A novel reactivity mode for metal-activated dialkylcyanamide species: Addition of N,N'-Diphenylguanidine to a cis-(R2NCN)2PtII center giving an eight-membered chelated platinaguanidine

Article abstract of DOI:10.1021/ic802109d

The nucleophilic addition of N,N′-diphenylguanidine, HNdC(NHPh) ₂ (DPG), to two adjacent dialkylcyanamide ligands in cis-[PtCl ₂(NCNR₂)₂] (R = Me; R₂ = C ₅H₁₀, C₄H

Full text of DOI:10.1021/ic802109d

Inorg. Chem. 2009, 48, 2583-2592
A Novel Reactivity Mode for Metal-Activated Dialkylcyanamide Species:
Addition of N,N′-Diphenylguanidine to a cis-(R2NCN)2PtII Center Giving
an Eight-Membered Chelated Platinaguanidine
Pavel V. Gushchin,† Maxim L. Kuznetsov,‡ Matti Haukka,§ Meng-Jiy Wang,| Aleksander V. Gribanov,⊥
and Vadim Yu. Kukushkin*,†,⊥
Department of Chemistry, St. Petersburg State UniVersity, 198504 Stary Petergof, Russian
Federation, Department of Chemistry, Moscow Pedagogical State UniVersity,
119021 Moscow, Russian Federation, Department of Chemistry, UniVersity of Joensuu,
P.O. Box 111, FI-80101 Joensuu, Finland, Department of Chemical Engineering, National Taiwan
UniVersity of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan, and
Institute of Macromolecular Compounds, Russian Academy of Sciences, V. O. Bolshoi Pr. 31,
199004 St. Petersburg, Russian Federation
Received November 4, 2008
The nucleophilic addition of N,N′-diphenylguanidine, HNdC(NHPh)2 (DPG), to two adjacent dialkylcyanamide ligands
in cis-[PtCl2(NCNR2)2] (R ) Me; R2 ) C5H10, C4H8O) gives unusual eight-membered chelates [PtCl2{NHdC-
(NR2)N(Ph)C(dNH)N(Ph)C(NR2)dNH}] (1-3) with trisguanidine as the cyclic ligand, in which the central guanidine
dNH group remains uncoordinated. Treatment of trans-[PtCl2(NCNR2)2] (R ) R ) Me; R2 ) C5H10, C4H8O) with
1 equiv of HNdC(NHPh)2 in a solution (R ) R ) Me; R2 ) C5H10) or in a suspension (R2 ) C4H8O) of CHCl3
or MeNO2 at 20-25 °C for 20 h results in the generation of the 1,3,5-triazapentadiene monochelates
[PtCl{NHdC(NR2)N(Ph)C(NH2)dNPh}(NCNR2)](Cl) (4-6). When any of trans-[PtCl2(NCNR2)2] reacts with 2 equiv
of DPG at 20-25 °C for 1-2 days or 4-6 are treated with 1 equiv more of HNdC(NHPh)2 at the same temperature,
the complexes bearing two chelate rings [Pt{NHdC(NR2)N(Ph)C(NH2)dNPh}2](Cl)2 (7-9) are formed. The formulation
of the obtained complexes was supported by satisfactory C, H, and N elemental analyses, agreeable ESI+-MS, IR
1
and H and 13C{1H} NMR spectroscopies; the structures of 1 and 2 were determined by the single-crystal X-ray
diffraction. Theoretical studies (at the B3LYP level of theory) revealed that the alkylnitrile eight-membered product
is significantly less stable than the corresponding cyanamide species 1-3, and this fact, at least partially, explains
why the former was not detected in the reaction between cis-dinitrileplatinum(II) complexes and DPG.
Introduction
of new compounds, often unreachable in metal-free organic
synthesis, via C-O, C-N, C-C, C-P, and C-S bond
making, (ii) of providing an environmentally friendly metal-
catalyzed hydrolytic transformation of RCN species to
amides, e.g., those of industrial and pharmacological sig-
nificance,3 and (iii) of synthesizing, via nucleophilic addition,
diverse imino complexes.4
Reactions of metal-activated RCt N species are one of
the frontier areas of current research on ligand reactivity and
also organic synthesis involving metal complexes. This topic
has been the subject of comprehensive reviews1 including
surveys by one of us.2,3 In general, interest in the conversions
of nitriles at metal centers stems from the possibility (i) of
using RCN species as versatile synthons for the preparation
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* To whom correspondence should be addressed. E-mail: kukushkin@
vk2100.spb.edu.
†
St. Petersburg State University.
Moscow Pedagogical State University.
University of Joensuu.
National Taiwan University of Science and Technology.
‡
§
|
⊥
Russian Academy of Sciences.
10.1021/ic802109d CCC: $40.75  2009 American Chemical Society
Inorganic Chemistry, Vol. 48, No. 6, 2009 2583
Published on Web 02/16/2009

Gushchin et al.
Scheme 1
Despite the wealth of chemistry associated with metal-
bound conVentional nitriles RCN (R ) alkyl, aryl), the
coordination chemistry of the so-called push-pull nitriles5
(a push-pull system is highly polarized, and it is character-
ized by an electron-withdrawing substituent or an electro-
negative atom on one side of the multiple bond and an
electron-donating substituent on the other side), such as, e.g.,
dialkylcyanamides R2NCN, has so far been little explored,
although data gradually accumulated in the literature indicate
that the R2NCN ligands might exhibit some exciting reactiv-
ity modes unknown for alkyl- or arylnitrile ligands.6-8 This
dissimilarity, in view of our general interest in the reactions
of nitrile ligands,2,3,9-11 prompted us to distinguish reactivity
differences between the push-pull and conventional nitrile
species ligated to a PtII center.
We have recently reported11 on the coupling between N,N′-
diphenylguanidine, HNdC(NHPh)2 (DPG), and coordinated
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Pombeiro, A. J. L.; Kukushkin, V. Yu. Reactions of Coordinated
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New York , 2004; Vol. 1, Chapter 1.34, pp 639-660. Bokach, N. A.;
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nitriles in the PtII complexes cis- and trans-[PtCl2(RCN)2]
(R ) Me, Et, CH2Ph, Ph), which proceeded rapidly under
mild conditions and afforded the 1,3,5-triazapentadiene
compounds. As a continuation of the project focused on the
study of reactivity differences between push-pull and
conventional nitrile species ligated to a PtII center, we
attempted the reaction between the dialkylcyanamideplati-
num(II) precursors [PtCl2(NCNR2)2] and DPG and found that
the process involving the dialkylcyanamide complexes
proceeds in another direction than that which occurred with
the structurally similar (RCN)2PtII species. Herein we report
on the study of the reaction between the PtII complexes
[PtCl2(NCNR2)2] and DPG, where we verified significant
reactivity differences between the push-pull and conven-
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Results and Discussion
We choose as starting materials for this study the dialkyl-
cyanamide compounds [PtCl2(NCNR2)2] (R ) Me; R2 )
C5H10, C4H8O).6 The route of the reaction between these
species and DPG strongly depends on cis or trans configu-
ration of the starting metal complex. Accordingly, in the
sections that follow, we consider interplay between DPG and
cis-(R2NCN)2PtII and then with trans-(R2NCN)2PtII centers.
Dialkylcyanamide-Guanidine Coupling at cis-(R2NCN)2-
PtII Centers. We have recently reported11 on the reaction of
two adjacent nitrile ligands in cis-[PtCl2(RCN)2] (R ) Me,
Et, CH2Ph, Ph) upon their interaction with HNdC(NHPh)2,
which afforded the 1,3,5-triazapentadiene compounds
[PtCl2{NHdC(R)NHC(R)NH}] and biguanidine (Scheme 1,
route A).
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M. L.; Kukushkin, V. Yu. Dalton Trans. 2008, 5178.
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M.; Wang, M.-J.; Lai, C.-H.; Chou, P.-T.; Kukushkin, V. Yu. Inorg.
Chem. 2008, 47, 11487.
In contrast to the reaction of DPG with the conventional
nitrile complexes (route A), its reaction with two adjacent
2584 Inorganic Chemistry, Vol. 48, No. 6, 2009

Metal-ActiWated Dialkylcyanamide Species
Scheme 2
dialkylcyanamide ligands in cis-[PtCl2(NCNR2)2] (R ) Me;
R2 ) C5H10, C4H8O) in a molar ratio of 1:1 proceeds in
MeNO2 or CHCl3 at 20-25 °C for ca. 1 day and gives
unusual eight-membered chelated complexes 1-3 with
trisguanidine (IUPAC name12 for the trisguanidine ligand:
N-[(dimethylamino)(imino)methyl]-N′,N′-dimethyl-N,N-di-
phenylimidodicarbonimidic diamide]) as the cyclic ligand, in
which the central guanidine dNH group remains uncoordinated
(Scheme 1, route B). If the syntheses were carried out in
MeNO2, pure complexes 1-3 were isolated in good yields (ca.
75%), while in CHCl3, the reaction is less selective and the
yields after column chromatography (or after crystallization and
purification under a layer of EtOH) are 50-60%.
Thus, the novel reaction for platinum-activated dialkyl-
cyanamide species, i.e., nucleophilic addition of DPG to two
dialkylcyanamide ligands of the cis-(R2NCN)2PtII center,
gives the previously unreported eight-membered chelated
platinaguanidines. Chelates 1-3 exhibit surprising stability,
and no transformation was observed upon keeping these
complexes at 25 °C for at least 2 years. Moreover, they
decompose to yield a broad spectrum of yet unidentified
species upon heating in the solid phase at elevated temper-
atures (>160 °C; see the Experimental Section) or upon
prolonged reflux in dichloroethane (ca. 83 °C; >15 h).
It is worth mentioning that five- and six-membered
metal chelate rings are the most conventional ring systems
in coordination chemistry insofar as they exhibit excep-
tional stablity13,14 (for general consideration of the chelate
effect, see refs15-17). However, seven-,18-22 eight- (in
particular, having N∩N,19,20,23-25 P∩P,21,26-28 S∩S,29,30
Se∩Se,30 O∩O,30-32 P∩O,33 and C∩O34 donor centers),19-35
nine-,20,24,27 ten-, eleven-, and twelve-membered and also
complexes with trans-spanned ligands36 and large metal-
lamacrocycles22,25-35,37 are also known, albeit they are
still unusual rather than common.
A plausible mechanism for the formation of eight-
membered chelates (Scheme 2) apparently involves (i) an
intermolecular nucleophilic attack of the PtII-activated di-
alkylcyanamide by the NPh center (route C) of the asym-
metric38 tautomer and (ii) tautomerization of the newly
formed ligand followed by ring closure via intramolecular
nucleophilic addition by the NPh center (route D).
One of the main reasons for the different chemical
behavior of dialkylcyanamide and alkylnitrile complexes may
be higher thermodynamic stability of complexes 1-3 in
comparison with similar eight-membered rings derived from
alkylnitrile species. Indeed, quantum-chemical calculations
indicate that the ∆Gs value of the formation of 1 from cis-
[PtCl2(NCNMe2)2] and DPG is 10.67 kcal/mol lower than
∆Gs of the formation of the corresponding acetonitrile deri-
vative cis-[PtCl2{NHdC(Me)N(Ph)C(dNH)N(Ph)C(Me)d
NH}] (1′) formed from cis-[PtCl2(NCMe)2] and DPG. The
higher relative stability of 1-3 compared to that of the
alkylnitrile derivatives is accounted for by additional reso-
nance stabilization in the former species including cyanamide
amino groups. The higher degree of bond delocalization in
1 than in 1′ is indicated by distributions of the bond orders
(Wiberg bond indices; see Scheme S2 in the Supporting
Information). Involvement of the NMe2 groups of 1 in
conjugation (see Scheme S3 in the Supporting Information)
is confirmed by sp2 orbital hybridization of the nitrogen seen
from the natural bond order analysis (Table S5 in the
Supporting Information) and also by X-ray data. A more
detailed description of the theoretical results is given in the
Supporting Information.
(12) http://www.iupac.org/nomenclature/index.html.
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Inorganic Chemistry, Vol. 48, No. 6, 2009 2585

Gushchin et al.
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Figure 1. Thermal ellipsoid view of 1 with an atomic numbering scheme.
Thermal ellipsoids are drawn with 50% probability. Selected bond lengths
(Å) and angles (deg): N1-C1 1.293(4), N2-C14 1.295(4), N5-C13
1.256(4), N4-C1 1.395(4), N7-C14 1.392(4), N4-C13 1.418(4), N7-C13
1.417(4); N2-Pt1-N1 93.93(10).
tions (medium-to-strong bands at 3477-3244 cm-1) are
displayed and no ν(C≡N) stretches of the dialkylcyanamide
ligands were observed.
In the 1H NMR spectra, complexes 1-3 reveal two singlets
of the NH protons at ca. 7.00 and 6.00 ppm in a ratio 1:1,
two doublets and three triplets in the region 7.61-7.21 ppm,
corresponding to the Ph protons. Data on variable-temper-
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are given in the Supporting Information.
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square-planar geometry, and two cis positions are occupied
with eight-membered bidentate ligands, while the other two
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2586 Inorganic Chemistry, Vol. 48, No. 6, 2009

Metal-ActiWated Dialkylcyanamide Species
the 1,3,5-triazapentadiene monochelates [PtCl{NHdC(NR2)-
N(Ph)C(NH2)dNPh}(NCNR2)](Cl) (4-6). When any of
trans-[PtCl2(NCNR2)2] reacts with 2 equiv of DPG at 20-25
°C for 1-2 days (Scheme 3, route J) or 4-6 are treated
with 1 equiv more of DPG at the same temperature, the
complexes bearing two chelate rings [Pt{NHdC(NR2)-
N(Ph)C(NH2)dNPh}2](Cl)2 (7-9) are formed. Further in-
creasing the quantity of DPG up to a molar ratio of the
reactants of 1:4 does not affect the reaction and also yields
of 7-9 (Scheme 3, route I). It is worth mentioning that the
coupling conditions giving the bischelates for the push-pull
nitrile trans-(R2NCN)2Pt species (Scheme 3, route J) are
much milder (20-25 °C) than those for conventional nitrile
trans-(RCN)2Pt complexes (75 °C) (Scheme 3, route G).
Inspecting the structures of 1,3,5-triazapentadiene species
derived, on the one hand, from the conventional organoni-
trileplatinum(II) complexes trans-[PtCl2(RCN)2] (R ) Et,
CH2Ph, Ph),11 and, on the other hand, the dialkylcyanamide-
platinum(II) complexes trans-[PtCl2(NCNR2)2], we assumed
that the conventional complexed organonitriles react with
the symmetric tautomer of DPG (Scheme 3, routes E-G),
while the push-pull nitrile ligands preferably react with the
asymmetric tautomer of DPG (Scheme 3, routes H-J).
Presumably, compounds 4-9 are generated via the previ-
ously unreported nucleophilic attack of the asymmetric
tautomer38 to the push-pull nitrile at the PtII center.
Characterization of the (1,3,5-Triazapentadiene)plati-
num(II) Complexes. The C, H, and N elemental analysis
data for 4-9 favor the presence of one (4-6) or two (7-9)
Cl- counterions, and their availability was also confirmed
by the reaction with Ag+ that give the solid AgCl. In ESI+-
MS, both the observed fragmentation and the isotopic pattern
of the complexes correspond to those expected for 4+-6+
and 72+-92+. Comparison of the IR spectra of 4-9 with
those of the starting dialkylcyanamide complexes indicates
the presence of the Ct N stretching vibrations (at ca. 2290
cm-1) but with a significant lesser intensity for 4-6 and the
absence of ν(Ct N) bands for 7-9. The IR spectra of 4-9
exhibit, in contrast to the starting materials trans-[PtCl2-
(NCNR2)2], strong ν(CdN) vibrations in the range of
1650-1629 cm-1 and N-H stretching vibrations, which
emerge between 3375 and 3150 cm-1.
Figure 2. Thermal ellipsoid view of 2 with an atomic numbering scheme.
Thermal ellipsoids are drawn with 50% probability. Selected bond lengths
(Å) and angles (deg): N1-C1 1.300(10), N2-C14 1.318(10), N5-C13
1.249(11), N4-C1 1.383(10), N7-C14 1.378(10), N4-C13 1.395(11),
N7-C13 1.403(11); N2-Pt1-N1 94.4(3).
Table 1. Selected Bond Lengths (Å) and Angles (deg) for 1 and 2
1
2
Pt1-N1
2.027(2)
2.027(2)
2.2962(8)
2.3018(8)
1.293(4)
1.295(4)
1.395(4)
1.418(4)
1.256(4)
1.392(4)
93.93(10)
91.48(3)
2.004(7)
1.970(7)
2.304(2)
2.302(2)
1.300(10)
1.318(10)
1.383(10)
1.395(11)
1.249(11)
1.378(10)
94.4(3)
Pt1-N2
Pt1-Cl1
Pt1-Cl2
N1-C1
N2-C14
N4-C1
N4-C13
N5-C13
N7-C14
N1-Pt1-N2
Cl1-Pt1-Cl2
92.32(8)
central guanidine group is not coordinated. Both 1 and 2
crystallize as a racemate, which consists of the two optical
isomers (∆- and Λ-twist-boat; Figure S1 in the Supporting
Information), probably due to the conformational flexibility
of the eight-membered cycles. For a detailed description of
the X-ray structural data and also for the packing diagrams
of the chloroform solvates (Figures S2-S6 and Table S1 in
the Supporting Information).
Dialkylcyanamide-Guanidine Coupling at trans-(R2-
NCN)2PtII Centers. Earlier we reported11 on the reaction
between the PtII-bound conventional nitriles in the complexes
trans-[PtCl2(RCN)2] (R ) Et, CH2Ph, Ph) and DPG. When
this interplay proceeds in a molar ratio of 1:2, it furnishes
the monochelates [PtCl{NHdC(R)NC(NHPh)dNPh}(RCN)]
(Scheme 3, route E) but with 4 equiv of DPG (Scheme 3,
route G) [or the reaction of [PtCl{NHdC(R)NC(NHPh)d
NPh}(RCN)] with 2 equiv of DPG (Scheme 3, route F)],
and the complexes containing two bidentate 1,3,5-triazap-
entadiene ligands, i.e., [Pt{NHdC(R)NC(NHPh)dNPh}2],
are formed.
In the 1H NMR spectra recorded at ambient temperature,
a noticeable broadening and/or some sets of signals of alkyl
protons of the NR2 amide groups of 4-9 has been observed.
Thus, 1H NMR data of 4-9 give collateral evidence favoring
inversion at the N atom of NR2 groups and/or a restricted
rotation of the amide groups NR2 (located close to the Ph
rings) around the C-NR2 bond, suggesting a significant
contribution of the form with CdNR2 double-bond character.
The relevant formamidinium ions, [H(R1)NCHdNR2(R3)]+,42
We now extended the coupling between DPG and the
conventional nitriles at PtII centers to PtII complexes bearing
the push-pull nitriles. Thus, the treatment of trans-
[PtCl2(NCNR2)2] (R ) Me; R2 ) C5H10, C4H8O) with 1 equiv
of DPG (Scheme 3, route H) in a solution (R ) R ) Me; R2
) C5H10) or in a suspension (R2 ) C4H8O) of CHCl3 (or
MeNO2) at 20-25 °C for 20 h results in the generation of
(39) Tomas, A.; Morgant, G.; Nguyen-Huy, D.; Lemoine, P.; Viossat, B.
Z. Kristallogr.-New Cryst. Struct. 2002, 217, 131.
(40) Tanatani, A.; Yamaguchi, K.; Azumaya, I.; Fukutomi, R.; Shudo, K.;
Kagechika, H. J. Am. Chem. Soc. 1998, 120, 6433.
(41) Newkome, G. R.; Gupta, V. K.; Fronczek, F. R. Acta Crystallogr. C
1986, 42, 1643.
(42) Ha¨felinger, G. In The Chemistry of Amidines and Imidates; Patai, S.,
Ed.; John Wiley: London, 1975; Chapter 1.
Inorganic Chemistry, Vol. 48, No. 6, 2009 2587

Gushchin et al.
Scheme 3
a derivative of the five-membered S3N2 ring (C6H11)2NC(Cl)-
nitrile-imine (guanidine) coupling,45 leading to multimetallic
systems derived from the ligand reactions. Work focusing
on the latter topic is underway in our group.
43
+
NS3N2 Cl-, amidoazavinylidene (or amidomethyleneam-
ide) species ModNdCH(NR2)7 and compound Mo2-
(OCH2CMe3)6(µ-η1,η2-NCNMe2)44 also exhibit an encum-
bered rotation around the CdN bond.
Experimental Section
1
In the H NMR spectra, 4-6 exhibit two signals of the
Materials and Instrumentation. The guanidine HNdC(NHPh)2
(Aldrich) and solvents were obtained from commercial sources and
used as received. The complex cis-[PtCl2(NCNC4H8O)2] was
synthesized upon heating of the clathrate Pt6Cl12 · 0.1C2H5Cl ·
5.7H2O46 with NCNC4H8O (Aldrich) (see the Experimental Sec-
tion), and the obtained compound contains an admixture of the trans
isomer (an isomeric cis:trans ratio obtained by 1H NMR integration
is ca. 2.7:1.0). The complexes trans-[PtCl2(NCNR2)2] (R ) Me;
R2 ) C5H10, C4H8O) and cis-[PtCl2(NCNR2)2] (R ) Me; R2 )
C5H10) were prepared in accordance with the published methods.6
Elemental analyses were obtained on a 185B Carbon Hydrogen
Nitrogen Analyzer Hewlett-Packard instrument. Differential thermal
analysis/thermogravimetry (DTA/TG) measurements were per-
formed using a Perkin-Elmer (Diamond TG/DTA) derivatograph
in air at a heating rate of 10 °C/min (carrier gas: air, 200 mL/min).
Time-of-flight (TOF)-ESI-MS spectra were obtained on a MX-5310
mass spectrometer. IR spectra (4000-400 cm-1) were recorded on
a Shimadzu FTIR 8400S instrument in KBr pellets. 1H and 13C{1H}
NMR spectra were measured on a Bruker-DPX 300 spectrometer
at ambient temperature.
Computational Details. The full geometry optimization of all
structures has been carried out in Cartesian coordinates with the
help of the Gaussian-9847 program package at the density functional
theory level. The calculations have been performed using Becke’s
three-parameter hybrid exchange functional48 in combination with
the gradient-corrected correlation functional of Lee, Yang, and
Parr49 (B3LYP). A quasi-relativistic Stuttgart pseudopotential
described 60 core electrons, and the appropriate contracted basis
set (8s7p6d)/[6s5p3d]50 for the Pt atom and the 6-31G* basis set
for other atoms were used. The combination of the B3LYP
functional and the basis set mentioned was found as a quite
reasonable approximation for the investigation of properties of
transition-metal complexes,51-53 including nitrile complexes of
NH protons, i.e., the broad signal at ca. 10.28 ppm and the
singlet in the range 5.67-5.84 ppm. The 13C NMR spectra
of 4-9 display resonances from two different carbons (ca.
158 and 155 ppm) of two different CdN bonds. The pro-
posed structures of 7 and 8 were also confirmed by X-ray
diffraction. However, these data will be reported separately.45
Final Remarks. The results from this work can be
summarized into three perspectives. First, the reaction
between two cis-ligated R2NCN species and DPG represents
a novel reactivity mode, which has never been reported for
any nitrile at any metal center. Second, the formation of
eight-membered rings described in this Article appears to
be specific for the push-pull nitriles R2NCN, and this
reaction was not observed for the conventional alkyl- and
arylnitriles R′CN. The performed quantum-chemical calcula-
tions allowed the interpretation of the different behaviors of
the conventional nitrile and dialkylcyanamide complexes in
their reactions with DPG, indicating that the eight-membered
product is significantly less stable in the case of the
alkylnitrile derivatives cis-(RCN)2PtII in comparison with the
cyanamide species cis-(R2NCN)2PtII. Third, the obtained
eight-membered chelates represent a novel type of guanidines,
which comprise one integrated system with the metal center.
These platinaguanidines bear the free dNH moiety that can
serve as a nucleophilic center in the metal-mediated
(43) Chivers, T.; Richardson, J. F.; Smith, N. R. M. Inorg. Chem. 1986,
25, 47.
(44) Chisholm, M. H.; Huffman, J. C.; Marchant, N. S. Organometallics
1987, 6, 1073.
(45) Gushchin, P. V.; Haukka, M.; Kukushkin, V. Yu., unpublished
data.
2588 Inorganic Chemistry, Vol. 48, No. 6, 2009

Metal-ActiWated Dialkylcyanamide Species
platinum,51 taking into account the low computational cost of this
method and the fact that the results obtained at B3LYP agree well
with those calculated at the higher correlated methods.
Table 2. Crystal Data
1
2
empirical formula
fw
temp (K)
λ (Å)
cryst syst
space group
a (Å)
b (Å)
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
C20H26Cl5N7Pt
722.81
C26H34Cl5N7Pt
816.94
120(2)
0.710 73
orthorhombic
Pbca
9.8934(7)
24.2416(13)
24.9307(18)
90
The Hessian matrix was calculated analytically for all optimized
structures in order to prove the location of correct minima (no
“imaginary” frequencies) and to estimate the zero-point-energy
(ZPE) correction and thermodynamic parameters, the latter of which
were calculated at 25 °C. Solvent effects were taken into account
at the single-point calculations based on the gas-phase equilibrium
geometries by using the polarizable continuum model (PCM)54 in
the CPCM version55 with CHCl3 as a solvent. For T2a, the
dispersion-repulsion term could not be calculated with CPCM and
other PCM-based models. Hence, the nonelectrostatic component
for this structure was estimated as ∆GNon-EL(T2a) ) ∆Gnon-EL(T2b)
+ ∆Gnon-EL(T3a) - ∆Gnon-EL(T3b), where ∆Gnon-EL are nonelec-
trostatic contributions in the solvent effects for T2a, T2b, T3a,
and T3b species. The enthalpies and Gibbs free energies in solution
(Hs and Gs) were estimated by the addition of the ZPE, thermal
(δHg), and also entropic (δGg) contributions taken from the gas-
phase calculations to the single-point CPCM-self-consistent-field
(SCF) energy (Es).
120(2)
0.710 73
triclinic
j
P1
8.7607(2)
11.4006(3)
13.6067(3)
109.475(1)
93.761(1)
104.921(1)
1220.82(5)
2
90
90
5979.2(7)
8
Z
F
calc (Mg/m3)
1.966
6.316
5616
5616
1.815
5.171
36566
6000
µ(Mo KR) (mm-1
)
no. of reflns
no. of unique reflns
Rint
0.0750
0.0245
0.0577
0.1120
0.0467
0.0887
2
R1a (I g 2σ)
wR2b (I g 2σ)
a R1 ) ∑||Fo| - |Fc|/∑|Fo|. wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo )2]]1/2
.
b
2
The starting geometries of eight- and six-membered reaction
products were based on the experimental X-ray structures of 1 and
2 (this work) and [PtCl4{NHdC(NH2)NHC(NMe2)dNH}].39 For
DPG, the most stable tautomeric form in the E,Z conformation,
i.e., PhNdC(NH2)N(H)Ph,40 was considered. The equilibrium
geometries and the main calculated bond lengths are in reasonable
agreement with the X-ray data obtained for trans-[PtCl2(NCN-
Me2)2],6 cis-[PtCl2(NCMe)2],41 1, and 2 (this work) and [PtCl4-
{NHdC(NH2)NHC(NMe2)dNH}]39 (Table S2 and Figure S7 in
the Supporting Information). The maximum deviations of the
theoretical and experimental parameters are 0.07 and 0.05 Å for
the Pt-N and Pt-Cl bonds, respectively, whereas the difference
a temperature of 120 K. The X-ray diffraction data were collected
by means of a Nonius Kappa CCD diffractometer using Mo KR
radiation (λ ) 0.710 73 Å). The Denzo-Scalepack56 or EValCCD57
program packages were used for cell refinements and data reduc-
tions. The structures were solved by direct methods using SIR200458
or SHELXS-9759 with the WinGX60 graphical user interface. A
semiempirical absorption correction (SORTAV61 or SADABS62) was
applied to all data. Structural refinements were carried out using
SHELXL-97.63 In 1, the CHCl3 solvent molecule was severely
disordered and therefore the final structural model was refined
without it. The contribution of the disordered solvent to the
calculated structure factors was taken into account by using the
SQUEEZE routine of the PLATON64 program. In 1, the NH
hydrogen atom H5 was located from the difference Fourier map
but constrained to ride on its parent atom. In 2, all NH hydrogen
atoms were also located from the difference Fourier map and
constrained on their parent atom, with Uiso ) 1.5Ueq (parent atom).
Other hydrogen atoms were positioned geometrically and were
constrained to ride on their parent atoms, with N-H ) 0.88 Å,
C-H ) 0.95-0.99 Å, and Uiso ) 1.2-1.5Ueq (parent atom). The
crystallographic details are summarized in Table 2 and selected
bond lengths and angles in Table 1.
˚
for the other bonds does not exceed 0.037A, often falling within
the 3σ interval of the X-ray data.
X-ray Structure Determinations. The crystals of 1 and 2 were
immersed in cryo-oil, mounted in a Nylon loop, and measured at
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Stratmann, R. E.; Burant, J. C.; Dapprich, S.; Millam, J. M.; Daniels,
A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J.; Barone,
V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.;
Clifford, S.; Ochterski, J.; Peterson, G. A.; Ayala, P. Y.; Cui, Q.;
Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;
Foresman, J. B.; Cioslowski, J.; Ortiz, J. V.; Baboul, A. G.; Stefanov,
B. B.; Liu, G.; Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts,
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Inorganic Chemistry, Vol. 48, No. 6, 2009 2589

Gushchin et al.
mmol) were dissolved in MeNO2 (1.0 mL), whereupon a yellow
precipitate immediately began to release. The suspension formed
was left to stand at 20-25 °C for 24 h without stirring, the
precipitate was filtered off, washed with one 0.5-mL portion of
MeNO2 and one 1.0-mL portion of Et2O, and dried in air at 20-25
°C. Yields were as follows: 56 mg, 75% (1); 59 mg, 70% (2); 59
mg, 70% (3).
Crystals of 2·CHCl3 suitable for an X-ray diffraction study were
obtained by slow evaporation of a benzene:chloroform (1:8, v/v)
solution at 20-25 °C.
3·1½CHCl3. Anal. Calcd for C23H29N7Cl2PtO2 ·1½CHCl3: C,
33.42; H, 3.49; N, 11.13. Found: C, 33.61; H, 4.01; N, 11.70. ESI+-
MS: m/z 1403 [2M]+, 702 [M]+. TLC: Rf ) 0.62 (eluent Me2CO:
CHCl3 ) 2:1). DTA/TG: 204 °C (gradual decomposition). IR (KBr,
selected bands, cm-1): 3356 (m), 3269 (m), 3244 (m), ν(N-H);
3050 (w), ν(C-H from Ar); 2969 (m-w), 2913 (m-w), 2856 (m-
w), ν(C-H from NC4H8O); 1619 (s), ν(CdN and CdC from Ar);
750 (m), 700 (m), δ(C-H from Ar). 1H NMR (CDCl3, δ): 7.76 (d,
br, 1H), 7.55 (t, 4H), 7.43 (t, 3H), 7.32 (t, 2H) (Ph’s), 7.15 (br,
1H), 6.16 (s, 1H) (NH), 3.95 (br, 1H), 3.70 (br, 1H), 3.35 (br, 9H),
3.01 (br, 1H), 2.63 (br), 2.48 (br), 2.40 (br), 2.31 (br, 4H) (16H,
NC4H8O). Poor solubility of this compound in all common
deuterated solvents and rapid solvolysis in DMSO-d6, where the
complex is soluble, precluded 13C{1H} NMR measurements.
Reaction of trans-[PtCl2(NCNR2)2] and 1 equiv of DPG. trans-
[PtCl2(NCNR2)2] (R ) Me; R2 ) C5H10, C4H8O) (0.07 mmol) and
HNdC(NHPh)2 (16 mg, 0.08 mmol) were dissolved (R ) Me; R2
) C5H10) or suspended (R2 ) C4H8O) in CHCl3 (1.0 mL) to give
a bright-yellow solution or a suspension and left to stand at 20-25
°C for 20 h without stirring (R ) Me; R2 ) C5H10) or with stirring
(R2 ) C4H8O), respectively, to form in each case a pale-yellow
solution, which was evaporated until dryness, and the yellow solid
residue formed was washed with one 4.5-mL portion of a Me2CO:
Et2O ) 1:2 mixture (R ) Me) or one 1.0-mL portion of Me2CO
(R2 ) C5H10), followed by centrifugation and decantation of
washing waters. After that, the formed pale-yellow (R ) Me) or
colorless powder (R2 ) C5H10) was washed with one 2.0-mL portion
of a Me2CO:Et2O ) 1:1 mixture (R ) Me) or one 1.0-mL portion
of Me2CO (R2 ) C5H10) and one 1.5-mL portion of Et2O (R )
Me), followed by centrifugation and decantation of washing waters,
and dried in air at 20-25 °C (R ) Me; R2 ) C5H10). In the case
of R2 ) NC4H8O, the colorless precipitate was centrifugated,
washed with one 0.5-mL portion of Me2CO and one 0.5-mL portion
of Et2O, followed by centrifugation and decantation of washing
waters, and dried in air at 20-25 °C. The yield was 5 mg (bischelate
9). Then, the washing waters and the filtrates were combined and kept
in air for evaporation of the solvent until dryness, and the pale-yellow
solid residue formed was washed with one 1.0-mL portion of Me2CO,
followed by centrifugation and decantation of washing waters. After
that, the pale-yellow powder formed was washed with one 0.2-mL
portion of Me2CO and one 0.2-mL portion of Et2O, followed by
centrifugation and decantation of washing waters, and dried in air at
20-25 °C. The washing waters and the filtrates were combined, and
one 5.0-mL portion of Et2O was added to the pale-yellow solution
formed. The released pale-yellow precipitate was centrifugated, washed
with one 2.0-mL portion of a Me2CO:Et2O ) 1:1 mixture and one
2.0-mL portion of Et2O, followed by centrifugation and decantation
of washing waters, and dried in air at 20-25 °C and combined with
the first fraction. Yields were as follows: 22 mg, 50% (4); 20 mg,
41% (5); 28 mg, 58% (6).
Reaction of cis-[PtCl2(NCNR2)2] and 1 equiv of DPG in
CHCl3. cis-[PtCl2(NCNR2)2] (R ) Me; R2 ) C5H10, C4H8O) (0.10
mmol) and HNdC(NHPh)2 (21.3 mg, 0.10 mmol) were dissolved
in CHCl3 (1.0 mL) and left to stand at 20-25 °C for 21 h. The
reaction mixture was evaporated to dryness at 20-25 °C (R ) Me;
R2 ) C5H10, C4H8O), and the greenish-beige solid residue formed
was recrystallized under a layer of one 1.5-mL portion of EtOH
(R2 ) C5H10, C4H8O), followed by centrifugation and decantation
of the solution. After that, the formed pale-yellow powder (R2 )
C5H10, C4H8O) was washed with one 1.5-mL portion (R2 ) C5H10)
or two 1.5-mL portions (R2 ) C4H8O) of EtOH and one 1.5-mL
portion of Et2O (R2 ) C5H10, C4H8O), followed by centrifugation
and decantation of washing waters, and then dried in air at 20-25
°C. In the case of R ) Me, the major product was isolated in
analytically pure form from the reaction mixture by column
chromatography on SiO2 (silica gel 60 F254, 0.063-0.200 mm,
Merck; eluent Me2CO:CHCl3 ) 1:1, Rf ) 0.31, second fraction).
Yields were as follows: 31 mg, 53% after column chromatography
(R ) Me, 1); 42 mg, 61% (R2 ) C5H10, 2); 45 mg, 67% (R2 )
C4H8O, 3).
1·1/2CHCl3. Anal. Calcd for C19H25N7Cl2Pt·1/2CHCl3: C, 34.59;
H, 3.80; N, 14.48. Found: C, 34.62; H, 4.37; N, 13.91. ESI+-MS:
m/z 1235 [2M]+, 1198 [2M - HCl]+, 635 [M + H2O]+, 618 [M +
H]+. TLC: Rf ) 0.31 (eluent Me2CO:CHCl3 ) 1:1). DTA/TG: 214
°C (gradual decomposition). IR (KBr, selected bands, cm-1): 3364
(m), 3277 (m, br), ν(N-H); 3043 (m-w), ν(C-H from Ar); 2936
(m-w), 2880 (m-w), 2814 (w), ν(C-H from NMe2); 1622 (vs),
ν(CdN and CdC from Ar); 746 (m-s), 711 (m-s), 690 (m), δ(C-H
from Ar). 1H NMR (CDCl3, δ): 7.55 (d, 2H), 7.47 (t, 4H), 7.41 (d,
2H), 7.33 (t, 1H), 7.21 (t, 1H) (Ph’s), 6.97 (s, 1H), 5.96 (s, 1H)
(NH), 3.11 (br), 2.76 (br), 2.69 (br), 1.74 (br, 12H) (NMe2). 13C{1H}
NMR (CDCl3, δ): 159.96, 157.84, 155.44 (CdN), 139.42, 138.89
(Cipso), 130.86, 129.03, 127.85, 126.65, 125.96, 124.32 (carbons in
Ph), 39.38-38.21 (group of overlapping signals) (carbons in NMe2).
Crystals of 1·CHCl3 suitable for an X-ray diffraction study were
obtained by slow evaporation of a chlorobenzene/chloroform (1:8,
v/v) solution at 20-25 °C.
2. Anal. Calcd for C25H33N7Cl2Pt: C, 43.05; H, 4.77; N, 14.06.
Found: C, 43.57; H, 5.11; N, 13.87. ESI+-MS: m/z 738 [M + K +
2H]+, 720 [M + Na]+, 661.5 [M - Cl]+. FAB+-MS: m/z 1395
[2M + H]+, 1359 [2M - HCl]+, 1286 [2M - Cl - 2HCl ]+, 1249
[2M + H - 4HCl]+, 697 [M]+, 662 [M - Cl]+, 624 [M - 2HCl]+.
TLC: Rf ) 0.52 (eluent MeOH:CHCl3 ) 1:20). DTA/TG: 175 °C
(gradual decomposition). IR (KBr, selected bands, cm-1): 3477 (m,
br), 3360 (m-s), 3254 (m-s, br), ν(N-H); 3056 (m), ν(C-H from
Ar); 2938 (m-s), 2855 (m-s), ν(C-H from NC5H10); 1619 (s, br),
ν(CdN and CdC from Ar); 751 (m-s), 701 (m-s), δ(C-H from
Ar). 1H NMR (CDCl3, δ): 7.61 (d, 1H), 7.48 (t, 4H), 7.41 (d, 3H),
7.34 (t, 1H), 7.24 (t, 1H) (Ph’s), 6.98 (s, 1H), 6.00 (s, 1H) (NH),
3.80 (br), 3.40 (br), 3.16 (br), 3.04 (br), 2.39 (br), 1.58 (br), 1.49
(br), 1.36 (br), 1.20 (br), 1.08 (br), 0.53 (br), 0.43 (br), 0.10 (br,
20H) (NC5H10). 13C{1H} NMR (CDCl3, δ): 160.43, 158.25, 155.83
(CdN), 140.14, 139.75 (Cipso), 130.80, 129.15, 128.21, 127.70,
126.94, 124.50 (carbons in Ph), 48.75 (br), 47.98 (br) (R-CH2),
24.86 (br) (ꢀ-CH2), 24.18, 23.68 (γ-CH2) (carbons in NC5H10).
4·1/3CHCl3. Anal. Calcd for C19H25N7Cl2Pt·1/3CHCl3: C, 35.33;
H, 3.89; N, 14.92. Found: C, 35.12; H, 4.57; N, 14.72. ESI+-MS:
m/z 1199 [2M - Cl]+, 1162 [2M - 2HCl]+, 1128 [2M - 3Cl]+,
582 [M - Cl]+. DTA/TG: 141 °C (gradual decomposition). IR
(KBr, selected bands, cm-1): 3375 (m), ν(N-H); 3150 (m), ν(N-H
and/or C-H from Ar); 3094 (m), 3050 (m), ν(C-H from Ar); 2963
(m), 2925 (m), 2813 (m-w), ν(C-H from NMe2); 2295 (s), ν(Ct N);
1646 (vs), 1594 (s), ν(CdN and/or CdC from Ar); 756 (m), 694
(m), δ(C-H from Ar). 1H NMR (CDCl3, δ): 10.28 (br,
H2N-CN(Ph)), 8.30 (d, 2H), 7.50 (t, 2H), 7.41 (t, 3H), 7.27 (t,
2590 Inorganic Chemistry, Vol. 48, No. 6, 2009

Metal-ActiWated Dialkylcyanamide Species
1H), 7.17 (d, 1H) (Ph’s), 5.67 (s, PtsNHdC), 3.04 (s, 6H), 3.01
(s, 0.5H), 2.98 (s, 0.5H), 2.58 (s, 5H) (NMe2). 13C{1H} NMR
(CDCl3, δ): 157.50, 154.73 (CdN), 144.67, 140.72 (Cipso), 130.07,
129.81, 128.88, 127.81, 127.21, 125.92 (carbons in Ph), 39.90
(HNdCNMe2), 39.51 (Nt CNMe2) (carbons in NMe2).
in air at 20-25 °C. Slow evaporation of the reaction mixture (R2
) C4H8O) for 48 h at 20-25 °C gave colorless crystals. The
colorless crystals formed were separated from the pale-yellow oily
residue by washing with one 0.5-mL portion of CHCl3, followed
by decantation, washing with two 0.25-mL portions of CHCl3, and
drying in air at 20-25 °C. Yields were as follows: 12 mg, 17%
(7); 29 mg, 36% (8); 12 mg, 14% (9).
Reaction of trans-[PtCl2(NCNR2)2] and 2 equiv of DPG in
MeNO2. trans-[PtCl2(NCNR2)2] (R ) Me; R2 ) C5H10, C4H8O)
(0.08 mmol) and HNdC(NHPh)2 (0.037 mg, 0.17 mmol) were
dissolved in MeNO2 (1 mL) and left to stand at 20-25 °C for 48 h.
The colorless precipitate that was formed was separated by filtration,
washed with one 1.0-mL portion of MeNO2 (R ) Me; R2 ) C5H10,
C4H8O), two 1.0-mL portions of CHCl3 (R2 ) C5H10), and one
1.0-mL portion of Et2O (R ) Me; R2 ) C5H10, C4H8O), and dried
in air at 20-25 °C. Yields were as follows: 13 mg, 19% (7); 23
mg, 32% (8); 15 mg, 20% (9).
The washing waters and filtrates were combined and kept in air
for evaporation of the solvent until dryness. The pale-yellow solid
residue formed was dissolved in one 1.0-mL portion of Me2CO,
whereupon one 5.0-mL portion of Et2O was added to the pale-
yellow solution. The released pale-yellow precipitate was centrifu-
gated, washed with one 2.0-mL portion of a Me2CO:Et2O ) 1:1
mixture and one 2.0-mL portion of Et2O, followed by centrifugation
and decantation of washing waters, and dried in air. The yield was
1
9 mg, 20%. The H NMR spectrum for this portion is reported
below and indicates that it contains at least two compounds
including complex 4.
1H NMR (CDCl3, δ): 11.33 (br), 10.45 (br) (H2NCN(Ph)), 8.34
(d, 1H), 7.89 (br, 2H, NH), 7.53 (t, 1H), 7.45-7.37 (m, 4H),
7.32-7.24 (m, 2H), 7.17 (t, 2H) (Ph’s), 5.90 (s), 5.62 (s)
(PtsNHdC), 3.07 (s, 3H), 3.04 (s, 3H), 3.01 (s, 3H), 2.60 (s, 3H)
7·3/4CHCl3. Anal. Calcd for C32H38N10Cl2Pt·3/4CHCl3: C, 42.84;
H, 4.25; N, 15.25. Found: C, 42.81; H, 4.97; N, 15.48. ESI+-MS:
m/z 757 [M - Cl - HCl]+. DTA/TG: 201 °C (dec). IR (KBr,
selected bands, cm-1): 3421 (m-s), 3265 (m-s), 3107 (m-s),
ν(N-H); 1632 (vs), 1585 (s), ν(CdN and CdC from Ar); 752 (m),
1
(NMe2, the ratio of compounds obtained by H NMR integration
of signals corresponding to NMe protons is ca. 1:1). Assignment
1
1
of the signals will be done by application of H-13C HETCOR
698 (m), δ(C-H from Ar). H NMR (CD3OD, δ): 7.61 (t, 4H),
and 1D NOE NMR experiments.
4.54-7.44 (m, 6H), 7.38 (t, 2H), 7.32 (d, 4H), 7.27 (d, 4H) (Ph’s),
2.98 (s, 1H), 2.61 (s, 11H) (NMe2). 13C{1H} NMR (CD3OD, δ):
157.89, 156.12 (CdN), 145.58, 141.59 (Cipso), 131.35, 131.10,
130.31, 126.94, 123.98, 122.84 (Ph carbons), 38.98 (NMe2).
In the case when the reaction is performed in MeNO2, the
washing waters and the filtrates were combined and kept in air at
20-25 °C for slow evaporation of the solvent until dryness. The
yellow oily residue formed was dissolved in MeNO2 (0.25 mL),
whereupon Et2O (2 mL) was added to the yellow solution formed.
The released pale-yellow precipitate was centrifugated, washed with
one 3.50-mL portion of a MeNO2:Et2O ) 1.0:6.0 mixture and one
1.0-mL portion of Et2O, followed by centrifugation and decantation
of washing waters, and dried in air at 20-25 °C. The yield was 36
mg, 55%. The 1H NMR spectrum for this portion is reported below,
and it indicates that the mixture contains, besides 7, at least two
more compounds.
5. Anal. Calcd for C25H33N7Cl2Pt: C, 43.05; H, 4.77; N, 14.06.
Found: C, 43.45; H, 5.03; N, 14.29. ESI+-MS: m/z 662 [M - Cl]+.
TG curve: mass loss is 11.8% at 131 °C (calcd mass loss for
-HNC5H10 is 12.2%). IR (KBr, selected bands, cm-1): 2937 (m-s),
2856 (m), ν(C-H from NC5H10); 2285 (s), 2208 (m-w), ν(Ct N); 1639
(vs, br), ν(CdN and CdC from Ar); 748 (m), 697 (m), δ(C-H from
Ar). 1H NMR (CDCl3, δ): 10.27 (s, br, H2N-CN(Ph)), 8.35 (d, 2H),
7.53 (t, 2H), 7.46-7.42 (t + t, 3H), 7.28 (t, 1H), 7.21 (d, 2H) (Ph’s),
5.71 (s, PtsNHdC), 3.50 (br), 3.39-3.36 (m), 2.86 (s, 4H), 1.93 (s,
3H), 1.68 (br, m), 1.60 (br, m), 1.43 (br), 1.20 (br) (NCNC5H10).
13C{1H} NMR (CDCl3, δ): 157.89, 155.17 (CdN), 145.10, 141.99
(Cipso), 130.38, 130.13, 129.27, 128.15, 128.04, 126.41 (carbons in Ph),
49.66 (R-CH2), 25.15 (ꢀ-CH2 in HNdCNC5H10), 24.76 (ꢀ-CH2 in
Nt CNC5H10), 24.00 (γ-CH2 in HNdCNC5H10), 22.69 (γ-CH2 in
Nt CNC5H10) (carbons in NC5H10).
6·11/4CHCl3. Anal. Calcd for C23H29N7Cl2PtO2 ·11/4CHCl3: C,
34.24; H, 3.58; N, 11.53. Found: C, 34.83; H, 3.94; N, 11.71. ESI+-
MS: m/z 666 [M - Cl]+. DTA/TG: 150 °C (gradual decomposition).
IR (KBr, selected bands, cm-1): 3050 (m-w), ν(C-H from Ar);
2963 (m-w), 2919 (m-w), 2906 (m-w), 2850 (m-w), ν(C-H from
NC4H8O); 2288 (m-w), ν(Ct N); 1638 (s), 1594 (s), 1563 (s),
ν(CdN and/or CdC from Ar); 756 (m), 700 (m), δ(C-H from
Ar). 1H NMR (CDCl3, δ): 8.30 (d, 1H), 7.56 (t, 2H), 7.49-7.43 (t
+ t or t + d, 4H), 7.38-7.24 (m, 3H) (Ph’s), 5.84 (s, br,
PtsNHdC), 3.79 (t, 1H), 3.75 (t, 1H), 3.69 (t, 2H), 3.58 (t, 4H),
3.49 (t, 1H), 3.38 (t, 2H), 3.31(br, 2H), 3.25 (t, 1H), 2.95 (t, 2H)
(NCNC4H8O). 13C{1H} NMR (CDCl3, δ): 157.59, 154.54 (CdN),
144.58, 141.17 (Cipso), 130.28, 130.08, 129.93, 127.97, 127.27,
126.01 (carbons in Ph), 65.52, 65.26 (OCH2), 47.92, 47.64 (NCH2)
(carbons in NC4H8O).
Reaction of trans-[PtCl2(NCNR2)2] and 2 equiv of DPG in
CHCl3. trans-[PtCl2(NCNR2)2] (R ) Me; R2 ) C5H10, C4H8O) (0.09
mmol) and HNdC(NHPh)2 (0.040 mg, 0.19 mmol) were dissolved
in CHCl3 (1 mL) and left to stand at 20-25 °C for 20 h. The pale-
yellow solution was evaporated to dryness, and the pale-yellow
solid residue formed was washed with one 1.0-mL portion of
Me2CO (R ) Me; R2 ) C5H10) to form the colorless precipitate,
which was filtered off, washed with one 1.0-mL portion of Me2CO
and one 1.0-mL portion of Et2O (R ) Me, R2 ) C5H10), and dried
1H NMR (CD3OD, δ): 7.79 (d, 1H), 7.72 (d, 1H), 7.62 (t, 2H),
7.55-7.45 (m, 9H), 7.41-7.27 (m, 7H) (Ph’s), 3.04 (s), 3.02 (s),
3.00 (s), 2.96 (s), 2.89 (s), 2.63 (s) (12H, NMe, the ratio of
compounds obtained by 1H NMR integration of signals correspond-
ing to NMe protons is ca. 1.5:1.0:3.0).
1
Slow evaporation of the reaction mixture (CHCl3) to /3 of the
starting volume for 1 day at 20-25 °C gave colorless crystals,
which were characterized by X-ray crystallography. These crystals
were separated from the pale-yellow solution by decantation,
washed with three 0.2-mL portions of CHCl3, and dried in air at
20-25 °C. The yield was 12 mg, 16%.
When the reaction was performed in CHCl3, the washing waters
and the filtrates were combined and kept in air at 20-25 °C for
slow evaporation of the solvent until dryness, the pale-yellow solid
residue formed was dissolved in Me2CO (2 mL), whereupon Et2O
(3 mL) was added to the pale-yellow solution formed. The released
colorless precipitate was centrifugated, washed with one 2-mL
portion of a Me2CO:Et2O ) 2:3 mixture, followed by centrifugation
and decantation of washing waters, and dried in air at 20-25 °C.
The yield was 30 mg, 40%. 1H and 13C{1H} NMR spectra for this
portion are reported below and indicate that it contains, besides 7,
at least two more compounds.
1H NMR (CD3OD, δ): 7.77 (d, 1H), 7.70 (d, 1H), 7.60 (t, 2H),
7.56-7.44 (m, 10H), 7.41 (d, 1H), 7.38-7.35 (m, 3H), 7.31 (d,
Inorganic Chemistry, Vol. 48, No. 6, 2009 2591

Gushchin et al.
2H), 7.26 (d, 1H) (Ph’s), 3.02 (s), 2.98 (s), 2.61 (s) (12H, NMe,
the ratio of compounds obtained by 1H NMR integration of signals
corresponding to NMe protons is ca. 2.0:1.0:2.0). 13C{1H} NMR
(CD3OD, δ): 159.26, 158.72, 158.61, 157.86, 157.23, 156.23
(CdN), 145.32, 142.76, 142.22, 142.17, 137.74, 137.52, 136.38
(Cipso), 131.77, 131.50, 131.34, 131.25, 131.20, 131.19, 131.12,
131.06, 129.57, 129.45, 129.16, 128.62, 128.27, 128.19, 127.78,
126.91, 126.77, 126.27, 125.82, 125.58, 124.89, 124.26, 123.75,
122.89 (carbons in Ph), 39.86, 39.56, 39.29 (NMe2).
Ph’s), 4.58 (s, br), 3.64 (t), 3.59 (br), 3.50 (t), 3.46-3.34 (m), 3.27
(t), 3.15 (br), 2.97 (br), 2.83 (br) (16H, NC4H8O). 13C{1H} NMR
(CD3OD, δ): 158.49, 158.27, 157.77, 156.93, 156.38, 156.15,
156.06 (CdN), 145.58, 145.55, 143.57, 143.10, 142.51, 142.50,
141.97, 138.36, 137.74, 136.44 (Cipso), 131.46, 131.33, 131.22,
131.20, 131.16, 131.14, 131.05, 130.36, 129.94, 129.17, 129.04,
128.58, 128.28, 127.95, 127.66, 127.04, 126.53, 126.24, 125.28,
124.81, 124.09, 123.54, 123.34 (carbons in Ph), 67.81, 67.55, 66.88,
66.74, 66.44, 66.34 (OCH2), 46.13, 45.27 (NCH2).
8·1/2CHCl3. Anal. Calcd for C38H46N10Cl2Pt ·1/2CHCl3: C, 47.69;
H, 4.94; N, 14.45. Found: C, 47.71; H, 5.55; N, 14.32. ESI+-MS:
m/z 837 [M - Cl - HCl]+. FAB+-MS: m/z 872 [M - HCl]+, 837
[M - Cl - HCl]+. DTA/TG: 168 °C (dec). IR (KBr, selected bands,
cm-1): 3625 (m-w), 3365 (m), ν(N-H); 3100 (m-s), 3059 (m-s),
ν(N-H and/or C-H from Ar); 2941 (m-s), 2859 (m), ν(C-H from
NC5H10); 1634 (s, br), ν(C)N and CdC from Ar); 748 (m), 697
(m), δ(C-H from Ar).1H NMR (DMSO-d6, δ): 8.96 (s, br) (NH),
7.58 (t, 4H), 7.49 (t, 4H), 7.40 (d, 4H), 7.35 (t, 4H), 7.29 (d, 4H)
(20H, Ph’s), 3.54 (br), 2.88 (br), 2.73 (br), 2.27 (br), 1.42 (br),
1.27 (br), 0.47 (br) (20H, NC5H10). 1H NMR (CD3OD, δ): 7.64 (t,
4H), 7.55 (t, 4H), 7.49-7.42 (t + t, 8H), 7.37 (d, 4H) (20H, Ph’s),
3.47 (br), 2.97 (br), 1.52 (br), 1.38 (br), 1.31 (s), 0.91 (br), 0.73
(br) (20H, NC5H10). 13C{1H} NMR (CD3OD, δ): 156.49, 155.27
(CdN), 144.68, 141.27 (Cipso), 130.39, 130.01, 128.14, 127.72,
125.98, 123.84 (carbons in Ph), 48.20 (R-CH2), 24.78 (ꢀ-CH2),
23.59 (γ-CH2) (carbons in NC5H10).
Synthesis of cis-[PtCl2(NCNC4H8O)2]. A synthetic experiment
was performed in accordance with the previously reported method
for the preparation of cis-[PtCl2(C6H5CH2CN)2].46 Thus, the clath-
rate Pt6Cl12 ·0.1C2H5Cl·5.7H2O (0.07 mmol) was placed into a 10-
mL flask thermostated at 100 °C, and 1 mL (9.9 mmol) of
NCNC4H8O also heated to 100 °C was added. The mixture was
kept at 100 °C for 2 min, whereupon the warm solution was filtered
off from some undissolved material. The greenish-yellow filtrate
was cooled to 20-25 °C and crystallized under a layer of Et2O
(15 mL) to form the solid beige powder, which was separated by
filtration, washed with three 3-mL portions of Et2O, and dried in
air at 20-25 °C. At 100 °C, the complex was released as a mixture
of cis and trans isomers in ca. 2.7:1.0 ratio (by 1H NMR integration).
The pure cis isomer was obtained from the cis/trans mixture by
column chromatography on SiO2 (silica gel 60 F254, 0.063-0.200
mm, Merck; eluent Me2CO:CHCl3 ) 1:1, Rf ) 0.47, second
fraction). The yield was 83 mg, 38%.
cis-[PtCl2(NCNC4H8O)2]·1/9NCNC4H8O·H2O. Anal. Calcd for
C10H16N4Cl2PtO2 ·1/9NCNC4H8O·H2O: C, 24.37; H, 3.66; N, 11.37.
Found: C, 24.33; H, 3.51; N, 11.12. ESI+-MS: m/z 508 [M +
H2O]+, 491 [M + H]+. TLC: Rf ) 0.47 (eluent Me2CO:CHCl3 )
1:1). IR (KBr, selected bands, cm-1): 2968 (m-w), 2927 (m-w),
2858 (m-w), ν(C-H from NC4H8O); 2295 (m-s), ν(Ct N). 1H NMR
(CDCl3, δ): 3.79 (t, 4H, J ) 4.89 Hz, OCH2), 3.47 (t, 4H, J )
4.89 Hz, NCH2). Poor solubility of this compound in all common
deuterated solvents and rapid solvolysis in DMSO-d6, where the
complex is soluble, precluded 13C{1H} NMR measurements.
1
Slow evaporation of the reaction mixture (CHCl3) to /3 of the
starting volume for 1 day at 20-25 °C gave colorless crystals; the
latter were characterized by X-ray crystallography. The colorless
crystals formed were separated from the pale-yellow solution by
decantation, washed with three 0.2-mL portions of CHCl3, and dried
in air at 20-25 °C. The yield was 29 mg, 35%.
9. Anal. Calcd for C36H42N10Cl2PtO2: C, 47.37; H, 4.64; N, 15.35.
Found: C, 46.71; H, 5.08; N, 15.95. ESI+-MS: m/z 876 [M - HCl]+,
840 [M - 2HCl]+, 764 [M - 2Cl - PhH]+. DTA/TG: 217 °C
(dec). IR (KBr, selected bands, cm-1): 3409 (m), 3068 (m), ν(N-H
and/or C-H from Ar); 2961 (m), 2926 (m), 2849 (m), ν(C-H from
NC4H8O); 1637 (vs), 1595 (s), ν(CdN and CdC from Ar); 751
(m-s), 695 (m-s), δ(C-H from Ar). 1H NMR (CD3OD, δ): 7.64 (t,
4H), 7.58 (t, 4H), 7.51-7.43 (m, 8H), 7.38 (d, 4H) (20H, Ph’s),
2.98 (br, 16H, NC4H8O). 13C{1H} NMR (CD3OD, δ): 156.78,
155.20 (CdN), 144.58, 140.98 (Cipso), 130.46, 130.23, 128.20,
128.03, 126.04, 123.69 (carbons in Ph), 65.35 (OCH2) 47.51 (NCH2)
(carbons in NC4H8O).
Acknowledgment. This work has been supported by the
Russian Fund for Basic Research (Grants 08-03-12027-ofi
and 08-03-00631-a), RAS Presidium Program coordinated
by acad. Nikolay T. Kuznetsov (Grant 8P) and also by
bilateral RFBR-NSF (Taiwan) Grant 07-03-92002. M.-J.W.
and V.Yu.K. express their gratitude to the National Taiwan
University of Science and Technology for the Cooperation
Grant NTUST-2007-R-01 and for a Visiting Chair Profes-
sorship provided for V.Yu.K. M.H. and V.Yu.K. thank the
Academy of Finland for financial support (Grant 121266).
We are very much obliged to Dr. S. I. Selivanov for running
the NMR spectra and valuable discusson of the NMR data.
When the reaction was performed in chloroform, slow evapora-
1
tion of the reaction mixture to /3 of the starting volume for 48 h
at 20-25 °C gave colorless crystals. These crystals were separated
from the pale-yellow oily residue by washing with one 0.5-mL
portion of CHCl3 with decantation and two 0.25-mL portions of
CHCl3 and drying in air at 20-25 °C. The yield was 12 mg, 14%.
Complex 9 crystallizes as a 9·2MeOH solvate from the reaction
mixture (CHCl3) upon the addition of MeOH (0.2 mL).
In the case when the reaction is performed in CHCl3, the washing
waters were evaporated to dryness, and the pale-yellow solid residue
formed was washed with one 1.0-mL portion of a Me2CO:Et2O )
1:1 mixture (R2 ) C4H8O) to form the colorless precipitate, which
was filtered off, washed with three 0.8-mL portions of a Me2CO:
Et2O ) 1:1 mixture (R2 ) C4H8O), and dried in air at 20-25 °C.
The yield was 46 mg, 56%. 1H and 13C{1H} NMR spectra for this
portion are reported below and indicate that it contains, besides 9,
at least two more compounds.
Supporting Information Available: Description of solution
dynamic processes for 1-3, detailed description of X-ray structures
of 1·CHCl3 and 2·CHCl3, Tables S2-S4 giving selected bond
lengths, total energies, enthalpies, and Gibbs free energies of the
calculated structures and reaction energies, Scheme S1 depicting
reactions considered theoretically, Figure S7 giving equilibrium
geometries of the calculated structures, and Figure S8 giving
calculated thermodynamic energy profiles. This material is available
free of charge via the Internet at http://pubs.acs.org.
1H NMR (CD3OD, δ): 7.92 (d), 7.83 (t), 7.63 (t), 7.59-7.53
(m), 7.51-7.44 (m), 7.41-7.33 (m), 7.27 (t), 7.21-7.11 (m) (20H,
IC802109D
2592 Inorganic Chemistry, Vol. 48, No. 6, 2009