Synthesis and characterisation of the amidine complexes trans-[PtCl(NH 3){HNC(NH2)R}2]Cl (R = Me, Ph, CH 2Ph) derived from addition of NH3 to the coordinated nitriles in trans-[PtCl2(NCR)<s

Article abstract of DOI:10.1016/j.jorganchem.2005.01.005

The di-nitrile complexes trans-[PtCl₂(NCR)₂] (R = Me, Ph, CH₂Ph) react with an excess of gaseous NH₃ in CH ₂Cl₂ at -10 °C to form, in high yield, the corresponding di-amidine complexes tran

Full text of DOI:10.1016/j.jorganchem.2005.01.005

Journal of Organometallic Chemistry 690 (2005) 2121–2127
www.elsevier.com/locate/jorganchem
Synthesis and characterisation of the amidine complexes
trans-[PtCl(NH3){HN@C(NH2)R}2]Cl (R = Me, Ph, CH2Ph)
derived from addition of NH3 to the coordinated
nitriles in trans-[PtCl2(N„CR)2]
a,
a
b,
b
Giovanni Natile *, Francesco P. Intini , Roberta Bertani *, Rino A. Michelin ,
b
b
c
Mirto Mozzon , Silvia Mazzega Sbovata , Alfonso Venzo , Roberta Seraglia
c
a
`
Dipartimento Farmaco-Chimico, Universita di Bari, via E. Orabona 4, 70125 Bari, Italy
`
b
`
Dipartimento di Processi Chimici dellꢀIngegneria, Facolta di Ingegneria, Universita di Padova, Via Marzolo 9, 35131 Padova, Italy
Istituto di Scienze e Tecnologie Molecolari, Sezione di Padova, Consiglio Nazionale delle Ricerche, Via Marzolo 1, 35131 Padova, Italy
c
Received 23 December 2004; accepted 4 January 2005
Available online 8 February 2005
Abstract
The di-nitrile complexes trans-[PtCl2(N„CR)2] (R = Me, Ph, CH2Ph) react with an excess of gaseous NH3 in CH2Cl2 at ꢀ10 ꢀC
to form, in high yield, the corresponding di-amidine complexes trans-[PtCl(NH3){HN@C(NH2)R}2]Cl in which also one chlorine
ligand has been displaced by NH3. The H NMR spectra in DMSO showed the formation of different species which were charac-
1
terized through NOESY, TOCSY and 1H/13C heteronuclear correlations as trans-[Pt(NH3){HN@C(NH2)R}2(DMSO)]Cl2 and
trans-[PtCl{HN@C(NH2)R}2(DMSO)]Cl.
ꢁ 2005 Elsevier B.V. All rights reserved.
Keywords: Platinum; Nitriles; Amidines; Ammonia; Nucleophilic attack
1. Introduction
tallic gold–platinum cluster cations as catalyst [3]. The
use of Pt3O4 in the catalytic oxidation of ammonia to
NO for the industrial production of nitric acid [4] has
also been extensively studied. New hydrophobic fluori-
nated carbon supported Pt catalysts, promoting the
reaction of nitrogen oxides NOx with NH3, are investi-
gated in order to develop a very effective post combus-
tion De-NOx technology for controlling NOx
emissions [5]. The synthesis of methylamines from
CO2, H2, and NH3 has been reported to occur over
Pt-alumina catalysts, together with significant methane
formation [6]. Very recently, Cu2+ has been shown to
be an efficient catalyst in cycloaddition of nitriles and
ammonia to give Cu(I) triazolate derivatives according
to the following equation [7]:
The coupling of small molecules promoted by a metal
center is a relevant feature in biological processes as well
as in industrial chemistry [1,2]. In particular, there are
many synthetic heterogeneous and homogeneous pro-
cesses involving NH3. A first example is the HCN syn-
thesis by the Degussa process, in which a 1:1 mixture
of methane and ammonia is passed through a Pt-coated
tube-wall reactor, or by the related process using bime-
*
Corresponding authors. Tel.: ++39 49 8275731; fax: ++39 49
8275525.
E-mail address: roberta.bertani@unipd.it (R. Bertani).
0022-328X/$ - see front matter ꢁ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.01.005

2122
G. Natile et al. / Journal of Organometallic Chemistry 690 (2005) 2121–2127
This appears to be a consequence of the low steric hin-
R
drance of the NHR00 group, which can be easily accomo-
dated cis to the platinum moiety, with respect to the
C@N double bond. In the solid state the Z conformation
could also be stabilized by strong intramolecular Pt–Cl–
H–N hydrogen bonds forming pseudo six-membered
metallacycles [14]. In contrast, secondary amines give
rise to E amidines, which represent a more thermodinam-
ically stable configuration, placing the bulky NR0R00
group trans to the platinum moiety with respect to the
C@N double bond. In the case of the benzonitrile deriv-
atives, the addition of secondary amines usually leads to
a mixture of Z and E isomers because of the comparable
size of the two substituents on the azomethine carbon
atom (Ph and NR0R00). Similar considerations have
been made in the case of addition of alcohols to coordi-
nated nitriles to yield iminoether derivatives [15].
The reactions of cis- and trans-[PtCl2(N„CPh)2]
with N,N0-di-tert-butylethylenediamine were also
studied in detail [16] and found to yield cis-[PtCl2-
{HN@C(Ph)N(t-Bu)CH2CH2NH(t-Bu)}(N„CPh)] and
N
N
160 ˚C, 3 days
Cu2+
Cu+
+
+
2
R
C
N
NH3
N
R
n
ð1Þ
Tetrazoles and 1,3,5-triazine have also been formed by
reaction of an aldehyde with iodine in aqueous ammo-
nia forming a nitrile intermediate which reacts further
with sodium azide or dicyandiamine [8] to yield the final
product according to the following equation:
H
N
a) I2, NH3 (aq), room temperature
N
O
H
R
C
R
C
b) NaN3, ZnBr2, reflux
N
N
ð2Þ
Acetylenic nitriles are reported to give photochemical
addition of ammonia to form E and Z isomers of 3-ami-
no-2-propene nitrile by regioselective addition to the
C„C triple bond [9].
,
[Pt{HN=C(Ph)N(t-Bu)CH2CH2NH(t-Bu)}Cl(N≡CPh)]Cl
In this paper we describe the reaction of gaseous NH3
with the coordinated nitrile ligands in platinum(II) com-
plexes of the type trans-[PtCl2(N„CR)2] (R = CH3, Ph,
CH2Ph) [10]. At our knowledge, only very few examples
of such reactions have been previously reported. For in-
stance, liquid NH3 was reacted with [Pt(N„CNMe2)-
(dien)][CF3SO3]2 (dien = diethylentriamine) to form
quantitatively a guanidine complex according to the fol-
lowing equation [11]:
respectively. The X-ray structure of cis-[PtCl2-
{HN@C(Ph)N(t-Bu)CH2CH2NH(t-Bu)}(N„CPh)]
showed the amino-amidine ligand to have E configura-
tion with an extensive electron delocalisation within the
amidine group. The same compound undergoes, in
solution, facile E–Z isomerisation about the azomethine
double bond.
2. Results and discussion
½PtðNBCNMe2ÞðdienÞꢁ2þ þ 2NH3ðlÞ
! ½PtfHN@CðNH2ÞNMe2gðdienÞꢁ
2þ
2.1. Synthesis
ð3Þ
Crystals of the acetamide derivative cis-[Pt{1-Me-
Ty(H)}{MeC(NH)@NH2}(PMe3)2][X] (1-MeTy = 1-
methylthymine; X = NO3, ClO4) were isolated from an
acetonitrile solution of cis-[Pt{l-OH)(PMe3)2]2[X]2
(X = NO3, ClO4) and 1-MeTy in the presence of a small
amount of water, due to the addition of in situ formed
NH3 to the coordinated MeCN [12].
Diffusion of ammonia into a solution of mer-
[RhCl3(PhCH2CN)3] in neat benzyl cyanide was re-
ported to afford in high yield the amidine complex
mer-[RhCl3{HN@C(NH2)CH2Ph}3] [13].
The addition of primary and secondary aliphatic
amines HNR0R00 (R0 = H, Me, Et; R00 = Me, Et, t-Bu),
but not of ammonia, to cis- and trans-[PtCl2(N„CR)2]
(R = Me, Ph) to give mono- or di-amidine derivatives
of the type [PtCl2(N„CR){HN@C(R)NR0R00}] and
[PtCl2{HN@C(R)NR0R00}2], respectively, has previously
been reported [14]. In particular, primary amines add to
cis- and trans-[PtCl2(N„CMe)2] affording the di-ami-
dine complexes having exclusively Z conformation of
the ligands both in solution and in the solid state [14].
trans-[PtCl2(N„CR)2] (R = Me, Ph, CH2Ph) react
with NH3 (excess) in CH2Cl2 at ꢀ10 ꢀC to afford, in high
yield, the corresponding di-amidine derivatives accord-
ing to the following equation:
NH3ðexcÞ; ꢀ10 ꢂC
trans-½PtCl ðNBCRÞ ꢁ
ƒƒƒƒƒƒƒƒƒ!
2
2
trans-½PtClðNH3ÞfHN@CðNH2ÞRg2ꢁCl
ð4Þ
ðR ¼ Me; 1; Ph; 2; CH2Ph; 3Þ
Compounds 1–3 are white solids, which exhibit good
solubility in water, but are poorly soluble in common or-
ganic solvents such as CH2Cl2. They have been charac-
terised by elemental analysis, IR and NMR
spectroscopy. The IR spectra show C@N absorption
bands in the range 1639–1652 cmꢀ1 characteristic of
amidine ligands and complete absence of bands assign-
able to C„N stretchings. N–H stretchings appear in
the range 3511–3167 cmꢀ1
.
The reaction of [PtCl2(N„CMe)2] with NH3 was re-
ported long time ago [17] to afford a compound of for-
mula [Pt(NH3)4(N„CMe)2]Cl2 Æ H2O (known as

G. Natile et al. / Journal of Organometallic Chemistry 690 (2005) 2121–2127
2123
Tschugaevꢀs salt). Later on this compound was shown
by X-ray crystallography to be an amidine complex of
formula [Pt(NH3)2{HN@C(NH2)Me}]Cl2 Æ H2O [18].
Therefore, the main difference between our com-
pounds and the Tschugaevꢀs salt is the number of chlo-
rine ligands substituted by ammonia molecules, one in
our case, both of them in the case of Tschugaevꢀs salt.
Ammonia is known to be a good ligand for platinum
[19] with whom it forms a wide variety of compounds
some of which are good antiviral [20] and antitumor
[21] drugs.
When we started this investigation we hypothesized
that, lowering the temperature to ꢀ10 ꢀC, could have re-
tarded the substitution of chloride by the ammine, while
still allowing the nucleophilic addition of the ammonia
to the coordinated nitrile. However, this has not been
the case and even at ꢀ10 ꢀC one chloride is substituted
by the ammine.
field of the methyl proton resonance (d = 1.93 ppm). A
methyl signals at lower field (d > 2.3 ppm ) has been
observed in the case of amidines having E configuration
[14,22].
1
Four N–H proton resonances are observed in the H
NMR spectrum of compound 1 recorded immediately
after dissolution in DMSO (resonances A in Fig. 1).
The signal at 4.04 ppm is assigned to the ammine pro-
tons, the resonance at 6.50 ppm to the iminic proton
(C@N–H) and the resonances at 7.17 and 7.03 ppm to
the aminic protons (C–NH2). The initial set of signals
decreases rapidly with time simultaneously with the
appearance of a new set of signals which becomes dom-
inant after 20 min at 22 ꢀC (signals B in Fig. 1). The new
set of signals indicates that the new species still contains
a coordinated ammine (signal at 4.53 ppm) and coordi-
nated amidines with signals at 6.82 ppm (C@NH pro-
ton) and at 8.21 and 7.63 ppm (C–NH2 protons). The
chemical shift of the C–Me protons (2.09 ppm) also indi-
cates that the amidines have still Z configuration. The
latter set of signals is assigned to the solvated species
trans-[Pt(NH3){HN@C(NH2)Me}2(DMSO)]2+ as con-
firmed by an NMR experiment performed on the
DMSO solution and an ESI mass spectrum performed
on a sample of 1 kept in DMSO for the time required
to undergo solvolysis, then taken to dryness and the so-
lid residue dissolved in MeOH or i-Pr–OH. The NOESY
spectrum showed a cross peak between the ammine pro-
ton at 4.53 ppm and the C@N–H proton at 6.82 ppm
clearly indicating that the ammine is coordinated to
platinum and is cis to the amidine (see Fig. 2). The
ESI mass spectra showed the presence of ions at m/z
420 and m/z 449, respectively, corresponding to [Pt
(O–Me){HN@C(NH2)Me}2(DMSO)]+ and [Pt(O–i-Pr)-
{HN@C(NH2)Me}2(DMSO)]+, respectively.
2.2. NMR characterisation
Due to their poor solubility in common organic sol-
vents, NMR spectra suitable for detailed analysis have
been recorded in DMSO. The most significant feature
for compounds 1–3 is the formation in solution of differ-
ent solvated species, whose relative abundance changes
with time. Through NOESY, TOCSY and 1H/13C heter-
onuclear correlations it was possible to assign the signals
to the different species as reported in Table 1.
In all complexes the amidine ligand can be assumed to
have the Z configuration since it has already been dem-
onstrated that even with primary amines, which are bulk-
ier than ammonia, the kinetically favoured
Z
configuration is also more stable thermodinamically.
Furthermore, the X-ray structure of the Tschugaevꢀs salt,
as determined by Stephenson, shows the amidine ligand
to have Z configuration [18a]. Analogous Z configura-
tion was found in the X-ray structure of trans-
[PtCl4{HN@C(NH2)Me}2] reported by Kukushkin and
co-workers [18b]. The Z configuration of the acetamidine
in compound 1 is also supported by the relatively high
Although the molecular ion of [Pt(DMSO)-
(NH3){HN@C(NH2)Me}2] was not observed, this
experiment clearly showed that this species contains a
coordinated DMSO molecule. Moreover the trans-
labilizing effect of DMSO can explain why the ammine
ligand undergoes substitution by a molecule of alcohol.
Table 1
Selected 1H and 13C NMR data of 1–3 in DMSO (d in ppm)
Compound
NH2
Pt–NH
R
NH3
C@N
trans-[PtCl(NH3){HN@C(NH2)Me}2]Cl, 1
trans-[Pt(DMSO)(NH3){HN@C(NH2)Me}2]Cl2
trans-[PtCl(DMSO){HN@C(NH2)Me}2]Cl
7.17
8.21
7.63
7.03
7.63
7.45
6.50
6.82
6.72
1.93 (21.42)
2.01 (21.58)
1.97 (21.33)
4.04
4.53
–
166.8
168.2
166.8
trans-[PtCl(NH3){HN@C(NH2)Ph}2]Cl, 2
trans-[Pt(DMSO)(NH3){HN@C(NH2)Ph}2]Cl2
trans-[PtCl(DMSO){HN@C(NH2)Ph}2]Cl
8.21
8.76
8.12
7.89
8.09
7.87
7.23
7.20
7.07
–
–
–
4.25
4.74
–
166.6
167.0
167.8
trans-[PtCl(NH3){HN@C(NH2)CH2Ph}2]Cl, 3
trans-[Pt(DMSO)(NH3){HN@C(NH2)CH2Ph}2]Cl2
trans-[PtCl(DMSO){HN@C(NH2)CH2Ph}2]Cl
7.86
8.40
7.75
7.68
7.84
7.48
7.03
7.15
6.95
3.58 (40.85)
3.60 (41.27)
3.55 (41.50)
4.14
4.61
–
168.4
169.9
169.1

2124
G. Natile et al. / Journal of Organometallic Chemistry 690 (2005) 2121–2127
trans-[Pt(NH3){HN@C(NH2)Me}2(DMSO)]2+ decrease
D
D
D
C
6
5
4
3
slowly with time while a new set of signals gains inten-
sity. The new set of signals has intensity comparable to
that of the ammine/DMSO precursor after standing for
days in DMSO solution (spectrum 3 in Fig. 1). How-
ever, if the solution is flashed with argon the new set
of signals increases in intensity and becomes dominant
(resonances C in Fig. 1). The new set of signals indi-
cates that the new species does not contain coordinated
ammine, but still contains the amidines in their original
Z configuration (C–Me resonance at 1.97 ppm). Most
likely the new species is the product of substitution
of the ammine by a chlorine ligand. This has been
proved by ESI mass spectrometry showing the presence
of a molecular peak at m/z 431 corresponding to
[PtCl{HN@C(NH2)Me}2(DMSO)]+. It is to be noted
that in both the ammine/DMSO and chloro/DMSO
species the platinum moieties have kept their original
trans geometry since a trans ! cis isomerisation of
the complexes would have lead to non-equivalent ami-
dines (one trans to DMSO and the other trans to NH3
or Cl). It has been possible to prove that the slow con-
version of the ammine/DMSO into the chloro/DMSO
species was not due to a slow rate of the interconver-
sion reaction but to a slow rate of release of gaseus
NH3 from the DMSO solution. In fact addition of gas-
eous ammonia to the solution containing mainly the
chloro/DMSO species converts rapidly this species
back to the ammino/DMSO species plus additional for-
mation of a significant amount of the Tschugaevꢀs cat-
ion [Pt(NH3)2{HN@C(NH2)Me}2]2+ (resonances D in
Fig. 1). The solvolysis of the amino-chloro species
can therefore be represented as shown in the scheme
below (L = amidine). It is to be noted that the equilib-
rium between ammine/DMSO and chloro/DMSO spe-
cies is shifted towards the ammine/DMSO species
even in the presence of a chloride ion concentration
twice that of the substrate and a very small amount
of free ammonia.
CC
B
B
B
B
2
A
A
1
A A
8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0
Fig. 1. 1H NMR spectra (in the region 9.0–3.6 ppm) of a solution of
compound 1 in DMSO taken soon after dissolution and after standing
for 0.2 and 17 days (spectra 1, 2, and 3, respectively), after flashing
with argon for 0.25 and 9 h (spectra 4 and 5, respectively), and after
addition of gaseous ammonia (spectrum 6). The peaks of the starting
substrate trans-[PtCl(NH3){HN@C(NH2)Me}2]+, of the monosolvated
species trans-[Pt(NH3){HN@C(NH2)Me}2(DMSO)]2+ and trans-
[PtCl{HN@C(NH2)Me}2(DMSO)]+, and of the Tschugaevꢀs cation
trans-[Pt(NH3)2{HN@C(NH2)Me}2]2+ are marked A, B, C, and D,
respectively.
Substitution of a chloride ligand by a DMSO molecule
has been demonstrated to occur readly in solvolysis
reactions of cis- and trans-[PtCl2(NH3)2] [23]. In
particular it has been observed that trans-[PtCl(NH3)2-
(DMSO)]Cl is the only product formed when trans-
[PtCl2(NH3)2] is dissolved in DMSO.
In the 1H NMR spectrum of 1 in DMSO, the
signals due to the ammine/DMSO solvated species
DMSO
DMSO
Cl
L
L
L
+ Cl-
Cl
+ DMSO
L
L
L
NH3
ammine/chloro
NH3
NH3
ammine/DMSO
Cl
L
+ NH3
L
DMSO
chloro/DMSO

G. Natile et al. / Journal of Organometallic Chemistry 690 (2005) 2121–2127
2125
species in which both chlorine ligands were substituted
by ammonia molecules. The NMR spectra of the newly
synthesized chloro/ammine compounds dissolved in
DMSO showed the formation of different solvated spe-
cies; first the ammine/DMSO species trans-[Pt(NH3)-
{HN@C(NH2)R}2(DMSO)]2+ and trans-[PtCl{HN@
1
C(NH2)R}2(DMSO)]+. All H NMR signals have been
ppm
5
1
assigned through NOESY, TOCSY and H/13C hetero-
B
nuclear correlation spectra. It is noteworthy that the sys-
tem of the two trans-amidines is stable towards
substitution by either DMSO or Clꢀ and does not isom-
erize to cis. In contrast, preliminary results indicate that
this is not the case for the corresponding cis-
[PtCl(NH3){HN@C(NH2)R}2]Cl derivatives.
6
7
8
9
4. Experimental
A
4.1. General procedures and materials
All experiments were carried out under nitrogen
atmosphere using standard Schlenck techniques. Sol-
vents were distilled prior to use; CH2Cl2 was distilled
from CaH2. Elemental analyses were performed by the
Department of Analytical, Inorganic, and Organometal-
lic Chemistry of the University of Padova. The com-
plexes trans-[PtCl2(N„CR)2] (R = Me, Ph, CH2Ph)
were synthesized as previously reported [25], while
NH3 was purchased from SIAD.
9
8
7
6
5
ppm
Fig. 2. Low field region of the 2D NOESY spectrum of the trans-
[Pt(NH3){HN@C(NH2)Me}2(DMSO)]2+ complex showing the con-
nectivities between the two aminic protons of the amidine (EXY peak,
A) and between the NH3 and the NH iminic proton of the amidine
ligands (NOESY peak, B).
Therefore, it can be concluded that the weakening of
the trans Pt–NH3 bond by DMSO in the solvated spe-
cies, as already reported by some of us [24], is smaller
than the weakening of the Pt–Cl bond trans to DMSO;
this is in accord with Cl competing more for platinum d
electrons than NH3.
4.2. Instrumentation
IR spectra were taken on a FT-IR AVATAR 320
(4000–400 cmꢀ1) or on a FT-IR Nexus (range 600–
50 cmꢀ1) of the Nicolet Instrument Corporation (KBr
or polyethylene (PE) films) spectrophotometers; the
ꢀ
1
wavenumbers ðmÞ are given in cmꢀ1. H and 13C NMR
1
Similarly to the case of compound 1, the H NMR
spectra of 2 and 3 in DMSO solution also indicate the
rapid substitution of the chlorine ligand by DMSO
giving rise to formation of the ammine/DMSO spe-
cies trans-[Pt(NH3){HN@C(NH2)R}2(DMSO)]Cl2 (R =
Ph, CH2Ph) and subsequent slow formation of the
chloro/DMSO species trans-[PtCl{HN@C(NH2)Me}2-
(DMSO)]Cl (R = Ph, CH2Ph).
solution spectra were obtained at 298 K (unless other-
wise stated) on Bruker Avance-400 and 300 spectrome-
ters operating at 400.13 and 300.13 MHz, respectively,
and a Bruker 200 AC spectrometer operating at
200.13 MHz; d values (ppm) are relative to internal
Me4Si. Suitable integral values for the proton spectra
were obtained by a pre-scan delay of 10 s. The assign-
ments of the proton resonances were performed by stan-
dard chemical shift correlations, COSY, TOCSY and
NOESY experiments. In the phase-sensitive NOESY
measurements (the so-called Exchange Spectroscopy
EXSY spectra) the presence of intense cross-peaks, in-
phase with the diagonal, indicates a chemical exchange
between the correlated nuclei [26]. The 13C resonances
were attributed through 2D-heterocorrelated COSY
experiments (HMQC with bird sequence [27a] and quad-
rature along F1 achieved using the TPPI method [27b]
for the H-bonded carbon atoms, HMBC [27c] for the
quaternary ones.
3. Conclusions
The reactivity of the di-nitrile complexes trans-
[PtCl2(N„CR)2] (R = Me, Ph, CH2Ph) with NH3 has
been investigated. The reactions, even performed at
low temperature (ꢀ10 ꢀC), afford the corresponding di-
amidine complexes in which also one chlorine ligand
has
been
displaced
by
NH3,
e.g.,
trans-
[PtCl(NH3){HN@C(NH2)R}2]Cl. By performing the
reaction at room temperature Tschugaev obtained the

2126
G. Natile et al. / Journal of Organometallic Chemistry 690 (2005) 2121–2127
The electrospray ionisation mass spectra of 1–3 were
uum. Yield 0.14 g, 84.3%. Anal. Calc. for C16H23Cl2N5Pt
(PM = 551.38): C, 34.8; H, 4.2; N, 12.7. Found: C, 34.2;
recorded on a LCQ DECA (Finningam MAT) instru-
ment, operating in positive ion mode. The instrumental
conditions used were the following: source potential
4 kV, capillary temperature 270 ꢀC, sheath gas (N2) flow
rate 40 arbitrary units. The final solution was directly
introduced into the ESI ion source by a syringe pump
at a flow rate of 10 ll/min.
ꢀ
H, 4.0; N, 13.0 %. IR (m, KBr film): 3405, 3167 (m, br, N–
H); 1639 (s, C@N). IR (m, PE film): 335 cmꢀ1 (s, Pt–Cl).
ꢀ
MS (ESI, m/z, rel.ab.%) 515 ([PtCl(NH3){HN@
C(NH2)CH2Ph}2]+, 50%), 498 ([PtCl{HN@C(NH2)-
CH2Ph}2]+, 18%), 462 ([PtCl{HN@C(NH2)CH2Ph}2 ꢀ
HCl]+, 100%).
4.3. Syntheses
Acknowledgements
4.3.1. Synthesis of trans-[PtCl(NH3){HN@C(NH2)-
Me}2]Cl (1)
The authors thank the C.N.R. (CNR/RAS Project),
the Universities of Bari and Padova and MIUR for
financial support. The authors thank Dr. Giuseppe Pace
and Francesco Cannito and Sig. Adriano Berton for
analytical and technical support.
A
suspension of trans-[PtCl2(MeCN)2] (0.56 g,
1.61 mmol) in CH2Cl2 (60 ml) was treated with NH3(g)
at ꢀ10 ꢀC. After 2 h the solution was heated to room
temperature and stirred for 4 h. The reaction mixture
was concentrated to a small volume and then treated
with cold Et2O (0 ꢀC, 15 ml). A white solid precipitated,
which was filtered off, washed with Et2O (3 · 15 ml) and
dried under vacuum. Yield 0.59 g, 91.9%. Anal. Calc.
for C4H15Cl2N5Pt (PM = 399.18): C, 12.0; H, 3.8; N,
17.5. Found: C, 11.8; H, 3.8; N, 17.3%. IR (ꢀm, KBr film):
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3511, 3458, 3353, 3243 (s, br, N–H); 1650 (s, C@N). IR
ꢀ1
ꢀ
(m, PE film): 333 cm (m, Pt–Cl). MS (ESI, m/z, rel.
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ꢀ
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