Inorganic Chemistry
Article
3-[(Diphenylphosphoryl)methyl]benzene-1,2-dithiol (4). An
ice-cooled solution of 2 (2.0 g, 4.5 mmol) was dissolved in
fluorobenzene (PhF) (20 mL) and treated with BBr3 (1.3 mL, 13.5
mmol). The stirred mixture was then heated to 70 °C for 12 h, allowed
to cool to rt, and stored at −20 °C. An off-white precipitate formed
which was filtered off and washed with cold PhF (2 × 5 mL) and
hexane (3 × 15 mL). The residue was dissolved in MeOH, and all
volatiles were removed in vacuum. This procedure was repeated until
the oily residue solidified (yield 1.61 g, 72%). 31P{1H} NMR (CDCl3):
δ = 48.5 (s). 1H NMR (CDCl3): δ = 3.46 (s, 1 H), 3.89 (s, 1 H), 4.43
(2-Bromo-4,7-bis(isopropylthio)benzo[d]-1,3,2-dithiaborole
Bis(tribromoborane) Adduct (7d′). The mother liquor obtained
after separation of 7d was once more stored at −20 °C. After 1 day
colorless blocks precipitated which were collected by careful
decantation, washed with hexane, and dried under vacuum (yield 5
1
mg, 0.5%). 11B{1H} NMR (CDCl3): δ = −6.2 (s), 52.3 (s). H NMR
(CDCl3): δ = 1.31 (d, 3JHH = 6.8 Hz, 12 H), 3.55 (sept, 3JHH = 6.8 Hz,
2 H), 7.45 (s, 2 H). 13C{1H} (CDCl3): δ = 22.8, 41.1, 129.4, 131.7,
145.6. The amount of product was too small to obtain an elemental
analysis.
3
3
2-Bromo-4-[(diphenylphosphoryl)methyl]benzo[d]-1,3,2-di-
thiaborole Tribromoborane Adduct (9d). The off-white precip-
itate was collected by filtration, washed with cold PhF and hexane, and
dried under vacuum (yield 473 mg, 68%). 31P{1H} NMR (CDCl3): δ
= 53.9 (q). 11B{1H} NMR (CDCl3): δ = −12.2 (s), 51.6 (s). 1H NMR
(CDCl3): δ = 4.60 (d, 3JPH = 14.4 Hz, 2 H), 6.99 (m, 1 H), 7.07 (m, 1
H) 7.31 (m, 1 H), 7.40−7.52 (m, 4 H), 7.58−7.72 (m, 6 H). 13C{1H}
(d, JPH = 14.1 Hz, 2 H), 7.05 (dd, JHH = 7.7 Hz, 8.0 Hz, 1 H), 7.29
(d, 3JHH = 8.0 Hz, 1 H), 7.39 (d, 3JHH = 7.7 Hz, 1 H), 7.49−7.56 (m, 4
H), 7.63−7.72 (m, 6 H). 13C{1H} NMR (CDCl3): δ = 37.7 (d, 1JPC
=
67.1 Hz), 126.7 (d, 5JPC = 2.9 Hz), 128.3 (d, 4JPC = 3.3 Hz), 128.4 (d,
3
3
3JPC = 4.7 Hz), 128.6 (d, JPC = 11.8 Hz), 129.8 (d, JPC = 6.2 Hz),
131.2 (d, 2JPC = 9.3 Hz), 131.8 (d, 1JPC = 99.3 Hz), 132.1 (d, 4JPC = 2.7
Hz), 134.4 (d, 2JPC = 8.6 Hz), 136.5 (d, 4JPC = 2.8 Hz). Anal. Calcd for
C19H17OPS2 (356.44): C, 64.02; H, 4.81; S, 17.99. Found: C, 63.42;
H, 4.86; S, 17.52.
2
(CDCl3): δ = 33.8 (d, JPC = 67.5 Hz), 124.7 (s), 129.36 (s), 133.38
(s), 135.4 (s), 142.0 (s). Anal. Calcd for C19H15B2Br4OPS2 (695.66):
C, 32.80; H, 2.17; S, 9.22. Found: C, 33.76; H, 2.29; S, 9.00.
Tetraethylammonium Bis(3-[(diphenylphosphoryl)methyl]-
benzene-1,2-dithiolato)cobaltate(III) ([Et4N]10). A solution of 4
(200 mg, 0.56 mmol) in degassed EtOH (20 mL) was treated with
NEt3 (0.16 mL, 1.12 mmol) and NEt4Cl (1.86 g, 11.2 mmol).
Addition of [(Co(H2O)6]Cl2 produced a yellow-brown precipitate.
The mixture was stirred for 4 h, after which it was exposed to air. The
yellow precipitate immediately turned deep blue. After the mixture was
stirred overnight, the precipitate was collected by filtration, washed
with EtOH, water, and MTBE (3 × 15 mL each), and dried in vacuum
(yield 186 mg, 74% based on Co). 31P{1H} NMR (CD2Cl2, 295 K): δ
= 99.7 (br s). 1H NMR (CD2Cl2, 295 K): δ = −33.7 (2 H), −25.7 (2
H), −21.6 (2 H), −4.5 (8 H), 1.7 (12 H), 7.0 (12 H), 9.7 (8 H), 21.3
(4 H). The paramagnetic nature of this compound prevented 13C
NMR data from being obtained. Anal. Calcd for C46H50CoNO2P2S4
(898.03): C, 61.52; H, 5.61; N, 1.56; S, 14.28. Found: C, 61.09; H,
5.67; N, 1.68; S, 14.29.
3-[(Diphenylphosphino)methyl]-1,2-mercaptobenzene (5).
A stirred solution of 3 (1.0 g, 2.8 mmol) in methyl tert-butyl ether
(MTBE) (80 mL) was treated with LiAlH4 (320 mg, 8.4 mmol). The
mixture was refluxed for 1 day, quenched with 1 M degassed
hydrochloric acid, and extracted with MTBE (2 × 50 mL) under strict
exclusion of air. The combined organic phases were washed with water
and brine (2 × 30 mL each) and the volatiles evaporated without
further purification. The product was obtained as slightly pink crystals
(yield 770 mg, 81%). 31P{1H} NMR (C6D6): δ = −16.2 (s). 1H NMR
((C6D6): δ = 3.26 (s, 2 H), 3.70 (br s, 2 H), 6.17−6.29 (m, 2 H),
6.58−6.65 (m, 1 H), 6.76−6.85 (m, 6 H), 7.05−7.14 (m, 4 H).
13C{1H} (C6D6): δ = 36.4 (d, 1JPC = 16.3 Hz), 125.8 (d, 3JPC = 1.8 Hz)
127.8 (d, 4JPC = 1.3 Hz), 128.0 (s), 128.3 (d, 3JPC = 6.5 Hz), 128.6 (s),
2
1
133.1 (d, JPC = 18.1 Hz), 133.1 (s) 137.8 (d, JPC = 16.2 Hz), 138.8
(s), 139.0 (s). Anal. Calcd for C19H17PS2 (340.45): C, 67.03; H, 5.03;
S, 18.83. Found: C, 66.83; H, 5.34; S, 18.38.
Generic Procedure for the Synthesis of Benzo-1,3,2-
dithiaboroles. The appropriate thioether (1 mmol) was dissolved
in PhF (15 mL) and BBr3 added (1 equiv per functional group, 1−4
mmol) under ice cooling. The mixture was then stirred for 4−12 h at
70 °C, allowed to cool to rt, and stored overnight at −20 °C.
(2-Bromo-4-(isopropylthio)benzo[d]-1,3,2-dithiaborole Tri-
bromoborane Adduct (7b). The reaction mixture was evaporated
to dryness and the residue suspended in hexane. The insoluble fraction
was filtered off and the filtrate stored at −20 °C. Colorless blocks
precipitated which were collected by careful decantation, washed with
hexane, and dried under vacuum (yield 195 mg, 35%). 11B{1H} NMR
Triethylammonium Bis(3-[(diphenylphosphoryl)methyl]-
benzene-1,2-dithiolato)niccolate ([Et3NH]11). A solution of 4
(200 mg, 0.56 mmol) in degassed EtOH (20 mL) was treated with
NEt3 (0.16 mL, 1.12 mmol) and HNEt3Cl (1.52 g, 11.2 mmol).
Addition of [(Ni(H2O)6]Cl2 (133 mg, 0.56 mmol) produced a deep
purple solution. The mixture was stirred for 4 h, after which it was
exposed to air. The deep purple solution immediately turned deep
green, and a precipitate of the same color appeared. The slurry was
stirred overnight. The precipitate was then collected by filtration,
washed with EtOH, water, and MTBE (each 3 × 15 mL), and dried in
vacuum (yield 204 mg, 78% based on Ni). Due to the paramagnetic
nature of this product, no interpretable NMR data could be obtained.
(−)-ESI-MS: 765.96 [C38H30NiNO2P2S4−]. Anal. Calcd for
C44H46NiNO2P2S4 (869.74): C, 60.76; H, 5.33; N, 1.61; S, 14.46.
Found: C, 60.68; H, 5.42; N, 1.55; S, 14.71.
B i s ( 2 - [ ( d i p h e n y l p h o s p h i n o ) m e t h y l ] - 6 -
mercaptobenzenethiolato)palladium(II) (12). A mixture of Pd-
(acac)2 (45 mg, 0.15 mmol) and 5 (100 mg, 0.30 mmol) in THF (10
mL) was placed in an ultrasound bath. A yellow precipitate began to
form. The mixture was then stirred for 12 h and filtered. The
precipitate was washed with THF (3 × 10 mL) and dried in vacuum
(yield 104 mg, 89% based on Pd). 31P{1H} NMR (DMF-d7): δ = 65.4
(s). − 1H NMR (DMF-d7): δ = 3.65 (m, 4 H), 5.54 (s, 2 H), 6.89 (t,
3JHH = 7.6 Hz, 2 H), 7.07 (d, 3JHH = 7.6 Hz, 2 H), 7.34 (d, 3JHH = 7.6
(CDCl3): δ = 2.2 (s), 55.4 (s). 1H NMR (CDCl3): δ = 1.40 (d, 3JHH
6.7 Hz, 6 H), 3.72 (sept, 3JHH = 6.7 Hz, 1 H), 7.36 (t, 3JHH = 7.8 Hz, 1
=
3
3
H), 7.71 (d, JHH = 7.9 Hz, 1 H), 7.72 (d, JHH = 7.8 Hz, 1 H).
13C{1H} (CDCl3): δ = 22.3 (s), 43.4 (s), 126.5 (s), 126.8 (s), 129.5
(s), 141.8 (s), 146.5 (s). Anal. Calcd for C9H10B2Br4S3 (555.61): C,
19.46; H, 1.81; S, 17.31. Found: C, 19.34; H, 2.31; S, 17.41.
2,6-Dibromobenzo[1,2-d:4,5-d′]bis(1,3,2-dithiaborole) (7c).
Thin colorless needles precipitated which were filtered off, washed
with hexane, and recrystallized from warm PhF (yield 215 mg, 56%).
11B{1H} NMR (CDCl3): δ = 52.6 (s). 1H NMR (CDCl3): δ = 7.97 (s,
2 H). 13C{1H} (CDCl33): δ = 123.0 (s), 139.3 (s). Anal. Calcd for
C6H2B2Br2S4 (383.77): C, 18.78; H, 0.53; S, 33.42. Found: C, 18.89;
H, 0.95; S, 33.63.
Hz, 2 H), 7.67−7.80 (m, 6 H), 8.07−8.18 (m, 4 H). − 13C{1H} NMR
(DMF-d7): δ = 35.0, 125.9, 128.8, 131.2, 134.0. (+)-ESI-MS: 806.98
[M + Na]. Anal. Calcd for C9H10S3B2Br4 (785.28): C, 58.12; H, 4.11;
S, 16.33. Found: C, 58.13; H, 4.16; S, 15.98.
Methanolysis of the Dithiaboroles 7a−d. An excess of
degassed MeOH was added to the corresponding isolated dithiaborole
at 0 °C with stirring.29 After the violent reaction stopped, the mixture
was allowed to warm to rt and stirred for 30 min, after which all
volatiles were removed in vacuum. This procedure was repeated three
times, and the resulting crude product was then dried in vacuum.
2,7-Dibromobenzo[1,2-d:3,4-d′]bis([1,3,2]dithiaborole) (7d).
Thin colorless needles precipitated which were filtered off and washed
with hexane. The mother liquor was treated with hexane and again
stored at −20 °C to give a second crop of crystalline material which
was again collected by filtration and washed with hexane. The
combined precipitates were washed once more with hexane and dried
under vacuum (yield 184 mg, 48%). 11B{1H} NMR (CDCl3): δ = 52.3
1
(s). H NMR (CDCl3): δ = 7.58 (s, 2 H). 13C{1H} (CDCl33): δ =
123.7 (s), 139.2 (s). Anal. Calcd for C6H2B2Br2S4 (383.77): C, 18.78;
H, 0.53; S, 33.42. Found: C, 18.82; H, 0.70; S, 33.15.
C
Inorg. Chem. XXXX, XXX, XXX−XXX