1,3,2-diselena- and 1,3,2-ditelluraphospholanes with an annelated 1,2-dicarba-closo-dodecaborane(12) unit

FULL PAPER

DOI:10.1002/ejic.201301600

1,3,2-Diselena- and 1,3,2-Ditelluraphospholanes with an

Annelated 1,2-Dicarba-closo-dodecaborane(12) Unit

Bernd Wrackmeyer,*^[a]Elena V. Klimkina,^[a]and Wolfgang Milius^[b]

Keywords: Carboranes / Chalcogens / Heterocycles / NMR spectroscopy / Density functional calculations / Structure

elucidation

The exchange reactions of phosphorus dihalides RPX₂[R =

iPr, cyclohexyl (Cy), tBu, (3,5-Me₂-C₆H₃)CH₂, Ph; X = Cl, Br],

EtOPCl₂, Et₂NPCl₂, Cl₂PCH₂PCl₂, and Cl₂PCH₂CH₂PCl₂

with 2,2-dimethyl-4,5-[1,2-dicarba-closo-dodecaborano(12)]-

ences were clear for the 2-phenyl-1,3,2-diselenaphospholane

derivative in solution and in the solid state. All reactions

were monitored by multinuclear magnetic resonance spec-

troscopy (¹H, ¹¹B, ¹³C, ³¹P, ⁷⁷Se, and ¹²⁵Te NMR), and solu-

tion-state structures could be proposed. Remarkably large

secondary isotope effects as isotope-induced chemical shifts

²Δ^12/13C(³¹P) exerted by the carborane carbon atoms were

observed; this is apparently a special property of the five-

membered ring. The gas-phase structures were optimized by

DFT methods [B3LYP/6-311+G(d,p) level of theory], and the

NMR parameters were calculated. Two 1,3,2-diselenaphos-

1,3-diselena-2-silacyclopentane provide

a straightforward

route to 1,3,2-diselenaphospholanes. Some tellurium ana-

logues were prepared from the dilithium salt [1,2-(LiTe)₂-1,2-

C₂B₁₀H₁₀] and were more difficult to characterize. For the

selenium compounds, some of the P-organosubstituted five-

membered rings dimerize to give ten-membered rings, most

readily with the more bulky alkyl groups such as tBu. This

was not observed for the tellurium compounds. The confor- pholanes and one dimer were characterized by X-ray analy-

mations of the five-membered rings were studied by NMR

spectroscopy and DFT methods. Striking structural differ-

sis.

unit and both of the lone pairs of electrons and the respec-

tive substituent at the phosphorus atom. This repulsion has

been shown to cause facile dimerization for E = O,^[4]which

is known for many 1,3,2-dioxaphospholanes in general,^[1,5]

as well as for E = S;^[6]dimerization is unusual for 1,3,2-

dithiaphospholanes.^[1,7]Although the synthesis, structures,

and first aspects of the reactivity of some derivatives A or

AЈ with E = Se have been reported,^[8–11]the nature of their

solution-state structures in comparison to their solid-state

structures has not been addressed in detail, and potential

dimerization has not been studied. In this work, we report

mainly our results for the derivatives of A or AЈ with E = Se

and our first attempts to prepare 1,3,2-ditelluraphosphol-

anes. Solution-state multinuclear magnetic resonance spec-

troscopic methods (¹H, ¹¹B, ¹³C, ³¹P, ⁷⁷Se, and ¹²⁵Te NMR)

were used as the major analytical tool. In particular, the

³¹P,^{[12] 77}Se,^[13]and ¹²⁵Te NMR parameters^[14]accompanied

by DFT calculations should be helpful. Example solid-state

structures were studied by X-ray structural analysis (for E

= Se).

Introduction

1,3,2-Dichalcogenophospholanes are well known for

oxygen and sulfur,^[1,2]less well studied for selenium,^[3]and

virtually unknown for tellurium. We are interested in the

annelation of these five-membered rings with the 1,2-di-

carba-closo-dodecaborane(12) unit (see A and AЈ) to study

the kinetic and steric or electronic effects.

The kinetic stabilization provided by the bulky carborane

unit may be potentially useful for E = Se and Te. By con-

trast, destabilization may be expected for E = O in particu-

lar because of repulsive interactions (short C–O and P–O

distances) between the rigid three-dimensional carborane

The synthetic approach is outlined in Scheme 1 and

starts from the parent carborane 1 and involves dilithiation

to form 2 and insertion of Se or Te into the C–Li bonds.

Although this protocol is fairly straightforward in the case

of 3 (E = Se)^[15]and for E = S,^[16]problems are encountered

for 4 (E = Te).^[17]Reactions with phosphorus halides afford

more pure products in better yield when the silane 5 is used

[a] Anorganische Chemie II, Universität Bayreuth,

95440 Bayreuth, Germany

E-mail: b.wrack@uni-bayreuth.de

[b] Anorganische Chemie I, Universität Bayreuth,

95440 Bayreuth, Germany

Supporting information for this article is available on the

WWW under http://dx.doi.org/10.1002/ejic.201301600.

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Scheme 1. Synthesis of starting materials 4 and 5, mainly used in this work for reactions with organophosphorus dihalides and diethyl-

amino- and ethoxyphosphorus dichloride.

instead of 3, as has been shown for phosphorus trihalides

A representative example of the NMR spectroscopic

to give 7.^[10]The analogous route for E = Te is not feasible, characterization is shown for 11 in Figure 1. The spectra

as all attempts so far to obtain the tellurium analogue of demonstrate the purity of the compound, its stability in

5 gave mainly the ditellane 6.^[17a]Thus, the major starting solution, and the complementary nature of the NMR pa-

materials in this study are the carborane derivatives 4 and rameters measured. Moreover, some of the spectra reveal

5, together with various phosphorus dihalides.

rather new aspects, for example, in Figure 1 (C) the isotope-

n

induced chemical shifts Δ^12/13C(³¹P) (n = 1, 2). These ef-

fects are readily measured in favorable cases. We were not

surprised to find that the effect for n = 1 covers a substan-

tial range.^[18]More exciting was the observation of the effect

for n = 2, exerted by the carborane ^12/13C nuclei across the

Results and Discussion

1,3,2-Diselenaphospholanes

In principle, all reactions of the silane 5 with phosphorus selenium atoms, as it had the same negative sign and often

dihalides in toluene (Scheme 2) proceed smoothly and even exceeded the effect for n = 1 (Supporting Information,

quantitatively to afford the desired 1,3,2-diselenaphos- Table S1]. The assignment of the ¹³C satellites in Figure 1

pholanes 8–18. However, for 8–10, the formation of other (C) is unambiguous because their relative intensities were

products can be observed, depending on the reaction time confirmed by the ¹³C NMR spectroscopic data. Usually

and the solvent. The air- and moisture-sensitive products such effects for n = 2 are much smaller than for n = 1 and

8–18 were readily identified by their diagnostic NMR spec- are often negligible and difficult to detect. We assume that

troscopic data (Table 1), which were confirmed by DFT cal- this effect for n = 2, as observed here, is related to properties

culations (see below). For 11 and 15, suitable crystalline mate- of the five-membered ring, as it was not observed for ten-

rial could be isolated for X-ray structural analysis (see below). membered rings (see below).

Scheme 2. Reactions of the silane 5 in [D₈]toluene or CD₂Cl₂with various phosphorus dihalides to form 1,3,2-diselenaphospholanes.

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Table 1. ¹³C, ³¹P, and ⁷⁷Se NMR spectroscopic data^[a]of the ortho-carborane derivatives (Se₂PR monomer).

³¹P,¹³C_carb

⁷⁷Se,³¹

P

Type

R

Solvent

δ¹³C(C_carb

)

²J

Other δ¹³C

δ³¹P

δ⁷⁷Se

¹J

[ppm]

[Hz]

[ppm]

[Hz]

iPr (8)

[D₈]toluene

80.5 [171.2]

{–7.3}

13.7

18.3 (27.6),

30.2 (47.9)

110.4 ͗240.9͘

47.6 (¹J), 27.6 (²J),

13.7 (²J)

629.6 ͗241.5͘ 241

A

CD₂Cl₂

80.6

12.6

18.8 (27.3),

30.4 (47.5)

110.8 ͗242.9͘

628.6 ͗242.7͘ 243

A

[D₈]THF

[D₈]toluene

–

13.7

–

116.9 ͗248.2͘

105.1 ͗237.2͘

632.6 ͗247.8͘ 248

613.1 ͗236.4͘ 237

A

Cy (9)

80.5 [171.6]

{–7.6}

25.6 (2.0), 26.2 (13.4),

29.1 (22.4),

39.9 (49.9) [31.8]

26.6 (2.0), 27.2 (13.2),

30.0 (22.5), 41.1 (50.7)

28.4 (18.5),

35.0 (48.3)

28.8 (18.4),

36.0 (49.8)

21.4 (0.4),

41.0 (53.8),

[D₈]THF

[D₈]toluene

[D₈]THF

CD₂Cl₂

81.5

12.9

2.6

110.9 ͗244.4͘

161.3 ͗152.6͘

161.8 ͗158.2͘

617.6 ͗244.2͘ 244

531.1 ͗153.0͘ 153

542.2 ͗158.9͘ 158

639.4 ͗232.5͘ 232

A

tBu (10)

75.0 [157.7]

{–7.6}

74.7

AЈ

A

5.7

(3,5-Me₂-C₆H₃)CH₂

(11)

80.8 [170.8]

{–8.4}

13.3

98.8 ͗232.0͘

53.8 (¹J)

127.7 (6.8) C_o,

129.7 (4.4) C_p,

134.5 (9.9) [1.2] C_i,

139.2 (3.4) C_m

[D₈]THF

80.8

11.5

20.8, 40.8 (55.6), 127.7 107.4 ͗233.1͘

(6.7) C_o, 129.3 (4.3) C_p,

135.1 (10.5)C_i, 138.7

642.5 ͗233.5͘ 233

A

(3.2) C_m

Ph (12)^[8]

[D₈]toluene

CD₂Cl₂

80.6 [169.0]

{–8.0}

15.4

14.9

128.9 (3.5) C_m, 130.1

(1.7) C_p, 130.2 (19.8)

C_o, 134.7 (60.0)C_i

129.4 (3.7) C_m, 130.5

(1.8) C_p, 130.6 (19.7)

[2.2] C_o, 134.7 (59.3)C_i

–

96.5 ͗268.5͘

96.2 ͗269.1͘

644.5 ͗268.2͘ 268

643.2 ͗269.0͘

A

80.5 [169.1]

{–7.7}

[D₈]THF

–

99.5 ͗270.6͘

209.8 ͗279.2͘

–

A

OEt (13)

[D₈]toluene

82.8 [172.8]

{–8.0}

77.1 [171.3]

{–9.5}

80.5

15.2

15.8 (6.0),

67.2 (7.7)

13.8 (4.4),

45.4 (18.4)

777.3 ͗278.6͘ 279

NEt₂(14)

[D₈]toluene

4.9

168.0 ͗208.9͘

631.7 ͗209.9͘ 209

AЈ

A

(C₂B₁₀Se₂P)₂CH₂(15) [D₈]toluene

13.0

12.8

9.6

31.3 (71.6)

95.3 ͗–227.0͘

“90.0” ͗+20.0͘

92.3 ͗–235.0͘

“121.0” ͗+17.0͘

107.4 ͗–235.0͘

“119.0” ͗+14.0͘

101.1 ͗–240.0͘

“16.5” ͗+4.0͘

100.3 ͗–242.5͘

“20.5” ͗+3.0͘

112.5 ͗–244.0͘

“10.0”

623.2 ^[b]

629.2 ^[b]

633.1 ^[b]

227.0

CD₂Cl₂

80.9

81.2

33.8 (70.6)

36.2 (74.7)

235.0

[D₈]THF

(C₂B₁₀Se₂PCH₂)₂(16) [D₈]toluene

CD₂Cl₂

80.7 [170.0]

{–7.6}

80.8

13.5

13.0

10.9

15.0

–

29.5

(–58.0, +15.5)

30.2

(–58.0, +15.0)

31.3

(–59.0, +16.5)

44.8 (79.5, 60.7)

632.8 ͗240.0͘ 240

634.0 ͗242.5͘ 242.5

638.2 ͗244.0͘ 244

[D₈]THF

81.4

CH₂PCl₂(17)

[D₈]toluene

[D₈]THF

80.9 [169.1]

87.8 “40.2” ͗227.7͘, 666.2

227.7

–

181.4 “40.2”

91.5 “44.8”,

182.2 “44.8”

͗227.7, 8.1͘

–

CH₂CH₂PCl₂(18)

[D₈]toluene

80.7

13.9

26.5 (57.2) (10.2),

38.3 (50.6) (17.4)

101.4 “6.4” ͗237.7͘, 637.7 ͗237.1͘ 237.1

187.7 “6.4”

n

³¹P,¹³

C

⁷⁷Se,¹³

C

⁷⁷Se,³¹

are given in

[a] Coupling constants J

are given in parentheses (Ϯ0.5 Hz); J

are given in square brackets [Ϯ0.5 Hz]; J

angle brackets ͗Ϯ0.5 Hz͘; ⁿJ

_Pare given in quotation marks “Ϯ0.5 Hz”; ¹Δ^10/11B[¹³C(carb)]^[19]are given in braces {Ϯ 0.5 ^PHz}; isotope-

³¹P,³¹

1

induced chemical shifts Δ are given in ppb, and the negative sign denotes a shift of the NMR signal of the heavy isotopomer to a lower

3

frequency. [b] |¹J

⁷⁷Se,³¹

P

⁷⁷Se,³¹

+ J _P| = 218.0 (in CD₂Cl₂), 207.0 (in [D₈]toluene), and 221.0 Hz (in [D₈]THF).

n

The isotope-induced chemical shifts Δ^12/13C(³¹P) (n = 1, assumption of an ABX spin system, instead of an AAЈX

2) are also essential for the simulation of the complex ¹³C system, in which A and B are ³¹P nuclei that become chemi-

NMR spectra (for example, that of 16 is shown in Figure 2). cally different because of ⁿΔ^12/13C(³¹P) (n = 1, 2). Again, we

As has been noted for other 1,2-diphosphinylethane deriva- note that the ¹³C NMR signals for the carborane ¹³C nuclei

tives,^[20]the interpretation of ¹³C NMR spectra requires the (Figure 2) can only be simulated by taking into account a

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Figure 1. NMR spectra of 11 in CD₂Cl₂at 23 °C. (A) 125.8 MHz ¹³C{¹H} NMR spectrum of 11. The typical pattern^[19]for the isotope-

1

induced chemical shift Δ^10/11B(¹³C_carb) is observed. (B) 500.13 MHz H(PCH₂) NMR spectrum of 11. (C) 202.5 MHz ³¹P{¹H} NMR

77

1

13

n

⁷⁷Se,³¹

P

³¹P,¹³

C

(n = 1, 2) are marked

spectrum (refocused INEPT) of 11. The Se satellites for J

are marked by ٌ. The C satellites for J

by arrows; the isotope-induced chemical shifts Δ^12/13C(³¹P) (n = 1, 2; Ϯ1 ppb) are given. (D) 95.4 MHz ⁷⁷Se NMR spectrum of 11.

n

rather large value |²Δ^12/13C(³¹P)| = 70 ppb. The magnitude erted by the different selenium isotopes can be regarded as

of the ⁿJ

³¹P,³¹

coupling constants in 15 and 16 depend negligible.

P

markedly on the solvent (Table 1), which indicates that they

have different preferred conformations because of distinct

solute–solvent interactions.

Figure 3. Experimental (CD₂Cl₂, at 23 °C) and simulated ³¹P and

⁷⁷Se NMR spectra of 15, revealing the coupling constants as shown

(A = ³¹P, X = ⁷⁷Se). Some additional weak intensities arise from

species containing two ⁷⁷Se nuclei (AAЈXXЈ spin system; the

AAЈX₂spin system was not considered, because of the low natural

abundance of ⁷⁷Se).

Figure 2. Experimental (CD₂Cl₂at 23 °C) and simulated ¹³C NMR

77

spectra of 16 [A, B = ³¹P, X = ¹³C, Y = Se; ¹J

⁷⁷Se,³¹

_P= –242.5 Hz,

2

⁴J

= +3.0 Hz, J

⁷⁷Se,³¹

P

⁷⁷Se,¹³C_CH2

= 0 Hz].

Dimerization of 1,3,2-Diselenaphospholanes

For complex ³¹P and ⁷⁷Se NMR spectra (e.g., those of

Annelation with a carborane unit increases the ring

16 and 15), AAЈX and minor intensity AAЈXXЈ spin sys- strain in 1,3,2-diselenaphospholanes, in particular, if the

tems can be assumed (Figure 3), as the isotope effects ex- substituent R at the phosphorus atom is bulky. The rigid

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Scheme 3. Dimerization of 2-alkyl-1,3,2-diselenaphospholanes.

carborane cage cannot avoid contacts with R in the axial The low solubility of the dimer 20 enables its separation

position (see A); this forces bulky R groups such as tBu from 9 and 9(Se) (Figure 4, B]. The addition of THF causes

into an equatorial position (see AЈ). As this unfavorable sit- immediate dissociation of 20 into 9 (Figure 4, C), which is

uation represents a bad compromise, dimerization appears almost complete after 30 min at 50 °C (Figure 4, D). This

to be the way out, at least for R = alkyl (Scheme 3).

behavior together with the strong solvent dependence of

For R = iPr (8), the dimer 19 forms only in ca. 10–15% δ³¹P for the monomer 9 indicates a bonding interaction be-

in concentrated reaction solutions of 5 with iPrPCl₂in tolu- tween THF and the 1,3,2-diselenaphospholane.

ene at room temp. In tetrahydrofuran (THF), the equilib-

The situation is different for R = tBu (10 and 21); dimer-

rium shifts almost completely towards the monomer, ac- ization of 10 towards 21 was irreversible under the experi-

companied by formation of a minor amount of the selenide mental conditions (Scheme 4). In contrast to its effect on 8

8(Se). For R = cyclohexyl (Cy, 9), reversible dimerization and 9, the addition of THF as a solvent increases the speed

occurs in toluene solution to form 20 in only ca. 15–20% of dimerization of 10, which already occurs in [D₈]toluene

at room temp. and ca. 30–40% at –30 °C, at which tempera- or CD₂Cl₂at room temp. Although the dimers 19 and 20

ture a white powder forms because of the low solubility of dissociate to some extent into the monomers in toluene

20. The dimer 20 dissociates in THF at 50 °C after 1 h, solution at 100 °C, this is not the case for 21.

again accompanied by the formation of a small amount of

Monitoring of the dimerization of 10 by ³¹P NMR spec-

the selenide 9(Se) (see Experimental Section). The NMR troscopy (Figure 5) showed first the sharp ³¹P NMR signal

spectroscopic data of the dimers and selenides are listed in of 10 and broad unresolved ³¹P NMR signals in the region

Tables 2 and 3, respectively.

assigned to the dimer, which probably arise from stereoiso-

The dimerization process for 9 is demonstrated by the mers and/or oligomers (Figure 5, A). The addition of THF

³¹P NMR spectra measured under different conditions (Figure 5, B) reduced the amount of the monomer and con-

(Figure 4). We note a pronounced effect of the solvent THF verted the broad signals into two sharp signals. Compound

on δ³¹P of the monomer 9 (see Figure 4, A and C); in con- 21Ј possesses almost identical NMR parameters as those of

trast, a small effect on δ³¹P of the dimer 20 was observed. 21 and could be a trimer. After 2 d in THF at room temp.

Table 2. ¹³C, ³¹P, and ⁷⁷Se NMR spectroscopic data^[a]of the ortho-carborane derivatives (Se₂PR dimer).

R

Solvent

Dimer (exp.)

Dimer (calcd.)

δ¹³C(C_carb) δ⁷⁷Se

δ¹³C(C_carb

)

²J

Other δ¹³C [ppm]

δ³¹P [ppm] δ⁷⁷Se

δ³¹P

³¹P,¹³C_carb

[ppm]

[Hz]

[ppm]

iPr (19)

Cy (20)

CD₂Cl₂

76.5 [166.0] 27.5

{–9.6}

76.8 [165.9] 27.8

{–12.4}

20.6 (15.5),

115.3

͗232.6͘

108.0

͗233.4͘

106.7

͗231.2͘

524.1

͗233.0͘

524.1

͗232.9͘

521.8

͗232.5͘

100.4

626.5

197.7

34.4 (32.6) [10.6]

25.9 (1.4), 27.3 (11.1),

30.9 (13.7), 43.8 (34.2)

25.6, 26.9 (10.9),

30.5 (13.6),

–

[D₈]toluene 76.6 [165.8] 27.5

{–9.9}

43.3 (34.2)

tBu (21), (dimer)

CD₂Cl₂

[D₈]THF

CD₂Cl₂

77.0 {–11.0} 28.1

28.1 (16.4),

39.4 (39.2)

28.3 (16.4) [2.5],

39.9 (34.4) [7.2]

28.2 (16.2)

129.3

͗243.7͘

129.7

͗240.9͘

129.8

522.6

͗241.6͘

523.1

͗241.2͘

501.3

͗228.4͘

–

100.6

596.5

–

219.9

–

78.0 [168.0] 28.5

{–10.4}

–

tBu (21Ј), (trimer)

76.2

30.0

–

H

–

102.1^[b]

617.0

67.8

n

³¹P,¹³

1

C

⁷⁷Se,¹³

C

⁷⁷Se,³¹

P

are given in

[a] Coupling constants J

are given in parentheses (Ϯ0.5 Hz); J

are given in square brackets [Ϯ0.5 Hz]; J

angle brackets ͗Ϯ 0.5 Hz͘; Δ^10/11B(¹³C_carb

the negative sign denotes a shift of the NMR signal of the heavy isotopomer to a lower frequency. [b] J

)

are given in braces {Ϯ 0.5 Hz}; isotope-induced chemical shifts Δ are given in ppb, and

[19]

1

2

1

³¹P,¹³C_carb

⁷⁷Se,¹³

C

=

= +23.5 Hz; J

1

⁷⁷Se,³¹

P

–197.7 Hz; J

= –176.9 Hz.

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Table 3. ¹³C, ³¹P, and ⁷⁷Se NMR spectroscopic data^[a]of the ortho-carborane derivatives (P=Se, P=S).

³¹P,¹³C_carb

Solvent

δ¹³C(C_carb

)

²J

Other δ¹³C

δ³¹P

δ⁷⁷Se

[ppm]

[Hz]

[ppm]

iPr–P(Se₂)=Se [8(Se)] ^[11]

Cy–P(Se₂)=Se [9(Se)]

CD₂Cl₂

75.7 [163.0] {–8.7} 7.3

75.4 {–8.8} 7.2

18.5 (1.8),

48.2 (26.6)

25.1 (2.8),

25.8 (17.8),

28.6 (4.4),

92.8 ͗363.7͘ ͗802.5͘

83.8 ͗358.1͘ ͗808.0͘

716.9 ͗364͘ (P–Se),

60.9 ͗802͘ (P=Se)

726.9 ͗359.0͘ (P–Se),

139.8 ͗809.6͘ (P=Se)

[D₈]toluene

57.4 (25.0)

tBu–P(Se₂)=Se [10(Se)]

[D₈]toluene

74.1 [161.6] {–8.2} 6.3

26.7 (3.0),

50.2 (22.2) [4.2]

21.4 (0.7),

106.7 ͗346.9͘ ͗807.8͘ 736.0 ͗347.8͘ (P–Se),

290.5 ͗807.8͘ (P=Se)

(3,5-Me-C₆H₃)CH₂P(Se₂)=Se CD₂Cl₂

[11(Se)]

75.9 {–8.2}

7.1

64.6 ͗363.3͘ ͗802.9͘

738.3 ͗363.4͘ (P–Se),

183.9 ͗803.5͘ (P=Se)

57.5 (23.5) [4.9],

128.8 (7.7) C_o,

130.8 (6.7) C_p,

130.9 (10.8)C_i,

138.9 (5.6) C_m

129.4 (16) C_m,

132.8 (13) C_o,

134.0 (4) C_p,

135.2 (57)C_i

–

Ph–P(Se₂)=Se [12(Se)]^[8,11]

CD₂Cl₂

75.5 [161] {–8.0}

6.0

49.6 ͗350.7͘ ͗815.6͘

802.1 ͗350.2͘ Ӷ34ӷ (P–Se),

251.4 ͗815.4͘ Ӷ34ӷ (P=Se)

[D₈]toluene

CD₂Cl₂

–

46.9 ͗348.9͘ ͗827.2͘

67.8 ͗448.8͘ ͗869.2͘

52.4 ͗359.7͘ ͗855.3͘

91.3 ͗361.5͘ (33.5)

805.1 ͗350.2͘ (P–Se),

261.3 ͗825.1͘ (P=Se)

797.2 ͗449͘ (P–Se),

104.4 ͗869͘ (P=Se)

767.2 ͗360.5͘ (P–Se),

304.7 ͗857.0͘ (P=Se)

740.2 ͗362.1͘

EtO–P(Se₂)=Se [13(Se)]^[11]

Et₂N–P(Se₂)=Se [14(Se)]

–

[D₈]toluene

CD₂Cl₂

(3,5-Me-C₆H₃)CH₂P(Se₂)=S

[11(S)]

73.8 [160.6] {–9.0} 6.2

21.4,

57.5 (33.6),

128.6 (7.7) C_o,

130.7 (11.1)C_i,

130.8 (6.4) C_p,

139.1 (5.3) C_m

21.36 (0.8),

(3,5-Me-C₆H₃)CH₂P(Se₄)=Se CD₂Cl₂

(25)

80.3 {–10.5}

2.9

24.8 ͗28.2͘ ͗439.0͘

͗730.5͘

698.2 ͗27.5͘ (C–Se),

558.0 ͗439.4͘ (P–Se),

–51.9 ͗726.9͘ (P=Se)

46.9 (18.8),

129.1 (7.7) C_o,

129.7 (9.5)C_i,

130.8 (6.7) C_p,

138.9 (5.1) C_m

19.4 (2.2),

28.2 (43.1)

37.2 (42.4) (PC) 40.3 ͘478.0͗ ͗805.0͘

C–PH(iPr)=Se (22)

C–PH(Cy)=Se (23)

CD₂Cl₂

62.7 (CH),

63.7 (PC)

62.7 (CH),

63.5 (PC)

21.8

20.3

47.1 ͘477.5͗ ͗798.5͘

467.5 ͗797.8͘

140.1 ͗805.0͘

[D₈]toluene

n

31 13

⁷⁷Se,¹³

C

⁷⁷Se,³¹

P

are given in

[a] Coupling constants J

are given in parentheses (Ϯ0.5 Hz); J

are given in square brackets [Ϯ0.5 Hz]; J

C

³¹P,¹H

angle brackets ͗Ϯ0.5 Hz͘;^P,ⁿJ

are given in angle brackets ͘Ϯ0.5 Hz͗; ²J

are given in quotation marks “Ϯ0.5 Hz”; ¹Δ^10/

⁷⁷Se,⁷⁷Se

¹¹B(¹³C_carb

)

are given in braces {Ϯ0.5 Hz}; isotope-induced chemical shifts Δ are given in ppb, and the negative sign denotes a shift

[19]

1

of the NMR signal of the heavy isotopomer to a lower frequency.

(Figure 5, C), the monomer was almost consumed, the sig-

nal for 21Ј had disappeared, and that for the selenide 10(Se)

was still present and slightly more intense than at the begin-

ning. We isolated crystalline samples of 21 that were suit-

able for X-ray analysis (see below), and after redissolving

this material, the identity with 21 in the reaction solution

was evident. In particular, the ⁷⁷Se NMR parameters (Fig-

ure 5, D and F) proved helpful. With excess tBuPCl₂for

the synthesis of 10, the formation of the expected monomer

10 was observed, together with a small amount of acyclic

Since the monomers 8–10 can be converted partly (8, 9;

derivatives B₁₀H₁₀C₂[SeP(tBu)Cl]₂(δ³¹P

=

187.2 and R = iPr, Cy) or completely (10; R = tBu) into the dimers

187.9 ppm in [D₈]toluene).

after some time at room temp. or by heating, this was also

Although the dimers 19–21 survived in toluene at 100 °C, investigated with 11 [R = CH₂(3,5-Me₂C₆H₃)], 12 (R =

slow decomposition became evident, for example, by the Ph),^[8]13 (R = OEt), and 14 (R = NEt₂; Scheme 5). Al-

formation of small amounts of 22, 23, and 24^[21]as side though dimers did not form, the respective selenides 11(Se),

products, which were also present when solutions of the di- 12(Se),^[11]13(Se),^[11]and 14(Se) could be identified (NMR

mers were kept in THF for prolonged periods of time.

spectroscopic data in Table 3), in addition to numerous un-

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Scheme 4. Irreversible dimerization of 10 via a mixture of stereoisomers towards pure 21.

identified decomposition products. The absence of dimers

for R = Ph and CH₂-(3,5-Me₂)C₆H₃is remarkable, as the

analogous oxygen and sulfur derivatives A (E = O, S), in

which apparently the ring strain is greater, dimerize read-

ily.^[4,6]By heating 11 in [D₈]toluene solution at 100 °C for

20 h, the selenide 11(Se) was observed in a mixture with 25,

as a result of further insertion of selenium. Similar to pre-

vious findings (for R = iPr, Ph),^[11]compound 25 could be

prepared independently as a single isomer by oxidation of

11 with excess selenium. Oxidation with sulfur led only to

the sulfide 11(S) (Table 3, Supporting Information:

Scheme S1 and Figure S1).

1,3,2-Ditelluraphospholanes

The reactions of the dilithium compound 4 with three

organophosphorus dichlorides RPCl₂(R = iPr, tBu, Ph)

and Et₂NPCl₂were performed (Scheme 6). Although the

desired 1,3,2-ditelluraphospholanes 26a–26d were the major

products, their formation was accompanied by many side

products, some of which could be identified. For instance,

the bis(ditellane) 31^[17]was always present in the reaction

mixtures, as shown by its ¹²⁵Te NMR signal (Figure 6). Ex-

cept for the formation of 31, the reaction of 4 with bis(di-

chlorophosphanyl)methane (Scheme 7) afforded the desired

product 32 without significant amounts of side products.

The NMR spectra (experimental and simulated; Figure S2)

support the proposed structure, which corresponds to that

determined for the selenium analogue 15. Compounds 26

and 32 appear to be air- and moisture-sensitive and also

decompose in solution or in the solid state in daylight.

When crystalline materials were collected for X-ray analysis,

decomposition upon irradiation was observed at low tem-

perature. The proposed structures of 26a–26d follow con-

clusively from the consistent NMR spectroscopic data

Figure 4. 202.5 MHz ³¹P{¹H} NMR spectra of the reaction solu-

tions obtained from the reaction of 5 with CyPCl₂. (A) [D₈]Toluene

at 25 °C after 1 d at room temp.; the mixture contains 9 and 20

together with 9(Se). (B) Compound 20 after 1 d in CD₂Cl₂at 25 °C.

(C) Compound 20 after 1 h in [D₈]THF at room temp. (D) The

same solution as that in (C) after 30 min at 50 °C.

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Figure 5. NMR spectra of the reaction solution obtained from the reaction of 5 with tBuPCl₂. (A) 202.5 MHz ³¹P{¹H} NMR spectrum

(in [D₈]toluene, 25 °C) of the mixture of 10 and stereoisomers including 21 (after 2 h at room temp. in [D₈]toluene). (B) 202.5 MHz

³¹P{¹H} NMR spectrum ([D₈]THF, 25 °C); note the solvent dependence of δ³¹P of 10) of the mixture of 10 and 21/21Ј (possibly a trimer)

after 2 h at room temp. in [D₈]THF. (C) 202.5 MHz ³¹P{¹H} NMR spectrum ([D₈]THF) of the dimer 21 together with 10 (5%) and

10(Se) (5%) after 2 d at room temp. in [D₈]THF. (D) ³¹P{¹H} NMR spectrum ([D₈]toluene, 25 °C) of the separated fraction of the less

soluble solid (21/21Ј) from the reaction of 5 with tBuPCl₂in [D₈]toluene. (E) The same solution as that in (D) after 20 h at room temp.

(F) 95.4 MHz ⁷⁷Se NMR spectrum of the same mixture as that in (E).

Scheme 5. Conversion (and partial decomposition) of the monomers 11, 12, 13, and 14 into the respective selenides by heating or over

time at room temp.

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Scheme 6. Attempted syntheses of 1,3,2-ditelluraphospholanes 26a–26d.

Scheme 7. Reaction of 4 with bis(dichlorophospino)methane.

(Table 4; Figures 6 and 7), and dimerization was not ob- Molecular Orbital Calculations – Molecular Geometries,

served, even for R = tBu (26b). By contrast with the selen- NMR Parameters

ium analogues, for which the NMR spectroscopic data

strongly suggest a different preferred conformation for R =

The gas-phase geometries of most 1,3,2-diselenaphos-

tBu (10), the three 1,3,2-ditelluraphospholanes 26a–26c pholanes and their respective dimers were optimized at the

seem to possess similar structures in solution (see below), B3LYP/6-311+G(d,p) level of theory.^[23]The structures of

that is, the usual envelope structure with the phosphorus the 1,3,2-ditelluraphospholanes 26 were also optimized at

atom in the flap and the phosphorus substituent in the axial the B3LYP/6-311+G(d,p) level by using pseudopotentials

position. According to calculated structures, the NEt₂de- for Te.^[24]For the monomeric selenium compounds, both

rivative 26d adopts a conformation with the NEt₂group in structures corresponding to A and AЈ were optimized, if

an equatorial position, as in the analogous selenium com- possible, and the NMR parameters [chemical shifts and

pound 14. The NMR spectra shown in Figure 7 give an coupling constants, Table S2] were calculated at the same

idea of the purity that can be achieved under favorable con- level of theory. For the dimers, only chemical shifts were

ditions. The cyclic structures of the side products shown in calculated, except for dimer with R = H (not available ex-

Scheme 6 are proposed mainly on the basis of ³¹P and ¹²⁵Te perimentally; Table 2).

NMR spectroscopic data, and the various ¹²⁵Te–³¹P and

The comparison of the relevant calculated^[25,26]and ex-

³¹P–³¹P coupling constants were the most useful parameters perimental NMR spectroscopic data for the 1,3,2-disel-

(see Figure 6).

enaphospholanes indicates that structure A is preferred over

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Figure 6. NMR spectra of the solution obtained from the reaction of 4 with iPrPCl₂in [D₈]toluene at 23 °C. Upper trace: 202.5 MHz

³¹P{¹H} NMR spectrum (refocused INEPT)^[22]showing the mixture of 26a, 27a, 28a, 29a/29aЈ, and 30a. Lower trace: 157.9 MHz ¹²⁵Te

NMR spectrum of the same mixture. Question marks indicate unidentified products.

AЈ except for the heterocycles with P–tBu (10) and P–NEt₂structure of type AЈ,^[8]whereas the NMR parameters, in

(14) units. The tBu group is forced into an equatorial posi- light of the present results, clearly suggest dominant contri-

tion (AЈ) mainly for steric reasons. In the P–NEt₂unit, an butions of the structure of type A. Therefore, ring inversion

orthogonal arrangement of the assumed orientations of the in solution is a likely process, and the solution-state NMR

lone pairs of electrons of the phosphorus and nitrogen spectroscopic data represent the average from different con-

atoms can be conveniently accommodated solely with the formations. For 11 and 15, the NMR parameters (exp. and

NEt₂group in the equatorial position (AЈ), as in the axial calcd.) agree well with those of type A structures, both in

position one ethyl group would be too close to the carbor- the solid state and in solution. The calculated differences in

2

³¹P,¹³C_carb

ane skeleton. This is mirrored by the J

coupling energies for structures A and AЈ show that 12 (R = Ph)

constants, which are close to zero for AЈ and much larger with gas-phase structure A is slightly more stable than AЈ

and positive for A. The ³¹P nuclei in A are better shielded (–1.1 kcal/mol) and 8 (R = iPr) with structure A is more

than those in AЈ, and the opposite is true for the carborane stable than AЈ (–3.8 kcal/mol), in contrast to 10 (R = tBu),

2

¹³C nuclei. The J

coupling constants measured for for which AЈ is more stable than A (–1.9 kcal/mol).

³¹P,¹³C_carb

the dimers 19–21 are larger than those for the monomers

The optimization of the gas-phase geometries for the

with type A structures,^[6]in agreement with the calculated 1,3,2-ditelluraphospholanes 26a–26c leads to energy min-

value for the hypothetical dimer with R = H (²J

=

ima only for structures of type A. Apparently, longer Te–C

³¹P,¹³C_carb

+24.5 Hz; Table 2).

and Te–P bond lengths significantly reduce the repulsive

It should be noted that the important features of the ex- interactions in the five-membered rings when compared

perimentally determined solid-state molecular structures do with the selenium homologues. Again, the values for the

not necessarily agree with the situation in solution. Thus, ²J

coupling constants are indicative of the type A

³¹P,¹³C_carb

in the case of 12, the X-ray structural analysis revealed a structure, as the experimental data are well reproduced by

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Table 4. ¹³C, ³¹P, and ¹²⁵Te NMR spectroscopic data^[a]of the ortho-carborane derivatives 26–30 and 32.

³¹P,¹³C_carb

R

Solvent

δ¹³C(C_carb

)

ⁿJ

Other δ¹³

C

δ³¹

P

δ¹²⁵Te

Type

[ppm]

[Hz]

[ppm]

iPr (26a)

[D₈]toluene 58.2 [445.2] {–8.2}

16.3 (²J),

calcd. +15.3

20.2 (25.9), 28.1

(46.0)

17.2 ͗473.0͘

͘391.9͗ (46.0) (¹J)

(25.8) (²J)

1271.5^[b]͗473.2͘

A

CD₂Cl₂

58.1 [446] {–8.0}

15.5 (²J)

20.6 (25.8), 28.4

(45.8)

28.9 (20.7), 35.0

(57.7)

16.2 ͗474.9͘

1264.9 ͗475.9͘

A

[c]

tBu (26b)

Ph (26c)

[D₈]toluene 56.5 [460] {–7.2}

[D₈]toluene 59.3{–8.4}

14.4 (²J),

calcd. +14.4

39.7 ͗426.1͘

͘353.5͗ (57.5) (¹J)

(21.0) (²J)

1230.4 ͗426.1͘

17.6 (²J),

calcd. +18.9

129.0 (3.4) C_m,

129.4 (1.6) C_p,

132.3 (18.3) C_o,

n.o. C_i

5.0 ͗530.6͘

1317.6 ͗533.2͘

A

Et₂N (26d)

(C₂B₁₀Se₂P)₂CH₂[D₈]toluene 58.8

(32)

[D₈]toluene

–

calcd. +0.3

14.7

–

89.7 ͗438.9͘

1416.2 ͗438.4͘

AЈ

A

[d]

25.8 (68.8)

4.9 ͗–421.0͘

1268.8

“122.0” ͗+31.0͘ ͘–

349.0͗ ͘+25.0͗

41.4 (d) “312.3”

͗520.9͘

͘431.4͗ (23.0),

74.8 (d) “312.3”

iPr (27a)

[D₈]toluene 100.0 (C–P),

57.0 (C–Te, pseudo-t)

106.3 (¹J),

8.9 (²J)

20.6 (24.8) (9.4),

21.3 (21.2) (9.4),

22.3 (22.7) (6.1),

23.1 (29.1) (4.1),

26.4 (30.7) (9.8),

28.7 (20.4) (8.6)

–

1068.4 ͗520͘,

1093.1

tBu (27b)

Ph (27c)

[D₈]toluene

–

49.1 (d) “287.6”

͗415.9͘,

969.1 ͗415.0͘

1083.3 ͗588͘

95.4 (d) “287.6”

49.1 (d) “304.5”

͗587.7͘,

[D₈]toluene 99.1 (C–P),

56.9 (C–Te, pseudo-t)

104.0 (¹J),

8.5 (²J)

[409]

–

61.0 (d) “304.5”

Et₂N (27d)

iPr (28a)

tBu (28b)

[D₈]toluene

–

111.0 (d) “196.9” 752.3 ͗260͘

͗253.8͘, 113.0 (d)

“196.9”

[D₈]toluene 91.6 (C–P),

39.3 (C–Te) [267]

100.8 (¹J)

66.8 ͗448.9͘

560.5 ͗449͘

Ӷ1885ӷ,

913.3 Ӷ1885ӷ

447.4 ͗371.8͘

Ӷ1870ӷ,

[D₈]toluene 88.7 (C–P) {–7.5}, 39.6 123.6 (¹J)

28.9 (17.9), 38.1

(44.2)

96.2 ͗371.5͘

(C–Te)

923.0 Ӷ1870ӷ

433.1 (t) ͗385͘

566.3 (t) ͗443͘

147.7 (t) ͗488͘

262.0 (t) ͗500͘

952.8 ͗651.0͘

1079.9 ͗640͘

iPr (29a)

[D₈]toluene 95.6 (C–P)

[D₈]toluene 97.0 (C–P)

108.7 (¹J)

–

55.1 ͗385.1͘

49.2 ͗443.1͘

92.2 ͗490.4͘

105.6 ͗501.8͘

96.7 ͗651.0͘

107.2 ͗641.1͘

͘536.1͗

iPr (29aЈ)

Et₂N (29d)

Et₂N (29dЈ)

iPr (30a)

110.5 (¹J)

[D₈]toluene

–

tBu (30b)

[D₈]toluene 75.9 (C–P, d) {–10.0},

93.9 (¹J),

29.1 (br),

38.1 (39.8)

43.1 (C–Te, dd) {–10.0} 37.5, 48.2 (²J)

n

³¹P,¹³

C

¹²⁵Te,¹³

C

¹²⁵Te,³¹

P

are given in square brackets [Ϯ0.5 Hz]; J

[a] Coupling constants J

brackets ͗Ϯ0.5 Hz͘; ⁿJ

are given in parentheses (Ϯ0.5 Hz); J

are given in angle

are given in

are given in angle brackets ͘Ϯ0.5 Hz͗; ⁿJ

are given in quotation marks “Ϯ0.5 Hz”; ¹J

¹²³Te,³¹

P

³¹P,³¹

P

¹²⁵Te,¹²⁵Te

double angle brackets ӶϮ0.5 Hzӷ; ¹Δ^10/11B(¹³C_carb

)

^[19]are given in braces {Ϯ 0.5 Hz}; isotope-induced chemical shifts Δ are given in ppb, and

1

the negative sign denotes a shift of the NMR signal of the heavy isotopomer to a lower frequency; n.o. = not observed. [b] δ¹²³Te = 1271.7 ppm

(¹J

= 391 Hz). [c] δ¹²³Te = 1229.3 ppm (¹J

= 353.9 Hz). [d] |¹J

+ J

_P| = 390 Hz; δ¹²³Te = 1267.8 ppm.

¹²⁵Te,³¹

3

¹²³Te,³¹

P

¹²³Te,³¹

P

¹²⁵Te,³¹

P

the calculated data (Tables 4 and S2) for the type A geome- vored with respect to the monomers by –0.5 kcal/mol. By

try. For the NEt₂derivative 26d, the optimization of the contrast, the dimer for R = tBu (21) is much more favored

gas-phase geometry converged to structure AЈ.

by –7.8 kcal/mol.

The experimental observations for the dimerization of

the 1,3,2-diselenaphospholanes are reflected by the calcu-

lated relative energies. A dimer for R = H was not ob-

served,^[10]in agreement with calculations, which show that

the dimer is energetically slightly less favored than two

monomers (+0.3 kcal/mol). The dimer with R = iPr (19)

X-ray Structural Analyses of the ortho-Carborane

Derivatives 11, 15, and 21

The molecular structures of 11, 15 and 21 are shown in

was experimentally observed and found to be slightly fa- Figures 8–10. The carborane units possess typical structural

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Figure 7. (A) 125.8 MHz ¹³C{¹H} NMR spectrum of 26a in CD₂Cl₂at 23 °C; the typical pattern^[19]for the isotope-induced chemical

shift ¹Δ^10/11B(¹³C_carb) is observed. (B) 202.5 MHz ³¹P{¹H} NMR spectrum (refocused INEPT)^[22]of 26a in [D₈]toluene at 23 °C. The

1

123

1

13

n

¹²⁵Te satellites for J

are marked by ٌ; the Te satellites for J

are marked by asterisks. The C satellites for J

are

¹²⁵Te,³¹

P

¹²³Te,³¹

P

³¹P,¹³

C

marked by arrows; the isotope-induced chemical shifts Δ^12/13C(³¹P) are given (Ϯ1 ppb). Note the absence of such an effect (n = 2) for

n

the ¹³CH₃groups in contrast to the carborane ¹³C nuclei.

parameters^[27,28]that differ in the C–C bond lengths the dimer 21, the four selenium atoms form a plane (mean

(shorter in 11 and 15, ca. 10 pm longer in 21). The structure deviation 1.4 pm). All distances and angles are found in the

of 11 corresponds to that of the iodide 7,^[10]and the folding expected ranges (Table 5).

of the C–C–Se–P–Se rings along the Se···Se axis is also sim-

ilar (154.7° for 11 and 158.4° for 7). The main structural

properties of both halves of 15 are similar to those of 11

(the angles between the Se–C–C–Se/Se–P–Se planes are

151.9 and 154.7°, Table 5). Expectedly, the structure of the

dimer 21 is closely related to that of the sulfur analogue.^[6]

For all three compounds studied here, the four atoms C–

C–Se–Se are in a plane (close to the experimental error). In

Figure 8. ORTEP plot (40% probability; hydrogen atoms omitted

for clarity) of the molecular structure of 11 (for selected distances

and angles, see Table 5).

Figure 9. Two views of ORTEP plots (40% probability; hydrogen

atoms omitted for clarity) of the molecular structure of 15 (for

selected distances and angles, see Table 5).

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bis(dichlorophosphanyl)methane (95%), 1,2-bis(dichlorophos-

phanyl)ethane, selenium (powder, 100 mesh, 99.99% trace metals

basis), sulfur (powder, 99.98% trace metals basis), tellurium (pow-

der, 200 mesh, 99.8% metals basis)]. Most syntheses were per-

formed on small scales sufficient for NMR studies. Owing to the

small scale of the reactions, the sensitivity of the compounds to

hydrolysis, and the multiple reaction pathways, it proved difficult

to obtain materials suitable for elemental analysis. Furthermore,

small carbon content and high boron content caused problems in

reproducibility. NMR measurements were performed with a Bruker

DRX 500 spectrometer. ¹H, ¹¹B, ¹³C, ³¹P, ⁷⁷Se, ¹²⁵Te, and ¹²³Te

chemical shifts are given relative to Me₄Si [δ¹H = 5.33 (CHDCl₂),

2.08 (Ϯ0.01) ppm (C₆D₅CD₂H); δ¹³C = 53.8 (CD₂Cl₂), 20.4

(C₆D₅CD₃), 25.4 (Ϯ0.1) ppm (C₄D₈O)], external BF₃·OEt₂[δ¹¹B

= 0Ϯ0.3 ppm for Ξ(¹¹B) = 32.083971 MHz], neat Me₂Se [δ⁷⁷Se =

0Ϯ0.1 ppm for Ξ(⁷⁷Se) = 19.071523 MHz], external aqueous

H₃PO₄[85%; δ³¹P = 0 ppm for Ξ(³¹P) = 40.480747 MHz], and neat

Me₂Te [δ¹²⁵Te = 0 ppm for Ξ(¹²⁵Te) = 31.549802 MHz; δ¹²³Te =

Figure 10. ORTEP plot (50% probability; hydrogen atoms and

CD₂Cl₂omitted for clarity) of the molecular structure of dimer 21

(for selected distances and angles, see Table 5).

1

0 ppm for Ξ(¹²³Te) = 26.169773 MHz]. The assignments of H and

1

¹¹B NMR signals are based on H{¹¹B} selective heteronuclear de-

coupling experiments. Mass spectra (EI, 70 eV) were recorded with

a Finnigan MAT 8500 instrument with a direct inlet (data for ¹²C,

¹H, ¹¹B, ³¹P, ⁸⁰Se, ¹³⁰Te). Melting points were determined with a

Büchi 510 melting point apparatus.

Conclusions

The most convenient access to 1,3,2-diselenaphos-

pholanes with an annelated 1,2-dicarba-closo-dodecabor-

ane(12) unit is provided by cleavage of Si–Se bonds by

phosphorus halides, whereas the corresponding tellurium

derivatives have to be prepared from reactions of the 1,2-

ditellurolato-1,2-dicarba-closo-dodecaborane(12) dianion

[1,2-(1,2-C₂B₁₀H₁₀)Te₂]^2–with phosphorus halides. The sel-

enium compounds are fairly stable and invite further trans-

formations that make use of the P–Se bonds, whereas the

light-sensitive tellurium compounds are obtained in com-

plex mixtures. Depending on the organo group at the phos-

phorus atom, dimerization of the 1,3,2-diselenaphos-

pholanes occurs and leads to ten-membered rings. This was

not observed for the analogous tellurium compounds. Most

phosphorus substituents in the 1,3,2-diselenaphospholanes

prefer the axial position in spite of the repulsive interactions

with the rigid carborane framework. However, the bulky

tBu group and the NEt₂group are forced into the equato-

rial position, for steric (tBu) and electronic (NEt₂) reasons,

as indicated by NMR spectroscopic data and confirmed by

DFT calculations. Other noteworthy NMR parameters are

the isotope-induced chemical shifts exerted by the carbor-

All quantum chemical calculations were performed with the

Gaussian 09 program package.^[29]The optimized geometries at the

B3LYP/6-311+G(d.p) level of theory^[23]were found to be minima

by the absence of imaginary frequencies. The NMR parameters

were calculated^[25,26]at the same level of theory. The calculated

δ¹³C, δ³¹P, δ¹¹B, and δ⁷⁷Se values were converted by δ¹³C (calcd.)

= σ(¹³C, TMS) – σ(¹³C) ppm with σ(¹³C, TMS) = +181 [δ¹³C

(TMS) = 0 ppm], δ³¹P(calcd.) = σ[³¹P, P(OMe)₃] – σ(³¹P) +

138 ppm with σ[³¹P, P(OMe)₃] = 159.8 ppm {δ³¹P = 138 ppm and

δ³¹P[aqueous H₃PO₄(85%)] = 0 ppm}, δ¹¹B (calcd.) = σ(¹¹B) –

σ(¹¹B, B₂H₆) ppm with σ(¹¹B, B₂H₆) = +84.1 [δ¹¹B (B₂H₆) =

18 ppm and δ¹¹B (BF₃·OEt₂) = 0 ppm], and δ⁷⁷Se (calcd.) =

σ(⁷⁷Se) – σ(⁷⁷Se, SeMe₂) ppm with σ(⁷⁷Se, SeMe₂) = +1621.7 ppm.

2-(1-Methylethyl)-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2-di-

selenaphospholane (8): A solution of 5 (74 mg, 0.205 mmol) in [D₈]-

toluene (0.6 mL) was cooled to –20 °C, and iPrPCl₂(0.025 mL,

0.203 mmol) was added through a microsyringe. The progress of

the reaction was monitored by ³¹P and ²⁹Si NMR spectroscopy.

After 1 h at room temp., the mixture contained 8 together with

Me₂SiCl₂. The volatile materials were removed under vacuum (3 h,

8ϫ 10^–3Torr) to give 8 as a white solid; m.p. 100–110 °C (dec.).

¹H{¹¹B} NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.68 (dd,

ane carbon atoms Δ^12/13C(³¹P), which are large in the five-

membered rings and large and unprecedented for n = 2.

n

3

³J

= 21.4 Hz, J₁_H,₁_H= 7.1 Hz, 6 H, CH₃), 2.47 [doublet of

³¹P,¹H

septets (dsept), ²J

= 3.4 Hz, ³J₁_H,₁_H= 7.1 Hz, 1 H, PCH], 2.60

³¹P,¹H

[br. s, 2 H, HB for δ(¹¹B) = –10.5 ppm], 2.66 [br. s, 1 H, HB for

δ(¹¹B) = –7.8 ppm], 2.73 [br. s, 2 H, HB for δ(¹¹B) = –8.4 ppm],

2.79 [br. s, 3 H, HB for δ(¹¹B) = –6.0 ppm], 2.82 [br. s, 1 H, HB for

δ(¹¹B) = –3.3 ppm], 3.13 [br. s, 1 H, HB for δ(¹¹B) = 0.1 ppm] ppm.

¹¹B{¹H} NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –10.5 (2 B),

–8.4 (2 B), –7.8 (1 B), –6.0 (3 B), –3.3 (1 B), 0.1 (1 B) ppm. ¹¹B

Experimental Section

All syntheses and sample handling were performed with necessary

precautions to exclude traces of air and moisture. Carefully dried

solvents and oven-dried glassware were used throughout. CD₂Cl₂

was distilled from CaH₂in an atmosphere of argon. All other sol-

vents were distilled from Na metal in an atmosphere of argon. The

starting silane 5^[15]and [(1,2-C₂B₁₀H₁₀)Te₂Li₂](Et₂O) (4)^[17a]were

prepared according to the published procedures. Other starting ma-

terials were purchased from KatChem (ortho-carborane 1), MCAT

GmbH (3,5-dimethylbenzylphosphorus dibromide), Aldrich [butyl-

NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –10.5 (d, ¹J

=

¹¹B,¹H

1

¹¹B,¹H

172 Hz, 2 B), –8.4 (d, J

= 164 Hz, 2 B), –7.8 (d, 1 B), –6.0

1

¹¹B,¹H

= 156 Hz, 1 B), 0.1 (d,

(d, J

¹¹B,¹H

= 151 Hz, 3 B), –3.3 (d, J

¹J

= 181 Hz, 1 B) ppm. ¹H NMR (500.13 MHz, CD₂Cl₂,

25 °C): δ = 1.18 (dd, ³J₃₁_P,₁_H= 21.6 Hz, ³J₁_H,₁_H= 7.2 Hz, 6 H, CH₃),

2.97 (dsept, ²J

= 3.3 Hz, J₁_H,₁_H= 7.2 Hz, 1 H, PCH) ppm.

3

³¹P,¹H

lithium (1.6 m in hexane), iPrPCl₂(97%), tBuPCl₂(97%), PhPCl₂EI-MS (70 eV): m/z (%) = 374 (10) [M]⁺, 358 (5) [M – CH₄]⁺, 331

(97%), EtOPCl₂(98%), Et₂NPCl₂(97%), CyPCl₂(95%), 1,1-

(15) [M – C₃H₇]⁺, 236 (4), 43 (100).

Eur. J. Inorg. Chem. 2014, 1929–1948

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Table 5. Selected bond lengths [pm] and angles [°] of the ortho-carborane derivatives 11, 11(calcd.), 15, 15(calcd.), 21, 21(calcd.), and

21(S₂).^[6]

11

(calcd.)

15

(calcd.)

21

(calcd.)

21(S₂)^[6]

C(1)–Se(1)

C(2)–Se(2)

C(3)–Se(3)

C(4)–Se(4)

C(1)–C(2)

C(3)–C(4)

Se(1)–P

Se(2)–P

Se(3)–P

Se(4)–P

P(1)–C

P(2)–C

P(1)–Se(1)–C(1)

P–Se(2)–C(2)

P–Se(3)–C(3)

P(2)–Se(4)–C(4)

Se(1)–C(1)–C(2)

Se(2)–C(2)–C(1)

Se(3)–C(3)–C(4)

Se(4)–C(4)–C(3)

Se(1)–P(1)–Se

Se–P(2)–Se(4)

P(1)–C(5)–P(2)

Se(1)–P(1)–C

Se(2)–P–C

194.1(3)

197.0

194.8(4)

194.1(4)

195.3(4)

193.9(4)

163.3(5)

164.1(5)

226.65(13) 230.4

227.06(13) 230.6

227.20(13) 230.9

227.27(13) 231.1

186.6(4)

185.3(4)

100.11(12) 99.6

100.04(12) 99.6

100.08(13) 100.3

100.67(12) 100.2

116.9(3)

117.5(3)

117.0(3)

117.6(3)

97.41(5)

97.96(5)

116.0(2)

104.01(13) 104.9

106.30(14) 104.7

100.86(14) 103.8

106.46(14) 104.2

197.3

197.1

197.3

197.2

163.9

163.7

191.4(11)

198.5(15)

193.3(13)

192.5(13)

173(2)

195.8

177.2

232.7

192.2

101.6

118.8

99.5

C(1)–S(1)

C(2)–S(2)

C(3)–S(3)

C(4)–S(4)

C(1)–C(2)

C(3)–C(4)

S(1)–P(1)

S(2)–P(2)

S(3)–P(1)

S(4)–P(2)

P(1)–C

P(2)–C

P(1)–S(1)–C(1)

P(1)–S(3)–C(3)

P(2)–S(2)–C(2)

P(2)–S(4)–C(4)

S(1)–C(1)–C(2)

S(2)–C(2)–C(1)

S(3)–C(3)–C(4)

S(4)–C(4)–C(3)

S(1)–P(1)–S(3)

S(2)–P(2)–S(4)

178.3(7)

178.5(8)

177.9(9)

178.3(9)

175.6(10)

181.3(11)

213.5(3)

214.1(3)

213.5(3)

214.4(3)

186.6(8)

188.6(9)

103.1(3)

102.8(3)

101.4(3)

103.2(3)

116.7(5)

117.9(5)

114.0(6)

119.3(6)

98.39(12)

98.48(11)

194.4(3)

197.4

–

164.0(3)

163.7

–

175(2)

226.77(8)

231.6

227.1(3)

226.9(4)

227.0(4)

227.9(4)

187.6(16)

189.2(16)

99.7(4)

100.1(4)

100.3(4)

100.8(4)

119.0(9)

116.1(8)

117.9(8)

118.4(8)

98.94(15)

99.36(15)

226.37(10)

231.3

–

186.4(3)

189.0

189.3

188.1

–

101.17(7)

100.6

100.60(8)

100.5

–

116.49(17)

117.9

117.7

117.5

117.8

118.0

97.1

117.62(18)

117.9

–

97.51(3)

97.5

98.0

107.8

99.5

104.86(9)

104.5

98.9(5)

100.0(5)

100.2(5)

99.6(5)

1.1

101.0

101.1

101.0

S(1)–P(1)–C

S(2)–P–C

S(3)–P–C

S(4)–P–C

plane S(1)–C(1)–

C(2)–S(2) Δ [pm]^[a]

plane S(3)–C(3)–

C(4)–S(4) Δ [pm]^[a]

99.4(3)

99.7(4)

98.8(3)

99.2(3)

0.02

105.39(10)

105.3

–

Se(3)–P–C

–

Se(4)–P–C

101.0

Se(1)–C(1)–C(2)–Se(2) Δ [pm]^[a]0.19

0.3

–

Se(3)–C(3)–C(4)–Se(4) Δ [pm]^[a]

1.7

1.1

0.08

–

Distance of P(1) from the plane 63.8

Se(1)–C(1)–C(2)–Se(2) [pm]

Distance of P(2) from the plane

70.5

–

63.7

Se(3)–C(3)–C(4)–Se(4), [pm]

Se(1)–Se(2)–Se(3)–Se(4) Δ [pm]^[a]

1.4

plane S(1)–S(2)–

S(3)–S(4) Δ [pm]^[a]

distance of P(1)

from the plane S(1)–

S(2)–S(3)–S(4)

distance of P(2)

from the plane S(1)–

S(2)–S(3)–S(4)

0.9

–

Distance of P(1) from the plane

Se(1)–Se(2)–Se(3)–Se(4) [pm]

129.5

120.5

–

Distance of P(2) from the plane

Se(1)–Se(2)–Se(3)–Se(4) [pm]

130.8

121.4

–

Plane Se(1)–C(1)–C(2)–Se(2)/

plane Se(1)–P(1)–Se(2) [°]

Plane Se(3)–C(3)–C(4)–Se(4)/

plane Se(3)–P(2)–Se(4) [°]

154.7

151.9

154.7

–

[a] Mean deviation from plane.

2,7-Bis(1-methylethyl)-4,5,9,10-bis[1,2-dicarba-closo-dodecaborano-

(12)]-2,7-diphospha-1,3,6,8-tetraselenacyclodecane (19): iPrPCl₂

19 was dissolved in CD₂Cl₂; after 2 d at –30 °C, the solution con-

tained 8 (20%) and 19 (80%). The dimer 19 was dissolved in [D₈]-

(0.080 mL, 0.65 mmol) was added through a microsyringe to a THF, after 2 d at room temp., the solution contained 8 (70%), 8(Se)

solution of 5 (233.6 mg, 0.65 mmol) in [D₈]toluene (0.6 mL) at (15%), and 22 (15%) as determined by ³¹P NMR spectroscopy.

room temp. The progress of the reaction was monitored by ³¹P

and ²⁹Si NMR spectroscopy. After 1 h at room temp., the mixture 19: ¹H{¹¹B} NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 1.34 (dd,

3

contained 8 (ca. 85%) and 19 (15%) together with 8(Se)^[11]and

Me₂SiCl₂. The volatile materials were removed under vacuum (1 h,

8ϫ 10^–3Torr), and the residue was dissolved in [D₈]toluene. This

solution was kept for 2 d at room temp., and the formation of a

white powder of 19 was observed. The precipitate was separated by

centrifugation, washed with [D₈]toluene, and dried under vacuum

to give 19 as a light yellow solid; m.p. 145–155 °C (dec.). The dimer

³J

= 16.4 Hz, J₁_H,₁_H= 7.0 Hz, 12 H, CH₃), 2.14 [br. s, 2 H,

³¹P,¹H

HB for δ(¹¹B) = –9.3 ppm], 2.21 [br. s, 2 H, HB for δ(¹¹B) =

–9.3 ppm], 2.25 [br. s, 2 H, HB for δ(¹¹B) = –7.4 ppm], 2.44 (dsept,

3

²J

= 12.1 Hz, J₁_H,₁_H= 7.0 Hz, 2 H, PCH), 2.45 [br. s, 4 H,

³¹P,¹H

HB for δ(¹¹B) = –2.3 ppm], 2.57 [br. s, 4 H, HB for δ(¹¹B) =

–9.3 ppm], 2.68 [br. s, 4 H, HB for δ(¹¹B) = –6.3 ppm], 2.99 [br. s,

2 H, HB for δ(¹¹B) = –9.3 ppm] ppm. ¹¹B{¹H} NMR (160.5 MHz,

Eur. J. Inorg. Chem. 2014, 1929–1948

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FULL PAPER

[D₈]toluene, 25 °C): δ = –9.3 (10 B), 7.4 (2 B), –6.3 (4 B), –2.3 (4

B) ppm. EI-MS (70 eV): m/z (%) = 705 (2) [M – C₃H₇]⁺, 374 (20)

[M/2]⁺, 358 (5) [M/2 – CH₄]⁺, 331 (20) [M/2 – C₃H₇]⁺, 43 (100).

for two months, after which transparent yellow crystals of 9(Se)

[m.p. 140–150 °C (dec.)] could be collected. The principle structure

of 9(Se) was confirmed by X-ray analysis, although severe disorder

in the region of the selenium atoms prevented an exact determi-

nation of a meaningful data set. The solution in [D₈]toluene con-

tained 9, 9(Se), 23, bis(diselane) 24,^[21]and several unidentified

products (from ³¹P and ⁷⁷Se NMR spectroscopy).

22: ¹H NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 4.43 (s, 1 H,

C_carbH), 6.57 (d, ¹J₃₁_P,₁_H= 477.3 Hz, 1 H, PH) ppm. ¹H{³¹P} NMR

(500.13 MHz, CD₂Cl₂, 25 °C): δ = 4.43 (s, 1 H, C_carbH), 6.57 (s, 1

H, PH).

20: ¹H{¹¹B} NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 1.22 [m, 2

H, C(4)H^afrom PCy], 1.35 [m, 8 H, C(2)H^aand C(3)H^afrom PCy],

1.71 [m, 2 H, C(4)H^bfrom PCy], 1.87 [m, 4 H, C(3)H^bfrom PCy],

2.13 [m, 6 H, C(2)H^band PC(1)H from Cy], 2.21 [br. s, 2 H, HB

for δ(¹¹B) = –9.0 ppm], 2.25 [br. s, 2 H, HB for δ(¹¹B) = –7.3 ppm],

2.47 [br. s, 4 H, HB for δ(¹¹B) = –2.4 ppm], 2.56 [br. s, 6 H, HB for

δ(¹¹B) = –9.0 ppm], 2.70 [br. s, 4 H, HB for δ(¹¹B) = –6.5,

–7.3 ppm], 2.99 [br. s, 2 H, HB for δ(¹¹B) = –9.0 ppm] ppm.

¹¹B{¹H} NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –9.0 (10 B), –7.3

(4 B), –6.6 (2 B), –2.4 (4 B) ppm.

2-Cyclohexyl-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2-disel-

enaphospholane (9): CyPCl₂(0.032 mL, 0.21 mmol) was added

through a microsyringe to a solution of 5 (75.5 mg, 0.211 mmol) in

CD₂Cl₂(0.6 mL) at room temp. The progress of the reaction was

monitored by ³¹P and ²⁹Si NMR spectroscopy. After 1 h at room

temp., the mixture contained 9 together with Me₂SiCl₂. The volatile

materials were removed under vacuum (3 h, 8ϫ 10^–3Torr) to give

1

9 as a white solid. H{¹¹B} NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ

3

³¹P,¹H

= 1.07 [dm, J

= 8.3 Hz, 2 H, C(2)H^a], 1.22 [m, 1 H, C(4)H^a],

1.37 [m, 2 H, C(3)H^a], 1.71 [m, 1 H, C(4)H^b], 1.87 [m, 2 H, C(3)

H^b], 1.94 [m, 2 H, C(2)H^b], 2.28 [br. s, 2 H, HB for δ(¹¹B) =

–6.5 ppm], 2.38 [br. s, 1 H, HB for δ(¹¹B) = –6.5 ppm], 2.40 [br. s,

1 H, HB for δ(¹¹B) = –3.8 ppm], 2.43 [br. s, 2 H, HB for δ(¹¹B) =

–10.7 ppm], 2.57 [br. s, 2 H, HB for δ(¹¹B) = –8.6 ppm], 2.73 [dtt,

9(Se): ¹H{¹¹B} NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.82

[m, 1 H, C(4)H^a], 0.90 [m, 2 H, C(3)H^a], 1.31 [m, 3 H, C(2)H^aand

C(4)H^b], 1.49 [m, 2 H, C(3)H^b], 1.64 [m, 2 H, C(2)H^b], 2.60 [m,

³J₁_H,₁_H= 11.9 Hz, 1 H, PC(1)H], 2.61 [br. s, 4 H, HB for δ(¹¹B)

= –9.0^tp^ranp^sm], 2.75 [br. s, 3 H, HB for δ(¹¹B) = –6.4, –4.2 ppm], 2.88

[br. s, 1 H, HB for δ(¹¹B) = –5.3 ppm], 3.00 [br. s, 1 H, HB for

δ(¹¹B) = –0.6 ppm], 3.50 [br. s, 1 H, HB for δ(¹¹B) = –4.2 ppm]

ppm. ¹¹B{¹H} NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –9.0 (4

²J

= 3.5 Hz, ³J

= 12.2 Hz, ³J

³¹P,¹H

¹H,¹H_trans

¹H,¹H_cis

= 3.6 Hz, 1 H,

PC(1)H], 2.78 [br. s, 1 H, HB for δ(¹¹B) = –8.0 ppm], 3.01 [br. s, 1

H, HB for δ(¹¹B) = 0.2 ppm] ppm. ¹¹B{¹H} NMR (160.5 MHz,

CD₂Cl₂, 25 °C): δ = –10.7 (2 B), –8.6 (2 B), –8.0 (1 B), –6.5 (3 B),

–3.8 (1 B), 0.2 (1 B) ppm. ¹¹B NMR (160.5 MHz, CD₂Cl₂, 25 °C):

B), –6.4 (1 B), –5.3 (1 B), –4.2 (3 B), –0.6 (1 B) ppm. ¹¹B NMR

1

¹¹B,¹H

(160.5 MHz, [D₈]toluene, 25 °C): δ = –9.0 (d, J

= 180 Hz, 4

¹¹B,¹H

= 168 Hz, 2

δ = –10.7 (d, J

= 165 Hz, 2 B), –8.6 (d, J

1

¹¹B,¹H

= 155 Hz, 1 B), –5.3 (d, 1 B), –4.2 (d, J

B), –6.4 (d, J

¹¹B,¹H

= 153 Hz, 3 B), –3.8 (d, J

B), –8.0 (d, 1 B), –6.5 (d, J

= 157 Hz, 3 B), –0.6 (d, ¹J

= 142 Hz, 1 B) ppm. EI-MS

= 148 Hz, 1 B), 0.2 (d, ¹J₁₁_B,₁_H= 176 Hz, 1 B) ppm. ¹H{¹¹B} NMR

¹¹B,¹H

(70 eV): m/z (%) = 493 (5) [M]⁺, 414 (4) [M – Se]⁺, 379 (2), 331

3

³¹P,¹H

(500.13 MHz, [D₈]toluene, 25 °C): δ = 0.59 [dm, J

= 8.2 Hz,

(12) [M – Se – C₆H₁₁]⁺, 83 (100) [C₆H₁₁].

2 H, C(2)H^a], 0.86 [m, 1 H, C(4)H^a], 0.92 [m, 2 H, C(3)H^a], 1.37

[m, 1 H, C(4)H^b], 1.47 [m, 2 H, C(3)H^b], 1.56 [m, 2 H, C(2)H^b],

1

23: H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 4.23 (s, 1 H,

2

3

³¹P,¹H

2.44 [dtt, J

= 2.9 Hz, J₁_H,₁_H

= 12.3, J₁_H,₁_H= 3.8 Hz, 1

trans cis

C

_carbH), 5.79 (d, ¹J₃₁_P,₁_H= 476.5 Hz, 1 H, PH) ppm. ¹H{³¹P} NMR

H, PC(1)H], 2.59 [br. s, 2 H, HB for δ(¹¹B) = –10.5 ppm], 2.73 [br.

s, 5 H, HB for δ(¹¹B) = –6.0, –8.4 ppm], 2.77 [br. s, 2 H, HB for

δ(¹¹B) = –3.3, –7.8 ppm], 3.14 [br. s, 1 H, HB for δ(¹¹B) = 0.2 ppm]

ppm. ¹¹B{¹H} NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –10.5 (2

(500.13 MHz, [D₈]toluene, 25 °C): δ = 4.23 (s, 1 H, C_carbH), 5.79

(s, 1 H, PH).

2-(1,1-Dimethylethyl)-4,5-[1,2-dicarba-closo-dodecaborano(12)]-

1,3,2-diselenaphospholane (10): A solution of 5 (92 mg, 0.257 mmol)

in [D₈]toluene (0.4 mL) was cooled to –30 °C, and a solution of

tBuPCl₂(40.8 mg, 0.257 mmol) in [D₈]toluene (0.2 mL) was added.

The progress of the reaction was monitored by ³¹P and ²⁹Si NMR

spectroscopy. After 2 h at room temp., the mixture contained 10

(ca. 80 %) and a stereoisomeric mixture of oligomers (20%) to-

gether with Me₂SiCl₂. The volatile materials were removed under

vacuum (2 h, 8ϫ10^–3Torr) to give a white solid. One part of the

remaining solid was dissolved in [D₈]THF. After 2 h at room temp.,

the mixture contained 10 (ca. 65%), 21 (30%), and 21Ј (possibly a

trimer, 5%). After 1 d at room temp., the mixture contained 10

(5%), 21 (90%), and 10(Se) (5%; Figure 5, A–C). A second part of

the remaining solid was dissolved in [D₈]toluene, and the precipi-

tate was separated by centrifugation and redissolved in [D₈]toluene;

the mixture contained 21 (70%) and 21Ј (possibly a trimer, 30%)

as determined by ³¹P NMR spectroscopy. After 20 h at room temp.,

the mixture contained 21 (90%), 21Ј (10%), and bis(diselane) 24

(from ³¹P and ⁷⁷Se NMR spectroscopy; Figure 5, D–F).

B), –8.4 (2 B), –7.8 (1 B), –6.0 (3 B), –3.3 (1 B), 0.2 (1 B) ppm.

1

¹¹B NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –10.5 (d, J

=

¹¹B,¹H

1

¹¹B,¹H

166 Hz, 2 B), –8.4 (d, J

= 164 Hz, 2 B), –7.8 (d, 1 B), –6.0

1

¹¹B,¹H

= 147 Hz, 1 B), 0.2 (d,

(d, J

= 150 Hz, 3 B), –3.3 (d, J

¹J

= 180 Hz, 1 B) ppm. EI-MS (70 eV): m/z (%) = 415 (12)

¹¹B,¹H

[M]⁺, 332 (5) [M – C₆H₁₁]⁺, 83 (100).

2,7-Di(cyclohexyl)-4,5,9,10-bis[1,2-dicarba-closo-dodecaborano-

(12)]-2,7-diphospha-1,3,6,8-tetraselenacyclodecane (20): A solution

of 5 (100.9 mg, 0.28 mmol) in [D₈]toluene (0.6 mL) was cooled to

–30 °C, and CyPCl₂(0.043 mL, 0.28 mmol) was added through a

microsyringe. The progress of the reaction was monitored by ³¹P

and ²⁹Si NMR spectroscopy. After 30 min at room temp., the mix-

ture contained 9 together with Me₂SiCl₂. After 24 h at room temp.,

the mixture contained 9 (ca. 85%), 20 (10%), and 9(Se) (5%) to-

gether with Me₂SiCl₂. The volatile materials were removed under

vacuum (1 h, 8ϫ 10^–3Torr), and the residue was dissolved in [D₈]-

toluene. This solution in [D₈]toluene was kept for 1 week at –30 °C,

and the formation of 20 as a fairly insoluble white powder was

observed. The precipitate was separated by centrifugation, washed

with [D₈]toluene, and dried under vacuum to give 20 as a light

yellowish solid; m.p. 165–175 °C (dec.). The dimer 20 was dissolved

in [D₈]THF; after 1 h at room temp., the solution contained 9

(75%), 20 (20%), and 9(Se) (5%), and after 30 min at 50 °C, the

mixture contained 9 (80%), 9(Se) (15%), and 23 (5%; Figure 4).

The residual solution in [D₈]toluene was left at room temperature

10: ¹H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.81 (d, ³J

³¹P,¹H

= 13.2 Hz, 9 H, CH₃) ppm.

21: ¹H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.98 (d, ³J

³¹P,¹H

= 15.2 Hz, 18 H, CH₃) ppm.

21Ј: ¹H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 1.07 (d,

³J

= 15.2 Hz, 27 H, CH₃) ppm.

³¹P,¹H

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The solution containing 10 (50%), 21 (45%), and 10(Se) (5%) in

[D₈]toluene was added to an excess of dry degassed elemental selen-

ium. The progress of the reaction was monitored by ³¹P NMR spec-

troscopy. After 24 h at 60 °C, the solution contained 21 (5 %),

10(Se) (90%), and several unidentified side products.

2-[3,5-Dimethylphenylmethyl]-2-selenide-4,5-[1,2-dicarba-closo-

dodecaborano(12)]-1,3,2-diselenaphospholane [11(Se)] and 3-[3,5-Di-

methylphenylmethyl]-3-selenide-6,7-[1,2-dicarba-closo-dodecabor-

ano(12)]-1,2,4,5-tetraselena-3-phosphacycloheptane (25): A solution

of 11 (0.30 mmol) in CD₂Cl₂(1.0 mL) was added to an excess of

dry degassed elemental selenium (80 mg, 1.01 mmol). After 48 h at

50 °C, the mixture contained 11(Se) (ca. 25%) and 25 (ca. 75%;

from ³¹P and ⁷⁷Se NMR spectroscopy). The excess selenium was

separated by centrifugation, and the volatile materials were re-

moved under vacuum (1 h, 8ϫ 10^–3Torr). The residue was washed

with [D₈]toluene and dried under vacuum to give 25 as a yellow-

green solid.

1

10(Se): H{¹¹B} NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.92

3

(d, J

= 24.3 Hz, 9 H, CH₃), 2.19 [br. s, 1 H, HB for δ(¹¹B) =

³¹P,¹H

–11.7 ppm], 2.51 [br. s, 2 H, HB for δ(¹¹B) = –9.5 ppm], 2.74 [br. s,

5 H, HB for δ(¹¹B) = –8.1, –5.7, –4.6 ppm], 2.84 [br. s, 1 H, HB for

δ(¹¹B) = –5.7 ppm], 3.73 [br. s, 1 H, HB for δ(¹¹B) = –7.5 ppm]

ppm. ¹¹B{¹H} NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –11.7 (1

B), –9.5 (2 B), –8.1 (2 B), –7.5 (1 B), –5.7 (2 B), –4.6 (2 B) ppm.

1

11(Se): H NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 2.33 (m, 6 H,

2

4

2,7-Bis(1,1-dimethylethyl)-4,5,9,10-bis[1,2-dicarba-closo-dodecabor-

ano(12)]-2,7-diphospha-1,3,6,8-tetraselenaacyclodecane (21): De-

gassed 5 (40 mg, 0.111 mmol) was added to tBuPCl₂(17.7 mg,

0.111 mmol). The mixture was cooled to –30 °C, and [D₈]toluene

(1 mL) was added. After 1 d at room temp., the volatile materials

were removed in vacuo. The resulting mixture thus obtained con-

tained 10 (ca. 50%) and a stereoisomeric mixture of 21 (ca. 50%

by ³¹P NMR spectroscopy). The remaining white solid was washed

with [D₈]toluene, the insoluble materials were dissolved in CD₂Cl₂

and centrifuged, and the liquid phase was collected. Transparent

crystals of 21 for X-ray analysis were grown from CD₂Cl₂solution

after 1 week at –30 °C; m.p. 215–225 °C (dec.). ¹H{¹¹B} NMR

³¹P,¹H

CH₃), 4.61 (d, J

= 9.5 Hz, 2 H, PCH₂), 7.02 (dm, J₁_H,₁_H

=

4

4.3 Hz, 2 H, Ph), 7.05 (dm, J₁_H,₁_H= 4.3 Hz, 1 H, Ph) ppm.

25: ¹H{¹¹B} NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 2.02 [br. s, 1

H, HB for δ(¹¹B) = –10.9 ppm], 2.27 [br. s, 1 H, HB for δ(¹¹B) =

–8.2 ppm], 2.34 (m, 6 H, CH₃), 2.43 [br. s, 1 H, HB for δ(¹¹B) =

–10.9 ppm], 2.59 [br. s, 4 H, HB for δ(¹¹B) = –8.2, –1.3 ppm], 2.79

[br. s, 2 H, HB for δ(¹¹B) = –7.1 ppm], 3.20 [br. s, 1 H, HB for

δ(¹¹B) = –10.9 ppm], 4.59 (d, ²J

= 9.5 Hz, 2 H, PCH₂), 6.96

³¹P,¹H

(d, ⁴J₁_H,₁_H= 3.8 Hz, 2 H, Ph), 7.03 (dm, ⁴J₁_H,₁_H= 3.8 Hz, 1 H, Ph)

ppm. ¹¹B{¹H} NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –10.9 (3 B),

–8.2 (3 B), –7.1 (2 B), –1.3 (2 B) ppm. ¹¹B NMR (160.5 MHz,

CD₂Cl₂, 25 °C): δ = –10.9 (d, ¹J

= 158 Hz, 3 B), –8.2 (d,

¹¹B,¹H

(500.13 MHz, CD₂Cl₂, 25 °C): δ = 1.37 (d, ³J

= 15.5 Hz, 18

³¹P,¹H

¹J

= 168 Hz, 3 B), –7.1 (d, 2 B), –1.3 (d, J

1

¹¹B,¹H

= 139 Hz, 2

H, CH₃), 2.17 [br. s, 2 H, HB for δ(¹¹B) = –8.8 ppm], 2.21 [br. s, 2

H, HB for δ(¹¹B) = –9.6 ppm], 2.27 [br. s, 2 H, HB for δ(¹¹B) =

–7.2 ppm], 2.47 [br. s, 4 H, HB for δ(¹¹B) = –2.5 ppm], 2.61 [br. s,

4 H, HB for δ(¹¹B) = –9.6 ppm], 2.71 [br. s, 4 H, HB for δ(¹¹B) =

–6.3 ppm], 2.95 [br. s, 2 H, HB for δ(¹¹B) = –9.6 ppm] ppm.

¹¹B{¹H} NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –9.6 (8 B), –8.8

(2 B), –7.2 (2 B), –6.3 (4 B), –2.5 (4 B) ppm. EI-MS (70 eV): m/z

(%) = 776 (1) [M]⁺, 719 (2) [M – C₄H₉] ⁺, 389 (6) [M/2]⁺, 232 (4)

[M/2 – C₄H₉]⁺, 57 (100) [C₄H₉]⁺.

B) ppm.

2-[3,5-Dimethylphenylmethyl]-2-thio-4,5-[1,2-dicarba-closo-dodeca-

borano(12)]-1,3,2-diselenaphospholane [11(S)]: A solution of 11

(0.15 mmol) in CD₂Cl₂(0.6 mL) was added to an excess of dry and

degassed elemental sulfur (ca. 8 mg). The progress of the reaction

was monitored by ³¹P NMR spectroscopy. The mixture was stirred

for 10 d at room temp. and then centrifuged from the unreacted

sulfur. The reaction solution contained 11(S) (ca. 90%) together

with bis(diselane) 24^[21]and several unidentified side products

(from ¹³C, ³¹P, and ⁷⁷Se NMR spectroscopy).

2-[3,5-Dimethylphenylmethyl]-4,5-[1,2-dicarba-closo-dodecaborano-

(12)]-1,3,2-diselenaphospholane (11): A solution of 5 (1144 mg,

0.319 mmol) in CD₂Cl₂(0.6 mL) was added through a microsy-

ringe to (3,5-Me_2–C₆H₃)CH₂PBr₂(99 mg, 0.319 mmol) at room

temp. The progress of the reaction was monitored by ³¹P and ²⁹Si

NMR spectroscopy. After 1 h at room temp., the mixture contained

11 together with Me₂SiBr₂. The volatile materials were removed

under vacuum (3 h, 8ϫ 10^–3Torr). The residue was washed with

[D₈]toluene and dried in a vacuum to give 11 as a white solid.

Transparent crystals of 11 for X-ray analysis were grown from

CD₂Cl₂solution after 1 week at room temp.; m.p. 140–150 °C

(dec.). The monomer 11 was dissolved in [D₈]THF, and after 2 d

at room temp., the solution contained 11 (85%), 11(Se) (5%), and

several unidentified products (from ³¹P NMR spectroscopy).

¹H{¹¹B} NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 2.30 (s, 6 H,

CH₃), 2.45 [br. s, 1 H, HB for δ(¹¹B) = –3.8 ppm], 2.49 [br. s, 5 H,

HB for δ(¹¹B) = –6.1, –6.5, –10.4 ppm], 2.67 [br. s, 2 H, HB for

δ(¹¹B) = –8.6 ppm], 3.05 [br. s, 1 H, HB for δ(¹¹B) = –0.2 ppm],

1

11(S): H NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 2.32 (m, 6 H,

CH₃), 2.41 [br. s, 1 H, HB for δ(¹¹B) = –6.8 ppm], 2.45 [br. s, 1 H,

HB for δ(¹¹B) = –5.8 ppm], 2.56 [br. s, 5 H, HB for δ(¹¹B) = –0.8,

–9.0 ppm], 2.70 [br. s, 1 H, HB for δ(¹¹B) = –6.8 ppm], 2.96 [br. s,

1 H, HB for δ(¹¹B) = –4.2 ppm], 3.33 [br. s, 1 H, HB for δ(¹¹B) =

–4.2 ppm], 4.33 (d, ²J₃₁_P,₁_H= 10.2 Hz, 2 H, PCH₂), 7.00 (dm, ⁴J₁_H,₁_H

4

= 4.2 Hz, 2 H, Ph), 7.03 (dm, J₁_H,₁_H= 4.2 Hz, 1 H, Ph) ppm.

¹¹B{¹H} NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –9.0 (4 B), –6.8

(2 B), –5.8 (1 B), –4.2 (2 B), –0.8 (1 B) ppm.

2-Phenyl-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2-diselena-

phospholane (12): A solution of 5 (53 mg, 0.148 mmol) in [D₈]tolu-

ene (0.6 mL) was cooled to –30 °C, and PhPCl₂(0.020 mL,

0.148 mmol) was added through a microsyringe. The progress of

the reaction was monitored by ³¹P and ²⁹Si NMR spectroscopy.

After 1 h at room temp., the mixture contained 12 together with

Me₂SiCl₂. The volatile materials were removed under vacuum (1 h,

8ϫ 10^–3Torr) to give 12 (purity ca. 95%) as a white oil. The mono-

mer 12 can be stored for prolonged periods of time in [D₈]toluene

or CD₂Cl₂at –30 °C. After 12 h at 50 °C in [D₈]toluene, the solu-

tion contained 12 (ca. 50%), 12(Se)^[8,11](ca. 10%), and several un-

identified products (from ³¹P NMR spectroscopy).

3.15 [br. s, 1 H, HB for δ(¹¹B) = –7.6 ppm], 3.85 [d, ²J

=

³¹P,¹H

3

⁷⁷Se,¹H

10.7 Hz, J

= 4.9 Hz, 2 H, PCH₂), 6.83 (s, 2H, Ph), 6.93 (s, 1

H, Ph) ppm. ¹¹B{¹H} NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ =

–10.4 (2 B), –8.6 (2 B), –7.6 (1 B), –6.5 (2 B), –6.1 (1 B), –3.8 (1

B), –0.2 (1 B) ppm. ¹¹B NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ =

1

¹¹B,¹H

= 171 Hz, 2 B),

–10.4 (d, J

= 160 Hz, 2 B), –8.6 (d, J

–7.6 (d, 1 B), –6.5 (d, ¹J

= 148 Hz, 2 B), –6.1 (d, ¹J

= 152 Hz, 1 B), –0.2 (d, ¹J

=

12: H{¹¹B} NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 2.50 [br.

1

¹¹B,¹H

153 Hz, 1 B), –3.8 (d, ¹J

s, 1 H, HB for δ(¹¹B) = –6.7 ppm], 2.58 [br. s, 3 H, HB for δ(¹¹B)

= –9.9, –11.0 ppm], 2.61 [br. s, 2 H, HB for δ(¹¹B) = –8.3 ppm],

2.72 [br. s, 2 H, HB for δ(¹¹B) = –5.8 ppm], 2.80 [br. s, 1 H, HB for

¹¹B,¹H

180 Hz, 1 B) ppm. EI-MS (70 eV): m/z (%) = 451 (20) [M]⁺, 332

(10) [M – C₉H₁₁]⁺, 119 (100) [C₉H₁₁]⁺.

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δ(¹¹B) = –3.3 ppm], 3.16 [br. s, 1 H, HB for δ(¹¹B) = 0.0 ppm], 6.90

(m, 3 H, Ph), 7.22 (m, 2 H, Ph) ppm. ¹¹B{¹H} NMR (160.5 MHz,

[D₈]toluene, 25 °C): δ = –11.0 (2 B), –9.9 (1 B), –8.3 (2 B), –6.7 (1

diselenaphospholane (15): A solution of 5 (99.7 mg, 0.28 mmol) in

[D₈]toluene (0.6 mL) was cooled to 0 °C, and Cl₂PCH₂PCl₂

(0.019 mL, 0.14 mmol) was added through a microsyringe. The

progress of the reaction was monitored by ³¹P and ²⁹Si NMR spec-

troscopy. After 2 h at room temp., the mixture contained 15 to-

B), –5.8 (2 B), –3.3 (1 B), 0.0 (1 B) ppm. ¹¹B NMR (160.5 MHz,

1

¹¹B,¹H

[D₈]toluene, 25 °C): δ = –11.0 (d, J

= 166 Hz, 2 B), –9.9 (d,

1

¹¹B,¹H

1 B), –8.3 (d, J

¹¹B,¹H

= 148 Hz, 1 gether with Me₂SiCl₂. A white powder of 15 formed and had rather

= 167 Hz, 2 B), –6.7 (d, J

B), –5.8 (d, ¹J₁₁_B,₁_H= 151 Hz, 2 B), –3.3 (d, ¹J₁₁_B,₁_H= 151 Hz, 1 B),

low solubility in [D₈]toluene. The precipitate was separated by cen-

trifugation, washed with [D₈]toluene, and dried under vacuum to

give 15 as a light yellowish solid. Compound 15 can be stored for

prolonged periods of time in [D₈]toluene at room temp., survives

in toluene solution at 100 °C, and decomposes slowly in [D₈]THF

under Ar at –30 °C into several unidentified products. Transparent

crystals of 15 for X-ray analysis were grown from a hot saturated

[D₈]toluene solution after 1 d at room temp.; m.p. 220–235 °C

(dec.).

15: ¹H{¹¹B} NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 2.49 [br. s, 4

H, HB for δ(¹¹B) = –6.0 ppm], 2.58 [br. s, 8 H, HB for δ(¹¹B) =

–3.5, –6.0, –10.5 ppm], 2.73 [br. s, 4 H, HB for δ(¹¹B) = –8.5 ppm],

3.03 [br. s, 2 H, HB for δ(¹¹B) = –8.5 ppm], 3.14 [br. s, 2 H, HB for

1

¹¹B,¹H

0.0 (d, J

= 180 Hz, 1 B) ppm.

2-Ethoxy-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2-diselena-

phospholane (13): A solution of 5 (51.9 mg, 0.145 mmol) in [D₈]-

toluene (0.6 mL) was cooled to –30 °C, and EtOPCl₂(0.016 mL,

0.14 mmol) was added through a microsyringe. The progress of the

reaction was monitored by ³¹P and ²⁹Si NMR spectroscopy. After

2 h at room temp., the mixture contained 13 together with Me₂-

SiCl₂. The volatile materials were removed under vacuum (1 h, 8ϫ

10^–3Torr) to give 13 (ca. 90%) together with 13(Se) (ca. 10%).^[11]

The monomer 13 decomposes slowly in [D₈]toluene or in CD₂Cl₂

under Ar at –30 °C to form 13(Se) and several unidentified prod-

ucts (from ³¹P NMR).

2

3

δ(¹¹B) = –0.3 ppm], 3.92 (t, J

= 13.9 Hz, J

³¹P,¹H

⁷⁷Se,¹H

= 4.5 Hz, 2

13: ¹H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.80 (t, ³J₁_H,₁_H

H, CH₂) ppm. ¹¹B{¹H} NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ =

–10.5 (4 B), –8.5 (6 B), –6.0 (6 B), –3.5 (2 B), –0.3 (2 B) ppm. ¹¹B

NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –10.5 (d, ¹J₁₁_B,₁_H= 156 Hz,

3

³¹P,¹H

= 7.0 Hz, 3 H, CH₃), 3.21 (dq, J

= 9.8 Hz, J₁_H,₁_H= 7.0 Hz,

2 H, POCH₂) ppm. ¹¹B{¹H} NMR (160.5 MHz, [D₈]toluene,

25 °C): δ = –10.0 (2 B), –8.4 (2 B), –6.3 (3 B), –5.6 (1 B), –4.1 (1

B), –1.2 (1 B) ppm. ¹¹B NMR (160.5 MHz, [D₈]toluene, 25 °C): δ

1

¹¹B,¹H

= 151 Hz, 6

4 B), –8.5 (d, J

= 156 Hz, 6 B), –6.0 (d, J

1

¹¹B,¹H

B), –3.5 (d, J

¹¹B,¹H

= 157 Hz, 2 B)

= 158 Hz, 2 B), –0.3 (d, J

= –10.0 (d, ¹J

–6.3 (d, ¹J

= 167 Hz, 2 B), –8.4 (d, ¹J

¹¹B,¹H

= 170 Hz, 2 B),

ppm. EI-MS (70 eV): m/z (%) = 677 (45) [M]⁺.

= 145 Hz, 3 B), –5.6 (d, 1 B), –4.1 (d, ¹J

¹¹B,¹H

=

148 Hz, 1 B), –1.2 (d, ¹J

= 180 Hz, 1 B) ppm. ¹H NMR

2-Dichlorophosphinomethyl-4,5-[1,2-dicarba-closo-dodecaborano-

(12)]-1,3,2-diselenaphospholane (17): A solution of 5 (59.9 mg,

0.167 mmol) in [D₈]toluene (0.6 mL) was cooled to –30 °C, and

Cl₂PCH₂PCl₂(0.023 mL, 0.169 mmol) was added through a micro-

syringe. The progress of the reaction was monitored by ³¹P and ²⁹Si

NMR spectroscopy. After 1 h at room temp., the mixture contained

17 (60%) and 15 (40%) together with Me₂SiCl₂and Cl₂PCH₂PCl₂.

The formation of a white powder of 15 was observed. The precipi-

tate of 15 was separated by centrifugation; the reaction solution

contained 17 (80 %) and 15 (20 %) together with Me₂SiCl₂and

¹¹B,¹H

3

(500.13 MHz, CD₂Cl₂, 25 °C): δ = 1.37 (t, 3 H, CH₃, J₁_H,₁_H

=

3

7.0 Hz), 3.98 (dq, ³J

= 9.9 Hz, J₁_H,₁_H= 7.0 Hz, 2 H, POCH₂)

³¹P,¹H

ppm. ¹¹B{¹H} NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –10.3 (2 B),

–8.6 (2 B), –6.8 (3 B), –6.1 (1 B), –4.5 (1 B), –1.2 (1 B) ppm. ¹¹B

NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –10.3 (d, ¹J₁₁_B,₁_H= 166 Hz,

1

¹¹B,¹H

= 150 Hz, 3

¹¹B,¹H

= 154 Hz, 1 B), –1.2 (d, J

2 B), –8.6 (d, J

= 172 Hz, 2 B), –6.3 (d, J

1

¹¹B,¹H

B), –6.1 (d, 1 B), –4.5 (d, J

= 189 Hz, 1 B) ppm.

13(Se): ¹H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.87 (t,

1

Cl₂PCH₂PCl₂(from ³¹P and H NMR spectroscopy).

3

³J₁_H,₁_H= 7.1 Hz, 3 H, CH₃), 3.71 (dq, J

= 12.2 Hz, J₁_H,₁_H=

³¹P,¹H

1

17: H{¹¹B} NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 2.51 [br.

7.1 Hz, 2 H, POCH₂) ppm. ¹H NMR (500.1 MHz, CD₂Cl₂, 25 °C):

δ = 1.45 (t, ³J₁_H,₁_H= 7.1 Hz, 3 H, CH₃), 4.32 (dq, ³J₃₁_P,₁_H= 11.8 Hz,

³J₁_H,₁_H= 7.1 Hz, 2 H, POCH₂) ppm.

2

s, 1 H, HB for δ(¹¹B) = –10.6 ppm], 2.54 (dd, J³¹

P

,¹H

= 20.0 Hz,

PCl

²J³¹

= 9.3 Hz, 2 H, CH₂), 2.58 [br. s, 1 H, HB for δ(¹¹B) =

P_PSe,¹H

–8.0 ppm], 2.68 [br. s, 2 H, HB for δ(¹¹B) = –8.5 ppm], 2.77 [br. s,

5 H, HB for δ(¹¹B) = –5.8, –3.3 ppm], 2.98 [br. s, 1 H, HB for δ(¹¹B)

= –0.6 ppm] ppm. ¹¹B{¹H} NMR (160.5 MHz, [D₈]toluene, 25 °C):

δ = –10.6 (1 B), –8.5 (2 B), –8.0 (1 B), –5.8 (4 B), –3.3 (1 B), –0.6

(1 B) ppm. ¹¹B NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –10.6

2-Diethylamino-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2-di-

selenaphospholane (14): A solution of 5 (78.6 mg, 0.22 mmol) in [D₈]-

toluene (0.6 mL) was cooled to –30 °C, and Et₂NPCl₂(0.032 mL,

0.22 mmol) was added through a microsyringe. The progress of the

reaction was monitored by ³¹P and ²⁹Si NMR spectroscopy. After

2 h at –10 °C, the mixture contained 14 together with Me₂SiCl₂.

The volatile materials were removed under vacuum (1 h, 8 ϫ

10^–3Torr) to give 14 (90%) together with several unidentified prod-

ucts. The monomer 14 decomposes in [D₈]toluene under Ar at

–30 °C to form 14(Se), bis(diselane) 24, and several unidentified

products (from ³¹P and ⁷⁷Se NMR spectroscopy).

1

¹¹B,¹H

= 158 Hz, 2 B), –8.0 (1

(d, J

= 168 Hz, 1 B), –8.5 (d, J

B), –5.8 (d, ¹J₁₁_B,₁_H= 150 Hz, 4 B), –3.3 (d, ¹J₁₁_B,₁_H= 152 Hz, 1 B),

–0.6 (d, J

1

¹¹B,¹H

= 175 Hz, 1 B) ppm.

15: ¹H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 2.87 (t, ²J

³¹P,¹H

= 15.3 Hz, 2 H, CH₂) ppm.

2-(2-{4,5-[1,2-Dicarba-closo-dodecaborano(12)]-1,3,2-diselena-

phospholan-2-yl}ethyl)-4,5-[1,2-dicarba-closo-dodecaborano(12)]-

1,3,2-diselenaphospholane (16): A solution of 5 (117 mg, 0.33 mmol)

i n [ D ₈] t o l u e n e ( 0 . 6 m L ) w a s c o o l e d t o – 3 0 ° C , a n d

Cl₂PCH₂CH₂PCl₂(0.025 mL, 0.165 mmol) was added through a

microsyringe. The progress of the reaction was monitored by ³¹P

and ²⁹Si NMR spectroscopy. After 1 h at room temp., the mixture

contained 16 together with Me₂SiCl₂. A white powder of 16 formed

and had rather low solubility in [D₈]toluene. The precipitate was

separated by centrifugation, washed with [D₈]toluene, and dried

under vacuum to give 16 as a white solid; m.p. 185–195 °C (dec.).

14: ¹H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.62 (t, ³J₁_H,₁_H

3

= 7.1 Hz, 6 H, CH₃), 2.78 (dq, J

= 11.7 Hz, ³J₁_H,₁_H= 7.1 Hz,

³¹P,¹H

4 H, PNCH₂) ppm. ¹¹B{¹H} NMR (160.5 MHz, [D₈]toluene,

25 °C): δ = –9.7 (2 B), –8.2 (2 B), –6.9 (1 B), –4.8 (4 B), –2.2 (1 B)

ppm. ¹¹B NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –9.7 (d,

¹J

= 170 Hz, 2 B), –8.2 (d, ¹J

= 163 Hz, 1 B), –4.8 (d, ¹J

= 180 Hz, 1 B) ppm.

= 170 Hz, 2 B), –6.9 (d,

= 151 Hz, 4 B), –2.2 (d,

¹¹B,¹H

2-{4,5-[1,2-Dicarba-closo-dodecaborano(12)]-1,3,2-diselenaphos-

pholan-2-yl}methyl-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2- Compound 16 can be stored for prolonged periods of time in

Eur. J. Inorg. Chem. 2014, 1929–1948

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FULL PAPER

[D₈]toluene at room temp. and decomposes slowly in toluene at

100 °C.

(20 mL) and centrifuged. The remaining solid was dissolved in

CD₂Cl₂(2 mL) and centrifuged; the liquid phase was separated and

dried under vacuum to give an orange-brown solid of 26a. Com-

pound 26a was only sparingly soluble in toluene.

16: ¹H{¹¹B} NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 1.78

(pseudo-t, |²J₃₁_P,₁_H+ ³J₃₁_P,₁_H| = 22.1 Hz, 4 H, CH₂), 2.56 [br. s, 4 H,

HB for δ(¹¹B) = –10.4 ppm], 2.71 [br. s, 4 H, HB for δ(¹¹B) =

–6.0 ppm], 2.76 [br. s, 10 H, HB for δ(¹¹B) = –3.1, –6.0, –8.5 ppm],

3.07 [br. s, 2 H, HB for δ(¹¹B) = –0.5 ppm] ppm. ¹¹B{¹H} NMR

(160.5 MHz, [D₈]toluene, 25 °C): δ = –10.4 (4 B), –8.5 (6 B), –6.0

(6 B), –3.2 (2 B), –0.5 (2 B) ppm. ¹H{¹¹B} NMR (500.13 MHz,

CD₂Cl₂, 25 °C): δ = 2.35 [br. s, 4 H, HB for δ(¹¹B) = –6.4 ppm],

26a: ¹H{¹¹B} NMR (500.13 MHz, CD₂Cl₂, 25 °C): δ = 1.38 (dd,

3

³J

= 21.2, J₁_H,₁_H= 7.0 Hz, 6 H, CH₃), 2.32 [br. s, 1 H, HB

³¹P,¹H

for δ(¹¹B) = –2.4 ppm], 2.37 [br. s, 3 H, HB for δ(¹¹B) = –4.4,

–9.3 ppm], 2.62 [br. s, 2 H, HB for δ(¹¹B) = –3.9 ppm], 2.71 [br. s,

2 H, HB for δ(¹¹B) = –7.1 ppm], 3.03 [br. s, 1 H, HB for δ(¹¹B) =

–7.1 ppm], 3.19 (dsept, ²J

= 3.8 Hz, J₁_H,₁_H= 7.0 Hz, 1 H,

3

³¹P,¹H

2.49 [br. s, 8 H, HB for δ(¹¹B) = –3.4, –6.4, –10.6 ppm], 2.64 [br. s,

PCH), 3.54 [br. s, 1 H, HB for δ(¹¹B) = 0.5 ppm] ppm. ¹¹B{¹H}

NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –9.3 (2 B), –7.1 (3 B), –4.4

(1 B), –3.9 (2 B), –2.4 (1 B), 0.5 (1 B) ppm. ¹¹B NMR (160.5 MHz,

3

4 H, HB for δ(¹¹B) = –8.6 ppm], 2.68 (pseudo-t, |²J

+ J

³¹P,¹H

|

= 22.2 Hz, 4 H, CH₂), 2.91 [br. s, 2 H, HB for δ(¹¹B) = –8.6 ppm],

3.05 [br. s, 2 H, HB for δ(¹¹B) = 0.1 ppm] ppm. ¹H NMR

(500.13 MHz, CD₂Cl₂, 25 °C): δ = 2.68 (pseudo-t, 4 H, CH₂,

CD₂Cl₂, 25 °C): δ = –9.3 (d, ¹J₁₁_B,₁_H= 158 Hz, 2 B), –7.1 (d, ¹J

¹¹B,¹H

1

¹¹B,¹H

= 160 Hz, 3 B), –4.4 (d, J

= 153 Hz, 1 B), –3.9 (d, J

=

|²J

+

³J₃₁_P,₁_H| = 22.2 Hz, ³J

149 Hz, 2 B), –2.4 (d, ¹J

= 150 Hz, 1 B), 0.5 (d, ¹J

³¹P,¹H

⁷⁷Se,¹H

= 2.1 Hz, 4 H, CH₂) ppm.

¹¹B,¹H

¹¹B{¹H} NMR (160.5 MHz, CD₂Cl₂, 25 °C): δ = –10.6 (4 B), –8.6

1

176 Hz, 1 B) ppm. H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ

(6 B), –6.4 (6 B), –3.4 (2 B), 0.1 (2 B) ppm. ¹¹B NMR (160.5 MHz,

= 0.87 (dd, ³J

= 21.0 Hz, J₁_H,₁_H= 7.1 Hz, 6 H, CH₃), 2.69

3

³¹P,¹H

CD₂Cl₂, 25 °C): δ = –10.6 (d, ¹J

= 166 Hz, 4 B), –8.6 (d,

= 155 Hz, 6 B), –3.4 (d,

= 170 Hz, 2 B) ppm.

(dsept, ²J₃₁_P,₁_H= 3.5 Hz, ³J₁_H,₁_H= 7.1 Hz, 1 H, PCH) ppm. ¹¹B{¹H}

NMR (160.5 MHz, [D₈]toluene, 25 °C): δ = –9.2 (2 B), –7.0 (3 B),

¹¹B,¹H

¹J

= 165 Hz, 6 B), –6.4 (d, ¹J

¹¹B,¹H

¹J

= 150 Hz, 2 B), –0.1 (d, ¹J

¹¹B,¹H

–4.1 (1 B), –3.4 (2 B), –1.9 (1 B), 0.5 (1 B) ppm. ¹¹B NMR

¹¹B,¹H

¹H{¹¹B} NMR (500.13 MHz, [D₈]THF, 25 °C): δ = 2.26 [br. s, 4

H, HB for δ(¹¹B) = –6.7 ppm], 2.41 [br. s, 8 H, HB for δ(¹¹B) =

1

¹¹B,¹H

(160.5 MHz, [D₈]toluene, 25 °C): δ = –9.2 (d, J

= 170 Hz, 2

B), –7.0 (d, ¹J₁₁_B,₁_H= 164 Hz, 3 B), –4.1 (d, ¹J₁₁_B,₁_H= 150 Hz, 1 B),

–4.0, –6.7, –10.3 ppm], 2.64 [br. s, 4 H, HB for δ(¹¹B) = –8.5 ppm],

–3.4 (d, ¹J₁₁_B,₁_H= 150 Hz, 2 B), –1.9 (d, ¹J₁₁_B,₁_H= 155 Hz, 1 B), 0.5

3

2.72 (pseudo-t, |²J

+ J₃₁_P,₁_H| = 20.0 Hz, 4 H, CH₂), 2.96 [br.

1

³¹P,¹H

¹¹B,¹H

(d, J

= 185 Hz, 1 B) ppm.

s, 2 H, HB for δ(¹¹B) = –6.7 ppm], 3.00 [br. s, 2 H, HB for δ(¹¹B)

= –0.2 ppm] ppm. ¹¹B{¹H} NMR (160.5 MHz, [D₈]THF, 25 °C): δ

= –10.3 (4 B), –8.5 (4 B), –6.7 (8 B), –4.0 (2 B), –0.2 (2 B) ppm.

EI-MS (70 eV): m/z (%) = 691 (30) [M]⁺.

2-(1,1-Dimethylethyl)-4,5-[1,2-dicarba-closo-dodecaborano(12)]-

1,3,2-ditelluraphospholane (26b): Freshly prepared 4 (895 mg,

1.84 mmol) was cooled to –40 °C and suspended in toluene

(50 mL). The suspension was cooled to –40 °C, and a solution of

tBuPCl₂(293 mg, 1.84 mmol) in toluene (0.3 mL) was added. The

reaction mixture was stirred for 1.5 h at –40 °C and 1 h at room

temp., the insoluble materials were separated by centrifugation, and

the clear liquid was collected. The volatile materials were removed

under vacuum to give a brown solid (769 mg). The resulting mix-

ture thus obtained contained 26b (ca. 45%), 27b (5%), 28b (40%),

30b (10%), and several unidentified products (from ³¹P and ¹²⁵Te

NMR spectroscopy). This mixture in [D₈]toluene was kept for 1

week at –30 °C, and the formation of an orange solid of 30b was

observed. The precipitates were separated by centrifugation,

washed with [D₈]toluene, and dried in a vacuum to give 30b as a

yellow-orange solid. The remaining insoluble materials from the

initial reaction were washed with toluene (2ϫ10 mL) and centri-

fuged. The remaining powder was dried under vacuum to give an

orange-brown solid of 28b.

2-(2-Dichlorophosphinoethyl)-4,5-[1,2-dicarba-closo-dodecaborano-

(12)]-1,3,2-diselenaphospholane (18): A solution of 5 (67 mg,

0.187 mmol) in [D₈]toluene (0.6 mL) was cooled to 0 °C, and

Cl₂PCH₂CH₂PCl₂(0.028 mL, 0.186 mmol) was added through a

microsyringe. The progress of the reaction was monitored by ³¹P

and ²⁹Si NMR spectroscopy. After 1 h at room temp., the mixture

contained 18 (ca. 50%) and 16 (ca. 50%) together with Me₂SiCl₂

and Cl₂PCH₂CH₂PCl₂. The formation of a white powder of 16

was observed. The precipitate was separated by centrifugation; the

solution contained 18 (60%) and 16 (40%) together with Me₂SiCl₂

1

and Cl₂PCH₂PCl₂(from ³¹P and H NMR spectroscopy).

1

18: H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 1.49 (m, 2 H,

PCH₂), 2.15 (m, 2 H, PCH₂).

Reactions of 4 with RPCl₂: All preparative work as well as handling

of the samples was performed in the dark to shield the samples as

much as possible from light. Thus, the reaction flasks and NMR

sample tubes were wrapped in aluminum foil. All tellurium-con-

taining compounds studied here decompose under Ar as solids, in

solution at room temp., and in the presence of light, accompanied

by the formation of black elemental tellurium.

1

26b: H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 0.95 (d, 9 H,

3

³¹P,¹H

CH₃, J

= 16.2 Hz) ppm.

28b: ¹H{¹¹B} NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 1.01 (d,

3

³¹P,¹H

9 H, CH₃, J

= 14.6 Hz), 2.49, 2.60 [br. s, br. s, 1 H, 1 H, HB

for δ(¹¹B) = –8.5 ppm], 2.66 [br. s, 1 H, HB for δ(¹¹B) = –9.1 ppm],

2.77 [br. s, 1 H, HB for δ(¹¹B) = 0.1 ppm], 2.83 [br. s, 2 H, HB for

δ(¹¹B) = –4.6, –5.0 ppm], 2.89 [br. s, 1 H, HB for δ(¹¹B) =

–6.6 ppm], 3.09 [br. s, 1 H, HB for δ(¹¹B) = –1.5 ppm], 3.31 [br. s,

1 H, HB for δ(¹¹B) = –7.3 ppm], 3.71 [br. s, 1 H, HB for δ(¹¹B) =

–2.1 ppm] ppm. ¹¹B{¹H} NMR (160.5 MHz, [D₈]toluene, 25 °C): δ

= –9.1 (1 B), –8.5 (2 B), –7.3 (1 B), –6.6 (1 B), –5.0 (1 B), –4.6 (1

B), –2.1 (1 B), –1.5 (1 B), 0.1 (1 B) ppm.

2-(1-Methylethyl)-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2-di-

telluraphospholane (26a): Freshly prepared 4 (844 mg, 1.74 mmol)

was cooled to –40 °C and suspended in toluene (50 mL); the sus-

pension was cooled to –40 °C, and iPrPCl₂(0.214 mL, 1.74 mmol)

was injected slowly through a syringe. The reaction mixture was

stirred for 1.5 h at –40 °C and 30 min at 10 °C, the insoluble materi-

als were separated by centrifugation, and the clear liquid was col-

lected. The volatile materials were removed under vacuum to give

a yellow-brown solid (597 mg). The resulting mixture thus obtained

contained 26a (ca. 50%), 27a (15%), 28a (15%), 29a (8–9%), 29aЈ

(1–2%), 30a (10%), together with bis(ditellane) 31^[17]and several

unidentified products (from ³¹P and ¹²⁵Te NMR spectroscopy; Fig-

ure 6). The remaining insoluble materials were washed with toluene

30b: ¹H NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 1.06 (d,

³J

= 15.8 Hz, 18 H, CH₃) ppm.

³¹P,¹H

2-Phenyl-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3-ditellura-2-

phospholane (26c): Freshly prepared 4 (2104 mg, 4.34 mmol) was

cooled to –20 °C and suspended in toluene (60 mL). The suspen-

Eur. J. Inorg. Chem. 2014, 1929–1948

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Table 6. Crystallographic data of the ortho-carborane derivative 11, 15, and 21.

11

15

21^[b]

Formula

Crystal

Dimensions [mm]

Temperature [K]

Crystal system

C₁₁H₂₁B₁₀PSe₂

colorless prism

0.25ϫ0.22ϫ0.16

133(2)

monoclinic

P2₁/n

C₅H₂₂B₂₀P₂Se₄

colorless prism

0.19ϫ0.14ϫ0.12

133(2)

monoclinic

P2₁/n

C₁₂H₄₀B₂₀P₂Se₄·1.4CD₂Cl₂

colorless prism

0.22ϫ0.18ϫ0.15

133(2)

monoclinic

C2/c

Space group

a [pm]

b [pm]

c [pm]

β [°]

1051.2(2)

1132.4(2)

1604.3(3)

99.29(3)

1459.0(3)

848.96(17)

1943.7(4)

92.53(3)

2024.3(4)

1154.0(2)

3203.6(6)

92.74(3)

Z

4

8

Absorption coefficient μ [mm^–1]

Diffractometer

3.998

6.231

4.224

STOE IPDS II; Mo-K_α, λ = 71.073 pm, graphite monochromator

Measuring range (θ) [°]

Reflections collected

Independent reflections [IՆ2σ(I)]

Absorption correction

Max./min. transmission

Refined parameters

wR₂/R₁[IՆ2σ(I)]

Max./min. residual electron density [10^–6epm^–3]

2.17–25.62

24731

1.71–25.64

16272

4057

numerical

0.7541/0.4000

280

0.116/0.044

1.079/–1.452

2.01–25.70

8403

3224

2146

none^[a]

–

none^[a]

–

217

0.081/0.032

1.228/–0.613

386

0.149/0.066

0.750/–0.459

[a] Absorption corrections did not improve the parameter set. [b] The D atoms of the disordered CD₂Cl₂molecule could not be found

in the difference Fourier syntheses.

sion was cooled to –40 °C, and PhPCl₂(775 mg, 0.588 mL,

4.34 mmol) in toluene (0.3 mL) was injected slowly through a sy-

ringe. The reaction mixture was stirred for 1.5 h at –30 °C and 1 h

at 10 °C, the insoluble materials were washed with toluene

(2ϫ10 mL) and separated by centrifugation, and the clear liquid

was collected. The volatile materials were removed under vacuum

to give a brown oil (110 mg). The resulting mixture thus obtained

contained 26c (ca. 80%), 27c (20%), and several unidentified prod-

ucts (from ³¹P and ¹²⁵Te NMR spectroscopy). The remaining insol-

uble materials from the initial reaction were washed with hexane

(2ϫ10 mL), dissolved in toluene (10 mL), and centrifuged. The li-

quid phase was separated and dried under vacuum to give a green-

brown solid (760 mg). The resulting mixture thus obtained con-

tained 27c (ca. 20%) and several unidentified products (from ³¹P

and ¹²⁵Te NMR spectroscopy).

was collected. The remaining insoluble materials were washed with

toluene (2ϫ20 mL) and centrifuged. The centrifuged solutions

were combined, and the volatile materials were removed in vacuo

to give an orange solid (286 mg). The resulting mixture contained

32 (ca. 70%) and bis(ditellane) 31^[17](ca. 30% from ¹³C and ¹²⁵Te

NMR spectroscopy). The product 32 decomposes in CD₂Cl₂under

Ar.

1

32: H{¹¹B} NMR (500.13 MHz, [D₈]toluene, 25 °C): δ = 2.45 [br.

s, 4 H, HB for δ(¹¹B) = –9.1 ppm], 2.74 [br. s, 2 H, HB for δ(¹¹B)

= –2.1 ppm], 2.84 [br. s, 6 H, HB for δ(¹¹B) = –3.9, –6.9 ppm], 2.97

[br. s, 2 H, HB for δ(¹¹B) = –6.9 ppm], 3.15 [br. s, 4 H, HB for

δ(¹¹B) = –3.1 ppm], 3.61 [br. s, 2 H, HB for δ(¹¹B) = –0.1 ppm],

3.70 (t, ²J

= 13.9 Hz, 2 H, CH₂) ppm. ¹¹B{¹H} NMR

³¹P,¹H

(160.5 MHz, [D₈]toluene, 25 °C): δ = –9.1 (4 B), –6.9 (6 B), –3.9 (2

1

B), –3.1 (4 B), –2.1 (2 B), –0.1 (2 B) ppm. H NMR (500.13 MHz,

CD₂Cl₂, 25 °C): δ = 4.57 (t, ²J₃₁_P,₁_H= 11.9 Hz, 2 H, CH₂) ppm. EI-

MS (70 eV): m/z (%) = 872 (5) [M]⁺.

2-Diethylamino-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2-di-

telluraphospholane (26d): Freshly prepared 4 (747 mg, 1.54 mmol)

was cooled to –40 °C and suspended in toluene (50 mL). The sus-

pension was cooled to –40 °C, and Et₂NPCl₂(0.223 mL,

1.54 mmol) was injected slowly through a syringe. The reaction

mixture was stirred for 1 h at –40 °C and 30 min at 0 °C, the insolu-

ble materials were separated by centrifugation, and the clear liquid

was collected. The volatile materials were removed under vacuum

to give a yellow-brown oil (690 mg). The resulting mixture thus

obtained contained 26d (ca. 35%), 27d (20 %), 29d (20%), 29dЈ

(25%), together with bis(ditellane) 31^[17]and several unidentified

products (from ³¹P and ¹²⁵Te NMR spectroscopy). The product 26d

decomposes in [D₈]toluene under Ar at room temp. or at –30 °C to

form 31 and black elemental tellurium powder.

Crystal Structure Determination of 11, 15, 21: Structure solutions

and refinements were performed with the program package

SHELXTL-PLUS V.5.1.^[30]Details pertinent to the crystal struc-

ture determination are listed in Table 6. Crystals of appropriate size

were sealed under argon in Lindemann capillaries, and the data

collections were performed at 133 K.^[31]

Supporting Information (see footnote on the first page of this arti-

n

³¹P,¹³

C

cle): J

(n = 1,2) data together with isotope-induced chemical

shifts Δ^12/13C(³¹P) (n = 1,2), depiction of the oxidation of 11 with

sulfur and selenium, ³¹P and ⁷⁷Se NMR spectra, ³¹P and ¹²⁵Te

NMR spectra of 32 (calcd. and exp.), and calculated NMR spectro-

scopic data of some 1,3,2-diselenaphospholanes prepared in this

work and their selenides.

n

2-{4,5-[1,2-Dicarba-closo-dodecaborano(12)]-1,3,2-ditelluraphos-

pholan-2-yl}methyl-4,5-[1,2-dicarba-closo-dodecaborano(12)]-1,3,2-

ditelluraphospholane (32): Freshly prepared 4 (430 mg, 0.89 mmol)

was cooled to –40 °C and suspended in toluene (30 mL). The sus-

pension was cooled to –40 °C, and Cl₂PCH₂PCl₂(0.060 mL,

0.445 mmol) was injected slowly through a syringe. The reaction

mixture was stirred for 1 h at –40 °C and 30 min at 0 °C, the insolu-

ble materials were separated by centrifugation, and the clear liquid

Acknowledgments

Support of this work by the Deutsche Forschungsgemeinschaft

(DFG) is gratefully acknowledged.

Eur. J. Inorg. Chem. 2014, 1929–1948

1947

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FULL PAPER

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[2]

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asov, A. N. Pudovik, Russ. Chem. Rev. 1983, 52, 361–376.

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Published Online: February 27, 2014

Eur. J. Inorg. Chem. 2014, 1929–1948

1948

Article Doi

1,3,2-diselena- and 1,3,2-ditelluraphospholanes with an annelated 1,2-dicarba-closo-dodecaborane(12) unit

DOI: 10.1002/ejic.201301600

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Article abstract of DOI:10.1002/ejic.201301600

Full text of DOI:10.1002/ejic.201301600

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