Interionic solution structure of [PtMe(η2-olefin)(N,N-diimine)]BF4 complexes by 19F{1H}-HOESY NMR spectroscopy: Effect of the substituents on the accessibility of the counterion to the metal

Article abstract of DOI:10.1021/om990401r

The relative cation - anion position in [Pt(Me)(η²-olefin)(N,N)]BF₄ complexes (where N,N = 2,6-(R')₂C₆H₃N=C(R)C(R)=N-2,6-(R') ₂C₆H₃, R' = H, Me, Et, and i-Pr, R= H, Me

Full text of DOI:10.1021/om990401r

Organometallics 1999, 18, 4367-4372
4367
In ter ion ic Solu tion Str u ctu r e of
[P tMe(η2-olefin )(N,N-d iim in e)]BF 4 Com p lexes by
19F {1H}-HOESY NMR Sp ectr oscop y: Effect of th e
Su bstitu en ts on th e Accessibility of th e Cou n ter ion to
th e Meta l
Cristiano Zuccaccia and Alceo Macchioni*
Dipartimento di Chimica, Universita` di Perugia, Via Elce di Sotto, 8-06123 Perugia, Italy
Ida Orabona and Francesco Ruffo
Dipartimento di Chimica, Universita` di Napoli “Federico II”, Via Mezzocannone,
4-80134 Napoli, Italy
Received May 26, 1999
The relative cation-anion position in [Pt(Me)(η2-olefin)(N,N)]BF4 complexes (where N,N
) 2,6-(R′)2C6H3NdC(R′′)C(R′′)dN-2,6-(R′)2C6H3, R′ ) H, Me, Et, and i-Pr, R′′ ) H, Me; olefin
) CH2dCHR, R ) H, Me, COOMe) in methylene chloride has been investigated by detecting
specific interionic dipolar interactions in the 19F{1H}-HOESY NMR spectra. The counterion
shows strong interionic contacts with R′′ and R′ protons and weak contacts with R and olefinic
protons only when R′ < Et and R′′ ) Me. For R′ g Et the accessibilty to the metal center is
completely inhibited and the counterion is located above or below the backside of the diimine
ligand. The same position is also observed when R′′ ) H and R′ ) R ) Me despite the limited
steric hindrance of the substituents due to specific interactions between H′′ and the fluorine
of BF4-. In the other cases (R′ < Et), the counterion also interacts with Me, R, and olefinic
protons, indicating that the accessibility to the metal center is not forbidden.
In tr od u ction
the organometallic fragment can be achieved in solution
by detecting anion-cation dipolar interactions in the
1H-NOESY and 19F{1H}-HOESY NMR spectra. These
ion-counterion interactions may be used to probe the
accessibility of a nucleophile to the metal and, conse-
quently, to directly investigate the role of the substit-
uents in blocking the axial sites of the metal center.
In this paper we report the results of our 19F{1H}-
HOESY NMR investigation in methylene chloride on
[Pt(Me)(η2-olefin)(N,N)]BF4 complexes reported in Chart
1. The principal aim of this study is to determine how
steric hindrance above and below the square-planar
coordination plane introduced by the substituents of the
N,N-diimine ligands affects the relative BF4--cation
position in solution.
The reactivity of [M(R)(η2-olefin)(N,N)]X (M ) Ni, Pd,
and Pt) complexes is known to be strongly dependent
on the choice of N,N-chelating ligands. In particular, a
crucial role is attributed to the capability of the N,N-
ligand to introduce steric hindrance above and below
the square-planar coordination plane. When a substan-
tial hindrance is introduced, the complexes are (1)
catalysts for the homogeneous polymerization of R-olefin
affording high molecular weight polymers (M ) Ni and
Pd)1 and (2) kinetically stable compounds (M ) Pt),2
even with electron-poor alkenes.3 This is attributed to
inhibition of associative termination processes in (1) and
prevents the attack of a generic nucleophile in (2).
Due to the importance of metal alkyl diimine olefin
π-complexes, which have been established1a,c to be the
catalytic resting state of olefin polymerization catalyzed
by M-diimine catalysts (M ) Ni and Pd), we decided
to investigate their interionic structure in solution when
M ) Pt. In previous studies, we have shown4 that the
dominant placement of the counterion with respect to
Resu lts a n d Discu ssion
In tr a m olecu la r Ch a r a cter iza tion . Complexes 1-8
were characterized in methylene chloride solution by 1H,
13C, and 19F NMR spectroscopies.
To precisely localize the relative cation-anion posi-
tion, accurate preliminary work must be done to assign
* To whom correspondence should be submitted.
(1) (a) J ohnson, L. K.; Killian, C. M.; Brookhart, M. J . Am. Chem.
Soc. 1995, 117, 6414. (b) J ohnson, L. K.; Mecking, S.; Brookhart, M.
J . Am. Chem. Soc. 1996, 118, 267. (c) Mecking, S.; J ohnson, L. K.;
Wang, L.; Brookhart, M. J . Am. Chem. Soc. 1998, 120, 888.
(2) (a) Fusto, M.; Giordano, F.; Orabona, I.; Ruffo, F. Organometallics
1997, 16, 5981. (b) Yang, K.; Lachicotte, R. J .; Eisenberg, R. Organo-
metallics 1998, 17, 5102.
(4) (a) Bellachioma, G.; Cardaci, G.; Macchioni, A.; Reichenbach, G.;
Terenzi, S.; Organometallics 1996, 15, 4349. (b) Macchioni, A.; Bella-
chioma, G.; Cardaci, G.; Gramlich, V.; Ru¨egger, H.; Terenzi, S.;
Venanzi, L. M. Organometallics 1997, 16, 2139. (c) Macchioni, A.;
Bellachioma, G.; Cardaci, G.; Cruciani, G.; Foresti, E.; Sabatino, P.;
Zuccaccia, C. Organometallics 1998, 17, 5549. (d) Bellachioma, G.;
Cardaci, G.; Gramlich, V.; Macchioni, A.; Valentini, M.; Zuccaccia, C.
Organometallics 1998, 17, 5025. (e) Zuccaccia, C.; Bellachioma, G.;
Cardaci, G.; Macchioni, A. Organometallics 1999, 18, 1.
(3) Ganis, P.; Orabona, I.; Ruffo, F.; Vitagliano, A. Organometallics
1998, 17, 2646.
10.1021/om990401r CCC: $18.00 © 1999 American Chemical Society
Publication on Web 09/14/1999

4368 Organometallics, Vol. 18, No. 21, 1999
Zuccaccia et al.
Ch a r t 1
(see Figure 1c). The components of the two pairs were
able to be distinguished by the observation of a weak
contact between the Me of R and Me′(Mdf) only (see
Figure 1b). The CH′ protons were assigned by observing
both the NOE contacts and the COSY peaks with “their”
Me′ groups (see Figure 2). Finally, the Hm and Hp
afforded a typical set of A2B spin system resonances.
1
From the assigned H resonances all the 13C resonances
1
were assigned by the H{13C}-COSY NMR “standard”
and long range with gradients spectra.5
The assignment of the resonances for the other
complexes was carried out in the same way. The spatial
differentiation was inevitably smaller because (1) when
R ) H (complex 6), it is impossible to distinguish above
from below the coordination plane; (2) when R′ ) H and
Me (complexes 1 and 2), the olefin rotation is fast
compared to the chemical shift NMR time scale, and
again, it is impossible to distinguish between above from
below the coordination plane; (3) when R′ ) Me (complex
2 and 5), the rotation around the R′-Cï bond is no
longer restricted and the three protons are equivalent;
and (4) in the case of electron-poor olefins (complexes 7
and 8) the two N,N halves (left/right) are in exchange.6
A 1H-NOESY NMR spectrum was recorded at 217 K for
complex 8 in order to slow the exchange process and,
consequently, to differentiate the two halves and the
positions above or below the coordination plane. The
latter differentiation occurs only on the side cis to the
olefin, where specific contacts were observed between
H olefin and Me′ protons (see Figure 3). Due to the
absence of contact between the COOMe and Me′ pro-
tons, it was impossible to distinguish between Me′(Muf)
and Me′(Mdf). It is interesting to note that in the
exchange process the acrylate primarily orients the CO2-
Me group toward Me, as indicated, for example, by the
absence of NOE between the HC(COOMe)dCH2trans and
any CH′ in Figure 3. Another interesting point is the
specificity of the exchange peaks between Me′(Odf) and
only one of the Me′(Mf) groups, which, on the basis of
the chemical shift trend observed for complex 4, should
be Me′(Mdf).
In ter ion ic Solu tion Str u ctu r e. The interionic struc-
ture of complexes 1-8 was investigated in methylene
chloride, at room temperature (302 K), by recording the
19F{1H}-HOESY NMR spectra. Methylene chloride has
a low dielectric constant (8.71 at 303 K), ensuring that
the complexes are substantially intimate ion-pairs.7 This
is a fundamental requirement for detecting the NOE
contacts between dipolar coupled nuclei which must be
closer than 4.5-5.0 Å.8
All the complexes 1-8 show very strong interionic
contacts between the fluorine atoms of the counterion
and the protons of the R′′ groups. There are also strong
interionic contacts with the protons of some R′ groups.
For complexes 4 and 8, where all the Me′ groups are
magnetically inequivalent, it can be noted that only the
backside Me′ pointing toward the R′′ groups (indicated
with b in Scheme 1) strongly interacts with the coun-
as many resonances as possible in both fragments. In
the case of complexes 1-8, the anion is symmetric and
only two resonances were observed in the 19F NMR
spectra due to 10BF4 and 11BF4-. On the other hand,
-
the cationic fragment consists of several proton reso-
nances, inhomogeneously distributed around platinum.
Not only do all four coordination positions contain
magnetically inequivalent protons but the region above
and below the square-coordination plane can also be
differentiated when R * H. Furthermore, in the case of
complex 4 (R′ ) isopropyl), there is a differentiation of
the methyl groups of R′ that point forward or backward
with respect to the plane containing the two phenyl
groups. This is due to restricted rotation around both
the N-Cipso and R′-Co bonds.
The assignment of all the proton resonances of
complex 4, based primarly on phase-sensitive 1H-
NOESY NMR spectra, is discussed in detail because of
the above-mentioned peculiarities. The resonances of
Me, R, and olefinic protons were easily assigned and
were used as starting points. Ten more resonances were
present in the chemical shift region 2.46-1.18 ppm,
each of them integrating for three protons. Eight of
these resonances (1.45-1.18 ppm) appeared as doublets
and must be due to the methyl groups of R′ (Me′) that
are all chemically inequivalent. Only one Me′ gave an
NOE contact with Me of R and with the olefin proton
geminal to it (see Figure 1, parts a and b). This Me′ has
to stay cis to the olefin (O), in front of the Me of R (down,
indicated with d), and oriented forward (f) with respect
to the plane containing the two phenyl groups. We will
label such a methyl group as Me′(Odf) (see Scheme 1).
Another Me′ gave a contact only with the CH2d protons,
and we can call it Me′(Ouf) (where u stands for up with
respect to the olefinic R group; see Figure 1a). Me′(Odf)
and Me′(Ouf) interact strongly with Me′(Odb) and Me′-
(Oub), respectively (where b stands for backward),
which were easily assigned. The latter gave specific
NOE contacts only with Me′′(O). The other singlet must
be due to Me′′(M) (where M stands for cis to the methyl
group). It was possible to distinguish between Me′(Muf),
Me′(Mdf) and Me′(Mub), Me′(Mdb) by the NOE contacts
between the Me group and the remaining Me′ groups
(5) For the economy of this article, the data are reported in the
Experimental Section but will not be discussed.
(6) The process of slow exchange was individuated by the detection
of exchange peaks (having the same signal as the diagonal peaks) in
the phase-sensitive 1H-NOESY NMR spectra between all the signals
relative to the two halves.
(7) Romeo, R.; Arena, G.; Monsu` Scolaro, L.; Plutino, M. R. Inorg.
Chim. Acta 1995, 240, 81.

Structure of [PtMe(η2-olefin)(N,N-diimine)]BF4
Organometallics, Vol. 18, No. 21, 1999 4369
1
F igu r e 1. Three sections of the H-NOESY NMR spectrum of complexes 4 recorded at 400.13 MHz in CD2Cl2 at 302 K
showing the specific contacts of (a) Me′(Ouf) with CH2d protons, (b) Me′(Odf) with Me of R group, and (c) Me with Me′-
(Muf) and Me′(Mdf). * indicates the O(CH2CH3)2 resonances relative to an impurity of diethyl ether. ** denotes the resonance
due to an impurity of H2O.
Sch em e 1
terion (see Figure 4).9 As the steric hindrance above and
below the coordination plane introduced by the N,N-
diimine ligands decreases, weak interionic contacts with
the Me, R, and olefinic protons start to appear. The
ratios between the percentage of NOEs of the interionic
contacts due to R′′ and Pt-Me groups for complexes 1-3
are the following: R′′/Me 14 (1), 41 (2), and 116 (3). The
interionic contacts with the Me, R, and olefinic protons
are not observed in the case of complex 4. The substitu-
tion of the Me′′ with H′′ groups (complex 5) affords
higher specificity of interionic contacts between H′′ and
the counterion. The ratio between the percentage of
NOEs H′′/Me is equal to 115. In the case of complex 6,
the above indicated ratio is closer to that of complex 2
(it amounts to 51) due to decreased steric hindrance in
F igu r e 2. Section of the 1H-COSY NMR spectrum of
complexes 4 recorded at 400.13 MHz in CD2Cl2 at 302 K
showing the assignment of the CH′ protons by the “cosy”
peaks with their Me′ protons.
the olefinic ligand even though R′ ) Et as in complex
3. Complexes 7 and 8 behave like 3 and 4, respectively.
The results illustrated above indicate that the coun-
terion BF4- pairs with the organometallic fragment from
the side of the N,N-ligand, preferentially interacting
with the R′′ and R′ substituents. Its exact position is
tuned by the steric hindrance of the R, R′, and R′′
(8) Neuhaus, D.; Williamson, M. The Nuclear Overhauser Effect in
Structural and Conformational Analysis; VCH Publishers: New York,
1989.
(9) In complexes 3 and 7, the rotation around the R′-Co is also
restricted. Owing to the complexity and partial overlap of the
CH1H2Me resonances, it is difficult to understand if specific interac-
tions are present.

4370 Organometallics, Vol. 18, No. 21, 1999
Zuccaccia et al.
the metal. This is reasonable because both protect the
metal more or less perpendicularly to the square-planar
coordination plane. Complex 5 behaves similarly to
complex 3 despite the substantial reduction of steric
hindrance in the R′ substituent. In the latter case, the
electronic contribution plays an important role: H′′
contributes to localizing the counterion on that side via
(a) weak H‚‚‚F interaction(s). A similar case was re-
ported10 for the complex [PtMe(Me2SO)N,N]X (where
-
N,N ) bis(2-pyridyl)amine and X- ) Cl-, CF3SO3
,
BF4-, and PF6-), which gives very specific interactions.
In that case, the amino group separating the two pyridyl
rings has a strong tendency to attract the counterion,
forming a hydrogen bond.
The reason the counterion prefers the “N,N” side
instead of the less hindered olefin and methyl one has
to be related to the positive charge distribution. In
particular, there must be a delocalization of the positive
charge on the N,N-ligands, as observed in previously
studied octahedral complexes.4 It was also found that
in square planar complexes [Pd(η1,η2-C8H12OMe)N,N]X
1
F igu r e 3. Two sections of the H-NOESY NMR spectrum
(where N,N ) 2,2′-bipyridine and X- ) BPh4-, CF3SO3
,
-
of complexes 8 recorded at 400.13 MHz in CD2Cl2 at 217
K showing the interactions of (i) Me with CH′(Md) and CH′-
(Mu), (ii) HC(COOMe)dCH2cis with CH′(Ou), and (iii) HC-
(COOMe)dCH2 with CH′(Od).
BF4-, PF6-, SbF6-, and B[3,5-(CF3)2C6H3]4-),11 the
counterion is located above or below the coordination
plane and shifted toward the N,N-ligand but it still
substantially interacts with protons that do not belong
to it.
The results reported here are in general agreement
with those coming from both experimental1,12 and
theoretical investigations carried out on nickel,13 palla-
dium,13b,c and platinum13c diimine catalysts for ethylene
polymerization. By increasing the bulk of the substit-
uents (in both R and R′), we observe a decreased
accessibility of the counterion to the metal center and
-
an increased specificity of the interionic contacts of BF4
with the R′′ and R′(b) protons. This is a direct proof that
associative processes on axial sites of the metal center
are unlikely to occur, at least for R′ > Et. The only
discrepancy comes from the analysis of the spectra of
complex 5. It is known1 that replacing Me′′ with H′′
decreases the productivity of the Ni and Pd diimine
catalysts. This could to be due to an increased steric
interaction between the aryl rings and the auxiliary
methyl fragments bound to the diimine ligand.13a On
the basis of the above discussion, we should observe
smaller NOE ratios (H′′/Me), but instead we observe the
exact opposite because H′′ are suitable to form hydrogen
-
bond(s) with BF4
.
Con clu sion s
The results from the present 19F{1H}-HOESY NMR
investigation of the interionic solution structure of Pt
complexes 1-8, analogous to Ni and Pd catalysts for
ethylene polymerization, have shed light on the acces-
sibility of a nucleophile to the metal center. By increas-
F igu r e 4. Section of the 19F{1H}-HOESY spectrum of
complexes 4 recorded at 376 MHz in CD2Cl2 at 302 K
showing the specific interionic contacts of BF4 with Me′
-
groups pointing toward R′′.
substituents. With the exception of complex 5, as the
steric hindrance of the substituents decreases, the
counterion populates positions closer to the platinum
even if it is still substantially shifted toward the N,N-
ligands. In complex 1, the interionic interactions are also
much stronger with R′′ than with Me. Interestingly, in
the complexes investigated here, it appears that the
addition of a methyl group in R and R′ substituents has
the same effect on the accessibility of the counterion to
(10) Romeo, R.; Nastasi, N.; Monsu` Scolaro, L.; Plutino, M. R.;
Albinati, A.; Macchioni, A. Inorg. Chem. 1998, 37, 5460.
(11) Macchioni, A.; Bellachioma, G.; Cardaci, G.; Zuccaccia, C.;
Milani, B.; Corso, G.; Zangrando, E.; Mestroni, G.; Carfagna, C.;
Formica, M. Organometallics 1999, 18, 3061.
(12) Svejda, S. A.; Brookhart, M. Organometallics 1999, 18, 65-74.
(13) (a) Deng, L.; Woo, T. K.; Cavallo, L.; Margl, P. M.; Ziegler, T.
J . Am. Chem. Soc. 1997, 119, 6177. (b) Froese, R. D. J .; Musaev,
D. G.; Morokuma, K. J . Am. Chem. Soc. 1998, 120, 1581. (c)
Musaev, D. G.; Froese, R. D.; Morokuma, K. New J . Chem. 1997, 21,
1269.

Structure of [PtMe(η2-olefin)(N,N-diimine)]BF4
Organometallics, Vol. 18, No. 21, 1999 4371
20.6 (s, HC(Me)dCH2), 13.54 (s, Me′(Od)), 13.52 (s, Me′(Ou)),
13.41 (s, Me′(Mu) or Me′(Md)), 13.37 (s, Me′(Md) or Me′(Mu)),
-3.0 (s, 1J PtC ) 700, Me). 19F{1H} NMR: δ -152.3 (b, 10BF4-),
ing the bulk of the substituents on the aryl moieties,
the accessibility to the metal center is reduced. When
such substituents are larger than or equal to Et, the
1
-152.4 (q, J BF ) 1.0, 11BF4-).
-
counterion BF4 does not interact at all with Me and
Ch a r a cter iza tion of Com p lex 4. 1H NMR (CD2Cl2, 302
K): δ 7.45 (m, aromatics), 4.40 (m, HC(Me)dCH2), 3.85 (m,
HC(Me)dCH2), 3.12 (sept, 3J HH ) 6.8, CH′(Md), 2.94 (sept, 3J HH
the olefinic protons, indicating that the axial sites of
the metal center exhibit little binding to the BF4-. Our
assumption to consider the counterion as a probe for
investigating the associative process of a generic nu-
cleophile to the metal was correct for all the complexes,
except complex 5, where H′′ diimine backbone substit-
uents afford weak H‚‚‚F interactions.
3
) 6.8, CH′(Ou)), 2.87 (sept, J HH ) 6.8, CH′(Od)), 2.85 (sept,
3J HH ) 6.8, CH′(Mu)), 2.46 (s, Me′′(M)), 2.25 (s, Me′′(O)), 1.67
3
3
3
(m, J HH ) 6.2, J HPt ) 53, HC(Me)dCH2), 1.45 (d, J HH ) 6.8,
3
3
Me′(Odf)), 1.44 (d, J HH ) 6.8, Me′(Ouf)), 1.36 (d, J HH ) 6.8,
3
3
Me′(Mdf)), 1.35 (d, J HH ) 6.8, Me′(Muf)), 1.30 (d, J HH ) 6.8,
Me′(Mdb)), 1.27 (d, 3J HH ) 6.8, Me′(Mub)), 1.27 (d, 3J HH ) 6.8,
3
2
Me′(Odb)), 1.18 (d, J HH ) 6.8, Me′(Oub)), 0.34 (s, J HPt ) 71,
Me). 13C{1H} NMR: δ 186.0 (s, C(O)), 178.5 (s, C(M)), 140.1
(s, Co(Md)), 139.9 (s, Cipso(M)), 139.4 (s, Co(Od)), 139.2 (s, Co-
(Ou)), 139.2 (s, Co(Mu)), 137.6 (s, Cipso(O)), 99.7 (s, HC(Me)d
CH2), 71.7 (s, HC(Me)dCH2), 29.2 (s, CH′(Mu)), 29.1 (s,
CH′(Md)), 29.0 (s, CH′(Ou)), 28.8 (s, CH′(Od)), 25.2 (s, Me′(Oub)),
24.8 (s, Me′(Odb)), 24.2 (s, Me′(Mdb)), 24.1 (s, Me′(Mub)), 23.6
(s, Me′(Muf)), 23.5 (s, Me′(Ouf) and Me′(Odf)), 23.0 (s, Me′-
(Mdf)), 22.6 (s, Me′′(O)), 22.2 (s, Me′′(M)), 20.6 (s, HC(Me)d
CH2), -2.5 (s, Me). 19F{1H} NMR: δ -152.5 (b, 10BF4-), -152.6
Exp er im en ta l Section
One- and two-dimensional 1H, 13C, and 19F NMR spectra
were measured on Bruker DPX 200 and DRX 400 spectrom-
eters. Referencing is relative to TMS (1H and 13C) and CCl3F
(19F). NMR samples were prepared dissolving about 20 mg of
1
compound in 0.5 mL of CD2Cl2. Two-dimensional H-NOESY
and 19F{1H}-HOESY spectra were recorded with a mixing time
of 500-800 ms.
Complexes 1-4, 6,2a 7 and 8,3 and [PtClMe(SMe)2]14 were
(q, J BF ) 1.0, 11BF4-).
1
synthesized as reported in the literature.
Ch a r a cter iza tion of Com p lex 1. 1H NMR (CD2Cl2, 302
K): δ 7.58, 7.43, 7.14 (aromatics) 4.66 (m, HC(Me)dCH2), 3.89
Syn th esis of [P t(Cl)Me{2,6-Me2C6H3NdCHCHdN-2,6-
Me2C6H3}]. The N,N-ligand (1.2 mmol) was added to a
suspension of [PtClMe(SMe)2] (1.0 mmol) in 10 mL of diethyl
ether. After 48 h of stirring the orange product was collected,
washed with diethyl ether, and dried under vacuum (yield:
80%). 1H NMR (CDCl3, 298 K): δ 9.37 (s, 3J HPt ) 106, H′′(M)),
8.71 (s, 3J HPt ) 36, H′′(Cl)), 7.24 (m, aromatics), 2.32 and 2.27
3
3
3
(m, J HH ) 7.8, J PtH ) 63.9 HC(Me)dCHcis), 3.67 (m, J HH
)
3
14.1, J PtH ) 63.9 HC(Me)dCHtrans), 2.36 (s, Me′′(M)), 2.11 (s,
Me′′(O)), 1.61 (m, 3J HH ) 6.2, 4J HPt ) 63.2, HC(Me)dCH2), 0.32
(m, J HPt ) 71.9, Me). 13C{1H} NMR: δ 185.7 (s, C(O)), 178.0
2
(s, C(M)), 144.7 (s, Cipso(M)), 143.8 (s, Cipso(O)), 130.2, 130.0,
128.4, 122.5, 121.6 (aromatics), 97.7(s, HC(Me)dCH2), 69.7 (s,
HC(Me)dCH2), 20.5 (s, HC(Me)dCH2), -3.1 (s, Me). 19F{1H}
2
(s, all Me′), 1.39 (s, J HPt ) 80, Me).
Syn th esis of Com p lex 5. A solution of [Pt(Cl)Me{2,6-
Me2C6H3NdCHCHdN-2,6-Me2C6H3}] (1.0 mmol) in 5 mL of
dichloromethane was added to a suspension of AgBF4 (1.0
mmol) in 10 mL of dichloromethane under a propene atmo-
sphere. After 48 h of stirring at room temperature, AgCl was
removed by filtration through Celite and the volume of the
resulting solution was reduced to 5 mL under vacuum. Slow
addition of diethyl ether afforded yellow-orange microcrystals
of product, which was collected, washed with diethyl ether,
and dried under vacuum (yield: 75%).
1
NMR: δ -151.7 (b, 10BF4-), -151.8 (q, J BF ) 1.0, 11BF4-).
Ch a r a cter iza tion of Com p lex 2. 1H NMR (CD2Cl2, 302
K): δ 7.30 (aromatics) 4.43 (m, 3J PtH ) 72 HC(Me)dCH2), 3.78
3
2
4
3
(m, J HH ) 8.7, J HH ) 1.1, J HH ) 0.7, J PtH ) 64, HC(Me)d
3
2
4
3
CH2cis), 3.77 (m, J HH ) 15.1, J HH ) 1.1, J HH ) 0.7, J PtH
)
64, HC(Me)dCH2trans), 2.37 (s, Me′′(M)), 2.32 (s, Me′(Md or
Mu)), 2.30 (s, Me′(Od or Ou)), 2.27 (s, Me′(Mu or Md)), 2.23 (s,
3
4
Me′(Ou or Od)), 2.13 (s, Me′′(O)), 1.67 (m, J HH ) 6.2, J HH
)
3
2
0.7, J HPt ) 60, HC(Me)dCH2), 0.21 (m, J HPt ) 72, Me). 13C-
Ch a r a cter iza tion of Com p lex 5. 1H NMR (CD2Cl2, 302
{1H} NMR: δ 186.3 (s, C(O)), 178.5 (s, C(M)), 141.8 (s, Cipso
-
3
3
K): δ 9.09 (s, J PtH ) 99, H′′(M)), 9.04 (s, J PtH ) 41, H′′(O)),
(M)), 140.8 (s, Cipso(O)), 129.9 (s, Co(Md) or Co(Mu)), 129.8 (s,
Co(Mu) or Co(Md)), 128.9 (s, Co(Od) or Co(Ou)), 128.6 (s, Co-
(Ou) or Co(Od)), 129.6, 129.3, 129.1, 129.0, 128.5 (other
3
7.28 (aromatics), 4.76 (m, J PtH ) 69 HC(Me)dCH2), 4.07 (m,
3J HH ) 7.8, 2J HH ) 1.1, 4J HH ) 0.7, 3J PtH ) 67, HC(Me)dCH2cis),
3
2
4
3
3.89 (m, J HH ) 14.3, J HH ) 1.1, J HH ) 0.7, J PtH ) 65, HC-
(Me)dCH2trans), 2.37 (s, Me′(Od)), 2.35 (s, Me′(Mu or Md)), 2.33
(s, Me′(Md or Mu)), 2.27 (s, Me′(Ou)), 1.70 (m, 3J HH ) 6.2, 4J HH
2
2
aromatics), 99.8 (s, J PtC ) 177, HC(Me)dCH2), 71.8 (s, J PtC
) 171, HC(Me)dCH2), 20.7 (s, HC(Me)dCH2), 20.6 (s, Me′′-
(M)), 20.2 (s, Me′′(O)), 17.88 (s, Me′(Md) or Me′(Mu)), 17.87 (s,
Me′(Mu) or Me′(Md)), 17.7 (s, Me′(Od) or Me′(Ou)), 17.6 (s, Me′-
) 0.7, J HPt ) 62, HC(Me)dCH2), 0.48 (s, J HPt ) 72, Me). 13C-
3
2
{1H} NMR: δ 176.4 (s, C(M)), 170.0 (s, C(O)), 143.7 (s, Cipso
-
1
(Ou) or Me′(Od)), -3.61 (s, J PtC ) 693, Me). 19F{1H} NMR: δ
(M)), 143.5 (s, Cipso(O)), 130.5 (s, Co(Md) or Co(Mu)), 130.2 (s,
1
-151.82 (b, 10BF4-), -152.88 (q, J BF ) 1.0, 11BF4-).
Co(Mu) or Co(Md)), 129.2 (s, Co(Od)), 128.9 (s, Co(Ou)), 129.5,
Ch a r a cter iza tion of Com p lex 3. 1H NMR (CD2Cl2, 302
K): δ 7.39 (m, aromatics), 4.35 (m, 3J PtH ) 72, HC(Me)dCH2),
3.76 (m, 3J HH ) 14.3, 2J HH ) 1.1, 4J HH ) 0.7, HC(Me)dCH2trans),
2
129.2, 129.0, 128.9, 128.8 (other aromatics), 101.8 (s, J PtC
172, HC(Me)dCH2), 72.9 (s, J PtC ) 171, HC(Me)dCH2), 21.1
(s, HC(Me)dCH2), 18.1 (s, Me′(Md) and Me′(Mu)), 18.0 (s,
)
2
3
2
4
3
1
3.74 (m, J HH ) 8.0, J HH ) 1.1, J HH ) 0.7, J PtH ) 64, HC-
(Me)dCH2cis), 2.62 (m, CH2′(AB system)), 2.38 (s, Me′′(M)), 2.15
Me′(Od)), 17.8 (s, Me′(Ou)), -3.7 (s, J PtC ) 683, Me).
19F{1H} NMR: δ -151.75 (b, 10BF4-), -152.80 (q, J BF ) 1.4,
1
3
4
3
11BF4-).
(s, Me′′(O)), 1.63 (m, J HH ) 6.2, J HH ) 0.7, J HPt ) 59, HC-
3
3
Ch a r a cter iza tion of Com p lex 6. 1H NMR (CD2Cl2, 302
(Me)dCH2), 1.38 (t, J HH ) 7.5, Me′(Od)), 1.36 (t, J HH ) 7.5,
Me′(Mu) or Me′(Md)), 1.34 (t, 3J HH ) 7.5, Me′(Md) or Me′(Mu)),
3
K): δ 7.39 (m, aromatics), 3.74 (m, J HPt ) 67.5, H2CdCH2),
1.32 (d, J HH ) 7.5, Me′(Ou)), 0.23 (s, J HPt ) 71.6, Me). 13C-
3
2
3
4
2.66 (qd, J HH ) 7.6, J HH ) 2.3, CH2′(M)), 2.57 (m, CH2′(O)),
{1H} NMR: δ 185.9 (s, C(O)), 178.3 (s, C(M)), 140.7 (s, Cipso
-
2.42 (s, Me′′(M)), 2.16 (s, Me′′(O)), 1.35 (t, 3J HH ) 7.5, Me′(O)),
(M)), 139.5 (s, Cipso(O)), 135.0 (s, Co(Md) or Co(Mu)), 134.9 (s,
1.34 (t, J HH ) 7.5, Me′(M)), 0.16 (s, J HPt ) 69, Me). 13C{1H}
NMR: δ 186.8 (s, C(M) or C(O)), 178.2 (s, C(O) or C(M)), 140.7
(s, Cipso(M)), 139.0 (s, Cipso(O)), 134.9 (s, Co(M)), 133.7 (s, Co-
(O)), 129.1 (s, Cp(O) or Cp(M)), 129.0 (s, Cp(M) or Cp(O)), 126.8
(s, Cm(O)), 126.7 (s, Cm(M)), 75.2 (s, H2CdCH2), 24.4 (s, CH2′-
(M)), 23.8 (s, CH2′(O), 21.1 (s, Me′′(M)), 20.8 (s, Me′′(O)), 13.6
(s, Me′(O)), 13.5 (s, Me′(M)), -4.8 (s, Me). 19F{1H} NMR: δ
3
2
Co(Mu) or Co(Md)), 134.0 (s, Co(Od)), 133.8 (s, Co(Ou)), 129.1,
2
128.9, 126.9, 126.8, 126.6 (aromatics), 99.7 (s, J PtC ) 90,
HC(Me)dCH2), 71.9 (s, 2J PtC ) 85, HC(Me)dCH2), 24.3 (s, CH2′-
(Ou) and CH2′(Od)), 23.88 (s, CH2′(Md) or CH2′(Mu)), 23.77
(s, CH2′(Mu) or CH2′(Md)), 20.9 (s, Me′′(M)), 20.9 (s, Me′′(O)),
1
(14) Scott, D.; Puddephatt, R. J . Organometallics 1986, 5, 1643.
-152.2 (b, 10BF4-), -152.2 (q, J BF ) 1.0, 11BF4-).

4372 Organometallics, Vol. 18, No. 21, 1999
Zuccaccia et al.
(Md)), 2.79 (sept, J HH ) 6.6, CH′(Ou)), 2.54 (s, Me′′(M)), 2.29
Ch a r a cter iza tion of Com p lex 7. 1H NMR (CD2Cl2, 302
3
3
3
3
3
K): δ 7.36 (m, aromatics), 4.32 (m, J HH ) 13.5, J PtH ) 59,
HC(COOMe)dCH2trans), 4.04 (m, 3J HH ) 13.5, 3J HH ) 8.3, 3J PtH
) 75, HC(COOMe)dCH2), 3.67 (s, HC(COOMe)dCH2), 3.61 (m,
(s, Me′′(O)), 1.46 (d, J HH ) 6.6, Me′(Odf)), 1.38 (d, J HH ) 6.6,
Me′(Ouf)), 1.26 (m, Me′(Muf), Me′(Mub) or Me′(Mdb), Me′-
(Mdf)), 1.19 (d, 3J HH ) 6.6, Me′(Oub)), 1.18 (d, 3J HH ) 6.6, Me′-
3
3
3J HH ) 8.3, J PtH ) 71, HC(Me)dCH2cis), 2.65 (m, CH2′(AB
(Mdb) or Me′(Mub)), 1.12 (d, J HH ) 6.6, Me′(Odb)), 0.13 (s,
3
system)), 2.51 (s, Me′′(M)), 2.24 (s, Me′′(O)), 1.40 (t, J HH
)
2J HPt ) 58, Me). 19F{1H} NMR (CD2Cl2, 302 K): δ -152.0 (b,
3
1
7.5, Me′(Od)), 1.35 (t, J HH ) 7.5, Me′(Md) or Me′(Mu)), 1.34
10BF4-), -152.1 (q, J BF ) 1.0, 11BF4-).
3
3
(t, J HH ) 7.5, Me′(Mu) or Me′(Md)), 1.33 (t, J HH ) 7.5, Me′-
(Ou)), 0.20 (s, J HPt ) 69.0, Me). 19F{1H} NMR: δ -151.89 (b,
2
Ack n ow led gm en t. The authors wish to thank Prof.
G. Cardaci for very helpful suggestions and discussions.
This work was supported by grants from the Ministero
dell’ Universita` e della Ricerca Scientifica e Tecnologica
(MURST, Rome, Italy), Programma di Rilevante Inter-
esse Nazionale, Cofinanziamento 1998-1999.
10BF4-), -151.95 (q, J BF ) 1.0, 11BF4-).
1
Ch a r a cter iza tion of Com p lex 8. 1H NMR (CD2Cl2, 217
K): δ 7.41 (m, aromatics), 4.28 (d, 3J HH ) 13.6, HC(COOMe)d
CH2trans), 4.14 (dd,3J HH ) 13.6, 3J HH ) 8.0, HC(COOMe)dCH2),
3.70 (d,3J HH ) 8.0, HC(COOMe)dCH2cis), 3.62 (s, HC(COOMe)d
CH2), 3.03 (sept, 3J HH ) 6.6, CH′(Md) or CH′(Mu)), 2.98 (sept,
3
3J HH ) 6.6, CH′(Od)), 2.85 (sept, J HH ) 6.6, CH′(Mu) or CH′-
OM990401R