Synthesis of RuHCl(CO)(Hdmpz)(L)2 (L=PPh3, AsPh3, and Hdmpz=3,5-dimethylpyrazole) and crystal structure of RuHCl(CO)(Hdmpz)(AsPh3)2

Article abstract of DOI:10.1016/S0277-5387(99)00179-5

Treatment of RuHCl(CO)(L)₃ with a slight excess amount of K[HB(3,5-Me₂pz)₃] in boiling MeOH solution yielded unusual 3,5-dimethylpyrzaole (Hdmpz) complexes, RuHCl(CO)(Hdmpz)(L)₂ (L=PPh₃, 1 or AsPh₃, 2). Unexpectedly the dissociation of the bonds between the boron atom and the nitrogen atoms of the potentially tridentate [HB(3,5-Me₂pz)₃]^- ligand during the coordination of the ligand to the Ru^II metal has been observed. In a separate preparation, the RuHCl(CO)(Hdmpz)(PPh₃)₂ complex has also been synthesized from the reaction between RuHCl(CO)(PPh₃)₃ and the monodentate Hdmpz ligand. Complexes 1 and 2 have been characterized by elemental analysis, IR and ¹H NMR spectroscopies. Compound 1 has also been prepared by the reaction between RuHCl(CO)(PPh₃)₃ and K[H₂B(3,5-Me₂pz)₂] in boiling toluene solution. The crystal structure of 2 has been studied by X-ray crystallography. The geometrical structure around Ru^II of 2 is a distorted octahedral structure. The crystal structure of 2 consists of a discrete monomeric compound. It is interesting to find that the sterically-demanding [HB(3,5-Me₂pz)₃]^- or [H₂B(3,5-Me₂pz)₂]^- ligands break up during the reaction with the Ru^II complexes to form the neutral 3,5-dimethylpyrazole complexes. In contrast to these observations, [H₂Bpz₂]^- and [H₂B(4-Brpz)₂]^- ligands form very stable Ru^II complexes. Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(99)00179-5

Polyhedron 18 (1999) 2625–2631
Synthesis of RuHCl(CO)(Hdmpz)(L)2 (L5PPh3, AsPh3, and Hdmpz53,5-
dimethylpyrazole) and crystal structure of RuHCl(CO)(Hdmpz)(AsPh3)2
*
Seong Huh, Youngmee Kim, Kyoung-Tae Youm, Moo-Jin Jun
Department of Chemistry, Yonsei University, Seoul 120-749, South Korea
Received 24 November 1998; accepted 2 June 1999
Abstract
Treatment of RuHCl(CO)(L)3 with a slight excess amount of K[HB(3,5-Me2pz)3] in boiling MeOH solution yielded unusual
3,5-dimethylpyrzaole (Hdmpz) complexes, RuHCl(CO)(Hdmpz)(L)2 (L5PPh3, 1 or AsPh3, 2). Unexpectedly the dissociation of the
bonds between the boron atom and the nitrogen atoms of the potentially tridentate [HB(3,5-Me2pz)3]2 ligand during the coordination of
the ligand to the RuII metal has been observed. In a separate preparation, the RuHCl(CO)(Hdmpz)(PPh3)2 complex has also been
synthesized from the reaction between RuHCl(CO)(PPh3)3 and the monodentate Hdmpz ligand. Complexes 1 and 2 have been
characterized by elemental analysis, IR and 1H NMR spectroscopies. Compound 1 has also been prepared by the reaction between
RuHCl(CO)(PPh3)3 and K[H2B(3,5-Me2pz)2] in boiling toluene solution. The crystal structure of 2 has been studied by X-ray
crystallography. The geometrical structure around RuII of 2 is a distorted octahedral structure. The crystal structure of 2 consists of a
discrete monomeric compound. It is interesting to find that the sterically-demanding [HB(3,5-Me2pz)3]2 or [H2B(3,5-Me2pz)2]2 ligands
break up during the reaction with the RuII complexes to form the neutral 3,5-dimethylpyrazole complexes. In contrast to these
observations, [H2Bpz2]2 and [H2B(4-Brpz)2]2 ligands form very stable RuII complexes.
reserved.
1999 Elsevier Science Ltd. All rights
Keywords: RuII complex; RuHCl(CO)(Hdmpz)(L)2; MeOH solution
1. Introduction
Using a more sterically-demanding ligand [HB(3,5-
Me2pz)3]2 (hydrotris(3,5-dimethylpyrazolyl)borate), we
have been interested in synthesizing such a complex, 3, in
which the [HB(3,5-Me2pz)3]2 ion is expected to coordi-
nate to the RuII as a tridentate ligand, in order to study its
asymmetric catalytic application. Here we report that,
rather than obtaining the expected poly(pyrazolyl)borate
complex of 3, the unexpected neutral pyrazole complexes,
RuHCl(CO)(Hdmpz)(L)2 (L5PPh3, 1; AsPh3, 2), have
been produced from the reaction between RuHCl(CO)(L)3
(L5PPh3 or AsPh3) and K[HB(3,5-Me2pz)3] in MeOH
solution. It is reported that, during the reaction, the bonds
between the boron atom and the nitrogen atoms of the
[HB(3,5-Me2pz)3]2 ligand have been dissociated and that
the [HB(3,5-Me2pz)3]2 ligand has been found to be
coordinated to the RuII ion as neutral monodentate 3,5-
dimethylpyrazole molecules to give 1 and 2 (Scheme 1). It
will be shown that, as a way to obtain a standard complex,
the RuHCl(CO)(Hdmpz)(PPh3)2 complex has also been
Recent research on the poly(pyrazolyl)borate RuII com-
plexes is an interesting area because these complexes can
be applied to the homogeneous catalysis especially in the
asymmetric synthesis [1–5]. From time to time, however,
unexpected complexes bearing only neutral pyrazoles or
anionic pyrazolides which result from the dissociation of
the poly(pyrazolyl)borate ligand have been obtained [6,7].
The RuII complex with an anionic tridentate poly-
(pyrazolyl)borate ligand, RuH(CO)(PPh3)(h3-HBpz3)
([HBpz3]25hydrotris(pyrazolyl)borate), has been prepared
from the reaction of RuHCl(CO)(PPh3)3 with Na[HBpz3]
in toluene under reflux condition. In this preparative
reaction the [HBpz3]2 ion has not been dissociated and has
coordinated to the RuII metal center as a tridentate ligand
(Scheme 1) [8].
prepared
directly
from
the
reaction
between
RuHCl(CO)(PPh3)3 and the monodentate Hdmpz ligand
(Scheme 2).
*Corresponding author. Tel.: 182-1-361-2639; fax: 182-1-364-7050.
E-mail address: mjjun@alchemy.yonsei.ac.kr (M-J. Jun)
0277-5387/99/$ – see front matter
PII: S0277-5387(99)00179-5
1999 Elsevier Science Ltd. All rights reserved.

2626
S. Huh et al. / Polyhedron 18 (1999) 2625–2631
Scheme 1.
2. Experimental
K[HB(3,5-Me2pz)3] [12] and K[H2B(3,5-Me2pz)2] [3]
have been prepared using previously published literature
methods. RuCl3?3H2O, PPh3, AsPh3, KBH4, and 3,5-
dimethylpyrazole (Hdmpz) have been supplied by Aldrich
and used as received. 1H NMR spectra were recorded on a
2.1. Materials and instruments
RuHCl(CO)(PPh3)3 [10], RuHCl(CO)(AsPh3)3 [11],
Scheme 2.

S. Huh et al. / Polyhedron 18 (1999) 2625–2631
2627
Bruker Avance/DPX 250 spectrometer at 250.13 MHz and
referenced to internal SiMe4. Microanalyses were per-
formed using Vario EL (Elementar Analysensysteme
GmbH) by the Korea Basic Science Institute, Seoul, South
Korea. Melting points were determined on a MEL-TEMP
II apparatus. All melting points are uncorrected.
from CHCl3 gave yellow block crystals (Yield: 264 mg,
60%). M.p. 1828C (decomposed). Anal. Calcd for
C42H39As2ClN2ORu: C, 57.7; H, 4.50; N, 3.20. Found: C,
56.9; H, 4.53; N, 2.95%. IR (KBr, cm21): 3209 (NH, m),
3053, 2044 (RuH, m), 1931 (CO, vs), 1570 (CN, m), 1480,
1434, 1310, 1275, 1182, 1078, 1027, 999, 841, 802, 740,
1
694, 623, 594, 540, 471 (RuAs, s). H NMR (d, CDCl3,
208C, 250 MHz): 11.6 (s, NH, 1H), 7.5 (m, 2C6H5, 10H),
7.3 (m, 4C6H5, 20H), 5.2 (s, CH, 1H), 1.7 (s, CH3, 3H),
1.6 (s, CH3, 3H), 214.3 (s, RuH, 1H).
2.2. Synthesis: Complex 1
2.2.1. Method A
A suspension of RuHCl(CO)(PPh3)3 (480 mg, 0.5
mmol) and K[HB(3,5-Me2pz)3] (237 mg, 0.7 mmol) in 30
ml of degassed MeOH was heated under reflux for 1 h in
nitrogen atmosphere. The reaction mixture was cooled to
room temperature and evaporated to dryness at a rotary
evaporator at room temperature. The resultant crude prod-
uct was dissolved in CHCl3 (ca. 2 ml) and filtered to
remove insolubles. The filtrate was transferred into a small
capped vial and recrystallized in air by slow evaporation.
After several days yellow block-shaped crystals were
formed, which were separated from the mother liquor,
washed with n-hexane and dried in air (Yield: 295 mg,
2.4. X-ray data collection and refinement
Crystals of 2 suitable for X-ray study were grown from
acetone in a small capped vial at room temperature by
slow evaporation of the solvent. Yellow well-faced block
crystals were obtained, which were separated, washed with
n-hexane and air-dried. The crystals of 2 are indefinitely
air-stable in the solid state for several months. A crystal
(0.530.530.4 mm) was mounted on an Enraf-Nonius
CAD-4 Mach3 diffractometer equipped with a mono-
chromator and molybdenum radiation. Unit cell dimen-
sions were determined by least-squares refinement of 25
intense reflections (9.05#u#11.78). Data were collected
at ambient temperature [293(2) K] in v/2u scan mode
using variable rates for the range 0#h#11, 0#k#19,
229#l#29, and three standard reflections measured after
every hour did not reveal any systematic variations in
intensity. Intensities were corrected for Lorentz and polari-
zation effects but not for absorption. The crystal structure
was determined by the conventional heavy atom method
and Fourier techniques. All non-hydrogen atoms were
refined anisotropically and hydrogen atoms except the
hydride were located in the calculated positions. All the
calculations were performed on IBM Pentium computer
using SHELXS-97 [13] and SHELXL-97 [14] and atomic
scattering factors for all non-hydrogen atoms were sup-
plied by the SHELXS-97. Detailed crystal parameters and
procedural information corresponding to data collection
and structure refinement are collected in Table 1.
1
75%). The IR and H NMR spectra found are in accord-
ance with the literature data [9].
2.2.2. Method B
A suspension of RuHCl(CO)(PPh3)3 (480 mg, 0.5
mmol) and K[H2B(3,5-Me2pz)2] (145 mg, 0.7 mmol) in
40 ml of dried toluene was heated under reflux for 14 h in
nitrogen atmosphere. The reaction mixture was cooled to
room temperature and filtered to remove any insolubles.
The filtrate was evaporated to dryness by rotary evaporator
at room temperature. The acetone solution dissolving the
residue was stored in a small capped vial in air. After
about a week, well-formed yellow block crystals were
obtained, washed with n-hexane and air-dried. Anal.
Calcd. for C42H39ClN2OP2Ru: C, 64.2; H, 5.00; N, 3.56.
1
Found: C, 63.2; H, 4.86; N, 3.31%. The IR and H NMR
spectra found are in accordance with the literature data [9].
2.2.3. Method C
A suspension of RuHCl(CO)(PPh3)3 (480 mg, 0.5
mmol) and Hdmpz (145 mg, 0.7 mmol) in 40 ml of
absolute EtOH was heated under reflux for 15 h in nitrogen
atmosphere. The reaction mixture was cooled to room
temperature and filtered to obtain white powder. The
product was washed with EtOH and Et2O and dried in
3. Results and discussion
Using the anionic tridentate hydrotris(pyrazolyl)borate
ligand, [HBpz3]2, Sun and Simpson [8] has prepared a
h3-type complex of RuH(CO)(PPh3)(h3-HBpz3) from the
reaction between RuHCl(CO)(PPh3)3 and [HBpz3]2, in
which the [HBpz3]2 ligand has, as expected, coordinated
to the metal center as a tridentate ligand.
1
vacuo (Yield: 349 mg, 88%). The IR and H NMR spectra
found are in accordance with the literature data [9].
Using the anionic hydrotris(3,5-dimethylpyrazolyl)bo-
rate ligand, [HB(3,5-Me2pz)3]2, we have been interested
in synthesizing a h3-type complex of RuH(CO)(L)(h3-
HB(3,5-Me2pz)3) (L5PPh3 or AsPh3) from the reaction
between RuHCl(CO)(L)3 and [HB(3,5-Me2pz)3]2. Since
the [HBpz3]2 and [HB(3,5-Me2pz)3]2 ligands are quite
2.3. Complex 2
This compound was prepared by Method A using
RuHCl(CO)(AsPh3)3 (520 mg, 0.5 mmol) in place of
RuHCl(CO)(PPh3)3. Recrystallization of the crude product

2628
S. Huh et al. / Polyhedron 18 (1999) 2625–2631
Table 1
Crystal data and structure refinement for 2, RuHCl(CO)(Hdmpz)(AsPh3)2
Empirical formula
Formula weight
Wavelength
C42H39As2ClN2ORu
874.11
0.71073 A
˚
Crystal system, space group
Unit cell dimensions
monoclinic, P21 /n (No.14)
˚
a59.7582(10) A
˚
b516.1088(10) A
˚
c524.7288(10) A
b594.637(10)8
3
˚
Volume
3874.5(5) A
Z
4
Calculated density
Absorption coefficient
F(000)
1.499 Mg/m3
2.203 mm21
1760
u range for data collection
Reflections collected/unique
Completeness to 2u524.97
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I.2s(I)]
R indices (all data)
Absolute structure parameter
Largest diff. peak and hole
2.08 to 24.978
7091/6679 [R(int)50.0315]
98.2%
Full-matrix least-squares on F2
6679/0/448
1.087
R1a50.0420, wR2b50.1090
R1a50.0773, wR2b50.1222
10 (10)
1.084 and 21.397 e A
23
˚
a R1 5SuuFou2uFcuu/Su Fou.
b wR2 5[Sw(uFou2uFcu)2 /SwuFou2]1 / 2; w51/[s2(Fo2)1(0.05813P)214.833P]; P5(Fo2123Fc2)/3.
similar except for the fact that the latter ligand has two
methyl groups substituted at the 3 and 5 positions of the
pyrazole ring, it has been anticipated that the [HB(3,5-
Me2pz)3]2 ligand would coordinate to the RuII ion as a
tridentate ligand to give the expected h3-type complex
(Scheme 1).
reaction between RuHCl(CO)(PPh3)3, RuCl2(PPh3)3, or
RuHCl(PPh3)3 and 1-hydroxymethyl-3,5-dimethylpyrazole
in EtOH or benzene (Scheme 2). Surprisingly, they found
that the 1-hydroxymethyl group of the pyrazole had been
substituted by the hydrogen atom. The X-ray structure
determination shows that two PPh3 ligands are mutually
trans-positioned in the apical positions and the remaining
ligands occupy the equatorial positions, while the chloride
ion is located trans to the hydride. As mentioned earlier,
the RuHCl(CO)(Hdmpz)(PPh3)2 complex has been syn-
thesized in this work from the reaction between
RuHCl(CO)(PPh3)3 and the monodentate pyrazole,
Hdmpz (Scheme 2).
In our work, however, treatment of the monomeric RuII
complexes, RuHCl(CO)(PPh3)3 or RuHCl(CO)(AsPh3)3,
with a potentially tridentate ligand, K[HB(3,5-Me2pz)3], in
boiling MeOH solution has unexpectedly yielded the 3,5-
dimethylpyrazole complexes of RuHCl(CO)(Hdmpz)(L)2
(L5PPh3, 1 or AsPh3, 2) instead of the expected
RuH(CO)(L)(h3-HB(3,5-Me2pz)3), which would have
been obtained if the [HB(3,5-Me2pz)3]2 ligand has coordi-
nated to the RuII ion as a tridentate ligand (Scheme 1). In
this work, the dissociation of the bonds between the boron
atom and the nitrogen atoms of the [HB(3,5-Me2pz)3]2
ligand during the coordination of the ligand to the RuII ion
has been observed and the [HB(3,5-Me2pz)3]2 ligand had
resulted in coordinating to the metal center as a neutral
monodentate 3,5-dimethylpyrazole. Rather than using the
potentially tridentate [HB(3,5-Me2pz)3]2 ligand, on the
other hand, the complex RuHCl(CO)(Hdmpz)(PPh3)2 it-
self has also been prepared in this work directly from the
reaction between RuHCl(CO)(PPh3)3 and the monodentate
Hdmpz in ethanol as shown in Scheme 2. The complex
RuHCl(CO)(Hdmpz)(PPh3)2 obtained in this way has
turned out to be exactly the same as 1.
The IR spectra of crystalline 1 and 2 show no charac-
teristic bands of BH group; instead, n(NH) stretching
bands appear at 3193 and 3209 cm21, respectively. From
the IR data, we could easily find out the breakage of the
1
[HB(3,5-Me2pz)3]2 ligand. The H NMR spectrum of 1 is
in
accordance
with
the
data
of
RuHCl(CO)(Hdmpz)(PPh3)2 prepared by other workers
1
[9]. From the H NMR spectrum of 2, which shows the
same pattern as that of 1, the structure of 2 could be
assumed to be the same as 1.
In order to compare its solid structure with that of 1, the
crystal structure of 2 has been studied. The geometrical
structure around RuII of 2 is the same as that of 1. The
crystal structure of 2 consists of a discrete monomeric
compound. Fundamentally, its ligand geometry is the same
as 1. Selected bond distances and angles are compared
with 1 in Table 2. The unit cell of 2 contains four
molecules. In fact, there are few structural comparison data
Using 1-hydroxymethyl-3,5-dimethylpyrazole, Romero
et al. [9] has obtained RuHCl(CO)(Hdmpz)(PPh3)2, which
turns out to be exactly the same as our complex 1, from the

S. Huh et al. / Polyhedron 18 (1999) 2625–2631
2629
Table 2
considered as the resonance form (i) relative to form (ii)
[17].
˚
Comparison of the selected bond lengths (A) and angles (8) for
RuHCl(CO)(Hdmpz)(PPh3)2 (1) and RuHCl(CO)(Hdmpz)(AsPh3)2 (2)a
Bonds
L5P or As
1
2
(i) Ru 5 C 5 O ↔ (ii) Ru–C ; O
Ref. [4]
This work
Coordination sphere
Ru(1)–L(1)
Ru(1)–L(2)
Ru(1)–N(1)
Ru(1)–C(1)
Ru(1)–Cl(1)
Ru(1)–H(1)
Such resonance phenomenon has been considered because
2.344(3)
2.4189(7)
the
allenylidene
complex,
[RuCp(5C5C5
2.345(3)
2.174(8)
1.816(11)
2.568(3)
1.58(10)
2.4234(7)
2.174(4)
1.820(6)
2.5565(15)
1.41(7)
CPh2)(PMe3)2]1, showed the Ru–C bond distance of
˚
1.884(5) A which was described as a Ru5C bond [18].
Therefore, the Ru–CO bond distance of 2 is close to the
form (i), namely, the Ru5C bond type. In contrast, the
phosphine analog, RuHCl(CO)(Hdmpz)(PPh3)2 also
Pyrazole ring
N(1)–N(2)
N(1)–C(40)
N(2)–H(2)
N(2)–C(38)
C(38)–C(39)
C(38)–C(42)
C(39)–C(40)
C(40)–C(41)
˚
shows the bond distance of 1.816(11) A for Ru–CO [9].
1.356(11)
1.353(12)
1.186(8)
1.339(13)
1.375(15)
1.517(16)
1.398(15)
1.518(15)
1.344(6)
1.342(7)
0.860
1.345(7)
1.356(9)
1.494(9)
1.381(8)
1.490(8)
˚
The Ru–As distances (2.4189(7) and 2.4234(7) A) are
longer than the phosphine analog which shows 2.344(3)
˚
and 2.345(3) A distances of the Ru–P bonds. This can be
expected considering the different covalent radii of arsenic
and phosphorus atoms. Two AsPh3 ligands adopt an
eclipsed configuration based on the ipso carbon atoms as in
˚
Fig. 2. The Ru–N distance (2.174(4) A) is the same as the
C(1)–O(1)
1.140(15)
1.142(7)
phosphine analog within esds. There is an intramolecular
hydrogen bond between the chloride and the pyrazolyl
hydrogen, N(2)–H(2) . . . Cl(1), as shown in Figs. 1 and 2.
The plane defined by Ru(1), N(1), N(2), H(2), and Cl(1)
is an almost perfect plane. The deviation from the root
Mean L–C
Mean C–C (Ph)
1.847(10)
1.380(17)
1.947(5)
1.374(9)
Coordination sphere
Cl(1)–Ru(1)–L(1)
Cl(1)–Ru(1)–L(2)
Cl(1)–Ru(1)–C(1)
Cl(1)–Ru(1)–N(1)
Cl(1)–Ru(1)–H(1)
L(1)–Ru(1)–L(2)
L(1)–Ru(1)–C(1)
L(1)–Ru(1)–N(1)
L(1)–Ru(1)–H(1)
L(2)–Ru(1)–C(1)
L(2)–Ru(1)–N(1)
L(2)–Ru(1)–H(1)
C(1)–Ru(1)–N(1)
C(1)–Ru(1)–H(1)
N(1)–Ru(1)–H(1)
90.7(1)
93.0(1)
102.1(4)
86.5(2)
162.8(10)
176.13(9)
90.4(4)
91.2(2)
93.8(10)
89.9(4)
92.33(4)
89.76(4)
100.2(2)
87.18(12)
˚
mean squares plane is only 0.0097 A. Although we could
not get the clear position of H(2) of the pyrazole ring, it
was fixed by the program, the donor–acceptor distance of
174(3)
˚
3.070 A (/ N(2)–H(2) . . . Cl(1)5130.098) is in accord-
176.83(2)
90.76(19)
87.22(12)
92(3)
91.22(19)
90.50(12)
86(3)
172.5(2)
83(3)
89(3)
ance with the reported values of N–H . . . Cl hydrogen
bonds whose donor–acceptor lengths usually range from
˚
˚
2.91 to 3.52 A (mean value53.21 A) [19].
The Hdmpz ligand is planar as expected. The root mean
88.0(2)
˚
squares deviations of the ring is only 0.0043 A. The angle
82.1(10)
171.2(4)
93.4(10)
77.8(10)
made by the equatorial coordination sphere (Ru(1), H(1),
C(1), Cl(1) and N(1)) and the Hdmpz ligand is only
2.39(20)8. The equatorial plane including Ru(1) is also a
perfect plane. Ru(1) resides at slightly below this plane,
Pyrazole ring
˚
20.0136(159) A.
N(1)–N(2)–C(38)
N(2)–N(1)–C(40)
N(1)–C(40)–C(39)
N(2)–C(38)–C(39)
C(38)–C(39)–C(40)
112.4(8)
105.2(8)
109.4(9)
106.5(9)
106.5(9)
112.1(5)
105.1(4)
109.7(5)
106.0(5)
107.0(5)
It is interesting to observe in this work that the bonds
between the boron atom and nitrogen atoms in the
[HB(3,5-Me2pz)3]2 or [H2B(3,5-Me2pz)2]2 ions, usually
multidentate ligands, have been dissociated during the
reaction of the ligand with RuHCl(CO)(PPh3)3 or
RuHCl(CO)(AsPh3)3, and the [HB(3,5-Me2pz)3]2 or
[H2B(3,5-Me2pz)2]2 ligands have resulted in coordinating
to RuII as a neutral monodentate 3,5-dimethylpyrazole to
give, respectively, RuHCl(CO)(Hdmpz)(PPh3)2, 1, or
RuHCl(CO)(Hdmpz)(AsPh3)2, 2. As a way to obtain a
standard complex, the RuHCl(CO)(Hdmpz)(PPh3)2 com-
plex has also been prepared directly from the reaction
between RuHCl(CO)(PPh3)3 and the monodentate Hdmpz
ligand. At this stage it is not clear how the [HB(3,5-
Me2pz)3]2 ion has resulted in coordinating to the metal
center as a neutral monodentate 3,5-dimethylpyrazole
during the preparation reactions of 1 and 2. In fact, it is
Mean C–L–C
Mean C–C–C(Ph)
Mean Ru–L–C
103.1(4)
120.0(10)
115.3(3)
102.27(2)
120.0(6)
116.0(16)
a Atoms are labeled in accordance with Fig. 1. Numbers in parentheses
are the estimated standard deviations in the least significant figure.
between phosphine and arsine analogs. Perspective views
of 2 are shown in Figs. 1 and 2, respectively.
˚
The Ru–CO bond distance (1.820(6) A) is normal for a
monomeric RuII carbonyl complex. Ru–CO bond distances
˚
A
generally range from 1.74 to 1.98
[15,16]. In
[RuCp(CO)(PPh3)2]1 (Cp5cyclopentadienyl ring), for
˚
example, the distance of Ru–CO (1.869(2) A) has been

2630
S. Huh et al. / Polyhedron 18 (1999) 2625–2631
Fig. 1. ORTEP view (50% probability) of 2 with atom numbering. All nonhydrogen atoms have been refined anisotropically. H-atoms are eliminated for
the sake of clarity except for the hydride and the H(2) with arbitrary small circles. Intramolecular hydrogen bond is shown as a dotted line.
really possible for the ligand to hydrolyze in alcoholic
solution. However, the reaction between the bidentate
ligand, [H2B(3,5-Me2pz)2]2, and RuHCl(CO)(PPh3)3 in
dried toluene solution has also produced 1 as a sole
product. We can, therefore, only speculate that (1) the
[HB(3,5-Me2pz)3]2 ligand may dissociate first to generate
the free pyrazole molecules, which subsequently coordi-
nate to the RuII center, or (2) the [HB(3,5-Me2pz)3]2
ligand coordinate to the metal center via h2- or h3-mode
and then breaks up to produce the complex 1 or 2. Further
work is under way to find out whether (1) or (2) is more
feasible for the results observed in our work. It is worth
mentioning that [H2Bpz2]2 and [H2B(4-Brpz)2]2 ligands
form very stable RuII complexes [20,21].
Supplementary data
Supplementary data (excluding structure factors) are
available from the Cambridge Crystallographic Data Cen-
tre, 12 Union Road, Cambridge CB2 IEZ, UK on request,
quoting the deposition number CCDC-103226.
Acknowledgements
We are indebted to Professor K. Shin (Sejong Universi-
ty) for the use of the diffractometer. We are also grateful to
the Basic Science Research Institute Program, Ministry of
Education of the Republic of Korea, Grant No. BSRI-97-
3426 for financial support.
Fig. 2. Perspective view of 2 with As(1)–Ru(1)–As(2) axis down.
Intramolecular hydrogen bond is represented as a dotted line. Only ipso
carbon atoms of phenyl rings are shown for clarity.

S. Huh et al. / Polyhedron 18 (1999) 2625–2631
2631
[12] S. Trofimenko, J. Am. Chem. Soc. 89 (1967) 6288.
[13] G.M. Sheldrick, SHELXS-97, A Program for Structure Determi-
References
¨
¨
nation, University of Gottingen, Gottingen, Germany, 1990.
[1] S. Trofimenko, Chem. Rev. 93 (1993) 943.
[2] S. Trofimenko, Chem. Rev. 4 (1971) 17.
[14] G.M. Sheldrick, SHELXL-97, A Program for Structure Refinement,
University of Gottingen, Gottingen, Germany, 1997.
[15] M.P. Garcıa, A.M. Lopez, M.A. Esteruelas, F.J. Lahoz, L.A. Oro, J.
Organomet. Chem. 388 (1990) 365.
[16] W.R. Roper, G.E. Taylor, J.M. Waters, L.J. Wright, J. Organomet.
Chem. 182 (1979) C46.
[17] J.M. Wisner, T.J. Bartczak, J.A. Ibers, Inorg. Chim. Acta 100 (1985)
115.
[18] J.P. Selegue, Organometallics 1 (1982) 217.
[19] G.A. Jeffrey, W. Saenger (Eds.), Hydrogen Bonding in Biological
Structures, Springer-Verlag, Berlin, Germany, 1991, p. 29.
[20] S. Huh, Y. Kim, Y. Park, K.-T. Youm, M.-G. Choi, M.-J. Jun, Inorg.
Chim. Acta (1999) submitted.
¨
¨
[3] S. Trofimenko, J. Am. Chem. Soc. 89 (1967) 3170.
[4] S. Trofimenko, Prog. Inorg. Chem. 34 (1986) 115.
[5] H. Brunner, U.P. Singh, T. Boeck, S. Altmann, T. Scheck, B.
Wrackmeyer, J. Organomet. Chem. 443 (1993) C16.
[6] M.M. Taqui Khan, P.S. Roy, K. Venkatasubramanian, N.H. Khan,
Inorg. Chim. Acta 176 (1990) 49.
[7] C.J Jones, J.A. McCleverty, A.S. Rothin, J. Chem. Soc., Dalton
Trans. (1986) 109.
[8] N.-Y. Sun, S.J. Simpson, J. Organomet. Chem. 434 (1992) 341.
[9] A. Romero, A. Vegas, A. Santos, J. Chem. Soc., Dalton Trans.
(1987) 183.
´
´
[10] N. Ahmad, J.J. Levinson, S.D. Robinson, M.F. Uttely, Inorg. Synth.
15 (1974) 48.
[21] S. Huh, Y. Kim, S. Park, T.-J. Park, M.-J. Jun, Acta Crystallogr.
(1999) in press.
´
[11] R.A. Sanchez-Delgado, W.Y. Lee, Y. Cho, M.-J. Jun, S.R. Choi,
Transition Met. Chem. 16 (1990) 241.