Iridium Halide Complexes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 (X = Cl, Br, I): Synthesis, Reactivity and Catalytic Activity

Article abstract of DOI:10.1002/ejic.201700498

The reactions of thallium salt Tl[7-SMe₂-7,8-C₂B₉H₁₀] with [(cod)RhCl]₂ and [Cp*RuCl]₄ are accompanied by room-temperature polyhedral rearrangement, giving rhoda- and ruthenacarboranes 1-co

Full text of DOI:10.1002/ejic.201700498

A Journal of
Accepted Article
Title: Iridium halide complexes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 (X
= Cl, Br, I): Synthesis, reactivity and catalytic activity
Authors: Alexander P. Molotkov, Mikhail M. Vinogradov, Alexey P.
Moskovets, Olga Chusova, Sergey V. Timofeev, Vasilii A.
Fastovskiy, Yulia V. Nelyubina, Alexander A. Pavlov, Denis A.
Chusov, and Dmitry Loginov
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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.201700498
Link to VoR: http://dx.doi.org/10.1002/ejic.201700498

10.1002/ejic.201700498
European Journal of Inorganic Chemistry
Iridium halide complexes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 (X = Cl, Br, I): Synthesis,
reactivity and catalytic activity
Alexander P. Molotkov,[a] Mikhail M. Vinogradov,[a] Alexey P. Moskovets,[a] Olga Chusova,[b]
Sergey V. Timofeev,[a] Vasilii A. Fastovskiy,[a] Yulia V. Nelyubina,[a] Alexander A. Pavlov,[a]
Denis A. Chusov,[a, b] Dmitry A. Loginov*[a]
Dedicated to the memory of Prof. Alexander R. Kudinov who contributed much to the
development of metallacarborane chemistry.
Abstract
The reactions of thallium salt Tl[7-SMe2-7,8-C2B9H10] with [(cod)RhCl]2 and
[Cp*RuCl]4 are accompanied by room temperature polyhedral rearrangement giving rhoda- and
ruthenacarboranes 1-cod-8-SMe2-1,2,8-RhC2B9H10 (2) and 1-Cp*-8-SMe2-1,2,8-RuC2B9H10 (3).
According to DFT-calculations, the rearrangement could be attained to the Triangular Face
Rotation (TFR) mechanism. The reaction of iridium derivative 1-cod-8-SMe2-1,2,8-IrC2B9H10
(1) with anhydrous hydrohalic acids HX (X = Cl, Br, I) results in the dimeric halide
iridacarboranes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 (4a–c, X = Cl (a), Br (b), I (c)). Bromide 4b
reacts with Tl[Tl(η-7,8-C2B9H11)] and TlCp giving iridacarboranes 8’-SMe2-1,1’-Ir(2,3-
C2B9H11)(2’,8’-C2B9H10) (5) and 1-Cp-8-SMe-1,2,8-IrC2B9H10 (6). The formation of latter
compound is accompanied by demethylation of the SMe2 substituent. Structures of 2, 3, 5 and 6
were determined by X-ray diffraction. Iridacarboranes 4b and [1,1-Br2-4-SMe2-1,2,3-
IrC2B9H10]2 (7) catalyze the dimerization of diphenylacetylene giving 1,2,3-triphenylnaphthalene
in 20–24% yields. 4b and 7 also effectively catalyze the reductive amination reaction between
aldehydes (or ketones) and primary (or secondary) amines in the presence of carbon monoxide
giving the corresponding secondary and tertiary amines in high yields (60–85%).
Keywords: CH activation; Iridium; Metallacarboranes; Metal complex catalysis
[a] A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Science,
28 ul. Vavilova, 119991 Moscow, Russian Federation
Fax: +7-499-135-5085
E-Mail: dloginov@ineos.ac.ru
Homepage: http://www.ineos.ac.ru/en
[b] Faculty of Science, RUDN University, 6 Miklukho-Maklaya St., Moscow 117198, Russian
Federation
1
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European Journal of Inorganic Chemistry
Introduction
The cyclopentadienyl complexes [(C5R5)MX2]2 (M = Rh, Ir; X = Cl, Br, I) are known to
be effective catalysts for numerous organic transformations.1 In the last decade, the use of these
complexes for C–H activation has gained traction. In particular, they have employed as catalysts
for the oxidative coupling of benzoic acids with internal alkynes2 as well as the carbenoid C–H
functionalization of benzenes and indoles.3 The both reactions proceed under chelation-
assistance of an appropriate directing group (e.g., C(O)OH, C(O)NR2, pyrazole, pyrimidine).
Recently, we have found that the substitution of cyclopentadienyl by boron-containing
ligands, viz. borole and carboranes, leads to the dramatically changes in selectivity of catalytic
reactions.4 For example, complex [Cp*IrCl2]2 catalyzes the oxidative coupling of benzoic acids
with internal alkynes giving naphthalenes, while the cationic iridacarborane [1-(C6H6)-1,2,3-
IrC2B9H11]+ results in isocoumarins.4b In this respect, the charge-compensated dicarbollides
containing dimethylsulfonium substituent at boron or carbon atoms seem to be promising ligands
for catalyst’s design.5 In contrast to unsubstituted dicarbolide, these carborane anions have the
same negative charge with Cp.6 Earlier, Kudinov with coworkers7 have been prepared the B-
substituted iridacarboranes [1,1-X2-4-SMe2-1,2,3-IrC2B9H10]2 (X = Cl, Br, I) which are close
analogs of [Cp*IrX2]2. Herein we report synthesis and reactivity of the related C-substituted
complexes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2. Catalytic activity of iridararboranes [1,1-Br2-8-
SMe2-1,2,8-IrC2B9H10]2 and [1,1-Br2-4-SMe2-1,2,3-IrC2B9H10]2 in alkyne dimerization and
reductive amination of aldehydes and ketones are also described.
Results and discussion
Synthesis and reactivity
In the preprimary work8 we have described synthesis and structure of
(cyclooctadiene)iridacarborane 1-cod-8-SMe2-1,2,8-IrC2B9H10 (1). This complex was prepared
by reaction of [(cod)IrCl]2 with [7-SMe2-7,8-C2B9H10]–. Noteworthy, this reaction is
accompanied by polyhedral rearrangement of the carborane ligand with a migration of the
substituted carbon atom from the metal bonded pentagonal face. In this work we found that
thallium salt Tl[7-SMe2-7,8-C2B9H10] reacts with [(cod)RhCl]2 and [Cp*RuCl]4 in similar
manner giving the corresponding rhoda- and ruthenacarboranes 1-cod-8-SMe2-1,2,8-RhC2B9H10
(2) and 1-Cp*-8-SMe2-1,2,8-RuC2B9H10 (3) in high yields (Scheme 1). For all metallacarboranes
2
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
in the present work we use a numbering system suggested by Stibr and Kudinov9 in which the
metal vertex bears number 1.
Scheme 1. Synthesis of rhoda- and ruthenacarboranes 2 and 3.
1
1
According to 11B{1H}–11B{1H} COSY, H−11B{1H} HETCOR and H with CW
decoupling on 11B nuclei NMR experiments data for complex 2 (see Figs. S1–S5 in the
Supporting Information) the most downfield signal (δ = 2.73 ppm) of BH hydrogen atoms
corresponds to the B(12)H hydrogen antipodal to the rhodium atom. The most upfield signal (δ =
1.18 ppm) corresponds to the B(10)H hydrogen connected with the only boron atom bonding
with other five boron atoms. Previously we have shown the same trend for BH hydrogen atoms
shifts in the related cyclooctadiene complex 2,8-Me2-1,1-(cod)-4-SMe2-1,2,8-RhC2B9H8.10
The proposed reaction path of the formation of 2 was investigated by relativistic PBE/L2
calculations (Fig. 1). According to this scheme on the first step initially formed closo-
rhodacarborane 2a undergoes transformation to the pseudocloso-configuration 2b. As was
previously shown for iridium analog 1,8 the closo-complex 2a is thermodynamically less stable
than pseudocloso complex 2b by 7.2 kcal mol–1 due to the anomeric effect of the SMe2
substituent. The second step is 2,3→2,8 carbon atoms rearrangement scheme via one transition
state (TS) and energy barrier ΔH≠ = 28.6 kcal mol–1. This TS has a geometry similar to a
previously found transition states for 2,3→2,8 isomerizations of the carbonyl complexes 3,3,3-
(CO)3-3,1,2-closo-MC2B9H11 (M = Re, Tc)11 and exhibits one imaginary frequency correspond
to the rotation of one CB2 face (see frequency animation in the Supporting Information). Thus,
isomerization of 2b to 2 could be attained to the Triangular Face Rotation (TFR) mechanism.
The final complex 2 has higher thermodynamic stability than the transient pseudocloso-isomer
2b by 9.4 kcal mol–1.
3
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
Figure 1. Energy profile for the plausible mechanism of the formation of 2. The values in
parentheses correspond to relative ZPE-corrected energies in kcal mol–1.
We found that reactions of iridacarborane 1 with anhydrous hydrohalic acids HX (X = Cl,
Br, I) affords the dimeric halide iridacarboranes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 (4a–c,
Scheme 2). One broad singlet (3.06–3.18 ppm) for CH-proton of carborane ligand and two sharp
singlets (3.06–3.11 ppm) for protons of methyl groups of the SMe2 substituent were observed in
the 1H NMR spectra of these compounds. Like the B-substituted isomers [1,1-X2-4-SMe2-1,2,3-
IrC2B9H10]2,7 iridacarboranes 4a–c are poorly soluble in non-coordinating solvents that inhibited
growing-up crystals for X-ray diffraction study. Moreover, the molecular ion peak was not
detected by mass-spectrometry; only the elimination of halomethanes MeX as a result of
intramolecular demethylation of the SMe2 substituent was observed by EI-MS. Nevertheless, the
dimeric structure can be suggested for these compounds based on their similarity to the
tricarbollide derivatives [1,1-X2-12-ButNH-1,2,4,12-MC3B8H10]2 (M = Rh, Ir),12 the structure of
which was unambiguously confirmed by X-ray diffraction.
4
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European Journal of Inorganic Chemistry
Scheme 2. Synthesis of the halide iridacarboranes 4a–c.
To demonstrate the utility of halides 4a–c as synthons of the iridacarborane fragment [8-
SMe2-1,2,8-IrC2B9H10]2+ we tested them in reactions with Tl[Tl(η-7,8-C2B9H11)] and TlCp. For
example, bromide 4b reacts with thallium dicarbollide giving the unsymmetrical bis(carborane)
complex 8’-SMe2-1,1’-Ir(2,3-C2B9H11)(2’,8’-C2B9H10) (5, Scheme 3). The 1H NMR spectrum of
5 displays three resonances corresponded to CH-protons (3.42, 3.97 and 4.03 ppm). The non-
equivalence of CH-protons of 7,8-C2B9H11 ligand can be explained by C1 symmetry of 5.13
Scheme 3. Reaction of 4b with Tl[Tl(η-7,8-C2B9H11)].
In contrast to the previous reaction, interaction of 4b with TlCp is accompanied by
monodemethylation of the SMe2 group with formation of iridacarborane 1-Cp-8-SMe-1,2,8-
IrC2B9H10 (6, Scheme 4). The main difference between these reactions consists in molar quantity
of thallium. Probably, in the case of reaction with TlCp the first bromide anion from 4a forms
TlBr, while the second one demethylates the SMe2 group. Previous works14 on the B-substituted
metallacarboranes, in which the SMe2 group is bonded to the open pentagonal face of carborane
ligand and located close to metal atom, suggest that demethylation is promoted by coordinated
halide anions because demethylation by the external halide ions is very slow at room
temperature. Contrary, the SMe2 group in 4b is far away from the metal atom. We assume that
the SMe2-group bonded with the cage carbon atom is more electrophilic to be attacked by the
external halide than boron connected one owing to higher acceptor ability of carbon vs. boron.15
1
In confirmation of the latter, the signal of SMe-protons in the H NMR spectrum of 6 is shifted
5
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
downfield (by 0.3 ppm) from corresponding signals for the related B-substituted iridacarboranes
1-(C5R5)-4-SMe2-1,2,3-IrC2B9H10 (R = H, Me).14c,16
Scheme 4. Reaction of 4b with TlCp.
X-ray diffraction study
The structures of 2, 3, 5, and 6 were determined by X-ray diffraction (Figs. 2–5). In all
compounds the pentagonal CB4 face is folded along the B3⋯B6 line by ca 9.7° for 2, 8.1° for 3,
6.8° for 5, and 3.3° for 6 so that the M–C2 bond is longer than the M–B bonds. Similar pattern
was observed earlier by Stone with coworkers for the monocarbollide complexes.17 In contrast,
in the transition metal complexes of the [7,8-C2B9H11]2− and [9-SMe2-7,8-C2B9H10]− anions, in
which metal atom is bonded with the C2B3 face, the M−C bonds are usually shorter than M−B
bonds in accordance with larger covalent radius of boron vs. carbon.18
The another feature of the 1,2,8-MC2B9 cages is shortening of the M⋯CB4 distance as
compared with the M⋯C2B3 distance in 1,2,3-MC2B9.19 In the complex 3 the distance from
ruthenium atom to the CB4 face (1.518 Å) is significantly shorter than Ru⋯C2B3 distance in 1-
(Cp*)-4-SMe2-3,1,2-closo-RuC2B9H10 (1.608 Å).6e Welch with coworkers20 have explained this
phenomena by increasing of the ring size of the pentagonal face going from C2B3 to CB4.
Interestingly, iridacarborane 5 contains both types of the cage units: 1,2,8-IrC2B9 and 1,2,3-
IrC2B9. In its structure the Ir⋯CB4 distance (1.540 Å) is considerably shorter than the Ir⋯C2B3
distance (1.642 Å), while the CB4 ring are larger only by 0.222 Å than C2B3. We propose that the
strong shortening of the M⋯CB4 distance is caused by not only geometry constraint but by
electronic effects.
To elucidate difference in the bonding of iridium atom in the 1,2,8-IrC2B9 and 1,2,3-
IrC2B9 cage units, we carried out energy decomposition analysis (EDA)21 for the model
iridacarborane [1,1’-Ir(2,3-C2B9H11)(2’,8’-C2B9H11)]– in terms of interactions [1,2,3-IrC2B9H11]+
+ [4,7-C2B9H11]2– or [1,2,8-IrC2B9H11]+ + [7,8-C2B9H11]2– (Table 1). Going from the Ir⋯4,7-
C2B9H11 bond to the Ir⋯7,8-C2B9H11 one, the orbital interaction (∆Eorb) considerably decreases,
whereas the sterical contribution (∆Esteric = ∆Eelstat + ∆EPauli) remains almost unchanged. As a
result, the overall interaction energy (∆Eint) for the first bond is higher by ca. 44 kcal mol–1 than
6
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
that for the second interaction. The ∆Eint values correlate well with the dissociation energies (De)
since the preparation energy (∆Eprep) is almost the same for both cases. We can conclude that the
metal bonding with the CB4 pentagonal face in metalladicarbollides is stronger than with the
C2B3 face owing to higher orbital contribution.
Table 1. Results of EDA (energy values in kcal mol–1) for complex [1,1’-Ir(2,3-C2B9H11)(2’,8’-
C2B9H11)]– using [1,2,3-IrC2B9H11]+ + [4,7-C2B9H11]2– or [1,2,8-IrC2B9H11]+ + [7,8-C2B9H11]2–
as interacting fragments at the BP86/TZP.
[1,2,3-IrC2B9H11]+ + [4,7-C2B9H11]2– [1,2,8-IrC2B9H11]+ + [7,8-C2B9H11]2–
∆Eint
–361.86
–317.29
∆EPauli 328.07
261.31
[a]
∆Eelstat –426.26
–362.54
(61.8%)
(62.7%)
[a]
∆Eorb
–263.67
–216.05
(38.2%)
(37.3%)
∆Eprep 22.75
De –339.11
18.62
–298.67
[a]
The values in parentheses give the percentage contribution to the total attractive interactions.
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European Journal of Inorganic Chemistry
Figure 2. Structure of complex 2. Atoms are represented by 50% thermal ellipsoids. Hydrogen
atoms are not depicted for clarity. Selected bond lengths [Å]: Rh1−C5 2.146(2), Rh1−C6
2.145(2), Rh1−C10 2.180(2), Rh1−C11 2.200(2), Rh1−B3 2.142(3), Rh1−C2 2.296(2), Rh1−B6
2.185(3), Rh1−B5 2.264(3), Rh1−B4 2.185(3), C8−S1 1.795(3), C3−S1 1.790(3), C4−S1
1.788(3), B3−C2 1.701(4), C2−B6 1.732(4), B5−B6 1.819(4), B4−B5 1.772(4), B3−B4
1.864(4), C5−C6 1.412(4), C10−C11 1.390(4).
8
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European Journal of Inorganic Chemistry
Figure 3. Structure of complex 3. Atoms are represented by 50% thermal ellipsoids. Hydrogen
atoms are not depicted for clarity. Selected bond lengths [Å]: Ru1−C15 2.197(4), Ru1−C16
2.204(4), Ru1−C17 2.202(4), Ru1−C18 2.219(4), Ru1−C19 2.197(4), Ru1−B3 2.097(4),
Ru1−C2 2.148(4), Ru1−B6 2.150(4), Ru1−B5 2.191(5), Ru1−B4 2.158(4), C8−S1 1.788(4),
C13−S1 1.785(4), C14−S1 1.790(4), B3−C2 1.726(6), C2−B6 1.746(6), B5−B6 1.821(6),
B4−B5 1.804(6), B3−B4 1.838(6), C15−C16 1.430(5), C16−C17 1.427(6).
9
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European Journal of Inorganic Chemistry
Figure 4. Structure of complex 5. Atoms are represented by 50% thermal ellipsoids. Hydrogen
atoms are not depicted for clarity. Selected bond lengths [Å]: Ir1−C2 2.209(7), Ir1−C3 2.218(5),
Ir1−B4 2.227(8), Ir1−B5 2.228(9), Ir1−B6 2.226(8), Ir1−B3’ 2.138(8), Ir1−C2’ 2.187(7),
Ir1−B6’ 2.190(8), Ir1−B5’ 2.216(8), Ir1−B4’ 2.145(7), C8’−S1 1.808(7), C5−S1 1.781(8),
C6−S1 1.791(7), C3−C2 1.638(9), C2−B6 1.730(11), B5−B6 1.828(11), B4−B5 1.847(12),
C3−B4 1.732(10), B3’−C2’ 1.739(11), C2’−B6’ 1.737(11), B5’−B6’ 1.857(11), B4’−B5’
1.789(10), B3’−B4’ 1.865(10).
10
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
Figure 5. Structure of complex 6. Atoms are represented by 50% thermal ellipsoids. Hydrogen
atoms are not depicted for clarity. Selected bond lengths [Å]: Ir1−C3 2.236(3), Ir1−C4 2.213(3),
Ir1−C5 2.211(3), Ir1−C6 2.209(3), Ir1−C7 2.224(3), Ir1−B3 2.154(3), Ir1−C2 2.187(3), Ir1−B6
2.177(3), Ir1−B5 2.164(3), Ir1−B4 2.135(3), C8−S1 1.801(3), C9−S1 1.794(3), B3−C2 1.796(4),
C2−B6 1.800(4), B5−B6 1.784(4), B4−B5 1.762(5), B3−B4 1.866(4), C3−C4 1.416(5), C4−C5
1.437(4).
Dimerization of alkynes
Taking into account the similarity of iridacarboranes 4a–c with [Cp*IrCl2]2, we examined
4b and its B-substituted analog [1,1-Br2-4-SMe2-1,2,3-IrC2B9H10]2 (7) as catalysts for the
oxidative coupling of benzoic acid with diphenylacetylene in the presence of Ag2CO3 in
refluxing o-xylene. Unexpectedly, instead of 3,4-diphenylisocoumarin or 1,2,3,4-
tetraphenylnaphthalene the only 1,2,3-triphenylnaphthalene was isolated in 6−7 % yields.
Interestingly, in the absence of benzoic acid the yields increase up to 22 % (Scheme 5). The
absence of coupling of benzoic acid with diphenylacetylene may be explained by electron
acceptor properties of the SMe2-substituted carborane ligands, which increase the oxidation
potentials of the reaction intermediates. This assumption correlates well with lower catalytic
11
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
activity of [CpIrI2]2 as compared with [Cp*IrCl2]2 in which cyclopentadienyl ligand contains five
donor methyl substituents.4b
Scheme 5. Dimerization of diphenylacetylene.
Dimerization of diarylacetylenes is well known for the Rh(I) complexes in the presence
of hydrohalic acids.22 Proposed mechanism includes initial oxidative addition of HX to Rh(I)
with the formation of rhodium hydride intermediate. Contrary, in our case we deal with another
reaction pathway because there are no strong acidic conditions. According to the plausible
mechanism (Scheme 6), the triple bond of diphenylacetylene acts as a directing group for ortho-
C−H activation in benzene ring to give intermediate A, in which iridium atom is π-bonded with
acetylene. Noteworthy, this process may be assisted by the carbonate anion. Similar assistance of
the acetate and pivalate anions was described earlier.23 The second diphenylacetylene insertion
leads to intermediate B, whereas following elimination of iridium with formation of 1,2,3-
triphenylnaphthalene remains unclear and requires future investigations. Probably, the low yield
of the dimerization product can be attributed to decomposition of catalyst as a result of side
processes of demethylation of the SMe2 group14 or hydroboration of diphenylacetylene.24
12
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European Journal of Inorganic Chemistry
Scheme 6. Plausible mechanism of dimerization of diphenylacetylene (L = SMe2-C2B9H10).
Reductive amination of aldehydes and ketones
We extended catalytic studies by testing iridacarboranes 4b, 7, [1,1-Cl2-4-SMe2-1,2,3-
IrC2B9H10]2, and [1-(C6H6)-1,2,3-IrC2B9H11]PF6 in the model reductive amination reaction
without an external hydrogen source between p-anisidine and p-methylbenzaldehyde.25
The reductive amination was attempted in a number of solvents to test the effect of
solvent properties (Table 2). Best results were obtained when ethereal solvents were used (THF,
diethyl ether and dioxane) as well as ethyl acetate followed by solvent free conditions, methanol,
isopropanol, toluene and then acetonitrile (Table 2, entry 4−12). No big impact of solvent was
found. To exclude the possibility of the water-gas shift reaction and Meerwein-Ponndorf-Verley
type reaction we chose dry THF as the solvent.
The effect of the temperature was investigated. Increasing temperature was found to have
a positive impact on the desired product yield (Table 2, entry 4, 13−16). However, if the
temperature is above 150 °C at prolonged experiment some decomposition may occur.
13
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
Increasing carbon monoxide pressure was found to have a positive impact on the desired
product yield. Usually, the reaction is working better under supercritical CO. Surprisingly, when
pressure was increased from 20 to 30 bar of CO (at room temperature) no significant changes
were found (Table 2, entry 19−20). However, when the pressure was further increased to 50 bar
the yield was increased from 63 to 81% (Table 2, entry 20−21).
Table 2. Screening of iridacarboranes as catalysts for reductive amination.
Yield 9,
[%]
Entry[a]
1
Catalyst
Solvent
THF
P, bar
30
T, °C
140
36
4b
[1,1-Cl2-4-SMe2-
1,2,3-IrC2B9H10]2
2
3
THF
THF
30
30
140
140
37
38
[1-(C6H6)-1,2,3-
IrC2B9H11]PF6
4
5
THF
MeCN
Toluene
MeOH
iPrOH
Dioxane
-
30
30
30
30
30
30
30
30
30
30
30
30
30
5
140
140
140
140
140
140
140
140
140
120
130
150
160
140
140
140
140
53
34
40
45
37
53
35
45
48
37
40
45
38
20
30
63
63
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
7
6
7
8
9
10
11
12
13
14
15
16
17[b]
18[b]
19[b]
20[b]
EtOAc
Et2O
THF
THF
THF
THF
THF
THF
10
20
30
THF
THF
14
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
21[b]
THF
50
140
81
7
[a] 0.2 mmol scale, 100 mol % of p-tolualdehyde, 100 mol % of p-anisidine, see general
i
procedure. Yields were determined by GC. MeCN, Et2O, PrOH, MeOH, 1,4-dioxane, toluene,
EtOAc, were used as received, THF was distilled over sodium with benzophenone. [b] 0.2 mmol
scale, 100 mol % of p-tolualdehyde, 200 mol % of p-anisidine.
The iridium complex 7 can catalyze reductive amination reaction with carbon monoxide
not only between aromatic aldehyde and aromatic amines. Secondary amines are working as well
(Table 3, entry 1−3). Primary aliphatic amines are also suitable for the reaction (Table 3, entry
4). Even aromatic ketones can react (Table 3, entry 5). Aliphatic ketones seem to be quite active
substrates for the reductive amination catalyzed by 7 (Table 3, entry 6).
Table 3. Substrate scope for reductive amination catalyzed by 7.
Entry[a]
1
R1
R2
R3
R4
H
Yield, [%]
60
Bn
Tol
2
3
Bn
Bu
Tol
Tol
H
H
85
64
4
5
6
CH3(CH2)11
PMP
H
H
H
Tol
Ph
H
68
68
85
CH3
CH3
PhCH2CH2
PMP
[a] p-tolyl = Tol, p-methoxyphenyl = PMP, benzyl = Bn.
Conclusion
Reactions of the C-substituted anion [7-SMe2-7,8-C2B9H10]– with metal complexes (e.g.
[(cod)MCl]2 (M = Rh, Ir) and [Cp*RuCl]4) are accompanied by room temperature polyhedral
rearrangement of the carborane ligand with migration of the substituted carbon atom from the
metal bonded pentagonal face resulting in the formation of 1,2,8-metalladicarbollides. DFT-
15
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
calculations suggest that the rearrangement proceeds via rotation of one CB2 face with one
transition state (activation barrier is ca. 28 kcal mol–1). Reaction of
(cyclooctadiene)iridacarborane 1 with anhydrous hydrohalic acids HX (X = Cl, Br, I) was shown
to be efficient method for the synthesis of the iridium halide complexes 4a–c. Bromides in 4b
can be easily replaced by cyclopentadienyl and carborane anions making it a convenient synthon
of the dicationic species [8-SMe2-1,2,8-IrC2B9H10]2+. Comparison of X-ray diffraction data for
metalladicarbollides with different cage carbon positions and DFT-calculations suggest that the
metal bonding with the CB4 pentagonal face in these compounds is stronger than with the C2B3
face owing to higher orbital contribution. In accordance with electron acceptor properties of the
SMe2-substituted carborane ligands, 4b and 7 do not catalyze the oxidative coupling of benzoic
acid with alkynes, but reveal moderate catalytic activity in dimerization of diphenylacetylene
giving 1,2,3-triphenylnaphthalene. Iridacarborane 7 can catalyze reductive amination reaction
with carbon monoxide between aromatic and aliphatic ketones, aromatic aldehydes and primary
and secondary amines with both aliphatic and aromatic nature. Moreover, dioxalyl, cyclopropyl,
N-benzyl and chlorine moieties are suitable for the reaction.
Experimental
General: The reactions were carried out under an inert atmosphere in dry solvents. The isolation
of products was conducted in air. Starting materials Tl[7-SMe2-7,8-C2B9H10],8 Tl[Tl(η-7,8-
C2B9H11)],26 [(cod)RhCl]2,27 [Cp*RuCl]4,28 and 77 were prepared as described in the literature.
11
1H and B{1H} NMR spectra (δ in ppm) were recorded on a Bruker Avance-400 spectrometer
operating at 400.13 and 128.38 MHz, respectively.
Synthesis of 1-cod-8-SMe2-1,2,8-RhC2B9H10 (2): A mixture of [(cod)RhCl]2 (50 mg, 0.10
mmol), Tl[7-SMe2-7,8-C2B9H10] (88 mg, 0.22 mmol) and THF (3 ml) was stirred overnight. The
precipitate of TlCl was filtered off and the filtrate was evaporated in vacuo. The residue was
chromatographed on SiO2 with CH2Cl2 as eluent. After evaporation of the solvent, complex 2
was crystallized from THF − petroleum ether as a yellow crystalline solid. Yield 67 mg (82%).
Anal. Calc. for C12H28B9SRh (%):C, 35.62; H, 6.98; B, 24.05. Found: C, 35.47; H, 7.19; B,
1
23.98. H{11B} NMR ([D6]acetone): δ = 4.56–4.48 (m, 2H, cod), 4.38–4.30 (m, 2H, cod), 3.01
(s, 3H, SMe), 2.97 (s, 3H, SMe), 2.73 (s, 1H, B(12)H), 2.50 (s, 1H, CHcage), 2.49–2.26 (m, 8H,
cod), 2.21 (s, 1H, B(5)H), 2.16 (s, 1H, B(7)H), 2.06 (s, 1H, B(9)H), 1.62 (s, 1H, B(11)H), 1.42
(s, 2H, B(3)H, B(6 or 4)H), 1.30 (s, 1H, B(6 or 4)H), 1.18 (s, 1H, B(10)H). 11B{1H} NMR
16
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European Journal of Inorganic Chemistry
([D6]acetone): δ = −6.3 (1В, B(5)), −8.2 (2В, B(6,4)), −11.1 (1В, B(9)), −14.9 (1B, B(3)), −16.2
(1В, B(12)), −21.7 (1В, B(11)), −22.9 (1В, B(10)), −24.9 (1B, B(7)).
Synthesis of 1-Cp*-8-SMe2-1,2,8-RuC2B9H10 (3): A suspension of [Cp*RuCl]4 (30 mg, 0.028
mmol) and Tl[7-SMe2-7,8-C2B9H10] (45 mg, 0.113 mmol) was stirred in THF (5 ml) overnight.
The precipitate of TlCl was filtered off and the filtrate was evaporated in vacuo. Crystallization
of the residue from the mixture of CH2Cl2 − petroleum ether at −4 °C gave 3 as colourless
crystalline powder, yield was 32.5 mg (69%). Anal. Calc. for C14H31B9RuS (%): C, 39.12; H,
1
7.27; B, 22.64. Found: C, 39.38; H, 7.55; B, 22.57. H (CDCl3): δ = 2.85 (s, 3H, SMe), 2.81 (s,
11
3H, SMe), 1.95 (s, 15H, Cp*). B{1H} NMR (CDCl3): δ = −1.8 (1В), −7.5 (3В), −12.6 (1В),
−17.2 (1В), −23.5 (2В), −25.8 (1В).
Synthesis of [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 (4a–c): The mixture of [(cod)IrCl]2 (81 mg,
0.11 mmol) and Tl[7-SMe2-7,8-C2B9H10] (105 mg, 0.26 mmol) in THF (3 ml) was stirred for 3 h.
The precipitate of TlCl was filtered off and the filtrate was evaporated in vacuo. The residue was
dissolved in CH2Cl2 (5 ml) and passed through the layer of SiO2. The solvent was removed in
vacuo, the residue containing 1-cod-8-SMe2-1,2,8-IrC2B9H10 (1) was dissolved in acetic
anhydride (6 ml) and the concentrated HX (1 ml) was added (an inert atmosphere is not
necessary). The reaction mixture was stirred overnight. Water (20 ml) was added and the yellow
or orange precipitate formed was filtered off, washed with water, iPrOH, acetone, and ether.
4a, X = Cl, 70% yield. Anal. Calc. for C4B9H16SCl2Ir: C, 10.52; H, 3.53; B, 21.31. Found: C,
10.56; H, 3.27; B, 19.73. 1H NMR ([D6]dmso): δ = 3.10 (s, 3H, SMe2), 3.07 (s, 3H, SMe2), 3.06
(s, 1H, CHcage). 11B{1H} NMR ([D6]dmso): δ = −0.55, −11.79, −21.50.
4b, X = Br, 72% yield. Anal. Calc. for C4B9H16SBr2Ir: C, 8.81; H, 2.96; B, 17.83. Found: C,
1
8.99; H, 2.89; B, 17.67. H NMR ([D6]dmso): δ = 3.11 (s, 3H, SMe2), 3.07 (s, 3H, SMe2).
11B{1H} NMR ([D6]dmso): δ = 1.42, −10.21, −19.87.
4c, X = I, 53% yield. Anal. Calc. for C4B9H16SI2Ir: C, 7.51; H, 2.52; B, 15.21; Ir, 30.05. Found:
1
C, 8.12; H, 2.39; B, 14.85; Ir, 31.50. H NMR ([D6]dmso): δ = 3.18 (s, 1H, CHcage), 3.11 (s, 3H,
SMe2), 3.06 (s, 3H, SMe2). 11B{1H} NMR ([D6]dmso): δ = 1.29, −9.13, −19.06.
Synthesis of 8’-SMe2-1,1’-Ir(2,3-C2B9H11)(2’,8’-C2B9H10) (5): The mixture of 4b (72 mg, 0.07
mmol) and Tl[Tl(η-7,8-C2B9H11)] (87 mg, 0.16 mmol) in acetonitrile was stirred for three days.
The precipitate of TlBr was filtered off and the filtrate was evaporated in vacuo. The residue was
chromatographed on SiO2 with CH2Cl2 as eluent. A colorless band was collected and the solvent
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European Journal of Inorganic Chemistry
was removed in vacuo. The residue was reprecipitated by petroleum ether from acetone to give 5
as a white solid. Yield 33 mg (44 %). Anal. Calc. for C6B18H27SIr: C, 13.91; H, 5.25; B, 37.56;
Ir, 37.10. Found: C, 14.11; H, 5.22; B, 36.74; Ir, 37.14. 1H NMR ([D6]acetone): δ = 4.03 (s, 1H,
CHcage), 3.97 (s, 1H, CHcage), 3.42 (s, 1H, CHcage), 3.34 (s, 3H, SMe2), 3.32 (s, 3H, SMe2).
11B{1H} NMR ([D6]acetone): δ = 2.23 (s, 1B), −2.16 (s, 1B), −2.68 (s, 1B), −3.43 (s, 1B), −7.81
(s, 1B), −8.93 (s, 1B), −9.70 (s, B), −11.35 (s, 1B), −12.46 (s, 1B), −18.33 (s, 1B), −19.42 (s,
1B), −20.01 (s, 1B), −22.47 (s, 1B), −24.15 (s, 1B).
Synthesis of 1-Cp-8-SMe-1,2,8-IrC2B9H10 (6): The mixture of 4b (72 mg, 0.07 mmol) and
CpTl (41 mg, 0.15 mmol) in acetonitrile (3 ml) was stirred overnight. The precipitate of TlBr
was filtered off and the filtrate was evaporated in vacuo. The residue was chromatographed on
SiO2 with the mixture of CH2Cl2/petroleum ether (2:1) as eluent. A colorless band was collected
and the solvent was removed in vacuo. The residue was recrystallized by petroleum ether from
CH2Cl2 to give 6 as a white crystalline solid. Yield 46 mg (81 %). Anal. Calc. for C8B9H18SIr: C,
1
22.05; H, 4.16; B, 22.33; Ir, 44.11. Found: C, 21.82; H, 4.04; B, 22.27; Ir, 44.1. H NMR
([D6]acetone): δ = 5.94 (s, 5H, Cp.), 3.62 (s, 1H, CHcage), 2.21 (s, 3H, SMe). 11B{1H} NMR
([D6]acetone): δ = 0.94 (s, 1B), −7.59 (s, 1B), −8.59 (s, 1B), −9.70 (s, 1B), −11.36 (s, 1B),
−11.74 (s, 1B), −18.40 (s, 1B), −22.56 (s, 1B), −21.92 (s, 1B).
Dimerization of diphenylacetylene: A mixture of diphenylacetylene (100.5 mg, 0.56 mmol), 4b
or 7 (6.5 mg, 0.006 mmol), Ag2CO3 (95.7 mg, 0.57 mmol) and ortho-xylene (2 ml) was refluxed
with vigorous stirring for 10 h. The precipitate was centrifuged off, the solvent was removed in
vacuo and the residue was extracted with diethyl ether. The extract was chromatographed on
column with silica gel (1 × 15 cm). Unreacted diphenylacetylene was washed off with petroleum
ether. The second pale-yellow band was collected and the solvent was removed in vacuo to give
1
1,2,3-triphenylnaphthalene as a crystalline solid. Yield 20−24 %. EI-MS; m/z: 356.2 [M+]. H
NMR (CDCl3):  = 7.98 (s, 1 H), 7.97 (d, 1 H), 7.61 (d, 1 H), 7.55 (t, 1 H), 7.43 (t, 1 H), 7.18–
7.29 (m, 10 H), 6.96–6.97 (m, 3H), 6.89–6.90 (m, 3H) (cf.29).
4-methoxy-N-(4-methylbenzyl)aniline (9). Complex 7 (1.3 mg, 1 mol %, 2.8 µmol), p-
anisidine (70.0 mg, 200 mol %, 0.568 mmol) and p-tolualdehyde (34 µL, 100 mol %, 0.284
mmol) were charged into a glass vial in a 10 mL stainless steel autoclave. 0.33 mL of THF(abs)
was added and the autoclave was sealed, flushed three times with 10 bar of CO, and then charged
with 50 bar CO. The reactor was placed into an oil bath preheated to 140 °C. After 20 h of
heating, the reactor was cooled to room temperature and depressurized. The reaction mixture was
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
transferred into a flask and the autoclave was washed with dichloromethane (4x1mL); combined
solvents were removed on a rotary evaporator. 81% yield by GC. 1H NMR (CDCl3): δ = 7.28 (d,
J = 7.8 Hz, 2H), 7.17 (d, J = 7.8 Hz, 2H), 6.80 (d, J = 8.9 Hz, 2H), 6.62 (d, J = 8.9 Hz, 2H), 4.25
(s, 2H), 3.76 (s, 3H), 2.36 (s, 3H).
N-((1,3-dioxolan-4-yl)methyl)-N-benzyl-1-(p-tolyl)methanamine. Complex 7 (1.1 mg, 2 mol
%, 2.4 µmol), N-((1,3-dioxolan-4-yl)methyl)-1-phenylmethanamine (38 µL, 200 mol %, 0.240
mmol) and p-tolualdehyde (14 µL, 100 mol %, 0.120 mmol) were charged into a glass vial in a
10 mL stainless steel autoclave. 0.23 mL of THF(abs) was added and the autoclave was sealed,
flushed three times with 10 bar of CO, and then charged with 50 bar CO. The reactor was placed
into an oil bath preheated to 140 °C. After 20 h of heating, the reactor was cooled to room
temperature and depressurized. The reaction mixture was transferred into a flask and the
autoclave was washed with dichloromethane (4x1mL); combined solvents were removed on a
rotary evaporator. 60% yield by NMR. 1H NMR (CDCl3): δ = 7.42–7.22 (m, 7H), 7.15 (d, J = 7.8
Hz, 2H), 4.94 (s, 1H), 4.84 (s, 1H), 4.24–4.11 (m, 1H), 3.90 (t, J = 7.3 Hz, 1H), 3.82–3.68 (m,
2H), 3.62–3.50 (m, 2H), 3.48–3.41 (m, 1H), 2.76–2.66 (m, 1H), 2.66–2.56 (m, 1H), 2.35 (s, 3H).
N-benzyl-1-(2,2-dichlorocyclopropyl)-N-(4-methylbenzyl)methanamine. Complex 7 (0.8 mg,
2 mol %, 1.8 µmol), N-benzyl-1-(2,2-dichlorocyclopropyl)methanamine (30 µL, 200 mol %,
0.175 mmol) and p-tolualdehyde (10 µL, 100 mol %, 0.087 mmol) were charged into a glass vial
in a 10 mL stainless steel autoclave. 0.17 mL THF(abs) was added and the autoclave was sealed,
flushed three times with 10 bar of CO, and then charged with 50 bar CO. The reactor was placed
into an oil bath preheated to 140 °C. After 20 h of heating, the reactor was cooled to room
temperature and depressurized. The reaction mixture was transferred into a flask and the
autoclave was washed with dichloromethane (4x1mL); combined solvents were removed on a
1
rotary evaporator. 85% yield by NMR. H NMR (CDCl3): δ = 7.38 (d, J = 7.5 Hz, 2H), 7.35–
7.20 (m, 5H), 7.13 (d, J = 7.5 Hz, 2H), 3.82–3.64 (m, 2H), 3.62–3.49 (m, 2H), 2.79–2.56 (m,
2H), 2.33 (s, 3H), 1.89–1.70 (m, 1H), 1.57 (dd, J = 10.7, 6.9 Hz, 1H), 1.04 (d, J = 7.4 Hz, 1H),
1.02 (d, J = 7.6 Hz, 1H).
N-((2,2-dichlorocyclopropyl)methyl)-N-(4-methylbenzyl)butan-1-amine. Complex 7 (1.2 mg,
2 mol %, 2.6 µmol), N-((2,2-dichlorocyclopropyl)methyl)butan-1-amine (42 µL, 200 mol %,
0.262 mmol) and p-tolualdehyde (15 µL, 100 mol %, 0.131 mmol) were charged into a glass vial
in a 10 mL stainless steel autoclave. 0.25 mL THF(abs) was added and the autoclave was sealed,
flushed three times with 10 bar of CO, and then charged with 50 bar CO. The reactor was placed
19
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into an oil bath preheated to 140 °C. After 20 h of heating, the reactor was cooled to room
temperature and depressurized. The reaction mixture was transferred into a flask and the
autoclave was washed with dichloromethane (4x1mL); combined solvents were removed on a
rotary evaporator. 64 % yield by NMR. 1H NMR (CDCl3): δ = 7.24 (d, J = 7.8 Hz, 2H), 7.13 (d, J
= 7.8 Hz, 2H), 3.69 (d, J = 13.6 Hz, 1H), 3.55 (d, J = 13.6 Hz, 1H), 2.80– 2.70 (m, 1H), 2.68 –
2.45 (m, 4H), 2.35 (s, 3H), 1.83–1.71 (m, 1H), 1.66–1.55 (m, 1H), 1.55–1.44 (m, 1H), 1.42–1.26
(m, 2H), 1.15–1.01 (m, 1H), 0.90 (t, J = 7.3 Hz, 3H).
N-(4-methylbenzyl)dodecan-1-amine. Complex 7 (1.4 mg, 2 mol %, 3.1 µmol), dodecylamine
(56.7 mg, 200 mol %, 0.306 mmol) and p-tolualdehyde (18 µL, 100 mol %, 0.153 mmol) were
charged into a glass vial in a 10 mL stainless steel autoclave. 0.29 mL THF(abs) was added and
the autoclave was sealed, flushed three times with 10 bar of CO, and then charged with 50 bar
CO. The reactor was placed into an oil bath preheated to 140 °C. After 20 h of heating, the
reactor was cooled to room temperature and depressurized. The reaction mixture was transferred
into a flask and the autoclave was washed with dichloromethane (4x1mL); combined solvents
were removed on a rotary evaporator. 68% yield by NMR. 1H NMR ([D6]dmso): δ = 7.17 (d, J =
7.9 Hz, 2H), 7.07 (d, J = 7.9 Hz, 2H), 3.59 (s, 2H), 2.41 (t, J = 7.0 Hz, 2H), 2.25 (s, 3H), 1.47–
1.06 (m, 20H), 0.84 (t, J = 6.6 Hz, 3H).
4-methoxy-N-(1-phenylethyl)aniline. Complex 7 (0.8 mg, 2 mol %, 1.7 µmol), p-anisidine
(21.5 mg, 200 mol %, 0.175 mmol) and acetophenone (10 µL, 100 mol %, 0.087 mmol) were
charged into a glass vial in a 10 mL stainless steel autoclave. 0.17 mL THF(abs) was added and
the autoclave was sealed, flushed three times with 10 bar of CO, and then charged with 50 bar
CO. The reactor was placed into an oil bath preheated to 140 °C. After 20 h of heating, the
reactor was cooled to room temperature and depressurized. The reaction mixture was transferred
into a flask and the autoclave was washed with dichloromethane (4x1mL); combined solvents
were removed on a rotary evaporator. 68 % yield by NMR. 1H NMR (CDCl3): δ = 7.41–7.19 (m,
5H), 6.70 (d, J = 8.9 Hz, 2H), 6.47 (d, J = 8.9 Hz, 2H), 4.42 (q, J = 6.6 Hz, 1H), 3.70 (s, 3H),
1.50 (d, J = 6.6 Hz, 3H).
4-methoxy-N-(4-phenylbutan-2-yl)aniline. Complex 7 (1.1 mg, 2 mol %, 2.4 µmol), p-
anisidine (29.6 mg, 200 mol %, 0.240 mmol) and benzylacetone (18 µL, 100 mol %, 0.120
mmol) were charged into a glass vial in a 10 mL stainless steel autoclave. 0.22 mL THF(abs)
was added and the autoclave was sealed, flushed three times with 10 bar of CO, and then charged
with 50 bar CO. The reactor was placed into an oil bath preheated to 140 °C. After 20 h of
20
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European Journal of Inorganic Chemistry
heating, the reactor was cooled to room temperature and depressurized. The reaction mixture was
transferred into a flask and the autoclave was washed with dichloromethane (4x1mL); combined
solvents were removed on a rotary evaporator. 85 % yield by NMR. 1H NMR (CDCl3): δ = 7.45–
7.13 (m, 5H), 6.79 (d, J = 8.8 Hz, 2H), 6.54 (d, J = 8.8 Hz, 2H), 3.81 (s, 3H), 3.52–3.39 (m, 1H),
3.27–3.05 (m, 1H), 2.79 (t, J = 7.9 Hz, 2H), 2.02–1.72 (m, 2H), 1.22 (d, J = 6.3 Hz, 3H).
X-ray crystallography: Crystals of 2 were grown by a gas-phase diffusion of the petroleum
ether in a solution of the complex in THF. Crystals of 3, 5 and 6 were obtained by slow diffusion
in two-layer system, petroleum ether and a solution of the complex in CH2Cl2. X-ray diffraction
data were collected at 120 K with a Bruker APEX2 CCD diffractometer, using graphite
monochromated Mo-K radiation ( = 0.71073 Å, -scans). The structures were solved by
direct method and refined by the full-matrix least-squares against F2 in anisotropic
approximation for non-hydrogen atoms. Hydrogen atoms in the carborane moiety were found in
difference Fourier synthesis while the positions of others were calculated and then refined in the
isotropic approximation within the riding model. Crystal data and structure refinement
parameters for 2, 3, 5 and 6 are given in Table 4. All calculations were performed using the
SHELXTL PLUS 5.0.30 CCDC 1544887 (for 6), CCDC 1544888 (for 2), CCDC 1544889 (for 5)
and CCDC 1544890 (for 3) contain the supplementary crystallographic data for this paper. These
data can be obtained free of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Computational details: The plausible mechanism of the formation of 2 was calculated
using PBE exchange-correlation functional as implemented in Priroda 16 code.31 The all-electron
triple-ζ basis set L2 augmented by two polarization functions was used.32 Frequency calculations
were performed to confirm the nature of the stationary points to yield one imaginary frequency
for the transition state and none for the minima. The nature of the transition state was
investigated by the calculations of the Intrinsic Reaction Coordinate (IRC).33 The bonding
interactions were studied by means of Morokuma-Ziegler energy decomposition analysis34 at the
BP86/TZP level using the ADF 2010.01 program package.35 The ChemCraft program36 was used
for molecular modeling and visualization.
Supporting Information (see footnote on the first page of this article): Details of DFT
calculations for complex [1,1’-Ir(2,3-C2B9H11)(2’,8’-C2B9H11)]– (atomic coordinates for
optimized geometry and energy data), frequency animation of 2,3→2,8 carbon atoms
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European Journal of Inorganic Chemistry
1
1
rearrangement as well as 11B{1H}–11B{1H} COSY, H−11B{1H} HETCOR and H with CW
decoupling on 11B nuclei NMR spectra for complex 2.
Acknowledgements: This work was supported by the Russian Foundation for Basic Research
(projects 15-03-04057, 15-03-02548 and 16-33-00166) and the Council of the President of the
Russian Federation (Grant for Young Scientists No. МК-520.2017.3). O.C. and D.C. thanks the
Ministry of Education and Science of the Russian Federation (Agreement number
02.a03.21.0008).
22
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European Journal of Inorganic Chemistry
Table 4. Crystal data and structure refinement parameters for 2, 3, 5 and 6
Compound
2
C12H28B9RhS
404.60
3
C15H33B9Cl2RuS
514.73
5
6
Empirical formula
Formula mass
C6H27B18IrS
C8H18B9IrS
435.77
120
518.11
Temperature [K]
Crystal size [mm]
120
120
120
0.20  0.25  0.25
0.15  0.15  0.35
0.25  0.25  0.30
0.10  0.10  0.35
Crystal system
Space group
a [Å]
monoclinic
P21/c
orthorhombic
Pbca
orthorhombic
P212121
10.9524(9)
12.8215(11)
13.5382(12)
90
triclinic
P-1
10.4094(6)
14.0247(9)
12.5624(8)
90
16.6334(16)
13.3459(13)
20.497(2)
90
7.4966(12)
8.7522(14)
12.209(2)
70.604(3)
79.914(3)
70.026(3)
708.4(2)
2
b [Å]
c [Å]
 []
104.4540(10)
90
90
90
 []
90
90
 []
V [Å3]
1775.92(19)
4
4550.1(8)
8
1901.1(3)
4
Z
3
D(calcd.) [g cm ]
1.513
1.503
1.810
2.043
F(000)
824
56
2096
58
984
58
408
58
2
[]
Linear absorption,  [cm–1]
max
10.67
10.16
71.19
95.41
23
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
Collected reflections
Independent reflections
Observed reflections [I >2(I)]
Parameters
18055
85414
22652
10390
4292 (Rint = 0.0562)
3528
6051 (Rint = 0.1281)
4465
5061 (Rint = 0.0651)
4660
3657 (Rint = 0.0211)
3518
250
261
235
173
R1 (on F for obs. refls.)
wR2 (on F2 for all refls.)
GOOF
0.0298
0.0527
0.0301
0.0167
0.0630
0.1515
0.0477
0.0420
1.032
1.034
1.006
1.049
3
Largest diff. peak and hole [e Å ]
0.521 and −0.388
2.319 and −1.024
1.023 and −1.480
1.173 and −1.568
24
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10.1002/ejic.201700498
European Journal of Inorganic Chemistry
Table of Contents entry
Key Topic
Iridacarboranes
A short text
Iridium halide complexes [1,1-X2-8-SMe2-1,2,8-IrC2B9H10]2 (X = Cl, Br, I) were synthesized by
reaction of the cyclooctadiene derivative 1-cod-8-SMe2-1,2,8-IrC2B9H10 with anhydrous
hydrohalic acids HX. These complexes proved to be effective catalysts for the dimerization of
alkynes and the reductive amination of aldehydes and ketones.
Graphical Element
References
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European Journal of Inorganic Chemistry
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