First example of an imine addition to coordinated isonitrile

Article abstract of DOI:10.1016/j.ica.2008.02.026

The interplay between cis-[PtCl₂{CNC₆H₃(2,6-Me₂)}₂] and Ph₂C{double bond, long}NH results in the addition of benzophenone imine to one isonitrile ligand to yield the aminoimino-carbene cis-

Full text of DOI:10.1016/j.ica.2008.02.026

Available online at www.sciencedirect.com
Inorganica Chimica Acta 362 (2009) 833–838
www.elsevier.com/locate/ica
First example of an imine addition to coordinated isonitrile
Konstantin V. Luzyanin a,b, M. Fatima C. Guedes da Silva ,
a,c
´
Vadim Yu. Kukushkin b,d,*, Armando J.L. Pombeiro a,*
a Centro de Quı´mica Estrutural, Complexo I, Instituto Superior Te´cnico, TU Lisbon, Av. Rovisco Pais, 1049-001 Lisbon, Portugal
b Department of Chemistry, St.Petersburg State University, 198504 Stary Petergof, Russian Federation
c Universidade Luso´fona de Humanidades e Tecnologias, ULHT Lisbon, Campo Grande, 376, 1749-024 Lisbon, Portugal
d Institute of Macromolecular Compounds of the Russian Academy of Sciences, V. O. Bolshoi Pr. 31, 199004 St.Petersburg, Russian Federation
Received 10 December 2007; accepted 10 February 2008
Available online 20 February 2008
Dedicated to Professor Bernhard Lippert as a sign of appreciation of his contributions to the platinum group metal chemistry.
Abstract
The interplay between cis-[PtCl2{CNC6H3(2,6-Me2)}2] and Ph2C@NH results in the addition of benzophenone imine to one isonitrile
ligand to yield the aminoimino-carbene cis-[PtCl2{CNC6H3(2,6-Me2)}{C(N@CPh2)N(H)C6H3(2,6-Me2)}]. The formulation of the latter
1
compound is based on the coherent H and 13C{1H} NMR and ESI-MS data. This adduct is not stable in solution even at room tem-
perature leading to diamino-carbene cis-[PtCl2{CNC6H3(2,6-Me2)}{C(NH2)N(H)C6H3(2,6-Me2)}], which is, formally, the product of the
addition of ammonia to one isonitrile ligand in cis-[PtCl2{CNC6H3(2,6-Me2)}2].
Ó 2008 Elsevier B.V. All rights reserved.
Keywords: Isonitriles; Platinum(II) complexes; Imine; Nucleophilic addition; Aminoimino-carbene; Diamino-carbene
1. Introduction
the additions of ammonia, primary or secondary amines
to metal-complexed RCN [4] and RNC molecules [8] are
well documented and this interplay brings about formation
of the amidine NH@C(R)NR0R00 and the amino-carbene
C(NR0R00)N(H)R ligands, respectively.
Activation of unsaturated substrates by their coordina-
tion to metal centers, especially those molecules whose
reactivity is not strongly pronounced, e.g., dinitrogen,
nitriles or isonitriles, is currently a research area of a para-
mount importance [1–9]. The activation provided by metal
centers can promote chemical transformations that are not
feasible for the metal-free species [4–9].
Among the reactions of coordinated nitriles and isoni-
triles, special attention has been dedicated to their coupling
with various types of nucleophiles, for instance, bearing
HN donor centers; these reactions give a great variety of
new ligated species with C–N bonds [4]. In this context,
In contrast to the additions of nucleophiles with sp3-N
donor centers, interaction of RCN and RNC ligands with
sp2-N nucleophiles such as imines is much less explored.
Indeed, although the coupling between nitriles and imines
[10–14] and heteroimines [15–19] at Pt centers has recently
been observed by some of us, the corresponding reactions
of metal-bound isonitriles and imines have never been
reported up to date. In this work, we extended our previous
studies on the addition of sp2-N nucleophiles to platinum-
bound nitriles to other Pt-ligated unsaturated substrates,
viz. isonitriles RN„C, and found the first example of
RNC–imine integration to furnish an imino-carbene moi-
ety. Isonitriles are isoelectronic with nitriles and since long
have been the object of attention of some of us, namely
toward their activation by coordination [7–9,20–30].
*
Corresponding authors. Present address: Department of Chemistry,
St.Petersburg State University, 198504 Stary Petergof, Russian Federa-
tion.
E-mail addresses: kukushkin@VK2100.spb.edu (V.Yu. Kukushkin),
pombeiro@ist.utl.pt (A.J.L. Pombeiro).
0020-1693/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2008.02.026

834
K.V. Luzyanin et al. / Inorganica Chimica Acta 362 (2009) 833–838
2. Experimental
and the yellow residue formed was washed with two 10-
mL portions of diethyl ether and dried in air at 20–25 °C.
The obtained solid residue (mixture of III and IV) was ana-
lyzed by ESI-MS, NMR and IR methods. ESI+-MS, m/z:
748 [MIII+K]+, 728 [MIV+H]+, 691 [MIIIꢀCl+OH]+, 545
[MIV]. ESIꢀ, m/z: 748 [MIII+K]ꢀ, 708 [MIIIꢀH]ꢀ, 364
Me), 2.12 (s, Me), 6.10–7.54 (m, aryls). 13C{1H} NMR in
CDCl3, d: 9.5 (Me), 11.5 (Me), 127.8, 128.3, 128.4, 128.5,
128.7, 128.8, 129.6, 130.0, 131.7, 132.4, 134.3, 135.7 (aryls;
Supplementary Fig. 1S), 172.4 (N@CPh2), 196.2 (C@N).
IR spectrum (selected bands), cmꢀ1: 3228 mw m(N–H),
3187 mw m(N–H), 2220 s m(C„N), 2196 s m(C„N), 1652
s m(C@N), 1619 s m(C@N), 1605 s m(C@N), 1598 s
m(C@N), 1475 s m(C@C), 782 s d(C–H), 775 s d(C–H). Slow
evaporation of an acetone solution of the obtained solid in
air at 20–25 °C for 1 d gives crystals of IV suitable for X-
ray diffraction along with some non-crystalline material.
2.1. Materials and instrumentation
Solvents were obtained from commercial sources and
used as received, while chloroform was conventionally
dried over CaCl2. Benzophenone imine (Aldrich) was used
without additional purification. The complex cis/trans-
[PtCl2(EtCN)2] was prepared as previously described [31].
C, H, and N elemental analyses were carried out by the
[MIII+OH]2ꢀ 1H NMR spectrum in CDCl3, d: 2.08 (s,
.
´
Microanalytical Service of the Instituto Superior Tecnico.
ESI+ mass-spectra were obtained on VARIAN 500-MS
LC ion trap mass spectrometer. Infrared spectra (4000–
400 cmꢀ1) were recorded on a BIO-RAD FTS 3000MX
instrument in KBr pellets. 1D (1H, 13C{1H}, 195Pt) NMR
spectra and 2D (1H,1H-COSY, 1H,13C-HMQC, 1H,13C-
1
HSQC and H,13C-HMBC) NMR correlation experiments
were recorded on Bruker Avance II+ 400 and 500 MHz
(UltraShieldTM Magnets) spectrometers at ambient temper-
ature. 195Pt NMR chemical shifts are given relatively to
K2[PtCl6] (0.0 ppm).
2.2.3. Interaction of cis-[PtCl2{CNC6H3(2,6-Me2)}2] and
Ph2C@NH in 1:2 molar ratio
A solution of Ph2C@NH (0.036 g, 0.20 mmol) in CHCl3
(5 mL) was added to a suspension of II (0.053 g,
0.10 mmol) in CHCl3 (10 mL) and the reaction mixture
was refluxed for ca. 2 h until homogenization forming a
bright yellow solution. This solution was evaporated to
dryness at 20–25 °C under a stream of dry N2, and the yel-
low solid residue formed was washed with two 10-mL por-
tions of diethyl ether and dried in air at room temperature.
Slow evaporation of an acetone solution of the obtained
solid in air at 20–25 °C for 1 d leads to crystals of V suit-
able for X-ray diffraction.
2.2. Synthetic work
2.2.1. Synthesis of cis-[PtCl2{CNC6 H3(2,6-Me2)}2] (II)
A
suspension of cis/trans-[PtCl2(EtCN)2] (0.38 g,
1 mmol) in CHCl3 (20 mL) was refluxed for ca. 5 min until
complete dissolution of the starting material, whereupon a
solution of C„NC6H3(2,6-Me2) (0.26 g, 2 mmol) in CHCl3
(5 mL) was added. In ca. 5 min after the addition, a bright
yellow precipitate started to release. The reaction mixture
was refluxed for 3 h giving a bright yellow precipitate under
a yellow supernatant solution. The precipitate was filtered
off, washed with one portion of cold acetone (10 °C;
5 mL) and with three 15-mL portions of diethyl ether and
dried in vacuo at 20–25 °C. An additional amount of II
was obtained upon evaporation of the filtrate from the
reaction mixture to ca. 1/2 and followed by the addition
of diethyl ether (5 mL). Total yield is 90%, based on Pt.
Anal. Calc. for C18H18N2Cl2Pt: C, 40.92; H, 3.43; N,
5.30. Found: C, 40.80; H, 3.24; N, 5.42%. ESI+-MS, m/z:
529 [M+H]. IR spectrum (selected bands), cmꢀ1: 2920 m
[PtCl{CNC6H3(2,6-Me2)}{C(NH2)N(H)C6H3(2,6-
Me2)}(Ph2C@NH)]Cl
(V).
Anal.
Calc.
for
C31H32N4Cl2Pt: C, 51.24; H, 4.44; N, 7.71. Found: C,
51.34; H, 4.67; N, 7.53%. IR spectrum (selected bands),
cmꢀ1: 3284 mw m(N–H), 2196 s m(C„N), 1652 w
m(C@N), 1620 s m(C@N), 1598 s m(C@N), 1473 s m(C@C),
775 s d(C–H). ESI+-MS, m/z: 691 [McationꢀH]+. 1H
NMR spectrum in (CD3)2CO, d: 2.32 (s, 6H, Me), 2.46
(s, 6H, Me), 7.10–7.78 (m, 16H, aryls). 13C{1H} NMR in
(CD3)2CO, d: 18.5 and 19.2 (Me), 119.2, 121.8, 128.9,
129.3, 130.2, 138.3, 140.2, 143.2 (aryls), 118.8 (C„NR),
179.2 (N@CPh2), 194.6 (C@N). 195Pt NMR in (CD3)2CO,
d: ꢀ2014 (120 Hz).
1
m(C–H), 2205, 2230 s m(C„NR), 830 m d(C–H) (aryl). H
NMR spectrum in CDCl3, d: 2.50 and 2.51 (s, 6H, Me),
7.17–7.33 (m, 3H, aryls). 13C{1H} NMR in CDCl3, d:
18.8 (Me), 128.5, 128.6, 130.7, 131.1, 136.2 (aryls), 117.4
(br, C„NR). 195Pt NMR in CDCl3, d: ꢀ2230 (120 Hz).
2.3. X-ray structure determinations
2.2.2. Reaction between II and Ph2C@NH taken in
equimolar amounts
Intensity data for complexes IV and V were collected
using a Bruker AXS-KAPPA APEX II diffractometer
using graphite monochromated Mo Ka radiation. Data
was collected at 150 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. Absorp-
tion corrections were applied using SADABS. Structure was
solved by direct methods by using the SHELXS-97 package
A solution of Ph2C@NH (0.018 g, 0.10 mmol) in CHCl3
(5 mL) was added to a suspension of II (0.053 g,
0.10 mmol) in CHCl3 (10 mL) and the reaction mixture
was refluxed for ca. 2 h until homogenization forming a
bright yellow solution with some opalescence. The solution
was filtered off from small undissolved impurities, evapo-
rated to dryness at 20–25 °C under a stream of dry N2,

K.V. Luzyanin et al. / Inorganica Chimica Acta 362 (2009) 833–838
835
[32] and refined with SHELXL-97 [33] with the WINGX graph-
ical user interface [34]. All hydrogens were inserted in cal-
culated positions. Least square refinement with anisotropic
thermal motion parameters for all the non-hydrogen atoms
and isotropic for the remaining atoms gave R1 = 0.0299
(IV) and 0.0390 (V). The maximum and minimum peaks
in the final difference electron density maps are close to
the platinum atoms.
ꢀ2031 ppm and it corresponds to the sole isomer, while
in the 13C{1H} spectrum, a weak and very broad (due to
the unresolved 13C–195Pt coupling) signal at ca. 117 ppm,
corresponding to the Pt-bound isonitrile moiety is
observed.
The interaction between the isonitrile species in II and
Ph2C@NH has been studied in CDCl3 by 1H and
13C{1H} NMR and ESI-MS and it was found that this
interplay results in the previously unreported addition of
an imine to one isonitrile ligand leading to the aminoimi-
3. Results and discussion
no-carbene
complex
cis-[PtCl2{CNC6H3(2,6-Me2)}-
For this study we addressed, on one hand, the plati-
num(II) isonitrile complex cis-[PtCl2{CNC6H3(2,6-
Me2)}2] and, on the other hand, benzophenone imine,
Ph2C@NH, which represents a stable imine useful as a
model for reactivity studies [10–14].
{C(N@CPh2)N(H)C6H3(2,6-Me2)}] (III) (Scheme 1). Thus,
after mixing equimolar amounts of II and Ph2C@NH, only
one signal (ca. 178 ppm) corresponding to d(C@N) from
the free unreacted Ph2C@NH was observed in the low-field
region (150–200 ppm) of the 13C{1H} spectrum. After heat-
ing of the reaction mixture at 55 °C for 2 h, two new signals
emerge (at ca. 196 and 172 ppm) and they belong to the
C@N(H)R and N@CPh2 imine moieties from the newly
formed C(N@CPh2)N(H)C6H3(2,6-Me2) ligand. The
inspection of the low-field region of the 13C{1H} spectrum
(Fig. 1S; see Supplementary material) of this reaction mix-
ture allows the recognition not only of the resonances from
those groups (including corresponding aryl/phenyl signals
from carbene and imine species), but also of the aryl/phe-
nyl resonances of the unreacted isonitrile ligand, and of
the free Ph2C@O originating from the hydrolysis of
Ph2C@NH (this was proved upon addition of commer-
cially available Ph2C@O to a sample of a reaction solution
A
common method for preparation of isonitrile
complexes of the type cis-[PtCl2(CNR)2] employs ‘‘the
Magnus salts” [Pt(CNR)4][PtCl4], obtained from K2[PtCl4]
and RNC in water, followed by thermolysis of
[Pt(CNR)4][PtCl4] to furnish cis-[PtCl2(CNR)2] [35]. Other
synthetic routes leading to cis-[PtX2(CNR)2] are also
known and they include, e.g., substitution of two Xꢀ
ligands in K2[PtX4] (X = Cl [36], SCN [37]) or replacement
of 1,5-cyclooctadiene in cis-[PtCl2(COD)] [38] with RNC.
In our study, the complex cis-[PtCl2{CNC6H3(2,6-Me2)}2]
(II) was prepared by substitution of the propiononitrile
ligands from cis/trans-[PtCl2(EtCN)2] (I) (containing ca.
80% of the cis isomer; based on the data of 1H NMR spec-
troscopy) with C„NC6H3(2,6-Me2). Thus, the reaction of
I with C„NC6H3(2,6-Me2) in a molar ratio 1:2 in CHCl3
upon reflux for ca. 2 h results in formation of II, which
1
and repeated run of the spectrum). The H and 13C{1H}
peak assignment performed using the conventional 2D
1H,1H-COSY, 1H, 13C-HMQC/1H,13C-HSQC, and
1H,13C-HMBC correlation experiments supports the for-
mulation of III. ESI+ and ESIꢀ mass-spectra of the reac-
tion mixture measured after heating for 2 h shows the
presence of the molecular ion and certain fragmentation
peaks, whose isotopic patterns are in a good agreement
with the calculated ones (ESI+-MS, m/z: 748 [M+K]+,
691 [MꢀCl+OH]+; ESI ꢀ-MS, m/z: 748 [M+K]ꢀ, 708
[MꢀH]ꢀ, 364 [M+OH]2ꢀ).
1
was isolated in ca. 90% yield; the mixture, based on H
NMR spectroscopy data, contains ca. 95% of the cis-
isomer.
Complex II was characterized by elemental analyses,
1
ESI mass-spectrometry, IR, H and 13C{1H} NMR spec-
troscopies. In the IR spectrum, II shows no m(N„C) vibra-
tions from the starting nitrile complex (2314 and
2342 cmꢀ1) [31], but the spectrum displays two very strong
stretches at 2205 and 2230 cmꢀ1
,
corresponding to
In the experiment, we also observed that III is not stable
in solution, even at room temperature, and it is gradually
converts to the diamino-carbene complex cis-[PtCl2-
{CNC6H3(2,6-Me2)}{C(NH2)N(H)C6H3(2,6-Me2)}] (IV);
all our attempts to isolate III as a solid failed. Complex
IV (Fig. 1) is at least formally a known product of the addi-
m(C„N) of the isonitrile ligands. The latter bands allow
the assignment of the cis-configuration of II because
usually in the corresponding symmetric trans-forms only
one m(C„N) signal is observed [35]. In the 195Pt NMR
spectrum measured in CDCl3, one resonance emerges at
H
Ph
Ph
N
Cl
Cl
R
Ph
Ph
Cl
Pt
C
N
R
+
Cl
Pt
C
HN
C
C
N
N
N
R
R
II
III
Scheme 1.

836
K.V. Luzyanin et al. / Inorganica Chimica Acta 362 (2009) 833–838
Ph
H
H
Pt
N
NH
N
Cl
R
R
C
Cl
Pt
Cl
Pt
C
C
C
NH2
NH2
N
N
R
R
IV
V
Fig. 1.
tion of ammonia to a Pt-bound isonitrile [8] and it could be
formed by one of the following routes: (i) hydrolytic
decomposition of III with formation of IV and liberating
of the free Ph2C@O, (ii) nucleophilic attack on platinum-
bound RNC by ammonia, formed upon the hydrolysis of
the free Ph2C@NH. However, the current system does
not allow the discrimination between these routes.
The influence of the molar ratio between the reactants
(II and Ph2C@NH) on the composition of products in
the final reaction mixture and on the reaction rates in dif-
ferent solvents was additionally studied. Thus, when the
molar ratio was 1:1, the reaction mixture after 2 h refluxing
comprised III and IV in ca. equal proportions, while after
12 h under reflux it contained ca. 80% of IV. After one
week at 20–25 °C, the reaction mixture contained ca.
50% of IV, along with some yet unidentified by-products.
When the reaction was performed in a 1:2 molar ratio,
[PtCl{CNC6H3(2,6-Me2)}{C(NH2)N(H)C6H3(2,6-Me2)}
(Ph2C@NH)]Cl (V), containing one coordinated benzophe-
none imine ligand was the isolated solid in ca. 80%
yield.
Fig. 2. Thermal ellipsoid view of complex IV with atomic numbering
scheme. Thermal ellipsoids are drawn with 50% probability. Selected bond
˚
lengths (A) and angles (°): Pt(1)–C(1) 1.884(6), Pt(1)–Cl(11) 2.3228(16),
C(1)–N(1) 1.152(9), Pt(1)–C(11) 1.983(7), C(11)–N(10) 1.333(9), C(11)–
N(11) 1.295(8), N(11)–C(12) 1.435(10), N(1)–C(101) 1.385(9), Pt(1)–C(1)–
N(1) 175.8(7), Cl(11)–Pt(1)–C(1) 177.38(18), Cl(12)–Pt(1)–C(11)
179.07(17), C(1)–N(1)–C(101) 170.5(6), C(11)–N(11)–C(12) 128.0(6).
The identification of III–V was performed using ESI-
MS, 1D (1H, 13C{1H}) and 2D (1H,1H-COSY, 1H,13C-
1
1
HMQC, H,13C-HSQC, and H,13C-HMBC) NMR exper-
iments and X-ray diffraction (for IV and V). In addition, V
was isolated in a pure form and characterized by elemental
analyses (C, H, N).
The structures of IV and V have been determined by X-
ray single-crystal diffraction (Figs. 2 and 3), and represent
the first crystallographic evidence for the ammonia–isoni-
trile coupling products ligated to a PtII center. In the crys-
tal unit of IV, two similar molecules are detected. In IV, the
chlorides are in the cis-position [Pt(1)–Cl(11) 2.3228(16),
Fig. 3. Thermal ellipsoid view of complex V with atomic numbering
scheme. Thermal ellipsoids are drawn with 50% probability. Selected bond
˚
lengths (A) and angles (°): Pt(1)–C(1) 1.890(7), Pt(1)–C(2) 1.995(6), Pt(1)–
Cl(1) 2.3613(15), Pt(1)–N(3) 2.038(6), C(1)–N(1) 1.151(9), C(2)–N(2)
1.330(8), N(3)–C(3) 1.279(9), C(2)–N(22) 1.310(8), N(1)–C(11) 1.415(9),
N(2)–C(21) 1.441(8), Cl(1)–Pt(1)–(C2) 179.13(17), C(1)–Pt(1)–N(3)
171.6(3), Pt(1)–C(1)–N(1) 172.2(6), Pt(1)–C(2)–N(2) 119.8(4), Pt(1)–
N(3)–C(3) 135.6(5), C(1)–N(1)–C(11) 175.2(7), C(2)–N(2)–C(21) 125.2(6).
˚
Pt(1)–Cl(12) 2.366(2) A] and one isonitrile CNC6H3(2,6-
Me2) and one diamino-carbene C(NH2)N(H)C6H3(2,6-
Me2) complete the slightly distorted square planar environ-
ment [Cl(11)–Pt(1)–C(1) 177.38(18)°, Cl(12)–Pt(1)–C(11)
179.07(17)°]. The newly formed diamino-carbene ligand is
in the E-configuration, and the Pt–Ccarbene [Pt(1)–C(11)
˚
1.983(7) A] bond distance is in a good agreement with that
˚
moiety [1.152(9) A] is of a typical value for platinum com-
previously observed in the related complex [Pt{g2-(S,S0)-
plexes containing the CNC6H3(2,6-Me2) ligand, e.g., as
t
t
˚
reported in [Pt{g2-(S,S0)-S2C@ C{C(O)Me}2}{CNC6H3-
S2C@ C(C(O)Me)}(CNBu ){C(NEt2)(NHBu )}] [2.053(2) A]
[39], while the Ccarbene–N [C(11)–N(11) 1.295(8)] distance
˚
(2,6-Me2)}2] [1.152(3) A] [39]. All other bond lengths are
˚
is slightly shorter than that in the former [1.334(3) A]
of normal values and agree with those observed in related
platinum(II) aminocarbene and isonitrile complexes [8,9].
[39]. The C(1)–N(1) triple bond of the unreacted isonitrile

K.V. Luzyanin et al. / Inorganica Chimica Acta 362 (2009) 833–838
837
The coordination polyhedron of V is a slightly distorted
square plane [Cl(1)–Pt(1)–(C2) 179.13(17)°, C(1)–Pt(1)–
N(3) 171.6(3)°]. In V, the chloride is in the trans position
to the diamino-carbene ligand C(NH2)N(H)C6H3(2,6-
Me2), with the coordinated benzophenone imine
Ph2C@NH and one isonitrile CNC6H3(2,6-Me2) complet-
ing the coordination environment. The carbene ligand is
in the E-configuration and both Pt–Ccarbene [Pt(1)–C(2)
Portugal). This work has also been supported by the Rus-
sian Fund for Basic Research (Grant 06-03-32065).
Appendix A. Supplementary material
CCDC 670267 and 670268 contain the supplementary
crystallographic data for cis-[PtCl2{CNC6H3(2,6-Me2)}-
{C(NH2)N(H)C6H3(2,6-Me2)}] and [PtCl{CNC6H3(2,6-Me2)}-
{C(NH2)N(H)C6H3(2,6-Me2)}(Ph2C@NH)]Cl. These data
can be obtained free of charge from The Cambridge Crys-
tallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this
article can be found, in the online version, at
doi:10.1016/j.ica.2008.02.026.
˚
˚
1.995(6) A] and Ccarbene–N [C(2)–N(2) 1.330(8) A]
distances are in a good agreement with those previously
observed in the related diamino-carbene complex [Pt-
{g2-(S,S0)-S2C@C(C(O)Me)}(CNBut){C(NEt2)(NHBut)}]
˚
[2.053(2) and 1.334(3) A, correspondingly] [39]. The C(1)–
˚
N(1) triple bond of the isonitrile ligand [1.151(9) A] is of
a normal value for the triple CN bond and coherent with
that observed in the related isocyanide platinum complex
[Pt{g2-(S,S0)-S2C@C{C(O)Me}2}{CNC6H3(2,6-Me2)}2]
References
˚
˚
[1] A.J.L. Pombeiro, V.Yu. Kukushkin, Ligand reactivity: general
introduction, 2nd ed., in: A.B.P. Lever (Ed.), Comprehensive Coor-
dination Chemistry, vol. 1, Elsevier, New York, 2004, p. 585 (Chapter
1.29).
[1.152(3) A] [39]. The Pt(1)–N(3) distance [2.038(6) A]
between the metal atom and the ligated Ph2C@NH agrees
with that reported in the related (benzophenone imine)PtII
˚
complexes, e.g., [PtCl2(Ph2C@NH)(R2SO)] [2.017–2.024 A]
[2] J.A. Davies, C.M. Hockensmith, V.Yu. Kukushkin, Yu.N. Kukush-
kin, Synthetic Coordination Chemistry: Principles and Practice,
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˚
[1.279(9) A] is of a typical C@N bond, and its value corre-
˚
lates with that in [PtCl2(Ph2C@NH)(R2SO)] [1.26–1.29 A]
[40]. All other bond lengths are of normal values and they
agree with those reported for related platinum(II) amino-
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4. Conclusions
To summarize, we observed the first example of reaction
between a Pt-bound isonitrile and an imine, i.e., Ph2C@NH,
which results in the addition of the latter to the former spe-
cies to give the aminoimino-carbene complex
cis-[PtCl2{CNC6H3(2,6-Me2)}{C(N@CPh2)N(H)C6H3(2,6-
Me2)}] (III). This addition product is not stable in solution,
even at room temperature, and it converts to cis-
[PtCl2{CNC6H3(2,6-Me2)}{C(NH2)N(H)C6H3(2,6-Me2)}]
(IV). Further works of our group in this direction will be
focused on the extension of this type of reaction to other
imines and isonitriles with the aim to discover more chem-
ically stable systems and to investigate their properties.
Acknowledgments
This work has been partially supported by the Fundaßcao
˜
para a Cieˆncia e a Tecnologia (FCT), Portugal, and its
POCI 2010 program (FEDER funded). K.V.L. express
gratitude to FCT and the POCI program (FEDER
funded), Portugal, for a fellowship (Grant SFRH/BPD/
27094/2006) and V.Y.K. is grateful to the FCT (Cientista
´
Convidado/Professor at the Instituto Superior Tecnico,

838
K.V. Luzyanin et al. / Inorganica Chimica Acta 362 (2009) 833–838
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