Synthesis and Reactivity of New Ni, Pd, and Pt 2, 6-Bis (di-tert ...

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Inorganic Chemistry Synthesis of [(PONOP)PdCl]Cl 3 CH 2 Cl 2 (2b). In a 500 mL Schlenk flask PONOP ligand (500 mg, 1.25 mmol), PdCl 2 (NCCH 3 ) 2 (324 mg, 1.25 mmol), and 100 mL of anhydrous CH 2 Cl 2 were combined under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 60 min. The volatiles were removed under vacuum (overnight), leaving a light yellow solid which was washed with hexane and benzene and dried under vacuum yielding complex 2c (87%). When this reaction was carried out in CH 3 CN as solvent, some decomposition of the PONOP ligand was observed. 1 H NMR (500 MHz, CD 3 OD): δ 8.28 (t, J H H = 8.3 Hz, 1H), 7.28 (d, J H H = 8.5 Hz, 2H), 2.01(s, 2H), 1.57 (vt, J P H = 8.0 Hz, 36H). 13 C{ 1 H} NMR (100 MHz, CD 2 Cl 2 ): δ 163.8 (s), 150.9 (s), 106.7 (s), 42.3 (t, J P C = 5.2 Hz), 27.5 (t, J P C = 2.5 Hz). 31 P{ 1 H} NMR (162 MHz, CD 2 Cl 2 ): δ 192.6 (s). Anal. Calcd (found) for C 22 H 41 Cl 4 NO 2 P 2 Pd: % C, 39.93 (40.25); % H, 6.24 (6.32); % N, 2.12 (2.13). [(PONOP)PdCl]Cl (3b). In a 500 mL Schlenk flask complex 2b (500 mg) and 100 mL of THF were combined under a nitrogen atmosphere. The mixture was sonicated for 2 h and then THF was removed by cannula leaving the solid at the bottom of the flask. A 100 mL portion of hexane was added, and the solid sonicated again for 2 h. Hexane was removed by cannula leaving the solid at the bottom of the flask. The solid was dried overnight under vacuum yielding pure complex 3b (83%). 1 H NMR (400 MHz, CD 2 Cl 2 ): δ 8.65 (t, J H H = 7.6 Hz, 1H), 7.28 (d, J H H = 8.0 Hz, 2H), 1.50 (vt, J P H = 8.0 Hz, 36H). 13 C{ 1 H} NMR (100 MHz, CD 2 Cl 2 ): δ 163.8 (s), 150.9 (s), 106.7 (s), 42.3 (t, J P C = 5.2 Hz), 27.5 (t, J P C = 2.5 Hz). 31 P{ 1 H} NMR (162 MHz, CD 2 Cl 2 ): δ 192.6 (s). (H-PONOP)PdCl (4b). In a 250 mL Schlenk flask, complex 3b (100 mg, 0.17 mmol) and 70 mL of pentane were combined under a nitrogen atmosphere. A 0.17 mL portion of LiHBEt 3 (0.17 mmol, 1 M in THF) was added dropwise at room temperature. The reaction mixture was stirred at room temperature for 20 min. The solution was filtered under a nitrogen atmosphere using a cannula, and the volatiles were removed under vacuum yielding complex 4b (79%). Crystals of complex 4b were grown by slow evaporation from a benzene solution. Complex 4b was more stable than 4c and slowly decomposed after a few days in solution. 1 H NMR (400 MHz, C 6 D 6 ): δ 4.18 (t, J H H = 2.8 Hz, 2H), 3.37 (t, J H H = 3.2 Hz, 2H), 1.34 (vt, J P H = 7.6 Hz, 36H). 13 C{ 1 H} NMR (125 MHz, C 6 D 6 ): δ 159.7 (s), 71.3 (t, J P C = 4.4 Hz), 39.8 (t, J P C = 7.8 Hz), 26.9 (s), 25.1 (s). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ): δ 173.1 (s). Attempted Synthesis of (H-PONOP)PdH (5b). In a 100 mL Schlenk flask, complex 4b (50 mg, 0.09 mmol) and 10 mL of pentane were combined under a nitrogen atmosphere. A 0.09 mL portion of LiHBEt 3 (0.09 mmol, 1 M in THF) was added dropwise at room temperature. The reaction mixture was stirred at room temperature and monitored by 31 P NMR spectroscopy over time. No Pd H complex was observed. With longer stirring times complex 4b slowly decomposed. From the decomposed mixture, one compound was isolated as crystalline solid, [Pd(μ-Cl)( t Bu 2 PO 333 H 333 OP t Bu 2 )] 2 (Figure 9), which is a known catalyst for the cross-coupling reactions of vinyl and aryl chlorides with arylboronic acids, arylzinc reagents, and thiols. 14,21 Synthesis of [(PONOP)PtCl]Cl 3 CH 3 CN (2c). In a 500 mL Schlenk flask, PONOP (500 mg, 1.25 mmol), PtCl 2 (NCPh) 2 (534 mg, 1.25 mmol), and 100 mL of anhydrous CH 3 CN were combined under a nitrogen atmosphere. The reaction mixture was stirred at room temperature for 30 min. The volatiles were removed under vacuum (overnight), leaving a white solid which was washed with hexane and benzene and dried under vacuum yielding complex 2c (84%). 1 H NMR (400 MHz, CD 2 Cl 2 ): δ 8.67 (t, J H H = 8.4 Hz, 1H), 7.32 (d, J H H = 8.0 Hz, 2H), 1.98 (s, 3H), 1.11 (vt, J P H = 8.0 Hz, 36H). 13 C{ 1 H} NMR (100 MHz, CD 3 CN): δ 164.0 (t, J P C = 5.5 Hz), 148.3 (s), 106.3 (s), 42.4 (t, J P C = 9.4 Hz), 27.0 (t, J P C = 2.5 Hz). 31 P{ 1 H} NMR (162 MHz, CD 3 CN): δ 175.0 (s, J Pt P = 2535 Hz). Anal. Calcd (found) ARTICLE Figure 9. X-ray structure of the decomposition product [Pd(μ-Cl)- ( t Bu 2 PO 333 H 333 OP t Bu 2 )] 2 . Ellipsoids are shown at the 50% level. for C 23 H 42 Cl 2 N 2 O 2 P 2 Pt: % C, 39.10 (39.20); % H, 5.99 (5.95); % N, 3.96 (3.76). [(PONOP)PtCl]Cl (3c). In a 500 mL Schlenk flask, complex 2c (500 mg) and 100 mL of THF were combined under a nitrogen atmosphere. The mixture was sonicated for 2 h, and then THF was removed by cannula while the solid remained at the bottom of the flask. A 100 mL portion of hexane was added, and the solid sonicated again for 2 h. Hexane was removed by cannula leaving solid at the bottom of the flask. The solid was dried overnight under vacuum yielding pure complex 3c (83%). The 1 H, 13 C, and 31 P NMR spectra of complex 3c were very similar to those of complex 2c, except for the absence of a bound CH 3 - CN resonance. 1 H NMR (500 MHz, CD 3 OD): δ 8.32 (t, J H H = 8.0 Hz, 1H), 7.29 (d, J H H = 8.0 Hz, 2H), 1.55 (vt, J P H = 8.0 Hz, 36H). 13 C{ 1 H} NMR (100 MHz, CD 3 CN): δ 164.0 (t, J P C = 5.5 Hz), 148.3 (s), 106.3 (s), 42.4 (t, J P C = 9.4 Hz), 27.0 (t, J P C = 2.5 Hz). 31 P{ 1 H} NMR (162 MHz, CD 3 CN): δ 175.0 (s, J Pt P = 2535 Hz). Anal. Calcd (found) for C 21 H 39 Cl 2 NO 2 P 2 Pt: % C, 37.90 (38.29); % H, 5.91 (5.85); % N, 2.10 (2.31). (H-PONOP)PtCl (4c). In a 250 mL Schlenk flask, complex 3c (100 mg, 0.15 mmol) and 70 mL of pentane were combined under a nitrogen atmosphere. A 0.15 mL portion of LiHBEt 3 (0.15 mmol, 1 M in THF) was added dropwise at room temperature. An immediate color change from colorless to light yellow was observed. The reaction mixture was stirred at room temperature for 20 min. The solution was filtered under a nitrogen atmosphere using a cannula, and the volatiles were then removed under vacuum yielding pure light yellow complex 4c (81%). Complex 4c was not stable in solution, as stirring the solution for 4 h led to a color change from yellow to colorless because of decomposition. Crystals of complex 4c were grown by slow evaporation from a benzene solution. 1 H NMR (400 MHz, C 6 D 6 ): δ 4.24 (t, J H H = 3.0 Hz, 2H), 3.44 (t, J H H = 3.4 Hz), 1.33 (vt, J P H = 7.6 Hz, 36H). 13 C{ 1 H} NMR (100 MHz, C 6 D 6 ): δ 159.4 (s), 70.8 , 40.8 (t, J P C = 12.1 Hz), 27.8 (t, J P C = 2.5 Hz), 25.6 (s). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ): δ 157.9 (s, J Pt P = 2799 Hz). Anal. Calcd (found) for C 21 H 40 ClNO 2 P 2 Pt: % C, 39.97 (40.10); % H, 6.39 (6.42); % N, 2.22 (2.43). Attempted Synthesis of (H-PONOP)PtH (5c). In a 100 mL Schlenk flask, complex 4c (50 mg, 0.08 mmol) and 10 mL of pentane were combined under a nitrogen atmosphere. A 0.08 mL portion of LiHBEt 3 (0.08 mmol, 1 M in THF) was added dropwise at room temperature. The reaction mixture was stirred at room temperature and monitored by 31 P NMR spectroscopy over time. No Pt H complex was observed. With longer stirring times complex 4c decomposed. From the decomposed mixture, one compound was isolated as crystalline solid, 9450 dx.doi.org/10.1021/ic201102v |Inorg. Chem. 2011, 50, 9443–9453
Inorganic Chemistry and the unit cell was similar to that obtained in an analogous reaction with the Pd complex (vide infra, Figure 9), but no X-ray data were collected. Reaction of the Complex 4c and 4b with CHCl 3 . In a 50 mL Schlenk flask complexes 4b or 4c (20 mg) and 0.5 mL of CHCl 3 were combined under a nitrogen atmosphere. The reaction mixture was stirred at room temperature. After 30 min both solutions changed color. The volatiles were removed under vacuum, and complex 3c 3 CHCl 3 or 3b 3 CHCl 3 had been generated accordingly along with some decomposition, as confirmed by NMR spectroscopy. 3c 3 CHCl 3 : 1 H NMR (400 MHz, CD 3 CN): δ 7.86 (t, J H H = 8.2 Hz, 1H), 7.26 (s, 1H), 6.80 (d, J H H = 8.0 Hz, 2H), 1.11 (vt, J P H = 8.0 Hz, 36H). 31 P{ 1 H} NMR (162 MHz, CD 3 CN): δ 175.0 (s, J Pt P = 2535 Hz). 3b 3 CHCl 3 : 1 H NMR (500 MHz, CD 2 Cl 2 ): δ 8.54 (t, J H H = 7.6 Hz, 1H), 7.36 (s, 1H), 7.28 (d, J H H = 8.0 Hz, 2H), 1.50 (vt, J P H = 8.0 Hz, 36H). 31 P{ 1 H} NMR (202 MHz, CD 2 Cl 2 ): δ 192.6 (s). Reaction of the Complex 4b with MeLi. In a 50 mL Schlenk flask, freshly prepared complex 4b (20 mg, 0.037 mmol) and 3 mL of THF were combined under a nitrogen atmosphere. Twenty-two microliters of MeLi (0.037 mmol, 1.66 M in THF) were added dropwise at room temperature. The reaction mixture was stirred at room temperature for 12 h, and the solution filtered through Celite. The volatiles were then removed under vacuum yielding complex 6b (80% purity). Compound 6b was not very stable. It slowly decomposed in solution over several days even in the freezer at 20 °C. Crystallization of complex 6b was not successful as it slowly decomposed in hexane after 4 d at room temperature. 1 H NMR (400 MHz, C 6 D 6 ): δ 4.16 (s, 2H), 3.74 (s, 2H), 1.23 (vt, J P H = 7.2 Hz, 36H), 0.52 (t, J P H = 5.4 Hz, 3H). 13 C{ 1 H} NMR (125 MHz, C 6 D 6 ): δ 159.1 (s), 67.9 (t, J P C = 3.3 Hz), 39.8 (t, J P C = 8.1 Hz), 28.0 (s), 27.1 (s), 20.4 (t, J P C = 6.8 Hz). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ): δ 168.4 (s). Reaction of the Complex 4c with MeLi. In a 50 mL Schlenk flask, freshly prepared complex 4c (20 mg, 0.03 mmol) and 3 mL of THF were combined under a nitrogen atmosphere. Eighteen microliters of MeLi (0.03 mmol, 1.66 M in THF) were added dropwise at room temperature. The reaction mixture was stirred at room temperature and monitored by 31 P NMR spectroscopy over time. After 12 h, a new product (highly unstable) was observed (30%) by 31 P NMR spectroscopy while unreacted 4c remained in the solution. Further stirring (24 h) of this solution at room temperature led to decomposition as determined by the observation of many peaks in the 31 P NMR spectrum. 1 H NMR (400 MHz, C 6 D 6 ) (12 h RT): δ 10.51 (t, J Pt H = 989 Hz, J P H = 10.0 Hz) and many unidentified peaks. 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ) (12 h RT): δ 198.4 (s, J Pt P = 2790 Hz), 157.9 (s, J Pt P = 2799 Hz, 4c). 31 P{ 1 H} NMR (162 MHz, C 6 D 6 ) (24 h RT, major peaks): δ 182.8 (s, J Pt P = 2263 Hz), 180.1 (s, J Pt P = 2256 Hz), 173.8 (s, J Pt P = 2831 Hz). Reaction of the Complexes 3c and 3b with MeLi. In a 50 mL Schlenk flask, complexes 3c or 3b (20 mg) and 1 mL of THF were combined under a nitrogen atmosphere. Two equivalents of MeLi (1.66 M in THF) were added dropwise at room temperature. The reaction mixture was stirred at room temperature for 30 min, and the solution was filtered through Celite. The volatiles were then removed under vacuum, and an NMR spectrum was recorded. Neither reaction was clean. Crystal structures of these unknown compounds were unsuccessful as they decomposed in hexane after 7 d. 31 P{ 1 H} NMR (162 MHz, C 6 D 6 )(3c): δ 163.1 (s, J Pt P = 2207 Hz), 161.4 (s, J Pt P = 2235 Hz) in: 1.25:1 ratio. 31 P{ 1 H} NMR (162 MHz, C 6 D 6 )(3b): δ 174.4 (s), 172.5 (s), 170.5 (s), 168.3 (s) in 1:2:4:7 ratio. (PONOP)NiCl(BPh 4 ) (3a-BPh 4 ). In a 50 mL Schlenk flask, complex 3a (30 mg, 0.057 mmol) and 1 mL of MeOH were combined under a nitrogen atmosphere. A solution of NaBPh 4 (194 mg, 0.57 mmol) in MeOH (2 mL) was added dropwise at room temperature. The reaction mixture was stirred at room temperature for 20 min, and a red solid precipitated from solution. The solvent was removed by syringe, and the ARTICLE solid was washed 2 times with MeOH and dried under vacuum yielding pure complex 3a-BPh 4 (88%). Crystals of complex 3a-BPh 4 were grown by slow evaporation from a THF/C 6 H 6 solution. 1 H NMR (500 MHz, THF-d 8 ): δ 7.54 (t, J H H = 8 Hz, 1H), 7.33 (m, 8H), 6.87 (t, J H H = 6.8 Hz, 8H), 6.73 (t, J H H = 6.5 Hz, 4H), 6.63 (d, J H H = 8 Hz, 2H), 1.62 (vt, J P H = 7.8 Hz, 36H). 13 C{ 1 H} NMR (125 MHz, THF-d 8 ): δ 166.2 (t, J P C = 4.0 Hz), 165.8 (q, J B C = 49.1 Hz), 150.9 (s), 137.8 (s), 126.4 (m), 122.5 (s), 106.5 (s), 42.6 (t, J P C = 4.8 Hz), 28.1 (s). 31 P{ 1 H} NMR (202 MHz, THF-d 8 ): δ 183.5 (s). Anal. Calcd (found) for C 45 H 59 BClNNiO 2 P 2 : % C, 66.49 (65.97); % H, 7.32 (7.37); % N, 1.72 (1.79). (PONOP)PtCl(BPh 4 ) (3c-BPh 4 ). In a 50 mL Schlenk flask, complex 3c (30 mg, 0.045 mmol) and 1 mL of MeOH were combined under a nitrogen atmosphere. A solution of NaBPh 4 (153 mg, 0.45 mmol) in MeOH (2 mL) was added dropwise at room temperature. The reaction mixture was stirred at room temperature for 20 min, and a colorless solid precipitated from solution. The solvent was removed by syringe, and the solid was washed 2 times with MeOH and dried under vacuum yielding pure complex 3c-BPh 4 (89%). Crystals of complex 3c-BPh 4 were grown by slow evaporation from a THF/C 6 H 6 solution. 1 H NMR (500 MHz, THF-d 8 ): δ 7.58 (t, J H H = 8 Hz, 1H), 7.34 (m, 8H), 6.88 (t, J H H = 7.3 Hz, 8H), 6.74 (m, 6H), 1.52 (vt, J P H = 8.3 Hz, 36H). 13 C{ 1 H} NMR (125 MHz, THF-d 8 ): δ 165.8 (q, J B C = 49.1 Hz), 164.2 (s), 149.6 (s), 137.8 (s), 126.4 (m), 122.5 (s), 106.7 (s), 43.1 (t, J P C = 9.2 Hz), 27.6 (s). 31 P{ 1 H} NMR (202 MHz, THF): δ 174.8 (s, J Pt P = 2535 Hz). Anal. Calcd (found) for C 51 H 65 BClNO 2 P 2 Pt: % C, 59.62 (59.94); % H, 6.38 (6.29); % N, 1.36 (1.18). (PONOP)PdCl(BPh 4 ) (3b-BPh 4 ). In a 50 mL Schlenk flask, complex 3b (30 mg, 0.051 mmol) and 1 mL of MeOH were combined under a nitrogen atmosphere. A solution of NaBPh 4 (173 mg, 0.51 mmol) in MeOH (2 mL) was added dropwise at room temperature. The reaction mixture was stirred at room temperature for 20 min, and a light yellow solid precipitated from solution. The solvent was removed by syringe, and the solid was washed 2 times with MeOH and dried under vacuum yielding pure complex 3b-BPh 4 (86%). Crystals of complex 3b-BPh 4 were grown by slow evaporation from a THF/C 6 H 6 solution. 1 H NMR (500 MHz, THF-d 8 ): δ 7.53 (t, J H H = 8.3 Hz, 1H), 7.34 (m, 8H), 6.88 (t, J H H = 7.3 Hz, 8H), 6.74 (m, 6H), 1.52 (vt, J P H = 8.5 Hz, 36H). 13 C{ 1 H} NMR (125 MHz, THF-d 8 ): δ 166.1 (q, J B C = 49.1 Hz), 164.8 (s), 150.9 (s), 138.1 (s), 126.7 (m), 122.8 (s), 107.2 (s), 43.2 (t, J P C = 5.4 Hz), 27.9 (s). 31 P{ 1 H} NMR (202 MHz, THF-d 8 ): δ 192.1 (s, J Pt P = 2535 Hz). Anal. Calcd (found) for C 51 H 65 BClNO 2 P 2 Pd: % C, 65.25 (65.05); % H, 6.98 (7.06); % N, 1.49 (1.34). Reaction Complex 5a with Different Substrates. In a J-Young tube 10 mg of complex 5a, 5 equiv of substrate (N-benzylidenemethylimine, 1-octene, t BuNC, or PhCHO), and 0.5 mL of C 6 D 6 were combined. The reactions were monitored by both 1 H and 31 P NMR spectroscopy at room temperature. In the case of gaseous substrates (CO, D 2 and ethylene), 1 atm substrate was added under the same reaction conditions. In the case of benzaldehyde, benzoin was formed, which was confirmed by 1 H NMR spectroscopy and GC-MS using an authentic sample. In the case of 1-octene after 2 days at room temperature, mostly isomerized 2-trans and 2-cis octene were observed by 1 H NMR spectroscopy. In the case of excess of t BuNC: 31 P{ 1 H} NMR (202 MHz, THF-d 8 ): δ 186.6 (s), 145.5 (s), 53.2 (s), 11.0(s). (D-PONOP)NiCl (4a-d 1 ). In a 50 mL Schlenk flask, complex 3a (20 mg, 0.038 mmol) and 10 mL of pentane were combined under a nitrogen atmosphere. A 0.038 mL portion of LiDBEt 3 (0.038 mmol, 1 M in THF) was added dropwise at room temperature. An immediate color change from red to deep green was observed. The reaction mixture was stirred at room temperature for 2 h. The solution was filtered under a nitrogen atmosphere using a cannula, and the volatiles were then removed under vacuum yielding a dark green complex 4a-d 1 (90%). 1 H NMR (400 MHz, C 6 D 6 ): δ 4.19 (2H), 3.39 (m, 1H), 1.45 (vt, J P H = 9451 dx.doi.org/10.1021/ic201102v |Inorg. Chem. 2011, 50, 9443–9453
Page 1 and 2: ARTICLE pubs.acs.org/IC Synthesis a
Page 3 and 4: Inorganic Chemistry ARTICLE Scheme
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