Nucleophilic attack of carbonyl-stabilized phosphorus ylides on neutral and cationic alkene platinum(II) complexes

Article abstract of DOI:10.1021/om020970q

The carbonyl-stabilized phosphorus ylides Ph₃P=CHCO₂R (R = Me, Et) react with the platinum complexes [PtCl(η²-CH₂=CH₂)(N,N,N′,N′-tet ramethylethylenediamine)]ClO₄ and [PtCl₂(η

Full text of DOI:10.1021/om020970q

Organometallics 2003, 22, 1843-1848
1843
Nu cleop h ilic Atta ck of Ca r bon yl-Sta bilized P h osp h or u s
Ylid es on Neu tr a l a n d Ca tion ic Alk en e P la tin u m (II)
Com p lexes
J ose´ Vicente,*,† Mar´ıa Teresa Chicote, and Calum MacBeath
Grupo de Quı´mica Organometa´lica, Departamento de Qu´ımica Inorga´nica, Facultad de
Quı´mica, Universidad de Murcia, Apartado 4021, E-30071 Murcia, Spain
Peter G. J ones*,‡
Institut fu¨r Anorganische und Analytische Chemie der Technischen Universita¨t, Postfach 3329,
38023 Braunschweig, Germany
Received November 26, 2002
The carbonyl-stabilized phosphorus ylides Ph3PdCHCO2R (R ) Me, Et) react with the
platinum complexes [PtCl(η2-CH2dCH2)(N,N,N′,N′-tetramethylethylenediamine)]ClO4 and
[PtCl2(η4-diene)] (diene ) 1,5-hexadiene (C6H10), dicyclopentadiene (C10H12), 4-vinylcyclohex-
1-ene (C8H12), norbornadiene (C7H8)) to give complexes resulting from nucleophilic attack of
the ylide at one of the olefinic carbons. The crystal structures of [PtCl2{η3-C6H10CH(PPh3)CO2-
Et}], [PtCl2{η3-C10H12CH(PPh3)CO2Me}]‚0.5CH2Cl2, and [PtCl2{η3-C8H12CH(PPh3)CO2Me}]‚
2CHCl3 are reported and indicate an exo attack in the case of the dicyclopentadiene complex
and anti-Markovnikov addition (attack at the CH2 group) in the other two complexes.
In tr od u ction
num(II) complexes containing N-bonded iminophospho-
rane and/or N-bonded â-iminophosphorus ylide ligands.6
These results could not be extended to [PtCl4(NCMe)2]
because reduction to [PtCl2(NCMe)2] was observed when
the ylide Ph3PdCHCO2Me was used.7
Although phosphorus ylides have been shown to
function as ligands with virtually every metal of the
periodic table,1 their use as nucleophiles toward coor-
dinated ligands has been scarcely examined. Thus, the
complexes [Fe(η5-Cp)(CO)(L)(η2-CH2dCH2] (L ) CO,
PPh3) react with Ph3PdCHR (R ) H,2 CO2Me,3 respec-
tively) to give [Fe(η5-Cp)(CO)(L){CH2CH2CHR(PPh3)}].
Similarly, the cluster [FeCo2(CO)9(µ3-η2-CdCH2)] reacts
with Ph3PdCHR (R ) H, CO2Et, C(O)Ph, SiMe3) to give
[FeCo2(CO)9{µ3-CCH2CHR(PPh3)}].4
Recently, we described8 the reactions of carbonyl-
stabilized phosphorus ylides with the complexes [MCl2-
(η4-cod)] (M ) Pt, Pd; cod ) 1,5-cyclooctadiene). Again,
instead of the expected [MCl2{CH(PR3)CO2R}2], com-
plexes were obtained resulting from the nucleophilic
attack of the ylide on the cod ligand. In this paper, we
extend this study to the reactivity of ylides Ph3Pd
CHCO2R (R ) Me, Et) toward other [PtCl2(η4-diene)]
complexes and toward the cationic complex [PtCl(η2-
CH2dCH2)(tmeda)]ClO4 (tmeda ) N,N,N′,N′-tetra-
methylethylenediamine). One of our objectives was to
study the regio- and stereoselectivity of these reactions,
and for this reason we chose complexes with different
diolefins such as 1,5-hexadiene, dicyclopentadiene, 4-vi-
nylcyclohex-1-ene, and norbornadiene.
We have reported5 that reactions of [PtCl2(NCPh)2]
with carbonyl-stabilized phosphorus ylides Ph3Pd
CHCO2R (R ) Me, Et) did not give the expected ylide
complexes [PtCl2{CH(PPh3)CO2R}2]. Instead, complexes
of the type [PtCl2{N(dPPh3)C(Ph)dCHCO2R}(NCPh)]
were obtained that contain an iminophosphorane ligand
resulting from the nucleophilic attack of the ylide on
one of the benzonitrile ligands. This opened further
research, leading to the synthesis of a range of plati-
The nucleophilic attack on alkenes coordinated to pla-
tinum(II) is very well documented,9-11 and nucleophiles
such as hydroxide, alkoxide,12-16 nitro,12 acetylaceto-
nate,12,17-19 ammonia and amines,19-27 ethyl acetoace-
† E-mail: jvs@um.es. WWW: http://www.scc.um.es/gi/gqo/.
‡ E-mail: p.jones@tu-bs.de.
(1) (a) Schmidbaur, H. Pure Appl. Chem. 1980, 52, 1057. (b) Belluco,
U.; Michelin, R. A.; Mozzon, M.; Bertani, R.; Facchin, G.; Zanotto, L.;
Pandolfo, L. J . Organomet. Chem. 1998, 557, 37. (c) Navarro, R.;
Urriolabeitia, E. P. J . Chem. Soc., Dalton Trans. 1999, 4111. (d)
J ohnson, A. V.; Kaska, W. C.; Starzewski, K. A. O.; Dixon, D. A. Ylides
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10.1021/om020970q CCC: $25.00 © 2003 American Chemical Society
Publication on Web 03/28/2003

1844 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
tate, diethyl malonate,17,19,28 carboxylate,13 azide,11,29
cyanate,29,30 cyclopentadienyl,31 1,8-bis(dimethylamino)-
naphthalene (Proton Sponge),32 and chloride33 have been
studied. Some of these processes have been of utility in
organic synthesis.33,34 In most cases, these reactions took
place in an exo fashion; i.e., the nucleophile directly
attacks at the coordinated double bond, giving com-
plexes in which it is anti with respect to the metal. The
endo mode is less common; it occurs when the coordina-
tion of the nucleophile precedes a migratory insertion
of the double bond into the M-nucleophile bond.31,35
Despite the great number of products obtained through
these nucleophilic additions and the different isomers
that can be obtained in some of these reactions (exo or
endo, Markovnikov or anti-Markovnikov), only two
crystal structures have been reported.20,30 Curiously,
they are derivatives of ethylene platinum complexes
which can only give one type of addition product. We
have reported the crystal structure of the complex that
we obtained in the reaction between [PtCl2(η4-cod)] and
Ph3PdCHCO2Me, showing that the attack of the ylide
on the cod took place in an exo fashion.8 In this paper
we report three crystal structures showing the mode of
attack of the ylides studied toward some other dienes.
Another objective of the present work was to check the
generality of the above-mentioned behavior. In view of
the facile coordination of ylides to platinum,36 we
thought it possible that in [PtCl2(η4-diene)] complexes,
other than [PtCl2(η4-cod)], coordination could be pre-
ferred to the direct nucleophilic attack on the alkene,
resulting, in this case, in complexes [PtCl2{CH(PR3)-
CO2R}2] or those resulting after an endo attack.
Exp er im en ta l Section
The IR spectra, elemental analyses, and melting point
determinations were carried out as described earlier.37 Unless
otherwise stated, the reactions were conducted at room tem-
perature without special precautions against moisture. Tech-
nical grade solvents were purified by standard procedures. The
1H and 31P{1H} NMR spectra were recorded with Varian Unity
300 or Bruker AC-200 spectrometers, and chemical shifts,
given in ppm, are referred to TMS (1H) or H3PO4 (31P{1H}).
[PtCl(C2H4)(tmeda)]ClO4 was prepared according to the lit-
erature procedure.38 The [PtCl2(diene)] complexes were pre-
pared via the displacement of benzonitrile ligands from
[PtCl2(NCPh)2] (thf, reflux, 5 h).14-16,39,40
Syn th esis of [P tCl{CH2CH2CH(P P h 3)CO2Me}(tm ed a )]-
ClO4 (1). The ylide Ph3PdCHCO2Me (0.067 g, 0.200 mmol)
was added to a rapidly stirred solution of [PtCl(η2-CH2dCH2)-
(tmeda)]ClO4 (0.100 g, 0.200 mmol; tmeda ) N,N,N′,N′-
tetramethylethylenediamine) in Me2CO (50 mL), and the
reaction mixture was stirred further for 24 h. The resulting
solution was concentrated to ca. 2 mL; addition of Et2O (25
mL) then gave a precipitate that was washed with Et2O to
give 1 as a white solid (0.124 g, 0.153 mmol). Yield: 77%. Mp:
151 °C. Anal. Calcd for C29H39Cl2N2O6PPt: C, 43.08; H, 4.86;
N, 3.46. Found: C, 43.42; H, 4.73; N, 3.75. 1H NMR (200 MHz,
CDCl3): δ 1.41-2.59 (m, 4 H, CH2CH2), 2.69 (s, 3 H, NMe),
2.73 (s, 3 H, NMe), 2.76 (s, 3 H, NMe), 2.85 (s, 3 H, NMe),
3.50 (s, 3 H, OMe), 4.89 (m, 1 H, CHP), 7.65-7.87 (m, 15 H,
Ph). 31P{1H} NMR (300 MHz, CDCl3): δ 24.08 (s). FAB MS
(m/z (%, abundance)): 709 (M+ - ClO4, 89), 363 (CH2CH2CH-
(PPh3)CO2Me, 100). IR (cm-1; ν(CO)): 1728.
Syn th esis of [P tCl2{η3-C6H10CH(P P h 3)CO2R}] (R ) Me
(2a), Et (2b)), [P tCl2{η3-C10H12CH(P P h 3)CO2Me}] (3), [P tCl2-
{η3-C8H12CH(P P h 3)CO2Me}] (4), a n d [P tCl2{η3-C7H8CH-
(P P h 3)CO2Me}] (5). To a rapidly stirred solution of the
appropriate [PtCl2(η4-diene)] complex (ca. 0.5 mmol) in 30 mL
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Attack of Ylides on Platinum(II) Complexes
Organometallics, Vol. 22, No. 9, 2003 1845
Ta ble 1. Cr ysta l Da ta for Com p ou n d s 2b,
of Me2CO (CH2Cl2 for 5) was added an equimolar amount of
the ylide Ph3PdCHCO2R. The reaction mixture was stirred
further for 24 h, during which time a white precipitate formed.
The resulting suspension was concentrated to ca. 2 mL,
whereupon the addition of Et2O (25 mL) completed the
precipitation of complexes 2-5 as white solids that were
washed with Et2O (2 × 5 mL) and suction-dried.
3‚0.5CH2Cl2, a n d 4‚2CHCl3
2b
3‚0.5CH2Cl2
4‚2CHCl3
formula
C
28H31Cl2-
O2PPt
C
31.5H32Cl3-
O2PPt
C
31H33Cl8-
O2PPt
cryst habit
cryst size (mm)
colorless
colorless
colorless
prism
prism
tablet
0.27 × 0.24 × 0.22 × 0.10 × 0.24 × 0.21 ×
2a . Yield: 78%. Mp: 194 °C. Anal. Calcd for C27H29Cl2O2-
PPt: C, 47.52; H, 4.28. Found: C, 47.54; H, 4.10. 1H NMR
(200 MHz, CDCl3): δ 0.8-3.2 (several m, 8 H, CH2CH(Pt)-
CH2CH2CH), 3.71 (s, 3 H, OMe), 3.86 (m, 1 H, dCH2), 4.5 (m,
1 H, CHP), 5.98 (m, 1 H, dCH2), 7.67-7.92 (m, 15 H, Ph). 31P-
{1H} NMR (200 MHz, CDCl3): δ 26.74 (s). IR (cm-1; ν(CO)):
1724.
0.19
monoclinic
P21/c
0.08
triclinic
P1h
0.14
monoclinic
Pn
12.1500(12)
8.8305(8)
16.9544(16)
90
106.744(3)
90
1741.9(3)
2
cryst syst
space group
a (Å)
9.6743 (8)
11.8139 (10)
23.728(2)
90
101.097(3)
90
2661.1(4)
4
1.738
11.7034(10)
12.2222(10)
12.6338(10)
110.224(3)
101.911(3)
113.268(3)
1429(2)
2
1.801
774.98
0.710 73
143(2)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
2b. Yield: 73%. Mp: 182 °C. Anal. Calcd for C28H31Cl2O2-
PPt: C, 48.28; H, 4.49. Found: C, 48.24; H, 4.33. 1H NMR
(300 MHz, CDCl3): δ 0.97 (t, 3 H, Me), 1.24-2.87 (several m,
8 H, CH2CH(Pt)CH2CH2CH), 3.83 (m, 1 H, dCH2), 3.94 (m, 2
H, CH2Me), 4.65 (m, 1 H, CHP), 6.11 (m, 1 H, dCH2), 7.68-
7.91 (m, 15 H, Ph). 31P{1H} NMR (300 MHz, CDCl3): 26.81
(s). IR (cm-1; ν(CO)): 1722.
3. Yield: 80%. Mp: 180 °C. Anal. Calcd for C31H31Cl2O2-
PPt: C, 50.83; H, 4.27. Found: C, 50.44; H, 4.33. 1H NMR
(200 MHz, CDCl3): δ 1.0-3.0 (several m, 10 H), 3.48 (s, 3 H,
OMe), 4.67 (m, 1 H, CHP), 4.86 (m, 1 H, dCH2), 5.83 (m, 1 H,
dCH2), 7.66-7.94 (m, 15H, Ph). 31P{1H} NMR (300 MHz,
CDCl3): δ 22.86 (s). IR (cm-1; ν(CO)): 1728.
4. Yield: 68%. Mp: 142 °C. Anal. Calcd for C29H31Cl2O2-
PPt: C, 49.16; H, 4.41. Found: C, 49.44; H, 4.30. 1H NMR
(300 MHz, CDCl3): δ 0.8-3.56, 3.60-5.60 (several m, 13 H),
3.57 (s, 3 H, OMe), 7.66-7.90 (m, 15 H, Ph). 31P{1H} NMR
(300 MHz, CDCl3): δ 26.88 (s). IR (cm-1; ν(CO)): 1728.
5. Yield: 66%. Mp: 194 °C. Anal. Calcd for C28H27Cl2O2-
PPt: C, 48.57; H, 3.93. Found: C, 48.23; H, 3.83. 1H NMR
(300 MHz, CDCl3): δ 1.35-3.40 (several m, 6 H), 3.48 (s, 3 H,
OMe), 3.98 (m, 1 H, dCH2), 4.7 (m, 1 H, CHP), 5.2 (m, 1 H,
dCH2), 7.4-7.9 (m, 15 H, Ph). 31P{1H} NMR (300 MHz, CD2-
Cl2): δ 24.42 (s). IR (cm-1; ν(CO)): 1730.
X-r a y Str u ctu r e Deter m in a tion s. Crystals of 2b, 3‚
0.5CH2Cl2, and 4‚2CHCl3 suitable for X-ray diffraction studies
were grown by the liquid diffusion method using CH2Cl2 (2b,
3) or chloroform (4) and Et2O. Data were collected on a Bruker
SMART 1000 CCD diffractometer fitted with a low-tempera-
ture device. Structures were solved with the heavy-atom
method and refined on F2 using the program SHELXL-97 (G.
M. Sheldrick, University of Go¨ttingen, Go¨ttingen, Germany).
Hydrogen atoms of the coordinated olefin groups were located
in difference syntheses and refined freely, but with C-H
distance restraints. Other hydrogens were included using a
riding model or rigid methyl groups. Special features of
refinement are as follows. For all structures, light-atom U
value components were restrained to be equal (command
DELU). For 3 and 4, the local ring geometry of phenyl groups
was also restrained (FLAT, SAME). Structure 4 was refined
as an enantiomeric twin. The solvent molecule in 3 is disor-
dered over an inversion center. The two solvent molecules in
4 are well ordered. Crystal data are presented in Table 1.
Fcalcd (Mg m-3
Mr
)
1.806
696.49
0.710 73
143(2)
947.23
0.710 73
143(2)
λ (Å)
T (K)
F(000)
1368
5.557
1.93-30.00
SADABS
21 762
7750
0.0253
0.949/0.740
762
5.274
1.87-30.00
SADABS
17 137
8247
0.0415
0.98/0.60
8247/104/
351
0.0289
0.0679
1.405
1.007
928
4.716
µ(Mo KR) (mm-1
θ range (deg)
abs cor
)
1.84-30.03
SADABS
20 811
10 020
0.0529
0.962/0.742
10 020/277/
398
no. of rflns coll
no. of indep rflns
Rint
transmissn
no. of data/restraints/ 7750/61/
params
315
0.0233
0.0523
2.321
R1 (I > 2σ(I))
0.0295
0.0523
1.112
wR2 (all rflns)
max ∆F (e Å-3
S(F2)
)
0.978
0.924
NCO-.29,30 There is only one exception: the reaction
with 1,8-bis(dimethylamino)naphthalene (Proton Sponge)
gives a product in which the CH2CH2PtCl(tmeda)
moiety has replaced the 4-proton of the nucleophile,
which is taken up by the amino groups.32 Therefore, in
contrast to the current work, most of the resulting
addition products were neutral complexes.
The complexes [PtCl2(η4-diene)] (diene ) 1,5-hexadi-
ene (C6H10), dicyclopentadiene (C10H12), 4-vinylcyclohex-
1-ene (C8H12), norbornadiene (C7H8)), reacted at room
temperature in acetone (or CH2Cl2 for [PtCl2(η4-C7H8)])
with equimolar amounts of phosphorus ylides Ph3Pd
CHCO2R to give the enyl complexes [PtCl2{η3-C6H10CH-
(PPh3)CO2R}] (R ) Me (2a ), Et (2b)), [PtCl2{η3-C10H12
-
CH(PPh3)CO2Me}] (3), [PtCl2{η3-C8H12CH(PPh3)CO2Me}]
(4), and [PtCl2{η3-C7H8CH(PPh3)CO2Me}] (5), as shown
in Scheme 1. Complexes 1-5 were obtained as white
powders after partial evaporation of the reaction solu-
tion and addition of Et2O. They are all stable both in
the solid state and in solution.
The nucleophilic attacks of some carbon and nitrogen
nucleophiles on [PtCl2(η4-diene)] complexes have been
reported. These studies include the reactivity of the
same [PtCl2(η4-diene)] complexes whose reactivity to-
ward ylides we have studied here. Thus, [PtCl2(η4-
dicyclopentadiene)] reacts with acetylacetone (Hacac) or
ethyl acetatoacetate (Heacac), in the presence of Na2-
CO3,19 or with Tl(â-diketonates)18 to give [PtX(η3-
C10H12X)] (X ) acac, eacac, â-diketonates) or with
diethyl malonate (Hdem) to give [PtCl(η3-C10H12X)]2 (X
) dem).19 Similarly, it reacts with methanol to give [Pt-
(µ-Cl)(η3-C10H12OMe)].14,16 Those complexes, studied by
NMR spectroscopy, were assigned a structure similar
to that shown for 3 in Scheme 1. The corresponding
Resu lts a n d Discu ssion
Syn th esis. The reaction in acetone of equimolar
amounts of the complex [PtCl(η2-CH2dCH2)(tmeda)]-
ClO4 (tmeda ) N,N,N′,N′-tetramethylethylenediamine)
and the ylide Ph3PdCHCO2Me gave the complex [PtCl-
{CH2CH2CH(PPh3)CO2Me}(tmeda)]ClO4 (1),) as shown
in Scheme 1. Previous studies of nucleophilic attack on
[PtCl(η2-CH2dCH2)(tmeda)]ClO4 have dealt mainly with
anionic nucleophiles such as acetylacetone, ethyl aceta-
toacetate, and diethyl malonate in the presence of
- 13
bases,17 OH-, RO-, MeCO2
,
NO2-, N3-, CN-,29 and

1846 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
Sch em e 1
F igu r e 1. Ellipsoid representation of 2b with 30% prob-
ability ellipsoids and the labeling scheme. Selected bond
lengths (Å) and angles (deg): Pt-C(1) ) 2.105(3), Pt-C(2)
) 2.114(3), Pt-C(5) ) 2.056(3), Pt-Cl(1) ) 2.4286(6), Pt-
Cl(2) ) 2.3241(7), P-C(7) ) 1.837(2), C(8)-O(1) ) 1.200-
(3); Cl(1)-Pt-Cl(2) ) 91.31(2), C(5)-Pt-Cl(2) ) 89.71(8),
C(1)-Pt-Cl(1) ) 88.87(9), C(2)-Pt-Cl(1) ) 93.56(8), C(5)-
Pt-C(1) ) 91.75(12), C(5)-Pt-C(2) ) 83.80(11).
F igu r e 2. Ellipsoid representation of 3‚0.5CH2Cl2 (solvent
omitted) with 50% probability ellipsoids and the labeling
scheme. Selected bond lengths (Å) and angles (deg): Pt-
C(1) ) 2.163(4), Pt-C(2) ) 2.119(3), Pt-C(9) ) 2.040(3),
Pt-Cl(1) ) 2.4575(8), Pt-Cl(2) ) 2.3230(8), P-C(11) )
1.843(3), C(12)-O(1) ) 1.201(4); Cl(1)-Pt-Cl(2) ) 90.30-
(3), C(1)-Pt-Cl(1) ) 85.95(10), C(2)-Pt-Cl(1) ) 97.84-
(10), C(9)-Pt-Cl(2) ) 88.12(9), C(9)-Pt-C(1) ) 95.85(14),
C(9)-Pt-C(2) ) 83.25(13).
norbornadiene complex led to metallic platinum with
these nucleophiles,19 while benzylamine (C7H7NH2) gave
the adduct [PtCl{η3-C10H12(NHC7H7)}]2, which was too
insoluble to allow the determination of its molecular
weight or its NMR spectrum.19 Ammonia and primary
or secondary aliphatic amines add to [PtCl2(η4-diene)],
diene being 1,5-hexadiene or 4-vinylcyclohex-1-ene, to
ligands in a mutually cis disposition. The greater Pt-
Cl bond distance trans to the σ-C donor ligands than to
the olefin (2b, 2.4286(6) vs 2.3241(7) Å; 3, 2.4575(8) vs
2.3230(8) Å; 4, 2.4307(12) vs 2.3434(12) Å) evidences the
greater trans influence of σ-C donor ligands as compared
to that of olefins. In addition to the previously existing
chiral centers (3, C(3), C(4), C(6), and C(7); 4, C(2)), the
exo attack of the ylide at one of the double bonds of the
diolefin ligands produces two (2b, C(5), C(7); 4, C(1),
C(9)) or three new chiral sites (3, C(9), C(10), C(11)).
While in 2b the carbon atom σ-bonded to platinum C(5)
and the methyne ylide carbon atom C(7) both display
the same S configuration, in 3 and 4 the homologous
atoms are of opposite configuration (3, C(9) is R and
C(11) is S; 4, C(1) is S and C(9) is R). In 3, the third
chiral carbon C(10) is, like C(11), of S configuration. The
give [PtCl2{η3-C10H12(NRR′)}] or [Pt(µ-Cl){η3-C10H12
-
(NRR′)}]2.24 However, no crystal structures of these
adducts were reported. The only precedents for com-
plexes related to 1-5 are those we prepared from [PtCl2-
(η4-cod)] and various carbonyl-stabilized phosphorus
ylides, one of which was characterized by X-ray crystal-
lography.8
X-r a y Cr ysta l Str u ctu r es of 2b, 3‚0.5CH2Cl2, a n d
4‚2CHCl3. The structures of complexes 2b (Figure 1),
3‚0.5CH2Cl2 (Figure 2), and 4‚2CHCl3 (Figure 3) show
them to be monomeric. The platinum atom is in a
distorted-square-planar environment, coordinated to an
alkyl carbon atom, an olefinic group, and two chloro

Attack of Ylides on Platinum(II) Complexes
Organometallics, Vol. 22, No. 9, 2003 1847
F igu r e 3. Ellipsoid representation of 4‚2CHCl3 with 50%
probability ellipsoids and the labeling scheme. Selected
bond lengths (Å) and angles (deg): Pt-C(1) ) 2.052(4), Pt-
C(4) ) 2.112(4), Pt-C(5) ) 2.106(5), Pt-Cl(1) ) 2.3434(12),
Pt-Cl(2) ) 2.4307(12), P-C(9) ) 1.831(4), C(10)-O(2) )
1.193(5); Cl(1)-Pt-Cl(2) ) 89.51(5), C(1)-Pt-Cl(1) )
92.31(12), C(4)-Pt-Cl(2) ) 93.99(12), C(5)-Pt-Cl(2) )
89.55(12), C(4)-Pt-C(1) ) 82.79(16), C(5)-Pt-C(1) )
90.36(16).
F igu r e 4. Packing diagram for 3‚0.5CH2Cl2 showing
hydrogen bonds. H atoms not involved in hydrogen bonding
have been omitted.
phosphorus-carbon bond lengths (2b, P-C(7) ) 1.837(2)
Å; 3, P-C(11) ) 1.843(3) Å; 4, P-C(9) ) 1.831(4) Å) are
in the range found in phosphonium salts, while the C-O
bond distances (2b, C(8)-O(1) ) 1.200(3) Å; 3, C(12)-
O(1) ) 1.201(4) Å; 4, C(10)-O(2) ) 1.193(5) Å) are
similar to the typical values found for C(sp2)dO in
esters.41
The structure of 3 reveals that the attack of the ylide
took place on the norbornene double bond of the fused
bicyclic ring system, as was observed with other nu-
cleophiles,14,16,18,19 and took place, as usual, in the exo
manner. The structures of 2b and 4 show the attack at
the ligands to occur at the CH2 group (anti-Markovni-
kov). In the case of platinum complexes with monosub-
stituted olefins, the addition occurs with a high degree
of regioselectivity according to Markovnikov’s rule.11,21-23
However, some studies on ammonia and amine addi-
tions to 1,5-hexadiene and 4-vinylcyclohexene complexes
of platinum have shown the addition to be anti-Mark-
ovnikov for amines and Markovnikov for ammonia.24
This suggests that steric rather than electronic effects
are important in determining the direction of the ylide
attack.
The packing diagram for 3‚0.5CH2Cl2 (Figure 4)
shows the four shortest H bonds from CH groups (one
to O(1) and three to Cl(2)), which link the molecules to
layers parallel to the xz plane. The view direction is
perpendicular to this plane. In 4, the chloroform mol-
ecules are hydrogen bonded to both chloro ligands
(H‚‚‚Cl ) 2.64-2.95 Å). The H‚‚‚Pt distances are also
relatively short (3.04, 3.18 Å), and one could thus argue
that these too have hydrogen-bonding character, thus
implying four-center hydrogen bonds as shown in Figure
5. However, we note that much shorter Pt‚‚‚H contacts
(2.48-2.75 Å) have been observed in other complexes
F igu r e 5. View of the hydrogen bond interactions in 4‚
2CHCl3.
containing a Cl3C-H‚‚‚Pt interaction.42,43 In the absence
of further evidence, the nature of the Pt‚‚‚H contacts
remains ambiguous. In the past few years an increasing
number of X-H‚‚‚M interactions have been reported44-48
which, along with other weak interactions, coopera-
tively49 contribute to the self-assembling of different
molecules.
NMR a n d IR Sp ectr a . With the exception of 1, all
complexes have more than one chiral center. Assuming
that the ylide attacks in an exo fashion, as happens in
the overwhelming majority of cases and is shown here
(42) Berenguer, J . R.; Fornies, J .; Gomez, J .; Lalinde, E.; Moreno,
M. T. Organometallics 2001, 20, 4847.
(43) Bruno, G.; Lanza, S.; Nicolo, F. Acta Crystallogr., Sect. C 1990,
46, 765.
(44) Braga, D.; Grepioni, F.; Tedesco, E.; Biradha, K.; Desiraju, G.
R. Organometallics 1997, 16, 1846.
(45) Crabtree, R. H.; Eisenstein, O.; Sini, G.; Peris, E. J . Organomet.
Chem. 1998, 567, 7.
(46) Canty, A. J .; Koten, G. V. Acc. Chem. Res. 1995, 28, 406.
(47) Mart´ın, A. J . Chem. Educ. 1999, 76, 578.
(48) Yao, W.; Eisenstein, O.; Crabtree, R. H. Inorg. Chim. Acta 1997,
254, 106.
(41) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 1 1987, S1.
(49) Prins, L. J .; Reinhoudt, D. N.; Timmerman, P. Angew. Chem.,
Int. Ed. 2001, 40, 2383.

1848 Organometallics, Vol. 22, No. 9, 2003
Vicente et al.
by the crystal structures of 2b, 3, and 4, two diastere-
oisomers of each complex may form upon attack of the
ylide, depending on the R or S configuration of the ylide
carbon atom. Indeed, both the 1H and the 31P{1H} NMR
spectra of all these complexes reveal the existence of
both diastereoisomers in solution, but one of them only
in very small quantities. This makes it difficult to assign
The 1H NMR spectrum of complex 1 displays four
singlets in the range 2.69-3.51 ppm, from the four
distinct methyl groups of the tetramethylenediamine
ligand, and four complex multiplets in the region 1.41-
2.59 ppm, which are assigned to the protons of the alkyl
group coordinated to platinum. In complexes 2-5, the
nonolefinic hydrogens of the enyl ligands give rise to a
series of complex, often overlapping multiplets, as we
observed in the spectra of the cyclooctenyl complexes
obtained previously.8
The IR spectra of complexes 1-5 show a strong
absorption in the 1722-1732 cm-1 region, assignable
to νassym(CO2), shifted to higher wavenumber with
respect to that in the corresponding free ylides (R ) Me,
1620 cm-1; R ) OEt, 1610 cm-1) and close to that in
the phosphonium salt (R ) Me, 1720 cm-1; R ) OEt,
1715 cm-1).
1
the H NMR resonances. The ratio between both dias-
tereoisomers is probably determined by steric effects.
Only the resonances due to the major species are
reported in the Experimental Section, but very small
resonances due to the methyl protons of the CO2R
fragment of the less abundant ones are observed at 3.46
(2a ), 1.24 (2b), 3.54 (3), 3.58 (4), and 3.56 ppm (5).
Similarly, in the 31P{1H} NMR spectra of complexes 2-5
resonances due to the minor species appear at 26.08
(2a ), 22.90 (2b), 26.84 (3), 25.22 (4), and 28.83 ppm (5).
Complexes 1-5 each display a multiplet due to the
ylidic CH proton in the range 4.5-4.89 ppm, as expected
for phosphonium salts. The CH proton in the free
phosphorus ylides Ph3PdCHCO2R gives rise to a broad
signal at 2.82 (R ) Me) or 2.85 ppm (R ) Et), while the
CH2 protons of the corresponding phosphonium chlo-
rides give doublets at 5.50 (R ) Me) and 5.40 ppm (R )
Et).8 The same is observed in the 31P{1H} NMR spectra.
The resonances of both diastereoisomers of complexes
1-5 (in the range 22.90-28.83 ppm) are also downfield
shifted with respect to that of the corresponding ylide
(R ) Me, 15.3 ppm; R ) Et, 17.9 ppm) or even to those
observed for the phosphonium chlorides [Ph3PCH2-
CO2R]Cl (R ) Me, 20.7 ppm; R ) Et, 21.1 ppm).8
Ack n ow led gm en t. We thank Ministerio de Ciencia
y Tecnolog´ıa, FEDER (Grant No. BQU2001-0133), and
the Fonds der Chemischen Industrie for financial sup-
port and the European Commission for the award of a
Marie Curie Fellowship to C.M. (Contract No. ERBFM-
BICT972115).
Su p p or tin g In for m a tion Ava ila ble: Listings of all re-
fined and calculated atomic coordinates, anisotropic thermal
parameters, and bond lengths and angles for 2b, 3‚0.5CH2-
Cl2, and 4‚2CHCl3. This material is available free of charge
via the Internet at http://pubs.acs.org.
OM020970Q