4. Experimental Section
General Procedures and Syntheses. One-dimensional NMR spectra were recorded at room temperature, proton and 31P NMR spectra on a Bruker Avance DRX 200 spectrometer. Additional 1D and 2D spectra were obtained for the nuclei 1H, 13C, 31P, and 19F by using a Bruker Avance DRX 500 spectrometer. The proton and carbon chemical shifts are given in ppm and referenced to the signal of residual solvent signals [46] (CDCl3: 1H 7.26 ppm, 13C 77.16 ppm; CD2Cl2: 1H 5.30 ppm, 13C 53.52 ppm; C6D6: 1H 7.16 ppm, 13C 128.1 ppm). Coupling constants are reported as absolute values and given in Hz. Infrared spectra were recorded on an FT-IR Bruker IFS 66 spectrometer. EI-MS data and FAB-MS spectra were recorded on a Finnigan MAT 8200 in a 3-nitrobenzylalcohol matrix. Elemental analyses were performed by using a Perkin-Elmer CHN-2400/II elemental analyser. GC/MS spectra were determined on a Thermo Finnigan Trace GC-Ultra Trace DSQ comprising a column of 15 m length with 0.25 mm in diameter and a DB5MS phase. Injection temperature was 220°C, and column temperature increased starting at 50 up to 250°C with 20°C min−1. The intensity of the signal in the gas chromatogram is listed as % area. Unless stated otherwise chemicals were purchased from commercial sources, used as received and dried and degassed by standard methods. The synthesis of the protonated N,O-chelate ligand 4,4,5,5,6,6,6-heptafluoro-3-oxo-2-[pyrrolidin-(2Z)-ylidene]hexanenitrile (HL) was reported previously [27].
n-Butyldiphenylphosphane. The synthesis was carried out according to the literature [47] using chlorodiphenylphosphane (3.7 mL, 20 mmol) and n-butyllithium (13.8 mL, 1.6 M solution in hexane). The reaction mixture was worked up as follows: after hydrolysis with half concentrated ammonia (100 mL), the organic layer was extracted with deionized water (3 × 50 mL) and dried over MgSO4. The solvent was removed in vacuo yielding 4.6 g (95%) of a colourless liquid. 1H NMR (200 MHz, CDCl3): 0.89 (t, 3H, PCH2CH2CH2CH3), 1.44 (mult, 4H, PCH2CH2CH2CH3), 2.06 (t, 2H, PCH2CH2CH2CH3), 7.28 (mult, 6H, m,p-CH Ph), 7.43 (mult, 4H, o-CH Ph) ppm. 1H NMR (200 MHz, C6D6): 0.77 (t, 3H, PCH2CH2CH2CH3), 1.32 (mult, 2H, PCH2CH2CH2CH3), 1.41 (mult, 2H, PCH2CH2CH2CH3), 1.95 (t, 2H, PCH2CH2CH2CH3), 7.10 (mult, 6H, m,p-CH Ph), 7.43 (mult, 4H, o-CH Ph) ppm. 31P{1H} NMR (81 MHz, CDCl3): δ = −14.8 ppm.
Di-n-butylphenylphosphane. The synthesis [47] was carried out as for n-butyldiphenylphosphane, except that dichlorophenylphosphane (3.58 g, 20.0 mmol) and n-butyllithium (26.3 mL) were used. Yield: 4.0 g (90%). 1H NMR (200 MHz, CDCl3): 0.88 (t, 6H, PCH2CH2CH2CH3), 1.37 (mult, 8H, PCH2CH2CH2CH3), 1.69 (mult, 4H, CH2CH2CH2CH3), 7.35 (mult, 3H, m,p-CH Ph), 7.72 (mult, 2H, o-CH Ph) ppm. 31P{1H} NMR (81 MHz, CDCl3): −23.1 ppm.
Cyclohexyldiphenylphosphane. Chlorodiphenylphosphane (3.05 mL, 17.0 mmol) was dissolved in tetrahydrofuran (15 mL). Cyclohexane magnesium bromide, prepared from Mg turnings (0.56 g, 23 mmol) and bromocyclohexane (3.75 g, 230 mmol) in tetrahydrofuran (30 mL), was added by means of a syringe and the reaction mixture stirred overnight. After hydrolysis with bidistilled water (22 mL) the solution was extracted with diethyl ether (5 × 50 mL) and dried over Na2SO4. The solvent was removed in vacuo and the remaining white solid was dried yielding 4.4 g (96%) of cyclohexyldiphenylphosphane. 1H NMR (200 MHz, C6D6): δ = 1.16 (mult, 6H, C3H2 and C4H2 Cy), 1.60 (mult, 4H, C2H2 Cy), 2.15 (mult, 1H, P-C1H), 7.08 (mult, 6H, m,p-CH Ph), 7.55 (mult, 4H, o-CH Ph) ppm. 31P{1H} NMR (81 MHz, C6D6): δ = −2.6 ppm.
General Procedure for the Synthesis of [NiBr2(PRaRbRc)2]. Based on a modified literature procedure [39], anhydrous nickel dibromide (1.64 g, 7.50 mmol) was dissolved in tetrahydrofuran (70 mL). The P-ligand (15 mmol) was added and the reaction mixture heated to reflux for several hours. After removing the solvent, the remaining solid was dried in vacuo, but usually it was used directly for the reaction with the Grignard reagent.
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(3a). Dark green solid. IR (KBr disk): ν~=3072, 3048 (νC–H aromatic, w), 2959, 2922, 2872, 2854 (νC–H aliphatic, m), 1463, 1433, 1408, 1380 (δC–H aliphatic, s), 1098 (νP–C, m), 744, 720 (δC–H aromatic, s) cm−1. MS (EI): m/z (%) = 242 ([P(nBu)Ph2]+, 33), 200 ([PCH3Ph2]+, 39), 199 ([PCH2Ph2]+, 91), 185 ([PPh2]+, 15), 183 ([M-C20H30PBr2Ni]+, 100), 152 (17), 121 (22), 109 (40), 108 ([PPh]+, 54), 107 (46), 77 ([Ph]+, 19), 57 ([nBu]+, 8).
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(4a). Dark brown solid. IR (KBr disk): ν~=3073, 3056, 3005 (νC–H aromatic, w), 2956, 2927, 2867 (νC–H aliphatic, vs), 1461, 1434, 1401, 1374 (δC–H aliphatic, s), 1092 (νP–C, s), 739, 711 (δC–H aromatic, m) cm−1. MS (EI): m/z (%) = 222 ([P(nBu)2Ph]+, 22), 193 (21), 166 ([HP(nBu)Ph]+, 16), 138 ([PC2H6Ph]+, 100), 109 ([HPPh]+, 63), 91 (34), 77 ([Ph]+, 6), 57 ([nBu]+, 5).
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(5a). Dark purple solid. 1H NMR (200 MHz, CDCl3): δ = 0.95 (t, 18H, CH2CH2CH2CH3), 1.50 (m, 12H, CH2CH2CH2CH3), 1.66 (m, 12H, CH2CH2CH2CH3), 1.90 (m, 12H, CH2CH2CH2CH3) ppm. IR (KBr disk): ν~=2958, 2927, 2869 (νC–H aliphatic, s), 1463, 1412, 1378 (δC–H aliphatic, m), 800 (νP–C, vs) cm−1. MS (ESI): m/z (%) = 543 ([M-Br]+, 6%), 340 ([M-Br-P(nBu)3]+, 2), 283 ([M-C16H36PBr]+, 13), 227 ([M-C20H45PBr]+, 4), 203 ([HP(nBu)3]+, 100), 147 ([M-C20H45PBr2]+, 13). MS (EI): m/z (%) = 283 ([81Br–P(nBu)3]+, 11), 281 ([79Br–P(nBu)3]+, 11), 202 ([P(nBu)3]+, 7), 173 ([M-C14H32PBr2]+, 18), 131 (13), 118 (20), 104 (23), 89 ([HP(nBu)]+, 16), 76 ([PC3H9]+, 100), 62 ([PC2H7]+, 59), 61 ([PC2H6]+, 46), 57 ([nBu]+, 11).
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(6a). Dark purple solid. 1H NMR (200 MHz, CDCl3): 1.43 (mult, 18H, CH3), 4.36 (mult, 12H, CH2) ppm. IR (KBr disk): ν~=2983, 2931, 2906 (νC–H aliphatic, m), 1477, 1442, 1392 (δC–H aliphatic, m), 1025, 783 (νP–O–C, vs) cm−1. MS (MALDI): m/z (%) = 507, 509, 511 ([M-C2HO]+, isotope pattern of 58Ni, 60Ni, 79Br and 81Br clearly identifiable), 391 ([M-Br2]+).
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(7a).This compound was synthesized according to the general procedure described above, except that PCyPh2 was dissolved before adding it to the NiBr2 solution. The complex can be isolated as a dark green solid. IR (KBr disk): ν~=3052 (νC–H aromatic, w), 2926, 2851 (νC–H aliphatic, vs), 1436, 1384 (δC–H aliphatic, s), 1096 (νP–C, m), 737, 723 (δC–H aromatic, s) cm−1.
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(8a).This compound was synthesized according to the general procedure described above, except that the synthesis was carried out in ethanol and PCy3 was dissolved before adding it to the NiBr2 solution. Upon refluxing the product precipitated, the brown solid was stirred in diethylether. IR (KBr disk): ν~=2925, 2845 (νC–H aliphatic, vs), 1442 (δC–H aliphatic, m), 731 (νP–C, m) cm−1. MS (ESI, thf): m/z (%) = 668, 669, 670, 671 ([M-C8H14]+, 21, isotope pattern of 58Ni, 60Ni, 79Br and 81Br clearly identifiable), 500, 502 ([M-C6H15PBr2]+, 100, isotope pattern of 58Ni and 60Ni clearly identifiable). MS (MALDI): m/z (%) = 505, 507 ([M-C6H11PBr2]+, isotope pattern of 58Ni and 60Ni), 281 ([HPCy3]+). C36H66P2Br2Ni (779.37): calcd. C 55.48, H 8.55; found C 55.6, H 8.6.
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(9a).Red-brown gel-like solid. Letting the reaction solution stand for several weeks leads to very few red-brown crystals which were analysed by IR spectroscopy. IR (KBr plates, paraffin oil): ν~=1619 (νC–C aromatic, w), 1237 (νC–O, w), 873 (νP–O, m), 724 (δC–H aromatic, w) cm−1.
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(3b). Anhydrous nickel dibromide (1.64 g, 7.50 mmol) was dissolved in tetrahydrofuran (70 mL). n-Butyldiphenylphosphane (3.6 g, 15 mmol) was added and the reaction mixture was heated to reflux for two to three hours. Upon cooling to room temperature, mesitylenido magnesium bromide, prepared from Mg (0.24 g, 10 mmol) and 2-bromomesitylene (2.0 g, 10 mmol) in tetrahydrofuran (20 mL), was added by means of a syringe. After stirring over night at room temperature, the solvent was removed in vacuo and the mixture quenched with methanol (100 mL). After removing the methanol in vacuo, the solid was treated with dichloromethane, filtered and the solvent again removed in vacuo yielding 0.58 g (40%) of a brown solid. 1H NMR (200 MHz, CDCl3): δ = 0.68 (t, 6H, CH3 Bu), 0.88–1.12 (m, 12H, CH2 Bu), 1.98 (s, 3H, p-CH3 Mes), 2.48 (s, 6H, o-CH3 Mes), 6.09 (s, 2H, CH Mes), 7.21 (m, 12H, CH Ph), 7.55 (m, 8H, CH Ph) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 14.0 (PCH2CH2CH2CH3), 20.8 (p-CH3 Mes), 25.0 (PCH2CH2CH2CH3), 26.8 (o-CH3 Mes), 27.6 (PCH2CH2CH2CH3), 27.8 (PCH2CH2CH2CH3), 127.4 (CH Mes), 129.8 (m-CH PPh2), 131.7 (p-CH PPh2), 132.8 (p-C Mes), 134.1 (i-C PPh2), 134.7 (o-CH PPh2), 142.6 (d, 3JCP =3.9 Hz, o-C Mes), 146.3 (d, 2JCP =32.8 Hz, i-C Mes) ppm. 31P{1H} NMR (81 MHz, CDCl3): δ = 14.1 ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 14.5 ppm. IR (KBr disk): ν~=3051, 3003 (νC–H aromatic, w), 2955, 2928, 2869 (νC–H aliphatic, m), 1459, 1433, 1376, 1307 (δC–H aliphatic, s), 800 (νP–C, w), 742, 713 (δC–H aromatic, vs) cm−1. MS (MALDI): m/z (%) = 461, 361 ([Mes–P(nBu)Ph2]+, 100%), 340. This compound was used without further purification.
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(4b).The synthesis was carried out as for 3b, except that di-n-butylphenylphosphane (3.3 g, 15 mmol) was used. Yield: 1.4 g (27%). 1H NMR (200 MHz, CDCl3): δ = 0.79 (t, 12H, CH3 Bu), 1.24–1.49 (m, 24H, CH2 Bu), 2.08 (s, 3H, p-CH3 Mes), 2.46 (s, 6H, o-CH3 Mes), 6.29 (s, 2H, CH Mes), 7.22 (m, 6H, CH Ph), 7.32 (m, 4H, CH Ph) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 14.1 (PCH2CH2CH2CH3), 21.0 (p-CH3 Mes), 24.0 (PCH2CH2CH2CH3), 25.1 (PCH2CH2CH2CH3), 26.6 (o-CH3 Mes), 26.9 (PCH2CH2CH2CH3), 127.1 (CH Mes), 129.3 (m-CH PPh), 132.1 (p-C Mes), 132.4 (o-CH PPh), 132.8 (p-CH PPh), 134.0 (i-C PPh), 142.7 (t, 3JCP = 3.9 Hz, o-C Mes), 146.0 (t, 2JCP = 32.8 Hz, i-C Mes) ppm. 31P{1H} NMR (81 MHz, CDCl3): δ = 5.7 ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 6.5 ppm. IR (KBr disk): ν~=3077, 3054 (νC–H aromatic, w), 2956, 2928, 2870 (νC–H aliphatic, vs), 1461, 1434, 1379, 1342, 1303 (νC–H aliphatic, s), 799 (νP–C, w), 740, 711 (δC–H aromatic, vs) cm−1. MS (MALDI): m/z (%) = 701 ([M]+), 621 ([M-Br]+), 566 ([M-(nBu)-Ph]+), 510 ([M-2(nBu)-Ph]+), 490 ([M-(nBu)-2Ph]+), 431 ([M-Br-2(nBu)-Ph]+), 400 ([M-Br-P(nBu)2Ph]+), 341 ([Mes–P(nBu)2Ph]+, 100%). This compound was used without further purification.
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(5b).The synthesis was carried out as for 3b, except that tri-n-butylphenylphosphane (3.0 g, 15 mmol) was used. Yield: 3.6 g (72%). 1H NMR (200 MHz, CDCl3): δ = 0.81 (t, 18H, CH3 Bu), 1.20–1.40 (m, 36H, CH2 Bu), 2.10 (s, 3H, p-CH3 Mes), 2.82 (s, 6H, o-CH3 Mes), 6.41 (s, 2H, CH Mes) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 14.2 (PCH2CH2CH2CH3), 21.0 (p-CH3 Mes), 24.8 (PCH2CH2CH2CH3), 25.5 (PCH2CH2CH2CH3), 27.0 (o-CH3 Mes), 27.2 (PCH2CH2CH2CH3), 126.7 (CH Mes), 132.6 (p-C Mes), 142.2 (t, 3JCP = 3.9 Hz, o-C Mes), 147.1 (t, 2JCP = 32.8 Hz, i-C Mes) ppm. 31P{1H} NMR (81 MHz, CDCl3): δ = 2.6 ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 3.5 ppm. IR (KBr disk): ν~=2956, 2927, 2869 (νC–H aliphatic, vs), 1463, 1377, 1341, 1300 (δC–H aliphatic, s), 796 (νP–C, m) cm−1. MS (EI): m/z (%) = 322 (35), 321 ([Mes–P(nBu)3]+, 100), 202 ([P(nBu)3]+, 13), 173 (20), 119 ([Mes]+, 11), 104 (28), 89 ([HP(nBu)]+, 14), 76 (88), 57 ([nBu]+, 10). MS (MALDI): m/z (%) = 490 ([M-C12H27]+), 485 ([M-Mes-(nBu)]+), 321 ([Mes–P(nBu)3]+, 100%). This compound was used without further purification.
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(6b).Triethylphosphite (3.32 g, 20.0 mmol) was added to anhydrous nickel dibromide (2.19 g, 10.0 mmol), whereupon the dark violet complex 6a directly forms. The reaction mixture was dissolved in tetrahydrofuran and heated to reflux for several hours. Upon cooling to room temperature, mesitylenido magnesium bromide, prepared from Mg (0.24 g, 10 mmol) and 2-bromomesitylene (2.0 g, 10 mmol) in tetrahydrofuran (20 mL), was added by means of a syringe. After stirring over night at room temperature, the solvent was removed in vacuo and the mixture quenched with methanol (50 mL). Undissolved solid was filtered off and the solvent removed in vacuo. The remaining solid was dissolved in toluene (100 mL) and again undissolved solid was filtered off. After removing the toluene in vacuo the orange solid was recrystallized from methanol. Orange needle-like crystals were obtained at −6°C yielding 3.7 g (62%). 1H NMR (200 MHz, C6D6): δ = 1.03 (t, 18H, OCH2CH3), 2.27 (s, 3H, p-CH3 Mes), 3.11 (s, 6H, o-CH3 Mes), 4.04 (mult, 12H, OCH2CH3), 6.69 (s, 2H, CH Mes) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 16.7 (OCH2CH3), 21.1 (p-CH3 Mes), 26.2 (o-CH3 Mes), 62.1 (OCH2CH3), 126.6 (CH Mes), 132.6 (p-C Mes), 143.5 (o-C Mes) ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 111.2 ppm. IR (KBr disk): ν~=2980, 2929, 2901 (νC–H aliphatic, m), 1475, 1442, 1388 (δC–H aliphatic, w), 1031, 780, 740 (νP–O–C, vs) cm−1. MS (ESI, CH3OH/HCOOH): m/z (%) = 285 ([Mes–P(OEt)3]+, 6%), 214 (23), 201 (100), 183 (47), 166 ([P(OEt)3]+, 4), 158 (27), 121 (55), 119 ([Mes]+, 51), 95 (31). C21H41BrO6P2Ni (590.21): calcd. C 42.73, H 7.02; found C 42.5, H 7.0.
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(7b). Anhydrous nickel dibromide (1.10 g, 5.00 mmol) was dissolved in ethanol (100 mL). In a separate flask cyclohexyldiphenylphosphane (2.72 g, 10.1 mmol) was dissolved in ethanol (80 mL), this solution was added to the first solution by means of a syringe, and the reaction mixture was heated to reflux for 40 minutes. Upon cooling to room temperature, mesitylenido magnesium bromide, prepared from Mg (0.24 g, 10 mmol) and 2-bromomesitylene (2.0 g, 10 mmol) in tetrahydrofuran (20 mL), was added by means of a syringe. After stirring over night at room temperature the solvent was removed in vacuo and the mixture quenched with methanol (100 mL). The resulting yellow solid was separated from the solution in the centrifuge and dried in vacuo to yield 0.79 g (20%). 1H NMR (200 MHz, C6D6): δ = 0.81–1.10 (mult, 12H, CH2 Cy), 1.48 (mult, 8H, CH2 Cy), 2.07 (s, 3H, p-CH3 Mes), 2.20 (mult, 2H, P-CH Cy), 2.90 (s, 6H, o-CH3 Mes), 6.08 (s, 2H, CH Mes), 7.00 (mult, 12H, CH Ph), 7.74 (mult, 8H, CH Ph) ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 21.1 ppm. IR (KBr disk): ν~=3050 (νC–H aromatic, w), 2927, 2851, 2799 (νC–H aliphatic, m), 1482 (νC–C aromatic, w), 1435, 1384 (δC–H aliphatic, w), 1090 (νP–C, vs), 741, 723 (δC–H aromatic, w) cm−1. This compound was used without further purification.
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(K3). 4,4,5,5,6,6,6-Heptafluoro-3-oxo-2-[pyrrolidin-(2Z)-ylidene]hexanenitrile (HL, 0.61 g, 2.0 mmol) was dissolved in toluene (15 mL), sodium bis(trimethylsilyl)amide (0.6 M in toluene, 3.3 mL, 2.0 mmol) was added, and the mixture was stirred. The deprotonated ligand was added by means of a syringe to a solution of the [NiBrMes(PnBuPh2)2] complex 3b (1.50 g,2.00 mmol) in toluene (200 mL) and the reaction mixture stirred overnight. After filtration of the solution over Celite, the solvent was removed in vacuo and the complex purified via column chromatography on neutral alumina. Elution with n-hexane yielded triphenylphosphane, and the complex was subsequently eluted with diethylether yielding 0.58 g of a yellow solid (40%). 1H NMR (200 MHz, C6D6): δ = 0.58 (t, 3H, CH3 Bu), 0.83 (mult, 2H, CH2CH2CH2N), 0.93 (mult, 2H, CH2 Bu), 1.05 (mult, 2H, CH2 Bu), 1.55 (q, 2H, CH2 Bu), 2.18 (s, 3H, p-CH3 Mes), 2.36 (t, 2H, CH2CH2CH2N), 2.60 (t, 2H, CH2CH2CH2N), 2.89 (s, 6H, o-CH3 Mes), 6.47 (s, 2H, CH Mes), 7.05 (mult, 6H, CH PPh2), 7.51 (mult, 4H, CH PPh2) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 13.4 (PCH2CH2CH2CH3), 20.3 (CH2CH2CH2N), 20.6 (p-CH3 Mes), 24.4 (d, 3JCP = 13 Hz, PCH2CH2CH2CH3), 25.0 (d, 1JCP = 29 Hz, PCH2CH2CH2CH3), 25.8 (o-CH3 Mes), 26.1 (d, 2JCP = 3.8 Hz, PCH2CH2CH2CH3), 38.8 (CH2CH2CH2N), 63.2 (CH2CH2CH2N), 83.9 (C=C–CN), 126.7 (d, 4JCP = 2.5 Hz, CH Mes), 130.1 (d, 3JCP = 2.5 Hz, m-CH PPh2), 131.0 (d, 1JCP = 39 Hz, i-C PPh2), 133.3 (d, 2JCP = 10 Hz, o-CH PPh2), 141.9 (d, 3JCP = 2.5 Hz, o-C Mes), 142.5 (d, 2JCP = 48 Hz, i-C Mes), 165.9 (CO), 172.1 (C=C–CN) ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 18.9 ppm. 19F NMR (471 MHz, C6D6): δ = −80.91 (t, CF2CF2CF3), −114.93 (q, CF2CF2CF3), −125.36 (t, CF2CF2CF3) ppm. IR (KBr disk): ν~=3060 (νC–H aromatic, w), 2960, 2872 (νC–H aliphatic, m), 2218 (νC≡N, s), 1591 (νC=O, vs), 1517 (νC–C aromatic, s), 1434 (δC–H aliphatic, s), 1270, 1229, 1197 (νC–F, vs), 1112 (νP–C, m), 749 (δC–H aromatic, m) cm−1. MS (ESI, CH3OH): m/z (%) = 361 ([Mes–P(nBu)Ph2]+, 100%), 303 (N,O-ligand: [C10H6N2OF7]+, 38), 263 ([HPPh3]+, 4), 249 (9), 193 (8), 114 (8), 85 (21). MS (MALDI): m/z (%) = 619 ([M-C7H5N]+), 563 ([M-C11H13N]+), 361 ([Mes–P(nBu)Ph2]+, 100%). C35H36F7N2OPNi (723.37): calcd. C 58.11, H 5.03, N 3.87; found C 57.9, H 5.3, N 3.7.
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(K4). The synthesis was carried out as for K3, except that the [NiBrMes(PnBu2Ph)2] complex 4b (1.41 g, 2.00 mmol) was used. Yield: 0.1 g (9%). 1H NMR (200 MHz, C6D6): δ = 0.76 (t, 6H, CH3 Bu), 0.89 (mult, 2H, CH2CH2CH2N), 1.19–1.47 (mult, 12H, CH2 Bu), 2.23 (s, 3H, p-CH3 Mes), 2.33 (t, 2H, CH2CH2CH2N), 2.58 (t, 2H, CH2CH2CH2N), 2.87 (s, 6H, o-CH3 Mes), 6.57 (s, 2H, CH Mes), 7.08 (mult, 3H, CH Ph), 7.37 (mult, 2H, CH Ph) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 14.0 (PCH2CH2CH2CH3), 20.6 (CH2CH2CH2N), 21.0 (p-CH3 Mes), 21.7 (d, 1JCP = 25 Hz, PCH2CH2CH2CH3), 25.0 (d, 3JCP = 14 Hz, PCH2CH2CH2CH3), 26.1 (o-CH3 Mes), 26.2 (PCH2CH2CH2CH3), 39.1 (CH2CH2CH2N), 63.4 (CH2CH2CH2N), 84.5 (C=C–CN), 126.9 (d, 4JCP = 2.5 Hz, CH Mes), 130.1 (m-CH PPh), 131.7 (d, 2JCP = 8 Hz, o-CH PPh), 132.5 (d, 1JCP = 38 Hz, i-C PPh), 133.6 (p-CH PPh), 142.5 (d, 3JCP = 1.3 Hz, o-C Mes), 142.9 (d, 2JCP = 47 Hz, i-C Mes), 166.0 (t, 2JFC = 23 Hz, CO), 172.1 (C=C–CN) ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 11.9 ppm. 19F NMR (471 MHz, C6D6): δ = −80.80 (t, CF2CF2CF3), −115.15 (q, CF2CF2CF3), −125.68 (t, CF2CF2CF3) ppm. IR (KBr disk): ν~=2959, 2931, 2872 (νC–H aliphatic, s), 2214 (νC≡N, s), 1587 (νC=O, vs), 1514 (νC–C aromatic, s), 1450, 1435, 1379 (δC–H aliphatic, s), 1260, 1230, 1185 (νC–F, vs), 1113 (νP–C, s), 749 (δC–H aromatic, m) cm−1. MS (EI): m/z (%) = 703 ([M]∙+, 0.3%), 702 ([M-H]+, 0.5), 363 ([M-Mes-P(nBu)2Ph]+, 1), 342 ([M-C14H15N2OF7]+, 46), 341 ([Mes–P(nBu)2Ph]+, 100), 241 (7), 222 ([P(nBu)2Ph]+, 3), 192 (7), 138 (17), 109 (16).
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(K5). The [Ni(L)MesPPh3] complex K2 (0.78 g, 1.0 mmol) was dissolved in toluene p.a. (40 mL), and tri-n-butylphosphane (0.40 g, 2.0 mmol) was added. The mixture was stirred for 6 days at room temperature and the substitution of the phosphane monitored with 31P{1H} NMR spectroscopy. After complete substitution, the solvent was removed in vacuo and the complex purified via column chromatography on neutral alumina. Elution with n-hexane first yielded triphenylphosphane and then the complex which was recrystallized from n-pentane yielding 0.24 g red-brown crystals (35%). 1H NMR (500 MHz, C6D6): δ = 0.82 (t, 11H, CH3 Bu and CH2CH2CH2N), 1.19 (mult, 14H, CH2 Bu), 1.31 (mult, 7H, CH2 Bu), 2.23 (s, 3H, p-CH3 Mes), 2.32 (t, 2H, CH2CH2CH2N), 2.57 (t, 2H, CH2CH2CH2N), 3.03 (s, 6H, o-CH3 Mes), 6.60 (s, 2H, CH Mes) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 14.1 (PCH2CH2CH2CH3), 20.6 (p-CH3 Mes), 21.0 (CH2CH2CH2N), 23.4 (d, 1JCP = 24 Hz, PCH2CH2CH2CH3), 25.3 (d, 3JCP = 13 Hz, PCH2CH2CH2CH3), 26.2 (o-CH3 Mes), 26.6 (PCH2CH2CH2CH3), 39.2 (CH2CH2CH2N), 63.3 (CH2CH2CH2N), 84.3 (C=C–CN), 117.3 (CN), 126.8 (CH Mes), 133.5 (d, 5JCP = 2.5 Hz, p-C Mes), 142.1 (d, 3JCP = 2.5 Hz, o-C Mes), 143.5 (d, 2JCP = 48 Hz, i-C Mes), 166.0 (CO), 172.1 (C=C–CN) ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 10.4 ppm. 19F NMR (471 MHz, C6D6): δ = −80.87 (t, CF2CF2CF3), −115.14 (mult, CF2CF2CF3), −125.59 (t, CF2CF2CF3) ppm. IR (KBr disk): ν~=3174 (νC–H aromatic, w), 2961, 2930, 2873 (νC–H aliphatic, s), 2211 (νC≡N, m), 1589 (νC=O, s), 1522 (νC–C aromatic, s), 1464, 1435, 1378 (δC–H aliphatic, m), 1261, 1233, 1195 (νC–F, vs) cm−1. MS (EI): m/z (%) = 683 ([M]∙+, 0.3%), 323 (33), 322 ([M-C14H15N2OF7]+, 15), 321 ([Mes–P(nBu)3]+, 100), 192 (8), 119 ([Mes]+, 8), 76 (10). C31H44F7N2OPNi (683.35): calcd. C 54.48, H 6.50, N 4.10; found C 54.5, H 6.7, N 4.0.
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(K6). The [NiBrMes(P(OEt)3)2] complex 6b (0.53 g, 0.90 mmol) was dissolved in toluene (30 mL). 4,4,5,5,6,6,6-Heptafluoro-3-oxo-2-[pyrrolidin-(2Z)-ylidene]hexanenitrile HL (0.27 g, 0.90 mmol) and sodium bis(trimethylsilyl)amide (0.6 M in toluene, 1.62 mL, 1.0 mmol) were added. The mixture was stirred for 2 h. After filtration over Celite and removal of the solvent in vacuo, the solid was recrystallized from methanol. Crystals suitable for X-ray analysis were obtained at −6°C. Yield: 0.21 g of orange crystals (36%). 1H NMR (200 MHz, C6D6): δ = 0.79 (p, 2H, CH2CH2CH2N), 0.94 (t, 9H, OCH2CH3), 2.22 (s, 3H, p-CH3 Mes), 2.34 (t, 2H, CH2CH2CH2N), 2.55 (t, 2H, CH2CH2CH2N), 3.03 (s, 6H, o-CH3 Mes), 3.71 (q, 6H, OCH2CH3), 6.63 (s, 2H, CH Mes) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 16.0 (d, 3JCP = 6,3 Hz, OCH2CH3), 20.1 (CH2CH2CH2N), 20.7 (p-CH3 Mes), 25.6 (o-CH3 Mes), 38.9 (d, J = 6.3 Hz, CH2CH2CH2N), 61.3 (d, 2JCP = 5.0 Hz, OCH2CH3), 62.5 (CH2CH2CH2N), 83.6 (C=C–CN), 126.4 (d, 4JCP = 3.8 Hz, CH Mes), 133.4 (d, 5JCP = 1.3 Hz, p-C Mes), 141.2 (d, 2JCP = 65.5 Hz, i-C Mes), 142.7 (d, 3JCP = 2.5 Hz, o-C Mes), 166.4 (t, 2JFC = 23.9 Hz, CO), 172.6 (C=C–CN) ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 105.0 ppm. 19F NMR (471 MHz, C6D6): δ = −80.93 (t, CF2CF2CF3), −115.07 (mult, CF2CF2CF3), −125.94 (t, CF2CF2CF3) ppm. IR (KBr disk): ν~=2986, 2938, 2908 (νC–H aliphatic, m), 2213 (νC≡N, m), 1592 (νC=O, vs), 1517 (νC–C aromatic, s), 1436 (δC–H aliphatic, m), 1275, 1229, 1194 (νC–F, vs), 1024, 777, 740 (νP–O–C, vs) cm−1. MS (ESI): m/z (%) = 670 ([M+Na]+, 85%), 647 ([M]∙+, 28), 545 (50), 480 ([M-P(OEt)3]+, 8), 285 ([Mes–P(OEt)3]+, 100), 201 (45). C25H32F7N2O4PNi (647.26): calcd. C 46.39, H 4.99, N 4.33; found C 46.1, H 5.0, N 4.3.
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(K7). The [NiBrMes(PCyPh2)2] complex 7b (0.79 g, 1.0 mmol) and 4,4,5,5,6,6,6-heptafluoro-3-oxo-2-[pyrrolidin-(2Z)-ylidene]hexanenitrile HL (0.30 g, 1.0 mmol) were dissolved in toluene (60 mL). Sodium bis(trimethylsilyl)amide (0.6 M in toluene, 1.8 mL, 1.1 mmol) was added and the mixture was stirred for 3 days. After filtration over Celite and removal of the solvent in vacuo, the solid was stirred in methanol (50 mL). After removing remaining solid with the centrifuge, the solvent was removed in vacuo and the solid dried in vacuo. The solid was stirred in hexane (40 mL) for one day. After filtration of undissolved solid, the solvent was removed in vacuo and the resulting oil recrystallized from methanol. Crystals suitable for X-ray analysis were obtained at −30°C. Yield: 0.20 g dark brown needle-like crystals (27%). 1H NMR (200 MHz, C6D6): δ = 0.83 (mult, 2H, CH2CH2CH2N), 0.92–1.04 (mult, 5H, CH2 Cy), 1.48–1.55 (mult, 5H, CH2 Cy), 2.11 (s, 3H, p-CH3 Mes), 2.14 (m, 1H, P–C1H Cy), 2.37 (t, 2H, CH2CH2CH2N), 2.57 (t, 2H, CH2CH2CH2N), 2.90 (s, 6H, o-CH3 Mes), 6.27 (s, 2H, CH Mes), 7.00 (mult, 6H, CH PPh2), 7.53 (mult, 4H, o-CH PPh2) ppm. 13C{1H} NMR (126 MHz, C6D6): δ = 20.6 (CH2CH2CH2N), 20.7 (p-CH3 Mes), 26.4 (o-CH3 Mes), 26.7 (C4H2 Cy), 27.9 (d, 2JCP= 11 Hz, C2H2 Cy), 29.3 (C3H2 Cy), 37.3 (d, 1JCP = 19 Hz, P–C1H Cy), 39.3 (CH2CH2CH2N), 63.7 (CH2CH2CH2N), 84.5 (C=C–CN), 117.3 (CN), 127.0 (d, 4JCP = 2.5 Hz, CH Mes), 130.2 (m-CH PPh2), 130.7 (d, 1JCP = 40 Hz, i-C PPh2), 133.4 (p-CH PPh2), 134.7 (d, 2JCP = 9 Hz, o-CH PPh2), 141.8 (d, 3JCP = 2.5 Hz, o-C Mes), 142.9 (d, 2JCP = 44 Hz, i-C Mes), 166.0 (CO), 172.5 (C=C–CN) ppm. 31P{1H} NMR (81 MHz, C6D6): δ = 27.9 ppm. 19F NMR (471 MHz, C6D6): δ = −80.82 (t, CF2CF2CF3), −114.53 (mult, CF2CF2CF3), −125.03 (t, CF2CF2CF3) ppm. IR (KBr disk): ν~=3082, 3057 (νC–H aromatic, w), 2934, 2854 (νC–H aliphatic, s), 2211 (νC≡N, m), 1588 (νC=O, vs), 1515, 1484 (νC–C aromatic, vs), 1433 (δC–H aliphatic, s), 1266, 1231, 1193 (νC–F, vs), 1110 (νP–C, m), 750, 736 (δC–H aromatic, m) cm−1. MS (EI): m/z (%) = 748 ([M]∙+, 2%), 387 ([Mes–PCyPh2]+, 100), 268 ([PCyPh2]+, 64), 186 (47), 183 (29), 108 (49). MS (ESI, CH3OH/H2O): m/z (%) = 771 ([M+Na]+, 3%), 629 ([M-Mes]+, 6), ([Mes–PCyPh2]+, 44), 305 ([C10H8N2OF7]+, 100). C37H38F7N2OPNi (748.20): calcd. C 59.39, H 5.13, N 3.74; found C 59.4, H 5.1, N 3.5.
4.1. Crystal Structure Determinations
Crystals of complexes K5, K6, and K7 suitable for X-ray study were selected by means of a polarization microscope and investigated with a STOE Imaging Plate Diffraction System, using graphite monochromatized MoKα radiation (λ = 0.71073 Å). Unit cell parameters were determined by least-squares refinements on the positions of 8000 reflections, in the θ range 2.1° to 25.1°, 2.25° to 25.95°, and 2.0° to 25.65°, respectively. Space group type no. 14 was uniquely determined for K5. For K6 and K7 triclinic symmetry was found consistent with space group types P1 and P1-. In accordance with E-statistics for both compounds significantly better results were observed with structural models in the centrosymmetric space group type in the course of structure refinements, taking into account a 1 : 1 conformational disorder of the ethoxy groups of the phosphite ligand in the case of K6. Corrections for Lorentz and polarization effects were applied. The structures were solved by direct methods [48] and subsequent ΔF-syntheses. Approximate positions of all but the hydrogen atoms of the disordered ethoxy groups of K6 and of the conformational disordered butyl groups of the tributylphosphane ligand of K5 were found in different stages of converging refinements by full-matrix least-squares calculations on F2 [49]. Anisotropic displacement parameters were refined for all atoms heavier than hydrogen. With idealized bond lengths and angles assumed for all the CH, CH2, and CH3 groups, the riding model was applied for the corresponding H atoms and their isotropic displacement parameters were constrained to 120%, 120%, and 150% of the equivalent isotropic displacement parameters of the parent carbon atoms, respectively. In addition, the H atoms of the CH3 groups (with the exception of those within the phosphane butyl groups of K5) were allowed to rotate around the neighbouring C–C bonds. Appropriate same distance and anisotropic displacement restraints had to be applied for the disordered carbon atoms of K5 and for the atoms of the C3F7 groups of K5 and K6. CCDC-885214 (K5), CCDC-885215 (K6), and CCDC-885216 (K7) contain the supplementary crystallographic data (excluding structure factors) for this paper. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/data_request/cif.
4.2. Catalysis Experiments
General Procedure. 20 mg of the catalyst complex were dissolved in toluene (10 mL) in a 100 mL steel autoclave with glass inlet under nitrogen atmosphere. Ethene (40 bar) and carbon monoxide (10 bar) were added and the reaction mixture was stirred for 20 h at 60°C. The weight of the autoclave was measured before and after adding the gases to determine the mass of the gases. Potentially resulting solid was separated, washed with methanol, dried in vacuo, and characterized by IR spectroscopy. The remaining solution was analysed with GC/MS spectrometry.
Catalysis Experiment with
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K3. Result: colourless, slightly cloudy solution. GC/MS: 10.8 min (n-butyldiphenylphosphane oxide, 64%), 11.0 min (mesitylaldehyde, 10%).
n-Butyldiphenylphosphane Oxide. Retention time: 10.8 min; MS (EI): m/z = 258 (fragment, relative intensity) ([M]∙+, 5%), 229 ([C2H5]+, 10), 216 ([M-C3H6]∙+, 54), 215 ([M-C3H7]+, 100), 201 ([M-C4H9]+, 28), 155 (8), 125 ([M-C10H13]+, 8), 77 (Ph, 8).
Mesitylaldehyde. Retention time: 11.0 min; MS (EI): m/z = 148 (fragment, relative intensity) ([M]∙+, 11%), 147 ([M-H]+, 100), 119 ([M-CHO]+, 10).
Catalysis Experiment with
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K5. Result: colourless, slightly cloudy solution. GC/MS: 8.2 min (tri-n-butylphosphane oxide, 33%), 11.0 min (mesitylaldehyde, 15%).
Tri-n-butylphosphane Oxide. Retention time: 8.2 min; MS (EI): m/z = 218 (fragment, relative intensity) ([M]∙+, 11%), 189 ([M-C2H5]+, 74), 162 ([M-C4H8]∙+, 52), 161 ([M-C4H9]+, 35), 147 ([M-C5H11]+, 59), 134 (38), 120 (53), 92 ([M-C9H18]∙+, 100), 78 (48).
Catalysis Experiment with
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K6. Result: colourless, slightly cloudy solution. GC/MS: 4.3 min (triethylphosphate, 47%), 11.0 min (mesitylaldehyde, 42%).
Triethylphosphate. Retention time: 4.3 min; MS (EI): m/z = 182 (fragment, relative intensity) ([M]∙+, 4%), 155 ([M-C2H3]+, 100), 127 ([M-C4H7]+, 54), 109 (27), 99 ([M-C6H11]+, 65), 81 (20).
Catalysis Experiment with
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K7. Yield: 3.41 g polyketone. Efficiency: 2,200 g PK/g Ni.