1,3,2-diselenaborolanes with an annelated dicarba-closo-dodecaborane(12) unit: Synthesis, molecular structure and reactivity

Article abstract of DOI:10.1002/ejic.201100563

Exchange reactions of 2,2-dimethyl-1,3-diselena-2-silacyclopentane and 2,2,3,3-tetramethyl-1,4-diselena-2,3-disilacyclohexane, as the 4,5-and 5,6-[1,2-dicarba-closo-dodecaborano(12)] derivatives, respectively, with boron trihalides (BCl₃, BBr

Full text of DOI:10.1002/ejic.201100563

FULL PAPER
DOI: 10.1002/ejic.201100563
1,3,2-Diselenaborolanes with an Annelated Dicarba-closo-dodecaborane(12) Unit:
Synthesis, Molecular Structure and Reactivity
Bernd Wrackmeyer,*[a] Elena V. Klimkina,[a] and Wolfgang Milius[a]
Dedicated to Professor Max Herberhold on the occasion of his 75th birthday
Keywords: Main group elements / Carboranes / Boron / Selenium / Heterocycles / Density functional calculations /
Multinuclear NMR spectroscopy
Exchange reactions of 2,2-dimethyl-1,3-diselena-2-silacyclo-
pentane and 2,2,3,3-tetramethyl-1,4-diselena-2,3-disilacy-
structural analysis. Attempts to synthesize the boron fluoride
failed, and the methoxy derivative was obtained in a mixture
clohexane, as the 4,5- and 5,6-[1,2-dicarba-closo-dodecabor- with a decomposition product. The gas-phase structures of
ano(12)] derivatives, respectively, with boron trihalides (BCl3,
BBr3, BI3) and dichlorides (PhBCl2, iPr2NBCl2) afford the cor-
responding 1,3,2-diselenaborolanes in essentially quantita-
tive yield. The products were characterized in solution by
multinuclear magnetic resonance spectroscopy (1H, 11B, 13C,
29Si, 77Se), and for two products, in the solid state by X-ray
all relevant products were optimized by DFT hybrid methods
[RB3LYP/6-311+G(d.p) level of theory], and NMR parameters
(shielding constants and spin–spin coupling constants) were
calculated. The calculated data compare well with experi-
mental data, both for the structures and the NMR spectro-
scopic parameters.
Introduction
The multifaceted chemistry of 1,2-dicarba-closo-dodeca-
borane(12) (“ortho-carborane”)[1,2] is based to a great extent
on metalation, for example, 1,2-dilithiation,[1–3] taking ad-
vantage of the reactive metal–carbon bonds. Thus, insertion
of chalcogens into the C–Li bonds is an obvious option,
which was originally developed and exploited for sul-
fur.[3c–3e] The development of selenium chemistry in this
field appears to be particularly attractive, considering the
rather favorable NMR spectroscopic properties of 77Se (I =
1/2; nat. abund. 7.58%).[4] The dianion A (used as its lith-
ium salt) has already proved valuable as a versatile ligand
in transition metal chemistry[5–8] and applications in main-
group-element chemistry are also emerging.[9–15] In our ex- Scheme 1. 1,2-Diselenolato-1,2-dicarba-closo-dodecaborane(12) di-
perience, it is preferable to use A after careful isolation[9] to
anion A as its dilithium salt, the precursor to cyclic selenasilanes 1
and 2.
avoid side reactions. Observing these precautions, the cyclic
selenasilanes 1 and 2[9] could be obtained in good yield
(Scheme 1) as useful starting materials for further syntheses.
gent A gives rise to problems (e.g., diethyl ether cleav-
age).[14] Therefore, in the present work, we report on the
exchange reactions of the cyclic selenasilanes 1 and 2 with
boron halides aiming for the synthesis of the first 1,3,2-
diselanaborolanes. With the exception of 1,2,4,3,5-triselena-
diborolanes,[16] and the poorly characterized iodide
(MeSe)2B-I,[17] no other noncyclic or cyclic boron halides
containing two B–Se bonds are known. The products ob-
served or obtained here were studied by multinuclear mag-
netic resonance spectroscopy, and in two cases by X-ray
structural analysis. Gas phase geometries were optimized
As part of the main group chemistry of A, the synthesis
of cyclic borane derivatives presents a major challenge. So
far, the products derived from A, structurally characterized
in solution and in the solid state, contain tetracoordinate
boron.[12,14] It was shown for reactions of A with boron
halides that the unavoidable presence of diethyl ether in rea-
[a] Laboratorium für Anorganische Chemie, Universität Bayreuth,
95440 Bayreuth, Germany
Fax: +49-921-552157
E-mail: b.wrack@uni-bayreuth.de
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for many of the products by DFT hybrid methods, and B(OPh)3 to this mixture shifted the equilibrium into the
NMR parameters (chemical shifts and spin–spin coupling direction of the phenoxy derivative 8 (Scheme 3) ac-
constants) were calculated and compared with experimental companied by slow decomposition.
data.
To obtain better evidence for the methoxy derivative, the
reaction of 5 with B(OMe)3 was studied (Scheme 4). The
NMR spectra of the reaction mixture showed the presence
of the desired compound 9 along with decomposition prod-
ucts, of which 10 could be identified by NMR spectroscopy.
It cannot be excluded that B(OMe)3 contained traces of
MeOH.
Results and Discussion
Exchange Reactions of the Selenasilanes 1 and 2 with
Boron Halides
In a previous study,[9] the cyclic disilane derivative 1 was
found to be somewhat more reactive than 2 in exchange
reactions with chlorosilanes. Therefore, both silanes 1 and
2 are attractive starting materials to explore exchange reac-
tions with boron halides (Scheme 2). All reactions pro-
ceeded smoothly to afford the 1,3,2-diselanaborolanes in es-
sentially quantitative yield as air- and moisture-sensitive
oils (4, 5) or solids (3, 6, 7). The progress of the reactions
was conveniently monitored by 29Si NMR spectroscopy, fol-
lowing the changes in the intensities of the 29Si NMR sig-
nals for 1 or 2 and Me4Si2X2 or Me2SiX2, respectively. By
contrast, B(OMe)3 did not react with 1 at ambient tempera-
ture. Heating of the mixture in toluene led to decomposi-
tion.
The reaction of 1 or 2 with MeOBCl2 or PhOBBr2 gave
the boron halides 5 and 6 instead of the methoxy or phen-
oxy derivatives, respectively. Addition of an excess of B(OMe)3.
Scheme 4. Exchange reaction of the boron chloride
5 with
Scheme 2. Synthesis of 1,3,2-diselenaborolanes 3–7 by exchange reactions of selenasilanes with the respective boron halides.
Scheme 3. Exchange reactions of 1 or 2 with MeOBCl2 and PhOBBr2.
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1,3,2-Diselenaborolanes
Scheme 5. Products identified in the reaction of 1 and 2 with BF3–OEt2.
Various attempts to prepare the boron fluoride analo- ane) NMR signals, the 11B NMR spectra clearly indicate
gous to 5–7 were unsuccessful; the treatment of 1 or 2 with the presence of three-coordinate boron, and each δ11B value
a solution of gaseous BF3 in toluene gave decomposition is typical of the effect exerted by the respective substituent
products of which only the diselenol 1,2-(HSe)2-1,2- at the boron atom in the 1,3,2-diselenaborolane.[18] The
C2B10H10 [12] (11) could be identified. The reaction of 1 with neighborhood to selenium should give rise to one-bond
BF3–OEt2 proceeded slowly after heating to give Me4Si2F2 77Se–11B spin–spin coupling. Although the 11B NMR sig-
along with a mixture of three products 11–13 without B–Se nals are somewhat broad, 77Se satellites are visible under
bonds. The analogous reaction of 2 proceeded in a similar certain conditions in the cases of 6 and 7 (Figure 1). The
way, and the compounds 12, 13, and 14 as a mixture, all 77Se NMR spectra are more enlightening in this respect,
without B–Se bonds, could be identified by NMR spec- since at least in the cases of the boron halides 5–7, the 77Se
troscopy (Scheme 5). A final attempt failed to convert 5 by NMR signals are split into partially relaxed 1:1:1:1 quartets
treatment with SbF3 into the corresponding fluoride.
(Figure 1). In the cases of 3, 4, and 8, splitting due to 77Se–
The proposed structures of 3–9 in solution follow conclu- 11B spin–spin coupling is not resolved in the 11B or 77Se
sively from the characteristic NMR spectroscopic data set NMR spectra. The 77Se NMR signals for 3, 4, and 8 appear
(Table 1). In addition to the typical set of four 11B(carbor- as broadened singlets. The 77Se NMR spectrum of 9 (Fig-
Table 1. 13C, 11B, and 77Se NMR spectroscopic data[a] of the carborane derivatives 3–9.
3 (R = Ph)
4 (R = iPr2N)
5 (X = Cl)
6 (X = Br)
7 (X = I)
8 (R = OPh) 9 (R = OMe)
[D8]toluene CD2Cl2
CD2Cl2
243 K
[D8]toluene
298 K
[D8]toluene [D8]toluene [D8]toluene [D8]toluene [D8]toluene
[D8]toluene
298 K
298 K
298 K
238 K
298 K
298 K
298 K
298 K
69.7
δ13C[C(1,2)] 75.6 [10.6]
75.7 [10.4]
[141.0]
74.9
71.0
68.9, 73.2
73.5 [10.2]
[137.8]
75.7
79.7 [10.1]
[142.1]
69.5
[140.4]
[138.2]
Other
δ13C data
Ph:
Ph:
Ph:
NMe2:
NMe2:
19.8, 22.3
(Me),
45.6, 60.6
(NCH)
–
–
–
OPh:
OMe:
60.3 [10.4]
128.8 (Cm), 129.2 (Cm),
128.6 (Cm),
133.8 (Cp),
133.7 (Co),
132.9 [br] (Ci)
21.7 (Me)
53.2 (br)
(NCH)
118.5 (Cm),
126.2 (Cp),
130.4 (Co)
156.3 (Ci)
133.6 (Cp),
133.8 (Co)
[9.0],
134.2 (Cp),
134.0 (Co)
[8.6],
n.o. (Ci)
n.o. (Ci)
δ11B(BSe)
76.2
76.3
n.o.
45.7
n.o.
68.6
64.7 [b]
52.2 (98.0)
55.5
53.9
h1/2 = 71 Hz h1/2 = 70 Hz h1/2 = 75 Hz h1/2 = 180 Hz h1/2 = 120 Hz
δ11B(calcd.) 82.8
δ77Se
609.9
55.0
80.6
84.6
62.1
609.7
603.6
441.5
h1/2 = 240 Hz 449.3
418.4,
622.0
(83.0)
648.2
(90.0)
694.4
(103.0)
484.6
469.6
h1/2 = 85 Hz h1/2 = 120 Hz
h1/2 = 110 Hz (65.0Ϯ10)
δ77Se(calcd.) 580.8 [–161.1] (–82.4)
407.0 [–167.9] (–83.4)
442.0 [–167.9] (–83.4)
584.9 [12]
614.1 [12]
445.3
(–80.2)
[+8.6] (3J)
[–159.7] (1J)
[a] Coupling constants nJ(77Se,13C) are given in brackets [Ϯ 0.5 Hz]; 1J(77Se,11B) in parentheses (Ϯ 0.5 Hz); [br] denotes broad 13C
1
resonances of boron-bonded carbon atoms; n.o. = not observed. [b] In hexane: δ 11B: 65.5 [BSe, J(77Se,11B) = 82 Hz].
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Figure 1. 77Se NMR and 11B NMR spectra of the 1,2-dicarba-closo-dodecaborane 5 (A), 6 (B, C), and 7 (D) at 23 °C, 10–15% solution
(0.4–0.5 mol/L).
ure 3), however, shows a partially relaxed quartet, of which (diisopropylamino)borole]}metal complexes.[20] In the case
the separation of the inner lines can just be measured to of compound 4, it is noteworthy that the barrier to rotation
1
give a coupling constant of J(77Se,11B) = 65 Hz.
is rather high, when compared with the aforementioned
The H(NCH) and 13C(NC) NMR signals of the diiso- complexes (for the borole–Cr(CO)3 complex: ΔG#
= 42
1
coal
propylamino derivative 4 are broad at room temperature, Ϯ2 kJmol–1 [20]) as shown by the evaluated[21] energy of acti-
sharpen upon heating, and change into separate signals at vation for 4 (ΔG# = 52 Ϯ2 kJmol–1).
coal
lower temperature. At low temperature, there are also two
In the 13C{1H} NMR spectrum of 9, the 13C(OMe)
signals each for the methyl groups, the 13C(carborane), as NMR signal is accompanied by 77Se satellites (Figure 3, A),
well as for the 77Se nuclei (Figure 2). This is in agreement proving the absence of fast exchange in solution. This is the
with restricted rotation about the NC(iPr) bonds and a first example of this type of vicinal coupling in boranes.
preference of the structure as determined for the crystalline The value J(77Se,13C) = 10.4 Hz represents the average for
3
material (see below). Apparently, this involves a so-called conceivable rotamers. Calculations predict a minimum in
gear-mesh mechanism.[19] This mechanism has been prop- energy for the coplanar arrangement of the atoms in the
erly analyzed for aminoboranes solely in the case of {η5-[1- Se2BOC unit, and the mean value of the calculated coupling
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1,3,2-Diselenaborolanes
Figure 2. 62.9 MHz 13C{1H} NMR and 47.7 MHz 77Se NMR spectra of 4 (in [D8]toluene) (upper trace: at 378 K, middle trace: at 298 K,
lower trace: at 238 K; given assignments follow calculated chemical shifts).
Figure 3. (A) 125.8 MHz 13C{1H} NMR spectrum of the mixture of 9 and 10 (in [D8]toluene, at 25 °C). (B) 47.7 MHz 77Se NMR
spectrum from 9 (in [D8]toluene, at 25 °C).
constants (+8.6 Hz) for the cis- (+3.1 Hz) and trans-cou- such materials for adducts. The results are shown in
pling pathways (+14.1 Hz) is close to the experimental Scheme 6 for the reaction of 5 with pyridine, 2,2Ј-bipyridine
value.
and N-methylpyrrolidine. In each case, the adduct forma-
tion is accompanied by further reactions leading mainly to
the spirocyclic borate anion 16, which we have already pre-
pared and characterized through a different route.[14] NMR
spectroscopic data (Table 2) clearly indicate the formation
of the adducts 15a and 15b, whereas no adduct was ob-
Formation of Adducts
Since the isolation of suitable crystalline materials of the
halides 5–7 turned out to be difficult, we tried to isolate
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B. Wrackmeyer, E. V. Klimkina, W. Milius
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served in the reaction of 5 with 2,2Ј-bipyridine. Crystalline ture containing 5 and pyridine, crystals of a rather insoluble
material was isolated for 15b (see below). Additional weak material were isolated in low yield. Although these crystals
11B NMR signals, typical of tetracoordinate boron atoms, were of poor quality for accurate X-ray diffraction studies,
were observed for the reaction solutions and assigned to the the data set collected allowed the deduction of at least the
boronium cations 17a (Figure 4, A) and 17b. From a mix- structural features of the boronium cation 17a.
Scheme 6. Reactions of the boron chloride 5 with pyridine, N-methylpyrrolidine and 2,2Ј-bipyridine.
Table 2. 13C, 11B, and 77Se NMR spectroscopic data[a] of the carborane derivatives 10, 12, 14–16.
10
12
14
15a
15b
16a
16b
16c
[D8]toluene
[D8]toluene
[D8]toluene
CD2Cl2
[D8]toluene [D8]toluene
CD2Cl2
76.3
[D8]toluene
76.9
CD2Cl2
76.3
δ13C[C(1,2)] 68.2 [133.0]
(SeH),
68.2 (SeH)
73.3 {–9.6}
(SeEt)
72.5 {–11.4} 73.7
72.6 {–10.5}
74.1 [8.7]
[151.7]
72.7
72.8 [161.0]
{–8.7}
(SeMe)
Other
δ13C data
Me:
11.5 [69.3]
Et:
13.6 [17.6]
26.1 [64.8]
Et:
13.5 [17.6]
26.9 [64.8]
py:
py:
C4H8NCH3:
pyH+:
127.0 (Cβ),
142.5 (Cγ),
146.5 (Cα)
C4H8N(CH3)H+: 2,2Ј-bipyH+:
125.4 (Cβ),
140.0 (Cγ),
146.9 (Cα)
126.0 (Cβ), 22.5 (Cβ),
143.4 (Cγ), 46.9 (Me),
145.9 (Cα)
23.5 (Cβ),
40.1 (Me),
54.9 (Cα)
123.5, 126.2,
141.1, 147.5,
150.9
61.1 (Cα)
δ11B(BSe)
δ77Se
–
–
–
14.0 (45.5) [b] 13.9 (45.0) 16.9 (47.6) [c]
6.0 (59.0)
6.7 (55.5)
5.9 (58.9)
350.1/54.9/
(SeH),
351.7/55.7/
(SeH),
489.3 (SeEt), 469.6
715.1 (Se–Se) (45.4)
467.6
(45.0)
435.6
477.9
(57.1)
477.6
(57.0)
477.9
(61.9)
415.4 (SeMe)
502.2 (SeEt)
δ77Se(calcd.) 292.1(SeH),
289.4 (SeH), 451.2 (SeEt), 436.7
413.6
500.7 (–81.8) [–191.5]
400.2 (SeMe)
452.2 (SeEt)
841.6 (Se–Se) (–70.0) [–18.1] [–173.7]
(–72.4) [–179.3], (for 16 (calcd.) [14]
)
437.3
(–73.0) [–179.5]
1
1
[a] Coupling constants nJ(77Se,13C) are given in brackets [Ϯ 0.5 Hz]; J(77Se,11B) in parentheses (Ϯ 0.5 Hz), J(77Se,1H) in// /Ϯ 0.5 Hz/;
1Δ10/11B[13C(1,2)] are given in braces {Ϯ 0.5 ppb},[34] isotope-induced chemical shifts Δ are given in ppb, and the negative sign denotes
1
a shift of the NMR signal of the heavy isotopomer to lower frequency. [b] δ11B (calcd.): 24.3 (–70.0). [c] δ11B (calcd.): 28.0 (–72.4)
(–73.0).
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1,3,2-Diselenaborolanes
Figure 4. 77Se NMR and 11B NMR spectra of the reaction solution obtained from the reaction of 5 with pyridine. (A) 47.7 MHz 77Se
NMR and 80.3 MHz 11B NMR spectra (in CD2Cl2, at 25 °C), the mixture of 15a and 16a (ratio 2:1) (after 2 h at room temperature in
[D8]toluene). (B) 76.2 MHz 77Se NMR and 80.3 MHz 11B NMR spectra (in CD2Cl2, at 25 °C), the mixture of 15a and 16a (ratio 9:1)
(after 1 h at –50 °C and 1 h at room temperature in [D8]toluene).
DFT Calculations of Molecular Geometries, Chemical
Since calculated shielding constants[23] for 11B, 13C, and
77Se[24] agree reasonably well with measured data, the calcu-
lated geometries are correct. Considering the large range of
δ77Se,[4] the calculated values are useful for structural as-
signments (see, for example, Figure 2). In addition to chem-
ical shifts, spin–spin coupling constants can also be calcu-
lated[25] based on optimized geometries. The data in
Tables 1 and 2 show that the trend and approximate magni-
Shifts δ11B and δ77Se, and Coupling constants
The optimized geometries calculated at the B3LYP/6-
311+G(d,p) level of theory[22] of 4 and 15b are in close
agreement with the experimental structural data (Table 3).
Table 3. Selected bond lengths [pm] and angles [°] of the of the
carborane derivatives 4, 4(calcd.), 15b, and 15b(calcd.).
1
tude of J(77Se,11B) and 1J(77Se,13C) coupling constants are
4
4 (calcd.) 15b
133 K
15b (calcd.)
predicted correctly. In the case of 9, the correct prediction
3
of J(77Se,13C) (see Figure 3) is noteworthy.
T [K]
133 K
C(1)–Se(1)
C(2)–Se(2)
C(1)–C(2)
Se(1)–B(13)
Se(2)–B(13)
B(13)–N
N–C(3)
N–C(6)
192.3(3)
193.2(4)
163.8(5)
197.5(4)
199.1(4)
138.0(5)
147.9(4)
148.4(4)
195.5
195.6
163.2
200.2
199.8
139.8
149.1
149.5
193.1(4)
193.2(5)
163.4(6)
205.9(5)
206.5(5)
160.5(7)
152.1(6)
151.2(6)
150.4(5)
185.0(5)
195.5
195.7
163.9
208.1
208.2
165.8
152.0
151.7
150.5
187.1
X-ray Structural Analyses of the ortho-Carborane
Derivatives 4 and 15b
The molecular structures of 4 and 15b are shown in the
Figures 5 and 6, respectively, and experimental structural
parameters together with calculated data are given in
Table 3. The diselenaborolane ring in 4 is almost planar,
whereas the analogous ring in 15b is slightly folded. Appar-
ently, the C(1)–C(2) and C–Se bond lengths in both 4 and
15b are not affected by the nature of the B(13) boron atom.
Expectedly,[26,27] the B(13)–Se bond lengths are shorter in 4
than in 15b. This effect is even more pronounced for the
B(13)–N bonds, which in the case of 4 is short [138.0(5)
pm], indicating considerable double-bond character.[28] The
conformation adopted by the N–iPr groups in 4 corre-
sponds closely to the results of NMR spectroscopic mea-
surements at low temperature (Figure 2), in agreement with
the calculated gas-phase structure of lowest energy. The B–
Se bond lengths in 15b are similar to those reported for the
dimethylsulfide adduct of the corresponding B–H deriva-
tive.[12]
N–C(7)
B(13)–Cl
B(13)–Se(1)–C(1)
B(13)–Se(2)–C(2)
Se(1)–C(1)–C(2)
Se(2)–C(2)–C(1)
Se(1)–B(13)–Se(2)
Se(1)–B(13)–N
Se(2)–B(13)–N
N–B(13)–Cl
Se(1)–B(13)–Cl
Se(2)–B(13)–Cl
B(13)–N–C(3)
B(13)–N–C(6)
B(13)–N–C(7)
C(3)–N–C(6)
96.31(15) 96.5
95.96(15) 96.4
98.25(19) 98.29
98.03(19) 98.26
116.5(2)
116.1(2)
116.2
116.4
116.7(3)
116.9(3)
109.8(2)
108.1(3)
110.4(3)
107.3(3)
111.9(3)
109.1(2)
111.7(3)
115.1(4)
110.0(4)
102.6(3)
3.0
116.87
116.80
109.74
109.7
111.1
105.6
111.10
109.68
112.3
114.0
110.5
102.0
115.07(19) 114.5
120.5(3)
124.5(3)
120.7
124.8
119.6(3)
125.4(3)
120.2
125.3
115.0(3)
114.5
0.0
Se(1)–C(1)–C(2)–Se(2)–B(13) 1.3
Se(1)–C(1)–C(2)–Se(2)
Distance of B(13) from the
plane: Se(1)–C(1)–C(2)–Se(2) 5.0
0.2
1.1
0.1
11.8
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B. Wrackmeyer, E. V. Klimkina, W. Milius
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coordinate boron atom. Considering the reactivity of B–Se
and B–X bonds (X = Cl, Br, I), the new boranes possess
synthetic potential for further useful transformations. Of
particular interest will be the reactivity towards alkynes
with respect to insertion (into B–Se or B–X bonds) or fur-
ther exchange reactions.
Experimental Section
General: All syntheses and the handling of the samples were carried
out observing necessary precautions to exclude traces of air and
moisture. Carefully dried solvents and oven-dried glassware were
used throughout. The CH2Cl2 and CD2Cl2 were distilled from
CaH2 under an atmosphere of argon. All other solvents were dis-
tilled from Na metal under an argon atmosphere. The starting ma-
terials were prepared as described in the literature; 1,[9] 2,[9]
MeOBCl2 from B(OMe)3 and BCl3 (molar ratio 1:2) in toluene,
PhOBBr2 from B(OPh)3 and BBr3 (molar ratio 1:2) in hexane.[29]
Other starting materials were purchased from Aldrich [BCl3 (1.0 m
in toluene), BBr3 (1.0 m in hexane), BI3 (Ն98%), BF3–OEt2 (puri-
fied by redistillation), PhBCl2 (97%), iPr2NBCl2, B(OMe)3
(99.999%), B(OPh)3, pyridine (anhydrous, 99.8%), N-methylpyr-
rolidine, SbF3 (98%)], from Messer Griesheim (BF3) and used as
received. 2,2Ј-Bipyridine (Aldrich, Ն 99%) was sublimed before use
(40–45 °C/2ϫ10–2 Torr). NMR spectroscopic measurements:
Bruker DRX 500 and Bruker ARX 250: 1H, 11B, 13C, 77Se, and
29Si NMR [refocused INEPT[30] based on 2J(29Si,1H) = 6–7 Hz];
Figure 5. Two views of the ORTEP plots (50% probabilities; hydro-
gen atoms have been omitted for clarity) of the molecular structure
of the 2-bis(isopropylamino)-4,5-[1,2-dicarba-closo-dodecabor-
ano(12)]-1,3-diselena-2-borolane
angles see Table 3).
4 (for selected distances and
1
Varian INOVA 400: H, 11B, 13C, 29Si, 77Se NMR; chemical shifts
are given relative to Me4Si [δ1H (CHDCl2) = 5.33, (C6D5CD2H) =
2.08 (Ϯ 0.01); δ13C (CD2Cl2) = 53.8, (C6D5CD3) = 20.4 (Ϯ 0.1);
δ29Si = 0 (Ϯ0.1) for Ξ(29Si) = 19.867184 MHz]; external BF3–OEt2
[δ11B = 0 (Ϯ0.3) for Ξ(11B) = 32.083971 MHz], neat Me2Se [δ77Se
1
= 0 (Ϯ 0.1) for Ξ(77Se) = 19.071523 MHz]. Assignments of H and
11B NMR spectroscopic signals are based on selective 1H{11B
selective} heteronuclear decoupling experiments. Mass spectra (EI,
70 eV): Finnigan MAT 8500 with direct inlet [data for (12C, 1H,
11B, 35Cl, 28Si, 80Se)]. Elemental analyses [C(H)] of the boranes 3–
8, and of the adduct 15b did not give satisfactory and reproducible
results, most likely on account of boron carbide formation. Melting
points (uncorrected) were determined using a Büchi 510 melting
point apparatus.
All quantum chemical calculations were carried out using the
Gaussian 03 program package (Revision-B.02).[31] Optimized geo-
metries at the RB3LYP/6-311+ g(d.p) level of theory were found
to be minima by the absence of imaginary frequencies. NMR pa-
rameters were calculated at the same level of theory. Calculated
chemical shifts δ11B and δ77Se were converted by δ11B (calcd) =
σ(11B) – σ(11B, B2H6), with σ(11B, B2H6) = +84.1 [δ11B (B2H6) =
18 and δ11B (BF3–OEt2) = 0] and δ77Se(calcd) = σ(77Se) – σ(77Se,
SeMe2) with σ(77Se, SeMe2) = +1621.7.
Figure 6. ORTEP plot (50% probabilities; hydrogen atoms have
been omitted for clarity) of the molecular structure of the 2-chloro-
2-(N-methylpyrrolidine)-4,5-[1,2-dicarba-closo-dodecaborano(12)]-
1,3-diselena-2-boracyclopentane 15b (for selected distances and
angles see Table 3).
Conclusion
2-Phenyl-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3-diselena-2-
borolane (3). Method A: A suspension of 1 (60 mg, 0.144 mmol) in
[D8]toluene (0.6 mL) was cooled to 0 °C and 1.5 equiv. of PhBCl2
(0.03 mL, 0.23 mmol) was added. The progress of the reaction was
monitored by 11B and 29Si NMR spectroscopy. After 24 h at r.t.,
the mixture contained 3 together with Me2Si(Cl)–SiMe2(Cl) and
PhBCl2 . Volatile materials were removed in vacuo (3 h,
8ϫ10–3 Torr) to give 3 as a white solid.
By contrast with previous attempts, a straightforward
route to 1,3,2-diselenaborolanes with an annelated dicarba-
closo-dodecaborane(12) unit by the exchange reactions of
boron halides with siladiselena heterocycles has been suc-
cessfully explored. The combination of multinuclear mag-
netic resonance spectroscopy in solution and DFT calcula-
tions of NMR parameters served well even in the charac-
terization of some side products. The X-ray structural
analysis of the B–NiPr2 derivative provided the first struc-
Method B: A solution of 2 (99 mg, 0.277 mmol) in [D8]toluene
(0.6 mL) was cooled to 0 °C and PhBCl2 (0.036 mL, 0.28 mmol)
tural data of a 1,3,2-diselenaborolane containing a three- was added. The progress of the reaction was monitored by 11B and
4488
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 4481–4492

1,3,2-Diselenaborolanes
29Si NMR spectroscopy. After 24 h at r.t., the mixture contained 3
together with Me2SiCl2. Volatile materials were removed in vacuo
(3 h, 8ϫ10–3 Torr) to give 3 as a white solid.
After 2 h at r.t., the mixture contained 5 together with Me2SiCl2
and BCl3. Volatile materials were removed in vacuo (1 h,
8ϫ10–3 Torr) to give 5 as a yellowish oil.
3: 1H{11B} NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 2.78 (br.
m, 10 H, HB), 6.80–7.10 (m, 5 H, Ph) ppm. 1H NMR (250.1 MHz;
[D8]toluene; –50 °C): δ = 2.93 (br. s, 10 H, HB), 6.80 (m, 3 H, Ph),
7.04 (m, 2 H, Ph) ppm. 11B{1H} NMR (80.3 MHz; [D8]toluene;
25 °C): δ = –9.2 (4 B), –7.1 (2 B), –5.9 (2 B), –4.7 (2 B), 76.0 (1 B,
SeB) ppm. 1H{11B} NMR (250.1 MHz, CD2Cl2; 25 °C): δ = 2.30
[br. s, 2 H, HB for δ(11B) = –6.1], 2.37 [br. s, 2 H, HB for δ(11B) =
–7.2], 2.64 [br. s, 4 H, HB for δ(11B) = –9.0], 2.78 [br. s, 2 H, HB
for δ(11B) = –4.4], 7.35–7.65 (m, 5 H, Ph) ppm. 11B{1H} NMR
(80.3 MHz, CD2Cl2; 25 °C): δ = –9.0 (4 B), –7.2 (2 B), –6.1 (2 B),
–4.4 (2 B), 76.4 (1 B, SeB) ppm. 11B NMR (80.3 MHz, CD2Cl2;
25 °C): δ = –8.9 (d, 4 B, 175 Hz), –7.1 (d, 2 B, 155 Hz), –6.1 (d, 2
B, 160 Hz), –4.3 (d, 2 B), 76.4 (s,1 B, SeB) ppm. EI-MS (70 eV) for
1
5: H{11B} NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 2.60 [br. s,
6 H, HB for δ(11B) = –9.0, –4.9], 2.69 [br. s, 4 H, HB for δ(11B) =
–7.2, –4.9] ppm. 11B{1H} NMR (80.3 MHz; [D8]toluene; 25 °C): δ
= –9.0 (4 B), –7.2 (2 B), –4.9 (4 B), 68.6 (1 B, SeB) ppm. 11B NMR
(80.3 MHz; [D8]toluene; 25 °C): δ = –9.0 (d, J = 180 Hz, 4 B), –7.2
(d, J = 158 Hz, 2 B), –4.9 (d, J = 150 Hz, 4 B), 68.6 (s, 1 B, SeB)
ppm. EI-MS (70 eV) for C2H10B11Se2Cl (346.40): m/z (%) = 346
(100) [M+], 301 (20) [M+ – BCl], 253 (5), 218 (8), 207 (7), 161 (6),
124 (22), 112 (18).
2-Bromo-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3-diselena-2-
borolane (6). Method A: A suspension of 1 (70 mg, 0.166 mmol) in
[D8]toluene (0.6 mL) was cooled to 0 °C and BBr3 (0.25 mL of a
1.0 m solution in hexane, 0.25 mmol) was added. The progress of
the reaction was monitored by 11B and 29Si NMR spectroscopy.
After 2 h at r.t., the mixture contained 6 together with Me2Si(Br)–
SiMe2(Br) and BBr3. Volatile materials were removed in vacuo (3 h,
8ϫ10–3 Torr) to give 6 as a yellowish solid.
C8H15B11Se2 (388.05): m/z (%) = 388 (5) [M+], 301 (100) [M+
–
BC6H5], 221 (15), 209 (35), 124 (22), 114 (32).
2-Diisopropylamino-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3-
diselena-2-borolane (4). Method A: A suspension of 1 (60 mg,
0.144 mmol) in [D8]toluene (0.6 mL) was cooled to 0 °C and
1.5 equiv. of iPr2NBCl2 (39 mL, 0.22 mmol) was added. The pro-
gress of the reaction was monitored by 11B and 29Si NMR spec-
troscopy. After 1 h at r.t., the mixture contained 4 together with
Me2Si(Cl)–SiMe2(Cl) and iPr2NBCl2. Volatile materials were re-
moved in vacuo (3 h, 8ϫ10–3 Torr) to give 4 as a white oil. Single
transparent crystals of 4 for X-ray analysis were grown from
[D8]toluene/hexane (1:2) solution after 2 months at –30 °C; m.p.
128–130 °C.
Method B: A solution of 2 (85 mg, 0.238 mmol) in [D8]toluene
(0.6 mL) was cooled to 0 °C and BBr3 (0.4 mL of a 1.0 m solution
in hexane, 0.4 mmol) was added. The progress of the reaction was
monitored by 11B and 29Si NMR spectroscopy. After 1 h at r.t.,
the mixture contained 6 together with Me2SiBr2 and BBr3. Volatile
materials were removed in vacuo (3 h, 8ϫ10–3 Torr) to give 6 as a
yellowish solid.
1
6: H{11B} NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 2.60 [br. s,
6 H, HB for δ(11B) = –9.1, –5.0], 2.69 [br. s, 4 H, HB for δ(11B) =
–7.0, –5.0] ppm. 11B{1H} NMR (80.3 MHz; [D8]toluene; 25 °C): δ
= –9.1 (4 B), –7.0 (2 B), –5.0 (4 B), 64.7 (1 B, SeB) ppm. 11B NMR
(80.3 MHz; [D8]toluene; 25 °C): δ = –9.1 (d, J = 165 Hz, 4 B), –7.0
(d, J = 160 Hz, 2 B), –5.0 (d, J = 162 Hz, 2 B), 64.7 (s, 1 B, SeB)
ppm. 11B NMR (80.3 MHz; hexane; 25 °C): δ = –8.4 (d, J =
167 Hz, 4 B), –6.4 (d, J = 160 Hz, 2 B), –4.3 (d, J = 169 Hz, 2 B),
Method B: A solution of 2 (93 mg, 0.258 mmol) in [D8]toluene
(0.6 mL) was cooled to 0 °C and iPr2NBCl2 (0.05 mL, 0.28 mmol)
was added. The progress of the reaction was monitored by 11B and
29Si NMR spectroscopy. After 30 min at r.t., the mixture contained
4 together with Me2SiCl2 and iPr2NBCl2. Volatile materials were
removed in vacuo (3 h, 8ϫ10–3 Torr) to give 4 as a white solid.
4: 1H{11B} NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 0.71 [d,
1
65.5 [s, J(77Se) = 81.1 Hz, 1 B, SeB] ppm.
3
3J(H,H) = 6.75 Hz, 12 H, NCMe2], 2.64 [sep, J(H,H) = 6.75 Hz,
2 H, NCH], 2.78 [br. s, 4 H, HB for δ(11B) = –6.8, –5.4], 2.88 [br.
s, 4 H, HB for δ(11B) = –8.8], 2.94 [br. s, 2 H, HB for δ(11B) = –3.1]
ppm. 1H NMR (250.1 MHz; [D8]toluene; –50 °C): δ = 0.48, 0.73
(br. s, br. s, 6 H, 6 H, NCMe2), 2.30, 2.38 (br. m, br. m, 1 H, 1 H,
NCH), 3.11 (br. s, 10 H, HB) ppm. 11B{1H} NMR (80.3 MHz;
[D8]toluene; 25 °C): δ = –8.8 (4 B), –6.8 (2 B), –5.4 (2 B), –3.1 (2
B), 45.7 (1 B, SeB) ppm. 11B NMR (80.3 MHz; [D8]toluene; 25 °C):
δ = –8.8 (d, J = 160 Hz, 4 B), –6.8 (d, J = 160 Hz, 2 B), –5.4 (d, J
= 160 Hz, 2 B), –3.1 (d, J = 175 Hz, 2 B), 45.7 (s, 1 B, SeB) ppm.
EI-MS (70 eV) for C8H24B11Se2N (411.12): m/z (%) = 411 (15)
[M+], 396 (100) [M+ – CH3], 353 (45) [M+ – C4H10], 310 (5), 221
(12), 143 (13).
2-Iodo-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3-diselena-2-
borolane (7): A solution of 2 (85 mg, 0.238 mmol) in [D8]toluene
(0.6 mL) was cooled to 0 °C and ca. 1.5 equiv. BI3 (157 mg,
0.4 mmol) was added. The formation of a red solution was ob-
served. The progress of the reaction was monitored by 11B and 29Si
NMR spectroscopy. After 10 min at r.t., the mixture contained 7
together with Me2SiI2 and BI3. Volatile materials were removed in
vacuo (5 h, 40 °C at 8ϫ10–3 Torr) to give 7 as a rosè-colored solid.
1
7: H{11B} NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 2.57 [br. s,
2 H, HB for δ(11B) = –5.2], 2.61 [br. s, 4 H, HB for δ(11B) = –9.2],
2.64 [br. s, 2 H, HB for δ(11B) = –5.2], 2.71 [br. s, 2 H, HB for
δ(11B) = –6.8] ppm. 11B{1H} NMR (80.3 MHz; [D8]toluene; 25 °C):
δ = –9.2 (4 B), –6.8 (2 B), –5.3 (4 B), 52.2 (1 B, SeB) ppm. 11B
NMR (80.3 MHz; [D8]toluene; 25 °C): δ = –9.2 (d, J = 165 Hz, 4
B), –6.8 (d, J = 170 Hz, 2 B), –5.3 (d, J = 170 Hz, 4 B), 52.2
[1J(77Se,11B) = 93.0 Hz, 1 B, SeB] ppm.
2-Chloro-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3-diselena-2-
borolane (5). Method A: A suspension of 1 (70 mg, 0.166 mmol)
in [D8]toluene (0.6 mL) was cooled to 0 °C and 1.5 equiv. of BCl3
(0.25 mL of a 1.0 m solution in toluene, 0.25 mmol) was added.
The progress of the reaction was monitored by 11B and 29Si NMR
spectroscopy. After 2 d at r.t., the mixture contained 5 together
with Me2Si(Cl)–SiMe2(Cl) and BCl3. Volatile materials were re-
moved in vacuo (1 h, 8ϫ10–3 Torr) to give 5 as a yellowish oil.
Reaction of 1 with MeOBCl2: A suspension of 1 (70 mg,
0.166 mmol) in [D8]toluene (0.6 mL) was cooled to 0 °C and a solu-
tion of freshly prepared MeOBCl2 in toluene (0.35 mmol) was
added. The progress of the reaction was monitored by 11B and 29Si
NMR spectroscopy. After 1 h at r.t., the mixture contained 5 to-
gether with Me2Si(Cl)–SiMe2(Cl), (MeO)2BCl, and MeOBCl2. Vol-
atile materials were removed in vacuo (2 h, 8ϫ10–3 Torr) to give 5
as a yellowish oil.
Method B: A solution of 2 (78 mg, 0.219 mmol) in [D8]toluene
(0.6 mL) was cooled to 0 °C and ca. 2 equiv. BCl3 (0.4 mL of a
1.0 m solution in toluene, 0.4 mmol) was added. The progress of
the reaction was monitored by 11B and 29Si NMR spectroscopy.
Eur. J. Inorg. Chem. 2011, 4481–4492
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4489

B. Wrackmeyer, E. V. Klimkina, W. Milius
FULL PAPER
Synthesis of PhOBBr2: A solution of (PhO)3B (154 mg, 0.53 mmol)
in hexane (1 mL) was cooled to 0 °C and BBr3 (1.06 mL of a 1.0 m
solution in hexane, 1.06 mmol) was added. After 30 min at 0 °C,
2.68 [s, 1J(77Se,1H) = 52.3 Hz, SeH from 12], 2.95–3.05 (m, CH2
from Et) ppm. 77Se NMR (47.7 MHz, CD2Cl2; 25 °C): δ = 355.1
[d, 1J(77Se,1H) = 52.3 Hz, SeH from 12], 370.4 [d, 1J(77Se,1H) =
the mixture contained PhOBBr2 (90%), (PhO)2BBr (5%), and BBr3 53.0 Hz, SeH from 11], 489.1 (13), 501.7 (12) ppm.
(5%). 11B NMR (80.3 MHz; hexane; 25 °C): δ = 22.5 [(PhO)2BBr],
Me2Si(F)–SiF(Me2): 29Si NMR (49.7 MHz; [D8]toluene; 25 °C): δ
28.1 (PhOBBr2), 39.4 (BBr3) ppm.
= 28.5 [dd, 1J(29Si,19F) = 303.6, 2J(29Si,19F) = 33.8 Hz, SiMe] ppm.
1H NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 0.22 [dm, SiMe,
Reaction of 2 with PhOBBr2: A solution of 2 (85 mg, 0.238 mmol)
in [D8]toluene (0.6 mL) was cooled to 0 °C and a solution of freshly
3J(19F,1H) = 9.0 Hz] ppm.
prepared PhOBBr2 in hexane (0.45 mmol) was added. The progress
Reaction of 2 with BF3–OEt2: A solution of 2 (67 mg, 0.187 mmol)
in [D8]toluene (0.6 mL) was cooled to 0 °C and BF3–OEt2
of the reaction was monitored by 11B and 29Si NMR spectroscopy.
After 1 h at r.t., the mixture contained 6 together with Me2SiBr2,
(PhO)2BBr, and PhOBBr2.
(0.05 mL, 0.41 mmol) was added. The progress of the reaction was
monitored by 11B and 29Si NMR spectroscopy. After 60 h at 70 °C,
the mixture contained 12, 13, and 14 together with Me2SiF2 and
BF3–OEt2. Volatile materials were removed in vacuo. The solution
thus obtained contained 12 (25%), 13 (30%), and 14 (45%) (77Se
NMR).
Reaction of 1 with PhOBBr2 and B(OPh)3. 2-Phenoxy-4,5-[1,2-di-
carba-closo-dodecaborano(12)]-1,3-diselena-2-borolane (8): A sus-
pension of 1 (70 mg, 0.166 mmol) in [D8]toluene (0.6 mL) was co-
oled to 0 °C and a solution of freshly prepared PhOBBr2 in hexane
(0.30 mmol) was added. The progress of the reaction was moni-
tored by 11B and 29Si NMR spectroscopy. After 1 h at r.t., the mix-
ture contained 6 together with Me2Si(Br)–SiMe2(Br), (PhO)2BBr,
and PhOBBr2. B(OPh)3 (87 mg, 0.30 mmol) was added to this mix-
ture at 0 °C. The progress of the reaction was monitored by 11B
and 29Si NMR spectroscopy. Volatile materials were removed in
vacuo (3 h, 8ϫ10–3 Torr). The resulting mixture thus obtained con-
tained 8 (50%), 11 (25%), 6 (25%), BrB(OPh)2, and B(OPh)3 (77Se,
13C, 11B NMR).
1
12 + 13 + 14: H NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 0.85
(m, Me from Et), 1.76 [s, 1J(77Se,1H) = 55.7 Hz, SeH from 12],
2.40–2.55 (m, CH2 from Et) ppm. 77Se NMR (95.4 MHz, CD2Cl2;
25 °C): δ = 351.7 [d, 1J(77Se,1H) = 55.7 Hz, SeH from 12], 489.3
(SeEt from 14), 491.9 (13), 502.2 (SeEt from 12), 715.1 (Se-Se from
14) ppm.
Me2SiF2: 29Si NMR (49.7 MHz; [D8]toluene; 25 °C): δ = 5.7 [t,
1J(29Si,19F) = 289.8 Hz, SiMe] ppm. 1H NMR (250.1 MHz; [D8]-
3
toluene; 25 °C): δ = 0.03 [t, J(19F,1H) = 6.2 Hz, SiMe] ppm.
Reaction of 5 with B(OMe)3. 2-Methoxy-4,5-[1,2-dicarba-closo-do-
decaborano(12)]-1,3-diselena-2-borolane (9) and 1-Hydroseleno-2-
methylseleno-1,2-dicarba-closo-dodecaborane(12) (10): A solution of
5 (68 mg, 0.20 mmol) in [D8]toluene (0.6 mL) was cooled to 0 °C
and B(OMe)3 (0.03 mL, 0.27 mmol) was added. The progress of
the reaction was monitored by 11B NMR spectroscopy. Volatile ma-
terials were removed in vacuo (1 h, 8ϫ10–3 Torr). The mixture thus
obtained contained 9 (80%) and 10 (20%) (77Se, 13C, 11B NMR;
see also Figure 3).
Reaction of 5 with Pyridine. 2-Chloro-2-pyridine-4,5-[1,2-dicarba-
closo-dodecaborano(12)]-1,3-diselena-2-boracyclopentane (15a) and
Pyridinium Bis(1,2-dicarba-closo-dodecaborane-1,2-diselena)borate
(16a): A solution of 5 (70 mg, 0.196 mmol) in [D8]toluene (0.6 mL)
was cooled to –50 °C and pyridine (0.1 mL, 1.2 mmol) was added.
The formation of a yellow solution was observed. The progress
of the reaction was monitored by 11B NMR spectroscopy. Volatile
materials were removed in vacuo (1 h, 8ϫ10–3 Torr). The mixture
thus obtained contained 15a (90%) and 16a (10%) (77Se, 13C, 11B
NMR). The same reaction at room temperature resulted in a mix-
ture, containing 15a (70%) and 16a (30%) (77Se, 13C, 11B NMR).
9: 1H{11B} NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 2.75 (m, 10
H, HB), 2.84 (s, 3 H, OMe) ppm. 11B{1H} NMR (80.3 MHz;
[D8]toluene; 25 °C): δ = –8.7 (4 B), –7.1 (2 B), –4.8 (2 B), –3.6 (2
B), 53.9 (1 B, SeB) ppm.
1
15a: H{11B} NMR (250.1 MHz, CD2Cl2; 25 °C): δ = 2.1–3.2 (m,
10 H, HB), 7.85 (m, Hβ-py), 8.17 (m, Hγ-py), 9.42 (m, Hα-py) ppm.
11B{1H} NMR (80.3 MHz, CD2Cl2; 25 °C): δ = –11.8, –9.5, –8.5,
–6.1, –1.3 (10 BH), 13.9 [1J(77Se,11B) = 45.0 Hz, 1 B, BSe2] ppm.
10: 1H{11B} NMR (250.1 MHz; [D8]toluene; 25 °C): δ = 1.64 [s,
1
2J(77Si,1H) = 13.4 Hz, 3 H, SeMe], 1.71 [s, J(77Si,1H) = 54.9 Hz,
1 H, SeH], 2.15 [br. s, 2 H, HB for δ(11B) = –8.8], 2.54 [br. s, 2 H,
HB for δ(11B) = –8.1], 2.66 [br. s, 2 H, HB for δ(11B) = –8.1], 2.75
[br. s, 2 H, HB for δ(11B) = –7.5], 2.87 [br. s, 2 H, HB for δ(11B) =
–2.1, –2.8] ppm. 11B{1H} NMR (80.3 MHz; [D8]toluene; 25 °C): δ
= –8.8 (2 B), –8.1 (4 B), –7.5 (2 B), –2.8 (1 B), –2.1 (1 B) ppm.
1
16a: H{11B} NMR (250.1 MHz, CD2Cl2; 25 °C): δ = 2.07 (br. s,
4 H, HB), 2.20 (br. s, 4 H, HB), 2.45 (br. s, 8 H, HB), 2.76 (br. s,
4 H, HB), 8.05 (m, Hβ-py), 8.51 (m, Hγ-py), 8.77 (m, Hα-py), 16.5
(br. s, pyH+) ppm. 11B{1H} NMR (80.3 MHz, CD2Cl2, 25 °C): δ =
–9.2 (8 B), –7.2 (8 B), –3.0 (4 B), 6.0 [1J(77Se,11B) = 59.0 Hz, 1 B,
BSe2] ppm.
Reaction of 1 (or 2) with BF3: A saturated solution of BF3 in tolu-
ene (5 mL) was added to 1 (or 2) (0.5 mmol) in [D8]toluene (1 mL)
at 0 °C. The mixture was stirred for 2 d at room temperature. Vola-
tile materials were removed in vacuo to give 11 along with other
decomposition products.
Reaction of 5 with N-Methylpyrrolidine. 2-Chloro-2-(N-methylpyr-
rolidine)-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3-diselena-2-
boracyclopentane (15b) and N-Methylpyrrolidinium Bis(1,2-dicarba-
closo-dodecaborane-1,2-diselena)borate (16b): The synthesis was
carried out as described for 15a, starting from 5 (35 mg, 0.10 mmol)
in [D8]toluene (0.6 mL) and N-methylpyrrolidine (25 mg,
0.29 mmol) at –40 °C. The formation of a yellow solution was ob-
served. Volatile materials were removed in vacuo (1 h,
8ϫ10–3 Torr). The mixture thus obtained contained 15b (70%) and
16b (30%) (77Se, 13C, 11B NMR). Single transparent crystals of 15b
were grown from [D8]toluene solution after 1 d at r.t.; m.p. 160–
165 °C (dec.).
Reaction of 1 with BF3–OEt2: A suspension of 1 (70 mg,
0.168 mmol) in [D8]toluene (0.6 mL) was cooled to 0 °C and BF3–
OEt2 (0.05 mL, 0.41 mmol) was added. The progress of the reaction
was monitored by 11B and 29Si NMR spectroscopy. After 60 h at
70 °C, the mixture contained 11, 12, and 13 together with
Me2Si(F)–SiMe2(F) and BF3–OEt2. Volatile materials were re-
moved in vacuo. The solution thus obtained contained 11 (30%),
12 (60%), and 13 (10%) (77Se NMR).
11 + 12 + 13: 1H NMR (250.1 MHz, CD2Cl2; 25 °C): δ = 1.35– 15b: H NMR (500.1 MHz; [D8]toluene; 25 °C): δ = 0.90, 1.00 (m,
1
1.45 (m, Me from Et), 2.61 [s, 1J(77Se,1H) = 53.0 Hz, SeH from 11],
m, 2 H, 2 H, Hβ-pyrrolidine), 1.82 (m, 3 H, CH3), 2.83 (m, 4 H,
4490
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 4481–4492

1,3,2-Diselenaborolanes
Hα-pyrrolidine) ppm. 11B{1H} NMR (160.5 MHz; [D8]toluene;
25 °C): δ = –15–0 (overlapping signals for 16b), 16.9 [1J(77Se,11B)
= 46.6 Hz, 1 B, BSe2] ppm.
[1]
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1
16b: H NMR (500.1 MHz; [D8]toluene; 25 °C): δ = 1.42 (m, Hβ-
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pyrrolidine), 2.03 (m, NCH3-pyrrolidine), 2.41 (m, Hα-pyrrolidine),
11.6 (br. s, NH+-pyrrolidine) ppm. 11B{1H} NMR (160.5 MHz;
[D8]toluene; 25 °C): δ = –15–0 (overlapping signals for 15b), 6.7
[1J(77Se,11B) = 55.5 Hz, 1 B, BSe2] ppm.
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Reaction of 5 with 2,2Ј-Bipyridine. 2,2Ј-Bipyridinium Bis(1,2-di-
carba-closo-dodecaborane-1,2-diselena)borate (16c): When the syn-
thesis was carried out as described for 15a, starting from 5 (79 mg,
0.228 mmol) in [D8]toluene (0.6 mL) and 2,2Ј-bipyridine (36 mg,
0.23 mmol) at –40 °C, the formation of a layer of red oil formed
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1
16c: H{11B} NMR (250.1 MHz; CD2Cl2; 25 °C): δ = 2.0–3.0 (m,
20H, HB), 7.73 (m, 2,2Ј-bipy), 8.27 (m, 2,2Ј-bipy), 8.72 (m, 2,2Ј-
bipy), 8.89 (m, 2,2Ј-bipy), 16.9 (br. s, 2,2Ј-bipyH+). 11B{1H} NMR
(80.3 MHz; CD2Cl2; 25 °C): δ = –13 to 0 (overlapping signals for [6] a) W.-G. Jia, Y.-F. Han, G.-X. Jin, Organometallics 2008, 27,
11 and ortho-carborane), 6.0 [1J(77Se,11B) = 56.5 Hz, 1 B, BSe4].
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Crystal Structure Determination of 4 and 15b: Details pertinent to
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the crystal structure determinations[32] are listed in Table 4.[33]
Zhang, Y.-J. Lin, J. Dai, G.-X. Jin, J. Organomet. Chem. 2007,
Crystals of appropriate size were sealed under argon in Lindemann
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and 15b by using a STOE IPDS II diffractometer with graphite-
monochromated Mo-Kα (λ = 71.073 pm) radiation.
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Table 4. Crystallographic data of the carborane derivatives 4 and
15b.
4
15b
Formula
Crystal
C8H24B11NSe2
colorless prism
0.42ϫ0.22ϫ0.18
133(2)
monoclinic
P21/c
700.29(14)
1740.3(4)
1529.0(3)
96.65(3)
C7H21B11ClNSe2
colorless prism
0.25ϫ0.19ϫ0.18
133(2)
monoclinic
P2(1)
705.02(14)
1134.6(2)
1073.2(2)
93.08(3)
Dimensions [mm3]
Temperature [K]
Crystal system
Space group
a [pm]
b [pm]
c [pm]
β [°]
[9]
B. Wrackmeyer, E. V. Klimkina, W. Milius, Appl. Organomet.
Chem. 2010, 25, 25–32.
Z
4
2
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Absorption coefficient, 3.981
4.452
μ [mm–1]
Measuring range (ϑ) [°] 1.78–25.68
Reflections collected
1.90–25.61
27891
1613
17976
[11]
Independent reflections 3072
[IՆ2σ(I)]
Absorption correction none[a]
numerical
200
0.52(3)
Refined parameters
Absolute structure pa-
rameter
199
–
[12]
[13]
[14]
[15]
[16]
wR2 / R1 [IՆ2σ(I)]
0.095 / 0.039
0.060 / 0.023[b]
0.797 / –0.388
Max. / min. residual e– 1.010 / –0.397
density [epm–3 10–6]
B. Wrackmeyer, E. V. Klimkina, W. Milius, Z. Anorg. Allg.
Chem. 2011, in press.
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[b] The crystal structure was solved and refined taking into account
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[18]
Acknowledgments
Support of this work by the Deutsche Forschungsgemeinschaft
(DFG) is gratefully acknowledged.
Eur. J. Inorg. Chem. 2011, 4481–4492
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4491

B. Wrackmeyer, E. V. Klimkina, W. Milius
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Received: June 3, 2011
Published Online: August 19, 2011
4492
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 4481–4492