOI:10.1016/S0022-328X(00)00750-6

Starting from the chloro-rhodium(I) complex, RhCl[P(η²-C₇H₇)₃] (1), several salts such as {Rh[P(η²-C₇H₇)₃]} ⁺X^- (X^- = BF^-₄ (2), CF₃COO^- (5), CF₃SO^-₃ (7)) and {Rh(L-L)[P(η²-C₇H₇)₂(C ₇H₇)]}⁺BF^-₄ (L-L = 1,10-phenanthroline (4a) or 2,2′-bipyridine (4b)) have been prepared. The reaction of 1 with trimethylsilyl trifluoromethane sulfonate, CF₃SO₂-OSiMe₃, has been found to involve a stereospecific 4:2 Diels-Alder cycloaddition between two coordinated cyclohepta-2,4,6-trienyl substituents to give a dinuclear rhodium(III) complex, {Rh₂[P(η³-C₁₄H₁₅)(C ₇H₇)]₂(η-Cl)₃} ⁺(CF₃SO^-₃) (8), which has been characterized by NMR spectroscopy and an X-ray structure analysis.

Full text of DOI:10.1016/S0022-328X(00)00750-6

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 621 (2001) 166–172
Cationic derivatives of RhCl[P(h2-C7H7)3]. An intramolecular
Diels–Alder rearrangement in the tripodal ligand
tri(1-cyclohepta-2,4,6-trienyl)phosphane, P(C7H7)3
Max Herberhold *, Stefan Eibl, Wolfgang Milius
Laboratorium fu¨r Anorganische Chemie der Uni6ersita¨t Bayreuth, Postfach 10 12 51, D-95440 Bayreuth, Germany
Received 16 August 2000; accepted 15 September 2000
Dedicated to Professor Henri Brunner on the occasion of his 65th birthday
Abstract
Starting from the chloro-rhodium(I) complex, RhCl[P(h2-C7H7)3] (1), several salts such as {Rh[P(h2-C7H7)3]}+X− (X−=BF−4
(2), CF3COO− (5), CF3SO−3 (7)) and {Rh(LꢀL)[P(h2-C7H7)2(C7H7)]}+BF−4 (LꢀL=1,10-phenanthroline (4a) or 2,2’-bipyridine
(4b)) have been prepared. The reaction of 1 with trimethylsilyl trifluoromethane sulfonate, CF3SO2ꢀOSiMe3, has been found to
involve a stereospecific 4:2 Diels–Alder cycloaddition between two coordinated cyclohepta-2,4,6-trienyl substituents to give a
dinuclear rhodium(III) complex, {Rh2[P(h3-C14H15)(C7H7)]2(m-Cl)3}+(CF3SO3−) (8), which has been characterized by NMR
spectroscopy and an X-ray structure analysis. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Rhodium; Olefinic phosphane complexes; Tripodal ligands; Diels–Alder cycloaddition; NMR; Crystal structure
1. Introduction
2. Results and discussion
The rhodium(I) complex RhCl[P(h2-C7H7)3] (1)
which contains the metal as part of a ligand cage [1] is
a versatile educt [2,3]. Displacement of the chloro lig-
and by anions such as acetylacetonate, allyl, cyclopen-
tadienyl [2] or tris(3,5-dimethyl-1-pyrazolyl)borate
(Tp*) [3] leads to neutral derivatives in which one, two
or all three cyclohepta-2,4,6-trienyl substituents may be
displaced from rhodium(I), although phosphorus al-
ways remains coordinated. The reversible decomplexa-
tion of olefinic ligands — combined with opening of a
free coordination site at the metal — can be an impor-
tant step in metal-catalyzed processes.
Abstraction of the chloro ligand from RhCl[P(h2-
C7H7)3] (1) by AgBF4 in acetonitrile solution formally
leads to a salt, {Rh[P(h2-C7H7)3]}+BF4−, the cation of
which is apparently stabilized in the solution by the
donor solvent [1]. This can be deduced from the 31P-
NMR data of the salts {Rh[P(h2-C7H7)3]}+X− in
CD3CN solution, where the same chemical shift (l(31P)
330 ppm) and the same coupling constant (1J(Rh,P)
188 Hz) are observed, irrespective of the nature of the
anion (X−=BF−4 (2), CF3COO− (5) or CF3SO−3 (7)).
It is assumed that in all three cases an acetonitrile
ligand occupies the position trans to phosphorus in
solution, and that the cage formed by the tetradentate
P(C7H7)3 ligand is retained in the cations. The trigonal
pyramidal structure of the {Rh[P(h2-C7H7)3]}+ cation
in the solid is similar to the molecular structures found
in the cations {Ni[P(CH2CH2PPh2)3]}+ [4] and
{Co[N(CH2CH2PPh2)3]}+ [5]. In CD2Cl2 solution the
chemical shifts (l(31P) 314 ppm) observed for 5 and 7
are again very similar, although the coupling constants
J(Rh,P) are different (Table 1, Scheme 1).
* Corresponding author. Tel.: +49-921-552540; fax: +49-921-
552157.
E-mail address: max.herberhold@uni-bayreuth.de (M. Herberhold).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00750-6

M. Herberhold et al. / Journal of Organometallic Chemistry 621 (2001) 166–172
167
Table 1
analogue (1), the tetradentate ligand P(C7H7)3 forms a
cage; and the three coordinated olefinic bonds
(C(4)ꢀC(5), C(11)ꢀC(12) and C(18)ꢀC(19); d(CꢁC)
140.4(6) pm av., angle CꢀRhꢀC 35.68(15)° av.) define
the equatorial plane (with an average deviation of C
atoms by only 2.9 pm). The analogous parameters
described for 1 are d(CꢁC) 140.7(3) pm av. and angle
CꢀRhꢀC 35.9(1)° av. [1]. The rhodium atom is coplanar
with the six coordinated olefinic carbon atoms, the
pyrazole ring plane is nearly perpendicular to the equa-
torial plane [Rh(CꢁC)3] (dihedral angle 96,8°), and the
phenyl ring plane includes only a small dihedral angle
(16.8°) with the pyrazole plane.
31P-NMR data a
Complex
l(31P)
1J(RhP) Solvent
b
1
RhCl[P(C7H7)3]
325.3
327.2
330.3
310.8
189.5
187.1
187.9
167.5
CDCl3
CD3CN
CD3CN
CDCl3
CDCl3
CDCl3
CD3CN
CD2Cl2
CDCl3
CD3CN
CD2Cl2
CDCl3
b
2
3
{Rh[P(C7H7)3]}BF4
Rh(pz3Ph)[P(C7H7)3]
4a {Rh(ophen)[P(C7H7)3]}BF4 215.4 (263K) 181.7
4b {Rh(bipy)[P(C7H7)3]}BF4 214.8 (243K) 180.7
5
{Rh[P(C7H7)3]}(CF3COO)
329.9
314.6
238.6
330.3
313.3
188.6
195.4
181.5
187.9
208.6
150.7
6
7
Tp*Rh[P(C7H7)3] [3]
{Rh[P(C7H7)3]}(CF3SO3)
{Rh2[P(h3-C15H14)(C7H7)]2- 180.4
(m-Cl)3}(CF3SO3)
When Rh(pz3Ph)[P(C7H7)3] (3) is treated with excess
trifluoroacetic acid, the RhꢀN bond is cleaved to give
3-phenyl-1-pyrazole and the trifluoroacetate salt 5. Al-
though the CF3COO− anion is certainly displaced from
Rh in CD3CN solution (cf. Table 1), it is probably
coordinated in the solid state. Thus, the molecular ion
M+={Rh[P(C7H7)3](CF3COO)}+ (m/e=550) and a
fragment M+−C7H7 (m/e=459) are clearly observed
in the electron-impact (EI) mass spectra of solid
samples.
8
a Chemical shifts, l(31P), and coupling constants, 1J(103Rh,31P)
{91 Hz}; room temperature, unless noted otherwise (4a and 4b).
NMR spectrometer Bruker ARX 250.
b cf. Ref. [1] (NMR spectrometer Jeol FX 90Q); 1, 322.7 {190.4}
(CDCl3); 2, 327.7 {188.0} (CD3CN).
The reaction of 1 with pyrazole or substituted pyra-
zoles (such as 3-phenyl-pyrazole, Hpz3Ph) leads to pyra-
zolato complexes which contain a reactive RhꢀN amide
bond. The molecular geometry of the 3-phenyl-1-pyra-
zolato complex 3 has been determined by an X-ray
structure analysis; important bond lengths and angles
are given in the legend of Fig. 1. As in the chloro
The solvent-free salt {Rh[P(h2-C7H7)3]}+BF4− (2) is
able to incorporate chelating ligands such as 1,10-
phenanthroline (ophen) and 2,2%-bipyridine (bipy) into
the coordinated sphere to give and {Rh(LꢀL)[P(h2-
C7H7)2(C7H7)]}+BF4− (LꢀL=ophen (4a) or bipy (4b)).
Scheme 1.

168
M. Herberhold et al. / Journal of Organometallic Chemistry 621 (2001) 166–172
p-coordinated olefinic double bond and the phosphorus
atom; one cyclohepta-2,4,6-trienyl substituent is unco-
ordinated. A stereoselective 4:2 Diels–Alder cycloaddi-
tion between the two other C7H7 substituents has taken
place to give a rigid cyclohexene ring. It should be
noted that cycloadditions involving cycloheptatrienes
are, in general, difficult to control [6,7], although in-
tramolecular Diels–Alder reactions in 1-cyclohepta-
2,4,6-trienyl derivatives have been used synthetically in
special cases [8,9].
The molecular geometry of the cation in 8 could not
have been understood without an X-ray structure anal-
ysis (Fig. 2, Table 3). However, on the basis of this
1
structure, the H- and 13C-NMR data could unambigu-
1
ously be assigned using two-dimensional H/1H-COSY
and 13C/1H-HETCOR correlation spectra; in particular,
the unique CH2 group (C14 and C35, respectively) was
clearly identified by a 13C J-modulated spin-echo NMR
experiment. The cation of complex 8 is rigid in CDCl3
solution at room temperature.
The dinuclear structure of the cation in 8 (Fig. 2)
contains three chloro bridges, but only one (Cl(3)) is
symmetrical. The tridentate phosphane ligand [P(h3-
C14H15)(C7H7)] behaves formally as an anionic five-
electron system, i.e. 8 is an analogue of the pen-
Fig. 1. Molecular structure of Rh(pz3Ph)[P(h2-C7H7)3], (3·CHCl3), in
the crystal. Selected bond distances (pm) and bond angles (°): RhꢀP
217.15(9), RhꢀN(1) 214.8(3), RhꢀC(4) 230.7(4), RhꢀC(5) 229.7(4),
RhꢀC(11) 231.2(3), RhꢀC(12) 228.6(4), RhꢀC(18) 227.7(4), RhꢀC(19)
226.7(4); C(4)ꢀC(5) 140.7(5); C(11)ꢀC(12) 139.8(6), C(18)ꢀC(19)
140.6(6); N(1)ꢀN(2) 135.0(4), N(1)ꢀC(22) 134.1(5), C(22)ꢀC(23)
137.9(6), C(23)ꢀC(24) 138.4(6), C(24)ꢀC(25) 147.3(5); N(1)ꢀRhꢀP(1)
178.20(9), PꢀRhꢀC(4) 89.45(10), PꢀRhꢀC(5) 90.60(10), N(1)ꢀRhꢀC(4)
90.11(13), N(1)ꢀRhꢀC(5) 88.03(13), C(4)ꢀRhꢀC(5) 35.60(13);
RhꢀN(1)ꢀN(2) 119.7(2), RhꢀN(1)ꢀC(22) 132.5(3), N(2)ꢀN(1)ꢀC(22)
107.5(3).
tamethylcyclopentadienyl
complexes
{Cp2*Rh2(m-
Cl)3}ClO4 and {Cp*Ir2(m-Cl)3}ClO4 [10]. In contrast to
2
8, the three chloro bridges are symmetrical in the salts
Cs3[Cl3Rh(m-Cl)3RhCl3] (RhꢀCl(bridge) 252.4(1) pm,
In the cations, the P(C7H7)3 ligand behaves as a triden-
tate six-electron ligand with one uncoordinated cyclo-
hepta-2,4,6-trienyl substituent, thus opening one
equatorial position for the bidentate four-electron lig-
and LꢀL. The complexes 4a and 4b are fluxional in
solution at room temperature, but become rigid at
−10°C (4a) or −30°C (4b), respectively. The fully
RhꢀCl(terminal) 229,3(1) pm) [11] and {Cp*Ir2(m-
2
Cl)3}ClO4 (IrꢀCl 244.9 pm av.) [10]. The distance be-
tween the two metals (327.9(1) pm in 8 and 332.2(2) pm
in {Cp*Ir2(m-Cl)3}ClO4 [10], respectively) indicates that
2
direct interactions are absent, although the bridge sys-
tem is contracted in Cs3[Rh2Cl9] and Cs3[Rh2Br9]
(RhꢀRh distances of 306.6(1) pm and 298.9(1) pm,
respectively [11]). Each phosphorus atom carries an
uncoordinated cyclohepta-2,4,6-trienyl substituent, one
of them (C(15)ꢀC(21)) is disordered in the C(18)ꢀC(21)
part.
1
assigned H- and 13C-NMR data of 4a and 4b are given
in Table 2.
The trifluoromethane sulfonate salt, {Rh[P(h2-
C7H7)3]}+CF3SO−3 (7), was prepared using the
trimethylsilyl ester, CF3SO2ꢀOSiMe3 (Scheme 2). With
Cl-free precursors such as the 3-phenyl-pyrazolate com-
plex 3 or the tris(3,5-dimethyl-1-pyrazolyl)borate com-
plex 6, the yellow salt 7 is formed as expected if an
excess of CF3SO2ꢀOSiMe3 is applied. If, however, the
trimethylsilyl ester was added slowly in small concen-
trations and moist THF was used, an orange dinuclear
complex (8) became the main product.
3. Experimental
The synthesis of the ligand P(C7H7)3 [12] and of the
rhodium(I) educts [RhCl(h4-C8H12)]2 [13], [RhCl-
[P(C7H7)3] (1) [1], [Rh(Cp)[P(C7H7)3] [2] and
Tp*Rh[P(C7H7)3] (6) [3] has been documented in the
literature.
Instrumentation: IR spectra: Perkin–Elmer, 983G.
NMR spectrometer: Bruker ARX 250 (1H, 13C, 31P)
and AM 500 (1H, 13C). EI-MS: Finnigan MAT
8500 (Ionisation energy 70 eV); FD-MS: Varian MAT
311A.
According to the X-ray crystallographic structure
determination, complex 8 contains a triply chloro-
bridged rhodium(III) cation with a modified olefinic
phosphane ligand which has apparently been formally
reduced during the redox process (Fig. 2). The rear-
ranged phosphane is formally a five-electron ligand,
attached to rhodium(III) through a RhꢀCH s-bond, a

M. Herberhold et al. / Journal of Organometallic Chemistry 621 (2001) 166–172
169
Table 2
a
1H- and 13C-NMR spectra of the cations in {Rh(LꢀL)[P(C7H7)3]}BF4
3.1. Syntheses
Irel.): 550 (M+, 30%), 459 (M+−C7H7, 12%), 144
(Hpz−Ph+, 100%), 91 (C7H7+, 100%).
3.1.1. Tri(1-cyclohepta-2,4,6-trienyl)phosphane-rhodium
tetrafluoroborate (2) [cf. 1]
3.1.3. (1,10-Phenanthroline)-tri(1-cyclohepta-2,4,6-
trienyl)phosphane-rhodium tetrafluoroborate (4a)
A tetrahydrofuran solution (20 ml) containing both
100 mg (0.20 mmol) Rh[P(C7H7)3]BF4 (2) and 36 mg
A solution of 195 mg (1 mmol) AgBF4 in 20 ml of
acetonitrile was added dropwise to an acetonitrile solu-
tion (30 ml) of 443 mg (1 mmol) RhCl[P(C7H7)3] (1).
The precipitate (AgCl) was removed and the solution
brought to dryness. The yellow product was washed
with hexane and dried under high vacuum at 40°C.
Yield 450 mg (91%), light-yellow powder, dec. above
250°C. The IR and 1H-NMR spectra confirmed the
absence of acetonitrile.
3.1.2. (3-Phenyl-1-pyrazolato)-tri(1-cyclohepta-2,4,6-
trienyl)phosphane-rhodium (3)
50 mg (0.35 mmol) 3-phenyl-pyrazol and 80 mg (0.18
mmol) RhCl[P(C7H7)3] (1) were dissolved in acetonitrile
(30 ml), and the solution was stirred at room tempera-
ture. After 2h a light-yellow powder started to precipi-
tate which was collected, washed with pentane and
dried. Yield: 59 mg (60%), dec. 278°C. EI-MS: (m/e,
Scheme 2.

170
M. Herberhold et al. / Journal of Organometallic Chemistry 621 (2001) 166–172
Fig. 2. Molecular structure of {Rh2[P(h3-C14H15)(C7H7)]2(m-Cl)3}+(CF3SO−3 ) (8) in the crystal. Selected bond distances (pm) and bond angles (°):
Rh(1)ꢀCl(1) 242.40 (16), Rh(1)ꢀCl(2) 259.57(16), Rh(1)ꢀCl(3) 250.74(16); Rh(2)ꢀCl(1) 259.73(15), Rh(2)ꢀCl(2) 240.72(16), Rh(2)ꢀCl(3) 252.31(18);
Rh(1)ꢀP(1) 221.08(17), Rh(1)ꢀC(13) 214.1(6), Rh(1)ꢀC(4) 216.3(6), Rh(1)ꢀC(5) 227.5(6); Rh(2)ꢀP(2) 221.89(18), Rh(2)ꢀC(34) 215.1(6),
Rh(2)ꢀC(25) 216.3(6), Rh(2)ꢀC(26) 227.0(6); P(1)ꢀC(1) 183.4(6), P(1)ꢀC(8) 183.7(6), P(1)ꢀC(15) 187.3(7), P(2)ꢀC(22) 183.2(6), P(2)ꢀC(29) 183.2(7),
P(2)ꢀC(36) 182.8(6); C(4)ꢀC(5) 138.6(9), C(25)ꢀC(26) 137.6(10), C(10)ꢀC(11) 131.6(11), C(31)ꢀC(32) 132.7(11); Rh(1)ꢀCl(1)ꢀRh(2) 81.50(5),
Rh(1)ꢀCl(2)ꢀRh(2) 81.85(5), Rh(1)ꢀCl(3)ꢀRh(2) 81.40(5), C(4)ꢀRh(1)ꢀC(5) 36.3(2), C(25)ꢀRh(2)ꢀC(26) 36.1(2).
Table 3
1H- and 13C-NMR spectra a,b of the cation {Rh2[P(h3-C14H15)(C7H7)]2(m-Cl)3}+(CF3SO−3 ) (8)
c
d
1H-NMR
13C-NMR
Coordinated ring systems (p3-C14C15
)
H1
H2
H3
H4
H5
H6
H7
H22
H23
H24
H25
H26
H27
H28
3.46
2.40
2.88
5.08
6.00
6.31
6.57
C1
C2
C3
C4
C5
C6
C7
C22
C23
C24
C25
C26
C27
C28
42.5 d [12.3]
45.4 d [8.9]
44.5 d [14.2] 44.6 d [14.2]
90.9 br
96.3 br
128.6 s 128.7 s
134.7 s
H8
H29
H30
H31
H32
H33
H34
H35
2.54
2.88
6.00
6.15
3.62
5.75
1.00 e
C8
C29
C30
C31
C32
C33
C34
C35
37.6 d [24.1]
44.5 d [14.5] 44.6 d [14.2]
128.5 s 128.6 s
131.9 br
55.9 s
71.2 d {8.3}
39.6 d [10.3]
H9
C9
H10
H11
H12
H13
H14
C10
C11
C12
C13
C14
Uncoordinated rings (C7H7)
H15 H36
3.62
5.35
6.31
6.51
C15
C
C
C
C36
38.7 d [22.4]
118.2 s 119.4 s
129.0 d [8.8] 129.5 d [8.9]
131.5 s 131.9 s
H
H
H
16/H21
H
H
H
37/H42
16/C21
17/C20
18/C19
C
C
C
37/C42
17/H20
18/H19
38/H41
39/H40
38/C41
39/C40
a CDCl3 solutions, room temperature; Bruker AM 500.
b The numbering system corresponds to that of the X-ray structure analysis (Fig. 2).
c All 1H-NMR signals are multiplets (which may overlap).
d Coupling constants [nJ(31P,13C)] and {1J(103Rh,13C)} in Hz.
e CH2 group.
(0.20 mmol) ortho-phenanthroline was stirred at room
temperature for 3h. During the first hour, the yellow
solution became orange-red, and an orange solid pre-
cipitated. More precipitate was formed by addition of
pentane. The product 4a was dried under high vacuum.
Yield 110 mg (93%), dec. above 204°C. FD-MS (m/e,
3.1.4. Tri(1-cyclohepta-2,4,6-trienyl)phosphane-rhodium
trifluoroacetate (5)
A tetrahydrofuran (THF) solution (10 ml) containing
82 mg (0.17 mmol) Rh(Cp)[P(C7H7)3] was treated with
1 ml (z=1.49 g/ml, ca 13 mmol) of trifluoro acetic
acid. A yellow precipitate was formed which was col-
lected, washed with THF and dried under high vacuum.
Yield 93 mg (98%), dec. 238°C.
I
rel.): 587 (M+, 8%), 496 (M+−C7H7, 3%).
The analogous addition reaction (1:1) of 2 with 2,2%-
bipyridine (bipy) can be similarly carried out in THF
solution.
EI-MS: (m/e, Irel.): 520 (M+, 18%), 429 (M+−C7H7,
8%), 407 (M+−CF3COO, 5%), 316 (Rh[P(C7H7)2]+,

M. Herberhold et al. / Journal of Organometallic Chemistry 621 (2001) 166–172
171
5%), 307 (Rh(C7H7)(CF3COO)+, 6%), 285 (Rh(C7H7)2+,
5%), 238 (Rh(C7H7)(CO2)+, 6%), 91 (C7H7+, 100%). IR
(cm−1): w(C=O) 1684 vs, w(C=C) 1607 w, br.
rection (C-scans) yielded min./max. transmission fac-
tors of 0.2402/0.2602, the max./min. residual electron
density was 0.492/−0.532 · 10−6 e pm−3
.
3.1.5. Tri(1-cyclohepta-2,4,6-trienyl)phosphane-rhodium
trifluormethane sulfonate (7)
3.2.2. Crystal structure of 8
[C42H86P2Cl3Rh2]·[CF3SO3], orange platelet with di-
0.1 ml (0.55 mmol) Trimethylsilyl trifluoromethane
sulfonate (z=1.23 g/ml) were added to an orange
solution of 70 mg (0.10 mmol) Tp*Rh[PC7H7)3 in 10 ml
of acetonitrile. The colour of the solution turned to
light-yellow. After 15 min the solvent was distilled off,
and the light yellow residue was washed with hexane
and dried. Yield: 48 mg (87%), dec. 278°C.
mensions 0.40×0.35×0.08 mm crystallizes in the tri-
(
clinic space group P1 with the lattice parameters
a=1046.2(2), b=1410.5(3), c=11436.0(3) pm, h=
106.78(3),
i=97.70(3),
k=90.28(3)°,
V=
2008.4(7) · 106 pm3, Z=2, v=1.212 mm−1; 8166
reflections collected in the range 3°52r550°, 6939
reflections independent, 6012 assigned to be observed
[I\2|(I)], full-matrix least squares refinement against
F2 with 500 parameters converged at R1/wR2-values of
0.058/0.156, empirical absorption correction (C-scans)
resulted in min./max. transmission factors of 0.3573/
0.5299, the max./min. residual electron density was
3.1.6. Synthesis of
{Rh2[P(p3-C14H15)(C7H7)]2(v-Cl)3}+CF3SO−3 (8)
Trimethylsilyl trifluoromethane sulfonate was slowly
added to
a
solution of 90 mg (0.20 mmol)
1.93/−1.66 10−6 e pm−3
.
RhCl[P(C7H7)3] (1) in 30 ml of technical (i.e. moist)
tetrahydrofuran. (Note: pure and dry THF may be
polymerized in the presence of the cation
Rh[P(C7H7)3]+.) The colour changed immediately from
yellow to orange, indicating the formation of 8. The
orange solution was stirred for 5 h, then THF was
evaporated at room temperature and the orange residue
extracted with 20 ml of Et2O in which 1 and salts of the
Rh[P(C7H7)3]+ cation are almost insoluble.
4. Supplementary information
Crystallographic data (excluding structure factors)
for the structures of 3 and 8 have been deposited with
the Cambridge Crystallographic Data Centre as supple-
mentary publications Nos CCDC 154038 and 154039.
Copies of the data can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge CB2
1EZ, UK (Fax: +44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
The combined Et2O extracts were brought to dryness
and the product 8 crystallized from THF. Yield 32 mg
(32%), dec. above 237°C.
3.2. Crystal data and structure determinations
The reflection intensities were collected on a Siemens
P4 diffractometer (Mo–Ka radiation, u=71.073 pm,
graphite monochromated). Structure solution and re-
finement were carried out with the program package
SHELXTL-PLUS V.5.1. Measuring temperature for all
structure determinations was 296 K.
All non-hydrogen atoms were refined with an-
isotropic temperature factors. The hydrogen atoms are
on calculated positions. All hydrogen atoms were
refined applying the riding model with fixed isotropic
temperature factors.
Acknowledgements
Support of this work by the Fonds der Chemischen
Industrie is gratefully acknowledged. We particularly
thank Professor B. Wrackmeyer, Bayreuth, and Dr G.
Kehr for discussions and help on NMR problems.
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