The synthesis and structural characterisation of [Ru(eta-Cp)(dppf)SnBr3].

Article abstract of DOI:10.1016/j.saa.2003.12.012

The reaction of [Ru(eta-Cp)(dppf)N(3)] (1) with equimolar amount of SnBr(2) yielded an interesting heterotrimetallic compound [Ru(eta-Cp)(dppf)SnBr(3)] (2) (dppf: 1,1'-bis-diphenylphosphinoferrocene). Compounds 1 and 2 were characterised by IR, NMR (1H, 13C, 31P and 119Sn), and 2, additionally, by 57Fe and 119Sn Moessbauer spectroscopy and X-ray crystallography. The latter results were as follows: monoclinic, C2/c, a = 32.8879(4)A, b = 11.9888(2)A, c = 20.8986(3)A, beta = 92.545(1)degrees, V = 8231.9(2)A(3), Z =8.

Full text of DOI:10.1016/j.saa.2003.12.012

Spectrochimica Acta Part A 60 (2004) 2383–2386
The synthesis and structural characterisation of [Ru(␩-Cp)(dppf)SnBr3]
L.A. Paima, E.M. Mourab, H.G.L. Siebalda,∗, G.M. de Limaa,∗, A.C. Doriguettoc, J. Ellenac
a
Laboratório de Qu´ımica de Coordenação e Organometálica do Estanho, Departamento de Qu´ımica, Universidade Federal de Minas Gerais, Avenida
Antonio Carlos 6627, CEP 31270-901 Belo Horizonte, MG, Brazil
Departamento de Qu´ımica, Universidade Federal do Piau´ı, CEP 64049-550 Teresina, PI, Brazil
Grupo de Cristalografia, FFI, IFSC, USP, CP 369, CEP 13560-970 São Carlos, SP, Brazil
b
c
Received 27 October 2003; accepted 9 December 2003
Abstract
The reaction of [Ru(␩-Cp)(dppf)N3] (1) with equimolar amount of SnBr2 yielded an interesting heterotrimetallic compound [Ru(␩-
Cp)(dppf)SnBr3] (2) (dppf: 1,1’-bis-diphenylphosphinoferrocene). Compounds 1 and 2 were characterised by IR, NMR (1H, 13C, 31P and
119Sn), and 2, additionally, by 57Fe and 119Sn Mössbauer spectroscopy and X-ray crystallography. The latter results were as follows: monoclinic,
C2/c, a = 32.8879(4) Å, b = 11.9888(2) Å, c = 20.8986(3) Å, β = 92.545(1)◦, V = 8231.9(2) Å3, Z = 8.
© 2003 Elsevier B.V. All rights reserved.
Keywords: Crystal structure; Stannyl; Heterotrimetallic; Diphenylphosphinoferrocene
1. Introduction
gations depend upon the preparation of well-characterised
compounds. In here we report the synthesis and charac-
terisation of a heterotrimetallic Ru–Sn based derivative,
[Ru(␩-Cp)(dppf)SnBr3].
Some of us have been investigating the ability of the frag-
ment [Ru(␩5-Cp)(PPh3)2Cl] to form other Ru-containing
compounds. A new series of organoruthenium derivatives
either employing ligands such as phosphines, by exploring
the wide range of co-ordination mode of Ru [1] or through
promoting the insertion of SnX2 in the Ru–X bond in order
to obtain heterometallic species [2].
2. Experimental
2.1. Material and procedures
In addition, our research has contributed to the study
of the selectivity of Ru(II)/Sn(II) catalysts [3], revealing
that Ru–Sn based species exhibit an interesting catalyst
behaviour towards the preparation of methyl acetate from
methanol [4].
It is also our interest the preparation of nano-structurally
materials, such as Ru–Sn oxides or alloys by thermal decom-
position of organometallic single source precursors such as
[Ru(␩5-Cp)(PPh3)2Cl]. Several approaches are encountered
in the literature, among them the chemical vapour deposi-
tion and pyrolysis of well characterised starting materials.
The latter has been employed by us over the last 2 years,
rendering nano-materials in good yield [5]. Such investi-
Experimental work was carried out in an atmosphere
of dry nitrogen. All manipulations were conducted using
Schlenk techniques, employing a vacuum/nitrogen line or
using a glove box under an atmosphere of nitrogen. Sol-
vents were distilled from Na suspension and kept in Schlenk
flasks with K or Na mirror or else dry molecular sieves.
1
NMR spectra were recorded at 400 MHz, H; 100.62 MHz,
1
1
1
13C{ H}; 50.29 MHz, 31P{ H} and 148.97 MHz, 119Sn{ H}
using a Bruker DPX-400 spectrometer equipped with an
89 mm wide-bore magnet. 13C shifts are reported rela-
tive to SiMe4 and 119Sn shifts relative to SnMe4. 119Sn
and 57Fe Mössbauer spectra were collected with samples
kept at 77 K using sources of CaSnO3 and 57Co, respec-
tively, kept at room temperature. All spectra were fitted
by means of Lorentzian line shapes. The infrared spectra
were recorded with samples pressed as CsI pellets on a
Perkin-Elmer 283B spectrometer in the 4.000–200 cm−1
∗
Corresponding authors. Tel.: +55-313-4995744;
fax: +55-313-4995720.
E-mail addresses: gmlima@dedalus.lcc.ufmg.br,
hsiebald@dedalus.lcc.ufmg.br (H.G.L. Siebald).
1386-1425/$ – see front matter © 2003 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2003.12.012

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L.A. Paim et al. / Spectrochimica Acta Part A 60 (2004) 2383–2386
range. Carbon, hydrogen and nitrogen analyses were per-
formed on a Perkin-Elmer PE-2400 CHN-analyses using
tin sample-tubes. Bromine analyses were performed by
means of X-ray fluorescence in Rigaku–Geigerflex spec-
trophotometer with samples pressed as borax plates. Tin
analysis was carried out using a Hitachi Z-8200 atomic
absorption spectrophotometer (Sn lamp, λmax = 224.6 nm,
N2O/acetylene flame).
2.1.2. Synthesis of [Ru(η-C5H5)(dppf)2N3]
To a Schlenk flask containing [Ru(␩-C5H5)(dppf)Cl]
(0.55 g, 0.69 mmol), in an atmosphere of dry N2, dis-
solved in 100 ml of ethanol, was added at once NaN3
(0.05 g, 0.75 mmol). The resultant mixture was stirred and
refluxed for 6 h. Thus, the solvent was partially removed
under vacuum to 40 ml and an orange precipitate was ob-
tained. After filtration the solid was washed with n-hexane
and re-crystallised in a mixture of dichloromethane and
n-hexane. Yield 85%. 1H NMR (CDCl3, 400.13 MHz),
7.4–6.7 (m, C6H5), δ 5.2–4.1 (m, C5H4Fe), δ 4.0 (s,
2.1.1. X-ray structure determination of 2
Intensity data were collected at 120(2) K on an
Enraf-Nonius Kappa CCD diffractometer with Mo K␣ radi-
ation for a single crystal of 0.01 mm ×0.08 mm ×0.13 mm.
The structures were solved using SHELXS-97 software
[6] and the refinements were carried out on F2 using
SHELXL-97 software [7]. Further details are given in
Table 1. Tables of atom positions and thermal parame-
ters have been deposited at CCDC. The water molecule
was found to be disordered over three positions and
from refinement these were found to have site occupan-
cies 0.333:0.333:0.333. All non-H atoms were refined
anisotropic. The carbons’ H atoms were positioned stere-
ochemically and were refined with fixed individual dis-
placement parameters (Uiso (H) = 1.2 Ueq. (C)) using
the SHELXL riding model. Fig. 1 is an ORTEP3 [8]
draw showing the non-H atoms as 50% thermal vibration
ellipsoids.
1
C5H5Ru); 13C{ H} NMR (CDCl3, 100.61 MHz), 131–127
1
(m, C6H5), δ 81 (s, C5H5Ru), δ 73–67 (C5H4Fe); 31P{ H}
(CDCl3, 161.98 MHz), δ 44 (s, PPh3). IR (CsI) ν(N3)
2005, δ(N3) 660 ν(Ru–N) 387 cm−1. Elemental analysis
for C39H33N3FeP2Ru, calculated (found): C 60.1(62.3), H
4.37(4.41), N 5.51(5.44).
2.1.3. Synthesis of [Ru(η-Cp)(dppf)SnBr3] (2)
To a Schlenk flask containing a solution of [Ru(␩-
C5H5)(dppf)N3] (0.25 g, 0.34 mmol) in benzene (35 ml),
was added SnBr2 (0.37 g, 0.34 mmol) in 80 ml of ethanol.
After 10 h of stirring and reflux in N2, the solvent was re-
moved in vacuum, the solid was washed with ethanol and
re-crystallised from a mixture of chloroform and n-hexane.
mp 315–316. 1H NMR (CDCl3, 400.13 MHz), δ 7.3–7.2
(m, C6H5), 5.3(s), 4.4(s), 4.2(s), 4.0(s) (C5 H4Fe), 4.3
Table 1
Crystal data and structure refinement for [Ru(␩-Cp)(dppf)SnBr3] (2)
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system
C40H36Br3Cl3FeOP2RuSn
1211.31
120(2)
0.71073
Monoclinic
C2/c
Space group
Unit cell dimensions
a = 32.8879(4) Å
α = 90◦
b = 11.9888(2) Å
β = 92.545(1)◦
γ = 90◦
c = 20.8986(3) Å
Volume (Å3)
8231.9(2)
Z
8
Density (calculated) (Mg m−3
)
1.960
Absorption coefficient (mm−1)
4.529
4704
F(0 0 0)
Crystal size (mm)
0.01 × 0.08 × 0.13
Theta range for data collection (◦)
Index ranges
0.00–25.00
−39 ≤ h ≤ 39, −14 ≤ k ≤ 14, −24 ≤ l ≤ 24
Reflections collected
14073
Independent reflections
Completeness to theta = 25.00◦ (%)
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices (I > 2␴(I))
R indices (all data)
Extinction coefficient
Largest diffraction peak and hole (e Å−3
CCDC reference
7233 (R(int) = 0.023)
99.7
Full-matrix least-squares on F2
7233/1/491
1.056
R1 = 0.044, wR2 = 0.110
R1 = 0.056, wR2 = 0.118
0.00012(3)
)
2.673 and −1.135
206366

L.A. Paim et al. / Spectrochimica Acta Part A 60 (2004) 2383–2386
2385
Fig. 1. The molecular structure of [Ru(␩-Cp)(dppf)SnBr3] (2) and the atom numbering scheme. Ellipsoids are drawn at the 50% probability level. The
H atoms and solvent molecules are omitted for clarity.
1
(s, C5H5Ru); 13C{ H} NMR (CDCl3, 100.61 MHz), δ
ruthenium centre, Ru–Sn 2.5691(6) Å. The average of the
Sn–Br distances, 2.55(2) Å is very similar to that one found
for [Ru(␩5-Cp)(dppe)SnBr3] compound, 2.5508 Å [2].
The angles at the Sn(II) centre Br(1)–Sn–Br(2) 96.80(2),
Br(1)–Sn–Br(3) 96.55(2), Br(2)–Sn–Br(3) 93.79(3),
Ru–Sn–Br(1) 129.88(2), Ru–Sn–Br(2) 115.01(2), Ru–Sn–
Br(3) 117.46(2) are less symmetrical than those detected
for other derivatives [1,2].
127–141 (m, C6H5); 88(t), 85(t), 75(s), 73(s), 71(s), 69(s)
1
(C5H4Fe), 81 (s, C5H5Ru); 31P{ H} (CDCl3, 161.98 MHz),
δ 45 (s, dppf) (J2(31Pre-crystallized 119Sn) = 490 Hz),
1
119Sn{ H} (CDCl3, 149.21 MHz) δ −120 (t, SnBr3)
(2J(
= 490 Hz). 57Fe Mössbauer: IS 0.53(0.05)
119Sn–31P)
mm s−1, QS 2.29(0.05) mm s−1
.
119Sn Mössbauer: IS
2.71 mm s−1, QS 1.74 mm s−1. IR (CsI): ν(Sn–Br) 262 and
268 cm−1. Elemental analysis for C39H33Br3FeP2RuSn,
calculated (found): C 43.40(43.6), H 3.09(3.01), Br
22.21(22.31), Sn 11.01(11.07).
The infrared spectroscopic data were very important in the
characterisation process of both compounds. For 1, the more
important frequencies relates to the N3 group and Ru–N
bond. The former exhibits two signals at 2005 and 660 cm−1
,
which can be, respectively, associated to the symmetric vi-
bration mode (ν) and the to the deformation mode (δ) of the
fragment. A peak at 387 cm−1 was attributed to symmetric
vibration mode of the Ru–N bond. The two absorption re-
3. Results and discussion
Compounds 1 and 2 were isolated as mixture-free deriva-
tives and after re-crystallisation they showed acceptable
melting point, as well as satisfactory elemental analysis.
It was obtained as air- and moisture-stable orange–red
crystalline solids, readily soluble in polar organic solvents.
Compound 2 was studied by X-ray crystallography and
the results are displayed in Table 1. It is shown that the
compound crystallises as a chloroform and water solvate so
that the ratio between the complex and solvents is 1:1:1.
The water was probably originated from the RuCl3·xH2O,
employed in the preparation of the starting material.
Table 2 comprises the selected bond length and angles.
The Ru–P and Ru–Cp bond lengths and angles correlates
very well with other reported values [1,2]. The Sn(II) centre
posses a pseudo pyramidal trigonal geometry, where it is
asymmetric bonded to three halogens Sn–Br(1) 2.5362(7) Å,
Sn–Br(2) 2.5789(7) Å and Sn–Br(3) 2.5373(7) Å, and to a
Table 2
Selected bond lengths (Å) and angles (◦) for [Ru(␩-Cp)(dppf)SnBr3] (2)
P(1)–Ru
P(2)–Ru
Br(1)–Sn
2.343(2)
2.356(2)
2.5364(7)
Br(2)–Sn
Br(3)–Sn
Ru–Sn
Ru–M
2.5791(7)
2.5374(7)
2.5686(6)
1.858(1)
P(1)–Ru–P(2)
P(1)–Ru–Sn
P(2)–Ru–Sn
C(5)–Ru–Sn
C(4)–Ru–Sn
C(1)–Ru–Sn
C(2)–Ru–Sn
C(3)–Ru–Sn
100.62(5)
M–Ru–Sn
116.4(2)
95.43(4)
97.41(4)
102.9(2)
83.6(2)
140.3(2)
140.0(2)
102.8(2)
M–Ru–P(1)
M–Ru–P(2)
Br(1)–Sn–Br(3)
Br(1)–Sn–Ru
Br(3)–Sn–Ru
Br(1)–Sn–Br(2)
Br(3)–Sn–Br(2)
Ru–Sn–Br(2)
121.7(2)
120.1(2)
96.55(2)
129.88(2)
117.46(2)
96.79(2)
93.78(3)
115.02(2)
M denotes the centroid of the Cp bonded to Ru atom.

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L.A. Paim et al. / Spectrochimica Acta Part A 60 (2004) 2383–2386
lated to the N3 group was absent in the infrared spectra of
2. Two signals at 262 and 268 cm−1 have been attributed to
SnBr3 group.
attributed to Fe(II) and compares closely with the classical
values reported for ferrocene, [FeCp2], δ 0.44(2) mm s−1
and ∆ 2.38(3) mm s−1 and the dppf δ 0.42(2) mm s−1 and ∆
2.30(3) mm s−1 [9]. The single signal observed in the 119Sn
Mössbauer spectrum with parameters IS 2.71 mm s−1, QS
1.74 mm s−1, agrees with the 119Sn chemical shift found
in the NMR experiments and is characteristic of Sn(II)
[10].
1
The H NMR spectrum of compound 1 revealed signals
for the phenyl groups of the phosphine as a multiplet at
7.4–6.7. The resonances related to the hydrogens of the Fe
bonded cyclopentadienyl ring were observed as two sig-
nals at δ 5.2 and 4.1 with relative integrals 1:1. Finally, the
single signal related to the C5H5Ru fragment appeared at
1
δ 4.0. The 13C{ H} spectrum showed multiple signals at
131–127 corresponding to C6H5, a single resonance at δ 81
(s, C5H5Ru), and three peaks at δ 73, 70 and 67 attributed to
the ferrocene-containing Cp fragment. A single signal was
4. Supplementary data
Crystallographic data for the structural analysis for the
complexes discussed here have been deposited at the Cam-
bridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK, and are available on request quoting
the deposition numbers CCDC 206366.
1
1
detected in the 31P{ H} NMR spectrum δ 44. The H and
13C NMR data of 2 were quite remarkable. The Cp of the
dppf group normally displays two signals in the H NMR,
1
corresponding to a AB, AB system (integral 4:4), and the
13C NMR three signals of C␣, C␤ and C␥ (2:4:4), as in com-
pound 1. Upon co-ordination to SnBr3− fragment, there was
a broadening of the resonance signals of both nuclei, and also
a noteworthy change in the H and C multiplicity of both dppf
and Ph groups. The proton changed to a AB, AꢀBꢀ system
in 2, exhibiting signals at 5.3(s), 4.4(s), 4.2(s), 4.0(s) for the
dppf rings. Instead of three signals it was observed six 13C
resonances at 88(t), 85(t), 75(s), 73(s), 71(s), 69(s) for the
dppf ring. For the phenyl group it was observed multiplets in
both spectra. The unusual resonances of the dppf ring may be
from subtle variation on the electronic balance at each Fe–Cp
ring, which became slightly different after co-ordination to
SnBr3. It may be caused by small differences at the chemi-
cal environment of the phosphorous atoms. The C␣ bonded
to phosphorous should be equivalent and only one triplet
was supposed be detected. Instead, two distinct triplets were
observed in the 13C NMR experiment. It has been raised
by an asymmetric distribution of the bromine atoms around
the Sn(II) centre, as revealed by the X-ray diffraction study.
If the structure is carefully rotated, a closer approach be-
tween Br(1) and P(1) atoms can be observed. In spite of the
contact between both nuclei are not too close it is possible
that the electric and magnetic field of the magnetically ac-
tive 81Br (s = 32 ) effects a break the magnetic symmetry of
the phosphorous, changing the multiplicity of both H and C
in the corresponding Cp and Ph rings. Moreover, it is well
known that Sn–metal interactions have a high character of
double bond, hence, any rotation around the Sn–Ru bond,
Acknowledgements
The authors are grateful do CNPq and Fapemig for finan-
cial support. One of us, ACD, thanks FAPESP for a post-
doctoral fellowship.
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1
that could average the resonance signals in the H and 13C
NMR spectra, is frustrated. The 119Sn chemical shift, for
2 δ −120 with coupling constant J2(31P–119Sn) = 490 Hz,
situates in the expected position and relates very well the
obtained value for [Ru(␩5-Cp)(dppe)SnBr3].
The 57Fe Mössbauer parameters, IS 0.53(0.05) mm s−1
,
[10] A.G. Pereira, A.O. Porto, G.M. de Lima, H.G.L. Siebald, J.D. Ardis-
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QS 2.29(0.05) mm s−1 observed in the spectrum of 2, can be