Allenylidene Ligand of [Ru(η5-C5H5)(C=C=CPh 2)(CO)(PPri3)]BF4 as Entry to Novel Unsaturated η1-Carbon Ligands Containing Azetidine and Hexahydroquinoline Skeletons

Article abstract of DOI:10.1021/om9809522

The allenylidene complex [Ru(η⁵-C₅H₅)(C=C=CPh ₂)(CO)(PPrⁱ₃)]BF₄ (1) reacts with dicyclohexylcarbodiimide to give the iminiumazetidinylidenemethyl complex [Ru(η⁵-C₅H₅){CH= CCPh₂N(Cy)=C=N=C(CH₂)₄CH ₂}(CO)(PPrⁱ₃)]BF₄ (2), as a 4:1 mixture of isomers Z (2a) and E (2b). The structure of 2a was determined by an X-ray investigation, revealing a Ru-C distance of 2.070(4) A?. Treatment of the isomeric mixture of 2 with sodium methoxide in tetrahydrofuran at room temperature affords the iminoazetidinylidenemethyl complex Ru(η⁵-C₅H₅){(Z)-CH=CCPh ₂N(Cy)C=NC=CH(CH₂)₃CH₂}(CO)(PPr ⁱ₃) (6), which reacts with HBF₄·OEt₂ to give [Ru(η⁵-C₅H₅){(Z)-CH=CCPh ₂N(Cy)C=N(H)C=CH(CH₂)₃CH ₂}(CO)(PPrⁱ₃)]-BF₄ (7), as a result of the protonation of the exocyclic nitrogen atom of the unsaturated η¹-carbon ligand of 6. In the solid state and in solution at low temperature, complex 7 is stable. However, in solution at room temperature, complex 7 evolves into [Ru(η⁵-C₅H₅){(Z)-CH=CCPh ₂C(CH₂)₄CN(H)=CNHCy}(CO)(PPrⁱ ₃)]BF₄ (8), which reacts with sodium methoxide in tetrahydrofuran at room temperature to give the hexahydroquinolinylidenemethyl complex Ru(η⁵-C₆H₅){(Z)-CH=CCPh ₂C(CH₂)₄CN=CNHCy}(CO)(PPrⁱ ₃) (9), as a result of the deprotonation of the endocyclic nitrogen atom of 8. The structure of 9 was also determined by an X-ray investigation, revealing, in this case, a Ru-C distance of 2.113(4) A?. The formation of the azetidine and hexahydroquinoline skeletons of the ligands of these compounds is discussed.

Full text of DOI:10.1021/om9809522

1606
Organometallics 1999, 18, 1606-1614
Allen ylid en e Liga n d of
[Ru (η5-C5H5)(CdCdCP h 2)(CO)(P P r i )]BF 4 a s En tr y to
3
Novel Un sa tu r a ted η1-Ca r bon Liga n d s Con ta in in g
Azetid in e a n d Hexa h yd r oqu in olin e Sk eleton s
Miguel A. Esteruelas,* Angel V. Go´mez, Ana M. Lo´pez,* Enrique On˜ate, and
Natividad Ruiz
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
Received November 25, 1998
The allenylidene complex [Ru(η5-C5H5)(CdCdCPh2)(CO)(PPri )]BF4 (1) reacts with dicy-
3
clohexylcarbodiimide to give the iminiumazetidinylidenemethyl complex [Ru(η5-C5H5){CHd
CCPh2N(Cy)+C+NdC(CH2)4CH2}(CO)(PPri )]BF4 (2), as a 4:1 mixture of isomers Z (2a )
3
and E (2b). The structure of 2a was determined by an X-ray investigation, revealing a Ru-C
distance of 2.070(4) Å. Treatment of the isomeric mixture of 2 with sodium methoxide in
tetrahydrofuran at room temperature affords the iminoazetidinylidenemethyl complex Ru-
(η5-C5H5){(Z)-CHdCCPh2N(Cy)CdNCdCH(CH2)3CH2}(CO)(PPri ) (6), which reacts with
3
HBF4‚OEt2 to give [Ru(η5-C5H5){(Z)-CHdCCPh2N(Cy)CdN(H)CdCH(CH2)3CH2}(CO)(PPri3)]-
BF4 (7), as a result of the protonation of the exocyclic nitrogen atom of the unsaturated
η1-carbon ligand of 6. In the solid state and in solution at low temperature, complex 7 is
stable. However, in solution at room temperature, complex 7 evolves into [Ru(η5-C5H5){(Z)-
CHdCCPh2C(CH2)4CN(H)dCNHCy}(CO)(PPri3)]BF4 (8), which reacts with sodium methoxide
in tetrahydrofuran at room temperature to give the hexahydroquinolinylidenemethyl complex
Ru(η5-C5H5){(Z)-CHdCCPh2C(CH2)4CNdCNHCy}(CO)(PPri ) (9), as a result of the depro-
3
tonation of the endocyclic nitrogen atom of 8. The structure of 9 was also determined by an
X-ray investigation, revealing, in this case, a Ru-C distance of 2.113(4) Å. The formation of
the azetidine and hexahydroquinoline skeletons of the ligands of these compounds is
discussed.
In tr od u ction
lamine with 1-bromo-3-chloropropane and subsequent
hydrogenolysis.3 2-Methyleneazetidines have been syn-
thesized in high yield via closure of N-aryl â-chloro
ketimines induced by potassium tert-butoxide.4 Highly
selective reductions of â-lactams, direct-tandem bis-â-
lactams, and tandem bis-â-lactams to the corresponding
azetidines and bisazetidines have been successfully
performed by using diisobutylaluminum hydride, mono-
chlorohydroalane, and dichloroalane.5 Reactions of iso-
cyanides with 1-phthalimidoaziridines have led to 1-ph-
thalimidoazetidines by [1+3] cycloaddition to the azome-
thine ylides, which are in equilibrium with the aziridines.6
A general route to prepare 2-substituted azetidines
involves anodic acetoxylation of N-tosylazetidine fol-
lowed by nucleophilic displacement of the acetate by
nucleophiles such as trimethylsilylcyanide, allyltrim-
Azetidines are an interesting class of four-membered
heterocyclic compounds that exhibit various biological
activities such as antihypertensive, antiinflammatory,
antiarrhythmic, antidepressant and monoamine oxidase
inhibitory activities.1
The azetidine skeleton is difficult to synthesize due
to its ring strain. At first glance, the most straightfor-
ward route to prepare this type of compound should be
a polar [2+2] cycloaddition between an imine and an
electron-rich alkene. However, this reaction has been
restricted to a few exceptional cases.2 Accordingly,
several alternative methods have been used. Azetidines
can be prepared via the direct alkylation of benzhydry-
(1) (a) Testa, E.; Wittigens, A.; Maffii, G.; Bianchi, G. In Research
Progress in Organic, Biological and Medicinal Chemistry; Gallo, U.,
Santamaria, L., Eds.; North-Holland Publishing Co.; Ansterdam, 1964;
Vol. 1, pp 447-583. (b) Bellasio, E.; Cristiani, G. J . Med. Chem. 1969,
12, 196. (c) Wells, J . N.; Tarwater, O. R. J . Pharm. Sci. 1971, 60, 156.
(d) Miller, D. D.; Fowble, J .; Patil, P. N. J . Med. Chem. 1973, 16, 177.
(e) Okutani, T.; Kaneko, T.; Masuda, K. Chem. Pharm. Bull. 1974, 22,
1490.
(3) Causey, D. H.; Mays, R. F.; Shamblee, D. A.; Lo, Y. S. Synth.
Commun. 1988, 18, 205.
(4) Sulmon, P.; De Kimpe, N.; Schamp, N. J . Org. Chem. 1988, 53,
4462.
(5) Ojima, I.; Zhao, M.; Yamato, T.; Nakahashi, K. J . Org. Chem.
1991, 56, 5263.
(2) Aben, R. W. M.; Smit, R.; Scheeren, J . W. J . Org. Chem. 1987,
52, 365.
(6) Charrier, J .; Foucaud, A.; Person, H.; Loukakou, E. J . Org. Chem.
1983, 48, 481.
10.1021/om9809522 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 03/31/1999

Novel Unsaturated η1-Carbon Ligands
Organometallics, Vol. 18, No. 9, 1999 1607
ethylsilane, 2-methoxyfuran, and trimethylphosphite.7
Azetidium salts can be formed by cyclization of 3-ami-
nopropanol with trifluoromethanesulfonic anhydride.8
A few examples of azetidinylidene transition-metal
complexes have been also reported. In 1974 E. O.
Fischer observed that (CO)5CrdC(OH)Me reacted with
dicyclohexylcarbodiimide in dichloromethane solution to
produce the iminoazetidinylidene complex (CO)5Cr-
interest,21 up to now, [2+2] cycloaddition-type reaction
of allenylidene ligands has been observed only three
times. In 1996, H. Fischer and co-workers showed that
alkynyl complexes LnMCtCR (M ) Fe, Ni) undergo a
regioselective [2+2] cycloaddition to the CRdCâ bond of
diarylallenylidene complexes (CO)5MCdCdC(C6H4R-p)2
(M ) Cr, W) providing 1,3-dimetalated cyclobute-
nylidene derivatives in high yield.22 The same group has
recently reported that the reactions of the above-
mentioned allenylidene complexes with ynamines afford
two products, alkenylallenylidene and cyclobutenylidene
compounds. The first one is formed via cycloaddition of
the CtC bond of the ynamine to the Câ-Cγ bond of the
allenylidene ligand and subsequent cycloreversion, while
the second one is the result of the cycloaddition of the
ynamines to the CR-Câ double bond of the alle-
nylidene.23 We have observed that the allenylidene
{dCN(Cy)C(dNCy)CH2}.9 The alkoxycarbene (CO)5WC-
(OEt)Ph reacts with alkenyl isocyanides to give 3-aza-
1,2,4-pentatriene complexes, which add a second mol-
ecule of isocyanide to afford 1-azafulvene and azetidin-
2-ylidene derivatives by competitive [4+1] and [3+1]
cycloadditions, respectively. Azetidinylidene complexes
of tungsten and chromium have been also prepared by
addition of imines to carbene or allenylidene com-
pounds.10 Iron alkoxycarbene complexes undergo formal
[1+1+2] cycloaddition reactions with isocyanides to
afford iminoazetidinylidene compounds.11 Similarly,
formal [2+2] cycloaddition of iron-,12 rhenium-, and
manganese-vinylidene13 complexes with imines yield
azetidinylidene derivatives. Azatitanacyclobutane com-
plexes have been prepared by [2+2] cycloaddition of Tid
C and NdC units.14
ligand of Os(η5-C5H5)Cl(CdCdCPh2)(PPri ) reacts with
3
dimethyl acetylenedicarboxylate to give Os(η5-C5H5)-
Cl{CdC(CO2CH3)C(CO2CH3)dCdCPh2}(PPri ), via a
3
stepwise cycloaddition to the CR-Câ double bond of the
allenylidene to form a η1-cyclobutenyl intermediate,
which rapidly ring-opens to afford the allenylvinylidene
product.24
We have previously shown that the solvato complex
In this paper, we report a new [2+2] cycloaddition
reaction on an allenylidene fragment which allows the
formation of the azetidine skeleton and is the entry to
novel organometallic compounds containing new unsat-
urated η1-carbon ligands with four- and six-membered
heterocycles.
[Ru(η5-C5H5){η1-OC(CH3)2}(CO)(PPri )]BF4 reacts with
3
1,1-diphenyl-2-propyn-1-ol to afford the allenylidene
compound [Ru(η5-C5H5)(CdCdCPh2)(CO)(PPri3)]BF4 (1).
The diphenylallenylidene ligand of 1 has been found to
be the master key for the development of extensive
organometallic chemistry, including R,â-unsaturated-
hydroxycarbene, -alkoxycarbene, -(alkylthio)carbene,
and -2-azaallenyl, functionalized allenyl, acyl,15 (acetyl-
ide)carbene, cyclic carbene, vinylidene, alkynyl,16 tet-
rahydronaphthofuranyl,18 pyrazolopyrazolyl,17 ortho es-
ter alkenyl, lactonyl,19 and allenylphosphine20 derivatives.
The exceptional chemical properties of the alle-
nylidene fragment of 1 prompted us to ask ourselves
whether this fragment should also be capable of gen-
erating the azetidine skeleton by a [2+2] cycloaddition
with dicyclohexylcarbodiimide.
Resu lts a n d Discu ssion
1. Syn t h esis of Azet id in ylid en em et h yl Com -
p lexes. Treatment of red dichloromethane solutions of
1 with 1 equiv of dicyclohexylcarbodiimide at room
temperature affords orange solutions, from which the
iminiumazetidinylidenemethyl complex [Ru(η5-C5H5)-
{CHdCCPh2N(Cy)+C+NdC(CH2)4CH2}(CO)(PPri )]-
3
BF4 (2) was isolated as a yellow solid in 88% yield. The
solid is a 4:1 mixture of the isomers Z and E shown in
eq 1.
Although the reactivity of transition metal alle-
nylidene compounds is presently attracting considerable
(7) Shano, T.; Matsumara, Y.; Uchida, K.; Nakatini, F. Bull. Chem.
Soc. J pn. 1988, 61, 3029.
The formation of 2a and 2b (Scheme 1) can be
rationalized as a [2+2] cycloaddition of one of the two
carbon-nitrogen double bonds of the dicyclohexylcar-
bodiimide to the Câ-Cγ double bond of the allenylidene
of 1, to give the intermediate 4, which rapidly evolves
into 5, by an Alder-ene reaction, where the CR-Câ
(8) Erhardt, P. W.; Owens, A. H. Synth. Commun. 1987, 17, 469.
(9) Weiss, K.; Fischer, E. O.; Mu¨ller, J . Chem. Ber. 1974, 107, 3548.
(10) (a) Barrett, A. G. M.; Brock, C. P.; Sturgess, M. A. Organome-
tallics 1985, 4, 1903. (b) Aumann, R.; Kuckert, E.; Kru¨ger, C.;
Angermund, K. Angew. Chem., Int. Ed. Engl. 1987, 26, 563. (c) Fischer,
H.; Roth, G.; Reindl, D.; Troll, C. J . Organomet. Chem. 1993, 454, 133.
(11) Aumann, R.; Heinen, H. Chem. Ber. 1987, 120, 1297.
(12) Barrett, A. G.; Mortier, J .; Sabat, M.; Sturgess, M. A. Organo-
metallics 1988, 7, 2553.
(13) Terry, M. R.; Mercando, L. A.; Kelley, C; Geoffroy, G. L.;
Nombel, P.; Lugan, N.; Mathieu, R.; Ostrander, R. L.; Owens-
Waltermire, B. E.; Rheingold, A. L. Organometallics 1994, 13, 843.
(14) Beckhaus, R.; Wagner, M.; Wang, R. Eur. J . Inorg. Chem. 1998,
253.
(15) Esteruelas, M. A.; Go´mez A. V.; Lahoz, F. J .; Lo´pez, A. M.;
On˜ate, E.; Oro, L. A. Organometallics 1996, 15, 3423.
(16) Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A. M.; Modrego, J .;
On˜ate, E. Organometallics 1997, 16, 5826.
(17) Esteruelas, M. A.; Go´mez A. V.; Lo´pez, A. M.; On˜ate, E.; Ruiz,
N. Organometallics 1998, 17, 2297.
(21) For some recent examples see: (a) Touchard, D.; Pirio, N.;
Dixneuf, P. H. Organometallics 1995, 14, 4920. (b) Cadierno, V.;
Gamasa, M. P.; Gimeno, J .; Borge, J .; Garc´ıa-Granda, S. Organome-
tallics 1997, 16, 3178. (c) Crochet, P.; Demerseman, B.; Vallejo, M. I.;
Gamasa, M. P.; Gimeno, J .; Borge, J .; Garc´ıa-Granda, S. Organome-
tallics 1997, 16, 5406. (d) Cadierno, V.; Gamasa, M. P.; Gimeno, J .;
Lo´pez-Gonza´lez, M. C.; Borge, J .; Garc´ıa-Granda, S. Organometallics
1997, 16, 4453. (e) Bohanna, C.; Callejas, B.; Edwards, A. J .; Esteru-
elas, M. A.; Lahoz, F. J .; Oro, L. A.; Ruiz, N.; Valero, C. Organometallics
1998, 17, 373. (f) Touchard, D.; Haquette, P.; Daridor, A.; Romero, A.;
Dixneuf, P. H. Organometallics 1998, 17, 3844. (g) Bruce, M. I. Chem.
Rev. 1998, 98, 2797.
(18) Esteruelas, M. A.; Go´mez A. V.; Lo´pez, A. M.; On˜ate, E.
Organometallics 1998, 17, 3567.
(19) Esteruelas, M. A.; Go´mez A. V.; Lo´pez, A. M.; Puerta, C.;
Valerga, P. Organometallics 1998, 17, 4959.
(22) Fischer, H.; Leroux, F.; Stumpf, R.; Roth, G. Chem. Ber. 1996,
129, 1475.
(23) Roth, G.; Reindl, D.; Gockel, M.; Troll, C.; Fischer, H. Organo-
metallics 1998, 17, 1393.
(20) Esteruelas, M. A.; Go´mez A. V.; Lo´pez, A. M.; Modrego, J .;
On˜ate, E. Organometallics 1998, 17, 5434.
(24) Crochet, P.; Esteruelas, M. A.; Lo´pez, A. M.; Ruiz, N.; Tolosa,
J . I. Organometallics 1998, 17, 3479.

1608 Organometallics, Vol. 18, No. 9, 1999
Esteruelas et al.
double bond of 4 acts as an enophile. The formation of
the isomers Z (2a ) and E (2b) of 2 suggests that the
intermediate 5 exists as a mixture in equilibrium of the
isomers 5a and 5b.
Sch em e 1
F igu r e 1. Molecular diagram of the complex [Ru(η5-C5H5)-
{(Z)-CHdCCPh2N(Cy)+C+NdC(CH2)4CH2}(CO)(PPri )]-
3
BF4 (2a ). Thermal ellipsoids are shown at 50% probability.
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles
(d eg) of th e Com p lex [Ru (η5-C5H5){(Z)-
CHdCCP h 2N(Cy)+C+NdC(CH2)4CH2}-
(CO)(P P r i3)]BF 4 (2a )
Ru-P
2.3571(11)
1.875(5)
2.070(4)
1.346(5)
1.580(5)
1.534(5)
1.530(5)
C(18)-N(1)
N(1)-C(31)
N(1)-C(37)
C(37)-C(17)
C(37)-N(2)
N(2)-C(38)
1.545(5)
1.482(5)
1.340(5)
1.470(5)
1.369(5)
1.297(5)
Ru-C(15)
Ru-C(16)
C(16)-C(17)
C(17)-C(18)
C(18)-C(19)
C(18)-C(25)
P-Ru-C(15)
89.73(14) C(17)-C(18)-C(25) 113.0(3)
88.15(11) C(17)-C(18)-N(1) 84.0(2)
C(18)-N(1)-C(31) 132.3(3)
P-Ru-C(16)
P-Ru-G(1)a
128.0(2)
97.5(2)
C(15)-Ru-C(16)
C(15)-Ru-G(1)a
C(16)-Ru-G(1)a
Ru-C(16)-C(17)
C(18)-N(1)-C(37)
N(1)-C(37)-N(2)
N(1)-C(37)-C(17)
92.9(3)
128.1(4)
96.1(3)
The [2+2] cycloaddition possibly occurs via a polar
mechanism by attack of one of the N atoms of the
carbodiimide on the Cγ atom of the allenylidene, to give
3. In this context, it should be noted that EHT-MO
calculations on the model compound [Ru(η5-C5H5)(Cd
CdCH2)(CO)(PH3)]+ indicate that 31% of the LUMO of
the complex is located on the Cγ atom of the allenylidene
ligand.16 A similar mechanism has been proposed for
the cycloaddition of aromatic imines to the Cγ-Cδ double
bond of the butatrienylidene ligand of the cation [Ru-
(η5-C5H5)(CdCdCdCH2)(PPh3)2]+.25
Isomer Z (2a ) was obtained as a pure crystalline solid
by crystallization in dichloromethane-diethyl ether and
characterized by an X-ray crystallographic study. A view
of the molecular geometry of the cation 2a is shown in
Figure 1. Selected bond distances and angles are listed
in Table 1.
The geometry around the ruthenium center is close
to octahedral, with the cyclopentadienyl ligand occupy-
ing one face of the octahedron, and the angles formed
by the triisopropylphosphine, the carbonyl group, and
the unsaturated η1-carbon ligand are close to 90°.
The atoms C(16), C(17), C(18), N(1), C(37), and N(2)
of the unsaturated η1-carbon ligand, which form a
2-iminium-3-methyleneazetidine skeleton, are almost
planar. The deviations from the plane are -0.049(4)
[C(16)], 0.026(4) [C(17)], 0.054(4) [C(18)], -0.055(3)
[N(1)], 0.027(4) [C(37)], and 0.013 (3) [N(2)] Å.
121.5(2)
122.6(2)
135.3(3)
C(37)-N(2)-C(38) 123.9(3)
C(37)-C(17)-C(16) 139.3(4)
C(16)-C(17)-C(18) 133.8(3)
C(17)-C(37)-N(2) 135.7(4)
C(17)-C(18)-C(19) 116.6(3)
C(37)-C(17)-C(18)
86.7(3)
C(37)-N(1)-C(31) 134.0(3)
aG(1) is the midpoint of the C(1)-C(5) Cp ligand.
The Ru-C(16) distance [2.070(4) Å] lies within the
range 2.03(1)26-2.141(3)27 Å, where a Ru-C(sp2) single
bond has been proposed to exist. The C(16)-C(17)
distance of 1.346(5) Å, which is about 0.02 Å longer than
the carbon-carbon double bond length found in 4-ben-
zylidene-1-tert-butyl-2-(tert-butylimino)-3-phenylazeti-
dine [1.327(2) Å],28 is in agreement with the sample
mean of carbon-carbon bond lengths for double bonds
[1.32(1) Å].29 The angle Ru-C(16)-C(17) is 135.3(3)°.
The endocyclic N(1)-C(37) [1.340(5) Å] and exocyclic
C(37)-N(2) [1.369(5) Å] bond lengths indicate electron
delocalization over these three atomic centers, while the
C(17)-C(18) [1.580(5) Å] and C(18)-N(1) [1.545(5) Å]
distances reveal the tension within the four-membered
heterocycle. The C(17)-C(18) bond length is about 0.1
Å longer than the sample mean of the C(sp2)-C(sp3)
(26) Torres, M. R.; Vegas, A.; Santos, A.; Ros, J . J . Organomet. Chem.
1987, 326, 413.
(27) Bohanna, C.; Esteruelas, M. A.; Lahoz, F. J .; On˜ate, E.; Oro,
L. A. Organometallics 1995, 14, 4685.
(28) Fuks, R.; Baudoux, D.; Piccinni-Leopardi, C.; Declercq, J .-P.;
Van Meerssche, M. J . Org. Chem. 1988, 53, 18.
(25) Bruce, M. I.; Hinterding, P.; Ke, M.; Low, P. J .; Skelton, B. W.;
White, A. H. Chem. Commun. 1997, 715.
(29) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson,
D. G.; Taylor, R. J . Chem. Soc., Dalton Trans. 1989, S1.

Novel Unsaturated η1-Carbon Ligands
Organometallics, Vol. 18, No. 9, 1999 1609
single-bond distance [1.48(3) Å]29 and the C(18)-N(1)
bond length is about 0.06 Å longer than the single bond
N(1)-C(31) distance [1.482(5) Å]. The angles within the
heterocycle are between 84.0(2)° and 96.1(3)°. A similar
situation has been observed in the organic salts 1-ben-
zhydrylazetidindimethyliminium chloride30 and trans-
2-dimethylamino-3-p-nitrophenyl-1,4-diphenyl-3,4-di-
hydro-1-azetium perchlorate.31
1
In the H NMR spectrum of 2a , the most noticeable
resonance is a doublet [J (PH) ) 5.9 Hz] at 9.71 ppm,
corresponding to the RuCHd proton. In agreement with
the structure shown in Figure 1, this resonance shows
NOE effect (3%) with the resonance of the ortho-phenyl
protons. In the 13C{1H} NMR spectrum, the resonance
due to C(16) appears at 182.9 ppm as a doublet with a
P-C coupling constant of 13.9 Hz, whereas the reso-
nances corresponding to C(17), C(18), and C(37) appear
at 142.4, 86.4, and 185.5 ppm, respectively, as singlets.
In the 1H NMR spectrum of 2b, the RuCHd reso-
nance is observed at 10.27 ppm as a doublet with a P-H
coupling constant of 6.2 Hz. In agreement with the
E-stereochemistry around the RuCHdC double bond,
in this case, a NOE effect between the RuCH resonance
and that corresponding to the ortho-phenyl protons is
not observed. In the 13C{1H} NMR spectrum, the
RuCHd resonance appears at 180.4 ppm as a doublet
with a P-C coupling constant of 12.7 Hz, and the
resonances corresponding to dC, CPh2, and N+C+N
carbon atoms are observed at 144.1, 89.0, and 188.2
ppm, respectively, as singlets.
F igu r e 2. 1H-13C HETCOR NMR spectrum of the com-
plex Ru(η5-C5H5){(Z)-CHdCCPh2N(Cy)CdNCdCH(CH2)3C-
H2}(CO)(PPri ) (6).
3
tion of the RuCHd resonance produces a 3.45% NOE
effect on the resonance of the ortho-phenyl protons. The
selective formation of the Z-isomer of 6 appears to be
related with the steric requirements of the triisopropy-
lphosphine and azetidinylidenemethyl ligands, which
are mutually cis disposed. Thus, as can be viewed in
Figure 1, both phenyl groups of the unsaturated η1-
carbon ligand are away from the bulky phosphine
ligand.
The 13C{1H} NMR spectrum of 6 in benzene-d6
contains at 141.8 ppm a doublet with a P-C coupling
constant of 15.8 Hz, and at 154.6, 149.3, 144.0, 105.2,
79.7, and 57.0 ppm singlets. Figure 2 shows the 1H-
13C HETCOR NMR spectrum in benzene-d6. In this
spectrum, the most noticeable correlations are observed
at 141.8(13C)-7.39(1H), 105.2(13C)-5.23(1H), and 57.0-
(13C)-3.94(1H) ppm. On the basis of these correlations,
we have assigned the resonances at 141.8, 105.2, and
57.0 ppm to the RuCHd, -CHd, and NCH carbon
atoms, respectively. The resonance at 149.3 ppm was
assigned to the olefinic dC-N carbon atom of the
cyclohexenyl group, whereas the resonances at 154.6,
144.0, and 79.7 ppm were assigned to the N-CdN, d
C, and -CPh2 carbon atoms of the azetidine skeleton,
by comparison of the 13C{1H} NMR spectrum of 6 with
those of organic methyleneazetidines.4
Treatment of the isomeric mixture of 2 with sodium
methoxide in tetrahydrofuran at room temperature
affords the iminoazetidinylidenemethyl complex Ru(η5-
C5H5){(Z)-CHdCCPh2N(Cy)CdNCdCH(CH2)3CH2}(CO)-
(PPri ) (6) as a result of the deprotonation of a CH2-
3
CdN proton of the cyclohexylidene group of 2 (eq 2).
2. Syn t h esis of Hexa h yd r oqu in olin ylid en em -
eth yl Com p lexes. While in organic chemistry much of
the effort involving the azetidine nucleus has been
directed to its synthesis, few examples of rearrange-
ments of the azetidine ring are known. Dialkyl aze-
tidines afford olefins through a Hoffmann type elimi-
nation.32 Amino alcohols have been obtain by hydrogen-
olysis of 4-arylazetidines, as well as from bis-azetidines.5
Different Pd and Pt complexes are known to promote
the azetidine ring breakage to yield diamine complexes33
and aliphatic polyamines.34 Recently, Alcaide et al.35
have observed that, in the presence of Et2AlCl, some
azetidines give olefins or alternatively pyrrolidines. It
Complex 6 was obtained as a white solid in 74% yield
and characterized by MS, elemental analysis, IR, H,
1
31P{1H}, and 13C{1H} NMR spectroscopies. In the 1H
NMR spectrum, in dichloromethane-d2, the most notice-
able resonances are a doublet [J (PH) ) 3.3 Hz] at 7.02
ppm, a triplet [J (HH) ) 3.7 Hz] at 4.89 ppm, and a triple
triplet [J (HH) ) 12.0 and 3.6 Hz] at 3.68 ppm, which,
1
on the basis of a H-1H COSY spectrum, were assigned
to the RuCHd, -CHdCN, and NCH- protons, respec-
tively.
Although from the isomeric mixture of 2, two stere-
ochemistries at the carbon-carbon double bond of the
unsaturated η1-carbon ligand of 6 could be formed
according to eq 2, E and Z, only one of them, Z, is
obtained. This is supported by the fact that the irradia-
(32) De Kimpe, N.; Tehrani, K. A.; Fonck, G. J . Org. Chem. 1996,
61, 6500.
(33) Bertani, R.; Mozzon, M.; Benetollo, F.; Bombieri, G.; Michelin,
R. A. J . Chem. Soc., Dalton Trans. 1990, 1197.
(34) Murahashi, S.-I.; Yoshimura, N.; Tsumiyama, T.; Kojima, T.
J . Am. Chem. Soc. 1983, 105, 5002.
(30) Stierli, F.; Prewo, R.; Bieri, J . H.; Heimgartner, H. Helv. Chim.
Acta 1984, 67, 927.
(31) Lindley, P. F.; Walton, A. R.; Boyd, G. V.; Nicolaou, G. A. Acta
Crystallogr., Sect. C 1988, 44, 885.
(35) Alcaide, B.; Salgado, N. R.; Sierra, M. A. Tetrahedron Lett. 1998,
39, 467.

1610 Organometallics, Vol. 18, No. 9, 1999
Esteruelas et al.
Sch em e 2
has been proposed that the key step for the latter
reactions is the coordination of the lone electron pair of
the azetidine nucleus to the Lewis acid, Et2AlCl, which
promotes the C-N bond breakage. To investigate the
possible rearrangements of the azetidine nucleus of 6,
we carried out the reaction of this complex with HBF4.
Treatment of yellow diethyl ether solutions of 6 with
1 equiv of HBF4‚OEt2 at 193 K leads after 1 h to the
iminiumazetidinylidenemethyl complex [Ru(η5-C5H5)-
F igu r e 3. 1H-1H COSY NMR spectrum of the complex
[Ru (η5 -C5 H 5 ){(Z)-CH dCCP h 2 N (Cy)CdN (H )CdCH -
(CH2)3CH2}(CO)(PPri )]BF4 (7) showing the region between
3
8.9 and 5.9 ppm.
temperature, it evolves into a 9:1 mixture of a new
isomer [Ru(η5-C5H5){(Z)-CHdCCPh2C(CH2)4CN(H)dC-
NHCy}(CO)(PPri )]BF4 (8) and a minor product, which
could not be identified.
When a dichloromethane solution of the above -men-
tioned mixture was passed through an Al2O3 (neutral,
activity grade V) column, the hexahydroquinolinylidene-
{(Z)-CHdCCPh2N(Cy)CdN(H)CdCH(CH2)3CH2}(CO)-
3
(PPri )]BF4 (7), as a result of the protonation of the
3
exocyclic nitrogen atom of the unsaturated η1-carbon
ligand of 6 (Scheme 2).
Complex 7 was isolated as a yellow solid in 68% yield
1
and characterized by elemental analysis, IR, H, 31P-
methyl complex Ru(η5-C5H5){(Z)-CHdCCPh2C(CH2)4C-
1
{1H}, and 13C{1H} NMR spectroscopies. The H NMR
NdCNHCy}(CO)(PPri ) (9) was obtained, as a result of
spectrum of this complex in chloroform-d shows char-
acteristic resonances at 8.78, 8.08, 5.87, and 3.77 ppm.
The resonance at 8.78 ppm appears as a doublet with a
P-H coupling constant of 7.8 Hz and was assigned to
the RuCHd proton, whereas the resonances at 8.08 and
5.87 ppm appear as broad signals and were assigned to
the NH and dCH- protons, respectively. The resonance
at 3.77 ppm is observed as a broad triplet J (HH) ) 11.4
Hz) and was assigned to the NCH proton.
3
the deprotonation of the endocyclic nitrogen atom of 8.
The protonation of 9 again affords 8, which was isolated
as a pure yellow solid in 65% yield with regard to 7.
This reaction is reversible. Thus, the treatment of 8 with
sodium methoxide in tetrahydrofuran at room temper-
ature gives 9 (Scheme 2).
1
In the H NMR spectrum of 8, the RuCH resonance
appears at 9.04 ppm as a doublet with a P-H coupling
constant of 11.4 Hz, whereas the NH resonances are
observed at 8.77 and 8.29 ppm. The first one, assigned
to the exocyclic NH, appears as a doublet with a H-H
coupling of 8.4 Hz. According to the 1H-1H COSY
spectrum, the multiplicity of this signal is due to the
spin nuclear coupling with the NCH proton of the
cyclohexyl group, which gives rise to a multiplet at 3.79
ppm. The endocyclic NH resonance appears as a broad
signal. In the 13C{1H} NMR spectrum, the RuCHd
resonance is observed at 171.9 ppm as a doublet with a
P-C coupling constant of 11.9 Hz, whereas the Câ atom
of the RuCHdC unit gives rise to a singlet at 129.3 ppm.
Complex 9 was obtained as pale yellow crystals in
68% yield, with regard to 7, and characterized by
The protonation of the exocyclic nitrogen atom instead
of the endocyclic nitrogen atom of 6 was inferred on the
1
basis of a H-1H COSY spectrum, which shows nuclear
spin coupling between the resonances at 8.08 and 5.87
ppm (Figure 3).
In the 13C{1H} NMR spectrum, the most noticeable
resonances are observed at 167.5 [d, J (PC) ) 13.8 Hz],
125.3(s), and 59.3(s) ppm and were assigned to the
RuCHd, dCH, and NCH carbon atoms, respectively, on
1
the basis of a H-13C HETCOR NMR spectrum.
Complexes 2 and 7 are isomers. Formally, complex 7
is a result of the migration of a CH2CdN proton of the
cyclohexylidene group to the exocyclic nitrogen atom of
2. This isomerization is not spontaneous even at high
temperature in chloroform. The isomerization of 7 to 2
is also not observed. In dichloromethane and in chloro-
form, complex 7 is stable at low temperature. At room
1
elemental analysis, IR, H, 31P{1H}, and 13C{1H} NMR
spectroscopies, and X-ray diffraction. A view of the

Novel Unsaturated η1-Carbon Ligands
Organometallics, Vol. 18, No. 9, 1999 1611
Sch em e 3
Sch em e 4
F igu r e 4. Molecular diagram of the complex Ru(η5-C5H5)-
{(Z)-CHdCCPh2C(CH2)4CNdCNHCy}(CO)(PPri3) (9). Ther-
mal ellipsoids are shown at 50% probability.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) of th e Com p lex Ru (η5-C5H5){(Z)-
CHdCCP h 2C(CH2)4CNdCNHCy}(CO)(P P r i3) (9)
found between the exocyclic nitrogen atom N(1) and the
cyclohexyl group in 2a [1.482(5) Å]. However, the C(3)-
N(1) distance is 1.368(5) Å, the same as the separation
found between the atoms N(2) and C(37) of 2a . This
suggests that for an adequate description of the bonding
situation in the aminohexahydroquinolinylidenemethyl
ligand a second resonance form such as b (Scheme 3)
should be considered. This is also supported by the value
of the C(3)-N(2) distance [1.300(5) Å], which is slightly
longer than the N-C double bond found in Schiff bases,
hydrazones, and related compounds (about 1.29 Å), and
by the value of the C(3)-N(1)-C(4) angle, which is
123.3(3)°.
Ru-P
2.3234(11)
1.829(5)
2.113(4)
1.339(5)
1.499(5)
1.368(5)
1.300(5)
1.465(5)
1.558(5)
1.545(5)
C(16)-C(17)
C(16)-C(15)
C(15)-C(10)
C(10)-N(2)
C(10)-C(11)
C(11)-C(12)
C(12)-C(13)
C(13)-C(14)
C(14)-C(15)
1.556(5)
1.544(5)
1.344(5)
1.418(4)
1.515(5)
1.526(5)
1.518(6)
1.536(5)
1.519(5)
Ru-C(43)
Ru-C(1)
C(1)-C(2)
C(2)-C(3)
C(3)-N(1)
C(3)-N(2)
N(1)-C(4)
C(2)-C(16)
C(16)-C(23)
P-Ru-C(43)
90.17(14) C(2)-C(3)-N(2)
90.27(10) C(3)-N(1)-C(4)
122.8(3)
123.3(3)
107.7(3)
116.4(3)
113.1(3)
123.2(3)
P-Ru-C(1)
P-Ru-G(1)a
127.9(2)
C(3)-C(2)-C(16)
In the 1H NMR spectrum of 9, the most noticeable
resonance is that corresponding to the NH proton, which
appears at 5.37 ppm as a doublet with a H-H coupling
constant of 8.1 Hz, by nuclear spin coupling with the
NCH proton of the cyclohexyl group, according to the
1H-1H COSY spectrum. In the 13C{1H} NMR spectrum,
the RuCHd resonance is observed at 136.2 ppm as a
doublet with a P-C coupling constant of 11.5 Hz,
whereas the Câ atom of the RuCHdC unit and the
N-CdN carbon atom give rise to singlets at 116.3 and
158.2 ppm, respectively.
In a similar manner to 2, 7, and 8, complexes 9 and
6 are isomers. Although the isomerization of 6 into 9 is
not spontaneous, the sequence of reactions shown in
Scheme 2 indicates that it can be easily carried out by
protonation of 6 and subsequent deprotonation of 8. In
addition, it should be noted that during the process the
stereochemistry at the C-C double bond of the RuCHd
C unit is retained.
Scheme 4 shows a possible mechanism for the isomer-
ization of 6 to 9, where the species 7 and 8 are
intermediates. The process involves the split of the
N-CPh2 bond of the azetidine skeleton and the subse-
quent electrophilic attack of the resulting carbocation
to the olefin of the cyclohexenyl group. Although, as a
result of the protonation of 6, we have isolated only 7,
in solution, this compound should be in equilibrium with
a nondetectable concentration of its tautomer 7a , which
C(43)-Ru-C(1)
C(43)-Ru-G(1)a
C(1)-Ru-G(1)a
Ru-C(1)-C(2)
C(1)-C(2)-C(3)
C(1)-C(2)-C(16)
93.04(17) C(3)-N(2)-C(10)
128.0(3)
117.1(2)
131.2(3)
125.9(3)
126.4(3)
N(2)-C(10)-C(11)
N(2)-C(10)-C(15)
C(10)-C(11)-C(12) 112.9(3)
C(10)-C(15)-C(14) 121.7(3)
C(10)-C(15)-C(16) 118.5(3)
C(11)-C(10)-C(15) 123.5(3)
C(14)-C(15)-C(16) 119.6(3)
C(2)-C(16)-C(15) 106.6(3)
C(2)-C(3)-N(1)
117.4(3)
a
G(1) is the midpoint of the C(38)-C(42) Cp ligand.
molecular geometry is shown in Figure 4. Selected bond
distances and angles are listed in Table 2.
As for 2a , the geometry around the ruthenium center
is close to octahedral with the cyclopentadienyl ligand
occupying one face of the octahedron, and the angles
formed by the triisopropylphosphine, the carbonyl group,
and the hexahydroquinolinylidenemethyl ligand are
close to 90°.
The Ru-C(1) distance [2.113(4) Å] is about 0.04 Å
longer than the related parameter in 2a , while the
C(1)-C(2) distance [1.339(5) Å] is statistically identical
with the related bond length in 2a .
With regard to the aminohexahydroquinolinylidene
skeleton, the difference between the C(3)-N(1) and
N(1)-C(4) distances is noticeable. The separation be-
tween the exocyclic nitrogen atom N(1) and the C(4)
atom of the cyclohexyl group [1.464(5) Å] agrees well
with a C-N single bond and is similar to the separation

1612 Organometallics, Vol. 18, No. 9, 1999
Esteruelas et al.
0.47 mmol) in 10 mL of dichloromethane at room temperature
was treated with N,N ′-dicyclohexylcarbodiimide (99 mg, 0.48
mmol). The mixture was stirred for 5 h, and the color changed
from dark red to orange. Solvent was evaporated in vacuo, and
the residue was washed with tetrahydrofuran, to afford a
yellow solid. Yield: 349 mg (88%). Anal. Calcd for C43H58BF4N2-
OPRu: C, 61.64; H, 6.98; N, 3.34. Found: C, 61.61; H, 6.97;
N, 3.45. IR (Nujol, cm-1): ν(CO) 1927 (vs), ν(CdN) 1679 (s),
ν(CdC) 1528 (s), ν(Ph) 1607 (w), ν(BF4) 1053 (vs, br).
Sp ectr oscop ic Da ta for 2a . 1H NMR (300 MHz, 293 K,
CDCl3): δ 9.71 (d, 1H, J (PH) ) 5.9, Ru-CHd), 7.60-7.10 (m,
10H, Ph), 5.23 (s, 5H, Cp), 3.43 (m, 1H, NCH), 2.60 (m, 4H,
CH2), 2.10-1.60 (m, 19H, CH2 + PCHCH3), 0.96 (dd, 9H,
J (HH) ) 7.2, J (PH) ) 14.7, PCHCH3), 0.85 (dd, 9H, J (HH) )
7.1, J (PH) ) 13.5, PCHCH3). 31P{1H} NMR (121.4 MHz, 293
K, CDCl3): δ 68.3 (s). 13C{1H} NMR (75.4 MHz, 293 K, CDCl3,
plus HETCOR): δ 206.1 (d, J (PC) ) 17.6, CO), 185.5 (s,
N+C+N), 182.9 (d, J (PC) ) 13.9, Ru-CHd), 172.0 (s, CdN),
142.4 (s, Ru-CHdC), 138.1, 136.9, (both s, CipsoPh), 129.9,
129.4, 128.8, 128.3, 125.9 (all s, Ph), 86.7 (s, Cp), 86.4 (s, CPh2),
56.8 (s, NCH), 38.2, 38.1, 32.2, 30.0, 26.5, 26.3, 25.1, 25.0, 24.8,
23.9 (all s, CH2), 27.2 (d, J (PC) ) 23.8, PCHCH3), 19.4, 18.8
(both s, PCHCH3).
Sp ectr oscop ic Obser ved Da ta for 2b. 1H NMR (300
MHz, 293 K, CDCl3): δ 10.27 (d, 1H, J (PH) ) 6.2, Ru-CHd),
7.60-7.10 (m, 10H, Ph), 4.77 (s, 5H, Cp), 3.25 (m, 1H, NCH).
31P{1H} NMR (121.4 MHz, 293 K, CDCl3): δ 69.2 (s). 13C{1H}
NMR (75.4 MHz, 293 K, CDCl3, plus HETCOR): δ 205.6 (d,
J (PC) ) 16.8, CO), 188.2 (s, N+C+N), 180.4 (d, J (PC) ) 12.7,
Ru-CHd), 161.4 (s, CdN), 144.1 (s, Ru-CHdC), 135.9, 135.8,
(both s, CipsoPh), 129.5, 129.0, 128.7, 128.4 (all s, Ph), 89.0 (s,
CPh2), 86.3 (s, Cp), 55.9 (s, NCH), 37.9, 31.4, 31.2, 28.2, 24.9,
24.5, 24.0 (all s, CH2), 29.0 (d, J (PC) ) 23.2, PCHCH3), 19.5,
19.2 (both s, PCHCH3).
is produced by hydrogen transfer from the exocyclic
nitrogen atom to the endocyclic nitrogen atom. Thus,
the coordination of the lone electron pair of the azetidine
nitrogen atom to the proton should promote the N-CPh2
bond breakage to form the carbocation, in agreement
with Alcaide’s proposal.35
With regard to the result of the attack of the carboca-
tion to the olefin of the cyclohexenyl group, it should be
mentioned that the formation of the six-membered
heterocycles of 8 and 9 is determined by the disposition
of the substituents at the nitrogen atom of the imine
group, during the process. Thus, using a molecular
model, it can be easily established that a change in the
position of the substituents at this nitrogen atom does
not allow the formation of 8. In other words, the
rearrangement of the azetidine skeleton to the six-
membered heterocycle is due not only to the presence
of the cyclohexenylimino substituent in the azetidine
but also to the stereochemistry at the CdN double bond.
Con clu d in g Rem a r k s
This study has revealed that the transition-metal
allenylidene compounds are useful substrates to gener-
ate an azetidine skeleton. Thus, the addition of dicy-
clohexylcarbodiimide to the complex [Ru(η5-C5H5)(Cd
CdCPh2)(CO)(PPri )]BF4, followed by the deprotonation
3
of the resulting cation, affords the cyclohexenylimi-
noazetidinylidenemethyl complex Ru(η5-C5H5){(Z)-CHd
CCPh2N(Cy)CdNCdCH(CH2)3CH2}(CO)(PPri ), as a re-
3
sult of a formal [2+2] cycloaddition of one of the two
carbon-nitrogen double bonds of the dicyclohexylcar-
bodiimide to the Câ-Cγ double bond of the allenylidene
ligand, and an Alder-ene reaction, where the CR-Câ
double bond acts as an enophile.
In solution and in the solid state, this azetidinyliden-
emethyl derivative is stable. However, in the presence
of acid, it rearranges to the thermodynamically more
stable hexahydroquinolinylidenemethyl isomer Ru(η5-
P r ep a r a tion of Ru (η5-C5H5){(Z)-CHdCCP h 2N(Cy)CdN-
CdCH(CH2)3CH2}(CO)(P P r i3) (6). A suspension of 2 (324 mg,
0.41 mmol) in 15 mL of tetrahydrofuran at room temperature
was treated with sodium methoxide (22 mg, 0.41 mmol), and
the mixture was stirred for 1 h. The color turned from yellow
to pale yellow, and the solvent was removed in vacuo. A 15
mL portion of toluene was added, and the mixture was filtered
to eliminate sodium tetrafluoroborate. The solution was
concentrated to ca. 1 mL, and 20 mL of pentane was carefully
added. The mixture was stored at 241 K to afford 6 as white
crystals. Yield: 216 mg (74%). Anal. Calcd for C43H57N2-
OPRu: C, 68.86; H, 7.66; N, 3.74. Found: C, 68.40; H, 7.52;
N, 3.63. IR (Nujol, cm-1): ν(CO) 1909 (vs), ν(CdN) 1673 (vs),
C5H 5){(Z)-CH dCCP h 2C(CH 2)4CN dCN H Cy}(CO)-
(PPri ), as a consequence of the split of the N-CPh2
3
bond of the azetidine skeleton and the subsequent
attack of the CPh2 carbon atom to the olefin of the
cyclohexenyl group. The formation of the six-membered
heterocycle is the result of two factors: (i) the presence
of a cyclohexenylimino group bonded to the azetidine
skeleton and (ii) the stereochemistry at the CdN double
bond.
1
ν(CdC) 1599 (s). H NMR (300 MHz, 293 K, CD2Cl2): δ 7.60-
7.20 (m, 10H, Ph), 7.02 (d, 1H, J (PH) ) 3.3, Ru-CHd), 5.33
(s, 5H, Cp), 4.89 (t, 1H, J (HH) ) 3.7, CdCH), 3.68 (tt, 1H,
J (HH) ) 12.0, J (HH) ) 3.6, NCH), 2.14 (m, 4H, CH2), 1.80-
0.58 (m, 17H, CH2 + PCHCH3), 0.92 (dd, 9H, J (HH) ) 7.4,
J (PH) ) 14.6, PCHCH3), 0.89 (dd, 9H, J (HH) ) 7.4, J (PH) )
12.8, PCHCH3). 31P{1H} NMR (121.4 MHz, 293 K, CD2Cl2): δ
73.7 (s). 13C{1H} NMR (75.4 MHz, 293 K, C6D6, plus HET-
COR): δ 208.1 (d, J (PC) ) 18.9, CO), 154.6 (s, N-CdN), 149.3
(s, NCdCH), 145.2, 145.1 (both s, CipsoPh), 144.0 (s, Ru-CHd
C), 141.8 (d, J (PC) ) 15.8, Ru-CHd), 130.9, 127.9, 127.7,
127.6, 127.5, 126.0 (all s, Ph), 105.2 (s, NCdCH), 86.8 (s, Cp),
79.7 (s, CPh2), 57.0 (s, NCH), 32.1, 30.8, 30.3 27.2 (all s, CH2),
27.0 (d, J (PC) ) 23.3, PCHCH3), 26.7, 26.1, 25.3, 23.9, 23.4
(all s, CH2), 20.1, 19.1 (both s, PCHCH3). MS (FAB+): m/z )
751 ([M + 1]+).
Exp er im en ta l Section
All reactions were carried out with rigorous exclusion of air
using Schlenk-tube techniques. Solvents were dried by the
usual procedures and distilled under argon prior to use. The
starting material [Ru(η5-C5H5)(CdCdCPh2)(CO)(PPri3)]BF4 (1)
was prepared by the published method.15
In the NMR spectra, chemical shifts are expressed in ppm
downfield from Me4Si (1H and 13C) and 85% H3PO4 (31P).
Coupling constants, J , are given in hertz.
P r epar ation of [Ru (η5-C5H5){(Z)-CHdCCP h 2N(Cy)CdN-
P r epar ation of [Ru (η5-C5H5){(Z)-CHdCCP h 2N(Cy)+C+
NdC(CH2)4CH2}(CO)(P P r i3)]BF 4 (2a ) a n d [Ru (η5-C5H5){-
(H)CdCH(CH2)3CH2}(CO)(P P r i3)]BF 4 (7). A pale yellow
solution of 6 (102 mg, 0.14 mmol) in 15 mL of diethyl ether at
193 K was treated with tetrafluoroboric acid (19 µL, 57% in
Et2O, 0.14 mmol). The mixture was stirred for 1 h, while
temperature was slowly increased to 233 K, to afford a pale
(E)-CH dCCP h 2N(Cy)+C+NdC(CH 2)4CH 2}(CO)(P P r i3)]-
BF 4 (2b) a t a 4 to 1 Mola r Ra tio. A solution of 1 (300 mg,

Novel Unsaturated η1-Carbon Ligands
Organometallics, Vol. 18, No. 9, 1999 1613
Ta ble 3. Cr ysta l Da ta a n d Da ta Collection a n d
yellow solid, which was washed with cold diethyl ether.
Yield: 80 mg (68%). Anal. Calcd for C43H58BF4N2OPRu: C,
61.64; H, 6.98; N, 3.34. Found: C, 61.38; H, 6.59; N, 3.42. IR
(Nujol, cm-1): ν(NH) 3296 (w), ν(CO) 1921 (vs), ν(CdC) 1677
Refin em en t for Com p lexes [Ru (η5-C5H5){(Z)-
CHdCCP h 2N(Cy)+C+NdC(CH2)4CH2}(CO)-
(P P r i3)]BF 4 (2a ) a n d Ru (η5-C5H5){(Z)-
1
(w), ν(CdN) 1643 (s), ν(Ph) 1594 (m), ν(BF4) 1050 (vs, br). H
CHdCCP h 2C(CH2)4CNdCNHCy}(CO)(P P r i3) (9)
NMR (300 MHz, 253 K, CDCl3): δ 8.78 (d, 1H, J (PH) ) 7.8,
Ru-CHd), 8.08 (br, 1H, NH), 7.52-7.22 (m, 10H, Ph), 5.87
(br, 1H, NCdCH), 5.22 (s, 5H, Cp), 3.77 (br t, 1H, J (HH) )
11.4, NCH), 2.30-0.33 (m, 18H, CH2), 1.60 (m, 3H, PCHCH3),
0.85 (dd, 9H, J (HH) ) 7.2, J (PH) ) 14.4, PCHCH3), 0.83 (dd,
9H, J (HH) ) 6.7, J (PH) ) 13.6, PCHCH3). 31P{1H} NMR (121.4
MHz, 253 K, CD2Cl2): δ 68.3 (s). 13C{1H} NMR (75.4 MHz, 253
K, CDCl3, plus HETCOR): δ 208.3 (d, J (PC) ) 18.0, CO), 167.5
(d, J (PC) ) 13.8, Ru-CHd), 162.8 (s, N-CdN), 140.4 (s, NCd
CH), 138.8, 137.1, (both s, CipsoPh), 131.2 (s, Ru-CHdC), 130.0,
129.5, 128.6, 128.3, 127.8, 126.0 (all s, Ph), 125.3 (s, NCdCH),
86.8 (s, CPh2), 86.4 (s, Cp), 59.3 (s, NCH), 32.0, 28.6, 28.0 (all
s, CH2), 26.5 (d, J (PC) ) 23.9, PCHCH3), 25.4, 25.2, 24.5, 24.2,
21.8, 21.0 (all s, CH2), 19.4 (s, PCHCH3), 18.6 (d, J (PC) ) 1.9,
PCHCH3).
2a
9
formula
mol wt
C43H58BF4N2OPRu C43H57N2OPRu
837.76
749.95
color, habit
yellow, irregular
prism
yellow, rectangular
plate
cryst size, mm
space group
a, Å
b, Å
c, Å
0.83 × 0.55 × 0.29
monoclinic, P21/n
11.165(1)
21.762(2)
17.577(2)
90
101.295(7)
90
4188.0(7)
4
1.329
0.465
θ/2θ
3 e 2θ e 50
200.0(2)
9096
0.53 × 0.33 × 0.10
triclinic, P1h
9.870(1)
13.770(1)
16.110(2)
99.194(7)
102.323(8)
109.343(6)
1954.2(3)
2
1.274
0.476
θ/2θ
3 e 2θ e 50
223.0(2)
9697
R, deg
â, deg
γ, deg
V, Å3
P r epar ation of [Ru (η5-C5H5){(Z)-CHdCCP h 2C(CH2)4CN-
(H)dCNHCy}(CO)(P P r i3)]BF 4 (8). A pale yellow diethyl
Z
D(calcd), g cm-3
µ, mm-1
scan type
2θ range, deg
temp, K
ether solution of 9 (57 mg, 0.08 mmol) at room temperature
was treated with tetrafluoroboric acid (14 µL, 54% in Et2O,
0.08 mmol). Immediately, a pale yellow solid precipitated,
which was washed with diethyl ether. Yield: 59 mg (93%).
Anal. Calcd for C43H58BF4N2OPRu: C, 61.64; H, 6.98; N, 3.34.
Found: C, 61.54; H, 6.49; N, 3.16. IR (Nujol, cm-1): ν(NH)
3315, 3287 (both w), ν(CO) 1917 (vs), ν(CdN) 1628 (s), ν(Cd
C) 1537 (m), ν(BF4) 1074, 1051, 1013 (all s). 1H NMR (300 MHz,
273 K, CDCl3): δ 9.04 (d, 1H, J (PH) ) 11.4, Ru-CHd), 8.77
(d, 1H, J (HH) ) 8.4, CHNH), 8.29 (br s, 1H, NH), 7.26-6.88
(10H, Ph), 4.95 (s, 5H, Cp), 3.79 (m, 1H, CHNH), 2.58-0.79
(m, 18H, CH2), 1.97 (m, 3H, PCHCH3), 0.96 (dd, 9H, J (HH) )
7.2, J (PH) ) 12.9, PCHCH3), 0.95 (dd, 9H, J (HH) ) 7.5, J (PH)
) 15.9, PCHCH3). 31P{1H} NMR (121.4 MHz, 273 K, CDCl3):
δ 68.4 (s). 13C{1H} NMR (75.4 MHz, 273 K, CDCl3, plus
HETCOR): δ 206.2 (d, J (PC) ) 20.4, CO), 171.9 (d, J (PC) )
11.9, Ru-CHd), 155.1 (s, N-CdN), 144.5 (s, NCdC), 142.6,
141.5 (both s, CipsoPh), 129.3 (s, Ru-CHdC), 130.4, 128.7, 128.2,
127.6, 126.9, 126.5 (all s, Ph), 121.6 (s, NCdC), 86.0 (s, Cp),
62.2 (s, CPh2), 50.5 (s, NCH), 32.2, 31.0, 28.6 (all s, CH2), 26.4
(d, J (PC) ) 23.0, PCHCH3), 25.6, 25.0, 23.9, 23.7, 22.7, 21.8
(all s, CH2), 19.8 (s, PCHCH3), 18.8 (d, J (PC) ) 1.9, PCHCH3).
no. of data collected
no. of unique data
7363 (Rint ) 0.0175) 6825 (Rint ) 0.0219)
no. of params refined 517
436
R1 (F2 > 2σ(F2))
0.0488
0.1834
0.966
0.0489
0.1528
0.800
a
b
wR2 (all data)
S
c (all data)
R1(F) ) ∑||Fo| - |Fc||/∑|Fo|. wR2(F 2) ) [∑[w(Fo - Fc2)2]/
a
b
2
∑[w(Fo2)2]]1/2; w-1 ) [σ2(Fo2) + (aP)2 + bP], where P ) [max(Fo
,
2
0) + 2Fc2)]/3 (2a , a ) 0.0824, b ) 10.99; 9, a ) 0.1249, b ) 5.38).
c S ) [∑[w(Fo - Fc2)2]/(n - p)]1/2, where n is the number of
2
reflections and p the number of refined parameters.
CPh2), 48.9 (s, NCH), 32.8, 32.3, 31.4, 30.3 (all s, CH2), 26.0
(d, J (PC) ) 22.1, PCHCH3), 25.9, 25.0, 24.9, 23.6, 23.5 (all s,
CH2), 19.9, 19.1 (both s, PCHCH3).
Cr ysta l Da ta for 2a a n d 9. Crystals suitable for the X-ray
diffraction study were obtained by slow diffusion of diethyl
ether into a concentrated solution of 2 in dichloromethane, or
9 in dichloromethane/pentane. A summary of crystal data and
refinement parameters is reported in Table 3. The yellow
crystals (0.83 × 0.55 × 0.29 (2a ) and 0.53 × 0.33 × 0.10 (9))
were glued on a glass fiber and mounted on a Siemens P4 four-
circle diffractometer, with graphite-monochromated Mo KR
radiation. A group of 29 reflections in the range 20° e 2θ e
30° (2a ) or 60 reflections in the range 20° e 2θ e 40° (9) were
carefully centered at 200 (2a ) or 223 K (9) and used to obtain
by least-squares methods the unit cell dimensions. Three
standard reflections were monitored at periodic intervals
throughout data collection: no significant variations were
observed. All data were corrected for absorption using a
semiempirical method.36 The structures were solved by direct
P r ep a r a tion of Ru (η5-C5H5){(Z)-CHdCCP h 2C(CH2)4C-
NdCNHCy}(CO)(P P r i3) (9). 7 (134 mg, 0.17 mmol) was
solved in 40 mL of dichloromethane at 203 K, and the yellow
solution was kept at 293 K for 5 days. The solution was
concentrated to ca. 1 mL and chromatographed on alumina.
A dichloromethane/tetrahydrofuran mixture (1:1) eluted a pale
yellow fraction. Solvent was removed in vacuo, and the residue
was extracted with three fractions of 20 mL of diethyl ether.
Solvent was removed in vacuo from the diethyl ether solution,
and the residue was washed with pentane to afford 9 as a
white solid. Yield: 80 mg (68%). Anal. Calcd for C43H57N2-
OPRu: C, 68.86; H, 7.66; N, 3.74. Found: C, 68.63; H, 7.82;
N, 3.98. IR (Nujol, cm-1): ν(NH) 3447 (w), ν(CO) 1909 (vs),
ν(CdN) 1585 (s), ν(CdC) 1501 (m). 1H NMR (300 MHz, 273
K, CDCl3): δ 7.18-7.02 (11 H, Ph + RuCH), 5.37 (d, 1H, J (HH)
) 8.1, NH), 5.00 (s, 5H, Cp), 3.70 (m, 1H, NCH), 2.31-0.79
(18H, CH2), 2.02 (m, 3H, PCHCH3), 1.02 (dd, 9H, J (HH) ) 6.6,
J (PH) ) 13.8, PCHCH3), 1.00 (dd, 9H, J (HH) ) 5.1, J (PH) )
12.6, PCHCH3). 31P{1H} NMR (121.4 MHz, 273 K, CDCl3): δ
71.4 (s). 13C{1H} NMR (75.4 MHz, 273 K, CDCl3, plus HET-
COR): δ 208.5 (d, J (PC) ) 20.7, CO), 158.2 (s, N-CdN), 148.9
(s, NCdC), 146.2, 145.7, (both s, CipsoPh), 141.8 (s, NCdC), 136.2
(d, J (PC) ) 11.5, Ru-CHd), 130.6, 130.1, 127.1, 127.0, 125.4,
125.1 (all s, Ph), 116.3 (s, Ru-CHdC), 86.3 (s, Cp), 63.4 (s,
methods37 and conventional Fourier techniques, and refined
2
by full-matrix least-squares on
F
(SHELXL93 (2a ) or
SHELXL97 (9)).38 The BF4 anion of 2a was found to be
disordered. It was modeled on the basis of two different
moieties sharing the central boron atom with complementary
occupancy factors refined to final values of 0.62(2) and 0.38-
(2). After anisotropic refinement of 9, only two peaks of high
electron density were observed (>1 e/Å3). The relative intensity
-
(36) North, A. C. T.: Phillips, D. C.: Mathews, F. S. Acta Crystallogr.
1968, A24, 351.
(37) Altamore, A.; Cascarano, G.; Giacovazzo, C. and Guagliardy,
A. J . Appl. Crystallogr. 1994, 27, 435.
(38) Sheldrick, G. SHELXL-93 and SHELXL-97, Programs for
Crystal Structure Refinement; Institu¨t fu¨r Anorganische Chemie der
Universita¨t, Go¨ttingen, Germany, 1993 and 1997.

1614 Organometallics, Vol. 18, No. 9, 1999
Esteruelas et al.
and geometry of these residuals (see Experimental Section)
suggested the presence of a second Ru and P atom correspond-
ing to a situation of static disorder affecting the molecule. The
small intensity of these peaks prevents finding a proper model
for this disorder. Anisotropic parameters were used in the last
cycles of refinement for all non-hydrogen atoms. The hydrogen
atoms were calculated and refined riding on their respective
carbon atoms with a common isotropic thermal parameter (2a )
or thermal parameters related to bonded atoms (9). Atomic
scattering factors, corrected for anomalous dispersion for Ru
and P, were implemented by the program. The refinement
parameters x ) 0.0824, y ) 10.99 (2a ) and x ) 0.1249, y )
5.38 (9).
Ack n ow led gm en t. We thank the DGES (Project
PB-95-0806, Programa de Promocio´n General del Cono-
cimiento) for financial support.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates, anisotropic and isotropic thermal parameters,
experimental details of the X-ray study, and bond distances
and angles. This material is available free of charge via the
Internet at http://pubs.acs.org.
2
converge to R1 ) 0.0488 (2a ) or 0.0489 (9) [F > 2σ(F 2)] and
wR2 (all data) ) 0.1834 (2a ) or 0.1528 (9), with weighting
OM9809522