Direct synthesis of (imine)platinum(ii) complexes by iminoacylation of ketoximes with activated organonitrile ligands

Article abstract of DOI:10.1039/b611341a

The metal-mediated iminoacylation of ketoximes R₁R ₂CNOH (1a R₁ = R₂ = Me; 1b R₁ = Me, R₂ = Et; 1c R₁R₂ = C₄H₈; 1d R₁R₂ = C₅H₁₀) upon treatment with the platinum(ii) complex trans-[PtCl₂(NCCH₂CO ₂Me)₂] 2a with an organonitrile bearing an acceptor group proceeds under mild conditions in dry CH₂Cl₂ to give the trans-[PtCl₂{NHC(CH₂CO₂Me)ONCR ₁R₂}₂] 3a-d isomers in moderate yield. The reaction of those ketoximes with trans-[PtCl₂(NCCH ₂Cl)₂] 2b under the same experimental conditions gives a 1: 1 mixture of the isomers trans/cis-[PtCl₂{NHC(CH ₂Cl)ONCR₁R₂}₂] 3e-h and 4e-h in moderate to good yield. These reactions are greatly accelerated by microwave irradiation to give, with higher yields (ca. 75%), the same products which were characterized by IR and ¹H, ¹³C and ¹⁹⁵Pt NMR spectroscopies, FAB-MS, elemental analysis for the stable trans isomers, and X-ray diffraction analysis (3f). The diiminoester ligand in 3a was liberated upon reaction of the complex with a diphosphine. The Royal Society of Chemistry 2006.

Full text of DOI:10.1039/b611341a

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www.rsc.org/dalton | Dalton Transactions
Direct synthesis of (imine)platinum(II) complexes by iminoacylation of
ketoximes with activated organonitrile ligands
Jamal Lasri,a M. Ad´ılia Janua´rio Charmier,*a,b M. Fa´tima C. Guedes da Silvaa,b and Armando J. L. Pombeiro*a
Received 7th August 2006, Accepted 30th August 2006
First published as an Advance Article on the web 11th September 2006
DOI: 10.1039/b611341a
=
The metal-mediated iminoacylation of ketoximes R1R2C NOH (1a R1 = R2 = Me; 1b R1 = Me, R2 =
Et; 1c R1R2 = C4H8; 1d R1R2 = C5H10) upon treatment with the platinum(II) complex
trans-[PtCl2(NCCH2CO2Me)2] 2a with an organonitrile bearing an acceptor group proceeds under mild
=
=
conditions in dry CH2Cl2 to give the trans-[PtCl2{NH C(CH2CO2Me)ON CR1R2}2] 3a–d isomers in
moderate yield. The reaction of those ketoximes with trans-[PtCl2(NCCH2Cl)2] 2b under the same
=
=
experimental conditions gives a 1 : 1 mixture of the isomers trans/cis-[PtCl2{NH C(CH2Cl)ON
CR1R2}2] 3e–h and 4e–h in moderate to good yield. These reactions are greatly accelerated by
microwave irradiation to give, with higher yields (ca. 75%), the same products which were characterized
by IR and 1H, 13C and 195Pt NMR spectroscopies, FAB-MS, elemental analysis for the stable trans
isomers, and X-ray diffraction analysis (3f). The diiminoester ligand in 3a was liberated upon reaction
of the complex with a diphosphine.
Further aims of the current study are as follows. Firstly,
Introduction
we could prepare the difficultly accessible novel iminoacylated
PtII products with those functional groups. Secondly, the study
would provide an opportunity to apply unconventional methods
of activation, i.e. focused microwave irradiation20 to reduce the
reaction time, to increase the purity and the selectivity and/or yield
in comparison with traditional methods.10 Thirdly, at a later stage,
these (imine)Pt complexes with a reactive group could be used for
further synthesis of derivatives structurally related to aminoesters,
precursors of lactam heterocycles, with potential bioactivity or
catalytic interest.21
Hence, we have succeeded to extend to (nitrile)PtII the iminoa-
cylation reaction of oximes (not feasible in pure organic chemistry
and previously requiring a higher metal oxidation state) and now
report a direct method for generation of (imine)PtII compounds
without any Lewis acid catalyst and using either traditional
heating or microwave irradiation.
Organonitriles can be activated by ligation to a metal centre,
what can provide a simple method for the synthesis of a large
number of organonitrogen compounds.1–3 Oximes are reagents
with a rich coordination chemistry4–6 and, in spite of their relatively
weak nucleophilic character, they can act as nucleophiles towards
organonitriles, NCR, when the latter are coordinated to PtIV,7
ReIV,8 RhIII,9 or PdII,10 and on deprotonation yield interesting
substituted iminoacylated species.
The metal oxidation state exhibits a key role and, in contrast to
the above reactions with oximes or other types of nucleophiles,11–13
at electron-rich ReI or Mo0 centres14,15 the nitrile group is activated
towards electrophilic attack. In the case of an oxime, the coupling
reaction with NCR proceeds at PtIV,7,16 but not at PtII, and in
order to obtain PtII products one has to reduce the previously
synthesized corresponding PtIV complexes.17 To our knowledge,
only one example of extension of the nitrile–oxime coupling to
PtII is known, but it concerns organocyanamides NCNR2 and
requires the presence of a catalytic amount of AgI or CuII as a
Lewis acid18 to bind the amino moiety and thus further activate the
cyano group. Similarly, the electrophilicity of nitriles is promoted
by an electron-acceptor R, such as an ester or Cl atom, and
can be enhanced by coordination to PtII to undergo [2 + 3]-
cycloadditions.19 These observations stimulated our interest to
extend to trans-PtII complexes the metal-mediated nitrile–oxime
reaction, by using ester- and chloro-substituted nitriles, what
would allow the direct (single pot) synthesis of iminoacylated PtII
complexes without requiring the involvement of intermediate PtIV
species.
Results and discussion
We have addressed the above aims by treating the oximes
=
R1R2C NOH 1 (1a R1 = R2 = Me; 1b R1 = Me, R2 = Et; 1c
R1R2 = C4H8; 1 R1R2 = C5H10) with the platinum(II) compounds
trans-[PtCl2(NCR)2] (2a R = CH2CO2Me, 2b R = CH2Cl) in dry
CH2Cl2 for 15 min with heating at 50 ◦C by the conventional way.
=
=
Compounds trans- and/or cis-[PtCl2{NH C(R)ON CR1R2}2]
(3 and/or 4, respectively) were isolated in moderate to good yields
(47–62%) (Scheme 1). The reactions are greatly accelerated by
focused microwave irradiation which, at the same temperature
and in a shorter time, without a decrease of selectivity, leads to
higher isolated yields (ca. 75%, in only 1–2 min).
In order to obtain the desired imino-complexes with a max-
imum yield, a close control of the time and temperature is
required. For example, the reaction of acetone oxime 1a and
trans-[PtCl2(NCCH2Cl)2] 2b with heating for 2 h at 50 ◦C
aCentro de Qu´ımica Estrutural, Complexo I, Instituto Superior Te´cnico, Av.
Rovisco Pais, 1049-001, Lisboa, Portugal. E-mail: pombeiro@ist.utl.pt
bUniversidade Luso´fona de Humanidades e Tecnologias, Av. Campo Grande
no 376, 1749-024, Lisboa, Portugal. E-mail: adilia.charmier@ist.utl.pt
5062 | Dalton Trans., 2006, 5062–5067
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coupling reaction (b2) and further reduction (b3) to PtII, typically
17
=
by using the phosphorus ylide Ph3P CHCO2Me.
The new complexes were characterised by elemental analyses,
IR and 1H, 13C and 195Pt NMR spectroscopies, and FAB-MS. In the
IR spectra, no m(N≡C) band is detected, the m(N–H) bands appear
at 3299–3195 cm−1 and the characteristic strong m(C N) bands of
=
the imine ligands occur in the 1666–1639 cm−1 range, in agreement
with literature results,7h,22 thus confirming the formation of the
imino–platinum complexes.
In the 1H and 13C NMR spectra, the resonances of the cis
isomers appear at lower fields (by ca. 0.02 to 0.5 ppm) than
the corresponding ones for the trans compounds. In the 195Pt
NMR spectra, the resonances of both isomers (from −2046
to −2080 ppm) lie within the range previously observed for
complexes derived from nitrile–oxime coupling.10,17 All trans
isolated compounds gave satisfactory elemental analyses and the
expected molecular ion/fragmentation patterns in the FAB+ mass
spectra.
The single-crystal X-ray diffraction structural analysis of trans-
=
=
[PtCl2{NH C(CH2Cl)ON C(Me)(Et)}2] 3f confirms the formu-
lation and its trans configuration (the molecular structure is
depicted in Fig. 1, crystal data and selected bond lengths and
angles are given in Tables 1 and 2, respectively). Half of the
molecule was found in the asymmetric unit and the central Pt atom
lies on a twofold axis. The values of bond lengths distances Pt1–N1
Scheme 1
=
=
gives only the trans-[PtCl2{NH C(CH2Cl)ON CMe2}2] isomer
in lower yield (16%) in comparison with the above mentioned
conditions (15 min, 50 ◦C, 56–62% yield). Moreover, the reac-
=
=
Table 1 Crystal data for trans-[PtCl2{NH C(CH2Cl)ON C(Me)(Et)}2]
tion of trans-[PtCl2(NCCH2Cl)2] 2b with cyclohexanone oxime
3f
◦
=
(C5H10)C NOH 1d with heating for 2 h at 50 C or heating for
10 min at 120 ◦C by microwave irradiation leads only to products
of degradation. The cis isomers are less stable than the trans ones
and undergo decomposition in solution at room temperature.
The formation of the two isomeric products is detected by TLC
on silica gel (spots with different Rf values) and they have been
separated by column chromatography on silica gel and isolated
as yellow solids. Curiously, the reaction is more selective with
the stronger electron-attractor CO2Me group giving only the trans
imino-complexes, whereas in the case of the chloro substituent a 1 :
3f
Empirical formula
C12H22Cl4N4 O2 Pt
591.23
130(2) K
0.71069
Tetragonal
I41/a
10.9223
10.9223
34.2519(39)
4086.1(5)
8
Mr
T/K
˚
k/A
Crystal system
Space group
˚
a/A
˚
b/A
˚
c/A
=
=
3
1 mixture of cis and trans-[PtCl2{NH C(CH2Cl)ON CR1R2)2]
˚
V/A
Z
(4e–h and 3e–h, respectively) is obtained (Scheme 1).
Dc/Mg m−3
l(Mo-Ka)/mm−1
No. collected
reflns
1.922
7.402
18448
These reactions allow the direct synthesis of iminoacylated
PtII complexes from nitrile PtII precursors upon nitrile/oxime
coupling (route a, Scheme 2), what constitutes a more convenient
route than the alternative one (route b, Scheme 2) involving the
coupling reaction at PtIV. The latter method would require the
initial oxidation, by Cl2, of PtII to PtIV (reaction b1) followed by the
No. unique rflns
Rint
4617
0.0389
0.0342
0.0819
R1a (I ≥ 2r)
wR2b (I ≥ 2r)
ꢀ
ꢀ
ꢀ
ꢀ
a R1 = ꢀFo| − |Fcꢀ/ |Fo|. b wR2 = [ [w(Fo − Fc2)2]/ [w(Fo2)2]]1/2
.
2
◦
˚
Table 2 Selected bond lengths (A) and angles ( ) for 3f
Pt1–Cl1
Pt1–N1
N1–C1
O11–C1
N11–C11
2.3098(10)
2.002(3)
1.268(5)
1.358(5)
1.255(6)
O11–N11
C1–C2
Cl2–C2
N1–H1
1.461(5)
1.472(6)
1.740(5)
0.88(4)
Cl1–Pt1–N1
Cl1–Pt1–Cl1a
N1–Pt1–N1a
Pt1–N1–H1
90.01(10)
178.49(4)
179.47(12)
115(3)
Pt1–N1–C1
125.9(3)
110.4(3)
125.1(3)
103(3)
N11–O11–C1
O11–C1–N1
N1–H1 · · · N11
Scheme 2
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nucleophile such as an oxime which is expected16c to proceed via
a transition state with a four membered NCOH ring (Scheme 4).
For normal unfunctionalized nitriles NCR (R = alkyl, aryl), their
coordination to a stronger PtIV activator was required7,16c for such
a type of reaction to occur.
Fig.
1
ORTEP view of the iminoacylated PtII complex trans-
=
=
[PtCl2{NH C(CH2Cl)ON C(Me)(Et)}2] 3f with atomic numbering
scheme (ellipsoids are drawn at 30% probability), the dotted line indicating
the intramolecular H-bond. Symmetry transformations used to generate
equivalent atoms: (a) 2 − x, 3/2 − y, z.
Scheme 4
As a result of the combined double mode of nitrile activation,
we have prepared directly, by simple coupling of an oxime to a
PtII-bound nitrile, the derived iminoacyl–platinum(II) complexes.
This type of compounds was previously reached only indirectly,
via reduction (typically with a phosphorus-ylide)17 of the cor-
responding PtIV complexes derived from the oxime addition to
a PtIV-bound nitrile. By using the above nitriles we have also
achieved novel functionalized imino compounds, i.e. diiminoesters
and chlorodiimino species, inaccessible directly by pure organic
chemistry. They can be liberated from the metal by displacement
with a phosphine and, although unstable in the free state, they
can be generated and further used in situ when required, a type of
strategy that has been applied22 for other imines. Hence, they are
expected to provide a new route for the synthesis e.g. of heterocyclic
compounds by further reactions which are under study in our
laboratory.
˚
˚
˚
[2.002(3) A], Pt1–Cl1 [2.3098(10) A], N1–C1 [1.268(5) A)] and N1–
◦
˚
H1 [0.88(4) A], and angles Cl1–Pt1–N1 [90.01(10) ], Pt1–N1–H1
[115(3)◦], as well as the N1–H1 · · · N11 hydrogen bond between
the imine hydrogen and oxime nitrogen atoms [H1 · · · N11, 2.27(4);
◦
˚
N1 · · · N11, 2.619(6) A; N1–H1 · · · N11, 103(3) ] which stabilizes
the E-conformation of the iminoacyl ligands, agree with those
reported for other iminoacylated platinum complexes.7i
Liberation of the diiminoester 5 was achieved by adding the
diphosphine Ph2PCH2CH2PPh2 (dppe) to a CDCl3 solution of
3a (Scheme 3), but unfortunately the compound is not stable
enough to be isolated and could be characterized only by 1H
NMR spectroscopy. Its resonances appear at higher field than the
corresponding ones for the complex precursor 3a. For example,
the methylene CH2CO2Me protons singlet is observed at d 3.77
in 5 and at 4.19 ppm in 3a. According to the type of reaction
of Scheme 3, we are able to obtain new substituted iminoesters
that are expected to find further use for the synthesis of novel
heterocyclic compounds.
Experimental
Materials and instrumentation
Solvents were purchased from Aldrich and dried by usual proce-
dures. The organonitrile complexes trans-[PtCl2(NCR)2] (2a R =
CH2CO2Me, 2b R = CH2Cl) were prepared according to published
methods.19 The oximes were obtained from commercial sources
(Aldrich). C, H and N elemental analyses were carried out by
the Microanalytical Service of the Instituto Superior Te´cnico.
1H, 13C and 195Pt NMR spectra (in CDCl3) were measured on a
Varian Unity 300 spectrometer at ambient temperature. Positive-
ion FAB mass spectra were obtained on a Trio 2000 instrument
by bombarding 3-nitrobenzyl alcohol (NBA) matrixes of samples
with 8 keV (ca 1.28 × 1015 J) Xe atoms. 1H and 13C chemical shifts
(d) were expressed in ppm relative to Si(Me)4, and 195Pt chemical
shifts are relative to Na2[PtCl6] (by using aqueous K2[PtCl4],
d = −1630 ppm, as a standard) with half-height line width in
parentheses. J values are in Hz. Infrared spectra (4000–400 cm−1)
were recorded on a Bio-Rad FTS 3000MX and a Jasco FT/IR-430
instruments in KBr pellets and the wavenumbers are in cm−1. The
microwave irradiation experiments were undertaken in a focused
microwave CEM Discover reactor (10 mL, 13 mm diameter, 300
W) which is fitted with a rotational system and an IR detector of
temperature.
Scheme 3
Concluding remarks
A great enhancement of the electrophilicity of the cyano-carbon
of a nitrile was achieved in this study by the combined effects
of a metal and of an electron-acceptor substituent at the nitrile
itself. In particular, by bearing an ester or a chloro substituent and
upon coordination to a PtII centre, the cyano-carbon atom of the
NCCH2X (X = CO2Me, Cl) nitriles is doubly activated to such an
extend that it can undergo ready nucleophilic addition by a weak
5064 | Dalton Trans., 2006, 5062–5067
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1
3.79 (s, 3H, MeO), 4.17 (s, 2H, CH2), 8.2 (s, br, 1H, NH). 13C{ H}
Reactions of the organonitrile platinum(II) complexes
trans-[PtCl2(NCR)2] (2a R = CH2CO2Me, 2b R = CH2Cl) with
NMR, d 24.4, 25.0, 29.7, 31.4 (C4H8), 39.3 (CH2CO), 52.7 (MeO),
166.5 (CO2Me), 167.2 ( C{C4H8}), 177.1 (C(O) N). 195Pt NMR,
d −2076 (645 Hz). FAB+-MS, m/z 663 [M]+, 626 [M − HCl]+,
590 [M − 2HCl]+. Anal. Calc. for C18H28N4Cl2O6Pt: C, 32.64; H,
4.26; N, 8.46. Found: C, 32.72; H, 4.46; N, 8.14%.
=
=
=
=
=
Me2C NOH (1a), (Me)(Et)C NOH (1b), (C4H8)C NOH (1c),
=
(C5H10)C NOH (1d)
(i) By conventional method. A solution of 2a (50.0 mg,
0.107 mmol) or 2b (50.0 mg, 0.119 mmol) in dry CH2Cl2
(3 mL) is added at room temperature to the appropriate oxime
(3 eq) and the mixture is heated with stirring at 55–60 ◦C for
15 min to form a bright yellow solution. After evaporation
of the solvent under vacuum to dryness, the residue is washed
with diethyl ether (five 3 mL portions) to remove the excess
of oxime, and then purified by column chromatography
(SiO2/CH2Cl2, Et2O) followed by evaporation of the solvent in
vacuo to give yellow powders of the corresponding iminoacy-
=
=
trans-[PtCl2{NH C(CH2CO2Me)ON C(C5H10)}2]
(3d).
Method (i), 48% yield. TLC on SiO2: Rf = 0.5 (eluent CH2Cl2–
Et2O (8 : 1)). IR (cm−1): 3299 (NH), 1747 (CO2Me), 1660 and
1
=
1639 (C N), 1166 (C–O). H NMR, d 1.65 (m, 2H), 1.75 (m, 4H),
=
2.32 (t, JHH 5.4 Hz, 2H), 2.51 (t, JHH 5.4 Hz, 2H) ( C{C5H10}),
1
3.79 (s, 3H, MeO), 4.18 (s, 2H, CH2), 8.2 (s, br, 1H, NH). 13C{ H}
NMR, d 25.8, 26.3, 27.3, 27.9, 32.5 (C5H10), 40.1 (CH2CO), 53.4
=
=
(MeO), 167.2 (CO2Me), 168.0 ( C{C5H10}), 170.9 (C(O) N).
195Pt NMR, d −2075 (687 Hz). FAB+-MS, m/z 690 [M], 653 [M −
HCl]. Anal. Calc. for C20H32N4Cl2O6 Pt: C, 34.79; H, 4.67; N,
8.11. Found: C, 34.50; H, 4.26; N, 7.95%.
=
=
lated products trans-[PtCl2{NH C(CH2CO2Me)ON CR1R2}2]
(3a–d) or the isomeric mixtures of trans/cis-
1
:
1
=
=
[PtCl2{NH C(CH2Cl)ON CR1R2}2] (3e–h and 4e–h). The trans
isomers can be recrystallised in air from CH2Cl2–Et2O.
=
=
trans-[PtCl2{NH C(CH2Cl)ON CMe2}2] (3e). Method (i),
(ii) By focused microwave irradiation. The reagents, in
amounts identical to those detailed above, were added to a
cylindrical Pyrex tube which was then placed in the focused
microwave reactor. After reaction (ca. 50 ◦C, 1–2 min), the mixture
was allowed to cool down, the solvent was evaporated under
vacuum to dryness. The residue was washed with diethyl ether (five
3 mL portions), to remove the excess of oxime, and then purified
by column chromatography (SiO2/CH2Cl2, Et2O) followed by
evaporation of the solvent under vacuum to give the final yellow
powders of the 3 or 4 products (ca. 75% yield). The trans isomers
can be recrystallised in air from CH2Cl2–Et2O.
31% yield. TLC on SiO2: Rf = 0.5 (eluent CH2Cl2–Et2O (10 : 1)).
−1
=
IR (cm ): 3210 (NH), 1666 and 1644 (C N), 1278 (CH2Cl), 1197
1
=
(C–O). H NMR, d 2.06 and 2.08 (two s, 3H each, CMe2), 4.93
(s, 2H, CH2Cl), 8.32 (s, br, 1H, NH). 13C{ H} NMR, d 18.0 and
1
=
=
22.4 (Me groups), 39.8 (CH2Cl), 167.1 ( CMe2), 168.6 (C(O) N).
195Pt NMR, d −2067 (752 Hz). FAB+-MS, m/z 563 [M]+, 529 [M −
HCl]+. Anal. Calc. for C10H18N4Cl4O2Pt·1/4CH2Cl2: C, 21.07; H,
3.19; N, 9.58. Found: C, 21.50; H, 3.17; N, 9.34%. The solvent of
crystallization CH2Cl2 has been detected in the NMR spectra.
=
=
cis-[PtCl2{NH C(CH2Cl)ON CMe2}2] (4e). Method (i),
31% yield. TLC on SiO2: Rf = 0.5 (eluent CH2Cl2/Et2O (6 : 1)).
−1
1
=
=
=
trans-[PtCl2{NH C(CH2CO2Me)ON CMe2}2]
(3a).
IR (cm ): 3176 (NH), 1670 and 1643 (C N). H NMR, d 2.07
=
Method (i), 50% yield. TLC on SiO2: Rf = 0.55 (eluent
and 2.09 (two s, 3H each, CMe2), 4.95 (s, 2H, CH2Cl), 8.6 (s, br,
CH2Cl2–Et2O (10 : 1)). IR (cm−1): 3216 (NH), 1747 (CO2Me),
1H, NH). FAB+-MS, m/z 563 [M]+, 529 [M − HCl]+. The complex
1
1
=
1646 and 1666 (C N), 1176 (C–O). H NMR, d 2.01 and 2.03
is too unstable in CDCl3 to measure the 13C{ H} NMR and 195Pt
=
(two s, 3H each, CMe2), 3.79 (s, 3H, MeO), 4.19 (s, 2H, CH2),
NMR spectra.
8.2 (s, br, 1H, NH). 13C{ H} NMR, d 17.9 and 22.4 (Me groups),
1
=
=
trans-[PtCl2{NH C(CH2Cl)ON C(Me)(Et)}2] (3f). Method
=
40.0 (CH2), 53.4 (MeO), 166.3 (CO2Me), 167.1 ( CMe2), 167.8
(i), 28% yield. TLC on SiO2: Rf = 0.53 (eluent CH2Cl2). IR
(C(O) N). 195Pt NMR, d −2080 (774 Hz). FAB+-MS, m/z 611
=
−1
=
(cm ): 3213 (NH), 1666 and 1643 (C N), 1269 (CH2Cl), 1194
[M]+. Anal. Calc. for C14H24N4Cl2O6Pt: C, 27.55; H, 3.96; N, 9.18.
Found: C, 28.05; H, 4.07; N, 8.99%.
1
(C–O). H NMR, d 1.12–1.20 (dt, JHH 7.8 Hz, JHH 7.2 Hz, 3H,
CH3CH2), 2.04 and 2.06 (two s, 3H, CMe), 2.35–2.53 (dq, JHH
=
=
=
trans-[PtCl2{NH C(CH2CO2Me)ON C(Me)(Et)}2]
(3b).
7.8 Hz, JHH 7.2 Hz, 2H, CH3CH2), 4.94 (s, 2H, CH2Cl), 8.3 (s, br,
1
Method (i), 48% yield. TLC on SiO2: Rf = 0.62 (eluent CH2Cl2–
1H, NH). 13C{ H} NMR, d 10.7 and 11.0 (CH3CH2), 16.5 and
Et2O (10 : 1)). IR (cm−1): 3221 (NH), 1747 (CO2Me), 1643 and
1666 (C N), 1176 (C–O). H NMR, d 1.14 (m, 3H), 1.99 and
20.1 ( CMe), 25.0 and 30.1 (CH3CH2), 39.9 (CH2Cl), 168.7 and
=
171.5 ( C(Me)(Et)), 170.9 (C(O) N). 195Pt NMR, d −2065 (806
Hz). FAB+-MS, m/z 591 [M]+, 557 [M − HCl]+. Anal. Calc. for
C12H22N4O2Cl4Pt: C, 24.34; H, 3.75; N, 7.48. Found: C, 24.28; H,
3.55; N, 7.94%. Suitable crystals for X-ray analysis were obtained
upon recrystallization from CH2Cl2–Et2O.
1
=
=
=
=
2.01 (two s, 3H each, CMe), 2.35 (m, 2H), 3.79 (s, 3H, MeO),
4.20 (s, 2H, CH2), 8.2 (s, br, 1H, NH). 13C{ H} NMR, d 10.6
1
=
and 10.9 (two s, CH3CH2), 16.4 and 20.1 (two s, CMe), 24.9
and 30.0 (two s, CH2CH3), 40.1 (CH2), 53.4 (MeO), 167.1 and
167.9 (CO2Me), 169.9 ( C(Me)(Et)), 170.6 (C(O) N). 195Pt,
d −2078 (737 Hz). FAB+-MS, m/z 638 [M]+. Anal. Calc. for
C16H28N4Cl2O6Pt·H2O: C, 29.27; H, 4.61; N, 8.53. Found: C,
29.31; H, 4.48; N, 8.59. H2O has been detected in the IR and 1H
NMR spectra.
=
=
=
=
cis-[PtCl2{NH C(CH2Cl)ON C(Me)(Et)}2] (4f). Method
(i), 28% yield. TLC on SiO2: Rf = 0.75 (eluent CH2Cl2/Et2O
−1
=
(6 : 1)). IR (cm ): 3195 (NH), 1666 and 1641 (C N), 1265
1
(CH2Cl), 1194 (C–O). H NMR, d 1.11–1.19 (m, 3H, CH3CH2),
=
2.03–2.07 (m, 3H, CMe), 2.36–2.48 (m, 2H, CH3CH2), 4.97 (s,
trans-[PtCl2{NH C(CH2CO2Me)ON C(C4H8)}2]
(3c).
2H, CH2Cl), 8.6 (s, br, 1H, NH). 13C{ H} NMR, d 10.6 and 11.0
1
=
=
=
Method (i), 47% yield. TLC on SiO2: Rf = 0.7 (eluent CH2Cl2–
(CH3CH2), 16.4 and 20.2 ( CMe), 24.9 and 30.1 (CH3CH2), 40.4
−1
Et2O (10 : 1)). IR (cm ): 3217 (NH), 1753 (CO2Me), 1655 (C N),
(CH2Cl), 168.7 ( C(Me)(Et)), 170.9 (C(O) N). 195Pt NMR, d
−2046 (806 Hz). FAB+-MS, m/z 591 [M]+, 557 [M − HCl]+.
=
=
=
1
=
1124 (C–O). H NMR, d 1.82 (m, 4H), 2.52 (m, 4H) ( C{C4H8}),
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Dalton Trans., 2006, 5062–5067 | 5065
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View Article Online
=
=
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b611341a
trans-[PtCl2{NH C(CH2Cl)ON C(C4H8)}2] (3g). Method
(i), 29% yield. TLC on SiO2: Rf = 0.5 (eluent CH2Cl2). IR (cm−1):
1
=
3286 (NH), 1647 (C N), 1263 (CH2Cl), 1144 (C–O). H NMR,
Liberation of the iminoacylated oxime. dppe (11.7 mg,
=
d 1.85 (m, 4H), 2.53 (m, 2H), 2.62 (m, 2H) ( C{C4H8}), 4.90 (s,
=
2H, CH2Cl), 8.2 (s, br, 1H, NH). 13C{ H} NMR, d 25.1, 25.7, 30.5,
1
0.029 mmol) was added to a solution of trans-[PtCl2{NH
=
C(CH2CO2Me)ON CMe2}2] (3a) (9.0 mg, 0.015 mmol) in CDCl3
(1 mL, 99.8% D), the mixture was left to stand for 10 min until a
colourless precipitate of [Pt(dppe)2]Cl2 was released. The complex
was removed by filtration and the filtrate was characterised by 1H
=
=
32.2 (C4H8), 39.8 (CH2Cl), 168.8 ( C{C4H8}), 178.6 (C(O) N).
195Pt NMR, d −2064 (816 Hz). FAB+-MS, m/z 615 [M]+, 581 [M −
HCl]+. Anal. Calc. for C14H22N4O2Cl4Pt: C, 27.33; H, 3.60; N, 9.11.
Found: C, 27.35; H, 3.16; N, 8.72%.
NMR.
1
=
=
=
=
cis-[PtCl2{NH C(CH2Cl)ON C(C4H8)}2] (4g). Method (i),
NH C(CH2CO2Me)ON CMe2: H NMR, d 1.88 and 1.89
=
29% yield. TLC on SiO2: Rf = 0.57 (eluent CH2Cl2–Et2O (10 : 1)).
(two s, 3H each, CMe2), 3.66 (s, 3H, MeO), 3.77 (s, 2H,
IR (cm ): 1647 (C N), 1227 (CH2Cl), 1132 (C–O). H NMR, d
CH2), 7.69 (s, br, 1H, NH). 13C{ H} NMR, d not reliable due
−1
1
1
=
=
1.84 (m, 4H), 2.56 (m, 2H), 2.60 (m, 2H) ( C{C4H8}), 4.92 (s, 2H,
to decomposition of the compound.
CH2Cl), 8.4 (s, br, 1H, NH). 13C{ H} NMR, d 25.1, 25.8, 30.6,
1
=
=
32.3 (C4H8), 40.3 (CH2Cl), 169.3 ( C{C4H8}), 179.0 (C(O) N).
FAB+-MS, m/z 615 [M]+, 581 [M − HCl]+. The complex is too
unstable in CDCl3 to measure the 195Pt NMR.
Acknowledgements
This work has been partially supported by the Fundac¸a˜o para
a Cieˆncia e a Tecnologia (FCT) and its POCI 2010 programme
(FEDER funded) (Portugal). J. L. expresses gratitude to FCT
for a post-doc fellowship (grant SFRH/BPD/20927/2004). The
authors are also grateful to Prof. V. Yu. Kukushkin (St. Petersburg
State University) for stimulating discussions.
=
=
trans-[PtCl2{NH C(CH2Cl)ON C(C5H10)}2] (3h). Method
(i), 29% yield. TLC on SiO2: Rf = 0.8 (eluent CH2Cl2). IR (cm−1):
=
3263 (NH), 1639 and 1664 (C N), 1263 (CH2Cl), 1147 (C–O).
1H NMR, d 1.75 (m, 6H), 2.34 (t, JHH 6.3 Hz, 2H), 2.58 (t, JHH
=
6.3 Hz, 2H) ( C{C5H10}), 4.93 (s, 2H, CH2Cl), 8.2 (s, br, 1H,
NH). 13C{ H} NMR, d 25.8, 26.4, 27.4, 27.9, 32.6 (C5H10), 39.9
1
(CH2Cl), 168.8 ( C{C5H10}), 171.7 (C(O) N). 195Pt NMR, d
−2064 (780 Hz). FAB+-MS, m/z 643 [M]+, 609 [M − HCl]+. Anal.
Calc. for C16H26N4O2Cl4Pt: C, 29.87; H, 4.07; N, 8.71. Found: C,
29.99; H, 4.32; N, 8.30%.
References
=
=
1 V. Yu. Kukushkin and A. J. L. Pombeiro, Chem. Rev., 2002, 102, 1771.
2 A. J. L. Pombeiro and V. Yu. Kukushkin, Reactivity of Coordinated
Nitriles, in Comprehensive Coordination Chemistry II, Elsevier, Amster-
dam, 2nd edn, 2003, vol. 1 (ed. A. B. P. Lever), ch. 1.34, pp. 639–660,
and references therein.
3 R. A. Michelin, M. Mozzon and R. Beitani, Coord. Chem. Rev., 1996,
147, 299.
4 A. J. L. Pombeiro and V. Yu. Kukushkin, Reactivity of Coordinated
Oximes, in Comprehensive Coordination Chemistry II, Elsevier, Ams-
terdam, 2nd edn, 2003, vol. 1 (ed. A. B. P. Lever), ch. 1.33, pp. 631–638,
and references therein.
5 V. Yu. Kukushkin and A. J. L. Pombeiro, Coord. Chem. Rev., 1999, 181,
147.
=
=
cis-[PtCl2{NH C(CH2Cl)ON C(C5H10)}2] (4h). Method (i),
29% yield. TLC on SiO2: Rf = 0.6 (eluent CH2Cl2/Et2O (10 : 1)).
−1
1
=
IR (cm ): 3195 (NH), 1660 (C N), 1223 (CH2Cl), 1134 (C–O). H
=
NMR, d 1.63 (m, 6H), 2.34 (m, 2H), 2.55 (m, 2H) ( C{C5H10}),
4.93 (s, 2H, CH2Cl), 8.4 (s, br, 1H, NH). FAB+-MS, m/z 643 [M]+,
609 [M − HCl]+. The complex is too unstable in CDCl3 to measure
the 13C{ H} and 195Pt NMR.
1
6 V. Yu. Kukushkin, D. Tudela and A. J. L. Pombeiro, Coord. Chem. Rev.,
1996, 156, 333.
Crystal structure determination of 3f
7 (a) D. A. Garnovskii, A. J. L. Pombeiro, M. Haukka, P. Sobota and
V. Yu. Kukushkin, Dalton Trans., 2004, 1097; (b) K. V. Luzyanin, V.
Yu. Kukushkin, M. Haukka, J. J. R. Frau´sto da Silva and A. J. L.
Pombeiro, Dalton Trans., 2004, 2728; (c) S. S. P. R. Almeida, M. F. C.
Guedes da Silva, L. B. Jerzykiewicz, P. Sobota and A. J. L. Pombeiro,
Inorg. Chim. Acta, 2003, 356, 259; (d) A. V. Makarycheva-Mikhailova,
M. Haukka, N. A. Bokach, D. A. Garnovskii, M. Galanski, B. K.
Keppler, A. J. L. Pombeiro and V. Yu. Kukushkin, New J. Chem., 2002,
26, 1085; (e) N. A. Bokach, M. Haukka, A. J. L. Pombeiro, S. N.
Morozkina and V. Yu Kukushkin, Inorg. Chim. Acta, 2002, 336, 95;
(f) V. Yu. Kukushkin, T. B. Pakhomova, N. A. Bokach, G. Wagner,
M. L. Kuznetsov, M. Galanski and A. J. L Pombeiro, Inorg. Chem.,
2000, 39, 216; (g) D. A. Garnovskii, M. F. C. Guedes da Silva, T. B.
Pakhomova, G. Wagner, M. T. Duarte, J. J. R. Frau´sto, da Silva, A. J. L.
Pombeiro and V. Yu. Kukushkin, Inorg. Chim. Acta, 2000, 300–302,
499; (h) V. Yu. Kukushkin, T. B. Pakhomova, Y. N. Kukushkin, H.
Herrmann, G. Wagner and A. J. L. Pombeiro, Inorg. Chem., 1998, 37,
6511; (i) G. Wagner, T. B. Pakhomova, N. A. Bokach, J. J. R. Frau´sto
da Silva, J. Vicente, A. J. L. Pombeiro and V. Yu. Kukushkin, Inorg.
Chem., 2001, 40, 1683.
=
=
trans-[PtCl2{N(H) C(CH2Cl)ON C(Me)(Et)}2]. C12H22N4O2-
Cl4Pt, M = 591.23, tetragonal, space group, I41/a (no. 88),
3
˚
˚
a = b = 10.9223, c = 34.2519(39) A, U = 4086.1(5) A , Z =
8 l(Mo-Ka) = 7.402 mm−1. Intensity data were collected using
a Bruker AXS-KAPPA APEX II diffractometer using graphite
monochromated Mo-Ka radiation. Data was collected at 130 K
using omega scans of 0.5◦ per frame and a full sphere of data
was obtained. Cell parameters were retrieved using Bruker
SMART software and refined using Bruker SAINT on all the
observed reflections. Absorption corrections were applied using
SADABS. Structure was solved by direct methods by using the
SHELXS-97 package23 and refined with SHELXL-9724 with the
WinGX graphical user interface.25 All hydrogens were inserted in
calculated positions except H1 which was located. Least square
refinement with anisotropic thermal motion parameters for all the
non-hydrogen atoms and isotropic for the remaining atoms gave
R1 = 0.0342 [I > 2r(I)]; R1 = 0.0681 (all data)]. The maximum
and minimum peaks in the final difference electron density map
8 G. Wagner, A. J. L. Pombeiro, N. A. Bokach and V. Yu Kukushkin,
J. Chem. Soc., Dalton Trans., 1999, 4083.
9 V. Yu. Kukushkin, I. V. Ilichev, G. Wagner, J. J. R. Frau´sto da Silva and
A. J. L. Pombeiro, J. Chem. Soc., Dalton Trans., 1999, 3047.
10 D. A. Garnovskii, N. A. Bokach, A. J. L. Pombeiro, M. Haukka,
J. J. R. Frau´sto da Silva and V. Yu. Kukushkin, Eur. J. Inorg. Chem.,
2005, 3467.
−3
˚
are of 1.242 and −1.109 e A , located around the Cl2 atom.
CCDC reference number 617145.
5066 | Dalton Trans., 2006, 5062–5067
This journal is
The Royal Society of Chemistry 2006
©

View Article Online
11 (a) N. A. Bokach, T. V. Kuznetsova, S. A. Simanova, M. Haukka,
A. J. L. Pombeiro and V. Yu. Kukushkin, Inorg. Chem., 2005, 44, 5152;
(b) N. A. Bokach, V. Yu. Kukushkin, P. F. Kelly, M. Haukka and A. J. L.
Pombeiro, Dalton Trans., 2005, 1354.
12 K. V. Luzyanin, V. Yu. Kukushkin, A. D. Ryabov, M. Haukka and
A. J. L. Pombeiro, Inorg. Chem., 2005, 44, 2944.
13 (a) J. Vicente, M. T. Chicote, M. A. Beswick and M. C. Ram´ırez
de Arellano, Inorg. Chem., 1996, 35, 6592; (b) J. Vicente, M. T.
Chicote, J. Ferna´ndez-Baeza, F. J. Lahoz and J. A. Lopez, Inorg.
Chem., 1991, 30, 3617; (c) E. Ciganek, J. Org. Chem., 1970, 35,
3631.
14 M. F. C. Guedes da Silva, J. J. R. Frau´sto da Silva and A. J. L. Pombeiro,
Inorg. Chem., 2002, 41, 219.
Vicente, A. J. L. Pombeiro and V. Yu. Kukushkin, Inorg. Chem., 2001,
40, 1683.
18 C. M. P. Ferreira, M. F. C. Guedes da Silva, J. J. R. Frau´sto da Silva,
A. J. L. Pombeiro, V. Yu. Kukushkin and R. A. Michelin, Inorg. Chem.,
2001, 40, 1134.
19 M. A. Charmier-Janua´rio, M. Haukka and A. J. L. Pombeiro, Dalton
Trans., 2004, 2741.
20 (a) Microwaves in Organic Synthesis, ed. A. Loupy, Wiley/VCH, Wein-
heim, 2002; (b) Microwave Assisted Organic Synthesis, ed. J. P. Tierney
and P. Lidstro¨m, Blackwell Publishing/CRC Press, Oxford, 2005.
21 (a) A. K. Mukerjee and R. C. Srivastava, Synthesis, 1973, 327;
(b) Chemistry and Biology of b-Lactam Antibiotics, ed. R. B. Morin
and M. Gorman,Academic Press, New York, 1982, vol. 1–3; (c) The
Chemistry of b-Lactam, ed. M. I. Page, Chapman and Hall, London,
1997; (d) Comprehensive Asymmetric Catalysis, ed. E. N. Jacobsen,
A. Pfaltz and H. Yamamoto, Springer, Berlin, 1999.
22 N. A. Bokach, V. Yu. Kukushkin, M. Haukka, J. J. R. Frau´sto da Silva
and A. J. L. Pombeiro, Inorg. Chem., 2003, 42, 3602.
23 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
24 G. M. Sheldrick, SHELXL-97, University of Gottingen, Germany,
1997.
15 S. M. P. R. Cunha, M. F. C. Guedes da Silva and A. J. L. Pombeiro,
Inorg. Chem., 2003, 42, 2157.
16 (a) M. L. Kuznetsov, V. Yu. Kukushkin, A. I. Dement’ev and A. J. L.
Pombeiro, J. Phys. Chem. A, 2003, 107, 6108; (b) M. L. Kuznetsov, V.
Yu. Kukushkin, M. Haukka and A. J. L. Pombeiro, Inorg. Chim. Acta,
2003, 356, 85; (c) M. L. Kuznetsov, N. A. Bokach, V. Yu. Kukushkin,
T. Pakkanen, G. Wagner and A. J. L. Pombeiro, J. Chem. Soc., Dalton
Trans., 2000, 4683.
17 G. Wagner, T. B. Pakhomova, N. A. Bokach, J. J. R. Frau´sto da Silva, J.
25 L. J. Farrugia, J. Appl. Crystallogr., 1999, 32, 837.
This journal is
The Royal Society of Chemistry 2006
Dalton Trans., 2006, 5062–5067 | 5067
©