ω-Monofluoroalkylrhodoximes: Synthesis and structures of [Rh{(CH2)nF}(dmgH)2(PPh3)] (n=1, 3) and C-F activation reactions

Article abstract of DOI:10.1016/S0022-328X(00)00886-X

[Rh(dmgH)₂(PPh₃)]^- ([Rh]^-), synthesized by reduction of [Rh]-Cl with NaBH₄ in methanolic KOH, reacts with 1,ω-dihaloalkanes X(CH₂)_nF (X=Cl, n=1; X=Br, n=3) forming [Rh]-CH₂F (2a) and [Rh]-(CH₂)₃F (2b). Reaction of [Rh]^- with BrCH₂CH₂F affords instead of the expected 2-fluoroethyl complex the dinuclear complex [Rh]-CH₂CH₂-[Rh] (4) exhibiting an unexpected C-F bond activation. Complexes 2a and 2b were fully characterized by NMR spectroscopy (¹H, ¹³C, ³¹P, ¹⁹F) and by X-ray diffraction. Complex 2a crystallizes as a dimer with crystallographically imposed C_i symmetry. The monomeric entities are linked via two O-HO hydrogen bridges. Complex 2b is monomeric in solid state. In both complexes there is a nearly linear P-Rh-C moiety. Structural and NMR trans influence of fluoromethyl and 3-fluoropropyl ligand is discussed.

Full text of DOI:10.1016/S0022-328X(00)00886-X

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 622 (2001) 172–179
v-Monofluoroalkylrhodoximes: synthesis and structures of
[Rh{(CH2)nF}(dmgH)2(PPh3)] (n=1, 3) and CꢀF activation
reactions
Mario Rausch, Clemens Bruhn, Dirk Steinborn *
Institut fu¨r Anorganische Chemie der Martin-Luther-Uni6ersita¨t Halle-Wittenberg, Kurt-Mothes-Str. 2, D-06120 Halle, Germany
Received 21 July 2000; received in revised form 5 October 2000; accepted 8 November 2000
Dedicated to Professor Brigitte Sarry on the occasion of her 80th birthday.
Abstract
[Rh(dmgH)2(PPh3)]− ([Rh]−), synthesized by reduction of [Rh]ꢀCl with NaBH4 in methanolic KOH, reacts with 1,v-di-
haloalkanes X(CH2)nF (X=Cl, n=1; X=Br, n=3) forming [Rh]ꢀCH2F (2a) and [Rh]ꢀ(CH2)3F (2b). Reaction of [Rh]− with
BrCH2CH2F affords instead of the expected 2-fluoroethyl complex the dinuclear complex [Rh]ꢀCH2CH2ꢀ[Rh] (4) exhibiting an
unexpected CꢀF bond activation. Complexes 2a and 2b were fully characterized by NMR spectroscopy (1H, 13C, 31P, 19F) and by
X-ray diffraction. Complex 2a crystallizes as a dimer with crystallographically imposed Ci symmetry. The monomeric entities are
linked via two OꢀH···O hydrogen bridges. Complex 2b is monomeric in solid state. In both complexes there is a nearly linear
PꢀRhꢀC moiety. Structural and NMR trans influence of fluoromethyl and 3-fluoropropyl ligand is discussed. © 2001 Elsevier
Science B.V. All rights reserved.
Keywords: Organorhodoximes; Fluoroalkyl complexes; Dinuclear complexes; CꢀF Activation; Crystal structures
These two aspects led us to investigate the synthesis and
characterization of bis(dimethylglyoximato) complexes
1. Introduction
of rhodium (rhodoximes) with v-fluoroalkyl ligands of
the type [Rh]ꢀ(CH2)nF (n=1, 3).
Transition metal complexes with fluoroalkyl lig-
ands — except for perfluoroalkyl ligands [1] —
belong to a less thoroughly investigated class of
organometallic compounds. In general, carbonꢀfluorine
bonds in saturated hydrocarbons are inert and their
activation is a topic of considerable recent interest [2].
Organorhodoximes [RhR(dmgH)2(L)] (Fig. 1; R=
hydrocarbyl, L=axial base: py, PPh3, PMe3, H2O...),
first prepared by Weber and Schrauzer [3], have been
extensively investigated. They are readily accessible and
normally quite stable compounds. When a P-donor is
used as axial base [4] the electronic structure in the
linear complex fragment PꢀRhꢀC can be thoroughly
studied by NMR spectroscopy (I=1/2; 103Rh, 31P, 13C)
[5]. For L=PPh3 organorhodoximes with all basic
types of hydrocarbyl ligands R (sp3: alkyl; sp2: vinyl,
aryl, allenyl; sp: alkinyl), with functionalized organo
ligands such as ꢀ(CH2)nYRx and ꢀCHꢁCHYRx (Y=el-
ement of group 15–17) [4] and dinuclear complexes
[Rh]ꢀ(CH2)nꢀ[Rh] (n=2–5) [6] were synthesized.
Organocobaloximes [CoR(dmgH)2(L)] (L=py, PPh3,
P(OMe)3...) with fluoroalkyl ligands have been de-
scribed [7], especially those with perfluorinated carbon
Fig. 1. Organorhodoximes (general formula).
Abbre6iations: [Rh], [Rh(dmgH)2(PPh3)]; dmgH2, dimethylgly-
oxime.
* Corresponding author. Tel.: +49-345-5525620; fax: +49-345-
5527028.
E-mail address: steinborn@chemie.uni-halle.de (D. Steinborn).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00886-X

M. Rausch et al. / Journal of Organometallic Chemistry 622 (2001) 172–179
173
plexes with R=CF2CHF2, CF2CHFCl were obtained
in reactions of the cobalt(I) precursor with fluorinated
olefins [9]. The difluoromethyl complex (R=CHF2)
was obtained as side product in the preparation of the
trifluoromethyl complex and directly in the reaction of
[Co(dmgH)2(L)]− with ClCHF2. In the latter case, par-
tial replacement of F by H occurred, yielding the CH2F
complex as side product [10]. Fluoromethyl- and difl-
uoromethylcobalamins, vitamin B12 analogues with
CH2F and CHF2, respectively, replacing CN, were syn-
thesized [11]. The latter one was also structurally char-
acterized [12].
Scheme 1.
Except for [Rh(CH2CF3)(dmgH)2(py)] [4b,13],
oganorhodoximes with fluoroalkyl ligands have not yet
been described. Structures of transition metal com-
plexes with monofluoromethyl ligands LxMꢀCH2F or
those with terminal CH2F groups LxMꢀ(CH2)nꢀCH2F
(n=1–6) are not known at all. We report here synthe-
ses, characterization and structures of fluoromethyl and
3-fluoropropyl
rhodoximes
[Rh]ꢀCH2F
and
[Rh]ꢀ(CH2)3F. Furthermore, we report unprecedented
CꢀF bond activation in the reaction with corresponding
2-fluoroethyl moiety.
2. Results and discussion
Fig. 2. Structure of [Rh]ꢀCH2F (2a) in the crystal (only major
occupied position of F atom is shown). Ellipsoids are drawn at 30%
probability level. Apart from the OꢀH···O bridges, hydrogen atoms
have been omitted for clarity. The mononuclear entities are related by
an inversion center.
2.1. Monofluoroalkyl complexes
2.1.1. Synthesis
[Rh]− (1), prepared by reduction of [Rh]ꢀCl with
NaBH4 in methanolic KOH [14], reacts with ClCH2F at
room temperature within 4 h to give the fluoromethyl
complex [Rh]ꢀCH2F (2a, yield: 37%), cf. Scheme 1.
Br(CH2)3F reacts with [Rh]− in ratio 1.3:1 within five
min to give the 3-fluoropropyl complex [Rh]ꢀ(CH2)3F
(2b, yield: 84%). Complex 2b could also be prepared in
the same yield (82%) from the reaction of Br(CH2)3F
with two equivalents [Rh]− showing high stability of
the CꢀF bond against nucleophilic substitution (oxida-
tive addition). Under these conditions Br(CH2)3Br was
found to react with [Rh]− yielding the trimethylene-
bridged dinuclear complex [Rh]ꢀ(CH2)3ꢀ[Rh] [6]. The
fluoroalkyl complexes 2a and 2b form yellow air stable
crystals. Their identities were confirmed by microanaly-
sis, NMR spectroscopy (1H, 13C, 31P, 19F) and X-ray
structure analyses. Complex 2a is monomeric in CHCl3
as was shown by osmometric molecular weight determi-
nation (found 615.3 g mol−1, calc. for [Rh]ꢀCH2F
628.4 g mol−1).
Fig. 3. Structure of [Rh]ꢀ(CH2)3F (2b) in the crystal. Ellipsoids are
drawn at 30% probability level. Apart from the OꢀH···O bridges,
hydrogen atoms have been omitted for clarity.
2.1.2. Structures
Molecular structures of 2a and 2b are shown in Figs.
2 and 3. Selected bond lengths and angles are listed in
Table 1. Complex 2a crystallizes as a dimer that ex-
hibits crystallographically imposed Ci symmetry. The
atoms (R=CF3, CF2CF3, CF(CF3)2, CH2CF3) [8].
Complexes in which the alkyl ligand carries hydrogen
and fluorine at the same carbon atom are rare. Com-

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M. Rausch et al. / Journal of Organometallic Chemistry 622 (2001) 172–179
intramolecular O(1)ꢀH(1)···O(3) hydrogen bridge the
angle N(1)ꢀRhꢀN(3) is smaller than the opposite angle
N(2)ꢀRhꢀN(4) [96.7(1) vs 108.7(1)°]. The PꢀRhꢀC units
are nearly linear [C(27)ꢀRhꢀP: 2a 176.2(1)°; 2b
176.3(1)°]. In organorhodoximes [Rh]ꢀR the RhꢀP
bond lengths reflect the structural trans influence of
organo ligand R. Comparison of the RhꢀP distances in
2a and 2b with those in rhodoximes with simple organo
ligands R indicate a relatively high trans influence of
monomeric entities are linked via two OꢀH···O hydro-
gen bridges. Crystals of complex 2b contain discrete
monomeric molecules. In both complexes the rhodium
atoms display a distorted octahedral coordination with
the dimethylglyoximato ligands in the equatorial plane
and triphenylphosphine and the fluoroalkyl ligand in
the axial positions. In complex 2a the fluoromethyl
ligand is disordered due to a location of fluorine and
two hydrogens in two positions with an occupancy of
64.2 and 35.8%. This corresponds to a ‘rotation’ of
CH2F ligand around the RhꢀC(27) axis by about 79°.
Whereas in other rhodoximes [4] the two dimethyl-
glyoximato ligands are stabilized by two strong in-
tramolecular hydrogen bonds, complex 2a exhibits only
one and the two intermolecular OꢀH···O bridges de-
scribed above. The O···O distances [O(1)···O(3) 2.484(5)
,
the fluoroalkyl ligand [16]: CꢂCPh (2.409(1) A)B
,
,
CHꢁCH2 (2.447(1) A)BMe (2.454(1) A)BEt (2.461(2)
,
,
,
A):(CH2)3F 2b (2.467(1) A):CH2F 2a (2.471(1)
,
,
A)Bi-Pr (2.489(2) A):t-Bu (2.492(1) A). The dmgH
ligands are tilted away from the triphenylphosphine
ligand. This distortion can be described by the angle a
between the normal vectors of the dmgH planes and by
the displacement d of the Rh atom out of the mean
plane passing through the four N-donor atoms towards
the P atom [17]. There are no remarkable differences
between angles a and displacements d in 2a (3.0(2)°,
0.073(1) A) and 2b (11.6(2)°, 0.115(1) A) and those in
other alkylrhodoximes [Rh]ꢀR (9.5–13.5°, 0.048–0.130
A [16]).
Median of CꢀF bonds in organic ꢀCH2F compounds
(omitting 1,2-difluorides) is 1.399 A (lower/upper quar-
,
,
A, O(2)···O(4)% 2.459(5) A] show that these are strong
hydrogen bonds [15]. As a consequence of the strong
Table 1
,
,
,
Selected bond lengths (A) and bond angles (°) for 2a and 2b
[Rh]ꢀCH2F (2a)
[Rh]ꢀ(CH2)3F (2b)
,
Bond lengths
RhꢀC(27)
C(27)ꢀF
C(27)ꢀC(28)
C(28)ꢀC(29)
C(29)ꢀF
,
2.059(4)
2.102(4)
,
tile 1.389/1.408 A) [18]. Compared with that, the CꢀF
bond length in 2b is decreased by 0.04 A and that in 2a
by 0.09 A . RhꢀC bond in 2a is shorter than that in the
corresponding methyl complex (2.059(4) vs 2.119(4) A
1.307(7)/1.25(1) a
,
1.455(7)
1.532(8)
1.361(8)
2.467(1)
1.976(3)
1.973(3)
1.979(3)
1.965(3)
1
,
,
RhꢀP
2.471(1)
1.991(3)
2.032(3)
1.997(3)
2.042(3)
[16d]. Fluorine substitution may strengthen the
rhodiumꢀcarbon bond by ionic-covalent resonance
and/or by two-orbital–four-electron p-type interaction
[19].
RhꢀN(1)
RhꢀN(2)
RhꢀN(3)
RhꢀN(4)
Bond angles
C(27)ꢀRhꢀP
FꢀC(27)ꢀRh
176.2(1)
176.3(1)
2.1.3. NMR spectroscopy
118.1(4)/118.7(6) a
Both compounds 2a and 2b were fully characterized
by NMR spectroscopy. Selected values are shown in
FꢀC(29)ꢀC(28)
N(1)ꢀRhꢀN(2)
N(1)ꢀRhꢀN(3)
N(1)ꢀRhꢀN(4)
N(2)ꢀRhꢀN(3)
N(2)ꢀRhꢀN(4)
N(3)ꢀRhꢀN(4)
107.1(6)
78.6(2)
77.3(1)
96.7(1)
172.2(1)
173.1(1)
108.7(1)
77.0(1)
Table 2. The assignment of the 13C and H signals was
1
173.3(1)
100.9(2)
100.6(2)
173.3(1)
79.1(2)
proved by HETCOR experiments and attached proton
test (APT) spectra. Due to coupling with 19F, 31P, 103Rh
(I=1/2, natural abundance 100%), 13C resonances are
first order multipletts, see Fig. 4 as example. Fluorine
substitution gives rise to a strong down-field shift of the
carbon atom which is F bonded as the comparison with
other haloalkyl complexes [Rh]ꢀ(CH2)nX and with the
requisite alkyl complexes (X=H) shows [4e,6]: l(13C)
(n=1): X=F (2a) (93.3 ppm)BX=Cl (47.4 ppm)B
X=Br (39.2 ppm)BX=H (15.1 ppm); l(13C) (n=3):
X=F (2b) (85.9 ppm)BX=Cl (45.5 ppm)BX=H
(16.2 ppm).
a First value refers to F(1) (occupancy 64.2%) and the second one
to F(2) (occupancy 35.8%).
Table 2
Selected NMR data (chemical shifts in ppm, coupling constants in
Hz) of complexes [Rh]ꢀ(CH2)nF 2a (n=1) and 2b (n=3)
2a
2b
d(13C): a-/b-/g-CH2
d(19F)
93.3
27.4/29.9/85.9
−215.9
20.6/63.5
Due to coupling with I=1/2 nuclei (19F, 31P, 103Rh),
19F-NMR signals are complex first order multipletts,
see Fig. 5 as example. The 19F chemical shift in the
−226.9
24.7/61.0
16.0 (n=2)
31.7 (n=3)
225.0
1J(Rh,C)/1J(Rh,P)
nJ(Rh,F)
nJ(P,F)
4.9 (n=5)
167.0/18.6/4.5
1J/2J/3J(F,C)
1 Value refers to the major occupied position. Due to disorder of
fluorine atom, discussion must not be exaggerated.

M. Rausch et al. / Journal of Organometallic Chemistry 622 (2001) 172–179
175
Fig. 4. 125 MHz 13C-NMR spectrum of [Rh]ꢀ(CH2)3F (2b) in CDCl3.
fluoromethyl complex 2a was found at −226.9 ppm.
This corresponds to a down-field shift by 41 ppm in
comparison with CH3F (l(19F)= −267.9 ppm [20]).
On the other hand, in the fluoropropyl complex 2b and
in MeCH2CH2F the 19F chemical shifts are virtually the
same (−215.9 vs −218.6 ppm [20]). The 31P chemical
shifts (2a: 9.1 ppm; 2b: 9.4 ppm) are in the range
expected for organorhodoximes with triphenylphos-
phine as axial base [4]. In complexes [Rh]ꢀR magni-
tudes of the coupling constants 1J(103Rh,31P) can be
regarded as a measure for (NMR) trans influence of
organo ligands R such that higher values reflect lower
trans influence [4e,5]. For haloalkyl complexes
[Rh]ꢀ(CH2)nX [4e,6] the order (n=1) X=Br (70.8
Hz)\X=Cl (68.4 Hz)\X=F (2a) (61.0 Hz) and
(n=3) X=Cl (64.8 Hz)\X=F (2b) (63.5 ppm)
points to an increasing trans influence with increasing
electronegativity of the halo substituent. Fig. 6 shows
shows for organorhodoximes [Rh]ꢀR the correlation
high when BrCH2CH2F is used. Moreover, the yield
increased up to 80%, when the reaction of [Rh]− with
BrCH2CH2F was performed at −78°C and when the
reaction mixture was allowed to warm up at room
temperature within 12 h.
Most likely the reaction proceeds via the 2-
fluoroethyl complex 3 as an intermediate (Scheme 2).
But until now, attempts failed to detect 3 by NMR
spectroscopy also when [Rh]− was added to an excess
(1:5) of BrCH2CH2F or when the reaction was per-
formed in n-butanol. In the absence of KOH, [Rh]−
(prepared by reduction of [Rh]ꢀCl with NaBH4 in
dimethylformamide) reacts slowly (15 h) with
BrCH2CH2F forming the dinuclear complex 4 in traces
only.
The reaction of BrCH2CH2F with [Rh]− yielding the
dinuclear complex 4 clearly shows an activation of the
b-CꢀF bond. In the analogous reactions with
1
(r2=0.91) between trans influence parameters J(Rh,P)
and d(RhꢀP). Complexes 2a and 2b with their fluori-
nated alkyl ligands fit this correlation quite well.
2.2. Reaction of [Rh]− with 1-bromo-2-fluoroethane
In contrast to the reactions with ClCH2F and
BrCH2CH2CH2F yielding the fluoroalkyl complexes 2a
and 2b, the reaction of [Rh]− with BrCH2CH2F readily
proceeded at room temperature within five min to give
the
dinuclear
dimethylene-bridged
complex
[Rh]ꢀCH2CH2ꢀ[Rh] (4) in 46% yield (Scheme 2). The
identity of complex 4 was confirmed by NMR spec-
troscopy (1H, 13C, 31P) and comparison with an authen-
tical sample [6]. Two facts are worth mentioning in this
context: (i) The reaction of [Rh]− with XCH2CH2X%
yielding complex 4 is faster when X/X%=Br/F (room
temperature, 5 min, yield 46%) than when X/X%=Br/Cl
(room temperature, 60 min, yield 44%) or X/X%=Cl/Cl
(room temperature, 120 min, yield 24%) [6]. (ii) The
yield of complex 4 (values given in parantheses) is quite
Fig. 5. 188 MHz 19F-NMR spectrum of [Rh]ꢀCH2F (2a) in CDCl3.

176
M. Rausch et al. / Journal of Organometallic Chemistry 622 (2001) 172–179
measurements by the same authors could not establish
this effect, except for reaction of 6 with 1,2-dibro-
moethane yielding the dimethylene-bridged complex
[(PPDOBF2)RhꢀCH2CH2ꢀRh(PPDOBF2)] that may in-
volve neighboring group activation of bromine by
Rh(III) macrocycle in (non-seen) intermediate 2-bro-
moethyl complex [Rh{(CH2)2Br}(PPDOBF2)] [23].
To summarize, reactions of [Rh]− with X(CH2)nF
(n=1–3; X=Br, Cl) afford for n=1 and n=3 stable
v-fluoroalkyl rhodoximes [Rh]ꢀCH2F (2a) and
[Rh]ꢀ(CH2)3F (2b), respectively. In the case of the
reaction with BrCH2CH2F the probable intermediate
2-fluoroethyl complex 3 reacts further to give the
Fig. 6. Comparison between structural and NMR trans influence in
organorhodoximes [Rh]ꢀR. Error bars for bond lengths d(RhꢀP) are
93s and for coupling constants 1J(Rh,P) 90.3 Hz.
dimethylene-bridged
dinuclear
complex
[Rh]ꢀ(CH2)2ꢀ[Rh] (4) in an intermolecular substitution
reaction. The investigations contribute to the under-
standing of stability and reactivity of fluoroalkyl metal
complexes and of the electronic influence of fluorinated
alkyl ligands.
Scheme 2.
3. Experimental
Scheme 3.
3.1. General
X(CH2)nF (X=Cl, n=1; X=Br, n=3) (see above) an
activation of the a-CꢀF and a-CꢀF bond, respectively,
was not observed. Furthermore, it was shown that
simple alkyl halides as Me(CH2)4X (X=Br, Cl, F)
exhibit in the reaction with [Rh]− the expected reactiv-
ity yielding n-pentylrhodoxime 5 (Scheme 3): In accor-
dance with the increasing bond dissociation energies
(DHCꢀX: CꢀBr 285 kJ mol−1, CꢀCl 327 kJ mol−1, CꢀF
485 kJ mol−1 [21]) n-pentyl bromide and chloride react
within 10 min and 6–12 h, respectively, whereas n-pen-
tyl fluoride does not react at all.
All reactions with RhI were carried out under argon
using Schlenk techniques. [Rh]ꢀCl was prepared ac-
cording to a published method [24]. The other chemi-
cals were commercial materials used without further
purification. Solvents were dried by standard methods
and distilled prior use. Microanalyses (C, H, N) were
performed by the University of Halle microanalytical
laboratory using CHNS-932 (LECO) and vario EL
(elementar Analysensysteme) elemental analyser, re-
1
spectively. H-, 13C-, 19F- and 31P-NMR spectra were
The formation of a MꢀC bond with cleavage of a
CꢀF bond is rather unusual for a nucleophilic substitu-
tion reaction (that can be regarded in the wider sense as
an oxidative addition) at an saturated sp3-hybridized
carbon atom. The reason for this unusual reactivity is
not clear. A neighboring group activation of CꢀF bond
by the bis(dimethylglyoximato)rhodium(III) entity in
(non-seen) intermediate 2-fluoroethyl complex 3 may
play a role. Collman and coworkers [22] reported such
effects in several reactions of 1,v-dihalogenalkanes
X(CH2)nX (n=2, 3; X=Cl, Br, I) with neutral RhI-nu-
cleophil [Rh(PPDOBF2)] (6). But more exact kinetic
recorded on Varian Unity 500 and Gemini 200 spec-
trometers operating at 499.88 and 199.97 MHz for H,
1
respectively. Solvent signals (1H, 13C) were used as
internal standards. l(31P) and l(19F) are referred to
external H3PO4 (85%) and trifluoromethylbenzene
(0.05% in C6D6), respectively. Two-dimensional het-
eronuclear correlation NMR spectra (HETCOR) were
recorded on the UNITY 500 spectrometer. A CP9000
(Chrompack) was used for gaschromatographic analy-
ses. For the osmometric molecular weight determina-
tion a Vapor Pressure Osmometer No. A0280 (Knaur)
was used.

M. Rausch et al. / Journal of Organometallic Chemistry 622 (2001) 172–179
177
3.2. Synthesis of [Rh]ꢀCH2F (2a) and [Rh]ꢀ(CH2)3F
(2b)
6–12 h, X=Cl) water (100 ml) was added. The reac-
tion mixture was neutralized (pH=7–8) with solid CO2
and extracted with CH2Cl2 (3×10 ml). The extract was
dried (Na2SO4) and concentrated. The precipitate of
[Rh]ꢀ(CH2)4Me (5) was dissolved in acetone and repre-
cipitated with heptane. Yields: X=Br, 795 mg (78%);
X=Cl, 640 mg (63%). In the case of X=F after two
weeks no reaction product could be isolated.
To a solution of [Rh]ꢀCl (957 mg, 1.52 mmol) in
methanolic KOH (75 ml, 0.15 M), a solution of NaBH4
(76 mg, 2.01 mmol) in methanolic KOH (25 ml, 0.15
M) was added dropwise and stirred for 2 h at 20°C to
give a deep violet solution of [Rh]−. Compound 2a: To
this a solution of ClCH2F (ca. 18 mmol) in methanol
(25 ml) was added within 2 min. After the color had
turned yellow (4 h) water (100 ml) was added. The
reaction mixture was neutralized (pH=7–8) with solid
CO2 and extracted with CH2Cl2 (3×10 ml). The ex-
tract was dried (Na2SO4) and concentrated. The precip-
itate was dissolved in acetone and reprecipitated with
heptane. Yield: 350 mg (37%). Compound 2b: To the
solution of [Rh]− a solution of Br(CH2)3F (280 mg,
1.99 mmol) in methanol (20 ml) was added within 2
min. After the color had turned yellow (5 min) water
(100 ml) was added. The reaction mixture was neutral-
Compound 5: m.p. 160–170°C. Anal. Found: C,
56.1; H, 6.1; N, 8.1. Calc. for C31H40N4O4PRh C, 55.9;
1
H, 6.1; N, 8.4%. H-NMR (CDCl3, 500 MHz): 0.73 (3
H, t, o-CH3), 0.90–1.27 (8 H, m, a-d-CH2), 1.84 (12 H,
5
d, JP,H 2.1 Hz, 4 CH3), 7.4 (15 H, m, 3 C6H5).
13C-NMR (CDCl3, 125 MHz): 11.5 (s, 4 CH3), 13.9 (s,
o-CH3), 22.3 (d, 5JP,C 1.5 Hz, d-CH2), 23.9 (d, 4JP,C 10.8
3
2
Hz, g-CH2), 27.8 (d, JP,C 3.0 Hz, b-CH2), 35.5 (d, JP,C
1
3
75.2 Hz, JRh,C 19.8 Hz, a-CH2), 128.0 (d, JP,C 9.2 Hz,
1
Cm), 129.6 (s, Cp), 130.5 (d, JP,C 28.5 Hz, Ci), 133.4 (d,
2JP,C 10.8 Hz, Co), 148.2 (s, 4 CꢁN). 31P-NMR (CDCl3,
80 MHz): 8.8 (2JRh,P 61.0 Hz).
ized (pH=7 8) with solid CO2. After standing for
–
12–24 h the yellow precipitate of 2b was filtered off,
washed with diethyl ether and recrystallized from ace-
tone. Yield: 840 mg (83%).
3.4. Reactions of [Rh]− with BrCH2CH2F
A solution of BrCH2CH2F (380 mg, 3.0 mmol) in
methanol (20 ml) was added within 2 min at room
temperature to a solution of [Rh]− in methanolic KOH
(prepared from 1.52 mmol [Rh]ꢀCl as described above).
After the color had turned yellow (5 min) and stirring
for further 30 min, water (100 ml) was added. The
precipitate of 4 is filtered off, washed with acetone
(2×10 ml) and dried in vacuo. Yield: 425 mg (46%).
The identity of 4 was confirmed by NMR spectroscopy
(1H, 13C, 31P) [6].
Variation of reaction conditions: When the reaction
was performed at −78°C (2 h) and then reaction
mixture was allowed to warm at room temperature
within 12 h, 4 was obtained with a yield of 80% (740
mg). Using n-butanol instead of methanol the reaction
takes 6 h and 4 was obtained with 21% yield (195 mg).
Using dimethylformamide instead of methanol in the
absence of KOH after 15 h 4 was obtained only in
traces (ca. 3–4 mg).
Compound 2a: m.p. 175–185°C (dec.). Anal. Found:
C, 50.2; H, 4.8; N, 8.5. Calc. for C27H31FN4O4PRh: C,
1
51.6; H, 5.0; N, 8.9%. H-NMR (CDCl3, 200 MHz):
5
1.81 (2 H, d, JP,H 1.9 Hz, 4 CH3), 4.90 (2 H, ddd,
3
2
2JRh,H 1.1 Hz, JP,H 2.4 Hz, JF,H 47.5 Hz, a-CH2), 7.3
(15 H, m, 3 C6H5). 13C-NMR (CDCl3, 125 MHz): 11.4
(s, 4 CH3), 128.0 (d, JP,C 9.2 Hz, Cm), 129.7 (d, JP,C
3
1
4
2
30.8 Hz, Ci), 129.8 (d, JP,C 1.7 Hz, Cp), 133.2 (d, JP,C
10.8 Hz, Co), 149.1 (s, 4 CꢁN). 19F-NMR (CDCl3, 188
MHz): −226.9 (2JRh,F 16.0 Hz; JP,F 31.7 Hz; JF,H
3
2
47.5 Hz). 31P-NMR (CDCl3, 80 MHz): 9.1 (1JRh,P 61.0
3
Hz, JP,F 31.7 Hz), further values see Table 2.
Compound 2b: m.p. 170–180°C (dec.). Anal. Found:
C, 52.8; H, 5.6; N, 8.1. Calc. for C29H35FN4O4PRh: C,
1
53.1; H, 5.4; N, 8.5%. H-NMR (CDCl3, 500 MHz):
1.10 (2 H, m, a-CH2), 1.35 (2 H, m, b-CH2), 1.82 (12 H,
5
3
d, JP,H 2.1 Hz, 4 CH3), 4.15 (2 H, dt, JH,H 6.3 Hz,
2JF,H 47.7 Hz, g-CH2), 7.2 (15 H, m, 3 C6H5). 13C-
NMR (CDCl3, 125 MHz): 11.5 (s, 4 CH3), 129.3 (d,
3JP,C 9.1 Hz, Cm), 131.0 (d, JP,C 2.0 Hz, Cp), 131.4 (d,
3.5. Crystallographic studies
4
1JP,C 30.2 Hz, Ci), 134.5 (d, JP,C 11.1 Hz, Co), 149.7 (s,
2
4 CꢁN). 19F-NMR (CDCl3, 188 MHz): −215.9 (5JP,F
4.9 Hz; 2JF,H 47.7 Hz). 31P-NMR (CDCl3, 80 MHz): 9.4
(1JRh,P 63.5 Hz, 5JP,F 4.9 Hz), further values see Table 2.
Suitable single crystals of 2a and 2b were obtained by
recrystallization from acetone. The X-ray measure-
ments were performed on a STOE-Stadi4 four circle
diffractometer (2a) and on a STOE IPDS image plate
system (2b), respectively. The F atom in 2a is disor-
dered over two positions with an occupancy of 64.2 and
35.8%, respectively. Crystal data collections and pro-
cessing parameters are listed in Table 3. Compound 2b
is numerically corrected for absorption. The structures
were solved with direct methods (SHELXS-86 [25]) and
subsequent Fourier difference syntheses revealed the
3.3. Reactions of [Rh]− with Me(CH2)4X (X=Br, Cl,
F)
To a solution of [Rh]− in methanolic KOH, prepared
as described above, a solution of Me(CH2)4X (2.0
mmol) in methanol (20 ml) was added within 5 min.
After the color had turned yellow (10 min, X=Br;

178
M. Rausch et al. / Journal of Organometallic Chemistry 622 (2001) 172–179
Acknowledgements
positions of all non-hydrogen atoms which were refined
with anisotropic displacement parameters by full-matrix
least-squares routines against F2 (SHELXL-93 [26]).
Hydrogen atoms of 2a were added to the model in their
calculated positions, except for the oxygen bound H
atoms, which were found in the difference Fourier map.
In 2b all H atoms were found in the difference Fourier
map, except those on C28 and C29, which were placed
in calculated positions. All H atoms were refined
isotropically.
We gratefully acknowledge financial support from
the Deutsche Forschungsgemeinschaft and the Fonds
der Chemischen Industrie as well as the loan of chemi-
cals from the companies Merck (Darmstadt) and De-
gussa (Hanau).
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4. Supplementary material
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
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Table 3
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2a
2b
Molecular formula
Mr
C27H31FN4O4PRh C29H35FN4O4PRh
628.44
Yellow
0.3×0.1×0.1
298(2)
656.49
Yellow
0.30×0.20×0.08
220(2)
Monoclinic
P21/a
14.798(4)
13.308(5)
15.056(6)
94.10(3)
2957.4(18)
4
0.71073
1.474
0.678
2.04–25.00
24334
Color
Size (mm3)
Temperature (K)
Crystal system
Space group
Monoclinic
P21/n
,
a (A)
11.1228(12)
10.9712(17)
22.679(2)
100.129(11)
2724.4(6)
4
0.71073
1.532
0.733
1.82–24.96
5056
,
b (A)
,
c (A)
i (°)
3
,
V (A )
Z
a
,
u0 (A)
Dcalc (g cm−3
)
v (mm−1
)
q range (°)
Reflections collected
Independent reflections
Final R indices
[I\2|(I)]
R indices [all data]
4768
5192
R1=0.0366,
wR2=0.0860
R1=0.0544,
wR2=0.1039
0.612, −0.362
R1=0.0379,
wR2=0.1028
R1=0.0547,
wR2=0.1114
1.500, −0.813
Largest residual peaks
−3
,
(e A
)
a Mo–Ka radiation.

M. Rausch et al. / Journal of Organometallic Chemistry 622 (2001) 172–179
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Crystal Structures, University of Go¨ttingen, Germany, 1993.
.