Reactions of Os(η5-C5H5)Cl(PiPr 3)2 with NH=CPh2 and PPh3: The Unit Os(η5-C5H5) as Support for the Study of the Competitive Alkane-Arene Intramolecular C-H Activation

Article abstract of DOI:10.1021/om990538h

The cyclopentadienyl complex Os(η⁵-C₅H₅)Cl(P¹Pr ₃)₂ (1) reacts with benzophenone imine to give the cationic orthometalated derivative [OsH(η⁵5-C₅H₅){NH=C(Ph)C₆H ₄}(PⁱPr₃)]Cl (2a), containing the hydride ligand and the metalated phenyl group mutually cisoid disposed. Treatment of 2a with NaOCH₃ affords the neutral species Os(η⁵-C₅H₅){NH=C(Ph)C₆H ₄}(PPr₃) (3), which by protonation with HBF₄-OEt₂ gives [OsH(η⁵-C₅H₅){NH=C(Ph)C₆H ₄}-(PPr₃)]BF₄ (4). The structure of 4 was determined by an X-ray investigation. The geometry around the osmium center can be described as a four-legged piano-stool geometry, with the hydride ligand transoid disposed to the metalated phenyl group and cisoid to the NH of the imine. The separation between the hydride and the NH hydrogen atom is about 2.5 A?. Complex 1 also reacts with triphenylphosphine. In this case the reaction product is the mixed-ligand compound Os(η⁵-C₄H₅)Cl(PPh₃)(P ⁱPr₃) (5). Treatment of 5 with TlPF₆ affords the orthometalated triphenylphosphine derivative [OsH(η⁵-C₅H₅)(PPh₂C ₆H₄}(PⁱPr₃)]PF₆ (6). The structure of 6 was also determined by an X-ray investigation. As for 4, the geometry around the osmium center can be described as a four-legged piano-stool geometry with the hydride ligand and the metalated phenyl group in transoid positions. Treatment of 6 with NaOCH₃ produces the extraction of the hydride ligand and the formation of the neutral species Os(η⁵-C₅H₅)(PPh₂C ₆H₄)(PⁱPr₃) (7), which in methanol under reflux gives OsH(η⁵-C₅H₅)(PPh₃)-(PPr ₃) (8). Protonation of 8 with HBF₄-OEt₂ affords the cationic dihydride [OsH₂(η⁵-C₅H₅)(PPh ₃)(PⁱPr₃)]BF₄ (9).

Full text of DOI:10.1021/om990538h

Organometallics 2000, 19, 275-284
275
Rea ction s of Os(η5-C5H5)Cl(P iP r 3)2 w ith NHdCP h 2 a n d
P P h 3: Th e Un it Os(η5-C5H5)(P iP r 3) a s Su p p or t for th e
Stu d y of th e Com p etitive Alk a n e-Ar en e In tr a m olecu la r
C-H Activa tion
Miguel A. Esteruelas,*,‡ Enrique Gutie´rrez-Puebla,§ Ana M. Lo´pez,*,‡
Enrique On˜ate,‡ and J ose´ I. Tolosa‡
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain, and Instituto de Ciencia de
Materiales de Madrid, CSIC, Campus de Cantoblanco, 28049 Madrid, Spain
Received J uly 12, 1999
The cyclopentadienyl complex Os(η5-C5H5)Cl(PiPr3)2 (1) reacts with benzophenone imine
to give the cationic orthometalated derivative [OsH(η5-C5H5){NHdC(Ph)C6H4}(PiPr3)]Cl (2a ),
containing the hydride ligand and the metalated phenyl group mutually cisoid disposed.
Treatment of 2a with NaOCH3 affords the neutral species Os(η5-C5H5){NHdC(Ph)C6H4}-
(PiPr3) (3), which by protonation with HBF4‚OEt2 gives [OsH(η5-C5H5){NHdC(Ph)C6H4}-
(PiPr3)]BF4 (4). The structure of 4 was determined by an X-ray investigation. The geometry
around the osmium center can be described as a four-legged piano-stool geometry, with the
hydride ligand transoid disposed to the metalated phenyl group and cisoid to the NH of the
imine. The separation between the hydride and the NH hydrogen atom is about 2.5 Å.
Complex 1 also reacts with triphenylphosphine. In this case the reaction product is the mixed-
ligand compound Os(η5-C5H5)Cl(PPh3)(PiPr3) (5). Treatment of 5 with TlPF6 affords the
orthometalated triphenylphosphine derivative [OsH(η5-C5H5)(PPh2C6H4}(PiPr3)]PF6 (6). The
structure of 6 was also determined by an X-ray investigation. As for 4, the geometry around
the osmium center can be described as a four-legged piano-stool geometry with the hydride
ligand and the metalated phenyl group in transoid positions. Treatment of 6 with NaOCH3
produces the extraction of the hydride ligand and the formation of the neutral species Os-
(η5-C5H5)(PPh2C6H4)(PiPr3) (7), which in methanol under reflux gives OsH(η5-C5H5)(PPh3)-
(PiPr3) (8). Protonation of 8 with HBF4‚OEt2 affords the cationic dihydride [OsH2(η5-
C5H5)(PPh3)(PiPr3)]BF4 (9).
In tr od u ction
We have recently reported the synthesis of the half-
sandwich compound Os(η5-C5H5)Cl(PiPr3)2, which is a
labile starting material for the development of new
cyclopentadienyl-osmium chemistry.1 Thus, in pentane
and toluene, the splitting of an Os-P bond takes place,
and the reactions of this complex with olefins and
alkynes afford chloro π-olefin and π-alkyne derivatives.1b,d
On the other hand, in polar solvents such as methanol
and acetone, the dissociation of the chlorine ligand
occurs, and the resulting fragment is capable of activat-
ing a methyl C-H bond of a triisopropylphosphine to
give [OsH(η5-C5H5){CH2CH(CH3)PiPr2}(PiPr3)]+, as a
mixture of two pairs of diasteroisomers (eq 1).
Tilley and co-workers2 have also observed that the bis-
(triphenylphosphine) derivative Os(η5-C5H5)(OTf)(PPh3)2
evolves, in a similar way, into the orthometalated
‡ Universidad de Zaragoza-CSIC.
§ Instituto de Ciencia de Materiales de Madrid, CSIC.
(1) (a) Esteruelas, M. A.; Go´mez, A. V.; Lo´pez, A. M.; Oro, L. A.
Organometallics 1996, 15, 878. (b) Esteruelas, M. A.; Lo´pez, A. M.;
Ruiz, N.; Tolosa, J . I. Organometallics 1997, 16, 4657. (c) Crochet, P.;
Esteruelas, M. A.; Gutie´rrez-Puebla, E. Organometallics 1998, 17,
3141. (d) Crochet, P.; Esteruelas, M. A.; Lo´pez, A. M.; Ruiz, N.; Tolosa,
J . I. Organometallics 1998, 17, 3479.
species [OsH(η5-C5H5)(PPh2C6H4)(PPh3)]OTf in dichlo-
(2) Wanandi, P. W.; Tilley; T. D. Organometallics 1997, 16, 4299.
10.1021/om990538h CCC: $19.00 © 2000 American Chemical Society
Publication on Web 01/04/2000

276 Organometallics, Vol. 19, No. 3, 2000
Esteruelas et al.
Sch em e 1
romethane and in the solid state under nitrogen (eq 2).
isopropyl or alternatively the phenyl group of the
corresponding PiPr3 and LPh ligands.
This paper shows the selective arene intramolecular
C-H activation in the mixed-ligand fragments [Os(η5-
C5H5)(NHdCPh2)(PiPr3)]+ and [Os(η5-C5H5)(PPh3)-
(PiPr3)]+. In addition, we report a new example of
H‚‚‚H interaction in a four-membered LH‚‚‚H-M ring.
Of great importance in biological and organic chemis-
try,6 the hydrogen bonding is presently attracting
considerable interest in the chemistry of transition
metals.7
The activation of C-H bonds by transition-metal
compounds has attracted a great deal of attention in
recent years,3 in particular the selectivity of the com-
petitive alkane-arene intermolecular activation.4 Al-
though the arene C-H bond is between 14 and 8
kcal‚mol-1 stronger than the alkane C-H bond, in
general, the activation of the first one is kinetically and
thermodynamically favored. The kinetic advantange of
the arene activation appears to be due to its prior
π-coordination, while the thermodynamic preference has
been largely attributed to a metal-carbon bond much
stronger for aryl than for alkyl.
Resu lts a n d Discu ssion
1. C-H Activa tion of a P h en yl Gr ou p of Ben -
zop h en on e Im in e. Treatment at room temperature of
pentane suspensions of Os(η5-C5H5)Cl(PiPr3)2 (1) with
1 equiv of benzophenone imine affords after 2 h the
cationic orthometalated complex [OsH(η5-C5H5)-
The selectivity of the competitive alkane-arene in-
tramolecular C-H activation is much less clear. In
examining the numerous examples of cyclometalations,5
one finds that is not easy to conclude about the arene
or alkane preference, because many variables are being
changed at the same time.
{NHdC(Ph)C6H4}(PiPr3)]Cl (2a ), which was isolated as
a yellow solid in 85% yield. The [BF4]- salt (2b) was
obtained by addition of sodium tetrafluoroborate to a
tetrahydrofurane solution of 2a (Scheme 1).
The formation of 2a is a result of the selective C-H
activation of a phenyl group of the imine. The higher
The lability of an Os-P bond of the complex Os(η5-
C5H5)Cl(PiPr3)2 makes this compound a suitable candi-
date to generate mixed-ligand fragments of the type
[Os(η5-C5H5)(LPh)(PiPr3)]+, which have the same metal-
ligand system to activate, in a competitive manner, the
(6) J effrey, G. A.; Saenger, W. Hydrogen Bonding in Biological
Structures; Springer: Berlin, 1991.
(7) (a) Stevens, R. C.; Bau, R.; Milstein, D.; Blum, O.; Koetzle, T. F.
J . Chem. Soc., Dalton Trans. 1990, 1429. (b) Lough, A. J .; Park, S.;
Ramachandran, R.; Morris, R. H. J . Am. Chem. Soc. 1994, 116, 8356.
(c) Shubina, E. S.; Belkova, N. V.; Krylov, A. N.; Vorontsov, E. V.;
Epstein, L. M.; Gusev, D. G.; Niedermann, M.; Berke; H. J . Am. Chem.
Soc. 1996, 118, 1105. (d) Braga, D.; Grepioni, F.; Desiraju, G. R. J .
Organomet. Chem. 1997, 548, 33. (e) Ayllon, J . A.; Sabo-Etienne, S.;
Chaudret, B.; Ulrich, S.; Limbach, H.-H. Inorg. Chim. Acta 1997, 259,
1. (f) Aime, S.; Gobetto, R.; Valls, E. Organometallics 1997, 16, 5140.
(g) Crabtree, R. H.; Eisenstein, O.; Sini, G.; Peris, E. J . Organomet.
Chem. 1998, 567, 7. (h) Crabtree, R. H. J . Organomet. Chem. 1998,
577, 111. (i) Yandulov, D. V.; Caulton, K. G.; Belkova, N. V.; Shubina,
E. S.; Epstein, L. M.; Khoroshun, D. V.; Musaev, D. G.; Morokuma, K.
J . Am. Chem. Soc. 1998, 120, 12553. (j) Gusev, D. G.; Lough, A. J .;
Morris, R. H. J . Am. Chem. Soc. 1998, 120, 13138. (k) Buil, M. L.;
Esteruelas, M. A.; On˜ate, E.; Ruiz, N. Organometallics 1998, 17, 3346.
(l) Lee, D.-H.; Kwon, H. J .; Patel, B. P.; Liable-Sands, L. M.; Reingold,
A. L.; Crabtree, R. H. Organometallics 1999, 18, 1615. (m) Esteruelas,
M. A.; Oliva´n, M.; On˜ate, E.: Ruiz, N.; Tajada, M. A. Organometallics
1999, 18, 2953.
(3) (a) Shilov, A. E. Activation of Saturated Hydrocarbons by
Transition Metal Complexes; D. Riedel Publishing Co.: Dordrecht, The
Netherlands, 1984. (b) Bergman, R. G. Science 1984, 223, 902. (c)
Halpern, J . Inorg. Chim. Acta 1985, 100, 41. (d) Crabtree, R. H. Chem.
Rev. 1985, 85, 245. (e) Green, M. L.; O’Hare, D. Pure Appl. Chem. 1985,
57, 1897. (f) Activation and Functionalization of Alkanes; Hill, C. L.,
Ed.; J ohn Wiley and Sons: New York, 1989; Chapter IV, p 11: (g)
Ryabov, A. Chem. Rev. 1990, 90, 403. (h) Esteruelas, M. A.; Lahoz, F.
J .; On˜ate, E.; Oro, L. A.; Sola, E. J . Am. Chem. Soc. 1996, 118, 89, and
references therein.
(4) J ones, W. D.; Feher, F. J . Acc. Chem. Res. 1989, 22, 91.
(5) (a) Parshall, G. W. Acc. Chem. Res. 1970, 3, 139. (b) Dehand, J .;
Pfeffer, M. Coord. Chem. Rev. 1976, 18, 327. (c) Bruce, M. I. Angew.
Chem., Int. Ed. Engl. 1977, 16, 73. (d) Edwards, A. J .; Esteruelas, M.
A.; Lahoz, F. J .; Lo´pez, A. M.; On˜ate, E.; Oro, L. A.; Tolosa, J . I.
Organometallics 1997, 16, 1316, and references therein.

Reactions of Os(η5-C5H5)Cl(PiPr3)2
Organometallics, Vol. 19, No. 3, 2000 277
stability of the five-membered rings with regard to the
four-membered rings could explain why the aryl group
of the benzophenone imine is selectivily activated in the
presence of the isopropyl group of the triisopropylphos-
phine. The previously mentioned greater strength of the
metal-aryl bonds with regard to the metal-alkyl bonds
does not seem to be a determinant factor of the process.
Thus, it has been previously observed that the reaction
of [Pd(OAc)2]3 with N,N-dimethyl-o-toluidine gives [Pd-
(µ-OAc){CH2C6H4N(CH3)2}]2 as a consequence of the
metalation of the ortho-methyl group of the amine.8
In addition, it should be mentioned that complex 2a
is reminiscent of the intermediates proposed by Murai
for the insertion of olefins into aromatic C-H bonds
located in ortho position relative to a coordinating group
such as ketone, imine, or pyridine.9
F igu r e 1. Molecular diagram of the cation of 4, [OsH(η5-
C5H5){NHdC(Ph)C6H4}(PiPr3)]+. Thermal ellipsoids are
The 1H NMR spectra of 2a and 2b are consistent with
a four-legged piano-stool structure with the hydride
cisoid to the triisopropylphosphine ligand. Thus, they
show at -12.98 (2a ) and -12.96 (2b) ppm doublets with
a H-P coupling constant of 38 Hz, which agrees well
with those found in the dihydride-silyl derivative RuH2-
(η5-C5Me5)(SiMePh2)(PiPr3) (29 Hz)10 and in the dihy-
dride cations [RuH2(η5-C5Me5)(PMe3)2]+ (33 Hz),11 [RuH2-
(η5-C5H5)(PMe3)2]+ (29 Hz),12 [OsH2(η5-C5H5)(PiPr3)2]+
(32.2 Hz),1b and [OsH2(η5-C5H5)(PPh3)2]+ (29.0 Hz),13
where hydride and phosphine ligands mutually cisoid
have also been proposed. The resonance corresponding
to the NH proton appears as a broad singlet at 12.81
ppm in the spectrum of 2a and at 11.09 ppm in the
spectrum of 2b. The 13C{1H} NMR spectra are consis-
tent with the presence of a heterometallacycle in these
species. The coordination of the nitrogen atom of the
imine is supported by the multiplicity of the resonance
due to the CdN carbon atom, which appears as a
doublet with a C-P coupling constant of approximately
3 Hz, at about 190 ppm. The resonance of the Os-C
carbon atom of the metalated phenyl group is observed
at about 165 ppm as a doublet with a C-P coupling
constant of about 4 Hz. The chemical shifts of these
resonances agree well with those previously observed
for related compounds.14
shown at 50% probability.
In the 1H NMR spectrum of 3 the most noticeable
features are the presence of a broad singlet at 9.96 ppm,
corresponding to the NH hydrogen atom, and the
absence of any hydride resonance. The 13C{1H} NMR
spectrum agrees well with those of 2a and 2b . The
CdN resonance appears at 184.5 ppm, as a doublet with
a C-P coupling constant of 2.8 Hz, whereas the Os-C
resonance is observed at 186.0 ppm, also as a doublet
but with a C-P coupling constant of 7.8 Hz.
Although the protonation of 3 affords a hydride
derivative, the deprotonation of 2 is not reversible. The
addition of 1 equiv of HBF4‚OEt2 to diethyl ether
solutions of 3 produces 4 (Scheme 1), an isomer of 2b,
which contains the hydride ligand and the nitrogen
atom of the imine group in cisoid positions instead of
transoid as in 2b. Complex 4 was isolated as a brown
solid in 92% yield.
The X-ray analysis of a crystal of 4 shows two
independent, but chemically equivalent molecules in the
asymmetric unit (A and C enatiomers). A view of the
molecular geometry of the A enatiomer of 4 is shown in
Figure 1. Selected bond distances and angles are listed
in Table 1. Although the hydride ligand and the NH
hydrogen atom could not be located, the presence of
these atoms in the complex is supported by the 31P{1H}
and 1H NMR spectra. The 31P{1H} NMR spectrum
shows a singlet at 18.9 ppm, which is split into a doublet
under off-resonance conditions, as a result of the
coupling with the hydride ligand. In the 1H NMR
spectrum the NH resonance appears at 11.24 ppm as a
broad signal, and the hydride resonance is observed at
-11.92 ppm as a double doublet by spin coupling with
the phosphorus nucleus of the phoshine ligand [J (HP)
) 41.7 Hz] and the NH hydrogen atom [J (HH) ) 4.1
Complex 2 can be deprotonated by reaction with
sodium methoxide. The addition of this base to tetra-
hydrofurane solutions of 2a gives rise to the formation
of the neutral compound Os(η5-C5H5){NHdC(Ph)C6H4}-
(PiPr3) (3) (Scheme 1), as a result of the extraction of
the hydride ligand. Complex 3, which is a green,
extremely air-sensitive solid, was isolated in 81% yield.
(8) Mutet, C.; Pfeffer, M. J . Organomet. Chem. 1979, 171, C34.
(9) (a) Murai, S.; Kakiuchi, F.; Sekine, S.; Tanaka, Y.; Kamatani,
A.; Sonoda, M.; Chatani, N. Nature 1993, 366, 529. (b) Kakiuchi, F.;
Sekine, S.; Tanaka, Y.; Katmatani, A.; Sonoda, M.; Chatani, N.; Murai,
S. Bull. Chem. Soc. J pn. 1995, 68, 62. (c) Sonoda, M.; Kakiuchi, F.;
Kamatani, A.; Chatani, N.; Murai, S. Chem. Lett. 1996, 109, and
references therein.
(10) (a) Campion, B. K.; Heyn, R. H.; Tilley, T. D. Chem. Commun.
1992, 1201. (b) Campion, B. K.; Heyn, R. H.; Tilley, T. D.; Rheingold,
A. L. J . Am. Chem. Soc. 1993, 115, 5527.
(11) Grumbine, S. K.; Mitchell, G. P.; Strauss, D. A.; Tilley, T. D.;
Reingold, A. L. Organometallics 1998, 17, 5607.
(12) Lemke, F. R.; Brammer, L. Organometallics 1995, 14, 3980.
(13) Rottink, M. K.; Angelici, R. J . J . Am. Chem. Soc. 1993, 115,
7267.
1
Hz]. The last coupling was confirmed by the H COSY
spectrum.
The distribution of ligands around the osmium atom
can be described as a four-legged piano-stool geometry,
with the cyclopentadienyl ligand occupying the three-
membered face, while the phoshine, hydride, and ortho-
metalated benzophenone imine ligands lie in the four-
membered face. The phosphine ligand is disposed
transoid to the N(1) nitrogen atom of the imine group
[P(1)-Os-N(1) ) 106.5(6)° (molecule a ) and 103.9(5)°
(molecule b)], cisoid to the metalated C(15) carbon atom
[P(1)-Os-C(15) ) 87.9(7)° (a ) and 87.8(6)° (b)] and, in
(14) Esteruelas, M. A.; Lahoz, F. J .; Lo´pez, A. M.; On˜ate, E.; Oro,
L. A. Organometallics 1995, 14, 2496, and references therein.

278 Organometallics, Vol. 19, No. 3, 2000
Esteruelas et al.
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for th e Com p lex
hydrogen separation in four-membered rings of the type
LH‚‚‚H-M, with an electrostatic hydrogen-hydrogen
interaction [2.407a-2.907k].
[OsH(η5-C5H5){NHdC(P h )C6H4}(P iP r 3)]BF 4 (4)
molecule a
molecule b
The orthometalated benzophenone imine ligand acts
with a bite angle of 74.0(10)° (a ) and 75.7(8)° (b). The
five-membered metallacycle is almost planar. The de-
viations from the best plane are 0.0000(9) (a ),
0.0001(8) (b) [Os], 0.03(2) (a ), -0.05(2) (b) [C(15)],
-0.01(2) (a ), 0.03(2) (b) [C(20)], -0.02(2) (a ), 0.01(2) (b)
[C(21)], and 0.02(2) (a ), -0.02(2) (b ) [N(1)] Å. The
Os-N(1) bond lengths of 2.078(18) (a ) and 2.080(19) (b)
Å and the Os-C(15) bond distances of 2.10(2) (a ) and
2.137(19) (b) Å are typical for Os-N and Os-C(aryl)
single bonds, respectively, and are in agreement with
Bond Lengths
2.335(6) Os(2)-P(51)
2.078(18) Os(2)-N(51)
Os(1)-P(1)
Os(1)-N(1)
Os(1)-C(1)
Os(1)-C(2)
Os(1)-C(3)
Os(1)-C(4)
Os(1)-C(5)
Os(1)-C(15)
N(1)-C(21)
C(15)-C(16)
C(15)-C(20)
C(20)-C(21)
C(21)-C(22)
2.329(6)
2.080(19)
2.25(2)
2.21(2)
2.24(2)
2.21(2)
2.25(2)
2.137(19)
1.27(2)
1.35(3)
1.47(3)
1.44(3)
1.48(3)
2.20(2)
2.28(2)
2.22(2)
2.17(2)
2.19(2)
2.10(2)
1.26(3)
1.42(4)
1.38(3)
1.51(3)
1.49(3)
Os(2)-C(51)
Os(2)-C(52)
Os(2)-C(53)
Os(2)-C(54)
Os(2)-C(55)
Os(2)-C(65)
N(1)-C(71)
C(65)-C(66)
C(65)-C(70)
C(70)-C(71)
C(71)-C(72)
the values previously found for the complexes OsCl-
{NHdC(Ph)C6H4}(η2-H2)(PiPr3)2 [2.097(3) and 2.069
Å],17 Os(C2Ph){NHdC(Ph)C6H4}(CO)(PiPr3)2 [2.106(7)
and 2.089(7) Å],14 [Os{NHdC(Ph)C6H4}(η6-C6H3Me3)-
(PiPr3)]PF6 [2.083(4) and 2.072(4) Å],18 OsH(C6H3-pMe)-
Bond Angles
129.2(3)
G(1)*-Os(1)-P(1)
G(2)*-Os(2)-P(51) 130.4(4)
G(2)*-Os(2)-N(51) 123.7(7)
G(2)*-Os(2)-C(65) 114.7(7)
P(51)-Os(2)-N(51) 103.9(5)
G(1)*-Os(1)-N(1) 122.0(6)
G(1)*-Os(1)-C(15) 117.6(7)
P(1)-Os(1)-N(1)
P(1)-Os(1)-C(15)
N(1)-Os(1)-C(15)
106.5(6)
87.9(7)
74.0(10)
P(51)-Os(2)-C(65)
N(51)-Os(2)-C(65)
87.8(6)
75.7(8)
Os(1)-N(1)-C(21) 123.4(17)
Os(1)-C(15)-C(16) 132(2)
Os(1)-C(15)-C(20) 118(2)
C(15)-C(20)-C(21) 111.9(19)
N(1)-C(21)-C(20) 112.6(19)
N(1)-C(21)-C(22) 122(2)
Os(2)-N(51)-C(71) 121.0(15)
Os(2)-C(65)-C(66) 130.3(18)
Os(2)-C(65)-C(70) 113.5(17)
C(65)-C(70)-C(71) 112.7(18)
N(51)-C(71)-C(70) 117(2)
N(51)-C(71)-C(72) 119.5(19)
(p-tolyl)CNNC(p-tolyl)2(CO2)(PPh3) [2.119(5) and 2.100-
(7) Å],19 and fac-Os{C,N-3-Me[2-(MeC6H4)NCMe3]C6H3}-
(2-MeC6H4)(CN-tBu)3 [2.193(24) and 2.077(20) Å].20
The 13C{1H} NMR spectrum of 4 agrees well with the
presence of a heterometallacyle in this compound.
Similarly to the 13C{1H} NMR spectra of 2a , 2b, and 3,
the spectrum of 4 shows the resonance due to the CdN
carbon atom at 188.3 ppm as a doublet with a C-P
coupling constant of 7.8 Hz. The Os-C resonance is
observed at 158.0 ppm, as a doublet with a C-P
coupling constant of 13.8 Hz.
At first glance, the formation of 4 by protonation of 3
appears to suggest that complex 4, containing the
hydride ligand cisoid to the NH group, is thermody-
namically favored with regard to 2b, while the cation
of 2b, which is formed by direct reaction of 1 with
benzophenone imine, appears to be the kinetic product
of the activation. Scheme 2 shows two possible pathways
to the formation of this species.
As a consequence of the large steric hindrance expe-
rienced by the triisopropylphosphine groups, which are
mutually cis disposed, complex 1 shows a high tendency
to release a phosphine ligand in pentane as solvent.1b
So, it seems reasonable to think that the first step for
the C-H activation of the phenyl group of the ben-
zophenone imine molecule is the formation of the imine
intermediate A as a result of the dissociation of a
phosphine ligand from 1 and the subsequent coordina-
tion of the benzophenone imine group. Although mono-
dentate nitrogen-bonded imine compounds are rare as
*G(1) and G(2) are the centroids of the C(1)-C(5) and C(51)-
C(55) Cp ligands.
agreement with the value of the coupling constant
between the hydride and phosphine, cisoid to the
hydride ligand. The hydride ligand is located transoid
to the metalated C(15) carbon atom and cisoid to the
N(1) nitrogen atom. In solution, the cisoid disposition
of the hydride ligand and the NH group of the imine
was confirmed by a NOE experiment. The saturation
of the NH resonanace increases the intensity of the
hydride signal in 9%. In contrast to 4, the saturation of
the NH resonance of 2b has no effect on the correspond-
ing hydride signal.
The cisoid disposition of the hydride ligand and the
N(1) nitrogen atom of the imino group leads to a
situation where the H-Os-N-H dihedral angle should
be about 30°, in agreement with the observed spin
coupling between these nuclei. As a result, the distance
between the hydride ligand and the NH hydrogen atom
should be short. To corroborate this, the T1 values for
the resonances corresponding to the hydride ligands of
2b and 4 were determined over the temperature range
293-203 K, in dichloromethane as solvent. The T1(min)
values of the two resonances were found to the same
temperature, 213 K. The lower T1(min) value at 300
MHz for the hydride resonance of 4 [285(4) ms] versus
the hydride resonance of 2b [330(5) ms] implies an
excess relaxation rate for the hydride resonance of 4
between 0.38 and 0.83 s-1. Assuming that the excess
relaxation rate for the hydride resonance of 4 is a result
of the proximity of the NH hydrogen atom in this
compound and that the hydride-NH hydrogen vector
rotates with the molecule as a whole, we can estimate
a hydride-NH hydrogen separation between 2.6 and 2.3
Å, according to the standard equation.7k,15 These values
lie within the range reported for the hydrogen-
(16) (a) Hamilton, D. G.; Crabtree, R. H. J . Am. Chem. Soc. 1988,
110, 4126. (b) Bautista, M. T.; Earl, K. A.; Maltby, P. A., Morris, R.
H.; Schweitzer, C. T.; Sella, A. J . Am. Chem. Soc. 1988, 110, 7031. (c)
Desrosiers, P. J .; Cai, L.; Lin, Z.; Richards, R.; Halpern, J . J . Am. Chem.
Soc. 1991, 113, 4173. (d) Gusev, D. G.; Kuhlman, R.; Sini, G.;
Eisenstein, O.; Caulton, K. G. J . Am. Chem. Soc. 1994, 116, 2685.
(17) Barea, G.; Esteruelas, M. A.; LLedo´s, A.; Lo´pez, A. M.; On˜ate,
E.; Tolosa, J . I. Organometallics 1998, 17, 4065.
(18) Werner, H.; Daniel, T.; Braun, T.; Nu¨rnberg, O. J . Organomet.
Chem. 1994, 480, 145.
(19) Gallop, M. A.; Rickard, C. E. F.; Roper, W. R. J . Organomet.
Chem. 1990, 395, 333.
(20) Arnold, J .; Wilkinson, G.; Hussain, B.; Hurthouse, M. B.
Organometallics 1989, 8, 1362.
(15) R ) 129.18/r6. See ref 16.

Reactions of Os(η5-C5H5)Cl(PiPr3)2
Organometallics, Vol. 19, No. 3, 2000 279
Sch em e 2
a consequence of the weak Lewis basicity of the imine
nitrogen atom, stable derivatives of ruthenium and
osmium have been recently isolated.21 According to
pathway a , the dissociation of the chloro ligand could
give the intermediate B containing the Cortho-H bond
to be activated parallel to the P-N vector. The oxidative
addition of this bond should afford 2a . Alternatively to
the dissociation of chloride from A, the intermediate B
could be formed according to pathway b. The η5-η3
rearrangement of the cyclopentadienyl group in A could
generate a coordination vacancy disposed trans to the
chloro ligand. In this way, the subsequent coordination
of the Cortho-H bond to be activated in this place,
followed of the displacement of chloride by, now, an η3-
η5 rearrangement of the cyclopentadienyl group, should
afford B. Since, the reaction of orthometalation of the
imine takes place in pentane as solvent and it is fast,
pathway b seems to be more reasonable than pathway
a .
In addition, it should be mentioned that the coordina-
tion of the Cortho-H bond to the metal center in the [Os-
(η5-C5H5)(NHdCPh2)(PiPr3)]+ fragment can be parallel
to the P-N vector as in B or, alternatively, perpendicu-
lar. In the second case, the oxidative addition of the
C-H bond should give 4. Using a molecular model, it
can be observed that, from a geometrical point of view,
the parallel coordination is more favored than the
perpendicular. This could explain why complex 2a is the
kinetic product.
rings indicate that the H‚‚‚H interaction favors the
formation of determined conformers and reduces the
dynamic properties of the ligands supporting the inter-
action. However, it does not impose the stereochemistry
of a particular derivative.7k
2. C-H Act iva t ion of a P h en yl Gr ou p of Tr i-
p h en ylp h osp h in e. We have previously shown that the
addition of 1 equiv of benzophenone imine to pentane
suspensions of 1 produces the displacement of both a
triisopropylphosphine group and the chloro ligand from
the coordination sphere of the osmium atom and the
C-H activation of a phenyl group of the imine. The
reaction of 1 with triphenylphosphine is different from
that mentioned above. The treatment of 1, in pentane
or toluene, with 1 equiv of triphenylphosphine produces
only the displacement of a triisopropylphosphine group.
As a result, the mixed-ligand complex Os(η5-C5H5)Cl-
(PPh3)(PiPr3) (5) was isolated as a yellow solid in 94%
yield (Scheme 3). The displacement of the chloro ligand
and the subsequent C-H activation does not occur even
under refluxing toluene.
The release of the chloro from the coordination sphere
of 5 requires the addition of thallium hexafluorophos-
phate. Thus, the addition of 1 equiv of this salt to
acetone solutions of 5 gives rise to the precipitation of
thallium chloride and the formation of [OsH(η5-C5H5)-
(PPh2C6H4}(PiPr3)]PF6 (6), as a consequence of the
activation of a Cortho-H bond of a phenyl group of the
triphenylphosphine ligand. The selective activation of
the phenyl group in the presence of the isopropyl groups
of the triisopropylphosphine ligand can be related with
the previously mentioned kinetic and thermodynamic
preference for the arene C-H activation, in comparison
with the alkane C-H activation.
Not only are the activation processes of the phenyl
groups of benzophenone imine and triphenylphosphine
produced in a different manner but also the stere-
ochemistries of the activated products are different. As
it has been previously mentioned, the activation of the
phenyl group of the imine appears to take place by
approach of the C-H bond in a parallel direction to the
P-N vector, and the resulting product, complex 2a ,
Although thermodynamically complex 4 seems to be
more stable than 2b, isomerization from 2b into 4 is
not observed. This could be due to the high stability of
the five-membered heterometallacycle, which imposes
a high activation barrier for the isomerization. The
higher stability of 4 with regard to 2b should not be
related with the presence of the H‚‚‚H interaction in 4
but with the transoid disposition of the hydride ligand
and the orthometalated phenyl group (vide infra).
Previous studies on complexes containing LH‚‚‚H-M
(21) (a) Bohanna, C.; Esteruelas, M. A.; Lo´pez, A. M.; Oro, L. A. J .
Organomet. Chem. 1996, 526, 73. (b) Albe´niz, M. J .; Buil, M. L.;
Esteruelas, M. A.; Lo´pez, A. M. J . Organomet. Chem. 1997, 545-546,
495.

280 Organometallics, Vol. 19, No. 3, 2000
Esteruelas et al.
Sch em e 3
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for th e Com p lex
[OsH(η5-C5H5)(P P h 2C6H4)(P iP r 3)]P F 6 (6)
molecule a
molecule b
Bond Lengths
Os(1)-P(1)
Os(1)-P(2)
Os(1)-C(2)
Os(1)-C(28)
Os(1)-C(29)
Os(1)-C(30)
Os(1)-C(31)
Os(1)-C(32)
Os(1)-H(1)
P(1)-C(1)
2.328(2)
Os(2)-P(3)
2.319(2)
2.388(2)
2.136(9)
2.202(12)
2.231(11)
2.267(11)
2.339(11)
2.292(11)
1.49(7)
2.395(3)
2.180(9)
2.219(9)
2.264(10) Os(2)-C(79)
2.315(10) Os(2)-C(80)
2.281(9)
2.224(9)
1.50(6)
Os(2)-P(4)
Os(2)-C(52)
Os(2)-C(78)
Os(2)-C(81)
Os(2)-C(82)
Os(2)-H(2)
P(3)-C(51)
1.791(8)
1.387(12) C(51)-C(52)
1.400(13) C(52)-C(53)
1.800(9)
1.412(12)
1.400(13)
C(1)-C(2)
C(2)-C(3)
Bond Angles
G(1)a-Os(1)-P(1)
G(1)a-Os(1)-P(2)
124.25(15)
128.39(14)
G(2)a-Os(2)-P(3)
126.77(16)
129.65(15)
F igu r e 2. Molecular diagram of the cation of 6, [OsH(η5-
C5H5)(PPh2C6H4)(PiPr3)]+. Thermal ellipsoids are shown at
50% probability.
G(2)a-Os(2)-P(4)
G(1)a-Os(1)-C(15) 117.2(3)
G(2)a-Os(2)-C(52) 123.7(7)
G(1)a-Os(1)-H(1) 113(2)
G(2)a-Os(2)-H(2)
P(3)-Os(2)-P(4)
P(3)-Os(2)-C(52)
P(3)-Os(2)-H(2)
P(4)-Os(2)-C(52)
P(4)-Os(2)-H(2)
114.7(7)
103.07(8)
65.3(3)
77(3)
84.5(2)
70(3)
P(1)-Os(1)-P(2)
P(1)-Os(1)-C(2)
P(1)-Os(1)-H(1)
P(2)-Os(1)-C(2)
P(2)-Os(1)-H(1)
C(2)-Os(1)-H(1)
Os(1)-P(1)-C(1)
P(1)-C(1)-C(2)
P(1)-C(1)-C(6)
C(1)-C(2)-C(3)
C(2)-C(1)-C(6)
107.15(8)
64.9(2)
79(2)
86.7(2)
70(2)
contains the added fragments in mutually cisoid posi-
tions. In contrast to the activation of the imine, the
approach of the C-H bond of the activated phenyl group
of the triphenylphosphine occurs in the direction per-
pendicular to the P-P vector, and in the resulting
product, complex 6, the hydride ligand and the ortho-
metalated phenyl group lie in mutually transoid posi-
tions.
The stereochemistry of 6 is strongly supported by the
1H, 31P{1H}, and 13C{1H} NMR spectra and was con-
firmed by an X-ray diffraction study on a single crystal
of the complex. Similarly to 4, 6 shows two independent,
but chemically equivalent molecules in the asymmetric
unit (in this case the same enantiomer). A view of the
molecular geometry of one of the molecules of 6 is shown
in Figure 2. Selected bond distances and angles are
listed in Table 2. In contrast to 4, the hydride ligand
H(1) was located in the difference Fourier maps and
refined as an isotropic atom together with the rest of
the non-hydrogen atoms of the structure, giving an Os-
H(1) distance of 1.50(6) (molecule a ) and 1.49(7) Å
(molecule b).
129(2)
C(52)-Os(2)-H(2) 128(3)
88.9(3)
98.5(6)
138.0(7)
118.6(9)
123.4(8)
Os(2)-P(3)-C(51)
P(3)-C(51)-C(52)
P(3)-C(51)-C(56)
89.1(3)
96.5(6)
138.9(8)
C(51)-C(52)-C(53) 115.8(9)
C(52)-C(51)-C(56) 124.4(9)
a
G(1) and G(2) are the centroids of the C(28)-C(32) and C(68)-
C(82) Cp ligands.
metalated phenyl group and cisoid to both phosphorus
atoms, which are mutually transoid [P(1)-Os-P(2) )
107.15(8)° (a ) and 103.07(8)° (b)]. In agreement with
1
this disposition, the H NMR spectrum shows at -12.10
ppm a double doublet with H-P coupling constants of
35.7 and 26.4 Hz, for the hydride ligand, and the 31P-
{1H} NMR contains two doublets at 16.8 and -74.8 ppm
with a P-P coupling constant of 18.1 Hz, which cor-
respond to the triisopropylphosphine and orthometa-
lated triphenylphosphine ligands, respectively.
The orthometalated triphenylphosphine acts with a
bite angle of 64.9(2)° (a ) and 65.3(3)° (b). The four-
membered heterometallacycle is almost planar. The
deviations from the best plane are 0.0001(4) (a ) and
0.0001(4) (b) [Os(1)], -0.059(9) (a ) and -0.055(9) (b)
The distribution of ligands around the osmium atom
of 6 can be described as a four-legged piano-stool
geometry with the hydride ligand transoid to the

Reactions of Os(η5-C5H5)Cl(PiPr3)2
Organometallics, Vol. 19, No. 3, 2000 281
[C(2)], 0.057(8) (a ) and 0.055(9) (b ) [C(1)], and
-0.003(2) (a ) and -0.002(2) Å (b) [P(1)]. The Os(1)-
C(2) distance [2.180(9) (a ) and 2.136(9) Å (b)] agrees
well with the values reported for related compounds.16-19
The Os(1)-P(1) distance [2.328(2) (a ) and 2.319(2) Å (b)]
is about 0.06 Å shorter than the separation between the
osmium atom and the triisopropylphosphine ligand.
However, it is about 0.02 Å longer than the Os-P bond
NMR spectrum the most noticeable feature is a double
doublet at -13.09 ppm, with both H-P coupling con-
stants of 28.9 Hz. The 31P{1H} NMR spectrum contains
at 35.4 and 9.7 ppm doublets with a P-P coupling
constant of 26.6 Hz. The multiplicity of these signals
and the values of the spin coupling constants strongly
support the stereochemisty proposed for 9 in Scheme
3.
length in the metalated osmium(IV) compound [OsH-
Con clu d in g Rem a r k s
(η5-C5H5){CH(SiMe3)C6H4PPh2}(PPh3)]OTf.22
This study has revealed that despite the high kinetic
stability of the CpOsL3 compounds,23 the derivative Os-
(η5-C5H5)Cl(PiPr3)2 (1) reacts with benzophenone imine
and triphenylphosphine to give hydride-metalated com-
plexes, which are the result of the C-H activation of
one phenyl group.
In agreement with the presence of an orthometalated
phenyl group in 6, the 13C{1H} NMR spectrum of this
compound contains at 116.4 ppm a double doublet with
C-P coupling constants of 29.9 and 15.2 Hz.
Similarly to 2b, the treatment of tetrahydrofuran
solutions of 6 with sodium methoxide produces the
extraction of the hydride ligand and the formation of
Although in both cases the reactions lead to the same
type of derivatives, the C-H activations proceed in a
the neutral complex Os(η5-C5H5)(PPh2C6H4)(PiPr3)]Cl
(7), which was isolated as a yellow solid in 85% yield.
The reaction is reversible. Thus, the addition of 1 equiv
of HBF4‚OEt2 to diethyl ether solutions of 7 affords the
BF4 salt of 6. This suggests that for the hydride ligand
and the metalated group the transoid disposition is
favored not only kinetically but also thermodynamically.
A similar situation has also been observed in the
different manner. Thus, while the cation [OsH(η5-C5H5)-
{NHdC(Ph)C6H4}(PiPr3)]Cl (2) is obtained in an one-
pot synthesis starting from 1 and benzophenone imine,
the formation of the related cation [OsH(η5-C5H5)-
(PPh2C6H4)(PiPr3)]PF6 (6) occurs in a two-step proce-
dure. Initially, the reaction of 1 with triphenylphosphine
gives rise to the replacement of a triisopropylphosphine
group by the triphenylphosphine ligand. The release of
the chloride from the coordination sphere of the osmium
atom requires the addition of TlPF6.
complexes [OsH(η5-C5H5)(PPh2C6H4)(PPh3)]OTf,2 [OsH-
(η5-C5H5){CH2CH(CH3)PiPr2}(PiPr3)]+,1b and [OsH(η5-
C5H5){CH(SiMe3)C6H4PPh2}(PPh3)]OTf.22
The stereochemistries of the cations 2 and 6 are also
different. The distribution of ligands around the osmium
atom of both cations can be described as a four-legged
piano-stool geometry. However, while in the cation 2 the
hydride ligand and the metalated phenyl group lie in a
cisoid disposition, in the cation 6 the hydride ligand and
the metalated phenyl group are mutually transoid
disposed. The different stereochemistry of these species
can be related to the different approach to the metallic
center of the added bonds. Thus, the approach in the
case of the benzophenone imine appears to take place
along the direction parallel to the vector P-N of an
Characteristic spectroscopic features of 7 are two
doublets at 20.9 and -71.0 ppm in the 31P{1H} NMR
spectrum, with a P-P coupling constant of 18.6 Hz, and
in the 13C{1H} NMR spectrum a double doublet at 143.1
ppm, with C-P coupling constants of 17.0 and 11.9 Hz,
assigned to the Os-C carbon atom.
In the solid state, complex 7 is stable for 1 week if
kept under argon at -20 °C. In solution at room
temperature it is stable in toluene, benzene, and metha-
nol. However, under refluxing methanol, it evolves in
quantitative yield into the monohydride OsH(η5-C5H5)-
(PPh3)(PiPr3) (8) after 24 h. Complex 8, which is a yellow
air-sensitive solid, can also be prepared by reaction of
5 with NaBH4. By this procedure it was isolated in 85%
yield. The presence of a hydride ligand in 8 is strongly
unsaturated
triisopropylphosphine-benzophenone
imine-osmium fragment, while in the case of the
triphenylphosphine the approach appears to take place
along the direction perpendicular to the P-P vector in
an unsaturated triisopropylphosphine-triphenylphos-
phine-osmium fragment.
In the case of the benzophenone imine, the oxidative
addition leads to the isomer kinetically favored. Al-
though a spontaneous isomerization of 2 is not observed,
its deprotonation and subsequent protonation afford a
new isomer, containing the hydride and the metalated
phenyl group mutually transoid disposed. Furthermore,
in this isomer the hydride and NH group of the imine
are mutually cisoid. As a result, the separation between
the hydride and NH hydrogen atom is short (about
2.5 Å), lying in the range previously reported for
H‚‚‚H interactions in four-membered rings of the type
1
supported by the H NMR spectrum, which contains at
-15.27 ppm a double doublet with both H-P coupling
constants of 29.7 Hz. The 31P{1H} NMR spectrum shows
at 33.6 and 21.2 ppm doublets, with a P-P coupling
constant of 9.8 Hz, which were assigned to the triiso-
propylphosphine and triphenylphosphine ligands, re-
spectively.
In contrast to 7, complex 6 is stable in methanol under
reflux and does not evolve into the corresponding
dihydride [OsH2(η5-C5H5)(PPh3)(PiPr3)]+. However, the
BF4 salt of this cation (9 in Scheme 3) can be prepared
by addition of 1 equiv of HBF4‚OEt2 to diethyl ether
solutions of 8.
Complex 9 was isolated as a white solid in 92% yield
and characterized by MS, elemental analysis, and IR
and 1H and 31P{1H} NMR spectroscopies. In the 1H
LH‚‚‚H-M. In contrast to benzophenone imine, the
(23) Atwood, J . D. Inorganic and Organometallic Reaction Mecha-
nisms; VCH Publishers, Inc.: New York, 1997; Chapter 3.
(22) Koch, J . L.; Shapley, P. A. Organometallics 1999, 18, 814.

282 Organometallics, Vol. 19, No. 3, 2000
Esteruelas et al.
MHz, CD2Cl2, 293 K): δ 11.09 (br, 1 H, NH), 8.24-8.21 (m, 1
H, Ph), 7.68-7.56 (m, 6 H, Ph), 7.11-7.03 (m, 2 H, Ph), 5.68
(s, 5 H, Cp), 2.40 (m, 3 H, PCH), 1.18 (dd, J (HH) ) 7.2 Hz,
J (PH) ) 15.0 Hz, 9 H, PCCH3), 0.94 (dd, J (HH) ) 6.9 Hz,
J (PH) ) 14.4 Hz, 9 H, PCCH3), -12.96 (d, J (PH) ) 38.5 Hz, 1
H, OsH). 31P{1H} NMR (121.42 MHz, CD2Cl2, 293 K): δ 23.7.
13C{1H} NMR (75.42 MHz, CD2Cl2, 293 K, plus APT): δ 190.9
(-, d, J (PC) ) 2.7 Hz, NdC), 165.5 (-, d, J (PC) ) 4.1 Hz, Os-
C), 146.7 (-, s, ipso-Ph), 146.2 (+, s, Ph), 134.8 (-, s, ipso-
Ph), 132.7, 131.3, 130.3, 129.7, 129.0, 123.0 (+, all s, Ph), 86.1
(+, d, J (PC) < 1 Hz, Cp), 28.2 (+, d, J (PC) ) 30.4 Hz, PCH),
20.3 (+, s, PCCH3), 18.6 (+, d, J (PC) ) 2.3 Hz, PCCH3). Anal.
Calcd for C27H37BF4NOsP: C, 47.44; H, 5.45; N, 2.05. Found:
C, 47.89; H, 5.39; N, 2.09. MS (FAB+): m/e 598 (M+).
oxidative addition in the case of triphenylphosphine
leads to the isomer kinetically and thermodynamically
favored.
In addition, it should also be mentioned that this
study proves that under, strictly, the same metal ligand
system the competitive alkane-arene intramolecular
C-H activation shows kinetic and thermodynamic
arene preference when, in the resulting product, the
formed heterocycle has the same number of members
or the reaction gives rise to a more stable heterocycle
than the hypothetic product resulting from the alkane
activation.
P r ep a r a tion of [OsH(η5-C5H5){NHdC(P h )C6H4}(P iP r 3)]
(3). A yellow solution of 2a (185 mg, 0.31 mmol) in 10 mL of
THF was treated with sodium methoxide (25.1 mg, 0.47 mmol).
The mixture was stirred for 17 h at room temperature. The
green solution obtained was evaporated to dryness, and 10 mL
of toluene was added. The suspension was filtered through
Kieselguhr and concentrated to dryness. Addition of methanol
caused the precipitation of an extremely air-sensituve green
solid, which was separated by decantation and dried in vacuo.
Yield: 104 mg (81%). 1H NMR (300 MHz, C6D6, 293 K): δ 9.96
(br, 1 H, NH), 8.62 (d, J (HH) ) 7.8 Hz, 1 H, Ph), 7.77 (d, J (HH)
) 7.8 Hz, 1 H, Ph), 7.33 (d, J (HH) ) 7.2 Hz, 2 H, Ph), 7.11 (m,
3 H, Ph), 6.96 (m, 2 H, Ph), 4.62 (s, 5 H, Cp), 1.73 (m, 3 H,
PCH), 0.94 (dd, J (HH) ) 7.5 Hz, J (PH) ) 13.2 Hz, 9 H,
PCCH3), 0.70 (dd, J (HH) ) 7.2 Hz, J (PH) ) 12.3 Hz, 9 H,
PCCH3). 31P{1H} NMR (121.42 MHz, C6D6, 293 K): δ 16.4. 13C-
{1H} NMR (75.42 MHz, C6D6, 293 K, plus APT): δ 186.0
(-, d, J (PC) ) 7.8 Hz, Os-C), 184.5 (-, d, J (PC) ) 2.8 Hz,
NdC), 144.7 (-, s, ipso-Ph), 143.3 (+, s, Ph), 139.2 (-, s, ipso-
Ph), 130.9, 128.7, 128.4, 127.8, 117.6 (+, all s, Ph), 26.1 (+, d,
J (PC) ) 25.3 Hz, PCH), 20.4, 18.7 (+, both s, PCCH3). MS
(FAB+): m/e 598 (M+ + H).
Exp er im en ta l Section
P h ysica l Mea su r em en ts. Infrared spectra were recorded
as Nujol mulls on polyethylene sheets using a Nicolet 550
spectrometer. NMR spectra were recorded on a Varian UNITY
300, Varian GEMINI 2000 (300 MHz), or a Bruker ARX 300.
The probe temperature of the NMR spectrometers was cali-
brated against a methanol standard. For the T1 measurements
1
the 180° pulses were calibrated at each temperature. H and
13C{1H} chemical shifts were measured relative to partially
deuterated solvent peaks but are reported relative to tetra-
methylsilane. 31P{1H} chemical shifts are reported relative to
H3PO4 (85%). Coupling constants J are given in hertz. C, H,
and N analyses were carried out in a Perkin-Elmer 2400
CHNS/O analyzer. Mass spectra analyses were performed with
a VG Auto Spec instrument. The ions were produced, FAB+
mode, with the standard Cs+ gun at ca. 30 kV, and 3-nitro-
benzyl alcohol (NBA) was used as the matrix.
Syn th esis. All reactions were carried out with exclusion of
air using standard Schlenk techniques. Solvents were dried
by known procedures and distilled under argon prior to use.
The complex Os(η5-C5H5)Cl(PiPr3)2 (1) was prepared according
to the literature method.1b
P r ep a r a tion of [OsH(η5-C5H5){NHdC(P h )C6H4}(P iP r 3)]-
BF 4 (4). A solution of 3 (103 mg, 0.17 mmol) in 6 mL of diethyl
ether was treated with 22.7 µL (0.17 mmol) of HBF4‚OEt2. The
brown solid formed was separated by decantation, washed with
diethyl ether, and dried in vacuo. Yield: 109 mg (92%). IR
P r ep a r a tion of [OsH(η5-C5H5){NHdC(P h )C6H4}(P iP r 3)]-
Cl (2a ). A suspension of 1 (150 mg, 0.24 mmol) in 10 mL of
pentane was treated with 48.9 mg (0.27 mmol) of benzophe-
none imine. After the mixture was stirred for 2 h at room
temperature, a yellow solid was formed, which was separated
by decantation, washed with pentane, and dried in vacuo.
(Nujol): ν(NH) 3304 cm-1, ν(BF4) 1047 cm-1 1H NMR (300
.
MHz, CD2Cl2, 293 K): δ 11.24 (br, 1 H, NH), 8.00 (m, 1 H,
Ph), 7.66 (m, 1 H, Ph), 7.57 (m, 5 H, Ph), 7.24 (m, 2 H, Ph),
5.52 (s, 5 H, Cp), 2.43 (m, 3 H, PCH), 1.09 (dd, J (HH) ) 6.9
Hz, J (PH) ) 15.6 Hz, 9 H, PCCH3), 0.83 (dd, J (HH) ) 6.9 Hz,
J (PH) ) 13.5 Hz, 9 H, PCCH3), -11.92 (dd, J (PH) ) 41.7 Hz,
J (HH) ) 4.1 Hz, 1 H, OsH). 31P{1H} NMR (121.42 MHz, CD2-
Cl2, 293 K): δ 18.9. 13C{1H} NMR (75.42 MHz, CD2Cl2, 293 K,
plus APT): δ 188.3 (-, d, J (PC) ) 7.8 Hz, NdC), 158.0 (-, d,
J (PC) ) 13.8 Hz, Os-C), 146.6 (-, s, ipso-Ph), 143.3 (+, d,
J (PC) ) 1.9 Hz, Ph), 135.2 (-, s, ipso-Ph), 131.8, 131.4, 130.1,
129.4, 128.9 (+, all s, Ph), 84.9 (+, d, J (PC) ) 1.8 Hz, Cp),
26.9 (+, d, J (PC) ) 32.2 Hz, PCH), 20.4 (+, s, PCCH3), 18.5
(+, d, J (PC) ) 3.7 Hz, PCCH3). Anal. Calcd for C27H37BF4-
NOsP: C, 47.44; H, 5.45; N, 2.05. Found: C, 47.47; H, 5.37;
N, 1.88. MS (FAB+): m/e 598 (M+).
P r ep a r a tion of Os(η5-C5H5)Cl(P P h 3)(P iP r 3) (5). A solu-
tion of 1 (260 mg, 0.43 mmol) in 8 mL of toluene was treated
with 111.5 mg (0.43 mmol) of triphenylphosphine. After
stirring for 5 h at room temperature, the yellow solution
obtained was filtered through Kieselguhr and concentrated to
dryness. Addition of pentane caused the precipitation of a
yellow solid, which was separated by decantation, washed with
pentane, and dried in vacuo. Yield: 285 mg (94%). 1H NMR
(300 MHz, C6D6, 293 K): δ 7.91 (dd, J (HH) ) 8.1 Hz, J (HH)
) 8.7 Hz, 6 H, m-Ph), 7.09-6.96 (m, 9 H, Ph), 4.53 (s, 5 H,
Cp), 2.31 (m, 3 H, PCH), 1.05, (dd, J (HH) ) 7.2 Hz, J (PH) )
12.6 Hz, 9 H, PCCH3), 0.87 (dd, J (HH) ) 7.2 Hz, J (PH) ) 12.6
Hz, 9 H, PCCH3). 31P{1H} NMR (121.42 MHz, C6D6, 293 K):
Yield: 130 mg (85%). IR (Nujol): ν(NH) 3386 cm-1. H NMR
1
(300 MHz, CD2Cl2, 293 K): δ 12.81 (br, 1 H, NH), 8.22 (m, 1
H, Ph), 7.72-7.52 (m, 6 H, Ph), 7.06-6.98 (m, 2 H, Ph), 5.77
(s, 5 H, Cp), 2.43 (m, 3 H, PCH), 1.18 (dd, J (HH) ) 6.9 Hz,
J (PH) ) 14.7 Hz, 9 H, PCCH3), 0.94 (dd, J (HH) ) 7.2 Hz,
J (PH) ) 13.8 Hz, 9 H, PCCH3), -12.98 (d, J (PH) ) 38.2 Hz, 1
H, OsH). 31P{1H} NMR (121.42 MHz, CD2Cl2, 293 K): δ 20.9.
13C{1H} NMR (75.42 MHz, CD2Cl2, 293 K, plus APT): δ 190.1
(-, d, J (PC) ) 2.8 Hz, NdC), 165.3 (-, d, J (PC) ) 3.7 Hz, Os-
C), 147.5 (-, s, ipso-Ph), 146.2 (+, s, Ph), 134.6 (-, s, ipso-
Ph), 132.3, 131.0, 130.2, 130.2, 129.9, 1292, 128.7, 122.7 (+,
all s, Ph), 85.9 (+, s, Cp), 28.2 (+, d, J (PC) ) 29.9 Hz, PCH),
20.4 (+, s, PCCH3), 18.7 (+, d, J (PC) ) 2.3 Hz, PCCH3). Anal.
Calcd for C27H37ClNOsP: C, 51.29; H, 5.89; N, 2.21. Found:
C, 50.86; H, 6.43; N, 2.21. MS (FAB+): m/e 598 (M+).
P r ep a r a tion of [OsH(η5-C5H5){NHdC(P h )C6H4}(P iP r 3)]-
BF 4 (2b). A solution of 2a (100 mg, 0.16 mmol) in 10 mL of
THF was treated with sodium tetrafluoroborate (19.1 mg, 0.17
mmol). After stirring for 20 min at room temperature the
brown solution obtained was concentrated to dryness. The
product was extracted with 8 mL of dichloromethane. The
suspension was filtered through Kieselguhr and concentrated
to dryness. Addition of diethyl ether caused the precipitation
of a brown solid, which was separated by decantation, washed
with diethyl ether, and dried in vacuo. Yield: 101.5 mg (94%).
IR (Nujol): ν(NH) 3286 cm-1, ν(BF4) 1073 cm-1. 1H NMR (300

Reactions of Os(η5-C5H5)Cl(PiPr3)2
Organometallics, Vol. 19, No. 3, 2000 283
δ 3.5 (d, J (PP) ) 16.8 Hz, PiPr3), -5.7 (d, J (PP) ) 16.8 Hz,
PPh3). Anal. Calcd for C32H41ClOsP2: C, 53.88; H, 5.79.
Found: C, 54.34; H, 5.88. MS (FAB+): m/e 714 (M+), 679 (M+
- Cl).
with 1.0 mL of methanol. After the mixture was stirred for 15
min at room temperature, the solution was filtered through
Kieselguhr. The solvent was removed to dryness, and 5 mL of
pentane was added. The yellow solid obtained was separated
by decantation and dried in vacuo. Yield: 80.8 mg (85%). IR
P r ep a r a tion of [OsH(η5-C5H5)(P P h 2C6H4)(P iP r 3)]P F 6
(6). A solution of 5 (285 mg, 0.40 mmol) in 10 mL of acetone
was treated with 140 mg (0.40 mmol) of thallium hexafluoro-
phosphate. After stirring for 15 min at room temperature the
colorless solution obtained was filtered through Kieselguhr and
concentrated to dryness. The addition of diethyl ether caused
the precipitation of a white solid, which was separated by
decantation, washed with diethyl ether, and dried in vacuo.
1
(Nujol): 2052 cm-1 (OsH). H NMR (300 MHz, C6D6, 293 K):
δ 7.91 (m, 6 H, Ph), 7.07 (m, 6 H, Ph), 6.98 (m, 3 H, Ph), 4.46
(s, 5 H, Cp), 1.44 (m, 3 H, PCH), 1.04 (dd, J (HH) ) 7.2 Hz,
J (PH) ) 12.6 Hz, 9 H, PCCH3), 0.87 (dd, J (HH) ) 7.2 Hz,
J (PH) ) 12.6 Hz, 9 H, PCCH3), -15.27 (dd, J (PH) ) 29.7 Hz,
J (PH) ) 29.7 Hz, 1 H, OsH). 31P{1H} NMR (121.42 MHz, C6D6,
293 K): δ 33.6 (d, J (PP) ) 9.8 Hz, PiPr3), 21.2 (d, J (PP) ) 9.8
Hz, PPh3). Anal. Calcd for C32H42OsP2: C, 56.62; H, 6.24.
Found: C, 56.34; H, 6.61. MS (FAB+): m/e 681 (M+ + H).
1
Yield: 302 mg (91%). H NMR (300 MHz, CD2Cl2, 293 K): δ
8.06 (m, 2 H, Ph), 7.60 (m, 2 H, Ph), 7.48-7.31 (m, 10 H, Ph),
5.28 (s, 5 H, Cp), 2.02 (m, 3 H, PCH), 0.96 (dd, J (HH) ) 6.9
Hz, J (PH) ) 13.2 Hz, 9 H, PCCH3), 0.71 (dd, J (HH) ) 7.5 Hz,
J (PH) ) 15.3 Hz, 9 H, PCCH3), -12.10 (dd, J (PH) ) 35.7 Hz,
J (PH) ) 26.4 Hz, 1 H, OsH). 31P{1H} NMR (121.42 MHz, CD2-
Cl2, 293 K): δ 16.8 (d, J (PP) ) 18.1 Hz, PiPr3), -74.8 (d, J (PP)
) 18.1 Hz, (C6H4)PPh2). 13C{1H} NMR (75.42 MHz, CD2Cl2,
293 K, plus APT): δ 154.4 (-, d, J (PC) ) 59.9 Hz, ipso Ph),
139.7 (+, d, J (PC) ) 16.1 Hz, Ph), 133.9 (+, d, J (PC) ) 2.8
Hz, Ph), 132.6 (+, d, J (PC) ) 2.8 Hz, Ph), 132.3 (+, d, J (PC)
) 10.1 Hz, Ph), 132.2 (-, d, J (PC) ) 54.7 Hz, ipso Ph), 131.7
(+, d, J (PC) ) 2.7 Hz, Ph), 131.2 (+, s, Ph), 130.5 (+, d, J (PC)
) 10.1 Hz, Ph), 129.8 (+, d, J (PC) ) 11.5 Hz, Ph), 129.7 (+, d,
J (PC) ) 11.0 Hz, Ph), 129.0 (-, d, J (PC) ) 55.3 Hz, ipso Ph),
125.7 (+, d, J (PC) ) 10.6 Hz, Ph), 116.4 (-, dd, J (PC) ) 29.9
Hz, J (PC) ) 15.2 Hz, Os-C), 85.5 (+, s, Cp), 26.5 (+, d, J (PC)
) 29.9 Hz, PCH), 20.0 (+, s, PCCH3), 19.9 (+, d, J (PC) ) 4.1
Hz, PCCH3). Anal. Calcd for C32H41OsP3F6: C, 46.72; H, 5.02.
Found: C, 46.95; H, 5.10. MS (FAB+): m/e 679 (M+).
P r ep a r a tion of [OsH2(η5-C5H5)(P P h 3)(P iP r 3)]BF 4 (9). A
solution of 8 (70.6 mg, 0.10 mmol) in 6 mL of diethyl ether
was treated with 14.2 µL (0.10 mmol) of HBF4‚OEt2. The white
solid formed was separated by decantation, washed with
diethyl ether, and dried in vacuo. Yield: 70 mg (92%). IR
(Nujol): ν(BF4) 1065 cm-1 1H NMR (300 MHz, CD2Cl2, 293
.
K): δ 7.60-7.53 (m, 6 H, Ph), 7.51-7.46 (m, 9 H, Ph), 5.18 (s,
5 H, Cp), 1.57 (m, 3 H, PCH), 1.03 (dd, J (HH) ) 7.2 Hz, J (PH)
) 15.0 Hz, 18 H, PCCH3), -13.09 (dd, J (PH) ) 28.9 Hz, J (PH)
) 28.9 Hz, 2 H, OsH2). 31P{1H} NMR (121.42 MHz, CD2Cl2,
293 K): δ 35.4 (d, J (PP) ) 26.6 Hz, PiPr3), 9.7 (d, J (PP) )
26.6 Hz, PPh3). Anal. Calcd for C32H43BF4OsP2: C, 50.13; H,
5.65. Found: C, 49.69; H, 5.26. MS (FAB+): m/e 681 (M+).
X-r a y Str u ctu r e An a lysis of Com p lex [OsH(η5-C5H5)-
{NHdC(P h )C6H4}(P iP r 3)]BF 4 (4). The poor quality of the
crystals caused the repetition of the data collection and
refinement with different crystals. Finally, a brown, prismatic
crystal glued on a glass fiber and mounted on a Siemens-CCD
diffractometer (sealed tube 2.4 kW, λ ) 0.71073, T ) 153.0(2)
K) gave data good enough to properly solve the structure. A
summary of crystal data and refinement parameters is re-
ported in Table 3. A total of 11 782 reflections were collected
via runs of ω scans at different æ values, over a θ range of
1.7-23.5°. All data were corrected for absorption using a
semiempirical method.24 The structure was solved by Patterson
(Os atoms, SHELXL9725) and conventional Fourier techniques
and refined by full-matrix least-squares on F2 (SHELXL9725).
Two independent molecules (the A and C enantiomers) were
observed in the asymmetric unit. Anisotropic parameters were
used in the last cycles of refinement for all non-hydrogen
atoms. Hydrogen atoms (except the hydride and N-H atoms)
were included in calculated positions and refined riding on
their respective carbon atoms with the thermal parameter
related to the bonded atoms. Atomic scattering factors, cor-
rected for anomalous dispersion, were implemented by the
P r ep a r a tion of Os(η5-C5H5)(P P h 2C6H4)(P iP r 3) (7). A
solution of 6 (150 mg, 0.18 mmol) in 10 mL of THF was treated
with sodium methoxide (14.6 mg, 0.27 mmol). The mixture was
stirred for 6 h at room temperature. The yellow solution
obtained was evaporated to dryness, and 10 mL of toluene was
added. The suspension was filtered through Kieselguhr and
concentrated to dryness. Addition of methanol caused the
precipitation of a yellow solid, which was separated by
decantation and dried in vacuo. Yield: 104 mg (85%). 1H NMR
(300 MHz, C6D6, 293 K): δ 7.82 (dd, J (HH) ) 7.8 Hz, J (HH)
) 8.7 Hz, 2 H, m-Ph), 7.60 (m, 1 H, Ph), 7.45 (dd, J (HH) ) 9.6
Hz, J (HH) ) 8.4 Hz, 2 H, m-Ph), 7.19 (dd, J (HH) ) 7.5 Hz,
J (HH) ) 7.5 Hz, 1 H, Ph), 7.07-6.88 (m, 8 H, Ph), 4.50 (s, 5
H, Cp), 1.97 (m, 3 H, PCH), 0.88 (dd, J (HH) ) 7.2 Hz, J (PH)
) 12.3 Hz, 9 H, PCCH3), 0.81 (dd, J (HH) ) 7.2 Hz, J (PH) )
12.3 Hz, 9 H, PCCH3). 31P{1H} NMR (121.42 MHz, C6D6, 293
K): δ 20.9 (d, J (PP) ) 18.6 Hz, PiPr3), -71.0 (d, J (PP) ) 18.6
Hz, (C6H4)PPh2). 13C{1H} NMR (75.42 MHz, C6D6, 293 K, plus
APT): δ 161.7 (-, d, J (PC) ) 50.7 Hz, ipso Ph), 143.1 (-, dd,
J (PC) ) 17.0 Hz, J (PC) ) 11.9 Hz, Os-C), 140.4 (-, d, J (PC)
) 45.2 Hz, ipso Ph), 132.6 (+, d, J (PC) ) 10.1 Hz, Ph), 130.8
(+, d, J (PC) ) 9.4 Hz, Ph), 129.2 (+, d, J (PC) ) 4.1 Hz, Ph),
128.7 (+, d, J (PC) ) 1.8 Hz, Ph), 127.8 (+, d, J (PC) ) 2.8 Hz,
Ph), 127.7 (+, s, Ph), 119.6 (+, d, J (PC) ) 8.3 Hz, Ph), 73.6
(+, dd, J (PC) ) 2.3 Hz, J (PC) ) 2.3 Hz, Cp), 28.6 (+, dd, J (PC)
) 24.8 Hz, J (PC) ) 2.3 Hz, PCH), 20.9, 19.8 (+, both s,
PCCH3). Anal. Calcd for C32H40OsP2: C, 56.78; H, 5.95.
Found: C, 56.29; H, 5.79. MS (FAB+): m/e 678 (M+ + H).
program. The refinement converged to R1(F) ) 0.0747 [F2
>
2σ(F2)], and wR2(F2) ) 0.1914 [all data], with weighting
parameters x ) 0.1188 and y ) 7.0299.
X-r a y Str u ctu r e An a lysis of Com p lex [OsH(η5-C5H5)-
(P P h 2C6H4)(P iP r 3)]P F 6 (6). A crystal suitable for X-ray
diffraction analysis was mounted onto a glass fibber and
transferred to a Siemens-P4 automatic diffractometer (T )
296.0(2) K, Mo KR radiation, graphite monocromator, λ )
0.71073 Å). Accurate unit cell parameters and an orientation
matrix were determined by least-squares fitting from the
settings of 62 high-angle reflections. Crystal data and details
on data collection and refinements are given in Table 3. Data
were collected by the ω scan method over a θ range of 1.5-
25°. Decay was monitored by measuring three standard
Rea ction of 7 w ith HBF 4. A solution of 7 (23.6 mg, 0.034
mmol) in 0.5 mL of CD2Cl2 was treated with 4.8 µL (0.034
mmol) of HBF4‚OEt2. After 2 min at room temperature, the
NMR spectra showed only the presence of the compound [OsH-
(η5-C5H5)(PPh2C6H4)(PiPr3)]+.
P r ep a r a tion of OsH(η5-C5H5)(P P h 3)(P iP r 3) (8). A solu-
tion of 5 (100 mg, 0.14 mmol) in 10 mL of toluene was treated
with 33 mg (0.70 mmol) of NaBH4 and, after 3 min, dropwise
(24) SADABS, Area-Detector Absorption Correction; Siemens In-
dustrial Automation, Inc.: Madison, WI, 1996.
(25) Sheldrick, G. M. SHELX Suite of Programs for Crystal Structure
Analysis (Release 97-2); Institu¨t fu¨r Anorganische Chemie der Uni-
versita¨t: Tammanstrasse 4, D-3400 Go¨ttingen, Germany, 1998.

284 Organometallics, Vol. 19, No. 3, 2000
Esteruelas et al.
Ta ble 3. Cr ysta l Da ta a n d Da ta Collection a n d Refin em en t for [OsH(η5-C5H5){NHdC(P h )C6H4}(P iP r 3)]BF 4
(4) a n d [OsH(η5-C5H5)(P P h 2C6H4)(P iP r 3)]P F 6 (6)
4
6
Crystal Data
formula
molecular wt
C
27H37BF4NOsP
C32H41F6OsP3
822.76
683.56
color and habit
symmetry, space group
brown, prismatic block
orthorhombic, Pca21
29.689(2)
10.5522(8)
16.9856(13)
orange, prismatic block
monoclinic, P21/c
16.516(2)
21.221(3)
19.470(2)
101.059(6)
6697.2(14)
8
a, Å
b, Å
c, Å
â, deg
V Å3
Z
5321.2(7)
8
1.706
D
calc, g cm-3
1.632
Data Collection and Refinement
diffractometer
λ(Mo KR), Å
Siemens-CCD
0.71073
graphite oriented
4.897
ω scans at different æ values
3° e 2θ e 46.5°
153.0(2)
Siemens-P4
0.71073
graphite oriented
4.006
monochromator
µ, mm-1
scan type
2θ range, deg
temp, K
ω
3° e 2θ e 50°
296.0(2)
no. of data collect
no. of unique data
no. of params refined
R1a [F2 > 2σ(F2)]
wR2b [all data]
Sc [all data]
11 782 (h: -33, 8; k: -5, 11; l: -18, 18)
15 033 (h: 0, 19; k: -25, 25; l: -23, 22)
6767 (merging R factor 0.0398)
11 710 (merging R factor 0.0515)
581
778
0.0747
0.1914
1.054
0.0508
0.1409
1.011
R1(F) ) ∑||Fo| - |Fc||/∑|Fo|. wR2(F2) ) {∑[w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2
.
c Goof ) S ) {∑[w(Fo - Fc2)2]/(n - p)}1/2, where n is the
a
b
2
2
number of reflections and p is the number of refined parameters.
reflections every 100 measurements. Corrections for decay and
absoption (semiempirical method26) were applied. The struc-
ture was solved by Patterson (Os atoms, SHELXL9725) and
conventional Fourier techniques and refined by full-matrix
least-squares on F2 (SHELXL9725). Two independent molecules
(both the A enantiomers) were observed in the asymmetric
unit. Anisotropic parameters were used in the last cycles of
refinement for all non-hydrogen atoms. Hydrogen atoms were
included in calculated positions and refined riding on their
respective carbon atoms with the thermal parameter related
to the bonded atoms. Atomic scattering factors, corrected for
anomalous dispersion, were implemented by the program. The
refinement converged to R1(F) ) 0.0508 [F2 > 2σ(F2)], and
wR2(F2) ) 0.1409 [all data], with weighting parameters x )
0.0799 and y ) 3.877.
Ack n ow led gm en t. We thank the DGES (Project PB
95-0806, Programa de Promocio´n General del Cono-
cimiento).
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and equivalent isotropic displacement coefficients,
anisotropic thermal parameters, experimental details of the
X-ray studies, and bond distances and angles for 4 and 6. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(26) Walker, N.; Stuart, D. Acta Crystallogr., Sect. A 1995, 28, 53.
OM990538H