Synthesis of new (σ2-N,N′-diazadiene)(η2-alkene) platinum(0) compounds

Article abstract of DOI:10.1016/S0020-1693(01)00676-4

Novel, thermally stable, dark-red to orange Pt⁰(σ²-N,N′-diazadiene) (η²-alkene) compounds have been synthesized in good yields from Pt⁰(COD)₂ or Pt⁰(NBE)₃, by stepwise substitution of the respective dienes or alkenes by an electron-poor alkene (dimethyl fumarate, maleic anhydride or fumaronitrile), followed by the appropriate diazadiene ligand in dry diethyl ether at 20°C (diazadiene = various N,N′-disubstitued-1,4-diaza-1,3-dienes). The complex Pt(DBA)₂ is less suited as a precursor for the synthesis of Pt⁰(σ²-N,N′-diazadiene) (η²-alkene) compounds. These zerovalent Pt(diazadiene)(η²-alkene) compounds constitute a useful category of starting materials for synthetic organoplatinum chemistry and catalysis.

Full text of DOI:10.1016/S0020-1693(01)00676-4

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Inorganica Chimica Acta 327 (2002) 90–97
Synthesis of new (s2-N,N%-diazadiene)(h2-alkene)platinum(0)
compounds
Dorette S. Tromp, Marcel A. Duin, Alexander M. Kluwer, Cornelis J. Elsevier *
Institute of Molecular Chemistry, Coordination and Organometallic Chemistry, Uni6ersiteit 6an Amsterdam, Nieuwe Achtergracht 166,
1018 WV Amsterdam, The Netherlands
Received 30 April 2001; accepted 14 August 2001
Dedicated to Professor Dr Kees Vrieze in recognition of his many outstanding contributions to organometallic and coordination chemistry,
for his guidance and for his friendship during the many fruitful years we worked together
Abstract
Novel, thermally stable, dark-red to orange Pt0(s2-N,N%-diazadiene)(h2-alkene) compounds have been synthesized in good
yields from Pt0(COD)2 or Pt0(NBE)3, by stepwise substitution of the respective dienes or alkenes by an electron-poor alkene
(dimethyl fumarate, maleic anhydride or fumaronitrile), followed by the appropriate diazadiene ligand in dry diethyl ether at
20 °C (diazadiene=various N,N%-disubstitued-1,4-diaza-1,3-dienes). The complex Pt(DBA)2 is less suited as a precursor for the
synthesis of Pt0(s2-N,N%-diazadiene)(h2-alkene) compounds. These zerovalent Pt(diazadiene)(h2-alkene) compounds constitute a
useful category of starting materials for synthetic organoplatinum chemistry and catalysis. © 2002 Elsevier Science B.V. All rights
reserved.
Keywords: Bidentate nitrogen ligands; Low-valent platinum compounds; Pt(diazadiene) compounds; Pt(alkene) compounds
1. Introduction
reactivity [7–9]. Nowadays, many examples of late
transition metal complexes in low oxidation states con-
taining bidentate nitrogen ligands, such as 1,10-phenan-
throline, pyridine-carbaldimine (Pyca) derivatives,
N,N%-disubstituted-1,4-diazabutadiene (R-DAB) and
bis(arylimino)acenaphthene (Ar-BIAN) ligands, to
name just a few, are known. Pioneering work regarding
the coordination chemistry of diaza(buta)dienes has
been carried out notably by Vrieze and van Koten, tom
Dieck, Schurig, Fru¨hauf, and quite a number of R-
DAB-complexes of low-valent transition metals, often
with CO as co-ligand, have been prepared (for a few
examples, see Fig. 1) [1–3].
As shown by several groups, chelating bidentate ni-
trogen ligands are valid alternatives to phosphines and
phosphites as stabilizing entities for the synthesis of
zerovalent compounds containing a Group 8, 9 or 10
metal atom [1–6] and useful directing ligands in their
An early publication by Cavell et al. [4] reports the
isolation of mononuclear zerovalent Pd0(R-DAB)(h2-
alkene) (A, Fig. 2) for various R and electron-poor
alkenes. In many cases, Pd0(R-DAB)(L) complexes
derived from open-chain R-DAB exist as mononuclear
species with the R-DAB acting as a bidentate chelating
entity, notably when the stoichiometry of Pd, R-DAB
and alkene is 1:1:1. Dinuclear compounds with a bridg-
ing R-DAB ligand are obtained in quite a number of
Fig. 1. Some examples of transition-metal diazadiene compounds.
* Corresponding author. Fax: +31-20-525 6456.
E-mail address: else4@anorg.chem.uva.nl (C.J. Elsevier).
0020-1693/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0020-1693(01)00676-4

D.S. Tromp et al. / Inorganica Chimica Acta 327 (2002) 90–97
91
been synthesized, e.g. Pt11X2(diazadiene)(h2-alkene)
and similar compounds [7].
The interest in our group in low-valent Group 10
metal compounds containing chelating N-ligands, espe-
cially palladium compounds containing the rigid Ar-
BIAN ligand (B, Fig. 2), stems largely from their
excellent suitability as (pre)catalysts for a number of
selective carbon–element coupling reactions [9], such as
Suzuki/Negishi type CꢀC bond formation [9a,b], three-
component coupling reactions [9b–d] and stereoselec-
tive cis-hydrogenation of alkynes (Scheme 1) [9e].
For modelling purposes of some of these palladium-
catalyzed reactions and for several other reactions cur-
rently under investigation, we needed a series of
zerovalent platinum compounds similar to A, i.e. con-
taining the simple diimine motif. Contrary to the palla-
dium case, the number of known zerovalent platinum
compounds containing bidentate N-ligands is not very
large, but several Pt0(NN) compounds have been re-
ported in the literature [5a,6]. Examples are Pt0(R-
DAB)(h2-alkene) [6a,b], water–soluble analogues
containing chiral substituents on the N-atoms, based on
Fig. 2. Generic structures of zerovalent Pd(diazadiene)(h2-alkene)
and Pd(Ar-BIAN)(h2-alkene) compounds.
a-D
-mannose [6c,d], and Pt0(Phen)(h2-alkene) [6e].
In this paper we describe the efficient synthesis of
Scheme 1. Stereoselective Pd(BIAN)-catalyzed cis-hydrogenation of
alkynes to (Z)-alkenes.
new Pt0(diazadiene)(h2-alkene) complexes of the gen-
eral formula A (Fig. 2), prepared from readily available
Pt0 precursors, various diazadiene ligands and electron-
poor alkenes. The complexes obtained are relevant as
an (alternative) entry into systems which are capable of
carbon–element bond-forming (e.g. hydrosilation),
bond-breaking and bond-activation reactions (e.g. CꢀH
activation) [9,10].
2. Results and discussion
2.1. Synthesis
The R-DAB ligands 1a–e and similar diazadienes
1f–k (Fig. 3) have been synthesized according to litera-
ture by condensation of glyoxal or 2,3-butadione with
the appropriate primary amine [11].
Synthesis of zerovalent platinum compounds of these
diazadiene ligands was attempted starting from the
readily available Pt0 precursors Pt(DBA)2 [12a] and
(Pt(dipDBA)2 [12b], using dimethyl fumarate (DMFU,
x), maleic anhydride (MA, y) or fumaronitrile (FN, z)
as the alkene according to Eq. (1). In all cases, first the
alkene was allowed to react with the platinum reagent
in dry diethyl ether for a given period of time and then
the diazadiene was added in portions. Since the DBA
ligands are rather sluggishly substituted, the norbor-
nene complex Pt(NBE)3 and the cyclooctadiene com-
plex Pt(COD)2 were prepared.
Fig. 3. Diazadienes and zerovalent Pt(diazadiene)(h2-alkene) com-
pounds relevant to this study.
cases as well, for instance, see Refs. [1,4], especially in
the presence of more than 1 equiv. of alkene per
palladium, and in some cases upon oxidative addition
(e.g. of methallyl chloride to Pd0(R-DAB)(h2-alkene)).
At a later stage, several other Pd0(diazadiene)(h2-olefin)
compounds have been reported [5].
Furthermore, numerous divalent palladium and plat-
inum compounds containing the diazadiene entity have
[Pt0(L)n]+alkene“[Pt0(L)n−1(h2-alkene)]+L
(1a)

92
D.S. Tromp et al. / Inorganica Chimica Acta 327 (2002) 90–97
Table 1
Yields of Pt0(diazadiene)(h2-alkene) compounds synthesized from various precursors a
Compound
R
R%
E
Precursor
Yield (%)
2ax
2ax
2ax
2ax
2ay
2bx
2cx
2dx
2dx
2dx
2dz
2ex
2fx
2gx
2hx
2hy
H
H
H
H
H
H
H
H
H
H
H
H
CH3
CH3
CH3
CH3
i-Pr
i-Pr
i-Pr
i-Pr
i-Pr
n-Bu
t-Bu
p-tolyl
p-tolyl
p-tolyl
p-tolyl
p-anisyl
cyclopropyl
n-Bu
CO2Me
CO2Me
CO2Me
CO2Me
C(O)OC(O)
CO2Me
CO2Me
CO2Me
CO2Me
CO2Me
CN
CO2Me
CO2Me
CO2Me
CO2Me
C(O)OC(O)
Pt(DBA)2
Pt(dipDBA)2
Pt(NBE)3
Pt(COD)2
Pt(COD)2
Pt(COD)2
Pt(COD)2
Pt(DBA)2
Pt(NBE)3
Pt(COD)2
Pt(DBA)2
Pt(COD)2
Pt(COD)2
Pt(COD)2
Pt(COD)2
Pt(COD)2
56 b
0
43
77 c
80
7
47
0
64
49
6
15
91
56
24
19
n-octyl
n-octyl
a According to Eq. (1).
b Purified by column chromatography.
c Isolated via Pt(COD)(DMFU).
[Pt0(L)n−1(h2-alkene)]+diazadiene
Pt0(COD)(h2-alkene) is formed within 10–20 min at
20 °C. This could be verified by isolation and charac-
terization of Pt(COD)(DMFU) [13]. The subsequent
reaction of this complex with diimines was fast and
selective and resulted in Pt0(diazadiene)(DMFU) com-
pounds 2ax–2hy. Similar reactions were carried out
using maleic anhydride or fumaronitrile for a few cases,
see Table 1.
In all cases the complexes could simply be purified by
evaporating the solvent and free COD and, addition-
ally, one washing with pentane. No column chromatog-
raphy or repeated washing was necessary to obtain pure
complexes in these instances and the yields were gener-
ally good.
The complexes 2ax–2hy are dark-red to orange
solids, which are stable in air for a long time. Appar-
ently, the exchange of the COD, compared to substitu-
tion of DBA, is much faster and is accompanied by
almost no decomposition of the Pt0 precursor. Further-
more, we have evaluated Pt(NBE)3 for the synthesis of
the Pt0(diazadiene)(h2-alkene) complexes. The results
for Pt(NBE)3 were comparable to the results for Pt-
(COD)2. Hence, Pt(COD)2 and Pt(NBE)3 are to be
preferred as the starting materials. Since the former is
obtained via the latter, application of Pt(NBE)3 seems
to be more economic. However, Pt(COD)2 is the more
stable of the two.1
“[Pt0(diazadiene)(h2-alkene)]+(n−1)L
(1b)
Employing diazadiene ligands 1a–1h resulted in the
ready formation of the corresponding 1:1:1 complexes
Pt0(diazadiene)(h2-alkene) 2ax–2hy (Fig. 3), albeit
the ease of work-up and the yields varied drastically,
as described below. When using Pt(DBA)2 or
Pt(dipDBA)2 as a Pt0 precursor, long reaction times
were necessary for the substitution to go to completion
for all the complexes investigated. Compounds 2dx,
2dz, 2jx, 2jz, 2kx and 2kz were obtained in very low
yields or could not be isolated using this method. Also,
because of the slow substitution of DBA and dipDBA
by the diazadiene ligand, much metallic platinum was
formed in most cases. Furthermore, the similar solubil-
ity properties of DBA and the target compounds posed
difficulties in purification of the complexes. Upon re-
peated washing with pentane, all of the DBA could be
removed, but altogether, the yields of the reactions
employing these precursors were rather low. Column
chromatography on alumina, eluting with toluene, gave
a good separation and provided the pure complex 2ax
in much higher yield (56%) as compared to washing the
crude product with pentane (17%). Column chromatog-
raphy also gave a reasonable to good yield for 2dx, but
represents a rather tedious and time-consuming work
up procedure. Especially because of the long reaction
times required for reactions with Pt(DBA)2 (which in
several cases led to very low or no yield at all), we
decided to apply Pt0 precursors containing more substi-
tution-labile ligands, such as Pt(COD)2 and Pt(NBE)3
[6b,13]. Typically, Pt(COD)2 was reacted with the ap-
propriate alkene in diethyl ether whereupon
1 Pt(COD)2 can be safely stored under N2 at 20 °C for a long time
and can be handled in air, whereas Pt(NBE)3 has to be stored for
only a limited period under N2 at −20 °C in the presence of some
free norbornene to prevent decomposition.

D.S. Tromp et al. / Inorganica Chimica Acta 327 (2002) 90–97
Table 2 (Continued)
93
Table 2
1H NMR data of the Pt0(diazadiene)(h2-alkene) complexes a
2hy
2.06 s
4.05 m,
3.53 s
NCH2
1.94 m,
Complex
R
R%
AlkeneꢁCꢀH R¦
3.53 d, 78
Hz
NCH2CH2
1.21 m,
2ax
8.90 s
1.60 d, 6.0
Hz, CH3
1.40 d, 6.6
Hz, CH3
4.06 m, CH
1.56 d, 6.3
Hz, CH3
1.49 d, 6.3
Hz, CH3
4.07 m, CH
4.07 m,
3.88 s
CH3(CH2)5
0.84 t,
CH3(CH2)5
8.90 d, 55
Hz
3.88 d, 86
Hz
3.60 s, CH3
a Recorded in CDCl3 at 293 K (either at 300.13 or 499.99 MHz).
The second line in the second and fourth columns refers to 195Pt-
satellites.
2ay
2bx
8.86 s
3.76 s
8.86 d, 61
Hz
3.76 d, 81
Hz
b Recorded in CDCl3 at 293 K at 300.13 MHz.
8.74 s
3.88 s
2.2. Analysis
NCH2
8.74 d, 58
Hz
2.03 m,
NCH2CH2
1.38 m,
CH3CH2
0.97 t,
CH2CH3
3.88 d, 87
Hz
3.61 s, CH3
The compounds 2ax–2hy have been analyzed by
means of standard 1H and 13C NMR techniques,
infrared, FAB MS, and (in several cases) by elemental
analysis. All compounds showed the expected isotopic
pattern in the mass spectra of their molecular ions for
monomeric Pt0(diazadiene)(h2-alkene) complexes. The
NMR data (Table 2) are in agreement with the pro-
posed structures. A normal low-frequency shift of the
CH3-imine, of the alkene protons and alkene carbon
nuclei was observed. The usual high-frequency shift was
observed for the imine protons and NꢁC carbon nuclei.
2cx
2dx
8.93 s
8.93 d, 53
Hz
1.58 s, CH3 3.78 s
3.78 d, 73
3.58 s, CH3
3.52 s, CH3
Hz
4.01 s
9.22 s
2.36 s,
ArCH3
9.22 d, 52
Hz
7.05 d, 8.1
Hz, ArH
7.62 d, 8.7
Hz, ArH
2.35 s,
4.01 d, 84
Hz
Coupling constants J(195Pt, H) and J(195Pt, 13C) are
similar to values found in the literature for other
Pt(N,N-chelate)(h2-alkene) complexes [5a,6]. IR spectra
(selected compounds, see Section 4) showed a shift of
the w(CꢁN) stretch vibration from about 1630 cm−1 for
the uncoordinated diazadiene ligand to values around
1550 cm−1 for the complexes, in agreement with the
literature [11a,14].
n
1
n
2dz
2ex
9.16 s
3.01 s
ArCH3
9.16 d, 48
Hz
7.23 d, 9.9
Hz, ArH
7.72 d, 8.1
Hz, ArH
3.54 s,
3.01 d
89.4 Hz
3.97 s
9.12 s
OCH3
9.12 d, 52
Hz
7.72 d, 9.0
Hz, ArH
6.73 d, 9.3
Hz, ArH
2.45 m, CH 4.17 s
2.09 m,
CH2
1.71 m,
CH2
4.07 m,
NCH2
1.88 m,
NCH2CH2
1.44 m,
CH3CH2
0.98 t,
CH3CH2
4.03 m,
NCH2
3.97 d, 85
Hz
3.83 s, CH3
3.60 CH3
3. Conclusions
2fx b
2gx
0.98 s
1.88 s
4.17 d, 81
Hz
Novel, thermally stable Pt0(diazadiene)(h2-alkene)
complexes have been synthesized in good yield from
Pt0(COD)2 or Pt0(NBE)3 as a Pt0 precursor, via step-
wise substitution of the labile alkenes by an electron-
poor alkene, followed by the appropriate diazadiene
ligand. The exchange of DBA and dipDBA, when using
Pt(DBA)2 or Pt(dipDBA)2, with the alkenes and diaza-
diene-ligand is slow, much metallic platinum is formed,
and separation of the Pt(0)-complex from DBA or
dipDBA is difficult, resulting in very low yields of the
desired complexes. The Pt0(diazadiene)(h2-alkene) com-
plexes are dark-red to orange compounds and can, as
solids, be safely handled and stored in air without
decomposition. Normal coordination-induced shifts
and coupling constants of Pt to the diazadiene ligand
and alkene are observed in their NMR spectra and the
expected shifts of the asymmetric CꢁN stretching mode
3.66 s
3.66 d, 87
Hz
3.57 s, CH3
2hx
1.95 s
3.67 s
1.94 m,
NCH2CH2
1.31 br,
CH3(CH2)5
0.85 t,
3.67 d, 88
Hz
3.58 s, CH3
CH3(CH2)5

94
D.S. Tromp et al. / Inorganica Chimica Acta 327 (2002) 90–97
are observed in the IR spectra. The compounds ob-
tained are members of a very useful category of starting
materials for various endeavors in synthetic organoplat-
inum chemistry and catalysis. Not only may these be
employed in oxidative additions of organic halides, to
give models for related CꢀC bond forming Pd-catalysts,
but also, by addition of appropriate acids, provide an
alternative approach to systems suitable for activation
of CꢀH bonds [10,15].
4.2.2. 5,8-Diaza-dodeca-5,7-diene
(N,N%-di-n-butylDAB; 1b)
13C NMR (CDCl3): l 162.0 (HCꢁN), 61.3 (NCH2),
32.7 (CH2), 20.5 (CH2), 13.9 (CH3).
4.2.3. 3,6-Diaza-2,2,7,7-tetramethyl-octa-3,5-diene
(N,N%-t-butylDAB; 1c)
13C NMR (CDCl3): l 158.0 (HCꢁN), 58.3 (C(CH3)),
29.5 (CH3).
4.2.4. 1,4-Di(4-methylphenyl)-1,4-diaza-1,3-butadiene
(N,N%-di-p-tolylDAB; 1d)
4. Experimental
13C NMR (CDCl3): l 159.3 (HCꢁN), 147.8+138.4
(ArCH), 130.3+121.6 (ArCH), CH3 21.4.
4.1. General
4.2.5. 1,4-Di(4-methoxyphenyl)-1,4-diaza-1,3-butadiene
(N,N%-di-p-anisylDAB; 1e)
All reactions were carried out under nitrogen atmo-
sphere in dry solvents. Acetone was distilled from
CaSO4. Diethyl ether, THF and toluene were distilled
from sodium metal and dichloromethane was distilled
from CaH2. Chemicals were purchased from Acros
13C NMR (CDCl3): l 160.0 (ArCꢀN), 157.8 (CHꢁN),
123.3 (ArCH), 114.8 (ArCH), 55.7 (OCH3).
4.2.6. 5,8-Diaza-6,7-dimethyl-dodeca-5,7-diene
(N,N%-di-n-butylDAB-Me; 1g)
1
Chimica, Aldrich and Fluka. The H and 13C NMR
1
spectra were recorded at appropriate frequencies in
Varian Mercury 300 and Varian Inova 500 spectrome-
ters. The IR spectra were recorded in a BioRad FTS-7
spectrometer. Elemental analyses were carried out by
Kolbe, Mikroanalitisches Laboratorium, Mu¨lheim a.d.
Ruhr, Germany.
IR (KBr, cm−1): 1636 (CꢁN). H NMR (CDCl3): l
2.01 (s, 6H, NꢁC(CH3)), 3.38 (t, 4H, J(1H–1H)=7.1
Hz, NCH2), 1.62 (p, 4H, NCH2CH2), 1.39 (s, 4H,
CH3CH2), 0.92 (t, 6H, CH2CH3). 13C NMR (CDCl3): l
167.8 (NꢁC(CH3)), 52.2 (NCH2), 33.1 (NCH2CH2),
20.8 (CH2CH3), 14.0 (CH2CH3), 12.5 ((CH3)CꢁN).
Compounds 1a–1f, 1j are known [11,15], 1g–1i, 1k
and 2a–2h (x, y, z) are new compounds. Synthesis and
selected spectral data of these compounds are given
below.
4.2.7. 9,12-Diaza-10,11-dimethyl-eicosa-9,11-diene
(N,N%-di-n-octylDAB-Me; 1h)
1
IR (KBr, cm−1): 1635 (CꢁN). H NMR (CDCl3): l
2.03 (s, 6H, NꢁCꢀCH3), 3.40 (t, 4H, J(1H–1H)=7.2
Hz, NCH2), 1.32 (br, 10H, CH3(CH2)5), 0.87 (t, 6H,
CH3(CH2)5). 13C NMR (CDCl3): l 168.0 (NꢁC(CH3)),
52.9 (NCH2), 32.1 (NCH2CH2), 31.0+29.6+27.9+
22.9 (CH2), 14.3 (CH3), 12.8 ((CH3)CꢁN).
4.2. Synthesis of R-DAB and other diazadiene ligands
The syntheses were carried out in analogy to Ref.
[11]: 2 equiv. of the primary amine was stirred in
MeOH at 0 °C with 1 equiv. of glyoxal (30% in H2O),
or in dry MeOH at 20 °C with 1 equiv. of 2,3-buta-
dione. A catalytic amount of formic or p-toluene sul-
fonic acid was added for condensations with
2,3-butadione. Upon completion of the reaction, solid
diazadiene ligands were filtered off and washed. For
liquid diazadiene ligands, the solvent was evaporated
and the diazadiene distilled if necessary. Yields of new
diazadiene ligands 1g: 98%, 1i: 41%, 1k: 64%. The
NMR and some IR data of the diazadiene ligands
1a–1k which have not yet been published have been
compiled below.
4.2.8. 6,9-Diaza-7,8-dimethyl-tetradeca-1,6,8,13-
tetraene (N,N%-di(4-pentenyl)DAB-Me; 1k)
1H NMR (CDCl3): l 2.22 (s, 6H, NꢁC(CH3)), 4.13
(m, 4H, NCH2), 5.75 (m, 2H, CH2ꢁCH), 5.09 (m, 4H,
CH2ꢁCH), 2.13 (m, 4H, ꢁCHCH2ꢀCH2), 1.59 (m, 4H,
ꢁCHCH2CH2). 13C NMR (CDCl3): l 136.2 (CHꢁCH2),
125.6 (NꢁC(CH3)), 116.9 (CHꢁCH2), 45.5 (NCH2),
30.6 (ꢁCHCH2), 28.8 (NCH2CH2), 9.1 (CH3).
4.2.9. Pt0 precursors
The Pt0 precursors employed were synthesized ac-
cording to literature procedures: platinum dibenzylide-
neacetone (Pt(DBA)2) [12a], platinum diisopropyl-
dibenzylideneacetone (Pt(dipDBA)2) [12b], platinum
trisnorbornene (Pt(NBE)3) [16a] from Pt(COD)Cl2 ob-
tained according to Ref. [17], platinum bis(cyclooctadi-
ene (Pt(COD)2) [16a,16b] and platinum(cyclooctadiene)
dimethylfumarate (Pt(COD)(DMFU)) [13].
4.2.1. 3,6-Diaza-2,7-dimethyl-octa-3,5-diene
(N,N%-diisopropylDAB; 1a)
IR (KBr, cm−1): 1623 (CꢁN). 13C NMR (CDCl3): l
159.5 (HCꢁN), 61.1 (CH), 23.7 (CH3).

D.S. Tromp et al. / Inorganica Chimica Acta 327 (2002) 90–97
95
4.3. Synthesis of [Pt0(diazadiene)(p2-alkene)]
compounds
4.3.5. (|-N,|-N%-5,8-Diaza-dodeca-5,7-diene)-
(p2-(E)-dimethylbut-2-ene-1,4-dioate)platinum(0) (2bx)
1H NMR (CDCl3): l 8.74 (s, 2H, NꢁCH), 8.74 (d, 2H,
3J(195Pt–1H)=58.5 Hz, NꢁCH), 4.05 (m, 4H, NCH2),
3.88 (s, 2H, HCꢁCH), 3.88 (d, 2H, 2J(195Pt–1H)=87 Hz,
HCꢁCH), 3.61 (s, 6H, OCH3), 2.03 (m, 4H, NCH2CH2),
1.38 (s, 4H, CH2CH3), 0.97 (t, 6H, CH2CH3).
4.3.1. A. Using Pt(DBA)2 or Pt(dipDBA)2
An amount of 1.0 equiv. of Pt0 precursor and 1.0–1.5
equiv. of the appropriate alkene (DMFU, MA or FN)
were stirred in dry diethyl ether at 20 °C under N2 for
10 min. An amount of 1 equiv. of the diazadiene ligand
was then added in small portions to this solution. After
stirring at 20 °C during 12–24 h, the reaction mixture
was filtered over Celite, the solvent evaporated and the
residue washed several times with pentane. The complex
was then purified by column chromatography on Al2O3
(deactivated with 7% H2O, eluting with toluene, followed
by dichloromethane) and evaporation of the solvent.
4.3.6. (|-N,|-N%-3,6-Diaza-2,2,7,7-tetramethyl-octa-
3,5-diene)(p2-(E)-dimethylbut-2-ene-1,4-dioate)-
platinum(0) (2cx)
1H NMR (CDCl3): l 8.92 (s, 2H, NꢁCH), 8.92 (d,
3J(195Pt–1H)=53 Hz, 2H, NꢁCH), 3.79 (s, 2H,
HCꢁCH), 3.79 (d2, J(195Pt–1H)=73.2 Hz, 2H, HCꢁCH),
3.58 (s, 6H, OCH3), 1.57 (s, 18H, CH3(t-Bu)). 13C NMR
(CDCl3): l 177.9 (CꢁO), 159.2 (CꢁN), 65.3 (C(CH3)3),
50.9 (OCH3), 30.0 (C(CH3)3), 25.7 (CꢁC), 25.7 (d,
J(195Pt–1H)=412.5 Hz, CꢁC).
4.3.2. B. Using Pt(NBE)3 or Pt(COD)2
The same procedure as above was followed up to and
including the addition of diazadiene, but using 1.0–1.1
equiv. of the alkene. After a reaction time of 1–2 h, the
solvent was evaporated in vacuo and the residue was
washed once with a small amount of pentane and dried
to yield the pure products.
4.3.7. (|-N,|-N%-1,4-Di(4-methylphenyl)-
1,4-diaza-1,3-butadiene)(p2-(E)-dimethylbut-2-ene-
1,4-dioate)platinum(0) (2dx)
1
FAB MS: M+=576.1. H NMR (CDCl3): l 9.22 (s,
2H, NꢁCH), 9.22 (d, 3J(195Pt–1H)=52 Hz, 2H, NꢁCH),
7.62 (d, J(1H–1H)=8.7 Hz, 8H, p-tolylH), 7.05 (d,
J(1H–1H)=8.1 Hz, 8H, p-tolylH), 4.01 (s, 2H,
4.3.3. (|-N,|-N%-3,6-Diaza-2,7-dimethyl-octa-
3,5-diene)(p2-(E)-dimethylbut-2-ene-1,4-dioate)-
platinum(0) (2ax)
2
HCꢁCH), 4.01 (d, J(195Pt–1H)=84 Hz, 2H, HCꢁCH),
FAB MS: M+=480.1. IR (KBr. cm−1): 1547 (CꢁN).
1H NMR (CDCl3): l 8.90 (s, 2H, NꢁCH), 8.90 (d,
3J(195Pt–1H)=55.5 Hz, 2H, NꢁCH), 4.05 (m, 2H, CH(i-
3.52 (s, 6H, CH3(COOMe)), 2.36 (s, 6H, CH3C6H4).
4.3.8. (|-N,|-N%-1,4-Di(4-methylphenyl)-
2
Pr)), 3.85 (s, 2H, HCꢁCH), 3.85 (d, J(195Pt–1H)=86.4
1,4-diaza-1,3-butadiene)(p2-(E)-1,2-dicyano-ethene)-
platinum(0) (2dz)
Hz, 2H, HCꢁCH), 3.59 (s, 6H, OCH3), 1.60 (d, J(1H–
1H)=6 Hz, 6H, (CH3)2CH), 1.38 (d, J(1H–1H)=6.3 Hz,
6H, CH3(i-Pr)). 13C NMR (CDCl3): l 177.7 (CꢁO), 177.7
(d, 2J(195Pt–13C)=56 Hz, CꢁO), 160.3 (CꢁN), 64.7
1H NMR (CDCl3): l 9.16 (s, 2H, NꢁCH), 9.16 (d,
3J(195Pt–1H)=48 Hz, 2H, NꢁCH), 7.72 (d, J(1H–1H)=
8.1 Hz, 8H, p-tolylH), 7.23 (d, J(1H–1H)=9.9 Hz, 8H,
p-tolylH), 3.01 (s, 2H, HCꢁCH), 3.01 (d, 2J(195Pt–1H)=
89.4 Hz, 2H, HCꢁCH), 2.35 (s, 6H, CH3(p-tolyl)).
2
(CH3)2CH, 64.7 (d, J(195Pt–13C)=73 Hz, CH(CH3)2),
1
51.0 (OCH3), 25.4 (CꢁC), 25.4 (d, J(195Pt–13C)=399
3
Hz, CꢁC), 24.05 ((CH3)2CH), 24.05 (d, J(195Pt–13C)=
13.4 Hz, (CH3)2CH), 23.7 ((CH3)2-CH). Elemental anal-
ysis: Calc. for C14H24N2O4Pt (479.14): C, 35.07; H, 5.05;
N, 5.84. Found: C, 34.98; H, 5.12; N, 5.79%.
4.3.9. (|-N,|-N%-1,4-Di(4-methoxyphenyl)-1,4-
diaza-1,3-butadiene)(p2-(E)-dimethylbut-2-ene-1,4-
dioate)platinum(0) (2ex)
1H NMR (CDCl3): l 9.12 (s, 2H, NꢁCH), 9.12 (d,
3J(195Pt–1H)=52.2 Hz, 2H, NꢁCH), 7.72 (d,
J(1H–1H)=9 Hz, 4H, ArH), 6.73 (d, J(1H–1H)=9.3
Hz, 4H, ArH), 3.97 (s, 2H, HCꢁCH), 3.97 (d,
2J(195Pt–1H)=85.2 Hz, 2H, HCꢁCH), 3.83 (s, 6H,
OCH3), 3.54 (s, 6H, CH3(p-anisyl)).
4.3.4. (|-N,|-N%-3,6-Diaza-2,7-dimethyl-octa-
3,5-diene)(p2-(Z)-but-2-ene-1,4-dicarboxylic acid
anhydride)platinum(0) (2ay)
1H NMR (CDCl3): l 8.86 (s, 2H, NꢁCH), 8.86 (d,
3J(195Pt–1H)=60.9 Hz, 2H, NꢁCH), 4.08 (m, 2H,
CH(CH3)2), 3.76 (s, 2H, HCꢁCH), 3.76 (d 3J(195Pt–
1H)=81 Hz, 2H, HCꢁCH), 1.56 (d, J(1H–1H)=6.3 Hz,
6H (CH3)2CH), 1.49 (d, J(1H–1H)=6.3 Hz, 6H,
(CH3)2CH). 13C NMR (CDCl3): l 175.4 (CꢁO), 161.3
(CꢁN), 65.5 ((CH3)2CH), 24.8 ((CH3)2CH), 24.4 (CꢁC),
24.4 (d, J(195Pt–13C)=237 Hz, CꢁC), 23.6 ((CH3)2CH).
Elemental analysis: Calc. C14H24N2O4Pt (479.14): C,
33.26; H, 4.19; N, 6.46. Found: C, 30.25; H, 3.64; N,
5.71%.
4.3.10. (|-N,|-N%-1,4-Dicyclopropyl)-1,4-
diaza-2,3-dimethyl-1,3-butadiene)(p2-(E)-dimethylbut-2-
ene-1,4-dioate)platinum(0) (2fx)
1
FAB MS: M+=504.1. H NMR (C6D6): l 4.17 (s,
2H, HCꢁCH), 4.17 (d, 2J(195Pt–1H)=81.3 Hz, 2H,
HCꢁCH), 3.60 (s, 6H, OCH3), 2.45 (m, 2H,
CH(cyclopr.)), 2.09 (m, 4H, CH2(cyclopr.)), 1.66 (m,
4H, H2(cyclopr.)), 0.98 (s, 6H, NꢁC(CH)3). 13C NMR

96
D.S. Tromp et al. / Inorganica Chimica Acta 327 (2002) 90–97
(b) A. Togni, L.M. Venanzi, Angew. Chem., Int. Ed. Engl. 33
(1994) 497.
[3] (a) H. Bock, H. tom Dieck, Chem. Ber. 100 (1967) 228;
(b) E. Bayer, E. Breitmaier, V. Schurig, Chem. Ber. 101 (1968)
1594;
(CDCl3): l 176.9 (CꢁO), 169.6 (CꢁN), 50.3 (OCH3),
38.7 (CH-cyclopropyl), 25.1 (CꢁC), 17.5 (NꢁC(CH3)),
12.6, 10.8 (2 CH2-cyclopropyl). Elemental analysis:
Calc. for C16H24N2O4Pt (503.45): C, 38.17; H, 4.88; N,
5.56. Found: C, 38.52; H, 4.75; N, 5.64%.
(c) H. tom Dieck, I.W. Renk, Chem. Ber. 104 (1971) 92;
(d) M. Svoboda, H. tom Dieck, C. Kru¨ger, Y.-H. Tsay, Z.
Naturforsch., Teil B 36 (1981) 814;
(e) H.-W. Fru¨hauf, F. Seils, R.J. Goddard, M.J. Romao,
Organometallics 4 (1985) 948;
4.3.11. (|-N,|-N%-5,8-Diaza-6,7-dimethyl-dodeca-
5,7-diene)(p2-(E)-dimethylbut-2-ene-1,4-dioate)-
platinum(0) (2gx)
(f) W.P. Mul, C.J. Elsevier, H.-W. Fru¨hauf, K. Vrieze, I. Pein,
M.C. Zoutberg, C.H. Stam, Inorg. Chem. 29 (1990) 2336.
[4] K.J. Cavell, D.J. Stufkens, K. Vrieze, Inorg. Chim. Acta 47
(1980) 67.
[5] (a) R. van Asselt, C.J. Elsevier, W.J.J. Smeets, A.L. Spek, R.
Benedix, Recl. Trav. Chim. Pays-Bas 113 (1994) 88;
(b) R. van Asselt, C.J. Elsevier, W.J.J. Smeets, A.L. Spek, Inorg.
Chem. 33 (1994) 1521;
FAB MS: M+=536.2. IR (KBr, cm−1): 1558 (CꢁN).
1H NMR (CDCl3): l 4.07 (m, 4H, NCH2), 3.66 (s, 2H,
2
HCꢁCH), 3.66 (d, J(195Pt–1H)=87 Hz, 2H, HCꢁCH),
3.57 (s, 6H, OCH3), 1.88 (m, 4H, NCH2CH2), 1.88 (s,
6H, NꢁC(CH3)), 1.44 (m, 4H, CH3CH2), 0.98 (t, J(1H–
1H)=6.9 Hz, 6H, CH3ꢀCH2). 13C NMR (CDCl3): l
177.6 (CꢁO), 170.0 (CꢁN), 59.0 (NCH2), 51.1 (OCH3),
32.6 (NCH2CH2), 25.7 (NꢁC(CH3)), 20.7 (CH3CH2),
17.6 (CꢁC), 14.2 (CH3CH2). Elemental analysis: Calc.
for C18H32N2O4Pt (535.6): C, 40.37; H, 6.02; N, 5.23.
Found: C, 40.29; H, 5.97; N, 5.14%.
(c) R.A. Klein, R. van Belzen, K. Vrieze, C.J. Elsevier, R.P.
Thummel, J. Fraanje, K. Goubitz, Coll. Czech. Chem. Commun.
62 (1997) 238;
(d) M.L. Ferrara, F. Giordano, I. Orabona, A. Panunzi, F.
Ruffo, Eur. J. Inorg. Chem. (1999) 1939;
(e) C. Boriello, M.L. Ferrara, I. Orabona, A. Panunzi, F. Ruffo,
J. Chem. Soc., Dalton Trans. (2000) 2545.
[6] (a) P. Overbosch, G. van Koten, O. Overbeek, J. Am. Chem.
Soc. 102 (1980) 2091;
4.3.12. (|-N,|-N%-9,12-Diaza-10,11-dimethyl-eicosa-
9,11-dience)(p2-(E)-dimethylbut-2-ene-1,4-dioate)-
platinum(0) (2hx)
(b) V. De Felice, A. De Renzi, F. Ruffo, D. Tesauro, Inorg.
Chim. Acta 219 (1994) 169;
(c) M.L. Ferrara, L. Orabona, F. Ruffo, Organometallics 17
(1998) 3832;
(d) F. Ruffo, A. de Renzi, A. Panunzi, Inorg. Synth. 32 (1998)
158;
(e) M. Bigioni, P. Ganis, A. Panunzi, F. Ruffo, C. Salvatore, A.
Vito, Eur. J. Inorg. Chem. (2000) 1717.
FAB MS: M+=648.3. IR (KBr, cm−1): 1558 (CꢁN).
1H NMR (CDCl3): l 4.06 (m, 4H, NCH2), 3.67 (s, 2H,
HCꢁCH), 3.67 (d, 2J(195Pt–1H)=88.2 Hz, 2H,
HCꢁCH), 3.58 (s, 6H, OCH3), 1.95 (m, 4H, NCH2-
CH2), 1.95 (s, 6H, NꢁC(CH3)), 1.31 (m(b), 20H,
CH3(CH2)5), 0.85 (t, 6H, CH3(CH2)5). 13C NMR
(CDCl3): l 177.6 (CꢁO), 170.0 (CꢁN), 59.3 (NCH2),
[7] (a) L. Maresca, G. Natile, M. Calligaris, P. Delise, L. Randac-
cio, J. Chem. Soc., Dalton Trans. (1976) 2386;
(b) A. De Renzi, A. Panunzi, A. Saporito, A. Vitagliano, Gazz.
Chim. Ital. 107 (1977) 549;
2
59.3 (d, J(195Pt–13C)=70.7 Hz, NCH2), 51.1 (OCH3),
32.0 (NCH2CH2), 30.6+29.6+27.6+22.9 (CH3-
1
(CH2)5), 25.7 (CꢁC), 25.7 (d, J(195Pt–13C)=370 Hz,
(c) H. van der Poel, G. van Koten, K. Vrieze, M. Kokkes, C.H.
Stam, J. Organomet. Chem. 175 (1979) C21;
(d) H. van der Poel, G. van Koten, J. Organomet. Chem. 187
(1980) C17;
CꢁC), 17.6 (NꢁC(CH3)), 14.3 (CH3(CH2)5).
(e) G. Albano, F. Demartin, A. De Renzi, G. Morelli, A.
Saporito, Inorg. Chem. 24 (1985) 2032;
(f) V. De Felice, M. Funicello, A. Panunzi, F. Ruffo, J.
Organomet. Chem. 403 (1991) 243;
(g) K. Yang, J. Lachicotte, R. Eisenberg, Organometallics 16
(1997) 5234;
(h) P.J. Albietz, K. Yang, J. Lachicotte, R. Eisenberg,
Organometallics 18 (2000) 3543;
4.3.13. (|-N,|-N%-9,12-Diaza-10,11-dimethyl-eicosa-
9,11-diene)(p2-(Z)-but-2-ene-1,4-dicarboxylic acid
anhydride)platinum(0) (2hy)
FAB MS: M+=602.3. 1H NMR (CDCl3): l 4.05
(m(b), 4H, NCH2), 3.53 (s, 2H, HCꢁCH), 3.53 (d,
1J(195Pt–1H)=78 Hz, 2H, HCꢁCH), 2.06 (s, 6H,
NꢁC(CH3)), 1.94 (m(b), 4H, NCH2CH2), 1.21 (m(b),
20H, CH3(CH2)5), 0.84 (t, 6H, CH3(CH2)5). 13C NMR
(CDCl3): l 175.5 (CꢁO), 171.6 (CꢁN), 59.4 (NCH2),
31.99 (NCH2CH2), 30.6+29.5+27.4+22.9 (CH3-
(CH2)5), 25.1 (CꢁC), 22.9, 17.9 (NꢁC(CH3)), 14.3
(CH3(CH2)5).
(i) G.F. Hill, L.M. Rendina, R.J. Puddephatt, J. Chem. Soc.,
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(c) M. Brookhart, F.C. Rix, J.M. DeSimone, J.C. Barborak, J.
Am. Chem. Soc. 114 (1995) 5894;
(d) L.K. Johnson, C.M. Killian, M. Brookhart, J. Am. Chem.
Soc. 117 (1995) 6414;
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