Synthesis, structure, and some reactions of the cluster complex [(μ-H)2Fe5(μ3-Se)2(CO) 14]

Article abstract of DOI:10.1134/S1070328408100060

In the reaction of Na₂Se with [Fe(CO)₅] in isopropanol with subsequent acidification with HCl, which is used to synthesize [(μ-H)₂Fe₃(μ₃-Se)(CO)₉] (II), the cluster [(μ-H)₂Fe₅(μ₃-Se) ₂(CO)₁₄] (I) was detected. In assumption that compound I could serve as a suitable synthon for preparing the bulky heterometallic clusters, its reactions with the Rh-containing complexes were studied. The reaction of I with [Rh(CO)₂Cp*] (Cp*is pentamethylcyclopentadienyl) was found to give a mixture of the products. The main reaction products were isolated and their structures were determined: [Fe₂Rh(μ₃-Se)₂(CO)₆Cp*], [Fe₂Rh(μ₃-Se)(μ₃-CO)(CO) ₆Cp*], [FeRh₂(μ₃-Se)(μ-CO)(CO) ₃Cp ₂ * ], [Fe₂Rh₂(μ ₄-Se)(μ-CO)₄(CO)₂Cp ₂ * ]. Potassium hydride treatment of II with subsequent addition of [Cp*Rh(CH₃CN)₃](CF₃SO₃) ₂ leads to the well-known cluster complex [Fe₃Rh(μ ₄-Se)(CO)₉Cp*]. A set of the reaction products indicates that the {Fe₅Se₂} core cannot be used as one-piece building block in the synthesis of heterometallic clusters.

Full text of DOI:10.1134/S1070328408100060

ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2008, Vol. 34, No. 10, pp. 739–749. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © D.A. Bashirov, N.A. Pushkarevsky, A.V. Vitovets, O. Fuhr, S.N. Konchenko, 2008, published in Koordinatsionnaya Khimiya, 2008, Vol. 34, No. 10, pp. 748–758.
Synthesis, Structure, and Some Reactions of the Cluster Complex
[(m-H)2Fe5(m3-Se)2(CO)14]
D. A. Bashirova, N. A. Pushkarevskya, A. V. Vitovetsa, O. Fuhrb, and S. N. Konchenkoa
aNikolaev Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences,
pr. Akademika Lavrent’eva 3, Novosibirks, 630090 Russia
bInstitut für Nanotechnologie, Forschungszentrum Karlsruhe Postfach 3640, D-76021 Karlsruhe, Germany
E-mail: bashirov@ngs.ru
Received February 28, 2008
Abstract—In the reaction of Na2Se with [Fe(CO)5] in isopropanol with subsequent acidification with HCl,
which is used to synthesize [(µ-H)2Fe3(µ3-Se)(CO)9] (II), the cluster [(µ-H)2Fe5(µ3-Se)2(CO)14] (I) was
detected. In assumption that compound I could serve as a suitable synthon for preparing the bulky heterome-
tallic clusters, its reactions with the Rh-containing complexes were studied. The reaction of I with
[Rh(CO)2Cp*] (Cp* is pentamethylcyclopentadienyl) was found to give a mixture of the products. The main
reaction products were isolated and their structures were determined: [Fe2Rh(µ3-Se)2(CO)6Cp*], [Fe2Rh(µ3-
*
*
Se)(µ3-CO)(CO)6Cp*], [FeRh2(µ3-Se)(µ-CO)(CO)3Cp2 ], [Fe2Rh2(µ4-Se)(µ-CO)4(CO)2Cp2 ]. Potassium
hydride treatment of II with subsequent addition of [Cp*Rh(CH3CN)3](CF3SO3)2 leads to the well-known clus-
ter complex [Fe3Rh(µ4-Se)(CO)9Cp*]. A set of the reaction products indicates that the {Fe5Se2} core cannot be
used as one-piece “building block” in the synthesis of heterometallic clusters.
DOI: 10.1134/S1070328408100060
The target synthesis of the transition metal hetero- cle sizes, it seems reasonable to use the clusters with a
element cluster complexes is still being urgent due to higher nuclearity as the “building blocks”. This work is
the increasing interest in diverse functional materials devoted the experimental varification of the possibility
with preset composition and structure. Of special inter- of preparing the large heterometallic cluster complexes
est are the large heterometallic cluster complexes—the from diselenide complex [(µ-H)2Fe5(µ3-Se)2(CO)14] (I),
potential precursors of the highly ordered nanoparti- which is formed together with [(µ-H)2Fe3(µ3-Se)(CO)9]
cles, some of which have already showed themselves as (II) in the reaction of sodium selenide with iron pentac-
promising objects in the design of the high-capacity arbonyl in isopropanol with subsequent acidification
magnetic stores [1].
with HCl.
The chemistry of iron chalcogenide carbonyl clus-
ters has been well studied in terms of a subsequent
molecular design of the heteronuclear derivatives.
Thus, dichalcogenide complexes [Fe3(µ3-Q)2(CO)9],
EXPERIMENTAL
The synthesis and isolation of the reaction products
were performed in the atmosphere of inert gas in the
standard Schlenk apparatus. The solvents were dehy-
drated and degassed by boiling and refluxing in the
atmosphere of inert gas using the corresponding dehy-
drating agents [14]. The dissolved oxygen was removed
from water and HCl (in the form of azeotrope) by
refluxing in a slow argon flow. The Merck silica gel
(0.063−0.200 mm) was used in a column chromatogra-
phy. The following starting reagents were synthesized
by the known procedures: [Rh(CO)2Cp*] [15],
[Rh(CH3CN)3Cp*](CF3SO3)2 by analogy with
[Rh(CH3CN)3Cp*](BF4)2 [16]. The remaining reagents
were used as received.
[Fe3(µ3-Q)(µ3-Q')(CO)9],
[Fe2(µ-Q2)(CO)6],
and
[Fe2(µ-QQ')(CO)6] (Q, Q' = S, Se, Te) have been under
study for several decades [2, 3]. The sulfide cluster
[(µ-H)2Fe3(µ3-S)(CO)9 has been also studied thoroughly
[4], and suitable methods of synthesizing its analogs
[(µ-H)2Fe3(µ3-Q)(CO)9] (Q = Se, Te) have been devel-
oped later on, which allowed their systematic study
[5−7]. They were shown to be suitable synthons for
synthesizing a number of heteroelement clusters con-
taining several transition metals and/or p elements
(scheme 1; hereinafter the ligands CO are designated
by dashes) [8−13].
The above scheme illustrated huge potentialities and
The 1H NMR spectra were recorded on a Bruker AC
the high synthetic potential of the [(µ-H)2Fe3(µ3- 250 spectrometer at 250.133 MHz at room temperature.
Q)(CO)9] clusters. However, while expecting to obtain The TMS signals were used as the internal standard
the largest possible cluster aggregates of the nanoparti- when recording the NMR spectra.
739

740
BASHIROV et al.
Fe
Fe
Fe
Q
Fe
E
Fe
E
Q
Fe
Fe
Fe
S
Q
+
Fe
Fe
Fe
+
Fe
Q
Q
Fe
R
R
M
M
M
M
Ln
Cp*
Cp*
[CpM(CO)2]
M = Rh, Ir
Ln
{LnM}2+
M = Ir, Rh, Pt
S4N4
2–
Fe
Q
Fe
Q
Fe
{RE}2+
Base
H+
Fe
H
H
E = P, As, Sb, Bi
Q
Fe
Fe
Fe
E
Fe
Fe
R
Q = Se, Te
[CpxM(CO)3]2
M = Mo, W
CH3CN, ∆
Q
Fe
Fe
Fe
Fe
Me As
Fe
H
[CpxM(CO)3]2
M' = Mo, W
As Me
Q
Q
Q
MCpx
CpxM'
MCpx
Fe
Fe
Scheme 1.
The IR spectra of solutions were recorded on a trum; (toluene eluent) dark brown zone, (after concen-
Bruker IFS28 spectrometer.
Mass spectra were measured on a Varian MAT 711
instrument with the electronic impact ionization 70eV.
tration and cooling to −12°ë, ~0.105 g of the crystalline
product was obtained).
For I: 1H (CD2Cl2; δ, ppm): –39.69 (2H, µ-H).
IR (n-hexane; ν(CO), cm–1): 2098 w, 2068 s, 2059 w.
Synthesis of cluster I. To a solution of Na2Se in
100 cm3 of isopropanol prepared in situ from the amor-
phous selenium (1.99 g, 0.025 mol) and NaBH4 (2.13 g,
0.056 mol), 13 cm3 of Fe(CO)5 (18.98 g, 0.097 mol)
was added at room temperature. The mixture was
stirred for 12 h and then refluxed until liberation of CO
terminated (for another 12 h). Then, the mixture was
cooled, filtered through a glass filter G3, and 600 cm3
of a 5% HCl solution was added to the filtrate. The mix-
ture obtained was allowed to stay overnight. The liquid
was decanted from the black precipitate formed and
sh, 2026 s, 2012 m, 2002 w. sh.
Mass spectrum (m/z (Irel, %)): 832 (1.0) [M+]; 804
(0.7) [M+–CO]; 776 (0.7) [M+–2CO]; 748 (0.6) [M+–
3CO]; 720 (0.5) [M+–4CO]; 692 (1.2) [M+–5CO]; 664
(0.9) [M+–6CO]; 636 (1.5) [M+–7CO]; 608 (2.7) [M+–
8CO]; 580 (2.0) [M+–9CO]; 552 (1.9) [M+–10CO]; 524
(2.4) [M+–11CO]; 501 (8) [H2Fe3Se(CO)+9 ]; 473 (6)
[H2Fe3Se(CO)9+ –CO]; 445 (6) [H2Fe3Se(CO)9+ –2CO];
then, the latter was washed with 60 cm3 of water, 440 (5) [M+–14CO]; 417 (3.1) [H2Fe3Se(CO)+9 –3CO];
30 cm3 of methanol, and dried in a vacuum. The result-
387 (4.3) [H2Fe3Se(CO)+9 –4CO–2H]; 359 (12)
ing precipitate, containing I, II, and [Fe3(µ3-Se)2(CO)9],
[H2Fe3Se(CO)9+ –5CO–2H]; 331 (11) [H2Fe3Se(CO)+9 –
was stored in the atmosphere of argon at −12°C. For
every subsequent experiment, some portion of this mix-
6CO–2H]; 303 (6) [H2Fe3Se(CO)+9 –7CO–2H]; 247 (15)
[H2Fe3Se(CO)+9 –9CO–2H]; 28 (100) [CO+].
ture was used to prepare freshly isolated specimen of
cluster I. For this reason, ~0.25 g of the precipitate was
dissolved in several cm3 of toluene and them, ~3 cm3 of
silica gel was added and the solvent was removed in a
Reaction
of
I
with
KH
and
vacuum. The obtained mixture was applied onto a col- [Rh(CH3CN)3Cp*](CF3SO3)2. To a vessel, which con-
umn with silica gel (d = 2 cm, l = 30 cm) and chromato- tained a mixture of the solid starting compounds, i.e.,
graphed. The fraction order was as follows: (hexane I (0.213 g, 0.255 mmol) and KH (0.020 g, 0.5 mmol)
eluent) red-brown zone [Fe3(µ3-Se)2(CO)9], small quan- and was cooled with a liquid nitrogen, ~10 cm3 of THF
tities; broun zone, [Fe3(µ3-Se)2(CO)9]; green zone, was condensed. Then, the vessel was slowly heated in
[Fe3(CO)12], small quantities, identified from IR spec- air to room temperature. The mixture was stirred imme-
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 10 2008

SYNTHESIS, STRUCTURE, AND SOME REACTIONS
741
diately after the solvent melted and the stirring was vate VII · C7H8 were formed); (toluene as eluent) pale
continued for 24 h at room temperature. Then the mix-
ture was heated on a water bath at 55°ë and stirred at
this temperature until the liberation of hydrogen termi-
nated (~1.5 h). On cooling to room temperature, the
reaction mixture was filtered through a glass filter G3,
and the precipitate was washed with THF (15 cm3), and
the filtrates were poured together. The solution thus
obtained was frozen with a liquid nitrogen, and
[Rh(CH3CN)3Cp*](CF3SO3)2 (0.168, 0.255 mmol) was
added to a vessel. Then, the vessel was slowly heated in
air to room temperature. The stirring was started imme-
diately after the solvent melted and was continued for
24 h at room temperature. The reaction solution was fil-
tered and concentrated to dryness in a vacuum. The
solid residue was extracted with 20 cm3 or toluene and
10 cm3 of methylene chloride. The extracts were com-
bined and concentrated in a vacuum. The remaining
solid was dissolved in 3 cm3 of methylene chloride and
the solution was filtered. Then, hexane (10 cm3) was
poured over this solution. After the layers were mixed
fully at 0°ë, the dark red crystals of the above-men-
tioned compound [Fe3Rh(µ4-Se)(CO)9Cp*] (III) [9]
were obtained. The yield was 0.150 g (80% on conver-
sion to the starting Rh complex).
red-brown lengthy zone, the negligible amount of uni-
dentified compound.
For IV: IR (n-hexane: ν(CO), cm–1): 2067 w, 2051 s,
2026 s, 2009 w, 1984 s, 1968 s.
Mass spectrum (m/z (Irel, %)): 676 (3) [M+]; 648 (26)
[M+–CO]; 620 (27) [M+–2CO]; 592 (11) [M+–3CO]; 564
(8) [M+–4CO]; 536 (20) [M+–5CO]; 508 (100) [M+–6CO];
373 (27) [M+–6CO–Cp*].
For V: IR (n-hexane; ν(CO), cm–1): 2060 s, 2026 s,
2001 s, 1980 m, 1973 w, sh.
1H (CD2Cl2; δ, ppm): 1.94 (15 H, CH3, s).
Mass spectrum (m/z (IÓÚÌ, %)): 626 (24) [M+]; 598 (12)
[M+–CO]; 570 (19) [M+–2CO]; 542 (15) [M+–3CO]; 514
(24) [M+–4CO]; 486 (44) [M+–5CO]; 458 (92) [M+–6CO];
430 (100) [M+–7CO].
For VI: IR (CH2Cl2; ν(CO), cm–1): 2039 s, 2001 m,
1966 s.
Mass spectrum: 723 (5) [M+]; 695 (3.5) [M+–CO];
667 (3) [M+–2CO]; 639 (4) [M+–3CO]; 611 (28) [M+–
4CO]; 28 (100) [CO+].
For VII: mass spectrum (m/z (IÓÚÌ, %)): 835 (6) [M+];
751 (10) [M+–3CO]; 723 (5) [M+–4CO]; 695 (40) [M+–
5CO]; 667 (57) [M+–6CO]; 112 (100) [Fe(CO)+2 ].
Reaction of I with [Rh(CO)2Cp*]. Preparation of
[Fe2Rh(m3-Se)2(CO)6Cp*] (IV), [Fe2Rh(m3-Se)(m3-
X-ray diffraction analysis of I, IV−VI. VII · C7H8.
*
CO)(CO)6Cp*] (V), [FeRh2(m3-Se)(m-CO)(CO)3Cp2 ]
The crystallographic parameters and summary of data
*
(VI), and [Fe2Rh2(m4-Se)(m-CO)4(CO)2Cp2 ] (VII). To collection are presented in Table 1. The absorption cor-
rection for I, V was applied using the azimuthal scan-
a mixture of the solid reagents I (0.211 g, 0.254 mmol)
ning curves and integration with account for the crystal
and [Rh(CO)2Cp*] (0.077 g, 0.262 mmol), 5 cm3 of tol-
faceting, respectively; in the rest cases, it was applied
empirically on the basis of the intensities of the equiv-
uene was added on stirring. The mixture was stirred for
4 days at room temperature.After that, the solution con-
alent reflections. The structures were solved by the
tained a number of the reaction products (TLC control).
direct method and refined by the full-matrix least-
The reaction solution was concentrated to dryness in a
squares method in anisotropic approximation for non-
vacuum. The residue was dissolved in 6 cm3 of CH2Cl2,
hydrogen atoms. The calculations were performed with
~5 cm3 of silica gel was added, and the solvent was
the SHELXL-97 program package [17]. The hydrogen
removed in a vacuum after thorough stirring. The
obtained mixture was applied to a silica gel (the column
d = 2, l = 30 cm) and chromatographed. The order of
zones was as follows: (hexane–toluene (5 : 1) as eluent)
the dark brown zone containing the traces of [Fe3(µ3-
atoms were refined geometrically. The main bond
lengths for I, IV–VI, VII · C7H8 are listed in Table 2.
The coordinates of atoms, the thermal parameters, bond
lengths, and bond angles are deposited with the Cam-
bridge Crystallographic Data Center (No. 677881–
Se)2(CO)9], I, [Fe3(CO)12], and II; the red zone, IV 677885).
(after recrystallization from a toluene–hexane mixture,
only several crystals of the product were obtained); the
light yellow zone, the negligible amount of unidentified
RESULTS AND DISCUSSION
compound; the green zone, the negligible amount of
unidentified compound; (hexane–toluene (1 : 1) as elu-
ent) the dark red zone, V (after recrystallization from
hexane, the yield was 0.064 g (40% on conversion to
the starting Rh complex)); the light brown zone, the
The reaction of sodium selenide with [Fe(CO)5 in
isopropanol was used as a suitable method for synthe-
sizing cluster II [7]. The above reaction requires pro-
longed heating and gives several iron chalcogenide
forms in a solution. The addition of a 5% HCl solution
negligible amount of unidentified compound; (hexane– leads to the precipitation of a mixture of the products,
toluene (2 : 3) as eluent) the red zone, VI (with very low of which only three compounds were identified previ-
yield; after crystallization from hexane, only several ously, i.e., [Fe3(µ3-Se)2(CO)9], [Fe3(CO)12], and II. The
crystals were obtained); (hexane–toluene (1 : 7) as elu- components of the mixture, except for II, were present
ent) the brown zone, VII (in very low yield; on crystal- in insignificant amounts and therefore, the isolation and
lization from toluene, only several crystals of the sol- purification of the latter compound by extraction with a
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 10 2008

742
BASHIROV et al.
Table 1. The crystallographic parameters and summary of data collection for compound I, IV−VI, VII · C7H8
Value
Parameter
I
IV
V
VI
VII · C7H8
M
831.33
675.81
624.86
723.11
927.11
Crystal system
Monoclinic
Rhombic
Rhombic
Monoclinic
Triclinic
Space group
P21/n
P212121
P212121
P21/n
P1
8.6904(9)
9.9396(12)
20.839(2)
90.680(14)
96.958(13)
96.761(13)
1773.7(3)
2
a, Å
9.3907(12)
27.383(4)
9.5903(10)
90
9.1018(18)
12.452(3)
18.886(4)
90
9.062(3)
11.950(2)
14.737(3)
14.978(3)
90
b, Å
13.518(4)
c, Å
17.386(5)
α, deg
90
β, deg
106.446(9)
90
90
90
90
99.98(3)
90
γ, deg
90
V, Å3
2365.2(5)
4
2140.4(7)
4
2129.8(11)
4
2598.0(9)
4
Z
ρ(calcd.), g/cm3
F(000)
2.335
2.097
1.949
1.849
1.736
1584
1296
1216
1424
920
µ (radiation), mm–1
Crystal size, mm
6.137 (MoKα)
0.40 × 0.32 × 0.16
5.528 (MoKα)
19.244 (CuKα)
1.17 × 0.12 × 0.10
3.234 (MoKα)
2.782 (MoKα)
Diffractometer
T, K
Nonius CAD4,
Room temperature
STOE IPDS,
193.0(2)
Syntex P21, room
temperature
STOE IPDS,
203.0(2)
STOE IPDS,
213.0(2)
2θmax, deg
49.92
0 ≤ h ≤ 11
0 ≤ k ≤ 32
–11 ≤ l ≤ 10
4410
47.86
–8 ≤ h ≤ 10
–14 ≤ k ≤ 14
–19 ≤ l ≤ 21
6840
140.0
–2 ≤ h ≤ 11
0 ≤ k ≤ 16
0 ≤ l ≤ 21
2940
54.30
–15 ≤ h ≤ 15
–13 ≤ k ≤ 18
–18 ≤ l ≤ 19
11201
48.10
–9 ≤ h ≤ 9
–11 ≤ k ≤ 11
–23 ≤ l ≤ 23
10558
Range of reflection indices
Measured reflections
Independent reflection, Rint
Reflections with I ≥ 2σ (I)
Refined parameters
4149, 0.0519
1999
3268, 0.0492
3101
2633, 0.0707
2335
5473, 0.0696
4421
5263, 0.0549
3451
325
250
259
300
358
R-factors for I ≥ 2σ (I)
R1 = 0.0319
wR2 = 0.0567
R1 = 0.0366
wR2 = 0.1021
R1 = 0.0502
wR2 = 0.1177
R1 = 0.0438
wR2 = 0.1096
R1 = 0.0789
wR2 = 0.2481
R-factors for all reflections
GOOF on F2
R1 = 0.1035
R1 = 0.0386
R1 = 0.0556
R1 = 0.0519
R1 = 0.1069
wR2 = 0.0727
wR2 = 0.1042
wR2 = 0.1231
wR2 = 0.1132
wR2 = 0.2600
0.728
1.091
1.075
0.974
1.048
Residual electronic density
–0.444/0.474
–0.692/0.521
–1.543/1.433
–0.746/1.205
–1.046/4.683
(min/max, e Å–3)
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 10 2008

SYNTHESIS, STRUCTURE, AND SOME REACTIONS
Table 2. The main bond lengths and bond angles in I, IV−VI, VII · C7H8
743
Bond
d, Å
Angle
ω, deg
Bond
d, Å
Angle
ω, deg
I
C(11)–O(11) 1.145(17) O(1M)C(1M)Fe(2) 132.5(12)
Se(1)–Fe(1)
Se(1)–Fe(2)
Se(1)–Fe(3)
Se(2)–Fe(1)
Se(2)–Fe(4)
Se(2)–Fe(5)
Fe(1)–Fe(2)
Fe(1)–Fe(3)
Fe(1)–Fe(4)
Fe(1)–Fe(5)
Fe(2)–Fe(3)
Fe(2)–H(1)
Fe(3)–H(1)
Fe(4)–Fe(5)
Fe(4)–H(2)
Fe(5)–H(2)
Se(1)–Se(2)
2.3471(14) Fe(2)Fe(1)Fe(3)
2.3162(15) Fe(2)Fe(1)Fe(4)
2.2931(15) Fe(2)Fe(1)Fe(5)
2.3461(14) Fe(4)Fe(1)Fe(3)
2.3155(14) Fe(4)Fe(1)Fe(5)
2.2988(15) Se(2)Fe(1)Se(1)
2.6639(16) Se(1)Fe(1)Fe(4)
2.6783(16) Se(1)Fe(1)Fe(5)
2.6673(16) Se(2)Fe(1)Fe(2)
2.6700(16) Se(2)Fe(1)Fe(3)
2.6667(17) C(21)Fe(2)Fe(3)
59.89(4)
VI
153.31(6) Rh(1)–C(1)
2.019(5) Rh(1)Fe(1)Rh(2)
60.73(2)
59.27(2)
60.00(3)
68.873(19)
69.01(3)
69.52(2)
56.82(3)
56.63(2)
138.1(4)
134.5(4)
120.77(6) Rh(1)–Se(1) 2.3835(7) Fe(1)Rh(2)Rh(1)
128.15(6) Rh(1)–Fe(1) 2.6588(9) Fe(1)Rh(1)Rh(2)
60.17(4) Rh(1)–Rh(2) 2.6983(7) Rh(1)Se(1)Rh(2)
88.96(5) Rh(2)–C(1)
1.997(5) Fe(1)Se(1)Rh(1)
106.68(5) Rh(2)–Se(1) 2.3880(7) Fe(1)Se(1)Rh(2)
142.37(6) Rh(2)–Fe(1) 2.6786(9) Se(1)Fe(1)Rh(1)
102.58(5) Fe(1)–Se(1) 2.3088(11) Se(1)Fe(1)Rh(2)
142.71(6) C(1)–O(1)
1.186(5) O(1)C(1)Rh(2)
1.148(7) O(1)C(1)Rh(1)
VII · C7H8
101.9(3)
100.3(3)
23(3)
C(2)–O(2)
1.41(7)
1.48(7)
C(31)Fe(3)Fe(2)
Fe(3)Fe(2)H(1)
Rh(1)–Se(1) 2.5031(18) Fe(2)Rh(1)Fe(1)
Rh(1)–Fe(2) 2.598(2) Fe(1)Rh(2)Fe(2)
Rh(1)–Fe(1) 2.606(2) Fe(1)Se(1)Fe(2)
61.20(7)
61.56(7)
68.31(9)
2.6755(17) Fe(2)Fe(3)H(1)
22(3)
1.47(7)
1.57(7)
3.288 (8)
Fe(5)Fe(4)H(2)
Fe(4)Fe(5)H(2)
C(11)Fe(1)C(12)
IV
30(3)
28(3)
Rh(2)–Se(1) 2.490(2) Rh(2)Se(1)Rh(1) 117.39(7)
Rh(2)–Fe(1) 2.584(2) Rh(2)Fe(1)Rh(1) 110.58(8)
88.8(4)
Rh(2)–Fe(2) 2.592(2) Rh(2)Fe(1)Fe(2)
82.11(4) Se(1)–Fe(1) 2.359(3) Rh(1)Fe(1)Fe(2)
59.37(7)
59.25(7)
Rh(1)–Se(2)
Rh(1)–Se(1)
Rh(1)–Fe(2)
Rh(1)–Fe(1)
Fe(1)–Se(2)
Fe(1)–Se(1)
Fe(2)–Se(1)
Fe(2)–Se(2)
2.4040(10) Fe(2)Rh(1)Fe(1)
2.4057(10) Se(1)Rh(1)Se(2)
2.6575(13) Se(1)Fe(1)Se(2)
2.6872(13) Se(1)Fe(2)Se(2)
2.3564(14) Fe(1)Se(1)Fe(2)
2.3699(15) Fe(1)Se(2)Fe(2)
2.3617(14) C(1)Fe(1)Se(1)
2.3621(14) C(1)Fe(1)Se(2)
V
81.48(3) Se(1)–Fe(2) 2.359(3) Rh(2)Fe(2)Rh(1) 110.58(9)
83.24(5) Fe(1)–Fe(2) 2.649(3) Rh(2)Fe(2)Fe(1)
83.29(4) Rh(1)–C(22) 2.516(16) Rh(1)Fe(2)Fe(1)
95.79(5) Fe(1)–C(22) 1.797(19) Fe(1)C(22)Rh(1)
96.14(5) Rh(2)–C(23) 2.415(18) Fe(1)C(23)Rh(2)
59.07(7)
59.55(7)
72.2(6)
74.8(7)
75.8(7)
72.4(7)
87.5(3)
Fe(1)–C(23) 1.752(19) Fe(2)C(24)Rh(1)
Rh(1)–C(24) 2.388(18) Fe(2)C(25)Rh(2)
156.8(3)
Fe(2)–C(24) 1.766(17) O(22)C(22)Fe(1) 167.4(14)
Rh(1)–Fe(1)
Rh(1)–Fe(2)
Fe(1)–Fe(2)
Rh(1)–Se(1)
Fe(1)–Se(1)
Fe(2)–Se(1)
2.6373(17) Fe(2)Fe(1)Rh(1)
2.6506(19) Fe(1)Fe(2)Rh(1)
60.34(5) Rh(2)–C(25) 2.52(2)
59.84(6) Fe(2)–C(25) 1.73(2)
59.82(6) Fe(1)–C(21) 1.80(2)
O(21)C(21)Fe(1) 178(2)
O(22)C(22)Rh(1) 120.3(12)
O(23)C(23)Fe(1) 163.0(16)
2.637(3)
Fe(1)Rh(1)Fe(2)
2.3824(12) Fe(1)Se(1)Rh(1)
2.3396(18) Fe(2)Se(1)Rh(1)
67.90(5) Fe(2)–C(26) 1.770(19) O(23)C(23)Rh(2) 121.8(13)
68.48(5) C(21)–O(21) 1.11(3)
68.80(7) C(22)–O(22) 1.14(2)
55.28(5) C(23)–O(23) 1.18(2)
54.79(5) C(24)–O(24) 1.18(2)
132.9(10) C(25)–O(25) 1.21(2)
O(24)C(24)Fe(2) 161.3(15)
O(24)C(24)Rh(1) 122.2(12)
O(25)C(25)Fe(2) 168.5(17)
O(25)C(25)Rh(2) 119.1(13)
O(26)C(26)Fe(2) 177.7(19)
C(21)Fe(1)Fe(2) 157.8(7)
2.328(2)
Fe(2)Se(1)Fe(1)
Rh(1)–C(1M) 2.020(11) Se(1)Rh(1)Fe(1)
Fe(1)–C(1M) 2.124(13) Se(1)Rh(1)Fe(2)
Fe(2)–C(1M) 2.164(12) O(1M)C(1M)Rh
C(1M)–O(1M) 1.187(13) O(1M)C(1M)Fe(1) 135.1(10) C(26)–O(26) 1.16(2)
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 10 2008

744
BASHIROV et al.
hot hexane and crystallization on cooling did not cause
difficulties.
Since the anion [Fe5(µ3-Se)2(CO)14]2–, in principle,
is of interest as a large “building block” fro the synthe-
sis of heterometallic clusters, we performed a detailed
study of the above-mentioned mixture of the solid
product obtained on acidification and suggested that it
can contain the protonated form of the anion [Fe5(µ3-
Se)2(CO)14]2−. Indeed, in addition to [Fe3(µ3-
Se)2(CO)9], [Fe3(CO)12], and II, the mixture contained
cluster I in perceptible amounts (scheme 2) that could
be isolated by chromatography as individual com-
pound.
On the other hand, it was established previously that
in the reaction of K2Se with [Fe(CO)5] in DMF, which
resulted predominantly in the salt of the deprotonated
form II, i.e., [Fe3(µ3-Se)(CO)9]2–, gave also insignificant
amount of the cluster [Fe5(µ3-Se)2(CO)14]2–, identified in
[6] as a salt [PPh4]2[Fe5(µ3-Se)2(CO)14], whose accept-
able quantity can be obtained on lowering the reaction
temperature and reducing the synthesis time.
Fe
Fe
Fe
Fe
Fe
H
1. Se2–, iso-PrOH
Fe(CO)5
Se
Se
H
Fe
H
+
H
+ [Fe3(µ3-Se)2(CO)9] + [Fe3(CO)12]
Se Fe
2. H+, H2O
Fe
(I)
(II)
Scheme 2.
The cluster I core represents two tetrahedra {Fe3Se} ble in a solid state and can be stored in the atmosphere
of argon at –12°C for a week without noticeable decom-
position. Nevertheless, the elemental analysis of I did
not give satisfactory results. Taking this fact into
account, we used a freshly prepared specimen of com-
pound I for recording the spectra and in the subsequent
experiments.
with a shared vertex, i.e., the Fe(1) atom (Fig. 1). The
tetrahedra have a skewed conformation relative to the
mutual location of the Se atoms. The bridging H atoms
lie at the opposite bonds Fe–Fe, which lead to the char-
acteristic elongation of the corresponding bonds
Fe−Fe. All the Fe−Fe bond lengths in I are equal to
2.66–2.68 Å. The situation is different in
[Fe5(µ3-Se)2(CO)14]2–: the four central bonds Fe–Fe are
2.64–2.66 Å, but Fe(2)−Fe(3) and Fe(4)−Fe(5) (the
same numbering as in Fig. 1) are noticeably shorter,
i.e., ~2.60 Å [6]. The bridging H atoms are asymmetric
and deviate to different sides from the corresponding
plane Fe3. The H(1) atom deviates from the
F(1)Fe(2)Fe(3) plane toward the Se(1) atom (the angles
Fe91)Z(1)H(1) 168°), while H(2) deviates form the
The most probable approach to the design of heter-
ometallic clusters based on compound I core was
assumed to be the interaction of a neutral complex I or
its anionic form with the electrohpilic compounds of
transition metals or p elements. The distance between
two Se atoms in molecule I Se…Se is 3.29 Å (3.21 Å in
the dianionic form [6]). This suggests the possibility of
the bidentate coordination of the Se atoms to one metal
atom or to two other atoms located at a distance of a
bond. This coordination was supposed to be the emf of
the interaction between I and the electrophilic agents, at
least, at the first step.
1
Se(2) atom (the angle Fe(1)Z(2)H(2) 152°).
However, the 1H NMR spectrum of I in CD2Cl2 con-
tains only one singlet signal with the negative chemical
shift (d) corresponding to the bridging hydrogen, i.e.,
the asymmetry of the H atoms observed in X-ray dif-
fraction only occurs in the solid.
For cluster II and its sulfide and telluride analogs, it
was illustrated by a number of examples that the most suc-
cessful approach to the synthesis of heterometallic deriva-
tives is the following. By the reaction with KH,
complex II and its analogs are deprotonated and converted
to K2[Fe3(µ3-Q)(CO)9] (Q = S, Se, Te), which is then
reacted with the electrophilic agents. For example, the
subsequent treatment of compound II with KH and then
with [Rh(CH3CN)3Cp*](CF3SO3)2 results in the addition
of the fragment {RhCp*}2+ to [Fe3(µ3-Se)(CO)9]2– and
formation of heterometallic cluster III [9].
When studying compound II by the standard meth-
ods [7], cluster I was obtained in negligible amounts,
but it increases with the reduction in the reaction time.
However, in some experiments, after acidification of
the precipitate, cluster I was formed in quantities com-
parable with II, but its yields were unstable, and it is
still unclear what was the reason for this. Moreover, in
a solution, compound I turned unstable and gradually
(for several days) decomposed with the formation of II,
which is insoluble dark precipitate, and [Fe3(µ3-
Se)2(CO)9] in small quantities. Compound I is more sta-
It is particular this variant that was used for com-
pound I. It turned out hat in this case, too, the subse-
quent
treatment
with
KH
and
1
[Rh(CH3CN)3Cp*](CF3SO3)2 gave the same product III
Z(1) and Z(2) are the midpoints of the bonds Fe(2)−Fe(3) and
Fe(3)−Fe(4), respectively.
in a high yield (scheme 3).
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 10 2008

SYNTHESIS, STRUCTURE, AND SOME REACTIONS
745
Fe
Fe
Fe Se
RhCp*
Fe
Fe
1. äç, THF
2. [Rh(MeCN)3Cp*](CF3SO2)2
Se Fe Se
H
H
Fe
Fe
(I)
(III)
Scheme 3.
Thus, the reaction causes degradation of cluster I. design of heterometallic clusters containing the core of
This is likely to occur at the stage of the treatment with
KH, i.e., under the conditions required for completion
of the deprotonation reaction, and compound III
formed is actually the product of the interaction of the
cluster [Fe3(µ3-Se)(CO)9]2– obtained in a solution with
[Rh(CH3CN)3Cp*](CF3SO3)2. An attempt to vary the
time and temperature of the synthesis in reasonable
limits do not bring radical changes, and, in any case,
compound III is a sole heterometallic cluster being
compound I completely.
Nevertheless, one more variant of the synthesis of
heterometallic derivatives was tried using the neutral
protonated form of cluster I in the reaction with
[Rh(CO)2Cp*] that resulted in a mixture of a great
number of the products formed in a low yield, none of
the products being predominant. The most representa-
tive components IV−VII were isolated from a mixture
formed. The above result doubts the possibility of the and their structures were established (scheme 4):
Se
Se
Fe
Fe
Fe
RhCp*
Fe
Fe
Fe
Fe
Fe
Fe
Rh(CO) Cp* Cp*Rh
2
Se
Cp*Rh
RhCp*
Se Fe Se
H
+
+
+
H
Cp*Rh Se
Cp*Rh
toluene
Fe
Fe
Se
(IV)
(V)
(VI)
(I)
(VII)
Scheme 4.
O(42)
C(42)
O(31)
C(31)
Fe(4)
Se(1)
Fe(3)
Fe(1)
O(21)
Se(2)
H(2)
H(1)
C(21)
Fe(2)
Fe(5)
C(11)
O(11)
Fig. 1. The structure of cluster complex I (the thermal displacement ellipsoids of 50% probability, also used in Fig. 2–5).
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 10 2008

746
BASHIROV et al.
Rh(1)
Fe(1)
Fe(2)
Se(2)
O(1)
C(1)
Se(1)
Fig. 2. The structure of cluster complex IV.
Taking into account the tendency of I to a spontane- of a solution of this compound does not exhibit the
ous decay in a solution, the reaction was performed at absorption bands in the region of the wave numbers
room temperature, such that it could occur at reason- < 1970 cm–1. Obviously, the above distinct µ3-coordi-
able rate and the starting cluster could remain in a solu- nation of the CO ligand is realized only in a solid, while
tion for the maximum possible time. However, none of in a solution, the carbonyl groups show the dynamic
the products with the established structure contained behavior.
the {Fe5Se2} fragment completely, only it separate ele-
ments were detected.
Molecule VI (Fig. 4) also has the tringle metal core
with one coordinated µ3-Se ligand The Fe atom is coor-
Molecule IV (Fig. 2) represents the tetragonal pyra- dinated with three COt ligands and every Rh atom is
mid with Fe2Se2 base and the Rh atom in the apical ver- coordinated with Cp*. In addition, the bridging µ-CO
tex. Every Fe atom is coordinated with three terminal ligand is also coordinated to the Rh atoms. As in the
COt ligands, while the Rh atom is coordinated with case of V, the bridging CO group in the structure of VI
Cp*. The examples of the above clusters are numerous. lies on the other side of a plane passing through three
For instance, they are the typical products of replace- metal atoms such that the planes Rh(1)Rh(2)C(1) and
ment of the {Fe(CO)3} group by the isolobal metal frag- Rh(1)Rh(2)Fe(1) are almost mutually perpendicular.
ment in the compounds [Fe3(µ3-Q)2(CO)9] (Q = S, Se, The C(1) atom is equidistant from the Rh atoms, and
Te) or the products of addition of such a metal fragment the lengths of the Rh−C(1) bonds are almost equal to
to [Fe2(µ-Q2)(CO)6] (Q = S, Se, Te) [3].
those of Rh(1)–C(1M) in cluster V, but is remote from
the Fe(1) atom at a distance > 2.5 Å. The IR spectrum
of a solution of VI, as for cluster V, does not contain the
bands which could be assigned to the vibrations of the
bridging CO groups.
Molecule V (Fig. 3) forms the Fe2Rh triangle with
the coordinated µ3-ligands, i.e., Se and CO. As in com-
plex IV, every Fe atom is coordinated with the CO
ligands, while the Rh atom is coordinated with Cp*.
The µ3-CO ligand lies almost symmetrically above the
Molecule VII (Fig. 5) forms a distorted tribonal
Fe2Rh face: the distances M–C(1M) (M = Fe, Rh) differ bipyramid with the Fe2Se base and two Rh atoms in the
by about 0.15 Å, the MC(1M)O(1M) angles have close apical vertices. Every Rh atom is coordinated with the
values ~133°–135°. At the same time, the IR spectrum Cp* ligand and every Fe atom is coordinated to one COt
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 10 2008

SYNTHESIS, STRUCTURE, AND SOME REACTIONS
747
O(11)
Se(1)
C(11)
Fe(1)
Rh(1)
Fe(2)
C(1M)
O(1M)
Fig. 3. The structure of cluster complex V.
Se(1)
O(2)
C(2)
Rh(1)
Fe(1)
Rh(2)
C(1)
O(1)
Fig. 4. The structure of cluster complex VI.
ligand. The rest four CO groups are likely to be coordi- 120°. The analogous location of the carbonyl groups is
nated in a half-bridging mode: the distance between the
Fe and C atoms is characteristic of the Fe-C bond, but
the Rh-C distance is substantially longer (by 0.4 Å on
the average) than that in molecules of V and VI. How-
ever, in this case, the corresponding fragments Fe–C–O
are nonlinear, although the O atoms are shifted signifi-
cantly toward the Rh atoms: the corresponding FeCO
observed, for example, in the clusters [Fe3M(µ4-
Q)(CO)9Cp*] (Q = Se, Te; M = Rh, Ir), whose cores also
represent the trigonal bipyramid with the Fe2Q base and
the Rh or Ir atoms in the apical vertices [9].
The molecules of heterometallic products VI−VII
form as a result of different variants of addition of a
angles are 160°–170°, the RhCO angles are close to mononuclear fragment {Rh(CO)xCp*} and the frag-
RUSSIAN JOURNAL OF COORDINATION CHEMISTRY Vol. 34 No. 10 2008

748
BASHIROV et al.
O(21)
O(23)
C(21)
O(22)
Rh(1)
C(23)
C(22)
Fe(1)
Rh(2)
Se(1)
C(24)
Fe(2)
C(25)
O(24)
O(25)
C(26)
O(26)
Fig. 5. The structure of cluster complex VII.
ments of cluster I degradation: {Fe2Se(CO)y} and cluster. The set of the reaction products do not almost
{FeSe(CO)z}. The monitoring of the reaction course differ from that formed with the use of the
(TLC control) shows that compound II is soon formed [(µ-H)2Fe3(µ3-Se)(CO)9(II) cluster, which is more
in a solution, while compound V, which is the main studied.
component in a mixture of the reaction products, pre-
dominates among heterometallic clusters. The rest clus-
ters are formed with time in low quantities. Of course,
ACKNOWLEDGMENTS
the above stages are not separated and occur simulta-
neously, but in our opinion, compound V is the product
of the reaction of cluster I properly, while the rest are
the products of the reaction of cluster II formed in a
solution. To verify this fact, compound II was reacted
with [Rh(CO)2Cp*] under similar condition. The result-
ing se of the reaction products was almost identical to
that obtained in the reaction of I with [Rh(CO)2Cp*]. In
this case, too, the predominant product was
compound V, its yields in both cases being almost
equal. The sole difference observed was that clusterVII
was not detected in the reaction of [Rh(CO)2Cp*} with
II. However, since it was formed in negligible amounts
in the reaction with I, the above difference is not essen-
tial.
This work was supported by the Russian Foundation
for Basic Research (project no. 06-03-32946-a) and
INTAS Young Scientists Fellowship (project no. 05-
109-5302).
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