Synthesis of 5,5‘-di(9H-carbazol-9-yl)-2,2‘-bipyridine (Czbipy)
5,5‘-Di(9H-carbazol-9-yl)-2,2‘-bipyridine was synthesized according to a reported procedure by Shan et. al..[225] Under Ar atmosphere, a mixture of 5,5’-dibromo-2,2’-bipyridine (500 mg, 1.59 mmol), carbazole (586 mg, 3.5 mmol), copper(I) iodide (61 mg, 0.32 mmol), 18-crown-6 (84 mg, 0.32 mmol), potassium carbonate (549 mg, 3.98 mmol) and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU, 1.67 mL) were placed in a pre-heated 100 mL Schlenk flask. The flask was connected to a reflux condenser before the mixture was stirred for 24 h at 190 °C in an oil bath. At 190 °C the reaction mixture turned into a yellow solution, after 24 h a black viscous oil was obtained which was quenched with 2 M HCl solution (100 mL). The mixture was extracted with dichloromethane and washed with NH3·H2O (25%, 60 mL) and water. The combined organic layers were dried over magnesium sulfate and the solvent was removed in vacuo. The crude product was purified by column chromatography on amino-functionalized silica gel from cyclohexane and dichloromethane. The obtained yellow solid was further purified by recrystallization from a mixture of cyclohexane and dichloromethane and yielded a light yellow crystalline solid 540 mg (1.11 mmol, 70%).
1H NMR (200 MHz, CDCl3, 25 °C): δ = 9.02 (d, J= 2.4 Hz, 2H), 7.12 (d, J= 8.4 Hz, 2H), 8.19 (d, J = 7.5 Hz, 4H), 8.12 (dd, J = 8.4 Hz, J = 2.5 Hz, 2H), 7.56-7.41 (m, 8H), 7.36 (dt, J = 6.7 Hz, J = 2.5 Hz, 4H) ppm.
13C NMR (50 MHz, CDCl3, 25 °C): δ = 154.1, 147.8, 140.7, 135.3, 135.0, 126.5, 124.1, 122.3, 120.9, 120.7, 109.6 ppm.
Synthesis of rhenium(dicarbazolylbipyridine)(tricarbonyl) chloride [Re(Czbipy)(CO)3Cl]
Under inert conditions, 5,5‘-di(9H-carbazol-9-yl)-2,2‘-bipyridine (243 mg, 0.5 mmol) and rhenium pentacarbonyl chloride (181 mg, 0.5 mmol) were dissolved and refluxed in toluene for
C34H22N4
M = 486.58 g mol-1
C37H22ClN4O3Re M = 792.09 g mol-1
20 h. After cooling the reaction to room temperature, the solid was collected by filtration and was washed with hexane and toluene. To purify the compound, it was recrystallized in hexane to yield an orange solid (182 mg, 50%)
1H NMR (400 MHz, DMSO-d6, 25 °C): δ = 9.40 (d, J = 1.8 Hz, 2H), 9.17 (d, J = 8.8 Hz, 2H),
1,3,5-Tris(9-ethyl-9H-carbazol-3-yl)benzene was synthesized according to procedure reported by Ou and coworkers.[156] 1,3,5-Tris(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzene (428 mg, 0.94 mmol), 3-bromo-9-ethylcarbazole (800 mg, 2.92 mmol), [1,1’-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (103 mg, 0.14 mmol), cesium carbonate (3250 mg, 10.0 mmol), 1,4-dioxane (20 mL) and water (4 mL) were placed in a 100 mL Schlenk finger and were degassed by three freeze-pump-thaw cycles. Under Ar atmosphere, the suspension was stirred for 20 h at 90 °C. After cooling to room temperature, the brown suspension was quenched with water (30 mL). The mixture was extracted with dichloromethane and water. The combined organic layers were dried over magnesium sulfate and the solvent removed in vacuo. The crude product was purified by column chromatography from a mixture of cyclohexane and dichloromethane. The product was obtained as off-white solid (488 mg, 74%). 123.7, 123.3, 120.8, 119.4, 119.1, 108.9, 108.7, 37.8, 14.0 ppm.
C48H39N3
M = 657.861 g mol-1
Synthesis of tris(4-bromophenyl)phosphine
Tris(4-bromophenyl)phosphine was synthesized according to a reported procedure by Fischer et. al..[226] In a pre-dried Schlenk flask 1,4-dibromobenzene (4.48 g, 19.00 mmol) was dissolved in diethyl ether (110 mL). At -78 °C n-butyllithium (2.5 M in hexane, 7.5 mL, 18.75 mmol) was added slowly over 30 min. After 2 h of stirring at -78 °C, phosphorus trichloride (0.5 mL, 5.73 mmol) was added dropwise to the colorless solution which immediately turned yellow.
Then the solution was allowed to slowly warm up to room temperature and stirred overnight.
A saturated mixture of sodium bicarbonate (30 mL) and water (30 mL) was added so that the organic layer could be separated. The residual aqueous layer was extracted with dichloromethane (2 x 25 mL). The combined organic layers were dried over magnesium sulfate and the solvent was removed in vacuo. The crude product was purified by column chromatography from cyclohexane and 2.29 g (4.59 mmol, 80%) of a white crystalline solid was obtained as a product.
1H NMR (200 MHz, CDCl3, 25 °C): δ = 7.48 (dd, 3JHH = 8.5 Hz, 4JPH = 1.2 Hz, 6H, H-3), 7.12 (dd, 3JHH = 8.5 Hz, 3JPH = 7.2 Hz, 6H, H-2) ppm.
31P NMR (81 MHz, CDCl3, 25 °C): δ = -8.46 ppm.
13C NMR (50 MHz, CDCl3, 25 °C): δ = 135.2 (d, 3JCP = 12 Hz), 135.1 (d, 2JCP = 20 Hz), 132.0 (d, 1JCP = 7 Hz), 124.0 ppm.
Synthesis of tris(4-bromophenyl)phosphine-borane
Tris(4-bromophenyl)phosphine-borane was synthesized according to a procedure of Van Overschelde et al..[181] In a pre-dried Schlenk finger tris(4-bromophenyl)phosphine (100 mg, 0.2 mmol) was added and dissolved in anhydrous dichloromethane (0.4 mL). Then borane dimethyl sulfide complex (0.19 mL, 2.0 mmol) was added and after stirring the reaction for
C18H12Br3P M = 498.98 g mol-1
C18H15BBr3P M = 512.81 g mol-1
24 h at room temperature, saturated aqueous ammonia chloride solution (1 mL) was added. The reaction mixture was stirred for another 1 h, after that it was poured into water (10 mL). The collected organic phase was washed with saturated aqueous sodium bicarbonate solution (15 mL) before it was dried over magnesium sulfate and filtrated over silica. The crude product was purified by column chromatography from cyclohexane (70%) and dichloromethane (30%) and 297 mg (0.58 mmol, 83%) of a white crystalline solid was obtained as a product.
1H NMR (200 MHz, CDCl3, 25 °C): δ = 7.60 (dd, J= 8.5 Hz, J= 2.0 Hz, 6H), 7.40 (dd, J=
Synthesis of rhodium(I) amido bis(olefin) complex [Rh(trop2NH)(PPh3)](OTf)]
The complex [Rh(trop2NH)(PPh3)](OTf)] was provided and developed by Grützmacher and coworkers.[190] Dimer [RhCl(trop2NH)(PPh3)]2 (1.0 eq, 0.63 mmol, 500 mg) (trop2N = bis(5-H-dibenzo-[a,d]cyclohepten-5-yl)amide) and silver trifluoromethanesulfonate (AgOTf) (1.03 eq, 0.65 mmol, 166 mg) were suspended in dichloromethane (15 mL) and were stirred for 12 h. The suspension was filtered over celite, the product was precipitated from the remaining filtrate. The solid was decanted off and dried under vacuum (542 mg, 0.06 mmol, 95%).
1H NMR (200 MHz, CDCl3, 25 °C): δ = 7.84 (m, 6H), 7.70-7.55 (m, 9H), 7.40-7.15 (m, 8H),
Synthesis of rhodium(triphenylphosphine)carbonylacetylacetonate [Rh(PPh3)(CO)(acac)]
In a round bottom flask triphenylphosphine (71 mg, 0.27 mmol) and rhodium(triphenylphosphine)carbonylacetylacetonate (70 mg, 0.27 mmol) were dissolved in dichloromethane (15 mL). The reaction mixture immediately turned yellow and evolution of gas was observed. After stirring the reaction for 20 h at room temperature, the solvent was removed under vacuum and yellow powder was obtained as product (144 mg, 105%).
1H NMR (200 MHz, CDCl3, 25 °C): δ = 7.74-7.32 (m, 15H), 5.43 (s, 1H, H-C(sp2)), 2.09 (s, 3H, CH3), 1.61 (s, 3H, CH3) ppm.
31P NMR (81 MHz, CDCl3, 25 °C): δ = 48.7 (d, 1JRhP = 176.7 Hz) ppm.
13C NMR (50 MHz, CDCl3, 25 °C): δ = 186.7 (d, 1JRhCO = 256.0 Hz), 134.7 (d, J= 11.3 Hz), 132.9, 132.5 (d, J= 14.4 Hz), 132.2 (d, J= 18.2 Hz), 130.5, 128.7 (d, J= 11.5 Hz), 128.3 (d, J
= 10.4 Hz), 101.0, 27.8 (d, J= 6.0 Hz), 27.0 ppm.
31P MAS NMR (168 MHz, 25°C): δ = 47, 27 ppm.
Synthesis of tetrakis(4-bromophenyl)methane
Tetrakis(4-bromophenyl)methane was synthesized according to synthesis of Nguyen et al. with slight modifications.[227]Tetraphenylmethane (4.00 g, 12.5 mmol) was place in a round flask, neat bromine (8 mL, 156 mmol) was added dropwise and the mixture was stirred for 45 min.
At 0 °C ethanol (50 mL) was slowly added. The orange mixture was allowed to come to room temperature, stirred overnight and quenched by addition of bisulfite solution (100 mL).
Additionally, the yellow solid was washed with water and ethanol. The crude product was C25H25O3PRh
M = 507.35 g mol-1
C25H16Br4
M = 636.02 g mol-1
purified by column chromatography from cyclohexane. 4.93 g (7.75 mmol, 62%) of a white
Tris(4-(N-carbazolyl)phenyl)phosphine-borane (CzTPP) was synthesized according to tris(4-bromophenyl)phosphine borane. In a pre-dried Schlenk flask 9-(4-bromophenyl)carbazole (2.00 g, 6.2 mmol) was dissolved in diethyl ether (60 mL).
At -78 °C tert-butyllithium (2.5 M in hexane, 7.3 mL, 12.40 mmol) was added slowly over 15 min. After 2 h of stirring at -78 °C, and 1 h at room temperature, the reaction was cooled to -78 °C and phosphorus trichloride (0.16 mL, 1.86 mmol) was added dropwise to the colorless solution which immediately turned yellow. Then the solution was allowed to slowly warm up to room temperature and stirred overnight. A saturated mixture of sodium bicarbonate (30 mL) and water (30 mL) was added so that the organic layer could be separated. The residual aqueous layer was extracted with dichloromethane (2 x 25 mL). The combined organic layers were dried over magnesium sulfate and the solvent was removed in vacuo. The crude product was purified by column chromatography from cyclohexane and dichloromethane, and 1.058 g (1.396 mmol, 75%) of carbazolyl)phenyl)phosphine was obtained. In a second step, tris(4-(N-carbazolyl)phenyl)phosphine (200 mg, 0.264 mmol) was added and dissolved in anhydrous dichloromethane (18 mL) in a pre-dried Schlenk finger. Then borane dimethyl sulfide complex (0.25 mL, 2.64 mmol) was added and after stirring the reaction for 24 h at room temperature, saturated aqueous ammonia chloride solution (3 mL) was added. The reaction mixture was stirred for another 1 h, after that it was poured into water (15 mL). The collected organic phase was dried over magnesium sulfate and filtrated over silica. The crude product was purified by column chromatography from cyclohexane and dichloromethane and 175 mg (0.227 mmol, 86%) of a white crystalline solid was obtained as a product.
C54H39BN3P M = 771.71 g mol-1
1H NMR (500 MHz, CDCl3, 25 °C): δ = 8.17 (d, J= 7.63 Hz, 6H), 8.05 (t, J= 9.30 Hz, 6H), 7.85 (d, J= 7.93 Hz, 6H), 7.59 (d, J= 8.15 Hz, 6H), 7.46 (t, J= 7.70 Hz, 6H), 7.35 (t, J= 7.45 Hz, 6H), 0.7-2.0 (br s, 3H) ppm.
31P NMR (81 MHz, CDCl3, 25 °C): δ = 20.4 ppm.
11B NMR (160 MHz, CDCl3, 25°C): δ = -37.6 ppm.
13C NMR (125 MHz, CDCl3, 25 °C): δ = 141.2, 140.3, 135.1 (d, J= 10.7 Hz), 127.3 (d, J= 57.2 Hz), 127.2 (d, J= 10.7 Hz), 126.4, 124.0, 120.9, 120.7, 109.9 ppm.