Isolation and characterization of new mono- And polynuclear complexes formed in the thermal reaction of Ru3(CO)12 with l-(4-Tolyl)-3phenylaminoprop-2-en-1-one

Article abstract of DOI:10.1021/om901109q

Thermal reaction of Ru₃(CO)₁₂ with l-(4-tolyl)-3-phenylaminoprop-2-en-l-one (1) proceeds in heptane with the formation of a number of new chelate mononuclear complexes, cis-Ru(CO) ₂[O=C(Tol)CH=CHNPh]₂ (2), cis-Ru(CO)₂[O=C(Tol) CH=CNHPh][O=C(Tol)CH=CH-NPh] (3), and cis-Ru(CO)₂[O=C(Tol)CH=CNHPh] [O=C(Tol)CH=CHNPh] (4), isolated as the main products, along with minor amounts of the polynuclear clusters Ru₅(CO)₁₄(μ₂-H) ₂(μ₄-η¹:η¹:η: ²η²:CCHC(Tol)=O) (5), Ru₄(CO) ₁₁(μ₂-H)₂(μ₄- η²:η²:η¹:η²- NPhCCHC(Tol)=O) (6), and Ru₄(CO)₁₂(μ₄- η¹:-η ¹:η¹: η¹:- NPhCHCC(Tol)=O) (7). Complexes of both series were characterized by a combination of spectroscopic IR and multinuclear NMR data and by single-crystal X-ray diffraction study, which revealed the existence of different types of metal-to-ligand bonding in these species. Chelated six-membered azaoxaruthenacycles are formed in 2-4 via N-H activation, while unexpected fivemembered oxaruthenacycles are formed in 3-6 due to C_β-H activation. Among the products of the reaction, the butterfly cluster 7, with open-chain coordination of the ligand formed as a result of N-H and C _α-H bond activation, is also isolated. Complex 5 proved to be the only reaction product in which the deamination of amino vinyl ketone 1 is observed. Possible pathways for the formation of the complexes obtained are discussed.

Full text of DOI:10.1021/om901109q

1012 Organometallics 2010, 29, 1012–1025
DOI: 10.1021/om901109q
Isolation and Characterization of New Mono- and Polynuclear Complexes
Formed in the Thermal Reaction of Ru3(CO)12 with 1-(4-Tolyl)-3-
phenylaminoprop-2-en-1-one
Svetlana V. Osintseva, Fedor M. Dolgushin,* Nikolay A. Shtel’tser, Pavel V. Petrovskii,
Alexander S. Peregudov, Arkadii Z. Kreindlin, and Mikhail Yu. Antipin
A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilov Street,
119991 Moscow, Russian Federation
Received December 23, 2009
Thermal reaction of Ru3(CO)12 with 1-(4-tolyl)-3-phenylaminoprop-2-en-1-one (1) proceeds in
heptane with the formation of a number of new chelate mononuclear complexes, cis-Ru(CO)2[OdC-
(Tol)CHdCHNPh]2 (2), cis-Ru(CO)2[OdC(Tol)CHdCNHPh][OdC(Tol)CHdCH-NPh] (3), and
cis-Ru(CO)2[OdC(Tol)CHdCNHPh][OdC(Tol)CHdCHNPh] (4), isolated as the main prod-
ucts, along with minor amounts of the polynuclear clusters Ru5(CO)14(μ2-H)2(μ4-η1:η1:η2:η2-
CCHC(Tol)dO) (5), Ru4(CO)11(μ2-H)2(μ4-η2:η2:η1:η2-NPhCCHC(Tol)dO) (6), and Ru4(CO)12-
(μ4-η1:η1:η1:η1-NPhCHCC(Tol)dO) (7). Complexes of both series were characterized by a combina-
tion of spectroscopic IR and multinuclear NMR data and by single-crystal X-ray diffraction study,
which revealed the existence of different types of metal-to-ligand bonding in these species. Chelated
six-membered azaoxaruthenacycles are formed in 2-4 via N-H activation, while unexpected five-
membered oxaruthenacycles are formed in 3-6 due to Cβ-H activation. Among the products of the
reaction, the butterfly cluster 7, with open-chain coordination of the ligand formed as a result of
N-H and CR-H bond activation, is also isolated. Complex 5 proved to be the only reaction product
in which the deamination of amino vinyl ketone 1 is observed. Possible pathways for the formation of
the complexes obtained are discussed.
Introduction
known from organic chemistry that β-amino vinyl ketones
have three nucleophilic and two electrophilic centers capable
of interacting with various reagents. Nucleophiles attack
amino vinyl ketone at the carbonyl carbon or at the
β-carbon. Electrophiles attack the carbonyl oxygen, nitrogen,
and the R-carbon.5a,b Due to the rich and complex chemistry of
β-amino vinyl ketones, they can be used to obtain substances
often unobtainable by other synthetic routes.1
In organometallic reactions with the participation of the
amino vinyl ketones, the oxygen atom serves as a site for
strong coordination, whereas the nitrogen atom is likely to
be less strongly bound and, hence, may lead to ligand
hemilability and as a result to interesting catalytic behavior.6
To gain a better understanding of the nature of the catalytic
systems and to investigate the factors that affect the catalysis,
it was desirable to isolate and characterize as many products
of the reaction as possible.
The interest in the chemistry of β-amino vinyl ketones is
caused by their extensive applications. Amino vinyl ketones
and their metal complexes are frequently used as reagents,
intermediates, or catalysts in chemical synthesis of drugs,
polymers, and dyes.1,2 The polar character of amino vinyl
ketones, electronic interactions between substituents, and
the olefin bond are responsible for their nonlinear optical
properties.3a Complexes of amino vinyl ketone ligands with
metals are used for the deposition of metal coatings,3b,c and
they possess liquid-crystalline properties.3d,e
Amino vinyl ketones, the so-called “push-pull” olefins,
are highly reactive organic compounds with an electron
donor group on one side and a strong electron acceptor
group on the other side of the ethylene double bond.1,4 It is
*To whom correspondence should be addressed. Fax: þ7(499)1355085.
E-mail: fedya@xrlab.ineos.ac.ru.
(1) Greenhill, J. V. Chem. Soc. Rev. 1977, 6, 277.
(2) Fujita, H.; T. Uchida, T.; Irie, R.; Katsuki, T. Chem. Lett. 2007,
36, 1092.
Complexes with metals are obtained as a result of the
reactions of neutral organic compounds or their salts. As the
mechanisms of these reactions are various, the formed com-
plexes can adopt different types of coordination.7 The most
(3) (a) M. Kascheres, C. M. J. Braz. Chem. Soc. 2003, 14, 945.
(b) Chou, T.-Y.; Lai, Y.-H.; Chen, Y.-L.; Chi, Y.; Prasad, K. R.; Carty, A.
J.; Peng, S.-M.; Lee, G.-H. Chem. Vap. Deposition 2004, 10, 149. (c) Baxter,
D. V.; Caulton, K. G.; Chiang, W.-C.; Chisholm, M. H.; DiStasi, V. F.;
Dutremez, S. G.; Folting, K. Polyhedron 2001, 20, 2589. (d) Binnemans, K.;
(5) (a) Fendler, J. H.; Fendler, E. J.; Griffin, C. E. J. Org. Chem. 1969,
34, 689. (b) Murahashi, S.-I.; Mitsue, Y.; Tsumiyama, T. Bull. Chem. Soc.
Jpn. 1987, 60, 3285.
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B. W.; White, A. H. J. Chem. Soc., Dalton Trans. 1998, 255.
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Gorller-Walrand, C. Chem. Rev. 2002, 102, 2303. (e) Turanova, O. A.;
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ꢀ
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r
pubs.acs.org/Organometallics
Published on Web 01/21/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 4, 2010 1013
common organometallic compounds of β-amino vinyl
ketones are the six-membered metallochelates (six-membered
azaoxametallacycles, the so-called N-O coordination). Such
complexes are obtained with both transition and non-transi-
tion metals. The ligand mainly forms delocalized chelate ring
with some contribution of the imine-enol structure.3c,8 Salts
of metals and amino vinyl ketonates of alkaline metals are
often used to prepare such complexes.
Upon an interaction of neutral organic molecules in addi-
tion to N-O coordination, the formation of complexes with
monodentate coordination through the oxygen atom can
also be observed.6,8 The ligands in such complexes exist
mainly in the keto-enamine form. An unusual mixed com-
plex of zirconium [(η5-Cp*){CH3C(O)CHC(NHR)CH3}-
{CH3C(O)CHC(NR)CH3}ZrCl2], where R = p-CF3Ph, has
been prepared by the reaction of 4-amino(R)-but-3-en-2-one
and lithium 4-amino(R)-but-3-en-2-onate with Cp*ZrCl3.9
In this complex the first ligand is a monodentate one,
coordinated through the oxygen atom, while the second
ligand forms a six-membered metallochelate.
A number of metal complexes with an amino vinyl ketone
fragment as a ligand have been obtained by indirect chemical
reactions. For example, the complexes of rhenium with six-
membered N-O cycles are obtained by the combination of
enolates of rhenium and nitriles.10a,b Complexes obtained
from nitrates of uranium with acetylacetone in the presence
of primary and secondary amines result in keto-amine
products, coordinated with an atom of uranium through
the oxygen atom.11a,b
There are only two publications regarding the reactions of
the transition metal carbonyls with β-amino vinyl ketones. It
was shown that β-amino vinyl ketones do not react with iron
carbonyls because of a substantial difference in energy of the
lowest unoccupied π*-orbital of the olefin and 3d,4s-orbitals
of iron.12 However, several salicylidenimines, which can also
be viewed as amino vinyl ketones in the imine-enol tauto-
meric form, do react with metal carbonyls.13 In particular,
thermal reaction of Ru3(CO)12 with N-phenylsalicylideni-
mine (Ph-SaEn) results in product with low yield, which was
assumed to be cis-Ru(Ph-SaEn)(CO)2 on the basis of spectral
data.
morpholinoprop-2-en-1-one, with Ru3(CO)12.14 This reac-
tion was accompanied by ligand deamination, so that vinyl
ketonic and morpholine fragments of the amino vinyl ketone
are observed in different products of the reaction. This is in
agreement with the behavior of tertiary amines substituted
with alkyl and aryl groups in reactions with metal carbonyls.15a-d
Similar processes were also described for acetylamines.15e,f
Unlike tertiary amines, deamination of the secondary amines
is not as common.15b,16 Besides, there is an additional center
of coordination (N-H bond), which provides a broader
variety of types of coordination with transition metals.
Therefore, it is interesting to study the behavior of amino
vinyl ketones bearing a secondary amino group in reaction
with metal carbonyls.
In this paper we present the results of research on the
thermal reaction between Ru3(CO)12 and amino vinyl ketone
1-(4-tolyl)-3-phenylaminoprop-2-en-1-one (1). Preliminary
results of a part of this work have been published as a short
communication.17 This work is the continuation of our
systematical studies on the reactivity of functionally substi-
tuted olefins in reactions with Ru3(CO)12 (see ref 18 and
references therein).
Results and Discussion
Reaction of Ru3(CO)12 with 1 was carried out in boiling
heptane for 5 h. The course of the reaction was monitored by
the changes in IR spectra in the region of stretching vibra-
tions of the metalcarbonyl groups. After slow cooling, the
reaction mixture was separated into a solution and a pre-
cipitate.
From the solution, 10 mg of unreacted Ru3(CO)12 (5.6%
yield), hydride tetrahedral clusters H4Ru4(CO)12 (30 mg,
15.4% yield) and H2Ru4(CO)13 (14 mg, 6.9% yield), and
complexes cis-Ru(CO)2[OdC(Tol)CHdCHNPh]2 (2) (49.6mg,
29.9% yield), cis-Ru(CO)2[OdC(Tol)CHdC-NHPh][OdC-
(Tol)CHdCHNPh] (3) (16.5 mg, 10.0% yield), cis-Ru(CO)2-
[OdC(Tol)CHdCNHPh][OdC(Tol)CHdCHNPh] (4) (6.6 mg,
4.0% yield), Ru5(CO)14(μ2-H)2(μ4-η1:η1:η2:η2-CCHC(Tol)dO)
(5) (13.5 mg, 4.9% yield), Ru4(CO)11(μ2-H)2(μ4-η2:η2:η1:η2-
NPhCCHC(Tol)dO) (6) (10.2 mg, 4.2% yield), and Ru4-
(CO)12(μ4-η1:η1:η1:η1-NPhCHCC(Tol)dO) (7) (10.0 mg, 3.8%
yield) were isolated by column chromatography on silica gel
(Scheme 1). All stages of separation and purification have been
monitored by IR spectroscopy.
Recently, we have studied the reaction of amino vinyl
ketone bearing a tertiary amino group, 1-phenyl-2-methyl-3-
(8) Kakaliou, L.; Scanlon, W. J.; Qian, B.; Baek, S. W.; Smith, M. R.;
Motry, D. H. Inorg. Chem. 1999, 38, 5964.
(9) Kim, J.; Hwang, J.-W.; Kim, Y.; Lee, M. H.; Han, Y.; Do, Y.
Formation of the hydride clusters was also observed in
other reactions of Ru3(CO)12 and was explained by the
presence of traces of water at the reaction mixture.19 How-
ever, in those reactions hydride clusters are formed at the
first stage in a small amount, which is kept unchanged upon
the continuation of the reaction. This testifies to the com-
plete dehydration of the reaction mixture at the first stages of
reaction.20 At the same time, in the reaction of Ru3(CO)12
J. Organomet. Chem. 2001, 620, 1.
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Heathcock, C. H. Organometallics 1990, 9, 453.
(11) (a) Rodgers, A. L.; Nassimbeni, L. R.; Pauptit, R. A.; Orpen, G.;
Haigh, J. M. Acta Crystallogr., Sect. B 1977, 33, 3110. (b) Haigh, J. M.;
Nassimbeni, L. R.; Pauptit, R. A.; Rodgers, A. L.; Sheldrick, G. M. Acta
Crystallogr., Sect. B 1976, 32, 1398.
(12) Rybin, L. V.; Rybinskaya, M. I. Russ. Chem. Rev. 1993, 62, 637.
(13) Calderazzo, F.; Floriani, C.; Henzi, R.; Eplattenier, F. L.
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Trans. 1978, 1201. (b) Aime, S.; Gobetto, R.; Padovan, F.; Botta, M.;
Rosenberg, E.; Gellert, R. W. Organometallics 1987, 2074.
(17) Shtel’tser, N. A.; Rybin, L. V.; Rybinskaya, M. I.; Osintseva, S. V.;
Petrovskii, P. V.; Dolgushin, F. M. Russ. Chem. Bull. 2002, 51, 1771.
(18) Osintseva, S. V.; Dolgushin, F. M.; Shtel’tser, N. A.; Petrovskii,
P. V.; Kreindlin, A. Z.; Rybin, L. V.; Antipin, M. Yu. Organometallics
2005, 24, 2279.
(19) Eady, C. R.; Johnson, B. F. G.; Lewis, J. J. Chem. Soc., Dalton
Trans. 1977, 838.
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N. A.; Kreindlin, A. Z.; Rybin, L. V.; Rybinskaya, M. I. Russ. Chem.
Bull 2002, 51, 1754.
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A. Z.; Dolgushin, F. M. Russ. Chem. Bull., Int. Ed. 2006, 55, 2143.
(15) (a) Adams, R. D.; Kim, H. S.; Wang, S. J. Am. Chem. Soc. 1985,
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1014 Organometallics, Vol. 29, No. 4, 2010
Osintseva et al.
Scheme 1
with 1, a considerable amount of hydride tetrahedral clusters
H4Ru4(CO)12 and H2Ru4(CO)13 is formed, and their
amounts continue to increases in the course of the reaction.
In our opinion, the traces of water cannot serve as a source of
protons because water is completely consumed at the first
stage of the reaction; amino vinyl ketone 1, which is depro-
tonated during the formation of complexes 2-7, acts as a
proton donor.
Upon formation of an oxaruthenacycle in reactions of
Ru3(CO)12 with oxadienes, the ligand loses a hydrogen atom,
while an excess amount of the ligand acts as a hydrogen
acceptor and, thus, undergoes reduction to the correspond-
ing saturated ketone.20 However, in the reaction of Ru3-
(CO)12 with 1, products of reduction of amino vinyl ketone
are not observed. Thus, in this reaction, Ru3(CO)12 acts as
the hydrogen acceptor and is reduced to the hydride clusters
H4Ru4(CO)12 and H2Ru4(CO)13.21 This assumption is sup-
ported by the fact that in the absence of Ru3(CO)12 the
hydride tetrahedral clusters do not react with 1 (vide infra),
because of the lack of proton acceptors in the reaction
mixture.
assume that the precipitate consists of a salt-like substance
with the [HRu6(CO)18]- anion. Identification of a cation by
NMR spectroscopy appeared to be impossible, and our
attempts to grow single crystals suitable for X-ray analysis
were unsuccessful.
Complexes 2-7 have been characterized by IR and 1H and
13C NMR spectroscopy (Table 1), and their molecular
structures have been unambiguously determined by single-
crystal X-ray diffraction study.
In the reaction of 1 with Ru3(CO)12, the main products are
mononuclear complexes of identical composition (2-4), in
which the ruthenium atom is chelated by two molecules of
the ligand. In addition, in each complex there are two
carbonyl ligands at cis-position in the octahedral environ-
ment of the ruthenium atom. The complex 2, obtained with
the maximum yield, consists of two six-membered azaoxar-
uthenacycles (N-O coordination). Azaoxaruthenacycles are
formed via oxidative addition of the ruthenium atom to the
N-H bond with simultaneous coordination with one elec-
tron lone pair of the oxygen atom.
In spite of the fact that numerous complexes of various
metals with two azaoxaruthenacycles are reported in the
literature, only a few complexes with carbonyl ligands have
been described, namely, cis-[Ru(hpNP)2(CO)2][BF4], where
hpNP = 2-(2-hydroxyphenyl)-1,8-naphthyridine,23 cis-Ru-
(salalen)(CO)2, where salalen = N,N0-ethylenbis(salicyliden-
imine),2 and an osmium complex with one carbonyl ligand.24
The ruthenium complexes with two phosphine ligands in
axial positions, (acen)Ru(PPh3)2, where acen = N,N0-ethyl-
enbis(trifluoroacetoneimine),25 and with three ketoimine
ligands in a coordination environment of the ruthenium atom,
From 20 mg of the precipitate obtained in the reaction, we
have separated an unidentified substance in trace amounts by
chromatography. The IR spectrum of this substance shows
signals in the region of stretching vibrations of metalcarbonyl
groups: ν(CO), cm-1 (CH2Cl2) 2040w, 2010vs, 1982w, 1950w.
1
In the H NMR spectrum of its solution in CDCl3 we have
registered a single peak of low intensity at δ 16.46 ppm.
Complexes with similar spectra have been separated from
the reaction of Ru3(CO)12 with senecialdimine (CH3)2Cd
CHCHdNR (R = i-Pr, t-Bu)22 and have been characterized
as salts of [HRu6(CO)18]- with an organic cation obtained as a
result of ligand transformation. The data obtained allow us to
(23) Patra, S. K.; Majumdar, M.; Bera, J. K. J. Organomet. Chem.
2006, 691, 4779.
(21) Bruce, M. I.; Goodall, B. L.; Gordon, F.; Stone, A. J. Organo-
met. Chem. 1973, 343.
(22) Mul, W. P.; Elsevier, C. J.; Vuurman, M. A.; Smeets, W. J. J.;
(24) Collins, T. J.; Coots, R. J.; Furutani, T. T.; Keech, J. T.; Peake,
G. T.; Santarsiero, B. D. J. Am. Chem. Soc. 1986, 108, 5333.
(25) Serron, S. A.; Haar, C. M.; Nolan, S. P.; Brammer, L. Organo-
metallics 1997, 16, 5120.
Spek, A. L.; de Boer, J. L. J. Organomet. Chem. 1997, 532, 89.

Article
Organometallics, Vol. 29, No. 4, 2010 1015
Table 1. IR and NMR Spectra for 1-7
NMR
com-
pound
IR ν(CO), cm-1
(hexane)
δ 1H, ppm J, Hz
δ 13C, ppm
1a
1638 w, 1603 w,
1592 w
2.40 (s, 3H, Me); 6.09 (d, 1H, CHdCH-NH, 3JH-H
=
8.0); 7.05 (d, 2H, Tol, 3JH-H = 8.8); 7.22-7.37 (m,
5H, Ph); 7.48 (dd, 1H, CHdCH-NH, 3JH-H = 8.0,
12.4); 7.84 (d, 2H, Tol, 3JH-H = 8.8); 12.11 (br d,
1H, NH, 3JH-H = 12.4)
1b
2.13 (s, 3H, Me); 5.85 (d, 1H, CHdCH-NH, 3JH-H
=
20.94 (Me); 93.46 (CHdCH-N); 115.82; 122.80;
127.88; 128.81; 129.31 (CH, Ar); 137.28 (C-N);
140.48, 141.39 (C, Ar), 143.59 (CHdCH-N),
190.02 (CdO)
7.7); 6.60 (d, 2H, o-Ph, 3JH-H = 7.8); 6.80 (t, 1H, p-
Ph, JH-H = 7.3); 6.95 (dd, 1H, CHdCH-NH,
=
3
3JH-H = 11.4, 7.7); 6.99 (dd, 2H, m-Ph, 3JH-H
7.3, 7.8); 7.03 (d, 2H, Tol, 3JH-H = 8.0); 8.01(d, 2H,
=
Tol, 3JH-H = 8.0); 12.51 (br d, 1H, NH, 3JH-H
11.4)
2a
2046 s, 1980 s
2.34 (s, 3H, 2Me); 5.76 (d, 1H, CHdCH-N, 3JH-H
=
7.0); 7.15 (d, 2H, Tol, 3JH-H = 8.0); 7.25-7.32 (m,
5H, Ph); 7.42 (d, 1H, CHdCH-N, JH-H = 7.0);
3
7.82 (d, 2H, Tol, 3JH-H = 8.0)
2.12 (s, 3H, Me); 5.87 (d, H, CHdCH-N, JH-H
2b
=
6.8); 7.37 (d, 1H, CHdCH-N, 3JH-H = 6.8); 6.99 (t,
1H, p-Ph, 3JH-H = 7.4); 7.03 (d, 2H, Tol, 3JH-H
21.30 (Me); 92,30 (CHdC); 124.21, 125.82, 127.62,
128.23, 129.32 (CH, Ar); 137.18, 140.15, 160.09 (C,
Ar); 159.21 (CHdC-N); 174.58 (CdO); 198.33 (Ru-
CO)
3
=
8.1); 7.14 (dd, 1H, m-Ph, 3JH-H = 8.0, 7.4); 7,45 (d,
=
2H, o-Ph, 3JH-H = 8.0); 8.05 (d, 2H, Tol, 3JH-H
8.1)
3a
3b
2034 vs, 1976 sh,
1960 vs
2.31 (s, 3H, Me); 2.33 (s, 3H, Me); 5.70 (d, 1H,
CHdCH, JH-H = 6.5); 6.55 (s, 1H, HCdCH);
3
7.08-7.75 (m, 20H, 2Ph, 2Tol, CHdCH-N, NH)
2.01 (s, 3H, Me); 2.09 (s, 3H, Me); 5.87 (d, 1H,
22.79, 31.71 (Me); 92.87, 103.00 (CHdC); 123.53,
125.08, 127.28, 128.09, 128.11, 128.32, 128.73,
128.87, 129.06, 129.17 (CH, Ar); 134.54; 137.77,
139.52, 141.30, 159.11, 159.47, (C, Ar); 159.61
(CHdC-N); 174.81, 196.23 (CdO); 197.35, 201.06
(Ru-CO), 218.21 (CdRu).
3
CHdCH-N, JH-H = 6.7); 6.90 (m, 2H, CdCH,
p-Ph); 6.99-7.66 (m, 17H, o-Ph, m-Ph, Tol, p-Ph,
CHdCH-N, NH); 8.00 (d, 2H, Tol, 3JH-H = 8.1)
4a
2042 vs, 1974 sh,
1960 vs
2.33 (s, 3H, Me); 2.40 (s, 3H, Me); 5.68 (d, 1H,
CHdCH-N, JH-H = 7.5); 5.88 (s, 1H, CdCH);
3
3
6.69 (d, 2H, Tol, JH-H = 7.3); 6.90 (d, 2H, Tol,
3JH-H = 7.5); 7.23-7.30 (m, 10H, 2Ph); 7.34 (d,
1H, CHdCH-N, JH-H = 6.6); 7.48 (s, 1H, NH);
3
3
7.63 (d, 2H, Tol, JH-H = 7.3); 7.90 (d, 2H, Tol,
3JH-H = 7.5)
2.19 (s, 3H, Me); 2.02 (s, 3H, Me); 5.94 (d, 1H,
4b
19.20, 30.66 (Me); 91.78, 102.68, (CHdC); 124.49,
124.90, 125.11, 128.23, 128.30, 128.87, 128.92,
130.54, 133.06, 134.37 (CH, Ar); 136.21, 137.78,
140.03, 141.30, 167.28, 171.97 (C, Ar); 159.84
(CHdC-N); 177.24, 195.50 (CdO); 194.49, 202.43
(Ru-CO); 217.70 (CdRu)
3
CHdCH-N, JH-H = 7.3); 6.25 (s, 1H, CHdC);
6.55 (d, 2H, o-Ph, 3JH-H = 6.4); 6.88 (d, 2H, Tol,
3JH-H = 7,3); 6.97-7.08 (m, 8H, Ph); 7.16 (d, 2H,
Tol, JH-H = 7.8); 7.31 (br s, 1H, NH), 7.36 (d,
3
3
1H, CHdCH-N, JH-H = 7.3); 7.86 (d, 2H, Tol,
3JH-H = 7.3); 8.27 (d, 2H, Tol, 3JH-H = 7.8)
-27.86 (d, 1H, Ru-H, 2JH-H = 1.9); -21.08 (d, 1H,
Ru-H, 2JH-H = 1.9); 1.88 (s, 3H, Me); 5.49 (s, 1H,
5b
6b
7b
2098 w, 2070 s,
2062 s,
2048 s, 2030 m,
2016 m, 2004 w,
1988 w
2086 m, 2054 s,
2032 s, 2018 m,
2010 m, 2004 w,
1984 m, 1976 w
21.17 (Me); 65.28 (CHdC-Ru); 128.86, 128.99 (CH,
Ar); 129.76, 145.13 (C, Ar); 184.74 188.96, 191.83,
194.49, 195.62, 197.53, 199.18 (Ru-CO); 214.41
(CdO); 323.95 (CHdC-Ru)
3
CdCH); 6.69 (d, 2H, Tol, JH-H = 8.3), 7.62 (d,
2H, Tol, 3JH-H = 8.3)
-14.44 (d, 1H, Ru-H, 2JH-H = 2.3); -14.02 (d, 1H,
Ru-H, 2JH-H = 2.3); 1.86 (s, 3H, Me); 5.04 (s, 1H,
CdC-H); 6.58 (t, 1H, p-Ph, 3JH-H = 7.2); 6.72 (d,
2H, Tol, 3JH-H = 8.1); 6.82-7.11 (m, 4H, o-Ph, m-
Ph); 7.60 (d, 2H, Tol, 3JH-H = 8.1)
21.27 (Me); 57.23 (CdCH); 121.40, 125.27, 129.02,
129.40 130.05 (CH, Ar); 130.44, 130.53, 145.71 (C,
Ar); 162.24 (CHdC-Ru); 181.74, 186.79, 189.83,
191.75, 194.44, 199.04, 199.85 (Ru-CO); 208.51
(CdO)
20.98 (Me); 121.44, 126.88, 127.33, 129.40,
129.62(CH, Ar); 135.59, 141.74, 155.43 (C, Ar);
188.02, 188.61 (Ru-CO); 196.23 (CdCH-N);
199.20 (CdO); 202.89, 203.26, 204.68, 205.75 (Ru-
CO); 223.92 (CdRu)
2090 m, 2060 s,
2030 s, 2012 m,
2002 w, 1968 w
1.93 (s, 3H, Me); 6.70 (d, 2H, o-Ph, 3JH-H = 7.7); 6.83
3
(t, 1H, p-Ph, JH-H = 7.0); 6.91-6.98 (m, 4H, m-
Ph, Tol); 7.43 (d, 2H, Tol, 3JH-H = 8.1); 9.90 (s, 1H,
CH = N)
a 1H NMR in CDCl3. b 1H and 13C NMR in C6D6.
[Ru(OC(CF3)dCHC(CF3)dNMe)3],3b have been also de-
scribed. The above-mentioned complexes were obtained from
ruthenium chlorides and ketoiminates. Only one complex,
namely, cis-Ru(Ph-SaEn)(CO)2, was obtained in a thermal
reaction of Ru3(CO)12 with N-phenylsalicylidenimine.13
In complexes 3 and 4, one of the ligands chelates the ruthe-
nium atom, forming a six-membered azaoxaruthenacycle,
similar to that observed in 2. The second ligand forms a five-
membered oxaruthenacycle, which is unusual for amino
vinyl ketones. These five-membered chelate oxaruthena-
cycles are formed via oxidative addition of the ruthenium
atom to the Cβ-H bond with simultaneous coordination of
the keto-oxygen atom. Complexes 3 and 4 are isomers that
are different in the spatial arrangement of the chelate cycles.

1016 Organometallics, Vol. 29, No. 4, 2010
Osintseva et al.
Figure 1. ORTEP drawing of the molecular structure of com-
plex 2 with thermal ellipsoids at the 30% probability level
(hydrogen atoms of the phenyl and tolyl substituents have been
omitted for clarity).
Figure 2. ORTEP drawing of one of two independent mole-
cules of complex 3 with thermal ellipsoids at the 30% probability
level (hydrogen atoms of the phenyl and tolyl substituents have
been omitted for clarity).
˚
Table 2. Selected Bond Lengths (A) and Angles (deg) for
Complex 2
follows that the coordination of the transition metal atom to
the Cβ-H bond of amino vinyl ketones is unusual.
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-O(3)
Ru(1)-O(4)
Ru(1)-N(1)
Ru(1)-N(2)
O(3)-C(3)
C(3)-C(4)
1.857(3)
1.866(4)
2.051(2)
2.063(2)
2.084(2)
2.079(2)
1.284(3)
1.375(4)
C(4)-C(5)
1.403(4)
1.299(4)
1.428(3)
1.280(3)
1.382(4)
1.397(5)
1.286(4)
1.426(4)
N(1)-C(5)
N(1)-C(13)
O(4)-C(19)
C(19)-C(20)
C(20)-C(21)
N(2)-C(21)
N(2)-C(29)
1. Structure of Complexes 2-4. The structure of complex 2
has been previously determined at room temperature.17 Since
all other structures described in this work have been determined
at 100 K, we repeated the structure determination of complex 2
(Figure 1, Table 2) at 100 K for a more proper comparison of
the geometrical parameters of the isomeric complexes 2-4. An
asymmetric unit cell of crystal 3 contains two independent
molecules that differ by the orientation of the phenyl fragments
only (Figure 2, Table 3). Complex 4 forms a cocrystal with the
molecule of the initial amino vinyl ketone 1 (Figure 3, Table 4).
This fact allowed us to track the changes that occur in the
molecule of amino vinyl ketone upon the formation of the
chelate cycles of two types: five-membered oxaruthenacycle
and six-membered azaoxaruthenacycle. In the crystal “4 þ 1”,
the molecule of amino vinyl ketone 1 is in cis-form, which is
C(1)-Ru(1)-O(3)
C(2)-Ru(1)-O(4)
N(1)-Ru(1)-N(2)
O(3)-Ru(1)-N(1)
O(4)-Ru(1)-N(2)
C(3)-O(3)-Ru(1)
O(3)-C(3)-C(4)
C(3)-C(4)-C(5)
N(1)-C(5)-C(4)
171.9(1)
174.3(1)
170.71(9)
90.60(8)
90.54(9)
126.8(2)
124.3(3)
126.7(3)
129.2(3)
C(5)-N(1)-Ru(1)
C(5)-N(1)-C(13)
C(19)-O(4)-Ru(1)
O(4)-C(19)-C(20)
C(19)-C(20)-C(21)
N(2)-C(21)-C(20)
C(21)-N(2)-Ru(1)
C(21)-N(2)-C(29)
121.1(2)
117.0(2)
125.6(2)
125.5(3)
126.4(3)
128.7(3)
121.6(2)
118.1(3)
stabilized by the intramolecular H-bond (N(3) O(5)
3 3 3
In both complexes, one of the metalcarbonyl groups is
positioned trans to the oxygen atom of the five-membered
oxaruthenacycle. The second metalcarbonyl group is posi-
tioned either trans to the oxygen atom (complex 3) or trans to
the nitrogen atom (complex 4) of the six-membered cycle.
Thus, either the nitrogen atom (complex 3) or the oxygen
atom (complex 4) of the six-membered metallacycle is posi-
tioned trans to the σ-bound carbon atom of the five-mem-
bered cycle.
Several complexes of transition metals containing oxame-
tallacycles with amino substituents in β-position have been
described in the literature. All these complexes have been
synthesized as a result of coupling of organic fragments on
transition metal centers rather than directly from amino
vinyl ketones. For example, a cobalt five-membered cycle
was obtained in the reaction of an isocyanidecobalt complex
with an R-diazocarbonyl compound,26a and a palladium
five-membered cycle was obtained in the reaction of an
enolate palladium complex with isocyanide.26b Therefore it
˚
2.635(10) A, N(3)-H(3A) O(5) 133°). The bond lengths in
3 3 3
the central fragment of the molecule are localized to a con-
siderable extent according to the type N-CdC-CdO (keto-
˚
enamine), except for the bond C(35)-O(5) of 1.283(10) A,
which is somewhat longer in comparison to the standard value
of 1.22 A for the CdO double bond in ketones.27 This can be
˚
explained by the fact that the O(5) atom participates in forma-
tion of two N-H O bonds simultaneously: the previously
3 3 3
mentioned intramolecular bond as well as the intermolecular
˚
bond with complex 4 (N(1) O(5) 2.801(10) A, N(1)-H-
3 3 3
(1A) O(5) 152°). Phenyl and tolyl substituents are slightly
3 3 3
twisted relative to the central molecular plane (the dihedral
angles between the planes of substituents and the O(5)C(35)C-
(36)C(37)N(3) plane are 13.7° and 10.1°, correspondingly).
As a result of N-O chelation of the ruthenium atom in the
six-membered cycles of the complexes 2-4, there is significant
redistribution of the bond lengths with major contribution of
the imine-enol form of the ligand. Thus, the C-C(O) bonds
become systematically shorter than the C-C(N) bonds
(26) (a) Strecker, B.; Zeier, B.; Schulz, M.; Wolf, J.; Werner, H. Chem.
ꢀ
ꢀ
Ber. 1990, 123, 1787. (b) Vicente, J.; Arcas, A.; Fernandez-Hernandez, J. M.;
Bautista, D.; Jones, P. G. Organometallics 2005, 24, 2516.
(27) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1.

Article
Organometallics, Vol. 29, No. 4, 2010 1017
˚
Table 3. Selected Bond Lengths (A) and Angles (deg) for Two Crystallographically Independent Molecules (A/B) of Complex 3
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-O(3)
Ru(1)-O(4)
Ru(1)-C(5)
Ru(1)-N(2)
O(3)-C(3)
C(3)-C(4)
1.845(9)/1.856(8)
1.870(8)/1.844(9)
2.078(5)/2.088(5)
2.082(4)/2.080(5)
2.057(7)/2.077(7)
2.142(5)/2.140(6)
1.311(7)/1.299(7)
1.388(9)/1.383(9)
C(4)-C(5)
1.401(9)/1.391(9)
1.321(8)/1.323(8)
1.419(6)/1.413(6)
1.298(7)/1.292(7)
1.354(8)/1.360(9)
1.398(9)/1.399(10)
1.306(8)/1.292(8)
1.441(6)/1.433(7)
N(1)-C(5)
N(1)-C(13)
O(4)-C(19)
C(19)-C(20)
C(20)-C(21)
N(2)-C(21)
N(2)-C(29)
C(1)-Ru(1)-O(3)
C(2)-Ru(1)-O(4)
C(5)-Ru(1)-N(2)
C(5)-Ru(1)-O(3)
O(4)-Ru(1)-N(2)
C(3)-O(3)-Ru(1)
O(3)-C(3)-C(4)
C(3)-C(4)-C(5)
175.9(3)/178.8(3)
177.2(2)/176.8(3)
166.9(3)/165.4(3)
79.7(2)/79.8(3)
C(4)-C(5)-Ru(1)
C(5)-N(1)-C(13)
C(19)-O(4)-Ru(1)
O(4)-C(19)-C(20)
C(19)-C(20)-C(21)
N(2)-C(21)-C(20)
C(21)-N(2)-Ru(1)
C(21)-N(2)-C(29)
111.1(5)/110.6(5)
127.1(6)/127.7(6)
126.2(4)/127.6(5)
124.6(7)/123.9(7)
126.9(7)/128.3(7)
127.7(7)/128.3(7)
121.9(5)/121.9(6)
119.5(5)/118.7(6)
86.9(2)/88.4(2)
113.3(4)/111.7(4)
118.3(7)/120.5(7)
117.2(6)/116.8(7)
˚
Table 4. Selected Bond Lengths (A) and Angles (deg) for
Complex 4
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-O(3)
Ru(1)-O(4)
Ru(1)-C(5)
Ru(1)-N(2)
O(3)-C(3)
C(3)-C(4)
C(4)-C(5)
N(1)-C(5)
N(1)-C(13)
1.847(9)
1.877(9)
2.100(5)
2.146(5)
2.032(8)
2.094(6)
1.307(10)
1.397(11)
1.397(11)
1.351(10)
1.444(7)
O(4)-C(19)
C(19)-C(20)
C(20)-C(21)
N(2)-C(21)
N(2)-C(29)
O(5)-C(35)
C(35)-C(36)
C(36)-C(37)
N(3)-C(37)
N(3)-C(45)
1.295(9)
1.383(10)
1.389(10)
1.326(9)
1.449(7)
1.283(10)
1.422(12)
1.378(12)
1.382(10)
1.402(8)
C(1)-Ru(1)-O(3)
C(2)-Ru(1)-N(2)
C(5)-Ru(1)-O(4)
C(5)-Ru(1)-O(3)
N(2)-Ru(1)-O(4)
C(3)-O(3)-Ru(1)
O(3)-C(3)-C(4)
C(3)-C(4)-C(5)
C(4)-C(5)-Ru(1)
C(5)-N(1)-C(13)
C(19)-O(4)-Ru(1)
178.5(3)
174.4(3)
166.3(3)
80.0(3)
O(4)-C(19)-C(20)
C(19)-C(20)-C(21)
N(2)-C(21)-C(20)
C(21)-N(2)-Ru(1)
C(21)-N(2)-C(29)
C(37)-N(3)-C(45)
O(5)-C(35)-C(36)
O(5)-C(35)-C(38)
C(36)-C(35)-C(38)
C(37)-C(36)-C(35)
C(36)-C(37)-N(3)
126.0(8)
126.5(8)
129.5(8)
122.5(5)
114.9(6)
129.7(8)
119.9(9)
119.0(8)
121.1(9)
123.1(9)
124.2(9)
89.2(2)
111.1(5)
120.8(8)
114.6(8)
113.2(6)
127.0(7)
125.2(5)
convenient to use the concept of mutual trans-influence of
ligands.29a,b The considerable elongation of the Ru-O and
Ru-N bonds trans to the carbon atom is in an agreement
with known data on the strong trans-influence of σ-bound
sp2-hybridized carbon atoms.29c Taking the complexes with
five-membered cycles as examples, we can make a conclusion
about the stronger trans-influence of the nitrogen atom
compared to the oxygen, taking into account the difference
in Ru-C bond lengths trans to these atoms (2.057(7),
Figure 3. ORTEP drawing of the independent part of the unit
cell for cocrystal “4 þ 1” with thermal ellipsoids at the 30%
probability level (hydrogen atoms of the phenyl and tolyl
substituents have been omitted for clarity).
˚
(average values are 1.373 and 1.398 A, respectively), and the
˚
C-N bond is significantly shortened (average value is 1.307 A).
A similar distribution of the bond lengths with predominant
imine-enol form of the ligand is observed in the majority of
complexes with six-membered azaoxametallacycles.28
˚
˚
2.077(7) A for that trans to N and 2.032(8) A for that trans
to O). The trans-influence of the metalcarbonyl ligand is
comparable with the influence of the nitrogen atom (this can
be concluded from the equality of the Ru-N bond lengths in
complexes 2 and 4). According to these data, for the ligand
environment of the ruthenium atom in complexes 2-4 it is
possible to suggest the following order of trans-influence:
C . CO ≈ N > O.
At the same time, in the five-membered cycles of com-
plexes 3 and 4, the C-C bonds are equalized (average
˚
distance is 1.393 A), while the C-N bond is slightly elon-
gated (average value is 1.332 A). This means that the five-
˚
membered cycle is characterized by stronger delocalization
than the six-membered cycle. It should be noted that the
CdO bond is not sensitive to the changes in coordination,
and in all complexes it is characterized by a nearly identical
length that is insignificantly longer than that in 1.
While discussing the bond lengths with participation of
the ruthenium atom in octahedral complexes 2-4, it is
2. Spectral Data for 2-4. IR spectra of the complexes 2-4
(Table 1) contain two bands of equal intensity in the area of
stretching vibrations of metalcarbonyl groups, which is
normally observed for two CO ligands in cis-position to
each other. The presence of additional bands of low intensity
(29) (a) Anderson, K. M.; Orpen, A. G. Chem. Commun. 2001, 2682.
(b) Coe, B. J.; Glenwright, S. J. Coord. Chem. Rev. 2000, 203, 5. (c) Kapoor,
P. N.; Kakkar, R. J. Mol. Struct. (THEOCHEM) 2004, 679, 149.
(28) Cambridge Structural Database (CSD), version 5.30 (November
2008).

1018 Organometallics, Vol. 29, No. 4, 2010
Osintseva et al.
in complexes 3 and 4 is due to the distortion of the molecular
symmetry because of the presence of two nonequivalent
metallocycles (five- and six-membered cycles). The similarity
of azaoxaruthenacycles in complex 2 is confirmed by 1H and
13C NMR spectra. In NMR spectra of complexes 3 and 4 a
double set of signals is present, which is explained by the
presence of cycles of different structure.
both complexes. This allows us to assume that the oxygen
atom in the five-membered cycle is a stronger base than
oxygen in the six-membered cycle.
The signals of the carbon atoms in the R-position in the
five-membered cycles in 3 (103.0 ppm) and 4 (102.7 ppm) are
shifted toward low field in comparison with those in 1 (93.5 ppm),
unlike similar signals in six-membered cycles (91.8-92.9 ppm).
The position of the carbonyl carbon atom remains unchanged.
The spectral characteristics of the carbon atoms and the
olefin protons of six-membered azaoxaruthenacycles in
complexes 2-4 are similar. In 13C NMR spectra the position
of the signals of the carbon atoms in R-position is still nearly
the same upon the cycle formation compared to 1,30 while the
signals of the carbon atoms in β-position are shifted to low-
field up to 160 ppm (143.6 ppm in 1). The signals of the
carbonyl carbon atoms are shifted relative to 1 (190.4 ppm)
to high field up to 175 ppm in 2 and 3 and to 177.2 ppm in 4. A
similar shift of the signal of the carbonyl carbon atom is
noticed in the analogous complexes, and it corresponds to
the increase in the electron density at this atom.6,31 The
difference in the signal positions for complexes 2, 3, and 4 is
probably caused by the fact that in complexes 2 and 3 the
metalcarbonyl group is in trans-position to the oxygen atom
of the azaoxaruthenacycle, while in 4 the carbon atom of the
five-membered cycle appears to be oriented trans to this
oxygen atom. The stronger trans-influence of the carbon
atom leads to the low-field shift of the signal in 4. Spatial
differences have no influence on the proton doublets of the
olefin groups of six-membered cycles. In the three complexes,
the positions of the doublets of the olefin protons are nearly
identical and are slightly different from the corresponding
positions in 1 (Table 1). The spin-spin coupling constant of
the olefin protons decreases from 8 to 7 Hz (on average) upon
cycle formation. Thus, according to NMR spectra during the
formation of the six-membered cycles in the organic ligand
the order of carbonyl and olefin bonds decreases and a
partial imine bond is formed, which corresponds to deloca-
lization in the six-membered cycles with some apparent
imine-enol structure.
1
The singlets of amine protons in the H NMR spectra are
observed in the field of aromatic protons, which means that the
exocyclic nitrogen atom forms a partial imine bond with the
carbon atom in β-position. So, according to the spectral data,
the delocalized system of bonds is formed in the five-membered
cycles with some contribution of the keto-imine structure.
3. Formation of Chelate Metallacycles. There is a tradi-
tional point of view that the tautomeric equilibrium in
β-amino vinyl ketones is shifted to the keto-enamine form.1,7
However, in several publications the authors proved that
β-amino vinyl ketones exist in imine-enol form as well.
Depending on substituents and solvents, one of the two
forms prevails.3c,32
According to the 1H,1H COSY and 1H,13C HMQC spec-
tral data, amino vinyl ketone 1 exists in the keto-enamine
tautomeric form (Table 1), which agrees with the X-ray
structural data. We assume that formation of complexes
2-4 with relatively high yield is explained by this fact. This is
confirmed by the fact that a very low yield of the product is
obtained in the reaction of Ru3(CO)12 with N-phenylsalicyli-
denimine,20 which exists predominantly in the imine-enol
form.
Most of amino vinyl ketones with secondary amino groups
adopt a cis-conformation,33 which is stabilized by intra-
molecular hydrogen bond. However, in a number of pub-
lications it was noticed that the conformation of the molecule
is influenced by both substituents and solvent.34a,b A phenyl
substituent at the nitrogen atom stabilizes the intramolecular
hydrogen bond; therefore amino vinyl ketones with aromatic
substituents are observed only in a cis-conformation,
whereas amino vinyl ketones with methyl substituents (for
example, 4-methylamino-3-butene-2-one) are present in
solution in both cis- and trans-conformations.34b The methyl
substituent at the carbon atom in R-position stabilizes the
trans-conformation independently of other substituents. For
a number of amino vinyl ketones a mixture of cis- and trans-
conformers was observed in (CD3)2SO, a solvent that
strongly binds the protons, while in CDCl3 only cis-conformers
were observed.34a
In 13C NMR spectra of 3 and 4 three low-field signals are
observed. The signals located at 218.4 (3) and 217.7 (4) ppm
can possibly be attributed to carbon atoms in β-position of
the five-membered cycles. This can be explained by a partial
contribution of carbene character of the Ru-Cβ bond, which
implies a partial furan structure of the five-membered cycle.20
In the 13C NMR spectrum of complex Ru(CO)2(OdC(Fc)-
CHdC(Fc))2 a similar signal was observed at even lower
field, at 235.3 ppm.20 The signals located at 197.4 and 201.1
ppm in 3 and at 194.0 and 202.4 ppm in 4 can be attributed to
metalcarbonyl groups. We assume that the signal at 197.4
ppm in 3 corresponds to the metalcarbonyl group located
trans to the oxygen atom of the six-membered cycle. The
fact that the metalcarbonyl groups of complex 2 with
similar spatial environment appear as a singlet at 198.3
ppm supports this assumption. The slightly high-field-
shifted signal at 194.0 ppm in 4 corresponds to the metalcar-
bonyl group located trans to the nitrogen atom of the six-
membered cycle, which is a weaker base than the oxygen
atom. Two close signals at 201.1 in 3 and 202.4 ppm in 4 can
be attributed to the metalcarbonyl groups being in trans-
position to the oxygen atoms of the five-membered cycles in
1
According to the H NMR spectrum recorded at room
temperature in CDCl3, the protons of the olefin group in 1
are in cis-conformation (3JH-H =8.0 Hz, Table 1). The
proton of the amino group and the proton of the carbon
atom in β-position are in s-trans-conformation since the last
one appears as a doublet of doublets with two spin-spin
coupling constants 3JH-H = 8.0 and 12.4 Hz.
Replacement of a labile proton by an ion of a transition
metal leads to the formation of a six-membered chelate cycle.
In order for coordination of an amino vinyl ketone on a
carbon atom at β-position to occur and a five-membered
(32) Kikta, E. J.; Bieron, J. F. Org. Magn. Reson. 1976, 8, 192.
(33) Tripatri, V. K.; Venkataramani, P. S.; Mehta, G. J. Chem. Soc.,
Perkin Trans. 1 1979, 1, 36.
(34) (a) McMullen, C. H.; Stirling, C. J. M. J. Chem. Soc. (B) 1966,
1221. (b) Dudek, G. O.; Volpp, G. P. J. Am. Chem. Soc. 1963, 85, 2697.
(30) Haak, E. Eur. J. Org. Chem. 2007, 17, 2815.
(31) Kwiatkowski, M.; Kwiatkowski, E.; Olechnowicz, A.; Ho,
D. M.; Deutsch, E. J. Chem. Soc., Dalton Trans. 1990, 2497.

Article
Organometallics, Vol. 29, No. 4, 2010 1019
Scheme 2. Possible Stereoisomers for Complexes 2-4
cycle to form, the spatial transformation of a molecule from
cis- to trans-conformation is necessary.
and N-N atoms.3b It is necessary to point out that all these
complexes are obtained from salts and, hence, the mechanisms
of their formation can differ significantly from the processes
occurring in the thermal reaction of Ru3(CO)12 with 1.
Transformation of molecule 1 and Cβ-H bond activation
can occur as a result of ruthenium coordination to an oxygen
atom or on heating of the reaction mixture.35 To test the last
Among the reaction products of Ru3(CO)12 with 1, only one
complex with two azaoxaruthenacycles (2) in which the oxygen
atoms are located in trans-positions to metalcarbonyl groups
and the nitrogen atoms are in trans-position to each other has
been isolated. For complex 2 it is possible to suggest the
existence of two more stereoisomers (Scheme 2). The number
of possible stereoisomers is limited to the cis-arrangement of
metalcarbonyl ligands (taking into account the destabilizing
effect of the trans-arrangement of the two metalcarbonyl
groups). For example, in the complex (salalen)Ru(CO)2 the
necessity of cis-arrangement of the two metalcarbonyl groups
leads to the distortion of the rigid organic molecule.2
1
assumption, we have recorded H NMR spectra of 1 on
heating from room temperature to 363 K. No changes
indicating the presence of the trans-conformer were observed
(see Experimental Section). Therefore, we believe that the
transformation of molecule 1 with further Cβ-H bond
activation most likely results from coordination of ruthe-
nium to an oxygen atom.
4. Isomerism of the Mononuclear Complexes. For the
mononuclear complexes containing two azaoxaruthena-
cycles, there is a possibility of the formation of stereoisomers
differing in the mutual orientation of ligands in the coordi-
nation sphere of the metal. It was noticed in a number of
works that steric hindrance at nitrogen atoms makes the
formation of stereoisomers with cis-arrangement of nitrogen
less probable for both square-planar3c and octahedral ligand
environments.8 In structurally characterized octahedral
ruthenium complexes with two azaoxaruthenacycles various
mutual arrangements of ligands are observed: in complex
(F6-acen)Ru(PPh3)2 the cyclic ligand is located in an equa-
torial plane with the trans-orientation of oxygen and nitro-
gen atoms (trans O-N) and two thriphenylphosphine
ligands in axial positions;25 two complexes cis-Ru(salalen)-
(CO)2 are characterized by the trans-orientation of O-N,
O-CO, and N-CO atoms;2 cationic complex (hpNP)2-
Ru(CO)2 is characterized by the trans-orientation of N-N
and O-CO atoms.23 In the complex [Ru(HOC(CF3)d
CHCHdNMe)3] the relative arrangement of three chelate
cycles is such that there is a trans-orientation of O-O, O-N,
In order to study which isomer (2, 2a, and 2b) would be
energetically preferable, we have carried out the quantum
chemical calculations of these three isomers at the PBE0/
DGDZVP level of theory, using the Gaussian03 program.36
(36) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.;
Robb, M. A.; Cheeseman, J. R.; Montgomery, J. A., Jr.; Vreven, T.;
Kudin, K. N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.;
Barone, V.; Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson,
G. A.; Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.;
Hasegawa; J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai,
H.; Klene, M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Bakken,
V.; Adamo, C.; Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev,
O.; Austin, A. J.; Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.;
Morokuma, K.; Voth, G. A.; Salvador, P.; Dannenberg, J. J.;
Zakrzewski, V. G.; Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas,
O.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.;
Ortiz, J. V.; Cui, Q.; Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.;
Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong, M. W.;
Gonzalez, C.; Pople, J. A. Gaussian 03; Gaussian, Inc.: Wallingford, CT,
2004.
(35) Rosenberg, E.; Kabir, S. E.; Hardcastle, K. I.; Day, M.; Wolf, E.
Organometallics 1990, 9, 2214.

1020 Organometallics, Vol. 29, No. 4, 2010
Osintseva et al.
˚
Table 5. Selected Bond Lengths (A) and Angles (deg) for
Complex 5
Ru(1)-Ru(2)
Ru(1)-Ru(3)
Ru(1)-Ru(4)
Ru(2)-Ru(3)
Ru(2)-Ru(4)
Ru(3)-Ru(5)
Ru(4)-Ru(5)
Ru(2)-H(1M)
Ru(2)-H(2M)
Ru(4)-H(1M)
Ru(3)-H(2M)
Ru(1)-C(1)
2.7759(4)
2.8738(4)
2.8337(4)
2.9619(4)
3.0337(4)
2.8297(4)
2.8455(4)
1.77
1.65
1.75
1.72
1.925(4)
1.918(3)
1.895(3)
2.113(3)
1.923(4)
1.898(3)
Ru(2)-C(6)
Ru(3)-C(7)
Ru(3)-C(8)
Ru(3)-O(15)
Ru(3)-C(17)
Ru(4)-C(9)
Ru(4)-C(10)
Ru(4)-C(11)
Ru(4)-C(17)
Ru(5)-C(12)
Ru(5)-C(13)
Ru(5)-C(14)
Ru(5)-C(16)
Ru(5)-C(17)
O(15)-C(15)
C(15)-C(16)
C(16)-C(17)
1.908(3)
1.880(3)
1.928(3)
2.107(2)
2.095(3)
1.930(3)
1.911(3)
1.931(3)
2.146(3)
1.931(3)
1.917(3)
1.931(3)
2.197(3)
2.103(3)
1.269(4)
1.448(4)
1.468(4)
Ru(1)-C(2)
Ru(1)-C(3)
Ru(1)-C(17)
Ru(2)-C(4)
Ru(2)-C(5)
Ru(2)-Ru(1)-Ru(4)
Ru(2)-Ru(1)-Ru(3)
Ru(4)-Ru(1)-Ru(3)
Ru(1)-Ru(2)-Ru(3)
Ru(1)-Ru(2)-Ru(4)
Ru(3)-Ru(2)-Ru(4)
Ru(5)-Ru(3)-Ru(1)
Ru(5)-Ru(3)-Ru(2)
Ru(1)-Ru(3)-Ru(2)
65.47(1)
63.21(1)
81.63(1)
60.01(1)
58.18(1)
76.95(1)
92.85(1)
91.80(1)
56.78(1)
Ru(1)-Ru(4)-Ru(5)
Ru(1)-Ru(4)-Ru(2)
Ru(5)-Ru(4)-Ru(2)
Ru(3)-Ru(5)-Ru(4)
C(15)-O(15)-Ru(3)
O(15)-C(15)-C(16)
C(15)-C(16)-C(17)
C(16)-C(17)-Ru(3)
C(17)-Ru(3)-O(15)
93.36(1)
56.35(1)
90.02(1)
82.20(1)
114.1(2)
118.5(3)
114.8(3)
108.1(2)
79.4(1)
Figure 4. ORTEP drawing of the molecular structure of com-
plex 5 with thermal ellipsoids at the 50% probability level
(hydrogen atoms of the phenyl and tolyl substituents have been
omitted for clarity).
“softest” ligands). This qualitative conclusion is also con-
firmed by quantum chemical calculations, showing that
stereoisomer 3a lies higher in energy, by 6.9 kcal/mol, than
isomer 3. At the same time, the difference in energy between 3
and 4 is only 0.6 kcal/mol, and both complexes are found
among the reaction products. In spite of the fact that in 4 the
less favorable arrangement of a nitrogen atom in trans-
position to CO is observed, the total energy decreases,
apparently, due to the energetically more favorable trans-
arrangement of the O-C atoms, in comparison with the
trans-arrangement of the N-C atoms in complex 3.
The collected data (experimentally observed stereo-
isomers, their percentage in the reaction products, and the
calculated data on their relative stability) allow establishing
the following tendencies for complexes 2-4. The oxygen
atom of the carbonyl group of the ligand is the “hardest”
ligand in comparison to the nitrogen atom of the amine
group. The metalcarbonyl ligand and the carbon atom in the
five-membered cycle with a partial furan structure are the
“soft” ligands with comparable properties.
The formation of the complexes is controlled by both
thermodynamic and kinetic conditions, including the sterical
difficulties during the cis-arrangement of atoms with bulky
substituents. So, in spite of the fact that according to
calculations complex 4 is thermodynamically more stable
than 3, in the reaction the yield of complex 4 is 2.5 times less
than the yield of complex 3.
5. Polynuclear Complexes 5-7. Minor amounts of the
three polynuclear complexes 5-7 were also obtained from
the reaction of Ru3(CO)12 with 1. In these complexes Ru3-
(CO)12 exhibits the ability to form cluster compounds.
According to the X-ray diffraction data (Figure 4, Table 5)
the metal core of the pentanuclear complex 5 represents a
butterfly framework with an additional ruthenium atom
(Ru(5)) bridging the two wingtips (Ru(3) and Ru(4)). In
complex 14 terminally bonded carbonyl ligands and two
bridging hydrides are present. Complex 5 is the only reaction
product, during formation of which the deamination of
The obtained results show that all isomers correspond to the
stable conformations, which is also proved by frequency
analysis. It was found that the experimentally observed
isomer (complex 2) corresponds to a global minimum, while
isomers 2a and 2b appear to be sufficiently higher in energy
by 3.3 and 5.4 kcal/mol (including ZPVE correction).
The calculations coincide with the trans-choice of ligands
theory, according to which in the coordination sphere of a
metal the “hardest” and “softest” ligands are located in
trans-position.37a-d
According to the obtained data it is possible to suggest the
following scheme of formation of complex 2. After the
formation of the first azaoxaruthenacycle, the conditions
for addition of the second molecule of amino vinyl ketone 1
are created. Thus, the consecutive replacement of two metal-
carbonyl groups occurs according to the trans-choice theory.
The “hardest” oxygen atom attacks one of axial metal-
carbonyl groups, as their mutual trans-influence is at a
maximum. Chelation is completed with the coordination of
a nitrogen atom in trans-position to the nitrogen atom of the
first cycle, as a trans-arrangement of the oxygen atom and
metalcarbonyl group from the point of view of the trans-
choice is most favorable. The trans-arrangement of nitrogen
atoms is probably also caused by steric repulsions, as men-
tioned earlier.8
For complexes with two different chelate metallacycles in
the coordination sphere of the metal there is a possibility of
the existence of four stereoisomers, two of which (complexes
3 and 4) are isolated from the reaction. The absence of the
isomers 3a and 4a (Scheme 2) among the reaction products is
apparently caused by the destabilizing effect of the mutual
trans-arrangement of CO and the carbon atom (the two
(37) (a) Pearson, R. G. Inorg. Chem. 1973, 12, 712. (b) Pearson, R. G.
J. Chem. Educ. 1999, 76, 267. (c) Cuevas, J. V.; García-Herbosa, G.; Miguel,
~
D.; Munoz, A. Inorg. Chem. Commun. 2002, 5, 340. (d) Vicente, J.; Abad, J.-
A.; Frankland, A. D.; Ramírez de Arellano, M. C. Chem.;Eur. J. 1999, 5,
3066.

Article
Organometallics, Vol. 29, No. 4, 2010 1021
˚
Table 6. Selected Bond Length (A) and Angles (deg) for
Complex 6
Ru(1)-Ru(2)
Ru(1)-Ru(3)
Ru(1)-Ru(4)
Ru(2)-Ru(3)
Ru(2)-Ru(4)
Ru(2)-H(1M)
Ru(2)-H(2M)
Ru(3)-H(2M)
Ru(4)-H(1M)
Ru(1)-C(1)
2.8819(1)
2.9201(1)
2.8026(1)
2.7867(1)
2.7431(1)
1.72(2)
1.79(2)
1.66(2)
1.85(2)
1.899(1)
1.934(1)
1.936(1)
2.278(1)
2.231(1)
1.887(1)
1.865(1)
Ru(2)-N(1)
2.1340(9)
2.524(1)
1.969(1)
1.855(1)
2.1317(8)
2.018(1)
1.901(1)
1.948(1)
1.910(1)
2.1180(9)
1.267(1)
1.455(1)
1.429(1)
1.418(1)
1.434(1)
Ru(2) C(13)
3 3 3
Ru(3)-C(6)
Ru(3)-C(7)
Ru(3)-O(11)
Ru(3)-C(13)
Ru(4)-C(8)
Ru(4)-C(9)
Ru(4)-C(10)
Ru(4)-N(1)
O(11)-C(11)
C(11)-C(12)
C(12)-C(13)
N(1)-C(13)
N(1)-C(21)
Ru(1)-C(2)
Ru(1)-C(3)
Ru(1)-C(12)
Ru(1)-C(13)
Ru(2)-C(4)
Ru(2)-C(5)
Ru(2)-Ru(1)-Ru(3)
Ru(4)-Ru(1)-Ru(2)
57.405(3) O(11)-Ru(3)-Ru(2)
57.685(3) C(7)-Ru(3)-Ru(1)
137.22(2)
151.19(4)
113.98(4)
81.89(2)
88.9(8)
Ru(4)-Ru(1)-Ru(3) 103.612(4) C(6)-Ru(3)-Ru(1)
Ru(3)-Ru(2)-Ru(1)
Ru(4)-Ru(2)-Ru(1)
Ru(4)-Ru(2)-Ru(3) 108.866(4) C(6)-Ru(3)-H(2M)
Ru(2)-Ru(3)-Ru(1)
Ru(2)-Ru(4)-Ru(1)
C(13)-Ru(3)-O(11)
C(11)-O(11)-Ru(3) 112.00(7)
O(11)-C(11)-C(12) 119.07(9)
C(13)-C(12)-C(11) 113.86(9)
C(12)-C(13)-Ru(3) 111.49(7)
61.987(3) O(11)-Ru(3)-Ru(1)
59.707(3) C(7)-Ru(3)-H(2M)
85.7(8)
95.0(8)
Figure 5. ORTEP drawing of the molecular structure of com-
plex 6 with thermal ellipsoids at the 50% probability level
(hydrogen atoms of the phenyl and tolyl substituents have been
omitted for clarity).
60.608(3) C(13)-Ru(3)-H(2M)
62.609(3) O(11)-Ru(3)-H(2M) 174.7(8)
79.70(4)
C(13)-N(1)-C(21)
C(13)-N(1)-Ru(4)
C(21)-N(1)-Ru(4)
C(13)-N(1)-Ru(2)
C(21)-N(1)-Ru(2)
Ru(4)-N(1)-Ru(2)
117.79(8)
109.08(6)
125.17(7)
88.16(6)
125.90(7)
80.35(3)
amino vinyl ketone 1 is observed. The oxadiene fragment of
the ligand chelates the Ru(3) atom, forming a five-membered
oxaruthenacycle. The olefin group of the oxaruthenacycle
participates in π-coordination with the Ru(5) atom. The
formation of oxaruthenacycles of similar structure as a result
of deamination of amino vinyl ketone has been observed by
us earlier in the reaction of Ru3(CO)12 with 1-phenyl-3-
morpholineprop-2-en-1-one.14
N(1)-C(13)-C(12)
N(1)-C(13)-Ru(3)
124.62(9)
123.82(7)
Despite the difference in the substituents at the carbon
atoms, the structure of the cluster is completely identical to
that of 5. It was suggested39 that but-3-yn-2-ol is oxidized to
the corresponding ketone during one of the reaction steps.
Therefore, the mechanism of the formation of both com-
plexes can be similar.
The main feature of the oxaruthenacycle in complex 5
consists in the unusual μ4-coordination of the C(17) atom
(the four Ru-C(17) distances are in the range 2.095-
The IR spectrum of 5 reveals eight absorption bands of
different intensities in the region of stretching vibrations of
˚
(3)-2.146(3) A). The organic ligand is bonded with four of
five ruthenium atoms so that the wingtips of the butterfly are
bridged only by one atom (C(17)).
1
the terminal carbonyl ligands (Table 1). In H NMR spec-
trum of complex 5 the signal of the proton of the oxaruthe-
nacycle is observed at 5.51 ppm, which is characteristic for
the olefin group being σ,π-coordinated to two metal atoms.20
In addition, there are two high-field doublets at -21.08 and
-27.08 ppm (2JH-H = 1.9 Hz), which correspond to two
bridged hydrides. In the 13C NMR spectrum we have found a
signal at 323.95 ppm, which can be attributed to the carbido
carbon C(17). Similar signals were observed for such μ4-
In complex 5 the seven bonding Ru-Ru distances are
present and their values lie in the range 2.7759(4)-3.0337(4)
A, with the shortest distance between Ru(1) and Ru(2) atoms
at the hinge of the butterfly. The elongation of the Ru-
(2)-Ru(3) and Ru(2)-Ru(4) distances is possibly caused by
the loosening effect of the bridge hydride ligands, the posi-
tions of which are unambiguously established by X-ray
diffraction.
˚
carbido atoms in polynuclear ruthenium clusters.39,40
A
Considering the organic ligand in complex 5 as a six-
electron donor and taking into account the presence of
two hydride ligands and 14 carbonyl ligands, the total
number of cluster valence electrons (CVE) is equal to 76,
which corresponds to a wingtip-bridged butterfly skele-
ton.38 The dihedral angle between the wing planes of the
butterfly framework in complex 5 is equal to 92.9°, and
singlet at 214.14 ppm can be attributed to the carbon atom
of the ketone group, C(15). The signals of the metalcarbonyl
groups are located at 188.96-199.18 ppm.
According to the X-ray diffraction data the metal frame-
work of the tetranuclear complex 6 has a butterfly structure
(Figure 5, Table 6). The oxadiene fragment of the organic
ligand chelates the wingtip atom Ru(3) with the formation of
a five-membered oxaruthenacycle. The olefin group of the
oxaruthenacycle is π-coordinated with the Ru(1) atom in the
hinge position (corresponding bond lengths are Ru(1)-
the Ru(3) Ru(4) distance between wingtip atoms is
3 3 3
˚
3.731 A.
It is interesting to note that a similar pentanuclear cluster,
Ru5(CO)14(μ-H)2(μ4-η1:η1:η2:η2-CCHC(CH3)dO), was syn-
thesized in the reaction of Ru3(CO)12 with but-3-yn-2-ol.39
˚
˚
C(12) 2.278(1) A and Ru(1)-C(13) 2.231(1) A). Such a
binuclear fragment with a η3-coordinated oxaruthenacycle
(38) Sappa, E.; Tiripicchio, A.; Braunstein, P. Chem. Rev. 1983, 83,
203.
(39) Lau, C. S. W.; Wong, W. T. J. Chem. Soc., Dalton Trans. 1998,
3391.
(40) Adams, C. J.; Bruce, M. I.; Skelton, B. W.; White, A. H. Chem.
Commun. 1996, 969.

1022 Organometallics, Vol. 29, No. 4, 2010
Osintseva et al.
˚
2.134(1) and Ru(4)-N(1) 2.118(1) A). As a result, the
˚
C(13)-N(1) bond is considerably elongated (1.418(1) A),
in comparison to the similar bond in mononuclear complexes
3 and 4. Thus, in complex 6 the nitrogen atom is out of
conjugation with the oxadiene fragment, which is also con-
firmed by the orientation of the phenyl substituent (torsion
angle C(12)-C(13)-N(1)-C(21) is 90.0°). As a result, the
olefin group participates in π-coordination with the ruthe-
nium atom. This coordination is not typical for amino vinyl
ketones in which the olefin group is deactivated by the donor
influence of the amino group.
It is surprising that in complex 6 among five bonding Ru-Ru
˚
distances the shortest ones are Ru(2)-Ru(3) (2.7867(1) A) and
˚
Ru(2)-Ru(4) (2.7431(1) A), along which the μ-hydride ligands
were unambiguously localized by the X-ray analysis. Such
shortening of these Ru-Ru bonds is in contrast to the well-
known loosening effect of the bridging hydrides. Possibly, in
complex 6 this effect is decreased by the tightening action of the
organic ligand that bridges all four ruthenium atoms and its
coordination is formally described as μ4-η1:η1:η2:η2. Unlike 5, in
complex 6, the wingtip ruthenium atoms are bridged by the two-
atom C-N fragment of the ligand. The dihedral angle between
the wing planes of the butterfly framework in complex 6 is equal
Figure 6. ORTEP drawing of the molecular structure of com-
plex 7 with thermal ellipsoids at the 50% probability level.
to 137.3°, and the Ru(3) Ru(4) distance between the wingtip
3 3 3
˚
atoms is 4.498 A.
One of the 10 metalcarbonyl groups considerably devi-
ates from a linear structure (angle O(3)-C(3)-Ru(1) is
168.6(1)°), and apparently it participates in the semibridging
˚
Table 7. Selected Bond Length (A) and Angles (deg) for
Complex 7
interaction with the Ru(3) atom (Ru(3) C(3) distance is
Ru(1)-Ru(2)
Ru(1)-Ru(3)
Ru(1)-Ru(4)
Ru(2)-Ru(3)
Ru(2)-Ru(4)
Ru(1)-C(1)
Ru(1)-C(2)
Ru(1)-C(3)
Ru(1)-C(14)
Ru(2)-C(4)
Ru(2)-C(5)
Ru(2)-C(6)
Ru(2)-C(14)
2.7007(5)
2.8124(4)
2.8154(4)
2.7458(4)
2.7796(4)
1.908(4)
1.926(4)
1.917(4)
2.207(4)
1.914(4)
1.919(4)
1.904(4)
2.199(3)
Ru(3)-C(7)
Ru(3)-C(8)
Ru(3)-C(9)
Ru(3)-O(13)
Ru(4)-C(10)
Ru(4)-C(11)
Ru(4)-C(12)
Ru(4)-N(1)
O(13)-C(13)
N(1)-C(15)
N(1)-C(23)
C(13)-C(14)
C(14)-C(15)
1.885(4)
1.924(4)
1.914(4)
2.121(3)
1.887(4)
1.919(4)
1.906(4)
2.135(3)
1.269(4)
1.292(4)
1.445(4)
1.434(5)
1.441(5)
3 3 3
˚
2.849 A).
Considering the organic ligand in complex 6 as an eight-
electron donor and taking into account the presence of two
hydride ligands and 10 metalcarbonyl ligands, the total
number of CVEs is equal to 62, which is in agreement with
a butterfly skeleton.
The spectral data for complex 6 are in a good agreement
with the X-ray data. In the 1H NMR spectra the signals of the
hydrides are present as two doublets at -14.44 and -14.02 ppm
(2JH-H = 2.3 Hz).
According to X-ray data the metal core of complex 7 has a
flattened butterfly geometry (Figure 6, Table 7). Unlike all
other complexes, the organic ligand in 7 has an unusual
open-chain structure in the keto-imine tautomeric form. The
bond lengths O(13)-C(13) 1.269(4) and N(1)-C(15) 1.292(4)
Ru(2)-Ru(1)-Ru(3)
Ru(2)-Ru(1)-Ru(4)
Ru(3)-Ru(1)-Ru(4)
Ru(1)-Ru(2)-Ru(3)
Ru(1)-Ru(2)-Ru(4)
Ru(3)-Ru(2)-Ru(4)
Ru(2)-Ru(3)-Ru(1)
Ru(2)-Ru(4)-Ru(1)
O(2)-C(2)-Ru(1)
O(3)-C(3)-Ru(1)
O(5)-C(5)-Ru(2)
O(6)-C(6)-Ru(2)
59.70(1)
C(13)-O(13)-Ru(3)
C(15)-N(1)-C(23)
C(15)-N(1)-Ru(4)
C(23)-N(1)-Ru(4)
O(13)-C(13)-C(14)
C(13)-C(14)-C(15)
C(13)-C(14)-Ru(2)
C(15)-C(14)-Ru(2)
C(13)-C(14)-Ru(1)
C(15)-C(14)-Ru(1)
Ru(2)-C(14)-Ru(1)
N(1)-C(15)-C(14)
117.5(2)
118.9(3)
117.9(2)
123.2(2)
122.5(3)
117.6(3)
116.9(2)
114.1(2)
110.0(2)
115.6(2)
75.6(1)
60.48(1)
119.47(1)
62.17(1)
61.81(1)
123.21(2)
58.13(1)
57.72(1)
170.7(4)
170.7(3)
168.0(3)
169.9(3)
˚
A are close to those for the double bonds, but slightly
elongated due to the coordination with the metal atom.
The nitrogen and oxygen atoms are bonded with the wingtip
ruthenium atoms and the sp3-hybridized C(14) atom is
coordinated by two σ-bonds with the ruthenium atoms at
the hinge of the butterfly framework. The imine nature of the
121.7(3)
1
ligand is confirmed by the H NMR spectrum of the com-
is typical for the complexes obtained in the reactions of
Ru3(CO)12 with oxadienes.20
It should be noted that C(13) and Ru(2) atoms in complex
plex. A signal attributed to the proton at the C(15) atom is
located at 9.90 ppm, which corresponds to a proton at the
double CHdN bond.
The wingtip ruthenium atoms are bridged by the five-atom
fragment O(13)C(13)C(14)C(15)N(1). Such coordination not
only flattens the geometry of the butterfly but even leads to the
opening of the wings of the butterfly by almost 10° outward, in
the opposite direction from the coordinated ligand. The dihe-
dral angle between the wing planes of the butterfly framework
˚
6 are brought together to a distance of 2.524(1) A; however
from our point of view this is rather a forced contact than an
attractive interaction. This is confirmed by the 13C NMR
spectrum of the complex. A signal attributed to the C(13)
atom is located at 162.24 ppm. In binuclear complex Ru2-
(CO)6(μ-H)(OdC(Tol)CHdCPh), also containing a η3-co-
ordinated oxaruthenacycle, the corresponding carbon atom
has a closely located signal at 152.33 ppm.20
in complex 7is equal to 170.3°, and the Ru(3) Ru(4) distance
3 3 3
˚
between the wingtip atoms is 4.861 A.
The deprotonated nitrogen atom bridges Ru(2) and Ru(4)
atoms in an almost symmetrical manner (Ru(2)-N(1)
The bridging fragment (O(13)C(13)C(14)C(15)N(1))
slightly deviates from a planar structure (the maximum

Article
Organometallics, Vol. 29, No. 4, 2010 1023
deviation from an average plane for these five atoms is 0.067
˚
A). The plane of this fragment is perpendicular to the average
and Ru-Ru bond elongation.43a,b Besides electron-rich
butterfly clusters, several electron-precise flattened butterfly
clusters were also observed.43b-e All these complexes as well
as complex 7 are characterized by the shortened Ru-Ru
bond lengths. Whereas the complexes 5-7 are the electron-
precise clusters, it can be noted that the butterfly geometry
does not depend on the electronic properties of the ligands.
Such considerable changes in the values of the dihedral angle
between the wings are caused, first of all, by the length of the
organic chain bridging the wingtip atoms (one atom in 5,
two-atom fragment in 6, and five-atom fragment in 7). The
elongation of the chain connecting the wingtip atoms leads to
the increase in the dihedral angle between the “wing” planes
of the butterfly framework. It indicates the lability of the Ru4
metal core, which is capable of adjusting to both the electro-
nic and spatial peculiarities of the organic molecule.
plane of the quasiplanar metal framework (the dihedral
angle between these planes is 84.5°). The asymmetry of the
organic ligand does not affect the general symmetry of the
complex. It is manifested in the equalization of the Ru(3)-
˚
˚
O(13) (2.121(3) A) and Ru(4)-N(1) (2.135(3) A) distances,
as well as in the positions of the signals of the carbon atoms
C(13) and C(15) in the 13C NMR spectrum (at 199.20 (CdO)
and 196.23 (CHdN) ppm, respectively). It is interesting to
notice that the general symmetry of the complex is observed
also in the equivalence of the Ru-CO distances with the
metalcarbonyl groups located in trans-positions to the oxy-
gen and nitrogen atoms of the organic ligand (Ru(3)-C(7)
˚
1.885(4) and Ru(4)-C(10) 1.887(4) A, respectively). This
also points to an almost equal trans-influence of the carbonyl
and the imine groups.
The equatorial metalcarbonyl groups at the ruthenium
atoms at the hinge of the butterfly are semibridging with
respect to the wingtip ruthenium atoms (the deviation from a
linear structure for these metalcarbonyl groups is 10° on
average). All Ru-Ru distances in 7 are considerably shor-
tened in comparison to the complexes 5 and 6 and are in a
Conclusion
Unlike iron carbonyls, Ru3(CO)12 exhibits activity in
reactions with amino vinyl ketones. This is explained by
the ability of ruthenium to form metal chelates due to the
preferable coordination with the electron lone pairs of the
heteroatoms, instead of the π-systems of the olefin and
carbonyl groups, which is most frequently observed for iron.
As a result, the main products of the reaction of Ru3(CO)12
with 1 are the mononuclear chelate complexes 2-4. Along
with the six-membered chelate cycles the five-membered ones
are formed. This points to an alternative coordination of
ruthenium to N-H and Cβ-H bonds. Earlier the formation
of the five-membered chelate cycles in the reactions of amino
vinyl ketones with transition metals was not observed.
Among the products of the reaction only complex 7, with
open-chain coordination of the ligand, is isolated. This
complex is formed as a result of the N-H and CR-H bond
activation. The reaction is accompanied by the deprotona-
tion of the ligand and requires the presence of a hydrogen
acceptor in the reaction mixture.
˚
narrow interval of values (2.7007(5)-2.8154(4) A).
In the reaction of Ru3(CO)12 with 1 a considerable amount
of tetrahedral hydrides H4Ru4(CO)12 and H2Ru4(CO)13 is
formed. Formally, the M4 species in which the metal frame-
work has a butterfly configuration derive from the tetra-
hedral metal clusters by the cleavage of one metal-metal
bond.41 Therefore one can assume that these tetrahedral
hydrides are the precursors for complexes 5-7. In order to
prove this assumption, we have carried out separate reac-
tions in which the tetrahedral hydrides have been boiled in
heptane with an excess of ligand 1 under the same conditions
as the title reaction. It was shown that tetrahedral hydrides
H4Ru4(CO)12 and H2Ru4(CO)13 do not react with 1.42 This
fact confirms that exactly Ru3(CO)12 is the precursor for
complexes 5-7.
The polynuclear clusters 5-7 show unprecedented varia-
tion of the butterfly geometry; namely, the dihedral angle
between the wings varies from 93° in 5 to 170° in 7. It has been
shown that the electron donation from the ligands can play a
major role in influencing the butterfly geometry with higher
electron counts (64 CVE instead of 62 CVE for the electron-
precise butterfly clusters), favoring larger dihedral angles
All possible tautomeric forms of amino vinyl ketone 1 are
realized as a result of the coordination with the metal atoms.
In the organic ligand of the mononuclear chelate complexes
2-4, the delocalized system is observed with the main
contribution of the imine-enol form. In the butterfly clusters
6 and 7, the ligand is present in the keto-enamine and the
keto-imine forms, respectively.
Comparing the complexes and their ratio in the reaction
products, it is possible to order the relative reactivity of the
functional groups of 1-(4-tolyl)-3-phenylaminoprop-2-en-1-
one in the conditions of the thermal reaction with Ru3(CO)12
as follows: O: > N-H > C-H > N:, CdC.
Unlike earlier studied amino vinyl ketone with tertiary
amino group (1-phenyl-2-methyl-3-morpholinoprop-2-en-
1-one),14 the deamination is not a characteristic feature for
the amino vinyl ketone 1, with a secondary amino group. The
deamination of the ligand is observed only in one of the
minor products of the reaction (complex 5). Further study of
the influence of the substituents in β-amino vinyl ketones in
the course of the thermal reactions with Ru3(CO)12 and of
the structure of the forming products is in progress.
(41) (a) MacLaughlin, S. A.; Van Wagner, J.; Taylor, N. J. Organo-
metallics 1982, 1013. (b) Johnson, B. F. G.; Lewis, J. Adv. Inorg. Chem.
1981, 24, 225. (c) Canty, A. J.; Domingos, A. J. P.; Johnson, B. F. G.; Lewis, J.
J. Chem. Soc., Dalton Trans. 1973, 2056. (d) Sappa, E.; Tiripicchio, A.;
Carty, A. J.; Toogood, G. E. Progress in Inorganic Chemistry; Lippard, S. J.,
Ed.; John Wiley & Sons: New York, 1987; Vol. 35.
(42) A mixture of H4Ru4(CO)12 and 1 in heptane (50 mL) was
refluxed for 5 h. The course of the reaction was monitored by IR spectra
in the region of valence vibrations of the metal carbonyl groups. No
changes in the IR spectrum were detected. A mixture of H2Ru4(CO)13
and 1 in heptane (50 mL) was refluxed for 1 h. After 30 min of heating in
the IR spectrum the signals corresponding to H4Ru4(CO)12 were fixed.
After 60 min of heating in solution only H4Ru4(CO)12 was detected, and
any further changes in the IR spectrum were not observed.
(43) (a) Carty, A. J.; MacLaughlin, S. A.; Van Wagner, J.; Taylor,
N. J. Organometallics 1982, 1013. (b) Corrigan, J. F.; Dinardo, M.; Doherty,
S.; Hogarth, G.; Sun, Y.; Taylor, N. J.; Carty, A. J. Organometallics 1994,
3572. (c) Chi, Y.; Carty, A. J.; Blenkiron, P.; Delgado, E.; Enright, G. D.;
Wang, W.; Peng, S.;-M.; Lee, G.-H. Organometallics 1996, 5269. (d)
Adams, R. D.; Qu, X.; Wu, W. Organometallics 1994, 1272. (e) Charmant,
J. P. H.; King, P. J.; Quesada-Pato, R.; Sappa, E.; Schaefer, C. J. Chem. Soc.,
Dalton Trans. 2001, 46.
Experimental Section
All reactions were carried out in Schlenk equipment under
an atmosphere of dry argon using standard Schlenk techniques.

1024 Organometallics, Vol. 29, No. 4, 2010
Osintseva et al.
Table 8. Crystal Data, Data Collection, and Structure Refinement Parameters for Complexes 2-7
2
3
“4 þ 1”
formula
C34H28N2O4Ru
629.65
yellow plate
triclinic
P1
9.749(2)
10.453(2)
14.587(3)
81.119(4)
78.646(4)
78.244(4)
1416.8(5)
2
1.476
28.0
5.95
0.825/0.971
6788 (0.0564)
5174
0.0423
0.0853
0.979
0.605/-0.879
C34H28N2O4Ru
629.65
yellow prism
triclinic
P1
11.294(2)
14.256(2)
18.749(3)
88.756(4)
82.519(4)
77.315(4)
2919.9(8)
4
1.432
24.0
5.78
0.878/0.982
9129 (0.0862)
4274
0.0580
0.1164
0.873
0.816/-0.484
C34H28N2O4Ru4
866.94
yellow prism
monoclinic
P21/c
10.256(6)
27.132(15)
15.157(9)
90
91.619(8)
90
4216(4)
4
1.366
24.0
4.23
0.830/0.959
6569 (0.1608)
2734
0.0749
0.1537
C16H15NO
3
molecular weight
cryst color, habit
cryst syst
space group
˚
a, A
˚
b, A
˚
c, A
R, deg
β, deg
γ, deg
3
˚
V, A
Z
d(calc), g cm-3
θ
max, deg
-1
˚
μ (Mo KR, λ = 0.71073 A), cm
transmn factors, Tmin/Tmax
no. unique reflns (Rint
no. obsd reflns (I > 2σ(I))
R1 (on F for obsd reflns)
wR2 (on F2 for all reflns)
GOF
)
0.834
0.547/-0.630
-3
˚
largest diff peak/hole, e A
5
6
7
formula
C24H10O15Ru5
1043.67
orange prism
triclinic
P1
8.9357(8)
10.210(1)
16.755(2)
99.856(2)
98.711(2)
92.187(2)
1485.4(2)
2
2.334
30.0
25.54
0.588/0.862
8647 (0.0285)
7105
C26H15NO11Ru4
921.67
red prism
triclinic
P1
9.1494(2)
12.2864(3)
13.4511(3)
104.050(1)
91.887(1)
91.709(1)
1464.93(6)
2
2.089
43.0
20.81
0.653/0.851
21483 (0.0354)
17869
0.0247
0. 0540
1.020
1.372/-1.040
C28H13NO13Ru4 0.5(C6H14
)
3
molecular weight
cryst color, habit
cryst syst
1018.76
brown plate
triclinic
P1
11.3344(6)
12.2030(7)
14.060(1)
105.416(1)
95.563(1)
111.685(1)
1700.2(2)
2
1.990
30.0
18.08
0.782/0.948
9876 (0.0567)
7054
space group
˚
a, A
˚
b, A
˚
c, A
R, deg
β, deg
γ, deg
3
˚
V, A
Z
d(calc), g cm-3
θ
max, deg
-1
˚
μ(Mo KR, λ = 0.71073 A), cm
transmn factors, Tmin/Tmax
no. unique reflns (Rint
no. obsd reflns (I > 2σ(I))
R1 (on F for obsd reflns)
wR2 (on F2 for all reflns)
GOF
)
0.0290
0.0666
1.022
2.077/-0.838
0.0371
0.0814
0.990
1.188/-0.997
-3
˚
largest diff peak/hole, e A
All solvents were dried according to standard procedures. Column
chromatography was performed with Aldrich silica gel (70-230
mesh). Amino vinyl ketone 1 was prepared by a published method.44
Elemental analyses were performed by the Analytical Laboratory of
the Institute of Organoelement Compounds of the RAS. The IR
spectra were recorded in solution on a Specord 75-IR spectrometer.
The 1H NMR and 13C NMR spectra were obtained with a Bruker
Avance-400 spectrometer (400.13 and 100.61 MHz, respectively) and
Avance-600 spectrometer (600.22 and 150.93 MHz, respectively).
and then treated by column chromatography on silica gel.
Elution with a hexane yielded H4Ru4(CO)12 (30 mg, 15.4%),
Ru3(CO)12 (10 mg), and H2Ru4(CO)13 (14 mg, 6.9%), all of
which were identified by IR spectroscopy;45 complexes 5
(13.5 mg, 4.9%), 6 (10.2 mg, 4.2%), and 7 (10.0 mg, 3.8%) were
separated next. These were recrystallized from n-hexane, afford-
ing analytically pure samples 5-7, which were characterized by
analytical and spectral data (Table 1). 5: Anal. Calcd for
Ru5C24H10O15: C, 27.20; H, 0.99. Found: C, 27.35; H, 1.03. 6:
Anal. Calcd for Ru4C26H15NO11: C, 34.15; H, 1.59. Found: C,
34.30; H, 1.65. 7: Anal. Calcd for Ru4C28H13NO13: C, 34.47; H,
1.34. Found: C, 34.60; H, 1.42.
Further elution with a 1:1 n-hexane/benzene mixture yielded
102 mg of a mixture of the complexes 2-4. The obtained 102 mg
of the mixture 2-4 was separated by repeated column chromato-
graphy on silica gel (eluent benzene) to give pure fractions of
complex 2 (49.6 mg, 29.9%), 3 (16.5 mg, 10.0%), and 4 (6.6 mg,
4.0%). The NMR and IR data for complexes 2-7 are given in
Table 1. 2: Anal. Calcd for RuC34H28N2O4: C, 64.86; H, 4.45; N,
1
The H NMR and 13C NMR chemical shifts were referenced to
residual protons in the deuterated solvents (CDCl3, 7.25 ppm; C6D6,
7.26 ppm; all vs Me4Si). The 1H and 13C{1H} NMR and 2D
experiments (COSY for 1 and HMQC for 1 and 7) were performed
at 298 K using standard pulse sequences from the Bruker library.
Preparation of Complexes 2-7 from Ru3(CO)12 and 1. A
mixture of Ru3(CO)12 (178 mg, 0.28 mmol) and 1 (200 mg,
0.84 mmol) flushed with argon was added in 150 mL of heptane,
and the resulting suspension was refluxed for 5 h. After cooling
to 20 °C, the reaction mixture was filtered, partly concentrated,
(44) Nesmeyanov, A. N.; Rybinskaya, M. I.; Rybin, L. V. Russ.
Chem. Bull. 1965, 14, 1345.
(45) Johnson, B. F. G.; Lewis, J.; Williams, I. G. J. Chem. Soc. A
1970, 901.

Article
Organometallics, Vol. 29, No. 4, 2010 1025
4.45. Found: C, 64.73; H, 4.42; N, 4.41. 3: Anal. Calcd for
RuC34H28N2O4: C, 64.86; H, 4.45; N, 4.45. Found: C, 64.62; H,
4.57; N, 4.38. 4: Anal. Calcd for RuC34H28N2O4: C, 64.86; H, 4.45;
N, 4.45. Found: C, 64.71; H, 4.41; N, 4.35. In all cases, crystals
suitable for X-ray analysis were obtained by slow crystallization of
2-7 from n-hexane.
II diffractometer (graphite-monochromated Mo KR radiation,
ꢀ
˚
λ = 0.71073 A, ω-scan technique, T = 100(2) K). The APEX II
software46 was used for collecting frames of data, indexing
reflections, determination of lattice constants, integration of
intensities of reflections, scaling, and absorption correction, and
SHELXTL47 for space group and structure determination,
refinements, graphics, and structure reporting. The structures
were solved by direct methods and refined by the full-matrix
least-squares technique against F2 with anisotropic thermal
parameters for all non-hydrogen atoms. The hydrogen atoms
of hydride ligands in structures 5 and 6 were located in difference
Fourier synthesis. The rest of the hydrogen atoms in the
structures 2-7 were placed geometrically and included in the
structure factor calculations in the riding motion approxima-
tion. The principal experimental and crystallographic para-
meters are presented in Table 8.
High-Temperature 1H NMR Spectra of 1. High-temperature
1H NMR spectra of 1 were obtained with a Bruker Avance-600
spectrometer at 323, 343, and 363 K in nonane (internal
standard DMSO-D6). The presence of the trans-conformation
of 1 at 363 K was not observed. The spin-spin coupling
constant between the amino group proton and the proton at
the β-carbon atom, 3JH-H = 12.0 (at 293 K) and 11.4 Hz (at 363
K), shows that at 363 K the intramolecular hydrogen bond is not
broken. 1H NMR of 1 (nonane, 293 K): 2.28 (s, 3H, Me); 5.85 (d,
1H, CHdCH, 3JH-H = 8.0); 6.86 (t, 1H, p-Ph, 3JH-H = 7.3);
6.91 (d, 2H, o-Ph, 3JH-H = 8.0); 7.06 (d, 2H, Tol, 3JH-H = 8.2);
3
7.14 (dd, 2H, m-Ph, JH-H = 7.3, 8.0); 7.27 (dd, 1H, NH-
3
3
Acknowledgment. The authors are indebted to the
Russian Foundation for Basic Research (Grant Nos.
07-03-00631 and 10-03-00505) for financial support.
The authors also thank Prof. T. V. Timofeeva (New Mexico
Highlands University) for providing us with computational
time for the quantum chemical calculations.
CHdCH, JH-H = 8.0, 12.0); 7.75(d, 2H, Tol, JH-H = 8.2);
12.33 (d, 1H, NH, 3JH-H = 12.0). 1H NMR of 1 (nonane, 363
K): 2.33 (s, 3H, Me); 5.88 (d, 1H, CH = CH, 3JH-H = 8.0); 6.91
(t, 1H, p-Ph, 3JH-H = 7.3); 6.96 (d, 2H, o-Ph, 3JH-H = 8.0); 7.11
3
3
(d, 2H, Tol, JH-H = 8.2); 7.20 (dd, 2H, m-Ph, JH-H = 7.3,
3
8.0); 7.29 (dd, 1H, NH-CHdCH, JH-H = 8.0, 11.4); 7.79 (d,
2H, Tol, 3JH-H = 8.2); 12.25 (d, 1H, NH, 3JH-H = 11.4).
X-ray Diffraction Study of 2-7. Single-crystal X-ray diffrac-
tion experiments were carried out with a Bruker SMART APEX
Supporting Information Available: Full tables of crystal data,
atomic coordinates and equivalent isotropic displacement para-
meters, anisotropic displacement parameters, bond lengths and
angles for 2-7 as CIF files. This material is available free of
charge via the Internet at http://pubs.acs.org.
(46) APEX II software package; Bruker AXS Inc.: Madison, WI, 2005.
(47) SHELXTL v. 5.10, Structure Determination Software Suite;
Bruker AXS: Madison, WI, 1998.