Reaction of Ru3(CO)12 with dibenzylideneacetone

Article abstract of DOI:10.1021/om0489958

The thermal reaction of Ru₃(CO)₁₂ with dibenzylideneacetone PhCH=CHCOCH=CHPh (1) was studied. From the solution, the trinuclear complexes Ru₃(CO)₆{μ₃- η²-η²-η²-O=C(CH=

Full text of DOI:10.1021/om0489958

Organometallics 2005, 24, 2279-2288
2279
Reaction of Ru3(CO)12 with Dibenzylideneacetone
Svetlana V. Osintseva, Fedor M. Dolgushin,* Nikolay A. Shtel’tser,
Pavel V. Petrovskii, Arkadii Z. Kreindlin, Leonid V. Rybin,† and
Mikhail Yu. Antipin
A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 Vavilov Street, 119991 Moscow, Russian Federation
Received December 17, 2004
The thermal reaction of Ru3(CO)12 with dibenzylideneacetone PhCHdCHCOCHdCHPh
(1) was studied. From the solution, the trinuclear complexes Ru3(CO)6{µ3-η2-η2-η2-OdC(CHd
CHPh)-CHdCPh}2 (6) and Ru3(CO)7{η2-OdC(CHdCHPh)CHdCPh}{µ-η-η4-O-C(CHdCHPh)-
CH-CPh-CH(CH2Ph)C(O)(CHdCHPh)}{µ3-η-η-η4-(CH2Ph)CHdC(O)-CHdCHPh} (7) were
isolated, and the precipitate was found to contain the tetranuclear complex Ru4(CO)8{µ3-η-
η2-η6-O-C(CHdCHPh)dCH-CPh-CH(CH2Ph)-C(O)-CHdCHPh}2 (8). The organic ligand in
complexes realizes different coordination modes forming five-membered oxaruthenacycle,
η3-coordinated dihydropyran cycle, η4-coordinated diene, or oxadiene fragments. Complex 7
is unstable and undergoes chemical transformations yielding complex 8. Reversible changes
occur with complex 8 upon dissolution in acetone, and binuclear complex Ru2(CO)4(η-Od
CMe2)(µ-η-η2-η6-O-C(CHdCHPh)dCH-CPh-CH(CH2Ph)-C(O)-CHdCHPh) (9) is formed. The
central Ru2O2 cycle in complex 8 is cleaved and the formed vacant coordination site is occupied
by an acetone molecule in complex 9. Complexes 6-9 were characterized by IR and 1H NMR
spectroscopy, and their structures were determined by single-crystal X-ray diffraction
analysis. The structural and spectroscopic features and possible pathways of the complexes’
transformations are discussed.
Introduction
by the two electron-deficient centers, viz., the ruthenium
atom and the carbon atom of the former keto group. The
attack by the nucleophilic center of the R,â-unsaturated
ketone (i.e., by the keto-oxygen atom) proceeds competi-
tively at these two sites.2d In the former case, addition
to the ruthenium atom is followed by ligand chelation,
which results in the closing of the second oxaruthena-
cycle, yielding complex 4.
Transition metal complexes of R,â-unsaturated ke-
tones are important intermediates in the synthesis of
organic products such as â-lactams,1a,b amino acids,1c
phenols,1d and heterocyclic compounds.1e However, re-
ports on the coordination chemistry of these ligands
with transition metals are scarce, although the presence
of the CdO ketone and CdC double bound in these
molecules may lead to a wide reactivity and various
coordination patterns.
Over the past decade, we have conducted systematical
studies on the reactivity of the R,â-unsaturated ketones
in thermal reactions with ruthenium carbonyls.2a-d
Thermally activated reactions of Ru3(CO)12 with 4-phe-
nylbut-3-en-2-one (1a),2a,b 3-phenyl-1-p-tolylprop-2-en-
1-one (1b),2a,b or 1,3-diferrocenylprop-2-en-1-one (1c)2c,d
yield, as primary products, bi- and trinuclear complexes
of ruthenium containing one or two η3-coordinated five-
membered oxaruthenacycles, i.e., Ru2(CO)6(µ-H)(R1Cd
C(H)C(O)R2) (2) and Ru3(CO)8(R1CdC(H)C(O)R2)2 (3)
(Scheme 1). These five-membered chelate oxaruthena-
cycles are formed via oxidative addition of a ruthenium
atom to the Câ-H bond with simultaneous coordination
of the keto-oxygen electron lone pair. Further, acting
as ligand, the oxaruthenacycle can form η3-complexes
through the CdC bond and the Ru atom.
In the latter case, addition to the carbon atom of the
oxaruthenacycle carbonyl group gives rise to the dihy-
dropyran ring, which gets involved in the coordination
to other ruthenium atoms through the multiple CdC
bonds and the lone pair of the exocyclic oxygen atom
(complex 5).
Reactivity of these oxaruthenacycles in further reac-
tion with the initial R,â-unsaturated ketone is defined
* Corresponding author. E-mail: fedya@xrlab.ineos.ac.ru.
† Prof. Leonid V. Rybin died in 2003.
10.1021/om0489958 CCC: $30.25 © 2005 American Chemical Society
Publication on Web 03/31/2005

2280 Organometallics, Vol. 24, No. 10, 2005
Osintseva et al.
Scheme 1
Minor products of these reactions mainly present
species containing combinations of the same cyclic
fragments, i.e., oxaruthenacycles and dihydropyran
rings.
In addition, we have studied thermal reactions of Ru3-
(CO)12 with dibenzoylethylene (PhCOCHdCHCOPh)2e
and dimethylfumarate (CH3OOCCHdCHCOOCH3).2f
The main structural block of the complexes thus ob-
tained was still the oxaruthenacycle. However, the
presence of additional centers available for coordination,
i.e., oxygen lone pairs, leads to bicyclic systems, in which
both oxygen atoms are involved in the chelation of two
different ruthenium atoms.
In the present paper, we report on the reactivity of
dibenzylideneacetone (DBA), PhCHdCHCOCHdCHPh
(1), in the thermally activated reaction with Ru3(CO)12.
In contrast to all earlier studied R,â-unsaturated ke-
tones, DBA contains two symmetric olefin groups, which
allows additional possibilities for coordination to metal
atoms. In this respect a formation of complexes with
earlier unobserved coordination modes may be sug-
gested. Furthermore, the interest in the DBA ligand is
due to its role in organometallic chemistry. In particular,
palladium DBA complexes have been extensively used
in ligand exchange reactions.3a-c Numerous palladium
complexes containing DBA, along with other ligands
such as phosphines, isocyanates, amines, olefins, and
acetylenes, have been prepared and characterized.3d-i
Extension of synthetic methods developed for palladium
to other metals led to development of DBA complexes
of Pt,4 Rh,5a and Ir.5b In the Pt, Pd, Rh, and Ir complexes
known so far, the DBA ligand is most frequently
π-coordinated through one of the CdC bonds or, less
frequently, through both CdC bonds; coordination
through the oxygen atom or CdO double bond has never
been observed.
A number of complexes have been synthesized not
directly from DBA or substituted divinylideneacetones,
but rather as a result of coupling of acetylenes coordi-
nated to transition metal clusters with participation of
metal-coordinated carbonyls. Such reactions have been
realized for Mo6a and Mn,6b,c and no π-coordination was
observed in these complexes.
Complexes of metals from the iron subgroup with the
DBA ligand,7a,b involving a variety of substituted
divinylideneacetones7c,d and ligands, produced via co-
ordination-assisted coupling of acetylenes and carbonyl
ligand,7e,f,g manifest the most diverse coordination modes.
The ligand binding therein may be realized either
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G.; Chen, L.; Wu, W.; Yin, J. Organometallics 1993, 12, 3431.

Reaction of Ru3(CO)12
Organometallics, Vol. 24, No. 10, 2005 2281
Table 1. IR and NMR Spectra for Complexes 6-9
compound
IR ν(CO), cm-1
1H NMR δ, ppm (C6D6)
(PhCHdCH)2COa
1668m, 1610s
7.08(d, 2H, CHdCH, J ) 16.0 Hz), 7.35-7.62(m, 10H, Ph),
7.74(d, 2H, CHdCH, J ) 16.0 Hz)
(PhCH2CH2)2COb
1684m, 1612s
2.27(t, 4H, CH2, J ) 7.8 Hz), 2.94(t, 4H, CH2, J ) 7.8 Hz),
7.30-7.70(m, 10H, Ph)
6a
7a
2046w, 2038s, 2028s,1992m,
1978w, 1968w
2056m, 2042s, 2016s, 1996m,
1980s, 1968m, 1938w
4.36(d, 1H, CHdCH, J ) 12,8 Hz), 4.65(d, 1H, CHdCH,
J ) 12,8 Hz), 5.35(s, 1H, CHdC), 7.18-7.98(m, 10H, Ph)
1.69-1.77(m, 2H, CH2), 1.96(d, 1H, CHdCH, J ) 7.2 Hz),
2.56-2.91(m, 3H, CH2-CH), 3.09-3.14(m, 1H, CH), 5.64(d, 1H,
CHdCH, J ) 7.2 Hz), 5.85(s, 1H, CHdC), 6.18(d, 1H, CHdCH,
J ) 16.0 Hz), 6.61-7.74(m, 44H, Ph, CHdCH, CHdC), 8.18(d,
1H, CHdCH, J ) 16.0 Hz), 8.71(d, 1H, CHdCH, J ) 16.0 Hz)
2.66-2.91(m, 1H, CHH-CH), 3.67-3.70(m, 1H, CHH-CH), 4.15(d,
1H, CHdCH, J ) 8.8 Hz), 4.46(s, 1H, CHdC), 5.42(m, 1H, CH2-CH),
6.36(d, 1H, CHdCH, J ) 8.8 Hz), 6.89-7.57(m, 22H, Ph, CHdCH)
2.93(dd, 1H, 2JH-H ) 15.6 Hz, 3JH-H ) 10.4 Hz, CHH-CH), 3.38(dd,
1H, 2JH-H ) 15.6 Hz, 3JH-H ) 2.8 Hz, CHH-CH), 3.86(d, 1H,
8b
2034m, 2023s, 1964s, 1956s
9b,c
2027s, 2018s, 1939s, 1933s,
1701m
CHdCH, J ) 8.9 Hz), 4.42(s, 1H, CHdC), 5.06(dd, 1H, 3JH-H
10.4 Hz, 3JH-H ) 2.8 Hz, CH2-CH), 6.14(d, 1H, CHdCH, J )
8.9 Hz), 7.1-7.65(m, 22H, Ph, CHdCH)
)
a IR in hexane. b IR in Nujol. c 1H NMR in acetone-d6, complex contains coordinated molecule of acetone-d6.
Scheme 2
through π-coordination of one or both CdC bonds7a-f as
well as the CdO bond7b,c or through coordination
involving one or two oxygen lone pairs7c,e or the Câ atom
(which thus forms one or two metal-carbon bonds).7c,e-i
In the latter case oxametallacycles may be formed.7c,e,i
However, complexes of ruthenium with DBA derived
directly from dibenzylideneacetone or its substituted
analogues have not been reported.
Results and Discussion
Reaction of Ru3(CO)12 with DBA was carried out in
boiling heptane. The course of the reaction was moni-
tored by in situ IR spectra in the region of stretching
vibrations of the coordinated carbonyl groups. After slow
cooling, the reaction mixture was separated into a
solution and a precipitate. From the solution, complexes
6 (17.1% yield) and 7 (3.5% yield) were isolated by
column chromatography on silica gel. The precipitate
contained complex 8 (8.2% yield) in the form of small
yellow crystals (Scheme 2).
(7) (a) Cano, A. C.; Zuniga-Villarrreal, N.; Alvarez-Toledano, C.;
Toscano, R. A.; Cervantes, M.; Daz, A.; Rudler, H. J. Organomet. Chem.
1994, 464, C23. (b) Bernes, S.; Toscano, R. A.; Cano, A. C.; Mellado,
O. G.; Alvarez-Toledano, C.; Rudler, H.; Daran, J. C. J. Organomet.
Chem. 1995, 498, 15. (c) Ortega-Jimenez, F.; Ortega-Alfaro, M. C.;
Lopez-Cortes, J. P.; Toscano, R. A.; Velasco-Ibarra, L.; Pena-Cabrera,
E.; Alvarez-Toledano, C. Organometallics 2000, 19, 4127. (d) Alvarez-
Toledano, C.; Delgado, E.; Donnadieu, B.; Hernandez, E.; Martin, G.;
Zamora, F. Inorg. Chim. Acta 2003, 351, 119. (e) Ros, J.; Solans, X.;
Font-Altaba, M.; Mathieu, R. Organometallics 1984, 3, 1014. (f)
Rivomanana, S.; Mongin, C.; Lavigne, G. Organometallics 1996, 15,
1195. (g) Knox, S. A. R.; Lioyd, B. R.; Morton, D. A. V.; Orpen, A. G.;
Turner, M. L.; Hogarth, G. Polyhedron 1995, 14, 2723. (h) Fassler, N.;
Huttner, G. J. Organomet. Chem. 1989, 376, 367. (i) Romero, A.; Vegas,
A.; Dixneuf, P. H. An. Quim. 1996, 92, 299.
Yet another compound was isolated chromatographi-
cally from the reaction mixture. Its IR spectrum reveals
no signals in the region of stretching vibrations of metal-
coordinated carbonyl groups but a distinct absorption
band due to stretching vibrations of the CdO bond (ν-
(CO) ) 1684 cm-1). Such a shift relative to the DBA
molecule may be caused by hydrogenation of the CHd
1
CH bonds. The H NMR data for this compound (see
Table 1) are in a good agreement with the published

2282 Organometallics, Vol. 24, No. 10, 2005
Osintseva et al.
Table 2. Selected Bond Lengths (Å) and Angles
(deg) for Complex 6
Ru(1)-Ru(2)
Ru(1)-C(1)
Ru(1)-C(5)
Ru(1)-C(6)
Ru(2)-C(2)
Ru(2)-C(3)
Ru(2)-C(6)
Ru(2)-O(4)
Ru(2A)a-C(13)
Ru(2A)a-C(14)
2.8402(8)
1.902(6)
2.233(4)
2.233(4)
1.861(5)
1.899(5)
2.080(5)
2.087(3)
2.268(5)
2.352(5)
O(1)-C(1)
O(2)-C(2)
O(3)-C(3)
O(4)-C(4)
C(4)-C(13)
C(4)-C(5)
C(5)-C(6)
C(6)-C(7)
C(13)-C(14)
C(14)-C(15)
1.132(6)
1.140(6)
1.138(6)
1.300(5)
1.456(6)
1.458(6)
1.402(6)
1.510(6)
1.400(7)
1.469(7)
Ru(2)-Ru(1)-Ru(2A)a 97.65(3) C(13)-C(4)-C(5)
122.5(4)
115.9(4)
120.5(4)
108.9(3)
130.0(3)
C(6)-Ru(2)-O(4)
C(4)-O(4)-Ru(2)
O(1)-C(1)-Ru(1)
O(2)-C(2)-Ru(2)
O(3)-C(3)-Ru(2)
O(4)-C(4)-C(13)
O(4)-C(4)-C(5)
80.6(2) C(6)-C(5)-C(4)
109.3(3) C(5)-C(6)-C(7)
177.9(5) C(5)-C(6)-Ru(2)
177.1(4) C(7)-C(6)-Ru(2)
179.0(5) C(14)-C(13)-C(4) 120.4(4)
119.4(4) C(13)-C(14)-C(15) 126.2(5)
118.0(4)
Figure 1. ORTEP representation (thermal ellipsoids
drawn at the 30% probability level) of the molecular
structure of complex 6.
data for 1,5-diphenylpentan-3-one.8 Upon formation of
an oxaruthenacycle in reactions of Ru3(CO)12 with
oxadienes, the ligand molecule loses a hydrogen atom,
while an excess amount of the ligand acts as a hydrogen
acceptor and thus undergoes reduction to the corre-
sponding saturated ketone.2d
a Symmetry transformation -x, y, -z+3/2 was used to generate
equivalent atoms.
complex 6 is symmetric; in the unit cell it occupies a
special position at the 2-fold axis passing through the
Ru(1) atom. Two DBA molecules are coordinated to
three ruthenium atoms. The open metal chain includes
two Ru-Ru bonds with a bond length of 2.8402(8) Å,
and the Ru(2)‚‚‚Ru(2A) nonbonding distance is equal to
4.276 Å. Each ligand chelates one of the terminal
ruthenium atoms forming the five-membered oxaruth-
enacycle. Two oxaruthenacycles are η3-coordinated to
the central ruthenium atom. The olefin bonds of each
ligand that do not take part in chelation are π-coordi-
nated to the ruthenium atoms at the opposite edges of
the metal chain. Additionally, each ruthenium atom
coordinates two carbonyl ligands. Taking into account
π-coordination and metal-metal bonding, this results
in a distorted octahedral ligand environment and com-
pletely filled 18-e shell for each ruthenium atom, so the
EAN rule is fulfilled.
Additional coordination of the second olefin bond in
6 affects the geometry of the η3-coordinated oxaruth-
enacycles insignificantly as compared to the studied
earlier fragments in the bi- (2) and trinuclear (3)
complexes.2a-c The molecular geometry of 6 is charac-
terized by a slightly shortened endocyclic Ru-O bond
(2.087(3) Å) and respectively an elongated CdO bond
(1.300(5) Å) with respect to the corresponding mean
values in 2 and 3 (2.12 and 1.28 Å, respectively). Most
probably, this is due to the electron-donor influence of
the π-coordinated olefin substituent at the keto group
of the oxaruthenacycle. Furthermore, in contrast to the
structures of 2 and 3, complex 6 reveals symmetrical
coordination of the Ru(1) atom to the metallacycle olefin
bond (the Ru(1)-C(5) and Ru(1)-C(6) bond lengths are
equalized to 2.233(4) Å), which probably reflects the
contracting influence of an additional π-coordination of
the exocyclic olefin bond. Meanwhile, coordination of the
exocyclic olefin bond to the Ru(2) atom is asymmetric;
the respective Ru(2)-C(13A) and Ru(2)-C(14A) bond
lengths are 2.268(5) and 2.352(5) Å.
Spectroscopic and X-ray Structural Character-
ization of 6. The molecular structure of complex 6 was
suggested on the basis of IR and NMR spectra (Table
1) and confirmed further by single-crystal X-ray diffrac-
tion analysis. The unique set of signals corresponding
to the coordinated ligand was observed in the 1H NMR
spectrum of 6. Due to π-coordination of the double bond
of the PhCHdCH group to the metal atom, the signals
of olefin protons are considerably shifted to higher fields
up to δ 4.36 and 4.65 ppm as compared to respective
values of 7.08 and 7.74 ppm for the initial ligand. A
decrease in the spin-spin coupling constant from 16.0
to 12.8 Hz also supports this conclusion. Similar values
of the chemical shifts and spin-spin coupling constant
(δ 4.78 and 5.29 ppm, H-HJ ) 11.3 Hz) were reported
for [Fe(CO)4]2(DBA), where each of the two Fe(CO)4
moieties is π-coordinated to one of the DBA CdC
bonds.7a The signal of the â-carbon proton of oxaruth-
enacycle, which corresponds to the CdC bond σ,π-
coordinated to two metal atoms, is observed at δ 5.35
ppm. For the closely related aforementioned complexes
2 and 3 containing η3-coordinated oxaruthenacycles, the
respective proton signals lie in the range δ 3-5 ppm.
Only in one case were analogous proton signals at-
tributed to the σ,π-coordinated CdC bond observed
beyond this range, i.e., at δ 5.06 and 5.17 ppm, which
is caused probably by an additional coordination of the
oxaruthenacycle to the second ruthenium atom through
the oxygen lone pair.2a The larger shift in 6 can be
explained by an influence of the adjacent π-coordinated
olefin bond. Therefore, the 1H NMR spectrum suggests
that complex 6 contains an η3-coordinated oxaruthena-
cycle and a π-coordinated PhCHdCH group. With
respect to the metal core, the organic ligand acts as a
seven-electron donor. The IR spectrum of 6 reveals six
absorption bands of different intensities in the region
of metal-coordinated carbonyls.
To verify the molecular structure of 6, an X-ray
diffraction study of its single crystal has been ac-
complished (Figure 1, Table 2). According to X-ray data,
The five-membered oxaruthenacycle in 6 adopts a
flattened twist conformation with the Ru(2) and O(4)
atoms shifted up and down by 0.294 and 0.263 Å from
the plane defined by the three carbon atoms. Due to
coordination to the ruthenium atoms, the organic ligand
(8) Altava, B.; Burguete, M. I.; Garcia-Verdugo, E.; Luis, S. V.;
Miravet, J. F.; Vicent, M. J. Tetrahedron: Asymmetry 2000, 11, 4885.

Reaction of Ru3(CO)12
Organometallics, Vol. 24, No. 10, 2005 2283
Table 3. Selected Bond Lengths (Å) and Angles
(deg) for Complex 7
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-C(10)
Ru(1)-O(8)
Ru(1)-O(10)
Ru(1)-O(11)
Ru(2)-C(3)
Ru(2)-C(4)
Ru(2)-O(10)
Ru(2)-O(11)
Ru(2)-C(25)
Ru(2)-C(26)
Ru(2)-C(27)
Ru(3)-C(5)
Ru(3)-C(6)
Ru(3)-C(7)
Ru(3)-C(59)
1.865(6)
1.844(6)
2.039(5)
2.087(4)
2.154(3)
2.147(3)
1.838(6)
1.853(6)
2.056(3)
2.217(3)
2.717(5)
2.274(5)
2.118(5)
1.916(7)
1.896(7)
1.921(6)
2.249(5)
Ru(3)-C(60)
Ru(3)-C(61)
Ru(3)-C(68)
O(8)-C(8)
2.185(5)
2.199(6)
2.200(5)
1.265(6)
1.429(7)
1.364(7)
1.370(6)
1.458(6)
1.368(7)
1.446(7)
1.547(7)
1.526(7)
1.398(6)
1.352(6)
1.413(7)
1.428(7)
1.426(7)
C(8)-C(9)
C(9)-C(10)
O(9)-C(25)
O(9)-C(42)
C(25)-C(26)
C(26)-C(27)
C(27)-C(43)
C(42)-C(43)
O(10)-C(42)
O(11)-C(59)
C(59)-C(60)
C(59)-C(68)
C(60)-C(61)
O(11)-Ru(1)-O(10)
O(10)-Ru(2)-O(11)
76.16(12) C(25)-O(9)-C(42) 114.7(4)
76.63(12) C(26)-C(25)-O(9) 121.9(5)
Ru(2)-O(10)-Ru(1) 105.16(14) C(25)-C(26)-C(27) 121.4(5)
Ru(1)-O(11)-Ru(2) 100.04(13) C(26)-C(27)-C(43) 112.5(5)
C(10)-Ru(1)-O(8)
C(8)-O(8)-Ru(1)
O(8)-C(8)-C(9)
C(10)-C(9)-C(8)
C(9)-C(10)-Ru(1)
80.17(18) O(9)-C(42)-C(43) 109.5(4)
112.4(3)
118.4(5)
117.2(5)
111.1(4)
C(42)-C(43)-C(27) 107.2(4)
C(60)-C(59)-C(68) 116.5(5)
C(59)-C(60)-C(61) 120.1(5)
Figure 2. ORTEP representation (thermal ellipsoids
drawn at the 30% probability level) of the molecular
structure of complex 7. Phenyl substitutions are omitted
for clarity.
down from the plane defined by the three carbon atoms),
while the C-C bonds in the organic part of the metal-
lacycle are essentially alternating. A slight shortening
of the endocyclic Ru(1)-C(10) and C(8)-C(9) bonds
(2.039(5) and 1.429(7) Å) as compared to those in 6
(2.079(5) and 1.457(6) Å) indicates that the uncoordi-
nated oxaruthenacycle has a partial ruthenafuran (i.e.,
O-RudC(Ph)-C(H)dC(CHdCHPh)) character.2d
slightly deviates from planarity: the dihedral angle
between the C(4)C(5)C(6) and C(4)C(13)C(14) planes is
equal to 11.2°; the planes of the two phenyl substituents
are rotated by 17.6° and 13.3° with respect to the
corresponding three-carbon moieties.
Spectroscopic and X-ray Structural Character-
ization of 7. The second component of the solution
obtained in the reaction of Ru3(CO)12 with DBA, i.e.,
The nonplanar six-membered dihydropyrane cycle in
7 adopts a distorted twist conformation with the C(42)
and C(43) atoms shifted by 0.406 and 0.335 Å up and
down from the mean plane defined by the four atoms
O(9), C(25), C(26), and C(27) (which are planar to within
0.045 Å). A distinctive feature of coordination of this
ligand to the Ru(2) atom consists in the substantial
nonequivalency of the Ru(2)-Callyl bond lengths. It may
be explained by the asymmetric ligand environment of
the ruthenium atom involved in coordination. Indeed,
the carbonyl group C(3)O(3) and the coordinated O(11)
atom, which possess substantially different electron-
donating properties, are situated in the pseudo-trans
positions to the allylic fragment. The nonequivalence
of the Ru-Callyl distances and substantial difference in
the C-C bond lengths within the allylic fragment (see
Table 3) allow an alternative description of the coordi-
nation to the ruthenium atom. This implies formation
of a Ru-C σ-bond (Ru(2)-C(27)) and noticeable weak-
ening of the η2-coordination of the C(25)dC(26) olefin
bond. Note that similar η3-coordination of the dihydro-
pyran ring was revealed by us earlier for products of
reactions of Ru3(CO)12 with oxadienes. In particular,
binuclear complexes 5 have been characterized as one
of the major reaction products.2d
1
complex 7, has been characterized by IR and H NMR
spectra; its molecular structure has been unequivocally
determined by single-crystal X-ray diffraction analysis.
According to X-ray data, complex 7 is composed of three
Ru atoms linked together by four DBA ligands (Figure
2, Table 3). The oxadiene system of the first ligand
chelates the Ru(1) atom, forming a five-membered
oxaruthenacycle. Another two molecules of DBA are
coupled with formation of a dihydropyrane cycle, which
is η3-coordinated to the Ru(2) atom. The exocyclic oxygen
atom (O(10)) of the dimerized ligand links the Ru(1) and
Ru(2) atoms. Additionally, the Ru(1) and Ru(2) atoms
are bridged by the enolate oxygen atom (O(11)) of the
fourth ligand, which in turn is η4-coordinated to the Ru-
(3) atom. The formed four-membered Ru2O2 cycle is
folded along the line connecting the Ru(1) and Ru(2)
atoms by 17.1°. Each oxygen atom in this Ru2O2 cycle
acts as a three-electron donor and thus forms shorter
covalent and longer coordination Ru-O bonds (Table
3).
The geometry of the five-membered oxaruthenacycle
in 7 is similar to that observed earlier for uncoordinated
oxaruthenacycles in chloride-bridged binuclear com-
plexes Ru2(CO)4(µ-Cl)2[OdC(R′)-C(H)dC(R′′)]2, where R′
) Me, R′′ ) Ph,2c or R′ ) R′′ ) Fc.2d This indicates that
introduction of substituents into the chain of the start-
ing oxadiene has only an insignificant influence on the
geometry of the oxaruthenacycles. In contrast to the η3-
coordinated oxaruthenacycle in complex 6, the uncoor-
dinated oxaruthenacycle in 7 is planar (the Ru(1) and
O(8) atoms are shifted by 0.089 and 0.088 Å up and
A distinctive feature of the five-membered oxaruth-
enacycle and the η3-coordinated dihydropyran cycle in
complex 7 is the presence of free olefin groups uncoor-
dinated to ruthenium atoms; that is, the DBA ligand
behaves identically to alkyl- and aryl-substituted oxa-
dienes studied earlier. However, the similarity cannot
be extended further. The presence of the second olefin

2284 Organometallics, Vol. 24, No. 10, 2005
Osintseva et al.
group in DBA starts to play a role in coordination of
the fourth ligand in complex 7. Coordination of the keto-
oxygen O(11) atom to the Ru(1) and Ru(2) atoms
polarizes the CdO bond so that the enol form of the
ligand (produced by migration of the CdC double bond)
becomes more stable. As a result, the C(68)C(59)C(60)C-
(61) diene system η4-coordinated to the Ru(3) atom is
formed. The C(69) atom becomes sp3-hybridized and,
respectively, the C(59)-O(11) bond is elongated to
1.352(6) Å, which is typical for C(sp2)-O single bonds,
1.354 Å.9 It is necessary to note that the diene system
in 7 adopts the s-cis configuration. This coincides with
behavior of acyclic conjugated dienes: upon formation
of η4-complexes with transition metals, the s-cis ar-
rangement predominates over the s-trans geometry,
independently of the preferred conformation adopted by
the free ligand.10
Figure 3. ORTEP representation (thermal ellipsoids
drawn at the 30% probability level) of the molecular
structure of complex 8. Phenyl substitutions are omitted
for clarity.
The IR and 1H NMR data for complex 7 are in
agreement with results of X-ray diffraction analysis. The
IR spectrum reveals seven absorption bands of different
intensities in the region of metal-coordinated carbonyls
(Table 1). In the 1H NMR spectrum, a singlet at δH 5.85
ppm can be attributed to the allyl proton of the dihy-
dropyran cycle. Earlier, signals of similar protons in two
complexes containing dihydropyran cycles were ob-
served in the higher-field region, viz., at 3.82 and 5.16
ppm.2d In the former case, the pseudo-trans position to
the allyl fragment is occupied by a ligand other than
CO. The low-field shift of the proton signal in complex
7 as compared with the latter mentioned case may be
due to a benzylidene substituent.
The part of the spectrum attributable to the ligand
η4-coordinated to the Ru(3) atom is of particular note.
Protons of the coordinated C(60)dC(61) double bond give
rise to two doublets at 1.96 and 5.64 ppm (JH-H ) 7.2
Hz), with the terminal proton at the C(61) atom most
likely contributing to the high-field signal.11 The proton
attached to the C(68) atom gives a multiplet at 3.09-
3.14 ppm due to the spin-spin interaction with protons
of the adjacent C(69)H2 group.
Table 4. Selected Bond Lengths (Å) and Angles
(deg) for Complex 8
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-C(7)
Ru(1)-O(3)
Ru(1)-O(3A)a
Ru(1)-O(4)
Ru(2)-C(5)
Ru(2)-C(6)
Ru(2)-C(8)
Ru(2)-C(9)
Ru(2)-C(24)
1.853(9)
1.854(11)
2.098(8)
2.094(5)
2.259(5)
2.116(5)
1.940(9)
1.822(9)
2.276(8)
2.444(8)
2.208(8)
Ru(2)-C(25)
Ru(2)-C(26)
Ru(2)-O(4)
O(3)-C(9)
2.212(8)
2.136(7)
2.223(5)
1.335(9)
1.366(9)
1.544(10)
1.562(11)
1.406(10)
1.441(11)
1.429(11)
1.527(11)
O(4)-C(26)
C(7)-C(8)
C(7)-C(27)
C(8)-C(9)
C(24)-C(25)
C(25)-C(26)
C(26)-C(27)
O(3)-Ru(1)-O(3A)a
78.5(2) C(26)-C(25)-C(24) 116.6(7)
Ru(1)-O(3)-Ru(1A)a 101.5(2) O(4)-C(26)-C(25)
115.7(7)
77.0(3)
O(3)-Ru(1)-C(7)
C(9)-O(3)-Ru(1)
C(8)-C(7)-Ru(1)
C(9)-C(8)-C(7)
O(3)-C(9)-C(8)
84.7(2) C(7)-Ru(1)-O(4)
111.4(4) C(26)-O(4)-Ru(1)
102.8(5) O(4)-C(26)-C(27)
119.3(7) C(26)-C(27)-C(7)
118.7(7) C(27)-C(7)-Ru(1)
113.0(5)
116.5(7)
101.7(6)
105.7(5)
a Symmetry transformation -x+1, -y+1, -z+1 was used to
generate equivalent atoms.
X-ray Structural Characterization of Complex
8. According to X-ray diffraction data, complex 8 consists
of two equivalent binuclear fragments (the crystal-
lographic inversion center lies at the middle of the Ru-
(1) and Ru(1A) atoms, see Figure 3 and Table 4). Four
ruthenium atoms are joined together by four DBA
molecules, forming a system of fused metallacycles of
three different types. The central four-membered Ru2O2
cycle is planar with nonequivalent Ru(1)-O(3) (2.095-
(5) Å) and Ru(1)-O(3A) (2.258(5) Å) bonds. The O(3)
atom is involved in the five-membered oxaruthenacycle
Ru(1)C(7)C(8)C(9)O(3), in which the C(7) atom is satu-
rated and the C(8)dC(9) double bond is π-coordinated
to the Ru(2) atom (the Ru(2)-C(8) and Ru(2)-C(9) bond
lengths are substantially different, viz., 2.279(8) and
2.447(8) Å). The olefin bond migrates to the carbon atom
of the keto group so that the C(9)-O(3) bond becomes a
single one (1.338(9) Å). The observed redistribution of
the bonding within the chain of the initial DBA molecule
occurs as a result of coupling of two DBA molecules and
formation of a new C-C bond (C(7)-C(27) 1.558(11) Å).
The coupled ligand forms one more five-membered
oxaruthenacycle Ru(1)C(7)C(27)C(26)O(4), which con-
tains two saturated carbon atoms (C(7) and C(27)) and
a formally double C(26)dO(4) bond that is π-coordinated
to the Ru(2) atom. Due to additional coordination of the
O(4) atom to the Ru(1), the C(26)dO(4) bond is elon-
gated to 1.364(9) Å, which exceeds the normal values
of 1.306-1.320 Å for π-coordinated carbonyl groups.12,13
The remaining olefin bond of the second DBA molecule
is also π-coordinated to the Ru(2) atom, which makes it
possible to describe this moiety of complex 8 as a η4-
coordinated oxadiene fragment. Bond lengths in the
C(24)C(25)C(26)O(4) chain are equalized; thus the π-co-
ordination to the Ru(2) atom is nearly symmetrical. It
is important to note that η4-coordination of the oxadiene
ligand to the ruthenium atom that was observed in
complex 8 is quite rare in contrast to the η4-coordination
of diene ligands, frequently encountered in π-complexes
(9) Allen, F. H.; Kennard, O. K.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1.
(10) Erker, G.; Wicher, J.; Engel, K.; Rosenfeldt, F.; Dietrich, W. J.
Am. Chem. Soc. 1980, 102, 6346.
(11) (a) Warren, J. D.; Clark, R. I. Inorg. Chem. 1970, 9, 373. (b)
Ruh, S.; Philipsborn, W. J. Organomet. Chem. 1977, 123, C59.
(12) Hiraki, K.; Nonaka, A.; Matsunada, T.; Kawano, H. J. Orga-
nomet. Chem. 1999, 574, 121.
(13) Marcuzzi, A.; Linden, A.; Philipsborn, W. Helv. Chim. Acta
1993, 76, 976.

Reaction of Ru3(CO)12
Organometallics, Vol. 24, No. 10, 2005 2285
Scheme 3
of transition metals. Probably, this is due to the fact
that oxygen-containing ligands tend to coordinate ru-
thenium and osmium atoms via donation of lone pairs,
forming chelate rings.14 All η4-enone complexes isolated
so far are mononuclear and were obtained as a result
of intramolecular rearrangement12,15 or ligand-exchange
reactions13 rather than directly from the respective
enones.
The structure of the five-membered oxaruthenacycles
in 8 is noticeably different from the unsaturated oxaru-
thenacycles found in 6 and 7. The Ru(1)C(7)C(8)C(9)O-
(3) cycle is nearly planar, adopting a conformation of a
flattened envelope: the C(7) atom deviates from the
plane of the other four cyclic atoms by 0.316 Å in the
direction opposite the Ru(2) atom (the torsion angle
C(8)C(9)O(3)Ru(1) is 0.5°). The Ru(1)-C(7) bond is
elongated to 2.098(8) Å, as compared to 2.039(5) and
2.079(5) Å for similar bonds in the uncoordinated cycle
in 7 and η3-coordinated cycle in 6. The Ru(1)-O(3) bond
length of 2.095(5) Å is close to those of similar bonds in
the oxaruthenacycles of complexes 6 and 7 (2.087(4) Å).
The nonplanar Ru(1)C(7)C(27)C(26)O(4) cycle in 8
adopts an envelope conformation: the C(7) atom devi-
ates from the plane of the other four cyclic atoms by
0.844 Å in the direction of the Ru(2) atom (the torsion
angle Ru(1)O(4)C(26)C(27) is 4.3°). The Ru(1)-O(4)
bond is elongated to 2.117(5) Å.
which probably facilitates coupling. As a result, the
C(10) and C(68) atoms become sp3-hybridized, and the
order of the C(59)-O(11) bond increases, which enables
involvement of the CdO bond in π-coordination to the
Ru atom. Furthermore, the initial η4-diene fragment
transforms into the η4-oxadiene in the resultant com-
plex. The migration of the double bond from C(68)d
C(59) to C(59)dO(11) is, probably, accompanied by a
rotation around the C(59)-C(60) bond to realize the cis-
arrangement of the CdC and CdO bonds, which is more
favorable for coordination as in the case of butadienes.10
Similar rearrangements within the coordination sphere
of metal atoms were described for ruthenium com-
plexes.16 An additional driving force of the isomerization
is, probably, formation of the stable chelating oxaruth-
enacycle.17 Formation of complex 8 is completed by
association of the two modified fragments of complex 7
through the Ru(1) and O(8) atoms to a symmetrical
Ru2O2 cycle. Complex 8 is insoluble in heptane and
precipitates from the reaction mixture as crystalline
powder (see Experimental Section), which prevents its
further transformations under the reaction conditions.
It can be assumed that the second part of complex 7
(dihydropyrane cycle and Ru(2) atom in Scheme 3) also
undergoes coupling through the Ru(2) and O(10) atoms,
yielding a compound similar to complex 5.2a However,
we failed to isolate this complex from the reaction
mixture.
To our knowledge, only in one case was C-C coupling
of oxadienes reported to date, viz., formation of the
complex Ru2(CO)5{µ-η3-η2-CH(COOMe)-C(COOMe)-CH-
(COOMe)-CH(COOMe)}{η2 -CH(COOMe)-CH2 -
(COOMe)} in the reaction of Ru3(CO)12 with dimethyl-
fumarate.2f This complex is likely formed by introduc-
tion of an additional ligand molecule as in the case of
the formation of the dihydropyran cycles.
Solution Behavior of Complex 8 and X-ray Struc-
tural and Spectroscopic Characterization of Com-
plex 9. Complex 8 is poorly soluble in benzene. Other
solvents (e.g., CHCl3, CH2Cl2, ethers, acetonitrile, THF)
The solid-state IR spectrum of complex 8 reveals four
absorption bands of approximately equal intensities in
the region of the coordinated carbonyls, which is in
agreement with the symmetry of the molecule and the
presence of two CO groups at each ruthenium atom in
the cis-positions with respect to each other.
Irreversible Transformation of 7 into 8. The low
yield of complex 7 in the thermal reaction of Ru3(CO)12
with DBA can indicate that this product is unstable and
readily converts into other substances under the reac-
tion conditions. To gain deeper insight into the trans-
formation of complex 7, an investigation of the chemical
behavior of isolated complex 7 under the reaction
conditions was carried out. We found that boiling 7 in
heptane in the presence of DBA yields a mixture of
products, from which complex 8 was isolated (see
Experimental Section). It should be noted that no
reaction occurs in the absence of DBA. On the other
hand, complex 8 is also formed upon boiling 7 in heptane
with benzylideneacetone (4-phenylbut-3-en-2-one, 1a)
instead of DBA. This suggests that complex 8 is formed
as a result of the decomposition of complex 7 activated
by additional DBA or another oxadiene (e.g., 1a) mol-
ecule. We suppose that the decomposition of complex 7
goes through the cleavage of the longest Ru(2)-O(11)
and Ru(1)-O(10) bonds (2.217(3), 2.154(3) Å) of the
Ru2O2 cycle. The reaction proceeds further as C-C
intramolecular coupling of two ligands within the
coordination sphere of the ruthenium atoms (see Scheme
3). The new C-C bond is formed between atoms C(10)
and C(68). The distance between these two atoms in
starting complex 7 (3.375(7) Å) is slightly shorter than
the sum of the van der Waals radii of two carbon atoms,
(14) Arce, A. J.; Sanetis, I. D.; Deeming, A. J.; Hardcostle, K. J.;
Lee, R. J. Organomet. Chem. 1991, 406, 209.
(15) Jia, G.; Meek, D. W.; Gallucci, J. C. Organometallics 1990, 9,
2549.
(16) Blackmore, T.; Bruce, M. I.; Stone, F. G. A. J. Chem. Soc.,
Dalton Trans. 1974, 106.
(17) Rybinskaya, M. I.; Krivikh, V. V. Russ. Chem. Rev. 1984, 53,
825 [Uspehi Khim. 1984, 53, 825].

2286 Organometallics, Vol. 24, No. 10, 2005
Osintseva et al.
acetone is directly bonded to the metal center. The Ru-
(1)-O(5) bond length, 2.214(3) Å, lies within the normal
range of 2.103-2.363 Å reported for similar species.18
The presence of a donor acetone ligand strongly affects
coordination of the C(12) atom situated in the trans-
position. The Ru-C bond length increases from 2.098-
(8) Å in complex 8 up to 2.124(3) Å in 9. Moreover, on
going from 8 to 9, the absence of additional coordination
of the O(6) atom to the second ruthenium atom leads to
noticeable shortening of the formally single C(10)-O(6)
bond to 1.301(4) Å (as compared to 1.338(9) Å for the
respective C(9)-O(3) bond in 8). Other structural changes
are insignificant.
In the vast majority of cases described in the litera-
ture, acetone occupies the free coordination site at the
metal atom only in the absence of stronger coordinating
agents, for example, in the course of rearrangements
performed in acetone as a solvent.18b The ease of
elimination of acetone was successfully exploited for
deliberate modification of the complexes, e.g., for coor-
dination of acetylenes or molecular nitrogen.18a
The IR spectrum of complex 9 reveals four bands in
the region of stretching vibrations of metal-coordinated
carbonyl groups, which are shifted to lower frequencies
by 10 cm-1, on average, relative to the corresponding
frequencies for complex 8 due to the electron-donating
effect of the coordinated acetone ligand. The ν(CdO)
band is observed at 1701 cm-1, which is close to the
value observed for other ruthenium acetone complexes.18a
Note that the value is smaller than the frequency typical
for the free ligand appearing at 1710 cm-1, which is
consistent with the decrease in the bonding order upon
coordination.
Figure 4. ORTEP representation (thermal ellipsoids
drawn at the 30% probability level) of the molecular
structure of complex 9.
Table 5. Selected Bond Lengths (Å) and Angles
(deg) for Complex 9
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-C(12)
Ru(1)-O(5)
Ru(1)-O(6)
Ru(1)-O(7)
Ru(2)-C(3)
Ru(2)-C(4)
Ru(2)-C(10)
Ru(2)-C(11)
Ru(2)-C(25)
Ru(2)-C(26)
1.860(4)
1.843(4)
2.124(3)
2.214(3)
2.085(2)
2.116(2)
1.925(4)
1.845(4)
2.546(3)
2.284(3)
2.223(4)
2.199(4)
Ru(2)-C(27)
Ru(2)-O(7)
O(5)-C(5)
2.122(3)
2.174(2)
1.238(5)
1.301(4)
1.365(4)
1.414(5)
1.546(5)
1.546(5)
1.430(5)
1.393(5)
1.517(5)
O(6)-C(10)
O(7)-C(27)
C(10)-C(11)
C(11)-C(12)
C(12)-C(28)
C(25)-C(26)
C(26)-C(27)
C(27)-C(28)
The η4-oxadiene coordination of one of the ligands in
1
9 is strongly supported by the H NMR spectrum. It is
known that signals of the internal olefin protons for Fe-
(CO)3(η4-oxadiene) complexes are slightly shifted to
higher field as compared with the respective uncoordi-
nated ketones (∆δ is 0.5-1.0 ppm). Meanwhile, signals
of the external protons have a significantly larger
upfield shift (∆δ is 3.5-4.0 ppm).19 In complex 9, the
η4-oxadiene system manifests itself as a doublet of
doublets at δ 6.14 and 3.86 ppm (J ) 8.9 Hz). In the 1H
NMR spectrum, signals of protons at the C(28) and
C(29) atoms arise as three doublets of doublets at δ 5.06,
3.38, and 2.93 ppm. The presence of a chiral center at
the C(28) atom results in the diastereotopy and hence
inequivalency of protons at the C(29) atom. The lowest-
field signal is attributed to the sp3-proton at the C(28)
atom, in agreement with the 1H NMR data for isomeric
complexes Ru2(CO)4(η2-PhCOCHdCCOPh)2(µ-η2-η2-Ph-
COCHCHCOPh), in which signals of the protons lie in
C(5)-O(5)-Ru(1)
O(6)-Ru(1)-C(12)
C(10)-O(6)-Ru(1)
O(6)-C(10)-C(11)
136.6(3) C(27)-O(7)-Ru(1)
113.6(2)
84.3(1) C(28)-C(12)-Ru(1) 104.6(2)
110.9(2) O(7)-C(27)-C(28)
121.0(3) C(27)-C(28)-C(12) 102.8(3)
115.5(3)
C(10)-C(11)-C(12) 116.8(3) C(27)-C(26)-C(25) 117.7(3)
C(11)-C(12)-Ru(1) 101.7(2) O(7)-C(27)-C(26) 115.7(3)
O(7)-Ru(1)-C(12) 76.6(1) C(11)-C(12)-C(28) 108.2(3)
interact with the substance, leading to its chemical
modification. Reversible changes occur with the complex
upon dissolution in acetone, which is a weakly coordi-
nating donor ligand. This made it possible to investigate
solutions of complex 8 in more detail.
Upon dissolution of complex 8 in acetone, complex 9
is formed. In contrast to complex 8, complex 9 is well
soluble in hydrocarbons. Upon storage of hydrocarbon
solutions of 9 for 1 day, the dissolved complex loses
acetone, dimerizes, and converts into 8, which precipi-
tates as small crystals. To explore the changes occurring
in the coordination sphere of the ruthenium atoms, we
performed X-ray diffraction analysis of complex 9 (Fig-
ure 4, Table 5). As compared to the molecular structure
of 8, the central Ru2O2 cycle in 9 is cleaved and the
formed vacant coordination site is occupied by an
acetone molecule. Therefore, complex 9 belongs to a
small number of ruthenium complexes in which η1-
the range δ 5.30-5.70 ppm.2c The spin-spin coupling
2
constant for the protons at the C(29) atom is JH-H
)
15.6 Hz, while the protons at C(29) are coupled with
3
the proton at C(28) with JH-H ) 10.4 and 2.8 Hz.
(18) (a) Trimmel, G.; Slugovs, C.; Wiede, P.; Mereiter, K.; Sapunov,
V. N.; Schmid, R.; Kirchner, K. Inorg. Chem. 1997, 36, 1076. (b)
Esteruelas, M. A.; Lahoz, F. J.; Lopez, A. M.; Onate, E.; Oro, L. A.
Organometallics 1994, 13, 1669.
(19) Nesmeyanov, A. N.; Shulpin, G. B.; Rybin, L. V.; Rybinskaya,
M. I.; Gubenko, N. T.; Petrovskii, P. V.; Robas, B. I. Zh. Obshch. Khim.
1974, 44, 2032.

Reaction of Ru3(CO)12
Organometallics, Vol. 24, No. 10, 2005 2287
Table 6. Crystal Data, Data Collection, and Structure Refinement Parameters for 6-9
6
7
8
9
formula
C
40H26O8Ru3‚0.5(C6H14
)
C75H56O11Ru3
1436.41
red prism
0.3 × 0.2 × 0.1
triclinic
P1h
110(2)
10.675(1)
12.942(2)
23.694(3)
88.432(3)
83.478(3)
73.940(4)
3125.1(7)
2
C
76H56O12Ru4
C
41H34O7Ru2‚C3H6O
mol wt
980.90
1565.49
898.90
cryst color, habit
yellow needle
0.5 × 0.2 × 0.1
monoclinic
C2/c
yellow plate
0.20 × 0.15 × 0.05
triclinic
P1h
110(2)
10.496(2)
12.347(2)
12.762(2)
75.860(3)
83.084(3)
76.385(3)
1555.2(4)
1
yellow prism
0.3 × 0.2 × 0.2
triclinic
P1h
110(2)
11.255(1)
14.146(2)
14.174(2)
65.566(2)
80.367(2)
70.567(2)
1936.4(4)
2
cryst dimens, mm3
cryst syst
space group
temperature, K
153(2)
a, Å
14.120(4)
24.452(7)
11.080(3)
b, Å
c, Å
R, deg
â, deg
90.92(2)
γ, deg
V, Å3
3825(2)
4
1.703
12.23
Syntex P21
50
0 e h e 16,
-3 e k e 29,
-13 e l e 13
3512
3368 (0.0503)
2483
0.0367
0.0827
Z
dcalc, g/cm3
1.526
7.79
1.672
10.20
1.542
8.34
µ(Mo KR λ ) 0.71073 Å), cm-1
diffractometer
2θmax, deg
SMART CCD 1000
56
-14 e h e 14,
-17 e k e 17,
-31 e l e 31
30 794
14 876 (0.0532)
7052
0.0597
0.1187
SMART CCD 1000
44
-11 e h e 11,
-12 e k e 13,
-13 e l e 13
9165
3837 (0.0618)
2675
0.0437
0.1227
SMART CCD 1000
60
-15 e h e 15,
-19 e k e 19,
-19 e l e 19
23 459
11 238 (0.0323)
7767
0.0514
0.1225
range h, k, l
reflectns collected
indep reflectns (Rint
)
obsd reflectns (I>2σ(I))
R1 (on F for obsd reflectns)a
wR2 (on F2 for all reflectns)b
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) {∑[w(Fo - Fc )2]/∑w(Fo2)2}1/2
.
Conclusion
several coordination centers. However, such investiga-
tions play a significant role in organometallic and
organic chemistry because they assist with a more
complete description of many chemical processes and
transformations that occur with organic substrates in
the presence of metal catalysts.
According to the data obtained, formation of oxaru-
thenacycles may be regarded as the initial stage of the
reaction of Ru3(CO)12 with DBA. Further, the oxaruth-
enacycle interacts either with other ruthenium atoms,
yielding complex 6, or with another DBA molecule,
yielding dihydropyran cycle and complex 7. Complex 6
is stable and does not undergo any changes in the course
of the reaction (see Experimental Section). The example
of complex 6 clearly demonstrates that the presence of
the second olefin bond in the ligand does not affect its
ability to form an oxaruthenacycle. The vinyl substitu-
ent at the oxaruthenacycle represents simply an ad-
ditional coordination site for metal atoms. In contrast
with complex 6, complex 7 is unstable and undergoes
chemical transformations yielding other complexes.
Therefore, it is impossible to isolate complex 7 with
large yields irrespective of the reaction duration.
In complexes 7 and 8, the presence of two CdC double
bonds in DBA gives rise to the modification of the ligand
due to C-C coupling and migration of the olefin bond.
This leads to formation of the η4-diene (complex 7) or
η4-oxadiene (complex 8) fragments.
The described complexes 6, 7, and 8 do not complete
the thermal reaction of Ru3(CO)12 with DBA. Two more
complexes were isolated and characterized by IR spec-
troscopy (see Experimental Section), and as was men-
tioned above, formation of a compound similar to
complex 5 is assumed. In the thermal reaction with Ru3-
(CO)12, the DBA ligand realizes the most its coordination
abilities as an oxadiene system with an independent
CHdCH substituent and displays peculiarities due to
the presence of two olefin bonds linked in a conjugated
system through the carbonyl group.
Experimental Section
All reactions were carried out under an argon atmosphere
using standard Schlenk techniques. Solvents were dried
according to standard procedures. Column chromatography
was performed with Aldrich silica gel (70-230 mesh). DBA
was prepared by condensation of acetone and benzaldehyde.20
1
The H NMR spectra were recorded on a Bruker AMX-400
spectrometer (400.13 MHz) in solutions of CDCl3, C6D6 with
trace signals of CHCl3 (δ 7.25), and C6HD5 (δ 7.25) as the
internal standards, respectively. The IR spectra in solution
were recorded on a Specord 75-IR spectrometer. The IR spectra
in solid state were recorded on a Specord M82 spectrometer
in Nujol.
Reaction of Ru3(CO)12 with DBA. A mixture of Ru3(CO)12
(320 mg, 0.5 mmol) and 1 (468.5 mg, 2 mmol) was refluxed in
heptane (150 mL) for 4 h. After cooling to room temperature,
the reaction mixture was filtered to separate the precipitate
from solution. The filtrate was chromatographed on a column
with silica gel. Elution with a 1:1 hexane/benzene mixture
afforded complex 7 (25 mg, 3.5%), complex 6 (80 mg, 17.1%),
and two other unidentified compounds with IR spectra for the
first compound (18 mg) (ν(CO)/cm-1, hexane) 2044 s, 1980 s
and for the second compound (trace amount) (ν(CO)/cm-1
,
hexane) 2092 s, 2042 s, 2034 w, 2008 s, 1990 w, 1950 sm, 1940
sm. Crystals of 6 (yellow needles) and 7 (red prisms) suitable
for X-ray diffraction study were grown by slow evaporation of
the hexane solutions. Mp: 198-202 °C (dec) for 6. Anal. Found
for 6 (%): C, 51.26; H, 2.85. Ru3C40H26O8 Calcd (%): C, 51.23;
H, 2.79. Mp: 207-210 °C (dec) for 7. Anal. Found for 7 (%):
C, 62.77; H, 4.22. Ru3C75H56O11 Calcd (%): C, 62.70; H, 4.14.
The precipitate flushed with benzene was composed of small
The large amount of products and their complicated
separation and identification lead to a limited number
of studies of reactions with organic ligands that have
(20) Conard, C. R.; Dolliver, M. A. Org. Synth. Coll. 1943, 2, 167.

2288 Organometallics, Vol. 24, No. 10, 2005
Osintseva et al.
crystals of 8 (48 mg, 8.2%). Crystals of 8 (yellow plates) suitable
for X-ray diffraction study were obtained by recrystallization
from benzene. Mp: 220-225 °C (dec). Anal. Found (%): C,
58.25; H, 3.58. Ru2C38H28O6 Calcd (%): C, 58.28; H, 3.70.
Thermal Transformations of Complex 6. A mixture of
complex 6 (12.5 mg, 0.03 mmol) and 1 (17 mg, 0,075 mmol) in
heptane (20 mL) was refluxed for 4 h. No changes in IR
spectrum were detected.
X-ray Diffraction Study. Details of crystal data, data
collection, and structure refinement of compounds 6-9 are
presented in Table 6. The structures were solved by direct
methods and refined by the full-matrix least-squares technique
against F2 with anisotropic displacement parameters for non-
hydrogen atoms. In the crystal structure of 6, three additional
peaks were located around an inversion center and 2-fold axis
and proposed as a disordered solvate molecule of n-hexane with
half-occupancy. In the crystal structure of 9, a solvate molecule
of acetone is present. Hydrogen atoms in complexes 6 and 9
were located from the Fourier synthesis and refined in the
isotropic approximation; hydrogen atoms in the disordered
solvate molecule of n-hexane in structure 6 are not defined.
All hydrogen atoms in structures 7 and 8 were placed in
calculated positions and refined in the riding model ap-
proximation. The SHELXTL-9721 program package was used
throughout the calculations.
Thermal Transformations of Complex 7. (a) A solution
of complex 7 (53 mg, 0.037 mmol) in heptane was refluxed and
monitored by IR spectroscopy. No spectral changes were
detected after 3 h. (b) A mixture of complex 7 (53 mg, 0.037
mmol) and 1 (17 mg, 0.075 mmol) was refluxed in heptane
(50 mL) for 2 h 30 min. The reaction was stopped when the
IR signals of complex 7 disappeared. The solution contained
a mixture of complexes with main IR signals (ν(CO)/cm-1
,
hexane) 2044 s, 1980 s and precipitate. The reaction mixture
was cooled to room temperature, and the precipitate was
separated by filtering and flushed with benzene to afford small
yellow crystals of complex 8 (6 mg, 13.8%). (c) A mixture of
complex 7 (30 mg, 0.02 mmol) and 4-phenylbut-3-en-2-one (1a)
(6 mg, 0.04 mmol) was refluxed in heptane (50 mL) for 2 h 30
min. The reaction was stopped when the IR signals of complex
7 disappeared. The solution contained a mixture of complexes
and precipitate. The reaction mixture was cooled to room
temperature, and the trace amount of precipitate was sepa-
rated by filtering and flushed with benzene to afford small
yellow crystals of complex 8.
Interaction of 8 with Acetone. Complex 8 (16 mg, 0.01
mmol) in acetone (30 mL) was boiled until complete dissolu-
tion. The reaction mixture was cooled to room temperature
and filtered. Yellow-gray crystals of 9 (12 mg, 69.8%) grew over
the surface of the solution. Mp: 230-232 °C (dec). Anal. Found
(%): C, 58.80; H, 4.49. Ru2C41H34O7 Calcd (%): C, 58.57; H,
4.08.
Acknowledgment. We thank Dr. E. S. Shubina and
co-workers for their technical assistance in measure-
ments of IR spectra and fruitful discussion. The authors
are also indebted to the Russian Foundation for Basic
Research (Grant Nos. 04-03-32371 and 03-03-32499) for
financial support.
Supporting Information Available: CIF files for the
structures of 6-9. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM0489958
(21) Sheldrick, G. M. SHELXTL-97, V5.10, Program for crystal
structure refinement; Bruker AXS Inc.: Madison, WI 53719, 1997.