An unusual selective reduction of an oxime into an imine group in halogenomethyl rhodoximes

Article abstract of DOI:10.1016/S0022-328X(98)00534-8

[Rh(dmgH)₂(PPh₃)]^- ([Rh]^-, 1) {[Rh]=[Rh(dmgH)₂(PPh₃)]; (dmgH)₂=dimethylglyoxime}, obtained by reduction of [Rh]-Cl with NaBH₄ in methanolic KOH, reacts with dihalogenomethanes CH₂X₂ (X=Br, Cl) to give besides the known complexes [Rh]-CH₂X (X=Br, 2a; X=Cl, 2b) the complexes [Rh(CH₂X){ON=C(Me)-C(Me)=NH}(dmgH)(PPh₃)] (X=Br, 3a; X=Cl, 3b) where one oxime unit is reduced to an imine. Due to the strong alkaline medium (methanolic KOH) 3a was found to react partially, yielding [Rh(CH₂OMe){ON=C(Me)-C(Me)=NH}(dmgH)(PPh₃)] (3c). All three complexes were characterized by ¹H-, ¹³C-, ³¹P-NMR spectroscopy. 3a crystallizes in the triclinic space group P1 with two molecules in the asymmetric unit. These molecules are linked via two N-HO hydrogen bridges forming a dimer. The rhodium atoms display a distorted octahedral coordination with the dmgH/ON=C(Me)-C(Me)=NH ligands in the equatorial plane and PPh₃ and the CH₂Br ligands in the axial positions.

Full text of DOI:10.1016/S0022-328X(98)00534-8

Journal of Organometallic Chemistry 561 (1998) 191–197
An unusual selective reduction of an oxime into an imine group in
halogenomethyl rhodoximes
Dirk Steinborn *, Mario Rausch, Clemens Bruhn
Institut fu¨r Anorganische Chemie der Martin-Luther-Uni6ersita¨t Halle-Wittenberg, Kurt-Mothes-Straße 2, D-06120 Halle, Germany
Received 21 January 1998; received in revised form 19 February 1998
Abstract
[Rh(dmgH)2(PPh3)]− ([Rh]−, 1) {[Rh]=[Rh(dmgH)2(PPh3)]; (dmgH)2=dimethylglyoxime}, obtained by reduction of [Rh]–Cl
with NaBH4 in methanolic KOH, reacts with dihalogenomethanes CH2X2 (X=Br, Cl) to give besides the known complexes
[Rh]–CH2X (X=Br, 2a; X=Cl, 2b) the complexes [Rh(CH2X){ONꢀC(Me)–C(Me)ꢀNH}(dmgH)(PPh3)] (X=Br, 3a; X=Cl, 3b)
where one oxime unit is reduced to an imine. Due to the strong alkaline medium (methanolic KOH) 3a was found to react
partially, yielding [Rh(CH2OMe){ONꢀC(Me)–C(Me)ꢀNH}(dmgH)(PPh3)] (3c). All three complexes were characterized by 1H-,
13C-, 31P-NMR spectroscopy. 3a crystallizes in the triclinic space group P1 with two molecules in the asymmetric unit. These
molecules are linked via two N–H···O hydrogen bridges forming a dimer. The rhodium atoms display a distorted octahedral
coordination with the dmgH/ONꢀC(Me)–C(Me)ꢀNH ligands in the equatorial plane and PPh3 and the CH2Br ligands in the axial
positions. © 1998 Elsevier Science S.A. All rights reserved.
Keywords: Rhodium complexes; Organorhodoximes; Oxime–imine moiety; Crystal structure
In all these reactions the pseudomacrocyclic ligand
system (dmgH)2 proved to be very stable apart from
protonation/deprotonation equilibria involving the hy-
drogen bonds [6] and modifications replacing the hydro-
gen bridges with boron bridges [7]. Only very recently,
there has been observed axial–equatorial ligand (R/
(dmgH)2) interactions: Thus, the OH group of the
(Z)-3-hydroxy-3-methyl-but-1-enyl ligand in [Rh]–
CHꢀCH–CMe2OH act as both hydrogen donor and
acceptor forming two strong hydrogen bonds to the
equatorial (dmgH)2 ligand with cleavage an O–H–O
bond between them [8]. Furthermore, [Rh]− was found
to react with X(CH2)nX (X=Cl, Br, n=3–5) via [Rh]–
1. Introduction
Since the first preparation of organorhodoximes
[Rh(dmgH)2(L)R] (L=py; R=Me, Et, CH2CH2CN)
by Weber and Schrauzer [1] in 1970, there have been
synthesized numerous organorhodoximes with various
axial bases (L=PPh3, PMe3, H2O, py, …) and a wide
variety of organo ligands (R=alkyl, aryl, vinyl,
alkynyl, allenyl, functionalized organo ligands) [2,3].
Recently, dinuclear oligo–methylene bridged complexes
[Rh]–(CH2)n-[Rh] (n=2–5) and a vinylene bridged
complex,
[{K(MeOH)2}2{(PPh3)(dmg)(dmgH)Rh–
CHꢀCH–Rh(dmg)(dmgH)(PPh3)}], were also prepared
and characterized by NMR spectroscopy and by X-ray
structure analysis [4,5]. Especially the triphenylphos-
phine complexes [Rh]–R were used to study the struc-
tural and the NMR trans influence of R with the bond
length d(Rh–P) and the coupling constant
1J(103Rh,13C), respectively, as measure [3].
(CH2)nX as intermediates, yielding cyclic organ-
¸¹¹¹¹¹¹¹¹¹¹¹¹¹¹º
[Rh{(CH2)n–ONꢀC(Me)–C(Me)ꢀNO}
orhodoximes
(dmgH)(PPh3)] [4]. Their formation can be understood
as an interligand nucleophilic substitution reaction of
an equatorial oximato group with the C–X group
of the ligated axial ꢀ-halogenoalkyl ligand in the inter-
* Corresponding author.
mediate [Rh]–(CH2)nX. Recently, a reduction of
0022-328X/98/$19.00 © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00534-8

192
D. Steinborn et al. / Journal of Organometallic Chemistry 561 (1998) 191–197
Scheme 1.
an oxime to an imine group was observed upon the
reaction of [Rh(dmgH)(dmgH2)Cl2]/NaBH4 with phos-
phines [9].
X=Cl, 3b) (Scheme 1b) where one oxime unit of the
equatorial ligand (dmgH)2 is reduced into an imine
group.
Bromo- and chloromethyl rhodoximes [Rh]–CH2X
(X=Br, Cl) are rather reactive. They react with
NaOMe in a nucleophilic substitution reaction to give
the methoxymethyl complex (X=OMe) ([3]a). An
analogous reaction was found in the cobaloximes [10].
But three-membered Co–N–C rings were formed by
using closely related equatorial imine/oxime ligands
instead of the bis(dimethylglyoximato) ligands [11].
Here we report the reaction of [Rh]− with CH2Br2
and CH2Cl2 in methanolic KOH to give not only the
expected complexes [Rh]–CH2X (X=Br, Cl, OMe) but
also unprecedented reduction reactions to give
[Rh(CH2X){ONꢀC(Me)–C(Me)ꢀNH}(dmgH)(PPh3)]
where one oxime unit is reduced to an imine moiety.
The yield of the reduced chloromethyl complex 3b is
only ca. 5%, whereas the chloromethyl complex with
the unchanged (dmgH)2 ligand 2b is formed in about
40% yield. Fast mixing of CH2Br2 and [Rh]− affords
the reduced bromomethyl complex 3a in about 50%
yield. By adding CH2Br2 to [Rh]− over a period of 3 h,
a substitution reaction takes also place to give the
reduced methoxymethyl complex [Rh(CH2OMe)
{ONꢀC(Me)–C(Me)ꢀNH}(dmgH)(PPh3)] (3c) due to
the strong alkaline medium (methanolic KOH). The
total yield of the two reduced complexes is about 20%
(3a:3c ca. 1:1). The isolated reduced bromomethyl com-
plex 3a undergoes in methanolic KOH (20 h, r.t.) the
same substitution reaction to form the methoxymethyl
complex 3c, with a yield of about 20%.
The reduced bromomethyl complex 3a was isolated
as yellow crystals. Because of the low yield and the
similar solubility in common organic solvents, the re-
duced chloromethyl complex 3b was obtained after
recrystallization from acetone/heptane (four times) only
in a mixture with the non-reduced chloromethyl com-
plex 2b (3b:2b ca. 4:1). For the same reason the
methoxymethyl complex 3c was obtained in a mixture
with complex 3a (ca. 1:1). All complexes were fully
characterized by NMR spectroscopy (1H, 13C, 31P) and
complex 3a by X-ray structure analysis, too. Complex
3a is monomer in CHCl3 as was shown by osmometric
2. Results and discussion
2.1. Synthesis
[Rh]− (1), prepared by reduction of [Rh]–Cl with
NaBH4 in methanolic KOH [12], reacts with CH2Br2
and CH2Cl2 to give the known bromo- and
chloromethyl complexes [Rh]–CH2X (X=Br 2a, yield:
14%; X=Cl 2b, yield: 74%). These complexes react
with NaOMe to produce the methoxymethyl complex
[Rh]–CH2OMe 2c (yield: 37–47%) ([3]a) (see Scheme
1a).
molecular weight determination (found 669.8 g mol−1
,
Besides the formation of 2, CH2X2 (X=Br, Cl)
reacts with [Rh]− to give the complexes [Rh(CH2X)-
{ONꢀC(Me)–C(Me)ꢀNH}(dmgH)(PPh3)] (X=Br, 3a;
calc. for [Rh(CH2Br){ONꢀC(Me)–C(Me)ꢀNH}(dmgH)
(PPh3)] 673.3 g mol−1).

D. Steinborn et al. / Journal of Organometallic Chemistry 561 (1998) 191–197
193
Fig. 1. Molecular structure of [Rh(CH2Br){ONꢀC(Me)–C(Me)ꢀNH}(dmgH)(PPh3)] 3a.
˚
N4···O1* 2.908(6) A) are in the typical range for N–
H···O bonds [13]. The oxygen atoms of the N–H···O
bonds O1 and O1* lie nearly in both planes of the
equatorial ligand systems as is shown in the stereo-
graphic projection in Fig. 2. The angle between these
two planes amounts to 61.25(9)°.
2.2. Structure
The molecular structure of 3a is shown in Fig. 1.
Selected bond lengths and angles are listed in Table 1.
3a crystallizes in the triclinic space group P1 with two
molecules in the asymmetric unit. These molecules are
linked via two N–H···O hydrogen bonds forming a
dimer. The N···O distances (N4*···O1 2.873(6),
The Rh atoms display a distorted octahedral coordi-
nation with the dmgH/ONꢀC(Me)–C(Me)ꢀNH ligands
in the equatorial plane and PPh3 and the bromomethyl
ligand in the axial positions. Whereas in other rho-
doximes [2,3,5,12,14] the two dmgH− ligands are stabi-
lized by two strong intramolecular O–H–O hydrogen
bonds, complex 3a exhibits only one [O(2)···O(3)
Table 1
a
˚
Selected bond lengths (A) and bond angles (°) for 3a
Rh–C(27)
Rh–P
2.073(6)/2.078(6) C(27)–Rh–P
2.423(2)/2.443(2) Br–C(27)–Rh
2.022(5)/2.035(5) N(l)–Rh–P
174.7(2)
1
˚
/175.0(2)
121.0(3)
2.541(7)/2.573(8) A] and the two intermolecular N–
H···O bridges described above. As a consequence of the
strong O–H–O bonds the angles N(2)–Rh–N(3)
[97.6(2)/97.4(3)°] are smaller than the angles N(1)–Rh–
N(4) [106.7(2)/106.1(2)°].
/121.8(3)
90.94(14)
Rh–N(1)
/90.18(14)
92.0(2)/90.9(2)
92.3(2)
Rh–N(2)
Rh–N(3)
1.987(5)/1.983(5) N(2)–Rh–P
2.005(5)/1.998(5) N(3)–Rh–P
As expected, the P–Rh–C unit is nearly linear
[174.7(2)/175.0(2)°]. But unexpectedly, there is a signifi-
cant difference (D=0.02 A) between the two Rh–P
bond lengths [Rh–P 2.423(2)/2.443(2) A]. Their magni-
/95.59(14)
92.89(14)
˚
Rh–N(4)
2.027(5)/2.031(5) N(4)–Rh–P
˚
/93.82(13)
77.4(2)/78.3(2)
78.0(2)/77.7(2)
tudes are in-between the Rh–P bond length of the
N(1)–O(1) 1.300(6)/1.309(6) N(l)–Rh–N(2)
N(2)–O(2) 1.373(6)/1.369(6) N(3)–Rh–N(4)
N(3)–O(3) 1.310(6)/1.308(6) N(1)–Rh–N(4) 106.7(2)
˚
phenylalkynyl complex [Rh]–CꢁCPh [2.409(1) A]
([15]a) and the vinyl complex [Rh]–CHꢀCH2 [2.447(1)
˚
A] ([15]b) pointing to a relatively low trans influence of
/106.1(2)
97.6(2)/97.4(3)
C(27)–Rh–N(1) 83.8(2)/87.3(3)
C(27)–Rh–N(2) 87.2(2)/92.8(2)
C(27)–Rh–N(3) 93.0(2)/87.3(3)
C(27)–Rh–N(4) 88.3(2)/82.8(2)
the bromomethyl ligand. The Rh–C bond length [Rh–
C(27) 2.073(6)/2.078(6) A] corresponds to those in the
mononuclear alkyl complexes [Rh]–R {R=Me, Et;
Rh–C 2.064(7)/2.119(4) A ([15]c,d)}. As in (non-re-
C(27)–Br
1.945(6)/1.920(7) N(2)–Rh–N(3)
˚
˚
a
Here and as follows the first figure refers to the molecule [Rh,…..,
C1–C27] and the second one to the molecule [Rh*,….., C1*–C27*].
1 Here and as follows the first figure refers to the molecule [Rh,…..,
C1–C27] and the second one to the molecule [Rh*,….., C1*–C27*].

194
D. Steinborn et al. / Journal of Organometallic Chemistry 561 (1998) 191–197
Fig. 2. Stereographic projection for 3a.
duced) organorhodoximes, the dmgH and ONꢀC(Me)–
C(Me)ꢀNH ligands are tilted away from the
triphenylphosphine ligand what can be described [16] by
the angle h=4.9(4)/9.8(3)° between the normal vectors
of the dmgH and the ONꢀC(Me)–C(Me)ꢀNH planes
and by the displacement of the Rh atom out of the mean
plane passing through the four N-donor atoms towards
3. Discussion
There are two further reports on reduction of
dimethylglyoximato complexes into oxime–imine com-
plexes: (i) [Rh(dmgH)(dmgH2)Cl2] reacts with NaBH4 in
methanolic KOH in the presence of phosphines of small
size and good donor ability to give complexes 4 (PR3=
PEt3, P(n-Bu)3, PPh2Me) [9]. (ii) [TcCl3(MeCN)
(PPh3)2] reacts with dmgH2 in the presence of ethyl-
boronic acid to give not only the expected complex
[TcCl{(dmgH)2(dmg)BEt}] but also complex 5 with an
oxime–imine ligand [17]. As with complexes 3, the
mechanism of the reduction is not at all clear. In the case
of the complex 4, the assumption was made tentatively
that the loss of oxime oxygen gives OH− [9]. In the case
of complex 5 it does seem likely that the imine moiety
forms at or near the time of coordination of the ligand to
technetium [17].
˚
the P atom d(Rh/N4)=0.072(2)/0.091(2) A. Similar
values for h and d were found in the ‘normal’ organorho-
doximes [Rh]–R (R=Me, Et, CHꢀCH2, CꢁCPh, h=
˚
6.2–15.1°; d(Rh/N4)=0.07–0.13 A) ([15]a–d).
The relatively great differences (3.5–5.7°) (Table 1)
between the angles C(27)–Rh–N and the corresponding
angles C(27)*–Rh*–N* might be a result of the different
orientation of the bromomethyl ligand in respect to the
equatorial ligand system measured by the torsion angels
Br–C(27)–Rh–N(4) (52.9(4)°) and Br*–C(27)*–Rh*–
N(4)* (176.2(4)°).
Attempts to carry out the reaction of complexes 6
(R=CH2Br; L=py, H2O, N-methylimidazole) with
NaOMe did not lead to the expected methoxymethyl
complexes 6 (R=CH2OMe) (analogous to the conver-
sion of [Co(CH2Br)(dmgH)2(py)] to [Co(CH2OMe)-
(dmgH)2(py)] [10]) but to complex 7 with a Co–N–C
three-membered cycle [11]. This demonstrates that the
reduction 2“3 might also be enforced by a neighboring
group effect. The reduction agent could be the excess of
NaBH4.
2.3. NMR spectroscopy
Selected NMR data of complexes 3a–c are summa-
rized in Table 2. The assignment of the 13C and 1H signals
was proved by HETCOR experiments and attached
proton test (APT) spectra.
Contrary to the non-reduced organorhodoximes
[Rh]–R, all four methyl groups and all four oxime/imine
groups are non-equivalent in complexes 3a–c. The imine
carbon atoms are strongly downfield shifted (CꢀNH
172.9–174.2 ppm vs. CꢀNOH 145.4–153.3 ppm). The
chemical shifts of the methyl groups attached to the imine
groups fall in the range lH=1.99–2.04 ppm and lC=
22.7–22.8 ppm, at lower field than those of the corre-
sponding methyl groups attached to the oxime/oximate
groups (lH=1.58–1.84 ppm; lC=10.9–12.7 ppm).
The same observations were made in bis(phosphin) rho-
dium complexes [Rh(dmgH){ONꢀC(Me)–C(Me)ꢀNH}-
(PR3)2]X (4) (X=NO3, ClO4, [Rh(dmgH)2Cl2]) [9].
The only characteristic difference in the axial moiety
P–Rh–C between the reduced complexes 3a–c and the
corresponding non-reduced complexes 2a–c is
a
downfield shift of the phosphorus resonances of about
3–5 ppm.

D. Steinborn et al. / Journal of Organometallic Chemistry 561 (1998) 191–197
195
Table 2
Selected NMR data (chemical shifts in ppm, coupling constants in Hz) of complexes 3a–c (values of the corresponding non-reduced complexes
2a–c are given for comparison [3]a)
3a (X=Br)
3b (X=Cl)
3c (X=OMe)
CH2X
l(13C) [2J(P,C)/1J(Rh,C)]
l(1H) [2J(Rh,H)/3J(P,H)]
38.7 [113.2/26.3]
3.45 [2.2/3.5]
46.6 [108.3/24.4]
3.64 [2.5/3.1]
80.5 [109.7/20.9]a
4.10 [—/2.6]
dmgH/ONꢀC(Me)–C(Me)ꢀNH
CH3 l(13C)/l(1H) [5J(P,H)]
11.2/1.58 [1.2]
11.8/1.79
12.7/1.83 [1.2]
22.8/2.03 [1.2]
146.2 [2.2]
150.4 [2.4]
153.3 [2.0]
174.2 [3.0]
10.50/4.06
11.2/1.58 [1.2]
11.8/1.79
12.7/1.83
22.7/2.04 [1.2]
146.8
150.3
153.2
174.1
10.09/4.60
10.9/1.58
11.6/1.80
12.5/1.84
22.7/1.99
145.4
149.7
152.4
172.9
15.60/10.05
CꢀN l(13C) [2J(Rh,C)]
NH/OH: l(1H)
PPh3
l(31P) [1J(Rh,P)]
12.7 [71.2]
13.4 [69.5]
10.7 [62.4]
2a (X=Br)
2b (X=Cl)
2c (X=OMe)
CH2X
l(13C) [2J(P,C)/1J(Rh,C)]
l(1H) [2J(Rh,H)/3J(P,H)]
39.2 [112.6/27.1]
3.30 [1.7/1.7]
47.4 [107.1/25.8]
3.43 [2.4/3.3]
81.4 [85.5/21.2]b
3.94 [0.9/2.6]
dmgH
CH3 l(13C)/l(1H) [5J(P,H)]
CꢀN l(13C)
11.8/1.88 [2.0]
147.5
11.7/1.87 [2.0]
149.4
11.5/1.87 [1.2]
148.5
PPh3
l(31P) [1J(Rh,P)]
8.0 [70.8]
10.0 [68.4]
6.4 [59.8]
a
b
–OCH3: l(1H)=3.05, l(13C)=60.8. –OCH3: l(1H)=3.11, l(13C)=61.0.
tion NMR spectra (HETCOR) were recorded on the
UNITY 500 spectrometer. For the osmometric molecu-
lar weight determination a Vapor Pressure Osmometer
no. A0280 (Knauer) was used.
The unusual reduction described in this paper is not
only of interest with respect to the stability of the
bis(dimethylglyoximato) complexes that are B12 model
complexes but also with respect to reductive cleavage of
oximes by low-valent transition metal compounds [18].
4.1. [Rh(CH2X){ONꢀC(Me)–C(Me)ꢀNH}(dmgH)-
(PPh3)] (X=Br, 3a; X=OMe, 3c)
4. Experimental
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, 2.00 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]−. To this CH2Br2
(350 mg, 2.00 mmol) in methanol (20 ml) was added
within 5 min. After the color had turned to yellow (5
min), the stirring was continued for 30 min and water
(100 ml) was added. After 12 h, the yellow precipitate
of 3a was filtered off, washed with diethyl ether and
recrystallized from chloroform. Yield of 3a: 475 mg
(47%). Extraction of the water/methanol solution with
CH2Cl2 afforded a mixture of complexes 2a and 3a (2a:
3a ca. 2:1). Yield: 115 mg (12%).
All reactions with RhI were carried out under argon
using Schlenk techniques. [Rh]–Cl was prepared ac-
cording to a published method [19]. All other chemicals
were reagent grade and used without further purifica-
tion. Solvents were dried and distilled prior use by
standard methods. Microanalyses (C, H, N, Br) were
performed by the University of Halle microanalytical
laboratory using CHNS-932 (LECO) and vario EL
(elementar Analysensysteme) elemental analyzer, re-
spectively. 1H-, 13C- and 31P-NMR spectra were
recorded on Varian UNITY 500 and GEMINI 200
spectrometers operating at 499.88 and 199.97 MHz for
1H, respectively (13C at 125.71/50.28 MHz, 31P at
202.36/80.95 MHz). Solvent signals (1H, 13C) were used
as internal standards; l(31P) is referred to external
H3PO4 (85%). Two-dimensional heteronuclear correla-
3a: Anal. Found: C, 47.20; H, 4.37; Br, 12.23; N,
7.78%. Calc. for C27H31BrN4O3PRh: C, 48.23; H, 4.50;
Br, 11.87; N, 8.33%. 13C-NMR (CDCl3, 125 MHz): l

196
D. Steinborn et al. / Journal of Organometallic Chemistry 561 (1998) 191–197
129.8 (1J(P,C)=34.9 Hz, Ci), 133.5 (2J(P,C)=10.8 Hz,
Co), 128.2 (3J(P,C)=9.4 Hz, Cm), 130.1 (4J(P,C)=2.3
Hz, Cp); for further values see Table 2.
Table 3
Crystal data collection and processing parameters for 3a
Molecular formula
M
C27H31BrN4O3PRh
673.35
Yellow
0.2×0.2×0.1
298(2)
Triclinic
The addition of CH2Br2 within 3 h (instead of 5 min)
afforded a mixture of complexes 3c and 3a (ca. 1:1)
after recrystallization (three times) from chloroform.
Yield: 211 mg (21%).
Color
Size (mm3)
T (K)
Crystal system
Space group
3c: 13C-NMR (CDCl3, 125 MHz): l 130.0 (1J(P,C)=
34.9 Hz, Ci), 133.5 (2J(P,C)=10.8 Hz, Co), 128.2
(3J(P,C)=9.4 Hz, Cm), 130.1 (4J(P,C)=2.3 Hz, Cp);
for further values see Table 2.
P1
˚
a (A)
11.900(2)
12.850(2)
20.946(4)
105.386(14)
91.417(14)
109.72(2)
2883.8(8)
4
0.71073 (Mo–Kh radiation)
1.551
2.068
1360
1.76–24.02
16710
8534
0.0747
5516
8533/0/667
0.0491, 0.0988
0.0947, 0.1157
0.998
˚
b (A)
˚
c (A)
h (°)
i (°)
k (°)
4.2. [Rh(CH2Cl){ONꢀC(Me)–C(Me)ꢀNH}(dmgH)-
(PPh3)] (3b)
3
˚
V (A )
Z
˚
To a solution of [Rh]− (1.52 mmol) in methanolic
KOH (100 ml, 0.15 M), prepared as described above,
CH2Cl2 (175.0 mg, 2.00 mmol) in methanol (20 ml) was
added within 5 min. After the color had turned to
yellow (2.5 h), the stirring was continued for 30 min
and water (100 ml) was added. After 12 h, the yellow
precipitate was filtered off, washed with diethyl ether
and dried in vacuo. Yield of the crude product (3b:2b
ca. 1:1): 86 mg (10%). Recrystallization (four times)
from acetone/heptane afforded 3b:2b (ca. 4:1). Yield: 44
mg (5%).
u0 (A)
Dcalc. (g cm−3
)
v (mm−1
F(000)
)
q range (°)
No. reflections collected
No. independent reflections
Rint
No. reflections with [I\2|(I)]
Data/restraints/parameters
Final R1, wR2 [I\2|(I)]a
All data
GOF (S)b
−3
˚
Largest residual peaks (e A
)
0.927, −0.629
Extraction of the water/methanol solution with
CH2Cl2 afforded complex 2b as main product. Yield:
380 mg (39%).
a R1=SꢀFoꢁ−ꢁFcꢀ/SꢁFoꢁ, wR2=[Sw(Fo2−Fc2)2/Sw(Fo2)2]0.5
.
b S (goodness-of-fit)=[Sw(Fo2−F2c)2/(Nobs−Nparam)]0.5 (based on all
3b: 13C-NMR (CDCl3, 125 MHz): l 130.1 (1J(P,C)=
33.9 Hz, Ci), 133.5 (2J(P,C)=10.8 Hz, Co), 128.2
(3J(P,C)=9.5 Hz, Cm), 130.1 (s, Cp); for further values
see Table 2.
data)
available on request from the Fachinformationszentrum
Karlsruhe, Gesellschaft fu¨r wissenschaftlich-technische
Information mbH, D-76344 Eggenstein-Leopoldshafen,
on quoting the depository no. CCDC-100963, the
names of the authors, and the journal citation.
4.3. Crystallographic studies
Suitable single crystals of 3a were obtained by recrys-
tallization from chloroform. The X-ray measurement
was performed on a STOE IPDS image plate system.
For the measurement the reciprocal space has been
scanned with 133 frames each of which oscillating the
crystal 1.5° around the €-axis.
Crystal data collections and processing parameters
are listed in Table 3. The structure was solved with
direct methods (SHELXS-86 [20]) and subsequent
Fourier difference synthesis revealed the positions of all
non-H atoms which were refined with anisotropic dis-
placement parameters by full-matrix least-squares rou-
tines against F2 (SHELXL-93 [21]). Hydrogen atoms
were placed in calculated positions and refined isotropi-
cally with fixed displacement parameters (riding model).
Acknowledgements
The authors would like to thank the Deutsche
Forschungsgemeinschaft and the Fonds der Chemi-
schen Industrie for financial support and the companies
Merck (Darmstadt) and Degussa (Hanau) for their
loaning of chemicals.
References
[1] J.H. Weber, G.N. Schrauzer, J. Am. Chem. Soc. 92 (1970) 726.
[2] (a) R. Dreos Garlatti, G. Tauzher, G. Costa, Inorg. Chim. Acta
121 (1986) 27. (b) B. Giese, J. Hartung, C. Kesselheim, H.J.
Lindner, I. Svoboda, Chem. Ber. 126 (1993) 1193. (c) F. Asaro,
R. Dreos Garlatti, G. Pellizer, G. Tauzher, Inorg. Chim. Acta
211 (1993) 27. (d) F. Asaro, G. Costa, R. Dreos, G. Pellizer, W.
von Philipsborn, J. Organomet. Chem. 513 (1996) 193.
5. Supplementary material available
Further details of the crystal structure analysis are

D. Steinborn et al. / Journal of Organometallic Chemistry 561 (1998) 191–197
197
[3] (a) D. Steinborn, M. Ludwig, J. Organomet. Chem. 463 (1993)
Press, Oxford, 1993, p. 357.
65. (b) A.M.A. Aisa, F.W. Heinemann, D. Steinborn, Z.
Anorg. Allg. Chem. 622 (1996) 1946. (c) D. Steinborn, L.
Yang, A.M.A. Aisa, J. Organomet. Chem. 526 (1996) 43. (d)
[14] N. Bresciani Pahor, R. Dreos-Garlatti, S. Geremia, L.
Randaccio, G. Tauzher, E. Zangrando, Inorg. Chem. 29 (1990)
3437.
8
M. Ludwig, L. Ohrstro¨m, D. Steinborn, Magn. Reson. Chem.
33 (1995) 984.
[15] (a) M. Dunaj-Jurco, V. Kettmann, D. Steinborn, M. Ludwig,
Acta Crystallogr. Sect. C 51 (1995) 210. (b) M. Dunaj-Jurco,
V. Kettmann, D. Steinborn, M. Ludwig, Acta Crystallogr.
Sect. C 50 (1994) 1427. (c) I. Potocnak, M. Dunaj-Jurco, M.
Ludwig, D. Steinborn, Acta Crystallogr. Sect. C 51 (1995)
1999. (d) M. Dunaj-Jurco, V. Kettmann, D. Steinborn, M.
Ludwig, Acta Crystallogr. Sect. C 50 (1994) 1239.
[16] (a) N. Bresciani Pahor, M. Forcolin, L.G. Marzilli, L.
Randaccio, M.F. Summers, P.J. Toscano, Coord. Chem. Rev.
63 (1985) 1. (b) L. Randaccio, N. Bresciani Pahor, E.
Zangrando, Chem. Soc. Rev. 18 (1989) 225.
[17] K.E. Linder, D.P. Nowotnik, M.F. Malley, J.Z. Gougoutas,
A.D. Nunn, Inorg. Chim. Acta 190 (1991) 249.
[18] T. Gilchrist, in: B. Trost, I. Flemming (Eds.), Comprehensive
Organic Synthesis, vol. 8, Pergamon Press, Oxford, 1991, p.
381.
[4] (a) D. Steinborn, M. Rausch, C. Bruhn, H. Schmidt, D.
Stro¨hl, J. Chem. Soc. Dalton Trans. (1998) 221. (b) M.
Rausch, C. Bruhn, D. Steinborn, Proc. 16th Conf. Coord.
Chem. Smolenice/Bratislava, 1997, 153.
[5] D. Steinborn, A.M.A. Aisa, F.W. Heinemann, S. Lehmann, J.
Organomet. Chem. 527 (1997) 239.
[6] R. Dreos Garlatti, G. Tauhzer, M. Blaschich, G. Costa, Inorg.
Chim. Acta 105 (1985) 129.
[7] F. Asaro, R. Dreos, S. Geremia, et al., J. Organomet. Chem.
525 (1996) 71.
[8] F.W. Heinemann, A.M.A. Aisa, D. Steinborn, Z. Kristallogr.
211 (1996) 837.
[9] R. Dreos, G. Tauhzer, S. Geremia, et al., Inorg. Chem. 33
(1994) 5404.
[10] G.N. Schrauzer, A. Ribeiro, L.P. Lee, R.K.Y. Ho, Angew.
Chem. 83 (1971) 849.
[19] P. Powell, J. Chem. Soc. (A) (1969) 2418.
[20] G.M. Sheldrick, SHELXS-86, Program for the Solution of
Crystal Structures, University of Go¨ttingen, Germany, 1986.
[21] G.M. Sheldrick, SHELXL-93, Program for the Refinement of
Crystal Structures, University of Go¨ttingen, Germany, 1993.
[11] S.M. Polson, L. Hanson, L.G. Marzilli, J. Am. Chem. Soc.
118 (1996) 4804.
[12] T. Ramasami, J.H. Espenson, Inorg. Chem. 19 (1980) 1846.
[13] A.F. Wells, Structural Inorganic Chemistry, 5th ed, Clarendon
.