Addition reactions of η3-allenyl/propargyl and η3-trimethylenemethane complexes of platinum and palladium

Article abstract of DOI:10.1016/S0020-1693(02)01168-4

A study of reactions of η³-allenyl/propargyl complexes of platinum and palladium with transition-metal hydrides and secondary amines and of η³-trimethylenemethane (η³-TMM) complexes of platinum with unsaturated electrophiles is presented. The reaction of [(PPh₃)₂Pt(η³-CH₂CCPh)]OTf (1aOTf) with Cp(CO)₂RuH affords the η³-allyl complex [(PPh₃)₂Pt(η³-CH₂CHC(Ph)Ru (CO)₂Cp)]OTf, whereas that of 1aOTf with Cp₂Zr(Cl)H furnishes [(PPh₃)₂Pt(η³-CH₂CHCHPh)]OTf (3OTf). The source of the CHPh hydrogen in the latter reaction appears to be adventitious H₂O, as evidenced by the formation of [(PPh₃)₂Pt(η³-CH₂CHCDPh)]OTf when 1aOTf was treated with D₂O and Cp₂Zr(Cl)H. Possible mechanisms of formation of 3OTf are presented. The secondary amines R₂NH (R=i-Pr or sec-Bu) react with 1aOTs and its palladium analog, 1bOTs, to give the η³-(2-aminoallyl) complexes [(PPh₃)₂M(η³-CH₂C(NR ₂)CHPh)]OTs (M=Pt, Pd). Competition studies reveal the following order of reactivity, attributed to steric effects: Et₂NH (74 and 38)>(i-Pr)₂NH (3.5 and 5)>(sec-Bu)₂NH (1) for 1aOTs and 1bOTs, respectively. The complex 1aOTs reacts much faster with Et₂NH than with EtOH. Reactions of the η³-TMM complexes (PPh₃)₂Pt(η³-CH₂C(C(CO ₂Me)₂)CHR) (R=Me (7), Ph (8)) with the very strong electrophiles/polarophiles TCNE and p-toluenesulfonyl isocyanate (TSI) lead to [3+2] cycloaddition of the electrophile to the η³-TMM ligand, and the resulting cycloadduct is isolated either free (with TSI) or complexed as an alkene to the metal (with TCNE). The weaker electrophiles diethyl fumarate and fumaronitrile (E) react with 7 or 8 to furnish (PPh₃)₂PtE and a [3+3] coupling product of the η³-TMM ligand. All new compounds were characterized by a combination of elemental analysis, mass spectrometry and ¹H, ¹³C{¹H} and ³¹P{¹H} NMR spectroscopy.

Full text of DOI:10.1016/S0020-1693(02)01168-4

Inorganica Chimica Acta 342 (2003) 279ꢃ290
/
www.elsevier.com/locate/ica
Addition reactions of h3-allenyl/propargyl and h3-
trimethylenemethane complexes of platinum and palladium
R. Todd Dunsizer, Vera M. Marsico, Ve´ronique Plantevin, Andrew Wojcicki ꢀ
Department of Chemistry, The Ohio State University, 100 W. 18th Ave., Columbus, OH 43210-1185, USA
Received 2 May 2002; accepted 28 May 2002
Abstract
A study of reactions of h3-allenyl/propargyl complexes of platinum and palladium with transition-metal hydrides and secondary
amines and of h3-trimethylenemethane (h3-TMM) complexes of platinum with unsaturated electrophiles is presented. The reaction
of [(PPh3)2Pt(h3-CH2CCPh)]OTf (1aOTf) with Cp(CO)2RuH affords the h3-allyl complex [(PPh3)2Pt(h3-CH2CHC(Ph)Ru(CO)2-
Cp)]OTf, whereas that of 1aOTf with Cp2Zr(Cl)H furnishes [(PPh3)2Pt(h3-CH2CHCHPh)]OTf (3OTf). The source of the CHPh
hydrogen in the latter reaction appears to be adventitious H2O, as evidenced by the formation of [(PPh3)2Pt(h3-CH2CHCDPh)]OTf
when 1aOTf was treated with D2O and Cp2Zr(Cl)H. Possible mechanisms of formation of 3OTf are presented. The secondary
amines R2NH (Rꢁ
[(PPh3)2M(h3-CH2C(NR2)CHPh)]OTs (Mꢁ
steric effects: Et2NH (74 and 38)ꢀ(i-Pr)2NH (3.5 and 5)ꢀ
1aOTs reacts much faster with Et2NH than with EtOH. Reactions of the h3-TMM complexes (PPh3)2Pt(h3-CH2C(C(CO2-
Me)2)CHR) (RꢁMe (7), Ph (8)) with the very strong electrophiles/polarophiles TCNE and p-toluenesulfonyl isocyanate (TSI) lead
to [3ꢂ
2] cycloaddition of the electrophile to the h3-TMM ligand, and the resulting cycloadduct is isolated either free (with TSI) or
/
i-Pr or sec-Bu) react with 1aOTs and its palladium analog, 1bOTs, to give the h3-(2-aminoallyl) complexes
Pt, Pd). Competition studies reveal the following order of reactivity, attributed to
(sec-Bu)2NH (1) for 1aOTs and 1bOTs, respectively. The complex
/
/
/
/
/
complexed as an alkene to the metal (with TCNE). The weaker electrophiles diethyl fumarate and fumaronitrile (E) react with 7 or 8
to furnish (PPh3)2PtE and a [3ꢂ
/
3] coupling product of the h3-TMM ligand. All new compounds were characterized by a
combination of elemental analysis, mass spectrometry and H, 13C{1H} and 31P{1H} NMR spectroscopy.
1
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Platinum complexes; Palladium complexes; h3-Allenyl/propargyl; h3-Trimethylenemethane; Nucleophilic addition; Cycloaddition
1. Introduction
Cationic transition-metal h3-allenyl/propargyl com-
plexes react with a variety of nucleophilic reagents [1ꢃ6].
/
Generally, these reactions proceeded by addition of the
nucleophile to the central carbon atom of the hydro-
carbyl ligand as shown in Eq. (1), and a number of
oxygen, nitrogen and carbon nucleophiles NuH, in
particular, engage in such processes.
ð1Þ
We [1,5] and another group [2] have been investigating
addition reactions of nucleophiles with [(PPh3)2Pt(h3-
CH2CCR)]ꢂ (Rꢁ
H, Me, Ph) over the past several
/
years, and these studies have been recently reviewed. In
the present and the last paper in this series, we report
further studies of addition of amines to [(PPh3)2Pt(h3-
CH2CCPh)]ꢂ (1a) and [(PPh3)2Pd(h3-CH2CCPh)]ꢂ
ꢀ Corresponding author. Tel.: ꢂ
1685
E-mail address: wojcicki@chemistry.ohio-state.edu (A. Wojcicki).
/
1-614-292 4750; fax: ꢂ1-614-292
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 1 6 8 - 4

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R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ290
/
(1b) [7ꢃ
/
9], as well as new investigations on analogous
to room temperature (r.t.), in an adaptation of the
synthetic method for related complexes of platinum [9].
additions of transition-metal hydrido complexes to 1a.
Also included are cycloaddition reactions of the h3-
trimethylenemethane complexes [(PPh3)2Pt(h3-CH2C(C-
(CO2Me)2)CHR)] (RꢁMe (7), Ph (8)) with unsaturated
electrophilic reagents, which expand on our previously
published investigations [10].
2.3. Reactions of [(PPh3)2Pt(h3-CH2CCPh)]OTf
(1aOTf) with metal hydrido complexes
/
2.3.1. Reaction of 1aOTf with Cp(CO)2RuH
A solution of Cp(CO)2RuH in heptane, generated in
situ from Ru3(CO)12 (0.026 g, 0.041 mmol) and C5H6,
was added to a solution of 1aOTf (0.100 g, 0.102 mmol)
2. Experimental
in 10 ml of THF at ꢄ78 8, and the mixture was allowed
/
2.1. General procedures and measurements
to warm to r.t. over 3.5 h with stirring. The solvent was
removed under reduced pressure, and the solid residue
was recrystallized from 11 ml of 3/8 (by volume)
Reactions and manipulations of organoplatinum and
-palladium compounds were carried out under an
atmosphere of dry argon by use of standard procedures
[11]. Solvents were dried [12], distilled under argon and
degassed before use. Elemental analyses were performed
by Guelph Chemical Laboratories Ltd. of Canada and
CH2Cl2ꢃ
hexanes to afford [(PPh3)2Pt(h3-CH2CHC-
(Ph)Ru(CO)2Cp)]OTf (2OTf) as a pale yellow powder.
The yield was 0.090 g (73%). IR (CH2Cl2): n(CO) 2023
/
(s), 1966 (s) cmꢄ1 1H NMR (CDCl3): d 6.17 (dd,
.
3JHH(anti)
(s, 5H, Cp), 3.47 (br m, 2JHH
1H, syn-CHH), 2.26 (br t, 2JHH
Hz, JPH 10.0 Hz, JPtH 45 Hz, 1H, anti-CHH).
13C{1H} NMR (CDCl3): d 200.0 (s, JPtC
17.2 Hz,
CO), 199.5 (s, CO), 155.0 (s, ipso C of allyl Ph), 134ꢃ126
(m, Ph), 122.2 (m, JPC 3.5 Hz, JPtC 28.4 Hz, CH),
90.3 (s, Cp), 60.0 (d, JPC 30.4 Hz, JPtC 132 Hz, CH2)
(CPh signal was not observed). 31P{1H} NMR (CDC13):
d 20.6 (d, JPP 6.4 Hz, JPtP 3922 Hz), 16.4 (d, JPP
6.4 Hz, JPtP 4318 Hz). Anal. Found: C, 52.60; H, 3.73.
ꢁ
/
11.0 Hz, JHH(syn)
ꢁ
/
7.2 Hz, 1H, CH), 5.10
2 Hz, 3JHH(syn)
7.2 Hz,
2 Hz, 3JHH(anti)
11.0
3
M-H-W Laboratories, Phoenix, AZ. 1H, 2H, 13C and 31
P
B
/
ꢁ
/
NMR spectra were acquired on Bruker AM-250 and
AC-300 spectrometers, and IR spectra were obtained on
B
/
ꢁ
/
ꢁ
/
ꢁ
/
PerkinꢃElmer Model 283B and 1600 spectrophot-
/
ꢁ
/
ometers. Mass spectra (FAB and EI) were recorded on
a Kratos VG70-250S spectrometer by Mr. David C.
Chang.
/
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
/
2.2. Materials
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
/
Reagents were procured from various commercial
sources and used as received, except as noted below. The
amines diethylamine, diisopropylamine and di-sec-bu-
tylamine were purified by distillation from NaOH.
Absolute ethyl alcohol was distilled twice from
Mg(OEt)2. Tetracyanoethylene (TCNE) and fumaroni-
trile were sublimed under vacuum prior to reaction,
whereas p-toluenesulfonyl isocyanate (TSI) was distilled
from P4O10. Literature procedures were followed to
Calc. for C53H43F3O3P2PtRuS: C, 52.74; H, 3.59%.
2.3.2. Reaction of 1aOTf with Cp2Zr(Cl)H
A solution of 1aOTf (0.100 g, 0.102 mmol) in 10 ml of
THF at approximately ꢄ78 8C was added to a
suspension of Cp2Zr(Cl)H (0.025 g, 0.099 mmol) in 10
ml of THF also at ꢄ78 8C. The reaction was allowed to
warm to r.t. over 3 h with stirring and then was
concentrated under reduced pressure.
31P{1H}
/
/
synthesize the organic tosylates PhCÅ
MeCÅCCH2OTs (OTsꢁp-MeC6H4SO3) [13]. The me-
tal complexes (PPh3)2Pt(C2H4) [14], Pd2(dba)3×CHCl3
(dbaꢁ
dibenzylideneacetone) [15], [(PPh3)2Pt(h3-CH2C-
CPh)]OTf (1aOTf, OTfꢁCF3SO3) and -OTs (1aOTs)
[9], [(PPh3)2Pd(h3-CH2CCPh)]OTs (1b OTs) [9], [(P-
(6aOTs) [9].
/CCH2OTs and
A
/
/
NMR spectrum showed one major product, identified
as [(PPh3)2Pt(h3-CH2CHCHPh)]OTf (3OTf) (vide in-
fra); however, a ‘CpZr’ impurity was detected by H
NMR spectroscopy. This uncharacterized species could
be in part removed by filtration of the reaction mixture,
addition of hexanes to the filtrate and repeated crystal-
/
1
/
/
Ph3)2Pt(h3-CH2C(NEt2)CHPh)]OTs
[(PPh3)2Pd(h3-CH2C(NEt2)CHPh)]OTs (6bOTs) [9],
Cp(CO)2RuH [16], Cp(CO)2RuMe [17], Cp2ZrH2 [18]
and Cp2Zr(Cl)H [19] were prepared by published
methods. The complex Cp2Zr(Cl)H was washed with
CH2Cl2 to remove any Cp2ZrH2 or Cp2ZrCl2 [20]
immediately before use. Known (PPh3)Pt(h3-CH2-
C(C(CO2Me)2)CHPh) (8) [10] was obtained in 80%
yield by treatment of NaCH(CO2Me)2 in THF at
lization of the precipitated 3OTf from THFꢃ
/
hexanes.
The yield of 3OTf varied depending on the degree of
1
purity desired. H NMR (CDCl3): d 8.5ꢃ
/
6.5 (m, 35H,
11, 10.5 Hz, JHH(syn) 0, 1H,
11 Hz, JPH 10 Hz, 1H, anti-
CHPh), 3.4 (br m, 1H, syn-CHH), 3.3 (t, JHH(anti)
10.5 Hz, JPH
10 Hz, 1H, anti-CHH) (195Pt satellites
were indiscernible). 13C{1H} NMR (CDCl3): d 135ꢃ
127
(m, Ph), 112.0 (t, CH), 90.9 (d, JPC 26.4 Hz, CHPh),
66.2 (d, JPC
26.8 Hz, CH2). 31P{1H} NMR (CDCl3): d
3
3
Ph), 5.9 (m, JHH(anti)
ꢁ
/
]
/
CH), 4.9 (dd, 3JHH(anti)
ꢁ
/
ꢁ
/
3
ꢁ
/
ꢁ
/
/
ꢄ
/
78 8C first with (PPh3)2Pt(C2H4) and then with
ꢁ
/
PhCÅCCH2OTs, both in CH2Cl2, followed by warming
/
ꢁ
/

R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ
/290
281
18.0 (d, JPP
10.7 Hz, JPP
ꢁ
ꢁ
/
10.7 Hz, JPtP
ꢁ/4050 Hz), 14.5 (d, Jpp
ꢁ
/
NMR (CD2Cl2): d 7.8ꢃ6.8 (m, 39H, Ph, C6H4), 4.8 (br
m, 1H, CHPh), 3.4 (m, 2H, CH(Me)Et), 2.7 (br s, 1H,
syn-CHH), 2.3 (m, 1H, anti-CHH), 2.3 (s, 3H,
/
/4222 Hz).
2.3.3. Reaction of 1aOTf with Cp2Zr(Cl)D
This reaction was carried out similarly to the preced-
ing one, but with Cp2Zr(Cl)D in place of Cp2Zr(Cl)H.
C6H4Me), 1.8ꢃ
CHMe). 13C{1H} NMR(CD2Cl2):
NCCH2), 139ꢃ126 (m, Ph, C6H4), 56.7 (m, CHPh),
51.8 (m, NCH), 38.6 (m, CCH2), 21.4 (s, C6H4Me), 12.0
(s, CH2Me), 10.5. 10.3 (2s, CHMe, CH2Me). 31P{1H}
NMR (CD2Cl2): d 18.4 (m), 14.4 (m). FAB MS: 195Pt,
m/z 963 (Mꢂ), 719 (Pt(PPh3)2ꢂ), 456 (PtPPh3ꢂ).
/
0.7 (m, 16H, CH2Me, CH2Me,
d
161.2 (m,
/
1
The H NMR spectrum of the product [(PPh3)2Pt(h3-
CH2CDCHPh)]OTf (3ꢃd1OTf) (in CDCl3) was very
/
similar to that of 3OTf, the major difference being the
virtual absence of the central CH proton signal at d 5.9.
2
In the H NMR spectrum there was a broad signal at d
6.
2.5. Reactions of [(PPh3)2Pd(h3-CH2CCPh)]OTs
(1bOTs) with amines
2.3.4. Reaction of 1aOTf with Cp2ZrH2
To a suspension of Cp2ZrH2 (0.0113 g, 0.0509 mmol)
in 5 ml of THF at ꢄ
/
78 8C was added 1aOTf (0.050 g,
0.051 mmol) in 10 ml of THF also at ꢄ
/
78 8C. The
mixture was allowed to warm to r.t. over 2.5 h. A single
PPh3-containing product was observed by 31P NMR
spectroscopy and was identified as 3OTf.
2.5.1. Reaction of 1bOTs with (i-Pr)2NH
Diisopropylamine (0.100 ml, 0.718 g mlꢄ1, 0.710
mmol) was added by syringe to a stirred solution of
1bOTs (0.150 g, 0.164 mmol) in 10 ml of CH2Cl2 at r.t.
The color of the solution immediately changed from
light yellow to gold, and stirring was continued for 10
min. The solvent and excess amine were removed under
reduced pressure to leave a yellow solid, which was
2.4. Reactions of [(PPh3)2Pt(h3-CH2CCPh)]OTs
(1aOTs) with amines
2.4.1. Reaction of 1aOTs with (i-Pr)2NH
To a stirred solution of (PPh3)2Pt(C2H4) (0.150 g,
0.201 mmol) in 10 ml of CH2Cl2, at 0 8C was added
washed with hexanes (2ꢅ20 ml) and dried under
/
vacuum for several days. The yield of pale yellow
[(PPh3)2Pd(h3-CH2(N(i-Pr)2)CHPh)]OTs (4bOTs) was
0.060 g (0.201 mmol} of PhCÅ/CCH2OTs. The solution
1
changed color from light yellow to orange and was
allowed to warm to r.t. Diisopropylamine (0.100 ml,
0.718 g mlꢄ1, 0.710 mmol) was then introduced by
syringe, and stirring was continued for 30 min. All
volatiles were removed under reduced pressure to leave a
cream-colored solid, which was washed with hexanes
0.151 g (90%). H NMR (CD2Cl2): d 7.8ꢃ
/
6.9 (m, 39H,
Ph, C6H4), 5.3 (br m, 1H, CHPh), 3.6 (m, 2H, CHMe2),
2.8 (m, 1H, syn-CHH), 2.7 (m, 1H, anti-CHH), 2.3 (s,
3H, C6H4Me), 1.2ꢃ
NMR (CD2Cl2): d 152.9 (t, JPC
126 (m, Ph, C6H4), 73.1 (d, JPC
(d, JPC 39.5 Hz, CCH2), 48.7 (s, NCH), 21.2 (s,
C6H4Me), 13.8 (s, CHMe2). 31P{1H} NMR (CD2Cl2):
/
1.0 (m, 12H, CHMe2). 13C{1H}
ꢁ
/
5 Hz, NCCH2), 138ꢃ
/
ꢁ/44 Hz, CHPh), 48.8
(3ꢅ10 ml) and dried under vacuum for several days.
/
ꢁ
/
The yield of [(PPh3)2Pt(h3-CH2C(N(i-Pr)2)CHPh)]OTs
1
(4aOTs) was 0.215 g (97%). H NMR (CD2Cl2): d 7.8ꢃ
/
d 23.6 (d, JPP
ꢁ
/
31 Hz), 22.7(d, JPP
ꢁ31 Hz). FAB MS:
/
106Pd, m/z 846 (Mꢂ), 630 (Pd(PPh3)2ꢂ), 368
6.8 (m, 39H, Ph, C6H4), 4.8 (br m, 1H, CHPh), 3.8 (m,
2H, CHMe2), 2.7 (br m, 1H, syn-CHH), 2.3(m, 1H anti-
(PdPPh3ꢂ).
CHH), 2.3 (s, 3H, C6H4Me), 1.3ꢃ
13C{1H} NMR (CD2C12): d 159.3 (t, JPC
JPtC 120 Hz, NCCH2), 139ꢃ126 (m, Ph, C6H4), 60.2
(d, JPC 50 Hz, JPtC 260 Hz, CHPh), 49.4 (s, NCH).
38.0 (d, JPC 46 Hz, JPtC 260 Hz, CH2), 20.9 (s,
C6H4Me), 13.8 (s, CHMe2). 31P{1H} NMR (CD2Cl2): d
17.7 (d, JPP 7.5 Hz, JPtP 3324 Hz), 14.7 (d, JPP 7.5
Hz, JPtP
/0.9 (m, 12H, CHMe2).
ꢁ/4.5 Hz,
ꢁ
/
/
2.5.2. Reaction of 1bOTs with (sec-Bu)2NH
ꢁ
/
ꢁ
/
The reaction was conducted similarly to the preceding
one, starting with 1bOTs (0.150 g, 0.164 mmol) and (sec-
Bu)2NH (0.100 ml, 0.753 g mlꢄ1, 0.580 mmol). The
yield of [(PPh3)2Pd(h3-CH2C(N(sec-Bu)2CHPh)]OTs
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
/
ꢁ
2994 Hz). FAB MS: 195Pt, m/z 935 (Mꢂ),
/
1
719 (Pt(PPh3)2ꢂ), 456 (PtPPh3ꢂ).
(5bOTs), a yellow solid, was 0.128 g (75%). H NMR
(CD2C12): d 7.9ꢃ
CHPh), 3.3 (br m, 2H, CH(Me)Et), 2.7 (br m, 2H, syn-
and anti-CHH), 2.3 (s, 3H, C6H4Me), 1.8ꢃ0.5 (m, 16H,
CH2Me, CH2Me, CHMe2). 13C{1H} NMR (CD2Cl2): d
154.1 (m, NCCH2), 138ꢃ126 (m, Ph, C6H4), 72.5 (m,
CHPh), 51.5 (m, NCH), 48.2 (d, JPC 41 Hz, CCH2),
20.9 (s, C6H4Me], 11.5 (s, CH2Me), 10.1, 9.9 (2s,
CHMe, CH2Me). 31P{1H} NMR (CD2Cl2): d 23.8ꢃ
/
6.9 (m, 39H, Ph, C6H4), 5.4 (br m, 1H,
2.4.2. Reaction of 1aOTs with (sec-Bu)2NH
This reaction was conducted similarly to the preced-
ing one, starting with (PPh3)2Pt(C2H4) (0.150 g, 0.201
/
/
mmol), PhCÅ
/
CCH2OTs (0.060 g, 0.201 mmol) and (sec-
Bu)2NH (0.100 ml, 0.753 g mlꢄ1, 0.580 mmol). The
ꢁ
/
yield of [(PPh3)2Pt(h3-CH2C(N(sec-Bu)2CHPh)]OTs
(5aOTs), a cream-colored solid, was 0.205 g (90%). H
1
/

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R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ290
/
21.8 (m). FAB MS, 106Pd, m/z 874 (Mꢂ), 630
(Pd(PPh3)2ꢂ), 368 (PdPPh3ꢂ).
from CH2(CO2Me)2 and NaH, and the mixture was
cooled to ꢄ78 8C. One equiv. of MeCÅCCH2OTs
/
/
(0.030 g) in CH2Cl2 (1 ml) was slowly introduced to
this solution, and the contents were stirred with warm-
ing to r.t. over 4.5 h. Solvent was removed under
reduced pressure, and the residue was extracted with
20 ml portions of benzene. After the extract was filtered
and concentrated, addition of approximately 60 ml of
hexanes induced the precipitation of a pale yellow
powder, which was collected on a filter frit, washed
with hexanes and dried in vacuum for several hours. The
2.6. Competition reactions of [(PPh3)2M(h3-
CH2CCPh)]OTs (MꢁPt (1aOTs), Pd (1bOTs)) with
/
?
R2NH and R2NH or R2NH and R?OH
The reaction of 1aOTs with a mixture of Et2NH and
(i-Pr)2NH illustrates the procedure employed.
A well stirred mixture of Et2NH (0.0690 ml, 0.707 g
mlꢄ1, 0.667 mmol) and (i-Pr)2NH (1.39 ml, 0.718 g
mlꢄ1, 10.0 mmol) in 5 ml of CH2Cl2 was added to a
stirred solution of 1aOTs prepared in situ from
yield of 7 was 0.090 g (75%). 1H NMR (CDCl3): d 7.5ꢃ
7.0 (m, 30H, Ph), 4.0 (br m, 2H, CHMe, syn-CHH),
3.52 (s, 6H, CO2Me), 2.40 (d, JPH 9.5 Hz, JPtH 61.5
Hz, 1H, anti-CHH), 1.05 (sept, 3H, CHMe). 13C{1H}
NMR (CDCl3): d 170.3 (t, JPC 11.7 Hz, CO2Me),
153.8 (t, JPC 84 Hz, CCH2), 135ꢃ125 (m, Ph), 88.1 (s,
CCO2Me), 61.8 (d, JPC 37 Hz, JPtC 178 Hz,
CHMe), 50.0 (s, CO2Me), 42.5 (d, JPC 40.5 Hz,
JPtC 171 Hz, CH2), 16.8 (d, JPC 6.0 Hz, JPtC 48.3
Hz, CHMe) 31P{1H} NMR (CDCl3): d 21.4 (br s, JPP
not resolved, JPtP 3382 Hz), 18.4 (br s, JPP not
resolved, JPtP 3003 Hz). Anal. Found: C, 60.53; H,
/
ꢁ
/
ꢁ
/
(PPh3)2Pt(C2H4) (0.0500 g, 0.0669 mmol) and PhCÅ
/
CCH2OTs (0.0200 g, 0.0670 mmol) in 5 ml of CH2Cl2.
The resulting solution gradually changed color from
orange to light yellow, and after 15 min, all volatiles
were removed under reduced pressure and the yellow
ꢁ
/
ꢁ
/
/
ꢁ
/
ꢁ
/
ꢁ
/
1
solid was dried for several hours. The H and 31P{1H}
ꢁ
/
ꢁ
/
ꢁ
/
NMR spectra showed the presence of both
[(PPh3)2Pt(h3-CH2C(NEt2)CHPh)]OTs (6aOTs) and
[(PPh3)2Pt(h3-CH2C(N(i-Pr)2)CHPh)]OTs (4aOTs) in
the mixture. The relative intensities of the signals of
CHPh of each 6aOTs [9] and 4aOTs were used to
determine the ratio of the two products.
This competition reaction was also run with the
Et2NH-(i-Pr)2NH molar concentration ratios of 1/5
and 1/10.
ꢁ
/
ꢁ
/
4.99. Calc. for C45H42O4P2Pt: C, 59.8; H, 4.68%.
2.8. Reactions of (PPh3)2Pt(h3-
CH2C(C(CO2Me)2)CHR) (Rꢁ
/
Me (7), Ph (8)) with
unsaturated electrophiles
Similar procedures were employed for reactions of
1aOTs with mixtures of (i-Pr)2NH and (sec-Bu)2NH (1/
5 and 1/10 M concentration ratios) and of Et2NH and
EtOH (1/10, 1/20 and 1/40 M concentration ratios). The
faster reacting (smaller) amine was always in tenfold
excess over the metal complex. The relative intensities of
the signals of CHMe2 of 4aOTs and of CH(Me)Et of
[(PPh3)2Pt(h3-CH2C(NEt2)CHPh)]OTs (5aOTs) in the
former reaction, and of CHPh of each 4aOTs and
[(PPh3)2Pt(h3-CH2C(OEt)CHPh)]OTs [21] in the latter
reaction were used (available) to determine the ratios of
the (possible) products.
2.8.1. Reaction of 8 with diethyl fumarate
A solution of 8 (0.075 g, 0.078 mmol) and diethyl
fumarate (0.014 g, 0.081 mmol) in 5 ml benzene was
maintained at reflux temperature. Progress of the
reaction was monitored by 31P{1H} NMR spectroscopy.
After 18 h, the slightly cloudy solution was filtered, the
filtrate was evaporated to dryness and the residue was
washed with 10 ml of Et2O. The off-white solid
(PPh3)2Pt(h2-trans-EtO2CCHÄ
/
CHCO2Et) (9) was col-
lected by filtration, washed with 5-ml portions of Et2O
and dried under vacuum. The yield was 0.051 g (73%).
IR(C6H6): n(CO2) 1753 (s) cmꢄ1, n(CÄ
/
C of Ph) 1617
(m), 1528 (m), 1435 (m) cmꢄ1. 1H NMR (C6D6); d 8.0ꢃ
6.5 (m, 30H, Ph), 4.18 (d, JPH 3.5 Hz, JPtH 56 Hz,
2H, Ä 7.1
CH), 3.92, 3.43 (2 m, 4H, CH2), 0.75 (t, 3JHH
Hz, 6H, Me). 13C{1H} NMR(C6D6): d 173.0 (s, JPtC
39.6 Hz, CO2Et), 136ꢃ127 (m, Ph), 58.5 (s, CH2), 49.0
(t, JPC 13.5 Hz, JPtC CH), 13.9 (s, Me).
215 Hz, Ä
3862 Hz). FAB
Reactions of 1bOTs with each Et2NH-(i-Pr)2NH (1/5,
1/8 and 1/10 M concentration ratios) and (i-Pr)2NH/
(sec-Bu)2NH (1/5 and 1/10 M concentration ratios) were
conducted similarly, except that the 1bOTs used was an
isolated solid sample rather than an in situ preparation.
/
ꢁ
/
ꢁ
/
/
ꢁ
/
ꢁ
/
/
1
The H NMR signals used to determine the ratios of
products in the mixtures corresponded to those of the
analogous platinum products.
ꢁ
/
ꢁ
/
/
31P{1H} NMR (C6H6): d 25.8 (s, JPtP
ꢁ
/
MS: 195Pt, m/z 892 (Mꢂ), 719 (Pt(PPh3)2ꢂ).
The washings from the filtration of 9 were combined
and evaporated to dryness. The residue was extracted
2.7. Preparation of (PPh3)2Pt(h3-
CH2C(C(CO2Me)2CHMe) (7)
with 10 ml of hexanes at approximately ꢄ78 8C for 1 h,
/
and the extract was filtered. The oil obtained after
evaporation of the solvent from the filtrate contained a
mixture of the organic products 10 and 11 as indicated
by its 1H NMR spectrum. Purification by passage
A solution of (PPh3)2Pt(C2H4) (0.100 g, 0.134 mmol)
in 5 ml of CH2Cl2 was added with stirring to an excess of
solid NaCH(CO2Me)2 (0.153 g, 0.996 mmol), obtained

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/290
283
through a short column of silica gel with CH2Cl2 eluent
afforded off-white needles of 1,1,4,4-tetracarbo-
methoxy-2,5-dimethyl-3,6-diphenyl-2,5-cyclohexadiene
(11). The yield was 0.010 g (53%). In some instances, 11
was the only organic product observed in the H NMR
spectrum of the reaction solution to indicate that the
165.2 (2s, CO2Me), 164.5 (s, NCO), 144.9 (s, C Ä
136ꢃ126 (m, Ph, C6H4), 118.6 (s, Ä
CCO2Me), 66.4 (s, CHPh), 53.4, 53.1 (2s, CO2Me),
21.1 (C6H4Me). EI MS: m/z 443 (Mꢂ), 412 (Mꢂꢄ
OMe), 384 (Mꢂꢄ CO), 288 (Mꢂꢄ
OMeꢄ Ts). Anal.
/
CH2),
/
/
CH2); 68.0 (s,
/
1
/
/
/
Found: C, 62.00; H, 4.94. Calc. for C22H21O7NS: C,
61.81; H, 4.95%.
isomerization of 10 to 11 was complete at that point.
Selected data for 10: 1H NMR (C6H6): d 6.23 (d, JHH
ꢁ
/
2.9 Hz, 1H of Ä
4.65 (d, JHH
2.4 Hz, 1H of Ä
3.78 (s, 3H, Me). Data for 11: 1H NMR (CDCl3): d 7.5ꢃ
/
CH2), 5.77 (t, JHH
ꢁ2.6 Hz, 1H, CHPh),
/
ꢁ
/
/CH2), 4.02 (s, 3H, Me),
2.8.3. Reaction of 7 with tetracyanoethylene (TCNE)
To a solution of 7 (0.100 g, 0.110 mmol) in 10 ml of
benzene at r.t. was added with stirring 1 equiv. of TCNE
(0.014 g). The reaction was monitored by 31P{1H} NMR
spectroscopy and reached completion in 1 h. The solvent
was then removed under reduced pressure, and the
/
7.0 (m, 10H, Ph), 4.16 (s, 3H, CO2Me), 3.83 (s, 3H,
CO2Me), 2.41 (s, 6H, CMe). 13C NMR (CDCl3): d
164.1, 161.8 (2s, CO2Me), 139.5 (s, CMe), 130.5, 128.4,
126.7, 125.4 (s, 3d, Ph), 118.0 (s, CPh), 93.1 (s,
CCO2Me), 57.5, 50.8 (2q, CO2Me), 10.9 (q, CMe). EI
MS: m/z 492.178 (Mꢂ), 461 (Mꢂꢄ
OMeꢄ 2OMeꢄ
CO), 402 (Mꢂꢄ CO), 374 (Mꢂꢄ
2OMeꢄ
2CO). 246 (Mꢂ/2).
/
OMe), 434 (Mꢂꢄ
/
residue was washed with several 5 ml portions of Et2O.
1
The yield of 7×
(CDCl3): d 8.0ꢃ
CHMe), 3.45 (s, 3H, CO2Me), 3.2 (br d, JHH
/
TCNE (14) was 0.085 g (75%). H NMR
/
/
/
/
/
6.8 (m, 30H, Ph), 4.48 (m, 1H,
/
2
Ä
/
ꢁ
/
14.8
2
Hz, CHH), 3.05 (s, 3H, CO2Me), 2.3 (dd, JHH
Hz, JPH 9.3 Hz, CHH). 1.02 (d, JPH
CHMe). 13C{1H} NMR (CDCl3): d 170.6, 170.1 (m,
CO2Me), 138ꢃ125 (m, Ph), 112.8, 112.1, 111.8, 111.2
(4s, CN), 63.3 (dd, JPC 59, 4 Hz, JPtC 405 Hz,
CHMe), 53.1 (dd, JPC 38, 5 Hz, JPtC not resolved,
C), 51.8, 51.2 (2s, CO2Me), 49.7 (d, JPC 12 Hz,
CCO2Me), 48.2, 43.6 (2s, CCN), 43.2 (d, JPC 12 Hz,
JPtC 63 Hz, CH2), 20.4 (d, JPC 4.6 Hz, JPtC 31 Hz,
CHMe). 31P{1H} NMR (CDC13): d 20.5 (d, JPP
18
Hz, JPtP 3839 Hz), 20.2 (d, JPP 18 Hz, JPtP 3560
ꢁ/14.8
2.8.2. Reaction of 8 with p-toluenesulfonyl isocyanate
(TSI)
ꢁ
/
ꢁ7.4 Hz,
/
Ä
/
A solution of 8 (0.200 g, 0.207 mmol) in 5 ml of
CH2C12 was treated with 3 equiv. of TSI (0.656 M
solution in CH2Cl2) and the contents were stirred for 3 h
at r.t. The solvent was removed under reduced pressure,
the residue was treated with 10 ml of THF and the
resulting suspension was stirred for 30 min. The white
insoluble solid, (PPh3)2Pt(OCNSO2C6H4Me)2 (12), was
collected by filtration and washed with 5-ml portions of
/
ꢁ
/
ꢁ
/
Ä
/
ꢁ
/
Ä
/
ꢁ
ꢁ
/
/
ꢁ
/
ꢁ
/
ꢁ
/
Ä
/
ꢁ
/
THF. The yield was 0.042 g. IR (C6H6): n(CÄ
(m), 1550 (m), 1481 (m) cmꢄ1, n(SO2) 1020 (s) cmꢄ1. 1H
NMR (CDCl3): d 8.0ꢃ6.5 (m, 38H, Ph, C6H4,), 2.28 (s,
6H, C6H4Me). 13C{1H} NMR (CDC13): d 141.0, 140.0,
134ꢃ
127 (m, Ph, C6H4), 21.3 (s, C6H4Me). 31P{1H}
NMR (CDCl3): d 5.0 (s, JPtP 3704 Hz). Anal. Found:
/C) 1598
ꢁ
/
ꢁ
/
ꢁ
/
Hz). Anal. Found: C, 59.84; H, 4.92; N, 5.18. Calc. for
C51H42N4O4P2Pt: C, 59.36; H, 4.10; N, 5.43%.
/
/
ꢁ
/
2.8.4. Reaction of 7 with fumaronitrile
A solution of 7 (0.030 g, 0.033 mmol) and 2 equiv. of
freshly sublimed fumaronitrile (0.005 g) in 0.5 ml of
C, 55.70; H, 4.13; N, 2.61. Calc. for C52H44N2O6P2PtS2;
C, 56.06; H, 3.98; N, 2.51%.
The last-mentioned filtrate was combined with the
THF washings, and the mixture was concentrated to 5
ml and treated with 10 ml of hexanes. A slightly colored
1
benzene-d1 at r.t. was monitored by H and 31P{1H}
NMR spectroscopy for 44 h. The in-situ spectra were
consistent with the formation of (PPh3)2Pt(h2-trans-
solution was separated by filtration from a yellowꢃ
/
NCCHÄ
on slow evaporation of the solvent. H NMR (CDCl3):
d 8.0ꢃ7.0 (m, 30H, Ph), 2.57 (d, JPH 5.9 Hz, JPtH 60
Hz, 2H, C(CN)H). 31P{1H} NMR (CDCl3): d 23.0 (s,
JPtP 3709 Hz).
/
CHCN) (15), which crystallized from solution
orange precipitate. The filtrate was evaporated to
dryness, and the residue was washed with several 10
ml portions of hexanes. Further purification could be
effected by chromatography on silica gel. The yield of
1
/
ꢁ
/
ꢁ
/
the [3ꢂ
2] cycloaddition product of h3-CH2C(C(CO2-
/
ꢁ
/
The mother liquor was evaporated to dryness, and the
1
residue was examined by H NMR spectroscopy. No
Me)2)CHPh and TSI, an off-white solid (13), was 0.033
g (36%). IR (C6H6): n(CO2) 1773 (s) cmꢄ1; n(NCO)
1679 cmꢄ1; n(CÄ
/
C) 1570 (m), 1549 (m), 1436 (m) cmꢄ1
;
attempt was made at further purification of 1,4-
dimethyl-2,5-dimethylene-3,3,6,6-tetracarbomethoxycy-
1
clohexane (16) owing to its small quantity. H NMR
n(SO2) 1377 (s), 1176 (s) cmꢄ1. H NMR (CDCl3): d
1
8.0ꢃ
CHPh), 5.60 (dd, JHH
CHH), 5.33 (dd, 2JHH
CHH), 3.79 (s, 3H, CO2Me), 3.77 (s, 3H, CO2Me),
2.40 (s, 3H, C6H4Me). 13C{1H} NMR (C6D6): d 165.3,
/
6.5 (m, 9H, Ph, C6H4), 5.83 (t, 4JHH
ꢁ
/
2.25 Hz, 1H,
2.25 Hz, 1H,
2.25 Hz, 1H,
(CDCl3): d 5.49 (d, 2JHH
ꢁ
/
1.3 Hz, 2H, Ä
/
CHH), 4.88 (d,
2
4
ꢁ
ꢁ
/
1.93 Hz, JHH
1.93 Hz, 4JHH
ꢁ
ꢁ
/
2JHH
ꢁ
/
1.3 Hz, 2H, Ä
/
CHH), 3.25 (s, 12H, CO2Me), 2.27
Ä
/
/
/
3
3
7.1 Hz, CHMe), 0.75 (d, JHH
(q, JHH
CHMe).
ꢁ
/
ꢁ7.1 Hz, 6H,
/
Ä
/

284
R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ290
/
2.8.5. Reaction of 7 with p-toluenesulfonyl isocyanate
(TSI)
obtained earlier by reaction of [Cp(CO)2Ru(h2-CH2Ä
CÄ
/
/
CHPh]BF4 with (PPh3)2Pt(C2H4) [22] (Eq. (3)).
A solution of 7 (0.100 g, 0.11 mmol) in 5 ml of THF
was treated with approximately 3 equiv. of TSI (0.060
g), and the contents were stirred for 12 h at r.t. The color
of the solution turned bright orange during the reaction,
and an abundant white precipitate formed. This pre-
cipitate, characterized spectroscopically as 12, was
filtered off, washed with 2 ml portions of THF and
dried in vacuum. The yield was 0.107 g (90%). The
filtrate was then treated as described in Section 2.8.2 for
ð2Þ
the analogous 13. The yield of the [3ꢂ2] cycloaddition
/
product (17) of h3-CH2C(C(CO2Me)2)CHMe and TSI
was 0.032 g (76%). H NMR (CDCl3): d 7.95, 7.34 (2d,
1
3JHH
ꢁ
/
8.3 Hz, 4H, C6H4), 5.54 (m, 1H, Ä
/
CHH), 5.46
3
CHH), 4.96 (q, JHH
(m, 1H, Ä
/
ꢁ
/
6.4 Hz, 1H, CHMe),
3.75 (s, 3H, CO2Me), 3.63 (s, 3H, CO2Me), 2.44 (s, 3H,
C6H4Me), 1.65 (d, 3JHH 6.4 Hz, 3H, CHMe). 13C{1H}
NMR (CDCl3): d 164.8, 164.7 (2s, CO2Me), 164.1 (s,
NCO), 154.5 (s, C ÄCH2), 115.6 (s, ÄCH2), 59.3 (s,
ꢁ
/
/
/
CCO2Me), 53.8, 53.6 (2s, CO2Me), 29.6 (s, CHMe),
23.5 (s, CHMe), 21.6 (s, C6H4Me).
ð3Þ
3. Results and discussion
3.1. Reactions of [(PPh3)2Pt(h3-CH2CCPh)]OTf
(1aOTf) with metal hydrido complexes
Although reactions of transition-metal h3-allenyl/
propargyls have been investigated with a number of
The IR spectrum of 2OTf shows two strong n(CO)
bands at 2023 and 1966 cmꢄ1. These frequencies are
comparable to those of the cationic 2IBF4 at 2027 and
nucleophilic reagents [1ꢃ6], those with metal hydrido
/
1976 cmꢄ1 and the neutral Cp(CO)2RuCHÄ
CPh at 2031 and 1984 cmꢄ1
/
CÄ/CH2
complexes have not been studied. Yet metal hydrides
LxMH represent an interesting class of nucleophiles
because hydride is expected to add to the central carbon
atom of the h3-allenyl/propargyl, with the LxM frag-
ment bonding to the terminal CR carbon. Thus, these
and Cp(CO)2RuCH2CÅ
/
and 2014 and 1959 cmꢄ1, respectively [22]. Thus, the
positive charge of 2 and 2I is largely localized on the
platinum part of the complex, consistent with the
reactions, unlike those previously reported [1ꢃ6], gen-
/
1
assigned structures. The H NMR spectrum of 2OTf
erate metal h3-allyl products containing the entering
heteroatom substituent in the terminal position.
Furthermore, they would provide another synthetic
route to bimetallic complexes.
displays h3-allyl signals at d 6.17, 3.47 and 2.26, which
are attributed to CH, syn-CHH and anti-CHH, respec-
tively. The signal at d 2.26 occurs with readily dis-
cernible coupling to one phosphorus (10.0 Hz) and to
With the aforementioned objectives in mind, we
undertook
platinum-195 (45 Hz), as expected for a h3-allyl anti
a
study of reaction of 1aOTf with
78 8C
2
proton [9,10,21,23,24]. The coupling constants JHH
B2
/
Cp(CO)2RuH. The reaction was conducted at ꢄ
/
3
Hz, JHH(anti)
ꢁ
/
11.0 Hz and JHH(syn)
ꢁ7.2 Hz, all
/
with warming to r.t. and resulted in the isolation in 73%
yield of a pale yellow air-stable solid, characterized by
spectroscopy and elemental analysis as [(PPh3)2Pt(h3-
CH2CHC(Ph)Ru(CO)2Cp)]OTf (2OTf) (Eq. (2)). This
cationic product is isomeric with the complex
[(PPh3)2Pt(h3-CH2C(Ru(CO)2Cp)CHPh)]BF4 (2IBF4),
consistent with the proposed structure [25], were deter-
mined with the aid of decoupling experiments. The
13C{1H} resonances of the h3-allyl ligand are observed
at d 122.2 (JPC
ꢁ/3.5 Hz, JPtC
ꢁ28.4 Hz) for CH and
/
60.0 (JPC 30.4 Hz; JPtC
ꢁ
/
ꢁ
/
132 Hz) for CH2, again in

R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ
/290
285
accord with the structural assignment. However, no
signal was detected for the CPh carbon, possibly owing
to its presumed low intensity. The presence of the
Cp(CO)2Ru moiety in 2 is reflected by the appearance
of the CO resonances at d 200.0 and 199.5 and of the Cp
resonance at d 90.3. It is noteworthy that the signal at d
200.0 shows platinum-195 satellites, with JPtC
ꢁ17.2 Hz.
/
ð4Þ
Similar, but smaller (8.8ꢃ9.3 Hz), JPtC coupling was
/
reported [22] for the CO’s of 2IBF4. The magnitude of
the JPtC for 2OTf might indicate that the Cp(CO)2Ru is
positioned anti as a substituent on the h3-allyl ligand.
The 31P{1H} NMR spectrum of 2OTf is typical of those
for Pt(PPh3)2 complexes containing an unsymmetrical
h3 hydrocarbyl group [9,10,21].
Since Cp(CO)2RuH was found to add to the
h3-allenyl/propargyl ligand of 1aOTf, it was of interest
to determine whether the related alkyl complex
Cp(CO)2RuMe would behave similarly. However, no
reaction was observed by 31P NMR spectroscopy
between 1aOTf and Cp(CO)2RuMe in CH2C12 at reflux
temperature.
A point that remains to be addressed is the source of
the CHPh hydrogen in the 3OTf synthesized by reaction
of 1aOTf with Cp2Zr(Cl)H. To ascertain whether this
hydrogen derives from solvent, the reaction was carried
out in each of THF-d8, benzene and benzene-d6. It was
found to proceed very slowly in benzene owing to low
solubility of the reactants. However, in all cases, 3OTf
was obtained as the product, and no labeling was
observed when deuterated solvents were employed.
In order to determine whether adventitious H2O was
the source of the above hydrogen, a solution of 1aOTf in
THF was treated first with 2 equiv. of D2O and then
immediately with Cp2Zr(Cl)H. The h3-allyl product
isolated from the reaction mixture contained approxi-
mately 80% deuterium incorporation into the CHPh
Our investigation of reactions of 1aOTf with metal
hydrides was then extended to the early transition
metals represented by Cp2Zr(Cl)H. Treatment of
Cp2Zr(Cl)H with 1aOTf in THF at ꢄ78 8C with
/
warming to r.t. afforded [(PPh3)2Pt(h3-CH2CH-
CHPh)]OTf (3OTf) as the only organometallic product
that could be isolated and characterized (Eq. (4)). The
fate of the Cp2ZrCl moiety was not determined. The h3-
allyl complex 3OTf was synthesized earlier from
1
position (Eq. (5)) as ascertained by H NMR spectro-
scopy.
Pt(PPh3)4 and PhCHÄ/CHCH2HgCl by Nesmeyanov
and Rubezhov [26], but spectroscopic details were not
disclosed. In this study, the structure of 3OTf was
inferred with the aid of NMR data. Thus, the 1H NMR
spectrum shows h3-allyl signals at d 5.8, 4.9, 3.4 and 3.3,
which are assigned to the CH, anti-CHPh, syn-CHH
and anti-CHH protons, respectively, with the help of
decoupling experiments. The coupling constants JHH are
given Section 2.3.2. The magnitude of 3JHH between CH
and CHPh (11 Hz) indicates an anti arrangement of two
protons [25]. This arrangement receives further support
by the absence of W-coupling, which would he expected
for a h3-allyl containing two syn hydrogens [27]. The
13C{1H} and 31P{1H} NMR spectra are also in accord
with the h3-allyl structure. The former shows signals at
d 112.0 (CH), 90.9 (CHPh) and 66.2 (CH2), whereas the
ð5Þ
2
Furthermore, the H NMR spectrum of the product
latter consists of two doublets al d 18.0 (JPtP
and 14.5 (JPtP 4222 Hz) with JPP 10.7 Hz. When the
reaction in question was carried out by using
Cp2Zr(Cl)D in place or Cp2Zr(Cl)H, 3ꢃd1OTf was
obtained with deuterium exclusively at the central
carbon atom (cf. Eq. (4)). Reaction between 1aOTf
and Cp2ZrH2, also afforded 3OTf.
ꢁ
/
4050 Hz)
ꢁ
/
ꢁ
/
showed a signal at d 4.8. No labeling at the other
positions was inferred or found by 1H or 2H NMR
spectroscopy. Thus, it appears that the CHPh hydrogen
in 3OTf originates from adventitious H2O in the solvent.
We consider it unlikely that this H2O in very low
concentration reacts with 1aOTf to yield the oxygen-
/

286
R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ290
/
bridged
binuclear
[{(PPh3)2Pt(h3-CH2CCH-
however, they decompose in solution when exposed to
air and moisture. They also decompose, without melt-
ing, upon heating at 70ꢃ100 8C.
Ph)}2O](OTf)2 [21], which is then converted by
Cp2Zr(Cl)H to 3OTf. This is because reaction of
1aOTf with H2O [21] was found to proceed quite slowly
compared with the formation of 3OTf.
/
In conclusion, we propose that Cp2Zr(Cl)H reacts
with 1aOTf to afford a platinacyclobutene intermediate,
which is protonated by H2O at platinum and then
converted to 3OTf by hydrogen transfer to Ä
/
CPh.
Alternatively, the initial product of the reaction might
be a h3-allyl complex, [(PPh3)2Pt(h3-CH2CHC(Ph)-
Zr(Cl)Cp2)]OTf, analogous to 2OTf, which undergoes
transformation to 3OTf by the action of H2O. Both of
these mechanistic possibilities are depicted in Scheme 1.
ð6Þ
The new complexes were characterized by NMR (1H,
l3C{1H} and 31P{1H}) spectroscopy and FAB MS. Each
mass spectrum showed a strong peak corresponding to
the parent molecular ion, as well as peaks for
3.2. Reactions of [(PPh3)2M(h3-CH2CCPh]OTs
(MꢁPt (1aOTs), Pd (1bOTs)) with amines
/
M(PPh3)2 and MPPh3ꢂ. The NMR spectra are in
good agreement with those of the related h3-(2-ami-
noallyl) complexes of platinum and palladium
ꢂ
Nucleophilic addition reactions of primary and sec-
ondary amines with platinum and palladium h3-allenyl/
propargyl complexes have been the subject of several
[(PPh3)2M(h3-CH2C(NHR or NR2)CHR?)]ꢂ (Mꢁ
/Pt,
reports [7ꢃ9,28]. However, unlike the corresponding
/
Pd; Rꢁ
/
alkyl, aryl; R?ꢁ
/
Ph, Me, H) [7ꢃ
/
9,28] and
reactions of alcohols [21,24], these additions have not
been investigated with respect to relative reactivity of
various amines. We set out to fill this void, but first
considered it necessary to augment published synthetic
exhibit additional features as mentioned below.
The 1H NMR signals of the h3-allyl framework occur
as relatively broad miltiplets at d 4.8, 2.7 and 2.3 for the
studies [7ꢃ
9] to obtain a series of structurally related h3-
(2-aminoallyl) complexes of platinum and palladium.
/
platinum complexes, and d 5.4ꢃ
for the palladium complexes. By comparison with the
spectra of [(PPh3)2Pt(h3-CH2C(NR2)CHPh)]ꢂ (Rꢁ
Me, Et (6a)) [7,9] and
/
5.3, 2.8ꢃ
/
2.7 and 2.7ꢃ2.3
/
/
Reactions of 1aOTs and 1bOTs (the former prepared
CCH2OTs [9])
[(PPh3)Pd(h3-
in situ from (PPh3)2Pt(C2H4) and PhCÅ
/
CH2C(NEt2)CHPh)]ꢂ (6b), these signals are assigned
to the CHPh, syn-CHH and anti-CHH protons,
respectively. Similar appearance of the corresponding
resonances in the spectra of all of these complexes
suggests that they possess the same orientation of Ph
and NR2, viz., anti. This stereochemistry was previously
inferred for 6aOTf with the aid of proton decoupling
experiments [9].
with an excess of the secondary amine (i-Pr)2NH or
(sec-Bu)2NH in CH2Cl2 solution proceed readily at r.t.
to afford the appropriate h3-(2-aminoallyl) complexes
[(PPh3)2M(h3-CH2C(NR2)CHPh)]OTs (Rꢁ
/
i-Pr, Mꢁ
Pt (5aOTs),
Pt) or yellow (Mꢁ
97% isolated yield (Eq. (6)). The
products are stable in the solid for several days;
/
Pt (4aOTs), Pd (4bOTs); Rꢁ
Pd (5bOTs) as cream-colored (Mꢁ
Pd) solids in 75ꢃ
/
sec-Bu, Mꢁ
/
/
/
/
Scheme 1.

R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ
/290
287
In the 13C{1H} NMR spectra, resonances of the h3-
allyl framework are observed at d 161.2ꢃ159.3, 60.2ꢃ
56.7 and 38.6ꢃ38.0 for the platinum complexes 4aOTs
and 5aOTs, and at d 154.1ꢃ152.9, 73.1ꢃ72.5 and 48.8ꢃ
nucleophilic addition of Et2NH is much faster than that
of EtOH. This result may be attributed to a much
greater basicity of Et2NH compared with EtOH (e.g.
/
/
/
/
/
/
Kbꢁ
/
1.4ꢅ
/
10ꢄ3 and 5.0ꢅ10ꢄ17, respectively [30]).
/
48.2 for the palladium complexes 4bOTs and 5bOTs.
Their assignment to the NCCH2, CHPh and CH2
carbon atoms, respectively, again is based on compar-
Furthermore, amines are stronger nucleophiles than
alcohols [31]. Both of these factors override a compara-
tively small steric advantage of EtOH over Et2NH.
ison with the spectra of related complexes [7ꢃ
9,21,23,24,28] and on characteristic splitting patterns.
Thus, the signal of NCCH2 sometimes shows small
/
3.3. Reactions of (PPh3)2Pt(h3-
CH2C(C(CO2Me)2)CHR) (Rꢁ
/
Me (7), Ph (8)) with
phosphorusꢃ
rus atoms (triplet, JPC
CHPh and CH2 display larger coupling, to only one
phosphorus (doublet, JPC 40ꢃ50 Hz), and occur in
/
carbon coupling involving both phospho-
unsaturated electrophiles
ꢁ
/
ꢁ/5 Hz), whereas the signals of
Our group previously reported the synthesis of a h3-
trimethylenemethane (h3-TMM) complex of platinum,
8, by reaction of 1a with NaCH(CO2Me)2 [10]. The
preparation of an analogous palladium complex,
(PPh3)2Pd(h3-CH2C(C(CO2Me)2)CH2), was communi-
cated by Chen and coworkers [32]. Both complexes
ꢁ
/
/
conjunction with platinum-195 satellites (JPtC
ꢁ260 Hz)
/
for 4aOTs and 5aOTs.
Significantly, the h3-(2-aminoallyls) containing (sec-
Bu)2N (i.e. 5aOTs and 5bOTs) show more complex
signals in their NMR spectra than the h3-(2-aminoallyls)
containing (i-Pr)2N (i.e. 4aOTs and 4bOTs). These
differences are attributed to the fact that 5aOTs and
5bOTs each possess two chiral centers in the dialkyla-
mino group, and, therefore, exist as a mixture of
diastereomers. The 31P{1H} NMR spectra, especially,
are conspicuously dissimilar. Whereas the spectra of
4aOTs and 4bOTs appear as the usual doublet-of-
undergo [3ꢂ2] cycloaddition reactions with unsaturated
/
electrophiles; however, our study of such reactions of 8
was limited to TCNE. Here we report further investiga-
tions on the behavior of 8 toward unsaturated electro-
philes, as well as the preparation of a related h3-TMM
complex of platinum, 7, and its corresponding chemis-
try. Platinum h3-TMM complexes were recently re-
viewed [33].
doublets patterns [7ꢃ
/
9,21], with platinum-195 satellites
for 4aOTs, those of 5aOTs and 5bOTs present them-
In an exploratory study, complex 8 in benzene
solution was treated with several electron-deficient
alkenes and alkynes, including diethyl fumarate, fumar-
onitrile, malononitrile and dimethylacetylene dicarbox-
ylate. No reaction was observed at r.t.; however, upon
allowing these solutions to remain at reflux temperature
for 18 h, all of 8 was consumed. 31P{1H} NMR spectra
indicated the formation of appropriate (PPh3)Pt(h2-
alkene or -alkyne) as the only platinum-containing
selves as complex multiplets.
The relative reactivities of 1aOTs and 1bOTs toward
the secondary amines Et2NH, (i-Pr)2NH and (sec-
Bu)2NH at r.t. were elucidated by competition experi-
ments using mixtures of two amines as described in
Section 2.6. It was determined that, toward 1aOTs,
Et2NH is approximately 74 times more reactive than (i-
Pr)2NH (standard deviation (S.D.)ꢁ
is about 3.5 times more reactive than (sec-Bu)2NH
(S.D.ꢁ0.2). The palladium complex 1bOTs reacts 38
times faster (S.D.ꢁ5) with Et2NH than with (i-Pr)2NH,
and five times faster (S.D.ꢁ0.4) with (i-Pr)2NH than
with (sec-Bu)2NH. Thus, overall reactivity decreases in
the order Et2NH (74)ꢀ(i-Pr)2NH (3.5)ꢀ(sec-Bu)2NH
(1) for 1aOTs, and Et2NH (38)ꢀ(i-Pr)2NH (5)ꢀ(sec-
Bu)2NH (1) for 1bOTs. The two rate profiles are very
similar and indicate that steric demands of the amine are
most important in determining relative reactivity. Steric
properties of the amines are reflected by the values of
/
2), and (i-Pr)2NH
product [34ꢃ36]. Since all of these electophilic reagents
/
appeared to show similar behavior toward 8, only one of
them, viz., diethyl fumarate, was selected for a detailed
study.
The reaction between 8 and diethyl fumarate in
benzene solution at reflux temperature afforded
/
/
/
/
/
(PPh3)2Pt(h2-trans-EtO2CCHÄ
/
CHCO2Et) (9) and two
/
/
organic products, 10 and 11, derived by [3ꢂ
/
3] coupling
of h3-TMM (Eq. (7)). Complex 9 was characterized by
1H, 13C{1H} and 31P{1H} NMR spectroscopy and FAB
1
MS. The H NMR spectrum exhibits a characteristic
resonance of coordinated alkene as a doublet of d 4.18
(JPH
their cone angles, with Et2NH (1258)B
(1378)B(sec-Bu)2NH (1588) [29]. In contrast, the rela-
tive basicity of the amines used in this study*Kbꢁ
1.4ꢅ
10ꢄ3 for Et2NH, 1.6ꢅ10ꢄ3 for (i-Pr)2NH and
1.8ꢅ do not rationalize
10ꢄ4 for (sec-Bu)2NH [30]*
the observed trends.
/(i-Pr2)NH
ꢁ/3.5 Hz) with platinum-195 satellites (JPH
ꢁ56
/
/
Hz), as well as two signals of the diastereotopic ethyl
CH2 protons as multiplets at d 3.92 and 3.43. The
13C{1H} resonances of the equivalent carboethoxy
carbonyl groups and the olefinic carbons provide
evidence for interaction with the metal: d 173.0 (s,
/
/
/
/
/
/
Competition reaction of 1aOTs was also conducted
with mixtures of Et2NH and EtOH. Only the h3-(2-
aminoallyl) product 6aOTs was detected to indicate that
JPtC
JPtC
ꢁ
/
39.6 Hz, CO2Et) and 49.0 (t, JPC
215 Hz, ÄCH). There is, as expected, a single
3862 Hz).
ꢁ
/
13.5 Hz,
ꢁ
/
/
31P{1H} resonance (d 25.8, JPtP
ꢁ
/

288
R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ290
/
participate in cycloaddition reactions involving the h3-
azatrimethylenemethane ligand of (PPh3)2Pt(h3-
CH2C(NR)CHPh) (Rꢁ4-MeC6H4, 4-NO2C6H4) [8]
/
and the h3-azatrimethylenemethane and h3-oxatri-
methylenemethane ligands of platinum and palladium
complexes that were generated in situ [37,38].
Initial studies conducted on solutions containing 8
and PhNCO in benzene showed that there was no
detectable reaction in 10 h at reflux temperature. In
contrast, when 8 was allowed to react with 3 equiv. of
the more electrophilic TSI for 3 h at r.t., a platinum
complex analyzing for (PPh3)2Pt(OCNSO2C6H4Me)2
(12) and an organic cycloadduct, 13, were isolated (Eq.
(8)).
ð7Þ
The ratio of the organic products 10/11 depends on
reaction and workup conditions. Isomerization of 10 to
11 was found to occur in part during the reaction and
could be promoted further by elution of the mixture
through a silica gel column. Compound 10 was not
isolated pure, and the isolation of pure 11 required
several extraction steps to achieve complete separation
from 9 (cf. Section 2.8.1).
ð8Þ
The assigned structure of 10 is supported by the
1
CH2) H resonances at d 6.23
and 4.65 as doublets and an allylic (CHPh) resonance at
presence of two vinylic (Ä
/
d 5.77 as a triplet (JHH 2.6 Hz). Upon isomerization
ꢁ
/
of 10 to 11, these resonances disappear and are replaced
1
by a singlet methyl signal (CMe) at d 2.41. In the H
1
The H NMR spectrum of 12 revealed a C6H4Me
NMR spectrum of each compound, the carbomethoxy
Me groups resonate as two singlets: at d 4.02 and 3.78
for 10 and at d 4.16 and 3.83 for 11. The 13C{1H} NMR
spectrum of 11 is in agreement with the proposed
structure, and the EI mass spectrum confirms the
dimerization of h3-TMM by showing a parent mass
peak at m/z 492.178 and an intense peak at m/z 246 that
corresponds to Mꢂ/2.
The importance of diethyl fumarate in the formation
of 10 from 8 is underscored by the stability of 8 to
thermolysis in benzene at reflux temperature in the
absence of the fumarate. It is not known whether the
role of diethyl fumarate is to initiate the dimerization of
h3-TMM or to prevent the retrodimerization process by
irreversibly coordinating to the platinum fragment. To
our knowledge, the transformation in question repre-
sents the only reported example of such a transition
metal-promoted coupling reaction.
singlet at d 2.28 and an aromatic multiplet at d 8.0ꢃ6.5
/
in a ratio of 3/19 that corresponds to one PPh3 for each
TSI. However, a carbonyl resonance of TSI could not be
definitely assigned in the 13C{1H} NMR spectrum.
Moreover, the FAB mass spectrum showed the highest
peak to occur at m/z 1087, which most likely arises from
the loss of a CO by the molecular ion of 12. Unfortu-
nately, spectroscopic data did not allow the mode of
coordination of the TSI ligands to be elucidated.
Attempts to grow crystals of the complex for an X-ray
diffraction study proved unsuccessful.
The organic product 13 was characterized as a [3ꢂ2]
/
cycloadduct of h3-TMM and TSI on the basis of
elemental analysis, EI mass spectrum and IR and
NMR spectroscopic data. Its NMR spectra indicate
that the cyclization occurred at the C(CO2Me)2 and
CHPh centers of h3-TMM. Thus, the 1H NMR
The observed lack of reactivity between the h3-TMM
ligand of 8 and electrophilic alkenes and alkynes
suggested that the more polarized unsaturated species
such as isocyanates might be better reagents for the
desired cycloaddition. Isocyanates have been found to
spectrum shows the presence of an exocyclic CÄ
/
CH2,
2
double bond (d 5.60, dd; d 5.33, dd; JHH
ꢁ
/
1.93 Hz,
4JHH
2.25 Hz). As expected, the two carbomethoxy groups are
ꢁ
/
2.25 Hz) and an allylic proton (d 5.83, t, 4JHH
ꢁ
/
inequivalent and resonate as two singlets at d 3.79 and

R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ
/290
289
3.77. The 13C{1H} NMR spectrum is characterized of a
five-membered lactam substrate, with three carbonyl
resonances being observed: at d 165.3 and 165.2 for the
two carbomethoxy groups, and at d 164.5 for the amide
13P{1H} resonances with similar values of JPtP. The
aforementioned data compare well with those for the
adduct derived from 8 and TCNE, which has been
assigned the same type of structure [10].
carbonyl group [39]. The presence of an exocyclic CÄ
/
CH2 bond is confirmed by the appearance of two
olefinic resonances, at d 144.9 and 118.6. The structure
of 13 is similar to that proposed for the organic
cycloadducts
CH2C(NR)CHPh) (Rꢁ
TSI [8].
obtained
from
4-MeC6H4, 4-NO2C6H4) and
(PPh3)2Pt(h3-
/
In order to test the generality of the aforementioned
behavior of platinum h3-TMM complexes toward un-
saturated electrophiles we endeavored to extend this
study to the methyl-substituted analog of 8, viz.,
(PPh3)2Pt(h3-CH2C(C(CO2Me)2)CHMe) (7). This com-
plex was prepared in 75% yield by treatment of a
mixture of (PPh3)2Pt(C2H4) and NaCH(CO2Me)2 with
ð9Þ
The behavior of 7 toward fumaronitrile, shown in Eq.
(10), is similar to that of 8 toward diethyl fumarate.
After a solution of 7 and fumaronitrile in benzene had
been stored for 44 h at r.t., known (PPh3)2Pt(h2-trans-
MeCÅ
/
CCH2OTs, and was characterized by elemental
NCCHÄ
/
CHCN) (15) [34] was crystallized from the
analysis and H, 13C{1H} and 31P{1H} NMR spectro-
scopy. Its spectroscopic properties (cf. Section 2.7) show
features that are similar to those of 8 and the h3-2-
1
reaction mixture and characterized by H and 31P{1H}
NMR spectroscopy. Evaporation of the remaining
1
solution afforded the organic cycloadduct 16, which
1
alkoxyallyl
and
h3-2-aminoallyl
complexes
showed H NMR signals of the exocyclic Ä
/
CH2 at d
1.3 Hz and the
[(PPh3)2Pt(h3-CH2C(OR)CHMe)]ꢂ and [(PPh3)2Pt(h3-
CH2C(NR2)CHMe)]ꢂ, respectively [9]. The proposed
anti disposition of the C(CO2Me)2, and Me groups on
the h3-CH2C(C(CO2Me)2)CHMe ligand receives evi-
2
5.49 and 4.88 as doublets with JHH
ꢁ
/
2
signal of CHMe at d 2.27 as a quartet with JHH
ꢁ7.1
/
Hz, in addition to the methyl signals of CO2Me and
CHMe at d 3.25 and 0.75, respectively. Unlike 10,
which readily isomerized to 11 upon attempted chro-
matography on silica gel, 16 decomposed during such
treatment.
1
dence from selective H NMR decoupling experiments.
Thus, irradiation at the frequency of the CHMe and
syn-CHH protons (d 4.0) collapses the apparent septet
at d 1.05, assigned to CHMe, to a doublet. The doublet
splitting is attributed to JPH that involves one PPh3
phosphorus and suggests an anti position of the Me
group. The anti proton of CH2 resonates as a doublet
(JPH
ꢁ/9.5 Hz) with platinum-195 satellites (JPtH
ꢁ61.5
/
Hz) at d 2.40. Furthermore, as for 8, the two carbo-
methoxy methyl groups are equivalent and give rise to a
sharp singlet at d 3.52. The carbomethoxy carbonyl and
methyl groups also produce one 13C resonance each, at
ð10Þ
d 170.3 (t, JPC
ꢁ11.7 Hz) and 50.0 (s), respectively.
/
Reaction of 7 with 1 equiv. of TCNE in benzene at r.t.
afforded a 1/1 adduct of the reactants, 14, which was
characterized by chemical analysis and NMR spectro-
scopy as a platinum(0) alkene complex, with the alkene
being derived by [3ꢂ2] cycloaddition of TCNE to the
/
h3-TMM ligand (Eq. (9)). The 1H NMR spectrum of 14
shows a multiplet signal at d 4.48, assigned to the
The reaction of 7 with 3 equiv. of TSI at r.t. proceeds
analogously to the corresponding reaction of 8 (cf. Eq.
(8)). Accordingly, the products are the platinum com-
exocyclic Ä/CHMe, and resonances at d 3.2 and 2.3 with
a large geminal JHH (14.8 Hz), assigned to the ring CH2.
In the 13C{1H} NMR spectrum, signals are observed for
all of the inequivalent carbon atoms: two for each of
CO2Me, CO2Me and C(CN)2, and four for CN.
Olefinic carbon atoms resonate, as expected, at d 63.3
plex 12 and the [3ꢂ
2] cycloadduct of h3-TMM and TSI,
17. The NMR spectra of 17 compare closely with those
/
of 13. Especially noteworthy is the occurrence of two
proton signals for each of Ä
/
CH2 and CO2Me and of two
13C signals for each of CO2Me and CO2Me, with the
chemical shifts very similar to those in the spectra of 13.
(Ä
/
CHMe) and 53.1 (Ä
/
C), the former with a large JPtC of
405 Hz. Coordination of an unsymmetrical alkene to
platinum(0) is also indicated by the appearance of two

290
R.T. Dunsizer et al. / Inorganica Chimica Acta 342 (2003) 279ꢃ290
/
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Organomet. Chem. 65 (1974) 253.
The resonances of NCO and CÄ
/
CH2, also appear in
expected positions [39,40].
In summary, our studies revealed two patterns of
reactivity of the h3-TMM complexes (PPh3)2Pt(h3-
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(1975) 1710.
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unsaturated electrophiles. The weaker electrophiles
diethyl fumarate and fumaronitrile afford [3ꢂ3] cou-
/
pling of the h3-TMM ligand and coordination of the
electrophile (E) to platinum to give (PPh3)2PtE. Strong
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electrophiles/polarophiles, TCNE and TSL, give [3ꢂ2]
/
cycloaddition of the electrophile to h3-TMM, and this
cycloadduct has been isolated either free or complexed
to platinum.
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