Synthesis, isomerism, and catalytic properties of chelate ruthenium copper bimetallacarborane cluster exo-closo-(Ph3P)Cu(μ-H)Ru[Ph 2P(CH2)4PPh2](η5- C2B9H11

Article abstract of DOI:10.1007/s11172-010-0217-x

Chelate exo-nido-ruthenacarboranes exo-5,6,10-[RuCl(Ph₂P(CH ₂)₄PPh₂)]-5,6,10-(μ-H)₃-10-H-7,8- R,R′-nido-7,8-C₂B₉H₆ (R, R′ = H, PhCH₂) were synthesized by th

Full text of DOI:10.1007/s11172-010-0217-x

Russian Chemical Bulletin, International Edition, Vol. 59, No. 6, pp. 1145—1151, June, 2010
1145
Synthesis, isomerism, and catalytic properties
of chelate ruthenium copper bimetallacarborane cluster
5
exoꢀclosoꢀ(Ph P)Cu(μꢀH)Ru[Ph P(CH ) PPh ](η ꢀC B H ),
3
2
2 4
2
2 9 11
in radical polymerization of methyl methacrylate*
D. I. D´yachikhin, I. D. Grishin, F. M. Dolgushin, I. A. Godovikov, I. T. Chizhevsky, and D. F. Grishinb
a
b
a
a
a
aA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
2
8 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 5085. Еꢀmail: chizbor@ineos.ac.ru
Research Institute for Chemistry, Nizhny Novgorod N. I. Lobachevsky State University,
b
2
3 prosp. Gagarina, 603950 Nizhny Novgorod, Russian Federation.
Fax: +7 (831) 265 8162. Еꢀmail: grishin@ichem.unn.ru
Chelate exoꢀnidoꢀruthenacarboranes exoꢀ5,6,10ꢀ[RuCl(Ph P(CH ) PPh )]—5,6,10ꢀ
2
2 4
2
(
μꢀH) —10ꢀHꢀ7,8ꢀR,R´—nidoꢀ7,8ꢀC B H (R, R´ = H, PhCH ) were synthesized by the
3 2 9 6 2
direct method using the reaction of Cl Ru(PPh )(Ph P(CH ) PPh ) with [7,8ꢀR,R´ꢀnidoꢀ7,8ꢀ
2
3
2
2 4
2
C B H ][K] in benzene. Unsubstituted exoꢀnidoꢀruthenacarborane (R, R´ = H) was used
2
9
10
in situ for the synthesis of the dinuclear RuꢀCu exoꢀcloso cluster of the formula exoꢀclosoꢀ
5
(
Ph P)Cu(μꢀH)Ru(Ph P(CH ) PPh )(η ꢀC B H ). The isomerism of the complex and the
3 2 2 4 2 2 9 11
crystal structure were studied by NMR spectroscopy and Xꢀray diffraction. The catalytic activꢀ
ity of the cluster in the atom transfer radical polymerization of methyl methacrylate was inꢀ
vestigated.
Key words: dinuclear ruthenium copper carborane complexes, methyl methacrylate,
controlled radical polymerization, crystal structure.
Relatively recently, it has been proposed that organoꢀ
Results and Discussion
It was found that the reaction of the known complex
metallic compounds belonging to homoꢀ and heterobimeꢀ
tallic ruthenium complexes can be used as catalysts for the
atom transfer radical polymerization (ATRP) of vinyl
1
0
Cl Ru(PPh )(Ph P(CH ) PPh ) (1) containing the
2
3
2
2 4
2
1
monomers. In particular, it has been found that dinuclear
chelating diphosphine dppb ligand with nidoꢀdicarbaunꢀ
decaborate salts [7,8ꢀR ꢀnidoꢀ7,8ꢀC B H ][K] (2, R =
ruthenium complexes based on [RuCl (pꢀcymene)] exꢀ
2
2
2
2
9
10
hibit high activity in the controlled synthesis of narrowꢀ
polydispersity polymers based on (meth)acrylates and styꢀ
rene.2 From this point of view, bimetallacarboranes conꢀ
taining one or both ruthenium atoms would be promised.
This is supported by the results of the research of mononuꢀ
H; 3, R = PhCH ) in benzene affords mononuclear exoꢀ
2
nido complexes 4 and 5, respectively, of the general forꢀ
mula exoꢀ5,6,10ꢀ[RuCl(Ph P(CH ) PPh )]ꢀ5,6,10ꢀ(μꢀ
—4
2
2 4
2
H) —10ꢀH—7,8ꢀR —nidoꢀ7,8ꢀC B H (Scheme 1). In
3
2
2
9
6
the course of the isolation and purification by column
chromatography on silica gel, unsubstituted complex 4
exhibited properties absolutely identical to those of the
exoꢀnido complex, which has been synthesized previously
II
III
clear Ru and Ru closoꢀruthenacarboranes with chelatꢀ
ing diphosphine ligands,5 which showed their efficiency
as ATRP catalysts. In the present study, we synthesized
the first chelate rutheniumꢀcopper exoꢀclosoꢀbimetallaꢀ
—9
by the replacement of the PPh ligands in the exoꢀnido
3
carborane with the diphosphine ligand of the formula
complex exoꢀ5,6,10ꢀ[RuCl(PPh ) ]—5,6,10ꢀ(μꢀH) —10ꢀ
3
2
3
12
5
6,11
[
(Ph P)Cu(μꢀH)Ru(Ph P(CH ) PPh )(η ꢀC B H )],
H—nidoꢀ7,8ꢀC B H (6)
with the dppb ligand. Thus,
3
2
2 4
2
2
9
11
2
9
8
1
31
1
investigated its structure and isomerism by Xꢀray diffracꢀ
tion and NMR spectroscopy, and tested the complex as a
catalyst in the controlled synthesis of poly(methyl methꢀ
acrylate).
according to the H and P{ H} NMR spectroscopic data,
complex 4 exists as a mixture of geometric isomers (which
is characteristic of all known threeꢀbridge exoꢀnidoꢀmetꢀ
1
1—13
allacarboranes
), and it is readily rearranged into the
closo isomer 3,3ꢀ(dppb)—3ꢀH—3ꢀCl—closoꢀ3,1,2ꢀ
RuC B H (7)12 in 80% yield during storage in benzene
*
Dedicated to Academician of the Russian Academy of Sciences
2
9
11
I. L. Eremenko on the occasion of his 60th birthday.
(see Scheme 1). Unlike 4, its C,C´ꢀdibenzylꢀsubstituted
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1122—1128, June, 2010.
066ꢀ5285/10/5906ꢀ1145 © 2010 Springer Science+Business Media, Inc.
1

1
146
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 6, June, 2010
D´yachikhin et al.
analog 5 was isolated from the reaction as airꢀstable orange
crystals. Ruthenacarborane 5 does not undergo isomerꢀ
ization into the corresponding closo complex 3,3ꢀ(dppb)—
was performed in one step according to Scheme 2 folꢀ
lowed by the purification of the mixture of the isomeric
products exoꢀclosoꢀ(Ph P)Cu(μꢀH)Ru(Ph P(CH ) ꢀ
3
2
2 4
5
3
ꢀH—3ꢀCl—1,2ꢀ(PhCH ) ꢀclosoꢀ3,1,2ꢀRuC B H (8)
PPh )(η ꢀC B H ) (9a,b; the βꢀ and αꢀsite isomers, reꢀ
2
2
2
9
9
2 2 9 11
even upon heating in benzene. Complex 5 was characterꢀ
ized by H and P{ H} NMR spectroscopy and elemental
analysis (see the Experimental section).
spectively) by the lowꢀtemperature (–5 °C) recrystallizaꢀ
tion from a THF—ethanol mixture. The composition
and the structures of isomers 9a,b in solution and in the
solid state were determined by broadꢀband and selective
1
31
1
31
1
31
1
11
11
1
1
31
Pꢀdecoupled H, P{ H}, B/ B{ H}, and H{ P}
Scheme 1
NMR spectroscopy and based on the Xꢀray diffraction
data for the major βꢀsite isomer 9a (Fig. 1), whose single
crystals were obtained by slow recrystallization of a mixꢀ
ture 9a,b from a C H —nꢀhexane system at 20 °C.
6
6
The structure and the geometry of complex 9a are preꢀ
sented in Fig. 1. Selected interatomic distances and bond
angles are given in Table 1. Complex 9a contains the icosaꢀ
hedral moiety {closoꢀ3,1,2ꢀC B Ru(dppb)}, to which the
2
9
copper atom is coordinated by two bridging B—H...Cu
and Ru—H—Cu bonds. The copper atom is additionally
coordinated by one PPh ligand. The threeꢀcenter twoꢀ
3
electron (2e,3c)ꢀbond B(8)—H...Cu (Cu...B(8), 2.198(4) Å;
Cu...H(8), 1.75(4) Å) is formed with the involvement of
the boron atom B(8) from the upper pentagonal plane of
the carborane ligand bound at the most electronꢀrich β
position with respect to the cage carbon atoms C(1) and
C(2). The possible involvement of the αꢀB(4) atom in
the similar interaction with the copperꢀcontaining
Cu(PPh ) moiety through the formation of the 2e,3cꢀbond
3
B(4)—H...Cu is not confirmed by the observed Cu...B(4)
(
2.591(5) Å) and Cu...H(4) (2.65(4) Å) distances in the
structure. In complex 9a, the bond between the ruthenium
and copper atoms, which is additionally spanned by the
bridging hydrido ligand, can exist (Ru—Cu, 2.5846(5) Å;
Ru—Hbridge, 1.58(4) Å; Cu—Hbridge, 1.96(4) Å). Howevꢀ
er, it is difficult to conclusively prove the presence or abꢀ
sence of the metal—metal bond in complex 9a without
chemical quantum calculations of this bond order. On
the whole, the investigation of the structure of complex 9a
showed that the latter can be assigned to exoꢀcloso clusters
∩
R = H (4, 7), CH Ph (5, 8*); P P = dppb = Ph P(CH ) PPh
2
2
2 4
2
*
Attempts to synthesize complex 8 failed.
Since unsubstituted complex 4 readily undergoes the
exoꢀnido→closo rearrangement in solution, which hinders
the isolation of 4 in the individual state, we used this comꢀ
plex in situ in the synthesis of the dinuclear Ru—Cuꢀexoꢀ
closo cluster with the chelating dppb ligand. The reaction
1
4
Scheme 2

Synthesis of chelate Ru—Cu bimetallacarborane
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 6, June, 2010
1147
C(14)
C(15)
C(16)
C(13)
P(2)
H(1M)
P(1)
P(3)
Ru(3)
H(8)
Cu(1)
B(7)
B(8)
C(1)
B(12)
B(4)
С(2)
B(11)
B(9)
B(5)
B(6)
B(10)
Fig. 1. Molecular structure of complex 9a.
and confirmed that the formation of 9a from exoꢀnidoꢀ
ruthenacarborane 4 is accompanied by the mild exoꢀ
nido→closo rearrangement.
sition. Thus, the major isomer 9a is characterized by sinꢀ
glets at δ +48.50 (s, 2 P, dppb—Ru), +4.05 (s.br, 1 P,
PPh —Cu), whereas the minor isomer 9b gives singlets at
3
The structures of complexes 9a,b in solution were studꢀ
ied by NMR spectroscopy of a mixture of the isomers
δ +53.9 (s, 2 P, dppb—Ru), +3.3 (s.br, 1 P, PPh —Cu).
In the highꢀfield region of the H NMR spectrum, each
3
1
31
1
(
5 : 1) in C D . In the P{ H} NMR spectrum of 9a,b, the
isomer shows one doublet of triplets of the bridging hyꢀ
dride Cu—H—Ru at δ –9.38 (major isomer 9a) and –8.45
(minor isomer 9b) (Fig. 2, a), which is transformed into
6
6
singlets of the phosphine ligands at the ruthenium and
copper atoms substantially differ in the linewidth and poꢀ
3
1
1
31
singlets in the broadꢀband Pꢀdecoupled H{ P} NMR
31
spectrum (see Fig. 2, b). The selective Pꢀdecoupled NMR
spectra show doublets with the spinꢀspin coupling conꢀ
Table 1. Selected bond lengths (d) and bond angles (ω) in the
structure of 9a
2
stants J(H,PPPh3) = 10.0 Hz (major isomer 9a) and
2
J(H,PPPh3) = 8.5 Hz (minor isomer 9b) (see Fig. 2, c, d)
31
Parameter
Bond
Value
Parameter
Bond
Value
of the dppb ligands for both isomers, whereas the P deꢀ
coupling at δ 3.3—4.05 leads to triplets with the spinꢀspin
d/Å
d/Å
2
coupling constants J(H,Pdppb) = 24.9 Hz (major isomer
Ru(3)—C(1)
Ru(3)—C(2)
Ru(3)—B(4)
Ru(3)—B(7)
Ru(3)—B(8)
Ru(3)—P(1)
Ru(3)—P(2)
Ru(3)—Cu(1) 2.5846(5)
Ru(3)—H(1M) 1.58(4)
Cu(1)—H(1M) 1.96(4)
2.236(4)
2.252(4)
2.273(5)
2.236(5)
2.286(4)
Cu(1)…H(4)
C(1)—C(2)
C(1)—B(4)
C(2)—B(7)
B(7)—B(8)
2.65(4)
2
9
a) and J(H,Pdppb) = 25.4 Hz (minor isomer 9b) for the
1.607(7)
1.668(7)
1.698(7)
1.793(7)
1.798(7)
PPh ligands (see Fig. 2, е). Although the presence of the
3
B—H...Cu bond in the crystal structure of complex 9a was
unambiguously established (see the Xꢀray diffraction data),
the hydride signal of this bond at δ –20—0 is not observed
2.3006(12) B(4)—B(8)
2.2891(12)
1
in the H NMR spectrum. This signal would be expected
Angle
ω/deg
1
to be relatively broad due to the spinꢀspin coupling of H
1
1
10
63
P(2)—Ru(3)—P(1)
191.61(4)
with the magnetic nuclei B, B, and Cu and, conseꢀ
1
5
Ru(3)—H(1M)—Cu(1) 193(1)
2.1930(11) Cu(1)—H(8)—B(8) 101(2)
2.198(4)
2.591(5)
1.75(4)
quently, would coalesce with the baseline. The expected
set of closely spaced signals for the protons of the dppb
Cu(1)—P(3)
Cu(1)…B(8)
Cu(1)…B(4)
Cu(1)—H(8)
P(3)—Cu(1)—H(8)
P(3)—Cu(1)—H(1M) 118(2)
H(1M)—Cu(1)—H(8) 117(2)
124(2)
and PPh ligands, the Ph groups of diphosphines, and the
3
cluster CH groups of both isomers 9a,b is observed in the
1
aliphatic and aromatic regions of the H NMR spectrum;

1
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Russ.Chem.Bull., Int.Ed., Vol. 59, No. 6, June, 2010
D´yachikhin et al.
a
b
1
.0
4.6
–9.5
–
8.5
–9.0
δ
–8.5
–9.0
δ
c
d
e
–
8.5
–9.0
δ
–8.5
–9.0
δ
–8.5
–9.0
δ
1
1
31
1
Fig. 2. The H and H{ P} NMR spectra (hydride region) of a mixture of complexes 9a,b: the H NMR spectrum (the integrated
1
31
31
intensities of the signals of isomers 9a,b are given) (a); the broadꢀband decoupled H{ P} NMR spectrum (b); the Pꢀdecoupled
NMR spectrum of the dppb ligand of the major isomer 9a (c); the Pꢀdecoupled NMR spectrum of the dppb ligand of the minor
isomer 9b (d); the 3 Pꢀdecoupled NMR spectrum of the PPh ligand of both isomers 9a,b (e).
31
1
3
the signals of the cluster CH groups can be identified based
on the linewidths (see the Experimental section).
sis of the plot ln(M /M) versus the time shows that the
0
maximum number of active chains is observed in the iniꢀ
tial polymerization step and it decreases with time.
A relatively large number of chains in the initial
polymerization step is apparently associated with the irreꢀ
The cluster obtained as a mixture of isomers 9a,b was
examined as the catalyst for controlled ATRP of methyl
methacrylate (MMA). Carbon tetrachloride was used as
the initiator for the radical generation. Our experiments
showed that the catalytic system based on 9a,b and CCl4
can initiate the polymerization of MMA. At 80 °C, the
reaction proceeds smoothly to high degrees of conversion
without the gel effect (Fig. 3). The resulting polymers are
characterized by low molecular weights but by a rather
narrow molecular weight distribution (Fig. 4). The moꢀ
lecular weight of the polymers linearly increases with the
conversion, and the molecular weight distribution of the
samples becomes slightly narrower, which is characterisꢀ
tic of the controlled radical polymerization.1
versible reaction of complex 9 with CCl giving radicals,
4
which initiate the process, and producing ruthenium and
copper complexes, which mediate the controlled ATRP
7
polymerization.
Taking into account the observed features of the radiꢀ
cal polymerization of MMA in the presence of dinuclear
chelate complex 9, it was of interest to study the synthesis
of polyMMA in the presence of the structurally similar
nonꢀchelate bimetallacarborane, exoꢀclosoꢀ(Ph P)Cuꢀ
3
5
15
(μꢀH)Ru(PPh ) (η ꢀC B H ) (10), containing tripheꢀ
3
2
2
9
11
,4
nylphosphine ligands at the Cu and Ru atoms. The results
of the research (Table 2) show that the polymerization in
At the same time, the linear plot of the molecular
weight of polyMMA versus the conversion starts from the
nonꢀzero value (see Fig. 4), which indirectly indicates
that the initial step of the reaction is accompanied by side
processes, which are apparently associated with the in situ
formation of the catalyst responsible for the chain growth.
The side processes are also evidenced by the time depenꢀ
dence of the logarithm of the initial to current concentraꢀ
tion ratio, which is nonlinear and is characterized by an
inflection point in the initial region (see Fig. 3). An analyꢀ
Table 2. Polymerization of MMA in the presence of 10
(
0.125 mol.%) and CCl (0.25 mol.%) at 80 °C
4
t/h
Conversion
Mn
Mw
M /M
w
n
0
5
5
.5
0
30.2
54.6
99.0
9900
25000
40700
22200
43100
77900
2.2
1.7
1.9

Synthesis of chelate Ru—Cu bimetallacarborane
Conversion (%)
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 6, June, 2010
1149
a
b
ln(M /M)
0
1
1
0
.6
.2
.8
8
6
4
2
0
0
0
0
0
0.4
0
1
0
20
30
40
t/h
10
20
30
40
t/h
Fig. 3. Polymerization of MMA in the presence of the system based on 9 (0.125 mol.%) and CCl (0.25 mol.%) at 80 °C: a, the plot of
4
the conversion versus the time, b, the plot of ln(M /M) versus the time.
0
the presence of the dinuclear complexes with dppb and
and diphosphine ligands, we have observed a similar situaꢀ
tion, i.e., ruthenacarboranes with chelating diphosphines
provide the more efficient control over the molecular
weight distribution of polyMMA and polystyrene.5
However, complexes 9 and 10 proved to be thermally less
stable in the ATRP process, which is indirectly evidenced
by the fact that the time dependence of the logarithm of
the initial to current concentration ratio of the monomer
deviates from the linear dependence.
PPh ligands is characterized by similar features. The moꢀ
3
lecular weight of the polymers increases, whereas the polyꢀ
dispersity decreases with increasing conversion. The polyꢀ
dispersity indices of the samples prepared in the presence
of chelate complexes 9a,b are somewhat smaller than those
of the samples obtained in the presence of nonꢀchelate
—7
7
—9
bimetallacarborane 10. Previously,
when studying the
polymerization of vinyl monomers in the presence of
mononuclear ruthenium carborane complexes with monoꢀ
To sum up, based on the experimental data it can be
concluded that, although the systems under study are less
efficient and stable in the ATRP of MMA than mononuꢀ
–
3
M •10
w
M /Mn
n
5—8
clear closoꢀruthenacarboranes,
a considerable advanꢀ
tage of these systems is that they provide a higher rate of
the polymerization of MMA compared to monoꢀclosoꢀ
ruthenacarboranes due apparently to the higher reactivity
1
2
1
1
0
5
0
2
0
2.6
of the dinuclear systems with respect to CCl . Hence, it
4
can be suggested that the dinuclear clusters with carboꢀ
rane ligands under consideration are promising catalysts
for the polymerization of vinyl monomers when they are
used at low concentrations. This is an important problem
of the controlled synthesis of macromolecules under radiꢀ
2.2
1.8
1.4
1
,4
2
cal initiation conditions and will be the subject of our
further research.
Experimental
All reactions were carried out under an argon atmosphere
with the use of anhydrous solvents prepared according to stanꢀ
dard procedures. The products were isolated and purified by
column chromatography on silica gel (Merck, 230—400 mesh).
The NMR spectra were recorded on a Bruker AMXꢀ400 NMR
2
0
40
60
Conversion (%)
Fig. 4. Plots of the average molecular weight (M , 1) and the
polydispersity index (M /M , 2) versus the conversion of polyꢀ
MMA samples synthesized in the presence of the system based
on 9 (0.125 mol.%) and CCl (0.25 mol.%) at 80 °C.
n
w
n
1
31
11
spectrometer ( H, 400.13 MHz; P, 161.98 MHz; B, 128.3
4

1
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Russ.Chem.Bull., Int.Ed., Vol. 59, No. 6, June, 2010
D´yachikhin et al.
MHz). The elemental analysis of new compounds was carried
out in the Laboratory of Microanalysis of the A. N. Nesmeyanov
Institute of Organoelement Compounds of the Russian Acadeꢀ
my of Sciences. The bulk polymerization of MMA was perꢀ
formed under a residual pressure of 1.3 Pa according to a proceꢀ
asꢀ4); –1.2 (m, Hextra, sꢀ4, asꢀ4).12 In subsequent experiments,
complex 4 was used in situ as the reactant.
Synthesis of the dinuclear cluster exoꢀclosoꢀ(Ph P)Cu(μꢀH)ꢀ
3
5
Ru(Ph P(CH ) PPh )(η ꢀC B H11) (9a,b, a mixture of isomers,
2
2 4
2
2 9
5 : 1). A mixture of complex 1 (0.2 g, 0.233 mmol) and K salt 2
9
dure described previously. The molecular weight characterisꢀ
(0.07 g, 0.407 mmol) in dry C H (20 mL) was stirred at room
6
6
tics of the polymers were determined by gel permeation chromaꢀ
tography on a Knauer instrument (Germany) equipped with
a Phenomenex Linearꢀ2 linear column (USA) and an RI Deꢀ
tector Kꢀ2301 differential refractometer as the detector. Chloꢀ
roform was used as the eluent. The calibration was carried
temperature for 1 h. The solvent was removed in vacuo, and an
excess of powdered KOH (0.07 g, 1.25 mmol) was added to the
residue. The pumping of the mixture of the reactants was carried
out until all traces of air were removed. The reactor was filled
with argon, anhydrous ethanol (15 mL) was added, and the reacꢀ
tion mixture was stirred for 30 min until a yellow precipitate
formed. Then ClCu(PPh ) (see Ref. 16) (0.18 g, 0.20 mmol)
out with the use of narrowꢀpolydispersity polyMMA standards
5
(
Waters; the molecular weight varies from 2580 to 9.81•10 ).
3
3
The chromatographic data were interpreted using the Chromꢀ
Gate software.
and anhydrous THF (5 mL) were added to the reaction mixture,
and the mixture was stirred for 2.5 h. A dirtyꢀyellow precipitate
that formed was filtered off and washed with anhydrous diethyl
ether (2×3 mL). The product was purified by recrystallization
from a C H —nꢀhexane mixture. Dinuclear Ru—Cuꢀcomplex
exoꢀChloro[1´,4´ꢀbis(diphenylphosphino)butane]ꢀnidoꢀ[7,8ꢀ
dibenzylꢀ10ꢀhydroꢀorthoꢀcarboraneꢀ5,6,10ꢀtris(hydrido)]ruthenꢀ
ium (5, a mixture of symmetric (s) and asymmetric (as) isomers in
a ratio of 1.3 : 1). A mixture of complex 1 (0.2 g, 0.233 mmol)
and K salt 3 (0.09 g, 0.256 mmol) in benzene (15 mL) was stirred
at room temperature for 2 h until the color of the solution changed
from darkꢀgreen to orange. The reaction mixture was concenꢀ
trated in vacuo to 2—3 mL and then transferred to a column
packed with silica gel using benzene as the eluent. The subseꢀ
quent evaporation of the solvent in vacuo and the recrystallizaꢀ
tion of the residue from a benzene—nꢀhexane mixture afforded
analytically pure crystals of a mixture of s and as isomers 5 in
a yield of 0.16 g (79%). Found (%): C, 62.96; H, 6.11; B, 11.00.
C H B ClP Ru•C H . Calculated (%): C, 62.91; H, 6.08;
6
6
9a,b (a 5 : 1 mixture of isomers) was obtained as yellow needleꢀ
like crystals in a yield of 0.18 g (75%). Found (%): C, 60.45;
H, 5.29. C H B CuP Ru•C H . Calculated (%): C, 60.89;
4
8
55
9
3
6
6
–
1
1
H, 5.73. IR, ν/cm : 2542 (B—H). H NMR (C D , 20 °C), δ:
–9.39 (td, 1 H, Ru—H—Cu, 9a, J(H,PPPh3) = 10.0 Hz,
J(H,Pdppb) = 24.9 Hz); –8.47 (td, 0.2 H, Ru—H—Cu, 9b,
J(H,PPPh3) = 8.5 Hz, J(H,Pdppb) = 25.4 Hz); 1.44, 2.32, 2.47,
2.55 (m of different intensities with Σ = 9.8 H, (PCH CH ) ,
6
6
2
2
2
2
2
2 2
9a,b); 1.86 (br.s, >2 H, CHcarb, 9a,b); 6.75—7.85 (set of eleven t
1
31
and one br.m, 42 H, 9a,b). H{ P} NMR (C D , 20 °C), δ:
6
6
–9.39 (s, Ru—H—Cu, 9a); –8.47(s, Ru—H—Cu, 9b); 1.44, 2.32*,
2.47*, 2.55 (m of different intensities, Σ = 9.8 H, (PCH CH ) ,
4
4
52
9
2
6
6
1
B, 10.19. H NMR (CD Cl , 20 °C), δ: –17.2 (m, H(10), sꢀ5);
2
2
2
2 2
–
–
15.7 (m, H(6) or H(5), asꢀ5); –5.8 (m, H(10), asꢀ5); –4.0 and
3.3 (both m, H(5) or H(6), asꢀ5 and H(5), H(6), sꢀ5); –1.2
9a,b); 1.86 (br.s, 2 H, CHcarb, 9a); 6.79 (t, 3 H, J = 7.4 Hz); 6.86
(t, 3 H, J = 7.4 Hz); 6.93 (t, 2 H, J = 7.2 Hz); 7.02—7.22 (m, 18 H);
7.43 (m, 3 H); 7.53 (d, 3 H, J = 7.6 Hz); 7.62 (d, 3 H, J = 7.3 Hz);
(
(
(
2
m, Hextra, sꢀ5 and asꢀ5); 1.61, 2.05, 2.42, and 3.41 (all br.s,
PCH CH ) , sꢀ5); 1.48, 1.85, 2.37, 2.50, 3.25, and 3.66 (all br.s,
PCH CH ) , asꢀ5); 3.09—3.21 (two overlapping q (7 lines),
7.75—7.83 (m, 6 H); 7.85 (d, 1 H, J = 7.4 Hz). 3 P{ H} NMR
1
1
2
2 2
(C D , 20 °C), δ: 3.33 (br.s, PPh , 9b); 4.05 (br.s, PPh , 9a);
2
2 2
6
6
3
3
31
1
PhCH ); 7.12—7.61 (m, Ph). P{ H} NMR (CD Cl , 20 °C),
48.53 (s, (PCH CH ) , 9a); 53.9 (s, (PCH CH ) , 9b).
2
2
2
2 2 2 2 2 2
δ: 52.02 (m, asꢀ5); 53.05 (br.s, sꢀ5); 57.29 (br.d, asꢀ5, J
=
Xꢀray diffraction study of complex 9a. Crystals
(C H B CuP Ru, M = 1103.89) are orthorhombic, space group
P,P
1
1
=
+
39.3 Hz). B NMR (CD Cl , 20 °C), δ, J = JB,H/Hz: +4.4,
2 2
1.2, –7.8, –20.7, and –32.4 (all br.s, B(1)—B(4) sꢀ and asꢀ5;
57 64
9
3
P2 2 2, at 100 K a = 14.0546(5) Å, b = 34.6252(13) Å,
1 1
3
–3
B(5) asꢀ5); –18.8, –24.5, –26.6 (d of different intensities, B(5),
B(6), sꢀ5, B(9), B(11) sꢀ5, asꢀ5, J = 76, 99, 110 Hz); 41.2,
c = 10.9995(4) Å, V = 5352.8(3) Å , Z = 4, dcalc= 1.370 g cm ,
μ(MoꢀKα) = 8.07 cm– . The intensities of 52200 reflections
(10484 independent reflections, Rint = 0.0852) were measured
on a Bruker APEX II diffractometer equipped with an area deꢀ
1
(
m, B(10), sꢀ5); 44.6 (t, B(6), asꢀ5, J = 86 Hz).
exoꢀChloro[1´,4´ꢀbis(diphenylphosphino)butane]ꢀnidoꢀ[10ꢀ
1
7
hydroꢀorthoꢀcarboraneꢀ5,6,10ꢀtris(hydrido)]ruthenium (4, a mixꢀ
ture of symmetric (s) and asymmetric (as) isomers). Ruthenacarꢀ
borane 4 was formed as a mixture of s and as isomers under
conditions similar to those described above for complex 5 startꢀ
ing from complex 1 (0.150 g, 0.174 mmol) and K salt 2 (0.033 g,
tector (graphite monochromator, λ(MoꢀKα) = 0.71073 Å,
ωꢀscanning mode, 2θmax = 52°, T = 100 K). The structure was
solved by direct methods and refined by the fullꢀmatrix
leastꢀsquares method based on F 2 with anisotropic displaceꢀ
hkl
ment parameters for all nonhydrogen atoms. The absolute
configuration was determined based on the Flack parameter
0
.19 mmol) in benzene. Upon storage in solution, exoꢀnido comꢀ
1
2
18
plex 4 was transformed into the known closo isomer (7). An
attempt to isolate complex 4 in the individual state failed beꢀ
cause of its irreversible transformation in solution into closo isoꢀ
mer 7, although the exoꢀnido and closo isomers emerged from
a column packed with silica gel as individual bands: the lower
orange band (a mixture of the s and as isomers of 4) and the
upper yellow band (the closo isomer). The reaction was moniꢀ
(x = 0.00(2)). The hydrogen atoms of the carborane moiety
and the hydride ligand were located in difference Fourier maps.
The other hydrogen atoms were positioned geometrically and
refined using a riding model. In the crystal structure, there are
two benzene solvent molecules, one of which is in a general
position, and another molecule occupies a special position on
a twofold axis. The bridging methylene fragment of the complex
is disordered with occupancies of 60 and 40%. The final R facꢀ
tors are R = 0.0414 (based on F for 8366 reflections with
tored by 3 P{ H} NMR (CD Cl , 20 °C), δ: 37.3 (s, 7); 53.6
1
1
2
2
(
s, sꢀ4); 52.4 and 57.4 (both br.m, asꢀ4) or by the analysis of the
1
hkl
1
2
highꢀfield signals in the H NMR spectrum (C D , 20 °C), δ:
I > 2σ(I)), wR = 0.0840, and S = 1.046 (based on F
for all
6
6
2
hkl
–
–
16.6 (m, H(10), sꢀ4); –15.0 (m, H(6), asꢀ4); –7.9 (td, RuH, 7);
5.4 (m, H(10), asꢀ4); –3.3 (m, H(5), H(6), sꢀ4); –2.5 (m, H(6),
* Signals with a changed multiplicity.

Synthesis of chelate Ru—Cu bimetallacarborane
Russ.Chem.Bull., Int.Ed., Vol. 59, No. 6, June, 2010
1151
independent reflections). All calculations were carried out on a
9. D. F. Grishin, I. D. Grishin, I. T. Chizhevsky, in Conꢀ
trolled/Living Radical Polymerization: Progress in ATRP, Ed.
K. Matyjaszewski, Am. Chem. Soc.: Symposium Series, 2009,
1023, 115.
10. C. W. Jung, P. E. Garrou, P. R. Hoffman, K. G. Caulton,
Inorg. Chem., 1984, 23, 726.
1
9
PC with the use of the SHELXTL program package. The comꢀ
plete tables of atomic coordinates, bond lengths, bond angles,
and anisotropic thermal parameters were deposited with the
Cambridge Structural Database.
1
1
1
1. I. T. Chizhevsky, I. A. Lobanova, V. I. Bregadze, P. V. Petroꢀ
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Yu. T. Struchkov, Mendeleev. Commun., 1991, 47.
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Solodovnikov, I. T. Chizhevskii, Izv. Akad. Nauk, Ser. Khim.,
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4
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in revised form May 14, 2010