Formation of palladium- and platinum-substituted fulvenes by activation of a cyclopentadienyl or indenyl ligand

Article abstract of DOI:10.1021/om9806500

The stepwise, low-temperature reaction of {Pd[CH(SiMe₃)₂](/≤-Cl)(PMe₃)}₂ (1) with CNBu-t and NaCp′ (Cp′ = C₅H₅, C₅H₄Me) or Lilnd (Ind = C₉H₇) affords metal-substituted fulvenes of composition Pd[C(NHBu-t)=C(C₄H₃R)][CH(SiMe₃) ₂](CNBu-t)(PMe₃) (R = H, Me) and Pd[C(NHBu-t)=C(C₈H₆)][CH(SiMe₃) ₂](CNBu-t)(PMe₃), of which the C₅H₄Me-derived complex 5a has been characterized by X-ray crystallography. The mononuclear species Pd[CH(SiMe₃)₂]Cl(CNBu-t)(PMe₃) (2) has been isolated as an intermediate of this reaction. An alternative synthesis of the palladabenzofulvene complex 6 involves the reaction of the 16 electron indenyl derivative (η³-Ind)Pd[CH(SiMe₃)₂](PMe₃) (7) with 2 equiv of CNBu-t In this case an η¹-ndenyl intermediate of composition (η¹-Ind)Pd[CH(SiMe³)²](CNBu-t)(PMe ₃) (8) can be observed by low-temperature NMR spectroscopy. The complex Pt[CH(SiMe₃)₂]Cl(CNBu-t)(PMe₃) (12) has been synthesized by the comproportionation reaction of Pt[CH(SiMe₃)₂]Cl(PMe₃)₂ (10) and Pt[CH(SiMe₃)₂]Cl(CNBu-t)₂ (11), in the presence of catalytic amounts of CNBu-t. Complex 12 reacts with CNBu-t and NaCp to give first the cationic species {Pt[CH(SiMe₃)₂](CNBu-t)₂(PMe₃)}Cl (13) and then a mixture of platinafulvene isomers related to the above-mentioned Pd complexes. The fluxionality of these metallafulvene derivatives and the mechanism of their formation are discussed.

Full text of DOI:10.1021/om9806500

5620
Organometallics 1998, 17, 5620-5629
F or m a tion of P a lla d iu m - a n d P la tin u m -Su bstitu ted
F u lven es by Activa tion of a Cyclop en ta d ien yl or In d en yl
Liga n d
Francisco M. Al´ıas, Toma´s R. Belderra´ın, Margarita Paneque,
Manuel L. Poveda,* and Ernesto Carmona*
Departamento de Quı´mica Inorga´nica-Instituto de Investigaciones Quı´micas,
Universidad de Sevilla-Consejo Superior de Investigaciones Cientı´ficas,
C/ Ame´rico Vespucio s/ n, Isla de la Cartuja, 41092 Sevilla, Spain
Pedro Valerga
Departamento de Ciencia de Materiales e Ingenier´ıa Metalu´rgica y Quı´mica Inorga´nica,
Facultad de Ciencias, Universidad de Ca´diz, Apdo. 40, 11510 Puerto Real (Ca´diz), Spain
Received J uly 29, 1998
The stepwise, low-temperature reaction of {Pd[CH(SiMe3)2](µ-Cl)(PMe3)}2 (1) with CNBu-t
and NaCp′ (Cp′ ) C5H5, C5H4Me) or LiInd (Ind ) C9H7) affords metal-substituted fulvenes
of composition Pd[C(NHBu-t)dC(C4H3R)][CH(SiMe3)2](CNBu-t)(PMe3) (R ) H, Me) and Pd-
[C(NHBu-t)dC(C8H6)][CH(SiMe3)2](CNBu-t)(PMe3), of which the C5H4Me-derived complex
5a has been characterized by X-ray crystallography. The mononuclear species Pd[CH-
(SiMe3)2]Cl(CNBu-t)(PMe3) (2) has been isolated as an intermediate of this reaction. An
alternative synthesis of the palladabenzofulvene complex 6 involves the reaction of the 16
electron indenyl derivative (η3-Ind)Pd[CH(SiMe3)2](PMe3) (7) with 2 equiv of CNBu-t. In
this case an η1-indenyl intermediate of composition (η1-Ind)Pd[CH(SiMe3)2](CNBu-t)(PMe3)
(8) can be observed by low-temperature NMR spectroscopy. The complex Pt[CH(SiMe3)2]-
Cl(CNBu-t)(PMe3) (12) has been synthesized by the comproportionation reaction of Pt[CH-
(SiMe3)2]Cl(PMe3)2 (10) and Pt[CH(SiMe3)2]Cl(CNBu-t)2 (11), in the presence of catalytic
amounts of CNBu-t. Complex 12 reacts with CNBu-t and NaCp to give first the cationic
species {Pt[CH(SiMe3)2](CNBu-t)2(PMe3)}Cl (13) and then a mixture of platinafulvene isomers
related to the above-mentioned Pd complexes. The fluxionality of these metallafulvene
derivatives and the mechanism of their formation are discussed.
In tr od u ction
insertions involving other unsaturated molecules into
M-η1-Cp bonds have been known for many years.4 For
instance, Casey and co-workers have disclosed a CO
migratory insertion of this kind during the course of
the reaction of (η1-C5H5)Re(CH3)(CO)(NO)(PMe3)2 with
a large excess of PMe3. This gave the structurally
characterized cyclopentadienylidene ketene species
Organic isocyanides have a rich chemistry derived
from their migratory insertion into transition metal-
carbon bonds.1,2 Both η1- and η2-iminoacyl structures
have been reported to form along with a variety of
polyimino-type products derived from multiple insertion
reactions.1,2 Many different alkyl (or aryl) groups are
able to migrate onto the isocyanide carbon. However,
there seems to be no report on complexes that proceed
from the migratory insertion of the ubiquitous cyclo-
pentadienyl ligand, despite the ample precedent that
now exists for its monohapto coordination mode.3 This
contrasts with the fact that examples of related formal
Re[C(O)dC(C4H4)](NO)(PMe3)3.4a
Recently we have reported the synthesis of the η2-
iminoacyl complex Ni[η2-C(NBu-t)CH(SiMe3)2]Cl(PMe3),
the first nickel compound of this type to be structurally
authenticated by X-ray crystallography. This compound
is generated by migratory insertion of CNBu-t into the
Ni-C bond of the dimeric alkyl {Ni[CH(SiMe3)2](µ-Cl)-
(PMe3)}2.5 During the course of these studies we
(1) (a) Bonati, F.; Minghetti, G. Inorg. Chim. Acta 1974, 9, 95. (b)
Treichel, P. M. Adv. Organomet. Chem. 1973, 11, 21. (c) Singleton, E.;
Oosthuizen, H. E. Adv. Organomet. Chem. 1983, 22, 209. (d) Yama-
moto, Y.; Yamazaki, H. Coord. Chem. Rev. 1972, 8, 225. (e) Crociani,
B. In Reactions of Coordinated Ligands; Braterman, P. S., Ed.; Plenum
Press: New York, 1986; Vol. 1, Chapter 9, pp 553-638. (f) Durfee, L.
D.; Rothwell, I. P. Chem. Rev. 1988, 88, 1059.
(2) (a) Otsuka, S.; Nakamura, A.; Yoshida, T.; Naruto, M.; Ataka,
K.; J . Am. Chem. Soc. 1973, 95, 3180. (b) Yamamoto, Y.; Yamazaki,
H. Inorg. Chem. 1974, 13, 438. (c) Aoki, K.; Yamamoto, Y. Inorg. Chem.
1976, 15, 48. (d) Bellachioma, G.; Gardaci, G.; Zanazzi, P. Inorg. Chem.
1987, 26, 84. (e) Maitlis, P. M.; Espinet, P.; Russell, M. J . H. In
Comprehensive Organometallic Chemistry; Wilkinson, G., Stone, F. G.
A., Abel, E. W., Eds.; Pergamon Press: Oxford, 1982; Vol. 6, p 279.
(3) (a) O’Connor, J . M.; Casey, C. P. Chem. Rev. 1987, 87, 307. (b)
For a recent example, see: Cross, R. J .; Farrugia, L. J .; Kuma, K. E.
A. J . Organomet. Chem. 1994, 471, 273.
(4) (a) Casey, C. P.; O’Connor, J . M.; Haller, K. J . J . Am. Chem.
Soc. 1985, 107, 1241. (b) Anderson, G. K. Organometallics 1986, 5,
1903. (c) O’Hare, D. Organometallics 1987, 6, 1766. (d) Hill, M. N. S.;
J ohnson, B. F. G.; Keating, T.; Lewis, J . J . Chem. Soc., Dalton Trans.
1975, 1197.
(5) (a) Belderrain, T. R.; Paneque, M.; Poveda, M. L.; Sernau, V.;
Carmona, E.; Gutie´rrez, E.; Monge, A. Polyhedron 1995, 14, 323. (b)
Belderrain, T. R.; Paneque, M.; Poveda, M. L.; Sernau, V.; Carmona,
E.; Gutie´rrez, E.; Monge, A. Polyhedron 1996, 15, 3501.
10.1021/om9806500 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 11/20/1998

Formation of Pd- and Pt-Substituted Fulvenes
Organometallics, Vol. 17, No. 26, 1998 5621
became interested in the related chemistry of Pd- and
Pt-alkyl complexes that contain the bulky hydrocarbyl
unit CH(SiMe3)2. In this contribution we wish to report
the results of the reactions that involve the sequential
use of tert-butylisocyanide and cyclopentadienyl-type
ligands. As discussed below, the products of these
transformations have composition M[C(NHBu-t)dC-
(C4H3R)][CH(SiMe3)2](CNBu-t)(PMe3) (M ) Pd, Pt; R )
H, Me) and Pd[C(NHBu-t)dC(C8H6)][CH(SiMe3)2](CNBu-
t)(PMe3) and exhibit metallafulvene structures. At least
in a formal sense these complexes can be thought of as
deriving from the migratory insertion of the organic
isocyanide into a M-η1-Cp or M-η1-Ind bond (Ind )
C9H7), followed by tautomerization of the resulting
iminoacyl functionality. Part of this work has appeared
in a preliminary form.6
ies indicate the incorporation of a Cp and two CNBu-t
ligands and are in accord with 4 having formulation B,
i.e. the tautomeric enamine form of the imonoacyl
structure A, that would result from the formal insertion
Resu lts
Syn th esis a n d Ch a r a cter iza tion of P a lla d a fu l-
ven e Com p lexes. The reaction of 1 equiv of CNBu-t
with the recently described dimer {Pd[CH(SiMe3)2](µ-
Cl)(PMe3)}2 (1)7 cleanly and stereospecifically affords the
new isocyanide adduct Pd[CH(SiMe3)2]Cl(CNBu-t)-
(PMe3) (2), which has been fully characterized by
spectroscopy (eq 1).
of CNBu-t into a Pd-η1-Cp bond. Thus, the IR spec-
trum contains a sharp, albeit weak, absorption at ca.
3322 cm-1, indicative of the presence of a N-H bond,
whose existence is further substantiated by the observa-
tion of a broad resonance at δ 6.94 in the 1H NMR
spectrum. The 13C{1H} NMR spectrum is particularly
informative. The mutually trans arrangement of the
CNBu-t and PMe3 ligands is indicated by the strong
13C-31P coupling of 154 Hz found for the Pd-CNBu-t
nucleus (δ 139.1). The Pd-bound 13C atom of the
At variance with the results found in the analogous
Ni system,5 no insertion of the isocyanide into the Pd-
alkyl bond takes place under these conditions. How-
ever, the formation of 2 is not an unexpected observa-
tion, as neutral Pd(II)-alkyl complexes which contain
isocyanide ligands are rather inert toward this rear-
rangement. In those cases where this insertion reaction
is facile the intermediate isocyanide adduct is usually
sufficiently long-lived to be observed.1e,8
When an excess (g2 equiv) of CNBu-t is added to a
cold solution (-30 °C) of 1 in Et2O a white precipitate
forms. Due to a complex decomposition reaction, no
clean products can be isolated after work up, but
treatment of the above suspension with 1 equiv of NaCp,
also at -30 °C, furnishes, among other unidentified
compounds, the palladafulvene derivative Pd[C(NHBu-
t)dC(C4H4)][CH(SiMe3)2](CNBu-t)(PMe3) (4) in 45%
yield (eq 2). The already described complex (η5-C5H5)-
Pd[CH(SiMe3)2](PMe3) (3) is also generated in this
reaction and can be separated from 4 by fractional
crystallization.7 Analytical data and spectroscopic stud-
enamine moiety appears at low field (δ 206.0, d, 2J CP
)
5 Hz), whereas the resonances of the five nonequivalent
carbon atoms of the original Cp fragment cluster
between 102 and 129 ppm. Rotation of the C5 ring
around the CdC double bond is therefore slow in the
NMR time scale at 25 °C, in good agreement with the
behavior of related organic9 and organometallic10 sys-
tems.
The use of methylcyclopentadienyl anion allows for
the formation of the corresponding substituted fulvene
complex 5 (eq 2), which because of the presence of the
methyl group in the Cp ring is produced as a mixture
of stereoisomers. The 31P{1H} NMR spectrum of the
crude of the reaction shows the existence of three, out
of the four possible isomers 5a -d depicted in Scheme
1, in a ratio of 6:5:3. Pure samples of 5a can be isolated
by fractional crystallization from cold petroleum ether
solutions and its structure unambiguously assigned by
means of NOEDIFF experiments (Scheme 1). The most
significant NOEs are (i) Hc (δ 6.47) and the NH proton
(δ 6.99) with the protons of the methyl group of the
C5H4Me ligand; (ii) Hb (δ 6.66) with Hc and Ha (δ 7.16).
For the other isomers proton chemical shift and coupling
constant data cannot either be confidently used for
(6) Al´ıas, F. M.; Belderrain, T. R.; Paneque, M.; Poveda, M. L.;
Carmona, E.; Valerga, P. Organometallics 1997, 16, 301.
(7) Al´ıas, F. M.; Belderrain, T. R.; Carmona, E.; Graiff, C.; Paneque,
M.; Tiripicchio, A. J . Organomet. Chem., in press.
(8) (a) Otsuka, S.; Nakamura, A.; Yoshida, T. J . Am. Chem. Soc.
1969, 91, 7196. (b) Yamamoto, Y.; Yamazaki, H.; Hagihara, N. Bull.
Chem. Soc. J pn. 1968, 41, 532. (c) Yamamoto, Y.; Yamazaki, H.;
Hagihara, N. J . Organomet. Chem. 1969, 10, 189. (d) Maitlis, P. M.;
Espinet, P.; Russell, M. J . H. In Comprehesive Organometallic Chem-
istry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Pergamon:
London, 1982; Vol. 6, Chapter 38.4.
(9) Ammon, H. L. Acta Crystallogr., Sect. B 1974, 30, 1731.
(10) Legzdings, P.; Lumb, S. A.; Young, V. G., J r. Organometallics
1998, 17, 854.

5622 Organometallics, Vol. 17, No. 26, 1998
Al´ıas et al.
Sch em e 1
F igu r e 1. Molecular structure of complex 5a showing the
atom labeling scheme. Hydrogen atoms have been omitted
for clarity. ORTEP ellipsoids represent 30% probability.
C(13)-N(2) bonds (1.37(1) and 1.35(1) Å, respectively),
are similar to those found in H4C4CdC(H)NMe2.9
A similar transformation is observed when LiInd is
used instead of a cyclopentadienyl reagent. Upon
stepwise addition of 2 equiv of CNBu-t and 1 equiv of
LiInd to solutions of 2 at low temperatures the benzo-
annulated fulvene derivative Pd[C(NHBu-t)dC(C8H6)]-
[CH(SiMe3)2](CNBu-t)(PMe3) (6) is formed in a ca. 40%
yield (eq 3). The presence of an absorption at 3390 cm-1
Ta ble 1. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 5a
Pd-P
2.295(3)
2.17(1)
1.99(1)
2.09(1)
1.37(1)
1.35(1)
P-Pd-C(1)
P-Pd-C(8)
89.3(2)
170.9(3)
89.0(3)
92.3(4)
177.8(4)
89.1(4)
Pd-C(1)
Pd-C(8)
Pd-C(13)
C(13)-C(14)
C(13)-N(2)
P-Pd-C(13)
C(1)-Pd-C(8)
C(1)-Pd-C(13)
C(8)-Pd-C(13)
unequivocal structural identification but as for 5a
NOEDIFF experiments prove conclusive. Thus, ir-
radiation of the resonance corresponding to the ring
methyl group of the other two fulvene species produces
NOE effects with two neighboring protons. This implies
that these species are 5b and 5c, for the case of 5d only
one NOE effect (with Ha) would have been observed
(Scheme 1). Finally we have also made use in this
analysis of the closer similarity expected for the chemi-
cal shifts of Ha and Hb in isomers 5a and 5b in
comparison with 5c. The ratio in which these complexes
appear to coexist is 5a /5b/5c ) 5:6:3, and while the 5b/
5c proportion is probably thermodynamic in nature
because of the effective rotation around the CdC bond
in the laboratory time scale,9,10 the fraction of 5a may
reflect the kinetic distribution of the reaction.
The structure of the 5a isomer has been confirmed
by X-ray diffraction methods. Selected bond distances
and angles can be found in Table 1. As can be observed
in Figure 1, the Pd center is in a distorted square-planar
coordination environment, with the terminal isocyanide
carbon atom C(8) presenting the largest deviation (0.28
Å) from the least-squares plane defined by Pd, P, C(1),
C(8), and C(13). The fulvene moiety is planar and is
almost perpendicular to the Pd coordination plane
(dihedral angle of 80.77°), possibly to minimize adverse
steric interactions. The Pd-C(1) bond of 2.17(1) Å is
somewhat longer than Pd-C(13) at 2.09(1) Å due to
differences in the hybridization at carbon. The latter
length is in the range normally found for the Pd-C(sp2)
bonds.11 The remaining bond distances within the
fulvene unit, particularly those of C(13)-C(14) and
in the IR spectrum, and an associated broad singlet at
δ 7.27 in the 1H NMR spectrum are indicative of the
existence of a NH group. Additionally the analysis of
1
the resonances found in both the H and the 13C{1H}
NMR spectra reveal the presence of a fulvene unit (in
this case with a fused benzene ring) bonded to the metal
center through the exo carbon (δ 196.7). The ligand
disposition around the metal center is easily deduced
1
from the H and 13C{1H} NMR spectra as has already
been detailed for 4 and 5. Two possible stereoisomers
(“rotamers”) are to be expected depending on the relative
position of the benzene ring with respect to the amino
group, but just one is observed by NMR spectroscopy.
The presence of a NOE effect on Ha upon saturation of
the PMe3 protons clearly shows that the favored stere-
oisomer is the one depicted in eq 3.
Interestingly, the fulvene derivative 6 can be prepared
by reaction of the indenyl complex (η3-Ind)Pd[CH-
(SiMe3)2](PMe3) (7)7 with 2 equiv of CNBu-t. In an
attempt to gain mechanistic information this transfor-
mation has been monitored by low temperature NMR
spectroscopy. Only 1 equiv of the isocyanide reacts
initially, and an η1-indenyl species 8 is cleanly formed
at -50 °C (Scheme 2). Particularly informative from a
structural point of view is the presence of a doublet in
(11) (a) Onitsuka, K.; Ogawa, H.; J oh, T.; Takahashi, S.; Yamamoto,
Y.; Yamazaki, H. J . Chem. Soc., Dalton Trans. 1991, 1531. (b) Veya,
P.; Floriani, C.; Chiesa-Villa, A.; Rizzoli, C. Organometallics 1993, 12,
4899.

Formation of Pd- and Pt-Substituted Fulvenes
Organometallics, Vol. 17, No. 26, 1998 5623
Sch em e 2
the 13C{1H} NMR spectrum at δ 48.15 (2J CP ) 69 Hz).
This is assigned to the methyne group of the Pd-CH-
(ind) moiety and the strong 13C-31P coupling is indica-
tive of the trans disposition of the η1-indenyl ligand with
respect to the PMe3 group. The spectroscopic data
recorded for 8 are similar to those found for other
transition metal η1-indenyl complexes that have been
reported in the literature.12 The clean formation of
intermediate 8 implies that the isocyanide attacks
selectively the Pd atom at one of the pseudoallylic
positions of 7, that which is trans with respect to the
CH(SiMe3)2 group (Scheme 2).
tained. In accord with this result, the reaction of 9 with
2 equiv of PMe3 cleanly gives the bis(phophine) adduct
10 (eq 5) which is generated as a kinetic mixture of the
If the reaction temperature is allowed to reach 0 °C,
8 gradually disappears and the resonances correspond-
ing to the indenylfulvene species 6 (among those of other
species) concomitantly grow up in the 1H NMR spectrum
of the reaction mixture.
Syn t h esis of P t [CH (SiMe3)2]Cl(CNBu -t)(P Me3)
(12). To gain further information about the mechanism
of formation of these palladafulvene complexes and with
the expectation of isolating reaction intermediates we
decided to study the related Pt system. As an entry to
this chemistry the complex Pt[CH(SiMe3)2]Cl(cod) (9)
(cod ) 1,5-cyclooctadiene) was prepared by the proce-
dure described13 by Young and co-workers for the
synthesis of related alkyls (eq 4).
cis and trans isomers in a 3:1 ratio. The former, i.e.,
the cis-10 isomer can be readily isolated by fractional
crystallization from petroleum ether/Et2O mixtures. The
analysis of its 31P{1H} NMR spectrum is straightfor-
ward14 and merits no further comment but for the trans
isomer the corresponding spectrum is somewhat more
complicated due to the restricted rotation around Pt-
CH(SiMe3)2 bond. This behavior, also observed in the
Pd analogue,7 makes the two PMe3 ligands non equiva-
lent in the NMR time scale at 25 °C, and therefore the
31P{1H} NMR spectrum consists of the superposition of
two spin systems: the ABX of the 196Pt (S ) 1/2)-
containing molecules (ca. 34%) and the AB that corre-
sponds to other Pt isotopomers. The strong coupling
constant between the two phosphorus nuclei (2J PP ) 500
Hz) demonstrates the mutual trans disposition of the
phosphine ligands.15
All the efforts directed to obtain a dimeric Pt complex
similar to 1 by addition of 1 equiv of PMe3 to solutions
of 9 were unsuccessful, and equimolecular mixtures of
unreacted starting material and the monomeric com-
pound Pt[CH(SiMe3)2]Cl(PMe3)2 (10) were always ob-
Since the reaction of 9 with 1 equiv of PMe3, already
discussed, does not give the monophosphine complex
analogue of 1 a different synthetic strategy was devised
to prepare the desired mononuclear species Pt[CH-
(14) Appleton, T. G.; Clark, H. C.; Manzer, L. E. Coord. Chem. Rev.
1973, 10, 335.
(15) (a) Anderson, G. K.; Black, D. M.; Cross, R. J .; Robertson, F.
J .; Rycroft, D. S.; Wat, R. K. M. Organometallics 1990, 9, 2568. (b)
Siedle, A. R.; Gleason, W. B.; Newmark, R. A. Organometallics 1986,
5, 1969.
(12) (a) Casey, C. P.; O’Connor, J . M. Organometallics 1985, 4, 384.
(b) Herrmann, W. A.; Ku¨hn, F. E.; Roma˜o, C. C. J . Organomet. Chem.
1995, 489, C56.
(13) (a) Thomson, S. K.; Young, G. B. Polyhedron 1988, 7, 1953. (b)
Kelly, R. D.; Young, G. B. Polyhedron 1989, 8, 433.

5624 Organometallics, Vol. 17, No. 26, 1998
Al´ıas et al.
(SiMe3)2]Cl(CNBu-t)(PMe3) (12). Treatment of 9 with
2 equiv of CNBu-t affords the complex Pt[CH(SiMe3)2]-
Cl(CNBu-t)2 (11) exclusively as the trans isomer (eq 6).
and also with the observation of almost identical NMR
spectroscopic parameters for the species that results
when the chloride anion is replaced by the non coordi-
-
Analytical and spectroscopic data for this complex are
collected in the Experimental Section and are in accord
with the proposed formulation. When an equimolar
mixture of cis-10 and trans-11 is dissolved in Et2O and
treated with a catalytic amount of CNBu-t (or PMe3) a
ligand redistribution reaction16 takes place and complex
12 is generated as a mixture of the two isomers shown
in eq 7 (4:1 ratio). The trans configuration of the major
nating BAr4 anion (Ar ) 3,5-bis(trifluoromethyl)-
phenyl).18
Compound 13 reacts at low temperature with NaCp
to produce a mixture of several compounds (31P NMR
evidence) (eq 9). One of them, the platinafulvene 14a
2
(δ Pt-CH(SiMe3)2 -3.0, J CP ) 69 Hz), is isolated as a
brown-yellow crystalline solid by crystallization from
Et2O:petroleum ether solutions in ca. 40% yield. The
minor isomer 14b has the PMe3 cis to both the alkyl
species, 12a , is attested by the strong coupling that
exists between the methyne carbon, CH(SiMe3)2, and
the phosphorus nucleus of the PMe3 ligand (δ ) 16.0,
2J CP ) 77 Hz).13a As for the minor isomer 12b the cis
disposition of the PMe3 and chloride ligands can be
deduced from the analysis of the 195Pt satellites of 31P-
{1H} NMR spectrum (δ -15.3, 1J PPt ) 1750 Hz).14 It is
interesting to note that the Pd derivative 2 stereochem-
istry is identical to the less favored Pt isomer 12b.
Syn th esis a n d Ch a r a cter iza tion of P la tin a fu l-
ven e Der iva tives. In contrast with the behavior of 2,
the addition of an excess (g2 equiv) of tert-butylisocya-
nide to 12 results in the isolation (ca. 75% yield) of a
pure stable compound. This has been identified as the
cationic species {Pt[CH(SiMe3)2](CNBu-t)2(PMe3)}Cl (13)
(eq 8). This reaction is not unexpected. In fact, the
displacement of a chloride ligand by an isocyanide is a
well-known reaction in the chemistry of square-planar
Pt(II) complexes.17 The proposed trans geometry of 13
is based on NMR spectroscopic studies (2J CP ) 54 Hz
for the CH(SiMe3)2 carbon nucleus) whereas its ionic
formulation is in accord with its low solubility in Et2O
2
and the fulvene ligands (δ -7.5, d, J CP ) 5 Hz, CH-
(SiMe3)2 and δ 195, d, 2J CP ) 9 Hz, fulvene exo carbon).
As shown in Figure 2, complex 14a exhibits fluxional
behavior in solution. The two rotamers E and F that
are present at low temperatures in a ca. 1:7 ratio
(acetone-d6) interconvert rapidly in the NMR time scale
at higher temperatures. They are assigned as E and F
and are proposed to arise from restricted rotation
around C-N bond (see canonical form D) differing in
the spatial orientation of the Pt and Bu-t moieties (E,
trans; F , cis;19 Figure 2). The major rotamer F is
(18) Brookhart, M.; Grant, B.; Volpe, A. F., J r. Organometallics 1992,
11, 3920.
(16) Cooper, D. G.; Powell, J . J . Am. Chem. Soc. 1973, 95, 1102.
(17) Briggs, J . R.; Constable, A. G.; McDonald, W. S.; Shaw, B. L.
J . Chem. Soc., Dalton Trans. 1982, 1225.
(19) (a) Cross, R. J .; Davidson, M. F. J . Chem. Soc., Dalton Trans.
1988, 1147. (b) Crociani, B.; Richards, R. L. J . Chem. Soc., Dalton
Trans. 1974, 693.

Formation of Pd- and Pt-Substituted Fulvenes
Organometallics, Vol. 17, No. 26, 1998 5625
tory insertion of CNBu-t into a M-η1-Cp′ or M-η1-Ind
linkage, are initially formed in the reactions leading to
the metallafulvene complexes described in this paper.
Subsequent tautomerization to the more stable enamine
form (see for example B) leads to final products of these
reactions. A similar transformation has been advanced
to explain the generation of the keteneimine Ph3-
HC4dCdCNR in the reaction of PdCl2(CNR)2 with KC5-
Ph3H, but the purported palladafulvene complex inter-
mediate could not be detected.20 To our knowledge
compounds 4, 5, 6, and 14 find no precedent in the
literature, even though complexes of the transition
metals that contain fulvene ligands are well-known.21
In our view, their closest analogues are some cobal-
tafulvenes that possess a CodC-CHdCH-CHdCH
delocalized fragment22 and a recently described tung-
sten derivative that has an N-deprotonated 6-amino-
fulvene ligand.10
The higher stability of the enamine form B, as
compared to the iminoacyl structure A, is unusual in
transition metal chemistry, where the imine formulation
is clearly predominant.23 Moreover, organic enamines
that contain a hydrogen atom bonded to nitrogen are
commonly unstable with respect to their imine tau-
tomers.24 It is evident that the adoption of the enamine
structure in the compounds described herein is due to
the stability of the fulvene moiety, doubtless associated
with the extensive electronic delocalization of this
structure.25
In closing, some comments devoted to the mechanism
of the reaction that leads to the proposed iminoacyl
products with structure of type A appear appropriate.
Two reactions pathways, routes a and b of Scheme 3,
may be considered. The first involves initial attack at
the metal cationic center by Cp′ or indenyl ligand
followed by a migratory insertion reaction. The second
implicates direct attack at a coordinated isocyanide
ligand. Despite our efforts we have been unable to
distinguish conclusively between these possibilities. The
observation of more than one stereoisomer in some of
these reactions (for example 14a and 14b, eq 9) would
be in favor of route a since a neutral five-coordinate
species of the kind illustrated in Scheme 3 could readily
undergo isomerization even at low temperatures. There
is precedent in the literature for Pd- and Pt-η1-Cp
complexes26 as well as for five-coordinated M(II) com-
pounds of these elements.27 Furthermore, as already
1
F igu r e 2. Variable temperature H NMR spectra of 14a
(acetone-d6) in the range from 2.0 to -0.4 ppm.
3
characterized by a J HPt coupling of 105 Hz between the
N-H proton and the 195Pt nucleus whereas for the
minor, E, a value of ca. 40 Hz can be extracted from
1
the H NMR spectrum recorded in toluene at -30 °C.
These data are similar to those previously reported for
related species.19b In keeping with these considerations
only two resonances due to the C5H4 fragment can be
1
observed in the H NMR spectrum in the fast-exchange
regime.
(20) Tanese, T.; Fukushima, T.; Nomura, T.; Yamamoto, Y. Inorg.
Chem. 1994, 33, 32.
Interestingly the minor isomer 14b, which has trans
PMe3 and CNBu-t ligands (see eq 9), does not exhibit
any sign of fluxionality and resembles in this regard the
palladafulvene compounds already described. Hence for
this species canonical form D has a smaller contribution
to the electronic structure thereby explaining the higher
double-bond character of the Cexo-C5H4 linkage and the
faster rotation around the Cexo-N bond. The 3J HPt value
of 70 Hz found for the amine proton of this complex
clearly indicates the presence of fast equilibrating
rotamers of types E and F .
(21) (a) Bandy, J . A.; Mtetwa, V. S. B.; Prout, K.; Green, J . C.;
Davies, C. E.; Green, M. L. H.; Hazel, N. J .; Izquierdo, A.; Martin-
Polo, J . J . J . Chem. Soc., Dalton Trans. 1985, 2037. (b) Schock, L. E.;
Brock, C. P.; Marks, T. J . Organometallics 1987, 6, 237. (c) Glueck, D.
S.; Bergman, R. G. Organometallics 1990, 9, 2862. (d) McDade, C.;
Green, J . C.; Bercaw, J . E. Organometallics 1982, 1, 1629. (e) Gusev,
O. V.; Sergeev, S.; Saez, I. M.; Maitlis, P. M. Organometallics 1994,
13, 2059. (f) Blake, A. J .; Dyson, P.; J ohnson, B. F. G.; Reed, D.;
Shephard, D. S. J . Chem. Soc., Chem. Commun. 1994, 1347. (g) Kerber,
R. C.; Ehntholt, D. J . Synthesis 1970, 9, 449. (h) Teuber, R.; Ko¨ppe;
Linti, G.; Tacke, M. J . Organomet. Chem. 1997, 545-546, 105.
(22) Wadepohl, H. Comments Inorg. Chem. 1994, 15, 369.
(23) For some exceptions, see: Ca´mpora, J .; Hudson, S. A.; Carmona,
E. Organometallics 1995, 14, 2151 and references therein.
(24) (a) Lammertsma, K.; Prasad, B. V. J . Am. Chem. Soc. 1994,
116, 642. (b) De J eso, B.; Pommier, J . C. J . Chem. Soc., Chem.
Commun. 1977, 565.
Discu ssion
(25) Bergman, E. D. Chem. Rev. 1968, 68, 41.
(26) Anderson, G. K. Synlett 1995, 681.
It appears reasonable to suggest that iminoacyl
complexes of type A, formally derived from the migra-
(27) Canty, A. J .; van Koten, G. Acc. Chem. Res. 1995, 28, 406.

5626 Organometallics, Vol. 17, No. 26, 1998
Al´ıas et al.
Sch em e 3
mentioned related reactions that involve formal migra-
tory insertions of unsaturated molecules into M-η1-Cp
bonds are known.4a Notwithstanding the above, the
observations summarized in Scheme 3 are also consis-
tent with route b, i.e., with a direct attack onto the
coordinated isocyanide ligand.
isocyanide ligand. Similar mechanistic proposals have
been suggested for somewhat related processes.30 Hence,
as already indicated, it is not clear whether our fulvene
compounds are formed by either route a or b, the
additional possibility also exists that both pathways
may be operative under the reaction conditions.
As already mentioned, the addition of 2 equiv of
CNBu-t to a solution of the palladium-indenyl complex
7 in THF-d8, maintained at -50 °C, gives the η1-indenyl
derivative 8. Subsequent reaction with 1 equiv of NaCp
at -30 °C leads to the fulvene complexes 4 and 6 in ca.
1:1 ratio, along with very small amounts of the η5-C5H5
derivative 3 (Scheme 4). These results may be inter-
preted by assuming indenyl displacement by the iso-
cyanide28 and formation of an undetected cationic
bis(isocyanide) complex of palladium analogous to 13
that contains an η0-Cp or η0-Ind group as the counter-
anion,3,29 that is, with the generation of the fulvene
derivatives entailing a direct attack onto a coordinated
Exp er im en ta l Section
Microanalyses were performed by the Analytical Service of
the University of Seville. The spectroscopic instruments used
were Perkin-Elmer models 577 and 684 for IR spectra and
Bruker AMX-300 and AMX-500 for NMR spectroscopy. Spec-
tra are referenced to external SiMe4 using the residual protio
solvent peaks as internal standards (1H NMR experiments)
or the characteristic resonances of the solvent nuclei (13C NMR
experiments). 31P{1H} NMR chemical shifts are referenced to
external 85% H3PO4. All preparations and other operations
were carried out under oxygen-free nitrogen by conventional
Schlenk techniques. Solvents were dried and degassed before
use. The petroleum ether used had a boiling point of 40-60
°C. NaCp was prepared from NaH and freshly cracked
(28) For
a related process, see: Butts, M. D.; Bergman, R. G.
Organometallics 1994, 13, 1899.
(29) (a) Marder, T. B.; Williams, I. D. J . Chem. Soc., Chem. Commun.
1987, 1478. (b) Kakkar, A. K.; Taylor, N. J .; Marder, T. B. Organo-
metallics 1989, 8, 1765.
(30) For an example of a nucleophilic attack of a free indenyl anion
to one of the double bonds of a coordinated COD in a Ir(I) complex,
see: Merola, J . S.; Kacmarck, R. T. Organometallics 1989, 8, 778.

Formation of Pd- and Pt-Substituted Fulvenes
Organometallics, Vol. 17, No. 26, 1998 5627
Sch em e 4
dicyclopentadiene. Compounds {Pd[CH(SiMe3)2](µ-Cl)(PMe3)}2
(1), (η3-Ind)Pd[CH(SiMe3)2](PMe3) (7)7 and PtCl2(cod)31 were
prepared according to the reported procedures.
P r epar ation of P d[C(NHBu -t)dC(C4H3Me)][CH(SiMe3)2]-
(CNBu -t)(P Me3) (5). The methylcyclopentadienyl derivative
5 was obtained as a mixture of stereoisomers (NMR evidence)
following a similar procedure to that described above but using
NaC5H4Me. Fractional crystallization at -30 °C from petro-
leum ether solutions afforded only one stereoisomer, 5a , as
P r ep a r a tion of P d [CH(SiMe3)2]Cl(CNBu -t)(P Me3) (2).
CNBu-t (0.36 mmol, 0.36 mL of a 1 M solution in THF) was
added to a cold (-30 °C) solution of complex 1 (0.14 g, 0.18
mmol) in Et2O (10 mL). An instantaneous discoloration was
observed and the mixture stirred at that temperature for 30
min. The solvent was stripped off in vacuo, and the white
residue was extracted with a mixture of petroleum ether and
Et2O (1:1). Concentration and cooling at -30 °C provided
compound 2 as a white crystalline solid in essentially quan-
white crystals. Yield 40%. IR (Nujol): ν(NH) 3330, ν(CN)
3
2182 and 1520 cm-1
.
1H NMR (C6D6, 25 °C) δ -0.69 (d, J HP
) 14.2 Hz, 1H, CH(SiMe3)2), 0.38 (s, 9H, SiMe3), 0.51 (s, 9H,
2
SiMe3), 0.88 (s, 9H, CNCMe3), 0.95 (d, J HP ) 9.6 Hz, 9H,
PMe3), 1.38 (s, 9H, NHCMe3), 2.59 (s, 3H, Me-CC4H3), 6.47 (m,
4
4
3J HH ) 2.6, J HH ) 2.2, J HMe ) 1.1 Hz, 1H, CHfulv), 6.66 (dd,
titative yield. IR (Nujol): ν(CN) 2200 cm-1 1H NMR (C6D6,
.
3J HH ) 4.4 Hz, 3J HH ) 2.6 Hz, 1H, CHfulv), 6.99 (br s, 1H, NH),
25 °C) δ 0.18 (d, 3J HP ) 12.0 Hz, 1H, CH(SiMe3)2), 0.28 (s, 18H,
7.16 (dd, J HH ) 4.4 Hz, J HH ) 2.2 Hz, 1H, CHfulv); 13C{1H}
3
4
2
2
SiMe3), 0.93 (s, 9H, CNCMe3), 1.12 (d, J HP ) 10.2 Hz, 9H,
NMR (C6D6, 25 °C) δ -0.3 (d, J CP ) 6 Hz, CH(SiMe3)2), 4.9
(SiMe3), 5.3 (SiMe3), 14.5 (d, J CP ) 31 Hz, PMe3), 19.0 (Me-
PMe3); 13C{1H} NMR (C6D6, 25 °C) δ 4.0 (SiMe3), 7.8 (CH-
1
1
(SiMe3)2), 13.8 (d, J CP ) 32 Hz, PMe3), 29.0 (CMe3), 56.7
CC4H3), 28.9 (CMe3), 31.4 (NHCMe3), 57.5 (CMe3), 57.7 (NH-
CMe3), 115.0, 120.0, 124.6 (CHfulv), 117.1 (CdCC(Me)C3H3),
(CMe3), 138.2 (d, 2J CP ) 170 Hz, CNBu-t); 31P{1H} NMR (C6D6,
25 °C) δ -8.1.
2
129.0 (CdCC(Me)C3H3), 140.0 (d, J CP ) 159 Hz, CNBu-t),
2
200.6 (d, J CP ) 8 Hz, CdCC(Me)C3H3); 31P{1H} NMR (C6D6,
P r ep a r a tion of P d [C(NHBu -t)dC(C4H4)][[CH(SiMe3)2]-
(CNBu -t)(P Me3) (4). A solution of complex 1 (0.19 g, 0.25
mmol) in Et2O (30 mL) was cooled to -30 °C and treated with
a solution of CNBu-t in THF (2.6 mL, 0.57 M, 1.48 mmol). The
solution became colorless, and the formation of a white
precipitate was observed. After stirring for 30 min at this
temperature, a solution of NaCp was added (1.3 mL, 0.37 M,
0.48 mmol). The orange mixture formed was maintained at
-30 °C for 15 min and after stirring for the same period of
time at room temperature the solvent was evaporated under
vacuo, and the residue was extracted with a mixture of
petroleum ether/ethyl ether (30 mL, 2:1) and filtered. After
concentration and cooling at -30 °C, complex 4 was obtained
as white crystals (0.13 g, 45%). Anal. Calcd for C25H43N2Si2-
PPd: C, 52.38; H, 8.97; N, 4.89. Found: C, 51.95; H, 8.85; N,
25 °C) δ -16.3.
P r ep a r a tion of P d [C(NHBu -t)dC(C8H6)][[CH(SiMe3)2]-
(CNBu -t)(P Me3) (6). A solution of the dimer 1 (0.22 g, 0.28
mmol) in Et2O (25 mL) was treated, at -30 °C, with a solution
of CNBu-t in THF (1.2 mL, 1 M, 1.2 mmol). The solution
became colorless, and, after stirring for 30 min at low tem-
perature, a solution of LiInd (0.57 mmol, prepared by reaction
of a solution of indene in Et2O with n-BuLi) was added. The
intense yellow mixture was stirred at -30 °C for 30 min and
then taken to dryness. The resulting oily residue was redis-
solved in Et2O (3 mL), and purification was achieved by
chromatography at -15 °C (alumina as the static phase and
a 1:1 mixture of light petroleum/Et2O as eluant). Compound
6 was recovered as a yellow band and concentration of this
fraction, and cooling to -30 °C provided the product as a yellow
powder. Yield 0.14 g (40%). Anal. Calcd for C29H53N2Si2-
PPd: C, 55.89. Found: C, 55.59; H, 8.56; N, 4.57.; H, 8.51; N,
1
4.60. IR (Nujol): ν(NH) 3322, ν(CN) 2190 and 1508 cm-1. H
NMR (C6D6, 25 °C) δ -0.67 (d, 3J HP ) 14.5 Hz, 1H, CH(SiMe3)2),
0.35 (s, 9H, SiMe3), 0.50 (s, 9H, SiMe3), 0.89 (s, 9H, CNCMe3),
2
0.95 (d, J HP ) 9.4 Hz, 9H, PMe3), 1.29 (s, 9H, NHCMe3), 6.66
1
4.49. IR (Nujol): ν(NH) 3390, ν(CN) 2180 and 1530 cm-1. H
(m, 1H, CHfulv), 6.80 (m, 2H, CHfulv), 6.95 (br s, 1H, NH), 7.20
NMR (C6D6, 25 °C) δ -0.66 (d, 3J HP ) 14.0 Hz, 1H, CH(SiMe3)2),
2
(m, 1H, CHfulv); 13C{1H} NMR (CD2Cl2, 25 °C) δ 0.5 (d, J CP
)
0.37 (s, 9.0 H, SiMe3), 0.51 (s, 9H, SiMe3), 0.76 (s, 9H,
1
5 Hz, CH(SiMe3)2), 4.6 (SiMe3), 5.0 (SiMe3),15.1 (d, J CP ) 32
Hz, PMe3), 29.6 (CMe3), 31.4 (NHCMe3), 53.5 (CMe3), 57.7
(NHCMe3), 102.2, 114.7, 120.4, 123.6 (CHfulv), 129.2 (Cd
2
CNCMe3), 0.87 (d, J HP ) 9 Hz, 9H, PMe3), 1.40 (s, 9H,
NHCMe3), 6.99 (d, 3J HH ) 4.7 Hz, 1H, CHcpring), 7.27 (br s, 1H,
3
3
NH), 7.29 (t, J HH ) 7.5 Hz, 1H, CHbenzring), 7.38 (t, J HH ) 7.5
2
2
CC4H4), 139.1 (d, J CP ) 154 Hz, CNBu-t), 206.0 (d, J CP ) 9
3
Hz, 1H, CHbenzring), 7.76 (d, J HH ) 4.7 Hz, 1H, CHcpring), 7.83
Hz, CdCC4H4). 31P{1H} NMR (C6D6, 25 °C) δ -15.0.
3
3
(d, J HH ) 7.4 Hz, 1H, CHbenzring), 7.94 (d, J HH ) 7.7 Hz, 1H,
CHbenzring); 13C{1H} NMR (C6D6, 25 °C) δ -0.1 (d, J CP ) 5 Hz,
2
(31) McDermott, J . X.; White, J . F.; Whitesides, G. M. J . Am. Chem.
Soc. 1976, 98, 6521.
1
CH(SiMe3)2), 4.9 (SiMe3), 5.2 (SiMe3), 14.5 (d, J CP ) 30 Hz,

5628 Organometallics, Vol. 17, No. 26, 1998
Al´ıas et al.
2
PMe3), 28.7 (CMe3), 31.4 (NHCMe3), 52.8 (CMe3), 56.9 (NH-
CMe3), 112.4, 118.0 (CHcpring), 119.8 (CdCC8H6), 120.3, 120.8,
134.3 (CHbenzring), 129.9. 140.6 (Cq), 196.7 (d, 2J CP ) 9 Hz, Cd
CC8H6); 31P{1H} NMR (C6D6, 25 °C) δ -16.1.
Hz, PMe3); 31P{1H} NMR (C6D6, 25 °C) δ -17.3 (d, J PP )15,
1J PPt ) 1830 Hz) and -28.2 (d, J PP ) 15, J PPt ) 4150 Hz).
2
1
Data for trans-10: 1H NMR (C6D6, 25 °C) δ 0.03 (s, 9H, SiMe3),
3
3
0.06 (s, 9H, SiMe3), 0.48 (dd, J HP ) 15.0 Hz, J HP ) 10.0 Hz,
2
3
1H, CH(SiMe3)2), 1.46 (dd, J HP ) 8.6 Hz, J HP ) 1.0 Hz, 9H,
R ea ct ion of Com p lex 7 w it h CNBu -t. F or m a t ion of
P d (η1-C9H7)[CH(SiMe3)2](CNBu -t)(P Me3) (8). A solution of
complex 5 (13 mg, 0.03 mmol) in 0.5 mL of CD2Cl2 was placed
in an NMR tube and treated at -70 °C with approximately 2
equiv of CNBu-t (7.5 µL). 1H and 31P{1H} NMR spectra,
registered at -50 °C, showed the quantitative formation of
compound 8. When warmed to room-temperature decomposi-
tion of 8 was observed giving the metallafulvene 6 (30%, NMR)
plus other unidentified species. Data for 8: 1H NMR (CD2-
Cl2, -50 °C) δ -0.48 (d, 3J HP ) 19.6 Hz, 1H, CH(SiMe3)2), 0.13
(s, 9H, SiMe3), 0.22 (s, 9H, SiMe3), 1.01 (s, 9H, CNCMe3), 1.27
PMe3), 1.56 (dd, J HP ) 8.4 Hz, J HP ) 2.0 Hz, 9H, PMe3); 31P-
2
3
{1H} NMR (C6D6, 25 °C) δ -12.0 (d, J PP ) 500 Hz, J PPt
)
2
1
2
1
2760 Hz) and -19.1 (d, J PP ) 500 Hz, J PPt ) 2840 Hz).
P r ep a r a tion of P t[CH(SiMe3)2]Cl(CNBu -t)2 (11). To a
solution of compound 9 (0.26 g, 0.52 mmol) in Et2O (15 mL)
was added a solution of CNBu-t in toluene (2.2 mL, 0.49 M,
1.04 mmol) at room temperature, and the mixture stirred for
a period of 8 h. The solvent was removed completely in vacuo,
and the resulting oily residue crystallized from petroleum
ether at -30 °C to give 11 as a white microcrystalline solid.
Yield 0.14 g (50%). Anal. Calcd for C17H37N2Si2ClPt: C, 36.71;
2
(d, J HP ) 8.9 Hz, 9H, PMe3), 5.37 (br s, 1H, CHcpring), 6.55 (t,
3
1H, J HH ) 3.8 Hz, CHcpring), 6.93 (m, 2H, CHbenzring), 7.02 (m,
H, 6.66; N, 5.04. IR (Nujol): ν(CN) 2192 cm-1
. Found: C,
3
1H, CHcpring), 7.43 (d, J HH ) 6.9 Hz, 1H, CHbenzring), 7.51 (d,
36.93; H, 6.75; N, 4.69. 1H NMR (CDCl3, 25 °C) δ 0.05 (s, 18H,
3J HH ) 7.0 Hz, 1H, CHbenzring); 13C{1H} NMR (CD2Cl2, -50
SiMe3), 0.42 (s, J HPt ) 93 Hz, 1H, CH(SiMe3)2), 1.52 (s, 18H,
2
1
°C): δ 3.9 (SiMe3), 4.6 (SiMe3), 16.9 (d, J CP ) 29 Hz, PMe3),
CNCMe3); 13C{1H} NMR (CDCl3, 25 °C) δ -7.5 (1J CPt ) 509
Hz, CH(SiMe3)2), 3.71 (SiMe3), 29.9 (CMe3), 58.0 (CMe3), 129.5
(CNCMe3).
2
29.6 (coordinated CNCMe3), 30.3 (free CNCMe3), 48.2 (d, J CP
) 69 Hz, Pd-CH(ind)), 56.5 (CNCMe3), 115.6 (d, 3J CP ) 6 Hz,
CHcpring), 120.1, 120.7, 120.8, 122.6 (CHbenzring), 139.7 (CHcpring),
141.4 (Cq), 153.5 (d, 2J CP ) 4 Hz, coordinated CNBu-t); 31P{1H}
NMR (CD2Cl2, -50 °C) δ -16.6.
P r ep a r a tion of P t[CH(SiMe3)2]Cl(CNBu -t)(P Me3) (12).
To a mixture of complexes cis-10 (0.045 g, 0.08 mmol) and 11
(0.045 g, 0.08 mmol) in Et2O (10 mL) was added a trace of
CNBu-t, and the mixture stirred for 8 h at room temperature.
After that period, the solvent was evaporated under reduced
pressure and the product extracted into 10 mL of a mixture
of petroleum ether/Et2O (3:1). By concentration and cooling
to -30 °C, a white crystalline solid was obtained. Yield 0.048
g (50%). Anal. Calcd for C15H37NSi2PClPt: C, 32.8; H, 6.74;
N, 2.55. Found: C, 33.10; H, 6.95; N, 2.52. IR (Nujol): ν-
Rea ction of Com p lex 7 w ith 2 Equ iv of CNBu -t a n d 1
Equ iv of Na Cp . To a solution of complex 7 in CD2Cl2 (0.5
mL), at -30 °C, was added CNBu-t (10.5 µL). After 10 min at
this temperature, 1 equiv of NaCp (0.1 mL, 0.19 M in THF)
was added by syringe into this solution. The resulting mixture
was inmediately studied by NMR spectroscopy, and after 30
min the 1H NMR spectrum showed two doublets at δ -0.69
(3J HP ) 14.5 Hz) and -0.71 (3J HP ) 14.5 Hz) that correspond
to the two possible fulvene species 4 and 6, together with a
less intense doublet at δ -1.21 (3J HP ) 11.2 Hz) due to the
presence of 3. The 31P{1H} NMR spectrum consisted of two
singlets at δ -15.2 and -15.6 assigned to the two fulvene
complexes, and one singlet at δ -4.4 for 3 (5:5:1 ratio,
respectively). When 4 equiv of CNBu-t was used in the
reaction, the mentioned ratio of these species was 15:15:1.
P r ep a r a tion of P t[CH(SiMe3)2]Cl(cod ) (9). To a cold
(-70 °C) stirred suspension of PtCl2(cod) (2.35 g, 6.28 mmol)
in Et2O (30 mL) was added a solution of Mg[CH(SiMe3)2]Cl in
Et2O (28 mL, 0.22 N, 6.28 mmol) dropwise. The reaction
mixture was allowed to warm to room temperature and stirred
for 3 days. Filtration, concentration, and cooling to -30 °C
furnished complex 9 as white crystals. Yield 1.6 g (45%).
Anal. Calcd for C15H31Si2ClPt: C, 36.16; H, 6.23. Found: C,
36.23; H, 6.44. 1H NMR (CDCl3, -60 °C) δ 0.12 (s, 18H,
(CN) 2178 cm-1
.
Data for the major species 12a : 1H NMR
(CDCl3, 25 °C) δ 0.45 (s, 18H, SiMe3), 0.97 (s, 9H, CNCMe3),
1.09 (d, J HP ) 10.0 Hz, 9H, PMe3); 13C{1H} NMR (CDCl3, 25
2
1
2
°C) δ 4.4 (SiMe3), 14.1 (d, J CP ) 30 Hz, PMe3), 16.0 (d, J CP
)
77 Hz, CH(SiMe3)2), 30.0 (CMe3), 58.0 (CMe3); 31P{1H} NMR
(CDCl3, 25 °C) δ -18.0 (1J PPt ) 1660 Hz). Data for the minor
species 12b: 1H NMR (CDCl3, 25 °C) δ 0.64 (s, 18H, SiMe3),
0.87 (s, 9H, CNCMe3), 1.06 (d, 2J HP ) 10.0 Hz, 9H, PMe3); 31P-
{1H} NMR (CDCl3, 25 °C): δ -15.3 (1J PPt ) 1750 Hz).
P r epar ation of {P t[CH(SiMe3)2](CNBu -t)2(P Me3)}Cl (13).
To a solution of complex 12 (0.13 g, 0.24 mmol) in Et2O (10
mL) was added a solution of CNBu-t in THF (0.74 mL, 1 M,
0.74 mmol) at room temperature. After approximately 5 min,
the precipitation of a white solid was observed and the reaction
mixture stirred for 30 min. The solvent was completely
evaporated leaving a white solid. This residue was washed
with petroleum ether (10 mL) and dried in vacuo. Yield 0.11
g (75%). A sample of this complex of microanalytical purity
has proved difficult to be obtained. The formation of this
complex is however secured by the isolation of the related
2
SiMe3), 0.57 (s, J HPt ) 64 Hz, 1H, CH(SiMe3)2), 2.1-2.6 (m,
2
8H, CH2(cod)), 4.42 (m, J HPt ) 73 Hz, 2H, CH(cod)), 5.35 (m,
2J HPt ) 36 Hz, 2H, CH(cod)); 13C{1H} NMR (CDCl3, 25 °C) δ
4.2 (SiMe3), 23.2 (1J CPt ) 570 Hz, CH(SiMe3)2), 28.2 (2J CPt ) 9
Hz, CH2(cod)), 31.7 (2J CPt ) 10 Hz, CH2(cod)), 85.0 (1J CPt ) 213
Hz, CH(cod)), 111.3 (2J CPt ) 42 Hz, CH(cod)).
-
BAr4 derivative (see below) which gives reliable analytical
data. 1H NMR (CDCl3, 25 °C) δ 0.15 (s, 18H, SiMe3), 0.70 (d,
3J HP ) 8.0, J HPt ) 71 Hz, 1H, CH(SiMe3)2), 1.95 (d, J HP
)
2
2
10.0 Hz, 9H, PMe3) 1.63 (s, 18H, CNCMe3); 13C{1H} NMR
P r ep a r a tion of P t[CH(SiMe3)2]Cl(P Me3)2 (10). PMe3
(1.2 mmol, 1.2 mL of a 1 M solution in THF) was added to a
solution of complex 9 (0.26 g, 0.52 mmol) in Et2O (15 mL) at
room temperature. After stirring for 8 h, the reaction mixture
was taken to dryness and the resulting oily white residue was
extracted into a 2:1 mixture of petroleum ether/Et2O. Crystal-
lization at -30 °C afforded only the cis isomer as white crystals
(0.14 g, 50%). Concentration of the mother liquor and cooling
at -30 °C provided white crystals of the trans isomer (0.03 g,
10%). Anal. Calcd for C13H37Si2P2ClPt: C, 28.79; H, 6.83.
Found: C, 28.43; H, 7.01. Data for cis-10: 1H NMR (C6D6, 25
2
1
(CDCl3, 25 °C) δ 4.3 (SiMe3), 7.6 (s, J CP ) 54 Hz, J CPt ) 332
1
Hz, CH(SiMe3)2), 15.6 (d, J CP ) 35 Hz, PMe3), 29.8 and 29.9
(CMe3), 60.3 and 60.6 (CMe3), 125.8 (1J CPt ) 1460 Hz, CNC-
Me3), and 127.3 (1J CPt ) 1430 Hz, CNCMe3); 31P{1H} NMR
(CDCl3, 25 °C) δ -21.5 (1J PPt ) 1560 Hz).
-
P r ep a r a tion of Com p lex 13 w ith BAr 4 a s th e Cou n -
ter ion (Ar ) 3,5-Bis(tr iflu or om eth yl)p h en yl). Complex 13
(0.10 g, 0.18 mmol) and NaBAr4 (0.16 g, 0.18 mmol) were
dissolved in Et2O (15 mL) at room temperature. The formation
of a cloudy precipitate was immediately observed. After 15
min of stirring the reaction mixture was filtered, the volume
of the resulting solution was reduced to 5 mL and then cooled
to -70 °C. Petroleum ether (10 mL) was then added, and the
pale yellow solid obtained isolated by filtration and dried under
3
3
°C) δ 0.05 (s, 18H, SiMe3), 0.18 (dd, J HP ) 11.0, J HP ) 9.0
Hz, 1H, CH(SiMe3)2), 1.02 (d, 2J HP ) 10.0 Hz, 9H, PMe3), 1.06
(d, J HP ) 8.9 Hz, 9H, PMe3); 13C{1H} NMR (C6D6, 25 °C) δ
2
6.1 (SiMe3), 11.8 (d, 2J CP ) 77 Hz, 1J CPt ) 477 Hz, CH(SiMe3)2),
1
1
2
14.8 (d, J CP ) 30 Hz, PMe3), 17.3 (dd, J CP ) 42 Hz, J CP ) 3
vacuum. Yield: 0.14 g (50%). IR (Nujol): ν(CN) 2200 cm-1
.

Formation of Pd- and Pt-Substituted Fulvenes
Organometallics, Vol. 17, No. 26, 1998 5629
Ta ble 2. Cr ysta l a n d Refin em en t Da ta for 5a
Anal. Calcd for C52H58F24N2BSi2PPt: C, 42.77; H, 3.97; N,
1.91. Found: C, 42.05; H, 3.92; N, 1.84.
empirical formula
fw
PdC29H53PN2Si2‚1/2C4H10O2
632.32
P r ep a r a tion of P t[C(NHBu -t)dC(C4H4)][CH(SiMe3)2]-
(CNBu -t)(P Me3) (14). To a cold (-30 °C) suspension of
complex 13 (0.08 g, 0.128 mmol) in Et2O (20 mL) was added a
solution of NaCp in THF (3.2 mL, 0.04 M, 0.13 mmol) via
syringe. The cooling bath was removed, and as it was warmed,
the reaction mixture developed a yellow coloration. After 30
min at room temperature, the solvent was removed in vacuo,
leaving a brown residue. 1H and 31P{1H} NMR spectroscopy
showed that the residue was comprised of a mixture of 14a
and 14b, in an approximate 2:1 molar ratio, and, of a third
unidentified species. After extraction into a 2:1 mixture of
light petroleum/Et2O (15 mL) the solution was filtered. The
resulting yellow solution was reduced in volume and cooled
to -30 °C to afford the major isomer 14a as brown-yellow
crystals (0.035 g, 40%). Anal. Calcd for C25H53N2Si2PPt: C,
45.36; H, 7.77; N, 4.23. Found: C, 45.45; H, 7.80; N, 3.90. IR
(Nujol): ν(NH) 3350, ν(CN) 2160 and 1520 cm-1. Data for the
major species 14a : 1H NMR (CD3COCD3, -50 °C) δ -0.18 (s,
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
U (Å3)
triclinic
P1
16.254(5)
11.101(2)
11.081(2)
90.60(2)
70.52(2)
83.78(2)
1872(2)
2
674
1.122
Z
F(000)
Dc (g cm-3
)
temp (K)
290
cryst dimens (mm)
diffractometer
radiation
0.28 × 0.15 × 0.36
AFC6S-Rigaku
graphite-monochromated
Mo KR ( λ ) 0.710 69 Å)
6.12
µ(Mo KR) (cm-1
scan technique
scan rate
scan width
θmax
no. of reflcns measd
)
ω/2θ
8.0°/min (in ω) (3 scans)
(1.05 + 0.30 tan)°
45.1°
2
9H, SiMe3), 0.08 (s, 9H, SiMe3), 1.35 (d, J HP ) 10.0 Hz, 9H,
PMe3), 1.48 (s, 9H, CNCMe3), 1.58 (s, 9H, NHCMe3), 5.70 (m,
1H, CHfulv), 5.74 (m, 1H, CHfulv), 6.14 (m, 1H, CHfulv), 6.60 (m,
1H, CHfulv), 7.60 (br s, 3J HPt ) 105 Hz, 1H, NH); 13C{1H} NMR
total: 5104
unique: 4898 (Rint ) 0.080)
6.0 mm horizontal
6.0 mm vertical
2654
detector aperture
2
(CD3COCD3, -50 °C) δ -3.0 (d, J CP ) 69 Hz, CH(SiMe3)2),
no. of obsd data (I g 3(I))
structure solution
refinement
function minimized
least-squares weights
p-factor
anomalous dispersion
reflcn/param ratio
RF (%)
1
5.6 (SiMe3), 6.5 (SiMe3),13.9 (d, J CP ) 33 Hz, PMe3), 29.9
Patterson method
full-matrix least-squares
(CNCMe3), 31.4 (NHCMe3), 54.3 (CNCMe3), 59.1 (NHCMe3),
105.1, 113.9, 115.6, 124.8 (CHfulv), 128.4 (CdCC4H4), 193.8 (d,
2J CP ) 11 Hz, CdCC4H4); 31P{1H} NMR (CD3COCD3, -50 °C):
w(|Fo| - |Fc|)2
4Fo2/2(Fo
)
2
0.03
1
δ -24.2 (s, J PPt ) 1970 Hz).
all non-hydrogen atoms
8.83
5.1
5.5
1.24
0.03
0.93-1.00
X-r a y Str u ctu r e Deter m in a tion of Com p lex 5a . The
crystal selected for the X-ray study contained half a molecule
of 1,2-dimethoxyethane of crystallization per asymmetric unit.
Crystallographic data can be found in Table 2. A yellow plate
having approximate dimensions of 0.28 × 0.15 × 0.30 mm was
mounted on a glass fiber and transferred to an AFC6S-Rigaku
single-crystal diffractometer. The cell parameters were ob-
tained from the settings of 25 reflections ranged 11.61 < θ <
17.73°. The data were collected in the interval 5 < θ < 45°,
using the ω-2θ scan method at a speed of 8°/min. The
standard reflections were intensity controlled for decay cor-
rection (the final decay was 16%). Absorption (ψ scan method
and transmission factors ranged 0.93-1.00), Lorentz, and
polarization corrections were also applied. The structure was
solved by the Patterson method and phase expansion and
refinement of the remainder of the structure. All non-
hydrogen atoms in the complex molecule were anisotropically
refined, the carbon and oxygen atoms in the solvate were
isotropically refined by full-matrix least-squares methods.
Approximately half of the hydrogen atoms were localized in
difference Fourier maps and the rest have been placed at the
calculated positions. Refinements concluded with R ) 0.051,
Rw ) 0.055, and goodness of fit 1.24. Scattering factors were
Rw (%)
goodness of fit indicator
max shift/error
abs cor range
taken from those included in the TEXSAN system,32 running
on a DEC VAX 3520 at the Servicios Centralizados de Ciencia
y Tecnolog´ıa, Universidad de Ca´diz.
Ack n ow led gm en t. The Direccio´n General de In-
vestigacio´n Cient´ıfica y Te´cnica (Proyecto PB94-1445)
and the J unta de Andaluc´ıa are thanked for financial
support. Thanks are also due to the Ministerio de
Educacio´n y Ciencia (F.M.A. and T.R.B.) for research
fellowships.
Su ppor tin g In for m ation Available: Tables giving atomic
coordinates, thermal parameters and bond distances, and
angles (15 pages). Ordering information is given in any current
masthead page.
OM9806500
(32) TEXSAN-TEXRAY Structure Analysis Package; Molecular
Structure Corporation: The Woodlands, TX, 1985.