Influence of the bridging ligand on the substitution chemistry of neutral and cationic triruthenium carbonyl cluster complexes derived from 1,1-dimethylhydrazine

Article abstract of DOI:10.1016/S0020-1693(02)01493-7

The reactivity of the neutral triruthenium carbonyl cluster [Ru ₃(μ-H)(μ₃-HNNMe₂)(CO)₉] (1) and its protonated derivative [Ru₃(μ-H)₂(μ ₃-HNNMe₂)(CO)₉][BF₄] (2), both containing a face-capping 5-electron donor 1,1-dimethylhydrazido ligand, with triphenylphosphane has been studied. Compound 1 gives a mixture of two non-interconvertible isomeric carbonyl substitution products [Ru ₃(μ-H)(μ₃-HNNMe₂)(CO) ₈(PPh₃)] which bear the phosphane ligand attached to the same Ru atom as either the NMe₂ (3a) or the NH fragments (3b). Protonation of the 3a and 3b mixture with [HOEt₂][BF₄] gives a mixture of two non-interconvertible isomeric cationic dihydrido derivatives [Ru₃(μ-H)₂(μ₃-HNNMe₂)(CO) ₈(PPh₃)][BF₄] (4a and 4b) which maintain the phosphane ligand in the same position as their neutral precursors. Compound 4a can be selectively prepared from complex 2 and triphenylphosphane. Deprotonation of complex 4a with triethylamine gives compound 3a, selectively. These results contrast with those previously known for carbonyl substitution reactions on triruthenium clusters isostructural with compounds 1 and 2 but containing other face-capping five-electron donor ligands. The hardness of the bridging ligand is presented as an important factor in relation to the observed regioselectivity. The X-ray structures of compounds 2 and 4a are reported.

Full text of DOI:10.1016/S0020-1693(02)01493-7

Inorganica Chimica Acta 350 (2003) 93ꢁ100
/
www.elsevier.com/locate/ica
Influence of the bridging ligand on the substitution chemistry of
neutral and cationic triruthenium carbonyl cluster complexes derived
from 1,1-dimethylhydrazine
Javier A. Cabeza a,*, Ignacio del R´ıo a, Santiago Garc´ıa-Granda b,
Lorena Mart´ınez-Me´ndez a, V´ıctor Riera a
a Departamento de Qu´ımica Orga´nica e Inorga´nica, Instituto de Qu´ımica Organometa´lica ‘‘Enrique Moles’’, Universidad de Oviedo-CSIC,
E-33071 Oviedo, Spain
b Departamento de Qu´ımica-F´ısica y Anal´ıtica, Universidad de Oviedo, E-33071 Oviedo, Spain
Received 3 May 2002; accepted 3 June 2002
Dedicated to Professor Pierre Braunstein, an outstanding organometallic cluster chemist.
Abstract
The reactivity of the neutral triruthenium carbonyl cluster [Ru3(m-H)(m3-HNNMe2)(CO)9] (1) and its protonated derivative
[Ru3(m-H)2(m3-HNNMe2)(CO)9][BF4] (2), both containing a face-capping 5-electron donor 1,1-dimethylhydrazido ligand, with
triphenylphosphane has been studied. Compound 1 gives a mixture of two non-interconvertible isomeric carbonyl substitution
products [Ru3(m-H)(m3-HNNMe2)(CO)8(PPh3)] which bear the phosphane ligand attached to the same Ru atom as either the NMe2
(3a) or the NH fragments (3b). Protonation of the 3a and 3b mixture with [HOEt2][BF4] gives a mixture of two non-interconvertible
isomeric cationic dihydrido derivatives [Ru3(m-H)2(m3-HNNMe2)(CO)8(PPh3)][BF4] (4a and 4b) which maintain the phosphane
ligand in the same position as their neutral precursors. Compound 4a can be selectively prepared from complex 2 and
triphenylphosphane. Deprotonation of complex 4a with triethylamine gives compound 3a, selectively. These results contrast with
those previously known for carbonyl substitution reactions on triruthenium clusters isostructural with compounds 1 and 2 but
containing other face-capping five-electron donor ligands. The hardness of the bridging ligand is presented as an important factor in
relation to the observed regioselectivity. The X-ray structures of compounds 2 and 4a are reported.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Ruthenium; Ruthenium clusters; Carbonyl substitution reactions; 1,1-Dimethylhydrazine; Crystal structures
1. Introduction
substitution cannot be predicted in many occasions,
since it seems to be strongly influenced by the cluster
structure and by the remaining ligands of the complex.
In this field, we have previously reported the carbonyl
substitution chemistry of the cluster complexes [Ru3(m-
H)(m3-HNCONMe2)(CO)9] (A) [2], [Ru3(m-H)(m3-am-
The substitution of a phosphane ligand for a CO
ligand in carbonyl metal clusters is a common reaction
[1]. However, despite the great number of such reactions
reported to date, for a given cluster complex, the precise
coordination site that is prone to undergo a carbonyl
py)(CO)9] (B; Hampyꢀ
7] and the protonated derivative [Ru3(m-H)2(m3-am-
py)(CO)9][BF4] (C) [3ꢁ7] (Scheme 1). These compounds
/
2-amino-6-methylpyridine) [3ꢁ
/
/
contain face-capping five-electron donor ligands at-
tached to the three ruthenium atoms through two
* Corresponding author. Tel.: ꢂ
446.
E-mail address: jac@sauron.quimica.uniovi.es (J.A. Cabeza).
/
34-98-5103 501; fax: ꢂ34-98-5103
/
heteroatoms. Without exceptions, complexes AꢁC un-
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0020-1693(02)01493-7

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2. Results and discussion
2.1. Synthesis of compounds 1 and 2
The compound [Ru3(m-H)(m3-HNNMe2)(CO)9] (1)
was prepared from [Ru3(CO)12] and 1,1-dimethylhydra-
zine, as described by Vahrenkamp [9], using a modifica-
tion of the general method proposed by Suss-Fink et al.
¨
for the synthesis of other hydrazido derivatives of
[Ru3(CO)12] [8]. Its IR and 1H NMR spectroscopic
data are given in Tables 1 and 2, respectively, in order to
allow comparisons with the spectra of its derivatives.
The use of 1,1-dimethylhydrazine was decided because
the presence of two methyl groups on the same nitrogen
atom would lead to a symmetric triruthenium derivative,
with a statistically simpler regioreactivity than that of
asymmetric derivatives, and with reaction products
1
easily traceable by H NMR.
Protonation of compound 1 with [HOEt2][BF4] in
dichloromethane afforded the cationic derivative
[Ru3(m-H)2(m3-HNNMe2)(CO)9][BF4] (2) in quantitative
yield (Scheme 2). Its room temperature 1H NMR
spectrum showed only three singlet resonances (Table
2), assignable to the NH proton, the methyls and the
hydrides, suggesting a CS symmetry for the complex.
This surprised us because the related complex [Ru3(m-
H)2(m3-ampy)(CO)9][BF4] (C) is asymmetric both in the
solid state and in solution at room temperature [3]. In
addition, the carbonyl region of its IR spectrum (Table
1), that is comparable with that of C [3], showed the
n(CO) absorptions shifted to higher wavenumbers than
those of complex 1, as expected for a higher formal
oxidation state of the metal atoms.
Scheme 1.
dergo substitution of a phosphane ligand for a CO
ligand at an equatorial site on a ruthenium atom
attached to both a hydride and the amido fragment of
the bridging ligand (Scheme 1). This regioselectivity has
been associated with the cis-labilizing effect provoked
by the hardness of both the amido and hydride ligands
[3,4].
An X-ray diffraction study, commented below, de-
termined that compound 2 is asymmetric in the solid
state and suggested that the complex might be stereo-
chemically non rigid in solution. This was confirmed by
1
a variable temperature H NMR study, from which a
small activation DG% parameter of 9.1 kcal molꢃ1 was
estimated from the coalescence temperature [10]. Fig. 1
In 1990, Suss-Fink et al. published the synthesis of
¨
several triruthenium carbonyl derivatives of the type
[Ru3(m-H)(m3-HNNR1R2)(CO)9] by treatment of
[Ru3(CO)12] with hydrazines [8]. To date, no phosphane
derivative chemistry of these cluster complexes has been
reported. These compounds are isostructural with com-
plexes A and B, but their face-capping five-electron
donor ligands are hydrazido fragments, which are
harder than ureato and 2-amidopyridine fragments.
This fact prompted us to study the CO substitution
chemistry of [Ru3(m-H)(m3-HNNMe2)(CO)9] (1) and its
Table 1
Selected IR data for the new complexes
Compound n(CO) (cmꢃ1
)
1 a
2079 (m), 2049 (s), 2021 (s), 2001 (m), 1958 (w), 1942 (w)
2138 (m), 2102 (s), 2085 (s), 2067 (m), 2039 (m), 2027 (m)
2061 (m), 2023 (s), 1999 (m), 1979 (m), 1958 (m)
1984 (m), 1930 (w)
2 b
3a b
3b b,c
4a b
4b b,d
2130 (m), 2082 (s), 2059 (m), 2031 (m), 2003 (m), 1957 (m)
2100(w), 2074 (s), 2020 (m)
protonated
(CO)9][BF4] (2), in order to compare it with that known
for the derivatives AꢁC and to draw some conclusions
derivative
[Ru3(m-H)2(m3-HNNMe2)-
a
In THF.
In CH2Cl2.
Data extracted from the spectrum of a 1:1 mixture of 3a and 3b;
b
c
/
on the influence of ligand electronic factors (hardness) in
the regioselectivity of CO substitution reactions by
phosphane ligands on carbonyl cluster complexes.
only the absorptions that do not overlap with those of 3a are given.
d
Data extracted from the spectrum of a 1:1 mixture of 4a and 4b;
only the absorptions that do not overlap with those of 4a are given.

J.A. Cabeza et al. / Inorganica Chimica Acta 350 (2003) 93ꢁ
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95
Table 2
1H and 31P NMR data for the new complexesa
Complex
1H NMR
NH
31P{1H} NMR
Me2
m-H
PPh3
1 b
4.87 (s)
7.32 (s)
4.77 (s)
4.88 (s)
7.07 (s)
7.28 (s)
2.62 (s)
3.00 (s)
ꢃ
/
13.06 (s)
2 c
ꢃ
/
14.71 (s)
3a b
3b b,d
4a c
4b c,e
2.53 (s), 1.77 (s)
2.53 (s)
ꢃ
/
12.25 (d) {10.3}
7.55 (m)
7.55 (m)
7.52 (m)
7.50 (m)
26.9 (s)
33.8 (s)
27.3 (s)
41.0 (s)
ꢃ
/
12.00 (d) {9.8}
3.06 (s), 2.31 (s)
3.06 (s)
ꢃ
/
13.78 (t) [3.1] {3.1}, ꢃ
/
14.60 (dd) [3.1] {9.3}
ꢃ
/
12.90 (d) {6.0}, ꢃ15.22 (d) {7.9}
/
a
Spectra run at room temperature; multiplicities are given in parentheses; coupling constants are given within square brackets [J(HÃH)] or braces
{J(HÃP)} in Hz.
b
In CDCl3.
In CD2Cl2.
c
d
e
Data extracted from the spectrum of a 1:1 mixture of 3a and 3b.
Data extracted from the spectrum of a 1:1 mixture of 4a and 4b.
Scheme 2.
Fig. 2. Structure of the cationic part of compound 2 (only one of the
two independent cations found in the solid is shown). Ellipsoids are
drawn at the 50% probability level.
Fig. 2 shows a view of complex 2 in the solid state. A
selection of bond lengths and angles for the two
crystallographically independent clusters found in the
crystals is given in Table 3. The cation can be described
as a triangle of ruthenium atoms bonded to nine CO
groups (three to each metal atom) and to the nitrogen
atoms of a 1,1-dimethylhydrazido ligand. While the NH
Fig. 1. Variable temperature 1H NMR spectra of compound 2 in the
hydride region (400 MHz, CD2Cl2).
fragment of this ligand bridges the Ru(1)Ã
the NMe2 fragment is attached to the Ru(3) atom. Two
hydride ligands span the Ru(1)ÃRu(2) and Ru(2)ÃRu(3)
edges. The three axial CO ligands are approximately
trans to the NÃRu bonds, while two of the six
/
Ru(2) edge,
/
/
shows that the fluxional process was not completely
frozen at ꢃ
/
80 8C, at which two individual hydride peaks
/
start to become apparent (ꢃ
/
14.1 and ꢃ15.5 ppm). The
/
equatorial CO ligands are colinear with the Ru(1)Ã
/
same effect is observed for the methyls of the NMe2
group. We have found no reasons that could account for
the high fluxionality of complex 2 as compared with the
rigidity of complex C.
Ru(3) edge and the remaining four are trans to the
hydride ligands. This structure reminds that of cluster C
[3].

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Table 3
Selected interatomic distances (A) in 2a, 2b and 4a
a
˚
2a
2b
4a
Ru(1)Ã
Ru(1)Ã
Ru(2)Ã
Ru(1)Ã
Ru(2)Ã
Ru(3)Ã
Ru(3)Ã
Ru(1)Ã
Ru(1)Ã
Ru(1)Ã
Ru(2)Ã
Ru(2)Ã
Ru(2)Ã
Ru(3)Ã
Ru(3)Ã
Ru(3)Ã
Ru(1)Ã
Ru(2)Ã
Ru(2)Ã
Ru(3)Ã
N(1)Ã
C(1)Ã
C(2)Ã
/
Ru(2)
Ru(3)
Ru(3)
N(1)
2.7624(8)
2.7315(8)
2.9544(8)
2.102(6)
2.096(7)
2.176(6)
2.7801(8)
2.7445(8)
2.9486(8)
2.103(7)
2.101(7)
2.182(7)
2.7828(7)
2.7422(8)
2.9702(7)
2.106(6)
2.105(6)
2.202(5)
2.406(2)
1.951(8)
1.904(8)
1.900(8)
1.933(8)
1.944(8)
1.941(8)
1.873(8)
/
/
/
/
N(1)
/
N(2)
/
P(1)
ꢁ/
ꢁ/
/
C(11)
C(12)
C(13)
C(21)
C(22)
C(23)
C(31)
C(32)
C(33)
H(1)
1.966(10)
1.891(8)
1.904(8)
1.934(10)
1.953(10)
1.937(10)
1.912(9)
1.934(9)
1.905(8)
1.77(7)
1.964(9)
1.903(10)
1.916(10)
1.923(8)
1.967(10)
1.920(9)
1.895(9)
1.969(10)
1.899(10)
1.85
/
/
/
/
/
/
/
ꢁ/
/
1.861(7)
1.77(5)
1.70(5)
1.74
/
/
H(1)
1.53(7)
1.85
/
H(2)
1.71(8)
1.83(7)
/
H(2)
1.69(8)
1.86(7)
1.73
/
N(2)
1.473(8)
1.485(10)
1.499(10)
1.135(11)
1.140(10)
1.128(10)
1.129(11)
1.115(11)
1.120(11)
1.128(11)
1.142(10)
1.114(11)
1.457(9)
1.474(12)
1.488(11)
1.120(11)
1.138(11)
1.135(12)
1.122(10)
1.117(11)
1.141(11)
1.137(11)
1.118(11)
1.134(11)
1.462(7)
1.495(8)
1.491(8)
1.130(9)
1.132(8)
1.144(8)
1.138(8)
1.117(8)
1.112(8)
1.139(8)
/
N(2)
/
N(2)
C(11)Ã
C(12)Ã
C(13)Ã
C(21)Ã
C(22)Ã
C(23)Ã
C(31)Ã
C(32)Ã
C(33)Ã
/
O(11)
O(12)
O(13)
O(21)
O(22)
O(23)
O(31)
O(32)
O(33)
/
/
/
/
/
/
/
ꢁ/
/
1.146(8)
a
2a and 2b are the two independent molecules found in the
asymmetric unit of compound 2.
2.2. Reactivity of complex 1 with triphenylphosphane
No reaction was observed when complex 1 was
treated with 1 equiv. of triphenylphosphane in THF at
room temperature. After 30 min at reflux temperature,
1
an approximately 50% mixture (estimated by H NMR
integration) of two isomeric monosubstituted deriva-
tives, 3a and 3b, of formula [Ru3(m-H)(m3-HNNMe2)-
(CO)8(PPh3)] was obtained (Scheme 3). This mixture
could not be separated. Longer reaction times at reflux
temperature did not change the ratio of the complexes,
indicating that they do not interconvert. Their 1H NMR
spectrum showed their hydrides as doublets (Table 2)
with J(PÃH) coupling constants of approximately 10 Hz,
Scheme 3.
which bear the phosphane ligand attached to the same
Ru atom as either the NMe2 (3a) or the NH fragments
(3b). In the case of complex 3a, the carbonyl substitution
process is accompanied by an edge to edge migration of
the hydride ligand. Pure 3a was subsequently obtained
by deprotonation of the cationic complex 4a (vide infra),
in which the phosphane ligand is also attached to the
same Ru atom as the NMe2 group.
typical of cis P-hydride arrangements [2ꢁ7]. Interest-
/
ingly, the phosphane ligand affects strongly the methyls
of the NMe2 group only in complex 3a, for which two
distinct methyl resonances are clearly observed, while
both methyl groups of isomer 3b appear at the same
chemical shift. All these data strongly support the
structures depicted in Scheme 3 for these complexes,

J.A. Cabeza et al. / Inorganica Chimica Acta 350 (2003) 93ꢁ
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100
97
These results contrast with those known for the
reactions of clusters A and B with triphenylphosphane,
since those reactions are instantaneous at room tem-
perature and render only one substitution product (the
one analogous to 3b) [2,3]. In carbonyl cluster chem-
istry, carbonyl substitution processes preferentially oc-
cur in coordination sites cis to hard ligands [2ꢁ7].
/
Therefore, it seems that both nitrogen atoms of the
dimethylhydrazido ligand possess a similar cis-labilizing
effect, probably as a consequence of a parallel hardness.
However, in the case of compounds A and B, their NH
fragments are clearly harder than the ketonic fragment
of A or the pyridine fragment of B, which are involved in
p-bonding, and this accounts for the regioselectivity of
their substitution reactions.
Fig. 3. Structure of the cationic part of compound 4a. Ellipsoids are
drawn at the 50% probability level.
2.3. Reactivity of complex 2 with triphenylphosphane
The cationic character of complex 2 should enhance
the cluster reactivity toward nucleophilic reagents,
promoting carbonyl substitutions and/or nucleophilic
additions. In fact, complex 2 reacted slowly with 1
equiv. of triphenylphosphane at room temperature to
give the substituted derivative [Ru3(m-H)2(m3-
HNNMe2)-
bonded Ru atoms and this accounts for the observed
reactivity (Table 4).
2.4. Protonation and deprotonation reactions
(CO)8(PPh3)][BF4] (4a) (Scheme 3). However, the reac-
tion was more conveniently carried out at reflux
temperature (THF) in order to reduce the reaction
time to 20 min.
As outlined in Scheme 3, complex 4a could be
deprotonated with triethylamine to give the neutral
derivative 3a. This provided an appropriate synthetic
method to make complex 3a in a pure form, since
treatment of 1 with triphenylphosphane afforded an
inseparable mixture of the isomers 3a and 3b (vide
supra). In addition, protonation of this mixture with
[HOEt2][BF4] in dichloromethane led to a mixture of the
cationic dihydrido derivatives 4a and 4b. The ratio of
these complexes remained unaltered after heating the
mixture in refluxing THF for 1 h, therefore, they do not
interconvert. Although compound 4b could not be
In the 1H NMR spectrum of 4a (Table 2), it was
observed that both hydride ligands were coupled to each
other (Jꢀ3.1 Hz) and to the phosphorus atom. From
/
the values of the J(HÃP) coupling constants (9.3 and 3.1
Hz), it was inferred that the phosphane ligand is cis to a
hydride and far away from the other. With the analytical
and spectroscopic data of 4a it was not possible to
unequivocally assign its structure, which was determined
by X-ray diffraction methods.
The structure of compound 4a (Table 3, Fig. 3) is
entirely analogous to that of 2, except for the presence of
a triphenylphosphane ligand, attached to the same Ru
atom as the NMe2 fragment, in an equatorial position
cis to the bridging hydride.
Again, this result differs from that previously known
for the analogous ampy derivative C, for which its
substitution product contains the phosphane ligand
attached to the Ru atom bonded to the NH fragment
and to only one hydride [3].
The fact that compound 4a is the only product
obtained in the reaction of complex 2 with triphenyl-
phosphane indicates that the protonation of 1 increases
the electrophilic character of the Ru atom attached to
NMe2 fragment to a greater extent than those of the
other two Ru atoms. In contrast, the softness of the
pyridyl fragment of complex C makes the Ru atom to
which it is bonded less electrophilic than the amido-
1
prepared free of 4a, its H and 31P NMR spectroscopic
data (Table 2) were obtained from the spectra of the
mixture. The J(HÃP) coupling constants of its hydride
resonances (7.9 and 6.0 Hz) clearly indicate that the
phosphorus atom is not trans to any of the hydrides,
since J(HÃP) values greater than 20 Hz are expected for
this situation [3,4]. Consequently, the position of the
phosphane ligand in 4b is that depicted in Scheme 3.
All these data indicate that the atom connectivity is
maintained in the protonation and deprotonation reac-
tions.
3. Conclusions
The systematic study reported herein and the compar-
ison of the obtained results with those known for

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J.A. Cabeza et al. / Inorganica Chimica Acta 350 (2003) 93ꢁ100
/
Table 4
Crystal data and structure refinement details for compounds 2 and 4a
4. Experimental
2
4a
4.1. General data
Formula
C
703.22
11H9BF4N2O9Ru3 C28H24BF4N2O8PRu3
937.48
Formula weight
Crystal system
Space group
Solvents were dried over sodium diphenyl ketyl (THF,
diethyl ether hydrocarbons) or CaH2 (dichloromethane,
1,2-dichloroethane) and distilled under nitrogen prior to
use. The reactions were carried out under nitrogen,
using Schlenk-vacuum line techniques, and were routi-
nely monitored by solution IR spectroscopy and by spot
TLC. All reagents were purchased from commercial
suppliers. IR spectra (Table 1) were recorded in solution
triclinic
¯
P1
monoclinic
C2/c
/
˚
a (A)
8.3735(3)
16.4026(7)
16.9120(7)
63.659(2)
89.286(3)
79.993(2)
2044.7(1)
4
36.271(3)
12.4706(7)
16.5046(11)
90
˚
b (A)
˚
c (A)
a (8)
b (8)
112.296(3)
90
g (8)
3
V (A )
˚
6907.3(8)
8
3664
on a PerkinꢁElmer Paragon 1000 FT spectrophot-
/
Z
F(000)
Dcalc (g cmꢃ3
1336
2.284
ometer. NMR spectra (Table 2) were run on Bruker
DPX-300 (room temperature) and AMX-400 (low
temperature) instruments, using the residual solvent
peak (for 1H) or external 85% H3PO4 (for 31P) as
references. Microanalyses were obtained from the Uni-
versity of Oviedo Analytical Service. FAB MS were
obtained from the University of Santiago de Compos-
tela Mass Spectrometric Service; data given refer to the
most abundant molecular ion isotopomer.
)
1.803
Cu Ka (1.54180)
11.550
˚
Radiation (l, A)
m (mmꢃ1
Cu Ka (1.54180)
18.508
)
Crystal size (mm)
Temperature (K)
u Limits (8)
0.20ꢄ
200(2)
2.92ꢁ68.91
0/10, ꢃ19/19, ꢃ
20
/
0.02ꢄ
/
0.02
0.18ꢄ
200(2)
3.78ꢁ68.61
20/ 0/43, ꢃ15/15, ꢃ19/18
/0.13ꢄ0.10
/
/
/
Min/max h, k, l
/
/
/
/
Number of reflections 33 775
collected
12 311
Unique reflections
(Rint
Reflections with I ꢀ
2s(I)
7540 (0.083)
6352 (0.076)
4508
)
/
6107
4.2. Synthesis of [Ru3(m-H)(m3-HNNMe2)(CO)9] (1)
Absorption correction RefDelF (XABS2
Max/min transmission 0.478/0.212
Parameters, restraints 356, 2
)
RefDelF (XABS2
0.315/0.221
436, 0
)
A solution of [Ru3(CO)12] (1.000 g, 1.560 mmol) and
H2NNMe2 (500 ml, 8.32 mmol) in THF (70 ml) was
stirred at reflux temperature for 3 h. The color changed
from orange to dark brown. The solvent was removed
under reduced pressure and the residue was dissolved in
the minimum volume of THF. This solution was
transferred into a chromatography column of neutral
Goodness-of-fit on F2 1.088
1.030
0.0543
Final R1
0.0473
(on F, I ꢀ
/
2s(I))
Final wR2
(on F2, all data)
0.1615
0.1505
Min/max residuals
ꢃ3
ꢃ
/
1.142/1.695
ꢃ/0.715/1.037
˚
(e A
)
alumina (activity III, 2ꢄ
Hexane eluted a small amount of unreacted ruthenium
carbonyl. Dichloromethaneꢁhexane (1:1) eluted the
/20 cm) packed in hexane.
/
product, which was obtained as a yellow solid upon
solvent removal (376 mg, 39%). A dark residue re-
mained uneluted at the top of the column. Anal. Found:
C, 21.93; H, 1.41; N, 4.47. Calc. for C11H8N2O9Ru3: C,
21.46; H, 1.31; N, 4.55%. FAB MS (m/z): 617 [Mꢂ].
analogous carbonyl substitution reactions on structu-
rally related triruthenium clusters containing other face-
capping ligands allow the conclusion that the regios-
electivity of the reactions is more influenced by electro-
nic factors associated with the bridging ligands than by
structural factors, since structurally related compounds
displayed different reactivity. The entering phosphane
ligand ends cis to a hydride ligand in an equatorial site
attached to the most electrophilic metal atom, which is
generally bonded to the hardest fragment of the bridging
ligand.
4.3. Synthesis of [Ru3(m-H)2(m3-
HNNMe2)(CO)9][BF4] (2)
One drop (from a Pasteur pipette) of a 54% solution
of H[BF4] in diethyl ether was added to a solution of
compound 1 (50 mg, 0.081 mmol) in dichloromethane (5
ml). The solvent was removed under reduced pressure
Although hardness may account (at least to a
considerable extent) for the observed regioselectivity,
we have found no reasonable relationship between
ligand hardness and the milder conditions required for
and the residue was washed with diethyl ether (3ꢄ5 ml)
/
and dried in vacuo to give complex 2 as a pale yellow
solid (49 mg, 87%). Anal. Found: C, 18.57; H, 1.26; N,
3.67. Calc. for C11H9BF4N2O9Ru3: C, 18.79; H, 1.29; N,
the reactions of Aꢁ/C relative to those required by 1 and
2.
3.98%. FAB MS (m/z): 618 [Mꢂꢃ
BF4].
/

J.A. Cabeza et al. / Inorganica Chimica Acta 350 (2003) 93ꢁ
/
100
99
4.4. Reaction of compound 1 with triphenylphosphane
with SHELX-97 [12] against F2 of all reflections. Empiri-
cal absorption corrections were applied using XABS2
[13]. Two crystallographically independent molecules
were found in the crystal of compound 2. All non H-
atoms were refined anisotropically. The hydrogen atoms
H1A, H2A and H2B of 2 and H1 and H10 of 4a were
located in the corresponding Fourier maps and their
coordinates and thermal parameters were refined. The
position of the hydride atoms H1B of 2 and H2 of 4a
were calculated using the program XHYDEX [14], their
coordinates were fixed and their thermal parameters
were refined. The remaining hydrogen atom positions
were calculated riding on their parent atoms. The
drawings and structure calculations were performed
with PLATON [15]. The WINGX program package was
used throughout the structure determinations [16]. A
selection of crystal and refinement details is given in
Table 4.
PPh3 (24 mg, 0.089 mmol) was added to a solution of
compound 1 (50 mg, 0.081 mmol) in THF (30 ml). The
solution was stirred at reflux temperature for 30 min.
The solvent was removed under reduced pressure and
the oily residue was stirred in hexane (15 ml) to give a
yellow solid (53 mg, 78%), subsequently identified by IR
and NMR (1H and 31P) as an approximately 50%
mixture of complexes 3a and 3b.
4.5. Synthesis of [Ru3(m-H)(m3-
HNNMe2)(PPh3)(CO)8] (3a)
Triethylamine (8 ml, 0.057 mmol) was added to a
solution of complex 4a (40 mg, 0.043 mmol) in
dichloromethane (20 ml). After stirring for 30 min, the
solvent was removed under reduced pressure and the
residue was purified by column chromatography on
neutral alumina (activity III, 2ꢄ
/
10 cm). Hexaneꢁ
/
dichloromethane (2:1) eluted a yellow band that yielded
compound 3a as a yellow solid after solvent removal (21
mg, 57%). Anal. Found: C, 40.16; H, 2.82; N, 3.09. Calc.
for C28H23N2O8PRu3: C, 39.58; H, 2.73; N, 3.30%. FAB
MS (m/z): 851 [Mꢂ].
5. Supplementary material
Complete crystallographic data for compounds 2 and
4a have been deposited with the Cambridge Crystal-
lographic Data Center, CCDC Nos. 184271 and 184272,
respectively. Copies of this information may be obtained
free of charge from The Director, CCDC, 12 Union
4.6. Synthesis of [Ru3(m-H)2(m3-
HNNMe2)(PPh3)(CO)8][BF4] (4a)
Road, Cambridge, CB12 1EZ, UK (fax: ꢂ44-1223-336-
/
033; e-mail: deposit@ccdc.cam.ac.uk or http://
www.ccdc.cam.ac.uk).
PPh3 (20 mg, 0.078 mmol) was added to a solution of
compound 2 (50 mg, 0.071 mmol) in THF (30 ml). The
solution was stirred at reflux temperature for 20 min.
The solvent was removed under reduced pressure and
Acknowledgements
the oily residue was washed with diethyl ether (2ꢄ6 ml)
/
and dried in vacuo to give complex 4a as a yellow solid
(64 mg, 96%). Anal. Found: C, 36.02; H, 2.66; N, 2.78.
Calc. for C28H24BF4N2O8PRu3: C, 35.87; H, 2.58; N,
Financial support form the Spanish DGESIC (grants
PB98-1555 to J.A.C., and BQU2000-0219 to S.G.-G.) is
gratefully acknowledged.
2.99%. FAB MS (m/z): 852 [Mꢂꢃ
/BF4].
4.7. Protonation of 3aꢂ
/
3b with tetrafluoroboric acid
References
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/
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/
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