Unusual Tri-, Hexa-, and Nonanuclear Cu(II) Cage Methylsilsesquioxanes: Synthesis, Structures, and Catalytic Activity in Oxidations with Peroxides

Article abstract of DOI:10.1021/acs.inorgchem.7b00061

Three types of unusual cagelike copper(II) methylsilsesquioxanes, namely, nona- [(MeSiO_1.5)₁₈(CuO)₉] 1, hexa- [(MeSiO_1.5)₁₀(HO_0.5)₂(CuO)₆(C₁₂H₈N<

Full text of DOI:10.1021/acs.inorgchem.7b00061

Article
pubs.acs.org/IC
Unusual Tri‑, Hexa‑, and Nonanuclear Cu(II) Cage
Methylsilsesquioxanes: Synthesis, Structures, and Catalytic Activity
in Oxidations with Peroxides
,
†,‡
,∥
†,‡
†
†
Alexey N. Bilyachenko,*
Alena N. Kulakova, Mikhail M. Levitsky, Artem A. Petrov,
†
†
†,‡
§
Alexander A. Korlyukov, Lidia S. Shul’pina, Victor N. Khrustalev,
Pavel V. Dorovatovskii,
†
†
†,‡
†
Anna V. Vologzhanina, Ulyana S. Tsareva, Igor E. Golub,
Elena S. Shubina, and Georgiy B. Shul’pin*
Ekaterina S. Gulyaeva,
†
,□,△
†
Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Str., 28, 119991 Moscow, Russia
People’s Friendship University of Russia, Miklukho-Maklay Str., 6, 117198 Moscow, Russia
‡
∥
§
Pirogov Russian National Research Medical University, Ostrovitianov str., 1, 117997 Moscow, Russia
National Research Center “Kurchatov Institute”, Akademika Kurchatova pl., 1, 123182 Moscow, Russia
□
Semenov Institute of Chemical Physics, Russian Academy of Sciences, ulitsa Kosygina, dom 4, Moscow 119991, Russia
△Plekhanov Russian University of Economics, Stremyannyi pereulok, dom 36, Moscow 117997, Russia
S Supporting Information
*
ABSTRACT: Three types of unusual cagelike copper(II)
methylsilsesquioxanes, namely, nona- [(MeSiO ) (CuO) ]
1
.5 18
9
1
, hexa- [(MeSiO1.5)10(HO0.5) (CuO) (C H N ) -
2 6 12 8 2 2
(
MeSiO ) (HO ) (CH COO ) (CuO) (C H N ) ]
1.5 10 0.5 1.33 3 0.5 0.67 6 12 8 2 2
2
, [(MeSiO ) (CuO) (MeO ) (C H N ) ] 3, and trinu-
1.5 10 6 0.5 2 10 8 2 2
clear [(MeSiO ) (CuO) (C H N ) ] 4, were obtained in
1.5 8
3
10
8
2 2
4
4%, 27%, 20%, and 16% yields, respectively. Nuclearity and
structural fashion of products was controlled by the choice of
solvent system and ligand, specifically assisting the assembling
of cage. Structures of 1−4 were determined by single-crystal X-
ray diffraction analysis. Compounds 1 and 4 are the first cage
metallasilsesquioxanes, containing nine and three Cu ions,
respectively. Product 1 is the first observation of nonanuclear
metallasilsesquioxane ever. Unique architecture of 4 represents early unknown type of molecular geometry, based on two
condensed pentamembered siloxane cycles. Topological analysis of metal clusters in products 1−4 is provided. Complex 1
efficiently catalyzes oxidation of alcohols with tert-butylhydroperoxide TBHP to ketones or alkanes with H O to alkyl
2
2
hydroperoxides in acetonitrile.
INTRODUCTION
cyclodextrins is hydrophilic, while the interior cavity is
■
4
hydrophobic. This allows an encapsulation of large organic
An attractive family of cagelike metallasilsesquioxanes (CLMSs)
5
1
2
molecules (e.g., vitamins A and D ) into the inner space of
is known by its members’ unusual structural, catalytic, and
3
cyclodextrins (Figure 2, left). In turn, prismatic CLMSs possess
hydrophobic outer surface due to the presence of organic
substituents at the silicon atoms, while the inner space of cage
is hydrophilic. As a result, several polar molecules or anions
magnetic (spin-glass) properties. These compounds include a
group of objects possessing the following common features: (1)
they are built from monosubstituted organosilicon units RSi≡;
2) such CLMSs represent simultaneously siloxane Si−O−Si
(
−
−
(
H O, Cl , HO ) were observed being encapsulated into the
and metallasiloxane Si−OM fragments; (3) the atomic ratio Si/
M in them is comparatively high (Si/M ≥ 2, where M is
polyvalent metal). The most common molecular architecture of
these CLMSs is a hollow hexagonal prism (Figure 1) formed by
three parallel layersone metal oxide and two siloxane
2
1i
inner void of prismatic CLMSs (Figure 2, right). This feature
could be compared to the intriguing ability of polyhedral
oligosilsesquioxanes to encapsulate halide (fluoride anion).
6
The size of potential “guests” of both cyclodextrin and
metallasilsesquioxane cavities is obviously limited by the cavity
1i
(
usually, phenylsilsesquioxane) ones.
Interestingly, the properties of such prismatic CLMSs are
perfectly opposite to those observed for the well-studied
cyclodextrins. It is known that the outer surface of the
Received: January 9, 2017
©
XXXX American Chemical Society
A
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
formation control so to regulate a size of cage moiety. Herein
we present our results concerning the synthesis of Cu(II)
methylsilsesquioxanes that allow the tuning of both nuclearity
and cage shape.
Also, mono- and polynuclear copper complexes are known to
7
catalyze efficiently oxidations of alcohols with TBHP and
7a,8
alkanes with hydrogen peroxides. We are presenting here the
first instance of Cu(II) methylsilsesquioxane application as
catalyst under the same reaction conditions.
EXPERIMENTAL SECTION
■
Materials. MeSi(OMe) was purchased from ABCR and used as
3
received. All solvents (Acros) were used without specific purification.
Figure 1. Simplified view of prismatic CLMS’ structural organization.
Synthesis. Complex 1. Three grams (0.022 mol) of MeSi(OMe) in
0 mL of ethanol and 0.79 g (0.044 mol) of water were stirred for 30
3
5
min. Then 0.90 g (0.025 mol) of NaOH was added, and the resulting
white-colored mixture was heated to reflux for 2 h. Afterward the
solution was cooled to room temperature, and 1.35 g (0.01 mol) of
diameter. It is worth mentioning that this parameter in case of
cyclodextrins varies in the range of 5.2−8.4 Å, while usual
CLMS’ cavity diameter range is more narrow (3.4−3.6 Å). In
the line of investigation of CLMSs as potential molecular
containers, it would be desirable to find an opportunity of their
CuCl in 50 mL of dimethyl sulfoxide (DMSO) was added at once.
2
The solution was heated at reflux for 3 h, then cooled to room
temperature and left under intensive stirring for additional 12 h. The
Figure 2. General view of cyclodextrin (left) and prismatic cage metallasilsesquioxane (right) structures (front and side views; hydrogen atoms are
omitted for clarity).
B
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Scheme 1. Proposed Pathway of CLMS Aggregation through the Coordination with Pyrazine
resulting mixture was filtered from insoluble precipitate. Crystallization
of filtrate gave in 3−4 weeks crystal product. Several crystals were used
X-ray Crystallographic Data Collection and Refinement of the
Structures. The data sets for 2 and 3 were collected with Bruker APEX
DUO diffractometer. The structures were solved by charge flipping
method and refined in anisotropic approximation. Hydrogen atoms
were calculated from geometrical point of view, except for hydrogen
atom of solvated methanol molecule that was located from difference
Fourier maps. Hydrogen atoms were refined with restraints applied for
their displacement parameters and C−H (O−H) bond length. The
structure of complex 2 contains two independent molecules (see
below Discussion Section for details) with the terminal ligands,
coordinated to copper ions, being disordered. We interpreted the
disorder as a superposition of two-thirds hydroxyl and one-third
acetate ligands.
for single-crystal X-ray diffraction analysis (1·8DMSO·H O, see details
2
below). Anal. Calcd for [(MeSiO ) (CuO) ], Cu, 29.72; Si, 26.27.
1.5 18
9
Found (for vacuum-dried sample): Cu, 29.59; Si, 26.04%. Yield 0.94 g
44%).
Complex 2. Nine-tenths of a gram (0.005 mol) of 1,10-
(
phenanthroline was added at once to solution, produced as described
in the section dedicated to the synthesis of 1 (prior to crystallization
stage). Mixture was stirred for 4 h at room temperature. Then it was
left in a cool place (15 °C) for crystallization. After one week the
formation of crystalline material was observed. Several crystals were
used for single-crystal X-ray diffraction analysis (2·4DMSO·4H O, see
2
details below). Anal. Calcd for [(MeSiO1.5)10(HO )2(CuO)
0.5
6
Unfortunately, it was impossible to collect the reflection intensities
for single crystals of 1 and 4 using the laboratory equipment (even in
the case of microfocus copper tube). The quality of all collected data
sets was unsatisfactory due to strong symmetry-induced disorder of
solvated and coordinated molecules (as consequence the intensity of
diffraction was very weak with almost absent high-angle reflections).
To overcome the limitation of laboratory equipment we used protein
station of Kurchatov Centre for Synchrotron radiation. The results
were much better than those obtained with laboratory diffractometer.
We succeeded to localize all non-hydrogen atoms and refine their
position using a number of restraints. The positions of hydrogen
atoms were calculated from geometrical point of view and refined with
restraints applied for C−H bonds and equivalent displacement
parameters. All calculations were performed using SHELX program
(
(
C1 2 H N ) (MeSiO
)1 0 (HO0 . 5 )1 . 3 3 (CH COO
)0 . 6 7
8
2
2
1 . 5
3 0 . 5
CuO) (C H N ) ], Cu, 24.74; N, 3.64; Si, 18.23. Found (for
6
12
8
2 2
vacuum-dried sample): Cu, 24.31; N, 3.52; Si, 18.01%. Yield 0.69 g
27%).
Complex 3. Seventy-eight hundredths of a gram (0.005 mol) of
,2′-bipyridine was added at once to solution, produced as described in
(
2
the section dedicated to the synthesis of 1 (prior to crystallization
stage, 45 mL of methanol/ethanol (1:1) mixture was used instead of
DMSO). Mixture was stirred for 4 h at room temperature, and then it
was left in a cool place (15 °C) for crystallization. After one week the
formation of crystalline material was observed. Several crystals were
used for single-crystal X-ray diffraction analysis (3·2MeOH, see details
below). Anal. Calcd for [(MeSiO ) (CuO) (MeO ) (C H N ) ],
1.5 10
6
0.5
2
10
8
2 2
Cu, 25.30; N, 3.72; Si, 18.64. Found (for vacuum-dried sample): Cu,
2
9
10
suite and OLEX2 program. Additional crystallographic information
is available in the Supporting Information.
4.74; N, 3.64; Si, 18.23%. Yield 0.50 g (20%).
Complex 4. 2,2′-Bipyridine (1.57 g, 0.010 mol) was added at once
Oxidation of Alcohols. The reactions of alcohols were performed in
air in thermostated Pyrex cylindrical vessels with vigorous stirring and
using MeCN as solvent. The substrate was then added, and the
reaction started when the oxidant was introduced in one portion.
Concentrations of products obtained in the oxidation of 1-phenyl-
to solution, produced as described in the section concerning the
synthesis of 1 (prior to crystallization stage, 45 mL of methanol/
ethanol (1:1) mixture was used instead of DMSO). Mixture was
stirred for 4 h at room temperature, and then it was left in a cool place
(
15 °C) for crystallization. After one week the formation of crystalline
1
material was observed. Several crystals were used for single-crystal X-
ray diffraction analysis (4·3EtOH, see details below). Anal. Calcd for
ethanol after certain time intervals were measured using H NMR
method (solutions in acetone-d ; “Bruker AMX-400” instrument, 400
6
[
(MeSiO ) (CuO) (C H N ) ], Cu, 17.52; N, 5.15; Si, 20.65.
MHz). In the oxidation of cyclohexanol, concentrations of the
substrate and products were measured by chromatography as
described below for the oxidation of cyclohexane.
1.5
8
3
10
8
2 2
Found (for vacuum-dried sample): Cu, 17.40; N, 5.02; Si, 20.23%.
Yield 0.58 g (16%).
C
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Oxidation of Alkanes. This reaction was performed analogously.
Catalyst 1 and the cocatalyst (nitric acid) were introduced into the
reaction mixture in the form of stock solutions in acetonitrile. 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
stage and (ii) as a ligand during the crystallization stage. The
drawback of this choice is a well-known ambidentate behavior
of DMSO as ligand. DMSO might perform as a pure bridging
13
unit (with involvement of both sulfur and oxygen atoms (Chart
1
A)), or it could play a role of solvating ligand (when only
2
2
oxygen centers of DMSO are involved into coordination (Chart
1B)).
temperatures may be explosive. The reactions after addition of
nitromethane as a standard compound were analyzed by gas
chromatography (GC). Instrument LKhM-80−6 was used (columns
2
m with 5% Carbowax 1500 on 0.25−0.315 mm Inerton AW-HMDS;
Chart 1. Simplified View of Dimethyl Sulfoxide,
carrier gas argon) for measuring concentrations of cyclohexanol and
13a
13b
Coordinating Two Rh or Ag Atoms
cyclohexanone. The samples of reaction solutions were in some cases
analyzed twice: before and also after their treatment with PPh . This
3
method (an excess of solid triphenylphosphine is added to the samples
11
1
0−15 min before the GC analysis) proposed by one of us allows us
to detect alkyl hydroperoxides and to measure also the real
concentrations of all three products (alkyl hydroperoxide, alcohol,
and aldehyde or ketone) present in the reaction solution, because
usually alkyl hydroperoxides are decomposed in the gas chromato-
graph to produce mainly the corresponding alcohol and ketone. In our
kinetic studies described below, we measured concentrations of
cyclohexanone and cyclohexanol only after reduction of the reaction
We performed the following interaction based on in situ
transformation of methyltrimethoxysilane into reactive sodium-
containing intermediate species, followed by exchange reaction
mixture with PPh , which gives precisely concentration of a sum of the
3
oxygenates. This total concentration is used for measuring the reaction
with CuCl in DMSO media (Scheme 2, product 1).
2
rates W . Blank experiments with cyclohexane showed that in the
0
absence of catalyst 1 no products were formed.
a
Scheme 2. General Scheme of Synthesis of CLMSs 1−4
RESULTS AND DISCUSSION
■
To exclude the influence of bulky surrounding of silicon atoms
on the process of Cu(II)-CLMS self-assembly, methyltrime-
thoxysilane MeSi(OMe) was chosen as initial reagent for the
3
synthesis. It should be mentioned that examples for the
synthesis of copper(II) methylsilsesquioxanes are rather
1
2
limited. Interestingly, some of these results, namely, refs
2a and b, described the isolation of prismatic CLMSs of high
1
1
2a,b
12b
(octa-
and deca- ) nuclearity. Unfortunately, detailed
a
For compounds 3 and 4: parallel syntheses were performed in
condition of different loadings of 2,2′-bipy (y > x).
analysis of CLMSs, described in ref 12b, is impossible due to
the absence of corresponding structural information (CIF files)
in CCDC. In turn, octanuclear compound [(MeSiO )
1.5 8
12a
(
CuO) (DMF) ]·C H N
attracts attention due to unusual
The reaction gave nonacopper(II) cage silsesquioxane
8
9
4
4
2
encapsulation of pyrazine molecule by inner void of this
metallasilsesquioxane. The observed phenomenon seems to be
useful for the discussion of prismatic CLMS growth
mechanism. Probably, an inclusion of coordinative ligands
[(MeSiO ) (CuO) ] 1 in 44% yield. This compound is the
1.5 18
9
first example of prismatic CLMS, containing an odd number of
copper ions. More than that, product 1 is the first observation
of nonanuclear metallasilsesquioxane ever. Its structure (cage
metallasilsesquioxane, coordinated by DMSO and water
molecules) was established by single-crystal X-ray diffraction
analysis (Figure 3, see below for details).
(
e.g., pyrazine) is a “metallasilsesquioxane expanding factor”,
which provokes aggregation of higher clusters instead of
traditional hexanuclear ones. In this line of thought, a pyrazine
molecule could coordinate two metallasiloxane rings (Scheme
1i
The main feature of the compound is the DMSO
encapsulation fashion. It was revealed that the DMSO moiety
is contacting two neighboring copper ions by both its oxygen
and sulfur centers (alike principle shown on Chart 1A).
Interesting that such coordination provoked a specific mutual
orientation of two neighboring metallasilsesquioxane fragments,
located at 138.2° angle to each other (in terms of Si−Si−Si
angle value, see Scheme 2A).This value closely corresponds to
the one known for a regular nonagon (140°). Thus, formation
of nonanuclear product 1 is quite logical (Scheme 3B).
On the second stage of the study we were interested in the
investigation of the competition between several ligands that
are capable to participate in CLMS assembling. To evaluate
this, we performed reaction of copper(II)methylsilsesquioxane
synthesis in condition of simultaneous presence of two different
ligands (DMSO and 1,10-phenanthroline) in reaction mixture
(Scheme 2, product 2). It was revealed that such synthetic
procedure leads to the formation of the hexanuclear product
1A). The distance between two opposite Cu ions (7.96 Å)
determines the size of the future CLMS prism. This prediction
was based on comparing the magnitude of the Si−Si−Si angle
(estimated for three neighboring silicon atoms of the siloxane
ring). Noteworthy that structural synthone, including two
adjacent metallasiloxane fragments (Scheme 1B), is charac-
terized by Si−Si−Si angle equal to 124.7°. This value is close to
one observed for interior angle for a regular hexagon (120°).
One could conclude that only the presence of an additional
coordinating ligand (pyrazine) allowed to aggregate octanuclear
CLMS instead of expected hexanuclear one (Scheme 1C).
Being interested in further study of features of methyl-
substituted CLMSs self-assembling, we decided to see if other
types of bridging ligands could provoke similar “expanding”
effect. First of all, the role of the ligand DMSO was investigated.
The advantage of such choice is a nature of DMSOthis
compound could serve (i) as a medium during the synthesis
D
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 3. Molecular structure of 1 (single-crystal X-ray diffraction analysis). Color code: Si−yellow, O−red, C−gray, Cu−green, S−light yellow.
Scheme 3. Proposed Pathway of CLMS 1 Aggregation through the Coordination with DMSO
[
(
(MeSiO1.5)10(HO0.5) (CuO) (C H N ) (MeSiO ) -
14. One could observe that compound 2 is an unusual instance
of a solid solution of two types of complexes. The first type of
them characterizes by participation of hydroxyl in coordination
of copper ion. In turn, the second type demonstrates
unprecedented assistance of acetoxy group in the same
coordination site. It should be said that presence of such
fragment could not be explained by formal logic of reaction
mechanism, and thus some additional processes should be
taken into consideration. We could suggest that acetoxy group
formation may be due to an oxidation of some ethanol
molecules by atmosphere oxygen, catalyzed by copper ions. As
some of us have reported on several instances of Cu-CLMS
2
6
12
8
2
2
1.5 10
HO ) (CH COO ) (CuO) (C H N ) ] 2 in 27%
0
.5 1.33
3
0.5 0.67
6
12
8
2 2
yield. Its structure (cagelike compound, coordinated by
DMSO and water molecules) was established by single-crystal
X-ray diffraction analysis (Figure 4, see below for details). This
compound is the first example of a “CLMS−phenanthroline”
complex.
The most attractive feature of compound 2 is the fashion of
phenanthroline coordination to the cage metallasilsesquioxane
fragment. Two phenanthroline molecules coordinate two
opposite copper ions, provoking “withdrawing” of two copper
ions from prismatic structure. Noteworthy, a similar phenom-
enon was observed for phenylsubstituted Cu(II) CLMS during
15
activity in C−H compounds oxidation, this explanation may
be evaluated as adequate. One of the possible solutions how to
prove an influence of atmosphere oxygen on this process is to
14
its complexation to 2,2′-bipyridine. Product 2 possesses
several attractive features in comparison to compound from ref
E
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 4. Molecular structure of 2 (single-crystal X-ray diffraction analysis). Color code: Si−yellow, O−red, C−gray, Cu−green, N−blue. Solvating
molecules of DMSO and water are omitted for clarity.
perform the same synthesis in the inert conditions.
Unfortunately, we succeed in isolation of the single crystals
of the “inert” product only after the replacement of original
(
(
DMSO/ethanol) solvates by the dioxane/methanol mixture
see Supporting Information for details). This prevents a
correct comparison of two products; nevertheless, it should be
said that “inert” dioxane/methanol complex, being quite similar
to compound 2, contains no structural components, pointing to
any oxidation.
It is interesting to compare differences between prismatic
cage components of products 1 and 2. Both structures contain
cyclic siloxane ligands [(MeSi(O)O)] (n = 8 for 1, n = 5 for 2)
n
and metal oxide layer. Noteworthy that instead of copper-
containing cycle in 1, one could observe specific structural
rearrangement in case of 2, giving two almost linear copper-
containing trimeric fragments (see structural and Topological
Analysis Section below).
Figure 5. Molecular structure of 3 (single-crystal X-ray diffraction
analysis). Color code: Si−yellow, O−red, C−gray, Cu−green, N−blue.
Solvating molecules of methanol are omitted for clarity.
condensed pentamembered cycles (Figure 6, bottom). We
could compare this feature only to Cu Na -silsesquioxane
In further study, we performed modified synthesis of methyl-
CLMSs, excluding presence of DMSO, and evaluating an
influence of nitrogen-containing ligand only. It was shown that
the process of assembly of complexes of copper(II)
silsesquioxane with 2,2′-bipyridine is a ratio-dependent one.
2
2
complex, presented by some of us in ref 15a, which contains
condensed ligand formed by one tetra- and two pentam-
embered cycles. Symptomatically, three copper centers of 4 lay
in almost linear trimeric order, similarly to compounds 2 and 3
(see below structural and Topological Analysis section). The
coordination polyhedra of the two terminal copper atoms
correspond to the distorted square pyramid, while the central
copper atom adopts planar square coordination.
While molar ratio CuCl /bipy was equal to 2/1 (as in the case
2
of synthesis of 2), the formation of the hexanuclear compound
was observed (Scheme 2, product 3). In turn, the higher
loading of ligand (CuCl /bipy = 1/1) provoked the formation
2
of trinuclear compound (Scheme 2, product 4). The structure
of complex 3 (Figure 5) is similar to that of compound 2. The
difference between them is a different principle of additional
coordination of Cu ions, realized in case of 3 by methoxy
groups. Evidently these methoxy groups originate from initial
Solid-State Structures. The central copper−oxygen
Cu O framework of 1 has a tiara-like structure (Figure 7)
9
18
with the intrinsic C (m) symmetry that is retained within the
s
crystal structure. Each of the oxygen atoms of this fragment is
μ -bridging to two copper atoms, and thus all copper atoms
2
reagent, MeSi(OMe) . According to Cambridge Structural
adopt a tetracoordinated square-planar environment. Further
the copper atoms attach one additional solvate molecule
attaining the preferable [4 + 1] square-pyramidal environment.
Remarkably, the coordination geometry of the copper atoms in
1 is significantly different. The five copper atoms coordinate a
DMSO solvate molecule via the oxygen atom, with the capped
oxygen atom looking outward from the cage (Figure 7). The
three copper atoms coordinate the internal DMSO solvate
molecule (two of them through the bridged oxygen atom and
3
Database (CSD), compound 3 is the first observation of olato
groups coordinated to metallasilsesquioxane framework.
In turn, structure of 4 is an unprecedented one. First of all,
compound 4, along with complex 1, is the first instance of odd-
numbered copper silsesquioxane cluster. Also, 4 represents a
unique for CLMS type of molecular geometry (Figure 6, top).
This type of geometry is distinguished by the presence of
nontypical octamembered silsesquioxane ligand, formed by two
F
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
opposite atoms of copper (i.e., diameter of inner cavity of cage
framework) is equal to 8.229 Å. The bonds between copper
atoms and solvating molecules of dimethyl sulfoxide are varied
in wide range (1.91−2.30, mean value is 2.15(2) Å).
Discussing other products, we would like to emphasize that
peculiarities of structures 2−4 are no doubt explained mostly
by the presence of N-containing ligands. Namely, the flattening
of copper silsesquioxane framework in 2 and 3 (in comparison
to cylindrical geometry of 1), evidently provoked by assistance
of N-containing ligands. This led to appearance of weak Cu···O
coordination between copper atom and opposite oxygen atom
of siloxanolate ligand (the Cu2···O7 distance in 3 is equal to
2
.464 Å). Interesting that this distance varies is not the same for
two different cage components of 2. In case of acetoxy-
containing compound the Cu3A···O5A distance is equal to
2
.486 Å. In case of hydroxy-containing compound the Cu3···
O1 distance is equal to 2.512 Å.
Another consequence of the coordination with N-ligands is
the increase of shortest Cu···Cu intra-atomic distances in
hexacopper cage skeletons of 2 and 3 in comparison to
hexacopper silsesquioxanes of cylindric shape. Indeed, the
average Cu···Cu distance in case of 2 is equal to 3.122 Å (in
case of 3, 3.090 Å), while the longest Cu···Cu contact for
hexacopper cylinder CLMSs (presented by some of us in ref
15d) is 2.863 Å. Most of the Cu−O bonds in 2 and 3 are very
similar to those in hexacopper silsesquioxanes from ref 14d,
except for Cu2−O1 distance in 2 (2.239 Å) and Cu3−O7
distance in 3 (2.196 Å).
In turn, the most prominent feature of compound 4, in
addition to those mentioned above, is different coordination
environment of copper ions. While coordination polyhedra of
two terminal copper atoms correspond to distorted square
pyramid, the central copper atom Cu1 adopts planar-square
coordination. Cu−Cu distance in 4 is equal to 2.997 Å, and
Cu−O distances vary in the range of 1.905−2.186 Å.
Figure 6. (top) The molecular structure of 4 (single-crystal X-ray
diffraction analysis). Solvating molecules of ethanol are omitted for
clarity. (bottom) Silsesquioxane ligand from 4. Color code: Si−yellow,
O−red, C−gray, Cu−green, N−blue.
the third one via the sulfur atom). Finally, the ninth copper
atom coordinates a water solvate molecule that is looking
outward from the cage (Figure 7). It is important to point out
that the copper atom additionally coordinating the water
molecule is disposed between the copper atoms that are
connected to the internal DMSO molecule. This construction
is apparently determined by the mutual arrangement of
neighboring Cu(II)-silsesquioxane molecules that form a crystal
packing by the gear-wheel mechanism (Figure 7). Con-
sequently, the crystal packing observed in the crystal of 1
confirms the template method of synthesis of 1.
Topological Analysis. To reveal the effect of the
silsesquioxane ring nuclearity on disposition of CLMSs,
topologies of metal clusters should be compared. Simplification
of the molecular graph to obtain the graph of Cu-containing
skeleton keeping the cluster connectivity was performed with
Mean Cu···Cu and Cu−O distances with siloxanolate ligands
in 1 are equal to 2.869(5) and 1.935(9), while corresponding
ranges of variation are 2.856−2.932 and 1.909−1.975 Å. The
Cu−S coordination bond is 3.412(7) Å. The distance between
16
the ToposPro package. The enlargement of the ring is
accompanied by significant reorganization of connections
Figure 7. Arrangement of two neighboring Cu(II)-silsesquioxane molecules in the crystal of 1 using the gear-wheel mechanism.
G
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 8. Cu-containing clusters connected by bridge atoms in (a) CLMS 1, (b) CLMSs 2 and 3, and (c) CLMS 4 and the graphs of corresponding
clusters connectivity (d−f).
between metal atoms. CLMSs of the [(RSiO ) (CuO) ]
1
.5 12
6
composition form the 2M6-1 and 5M6-1 clusters in the absence
and the presence of the “enclosed” μ -Cl anions, respective-
6
15d
12a,b
1b
ly. Larger (RSiO )
and (RSiO )
rings were found
1
.5 8
1.5 10
in the structures of [(RSiO ) (CuO) ] and [(RSiO ) -
1
.5 16
8
1.5 20
(
CuO) ] complexes, while CLMS 1 is the first representative
10
of the [(RSiO ) (CuO) ] family. Despite the presence of the
1.5 18
9
encapsulated moieties, all octa-, nona-, and decacopper-
containing CLMSs are characterized with the 2M8-1, 2M9-1,
and 2M10-1 topologies, respectively (see the 2M9-1 topology
on Figure 8 left).
In turn, copper atoms in CLMSs 2 and 3 form the 2,3,4M6-1
trinodal discrete cluster (Figure 8 middle). The 2,3,4M6-1
topology was met for tens of metal-containing compounds
1
7
from the CSD, mainly containing bridge bidentate ligands
acetylacetonates, carboxylates, oximates). Among them five
CLMSs were found (refcodes in the CSD are {LAZBUK},
LAZBUK01}, {OBIDAG}, {OBIDEK}, and {OBIFOW});
and all of them contain (RSiO ) rings.
(
{
Figure 9. Accumulation of acetophenone with time in the oxidation of
1-phenylethanol (initial concentration 0.33 M) with TBHP (70%
aqueous; initial concentration 1.17 M) catalyzed by compound 1 (5 ×
1
.5 5
CLMS 4 belongs to the 1,2M3-1 binodal clusters (Figure 8
right). Formation of metal clusters connected by cagelike
metallasilsesquioxanes with mono- and biconnected metal
atoms is more typical for cubane silsesquioxanes. Among
−4
10 M) in the absence and in the presence of HNO (0.05 M).
3
Solvent was acetonitrile (total volume of the reaction solution was 5
mL); 50 °C.
18
them representatives of the same 1,2M3-1 and closely related
1
9
1
,2M4-1 clusters can be found. Taking the shape of
compound 1 on initial concentrations of catalyst 1 are
presented in Figure 10. Aliphatic alcohols are a bit less reactive
in comparison with 1-phenylethanol. Thus, the oxidation of
cyclohexanol (0.38. M; [compound 1] = 5 × 10− M; in the
methylsilsesquioxane moiety in 4 into account it is not
surprising that copper atoms also form the cluster more typical
for cubanes, than for prismatic CLMSs.
4
As a conclusion, it could be said that for prismatic copper
absence of HNO ; 50 °C) gave cyclohexanone in 77% after 24
3
silsesquioxanes [(RSiO ) (CuO) ] (n = 6−10) copper atoms
1
.5 2n
n
h (see also Figure S2). Compound 1 is among the most
efficient catalysts for the oxidation of secondary alcohols to
ketones (the yields were 96% for 1-phenylethanol and 77% for
tend to act as uninodal two-connected nodes upon cluster
formation, although for [(RSiO ) rings connected with six
1
.5 5
19e
copper atoms steric factors force distortion of hexacopper-
containing clusters, rapprochement of copper atoms followed
by appearance of additional bonds and 3- and 4-connected
nodes. Thus, steric factors from a silsesquioxane anion play a
key role upon mutual disposition of copper atoms in a cluster.
Catalyzed Oxidation of Alcohols and Alkanes with
Peroxides. Alcohols are efficiently oxidized with TBHP in
acetonitrile when complex 1 is used as a catalyst (Figures 9, 10,
S1, and S2). Note that addition of nitric acid leads to the
retardation of the reaction (Figure 9).
cyclohexanol). The following literature data can be cited here
for comparison (the MW-assisted oxidation of cyclohexanol
and 1-phenylethanol with TBHP catalyzed by Cu complex gave
cyclohexanone and acetophenone in 85 and 55% yields,
correspondingly).
We also found that alkanes can be oxidized in acetonitrile
solution to the corresponding alkyl hydroperoxides by
hydrogen peroxide in air in the presence of catalytic amounts
of complex 1 and nitric acid. The reaction proceeds in
acetonitrile solution under mild conditions (typically at 50 °C).
The alkyl hydroperoxide is relatively stable in the solution, and
Dependences of acetophenone accumulation rate in the
oxidation of 1-phenylethanol with TBHP catalyzed by
can be easily reduced by PPh to the corresponding alcohol.
3
H
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Figure 10. Dependences of acetophenone accumulation rate in the
oxidation of 1-phenylethanol with TBHP (70% aqueous) catalyzed by
compound 1 on initial concentrations of catalyst 1 (curve 1), 1-
phenylethanol (curve 2), and TBHP (curve 3). Solvent was
acetonitrile (total volume of the reaction solution was 5 mL); 50 °C.
Chromatogram obtained after reduction with PPh is drastically
3
distinguished from the chromatogram for unreduced sample
Figure 11. Oxidation of cyclohexane (0.23 M) with H O (50%, 2M)
2
2
(
compare top and bottom graphs in Figure 11). This difference
−4
catalyzed by complex 1 (5 × 10 M) in the presence of HNO (0.05
3
unambiguously indicates that cyclohexyl hydroperoxide is
formed in the process.
M). Solvent was acetonitrile (total volume of the reaction solution was
5 mL); 50 °C. Concentrations of cyclohexanol (curves 1) and
cyclohexanone (curves 2) were measured both before and after
7a,11
Using higher initial concentration of cyclohexane (0.46 M)
we were able to obtain after 5 h 0.084 M of cyclohexanol and
reduction with PPh . Curves 1a and 2a correspond to concentrations
3
of cyclohexanol and cyclohexanone, respectively, obtained in the
reaction in the absence of HNO3.
0
.008 M of cyclohexanone after reduction with PPh . Thus,
3
total yield attained 20%, and TON was 184. Comparable values
have been reported previously for the copper-catalyzed
7a,8b,20a,b
transformations of alkanes into alkyl hydroperoxides.
described in this work is its high efficiency. Thus, the
Regioselectivity parameter in n-heptane oxidation was C(1)/
C(2)/C(3)/C(4) = 1.0:6.0:6.5:6.0. Bond selectivity in
oxidation of methycyclohexane was 1°:2°:3° = 1:12:30. In the
oxidation of cis-1,2-dimethylcyclohexane the ratio of tertiary
alcohols with mutual configuration of methyl groups trans/cis
was 0.7. All these data allow us to assume that the reaction
proceeds with intermediate formation of hydroxyl radicals that
attack C−H bonds of a substrate [7, 11, 20]. The authors
realize that complex 1 plays a role of a precatalyst in the
oxidations with peroxides. In the course of the reaction
compound 1 is modified to afford a catalytically active species.
We can assume that under the action of an acid and H O some
cyclohexane oxidation with H
gave oxygenates in 18% yield after 1 h (Figure 11). Under the
same conditions, the oxidation catalyzed by Cu(NO afforded
2 2 3
O in the presence of HNO
)
3 2
oxygenates only in 3.5% yield, and we may conclude that
complex 1 is undoubtedly the more efficient catalyst in
comparison with simple salt Cu(NO ) .
3 2
CONCLUSIONS
■
Tuning of synthesis (varying of nature of solvents and/or N-
ligands) of Cu(II)-methylsilsesquioxanes gave three types of
unusual cagelike complexes, namely, nona- [(MeSiO ) -
1
.5 18
(CuO) ] 1, hexa- [(MeSiO ) (HO ) (CuO) (C H N ) -
2
2
9
1.5 10
0.5 2
6
12
8
2 2
bonds in the precatalyst cage are ruptured, and substrate and
oxidant can easily approach the copper-containing reaction
center. The catalyst is involved into a partial destruction, and
the activity of the solid obtained by evaporation after the first
run of the reaction is ca. 2 times lower than activity of “fresh”
catalyst. Note that it is difficult to follow the catalytic process
using spectra of the catalytically active species, because
(MeSiO ) (HO ) (CH COO ) (CuO) (C H N ) ]
1.5 10 0.5 1.33 3 0.5 0.67 6 12 8 2 2
2, [(MeSiO ) (CuO) (MeO ) (C H N ) ] 3, and trinu-
1.5 10
6
0.5 2
10
8
2 2
clear [(MeSiO ) (CuO) (C H N ) ] 4. Compounds 1 and 4
1.5 8
3
10
8
2 2
are the first cage metallasilsesquioxanes, containing nine and
three copper(II) ions, respectively. Moreover, cage complex 1 is
the first observation of nonanuclear metallasilsesquioxane ever.
Because of a significant size of its cavity (inner diameter >8 Å),
this particular architecture seems to have potential as a host
compound. We could suggest possible encapsulation of other
(except DMSO) molecules by this complex, for example,
acetone, acetonitrile, nitromethane, etc. Noteworthy is that
compound 1 catalyzes the homogeneous oxidation of either
−4
concentration of the active species is very low (1 × 10 to 1
−5
×
10 M), and many other compounds are present in the
reaction mixture. A detailed study of the nature of catalytically
active species will be a subject of new work with the help of
modern techniques. An advantage of the catalytic system
I
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
alcohols to ketones or alkanes to alkyl hydroperoxides. This
variety of molecular architectures, available from quite simple
starting reagents, points out to significant prospectives of this
synthetic route. Our team is going to investigate further this
promising reactivity to create new types of molecular topologies
and to study functional properties of these compounds, for
example, in catalysis of oxidative C−H compounds function-
alization.
Adv. Organomet. Chem. 2005, 53, 101−153. (f) Jutzi, P.; Lindemann,
H. M.; Nolte, J.-O.; Schneider, M. Synthesis, Structure, and Reactivity
of Novel Oligomeric Titanasiloxanes. In Silicon Chemistry: From the
Atom to Extended Systems; Jutzi, P., Schubert, U., Eds.; Wiley, 2007; pp
3
72−382. (g) Edelmann, F. T. Metallasilsesquioxanes. Synthetic and
Structural Studies. In Silicon Chemistry: From the Atom to Extended
Systems; Jutzi, P.; Schubert, U., Eds.; Wiley, 2007; pp 383−394.
(h) Ward, A. J.; Masters, A. F.; Maschmeyer, T. Metallasilsesquiox-
anes: Molecular Analogues of Heterogeneous Catalysts. Adv. Silicon
Sci. 2011, 3, 135−166. (i) Levitsky, M. M.; Bilyachenko, A. N. Modern
concepts and methods in the chemistry of polyhedral metallasiloxanes.
Coord. Chem. Rev. 2016, 306, 235−269.
(2) (a) Quadrelli, E. A.; Basset, J.-M. On silsesquioxanes’ accuracy as
molecular models for silica-grafted complexes in heterogeneous
catalysis. Coord. Chem. Rev. 2010, 254, 707−728. (b) Levitsky, M.
M.; Yalymov, A. I.; Kulakova, A. N.; Petrov, A. A.; Bilyachenko, A. N.
Cage-like metallsilsesquioxanes in catalysis: A review. J. Mol. Catal. A:
Chem. 2017, 426, 297−304. (c) Bilyachenko, A. N.; Yalymov, A. I.;
Shul’pina, L. S.; Mandelli, D.; Korlyukov, A. A.; Vologzhanina, A. V.;
Es’kova, M. A.; Shubina, E. S.; Levitsky, M. M.; Shul’pin, G. B. Novel
Cage-Like Hexanuclear Nickel(II) Silsesquioxane. Synthesis, Structure,
and Catalytic Activity in Oxidations with Peroxides. Molecules 2016,
ASSOCIATED CONTENT
Supporting Information
■
*
S
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.inorg-
chem.7b00061.
Crystallographic data for structures 1−4, catalytic studies
of 1, IR and computational studies, additional synthetic
procedures, X-ray crystallographic studies of 5 and 6
(
PDF)
X-ray crystallographic information (CIF)
X-ray crystallographic information (CIF)
X-ray crystallographic information (CIF)
X-ray crystallographic information (CIF)
X-ray crystallographic information (CIF)
X-ray crystallographic information (CIF)
2
1, 665. (d) Bilyachenko, A. N.; Yalymov, A. I.; Levitsky, M. M.;
Korlyukov, A. A.; Es'kova, M. A.; Long, J.; Larionova, J.; Guari, Y.;
Shul’pina, L. S.; Ikonnikov, N. S.; Trigub, A. L.; Zubavichus, Y. V.;
Golub, I. E.; Shubina, E. S.; Shul’pin, G. B. First cage-like pentanuclear
Co(II)-silsesquioxane. Dalton Trans. 2016, 45, 13663−13666.
(3) (a) Bilyachenko, A. N.; Yalymov, A. I.; Korlyukov, A. A.; Long, J.;
AUTHOR INFORMATION
Corresponding Authors
E-mail: bilyachenko@ineos.ac.ru. (A.B.N.)
E-mail: shulpin@chph.ras.ru. (G.B.S.)
ORCID
Alexey N. Bilyachenko: 0000-0003-3136-3675
Victor N. Khrustalev: 0000-0001-8806-2975
Anna V. Vologzhanina: 0000-0002-6228-303X
Igor E. Golub: 0000-0003-4142-454X
Larionova, J.; Guari, Y.; Zubavichus, Y. V.; Trigub, A. L.; Shubina, E.
S.; Eremenko, I. L.; Efimov, N. N.; Levitsky, M. M. Heterometallic
Na Co Phenylsilsesquioxane Exhibiting Slow Dynamic Behavior in its
■
6
3
*
Magnetization. Chem. - Eur. J. 2015, 21, 18563−18565. (b) Bilyachen-
ko, A. N.; Yalymov, A. I.; Korlyukov, A. A.; Long, J.; Larionova, J.;
Guari, Y.; Vologzhanina, A. V.; Es’kova, M. A.; Shubina, E. S.; Levitsky,
M. M. Unusual penta- and hexanuclear Ni(II)-based silsesquioxane
polynuclear complexes. Dalton Trans. 2016, 45, 7320−7327.
*
(c) Bilyachenko, A. N.; Levitsky, M. M.; Yalymov, A. I.; Korlyukov,
A. A.; Vologzhanina, A. V.; Kozlov, Yu. N.; Shul’pina, L. S.; Nesterov,
D. N.; Pombeiro, A. J. L.; Lamaty, F.; Bantreil, X.; Fetre, A.; Liu, D.;
Martinez; Long, J.; Larionova, J.; Guari, Y.; Trigub, A. L.; Zubavichus,
Y. V.; Golub, I. E.; Filippov, O. A.; Shubina, E. S.; Shul’pin, G. B. A
heterometallic (Fe6Na8) cage-like silsesquioxane: synthesis, structure,
spin glass behavior and high catalytic activity. RSC Adv. 2016, 6,
Notes
The authors declare no competing financial interest.
Crystallographic data for 1−4 was submitted to CSD (CCDC
Nos. 1509419−1509422) and can be obtained free of charge
using web request form https://www.ccdc.cam.ac.uk/
structures/?.
4
8165−48180.
4) Szejtli, J. Cyclodextrin Technology; Springer Science & Business
Media, 2013; Vol. 1.
(
(
(
5) Combs, G. F., Jr. The Vitamins; Academic Press, 2012.
6) (a) Lickiss, P. D.; Rataboul, F., Fully Condensed Polyhedral
ACKNOWLEDGMENTS
This work has been partially supported by the Russian
Foundation for Basic Research (Grant Nos. 17-03-00993 and
6-03-00254) and by the Ministry of Education and Science of
the Russian Federation (Agreement No. 02.a03.21.0008.
■
Oligosilsesquioxanes (POSS): From Synthesis to Application. In
Advances in Organometallic Chemistry; Anthony, F. H., Mark, J. F., Eds.;
Academic Press, 2008; Vol. 57, pp 1−116. (b) Taylor, P. G.;
Bassindale, A. R.; El Aziz, Y.; Pourny, M.; Stevenson, R.; Hursthouse,
M. B.; et al. Further studies of fluoride ion entrapment in
octasilsesquioxane cages; X-ray crystal structure studies and factors
that affect their formation. Dalton. Trans 2012, 41, 2048−2059. (c) El
Aziz, Y.; Bassindale, A. R.; Taylor, P. G.; Horton, P. N.; Stephenson, R.
A.; Hursthouse, M. B. Facile Synthesis of Novel Functionalized
Silsesquioxane Nanostructures Containing an Encapsulated Fluoride
Anion. Organometallics 2012, 31, 6032−6040.
1
REFERENCES
■
(
1) (a) Murugavel, R.; Voigt, A.; Walawalkar, M. G.; Roesky, H. W.
Hetero- and Metallasiloxanes Derived from Silanediols, Disilanols,
Silanetriols, and Trisilanols. Chem. Rev. 1996, 96, 2205−2236.
b) Lorenz, V.; Fischer, A.; Gießmann, S.; Gilje, J. W.; Gun’ko, Y.;
Jacob, K.; Edelmann, F. T. Disiloxanediolates and polyhedral
metallasilsesquioxanes of the early transition metals and f-elements.
Coord. Chem. Rev. 2000, 206−207, 321−368. (c) Hanssen, R. W. J. M.;
van Santen, R. A.; Abbenhuis, H. C. L. The Dynamic Status Quo of
Polyhedral Silsesquioxane Coordination Chemistry. Eur. J. Inorg.
Chem. 2004, 2004, 675−683. (d) Roesky, H. W.; Anantharaman, G.;
Chandrasekhar, V.; Jancik, V.; Singh, S. Control of Molecular
Topology and Metal Nuclearity in Multimetallic Assemblies: Designer
Metallosiloxanes Derived from Silanetriols. Chem. - Eur. J. 2004, 10,
(
(7) (a) Shul’pin, G. B. New Trends in Oxidative Functionalization of
Carbon−Hydrogen Bonds: A Review. Catalysts 2016, 6, 50. (b) Anbu,
S.; Paul, A.; Ribeiro, A. P. C.; Guedes da Silva, M. F.; Kuznetsov, M. L.;
Pombeiro, A. J. L. Biomolecular interaction, catecholase like activity
and alkane oxidation in ionic liquids of a phenylcarbohydrazone-based
monocopper(II) complex. Inorg. Chim. Acta 2016, 450, 426−436.
(c) Tabacaru, A.; Xhaferaj, N.; Martins, L. M. D. R. S.; Alegria, E. C. B.
̆ ̆
A.; Chay, R. S.; Giacobbe, C.; Domasevitch, K. V.; Pombeiro, A. J. L.;
Galli, S.; Pettinari, C. Metal Azolate/Carboxylate Frameworks as
4
106−4114. (e) Lorenz, V.; Edelmann, F. T. Metallasilsesquioxanes.
J
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
Article
Catalysts in Oxidative and C−C Coupling Reactions. Inorg. Chem.
Arkhipov, D. E.; Levitsky, M. M.; Shubina, E. S.; Shul’pin, G. B.
Solvent-controlled synthesis of tetranuclear cage-like copper(II)
silsesquioxanes. Remarkable features of the cage structures and their
high catalytic activity in oxidation of benzene and alcohols with
peroxides. Dalton Trans. 2014, 43, 872−882. (c) Vinogradov, M. M.;
Kozlov, Yu. N.; Bilyachenko, A. N.; Nesterov, D. S.; Shul’pina, L. S.;
Zubavichus, Y. V.; Pombeiro, A. J. L.; Levitsky, M. M.; Yalymov, A. I.;
Shul’pin, G. B. Alkane oxidation with peroxides catalyzed by cage-like
copper(II) silsesquioxanes. New J. Chem. 2015, 39, 187−199.
(d) Bilyachenko, A. N.; Dronova, M. S.; Yalymov, A. I.; Lamaty, F.;
Bantreil, X.; Martinez, J.; Bizet, C.; Shul’pina, L. S.; Korlyukov, A. A.;
Arkhipov, D. E.; Levitsky, M. M.; Shubina, E. S.; Kirillov, A. M.;
Shul’pin, G. B. Cage-like Copper(II) Silsesquioxanes: Transmetalation
Reactions and Structural, Quantum Chemical, and Catalytic Studies.
Chem. - Eur. J. 2015, 21, 8758−8770.
2
016, 55, 5804−5817.
(
8) (a) Shul’pin, G. B.; Gradinaru, J.; Kozlov, Y. N. Alkane
hydroperoxidation with hydroperoxides catalysed by copper com-
plexes. Org. Biomol. Chem. 2003, 1, 3611−3617. (b) Kirillova, M. V.;
Kozlov, Y. N.; Shul’pina, L. S.; Lyakin, O. Y.; Kirillov, A. M.; Talsi, E.
P.; Pombeiro, A. J. L.; Shul’pin, G. B. Remarkably fast oxidation of
alkanes by hydrogen peroxide catalyzed by a tetracopper(II)
triethanolaminate complex: Promoting effects of acid co-catalysts
and water, kinetic and mechanistic features. J. Catal. 2009, 268, 26−38.
(
9) Sheldrick, G. M. Crystal structure refinement with SHELXL. Acta
Crystallogr., Sect. C: Struct. Chem. 2015, C71, 3−8.
10) Dolomanov, O. V.; Bourhis, L. J.; Gildea, R. J.; Howard, J. A. K.;
(
Puschmann, H. OLEX2: a complete structure solution, refinement and
analysis program. J. Appl. Crystallogr. 2009, 42, 339−341.
(
11) (a) Shulpin, G. B.; Druzhinina, A. N. Hydroperoxidation of
(16) Blatov, V. A.; Shevchenko, A. P.; Proserpio, D. M. Applied
Topological Analysis of Crystal Structures with the Program Package
ToposPro. Cryst. Growth Des. 2014, 14, 3576−3586.
alkanes by atmospheric oxygen in the presence of hydroquinone or
quinone catalyzed by copper(II) acetate under visible light irradiation.
React. Kinet. Catal. Lett. 1992, 47, 207−211. (b) Shul’pin, G. B. Metal-
catalysed hydrocarbon oxygenations in solutions: the dramatic role of
additives: a review. J. Mol. Catal. A: Chem. 2002, 189, 39−66.
(17) (a) Groom, C. R.; Allen, F. H. The Cambridge Structural
Database in Retrospect and Prospect. Angew. Chem., Int. Ed. 2014, 53,
6
62−671. (b) Groom, C. R.; Bruno, I. J.; Lightfoot, M. P.; Ward, S. C.
The Cambridge Structural Database. Acta Crystallogr., Sect. B: Struct.
Sci., Cryst. Eng. Mater. 2016, B72, 171−179.
(
(
c) Shul’pin, G. B. Hydrocarbon Oxygenations with Peroxides
Catalyzed by Metal Compounds. Mini-Rev. Org. Chem. 2009, 6, 95−
04. (d) Shul’pin, G. B.; Kozlov, Y. N.; Shul’pina, L. S.; Kudinov, A. R.;
18) (a) Annand, J.; Aspinall, H. C.; Steiner, A. Novel Heterometallic
1
Lanthanide Silsesquioxane. Inorg. Chem. 1999, 38, 3941−3943.
Mandelli, D. Extremely Efficient Alkane Oxidation by a New Catalytic
(b) Quadrelli, E. A.; Davies, J. E.; Johnson, B. F. G.; Feeder, N.
Reagent H O /Os (CO) /Pyridine. Inorg. Chem. 2009, 48, 10480−
2
2
3
12
Molecular insight into the non-innocence of a silica-support: the
structure of a platinum−silsesquioxane derivative. Chem. Commun.
1
0482. (e) Shul’pin, G. B.; Kozlov, Y. N.; Shul’pina, L. S.; Petrovskiy,
P. V. Oxidation of alkanes and alcohols with hydrogen peroxide
2
̈
000, 1031−1032. (c) Ohde, C.; Limberg, C.; Stosser, R.; Demeshko,
catalyzed by complex Os (CO) (μ-H) . Appl. Organomet. Chem.
3
10
2
S. Oxovanadium(IV) Silsesquioxane Complexes. Inorg. Chem. 2010,
9, 2479−2485.
19) (a) Hanssen, R. W. J. M.; Meetsma, A.; van Santen, R. A.;
2
010, 24, 464−472. (f) Shul’pin, G. B. Selectivity enhancement in
4
(
functionalization of C−H bonds: A review. Org. Biomol. Chem. 2010,
8
, 4217−4228. (g) Shul’pin, G. B. C−H functionalization: thoroughly
Abbenhuis, H. C. L. Synthesis, Structural Characterization, and
Transmetalation Reactions of a Tetranuclear Magnesium Silsesquiox-
ane Complex. Inorg. Chem. 2001, 40, 4049−4052. (b) Lorenz, V.;
Blaurock, S.; Edelmann, F. T. The First Heterobimetallic Metal-
lasilsesquioxane Derivatives of Manganese. Z. Anorg. Allg. Chem. 2008,
tuning ligands at a metal ion, a chemist can greatly enhance catalyst’s
activity and selectivity. Dalton Trans. 2013, 42, 12794−12818.
(
h) Olivo, G.; Lanzalunga, O.; Di Stefano, S. Non-Heme Imine-
Based Iron Complexes as Catalysts for Oxidative Processes. Adv. Synth.
Catal. 2016, 358, 843−863.
6
34, 2819−2824. (c) Jones, M. D.; Keir, C. G.; Johnson, A. L.; Mahon,
(
12) (a) Zherlitsyna, L.; Auner, N.; Bolte, M. Bis(μ -cis-
6
M. F. Crystallographic characterisation of novel Zn(II) silsesquioxane
2
,4,6,8,10,12,14,16-octamethylcycloocta-siloxane-2,4,6,8,10,12,14,16-
complexes and their application as initiators for the production of
octolato)octakis[(dimethyl-formamide)copper(II)] dimethylforma-
mide solvate enclosing a pyrazine molecule. Acta Crystallogr., Sect. C:
Cryst. Struct. Commun. 2006, 62, 199−200. (b) Pashchenko, V.; Lang,
M.; Wolf, B.; Zherlitsyna, L.; Auner, N.; Shchegolikhina, O.;
polylactide. Polyhedron 2010, 29, 312−316. (d) Ehle, S.; Bru
Lorenz, V.; Hrib, C. G.; Saulich, K.; Muller, S.; Quade, A.; Edelmann,
F. T. Linear Heterometallic Co Li and Co Li Siloxides: Precursors
̈
ser, V.;
̈
3
2
4
2
for the Plasma Synthesis of Adsorbent Materials. Eur. J. Inorg. Chem.
Pozdniakova, Y.; Schu
magnetic investigations on new molecular quantum rings. C. R. Chim.
007, 10, 89−95. (c) Zherlitsyna, L.; Auner, N.; Bolte, M.;
Pozdniakova, Y.; Shchegolikhina, O.; Lyssenko, K.; Pashchenko, V.;
Wolf, B.; Lang, M.; Schutz, F.; et al. Synthesis, Structure and Magnetic
̈
tz, F.; Kopietz, P.; Kollar, M. Structural and
2
013, 2013, 1451−1457. (e) Hazra, S.; Martins, L. M. D. R. S.; Guedes
da Silva, M. F. C.; Pombeiro, A. J. L. Sulfonated Schiff base dimeric
and polymeric copper(II) complexes: Temperature dependent syn-
thesis, crystal structure and catalytic alcohol oxidation studies. Inorg.
Chim. Acta 2017, 455, 549−556.
2
̈
Properties of a Novel Hexanuclear Copper Methylsiloxane Complex.
(20) (a) Shilov, A. E.; Shul’pin, G. B. Activation and Catalytic
Eur. J. Inorg. Chem. 2007, 2007, 4827−4838.
Reactions of Saturated Hydrocarbons in the Presence of Metal Complexes;
Kluwer Academic Publishers: New York, 2002; pp 548. (b) Shilov, A.
E.; Shul’pin, G. B. Activation of C−H Bonds by Metal Complexes.
Chem. Rev. 1997, 97, 2879−2932. (c) Denisov, E. T.; Afanas’ev, I. B.
Oxidation and Antioxidants in Organic Chemistry and Biology; Taylor &
Francis: Boca Raton, FL, 2005. (d) Nesterov, D. S.; Chygorin, E. N.;
(
13) (a) Cotton, F. A.; Dikarev, E. V.; Petrukhina, M. A.; Stiriba, S.-E.
Studies of Dirhodium(II) Tetra(trifluoroacetate). 5. Remarkable
Examples of the Ambidentate Character of Dimethyl Sulfoxide.
Inorg. Chem. 2000, 39, 1748−1754. (b) Song, Y.-F.; Abbas, H.; Ritchie,
C.; McMillian, N.; Long, D.-L.; Gadegaard, N.; Cronin, L. From
polyoxometalate building blocks to polymers and materials: the silver
connection. J. Mater. Chem. 2007, 17, 1903−1908.
Kokozay, V. N.; Bon, V. V.; Boca
̌
, R.; Kozlov, Y. N.; Shul’pina, L. S.;
Jezierska, J.; Ozarowski, A.; Pombeiro, A. J. L.; Shul’pin, G. B.
(
14) Pashchenko, V.; Brendel, B.; Wolf, B.; Lang, M.; Lyssenko, K.;
III
III
Heterometallic Co 4Fe Schiff Base Complex: Structure, Electron
2
Shchegolikhina, O.; Molodtsova, Y.; Zherlitsyna, L.; Auner, N.; Schutz,
̈
Paramagnetic Resonance, and Alkane Oxidation Catalytic Activity.
Inorg. Chem. 2012, 51, 9110−9122.
F.; Kollar, M.; Kopietz, P.; Harrison, N. Synthesis, Structure and
II
Magnetic Properties of a Novel Linear Cu -Trimer Complex. Eur. J.
Inorg. Chem. 2005, 2005, 4617−4625.
(
15) (a) Bilyachenko, A. N.; Dronova, M. S.; Yalymov, A. I.;
Korlyukov, A. A.; Shul’pina, L. S.; Arkhipov, D. E.; Shubina, E. S.;
Levitsky, M. M.; Kirilin, A. D.; Shul’pin, G. B. New Binuclear Cage-like
Copper(II) Silsesquioxane (“Cooling Tower”); Its High Catalytic
Activity in Oxidation of Benzene and Alcohols. Eur. J. Inorg. Chem.
2
013, 2013, 5240−5246. (b) Dronova, M. S.; Bilyachenko, A. N.;
Yalymov, A. I.; Kozlov, Y. N.; Shul’pina, L. S.; Korlyukov, A. A.;
K
DOI: 10.1021/acs.inorgchem.7b00061
Inorg. Chem. XXXX, XXX, XXX−XXX