Synthesis and characterization of trigonal-bipyramidal platinum(II) olefin complexes with chalcogenide ligands in axial positions

Article abstract of DOI:10.1021/om020807v

The oxidative addition of RE-ER molecules (E = O, R = H, C(O)Ph, C(O)Me; E = S, Se, Te, R = Me, Ph) to Pt(0) precursors [Pt(N,N-chelate)(olefin)] (1: N,N-chelate = e.g. 2,9-dimethyl-1,10-phenanthroline; olefin = maleic or fumaric ester) has been studied.

Full text of DOI:10.1021/om020807v

Organometallics 2003, 22, 1223-1230
1223
Syn th esis a n d Ch a r a cter iza tion of Tr igon a l-Bip yr a m id a l
P la tin u m (II) Olefin Com p lexes w ith Ch a lcogen id e
Liga n d s in Axia l P osition s. X-r a y Molecu la r Str u ctu r es of
[P t(SMe)2(d m p h en )(d ip h en yl fu m a r a te)], Its Ca tion ic
Dip ositive Der iva tive [P t(SMe2)2(d m p h en )(d ip h en yl
fu m a r a te)][BF 4]2, a n d F r ee Dip h en yl F u m a r a te
Vincenzo G. Albano,*,† Magda Monari,† Ida Orabona,‡ Achille Panunzi,‡
Giuseppina Roviello,‡ and Francesco Ruffo*,‡
Dipartimento di Chimica “G. Ciamician”, Universita` di Bologna, Via Selmi 2,
40126 Bologna, Italy, and Dipartimento di Chimica, Universita` di Napoli “Federico II”,
Complesso Universitario di Monte S. Angelo, Via Cintia, 80126 Napoli, Italy
Received September 27, 2002
The oxidative addition of RE-ER molecules (E ) O, R ) H, C(O)Ph, C(O)Me; E ) S, Se,
Te, R ) Me, Ph) to Pt(0) precursors [Pt(N,N-chelate)(olefin)] (1: N,N-chelate ) e.g. 2,9-
dimethyl-1,10-phenanthroline; olefin ) maleic or fumaric ester) has been studied. Sym-
metrical cleavage of the E-E bonds affords unprecedented trigonal-bipyramidal Pt(II)
complexes of the formula [Pt(ER)2(N,N-chelate)(olefin)] (2). Products of type 2, which have
1
been characterized through H and 13C NMR spectroscopy, contain chalcogenide ligands in
the axial positions. The reactivity of the new compounds has also been investigated. Thus,
Pt-OH fragments generated by the addition of H2O2 are acetylated by acetic anhydride.
Furthermore, S, Se, and Te coordinated to Pt are readily methylated by trimethyloxonium
tetrafluoroborate, affording the first examples of dipositive coordinatively saturated platinum-
(II) cations (3). The structures of the related neutral [Pt(SMe)2(2,9-dimethyl-1,10-phenan-
throline)(diphenyl fumarate)] and cationic [Pt(SMe2)2(2,9-dimethyl-1,10-phenanthroline)-
(diphenyl fumarate)][BF4]2 compounds have been determined by X-ray diffraction together
with that of the free diphenyl fumarate ligand.
In tr od u ction
through new catalytic processes promoted by Pt or Pd
complexes.4b A crucial step of the proposed catalytic
cycle is the oxidative addition of a dichalcogenide to a
low-valent metal complex with formation of an inter-
mediate of formula [M(ER)2L2(unsaturated compound)].
Further impulse to gain knowledge about compounds
containing Pt-E bonds stems from the recent finding
that octahedral complexes bearing two σ-bonded OR
Complexes containing Pt-E bonds (E ) group 16
element) have been known for a long time.1 Neverthe-
less, several aspects of their chemistry are unexplored
or need further investigation. For example, no coordi-
natively saturated Pt(II) complex with σ-bonded chal-
cogenides has yet been described, since the only known
species are square-planar Pt(II)2 or octahedral Pt(IV)
derivatives.3 Furthermore, the reactivity of the Pt-E
bond has received substantial attention only recently.4
For example, formation of C-E bonds from dichalco-
genides and unsaturated compounds has been attained
(3) (a) Rostovtsev, V. V.; Henling, L. M.; Labinger, J . A.; Bercaw, J .
E. Inorg. Chem. 2002, 41, 3608-3619. (b) Rashidi, M.; Nabavizadeh,
M.; Hakimelahi, R.; J amali, S. J . Chem. Soc., Dalton Trans. 2001,
3430-3434. (c) Song, R.; Kim, K. M.; Lee, S. S.; Sohn, J . S. Inorg. Chem.
2000, 39, 3567-3571. (d) Canty, A. J .; J in, H. J . Organomet. Chem.
1998, 565, 135-140. (e) Canty, A. J .; J in, H.; Skelton, B. W.; White,
A. H. Inorg. Chem. 1998, 37, 3975-3981. (f) Kim, K. M.; Sohn, Y. S.
Inorg. Chem. 1998, 37, 6109-6112. (g) Davies, M. S.; Hambley, T. W.
Inorg. Chem. 1998, 37, 5408-5409. (h) Canty, A. J .; Fritsche, S. D.;
J in, H.; Patel, J .; Skelton, B. W.; White, A. H. Organometallics 1997,
16, 2175-2182. (i) Bierbach, U.; Hambley, T. W.; Roberts, J . D.; Farrell,
N. Inorg. Chem. 1996, 35, 4865-4872. (j) Aye, K. T.; Vittal, J . J .;
Puddephatt, R. J . J . Chem. Soc., Dalton Trans. 1993, 1835-1839. (k)
For examples of Pd(IV) complexes, see: Canty, A. J .; J in, H.; Roberts,
A. S.; Skelton, B. W.; White, A. H. Organometallics 1996, 15, 5713-
5722.
* To whom correspondence should be addressed. E-mail: V.G.A.,
vgalbano@ciam.unibo.it; F.R., ruffo@unina.it.
† Universita` di Bologna.
‡ Universita` di Napoli “Federico II”.
(1) (a) Kawakami, K.; Ozaki, Y.; Tanaka T. J . Organomet. Chem.
1974, 69, 151-159. See also: (b) Gysling, H. J . In The Chemistry of
Selenium and Tellurium Compounds; Patai, S., Rappoport, Z., Eds.;
Wiley: New York, 1986; Vol. 1. (c) Gysling, H. J . Coord. Chem. Rev.
1982, 42, 133-244.
(2) For recent examples, see: (a) Oilunkaniemi, R.; Laitinen, R. S.;
Ahlgre´n, M. J . Organomet. Chem. 2001, 623, 168-175. (b) Ford, S.;
Lewtas, M. R.; Morley, C. P.; Di Vaira, M. Eur. J . Inorg. Chem. 2000,
933-938. (c) Singh, A. K.; Sharma, S. Coord. Chem. Rev. 2000, 209,
49-98 and references therein. (d) Oilunkaniemi, R.; Laitinen, R. S.;
Ahlgre´n, M. J . Organomet. Chem. 1999, 587, 200-206. (e) Han, L.-B.;
Choi, N.; Tanaka, M. J . Am. Chem. Soc. 1997, 119, 1795-1796. (f)
Han, L.-B.; Shimada, S.; Tanaka, M. J . Am. Chem. Soc. 1997, 119,
8133-8134.
(4) (a) Barrientos-Astigarraga, R. E.; Castellani, P.; Comasseto, J .
V.; Formiga, H. B.; da Silva, N. C.; Sumida, C. Y.; Vieira, M. L. J .
Organomet. Chem. 2001, 623, 43-47. (b) Ogawa, A. J . Organomet.
Chem. 2000, 611, 463-474. (c) Kang, S.-K.; Lee, S.-W.; Ryu, H.-C.
Chem. Commun. 1999, 2117-2118. (d) Bayo`n, J . C.; Claver, C.;
Masdeu-Bulto`, A. M. Coord. Chem. Rev. 1999, 193-195, 73-145. (e)
Han, L.-B.; Tanaka, M. J . Am. Chem. Soc. 1998, 120, 8249-8250. (f)
Kuniyasu, H.; Sugoh, K.; Song Su, M.; Kurosawa, H. J . Am. Chem.
Soc. 1997, 119, 4669-4677.
10.1021/om020807v CCC: $25.00 © 2003 American Chemical Society
Publication on Web 02/19/2003

1224 Organometallics, Vol. 22, No. 6, 2003
Albano et al.
Sch em e 1
groups (R ) H, C(O)Me) display interesting antitumor
properties.5 Furthermore, the biological role of selenium
compounds is acknowledged and has recently been
reviewed.6
In the recent past, the ability of N,N-ligands with “in
plane” steric hindrance to stabilize the trigonal-bipyra-
midal (tbp)7 geometry in 18e platinum(II) complexes of
formula [Pt(X)(Y)(N,N-chelate)(olefin)] (I) has been
disclosed.8 Therefore, we decided to investigate the first
class of 18e platinum(II) complexes containing σ-bonded
chalcogenides (2).9 The complexes have been obtained
by oxidative addition of dichalcogenides to suitable
three-coordinate precursors [Pt(N,N-chelate)(olefin)]
(1; reaction 1 in Scheme 1).
The characterization of the products, which display
a tbp geometry with the anionic ligands in axial posi-
tions, has been carried out through elemental analyses
and NMR and IR spectroscopy. Compounds of type 2
are reliable models of the intermediates of the above-
mentioned Pt-catalyzed C-E bond formation.4 Further-
more, the availability of related Pt(IV) compounds3
allows us to verify that the differences between com-
pounds in very similar coordination environments but
different oxidation states can be more formal than real.
The reactions of type 2 species with electrophiles have
also been performed, yielding the first examples of
saturated dipositive Pt(II) complexes. The molecular
structures of the representative compounds [Pt(SMe)2-
(dmphen)(diphenyl fumarate)] and [Pt(SMe2)2(dmphen)-
(diphenyl fumarate)](BF4)2 (dmphen ) 2,9-dimethyl-
1,10-phenanthroline) have been determined by X-ray
diffractometry.
Resu lts a n d Discu ssion
Gen er a l F ea tu r es of th e Ad d ition . Type 2 com-
plexes have been obtained according to reaction 1 of
Scheme 1. dmphen is the N,N-chelate of choice, due to
its assessed peculiar ability in stabilizing the trigonal-
bipyramidal geometry.8 The olefins are dimethyl male-
ate, dimethyl fumarate, and diphenyl fumarate (a -c in
Scheme 1). Their properties confer sufficient solubility
and stability to the Pt(0) complexes without reducing
the basicity. Furthermore, the symmetry of these ligands
restricts the number of isomers of the products and
helps to correctly formulate their structure. More pre-
cisely, if the addition proceeds with cleavage of the E-E
bonds, the fumarate products are enantiomeric couples
of C2 symmetry. The 2-fold axis bisecting the equatorial
ligands generates the NMR equivalence of the axial
ligands, the trans-olefin protons, and the halves of the
N,N-chelate. On the other hand, the analogous maleate
products (Cs symmetry) possess a mirror symmetry
bisecting the equatorial plane and, hence, the olefin
protons and the halves of the chelate are equivalent,
while the axial ligands are no longer equivalent.
Some additions have been performed on the three-
coordinate precursor [Pt(phen)(dimethyl fumarate)]
(phen ) 1,10-phenanthroline), containing a chelate with
poor “in plane” steric hindrance. This choice is aimed
at obtaining the corresponding square-planar products
[Pt(ER)2(1,10-phen)] by olefin loss. Unexpectedly, also
in these cases five-coordinate products of type 2 have
been isolated, despite the lack of steric constraints. The
complexes do not show a tendency to release the olefin
but are involved in a slow nonchemoselective decompo-
sition process, which goes to completion within a few
hours at room temperature. Success in isolating tbp
complexes of phen is most probably due to a kinetic
inertness rather than thermodynamic stability, as
observed for other complexes of type I.10 The products
(5) Wong, E.; Giandomenico, C. M. Chem. Rev. 1999, 99, 2451-2466.
(6) Mugesh, G.; du Mont, W.-W.; Sies, H. Chem. Rev. 2001, 101,
2125-2179.
(7) Throughout this paper we refer to the 18e platinum complexes
as five-coordinate trigonal bipyramidal. The reader should keep in
mind that the alternative description as distorted octahedral is in some
cases more useful.
(8) Albano, V. G.; Natile, G.; Panunzi, A. Coord. Chem. Rev. 1994,
133, 67-114.
(9) Preliminary results have been published: Albano, V. G.; Monari,
M.; Orabona, I.; Panunzi, A.; Ruffo, F. J . Am. Chem. Soc. 2001, 123,
4352-4353.

Trigonal-Bipyramidal Pt(II) Olefin Complexes
Organometallics, Vol. 22, No. 6, 2003 1225
[
13Cb] NMR Da ta for Typ e 2 a n d 3 Com p lexes
Ta ble 1. Releva n t 1Ha
complex
E-Rc
olefind
other selected signals
[Pt(OH)2(dmphen)(dimethyl maleate)]
(2a (OH))
4.27 (s, 2H, 81)
3.78 (s, 6H, OMe),
3.46 (s, 6H, Me)
[Pt(OH)2(dmphen)(dimethyl fumarate)]
(2b(OH))
4.80 (s, 2H, 72)
3.81 (s, 6H, OMe),
3.36 (s, 6H, Me)
[Pt(AcO)2(dmphen)(dimethyl maleate)]
(2a (OAc))
4.60 (s, 2H, 74)
[38.1 (386)]
3.73 (s, 6H, OMe),
3.62 (s, 6H, Me),
1.59 (s, 3H, OAc),
1.39 (s, 3H, OAc)
[Pt(AcO)2(dmphen)(dimethyl fumarate)]
(2b(OAc))
5.37 (s, 2H, 76)
[37.5 (353)]
3.71 (s, 6H, OMe),
3.66 (s, 6H, Me),
1.49 (s, 6H, OAc)
[Pt(O2CPh)(OH)(dmphen)(dimethyl fumarate)]
(2b(O2CP h )(OH)
5.37 (d, 1H),
5.15 (d, 1H)
[37.1 (361),
35.0 (353)]
3.86 (s, 3H, OMe),
3.77 (s, 3H, OMe),
3.58 (s, 3H, Me),
3.37 (s, 3H, Me)
[174.5, 171.0,
170.8, CO]
[Pt(SMe)2(dmphen)(dimethyl maleate)]
(2a (SMe))
1.18 (s, 3H, 25), 0.77 (s, 3H, 27)
[11.6 and 10.6]
4.22 (s, 2H, 81)
[34.9 (393)]
3.79 (s, 6H, OMe),
3.41 (s, 6H, Me)
[Pt(SPh)2(dmphen)(dimethyl maleate)]
(2a (SP h ))
6.60 (m, 1H), 6.34 (m, 5H),
6.19 (d, 2H), 6.05 (t, 2H)
4.26 (s, 2H, 82)
[35.9 (377)]
3.89 (s, 6H, OMe),
3.42 (s, 6H, Me)
[Pt(SMe)2(dmphen)(dimethyl fumarate)]
(2b(SMe))
0.98 (s, 6H, 27)
[11.3]
4.75 (s, 2H, 86)
[30.4 (361)]
3.72 (s, 6H, OMe),
3.53 (s, 6H, Me)
[Pt(SPh)2(dmphen)(dimethyl fumarate)]
(2b(SP h ))
6.33 (t, 2H), 6.07 (m, 8H)
4.80 (s, 2H, 80)
[33.6 (355)]
3.79 (s, 6H, OMe),
3.56 (s, 6H, Me)
[Pt(SeMe)2(dmphen)(dimethyl maleate)]
(2a (SeMe))
0.92 (s, 3H, 20), 0.56 (s, 3H, 23)
[-3.3 and -3.9]
4.24 (s, 2H, 79)
[31.8 (388)]
3.76 (s, 6H, OMe),
3.41 (s, 6H, Me)
[Pt(SePh)2(dmphen)(dimethyl maleate)]
(2a (SeP h ))
6.75 (t, 1H), 6.57 (t, 1H),
6.49 (d, 2H), 6.32 (d, 2H),
6.23 (t, 2H), 6.02 (t, 2H)
4.34 (s, 2H, 81)
[32.3 (377)]
3.81 (s, 6H, OMe),
3.29 (s, 6H, Me)
[Pt(SeMe)2(dmphen)(dimethyl fumarate)]
0.61 (s, 6H, 25)
[-3.3]
4.85 (s, 2H, 82)
[30.6 (354)]
3.78 (s, 6H, OMe),
3.57 (s, 6H, Me)
(2b(SeMe))e
[Pt(SePh)2(dmphen)(dimethyl fumarate)]
6.35 (t, 2H), 6.10 (d, 4H),
5.95 (t, 4H)
4.81 (s, 2H, 80)
[31.7 (350)]
3.80 (s, 6H, OMe),
3.56 (s, 6H, Me)
(2b(SeP h ))e
[Pt(TePh)2(dmphen)(dimethyl maleate)]
(2a (TeP h ))
6.69 (t, 1H), 6.52 (t, 1H),
6.46 (d, 2H), 6.29 (d, 2H),
6.17 (t, 2H), 5.97 (t, 2H)
4.29 (s, 2H, 81)
[28.7 (318)]
3.85 (s, 6H, OMe),
3.26 (s, 6H, Me)
[Pt(TePh)2(dmphen)(dimethyl fumarate)]
(2b(TeP h ))
6.51 (t, 2H), 6.17 (d, 4H),
5.94 (t, 4H)
4.75 (s, 2H, 79)
[29.6 (348)]
3.80 (s, 6H, OMe),
3.50 (s, 6H, Me)
[Pt(SMe)2(dmphen)(diphenyl fumarate)]
(2c(SMe))
1.05 (s, 6H, 27)
[11.2]
5.04 (s, 2H, 82)
[31.8 (347)]
7.3-7.1 (m, 10 H, Ph),
3.53 (s, 6H, Me)
[Pt(SeMe)2(phen)(dimethyl fumarate)]
[Pt(SePh)2(phen)(dimethyl fumarate)]
0.90 (s, 6H, 24)
4.86 (s, 2H, 82)
4.80 (s, 2H, 84)
3.80 (s, 6H, OMe)
3.85 (s, 6H, OMe)
6.44 (t, 2H), 6.15 (d, 4H),
6.04 (t, 4H)
[Pt(SMe2)2(dmphen)(dimethyl fumarate)][BF4]2
1.93 (s, 6H, 28),
1.49 (s, 6H, 28)
4.98 (s, 2H, 68)
4.82 (s, 2H, 64)
5.34 (s, 2H, 66)
3.91 (s, 6H, OMe),
3.44 (s, 6H, Me)
(3b(SMe2))f
[Pt(SeMe2)2(dmphen)(dimethyl fumarate)][BF4]2
1.66 (s, 6H, 30),
1.35 (s, 6H, 29)
3.95 (s, 6H, OMe),
3.38 (s, 6H, Me)
(3b(SeMe2))f
[Pt(SMe2)2(dmphen)(diphenyl fumarate)][BF4]2
2.15 (s, 6H, 32),
1.53 (s, 6H, 30)
3.70 (s, 6H, Me)
(3c(SMe2))f
a
At 200 or 300 MHz and 298 K. CDCl3 was used as solvent (CHCl3, δ 7.26 as internal standard). Abbreviations: s, singlet; d, doublet;
t, triplet; m, multiplet. At 50.2 or 62.9 MHz and 298 K. CDCl3 was used as solvent (13CDCl3, δ 77 as internal standard).
J
(Hz)
Pt-H
b
c 3
in parentheses. J Pt-H and J Pt-C in parentheses. e Data taken from ref 9. f In CD3NO2 (CD2HNO2, δ 4.33 as internal standard).
d
2
1
are reported in Table 1 with their labeling: the letters
a -c indicate the olefin, while the axial fragments are
specified in parentheses.
The additions of H2O2 have been conducted in THF
and found to be complete within a few seconds. Addition
of diethyl ether to the reaction mixture affords the pale
yellow products 2a (OH) and 2b(OH) in good yields. The
complexes are soluble in chlorinated solvents and water.
The pattern of the 1H NMR spectra is in agreement with
the symmetry of the complexes just described. Thus, in
both cases the equivalent olefin protons resonate as
singlets, respectively, at δ 4.27 and 4.80. The signals
are shifted upfield by ca. 2 ppm with respect to those of
Oxid a t ive Ad d it ion of P er oxid es. The three-
coordinate precursors 1a and 1b have been reacted with
hydrogen peroxide, diacetyl peroxide, and dibenzoyl
peroxide.
(10) Albano, V. G.; Castellari, C.; Monari, M.; De Felice, V.; Panunzi,
A.; Ruffo, F. Organometallics 1992, 11, 3665-3669.

1226 Organometallics, Vol. 22, No. 6, 2003
Albano et al.
the free olefins, in the range considered diagnostic of
trigonal-bipyramidal complexes containing dimethyl
maleate or dimethyl fumarate.11 The IR spectra show
is filtered from the reaction mixture and washed with
diethyl ether.
The NMR spectra of the products are in line with the
aforementioned expected features.14 Again, the chemical
shifts of the olefin protons fall in the range considered
diagnostic for compounds of type I. With reference to
the free alkenes, the ∆δ value is ca. 2 ppm for both dmm
and dmf, irrespective of the organoelement ligand. The
high-field shift is substantially larger than that found11
in the corresponding dichloro, dibromo, and diiodo
complexes (∆δ < 1.5). The entity of the shift has been
correlated to the extent of π-back-donation,8 which
increases as the electronic density on the metal grows.
Hence, this spectral evidence suggests that organo-
chalcogenide ligands are better donors than halides in
the axial position of the trigonal bipyramid.
bands in the ranges 3520-3500 and 550-535 cm-1
,
accounting for the O-H and Pt-O stretchings, respec-
tively.12
The oxidative additions of diacetyl peroxide to 1a and
1
1b are complete within 12 h in toluene. In the H NMR
spectrum dimethyl maleate and dimethyl fumarate
olefin protons resonate at δ 4.60 and δ 5.37, respectively.
As expected, the axial groups are equivalent in the
fumarate product 2b(OAc), which confirms that the
addition proceeds with cleavage of the O-O bond.
Obviously, the equivalence of the acetyl groups is not
retained in 2a (OAc), and two singlets at δ 1.59 and 1.39
are found.
As expected, both olefins and -EMe nuclei couple to
The addition of dibenzoyl peroxide to 1b has also been
performed. The spectrum of the product, isolated after
6 days of stirring in toluene, unexpectedly discloses the
nonequivalence of the fumarate protons (two doublets
at δ 5.37 and 5.15) and the halves of dmphen. This
feature reveals that the axial ligands are not equivalent.
Furthermore, the aromatic region is integrated for only
11 protons (6 for dmphen and 5 for one phenyl group),
thus suggesting loss of one benzoate group. The 13C
spectrum is in keeping with this hypothesis, as only
three signals in the low-field region can be attributed
to as many carbonyl groups. The ensemble of results
suggests that the addition of dibenzoyl peroxide is
followed by hydrolysis of one Pt-OC(O)Ph bond with
formation of the mixed product [Pt{OC(O)Ph}(OH)(dm-
phen)(dimethyl fumarate)] (2b(O2CP h )(OH)). Attempts
to isolate the dibenzoate compound by working up the
reaction at earlier stages have proved unsuccessful.
2
1
195Pt. For the alkenes, the values of J Pt-H and J Pt-C
are within 78-82 and 350-450 Hz, respectively. On the
3
other hand, the J Pt-H satellites of the methyl signals
are in the range 20-25 Hz. The -SeMe resonances are
enriched by coupling to 77Se (2J Se-H ca. 10 Hz).
Another spectral feature worth mentioning is the
high-field shift of the phenyl protons of the -EPh
ligands. A high-field shift of ca. 1.5 ppm is observed,
presumably due to π-stacking of the phenyl rings with
the aromatic rings of the nitrogen chelate. This interac-
tion has been disclosed in the solid state for the
representative complex 2a (SeP h )9 and should be com-
pared to that found in the related Pt(IV) complexes
[PtMe2(EPh)2(N,N-chelate)].3d,h
On the whole, the spectral features of the complexes
do not significantly change upon variation of the axial
E atom.
Rea ctivity. The reactivity of the axial ligands in
some complexes of type 2 has been explored. The
hydroxyl groups in 2a (OH) are readily acetylated in the
presence of acetic anhydride (reaction 2 in Scheme 1).
The identity of the product 2a (OAc) has been confirmed
by comparison with the same complex obtained inde-
pendently by oxidative addition of diacetyl peroxide (see
above). Esterification of Pt-bonded hydroxyl groups in
the presence of a suitable electrophile has been previ-
ously reported in the case of platinum(IV) derivatives.12
This procedure has allowed the synthesis of orally active
antitumor compounds, which show significant structural
analogies with 2a (OAc) despite the different oxidation
state.
The nucleophilicity of S, Se, and Te atoms in the
coordinated chalcogenide ligands has been verified.
Thus, complexes 2b(SMe), 2b(SeMe), and 2c(SMe)
have been reacted with 2 equiv of Me3OBF4 in ni-
tromethane (reaction 3 in Scheme 1).
In all cases, the two axial heteroatoms are readily
methylated with formation of the corresponding diposi-
tive cations (3) containing the newly formed EMe2
ligands in axial positions. As far as we know, these are
the first examples of coordinatively saturated Pt(II)
compounds exhibiting a dipositive net charge. The
complexes can be isolated in high yield and stored for
several days at 273 K without appreciable decomposi-
tion.
It should be noted that cleavage of the M-benzoate
bond has been previously found to occur quite easily
when M ) Pd,3e while stable dibenzoate compounds are
isolated when the addition of dibenzoyl peroxide is
performed on Pt(II) precursors of formula [Pt(hydro-
carbyl)2(bipy)].3b,j
Use of dimethyl peroxide (MeOOMe) as oxidant was
also attempted. Unexpectedly, a violen t explosion
occurred during its preparation.13 No further experi-
ment was carried out.
Oxidative Addition of th e Oth er Dich alcogen ides.
The three-coordinate complexes have been reacted with
dichalcogenides RE-ER (E ) S, Se, Te; R ) Me, Ph).
The reactions have been performed by adding an excess
of oxidant to a chloroform solution or a toluene suspen-
sion of the Pt(0) precursors. A rapid change of color from
yellow to red often signals the completion of the reac-
tion. The products can be obtained in pure form as
yellow-orange solids by addition of hexane to the reac-
tion mixture. Only the less reactive dimethyl disulfide
requires more drastic conditions, and the reactions were
performed in neat electrophile. After 24 h the product
(11) De Felice, V.; Funicello, M.; Panunzi, A.; Ruffo, F. J . Organomet.
Chem. 1991, 403, 243-252.
(12) Giandomenico, C. M.; Abrams, M. J .; Murrer, B. A.; Vollano, J .
F.; Rheinheimer, M. I.; Wyer, S. B.; Bossard, G. E.; Higgins, J . D., III.
Inorg. Chem. 1995, 34, 1015-1021.
(13) Hanst, P. L.; Calvert, J . G. J . Phys. Chem. 1959, 63, 104-106.
The explosion occurred during dropwise addition at 273 K of 40%
aqueous potassium hydroxide to the solution of dimethyl sulfate and
hydrogen peroxide.
(14) The dimethyl selenide derivatives are reversibly dissociated in
solution into the corresponding precursors. This equilibrium process
is being investigated separately.9

Trigonal-Bipyramidal Pt(II) Olefin Complexes
Organometallics, Vol. 22, No. 6, 2003 1227
Ta ble 2. Com p a r ison of Releva n t Bon d
P a r a m eter s in [P t(SMe)2(d m p h en )(d ip h en yl
fu m a r a te)] (2c(SMe)) a n d
[P t(SMe2)2(d m p h en )(d ip h en yl fu m a r a te)]2+
(3c(SMe2)) (Dista n ces in Å a n d An gles in d eg)
2c(SMe)
3c(SMe2)
Bond Distances
2.071(4)
2.095(4)
Pt-C(olefin)
2.067(15)
2.087(13)
2.083 (av)
1.444(6)
2.378(1)
2.077 (av)
1.446(19)
2.348(4)
2.376(4)
C-C(olefin)
Pt-S
2.375(1)
2.376 (av)
1.816(5)
1.807(6)
1.812 (av)
2.196(3)
2.198(3)
2.362 (av)
S-C(methyl)
Pt-N
1.784(11), 1.798(11)
1.792(13), 1.811(13)
1.796 (av)
2.184(13)
2.228(12)
2.197 (av)
2.206 (av)
Bond Angles
177.52(4)
90.6(1)
92.3(1)
92.1(1)
91.9(1)
91.8(1)
89.9(1)
86.2(1)
S1-Pt-S2
S1-Pt-C1
S1-Pt-C2
S1-Pt-N1
S1-Pt-N2
S2-Pt-C1
S2-Pt-C2
S2-Pt-N1
S2-Pt-N2
N1-Pt-N2
177.34(15)
93.2(4)
95.0(4)
89.5(3)
88.4(3)
86.1(4)
86.1(4)
91.9(3)
89.7(3)
77.6(5)
86.0(1)
75.6(1)
F igu r e 1. ORTEP drawing (30% probability thermal
ellipsoids) of [Pt(SMe)2(dmphen)(diphenyl fumarate)] (2c-
(SMe)) showing one of the two conformational isomers (A)
present in the crystal in equal amounts. The second isomer
(B) exhibits the phenyl group (C11B-C16B) bound to O(3)
instead of O(4). Hydrogen atoms, except the olefinic ones,
have been omitted for clarity.
Torsion Angle (Fumarate)
44.4(4) 57.6(10)
C-CdC-C
The NMR spectra disclose that the products retain
the C2 symmetry. The halves of the olefin and N,N-
chelate are equivalent, as are the axial ligands. Due to
the presence of a prochiral olefin, the methyl groups on
each E atom are diastereotopic and, hence, not chemi-
cally equivalent.
The X-ray structure of 3c(SMe2) has been deter-
mined.
X-r a y Molecu la r Str u ctu r es of [P t(SMe)2(d m -
p h en )(d ip h en yl fu m a r a te)] (2c(SMe)), Its Ca tion ic
Der iva t ive [P t (SMe2)2(d m p h en )(d ip h en yl fu m a -
r a te)][BF 4]2 (3c(SMe2)), a n d F r ee Dip h en yl F u m a -
r a te. The crystals of [Pt(SMe)2(dmphen)(diphenyl fu-
marate)] (2c(SMe)) contain equal amounts of two
conformational isomers produced by different orienta-
tions of one -CO(O)Ph group in the fumarate ligand.
Figure 1 shows the structure of one isomer, while the
other contains a phenyl group attached to O(3) in place
of the one shown bonded to O(4) (see Experimental
Section). Although the molecule could conform to an
idealized C2 symmetry, as it does in solution on the
NMR time scale, the actual conformation is asymmetric,
mainly because of the unrelated orientations of the
-SMe axial groups. The methyl group bonded to S1
(C(31)) is oriented above the phenanthroline rings, while
that on the opposite side (C(32)) is oriented almost
orthogonal to the first one. The steric pressure of the
C(31) methyl induces a bending of the phenanthroline
out of the coordination plane (PtNN/dmphen dihedral
angle 13.5(2)°). The equatorial olefin carbons and ni-
trogen atoms are almost coplanar (PtNN/PtCC dihedral
angle 4.9(5)°). Bond parameters of interest are reported
F igu r e 2. ORTEP drawing (30% probability thermal
ellipsoids) of the dication [Pt(SMe2)2(dmphen)(diphenyl
fumarate)]2+ (3c(SMe2)). Hydrogen atoms, except the
olefinic ones, have been omitted.
in Table 2 together with the corresponding ones in the
dication [Pt(SMe2)2(dmphen)(diphenyl fumarate)]2+ (3c-
(SMe2)), whose geometry is shown in Figure 2. This
molecule is frozen in a single asymmetric conformation
in the crystal, and again the mutual orientations of the
SMe2 ligands are not symmetry-related. Also, the

1228 Organometallics, Vol. 22, No. 6, 2003
Albano et al.
metrical cleavage of the E-E bond has been observed,
with formation of trigonal-bipyramidal products [Pt-
(ER)2(N,N-chelate)(olefin)] (2) containing the chalco-
genide ligands in axial positions. Compounds of type 2
represent the first class of coordinatively saturated
Pt(II) species containing chalcogenide ligands and con-
stitute the platinum(II) complement of previously de-
scribed octahedral platinum(IV) species.3 Furthermore,
the basicity of S, Se, and Te atoms coordinated to Pt
has been usefully exploited for preparing the first
examples of dipositive Pt(II) cations in a trigonal-
bipyramidal arrangement. Finally, we recall that, in this
study, we have also found that the addition of the E-E
bond to platinum(0)9 precursors can be reversible. This
very rare case16 of equilibrium in an oxidative addition
process has also been very recently extended to related
platinum(II) species.17
F igu r e 3. ORTEP drawing (30% probability thermal
ellipsoids) of the solid-state structure of free diphenyl
fumarate. The idealized symmetry is Cs, if the phenyl
groups are ignored. Relevant distances (Å): C(1)-C(2) )
1.307(2), C(1)-C(3) ) 1.479(2), C(2)-C(4) ) 1.482(2), C(3)-
O(2) ) 1.193(2), C(4)-O(3) ) 1.195(2), C(3)-O(1) ) 1.341-
(2), C(4)-O(4) ) 1.341(2), O(1)-C(5) ) 1.416(1), O(4)-
C(11) ) 1.410(1) Å. Torsion angle (deg): C(3)-C(1)-C(2)-
C(4) ) 0.4(1).
Exp er im en ta l Section
-C(O)OPh groups are not superimposable by an ideal-
ized 2-fold rotation. In this molecule the methyl groups
exert steric pressure on either side of the phenanthro-
line rings, even though in an unbalanced way. As a
consequence the bending of the bidentate ligand out of
the equatorial plane is much smaller (6.4(4)°). Corre-
sponding bond parameters in the neutral and dicationic
species can be analyzed on inspecting Table 2. We were
expecting some shrinkage of the primarily σ bonds and
stretching of those with significant π-contribution. The
observed effects are small and only at the level of
average values can tiny shortenings, not exceeding 0.01
Å, be observed in the dication. Very probably, packing
effects tend to blur the differences that are in any way
small. A molecule whose structure is comparable to the
previous ones is [Pt(SCN)2(dmphen)(dimethyl male-
ate)],15 and the bond values, although affected by higher
errors, are in accord with the present ones.
Of some interest is a comparison between the geom-
etry of the diphenyl fumarate as a free molecule and as
a ligand coordinated to platinum. The solid-state struc-
ture of the ligand is illustrated in Figure 3. The molecule
adopts a flat conformation, if the phenyl groups are
disregarded, and the idealized symmetry is Cs. Upon
coordination the CdC double bond undergoes the ex-
pected elongation (ca. 0.14 Å for both molecules) and
outward bending of the C(carboxylate) atoms. The
C-CdC-C torsion angles are 0.4(1), 44.4(4), and 57.6-
(10)° in the free ligand and neutral and dipositive
complexes, respectively. The higher torsion of the carbon
skeleton in the dication can be explained in terms of
the metallacyclopropane bond model of the platinum-
olefin interaction. A stronger C-Pt σ bond induces a
more marked sp3 rehybridization of the carbon orbitals.
The equivalence of Pt-C bond distances in the neutral
and dipositive species also indicates that the total bond
order is substantially preserved through a different
balance of its σ and π components.
1H and 13C NMR spectra were recorded on Varian XL-200
or Varian Gemini-300 spectrometers. CDCl3 and CD3NO2 were
used as solvents; CHCl3 (δ 7.26), 13CDCl3 (δ 77.0) and CD2-
HNO2 (δ 4.33) were the internal standards. The following
abbreviations were used for describing NMR multiplicities: s,
singlet; d, doublet; dd, double doublet; t, triplet; m, multiplet.
Infrared spectra were recorded on
a J ASCO FT-IR 430
spectrometer. Dibenzoyl peroxide, hydrogen peroxide, dimethyl
disulfide, dimethyl diselenide, diphenyl disulfide, diphenyl
diselenide, diphenyl ditelluride, and trimethyloxonium tet-
rafluoroborate were commercially available (Sigma-Aldrich).
Diacetyl peroxide18 and the Pt(0) precursors19 were obtained
according to published methods.
[P t(OH)2(d m p h en )(d im eth yl m a lea te)] (2a (OH)). Aque-
ous hydrogen peroxide (30%, 0.3 mL) was added to a magneti-
cally stirred suspension of the three-coordinate precursor
(0.050 g, 0.090 mmol) in tetrahydrofuran (2 mL). After stirring
for 5 min at room temperature the precipitate was separated,
washed with tetrahydrofuran (3 mL) and chloroform (1 mL),
and dried in vacuo. Yield: 60%.
[P t(OH)2(dm ph en )(dim eth yl fu m ar ate)] (2b(OH)). Aque-
ous hydrogen peroxide (30%, 0.3 mL) was added to a magneti-
cally stirred suspension of the three-coordinate precursor
(0.050 g, 0.09 mmol) in tetrahydrofuran (2 mL). After the
mixture was stirred for 5 min at room temperature, the
resulting solution was filtered and concentrated in vacuo to a
small volume. Addition of diethyl ether caused crystallization
of the pale yellow product, which was washed with diethyl
ether and dried in vacuo. Yield: 50%.
[P t(OAc)2(d m p h en )(olefin )] (2a (OAc) a n d 2b(OAc)). An
ethereal solution of diacetyl peroxide (1 mL) was added under
nitrogen to a magnetically stirred suspension of the three-
coordinate precursor (0.050 g, 0.090 mmol) in dry toluene (2
mL). After the mixture was stirred for 16 h at room temper-
ature, a yellow precipitate was separated, washed with toluene
and diethyl ether, and dried in vacuo. Yield: 70-80%.
[P t{OC(O)P h }(OH)(d m p h en )(d im eth yl fu m a r a te)] (2b-
(O2CP h )(OH)). To a magnetically stirred suspension of the
three-coordinate precursor (0.10 g, 0.18 mmol) in toluene (5
mL) was added dibenzoyl peroxide (0.17 g, 0.72 mmol). The
suspension was stirred for 7 days. The residual solid was
removed by filtration and the solution concentrated to a small
Con clu sion s
This paper illustrates the oxidative addition of RE-
ER molecules (E ) O, S, Se, Te) to Pt(0) precursors of
the general formula [Pt(N,N-chelate)(olefin)]. Sym-
(16) Albano, V. G.; De Felice, V.; Monari, M.; Panunzi, A.; Ruffo, F.
Organometallics 1996, 15, 4012-4019.
(17) Panunzi, A.; Roviello, G.; Ruffo, F. Organometallics 2002, 21,
3503-3505.
(18) Cooper, W. J . Chem. Soc. 1951, 3112-3113.
(19) De Renzi, A.; Panunzi, A.; Ruffo, F. Inorg. Synth. 1998, 32, 158-
162.
(15) Giordano, F.; Panunzi, B.; Roviello, A.; Ruffo, F. Inorg. Chim.
Acta 1995, 239, 61-66.

Trigonal-Bipyramidal Pt(II) Olefin Complexes
Organometallics, Vol. 22, No. 6, 2003 1229
Ta ble 3. Cr ysta l Da ta a n d Diffr a ction Exp er im en ta l Deta ils for [P t(SMe)2(d m p h en )(d ip h en yl
fu m a r a te)]‚1.5CHCl3 (2c(SMe)), [P t(SMe2)2(d m p h en )(d ip h en yl fu m a r a te)][BF 4]2 (3c(SMe2)), a n d Dip h en yl
F u m a r a te
C
32H30N2O4PtS2‚1.5CHCl3
(2c(SMe))
C
34H36B2F8N2O4PtS2
(3c(SMe2))
C16H12O4
268.26
Mr
944.84
969.48
cryst symmetry
space group
a, Å
b, Å
triclinic
monoclinic
P21/ n (No. 14)
11.5573(8)
23.140(1)
14.653(1)
90
104.585(2)
90
3792.3(4)
4
monoclinic
P21/ c (No. 14)
10.8898(4)
7.7762(3)
16.3121(6)
90
106.639(2)
90
1323.49(9)
4
P1h (No. 2)
9.128(3)
13.748(4)
15.297(5)
77.071(1)
78.162(1)
89.583(1)
1829.7(1)
2
c, Å
R, deg
â, deg
γ, deg
cell vol, Å3
Z
Dc, Mg m-3
1.715
4.316
930
1.698
3.889
1912
1.346
0.097
560
µ(Mo KR), mm-1
F(000)
cryst size, mm
θ limits, deg
no. of rlfns collected
no. of unique obsd rflns (Fo > 4σ(Fo))
goodness of fit on F2
R1(F),a wR2(F2)b
0.20 × 0.25 × 0.45
0.10 × 0.15 × 0.21
0.10 × 0.13 × 0.16
1.95-30
34 609
3870 (Rint ) 0.042)
0.891
1.5-30
2.5-25
25 267
10 694 (Rint ) 0.044)
1.040
34 529
6659 (Rint ) 0.090)
0.961
0.0392, 0.1048
0.0632, 0.1595
0.0426, 0.1067
R1) ∑||Fo| - |Fc|/∑|Fo|. wR2 ) [∑w(Fo - Fc2)2/∑w(Fo2)2]1/2, where w ) 1/[σ2(Fo2) + (aP)2 + bP] and P ) (Fo + 2Fc
)
.
a
b
2
2
2 1/3
volume. Slow addition of hexane caused crystallization of the
afford the yellow compound 2a (OAc), which was washed with
product, which was washed with hexane (2 mL) and dried in
vacuo. Yield: 60%.
diethyl ether (1 mL) and dried in vacuo. Yield: 65%.
[P t(EMe2)2(dm ph en )(olefin )][BF4]2 (3b(SMe2), 3b(SeMe2),
a n d 3c(SMe2)). A solution of trimethyloxonium tetrafluorobo-
rate (0.060 g, 0.040 mmol) in nitromethane (0.5 mL) was added
to the appropriate type 1 compound (0.020 mmol). After the
mixture was stirred for 5 min, slow addition of diethyl ether
to the resulting solution afforded the light yellow product,
which was washed with diethyl ether and dried in vacuo.
Yield: 60-70%.
[P t(SMe)2(d m p h en )(olefin )] (2a (SMe), 2b(SMe), a n d
2c(SMe)). The appropriate three-coordinate precursor (0.20
mmol) was suspended in dimethyl disulfide (1 mL). After the
mixture was stirred for 24 h, a red solution was obtained.
Addition of diethyl ether caused crystallization of a pale yellow
compound, which was washed with diethyl ether (3 mL) and
dried in vacuo. Yield: >90%.
X-r a y Da ta Collection a n d Str u ctu r e Deter m in a tion
of [P t(SMe)2(d m p h en )(d ip h en yl fu m a r a te)] (2c(SMe)),
[P t (SMe2)2(d m p h en )(d ip h en yl fu m a r a t e)][BF 4]2 (3c(S-
Me2)), a n d Dip h en yl F u m a r a te. The X-ray diffraction
intensities for the three compounds were measured on a
Bruker AXS SMART 2000 diffractometer, equipped with a
CCD detector, using Mo KR radiation (λ ) 0.710 73 Å) at room
temperature. Crystal data and some experimental details are
given in Table 3. A full sphere of reciprocal space was scanned
by 0.3° ω steps with the detector kept at 5.0 cm from the
sample. The collected frames were processed for integration
by using the program SAINT, and an empirical absorption
correction was applied using SADABS.20 The structures were
solved by direct methods (SIR 97)21 and subsequent Fourier
syntheses and refined by full-matrix least squares on F2
(SHELXTL).22 The hydrogen atoms of the two complexes were
included in idealized positions, except the olefinic hydrogens
in the neutral [Pt(SMe)2(dmphen)(diphenyl fumarate)], which
were located in the Fourier map and their positions refined.
The final refinement proceeded using anisotropic thermal
parameters for all the non-hydrogen atoms. The H atoms were
assigned isotropic thermal parameters U(H) set at 1.2 (1.5 for
the methyl groups) times the Ueq value of the carrier carbon
atoms. The solution of the structure of [Pt(SMe)2(dmphen)-
(diphenyl fumarate)] was carried out in the centric space group
P1h, and electron density maps disclosed most atoms, including
a chloroform molecule. Complications arose for the interpreta-
[P t(SP h )2(d m p h en )(olefin )] (2a (SP h ) a n d 2b(SP h )). A
solution of diphenyl disulfide (0.042 g, 0.19 mmol) in chloro-
form (0.5 mL) was added to a suspension of the appropriate
three-coordinate compound (0.070 g, 0.13 mmol) in chloroform
(0.5 mL). After the mixture was stirred for 24 h, addition of
diethyl ether to the resulting red solution afforded the product
as an orange solid, which was washed with diethyl ether and
dried in vacuo. Yield: >90%.
[P t(SeR)2(d m p h en )(olefin )] (2a (SeMe), 2b(SeMe),9 2a -
(SeP h ), a n d 2b(SeP h )).9 A solution of the appropriate
diselenide (0.18 mmol) in chloroform (0.5 mL) was added to a
suspension of the appropriate three-coordinate compound
(0.050 g, 0.09 mmol) in chloroform (0.5 mL). After the mixture
was stirred for 3 h, addition of hexane afforded the orange
product, which was washed with hexane and dried in vacuo.
Yield: 80-90%.
[P t(TeP h )2(d m p h en )(olefin )] (2a (TeP h ) a n d 2b(TeP h )).
Diphenyl ditelluride (0.074 g, 0.18 mmol) was added to a
suspension of the appropriate three-coordinate compound
(0.050 g, 0.090 mmol) in chloroform (0.5 mL). After the mixture
was stirred for 3 h, a dark solution was obtained. By addition
of diethyl ether the crystallization of the dark red product
ensued, which was washed with diethyl ether and dried in
vacuo. Yield: 85%.
[P t (SeR )2(p h en )(d im et h yl fu m a r a t e)] (R ) Me, P h ).
The appropriate diselenide (1.3 mmol) was added to a suspen-
sion of the three-coordinate compound 2b (0.070 g, 0.013 mmol)
in toluene (4 mL). After the mixture was stirred for 48 h, the
precipitate was separated, washed with toluene and diethyl
ether, and dried in vacuo. Yield: 70-80%.
R ea ct ion of [P t (OH)2(d m p h en )(d im et h yl m a lea t e)]
(2a (OH)) w ith Acetic An h yd r id e. The complex 2a (OH)
(0.050 g, 0.090 mmol) was suspended in acetic anhydride (1
mL) and stirred in the dark at room temperature for 6 h. The
yellow solution was filtered and reduced under vacuum to
(20) Sheldrick, G. M. SADABS: Program for Empirical Absorption
Correction; University of Go¨ttingen, Go¨ttingen, Germany, 1996.
(21) Altomare, A.; Cascarano, C.; Giacovazzo, C.; Guagliardi, A.;
Moliterni, A. G. G.; Burla, M. C.; Polidori, G.; Camalli, M.; Spagna, R.
SIR97: a New Tool for Crystal Structure Determination and Refine-
ment. J . Appl. Crystallogr. 1999, 32, 115.
(22) Sheldrick, G. M. SHELXTLplus Version 5.1 (Windows NT
Version) Structure Determination Package; Bruker Analytical X-ray
Instruments Inc., Madison, WI, 1998.

1230 Organometallics, Vol. 22, No. 6, 2003
Albano et al.
tion of the electron density peaks in the region occupied by
one C(O)OPh group. Phenyl rings attached to both oxygen
atoms were recognized, and more than that, one of them was
superimposed to a group of out-of-plane peaks compatible with
a CCl3 group. The rationalization of the disorder was as
follows: two conformational isomers of the diphenyl fumarate
ligand corresponding to alternative orientations of the -C(O)-
OPh fragment bonded to C(2) are present in the crystal in
equivalent amounts. Where the phenyl group is bonded to O(4)
(C(11A)-C(16A) as shown in Figure 1), its alternative position
is occupied by a chloroform molecule in order to fill in the
available space. Where the phenyl group is bonded to O(3) (not
shown in Figure 1), the volume belonging to C(11A)-C(16A)
is empty. The packing of the two isomers is probably ordered
in the crystal, because the C(11A)-C(16A) phenyl bumps into
its equivalent in a nearby molecule, indicating that contiguous
molecules must belong to different isomers. Therefore, the
isomers are packed in a concerted way: i.e., they are ordered
in the space group P1 with two independent molecules. The
refinement of the latter structure model was not possible
because the least-squares matrix was unstable, probably
because most atoms conform to a centric packing. Therefore,
we had to go back to the disordered structure model in the P1h
space group comprising one complex and 1.5 chloroform
molecules in the asymmetric unit.
fluorine atoms. The standard errors of the structure model are
higher than for the previous molecule because the crystal did
not diffract for θ angles above 25°.
The structure of diphenyl fumarate was solved in the space
group P21/c, and all non-H atoms were refined anisotropically.
The hydrogen atoms were located in the electron density map
and refined without positional constraints with isotropic
displacement parameters. The excellent quality of the struc-
ture model allows us to use the bond parameters as reference
values.
Ack n ow led gm en t. We thank the Consiglio Nazio-
nale delle Ricerche, the MURST (Programmi di Ricerca
Scientifica di Rilevante Interesse Nazionale, Cofinan-
ziamento 2000-2001), the University of Bologna, and
the Centro Interdipartimentale di Metodologie Chimico-
Fisiche, Universita` di Napoli ”Federico II”, for NMR
facilities.
Su p p or tin g In for m a tion Ava ila ble: Tables giving el-
emental analyses for representative new complexes and X-ray
crystallographic data for 2c(SMe), 3c(SMe2), and diphenyl
fumarate; these latter data are also available in CIF format.
This material is available free of charge via the Internet at
http://pubs.acs.org.
The structure of [Pt(SMe2)2(dmphen)(diphenyl fumarate)]-
[BF4]2 was solved without difficulties in the space group P21/
n, and both [BF4]- anions exhibited double images of the
OM020807V