Synthesis and structure of new phosphine-substituted homo- and hetero-bimetallic carbonyl clusters of iron, ruthenium and nickel. Characterization of two inorganic-organometallic hybrid materials based on mesoporous SBA-15 silica

Article abstract of DOI:10.1016/j.ica.2010.03.001

The reactions of the complexes Fe₃(CO)₁₂, H₂FeRu₃(CO)₁₃, H₂Ru₄(CO)₁₃ and CpNiRu₃(H)₃(CO)₉ with 2(diphenylphosphino)ethyl-triethoxysilane give considerable yields of the complexes Fe₃(CO)₁₀L₂ (1), H₂FeRu₃(CO)₁₀L₂ (2), Ru₄(CO)₁₀L₃ (3) and CpNiRu₃(H)₃(CO)₇L₂ (4) where L = Ph₂PCH₂CH₂Si(OEt)₃. The complexes (1-3) have been characterized by analytical and spectroscopic techniques. The structure of (4) has been determined by X-ray analysis. The presence of a phosphine containing the -Si(OEt)₃ group has been exploited for grafting complexes (3) and (4) on the mesoporous SBA-15 and the resulting inorganic-organometallic materials have been characterized by means of ICP-MS, FT-IR, DR-UV-vis spectroscopy, XRD and textural analysis.

Full text of DOI:10.1016/j.ica.2010.03.001

Inorganica Chimica Acta 363 (2010) 1773–1778
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Synthesis and structure of new phosphine-substituted homo- and hetero-bimetallic
carbonyl clusters of iron, ruthenium and nickel. Characterization of two inorganic–
organometallic hybrid materials based on mesoporous SBA-15 silica
a
Fabio Carniato a, Giorgio Gatti a, Giuliana Gervasio b, Domenica Marabello b, Enrico Sappa a, , Andrea Secco
*
a Dipartimento di Scienze e Tecnologie Avanzate, Centro Interdisciplinare NanoSistemi, Università del Piemonte Orientale, Viale Teresa Michel 11, 15121 Alessandria, Italy
b Dipartimento di Chimica IFM, Università di Torino, Centro Interdipartimentale di Cristallografia Diffrattometrica (CrisDi), Via Pietro Giuria 7, 10125 Torino, Italy
a r t i c l e i n f o
a b s t r a c t
Article history:
The reactions of the complexes Fe3(CO)12, H2FeRu3(CO)13, H2Ru4(CO)13 and CpNiRu3(H)3(CO)9 with
2(diphenylphosphino)ethyl-triethoxysilane give considerable yields of the complexes Fe3(CO)10L2 (1),
H2FeRu3(CO)10L2 (2), Ru4(CO)10L3 (3) and CpNiRu3(H)3(CO)7L2 (4) where L = Ph2PCH2CH2Si(OEt)3. The
complexes (1–3) have been characterized by analytical and spectroscopic techniques. The structure of
(4) has been determined by X-ray analysis. The presence of a phosphine containing the –Si(OEt)3 group
has been exploited for grafting complexes (3) and (4) on the mesoporous SBA-15 and the resulting inor-
ganic–organometallic materials have been characterized by means of ICP-MS, FT-IR, DR-UV–vis spectros-
copy, XRD and textural analysis.
Received 3 February 2010
Received in revised form 27 February 2010
Accepted 1 March 2010
Available online 6 March 2010
Keywords:
Iron, ruthenium and nickel carbonyl clusters
Functionalized phosphine
Inorganic–organometallic systems
X-ray structure determination
SBA-15
Ó 2010 Elsevier B.V. All rights reserved.
1. Introduction
C) and of CpNiRu3H3(CO)9 (complex D) with dpts have been exam-
ined. Earlier studies showed that H2FeRu3(CO)13 [7] and the phos-
Attempts at introducing organometallic complexes into silica-
based sol–gel materials have been reported [1]. In particular, metal
carbonyls can be grafted on inorganic materials through function-
alized alkynes. For example, Ru3(CO)12 has been reacted with 2-
pentynal-diethyl-acetal [2] or with alkoxy-silyl functionalized al-
kynes and the resulting products have been grafted to amorphous
silica materials obtained from tetraethoxysilane (teos) [3]. In some
instances, however, the alkoxysilyl-alkynes undergo partial retro-
synthesis [4,5] and products different from those expected are ob-
tained in low yields. In addition, some of these products are
unsuitable for grafting on silica.
Another approach consists in reacting the metal carbonyls with
phosphines bearing substituents which can react with silica-based
materials. For example, Ru3(CO)12 has been reacted with 2(diphen-
ylphosphino)ethyl-triethoxysilane [Ph2PCH2CH2Si(OEt)3, dpts] and
the disubstituted complex Ru3(CO)10L2 (L = dpts), obtained in good
yields has been successfully supported onto the mesoporous SBA-
15 and MCM-41 materials [6].
phine-substituted derivatives of CpNiRu3H3(CO)9 [8] are active in
homogeneous hydrogenation catalysis. Complex D supported onto
alumina is also active in ammonia synthesis [9]. The structures of
the complexes are shown in Scheme 1.
The complexes Fe3(CO)10L2 (1), H2FeRu3(CO)10L2 (2), Ru4(CO)10
-
L3 (3) and CpNiRu3(H)3(CO)7L2 (4) [L = Ph2PCH2CH2Si(OEt)3] have
been obtained in medium or high yields and have been character-
ized by elemental analysis and by IR, NMR spectroscopies, EDS and
mass spectrometry and by single crystal X-ray diffraction (complex
4).
The complexes (3) and (4) were chemically anchored on a mes-
oporous silica (SBA-15) and the final hybrid materials (namely
mat-S-3 and mat-S-4) were characterized in detail by inductively
coupled plasma-mass spectrometry (ICP-MS), infrared spectros-
copy under vacuum conditions, DR-UV–vis spectroscopy, X-ray
diffraction (XRD) and textural analysis. The larger pores size of
SBA-15 silica, in contrast to the smaller ones of zeolite or other por-
ous supports (e.g. MCM-41), offers the possibility to create isolated
and catalytically active sites at the inner walls of the mesopores. In
addition, the heterometallic nature of complex (4), could confer to
the final hybrid material interesting catalytic properties which can
differ sharply from those of solid solutions of the bulk metals,
according to the literature [10].
Following this synthetic approach, the reactions of Fe3(CO)12
(complex A), H2FeRu3(CO)13 (complex B), H2Ru4(CO)13 (complex
* Corresponding author. Tel.: +39 0131 360217; fax: +39 0131 360250.
E-mail address: enrico.sappa@mfn.unipmn.it (E. Sappa).
0020-1693/$ - see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2010.03.001

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F. Carniato et al. / Inorganica Chimica Acta 363 (2010) 1773–1778
Scheme 1. Schematic view of the reactions which occur from the complexes Fe3(CO)12 (complex A), H2FeRu3(CO)13 (complex B), H2Ru4(CO)13 (complex C) and
CpNiRu3H3(CO)9 (complex D) and 2(diphenylphosphino)ethyl-triethoxysilane (dpts) to obtain the products (1–4).
plasma mass spectrometry (ICP-MS) under the following condi-
tions: alkaline fusion of the materials with LiBO3 at 1100 °C for
30 min. Dissolution in ultrapure water containing about 2% of
HNO3 followed by ICP-MS analysis.
2. Experimental
2.1. General experimental details. Materials and analysis of the
organometallic compounds
The FT-IR spectra were obtained with a resolution of 4 cmꢀ1 on
a Bruker Equinox 55 (KBr cells, path length 0.5 mm) with pyroelec-
tric DTGS detector (data elaboration through Opus 5.0 software)
and ATI-Mattson (data elaboration software WinFIRST). The IR
spectra of the materials were recorded under vacuum: the samples
were pressed in the form of self-supporting wafers and placed into
a IR cell equipped with KBr windows, permanently attached to a
high vacuum line (residual pressure 1.0 ꢁ 10ꢀ4 mbar).
Fe3(CO)12 (complex A) was obtained from Strem Chemicals and
used as received. The clusters H2FeRu3(CO)13 (complex B),
H2Ru4(CO)13 (complex C) [7] and CpNiRu3H3(CO)9 (complex D)
[8] have been obtained following literature methods. The phosphi-
nic ligand was purchased from ABCR Gelest (Karlsruhe) and was
used as received. Solvents (e.g. heptane, toluene, diethyl ether)
were laboratory grade (Carlo Erba) and were dehydrated, when
possible, over sodium. The reactions leading to the organometallic
products were performed under dry nitrogen in conventional three
necked flasks equipped with gas inlet, mercury check valve and
magnetic stirring. The reaction mixtures were filtered under N2,
brought to small volume under reduced pressure and separated
on preparative t.l.c. plates (Merck Kieselgel P.F.: eluents mixtures
of light petroleum (b.p. 40–70 °C) and diethyl ether in variable v/
v ratio). The products were extracted from the t.l.c. silica with
diethyl ether. The yields of the reactions are given on the metal
carbonyl consumed and the reaction times indicate the time re-
quired to obtain reflux, followed by the time of reflux: thus
‘‘7 + 6 min” indicated 7 min to reflux and 6 min of reflux.
The XRD analyses were performed on a Thermo ARL X’TRA 48
instrument using the Cu Ka radiation (k = 1.54062 Å).
N2 physisorption measurements were carried out at 77 K in the
relative pressure range from 1 ꢁ 10ꢀ6 to 1 P/P0 by using a Quanta-
chrome Autosorb1MP/TCD instrument. Prior to the analysis, the
samples were outgassed at 80 °C for 3 h (residual pressure lower
than 10ꢀ6 mbar). Upon this treatment, only water is removed from
the samples. Apparent surface areas were determined by using BET
equation, in the relative pressure range from 0.01 to 0.1 P/P0. Pore
size distributions were obtained by applying the NLDFT method
(N2 silica kernel based on a cylindrical pore model applied to the
desorption branch).
Diffuse reflectance UV–vis (DR-UV–vis) spectra of the hybrid
materials were recorded using a Perkin Elmer Lambda 900 spec-
trometer equipped with an integrating sphere accessory. Prior
the analysis, the samples were dispersed in anhydrous BaSO4
(10 wt.%).
Elemental analyses were performed by ITECON s.r.l. (Nizza
Monferrato, Piemonte, Italy). The infrared spectra were obtained
on a Bruker Vector 22 (KBr cells, path length 0.5 mm). The 1H,
13C and 31P NMR spectra were obtained on a JEOL Eclipse 400.
The C.I. mass spectra were collected on a Finnigan-Mat TSQ-700
mass spectrometer (Servizio di spettrometria di massa, Diparti-
mento di Scienza e Tecnologia del Farmaco, Università di Torino).
Energy Dispersive X-ray Spectroscopy (EDS), coupled to a Scanning
Electron Microscope (LEO 1450 VP instrument) was used to pro-
vide rapid semi-quantitative elemental analyses of the samples.
2.3. Synthesis of the dpts-substituted complexes
Reaction of Fe3(CO)12 (complex A) with dpts: About 3 g (ca.
6.0 mmol) of the iron carbonyl reacted with 1.5 cm3 (ca. 3.5 mmol)
of dpts in heptane, under N2. After reflux (7 + 12 min) the t.l.c. of
the dark green solution showed the presence of unreacted
Fe3(CO)12 (20%), a yellow complex (tr, not collected) and a dark
green complex (50%, complex (1)).
2.2. Characterization of the silica-based materials
The chemical composition of the materials obtained from SBA-
15 (mat-S-3 and mat-S-4) was determined by inductively coupled

F. Carniato et al. / Inorganica Chimica Acta 363 (2010) 1773–1778
1775
Table 1
Complex (1): C% 50.3 (50.25), H% 4.20 (4.19), Fe% 14.1 (14.07), P%
Crystal data and refinement parameters for the complex (4).
5.40 (5.36) [calculated values in parentheses]; m.w. = 1262. IR:
2084 m, 2047 s, 2032 s, 2010 s, 1978 s, 1994 vs, 1938 vs(sh)
Empirical formula
Formula weight
C52H65NiO13P2Ru3Si2
1378.08
cmꢀ1
.
1H NMR: 7.55–7.48 m (b) [20H, Ph], 3.79 m(b) [4H, PꢀCH2],
Temperature (K)
293(2) K
2.52 s(b), 2.41 s(b), 2.27 s(b) [4H, CH2–Si], 1.20 s(b) [18H, CH3 (Et)],
0.80 s(b) [6H, CH2 (Et)]. 13C NMR: 4.70 d [m], 18.30 s [vs], 23.96 d
[w], 26.0 d [m], 58.74 s [vi] (CH3,CH2) 128.8 d [i], 130.77 s [i],
132.17 d [i], 132.27 d [m] (Ph), 212.0 s [w], 213.5 d [ms], 218.33
s [m] (CO). 31P NMR: 71.49 d (v.i.), 52.76 d (i). CI-MS: 630 m/z
(weak) doubly charged ion, 545 m/z very intense.
Reaction of H2FeRu3(CO)13 (complex B) with dpts: About 1.0 g (ca.
1.5 mmol) of the complex was dissolved in heptane together with
1.0 cm3 (ca. 2.5 mmol) of dpts. After reflux (7 + 8 min), t.l.c. showed
the presence of a yellow band (trace amount, not investigated) and
of about 80% of a orange–red band (complex (2)) and some
decomposition.
Wavelength (Å)
0.71073 Å
Crystal system, space group
Unit cell dimensions
Monoclinic, C2/c
a = 37.1706(11) Å
b = 12.0820(3) Å
c = 28.1126(9) Å
b = 102.262(3)°
0
Volume
12 337.2(6) ÅA3
8,1.484 g cmꢀ3
1.167 mmꢀ1
5592
Z, Calculated density
Absorption coefficient
F(0 0 0)
Theta range for data collection
Limiting indices
Reflections collected/unique
Completeness to theta = 33.44
Refinement method
2.94–30.83°
ꢀ53 6 h 6 49, ꢀ17 6 k 6 15, ꢀ39 6 l 6 17
63 340/17 698 [R(int) = 0.18]
91.2%
Complex (2): C% 45.2 (45.23), H% 3.90 (3.88), Fe% 4.3 (4.26), Ru%
15.2 (15.10), P% 4.9 (4.87). The EDS analysis indicated the presence
of iron, ruthenium, phosphorus and silicon in the atomic ratio
1:3:2:2. I.R.: 2072 w, 2055 w, 2041 m, 2020 vs, 1992 s, 1974 m,
Full-matrix least-squares on F2
17 698/2/415
Data/restraints/parameters
Goodness-of-fit on F2
0.798
Final R indices [I > 2
r
(I)]
R1 = 0.0640, wR2 = 0.1079
R indices (all data)
Largest diff. peak and hole
R1 = 0.3497, wR2 = 0.1480
0.552 and ꢀ0.711 e ÅAꢀ3
1784 m–s, cmꢀ1
2.83 s, 2.56 s, 2.22 s [4H, CH2–Si], 1.61 s [18H, CH3], 0.43 s [12H,
CH2, OEt], ꢀ17.55 [2H, hydrides]. 31P NMR: 38.40, 33.49. CI-MS:
decomposition.
.
1H NMR: 7.34 s [20H, Ph], 3.72 s [4H, CH2ꢀP],
0
Reaction of H2Ru4(CO)13 (complex C) with dpts: About 0.7 g (ca.
1.0 mmol) of the ruthenium complex reacted with 1.0 cm3 of dpts
in heptane, under N2. After reflux (9 + 12 min) a purple solution
was obtained, together with a considerable amount of black resid-
ual (presumably metal powder). t.l.c. showed the presence of a yel-
low (tr, not collected), a pale red (tr, not collected) and a purple
band (80%, complex (3)).
2.5. Synthesis of the silica-based inorganic organometallic materials
(mat-S-3 and mat-S-4)
Preparation of SBA-15 [13]: Pluronic P123 (4.0 g, Sigma–Aldrich)
was dissolved in water (30 g) and HCl (2 N, 120 g) under stirring at
308 K. Tetraethoxysilane (8.5 g, Sigma–Aldrich) was added to the
solution and stirred at 308 K for 24 h. The mixture was aged at
373 K in autoclave for 24 h. The solid product was filtered and
washed several times with water. Calcination was carried out
increasing the temperature at 1 K minꢀ1 under air flow from room
temperature to 823 K and heating the material at 823 K for 5 h.
Reaction of complexes (3) and (4) with SBA-15: 0.11 g of SBA-15
were introduced into a three-necked flask connected to a vacuum
pump and heated at 473 K for 4 h in order to remove the water ad-
sorbed on the surface. After cooling, 0.030 g of complexes (3) and
(4) were dissolved in toluene and added to SBA-15. After 20 h of
stirring at room temperature, the suspensions were filtered and a
powder (0.10 g) was collected.
Complex (3): C% 46.3 (46.18), H% 4.80 (4.78), Ru% 22.3 (22.43),
P% 5.3 (5.28), Si% 4.7 (4.62). The EDS analysis showed the presence
of ruthenium, phosphorus and silicon in the atomic ratio of 4:3:3.
I.R: 2050 m–w, 2003 s(sh), 1975 vs(b), 1947 s(sh), 1889 m, 1881 m,
cmꢀ1 1H NMR: 7.83–7.35 m [30H, Ph], 3.74–3.72 m [24H, CH2
.
(OEt)], 3.08 m, 2.75 m, 2.06 m, 2.20 m [12H, CH2P/Si], 1.18 m
[27H, CH3], no hydrides. 31P NMR: 64.69, 35.42, 30.19. 29Si:
ꢀ46.09, ꢀ46.49, ꢀ46.84. CI-MS: decomposition.
Reaction of CpNiRu3H3(CO)9 (complex D) with dpts: About 1.5 g
(ca. 2.0 mmol) of the complex was dissolved in heptane and dpts
(1.5 cm3, ca. 3.5 mmol) was added to the solution. After reflux (7
+ 10 min), t.l.c. showed the presence of the reactant (about 10%),
a dark green band (60%, complex (4)) and a red residual (not
investigated).
3. Results and discussion
Complex (4): C% 45.4 (45.38), H% 4.24 (4.22), Ni% 4.3 (4.29), Ru%
22.3 (22.25), P% 4.7 (4.65); m.w. = 1375. I.R.: 2053 s, 2014 vs(sh),
The reactions of complexes (A–D) with dpts lead to medium–
high yields of the phosphine-substituted products, and in particu-
lar to the di-substituted complexes (1), (2) and (4). This is in accord
with that previously observed in the reaction of Ru3(CO)12 with the
same ligand: the monosubstituted derivative was obtained in
much lower yields than the disubstituted one [6].
2004 vs, 1982 s, 1956 s, 1945 m(sh), cmꢀ1 1H NMR: 7.20 m
.
[20H, Ph], 5.70 s [5H, Cp], 3.60 s [8H, CH2CH2, dpts], 2.30 s [6H.
CH2 (Et)], 1.15 s [9H, CH3, dpts], ꢀ15.40 s [3H, hydrides]. 31P
NMR: 32.08, 30.54. CI-MS: decomposition.
Complexes (1–3) did not give crystals suitable for the X-ray
analysis and were characterized by analytical and spectroscopic
techniques. Elemental and EDS analyses and IR and NMR spectros-
copies were employed to identify the complexes. Unfortunately, in
the CI-MS spectra of complexes (2–4) only decomposition could be
observed. The proposed structures are therefore based on the ana-
lytical and spectroscopic data reported in Section 2. It is however
difficult to decide whether the substitution has occurred on iron
or on ruthenium, although presumably iron would be more prone
to substitution. The proposed structures for complexes (1–3) are
shown in Scheme 1.
2.4. X-ray structure determination of complex (4)
Crystal and refinement data are reported in Table 1. The reflec-
tion data, using a crystal obtained from heptane solution, have
been collected on a Gemini R Ultra diffractometer [11]. The hydride
atoms H(12,13,23) have been found and refined with Uiso, while all
others have been calculated and kept riding with Uiso set at 1.2–1.5
times Ueq of the corresponding C atom. All other atoms have been
refined anisotropically. A very high thermal motion of all atoms
and a disorder of the cyclopentadienyl molecule linked to the Ni
atom has been detected. Programs used were CrysAlisPro [11] for
data collection and correction and SHELXTL [12] for structure solu-
tion, refinement and molecular graphics.
The IR spectrum and the analytical and NMR spectroscopic data
confirmed that the complex (1) is the disubstituted derivative and
that the structure is comparable with the ruthenium homologue

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F. Carniato et al. / Inorganica Chimica Acta 363 (2010) 1773–1778
Table 2
[6]. An example of monosubstituted complex bearing a phosphino-
alkyne substituent is known: this, however, contains bridging COs
not observed in the present case [14].
Complex (2) is a disubstituted derivative still maintaining
bridging hydrides and bridging CO (as observed from NMR and
IR data). It is supposed that one of the dpts ligands is linked to
the iron and the other to a ruthenium atom. As discussed below,
substitution is expected to occur in axial positions for sterical
reasons.
Complex (3) is a tri-substituted derivative which has lost the
hydrides but maintains bridging carbonyls. The shift of the IR sig-
nals to lower wavelengths indicates a heavy substitution. Once
again axial substitution is expected.
0
Selected bond distances (AÅ) and angles (°) for complex (4).
Ru(1)–Ru(2)
Ru(1)–Ru(3)
Ru(2)–Ru(3)
Ru(1)–Ni(1)
Ru(2)–Ni(1)
Ru(3)–Ni(1)
Ru(1)–P(1)
Ru(2)–P(2)
P(1)–Ru(1)–Ni(1)
Ru(2)–Ru(1)–Ru(3)
P(2)–Ru(2)–Ni(1)
Ru(1)–Ru(2)–Ru(3)
Ru(2)–Ru(3)–Ru(1)
2.8752(9)
2.8826(10)
2.8785(9)
2.5651(13)
2.5563(12)
2.5574(13)
2.354(2)
2.356(2)
174.46(7)
59.99(2)
173.84(6)
60.13(2)
59.88(2)
It has been found (with a computer-based research) that a high
number of structures for phosphine-substituted derivatives of
H4Ru4(CO)12 has been reported. Of the 31 complexes bearing
3.2. Synthesis and characterization of the hybrid materials (mat-S-3
and mat-S-4) obtained from complexes (3) and (4) and SBA-15
diphosphines, 28 maintain the four
have lost one up to three hydrides. In addition there are 16 struc-
tures containing -P, -P–O or -P–N bridges where – with only
l-H hydrides and only three
l
l
l
The homo- and hetero-metallic clusters (3) and (4) have been
selected to be anchored on the SBA-15 surface. The presence of li-
gands bearing triethoxysilyl groups allowed to the immobilization
of both complexes on the surface silanols of the SBA-15 support.
The amount of complexes in the final hybrid materials was esti-
mated by ICP-MS. The solid mat-S-3 was characterized by a Ru te-
nor of 33.9 mg/g. The elemental analysis of mat-S-4 showed that
the material contains nickel (6.1 mg/g) and ruthenium (25.3 mg/
g), according to the chemical composition of the complex.
Particular attention was devoted to the investigation of the
structural and textural properties of the mesoporous silica after
reaction with complexes (3) and (4).
one exception-loss of one up to three hydrides is observed. In con-
trast only 23 structures containing monophosphines are known.
Twelve are monosubstitution products (11 maintain 4
disubstituted (all with 4 -H) [15], only one is a trisubstituted
product (with four -H) [16] and five are tetrasubstituted deriva-
tives (four of them with 4 -H). Thus, maintaining the hydrides
l-H), 6 are
l
l
l
during substitution seems to be the prevailing trend. Under this
profile, complex (3) represents an exception, having lost all the
hydrides.
3.1. The X-ray structure of complex (4)
The X-ray diffraction pattern of the SBA-15 support (Fig. 2,
curve a) showed an intense reflection at 0.90° 2h along with two
weak peaks at 1.56° and 1.80° 2h, which can be indexed as the
(1 0 0), (1 1 0) and (2 0 0) planes related to the hexagonal pore ar-
ray of SBA-15 (Fig. 2, curve a) [13]. This pattern was preserved after
anchoring of the complexes, however, a decrease in intensity and a
shift of the reflections at higher 2h were detected for both hybrid
materials (Fig. 2, curves b and c). This was ascribed to the immobi-
lization of the complexes (3) and (4) inside the channels of the
support.
The structure of the complex is shown in Fig. 1 and relevant dis-
tances and angles are in Table 2. The Cp moiety is disordered on the
ring plane and only the prevailing (62%) ring is reported in Fig. 1.
There is a rotation of 49° between the two rings.
The complex is formed by an equilateral triangle of Ru atoms
0
0
(Ru–Ru 2.879(1) ÅA av.) capped by a Ni atom (Ru–Ni 2.560(1) ÅA
0
av.) linked at 1.79(1) ÅA to the centroid of the Cp ring. Three hydro-
gen atoms bridge the Ru–Ru bonds. The Ru(3) atom is linked to
three CO groups, while Ru(1) and Ru(2) are each linked to two
CO groups and to one axial phosphine ligand. The phosphine li-
gands are trans to the nickel atom (Table 2), as expected from pre-
vious work [17].
These results were also confirmed by a textural study which al-
lowed to estimate the specific surface area (SBET (m2/g)) and pore
volume (cm3/g) of the samples.
Fig. 1. ORTEP plot with anisotropic thermal ellipsoids (30% of probability) of
complex (4) CpNiRu3(H)3(CO)7[Ph2PCH2CH2Si(OEt)3]2. Non-hydridic H atoms are
shown for clarity.
Fig. 2. X-ray profiles of SBA-15 (curve a) and of mat-S-3 (curve b) and mat-S-4
(curve c).

F. Carniato et al. / Inorganica Chimica Acta 363 (2010) 1773–1778
1777
Fig. 3. (A) N2 adsorption/desorption isotherms at 77 K of SBA-15 (–d–), mat-S-3 (–
D
–) and mat-S-4 (–s–). Pores size distribution obtained by NLDFT are reported in B); SBA-
15 (–d–), mat-S-3 (–D–) and mat-S-4 (–s–).
Table 3
Textural parameters of mesoporous materials.
SBET (m2/g)
Pores volume (cc/g)
Pores diameter (Å)
SBA-15
mat-S-3
mat-S-4
700
482
604
1.12
0.80
0.94
85
70
73
For pure silica SBA-15 and the hybrid materials, the isotherms
are type IV according to the IUPAC classification and have an H1
hysteresis loop that is representative of mesoporous cylindrical
or rod-like pores (Fig. 3A). The results of the nitrogen isotherms,
the Brunauer–Emmett–Teller surface area (SBET) and the total pore
volume determined by NLDFT approach, for pure silica and func-
tionalized materials are shown in Table 3.
SBA-15 showed a high specific surface area (700 m2/g), a pore
volume of 1.12 cm3/g and a mesopores average diameter of 85 Å.
After reaction with complexes (3) and (4), a decrease of both SBET
(passing from 700 to 482 and 604 m2/g, for mat-S-3 and mat-S-4,
respectively) and pores volume (from 1.12 to 0.80 and 0.94 cc/g, for
mat-S-3 and mat-S-4, respectively) were observed in the final hy-
brid materials. In addition, a contraction of the pores diameter of
mat-S-3 and mat-S-4, passing from 85 (typical of pure SBA-15)
to ca.70–73 Å, for both hybrid solids (Table 3), with a partial lock-
ing of the support mesopores was highlighted in comparison with
the pristine silica SBA-15 (Fig. 3B). This suggested that a significant
amount of the complex molecules is anchored on the internal sur-
face of SBA-15 channels.
Particular attention was also devoted to the investigation of the
surface properties of SBA-15 before and after reaction with both
complexes by using the infrared spectroscopy tool. IR spectrum
of SBA-15, after outgassing in vacuum at room temperature,
(Fig. 4, curve a) showed at higher frequencies three different sig-
nals. The peaks at 3740 and 3700 cmꢀ1 were due to the stretching
of isolated and geminal silanol groups present on the silica surface.
The broad band centred at 3520 cmꢀ1 was assigned to Si–OH in-
volved in hydrogen bonds. After reaction with complexes (3) and
(4) (Fig. 4, curves b and c), the intensity of the isolated and geminal
silanols drastically decreased and the profile of the broad band at
lower wavenumbers was modified.
Fig. 4. IR spectra collected in vacuum at room temperature of SBA-15 (curve a),
mat-S-3 (curve b) and mat-S-4 (curve c).
tion (see Section 2). Only two main bands at 2060 and 1995 cmꢀ1
were found in the spectra of mat-S-3 and mat-S-4, whereas six
absorptions for the complexes were observed in homogeneous
solution.
IR absorptions at 2060–1995 cmꢀ1 have been often found for
Ru3(CO)12 cluster and derivatives adsorbed or anchored on porous
silica [18] and assigned to Ru(II) dicarbonylic species directly
linked to the support surface. The formation of Ru(II) dicarbonylic
moieties suggested that a large amount of the Ru4 or NiRu3 cores of
the complexes was broken upon reaction with the silica matrix.
The identification of these surface species was strongly supported
by numerous studies in literature [18–20] and by UV–vis results
(spectra not shown for sake of brevity).
The UV–vis spectra of the pure clusters in heptane solution
reported a typical band around 600 nm, which have been assigned
0
0
*
r
*
r
to
?
electronic transitions of Ru linked to phosphine groups
[21]. After chemical anchoring of the clusters on SBA-15 surface,
changes are observed in the absorption spectra and colour of the
hybrid materials. The colour of the clusters passed form red to yel-
low/grey after reaction with SBA-15 and the UV–vis spectra of the
final materials no longer showed the absorption around 600 nm.
These results suggested, as indicated by the IR data, that the oxida-
tion of Ru0 metal to RuII occurred in the hybrid materials [19].
These results suggested that a significant fraction of silanols of
SBA-15 were involved in the anchoring reaction with the
complexes.
IR spectrum in the range typical of CO stretching modes (around
2000 cmꢀ1) of complexes (3) and (4) after reaction with the silica
surface was very different than that of the clusters in heptane solu-

1778
F. Carniato et al. / Inorganica Chimica Acta 363 (2010) 1773–1778
[2] G. Gervasio, D. Marabello, E. Sappa, A. Secco, J. Organomet. Chem. 690 (2005)
According to the literature, the presence of these species dis-
3730.
persed on the silica surface may confer interesting catalytic prop-
erties to these materials for specific reactions, such as Fischer–
Tropsch synthesis reactions [19].
[3] A. Arrais, E. Boccaleri, E. Sappa, A. Secco, J. Sol–Gel Sci. Technol. 38 (2006) 283.
[4] G. Gervasio, D. Marabello, E. Sappa, A. Secco, J. Cluster Sci. 18 (2007) 67.
[5] A. Arrais, E. Sappa, A. Secco, J. Cluster Sci. 18 (2007) 535.
[6] F. Carniato, A. Secco, G. Gatti, L. Marchese, E. Sappa, J. Sol–Gel Sci. Technol. 52
(2009) 235.
4. Conclusions
[7] R. Giordano, E. Sappa, J. Organomet. Chem. 448 (1993) 157.
[8] M. Castiglioni, R. Giordano, E. Sappa, J. Mol. Catal. 42 (1987) 307;
M. Castiglioni, R. Giordano, E. Sappa, J. Organomet. Chem. 342 (1988) 97;
M. Castiglioni, R. Giordano, E. Sappa, J. Mol. Catal. 42 (1987) 307.
[9] G. Predieri, P. Moggi, S. Papadopoulos, A. Armigliato, S. Bigi, E. Sappa, J. Chem.
Soc., Chem. Commun. (1990) 1736;
A. Armigliato, S. Bigi, P. Moggi, S. Papadopoulos, G. Predieri, G. Salviati, E.
Sappa, Mater. Chem. Phys. 29 (1991) 251.
[10] D.S. Shephard, T. Aschmeyer, G. Sankar, J.M. Thomas, D. Ozkaya, B.F.G. Johnson,
R. Raja, R.D. Oldroyd, R.G. Bell, Chem. Eur. J. 4 (7) (1998) 1214.
[11] CrysAlis Pro. Oxford Diffraction Ltd. Company, Abingdon, Oxfordshire, England,
2006.
[12] M. Sheldrick, SHELXTL, Version 5.1, Bruker AXS Inc., Madison, 1997; M. Sheldrick,
Acta Crystallogr., A 64 (2008) 112.
[13] D. Zhao, J. Feng, Q. Huo, N. Melosh, G.H. Fredrickson, B.F. Chmelka, G.D. Stucky,
Science 279 (1998) 548.
[14] G. Gervasio, D. Marabello, E. Sappa, A. Secco, J. Cluster Sci. 19 (2008) 63.
[15] E.L. Diz, B. Therrien, G. Süss-Fink, Acta Crystallogr., Sect. E, Rep. Online 59
(2003) m431;
The complexes obtained in this study indicate – once again –
that substitution with functionalized phosphines occurs easily on
a wide variety of clusters giving acceptable yields of products:
these can be easily anchored to silica materials and give access
to many inorganic–organometallic systems active in heteroge-
neous catalysis. Some general trends could be observed: the dpts
ligand usually undergoes ‘‘heavy” substitution, giving generally
bi- or tri-substituted complexes. Upon anchoring on SBA-15 all
the ruthenium derivatives examined in previous [6] and in this
work, undergo formation of Ru(II)(CO)2 species on the supporting
material.
Beside a homo-metallic cluster (3), the new bimetallic complex
(4) containing Ni and Ru was successfully anchored on the meso-
porous silica SBA-15, in order to obtain a potential heterogeneous
catalyst for several catalytic reactions where the activity of both Ni
and Ru centres are required.
R.D. Wilson, M.S. Wu, R.A. Love, R. Bau, Inorg. Chem. 17 (1978) 1271;
K. Sasvari, P. Main, F.H. Cano, M. Martinez-Ripoll, P. Frediani, Acta Crystallogr.,
Sect. B, Struct. Crystallogr. Cryst. Chem. 35 (1979) 87;
W.-Y. Wong, F.-L. Ting, Z. Li, Organometallics 22 (2003) 5100;
S. Aime, M. Botta, R. Gobetto, L. Milone, D. Osella, R. Gellert, E. Rosenberg,
Organometallics 14 (1995) 3693;
V. Moberg, P. Homanen, S. Selva, R. Persson, M. Haukka, T.A. Pakkanen, M.
Monari, E. Nordlander, J. Chem. Soc., Dalton Trans. (2006) 279.
[16] M.I. Bruce, B.K. Nicholson, J.M. Patrick, A.H. White, J. Organomet. Chem. 254
(1983) 361.
[17] G. Predieri, A. Tiripicchio, C. Vignali, E. Sappa, P. Braunstein, J. Chem. Soc.,
Dalton Trans. (1986) 1135;
Supplementary material
CCDC 64295 contains the supplementary crystallographic data
for complex 4. These data can be obtained free of charge from
The Cambridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif.
E. Sappa, G. Predieri, A. Tiripicchio, M. Camellini, J. Organomet. Chem. 297
(1985) 103;
E. Sappa, A. Tiripicchio, unpublished.
[18] K. Dallmann, R. Buffon, J. Mol. Catal. A Chem. 185 (2002) 187.
[19] P. Moggi, G. Predieri, F. Di Silvestri, A. Ferretti, Appl. Catal. A Gen. 182 (1999)
257.
[20] J. Evans, G.S. McNulty, J. Chem. Soc., Dalton Trans. (1984) 1123.
[21] D.R. Tyler, R.A. Levenson, H.B. Gray, J. Am. Chem. Soc. 100 (25) (1978) 7888.
References
[1] R.J.P. Corriu, D. Leclerq, Angew. Chem., Int. Ed. 35 (1996) 1420;
U. Schubert, J. Chem. Soc., Dalton Trans. (1996) 3343;
A. Choualeb, P. Braunstein, J. Rosè, R. Welter, Inorg. Chem. 43 (2004) 57.