Trifluoromethanesulfonato derivatives of ruthenium(II)

Article abstract of DOI:10.1016/S0020-1693(02)00796-X

The reactivity of Ru(O₂CNⁱPr₂) ₂(CO)₂(PPh₃)₂ (1), towards CF ₃SO₃H (TfOH, trifloromethanesulfonic acid or triflic acid) has been studied and the products [R

Full text of DOI:10.1016/S0020-1693(02)00796-X

Inorganica Chimica Acta 334 (2002) 411ꢁ418
/
www.elsevier.com/locate/ica
Trifluoromethanesulfonato derivatives of ruthenium(II)
Daniela Belli Dell’Amico *, Fausto Calderazzo, Andrea Grazzini, Luca Labella,
Fabio Marchetti
Dipartimento di Chimica e Chimica Industriale, Universita` di Pisa, via Risorgimento 35, I-56126 Pisa, Italy
Received 31 December 2001; accepted 25 January 2002
Dedicated to Professor Andrew Wojcicki, The Ohio State University, in recognition of his outstanding contributions to Inorganic Chemistry
Abstract
The reactivity of Ru(O2CNiPr2)2(CO)2(PPh3)2 (1), towards CF3SO3H (TfOH, trifloromethanesulfonic acid or triflic acid) has
been studied and the products [Ru(O2CNiPr2)(CO)2(PPh3)2][OTf] (2), and Ru(OTf)2(CO)2(PPh3)2 (3), have been obtained, the
former being structurally characterised as one of the few examples of cationic N,N-dialkylcarbamato complexes. In compound 2,
the N,N-di-iso-propylcarbamato group is bidentate. In experiments aimed at obtaining Ru(OTf)2(CO)2(PPh3)2 according to the
literature method, i.e. from Ru(CO)3(PPh3)2 and TfOH, the intermediate species [RuH(CO)3(PPh3)2][OTf] (4), corresponding to the
oxidative addition of triflic acid, has been intercepted. Treatment of this derivative in refluxing toluene followed by addition of
methanol afforded the compound [RuH(CO)2(PPh3)2(CH3OH)][OTf] (5), which has been characterised by single-crystal X-ray
diffractometry. # 2002 Elsevier Science B.V. All rights reserved.
Keywords: Ruthenium(II); Trifluoromethanesulfonato; Triflic acid
1. Introduction
have shown cases of ruthenium-coordinated triflato
groups [3a], and examples where the anion is outside
the coordination sphere [3].
An earlier paper from these laboratories [1] has
reported a new valuable ruthenium compound, namely
Ru(O2CNiPr2)2(CO)2(PPh3)2 (1). This stable product
contains the substitutionally labile monodentate dia-
lkylcarbamato group, thus proving to be a remarkably
good starting material for the preparation of other
complexes, difficult to prepare otherwise. Metal com-
plexes containing the trifluoromethanesulfonato
(O3SCF3, triflato) ligand are interesting in view of the
low coordinating power of this ligand [2], and this area
of inorganic chemistry is growing rapidly. Several
ruthenium(II) triflates have been reported: they are
generally prepared from chlorides of ruthenium(II)
using Ag(OTf) as dehalogenating agent [3], from ruthe-
nium(II) hydrides and TfOH [4] or from ruthenium(0)
derivatives and TfOH [5]. X-ray diffractometric studies
In this paper, which is in the track of earlier
investigations by Wojcicki and coworkers [4], com-
pound 1 has been used for the preparation of triflato
derivatives. Also, attempts have been made aimed at
preparing new cationic N,N-dialkylcarbamato deriva-
tives based on the higher coordinating power of the
O2CNR2 ligand with respect to the triflato. Previous
literature data about cationic N,N-dialkylcarbamato
derivatives were limited to the ruthenium derivatives,
[Ru(O2CNMe2)(PMe2Ph)4]ꢀ and [Ru(CO)(O2CNMe2)-
(PMe2Ph)4]ꢀ, isolated as their hexafluorophosphate
derivatives [6]. In addition to the reaction of 1 with
both triflic anhydride and triflic acid, this paper reports
the room temperature oxidative addition of triflic acid
to the ruthenium(0) derivative Ru(CO)3(PPh3)2 leading
to the corresponding hydridoꢁtriflato complexes, the
/
product of carbonyl substitution by methanol,
[RuH(CO)2(PPh3)2(CH3OH)][OTf], being structurally
characterized.
* Corresponding author. Tel.: ꢀ
37.
E-mail address: belli@dcci.unipi.it (D.B. Dell’Amico).
/
39-050-918-206; fax: ꢀ39-050-202-
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 0 7 9 6 - X

412
D.B. Dell’Amico et al. / Inorganica Chimica Acta 334 (2002) 411ꢁ418
/
2. Experimental
2.3. Preparation of compound 3
2.3.1. From the reaction of 1 with triflic acid
2.1. General
To a solution of Ru(O2CNiPr2)2(CO)2(PPh3)2 (1)
(0.30 g, 0.31 mmol) in C6H5CH3 (10 ml), TfOH (0.19
g, 1.27 mmol) was added at about 20 8C. After 1 h
stirring, a 31P NMR spectrum showed the starting
product 1 to have disappeared, while the formation of
the soluble 3 was evidenced by a resonance at 20.2 ppm.
After 4 h stirring further C6H5CH3 (20 ml) was added,
the suspension was filtered, and the solid (A) was
All preparations were carried out in standard Schlenk
tubes. All solvents were freshly distilled over conven-
tional drying agents under dinitrogen and all reactions
were carried out under dinitrogen, unless otherwise
stated. The compounds Ru(O2CNiPr2)2(CO)2(PPh3)2
(1) [1], Ru(CO)3(PPh3)2 [7] and RuCl2(CO)2(PPh3)2
[7,8] were synthesized according to the literature. Di-
iso-propylammonium triflate [NHi2Pr2][OTf] was pre-
pared from [NHi2Pr2]Cl (1.26 g, 9.2 mmol) and Ag(OTf)
(2.32 g, 9.03 mmol) in CH2Cl2. After removal of AgCl
by filtration, the product with a satisfactory elemental
analysis was recovered from the filtrate upon evapora-
tion of the solvent. IR (most intense bands, cmꢂ1): 3122
(s, br), 2907 (s), 2496 (m, NH), 1605 (m-s), 1407 (s), 1294
(s), 1261 (s, SO3 [2a]), 1165 (s), 1100 (s), 1089 (s), 1035 (s,
washed with C6H5CH3 (10 mlꢄ/4). The filtered solution
was treated with C7H16 (100 ml) and stored at ꢂ
/
30 8C
for 12 h. The resulting suspension was filtered at low
temperature and the colourless solid (B) was recrystal-
lized from a mixture (2:5 by volume) of CH2Cl2 and
C6H5CH3, recovered by filtration and dried in vacuo
(0.10 g, 32.9% yield). Anal. Calc. for Ru(OTf)2(CO)2-
(PPh3)2 (3), C40H30F6O8P2RuS2: C, 49.0; H, 3.1. Found:
C, 48.6; H, 3.0%. IR (Nujol mull, most significant bands
1
SO3 [2a]), 805 (s), 641 (s), 579 (m), 517 (s). H NMR
in the 2300ꢁ
(sh), 1328 (m), 1190 (s, br), 1090 (s). 1H NMR (CDCl3):
d 7.5 (m). 13C NMR (C6D6): d 192.9 (s), 134.7ꢁ
129.0;
120.1 (q, JCꢀF
256 Hz). 31P NMR (C6D6): d 20.2 (s),
with a resonance of low intensity at 23.2 (s). 19F NMR
(C6D6): d ꢂ77.1 (s). A portion of the solid A was
/
1000 cmꢂ1 range): 2074 (s), 2012 (s), 1338
(CDCl3, ppm): 1.4 (d, CH3), 3.5 (sept, CH), 7.6 (br,
NH2). 13C NMR (CDCl3, ppm): 18.9 (CH3), 47.9 (CH).
Elemental analyses (C, H, N) were performed by
Laboratorio di Microanalisi, Facolta` di Farmacia,
Universita` di Pisa, with a C. Erba mod. 1106 elemental
/
ꢃ
/
/
analyzer. IR spectra were measured with a Perkinꢁ
/
dissolved in CD2Cl2 and NMR spectra showed signals
due to 2 (31P NMR: d 28.8) and to [NH2i Pr2][OTf], the
latter characterized by 1H NMR with d 1.4 (d, CH3); 3.5
(sept, CH) and 7.6 (br, NH2).
A gas-volumetric monitoring of the reaction was
carried out by reacting Ru(O2CNiPr2)2(CO)2(PPh3)2
(0.63 g, 0.65 mmol) in 25 ml of C6H5CH3 with triflic
acid (0.19 g, 1.27 mmol) under CO2 at 25.3 8C,
evolution of 0.65 mmol of CO2 being observed in about
Elmer FT-IR mod. 1725X spectrophotometer. NMR
spectra were recorded using a Varian Gemini 200 MHz
instrument, the data being expressed in ppm from TMS
for 1H and 13C, from H3PO4 for 31P and from CFCl3 for
19F.
2.2. Reaction of 1 with triflic anhydride. Preparation of
[Ru(O2CNiPr2)(CO)2(PPh3)2][OTf], (2)
10 min, corresponding to a CO2ꢁ
/
Ru molar ratio of 1.
Ru
Triflic anhydride (0.07 g, 0.25 mmol) in 5 ml of
C6H5CH3 was added to a solution of Ru(O2C-
NiPr2)2(CO)2(PPh3)2 (0.12 g, 0.12 mmol) in 5 ml of
C6H5CH3. Gas evolution was observed and a colourless
solid precipitated out after a few minutes. The solid,
recovered by filtration, was dissolved in 5 ml of CH2Cl2
and precipitated out by addition of C6H5CH3 (10 ml)
When the reaction was repeated with a triflic acidꢁ
/
molar ratio of 6 at 28.1 8C, Ru(O2CNiPr2)2(CO)2-
(PPh3)2 (0.29 g, 0.30 mmol) in 20 ml of C6H5CH3 and
triflic acid (0.27 g, 1.80 mmol) caused the evolution of
0.57 mmol of CO2, corresponding to a CO2ꢁ
ratio of 1.9 in about 1 h.
/Ru molar
and cooling at ꢂ
/
30 8C. The colourless crystals thus
2.3.2. From RuCl2(CO)2(PPh3)2 and Ag(OTf)
obtained were separated by filtration and dried in vacuo
(0.046 g, 39.3% yield). Anal. Calc. for C46H44F3NO7-
P2RuS: C, 56.7; H, 4.5; N, 1.4. Found: C, 55.8; H, 4.4;
N, 1.3%. IR (Nujol mull, most significant bands in the
The chloro-complex RuCl2(CO)2(PPh3)2 (0.65 g, 0.86
mmol) in 120 ml of C6H5CH3 was treated with Ag(OTf)
(0.44 g, 1.71 mmol). The suspension was refluxed for 1 h
and a grey suspension was thus obtained. The mixture
was cooled down to room temperature (r.t.) and the
suspension was filtered. The filtrate was evaporated to
about half its original volume, diluted with C7H16 (100
ml) and cooled down to 0 8C. After 12 h the suspension
2300ꢁ
1438 (s), 1274 (sh), 1262 (s), 1141 (m), 1095 (s), 1032 (s).
1H NMR (CDCl3): d 7.7ꢁ
7.1 (18H); 3.2 (m, Jꢃ7.4 Hz,
1H); 0.4 (d, Jꢃ
7.4 Hz, 6H). 31P NMR (CDCl3): d 28.7
(s). 19F NMR (CDCl3): d ꢂ
78.6. The product was
recrystallized from a C6H5CH3ꢁCH2Cl2 mixture, the
/
1000 cmꢂ1 range): 2070 (s), 2010 (s), 1556 (s),
/
/
/
/
was filtered, the solid was washed with C7H16 (3ꢄ10
/
/
ml) and dried in vacuo (0.59 g, 70.0% yield). Spectro-
scopic data corresponded to those reported for the
product described under Section 2.3.1.
resulting crystals being used for the X-ray diffracto-
metric experiment.

D.B. Dell’Amico et al. / Inorganica Chimica Acta 334 (2002) 411ꢁ
/
418
413
Upon
exposure
to
air,
a
sample
of
range): 2067 (s), 2007 (s), 1918 (w), 1296 (s), 1220 (s),
1160 (s, br), 1091 (s), 1024 (s). 31P NMR (CDCl3): d 44.1
(s) and a resonance of low intensity at 41.2 (s). 1H NMR
Ru(OTf)2(CO)2(PPh3)2 gave analytical results corre-
sponding to the formation of an aquo complex,
presumably [Ru(H2O)2(CO)2(PPh3)2][CF3SO3]2. Anal.
Calc. for C40H34F6O10P2RuS2: C, 47.3; H, 3.4. Found:
C, 46.9; H, 3.1%. The spectroscopic data (see Section 3)
are consistent with such a formulation.
(CDCl3): d 7.9ꢁ
3.6 (t, JHꢀP 19.3 Hz), ꢂ
NMR (CDCl3): d ꢂ78.3 (s); ꢂ
/
7.4 (m), 5.6 (q), 3.7 (s), 3.5 (s), 1.7 (d), ꢂ
4.3 (t, JHꢀP
19.4 Hz). 19F
78.7 (s). For the
/
ꢃ
/
/
ꢃ
/
/
/
NMR spectra in the presence of excess MeOH, see
Section 3.
2.3.3. From Ru(CO)3(PPh3)2 and TfOH
This preparation was carried out by a modification of
2.6. X-ray crystallographic studies
the literature method [5].
A
suspension of
Ru(CO)3(PPh3)2 (0.68 g, 0.96 mmol) in C6H5CH3 (30
ml) was treated with CF3SO3H (0.44 g, 2.93 mmol). The
mixture was refluxed for 1 h and then slowly cooled to
r.t. The suspension was filtered and the solid was
The X-ray diffraction experiments were carried out at
r.t. (Tꢃ/293 K) by means of a Bruker P4 diffractometer
operating with a graphite-monochromated Mo Ka
˚
radiation (lꢃ0.71073 A). The samples were sealed in
/
washed with MeOH (25 mlꢄ
/
3) and dried in vacuo
glass capillaries under an atmosphere of dinitrogen
saturated with the crystallization solvent. The intensity
data collection was carried out with the v/2u-scan
mode, collecting a redundant set of data. Three standard
reflections were measured every 97 measurements to
check sample decay. The intensities were corrected for
Lp effects and for absorption by means of a c-scan
method [9]. The structure solutions, obtained by means
of the automatic direct methods, and the refinements,
based on full-matrix least-squares on F2, were done by
means of the SHELX-97 programme [10]. Data reduction
of measured intensities was done by the XSCANS package
[11]. Some other utilities contained in the WINGX suite
[12] were also used.
(0.38 g, 40% yield). Anal. Calc. for C40H30F6O8P2RuS2:
C, 48.4; H, 3.0. Found: 49.0; H, 3.1%. For the spectro-
scopic data, see Section 2.3.2.
In sym-dichloroethane as solvent with an anhydrideꢁ
/
1 molar ratio of 1.7, the 31P NMR spectrum of the
reaction mixture showed the prevailing presence of
Ru(OTf)2(CO)2(PPh3)2 (3).
2.4. Preparation of [RuH(CO)3(PPh3)2](OTf), (4)
A suspension of Ru(CO)3(PPh3)2 (0.54 g, 0.76 mmol)
in C6H5CH3 (40 ml) was treated with TfOH (0.12 g, 0.80
mmol), which resulted in the immediate formation of a
colourless solid. The reaction mixture was stirred for 20
min and then filtered. The solid was washed with
Crystals of 2 are light yellow prisms. By selecting one
of them of dimensions 0.48ꢄ
cell parameters listed in Table 1 were obtained. A set of
3576 intensity data were collected in the range 2.015
u 522.58. By merging the equivalent ones, a set of 3027
independent intensities (Rint
/
0.48ꢄ
/
0.25 mm3 the unit
C6H5CH3 (10 mlꢄ3) and dried in vacuo (0.43 g, 66%
/
yield). Anal. Calc. for C40H31F3O6P2RuS: C, 55.9; H,
/
3.6. Found: C, 55.1; H, 3.6. IR (Nujol mull, most
1000 cmꢂ1 range): 2139
(w), 2083 (s), 2069 (s), 1998 (w), 1266 (s), 1162 (m), 1092
/
2
2
significant bands in the 2300ꢁ
/
ꢃ
/
[ajFo ꢂ
0.0282) was obtained, among which 2365
satisfied the condition I ꢀ2s(I). The systematic ab-
/
Fo (mean)j/
2
a(Fo )]ꢃ
/
(m), 1029 (s). 31P NMR (CDCl3): d 34.9 (s). H NMR
/
1
(CDCl3): d 7.5 (m); 6.4 (t, JHꢀP
(CDCl3): d 192.3 (t); 189.8 (t); 134.7ꢁ
(CDCl3): d ꢂ78.5 (s).
ꢃ
/
19.3 Hz). 13C NMR
sences suggested the C2/m, C2 or Cm space groups. The
multiplicity of these groups and the cell volume of 5199
/
128.5. 19F NMR
3
A appeared to be appropriate to contain four units of
˚
/
The 31P NMR spectrum of a CH2Cl2 solution of
[RuH(CO)3(PPh3)2](OTf) shows a signal at 34.5 ppm.
When an eccess of Et3N was added this resonance
disappeared, and a new signal, due to Ru(CO)3(PPh3)2,
appeared at 57.6 ppm.
[Ru(O2CNiPr2)(CO)2(PPh3)2](OSO2CF3) and four mo-
lecules of the solvents C6H5CH3 and CH2Cl2. By
considering the cell content, a mean atomic volume of
3
18.3 A per atom, almost identical to that calculated for
˚
compound 1, was obtained, see also Table 1. The
structure solution was obtained in the space group C2/
m, the asymmetric unit consisting of one-half of the
[Ru(O2CNiPr2)(CO)2(PPh3)2]ꢀ cation and one-half of
the triflate anion, one-third of C6H5CH3 and one
CH2Cl2. Toluene is placed on the inversion centre at 0,
0, 0, with a random distribution of the methyl groups,
which could not be localized, while the CH2Cl2 is
randomly placed in two positions related by an inversion
2.5. Preparation of 5
A suspension of 4 (0.22 g, 0.26 mmol) in C6H5CH3 (20
ml) was refluxed to give a yellow solution. By cooling
down to r.t. and adding MeOH (13 mg, 0.41 mmol),
colourless crystals precipitated out which were filtered
and dried in vacuo (4% yield). Anal. Calc. for
[RuH(CO)2(MeOH)(PPh3)2][OTf], C40H35F3O6P2RuS:
C, 55.6; H, 4.1%. Found: C, 55.7; H, 4.1%. IR (Nujol
centre at yꢃ0. A different kind of disorder was
/
observed in the position of the fluorine atoms, which
were treated, however, as ordered. The final refinement
mull, most significant bands in the 2300ꢁ
1000 cmꢂ1
/

414
D.B. Dell’Amico et al. / Inorganica Chimica Acta 334 (2002) 411ꢁ418
/
Table 1
Crystal data and structure refinement
3. Results and discussion
Metal N,N-dialkylcarbamato complexes have been
extensively studied in these laboratories [13] and results
on ruthenium derivatives have recently been reported
[1]. In the course of the present work, one of these
compounds, namely Ru(O2CNiPr2)2(CO)2(PPh3)2 (1),
has been used as a precursor to ruthenium triflates by
exploiting the reactivity of the N,N-dialkylcarbamato
ligand. In 1 the ruthenium centre is pseudo-octahedrally
coordinated with the phosphine ligands reciprocally
trans and with the carbonyl and the monodentate
carbamato ligands in mutual cis positions. The reaction
of 1 with triflic anhydride in toluene yields the sparingly
soluble [Ru(O2CNiPr2)(CO)2(PPh3)2](OTf) (2), which
has been structurally and spectroscopically charac-
terised. The CO stretching vibrations of 2, 2070 and
2010 cmꢂ1, are at higher wavenumbers with respect to
the precursor Ru(O2CNiPr2)2(CO)2(PPh3)2 (1), (2050
and 1988 cmꢂ1), suggesting a positive charge in the
ruthenium-containing moiety of the compound. The
highest energy band associated with the carbamato
group is at 1556 cmꢂ1, to be compared with the value
of 1594 cmꢂ1 in 1, containing monodentate carbamato
ligands. This suggests that the N,N-di-iso-propylcarba-
Compound
2×
/
0.5 toluene×
/
CH2Cl2
5
Empirical formula
Formula weight
Temperature (K)
Crystal system
C50.5H50Cl2F3NO7P2RuS C40H35F3O6P2RuS
1105.89
293(2)
monoclinic
863.75
293(2)
orthorhombic
Pnma (No. 62)
Space group
Unit cell dimensions
C2/m (No. 12)
˚
a (A)
23.635(6)
16.824(3)
15.269(3)
121.10(1)
5199(2)
4
17.400(2)
23.222(2)
9.4255(6)
˚
b (A)
˚
c (A)
b (8)
3
V (A )
˚
3808.5(5)
4
1.506
Z
rcalc (Mg mꢂ3
)
1.413
0.566
m (mmꢂ1
)
0.612
2729/0/250
Data/restraints/para- 3027/0/313
meters
R(Fo) [Iꢀ
/
2s(I)]
2s(I)]
0.0933
0.2545
0.0418
0.0952
Rw(Fo2) [Iꢀ
/
R(Fo)ꢃ
/
a jjFojꢂ
/
jFcjj/a jFoj;
Rw(Fo2)ꢃ
/
[a [w(Fo2ꢂ
/
Fc2)2]/a [w-
(Fo2)2]]1/2
2Fc2]/3.
;
wꢃ
/
1/[s2(Fo2)ꢀ
/
(AQ)2ꢀ
/
BQ] where Qꢃ
/
[max(Fo2, 0)ꢀ
/
mato is bidentate. In the 1400ꢁ
1000 cmꢂ1 region, bands
/
cycle was done by using anisotropic thermal parameters
for all heavy atoms of the anion, cation and CH2Cl2 and
isotropic for the others and by placing the hydrogen
atoms in calculated positions. The resulting reliability
factors are listed in Table 1.
attributable to the triflato group were observed at 1262
(s) and 1032 (s) cmꢂ1. The ionic OTfꢂ anion has intense
bands at 1269 and 1032 cmꢂ1 assigned to the asym-
metric and symmetric Sꢀ/O stretching modes, respec-
tively [2a,14a], as confirmed also by our independent
data on the di-iso-propylammonium derivative (NHi2-
Pr2)(OTf), see Section 2.
Crystals of 5 are colourless prisms. One of them of
dimensions 0.48ꢄ
parameters listed in Table 1. A set of 3430 intensity data
was collected in the range 2.352u 523.08. By merging
the equivalent ones, a set of 2729 independent intensities
(Rint 0.0169) was obtained, among which 2060 satis-
fied the condition I ꢀ2s(I). The systematic absences
/
0.38ꢄ
/
0.26 mm3 showed the unit cell
The spectroscopic information was completely con-
firmed by X-ray crystallographic study. The triflato
group is outside the coordination sphere of the metal,
the mononuclear cation having a distorted octahedral
geometry (see Fig. 1) with trans phosphines and cis
/
/
ꢃ
/
/
indicated the Pnma or Pn21a space groups. The solution
was found in the centrosymmetric group by the auto-
matic direct methods, which revealed the location of
ruthenium, carbonyl and MeOH ligands on the mirror
plane at yꢃ1/4. The triflato anion was found to be
/
randomly distributed in two mirror-related almost
superimposed positions. In order to exclude that the
anion disorder can be an artifact resulting from an
erroneous assumption of the higher symmetry, the
refinement was tried both in the Pnma and in the
Pn21a space groups. As the anion disorder was not
removed, and the R factor was not lowered, the Pnma
space group was preferred. The final refinement cycle
was done by using anisotropic thermal parameters for
all heavy atoms and placing the hydrogen atoms in
calculated positions. The resulting reliability factors are
listed in Table 1.
Fig. 1. Structure of the [Ru(O2CNiPr2)(CO)2(PPh3)2]ꢀ cation, with
some of the metal-coordinated atoms beeing represented by thermal
ellipsoids at 30% probability. The apex of the phosphorous label has
the same meaning as in Table 2.

D.B. Dell’Amico et al. / Inorganica Chimica Acta 334 (2002) 411ꢁ
/
418
415
carbonyl groups. The terminal bidentate N,N-di-iso-
propylcarbamato ligand displays RuꢀO(3) and Ruꢀ
O(4) distances of 2.088 and 2.157 A, respectively, and
a bite angle of 62.38 (see Fig. 1 and Table 2 for the most
significant bond distances and angles).
low solubility in the reaction medium. In fact, when the
reaction between 1 and excess of triflic anhydride was
carried out in 1,2-dichloroethane, the prompt and
transient formation of 2 was observed by 31P NMR
spectroscopy, followed by further reaction to produce
Ru(OTf)2(CO)2(PPh3)2, 3.
/
/
˚
The two tertiary phosphine groups are equivalent by
˚
When 1 was reacted with 4 or more equiv. of triflic
acid in toluene as medium Ru(OTf)2(CO)2(PPh3)2 (3),
was obtained as the main product together with variable
amounts of 2, depending on time, temperature and
excess of triflic acid. A gas-volumetric monitoring of this
reaction showed that the addition of the first 2 equiv. of
triflic acid produces the fast evolution of 1 equiv. of
CO2, corresponding to the formation of 2, see Eq. (1).
symmetry and show Ruꢀ
RuꢀP angle being 174.38. The Ruꢀ
1.87(1) and 1.86(2) A. In compound 1 the carbamato
ligands are monodentate with RuꢀO distances of
RuꢀO angle of
/
P distances of 2.420 A, the Pꢀ
/
/
/
CO distances are
˚
/
˚
2.076(5) and 2.090(5) A and an Oꢀ
/
/
˚
80.5(2)8. The RuꢀP [2.402(2) and 2.411(2) A] and Ruꢀ
CO (1.87 A) distances in 1 are comparable to those
observed in 2. In compound Ru(O2CNiPr2)2(PPh3)2 [1],
/
/
˚
Ru(O2CNiPr2)2(CO)2(PPh3)2ꢀ2 HOTf
with terminal bidentate carbamato ligands, the Ruꢀ
/
O
˚
1
distances range from 2.105(4) to 2.250(4) A, slightly
longer than the corresponding distances in the
[Ru(O2CNiPr2)(CO)2(PPh3)2]ꢀ cation. In Ru(CO3)-
0 [Ru(O2CNiPr2)(CO)2(PPh3)2][OTf]
2
ꢀ[NHi2Pr2][OTf]ꢀCO2
(1)
(2)
(CO)2(PPh3)2 [1], where the carbonato is terminal
˚
O distance [2.079(2) A] is shorter
bidentate, the Ruꢀ
/
2ꢀ2 HOTf 0 Ru(OTf)2(CO)2(PPh3)2
3
than in 2, as expected in view of the double negative
charge of the ligand; the OꢀRuꢀO bite angle is 62.7(2)8,
comparable to that observed in 2 (60.78). The RuꢀCO
ꢀ[NHi2Pr2](OTf)ꢀCO2
/
/
/
By reaction with 2 more equiv. of triflic acid, a second
equivalent of CO2 is slowly released with formation of 3
(see Eq. (2)). The low solubility of 2 in toluene can
explain its transient accumulation. Compound 3 is well
soluble in toluene, suggesting to be a non-ionic mono-
nuclear complex. The IR spectrum of the product
indicates that the carbonyl ligands maintain the relative
cis position, two stretching vibrations at 2074 and 2012
cmꢂ1 being observed. These bands are nearly coincident
with those of 2, which carries a positive charge. A band
at 1328 cmꢂ1 is typical of terminal monodentate OTf
groups [2a,14b]: for instance, Ru(O3SCF3)2(dppe)(CO)2,
containing a monodentate triflato, as confirmed by an
X-ray investigation [3a], has an absorption band at 1329
˚
distance [1.880(3) A] is similar to those observed in 2.
In the crystal the cations are disposed with the Pꢀ ꢀ ꢀP
axis parallel to b with the metal and the other ligands
lying on the mirrors spanned by b/2. The closest
interionic approach is between the carbonyl groups
˚
and the triflate anion at a Ruꢀ ꢀ ꢀS distance of 5.65 A.
The ion pairs are arranged in rows in the c direction,
spaced by the solvent molecules.
Although the field of the ruthenium N,N-dialkylcar-
bamato complexes has been recently enriched with some
new contributions [1,15], examples of cationic species
are rare [6], as reported in Section 1. In [Ru(O2CN-
Me2)(PMe2Ph)4][PF6] [6a], obtained from [RuH(P-
Me2Ph)5][PF6], CO2 and NHMe2, the carbamato
ligand is terminal bidentate, as in 2.
cmꢂ1
.
Compound 3, Ru(OTf)2(CO)2(PPh3)2, has already
The formation of 2 in toluene, even in the presence of
an excess of triflic anhydride, is presumably due to its
been described in the literature [5], being obtained by
the
reaction
of
the
ruthenium(0)
complex
Ru(CO)3(PPh3)2 with triflic acid. The spectroscopic
data reported earlier (31P NMR: 22.7 ppm; IR: nCO
2080, 2021 cmꢂ1) do not agree with our data (31P
NMR: 20.2 ppm; IR: nCO 2074, 2012 cmꢂ1). As the
compound is affected by moisture, we suggest that the
discrepancy may be reconciled by the formation of
aquo-complexes. As a matter of fact, upon ageing,
CH2Cl2 solutions of 3 show an additional 31P NMR
peak at 23.2 ppm beside the main one at 20.2 ppm. In
order to confirm our hypothesis, 3 was treated with the
stoichiometric amount of water in CDCl3 and the
system was monitored by 31P NMR spectroscopy: the
intensity of the original signal at 20.2 ppm gradually
decreased while that of the new signal at 23.2 ppm
increased. A Nujol IR spectrum of the resulting solid
Table 2
Bond lengths (A) and angles (8) for [Ru(O2CNiPr2)(CO)2-
˚
(PPh3)2](OTf)×
/
0.5 toluene×CH2Cl2
/
Bond lengths
Ruꢀ
Ruꢀ
Ruꢀ
/
C(1)
C(2)
P
1.872(17)
1.863(16)
2.420(2)
Ruꢀ
Ruꢀ
/
O(3)
2.088(10)
2.157(9)
/
/O(4)
/
Bond angles
C(1)ꢀ
C(1)ꢀ
C(2)ꢀ
O(3)ꢀ
C(1)ꢀ
C(2)ꢀ
/
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
/
C(2)
O(3)
O(4)
92.4(6)
99.4(6)
15.9(5)
62.3(4)
161.6(6)
168.2(4)
Pꢀ
Pꢀ
Pꢀ
Pꢀ
Pꢀ
/
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
/
C(1)
C(2)
O(3)
O(4)
P?
92.84(6)
89.74(7)
89.68(7)
87.35(6)
174.3(1)
/
/
/
/
/
/
/
/
/
/
O(4)
O(4)
O(3)
/
/
/
/
/
/
/
/
Symmetry transformations: ?ꢃ
/
x, ꢂy, z.
/

416
D.B. Dell’Amico et al. / Inorganica Chimica Acta 334 (2002) 411ꢁ418
/
[RuH(CO)3(PPh3)2](OTf)ꢀNEt30 Ru(CO)3(PPh3)2
ꢀ[NEt3H](OTf)
product showed that the original CO stretchings were
displaced to 2082 and 2027 cmꢂ1, while the band at
1328 cmꢂ1, assigned to the coordinated triflato group,
had disappeared being substituted by two bands at 1260
and 1032 cmꢂ1 attributable to the triflate ion and by a
broad absorption at 3250 cmꢂ1 due to water. These
data suggest the formation of a cationic aquo-complex
through the substitution of the terminal monodentate
triflato ligand.
Triflato ligand substitution by water with formation
of ionic aquo-complexes of ruthenium(II) has been
reported, documented by the structural characterization
of the solid products [3]. Moreover, spectroscopic
evidence of rapid equilibria in solution involving tri-
flato- and aquo-complexes has been reported [3]. The
lability of this family of low-spin hexacoordinated
ruthenium(II) derivatives can be exploited for the
preparation of a series of ruthenium derivatives, as
pointed out by Wojcicki and coworkers [4].
In order to confirm the nature of our product, we
have prepared 3 by the already quoted literature method
[5], see Eq. (3), at the reflux temperature of toluene.
Under these conditions and also by reacting
RuCl2(CO)2(PPh3)2 with Ag(O3SCF3), and by operating
under exclusion of moisture, we obtained a product with
spectroscopic features identical to those discussed
above.
(5)
Spectroscopic evidence of the formation of protona-
tion products by reaction of Ru(CO)3(PPh3)2 with
strong protic acids has been reported in the literature,
and the derivatives were described to be difficult to
isolate in a pure form [17]. In the course of our work, 4
was obtained in good yields and its IR spectrum shows
three bands attributable to CO stretching vibrations at
2139 (w), 2083 (s) and 2069 (s) cmꢂ1. These bands
compare well with those [at 2138 (m), 2077 (s) and 2055
(s) cmꢂ1] reported for mer-[RuI(CO)3(PPh3)2]I contain-
ing the mer-M(CO)3 fragment, and the two phosphine
ligands reciprocally trans [18]. Bands due to the triflato
group are found in the region typical of the ionic
derivatives. The 31P NMR displays a resonance at 34.9
ppm in CDCl3, similar to [RuH(CO)3(PPh3)2](O2CCF3)
[17c] and to [RuH(CO)3(PPh3)2]Cl [17c], both showing a
1
resonance at 34.5 ppm. In the H NMR spectrum, the
hydride absorbs at ꢂ6.4 ppm, the signal having multi-
/
plicity three by coupling with the two equivalent
phosphorus nuclei. The hydride resonances for
[RuH(CO)3(PPh3)2](O2CCF3)
[RuH(CO)3(PPh3)2]Cl are reported at ꢂ
and
6.1 and ꢂ6.2
/
/
ppm, respectively [17c]. In the 13C NMR spectrum, two
triplets are attributable to the CO ligands, the less
intense, at 189.8 ppm, being reasonably due to the
ligand trans to the hydride, the other one, at 192.3 ppm,
to the reciprocally trans carbonyls.
Ru(CO)3(PPh3)2 ꢀ2 HOTf 0 Ru(OTf)2(CO)2(PPh3)2
ꢀproducts
(3)
A suspension of [RuH(CO)3(PPh3)2][OTf] (4), was
refluxed in toluene and, after cooling and addition of
methanol to the resulting solution, colourless crystals of
[RuH(CO)2(MeOH)(PPh3)2][OTf] (5), were obtained.
Under these conditions of reduced partial pressure of
CO, one of the carbonyl groups is lost and replaced by
methanol (Eq. (6)).
In the hypothesis that reaction (3) is preceeded by a
primary oxidative addition of TfOH to ruthenium(0),
the reaction was carried out at room temperature. The
formation of a colourless solid, corresponding to the
species [RuH(CO)3(PPh3)2](OTf) (4), was observed,
being characterized by a 31P NMR signal (CH2Cl2
solution) at 34.5 ppm.
[RuH(CO)3(PPh3)2][OTf]ꢀMeOH
4
0 [RuH(CO)2(MeOH)(PPh3)2][OTf]ꢀCO
(6)
Ru(CO)3(PPh3)2 ꢀTfOH
5
0 [RuH(CO)3(PPh3)2](OTf)
(4)
Product 5 has been structurally characterized. In the
cation, see Fig. 2, ruthenium is hexa-coordinated in a
distorted octahedral geometry. The most significant
bond distances and angles are reported in Table 3.
Ruthenium, carbonyls, hydride and methanol ligands
are placed on a plane which is the mirror relating the
two phosphines. The presence of four monodentate
ligands releases some constraint and allows a coordina-
4
Product 4 in CDCl3 does not react with an excess of
triflic acid at room temperature in a week time. More
than 10 days are necessary to observe, in the 31P NMR
spectrum of the solution, signals due to small amounts
of 3. On the contrary, 4 reacts quickly with NEt3 with
production of the precursor Ru(CO)3(PPh3)2 (Eq. (5)),
this result showing that triethylamine is a sufficiently
strong Lewis base to deprotonate ruthenium(II). This is
a two-electron process, leading to ruthenium(0). Reac-
tion (5) is reminiscent of the two-electron reductive
elimination operated by tertiary amines on CoH(CO)4
giving the trialkylammonium derivatives (R3NH)-
[Co(CO)4] [16].
tion geometry close to the ideal octahedron. The COꢀ
RuꢀCO?, C(1)ꢀRuꢀO(3), C(2)ꢀRuꢀH(1) and O(3)ꢀ
RuꢀH(1) angles are in fact close to 908. The RuꢀCO
distances are significantly different, namely 1.981 and
/
/
/
/
/
/
/
/
/
˚
1.855 A for the CO ligands opposite to the hydride and
to methanol, respectively. Moreover, the PꢀRuꢀP?
angle is reduced to 164.98 with the RuꢀP bonds leaning
/
/
/

D.B. Dell’Amico et al. / Inorganica Chimica Acta 334 (2002) 411ꢁ
/
418
417
The NMR spectra of the product in CDCl3 are relatively
complex: the protonic spectrum shows a multiplet
centred at about 7.6 ppm due to the aromatic nuclei,
one quadruplet (5.6 ppm) and one doublet (1.7 ppm)
due to coordinated methanol, two singlets at 3.7 and 3.5
ppm attributed to uncoordinated methanol and two
triplets in the hydride region at ꢂ
/
3.6 and ꢂ4.3 ppm;
/
two 31P resonances are observed at 44.1 and 41.2 ppm,
the former of higher intensity. Moreover, two 19F
signals are found at ꢂ
addition of some drops of methanol to the solution
causes a simplification of the spectra, single 31P and 19
resonances at 44.1 and ꢂ78.7 ppm, respectively being
observed together with a single triplet (ꢂ4.3 ppm) due
to the hydride ligand in the H NMR spectrum. If the
solution was evaporated to dryness and treated in vacuo
to remove completely the solvents, the residue, dissolved
in CDCl3, shows again the original NMR spectra
showing coordinated methanol. This behaviour can be
explained by the following equilibrium in solution.
/
78.3 and ꢂ
/
78.7 ppm. The
F
/
Fig. 2. Structure of the [RuH(CO)2(MeOH)(PPh3)2]ꢀ cation. The Ru,
P and some of the C and O atoms are represented by ellipsoids at 30%
probability; two hydrogen atoms are represented as spheres of
arbitrary radii. The apexes of the labels have the same meaning as in
Table 3. The hydrogen interaction of the coordinated methanol with
the O(5) atom of the disordered anion is represented by a dashed line.
/
1
Table 3
˚
Bond lengths (A) and angles (8) for [RuH(CO)2(MeOH)(PPh3)2](OTf)
(5)
Bond lengths
Ruꢀ
Ruꢀ
Ruꢀ
/
C(1)
C(2)
P
1.981(7)
1.855(7)
2.389(1)
Ruꢀ
Ruꢀ
/
O(3)
2.141(5)
1.57(6)
/
/H(1)
/
Bond angles
Methanol and OTfꢂ compete for the coordination
sphere, the reaction being presumably balanced from a
thermodynamic point of view.
It is interesting to note that in compound 2 the
presence of a carbamato group, which acts as a
bidentate ligand, is sufficient to prevent the triflato
group from being coordinated [2]. This is consistent with
the expulsion of ruthenium-coordinated triflato groups
and with the formation of ionic products observed in the
presence of oxygen-, nitrogen-, and phosphorous donors
[3,4].
C(1)ꢀ
C(1)ꢀ
C(2)ꢀ
O(3)ꢀ
PꢀRuꢀ
/
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
C(1)
/
C(2)
O(3)
H(1)
94.8(3)
89.8(3)
93(2)
Pꢀ
Pꢀ
Pꢀ
Pꢀ
/
Ruꢀ
Ruꢀ
Ruꢀ
Ruꢀ
/
C(2)
O(3)
H(1)
P?
89.41(3)
89.99(3)
82.53(3)
164.92(6)
/
/
/
/
/
/
/
/
/
/
H(1)
82(2)
/
/
/
/
97.54(3)
Symmetry transformations: ?ꢃ
/
x, ꢂ
/
yꢀ1/2, z.
/
towards the less hindered hydride ligand. C2 symmetry is
however, rigorously maintained in the cation. The anion
is disordered in the crystal, being placed slightly out of
the mirror plane. The m operation produces another
equally populated position on the opposite side. The
two positions of the triflate have an almost coincident
oxygen, labelled as O(5) and O(5?) in Fig. 2, due to the
˚
4. Conclusions
hydrogen bond [O(3)ꢀ ꢀ ꢀO(5), 2.562 A] with the coordi-
nated methanol.
˚
H distance is about 1.6 A, to be compared
Taking the earlier results [1] into additional consid-
eration, the chemistry of these systems of ruthenium(II)
appears to be dictated by the requirement for the central
metal atom to attain the 18-electron configuration. The
hapticity of the potentially mono- or bidentate ligand
(R2NCO2), as confirmed by the X-ray diffraction
structural data, can therefore be predicted on this basis.
The Ruꢀ
/
˚
with the value of 1.7 A reported for [RuH(CO)2(H2O)-
(PPh3)2](BF4) [19], whose cation has a geometric dis-
tribution of the ligands analogous to that observed in 5,
with the H2O ligand replacing MeOH. The Ruꢀ
/
OH2
distance is 2.15 A. As in 2, the coordination around
ruthenium is distorted octahedral with the PꢀRuꢀ
angle of 165.18. The RuꢀCO bond distances are
different, the carbonyl trans to H2O being closer to
˚
/
/P
/
˚
the metal (1.83 A) than that trans to the hydride (1.97
5. Supplementary material
˚
A).
The IR spectrum of 5 displays two bands at 2067 and
2007 cmꢂ1 attributed to the CO stretching vibrations.
Crystallographic data (excluding structure factors)
have been deposited with the Cambridge Crystallo-

418
D.B. Dell’Amico et al. / Inorganica Chimica Acta 334 (2002) 411ꢁ418
/
[7] (a) N. Ahmad, J.J. Levison, S.D. Robinson, M.F. Uttley, Inorg.
Synth. 15 (1974) 50;
graphic Data Centre, CCDC Nos. 176709 and 176710
for compounds 2 and 5. Copies of this information may
be obtained free of charge from The Director, CCDC,
(b) N. Ahmad, S.D. Robinson, M.F. Uttley, J. Chem. Soc.,
Dalton Trans. (1972) 843.
12 Union Road, Cambridge, CB2 1EZ, UK (fax: ꢀ44-
/
[8] J.P. Collman, W.R. Roper, J. Am. Chem. Soc. 87 (1965) 4008.
[9] C.T. North, C. Phillips, F.S. Mathews, Acta Crystallogr. A24
(1968) 351.
1223-336-033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
[10] G.M. Sheldrick, SHELXTL-PLUS, rel. 5.1, Siemens Analytical X-
Ray Instruments Inc., Madison, WI, USA, 1997.
[11] XSCANS, X-ray Single Crystal Analysis System, rel. 2.1 Siemens
Analytical X-ray Instruments Inc., Madison, WI, USA, 1994.
[12] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
[13] (a) D. Belli Dell’Amico, F. Calderazzo, F. Marchetti, G. Perego,
J. Chem. Soc., Dalton Trans. (1983) 483;
Acknowledgements
The authors wish to thank the Ministero dell’Univer-
sita` e della Ricerca Scientifica e Tecnologica (MURST),
Programmi di Ricerca Scientifica di Rilevante Interesse
Nazionale, Cofinanziamento 2000-1, for financial sup-
port. The authors are grateful to Dr Alessandra Merigo
[20] for the synthesis and characterization of (NHi2-
Pr2)(OTf).
(b) D. Belli Dell’Amico, F. Calderazzo, B. Giovannitti, G. Pelizzi,
J. Chem. Soc., Dalton Trans. (1984) 647;
(c) D. Belli Dell’Amico, F. Calderazzo, U. Giurlani, G. Pelizzi,
Gazz. Chim. Ital. 116 (1986) 609;
(d) A. Belforte, D. Belli Dell’Amico, F. Calderazzo, M. Devillers,
U. Englert, Inorg. Chem. 32 (1993) 2282;
(e) D. Belli Dell’Amico, D. Boschi, F. Calderazzo, S. Ianelli, L.
Labella, F. Marchetti, G. Pelizzi, E.G. F. Quadrelli, Inorg. Chim.
Acta 300ꢁ302 (2000) 882 (and references therein).
/
References
[14a] D.H. Johnston, D.F. Shriver, Inorg. Chem. 32 (1993) 1045.
[14b] N.E. Dixon, W.G. Jackson, M.J. Lancaster, G.A. Lawrance,
A.M. Sargeson, Inorg. Chem. 20 (1981) 470.
[1] D. Belli Dell’Amico, F. Calderazzo, L. Labella, F. Marchetti, J.
Organomet. Chem. 596 (2000) 144.
[2] (a) G.A. Lawrance, Chem. Rev. 86 (1986) 17;
[15] T. Tsuda, M. Shiro, Organometallics 18 (1999) 2741.
[16] (a) F. Calderazzo, G. Fachinetti, F. Marchetti, P.F. Zanazzi,
Chem. Commun. (1981) 181;
(b) W. Beck, K. Sunkel, Chem. Rev. 88 (1988) 1405.
¨
[3] (a) M.F. Mahon, M.K. Whittlesey, P.T. Wood, Organometallics
18 (1999) 4068;
(b) L. Brammer, M.C. McCann, R.M. Bullock, R.K. McMullan,
P. Sherwood, Organometallics 11 (1992) 2339.
(b) J.F. Bickley, S.J. Higgins, C.A. Stuart, A. Steiner, Inorg.
Chem. Commun. 3 (2000) 211.
[17] (a) S. Singh, M.C. Baird, J. Organomet. Chem. 338 (1988) 255;
(b) B.F.G. Johnson, J.A. Segal, J. Organomet. Chem. 31 (1971)
C79;
[4] P.W. Blosser, J.C. Gallucci, A. Wojcicki, Inorg. Chem. 31 (1992)
2376.
(c) B.F.G. Johnson, J.A. Segal, J. Chem. Soc., Dalton Trans.
(1973) 478.
[5] (a) P.A. Harding, M. Preece, S.D. Robinson, K. Henrick, Inorg.
Chim. Acta 118 (1986) L31;
[18] (a) H.B. Kuhnhen, J. Organomet. Chem. 105 (1976) 357;
(b) H.B. Kuhnhen, J. Organomet. Chem. 129 (1977) 215.
[19] S.M. Boniface, G.R. Clark, T.J. Collins, W.R. Roper, J.
Organomet. Chem. 206 (1981) 109.
(b) P.A. Harding, S.D. Robinson, K. Henrick, J. Chem. Soc.,
Dalton Trans. (1988) 415.
[6] (a) T.V. Ashworth, M. Nolte, E. Singleton, J. Organomet. Chem.
121 (1976) C57;
(b) T.V. Ashworth, M.J. Nolte, E. Singleton, S. Afr. J. Chem. 31
(1978) 149.
[20] A. Merigo, PhD Thesis, Universita` di Pisa, Pisa, 1999.