Convenient synthesis of cationic allylplatinum(II) complexes with tertiary phosphines by oxidative allyl transfer from ammonium cations to platinum(0) substrates. Crystal and molecular structures of η3-propenyl- and η3-2-methylpropenyl-bis(triphenylphosphine)platinum(II)perchlorates

Article abstract of DOI:10.1016/S0022-328X(00)00251-5

A large variety of cationic η³-allylplatinum(II) complexes of the type [Pt(η³-CH₂C(R)C(R′)(R″)(PPh₃)₂]⁺ (1a-f) are prepared in high yield by oxidative allyl transfer from the ammonium cations [NEt₃CH₂C(R)=C(R′)(R″]⁺ to [Pt(η²-C₂H₄)(PPh₃)₂]. A similar reaction of [NEt₃CH₂C(R)=C(R′)₂]⁺ with [Pt(cod)₂] yields the related complexes [Pt(η³-CH₂C(R)C(R′)₂(cod)]⁺ (2a-c), indicating a rather general feasibility of such synthetic route. The 1,5-cyclooctadiene ligand of complexes 2a,c can be easily displaced by mono- and bidentate tertiary phosphines. The solution behaviour of the cationic η³-allyl platinum(II) complexes has been studied by multinuclear NMR spectroscopy. The solid state structures of the complexes [Pt(η³-CH₂CHCH₂)(PPh₃)₂]⁺ (1a) and [Pt(η³-CH₂C(Me)CH₂)(PPh₃)₂]⁺ (1b) have been determined by X-ray analyses. In 1b, the 2-methylpropenyl ligand is symmetrically η³-bound to platinum and assumes a unique orientation relative to the average coordination plane. In 1a, however, the propenyl ligand is disordered in two opposite orientations with occupation factors of 0.65 and 0.35. In the orientation with 0.65 occupation factor, the allyl ligand is symmetrically η³-bound to the metal, whereas, in the opposite orientation the C-C bond distances within the allyl group are considerably different [1.46(4) and 1.23(4) A?] with the three allyl carbon atoms being at roughly equal distances from platinum. Even though the C₃H₅ group is affected by large anisotropic thermal motion, the observed asymmetry may also arise from a prevailing η¹, η² coordination of the ligand in the solid.

Full text of DOI:10.1016/S0022-328X(00)00251-5

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 605 (2605) 28–38
Convenient synthesis of cationic allylplatinum(II) complexes with
tertiary phosphines by oxidative allyl transfer from ammonium
cations to platinum(0) substrates. Crystal and molecular structures
of h3-propenyl- and h3-2-methylpropenyl-bis-
(triphenylphosphine)platinum(II)perchlorates
Bruno Crociani a, Franco Benetollo b, Roberta Bertani c,d,*, Gabriella Bombieri e,
Fiorella Meneghetti c, Livio Zanotto d
a Dipartimento di Scienze e Tecnologie Chimiche, Via della Ricerca Scientifica, Uni6ersita` di Roma ‘Tor Vergata’, 00133 Rome, Italy
b I.C.T.I.M.A., C.N.R., Padua, Italy
c Dipartimento dei Processi Chimici dell’Ingegneria, Facolta` di Ingegneria, Uni6ersita` di Pado6a, Via F. Marzolo 9, 35131 Padua, Italy
d Centro di Studio per la Chimica e la Tecnologia dei Composti Metallorganici degli Elementi di Transizione del C.N.R., Via F. Marzolo 9,
35131 Padua, Italy
e Istituto di Chimica Farmaceutica, Uni6ersita` di Milano, Viale Abruzzi 42, I-20131 Milan, Italy
Received 15 February 2000; received in revised form 13 April 2000
Abstract
A large variety of cationic h3-allylplatinum(II) complexes of the type [Pt(h3-CH2C(R)C(R%)(R¦)(PPh3)2]+ (1a–f) are prepared
in high yield by oxidative allyl transfer from the ammonium cations [NEt3CH2C(R)ꢀC(R%)(R¦]+ to [Pt(h2-C2H4)(PPh3)2]. A
similar reaction of [NEt3CH2C(R)ꢀC(R%)2]+ with [Pt(cod)2] yields the related complexes [Pt(h3-CH2C(R)C(R%)2(cod)]+ (2a–c),
indicating a rather general feasibility of such synthetic route. The 1,5-cyclooctadiene ligand of complexes 2a,c can be easily
displaced by mono- and bidentate tertiary phosphines. The solution behaviour of the cationic h3-allyl platinum(II) complexes has
been studied by multinuclear NMR spectroscopy. The solid state structures of the complexes [Pt(h3-CH2CHCH2)(PPh3)2]+ (1a)
and [Pt(h3-CH2C(Me)CH2)(PPh3)2]+ (1b) have been determined by X-ray analyses. In 1b, the 2-methylpropenyl ligand is
symmetrically h3-bound to platinum and assumes a unique orientation relative to the average coordination plane. In 1a, however,
the propenyl ligand is disordered in two opposite orientations with occupation factors of 0.65 and 0.35. In the orientation with
0.65 occupation factor, the allyl ligand is symmetrically h3-bound to the metal, whereas, in the opposite orientation the C–C bond
,
distances within the allyl group are considerably different [1.46(4) and 1.23(4) A] with the three allyl carbon atoms being at
roughly equal distances from platinum. Even though the C3H5 group is affected by large anisotropic thermal motion, the observed
asymmetry may also arise from a prevailing h1, h2 coordination of the ligand in the solid. © 2000 Elsevier Science S.A. All rights
reserved.
Keywords: Synthesis; Platinum; Allyl complexes; X-ray structures
1. Introduction
The cationic complexes [Pt(h3-all)L2]+ [all=allylic
ligand; L=PPh3; L2=1,5-cyclooctadiene (cod)] have
generally been prepared through oxidative addition of
* Corresponding author. Tel.: +39-049-827 5731; fax: +39-049-
827 5525.
allyl halides[1] or acetates[2] to [Pt(PPh3)3] or [Pt(cod)2],
E-mail address: bertani@ux1.unipd.it (R. Bertani).
0022-328X/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0022-328X(00)00251-5

B. Crociani et al. / Journal of Organometallic Chemistry 605 (2000) 28–38
29
followed by exchange of the halide or acetate with the
2.2. Synthesis of triethylallylammonium salts (a–f)
poorly coordinating BF−4 or ClO4− anions.
In an early report, it was shown that the platinum(0)
To a solution of NaClO4 (6.11 g, 50.0 mmol) or
NaBF4 (5.49 g, 50.0 mmol) in acetone (50 ml) were
added NEt3 (1.70 ml, 12.0 mmol) and then the allylbro-
mide (11.0 mmol). The reaction mixture was stirred at
room temperature (r.t.) overnight and then concen-
trated to dryness in vacuo. CH2Cl2 (25 ml) was added
to the solid and, after filtration, the solution was con-
centrated at reduced pressure. Addition of Et2O gave
the salt as a white solid, or pale yellow oil (d), which
was filtered and dried under vacuum. This procedure
was used to prepare the compounds described below.
substrates,
such
as
[Pt(PPh3)3]
and
[Pt(h2-
C2H4)(PPh3)2], yield the derivatives [Pt(h3-all)L2]+
upon treatment with allyl ammonium cations [3]. Such
a reaction, involving an oxidative allyl transfer, has also
been used to prepare cationic h3-allylpalladium(II)
complexes containing monodentate phosphine and
phosphite ligands [4] or bidentate ligands, such as 1,2-
bis(diphenylphosphino)ethane [5] or a-diimines [6]. Fur-
thermore, the same type of reaction has been exploited
for selective desallylation of allyl amines catalyzed by
palladium(0) compounds [7]. On the other hand, h3-al-
lylplatinum(II) complexes have also been obtained in
redox transmetalation reactions involving an allyl
group transfer from palladium(II) to platinum(0) com-
pounds [8].
2.2.1. [NEt3CH2CHꢀCH2]ClO4 (a)
1
Yield: 96%. H-NMR: 5.95–5.66 ( m, 3H), 3.89 (d,
J
J
HH=6.6 Hz, 2H), 3.33 (q, JHH=7.3 Hz, 6H), 1.35 (t,
HH=7.3 Hz, 9H); m.p. 235°C (dec.). Anal. Calc. for
The principal object of the present work was to
extend this synthetic approach using variously substi-
tuted allyl ammonium cations to show the general
feasibility of this method. In addition, starting from
[Pt(cod)2], the allyl transfer reaction affords an easy
route for the preparation of h3-allylplatinum(II) com-
plexes containing mono- and bidentate ancillary lig-
ands, through displacement of the weakly bound
1,5-cyclooctadiene.
C9H20ClNO4: C, 44.72; H, 8.34; N, 5.79. Found: C,
45.1; H, 8.5; N, 5.5%.
2.2.2. [NEt3CH2C(Me)ꢀCH2]ClO4 (b)
1
Yield: 96%. H-NMR: 5.52 (bs, 1H), 5.36 (s, 1H),
3.83 (bs, 2H), 3.34 (q, JHH=7.3 Hz, 6H), 2.00 (bs, 3H),
1.38 (t, JHH=7.3, 9H); m.p. 67–69°C. Anal. Calc. for
C10H22ClNO4: C, 46.96; H, 8.67; N, 5.48. Found: C,
47.1; H, 8.3; N, 5.3%.
2. Experimental
2.2.3. [NEt3CH2CHꢀCMe2]ClO4 (c)
1
Yield: 94%. H-NMR: 5.21 (bt, JHH=7.7 Hz, 1H),
Safety note. Caution! Perchlorate salts are potentially
explosive. Only small amounts of these materials should
be prepared, and they should be handled with great
caution.
3.77 (d, JHH=7.7 Hz, 2H), 3.26 (q, JHH=7.3 Hz, 6H),
1.84 (s, 3H), 1.77 (bs, 3H), 1.32 (t, JHH=7.3 Hz, 9H);
m.p. 111–113°C. Anal. Calc. for C11H24ClNO4: C,
48.98; H, 8.97; N, 5.19. Found: C, 50.2; H, 9.3; N,
5.0%.
2.1. General
1H-, 13C-, and 31P-NMR spectra were recorded at
200.133, 50.323, and 81.015 MHz, respectively, in
CDCl3, with a Bruker AC 200 spectrometer. Infrared
spectra were recorded on a Perkin–Elmer 983 spec-
trometer. Melting points were measured on samples in
unsealed capillary tubes and are uncorrected. Elemental
analyses were carried out by the department of Analyt-
ical Chemistry of the University of Padua.
2.2.4. trans-[NEt3CH2CH=CHMe]BF4 (d)
Yield: 98%. H-NMR: 6.13 (dq, JHH=15.2, 6.5 Hz,
1H), 5.46 (dtq, JHH=15.2, 7.5, 1.7 Hz, 1H), 3.76 (d,
1
J
HH=7.5 Hz, 2H), 3.24 (q, JHH=7.3 Hz, 6H), 1.78
(dd, JHH=6.5, 1.7 Hz, 3H), 1.30 (t, JHH=7.3 Hz, 9H);
m.p. 83–86°C. Anal. Calc. for C10H22BF4N: C, 49.41;
H, 9.12; N, 5.76. Found: C, 50.2; H, 9.4; N, 5.9%.
THF, diethyl ether and toluene were dried over
sodium, in the presence of benzophenone, and distilled
under nitrogen. CH2Cl2 was dried over calcium hydride
and freshly distilled under nitrogen. All other reagents
were purchased from commercial suppliers and used as
received. All manipulations were carried out under dry
2.2.5. trans-[NEt3CH2CHꢀCHEt]BF4 (e)
This compound is a pale yellow viscous oil obtained
1
in 88% yield. H-NMR: 6.02 (dt, JHH=11.0, 7.6 Hz,
1H), 5.42 (dtt, JHH=11.0, 7.5, 1.5 Hz, 1H), 3.88 (d,
J
HH=7.5 Hz, 2H), 3.33 (q, JHH=7.2 Hz, 6H), 2.19
nitrogen
techniques.
atmosphere
using
standard
Schlenk
(dqd, JHH=7.6, 7.6, 1.5 Hz, 2H), 1.35 (t, JHH=7.2 Hz,
9H), 1.03 (t, JHH=7.6 Hz, 3H). Anal. Calc. for
C11H24BF4N: C, 51.38; H, 9.41; N, 5.45. Found: C,
50.3; H, 9.1; N, 5.2%.
[Pt(PPh3)2(C2H4)] [9] and [Pt(cod)2] [10] were synthe-
sized according to a previously described procedures.

30
B. Crociani et al. / Journal of Organometallic Chemistry 605 (2000) 28–38
1
2.2.6. trans-[NEt3CH2CHꢀCHPh]BF4 (f)
Selected H-, 31P-{1H}- and 13C-{1H}-NMR data of
1
Yield: 96%. H-NMR: 6.99 (d, JHH=15.7 Hz, 1H),
complexes 1a–f(X) are reported in Tables 1 and 2.
6.16 (dt, JHH=15.7, 7.5 Hz, 1H), 4.07 (d, JHH=7.5 Hz,
2H), 3.33 (q, JHH=7.2 Hz, 6H), 1.36 (t, JHH=7.2 Hz,
9H); m.p. 103–105°C. Anal. Calc. for C15H24BF4N: C,
59.04; H, 7.93; N, 4.59. Found: C, 57.6; H, 7.5; N,
4.2%.
2.4. Synthesis of the cationic complexes
[Pt(p3-CH2C(R)C(R%)2)(cod)]+ (2a–c)
Complexes 2a–c(ClO4) were prepared according
to the procedure described below for 2a(ClO4). To
2.3. Synthesis of the cationic complexes
[Pt(p3-CH2C(R)C(R%)(R¦)(PPh3)2]+ (1a–f)
a
stirred suspension of allylammonium salt
[NEt3CH2CHꢀCH2]ClO4 (0.121 g, 0.50 mmol) in THF
(50 ml), solid Pt(cod)2 (0.206 g, 0.50 mmol) was added
in one portion, and after a few minutes an off-white
solid began to precipitate. The reaction mixture was
kept aside for 2 h, and then reduced to small volume.
The product was filtered off, washed with THF (3×3
ml) and dried under vacuum. Yield: 0.187 g, 84%; m.p.
172–175°C (dec.). Anal. Calc. for C11H17ClO4Pt: C,
29.77; H, 3.86. Found: C, 28.4; H, 3.6%.
Unless otherwise mentioned, the allylplatinum com-
plexes 1a–f(X) (X−=ClO4−, BF−4 ) were prepared ac-
cording to the procedure outlined below for 1a(ClO4).
To a solution of [Pt(PPh3)2(C2H4)] (0.187 g, 0.25
mmol) in THF (30 ml), solid [NEt3CH2ꢀCHCH2]ClO4
(0.060 g, 0.25 mmol) was added in one portion, and the
reaction mixture stirred at r.t. for 4 h. The white solid
formed was filtered off, washed with THF and dried
under vacuum. Yield: 0.122 g, 57%. A second fraction
was obtained by reducing the mother liquor to a small
volume, and adding Et2O. Total yield 82%; m.p. 247°C
(dec.). Anal. Calc. for C39H35ClO4P2Pt: C, 54.46; H,
4.10. Found: C, 53.7; H, 4.0%.
2.4.1. 2b(ClO4)
Yield 80%; m.p. 209–212°C. Anal. Calc. for
C12H19ClO4Pt: C, 31.48; H, 4.18. Found: C, 30.2; H,
4.0%.
2.4.2. 2c(ClO4)
Yield 79%; m.p. 185–189°C (dec.). Anal. Calc. for
C13H21ClO4Pt: C, 33.09; H, 4.49. Found: C, 32.5; H,
4.2%.
2.3.1. 1b(ClO4)
Yield 97%; m.p. 267–269°C (dec.). Anal. Calc. for
C40H37ClO4P2Pt: C, 54.96; H, 4.27. Found: 53.3; H,
4.1%.
1
Selected H- and 13C-{1H}-NMR data of complexes
2a–c(ClO4) are reported in Tables 1 and 2.
2.3.2. 1c(ClO4)
2.5. Synthesis of the cationic complexes
[Pt(p3-CH2CHC(R)2)(L2)]+ (3a and 3c)
The reaction mixture was stirred for 24 h; yield: 87%;
m.p. 199–201°C (dec.). Anal. Calc. for C41H39ClO4-
P2Pt: C, 55.44; H, 4.43. Found: C, 55.0; H, 4.2%. This
complex was also prepared by adding PPh3 (0.106 g,
0.40 mmol) to a solution of complex 2c(ClO4) (0.095 g,
0.20 mmol) in CH2Cl2 (20 ml). The resulting solution
was stirred for 6 h and then concentrated at reduced
pressure. Addition of diethyl ether gave a white solid
which was filtered, washed with Et2O and dried under
vacuum. Yield: 0.149 g, 84%.
Complexes 3a(ClO4) and 3c(ClO4) were prepared by
cod displacement from the parent compounds 2a(ClO4)
and 2c(ClO4) according to the following procedure. To
a stirred suspension of [Pt(h3-CH2CHC(R)2)(cod)]ClO4
(0.25 mmol) in THF (25 ml), a solution of diphos
[1,2-bis(diphenylphosphino)ethane] (0.100 g, 0.25
mmol) in THF (10 ml) was added dropwise at r.t. The
resulting solution was further stirred for 1 h and then
concentrated. Addition of n-pentane gave an oily
product which was decanted and dried under vacuum.
Repetition of operations succeeded in obtaining the
solid complexes 3a(ClO4) and 3c(ClO4).
2.3.3. 1d(BF4)
Yield 88%; m.p. 241–243°C (dec.). Anal. Calc. for
C40H37BF4P2Pt: C, 55.77; H, 4.33. Found: C, 55.1; H,
4.0%.
2.3.4. 1e(BF4)
2.5.1. 3a(ClO4)
Yield: 71%. Anal. Calc. for C29H29ClO4P2Pt: C,
47.45; H, 3.98. Found: C, 46.8; H, 3.7%.
The reaction mixture was refluxed at 66°C for 24 h;
yield: 90%; m.p. 242–243°C (dec.). Anal. Calc. for
C41H39BF4P2Pt: C, 56.25; H, 4.49. Found: C, 55.2; H,
4.2%.
2.5.2. 3c(ClO4)
Yield: 87%. Anal. Calc. for C31H33ClO4P2Pt: C,
2.3.5. 1f(BF4)
48.86; H, 4.36. Found: C, 48.1; H, 4.2%.
1
The reaction mixture was stirred for 24 h; yield: 88%;
m.p. 194–196°C (dec.). Anal. Calc. for C45H39BF4P2Pt:
C, 58.52; H, 4.26. Found: C, 57.6; H, 4.0%.
Selected H-, 31P-{1H}- and 13C-{1H}-NMR data of
complexes 3a(ClO4) and 3c(ClO4) are reported in
Tables 1 and 2.

Table 1
Selected 1H-NMR data a
Compound Allyl protons
H3s
Others
H3a
R
Rs%yn
Ra¦nti
1a(ClO4)
3.73 d, (5.8) b
3.01 dd, (12.6) b, (7.8) c,
(38.6) d
5.52 m
3.73 d, (5.8) b
3.01 dd, (12.6) b, (7.8) c,
(38.6) d
1b(ClO4)
1c(ClO4)
1d(BF4)
syn
3.41 s
3.47 m
3.24 d, (8.3) c, (38.4) d
2.36 m
2.00 s, (63.8) d
5.37 m
3.41 s
3.24 d, (8.3) c, (38.4) d
1.18 dd, (4.6) c, (1.8) d
1.32 dd, (7.9) c, (3.4) d
3.26 m
4.00 m
2.92 m
2.59 m
5.31 m
5.54 m
1.23 m
4.44 m
3.86 m
1.03 m
/
anti
1e(BF4)
syn
anti
3.29 br
4.00 br
2.92 m, (37.5) d
2.49 m, (41.0) d
5.28 m
5.58 m
5.92 m
1.16 br; 0.76 t, (7.2) e
4.30 br
6.90-6.67 m
3.75 m, (50.0) d
1.36 br; 0.64 t, (7.2) e
4.86 dd, (13.2) b, (9.4) c,
(37.2) d
1f(BF4)
3.40 f
m
3.36 f
m
1,5-cyclopentadiene protons
CH
CH2
2.55 m br
2a(ClO4)
4.89 br
3.43 br
5.94 qt, (10.2) b, 4.89 br
(75.7) d
3.43 br
6.13 m br, (71.7) d
2b(ClO4)
2c(ClO4)
4.66 br
4.46 br
3.31 br, (29.3) d
3.34 br
2.01 s, (90.3) d
5.60 t, (10.7) b,
(75.7) d
4.66 br
3.31 br, (29.3) d
1.55 s, (5.4) d
6.11 m br, (68.5) d
6.24 m br, (73.1) d; 5.41 m br,
(67.0) d
2.62 m br
2.52 m br
2.23 s, (7.1) d
605
diphos CH2 protons
2.93–2.49 m
(
3a(ClO4)
3c(ClO4)
4.72 m
4.09 m
2.98 dd, (13.9) b, (8.7) c,
5.30 m, (48.3) d
5.15 m, (50.7) d
4.72 m
2.98 dd, (13.9) b, (8.7) c,
(44.6) d
(44.6) d
mk g
2.06 dd, (6.7) c, (4.6) c,
(9.3) d
0.94 s, (7.0) d
3.20–2.53 m
2
a In CDCl3, CHCl3 (l=7.26) as internal standard; coupling constant in Hz; d, doublet; dd, doublet of doublets; t, triplet; qt, quintet; m, multiplet; br, broad; mk, masked. The proton
numbering scheme is reported in Eqs. (1)–(3).
b J(HR).
c J(HP).
d J(HPt).
e J(HH).
f Partially overlapped resonances.
g Masked by diphos CH2 resonances.

Table 2
Selected 13C- and 31P-NMR data a
Compound Allyl carbons
Others
31P-NMR
C1
C2
C3
R
R%
R¦
/
1a(ClO4)
1b(ClO4)
1c(ClO4)
70.67 m b
70.08 m c
119.85 t, (18.1) d, 70.67 m
(2.6) e
16.14 s,
(3987.0) f
17.80 s,
(3862.1) f
19.80 d
130.71 s, (32.8) d 70.08 m
24.98 s, (33.0) d
105.98 d, (50.4) d, 110.72 t, (20.9) d, 59.03 d, (120.5) d,
(25.3) e (3.0) e (30.1) e
25.02 d, (2.5) e
21.87 d, (32.5) d,
(4.8) e
16.33 d,
(3952.8) f, (4074.3) f
(8.7) g , (8.7) g
1d(BF4)
syn
88.56 d, (42.3) d, 118.93 t, (24.2) d, 65.77 d, (107.9) d,
(26.8) e (3.1) e (28.5) e
16.57 d, (4.8) d,
(2.4) e
20.73 d, 17.37 d,
(3939.0) f, (4157.8) f
(9.0) g
, (9.0) g
anti
88.98 d, (31.4) d, 113.43 t, (29.2) d, 62.36 d, (95.1) d,
(27.0) e (2.8) e (29.6) e
15.34 d, (32.3) d,
(4.5) e
17.54 d, 16.30 d,
(4028.7) f, (3851.5) f
605
(10.7) g
, (10.7) g
1e(BF4)
(
syn
94.63 d, (46.0) d, 118.11 t, (16.2) d, 66.71 d, (105.5) d,
(26.7) e (3.2) e (27.7) e
25.05 d, (1.8) e;
17.44 d, (2.5) e
20.38 d, 17.12 d,
(3955.0) f, (4133.1) f
8
(9.4) g
, (9.4) g
anti
95.59 d, (40.8) d, 112.79 t, (16.2) d, 62.70 d, (115.5) d,
(26.9) e (2.7) e (30.5) e
23.93 d, (4.0) e;
17.30 d, (2.7) e
17.51 d, 16.27 d,
(4029.4) f, (3845.5) f
(10.7) g
, (10.7) g

Table 2 (Continued)
Compound Allyl carbons
C1
Others
31P-NMR
C2
C3
R
R%
R¦
1f(BF4)
91.54 d,
(26.3) e
113.19 s br
66.84 d, (27.4) e
19.43 d, 16.27 d,
(4011.0) f, (4191.7) f,
/
(11.4) g
(11.4) g
1,5-cyclooctadiene carbons
CH
103.87 m br
102.75 s
109.31 m br,
(126.0) d; 104.30 m
br, (105.5) d
CH2
30.79 s
30.86 s
30.67 br; 29.64 br
2a(ClO4)
2b(ClO4)
2c(ClO4)
68.71 s, (145.6) d 122.41 s, (46.7) d 68.71 s, (145.6) d
68.29 s, (152.6) d 140.26 s, (44.7) d 68.29 s, (152.6) d 25.76 s, (43.4) d
102.04 s, (131.9) d 114.28 s, (44.7) d 58.59 s, (193.3) d
26.40 s
26.76 s
22.37 s, (45.0) d
diphos carbons
28.88 dd, (52.5) d,
(40.7) e, (8.7) e
3a(ClO4)
3c(ClO4)
64.10 d,
119.03 s, (23.1) d 64.10 d, (83.1) d,
(29.1) e
47.85 s,
(83.1) d, (29.1) e
(3701.7) f
99.18 dd, (66.5) d, 111.74 t, (22.0) d, 54.05 d, (127.3) d,
21.42 d, (34.1) d, 30.71 dd, (49.4) d, 28.35 dd, (49.7) d, 46.79 d, 46.35 d,
605
(25.3) e, (2.4) e
(3.1) e
(30.2) e
(4.0) e
(38.5) e, (10.5) e
(38.9) e, (10.8) e
(3721.9) f, (3661.3) f,
(10.0) g (10.0) g
(
a In CDCl3;coupling constants in Hz; s, singlet; d, doublet; dd, doublet of doublets; t, triplet; m, multiplet; br, broad. The carbon numbering scheme is reported in Eqs. (1)–(3).
2
b X part of an AA%MX spin system (A,A%=31P; M=195Pt; see text); J(CP)=−30.7, J(CP%)=2.8, J(PP%)=9.0, J(CPt)=78.8 Hz.
c X part of an AA%MX spin system (A,A%=31P; M=195Pt; see text); J(CP)=−31.0, J(CP%)=2.8, J(PP%)=9.0, J(CPt)=86.8 Hz.
d J(CPt).
e J(CP).
f J(PPt).
g J(PP).

34
B. Crociani et al. / Journal of Organometallic Chemistry 605 (2000) 28–38
Table 3
introduced at calculated positions in their described ge-
ometries and during refinement were allowed to ride on
the attached carbon atoms with fixed isotropic thermal
parameters (1.2Uequiv of the parent carbon atom). For the
1b(ClO4) structure the Flack parameter [14] has been
refined. Calculations were performed with the SHELX-93
program [15], using the scattering factors inclosed
therein. The program for the ORTEP drawing was taken
from Ref. [16].
Experimental data for the crystallographic analyses
Compound
1a(ClO4)
1b(ClO4)
Formula
Molecular weight
Color
Crystal size (mm)
Crystal system
Space group
C39H35ClO4P2Pt
860.2
Colorless
0.42×0.48×0.36 0.34×0.44×0.32
Monoclinic
C2/c
25.525(5)
17.364(3)
17.931(3)
118.28(3)
6999(3)
8
C40H37ClO4P2Pt
874.2
Colorless
Monoclinic
Cc
,
a (A)
14.556(3)
14.856(3)
17.197(4)
94.83(3)
3706(1)
4
1.567
1736
3–28
,
b (A)
,
c (A)
3. Results and discussion
i (°)
3
,
V (A )
Platinum(0) complexes are known to react rapidly with
allyl halides in acetone or dichloromethane solution to
give the allylplatinum(II) derivatives [17]. Moreover they
behave like strong nucleophiles toward the allyl group
bonded to the quaternary nitrogen [3] from which a good
leaving group, such as the neutral amine, is released.
To enlarge the praticability of the latter reaction for
the synthesis of allylplatinum(II) complexes, the allylam-
monium salts a-f were prepared and reacted with
[Pt(PPh3)2(h2-C2H4)] in THF solution to afford the
cationic complexes 1a–f according to Eq. (1).
Z
Dcalc (g cm−3
F(000)
)
1.632
3408
3–26
q Range (°)
,
Radiation (u (A))
Mo–Ka (0.71073) Mo–Ka (0.71073)
42.2
293(2)
v (cm−1
T (K)
)
39.8
293(2)
5993
4408
0.039
0.078
1.19
No. of reflections collected 9037
No. of observed [I]3|(I)] 5097
R=ꢀꢁFoꢁ−ꢁFcꢁ/ꢀꢁFoꢁ
Rw (on F2)
GoF
0.045
0.106
1.19
(1)
The reaction time and temperature depend on the
substituents of the allylic precursors (see Section 2).
Complexes 1d(BF4) and 1e(BF4) were obtained as
mixtures of syn and anti isomers (4/1 and 3/2 molar
ratios, respectively), indicating that the syn geometry is
favoured by the less sterically demanding substituent
[18], whereas the allylic phenyl group in f leads to the
formation of the complex 1f(BF4) as a pure syn isomer
[18].
2.6. X-ray measurements and structure determination
Crystal data, collected reflections and parameters of
the final refinement for [Pt(h3-CH2CHCH2)(PPh3)2]-
ClO4, 1a(ClO4), and [Pt(h3-CH2C(Me)CH2)(PPh3)2]-
ClO4, 1b(ClO4), are reported in Table 3. Reflections were
collected using a Philips PW1100 diffractometer (Febo
System) [11] with graphite-monochromated (Mo–Ka) ra-
diation, following the standard procedures. There were
no significant fluctuations of intensities other than those
expected from Poisson statistics. All intensities were cor-
rected for Lorentz polarization and absorption [12]. The
positions of the heavy atoms were obtained from Patter-
son syntheses [13]. All non-H atoms were located in the
subsequent Fourier maps. Structures were refined by full-
matrix least-squares using anisotropic temperature fac-
tors for non-hydrogen atoms. Hydrogen atoms were
1
The H-NMR spectra (Table 1) show the presence of
static h3-allyl ligands in the cationic complexes 1a–f, as
reported for compounds [Pt(h3-allyl)(PR3)2]+X− where
X− is a non-coordinating anion (such as BF4−, PF−6 ,
ClO−4 or NO−3 ) [17,19]. In the 1H-NMR spectra, the allyl
anti protons always appear at higher field than the syn
protons, as they are nearer to the metal centre and hence
more strongly shielded.

B. Crociani et al. / Journal of Organometallic Chemistry 605 (2000) 28–38
35
The 31P-NMR spectra of 1a(ClO4) and 1b(ClO4)
(Table 2) are characterized by singlets, while in
1c(ClO4) and 1d–f(BF4) the asymmetric allyl group
gives rise to two doublets of an AB system flanked by
195Pt satellites.
nium compounds with platinum(0) complexes [3]. It
should be noted that the cationic complexes 1a and 1b
were already obtained following the later procedure.
In this paper we have shown that the above reaction
appears to be of general application for the synthesis of
cationic Pt(II) complexes containing variously substi-
tuted allyl ligands.
Our subsequent step was to explore the oxida-
tive allyl transfer process from ammonium cations
to bis(1,5-cyclooctadiene)platinum(0). By this way
we prepared complexes 2a–c(ClO4) according to Eq.
(2).
In Table 2, selected 13C-NMR data of allyl platinum
complexes are also reported. For our systems the as-
signment of the allyl carbon resonances is rather simple:
the central carbon C2 appears as a singlet (or triplet) at
lower field, the unsubstituted carbon C3 is always at
higher field, while the carbon C1 moves downfield by
introducing one or two substituents [20]. In complexes
(2)
The cationic compounds 2a and 2b were previously
prepared by halide abstraction with silver tetrafluorob-
orate or hexafluorophosphate either from h1-allylplat-
inum complexes [1] or, in the case of 2b, from the dimer
[Pt(h3-CH2C(Me)CH2)Cl]2 in the presence of cod [24].
It is clear, however, that our method is more feasible
and of more general applicability.
1a(ClO4) and 1b(ClO4), the terminal carbon resonances
of the h3-allyl ligand appear as a multiplet, which was
analysed as the X part of an AA%MX (A, A%=31P;
M=195Pt; X=13C) spin system [21]; the coupling con-
stants (Table 2) were refined using a G-NMR 4.0
program, the simulated spectra being in a good agree-
ment with the experimental ones.
The complexes 2a–c(ClO4) containing the modest
s-donor 1,5-cyclooctadiene ligand exhibit a dynamic
behaviour in solution.
Quite similar 13C-NMR patterns have been previ-
ously observed for the olefin carbons in complexes of
the type [Pt(h2-ol)(PPh3)2] (ol=diethyl fumarate or
maleate) [22].
1
Examination of the H- and 13C-NMR spectra (Ta-
bles 1 and 2) shows that the allyl group undergoes an
h3-h1-h3 interconversion at r.t. For the cationic com-
plexes 2a and 2b such interconversion involves breaking
of a Pt–C bond, which can occur at either the two ends
of the symmetric allyl ligand, whereas in 2c the break-
ing occurs selectively at the substituted carbon atom [1].
While the dynamic behaviour of the cationic complexes
2a and 2b have been already discussed in detail [1], we
like to describe here the NMR data of 2c.
The magnetic non-equivalence of the 31P nuclei in the
cis-Pt(PPh3)2 unit, may be ascribed to a slow rotation,
on the 13C-NMR time scale, of the PPh3 ligands around
the Pt–P bonds, caused by steric interactions as early
proposed for the complex [Pt(h3-CH2CHCH2)-
(PCy3)2]PF6 [19c].
This interpretation is also supported by the 13C-
NMR spectrum of [Pt(h3-CH2CHCH2)(diphos)]+ (3a)
where the terminal allyl carbons appear as a simple
doublet at 64.10 ppm, flanked by 195Pt satellites, indi-
cating the presence of magnetically equivalent 31P nu-
At 253 K, in CDCl3, the h3-h1-h3 process is frozen
out allowing analysis of the 1H-NMR spectrum. In fact,
all the allylic proton resonances appear as doublets of
doublets: at 5.53 ppm (JHH=13.7 and 7.6, JHPt
=
clei. In this case, only
a
fast conformational
76.1Hz), 4.47 ppm (JHH=7.6 and 3.8 Hz), and 3.09
ppm (JHH=13.7 and 3.8, JHPt=42.3 Hz) for the cen-
tral, syn and anti protons, respectively.
On raising the temperature, the signals of syn and
anti protons progressively broaden, until at r.t. they
collaps completely, and the central proton appears as a
sharp triplet at 5.60 ppm (JHH=10.7, JHPt=75.7 Hz).
An approximate calculation gives a DG‡ of ca. 15.0 kcal
rearrangement of the five-membered Pt(diphos) ring
can take place, which generates an averaged plane of
symmetry, passing through the central allyl carbon and
perpendicular to the P–Pt–P coordination plane.
Cationic allyl complexes were previously prepared by
Kurosawa by reacting cationic platinum(II) hydrides
with allylic alcohols, diallyl ethers [19a], or with allylic
amines [23], and subsequently by reacting allylammo-

36
B. Crociani et al. / Journal of Organometallic Chemistry 605 (2000) 28–38
(3)
1
The H-NMR spectra of 3a,c(ClO4) shows that the
allyl ligands are rigid in solution at r.t., and the 31P-
NMR spectroscopy evidences a singlet for the symmet-
ric cationic complex 3a, and an AB system for 3c, both
with 195Pt satellites, as previously described for 1a and
1c.
It is noteworthy that complexes 3a,c(ClO4) could not
be achieved through reaction (1) being [Pt(h2-
C2H4)(diphos)] not stable [25], so that reaction (3)
appears to be a new and easy approach to perform the
synthesis of cationic allyl platinum complexes with
diphos and, possibly, with a variety of bidentate ligands.
Fig. 1. (a) Perspective view of the platinum coordination plane of
[Pt(h3-CH2CHCH2)(PPh3)2]+ (1a) showing the two orientations of
the allyl ligand. (b) Perspective view of the coordination plane of
[Pt(h3-CH2C(Me)CH2)(PPh3)2]+ (1b).
3.1. Structural characterization of complexes 1a(ClO4)
and 1b(ClO4)
The structures of 1a(ClO4) and 1b(ClO4) consist of
discrete cations and anions. A perspective view of the
platinum coordination plane is shown in Fig. 1a, b for
the cationic complexes 1a and 1b, respectively. An
ORTEP drawing of the cation [Pt(h3-CH2C(Me)CH2)-
(PPh3)2]+ is shown in Fig. 2.
Table 4
Selected bond lengths (A) and angles (°) for [Pt(PPh3)2(h3-
,
CH2CHCH2)]+ (1a) and [Pt(PPh3)2(h3-CH2C(CH3)CH2)]+ (1b)
1a
1b
Pt–P(1)
Pt–P(2)
Pt–C(37)
2.280(3)
2.287(2)
2.171(7)
2.17(1)
2.16(2)
2.20(1)
1.39(2)
1.46(4)
1.37(2)
1.24(4)
–
2.293(1)
2.311(2)
2.19(1)
2.21(1)
–
2.21(1)
1.41(2)
–
Pt–C(38A)
Pt–C(38B)
Pt–C(39)
C(37)–C(38A)
C(37)–C(38B)
C(38A)–C(39)
C(38B)–C(39)
C(38)–C(40)
Fig. 2. ORTEP drawing of the cationic complex 1b with the atom
numbering scheme.
1.43(2)
–
1.50(1)
P(1)–Pt–P(2)
P(1)–Pt–C(37)
P(1)–Pt–C(39)
P(2)–Pt–C(37)
100.85(8)
95.9(3)
163.8(3)
163.1(2)
94.7(3)
68.4(4)
126(1)
131(3)
–
103.92(7)
97.4(3)
164.6(3)
158.7(3)
91.5(3)
67.2(4)
118(1)
mol−1 for the whole process, evaluated on the basis of
the loss of the geminal HH coupling [21].
Complexes of the type [Pt(cod)(h3-allyl)]+ are good
starting materials for the synthesis of allyl compounds
bearing a wide variety of ancillary ligands. For example,
PPh3 or 1,2-bis(diphenylphosphino)ethane displace
quantitatively 1,5-cyclooctadiene leading to compounds
1(ClO4) or 3(ClO4), respectively.
P(2)–Pt–C(39)
C(37)–Pt–C(39)
C(37)–C(38A)–C(39)
C(37)–C(38B)–C(39)
C(37)–C(38)–C(40)
C(39)–C(38)–C(40)
–
120.3(9)
120.4(9)
–

B. Crociani et al. / Journal of Organometallic Chemistry 605 (2000) 28–38
37
Table 5
Selected bond lenghts(A) and angles (°) in the complexes [Pt(h -CH2CHCH2)(L2)]
3
+
,
a
b
Pt–P
Pt–Ct
Pt–Cc
Ct–Cc
Ct–Cc
Ct–Cc–Ct
P–Pt–P
c
L=PCy3
2.327(4), 2.335(3)
2.277(2), 2.279(3)
2.280(2), 2.287(2)
2.24(2), 2.24(2)
2.20(1), 2.22(1)
2.171(7), 2.20(1)
2.19(3), 2.16(5)
2.18(2), 2.14(3)
2.17(2), 2.16(2)
1.36(4), 1.39(5)
1.34(3), 1.39(3)
1.39(3), 1.46(4)
1.47(4), 1.44(6)
1.45(3), 1.40(3)
1.37(3), 1.23(4)
126(3), 126(4)
–
126(1), 131(1)
111.2(1)
95.4(1)
100.85(8)
d
L2=biphemp
e
L=PPh3
a Ct, terminal carbon in the allyl group.
b Cc, central carbon in the allyl group.
c Ref. [26].
d Ref. [27].
e Present work.
Selected bond lengths and angles for both complexes
are presented in Table 4.
The cationic complex 1a exhibits a distorted square-
planar configuration with C(37)–Pt–C(39) and P(1)–
Pt–P(2) angles of 68.4(4)° and 100.85(8)°, respectively,
,
and with the Pt atom lying out of 0.05 A from the P(1),
According to this picture, the allyl ligand of the
cationic complex 1a would exist in the solid state in the
orientation C(37)–C(38A)–C(39) with an h3-bonding
mode A, and in the orientation C(37)–C(38B)–C(39)
with a bonding mode much closer to B. This view is
indirectly supported by the unequal statistical distribu-
tion of the two orientations in the crystal.
P(2), C(37), C(39) plane. The central carbon atom of
the allyl ligand is disordered in two positions with an
occupation factor of 0.65 for C(38A) and 0.35 for
C(38B). In both orientations, the three allyl carbon
atoms are bonded to platinum at roughly equal dis-
tances. In the C(37)–C(38A)–C(39) unit the C–C bond
distances are of comparable values [1.39(2) and 1.37(2)
,
A], whereas in C(37)–C(38B)–C(39) unit the C–C
bond lengths are significantly different [1.46(4) and
The X-ray structural analysis of 1b shows the 2-
methylallyl ligand in a unique orientation relative to the
rest of the molecule (Figs. 1b and 2), as it was found (to
the best of our knowledge) in all the structures of the
,
1.24(4) A]. The C(37)–Pt–C(39) plane forms a dihedral
angle of 62(2)° with the C(37)–C(38A)–C(39) plane,
and of 58(2)° with the C(37)–C(38B)–C(39) plane. In
both cases, the allyl central atom is inclined away from
the metal. The coordination of the allyl moiety in two
opposite orientations appears to be a common feature
for cationic complexes with the unsubstituted p-allyl
ligand of the type [Pt(h3-CH2CHCH2)(L2)]+, as it has
been observed for L=PCy3 [26] and L2=bi-
phemp [biphemp=(6,6%-dimethyl-1,1%-biphenyl-diyl)bis-
(diphenylphosphine)] [27]. A comparison of some se-
lected bond distances and angles of the latter com-
pounds with those of 1a (Table 5) shows that: (i) the
Pt–P bonds and P–Pt–P angle decrease on going from
PCy3 to the less sterically demanding phosphines PPh3
and biphemp; (ii) in one of the two orientations, the
C–C bond lengths of the allyl ligand are considerably
2-substituted
allyl
derivatives
[Pt(h3-CH2C(R)-
CH2)(PPh3)2)]+ (R=NEt2 [29] and OH [28]). The coor-
dination around the central metal is distorted square-
planar with C(37)–Pt–C(39) and P(1)–Pt–P(2) angles
of 67.2(4)° and 103.92(7)°, respectively, and with the Pt
atom lying on the P(1), P(2), C(37), C(39) plane. The
2-methylallyl moiety is h3-bound to platinum, as indi-
cated by the almost equal Pt–C(37), Pt–C(38), Pt–
C(39) bond distances, and by the nearly identical
C(37)–C(38) and C(38)–C(39) bond lengths [1.41(2)
,
and 1.43(2) A, respectively]. The C(37)–Pt–C(39) and
the C(37)–C(38)–C(39) planes form a dihedral angle of
68.7(9)°, with the central carbon atom C(38) inclined
away from the metal. It is worth noting that the methyl
carbon atom C(40) is not coplanar with the other allyl
carbon atoms, but is bent towards the metal at a
,
different, the largest difference (ca. 0.2 A) being ob-
served for L=PPh3 (1a).
,
distance of 0.30(1) A from the C(37)–C(38)–C(39)
A comparable difference in the two allyl bond dis-
plane. A similar structural feature was previously ob-
served for palladium(II) derivatives containing the h3-2-
methylallyl ligand [30].
,
tances [1.41(3) and 1.21(3) A] was observed for the
cationic complexes [Pt(h3-CH2C(OH)CH2)(PPh3)2)]+,
and was ascribed to large anisotropic thermal motion
of the allyl ligand [28]. Although the high estimated
S.D. values make precise deductions difficult, the differ-
ence in the C–C bond lengths may alternatively arise
from a different bonding mode in which the limiting h1,
h2 structure B predominates:
In conclusion, the introduction of a 2-methyl sub-
stituent in the allyl group stabilizes only one orientation
of the ligand, which assumes an h3-bonding mode with
a decreased inclination of the allyl plane with respect to
the C(37)–Pt–C(39) plane.

38
B. Crociani et al. / Journal of Organometallic Chemistry 605 (2000) 28–38
Internal Report 1/93, Centro di Studio per la Strutturistica
4. Supplementary material
Diffrattometrica del CNR, Parma, 1993.
[12] A.C.T. North, D.C. Philips, F.S. Mathews, Acta Crystallogr.
Sect. A 24 (1968) 351.
[13] G.M. Sheldrick, SHELXS86, Acta Crystallogr. Sect. A 46 (1990)
467.
[14] H.D. Flack, Acta Crystallogr. Sect. A 39 (1983) 876.
[15] G.M. Sheldrick, SHELXL93, Program for the Refinement of
Crystal Structures, University of Go¨ttingen, Germany, 1993.
[16] C.K. Johnson, ORTEP II Report ORNL-5138, Oak Ridge Na-
tional Laboratory, TN, USA, 1976.
Crystallographic data (excluding structure factors)
for the structural analysis have been deposited with the
Cambridge Crystallographic Data Centre, CCDC no.
139489 for compound [Pt(h3-CH2CHCH2)(PPh3)2]·
ClO4, and CCDC no. 139490 for compound [Pt(h3-
CH2C(Me)CH2)(PPh3)2]·ClO4. Copies of this informa-
tion may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(Fax: +44-1223-336-033; e-mail: deposit@ccdc.cam.
ac.uk or www: http://www.ccdc.cam.ac.uk).
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