Triphenylphosphine-substituted N,N-di-iso-propylcarbamate of ruthenium(II) and its reactions with carbon monoxide

Article abstract of DOI:10.1016/s0022-328x(99)00612-9

Chloride displacement from RuCl₂(PPh₃)₃ by NHⁱPr₂/CO₂ in toluene as medium gave the N,N-di-iso-propylcarbamato derivative Ru(O₂CNⁱPr₂)₂(PPh₃) ₂, (1), whose X-ray crystal structure determination showed the mononuclear compound to contain hexacoordinated ruthenium bonded to bidentate carbamato and to cis-arranged tertiary phosphine groups in a distorted octahedral geometry. Carbonylation at room temperature rapidly converted 1 to the monocarbonyl derivative Ru(O₂-CNⁱPr₂)₂(PPh₃) ₂(CO) (2), presumably containing a monodentate carbamato group, the dicarbonyl compound Ru(O₂CNⁱPr₂)₂-(PPh₃) ₂(CO)₂ (3) being formed over longer reaction times. X-ray diffraction data showed 3 to contain hexacoordinate ruthenium(II) with monodentate carbamato groups trans to the carbonyl groups and with trans-arranged triphenylphosphine groups. Controlled hydrolysis of 3 yielded the dicarbonyl-carbonato complex Ru(O₃C)(PPh₃)₂(CO)₂·H ₂O (4), crystallographically established to contain a bidentate carbonato group, trans triphenylphosphine ligands and water hydrogen-bonded to the carbonato ligand.

Full text of DOI:10.1016/s0022-328x(99)00612-9

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 596 (2000) 144–151
Triphenylphosphine-substituted N,N-di-iso-propylcarbamate of
ruthenium(II) and its reactions with carbon monoxide
Daniela Belli Dell’Amico a, Fausto Calderazzo a,*, Luca Labella a, Fabio Marchetti b
a Dipartimento di Chimica e Chimica Industriale, Via Risorgimento 35, I-56126 Pisa, Italy
b Dipartimento di Ingegneria Chimica, dei Materiali, delle Materie Prime e Metallurgia, Uni6ersita` ‘La Sapienza’ di Roma,
6ia del Castro Laurenziano,7, Box 15 Roma 62, I-00185 Rome, Italy
Received 28 August 1999
Dedicated to Professor Frank Albert Cotton in recognition of his outstanding contributions to inorganic chemistry, on the
occasion of his 70th birthday
Abstract
Chloride displacement from RuCl2(PPh3)3 by NHiPr2/CO2 in toluene as medium gave the N,N-di-iso-propylcarbamato
derivative Ru(O2CNiPr2)2(PPh3)2, (1), whose X-ray crystal structure determination showed the mononuclear compound to contain
hexacoordinated ruthenium bonded to bidentate carbamato and to cis-arranged tertiary phosphine groups in a distorted
octahedral geometry. Carbonylation at room temperature rapidly converted 1 to the monocarbonyl derivative Ru(O2-
CNiPr2)2(PPh3)2(CO) (2), presumably containing a monodentate carbamato group, the dicarbonyl compound Ru(O2CNiPr2)2-
(PPh3)2(CO)2 (3) being formed over longer reaction times. X-ray diffraction data showed 3 to contain hexacoordinate
ruthenium(II) with monodentate carbamato groups trans to the carbonyl groups and with trans-arranged triphenylphosphine
groups. Controlled hydrolysis of 3 yielded the dicarbonyl-carbonato complex Ru(O3C)(PPh3)2(CO)2·H2O (4), crystallographically
established to contain a bidentate carbonato group, trans triphenylphosphine ligands and water hydrogen-bonded to the
carbonato ligand. © 2000 Elsevier Science S.A. All rights reserved.
Keywords: Carbamato complexes; Ruthenium; Carbonylation; Structure
1. Introduction
require both specific reaction conditions and especially
designed precursors for their preparation to be success-
ful. Cotton and Chisholm and their coworkers [16–18],
together with Lappert [19], have pioneeered the area of
N,N-dialkylcarbamato complexes of early transition el-
ements (generally in their d0 electronic configuration),
as prepared by carbonatation of the corresponding
N,N-dialkylamide derivatives.
N,N-carbamato complexes of ruthenium have been
little studied until now, the only known examples being
the cationic N,N-dimethylcarbamates [Ru(O2CNMe2)-
(PMe2Ph)4]+ and [Ru(CO)(O2CNMe2)(PMe2Ph)4]+
(isolated as their hexafluorophosphate derivatives) [20]
and a neutral complex of formula Ru(O2CNEt2)3 of
unknown structure produced [21] in milligram quanti-
ties and in low yields (due to secondary reactions) by
one of us through the reaction of RuCl3·3L (L=Et2S)
with the NHEt2/CO2 system.
Coordination compounds of ruthenium(II) have at-
tracted considerable interest [1] both for their scientific
relevance and for their catalytic properties, especially in
connection with hydrogenation of unsaturated sub-
strates [1c]. Halo- [2–5], carboxylato- [6–12] and sul-
fonato [13] complexes have been studied more
extensively, together with their interaction with carbon-
based ligands, such as carbon monoxide.
Several years ago we initiated a study of the relatively
new area of N,N-dialkylcarbamato complexes of transi-
tion- and non-transition elements of general formula
M(O2CNR2)n, including late transition metals of the 4d
series, such as silver [14] and palladium [15], which
* Corresponding author. Tel.: +39-050-20218.
E-mail address: facal@dcci.unipi.it (F. Calderazzo)
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(99)00612-9

D.B. Dell’Amico et al. / Journal of Organometallic Chemistry 596 (2000) 144–151
145
We now wish to report that the reaction of
2. Results and discussion
RuCl2(PPh3)3 with NHiPr2/CO2 produces the corre-
sponding triphenylphosphine-substituted carbamato
complex of ruthenium(II) Ru(O2CNiPr2)2(PPh3)2 (1).
We also have carried out the reactions of this com-
pound with carbon monoxide yielding the correspond-
ing mono- (2), and dicarbonyl (3), adducts, whereas
the controlled hydrolysis of 3 under an inert atmo-
sphere gave the dicarbonyl-carbonato derivative 4,
Ru(O3C)(CO)2(PPh3)2·H2O. The crystal and molecular
structures of 1, 3 and 4 are reported.
The homoleptic N,N-di-iso-propylcarbamato deriva-
tive of ruthenium(II) 1 was obtained by chloride dis-
placement from RuCl2(PPh3)3 with NHiPr2/CO2 in
toluene as medium, see Eq. (1):
RuCl2(PPh3)3+4NHiPr2+2CO2
“PPh3+Ru(O2CNiPr2)2(PPh3)2+2[NH2 Pr2]Cl (1)
i
1
Complete chloride substitution on RuCl2(PPh3)3 re-
quires several hours to proceed to completion. Shorter
reaction times may lead to partial substitution. The
red–orange product is well soluble in common organic
solvents; its IR spectrum shows strong bands at-
tributable to the carbamato ligands around 1500
cm−1, which is suggestive of bidentate linkage [22,23].
Moreover, the 31P-NMR spectrum, showing one signal
only, suggested the presence of equivalent phosphine
ligands. This structural evidence in solution was subse-
quently confirmed by X-ray diffraction data on a single
crystal.
The molecular structure of compound 1 is shown in
Fig. 1, the more significant bond distances and angles
being listed in Table 1.
Ruthenium is hexacoordinate with cis-arranged PPh3
ligands. However, the bite angle of the carbamato
ligands is small, giving rise to a very distorted octahe-
dral geometry. Within each carbamato group, the oxy-
gen atoms are connected to ruthenium through a small
O–Ru–O angle of 60.7°. The large free space thus
available around the metal allows the sterically hin-
dered triphenylphosphines to increase the P–Ru–P
angle to 99.3°. A closely resembling geometry was
found in L–(S)–(2,2%-bisdiphenylphosphino-1,1%-bi-
naphthyl-P,P%)-bisbutyratoruthenium(II) [24] and in
cis-bisacetato[t-butyl-bis(2-thienyl)phosphine]ruthen-
ium(II) [25], the latter as the dichloromethane solvate.
Two oxygen atoms, O(2) and O(4), occupy approxi-
mately trans positions with respect to the phosphine
ligands, the P–Ru–O angles being 156.0 and 157.6°,
respectively. The oxygen atoms O(1) and O(3) are
substantially cis to both phosphine ligands, see Fig. 1
and bond angles of Table 1. The Ru–O bonds trans to
Fig. 1. View of the molecular structure of 1. Thermal ellipsoids are at
30% probability. All hydrogen atoms and the methyl groups of
carbamates are removed for clarity.
Table 1
i
,
Bond distances (A) and angles (°) for compound 1, Ru(O2CN Pr2)2-
(PPh3)2, with estimated S.D.s in parentheses
Bond distances
Ru–O(1)
Ru–O(2)
Ru–O(3)
Ru–O(4)
Ru–P(1)
2.105(4)
2.250(4)
2.112(4)
2.231(4)
2.2465(18)
Ru–P(2)
2.2408(18)
1.279(7)
1.281(7)
1.279(6)
1.270(7)
O(1)–C(1C)
O(2)–C(1C)
O(3)–C(8C)
O(4)–C(8C)
,
phosphine are 0.14 A longer than the cis ones, thus
making the bite of the bidentate carbamato ligand an
asymmetric one.
Bond angles
O(1)–Ru–O(3)
O(1)–Ru–O(4)
O(3)–Ru–O(4)
O(1)–Ru–P(2)
O(3)–Ru–P(2)
O(4)–Ru–P(2)
O(1)–Ru–P(1)
O(3)–Ru–P(1)
O(4)–Ru–P(1)
P(2)–Ru–P(1)
158.01(14)
102.29(15)
60.75(14)
93.37(12)
99.72(12)
157.63(11)
96.01(12)
99.19(12)
94.91(12)
99.28(6)
O(1)–Ru–O(2)
O(3)–Ru–O(2)
O(4)–Ru–O(2)
P(2)–Ru–O(2)
P(1)–Ru–O(2)
C(1C)–O(1)–Ru
C(1C)–O(2)–Ru
C(8C)–O(3)–Ru
C(8C)–O(4)–Ru
60.72(15)
101.78(15)
85.39(16)
88.53(12)
156.02(11)
93.3(3)
86.8(4)
92.2(3)
87.1(3)
Compound 1 was found to undergo carbonylation in
two steps; the first rapid step, see Eq. (2), leads to the
monocarbonyl derivative 2, followed by the relatively
slow addition of a second CO molecule to give the
disubstitution product 3:
Ru(O2CNiPr2)2(PPh3)2+CO
“Ru(O2CNiPr2)2(PPh3)2(CO)
(2)
2

146
D.B. Dell’Amico et al. / Journal of Organometallic Chemistry 596 (2000) 144–151
2050 cm−1, corresponding to a shift of about 100
cm−1, with respect to both the halo- and the carbam-
ato substituted derivatives, as one would expect taking
into consideration the electron-withdrawing effect of
the fluorinated R groups.
The dicarbonyl derivative 3 has two IR CO stretch-
ing vibrations, suggesting the presence of mutually cis
carbonyl groups. Moreover, intense IR absorptions,
due to the O2CN moiety, are present in the region just
below 1600 cm−1, corresponding to a shift of about
100 cm−1 above the absorptions typical of compound
1. This is suggestive of the conversion from bidentate
carbamato groups to monodentate ones on going from
1 to 3. In this connection, it is interesting to note that
in the silicon derivative Si(O2CNR2)4 [26] the monoden-
Fig. 2. View of the molecular structure of 3. Thermal ellipsoids are at
30% probability. All hydrogen atoms and the methyl groups of
carbamates are removed for clarity.
tate carbamato groups absorb at about 1700 cm−1
.
The molecular structure of 3 can be described as the
octahedrally arranged disposition of the substituents
around ruthenium(II), with mutually cis monodentate
carbamato and carbonyl groups and with mutually
trans phosphine ligands. The molecular structure is
shown in Fig. 2 and a selected list of bond distances
and angles is in Table 2.
The coordination geometry closely approaches that
of an ideal octahedron, the residual distortions being
due to the different steric hindrance of the ligands. A
similar bonding situation has been observed in two
dicarbonyl-biscarboxylato triphenylphosphino-substi-
tuted derivatives of ruthenium(II) [10,27]. As expected,
the monodentate carbamato groups of 3 show a consid-
erable difference of C–O bond lengths (0.06 and 0.08
Table 2
,
Bond lengths (A) and angles (°) for compound 3,
Ru(O2CNiPr2)2(PPh3)2(CO)2, with estimated S.D.s in parentheses
Bond distances
Ru–C(2)
Ru–C(1)
Ru–O(1C)
Ru–O(3C)
Ru–P(1)
Ru–P(2)
1.862(9)
1.882(8)
2.076(5)
2.090(5)
2.402(2)
2.411(2)
C(1)–O(1)
C(2)–O(2)
O(1C)–C(1C)
O(2C)–C(1C)
O(3C)–C(8C)
O(4C)–C(8C)
1.117(8)
1.148(9)
1.313(9)
1.231(8)
1.296(9)
1.235(9)
Bond angles
C(2)–Ru–C(1)
C(2)–Ru–O(1C)
C(1)–Ru–O(1C)
C(2)–Ru–O(3C)
C(1)–Ru–O(3C)
O(1C)–Ru–O(3C)
C(2)–Ru–P(1)
C(1)–Ru–P(1)
O(1C)–Ru–P(1)
O(3C)–Ru–P(1)
86.1(4)
96.3(3)
176.0(3)
175.7(3)
97.3(3)
80.47(19)
90.9(3)
90.8(2)
C(2)–Ru–P(2)
C(1)–Ru–P(2)
O(1C)–Ru–P(2)
O(3C)–Ru–P(2)
P(1)–Ru–P(2)
O(1)–C(1)–Ru
O(2)–C(2)–Ru
91.2(2)
90.6(2)
86.24(14)
91.55(14)
177.58(9)
174.1(8)
174.5(8)
,
A) between the terminal and the bridging oxygen
atoms. The ruthenium–CO bonds have the same length
,
(1.87 A) as in the two just mentioned dicarbonyl deriva-
tives of ruthenium(II) [10,27].
C(1C)–O(1C)–Ru 123.2(5)
C(8C)–O(3C)–Ru 122.5(5)
The fact that di-iso-propylcarbamato derivative of
ruthenium(II) has the same overall geometry as the
corresponding dicarboxylato derivatives [10,27] con-
firms the general observation [23] that carboxylates and
carbamates of low nuclearity (mono- or dinuclear) have
frequently similar structures.It is interesting to note that
the slow addition of the second CO molecule to 2 can
be rationalized by taking into consideration the molec-
ular structure of the resulting compound 3 showing that
a dramatic structural change has occurred on going
from 1 to 3. The more drastic change concerns the
disposition of the phosphine ligands becoming almost
exactly trans in 3.
92.25(14)
86.33(14)
Ru(O2CNiPr2)2(PPh3)2(CO)+CO
“Ru(O2CNiPr2)2(PPh3)2(CO)2
(3)
3
With the molecular parameters of 1 being available,
it is quite reasonable to assume that the fast addition of
the first CO group corresponds to the conversion of one
of the carbamato groups from bidentate to monoden-
tate, thus leaving a free coordination site for the incom-
ing CO. The monocarbonyl derivative is characterized
by an IR CO stretching vibration at 1936 cm−1, in
agreement with similar findings for the halo-monocar-
bonyl derivatives of ruthenium(II) [2,5] of formula
Controlled hydrolysis of the carbamato complex 3
led to the carbonato derivative 4 according to Eq. (4):
Ru(O2CNiPr2)2(PPh3)2(CO)2+2H2O
“Ru(O3C)(PPh3)2(CO)2·H2O+CO2+2NHiPr2 (4)
RuX2(CO)(PR3)3, showing
a carbonyl absorption
around 1950 cm−1. The monocarbonyl derivatives of
ruthenium(II) with perfluorinated carboxylato groups
[8] of formula Ru(O2CR)2(CO)(PPh3)2 absorb at about
4
Reaction (4) has been carried out with a twofold excess
of water, see Section 4, taking into consideration that

D.B. Dell’Amico et al. / Journal of Organometallic Chemistry 596 (2000) 144–151
147
Ag2O/NHiPr2/CO2 system, invariably led to the corre-
sponding carbonate Ag2CO3, presumably through the
intermediacy of the expected but unstable carbamato
derivative.
A projection of the molecular structure of compound
4 is shown in Fig. 3, while Table 3 collects a selection of
some relevant bond distances and angles. The carbon-
ato ligand has bidentate coordination. The phosphines
are trans with a P–Ru–P angle of 176°, to be compared
with the corresponding angle of 177.6° for compound 3.
Similar again to compound 3, the Ru–P bonds are
the compound crystallizes with one molecule of water
per ruthenium. It is important to realize that reaction
(4) must be carried out under an inert atmosphere; as a
matter of fact, the hydrolysis of 1 or 3 under carbon
monoxide leads to reduction forming the carbonyl
derivative of ruthenium(0), Ru(CO)3(PPh3)2, vide infra.
Compound 4 shows two strong carbonyl stretching
vibrations at 2046 and 1982 cm−1, suggestive of a cis
arrangement of the CO ligands. Moreover, it displays
bands at 1651 and 1626 cm−1, consistent with the
presence of a bidentate carbonato group [28], although
a contribution from hydrogen-bonded water to the
lower wavenumber vibration cannot be excluded. The
failure to detect nitrogen analytically in the compound
indicated that the starting carbamato derivative had
undergone complete hydrolysis. Earlier attempts in
these laboratories [14] to prepare the iso-propylcarbam-
ato derivative of silver, Ag(O2CNiPr2), through the
,
elongated to about 2.4 A, with respect to the value of
,
about 2.2 A in compound 1. Since the steric hindrance
of the carbonato ligand of 4 is certainly smaller than
that of the oxygen-based anionic ligands of 1 and 3,
this finding suggests the presence of weaker Ru–P
bonds in both 3 and 4, in agreement with the literature
data [29] on trans-diphosphino derivatives of ruthen-
ium(II). The molecule possesses a twofold axis of sym-
metry passing through C(2) and O(3). Within the car-
bonato group, the two C–O bonds involving the
,
ruthenium-bonded oxygens (1.311 A) are longer than
,
the third one (1.207 A). The coordination geometry is
close to that of an ideal octahedron with the exclusion
of the small O(2)–Ru–O(2%) angle of 62.7° obviously
due to the short bite of the carbonato ligand.
Mostly interesting is the fact that the coordinated
carbonato ligand is involved in a rather strong hydro-
,
gen bond with water, the O···Ow distance of 2.602 A
,
being about 0.4 A shorter than the double of the
oxygen van der Waals radius [30]. A similar example of
a water molecule interacting with a carbonato ligand
was found [31a] within the [W(CO)4(O3C)·H2O]2− an-
,
ion, but at a longer O···Ow distance of 2.834 A.
Compound 4 represents one of the few known exam-
ples of mixed carbonato-carbonyl derivatives [31b–f];
as such, it is interesting per se and for its possible
intermediacy in the reduction of the ruthenium(II) pre-
cursor to ruthenium(0) by carbon monoxide. We have
in fact also found that hydrolysis of the carbamato
derivative 3 in the presence of carbon monoxide leads
to the well established [32] ruthenium(0) complex
Ru(CO)3(PPh3)2, see Eq. (5), presumably through the
intermediacy of the carbonato complex 4, see Eq. (6).
Fig. 3. View of the molecular structure of 4. Thermal ellipsoids are at
30% probability. Hydrogen atoms and hydrogen-bonded water are
removed for clarity.
Table 3
,
Bond distances (A) and angles (°) for compound 4,
Ru(O3C)(PPh3)2(CO)2·H2O, with estimated S.D.s in parentheses a
Bond distances
Ru–C(1%)
Ru–C(1)
Ru–O(2%)
Ru–O(2)
Ru–P%
1.880(3)
1.880(3)
2.079(2)
2.079(2)
2.4151(7)
Ru–P
2.4151(7)
2.518(5)
1.134(4)
1.311(4)
1.207(7)
Ru–C(2)
C(1)–O(1)
O(2)–C(2)
C(2)–O(3)
Ru(O2CNiPr2)2(PPh3)2(CO)2+H2O+2CO
“3CO2+Ru(CO)3(PPh3)2+2NHiPr2
Ru(O3C)(CO2)2(PPh3)2+2CO
(5)
(6)
Bond angles
C(1%)–Ru–C(1)
C(1)–Ru–O(2%)
C(1)–Ru–O(2)
O(2%)–Ru–O(2)
C(1)–Ru–P%
89.68(18)
166.38(12)
103.86(12)
62.65(16)
91.88(9)
O(2)–Ru–P
P%–Ru–P
O(1)–C(1)–Ru
C(2)–O(2)–Ru
O(3)–C(2)–O(2)
O(2%)–C(2)–O(2)
86.54(7)
176.05(4)
179.3(3)
93.1(2)
124.5(2)
111.1(4)
“2CO2+Ru(CO)3(PPh3)2
It is easily recognized that release of one of the bites
of the sterically constrained carbonato complex fol-
lowed by addition of CO may lead to carbon dioxide
elimination with reduction of the central metal atom to
the zerovalent state (see Scheme 1).
O(2)–Ru–P%
90.08(6)
C(1)–Ru–P
90.92(9)
a Symmetry transformations used to generate equivalent atoms:
−x+1, y, −z+3/2.

148
D.B. Dell’Amico et al. / Journal of Organometallic Chemistry 596 (2000) 144–151
4. Experimental
4.1. General considerations
All preparations were carried out in standard
Schlenk tubes. All solvents were freshly distilled over
conventional drying agents under dinitrogen and all
reactions were carried out under an atmosphere of
dinitrogen, or carbon monoxide, or carbon dioxide, as
indicated. RuCl2(PPh3)3 was synthesized as previously
described [34]. Elemental analyses (C, H, N,) were
performed by Laboratorio di Microanalisi della Facolta`
di Farmacia, Universita` di Pisa, with a C. Erba model
1106 elemental analyzer. IR spectra were measured
with a Perkin–Elmer FT–IR model1725X spectropho-
tometer. Nuclear magnetic resonance spectra were
recorded using a Varian Gemini 200 MHz, the data
Scheme 1.
In this connection, it is interesting to recall the
isolation of an iridium complex [33] having two carbon
dioxide moieties linked together to form a five-mem-
bered metallacycle: a similar intermediate can possibly
be involved in the reduction from ruthenium(II) to
ruthenium(0).
It is interesting to note that attempts to oxidatively
add N,N-di-isopropylcarbamic acid (HOOCNiPr2, pre-
pared in situ from CO2/NHiPr2 with carbon dioxide
under pressure) to the ruthenium(0) complex Ru(CO)3-
(PPh3)2 were unsuccessful. This contrasts with the be-
haviour of carboxylic acids; the oxidative addition of
RCOOH to Ru(CO)3(PPh3)2 is in fact one of the cur-
rent methods for the preparation of ruthenium(II) car-
boxylato complexes [6,10,13].
1
being expressed in ppm from TMS for H and 13C and
from H3PO4 for 31P.
4.2. Synthesis of Ru(O2CNiPr2)2(PPh3)2 (1)
A suspension of RuCl2(PPh3)3 (1.83 g, 1.91 mmol) in
toluene (50 ml) was treated at room temperature (r.t.)
with di-iso-propylamine (3.3 ml, 25.5 mmol) and car-
bon dioxide at atmospheric pressure. After stirring for
2 days, no further absorption of CO2 was observed; a
31P-NMR spectrum of the supernatant liquid showed
only one signal at 65.6 ppm. The suspension was
filtered to eliminate [NHi2Pr2]Cl and the filtrate was
evaporated to dryness under reduced pressure. The
resulting dark orange solid was dissolved in toluene (10
ml) and heptane (30 ml) was added to precipitate the
title compound. After a few days, dark orange crystals
were collected (0.89 g, 51% yield). Triphenylphosphine,
a byproduct of the reaction, is soluble under these
conditions, as confirmed by separate experiments. Anal.
Found: C, 65.6; H, 6.7; N, 2.7%. C50H58N2O4P2Ru
requires: C, 65.7; H, 6.4; N, 3.1%. IR (Nujol, cm−1):
1588(w), 1574(w), 1505(vs), 1465(s), 1436(s), 1378(s),
3. Conclusions
This paper reports the first homoleptic (i.e. contain-
ing a number of anionic ligands of the same type
corresponding to the oxidation state of the central
metal atom) N,N-dialkylcarbamato derivatives of
ruthenium(II) and a preliminary investigation of their
reactivity. Although the study has been until now lim-
ited to the di-iso-propyl derivative only, it has been
demonstrated for the first time that N,N-dialkylcar-
bamato complexes of ruthenium(II) can become easily
accessible when ruthenium(II) chloride stabilized by
triphenylphosphine coordination is used as starting ma-
terial. As expected, the new complexes are structurally
similar to their carboxylato counterparts already re-
ported in the literature. On the other hand, the reactiv-
ity is largely different and the new carbamato
derivatives have been shown to undergo: (a) addition of
carbon monoxide, (b) hydrolysis to the carbonato
derivative, (c) reduction by the combined action of
carbon monoxide and water. All these reactions occur
under mild conditions, i.e. at room temperature and
atmospheric pressure. This behaviour can be compared
with that of the more robust carboxylato derivatives
[12], which normally require more drastic conditions to
undergo reduction (by dihydrogen) and, of course, are
not attacked by water. The catalytic activity of these
new systems is now under investigation and will be
reported in a forthcoming paper.
1
1366(m), 1352(s), 1314(w). NMR (C6D6, ppm); H: 1.1
(CH3, 24 H), 3.8 (CH, 4 H), 7.0 (m-CH and p-CH, 18
H), 7.6 (o-CH, 12 H); 31P: 65.6; 13C: 21.1 (CH3), 44.2
(CH), 134.8, 137.4 (aromatic carbons), 169.1 (CO2).
4.3. Synthesis of Ru(O2CNiPr2)2(PPh3)2(CO) (2)
An orange solution of Ru(O2CNiPr2)2(PPh3)2 (0.1 g,
0.11 mmol) in 20 ml of toluene turned quickly yellow
under carbon monoxide at atmospheric pressure at r.t.
After 10 min, carbon monoxide uptake slowed down.
The IR spectrum in solution showed one carbonyl band
only at 1936 cm−1. By removing the volatiles within 30
min, the monocarbonyl derivative was recovered in a
substantially quantitative yield. A minor impurity of
the dicarbonyl derivative (vide infra) was detected in

D.B. Dell’Amico et al. / Journal of Organometallic Chemistry 596 (2000) 144–151
149
the Nujol IR spectrum as evidenced by two bands of
4.6. Hydrolysis of 3 under carbon monoxide
low intensity at 2046 and 1984 cm−1, accompanying
the intense band of the main product. NMR (C6D6,
ppm): 31P: 35.0; 13C: 21.5 (CH3), 21.8 (CH3), 44.2 (CH),
45.2 (CH), 128.6, 130.0, 132.4, 135.5 (aromatic car-
bons), 162.9 (CO2), 208.5 (CO). The compound can be
directly recovered by carrying out the carbonylation in
a 1:3 toluene–heptane mixture, the monocarbonyl
derivative precipitating out from solution, while the
dicarbonyl remained in solution. The carbonylation
reaction was monitored gas volumetrically: about one
equivalent of carbon monoxide was absorbed in toluene
solution in 10 min. Compound 1 absorbs CO even in
the solid state, the uptake of one equivalent of CO
being complete in 2 days.
To
a solution in toluene (20 ml) of Ru(O2-
CNiPr2)2(PPh3)2(CO)2 (0.33 g, 0.34 mmol) under carbon
monoxide at atmospheric pressure, water (0.02 ml, 1.11
mmol) was added. A slow reaction occurred in about 3
days. A 31P-NMR spectrum of the solution showed
a
major peak at 56.0 ppm due to Ru(PPh3)2-
(CO)3, while a minor peak due to Ru(O2CNiPr2)2-
(PPh3)2(CO)2 was still present at 28.9 ppm, together
with unidentified products with peaks of low intensity
at 47.1 and 24.3 ppm and free PPh3 at −5.1 ppm. The
solution showed a strong broad IR band at 1900 cm−1
due to Ru(PPh3)2(CO)3. The ruthenium(0) tricarbonyl
complex was precipitated by adding heptane to a con-
centrated toluene solution, collected by filtration and
dried in vacuo (0.11 g, 46% yield). It was characterized
analytically (C, H) and spectroscopically [32].
4.4. Synthesis of Ru(O2CNiPr2)2(PPh3)2(CO)2 (3)
An orange solution of Ru(O2CNiPr2)2(PPh3)2 (0.86 g,
0.94 mmol) in 20 ml of toluene turned quickly yellow
under carbon monoxide at atmospheric pressure. After
3 days, two CO bands in the IR spectrum of the
solution were present at 2046 and 1984 cm−1. By
removing the volatiles, a sufficiently pure product was
recovered in good yields (79%). Anal. Found: C, 64.9;
H, 6.4; N, 2.3%. C52H58N2O6P2Ru requires: C, 64.4; H,
6.0; N, 2.9%. IR (Nujol, cm−1): 2050(s), 1988(s),
1958(m), 1904(w), 1594(s), 1570(s), 1529(w), 1485(s),
1434(s), 1425(s), 1370(s), 1337(s). NMR (C6D6, ppm):
1H: 0.8 (CH3, d, 12 H), 1.3 (CH3, d, 12 H), 3.3 (CH,
sept, 2 H), 4.5 (CH, sept, 2 H), 7.1 (m-CH and p-CH,
m, 18 H), 8.1 (o-CH, m, 12 H); 31P: 28.9; 13C: 21.3
(CH3), 21.9 (CH3), 44.2 (CH), 46.7 (CH), 129.9, 132.7,
134.5 (aromatic carbons), 160.5 (CO2), 196.7 (CO). A
sample of Ru(O2CNiPr2)2(PPh3)2(CO)2 in C6D6 was
sealed under carbon monoxide in an NMR tube: no
modification of the 31P-NMR signals was observed in 3
weeks.
4.7. Attempted oxidati6e addition to Ru(PPh3)2(CO)3
A solution of Ru(PPh3)2(CO)3 (0.6 g, 0.85 mmol) in
20 ml of toluene was treated with diisopropylamine (15
ml) and introduced in a glass autoclave loaded with 5
atm pressure of carbon dioxide. After 2 h at r.t., the
suspension was heated at 60°C for 10 h: an IR spec-
trum of the solution showed only the band at 1900
cm−1 due [30] to the starting metal complex.
4.8. X-ray crystallography
All X-ray diffraction measurements were carried out
at r.t. (T=293 K) by means of a Siemens P4 diffrac-
tometer equipped with graphite-monochromated Mo–
,
Kh radiation (u=0.71073 A). The samples were sealed
in glass capillaries under dinitrogen. The intensity data
collection was carried out with an ꢀ/2q scan mode. The
intensities of 1 and 3 were corrected for absorption by
means of a „-scan method; for 4, an integration
method based on crystal shape was used. Data reduc-
tion was carried out by means of the SHELXTL package
[35] and structure solutions and refinements, based on
full-matrix least-squares on F2, were done by means of
the SHELX97 programme [36]. The structure of 3 was
solved by the direct methods of the SIR92 programme
[37].
4.5. Synthesis of Ru(O3C)(PPh3)2(CO)2·H2O (4)
By operating under a dinitrogen atmosphere, a solu-
tion of Ru(O2CNiPr2)2(PPh3)2(CO)2 (0.26 g, 0.27 mmol)
in toluene (20 ml) was treated with water (0.02 ml, 1.11
mmol). After a few hours, a colourless solid started to
precipitate out. After 2 days, the carbonato complex
was filtered and dried in vacuo (0.12 g, 59% yield).
Anal. Found: C, 61.9; H, 3.6%. C39H32O6P2Ru requires:
C, 61.7; H, 4.2%. IR (Nujol, cm−1): 3376(wOH), 2046(s),
1982(s), 1651(s), 1626(s), 1481(m), 1435(s), 1311(w).
NMR (MeOH, ppm): 31P: 28.0. The hydrolysis was
monitored by NMR in a tube sealed under dinitrogen:
1H peaks due to di-iso-propylamine were found to
progressively grow.
Dark orange prismatic crystals of 1, obtained by
layering heptane on a toluene solution, were found to
have the lattice parameters listed in Table 4. The cell
parameters were calculated from the setting angles of
37 reflections having 5.2°BqB11.7°. The structure
was solved by direct methods and completed by stan-
dard Fourier methods. The hydrogen atoms were intro-
duced in calculated positions and were let to ride on the
connected carbon atoms. The final refinement cycle
gave the reliability factors listed in Table 4.

150
D.B. Dell’Amico et al. / Journal of Organometallic Chemistry 596 (2000) 144–151
Table 4
Crystal data and structure refinement
Compound
Ru(O2CNiPr2)2(PPh3)2 (1)
Ru(O2CNiPr2)2(PPh3)2(CO)2 (3) Ru(O3C)(PPh3)2(CO)2·H2O (4)
Empirical formula
Formula weight
Crystal system
Space group
C50H58N2O4P2Ru
913.99
Monoclinic
P21/n (No. 14)
13.241(3)
26.127(7)
13.594(3)
90.05(1)
4702.8(19)
C52H58N2O6P2Ru
970.01
Monoclinic
P21/n (No. 14)
11.419(1)
20.796(2)
21.627(3)
99.71(1)
5062.2(10)
C39H32O6P2Ru
759.66
Orthorhombic
Pbcn (No. 60)
19.218(2)
10.919(2)
15.814(1)
–
3318.4(7)
4
1.521
0.618
,
a (A)
,
b (A)
,
c (A)
i (°)
3
,
Volume (A )
Z
4
4
Dcalc (Mg m−3
)
1.291
0.446
1912
0.60×0.28×0.20
2.15–22.51
−145h51, −15k528,
−145l514
7483
1.273
0.421
2024
0.44×0.32×0.10
2.06–21.25
−115h51, −15k521,
−215l522
7132
Absorption coefficient (mm−1
F(000)
)
1552
Crystal size (mm3)
0.29×0.27×0.18
2.12–25.00
−225h522, −125k51,
−15l518
6850
q range for data collection (°)
Index ranges
Reflections collected
Independent reflections
Completeness to q=22.51°
Data/restraints/parameters
Goodness–of-fit a on F2
Final R indices a [I\2|(I)]
R indices a (all data)
A; B (w) a
6162 [Rint=0.0417]
99.9%
6162/0/532
1.025
R1=0.0477, wR2=0.0938
R1=0.0917, wR2=0.1155
0.0350; 8.46
0.439 and −0.533
5610 [Rint=0.0526]
99.7%
5610/0/568
1.000
R1=0.0562, wR2=0.0831
R1=0.1268, wR2=0.1025
0.0263; 0.00
0.402 and −0.317
2920 [Rint=0.0270]
100.0%
2920/0/220
1.033
R1=0.0301, wR2=0.0681
R1=0.0452, wR2=0.0741
0.0386; 0.04
0.319 and −0.478
Largest difference peak and hole
−3
,
(e A
)
a Goodness-of-fit=[ꢀ[w(Fo2−Fc2)2]/(N−P)]1/2, where N, P are the numbers of observations and parameters, respectively. R1=ꢀꢁꢁFoꢁ−ꢁFcꢁꢁ/
ꢀꢁFoꢁ; wR2=[ꢀ[w(F2o−Fc2)2]/ꢀ[w(Fo2)2]]1/2; w=1/[|2(F2o)+(AQ)2+BQ] where Q=[max(Fo2,0)+2F2c]/3.
5. Supplementary material
Colourless tabular crystals of 3, obtained by slow
evaporation of a heptane solution, were found to
have the lattice parameters listed in Table 4. The cell
parameters were calculated from the setting angles of
36 reflections having 5.2BqB11.1°. The struc-
ture was solved by direct methods. The hydro-
gen atoms were partly localized in the difference
Fourier map and partly introduced in calculated posi-
tions. The final refinement cycle, performed with an-
isotropic thermal factors for all carbon and oxygen
atoms, produced the reliability factors listed in Table
4.
Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 133939 for compound 1,
133940 for compound 3, and 133941 for compound 4.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge, CB2 1EZ, UK (fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or http://www.ccdc.
cam.ac.uk).
Prismatic crystals of 4, obtained by slowly hy-
drolysing the precursor 3 in toluene solution, were
found to have the lattice parameters listed in Table 4.
The cell parameters were calculated from the setting
angles of 27 reflections having 2.1BqB11.3°. The
structure was solved by direct methods and refined by
full-matrix least-squares methods after introducing the
hydrogen atoms in calculated positions. The final reli-
ability factors are listed in Table 4.
Acknowledgements
The authors wish to thank the Ministero dell’ Univer-
sita` e della Ricerca Scientifica e Tecnologica (MURST),
Progetto di Rilevante Interesse Nazionale, 1998-9, and
the Consiglio Nazionale delle Ricerche (C.N.R., Roma)
for financial support. A loan of ruthenium chloride by
Chimet S.p.A., Badia al Pino, Arezzo, Italy, is gratefully
acknowledged.

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