Synthesis and characterization of a dinuclear platinum complex with silsesquioxanate ligand

Article abstract of DOI:10.1016/j.jorganchem.2010.03.033

The first dinuclear platinum complex with a silsesquioxanate ligand {[Pt(Ph)(PEt₃)₂]₂O₁₁Si ₇(c-C₅H₉)₇(OH)} was synthesized by reaction of incompletely condensed silsesquioxane, (c-C₅H ₉)₇Si₇O₉(OH)₃ with trans-PtI(Ph)(PEt₃)₂. Multinuclear (¹H, ¹³C, ²⁹Si, and ³¹P) NMR data clearly show two unequivalent platinum moieties (Pt(Ph)(PEt₃)₂) bridged by bulky silsesquioxanate ligand. DFT calculations were performed to analyse the molecular structure and NMR properties of the new platinum complex.

Full text of DOI:10.1016/j.jorganchem.2010.03.033

Journal of Organometallic Chemistry 695 (2010) 1738e1743
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Note
Synthesis and characterization of a dinuclear platinum complex with
silsesquioxanate ligand
,
b
b
c
c
Neli Mintcheva a , Makoto Tanabe , Kohtaro Osakada , Ivelina Georgieva , Tzvetan Mihailov ,
*
Natasha Trendafilova c
a Department of Chemistry, University of Mining and Geology “St. Ivan Rilski”, Students’ Town, Sofia 1700, Bulgaria
b Chemical Resources Laboratory, Tokyo Institute of Technology, 4259-R1-3 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan
c Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, Acad. G. Bonchev str., bl. 11, Sofia 1113, Bulgaria
a r t i c l e i n f o
a b s t r a c t
Article history:
The first dinuclear platinum complex with a silsesquioxanate ligand {[Pt(Ph)(PEt3)2]2O11Si7(c-C5H9)7(OH)}
was synthesized by reaction of incompletely condensed silsesquioxane, (c-C5H9)7Si7O9(OH)3 with trans-PtI
(Ph)(PEt3)2. Multinuclear (1H,13C, 29Si, and 31P) NMR data clearly show two unequivalent platinum moieties
(Pt(Ph)(PEt3)2) bridged by bulky silsesquioxanate ligand. DFT calculations were performed to analyse the
molecular structure and NMR properties of the new platinum complex.
Received 25 January 2010
Received in revised form
7 March 2010
Accepted 21 March 2010
Available online 24 April 2010
Ó 2010 Elsevier B.V. All rights reserved.
Keywords:
Dinuclear platinum complex
Silsesquioxane
Metallasilsesquioxane
DFT calculation
1. Introduction
(L)2] (M ¼ Pt, Pd, Ar ¼ C6H5, C6F5, L ¼ PMe3, PEt3, PMe2Ph) were
obtained and fully characterised [7,8]. Crystallographic results
Metallasilsesquioxanes are structurally well-defined soluble
compounds derived from numerous metal ions (early and late
transition metals [1], lanthanides [2], earth-alkaline metals [3]) and
incompletely condensed silsesquioxanes that mimic the surface of
metal supported silica widely used in heterogeneous catalysis [4].
Understanding of mechanisms in surface chemistry attracts the
attention of many scientists to investigate preparation, structure
and reactivity of metallasilsesquioxanes. On the other side, metal
complexes of silsesquioxanes show great structural diversity and
therefore exploring structure-properties correlation is of current
interest.
revealed that incompletely condensed silsesquioxane acts as
a monodentate O-coordinated ligand with two intramolecular
hydrogen bonds. The dynamic behavior in solution of the
compounds mentioned above and of arylpalladium silsesquioxa-
nate complexes with diamine ligands were studied by multinuclear
NMR spectroscopy [9].
In this paper we report preparation, NMR and DFT studies of
dinuclear platinum complex with bridging O,O-bonded silses-
quioxane. In order to obtain additional information about the
molecular structure of the dinuclear platinum complex we per-
formed DFT calculations.
In the last years we have focused our research on investigation
of coordination capability of incompletely condensed silsesquiox-
ane trisilanol, R7Si7O9(OH)3 to organoplatinum and organo-
palladium complexes. Prior to our work, Abbenhuis [5] and Johnson
[6] have reported platinum silsesquioxane complexes containing O,
O-chelating bidentate silsesquioxanate ligands. A series of phe-
nylplatinum and arylpalladium silsesquioxane complexes with
auxiliary phosphine ligands, trans-[M{O10Si7(c-C5H9)7(OH)2}(Ar)
2. Results and discussion
2.1. Preparation of dinuclear Pt(II) complex
Two pathways were used to synthesize the dinuclear
compound as shown in Eq. (1). Reaction of organoplatinum
complex trans-PtI(Ph)(PEt3)2 (1) with incompletely condensed
silsesquioxane (c-C5H9)7Si7O9(OH)3 (2) in a 2:1 molar ratio and in
the presence of Ag2O leads to the dinuclear platinum complex {[Pt
(Ph)(PEt3)2]2(
m-O)2O9Si7(c-C5H9)7(OH)} (3). The same product was
* Corresponding author. Tel.: þ359 2 8060 311; fax: þ359 2 962 49 40.
E-mail address: nmintcheva@abv.bg (N. Mintcheva).
achieved by coupling reaction of mononuclear platinum complex
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.03.033

N. Mintcheva et al. / Journal of Organometallic Chemistry 695 (2010) 1738e1743
1739
trans-[Pt{O10Si7(c-C5H9)7(OH)2}(Ph)(PEt3)2] (4) and trans-PtI(Ph)
(PEt3)2 (1) in the presence of Ag2O and in toluene medium at
60 ꢀC.
optimization with DFT/ MPW1PW91/DZ method and it was used
further for calculations of the NMR parameters.
R
O
OH
Si
OH
R
O
Si
R
Si
PEt3
Ph Pt
O
OH
R
O
R
Si
O
I
2
O
+
O
Si
O
Ph
Et3P
O
Si
O
6
0 °C
PEt3
Si
,
2
Pt
Si
4
O
t
o
h
l
u
e
PEt3
Et3P
R
n
R
R
O
e
,
Ag
2 O
OH
1
2, R=c-C5H9
Ph
Si
R
Si
(1)
R
Si
Pt
O
O
O
R
PEt3
R
O
Ph
PEt3
Si O
Et3P
O
O
Si
R
O
Pt
Si
O
OH
Si
O
O
R
R
Si
R
h
4
Si
PEt3
R
Si
3, R=c-C5H9
1
OH
O
O
2
,
g
O
R
Ph Pt
I
+
, A
0 °C
O
e
6
R
n
Si O
e
u
l
PEt3
O
O
o
Si
t
Si
O
R
R
1
4, R=c-C5H9
Attempts to synthesize a tricoordinated silsesquioxane complex
with three organoplatinum (Pt(Ph)(PEt3)2) units bonded to silanol
groups were unsuccessful, probably due to steric reasons. In addi-
tion, dinuclear platinum complex with PMe2Ph ligands was not
obtained either.
Complex 3 was isolated as a white solid in 46 % yield and was
characterized by 1H, 13C{1H}, 31P{1H} and 29Si{1H} NMR spectros-
copy in solution. We performed attempts to determine the crystal
structure of the newly synthesized compound. In spite of a good
diffraction pattern, the final calculation was not converged well and
lifted R-factors. Preliminary crystallographic data and details are
summarized in Table 1. The structure of the dinuclear Pt(II) complex
suggested by X-ray analysis was refined by means of geometry
2.2. Calculated structure of dinuclear Pt(II) complex
The structure of Pt(II) complex optimized at MPWPW91/DZ
level is shown in Fig. 1. Selected experimental and calculated
structural data of 3 are collected in Table 2. Since the X-ray deter-
mination of the molecular structure of 3 was not completely
successful, selected bond lengths and angles of 4 are also given in
Table 2 for comparison. The crystallographic data of 4 were previ-
ously published [7].
The complex 3 contains two Pt atoms each bonded to a phenyl
ring, two PEt3 ligands and one bridging silsesquioxanate ligand (see
Fig. 1). Similar coordination mode of silsesquioxane in osmium
complex {[Os3(CO)10(m-H)]2(m-O)2Si7O9(OH)(c-C6H11)7} was sug-
gested by Feher et al. [10]. The geometry around both platinum
centers is square planar. Each phenyl ring is perpendicular to the
corresponding coordination plane. The planes at the two Pt-centers
are not coplanar and the calculated angle between them is about
46ꢀ. According to the experimental X-ray data of 3, the PteL bond
Table 1
Crystallographic data and details of refinement of 3.
Complex 3
ꢀ
distances (L ¼ C, O, P) are longer (up to 0.077 A) than the corre-
Empirical formula
Formula weight
Crystal colour
Crystal dimensions (mm)
Crystal system
C71H134O12P4Si7Pt2
1890.51
Colorless
0.20 ꢁ 0.20 ꢁ 0.05
Monoclinic
P21/n (No. 14)
22.490(9)
15.188(6)
28.199(12)
106.961(5)
9213(7)
4
1.363
3880
32.309
54,936
19,558
0.085
1029
0.1764
sponding Pt0eL’ bond lengths, with exception of Pt0eP2’ bond. The
0
ꢀ
experimental PteC1 and Pt eC1’ bonds (1.96(1) A) are shorter than
ꢀ
the Pt-C distance (2.014(4) A) in mononuclear complex 4. The
PteO1 bond distance (2.122(8) A) is similar to that of 4 (2.129(3) A)
and these are longer than the second Pt -O1’ bond (2.046(7) A) in
the dinuclear complex. In comparison with the experiment, PteL
bond lengths are overestimated with about 0.06 A. The geometry
ꢀ
ꢀ
Space group
0
ꢀ
ꢀ
a (A)
ꢀ
b (A)
ꢀ
ꢀ
c (A)
b
(ꢀ)
differences observed are probably due to the comparison of a gas
phase (obtained after optimization) with the solid state molecular
geometry suggested by the X-ray analysis. The position of the H
atom of the free silanol group is not determined by crystallographic
data and it is completed by the geometry calculations of the
dinuclear Pt(II) complex. The experimental O1/O2 distance of
3
ꢀ
Volume (A )
Z
Calculated density (g.cmꢂ3
)
F(000)
m
/cmꢂ1
No. of reflections measured
No. of unique reflections
Rint
ꢀ
2.626 A is close to the sum of the van der Waals radii of H and O
ꢀ
atoms (2.72 A) [11]. The MPWPW91/DZ method shows distance of
No. of variables
ꢀ
ꢀ
R1 (I > 2.00
wR2 (I > 2.00
Goodness of fit
s
(I))
2.578 A for O1/O2 and 178.3 A for O1/H2eO2 angle, indicating
formation of hydrogen bond between the free OH group and the
coordinated O atom of silsesquioxane. It was found that silanol
s(I))
0.1711
1.455

1740
N. Mintcheva et al. / Journal of Organometallic Chemistry 695 (2010) 1738e1743
Fig. 1. MPWPW91/DZ optimized molecular structure of 3.
groups in several mononuclear platinum silsesquioxane complexes
are also engaged in hydrogen bonding [7e9]. It is worth
mentioning that the calculated structural parameters at
MPWPW91/DZ level confirm the available preliminary X-ray data
and they complete and specify the structure of dinuclear Pt(II)
complex with silsesquioxane.
2.3. Experimental and theoretical NMR study
Our calculations of Ptesilsesquioxane complexes in benzene
have shown insignificant effect of the solvent on the geometry as
well as on the NMR data. Therefore, we accept that the comparison
of the calculated NMR data in gas phase with the experimental
NMR data obtained in solution is reasonable and could help for
reliable interpretation of the experimental NMR spectra. The list of
theoretical chemical shifts of 1H, 13C, 31P, 29Si atoms with OPW91/6-
31G(d,p) basis set and relevant experimental values are presented
in Table S1 in Supplementary materials.
Table 2
Selected experimental and calculated (at MPWPW91/DZ level) structural parame-
ters of 3 and experimental bond lengths and angles of 4 [7].
Exp. 3
MPWPW91/DZ
Exp. 4 [7]
13C NMR data show two sets of signals in the aromatic region at
ꢀ
Bond lengths (A)
d
139.29, 133.54, 122.04 and d 138.23, 132.09, 121.49 ppm assigned,
PteC1
PteO1
PteP1
PteP2
O1eSi1
1.96(1)
2.122(8)
2.311(3)
2.300(4)
1.59(1)
2.029
2.144
2.373
2.376
1.699
2.014(4)
2.129(3)
2.309(1)
2.309(1)
1.593(3)
respectively, to Cortho, Cipso, Cpara of the two unequivalent phenyl
rings coordinated to the platinum centers. Similar chemical shifts
were observed and assigned to the mononuclear platina silses-
quioxane complexes [7]. The NMR calculations predicted six signals
Pt0eC10
Pt0eO10
Pt0eP10
Pt0eP20
O10eSi10
1.96(1)
2.046(7)
2.303(4)
2.325(4)
1.63(1)
2.032
2.124
2.372
2.370
1.686
(1 Cipso
156.89e112.50 ppm for C atoms of each phenyl ring in the complex.
According to the calculations, the chemical shifts for Cortho, Cmeta
, 2 Cortho, 2 Cmeta and 1 Cpara) in the range of
,
Cpara are in agreement with the previous suggestions. On the
contrary to this interpretation, the Cipso peak is calculated at low
magnetic field (156.89 and 156.44 ppm) in line with the less
negative charge on Cipso atom (ꢂ0.190 a.u) as compared to the
charges of the other phenyl carbon atoms (ꢂ0.259Oꢂ0.306 a.u).
More experimental and theoretical data are required to solve the
Cipso peak interpretation.
O1/O2
O2eH2
O1/H2
2.626a
e
2.578
1.040
1.539
2.558(4)
1.84(6)
e
Bond angles (ꢀ)
C1ePteO1
P1ePteP2
C1ePteP1
C1ePteP2
O1ePteP1
O1ePteP2
PteO1eSi1
177.9(3)
175.2(2)
91.0(3)
90.1(3)
87.0(2)
91.9(2)
137.5(5)
176.67
173.59
91.59
89.76
86.90
91.41
132.23
177.9(1)
173.2(4)
88.5(1)
Two pairs of signals are observed in the high magnetic field
region at 7.74; 8.02 ppm and 13.20; 13.74 ppm and according to the
calculations they are assigned to methyl and methylene carbon
atoms of PEt3, respectively. The doublets indicate two couples of
PEt3 ligands in trans position in the coordination plane of each
metal ion. The carbon atoms of the PEt3 ligands and the cyclopentyl
groups produce well distinguished calculated signals, Table S1 in
Supplementary materials. The chemical shifts of CH and CH2
carbons of cyclopentyl substituents are calculated in the range of
32e26 ppm and their interpretation is not sufficiently reliable.
86.6(1)
92.02(8)
92.70(9)
134.6(2)
C10ePt0eO10
P10ePt0eP20
C10ePt0eP10
C10ePt0eP20
O10ePt0eP10
O10ePt0eP20
Pt0eO10eSi10
178.5(4)
169.8(2)
90.6(4)
89.4(4)
88.1(2)
91.9(2)
135.8(6)
178.31
168.91
93.87
90.41
84.90
90.59
131.77
29Si NMR spectrum displays seven signals at
ꢂ64.14, ꢂ66.71, ꢂ66.75, ꢂ67.03 and ꢂ69.21 ppm and provides
evidence for a different chemical environment of each silicon atom
of silsesquioxane framework. We assigned the higher frequency
d
ꢂ58.47, ꢂ58.67,
O1/H2eO2
e
178.30
172(5)
a
The value was taken from the visualized cif file containing the X-ray structure
data.

N. Mintcheva et al. / Journal of Organometallic Chemistry 695 (2010) 1738e1743
1741
resonances (ꢂ58.47 and ꢂ58.67 ppm) to the coordinated Si atoms
3. Conclusion
(PteOeSi) and the signal at ꢂ64.14 ppm to Si of SieOH group
engaged in hydrogen bonding. The next two peaks are positioned
very closely to each other (ꢂ66.71 and ꢂ66.75 ppm) and together
with the signals at ꢂ67.03 and ꢂ69.21 ppm correspond to Si atoms
from internal silsesquioxane backbone. The low magnetic field
shift of Si1, Si1’ and Si2 could be explained with the lower electron
density on the neighboring O atoms (ꢂ1.148, ꢂ1.170, ꢂ1.143 a.u),
which are coordinated to the Pt or are included in OeH/O
bonding, Fig. 1. For comparison the charges of O atoms from sil-
sesquioxane backbone are approximately ꢂ1.25 a.u. According to
the calculations, the NMR signals of Si atoms in silsesquioxane of
dinuclear Pt(II) complex could be used for prediction of coordi-
nation mode to Pt as well as of hydrogen bonding of HeOeSi
group.
The molecular structure of the newly obtained Pt(II) complex of
silsesquioxane trisilanol was predicted by means of DFT calcula-
tions and X-ray analysis. Incompletely condensed silsesquioxane
acts as (m-O,O)-bridging ligand in a dinuclear platinum complex.
The two platinum centers are magnetically unequivalent as
revealed by the NMR data. The SieOH group forms hydrogen bond
with a coordinated oxygen atom. The calculated and experimental
1H, 31P, 13C and 29Si NMR spectra of the dinuclear platinum silses-
quioxane complex are in good agreement and confirmed the sug-
gested molecular structures.
4. Experimental section
In 1H NMR spectrum of 3, a sharp peak at 8.76 ppm is assigned
to the hydrogen from the silanol group. The low magnetic field
position of this signal indicates formation of a hydrogen bond
between the OH group and the coordinated oxygen, in accord with
our geometry calculations of 3. The calculated 1H chemical shift for
OH hydrogen is obtained at 11.18 ppm. In the range 7.64e7.52 ppm,
four peaks were calculated for the C6H5-ortho hydrogen atoms in
the dinuclear complex 3. The values obtained could be grouped and
assigned to two observed 1H NMR signals at 7.56 ppm (doublet)
with JHH ¼ 6.9 Hz and at 7.45 ppm (broaden) corresponding to the
two unequivalent phenyl rings in the dinuclear Pt(II) complex.
The 1H signals of the cyclopentyl substituents (CH and CH2) and
of the PEt3 groups (CH2 and CH3) appear in the high magnetic field
region at 3.6e0.8 ppm. The interpretation of the observed peaks is
complicated because of the numerous CeH groups as well as
because of overlapped signals. The upfield peaks at 1.3 ppm and
1.07 ppm are assigned to CH-pentyl and CH3 signals, respectively.
The platinum complexes trans-[Pt{O10Si7(c-C5H9)7(OH)2}(Ph)
(PEt3)2] (4), trans-[PtI(Ph)(PEt3)2] and its precursor [PtI(Ph)(cod)]
were synthesized as described in [7,13,14], respectively. All
manipulations of the complexes were carried out using standard
Schlenk techniques under argon or nitrogen atmosphere. 1H, 13C
{1H}, 29Si{1H}, and 31P{1H} NMR spectra were recorded on Varian
Mercury 300 or JEOL EX-400 spectrometers.
4.1. Preparation of [(Pt(Ph)(PEt3)2)2{O11Si7(c-C5H9)7(OH)}] (3)
(Cyclo-C5H9)7Si7O9(OH)3 (71 mg, 0.08 mmol) and Ag2O (46 mg,
0.20 mmol) were added to a toluene (10 mL) solution of trans-[PtI
(Ph)(PEt3)2] (103 mg, 0.16 mmol). The mixture was heated at 60 ꢀC
for 24 h. After completion of the reaction, monitored with 31P{1H}
NMR spectroscopy, a grey solid was removed by filtration under
argon. The solvent was evaporated in vacuum, and then 0.5 ml
hexane and 1 ml acetone were added. Cooling of the solution at
ꢂ20 ꢀC for several days afforded 3 as white crystals (70 mg, 46%).
Anal. Calcd. for C71H134O12P2Si7Pt2 (1890.49): C, 45.11; H, 7.14.
Found: C, 44.89; H, 7.06.
A
31P NMR spectrum of 3 consists of two single peaks at
d 17.15 accompanied by platinum satellites with coupling
d 16.40
and
constants J(PtP) ¼ 2876 Hz and J(PtP) ¼ 2905 Hz, respectively.
Chemical shift and the value of the coupling constants are similar
to the previously reported for the mononuclear complex trans-[Pt
{O10Si7(c-C5H9)7(OH)2}(Ph)(PEt3)2] (4) [7]. These patterns clearly
indicate the presence of two magnetically unequivalent platinum
moieties (Pt(Ph)(PEt3)2) coordinated to silanol sites of silses-
quioxane. Four 31P NMR chemical shifts are calculated at 37.53
(P1), 36.93 (P2), 36.18 (P10), 39.37 (P20) ppm. The 31P signal of free
PEt3 is measured at ꢂ20 ppm [12]. When PEt3 is bonded to Pt, the
electron density on P atom decreases due to donor-acceptor
1H NMR (300 MHz, benzene-d6, room temperature):
d 1.07 (m,
36H, PCH2CH3), 1.3 (br m, 7H, CH-pentyl), 1.5e2.4 (br m, 56H, CH2-
pentyl and 24H, PCH2CH3), 7.00 (m, 6H, C6H5 meta and para), 7.45
(br, 2H, C6H5 ortho), 7.56 (d, 2H, C6H5 ortho, JHH ¼ 6.9 Hz), 8.76 (s,
1H, OH). 13C{1H} NMR (100.4 MHz, benzene-d6, room tempera-
ture):
d 7.74, 8.02 (s, PCH2CH3), 13.2 (br, PCH2CH3), 13.74 (vt,
V
PCH2CH3, JCP ¼ 15.5 Hz), 24.28, 24.45, 24.66, 24.67, 25.03, 26.82,
27.63, 27.73e27.97, 28.45ꢂ28.75, 29.81, 29.96, 30.09, 30.16 (7C,
CH-pentyl and 28C, CH2-pentyl), 121.49, 122.04 (C6H5 para),
132.09, 133.54 (C6H5 ipso), 138.23, 139.23 (C6H5 ortho). 29Si{1H}
NMR (79.3 MHz, benzene-d6, 0.02 M Cr(acac)3, room tempera-
P / Pt interaction with dominant
s-donation contribution and
causes significant changes of the chemical shift. Taking into
account the large range of 31P chemical shift the differences
observed between the calculated and the experimental values are
reasonable.
ture):
d
ꢂ58.47, ꢂ58.67, ꢂ64.14, ꢂ66.71, ꢂ66.75, ꢂ67.03, ꢂ69.21.
31P{1H} NMR (122 MHz, benzene-d6, room temperature):
d
16.40,
JPtP ¼ 2876 Hz, 17.15, JPtP ¼ 2905 Hz. IR spectrum (KBr): 3450 (vw),
2949 (s), 2865 (s), 1572 (w), 1456 (w), 1242 (w), 1100 (vs), 990 (m),
900 (w), 766 (w), 739 (w), 733 (w), 704 (w), 633 (w), 500 (m)
2.4. IR data
cmꢂ1
.
The IR data of 3 show broad band at 3450 cmꢂ1 due to stretching
vibration of the OH group. Very similar peak position was observed
in the IR spectrum of PteAg heterobimetallic complex, [Pt{O11Si7(c-
C5H9)7(OH)(AgPPh3)}(Ph)(PPh3)] containing bidentate O,O-coordi-
nated silsesquioxane and one free silanol group, whereas nOH
vibrations of the monodentate platinum silsesquioxanes were
obtained at lower wavenumbers (3300e3200 cmꢂ1) [7]. New bands
in the range 770e700 cmꢂ1 appear in the spectrum of 3 in
comparison with the free silsesquioxane ligand. Peaks at 739 and
733 cmꢂ1 are assigned to the stretching vibration of SieO bonds of
the coordinated silanolate groups. This vibration was observed as
a single peak at 739 cmꢂ1 for monodentate platina silsesquioxane 4.
4.2. Computational details
Geometry optimization of the dinuclear platinum(II) complex
with bridging silsesquioxanate ligand was performed in gas phase
at non-local DFT level of theory using ADF2008 program package
[15]. A density functional, consisting of local density part (VWN)
[16] and exchange-correlation gradient corrected parts
(mPWx þ PW91c) was used [17]. Scalar relativistic effects were
considered by the Zero Order Regular Approximation (ZORA) [18].
A relativistic valence double zeta (DZ) basis set was applied for all
the elements and thus the final level of calculations is MPW1PW91/
DZ. All electron ZORA/DZ calculations were used. The 1H, 13C, 29Si,

1742
N. Mintcheva et al. / Journal of Organometallic Chemistry 695 (2010) 1738e1743
31P isotropic shielding constants of the optimized dinuclear Pt(II)
complex were calculated by using the gauge independent atomic
orbital (GIAO) method [19] and OPW91 functional, implemented in
Gaussian03 program package [20]. With a view to the large system
studied (230 atoms), the 6e31G(d,p) basis set for Si, H, C, O, P atoms
[8] M. Tanabe, K. Mutou, N. Mintcheva, K. Osakada, Organometallics 27 (2008)
519.
[9] N. Mintcheva, M. Tanabe, K. Osakada, Organometallics 26 (2007) 1402.
[10] E. Lucenti, F.J. Feher, J.W. Ziller, Organometallics 26 (2007) 75.
[11] A. Bondi, J. Phys. Chem. 68 (1964) 441.
[12] C.A. Tolman, W.C. Seidel, L.W. Gosser, J. Am. Chem. Soc. 96 (1974) 53.
[13] C.R. Kistner, J.H. Hutchinson, J.R. Dolve, J.C. Storlie, Inorg. Chem. 2 (1963) 1255.
[14] H.C. Clark, L.E. Manzer, J. Organomet. Chem. 59 (1973) 411.
[15] ADF2008.01, SCM, Theoretical Chemistry.http://www.scm.com.
[16] S.H. Vosko, L. Wilk, M. Nusair, Can. J. Phys. 58 (1980) 1200.
[17] (a) C. Adamo, V. Barone, J. Chem. Phys. 108 (1998) 664;
(b) J.P. Perdew, J.A. Chevary, S.H. Vosko, K.A. Jackson, M.R. Pederson, D.J. Singh,
C. Fiolhais, Phys. Rev. B 46 (1992) 6671.
was chosen as
a good compromise between reliability and
computing time. The Pt atom was treated with quasi-relativistic
effective core potential (RECP, MWB60), where 5s25p65d96s1 are
valence electrons and all other 60 electrons are included into the
core. The absolute isotropic magnetic shielding constants (si) were
[18] (a) E. van Lenthe, A.E. Ehlers, E.J. Baerends, J. Chem. Phys. 110 (1999) 8943;
(b) E. van Lenthe, E.J. Baerends, J.G. Snijders, J. Chem. Phys. 99 (1993) 4597;
(c) E. van Lenthe, E.J. Baerends, J.G. Snijders, J. Chem. Phys. 101 (1994) 9783;
(d) E. van Lenthe, J.G. Snijders, E.J. Baerends, J. Chem. Phys. 105 (1996) 6505;
(e) E. van Lenthe, R. van Leeuwen, E.J. Baerends, J.G. Snijders, Int. J. Quant.
Chem. 57 (1996) 281.
used to obtain the chemical shifts (di
¼
sTMS si) by referring to the
ꢂ
standard compounds, tetramethylsilane (TMS) (for Si, C and H
atoms) and H3PO4 (for P atom). Both referred to compounds, TMS
and H3PO4, were calculated at the same OPW91/6-31G(d,p) level of
theory.
[19] (a) K. Wolinski, J.F. Hinton, P. Pulay, J. Am. Chem. Soc. 112 (1990) 8251;
(b) G. Magyarfalvi, P. Pulay, J. Chem. Phys. 119 (2003) 1350.
[20] M.J.Frisch, G.W.Trucks, H.B.Schlegel, G.E.Scuseria, M.A.Robb, J.R.Cheeseman,
J.A.Montgomery, Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S.
Iyengar, J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.
A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J.
Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X.
Li, J.E. Knox, H.P. Hratchian, J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts,
R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski,
P.Y. Ayala, K. Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G.
Zakrzewski, A.D. Daniels, O. Farkas, A.D. Rabuck, K. Raghavachari, J.V. Ortiz.
Gaussian 03.
Acknowledgments
N.M. thanks the Japanese Society for the Promotion of Science
for a postdoctoral fellowship for foreign researchers. This work was
financially supported by Bulgarian Science Fund, Grants DO-02-233
and DO-02-82.
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2010.03.033.
Neli Mintcheva was born in Kavarna, Bulgaria, in 1970.
She graduated from the University of Sofia “St. Kliment
Ohridski”, Bulgaria in 1992 and received her PhD degree in
Analytical Chemistry at the University of Sofia in 2001. In
1999e2000 she was participant in the 35th International
UNESCO Course for Advanced Research in Chemistry and
Chemical Engineering held at Tokyo Institute of Tech-
nology. In 2004 she came back in Japan as a postdoctoral
fellow at Professor Kohtaro Osakada’s laboratory and
studied silsesquioxane complexes. Research interests are
focused in organometallic chemistry, catalysis and bio-
coordination chemistry. Since 2007 she has worked as an
assistant professor at the University of Mining and
Geology, Sofia, Bulgaria.
References
[1] (a) R. Duchateau, H.C.L. Abbenhuis, R.A. Van Santen, A. Meetsma, S.K.-
H. Thiele, M.F.H. Van Tol, Organometallics 17 (1998) 5663;
(b) K. Wada, K. Yamada, T. Kondo, T. Mitsudo, Chem. Lett. (2001) 12;
(c) K. Wada, N. Itayama, N. Watanabe, M. Bundo, T. Kondo, T. Mitsudo,
Organometallics 23 (2004) 5824;
(d) F.T. Edelmann, St. Gießmann, A. Fischer, J. Organomet. Chem. 620 (2001)
80;
(e) K. Wada, D. Izuhara, M. Shiotsuki, T. Kondo, T. Mitsudo, Chem. Lett. (2001)
734;
(f) J.I. van der Vlugt, M. Fioroni, J. Ackerstaff, R.W.J.M. Hanssen, A.M. Mills, A.
L. Spek, A. Meetsma, H.C.L. Abbenhuis, D. Vogt, Organometallics 22 (2003)
5297;
(g) J.I. van der Vlugt, J. Ackerstaff, T. Dijkstra, A.M. Mills, H. Kooijman, A.L.
S. Spek, A. Meetsma, H.C.L. Abbenhuis, D. Vogt, Adv. Synth. Catal. 346 (2004)
399;
(h) F. Liu, K.D. John, B.L. Scott, R.T. Baker, K.C. Ott, W. Tumas, Angew. Chem. Int.
Ed. 39 (2000) 3127;
(i) P.A. Shapley, W.S. Bigham, M.T. Hay, Inorg. Chim. Acta 345 (2003) 255;
(j) V. Lorenz, St. Blaurock, F.T. Edelmann, Z. Anorg. Allg. Chem. 634 (2008)
2819.
Makoto Tanabe was born in Tokyo in 1974. He received his
Bachelor degree in Chemistry in 1998 from Rikkyo
University and his Ph.D. degree in 2003 from the Tokyo
Institute of Technology under the supervision of Prof.
Kohtaro Osakada. He worked in the field of metal-con-
taining polymer chemistry with Prof. Ian Manners at the
University of Toronto in Canada. He joined Chemical
Resources Laboratory of the Tokyo Institute of Technology
in 2004 as an assistant professor in the group led by Prof.
Kohtaro Osakada. His research interest focuses on the
synthesis, properties, and applications of transition metal
multinuclear complexes.
[2] (a) V. Lorenz, S. Blaurock, H. Görls, F.T. Edelmann, Organometallics 25 (2006)
5922;
(b) Y.K. Gun’Ko, R. Reilly, F.T. Edelman, H.-G. Schmidt, Angew. Chem. Int. Ed.
40 (2001) 1279;
(c) G. Wu, Y. Chen, D.-J. Xu, J.-C. Liu, W. Sun, Zh. Shen, J. Organomet. Chem. 694
(2009) 1571.
[3] V. Lorenz, St. Blaurock, F.T. Edelmann, Z. Anorg. Allg. Chem. 634 (2008) 441.
[4] (a) F.J. Feher, T.A. Budzichowski, Polyhedron 14 (1995) 3239;
(b) R. Murugavel, A. Voigt, M.G. Walawalkar, H.W. Roesky, Chem. Rev. 96
(1996) 2205;
Kohtaro Osakada, Ph D. (b 1955 in Japan) is Professor in
Chemical Resources Laboratory at Tokyo Institute of
Technology, Japan. He received Dr. degree from Tokyo
University in 1988. His research interest covers structure
and properties of organotransition metal complexes,
mechanistic studies of homogeneous catalytic reactions,
oligomerization and polymerization of olefins catalyzed by
transition metal complexes, and supramolecules
composed of organometallic molecules. He is a co-leader
of Global COE program (chemistry and material) of Tokyo
Institute of Technology.
(c) H.C.L. Abbenhuis, Chem. Eur. J. 6 (2000) 25;
(d) V. Lorenz, A. Fischer, St. Gie
bmann, J.W. Gilje, Y. Gun’ko, K. Jacob, F.
T. Edelmann, Coord. Chem. Rev. 206-207 (2000) 321;
(e) R. Duchateau, Chem. Rev. 102 (2002) 3525;
(f) R.W.J.M. Hanssen, R.A. van Santen, H.C.L. Abbenhuis, Eur. J. Inorg. Chem.
(2004) 675;
(h) V. Lorenz, F.T. Edelmann, Z. Anorg. Allg. Chem. 630 (2004) 1147;
(i) M.M. Levitskii, V.V. Smirnov, B.G. Zavin, A.N. Bilyachenko, A.Yu. Rabkina,
Kinetics Catal. 50 (2009) 490.
[5] H.C.L. Abbenhuis, A.D. Burrows, H. Kooijman, M. Lutz, M.T. Palmer, R.A. van
Santen, A.L. Spek, Chem. Commun. (1998) 2627.
[6] E.A. Quadrelli, J.E. Davies, B.F.G. Johnson, N. Feeder, Chem. Commun. (2000)
1031.
[7] N. Mintcheva, M. Tanabe, K. Osakada, Organometallics 25 (2006) 3776.

N. Mintcheva et al. / Journal of Organometallic Chemistry 695 (2010) 1738e1743
1743
Ivelina Georgieva was born in Silistra, Bulgaria, in 1966. She
receivedan MSc degreeinInorganicandAnalyticalChemistry
from Sofia University in 1989 and a PhD degree in Inorganic
Chemistry in2001 fromBulgarianAcademy of Sciences. Since
2009 she is Assoc. Prof. in Theoretical Chemistry at the Insti-
tute ofGeneraland InorganicChemistry. She hasbeenvisiting
Researcher in the group of Prof. M. Sodupe, Autonomous
University of Barcelona and in the group of Prof. Lischka,
Vienna University. Her current research interests lie in the
field of theoretical and computational chemistry, coordina-
tion chemistry and material science.
Natasha Trendafilova, Ph.D. (b. 1949 in Bulgaria) is Assoc.
Prof. in Theoretical Chemistry at the Bulgarian Academy of
Sciences, Institute of General and Inorganic Chemistry,
Head of Coordination Chemistry Department; Research
interests and current scientific work lie in the field of the
computational chemistry, coordination chemistry, and
materials science. Co-author of 68 scientific papers; Leader
of 3 national scientific projects; participation in long-term
research cooperation with the Technical University of
Vienna; President of the Scientific Council of the Institute
of General and Inorganic Chemistry; Member of the
National Scientific Council of Theoretical and Computa-
tional Chemistry.
Dr. Tzvetan T. Mihaylov earned his MSc in Inorganic and
Analytical Chemistry from Sofia University, Bulgaria in
2001. After two years working as research chemist, he
pursued and received the Ph.D. in Theoretical Chemistry
from the Institute of General and Inorganic Chemistry,
Bulgarian Academy of Sciences, awarded in 2009. Dr.
Mihaylov’ research interests and current research work lie
in the field of the computational chemistry, coordination
chemistry and bioinorganic chemistry - Ab initio, DFT and
MM modeling of geometrical, electronic and vibrational
structure of 3d- and 4f metal complexes, estimation of the
metal-ligand bonding properties, reactivity indices, inter-
and intramolecular hydrogen bondings.