Family of penta- and hexanuclear metallasilsesquioxanes: Synthesis, structure and catalytic properties in oxidations

Article abstract of DOI:10.1016/j.jorganchem.2017.10.033

The deliberate synthesis of two types of prismatic cage-like metallasilsesquioxanes (hereinafter, referred to as CLMSs), viz., penta- and hexanuclear ones, is reported. It is shown that the size of the prismatic cage can be readily and reliably controlled by synthesis parameters. More specifically, the nuclearity shift from six, which is most common in CLMS chemistry (complexes 1–6, 8), to five, which is observed significantly more rarely, is achieved by applying pyridine as a key solvent/crystallization medium (complexes 7, 9–12). Structures of 1–12 were established by single-crystal X-ray diffraction. In sum, their composition could be described as [PhSiO_1.5]₁₂[CuO]₆ (for hexanuclear products) or [RSiO_1.5]₁₀[MO]₅ (R = Ph, Vin, M = Cu, Ni, Co for pentanuclear products). Compounds 7, 9–10 represent the rare examples of cage silsesquioxanes comprising pentagonal metalla-oxa rings of Cu(II) ions. The complex 10 is the very first observation of a co-crystal composed of different CLMS (i.e., two Co(II)₅ and one Cu(II)₅ prismatic cages). The compound 12 (Co₅ cage with vinyl substituents at the silicon atoms) is the very first example of a pentanuclear CLMS-based coordination polymer. Complex 7 efficiently catalyzes oxidation of secondary alcohols to the corresponding ketones and alkanes to the corresponding alkyl hydroperoxides.

Full text of DOI:10.1016/j.jorganchem.2017.10.033

Accepted Manuscript
Family of penta- and hexanuclear metallasilsesquioxanes: Synthesis, structure and
catalytic properties in oxidations
Alexey N. Bilyachenko, Alena N. Kulakova, Lidia S. Shul'pina, Mikhail M. Levitsky,
Alexander A. Korlyukov, Victor N. Khrustalev, Yan V. Zubavichus, Pavel V.
Dorovatovskii, Ul'yana S. Tsareva, Elena S. Shubina, Artem A. Petrov, Nikolay V.
Vorontsov, Georgiy B. Shul'pin
PII:
S0022-328X(17)30620-4
10.1016/j.jorganchem.2017.10.033
JOM 20153
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 1 September 2017
Revised Date: 22 October 2017
Accepted Date: 24 October 2017
Please cite this article as: A.N. Bilyachenko, A.N. Kulakova, L.S. Shul'pina, M.M. Levitsky, A.A.
Korlyukov, V.N. Khrustalev, Y.V. Zubavichus, P.V. Dorovatovskii, Ul'.S. Tsareva, E.S. Shubina, A.A.
Petrov, N.V. Vorontsov, G.B. Shul'pin, Family of penta- and hexanuclear metallasilsesquioxanes:
Synthesis, structure and catalytic properties in oxidations, Journal of Organometallic Chemistry (2017),
doi: 10.1016/j.jorganchem.2017.10.033.
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ACCEPTED MANUSCRIPT
Manuscript for Journal of Organometallic Chemistry, Special Issue "Organometallic Chemistry in
Russia" dedicated to Professor I.P. Beletskaya
Research Article
Family of penta- and hexanuclear metallasilsesquioxanes: synthesis,
structure and catalytic properties in oxidations
a,b,
a,b
a
a
Alexey N. Bilyachenko, * Alena N. Kulakova, Lidia S. Shul’pina, Mikhail M. Levitsky,
a,c
b
d
d
Alexander A. Korlyukov, Victor N. Khrustalev, Yan V. Zubavichus, Pavel V. Dorovatovskii,
a
a
a,b
e
Ul’yana S. Tsareva, Elena S. Shubina, Artem A. Petrov, Nikolay V. Vorontsov,
e,f,
Georgiy B. Shul’pin *
a Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Str., 28,
19991 Moscow, Russia
1
b Peoples’ Friendship University of Russia (RUDN University), Miklukho-Maklaya Str., 6, 117198
Moscow, Russia
c Pirogov Russian National Research Medical University, Ostrovitianov str., 1, 117997 Moscow, Russia
d National Research Center “Kurchatov Institute”. Akademika Kurchatova pl., 1, 123182 Moscow, Russia
e Plekhanov Russian University of Economics, Stremyannyi pereulok, dom 36, Moscow 117997, Russia
f Semenov Institute of Chemical Physics, Russian Academy of Sciences, ulitsa Kosygina, dom 4,
Moscow 119991, Russia.
_____________________________________________________
ARTICLE INFO
This article is dedicated to Professor Irina P. Beletskaya.
_____________________________________________________
Keywords:
Alkanes
Catalysis
Complexes of copper, nickel and cobalt
Functionalization of CH bonds
Metallasilsesquioxanes
Oxidation with hydrogen peroxide
1

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Highlights
-
-
-
-
New penta- and hexanuclear metallasilsesquioxanes have been synthesized
A structure of a complex depends on presence of pyridine in reaction media
Some complexes are good catalysts in oxidation of alkanes with H O
2
2
Hydroxyl radicals take part in the reaction, O from atmosphere is inserted into C-H bonds
2
________________________________________________________
ABSTRACT
The deliberate synthesis of two types of prismatic cage-like metallasilsesquioxanes (hereinafter, referred
to as CLMSs), viz., penta- and hexanuclear ones, is reported. It is shown that the size of the prismatic
cage can be readily and reliably controlled by synthesis parameters. More specifically, the nuclearity shift
from six, which is most common in CLMS chemistry (complexes 1 - 6, 8), to five, which is observed
significantly more rarely, is achieved by applying pyridine as a key solvent/crystallization medium
(complexes 7, 9 - 12). Structures of 1 - 12 were established by single-crystal X-ray diffraction. In sum,
their composition could be described as [PhSiO ] [CuO] (for hexanuclear products) or
1.5 12
6
[
RSiO ] [MO] (R = Ph, Vin, M = Cu, Ni, Co for pentanuclear products). Compounds 7, 9 - 10
1.5 10 5
represent the rare examples of cage silsesquioxanes comprising pentagonal metalla-oxa rings of Cu(II)
ions. The complex 10 is the very first observation of a co-crystal composed of different CLMS (i.e., two
Co(II) and one Cu(II) prismatic cages). The compound 12 (Co cage with vinyl substituents at the
5
5
5
silicon atoms) is the very first example of a pentanuclear CLMS-based coordination polymer. Complex 7
efficiently catalyzes oxidation of secondary alcohols to the corresponding ketones and alkanes to the
corresponding alkyl hydroperoxides.
_____________________________________________________________________________
*
Corresponding authors. Tel.: +7 495 9397317; fax: +7495 6512191.
E-mail addresses: for ANB, bilyachenko@ineos.ac.ru; for GBS, shulpin@chph.ras.ru
Graphical Abstract:
1. Introduction
Unusual representatives of ever-growing family of cage compounds, cage-like
metallasilsesquioxanes (CLMSs), are the subject of unflagging interest of many scientific teams
worldwide due to enthralling properties of such complexes. Major goals of CLMSs’ chemistry encompass
studies of their intriguing structural organization [1] as well as diverse catalytic applications [2]. Several
works also unveiled the potential of CLMSs’ reactivity [3] and non-trivial magnetic effects due to specific
location and exchange interactions between metal ions in the silsesquioxane matrix (spin glass behavior)
[
4]. One of the most widespread family of CLMSs include prismatic (cylindrical) type cages with two
silsesquioxane [(PhSiO )] rings coordinating a central metal oxide layer (MO) . It is worth mentioning
1
.5
x
x
that since the classical work of one of us [5], hexanuclear prismatic cages has proven to be most frequent
and affordable with more than 25 representatives of [RSiO ] [MO] stoichiometry [1a, 1c, 1f] in CCDC.
1
.5 12
6
Some of higher nuclearity prismatic CLMSs were also described [1c, 6] (including the largest known to
2

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date Cu -cage reported by some of us very recently [7]. To the contrary, capabilities of deliberate
9
synthesis of smaller prismatic CLMSs was also discussed by us [4b,4d] and others [1j] (Fig. 1).
Fig. 1. General view of prismatic CLMS’ structure (M = Cu, Mn, Co, Ni, Cd; n = 1, 2, 4, 5; R = Me, Ph)
2. Results and Discussion
In the present article we report that cyclohexane and other alkanes as well as benzene can be
oxidized to the corresponding alkyl hydroperoxides and phenol, respectively, by hydrogen peroxide in air
in the presence of catalytic amounts of ferrocene and pyrazine-2-carboxylic acid (PCA; for co-catalytic
role of this compound in various reactions, see a review [4]) or trifluoroacetic acid, as shown in eqs. (1)
and (2). The reaction proceeds in acetonitrile solution under mild conditions (typically at 50 °C). Alkyl
hydroperoxide is relatively stable in the solution, and can be easily reduced by PPh to the corresponding
3
alcohol.
In this article, we report on our success in nuclearity-controlled synthesis of prismatic CLMSs with
comprehensive characterization of 12 novel complexes containing penta- and hexanuclear cage
silsesquioxanes. The strong influence of pyridine media favoring the formation of pentanuclear prismatic
copper(II) complexes (the so-called pyridine factor) was shown to be valid also for Ni(II)-based CLMS,
for mixed Co(II)/Cu(II)-phenylsilsesquioxane system’ organization as well as for the first
vinylsilsesquioxane containing cobalt ions. In turn, the results of the first evaluation of pentanuclear
Cu(II)-CLMSs in catalysis (in oxidation of alkanes and alcohols) are presented.
2.1. Synthesis
At the first stage, features of exchange interaction between siloxanolate species
[
(PhSiO )(NaO )] and copper(II) chloride were studied. The variation of synthesis/crystallization
1.5 0.5 x
media (Fig. 2) does not affect the nuclearity of prismatic Cu(II)-CLMSs afforded. Compounds 1-6 belong
to the hexanuclear type confirming the aforementioned fact on the striking abundance of such complexes.
3

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Fig. 2. General scheme of synthesis of hexacopper CLMSs 1 - 6
At the second stage, the synthetic procedure elaborated for the synthesis of complexes 1-6 was
modified by applying pyridine as the main solvent. This unexpectedly gave rise to a rare type of smaller
nuclearity’ prismatic CLMS, viz. a pentanuclear Cu(II)-cage (compound 7, Fig. 3). The first observation
of a similar structure (synthesized from Cu(I)-based reagent) has been reported by some of us in recent
work [1j].
Fig. 3. General scheme of synthesis of Cu-CLMS 7. The use of pyridine promotes the formation of the
pentanuclear cage product.
Taking into account the obvious structural difference between compounds 1-6 and 7 it becomes
obvious that the pyridine coordination plays an essential role in switching the preferred nuclearity. It could
be easily observed (Fig. 4) that in the case of a Si-Si-Si angle corresponding to a regular pentagon (108.5
4

ACCEPTED MANUSCRIPT
°
) the pyridine molecules coordinated to neighboring copper sites perfectly fit to the available van der
Waals space. To the contrary, in the case of a Si-Si-Si angle typical of a hexagonal structure the same
arrangement of pyridines is not so sterically favorable. This could be a driving force for the selective
formation of pentanuclear compound 7 in the presence of pyridine.
Fig. 4. Front and top views of neighboring Py-coordinating copper ions in 7 (van der Waals spheres and
the Si-Si-Si angle are shown to explain steric features of complex 7)
In order to explore the pyridine effect in the CLMS’ formation more comprehensively, we have
performed the following procedures. Firstly, it has been revealed that the uncommon nuclearity structure 7
is inherited even after recrystallization from DMF giving rise to complex 8 (Fig. 5, left) despite the fact
that the direct self-assembly reaction between [(PhSiO )(NaO )] and copper(II) chloride in DMF (at the
1
.5
0.5 x
absence of pyridine, Fig. 5, right) readily affords the classical hexanuclear complex 9. It should be noted
that DMF-surrounded complex similar to compound 9 was reported earlier in ref. 8. Two these products
differ from each other by the number of DMF solvated molecules and consequently by the unit cell
volume.
5

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Fig. 5. Parallel syntheses of Cu-CLMSs 8 and 9. Left: DMF substitution for pyridine solvates in 7 with the
preservation of the pentanuclear core in 8. Right: Direct self-assembly reaction in DMF affording the
hexanuclear product 9.
As it follows from a close inspection of crystallographic parameters of compounds 7 and 8 (Table
1) they can be ascribed as isostructural. This allows us to conclude that the nature of solvates can indeed
play a crucial role in the self-assembly of CLMS cage (compare complexes 8 and 9). In turn, the
replacement of solvate surrounding in the prebuilt CLMS skeleton (compare complexes 7 and 8, see Table
1) does not provoke deep structural changes. This points to stability of the cage structure of CLMS during
the recrystallization procedure (two-way transfer “solid state – solution – solid state”).
Table 1. Structure parameters of complexes 7 and 8
Si-O Å
∠ SiOSi Cu-Cu ∠ CuOCu
Å
7
8
1.61 -
132.7 -
137.4
2.81 - 90.8 - 92.2
2.84
1
.63
1.63 -
.64
133.0 -
137.6
2.78 - 89.6 - 93.5
2.84
1
Secondly, it was of interest for us to elucidate the role of pyridine media for the synthesis of CLMS
with different metal ions. Thus the self-assembly reaction between [(PhSiO )(NaO )] and a 1:1 mixture
1
.5
0.5
x
of copper(II) and cobalt(II) chlorides has been performed. Under these conditions one could expect the
formation of cage silsesquioxane containing metal ions of both types simultaneously (the occurrence of
polymetallic cages is well known in CLMSs chemistry [1c]). Instead of this, we isolated compound 10,
which represents the very first example of a co-crystal of CLMSs composed of different metals. This
complex is a result of a redistribution of metal ions between silsesquioxane matrixes giving a mixed crystal
of prismatic Co and Cu cages in a 2:1 ratio (Fig. 6).
5
5
6

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Fig. 6. General scheme of synthesis of mixed metal (Co/Cu) CLMS 10. The use of pyridine enables mixed
crystals of pentanuclear Co and Cu cages (in ratio 2:1).
5
5
This product, in addition to its other features, is attractive as an observation of the pentanuclear
cobaltsilsesquioxane cage formation. Recently, some of us reported on the synthesis of the first
pentanuclear cobaltphenylsilsesquioxane as a result of DMF participation as a key media [4d]. Thus, the
new complex 10 expands the list of “pentanuclear prospective” solvates with pyridine. This encouraged us
to perform a “pyridine governed” synthesis of Ni(II)-containing silsesquioxane. It is important that some of
us observed an isolation of the first pentanuclear Ni(II)-phenylsilsesquioxane as a result of the
complexation with DMF [4b]. The self-assembling reaction of [(PhSiO )(NaO )] and Ni(NH ) Cl in
1
.5
0.5
x
3 6
2
pyridine solution gave a pentanuclear product (PhSiO ) (NiO) 11, confirming the ability of pyridine to
1
.5 10
5
induce the pentanuclear metallasilsesquioxane assembly (Fig. 7).
7

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Fig. 7. General scheme of synthesis of Ni-CLMS 11. The use of pyridine gives rise to the pentanuclear
cage product.
Finally, the syntheses of CLMSs with less sterically hindered substituents at silicon atoms (e.g.,
vinyl instead of phenyl) have been performed. The self-assembly reaction of [(VinSiO )(NaO )] species
1
.5
0.5 x
(
generated in situ from VinSi(OMe) ) and cobalt(II) chloride in pyridine media results in the formation of
3
expected pentanuclear cage complex with (VinSiO ) (CoO) stoichiometry 12 (Fig. 8, top). To our
1
.5 10
5
delight, these cages succeeded in their supramolecular organization forming a 1D coordination polymer
structure (Fig. 8, bottom). This is the first instance of Co-based prismatic silsesquioxane forming a
coordination polymer structure. No doubt that this supramolecular architecture became possible due to
lower steric demands of vinyl groups as compared to phenyl ones [9]. Our team is going to present
additional results within the context of CLMSs’ molecular/supramolecular aggregation in our future
reports.
8

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Fig. 8. Top. General scheme of synthesis of Co-CLMS 12. The use of pyridine gives rise to the
pentanuclear cage product. Bottom. 1D coordination polymer packing of complex 12.
A comparison of structural parameters of pentagonal M fragments in reported complexes has
5
revealed that the mean M…M distances are very similar irrespective of the nature of the transition metal.
The shortest M…M distance is observed in the case of cobalt-containing complex (2.805 Å) while the
longest one in realized in the case of nickel-containing one (2.842 Å). Compounds 7 and 8 are
characterized by M…M distances intermediate between Co and Ni moieties (2.831 and 2.812 Å,
5
5
respectively). At the same time, mean Cu…Cu values in 10 are considerably larger than those in 7 and 8
2.884 Å). For the cobalt-containing complex, the shortest Co…Co distance can be explained by the
(
presence of hydroxyl anion encapsulated into the metallasilsesquioxane moiety. In turn,
pentanickelsilsesquioxane moieties contain no hydroxyl anion (note that Ni -CLMS, reported by one of us
10
[
10] includes similar to described in this article [(C H SiO )] cyclic ligands and encapsulates hydroxyl
9 9 1.5 5
species).
9

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2.2. Catalyzed oxidations
Recently we have reported on high catalytic activity of the several types of Cu(II)-based
silsesquioxane (bi-[11a-b], tetra- [11b-c], hexa- [11d] or nonanuclear [7]) in homogeneous oxidations of
alkanes, arenes and alcohols. Thus, we were interested in testing of the catalytic properties of pentanuclear
compound 7.
2.2.1. Oxidation of alcohols to ketones by TBHP
Complex 7 was found to be a good catalyst in oxidations of alcohols and alkanes with TBHP and
H O , respectively. It is important to note that the reaction with cyclohexane does not occur in the absence
2
2
of nitric acid. 1-Phenylethanol and heptanol-2 could be converted into corresponding ketones in yields up
to 94% and 50%, respectively (Fig. 9).
concentration (M)
yield 94%
0.4
0.3
0.2
0.1
0
1
2
0
1
2
3
4
time (h)
Fig. 9. Accumulation of acetophenone (1) and cyclohexanone (2) with time in the oxidation of 1-
phenylethanol and cyclohexanol (initial concentration was 0.4 M) with TBHP (70% aqueous; initial
‒
4
concentration 1.2 M) catalyzed by compound 7 (5 × 10 M; curve 1), HNO (0.05M). Solvent was
3
acetonitrile (total volume of the reaction solution was 5 mL); 60 °C.
2
.2.2. Hydroperoxidation of alkanes by H O
2 2
Cyclohexane has been converted into cyclohexyl hydroperoxide which was gradually transformed
in a mixture of cyclohexanol and cyclohexanone in the course of the oxidation (Fig. 10).
1
0

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0.08
concentration (M)
1
0
.06
.04
0
0.02
2
0
0
1
2
3
time (h)
Fig. 10. Accumulation of cyclohexanol (1) and cyclohexanone (2) with time in the oxidation of
cyclohexane (initial concentration was 0.46 M) with H O (70% aqueous; initial concentration 2 M)
2
2
‒
4
catalyzed by compound 7 (5 × 10 M; curve 1), HNO (0.05M). Solvent was acetonitrile (total volume of
3
the reaction solution was 5 mL); 60 °C. All samples were reduced by PPh before GC.
3
Regioselectivity parameters in the oxidation of n-heptane catalyzed by complex 7 are given in
Table 2. The oxidation of cis-1,2-dimethylcyclohexane with H O occurs without retention of
2
2
configuration (the trans/cis ratio was 0.8 where the trans/cis is the ratio of isomers of tert-alcohols with
mutual trans- and cis-orientation of the methyl groups). These parameters indicate that the oxidation with
H O occurs with the participation of free hydroxyl radicals [12].
2
2
Table 2. Oxidation of n-heptane with H O catalyzed by 7.
2
2
Entry Time (min)
C(1):C(2):C(3):C(4)
1: 4.1: 4.4:4.5
1
2
3
60
120
180
1: 5.6: 5.5:5.2
1: 5.7: 5.8:5.5
‒
4
Note. Oxidation of cyclohexane (0.46 M) with H O (50%, 2 M) catalyzed by complex 7 (5 × 10
2
2
M) in the presence of HNO (0.05 M) at 60 °C. Concentrations of products (isomeric alcohols) were
3
measured after reduction with PPh . The parameter C(1):C(2):C(3):C(4) is given after normalization
3
which takes into account the number of hydrogen atoms at each carbon
3. Conclusions
The parallel synthesis of cage metallasilsesquioxanes revealed a high stability of hexanuclear
prismatic type as demonstrated by the isolation of a new family of six Cu complexes 1 - 6, 8 despite the
6
significant variation of reaction/crystallization media (THF, EtOH, MeCN,…). In turn, application of
pyridine as a key reaction media was found to induce an unusual pentacopper complex 7 formation. The
1
1

ACCEPTED MANUSCRIPT
pyridine-driven formation of pentanuclear cages was also found for mixed Cu/Co-silsesquioxane complex
0, as well as for Ni- and Co-based compounds 11 and 12. Complex 12 bearing less sterically huindered
1
vinyl groups at silicon atoms (with respect to phenyls in 1 - 11) form 1D coordination polymer structure,
which is the very first example among all types of prismatic copper silsesquioxanes. Complex 7 is the first
example of pentanuclear Cu(II)-silsesquioxane chosen for the catalytic testing. It has been found that
compound 7 efficiently catalyzes oxidation of secondary alcohols to the corresponding ketones by TBHP
and alkanes to the corresponding alkyl hydroperoxides by H O .
2
2
4
.
Experimental section
.1. Syntheses
PhSi(OMe) was purchased from Sigma-Aldrich and used as received. Solvents were purchased
4
3
from Panreac.
Syntheses of complexes 1-9
2
g (0.01 mol) of PhSi(OMe) and 0.405 g (0.01 mol) of NaOH were dissolved in 25 mL of
3
ethanol and the resulting mixture was heated to reflux for 2 h. Afterwards the solution was cooled to room
temperature and 0.672 g (0.005 mol) of CuCl was added at once. The solution was left under stirring for
2
3
h and filtered off from the insoluble precipitate. The filtrate was left for crystallization (being mixed
with 15 ml of DMF, complex 1) or dried in vacuum and recrystallized from corresponding solvate
systems (complexes 2-5), see below for details. Several crystals of each product were studied by single
crystals X-ray diffraction (see below for X-ray investigation section).
Complex 1. Anal. Calcd for [(PhSiO ) (CuO) ] Cu, 18.80; Si, 16.62. Found (for vacuum-dried sample):
1.5 12
6
Cu, 18.71; Si, 16.50%. Yield 0.75 g (44%).
Complex 2. Recrystallization from mixture (20 ml/20 ml) of DMF/THF. Anal. calcd for
(PhSiO ) (CuO) ] Cu, 18.80; Si, 16.62. Found (for vacuum-dried sample): Cu, 18.71; Si, 16.50%.
[
1
.5 12
6
Yield 1.09 g (64%).
Complex 3. Recrystallization from 40 ml of DMSO. Anal. calcd for [(PhSiO ) (CuO) ] Cu, 18.80; Si,
1
.5 12
6
16.62. Found (for vacuum-dried sample): Cu, 18.69; Si, 16.49%. Yield 0.89 g (53%).
Complex 4. Recrystallization from 50 ml of hot MeCN. Anal. calcd for [(PhSiO ) (CuO) ] Cu, 18.80;
1
.5 12
6
Si, 16.62. Found (for vacuum-dried sample): Cu, 18.72; Si, 16.52%. Yield 0.68 g (40%).
Complex 5. Recrystallization from 40 ml of PhCN. Anal. calcd for [(PhSiO ) (CuO) ] Cu, 18.80; Si,
1
.5 12
6
16.62. Found (for vacuum-dried sample): Cu, 18.68; Si, 16.48%. Yield 0.25 g (15%).
Complex 6. Recrystallization from 40 ml of THF. Anal. calcd for [(PhSiO ) (CuO) ] Cu, 18.80; Si,
1
.5 12
6
16.62. Found (for vacuum-dried sample): Cu, 18.67; Si, 16.50%. Yield 0.87 g (50%).
Complex 7. Recrystallization from 40 ml of pyridine. Anal. calcd for [(PhSiO ) (CuO) ] Cu, 18.80; Si,
1
.5 10
5
16.62. Found (for vacuum-dried sample): Cu, 18.71; Si, 16.52%. Yield 1.12 g (66%).
Complex 8. Recrystallization of dried complex 6 (0.5 g) from 40 ml of DMF. Anal. calcd for
(PhSiO ) (CuO) ] Cu, 18.80; Si, 16.62. Found (for vacuum-dried sample): Cu, 18.72; Si, 16.50%.
[
1
.5 10
5
Yield 0.39 g (78%).
1
2

ACCEPTED MANUSCRIPT
Complex 9. Recrystallization from 40 ml of DMF. Anal. calcd for [(PhSiO ) (CuO) ] Cu, 18.80; Si,
1
.5 12
6
16.62. Found (for vacuum-dried sample): Cu, 18.71; Si, 16.51%. Yield 1.36 g (80%).
Synthesis of complex 10.
g (0.01 mol) of PhSi(OMe) and 0.405 g (0.01 mol) of NaOH were dissolved in 25 mL of
2
3
ethanol, and the resulting mixture was heated to reflux for 2 h. Afterwards the solution was cooled to
room temperature, and mixture of 0.335 g (2.49 mmol) of CuCl and 0.324 g (2.49 mmol) of CoCl was
2
2
added at once. The solution was left under stirring for 3 h and filtered off from the insoluble precipitate.
Filtrate was dried in vacuum and recrystallized from 40 ml of pyridine. Several crystals of resulted
crystalline product were studied by single crystals X-ray diffraction (see below for X-ray investigation
section). Anal. calcd for {[(PhSiO ) (CoO) (H O) ] [(PhSiO ) (CuO) ]} Co, 11.57; Cu, 6.24; Si,
1
.5 10
5
2
2 2
1.5 10
5
16.54. Found (for vacuum-dried sample): Co, 11.49; Cu, 6.18; Si, 16.47. Yield 0.37 g (29%).
Synthesis of complex 11.
g (0.01 mol) of PhSi(OMe) and 0.405 g (0.01 mol) of NaOH were dissolved in 25 mL of
2
3
ethanol, and the resulting mixture was heated to reflux for 2 h. Afterwards the solution was cooled to
room temperature, and 1.157 g (0.005 mol) of Ni(NH ) Cl was added at once. The solution was heated to
3
6
2
reflux for 6 h and then left under stirring overnight. Afterward reaction solution was filtered off from the
insoluble precipitate. Filtrate was dried in vacuum and recrystallized from 40 ml of pyridine. Several
crystals of resulted crystalline product were studied by single crystals X-ray diffraction (see below for X-
ray investigation section). Anal. calcd for [(PhSiO ) (NiO) ] Ni, 17.62; Si, 16.86. Found (for vacuum-
1
.5 10
5
dried sample): Ni, 17.53; Si, 16.78. Yield 0.59 g (35%).
Synthesis of complex 12.
2
g (0.013 mol) of VinSi(OMe) and 0.54 g (0.013 mol) of NaOH were dissolved in 25 mL of
3
ethanol, and the resulting mixture was heated to reflux for 2 h. Afterwards the solution was cooled to
room temperature, and 0.86 g (6.62 mmol) of CoCl was added at once. The solution was left under
2
stirring for 3 h and filtered off from the insoluble precipitate. Filtrate was dried in vacuum and
recrystallized from 40 ml of pyridine. Several crystals of resulted crystalline product were studied by
single crystals X-ray diffraction (see below for X-ray investigation section). Anal. calcd for
[
(VinSiO ) (CoO) (NaOH)] Co, 24.43; Si, 23.29. Found (for vacuum-dried sample): Co, 24.34; Si,
1.5 10 5
23.20. Yield 0.58 g (36%).
4.2. X-ray structures determination
X-ray diffraction data for 1, 3, 4, 9 - 12, were collected on the ‘Belok’ beamline of the National
Research Center ‘Kurchatov Institute’ (Moscow, Russian Federation) using a Rayonix SX165 CCD
detector. A total of 720 images were collected using an oscillation range of 1.0° and scan mode, and
ϕ
corrected for absorption using the Scala program [13]. The data were indexed, integrated and scaled using
the utility iMOSFLM in CCP4 program [14]. X-ray diffraction data for 2, 5-8 were collected on a three-
circle Bruker APEX-II CCD diffractometer of Center for molecular composition studies of INEOS RAS
(
[
(
graphite monochromator, ϕ and ω scan mode) and corrected for absorption using the SADABS program
15]. The data were indexed and integrated using the SAINT program [16]. For details, see Tables S1-3
ESI). The structures were determined by direct methods and refined by full-matrix least squares
2
technique on F with anisotropic displacement parameters for non-hydrogen atoms. In the case of 2, 6,
and 10, all attempts to model and refine positions of the solvate molecules were unsuccessful. Therefore,
their contribution to the total scattering pattern was removed by use of the utility SQUEEZE in
PLATON06 [17] or Solvent mask procedure in Olex2 program. The hydrogen atoms of the OH-groups as
well as the water and acetonitrile solvate molecules were localized in the difference-Fourier map and
included in the refinement within the riding model with fixed isotropic displacement parameters. The
other hydrogen atoms were placed in calculated positions and refined within riding model with fixed
isotropic displacement parameters [U (H) = 1.5U (C) for the CH -groups and 1.2U (C) for the other
iso
eq
3
eq
groups]. All calculations were carried out using the SHELXTL [18] and Olex2 [19] programs.
1
3

ACCEPTED MANUSCRIPT
Crystallographic data for 1-12 have been deposited with the Cambridge Crystallographic Data
Center, CCDC 1566402 - 1566406, 1566412 - 1566418. Copies of this information may be obtained free
of charge from the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (Fax: +44 1223 336033;
e-mail: deposit@ccdc.cam.ac.uk or www.ccdc.cam.ac.uk).
4.3. Hydroperoxidation of Alkanes by Hydrogen Peroxides
Catalyst 7 was introduced into the reaction mixture in the form of solid powder. The alkane was
then added and the reaction started when hydrogen peroxide was introduced in one portion. (CAUTION.
The combination of air or molecular oxygen and H O with organic compounds at elevated temperatures
2
2
may be explosive!). The reactions after addition of nitromethane as a standard compound were analyzed
by GC. As we made previously, the samples obtained in the alkane oxidation were typically analyzed
twice (before and after their treatment with PPh ) by GC. This method (the comparison of chromatograms
3
of the same sample obtained before and after addition of PPh ) which was proposed by Shul’pin earlier
3
[
20] allows us to estimate real concentration of alkyl hydroperoxide, ketone (aldehyde) and alcohol
present in the reaction solution. Attribution of peaks was made by comparison with chromatograms of
authentic samples and by GC–MS. In our kinetic studies described below, we measured concentrations of
cyclohexanone and cyclohexanol only after reduction of the reaction mixture with PPh because in this
3
case we measure precisely concentration of a sum of the oxygenates. Blank experiments with
cyclohexane showed that in the absence of a catalyst products were formed in negligible concentrations.
4.4. Oxidation of Alcohols to Ketones by TBHP
These reactions were carried out analogously. Triphenylphosphine was added in order to reduce
1
remain TBHP to isopropanol. The reactions with 1-phenyethanol were analyzed by H NMR method
(
solutions in acetone-d ; “Bruker AMX-400” instrument, 400 MHz).
6
Acknowledgments
This work has been supported by the "RUDN University Program 5-100" and the Russian
Foundation for Basic Research (Grants 16-29-05180 and 16-03-00254). Synchrotron single-crystal
diffraction measurements were performed at the unique scientific facility Kurchatov Synchrotron
Radiation Source supported by the Ministry of Education and Science of the Russian Federation (project
code RFMEFI61917X0007).
Appendix A. Supplementary data
Supplementary data related to this article (details of X-ray experiments) can be found at xxxx
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Highlights
-
-
-
-
New penta- and hexanuclear metallasilsesquioxanes have been synthesized
A structure of a complex depends on presence of pyridine in reaction media
Some complexes are good catalysts in oxidation of alkanes with H2O2
Hydroxyl radicals take part in the reaction, O2 from atmosphere is inserted into C-H bonds