Aliphatic and aromatic C–H activation of benzo[h]quinolines by Rh(I). Unique precursor dependent formation of mono-, di- and trinuclear complexes (original) (raw)

2011, Inorganica Chimica Acta

a b s t r a c t Treatment of 7,8-benzo[h]quinoline (bhq-H, 1) and 10-methyl benzo[h]quinoline (bhq-Me, 3) with [Rh(C 2 H 4 ) 2 (THF) 2 ] [BF 4 ] resulted in double C-H activation of aliphatic and aromatic C-H bonds, yielding the Rh(III) complexes 4 and 5, respectively. The structures of 4 and 5 were revealed by X-ray diffraction. The reaction of 1 with two other slightly different rhodium precursors, [Rh(olefin) n (THF) 2 ][BF 4 ] (COE (n = 2), COD (n = 1)), led to completely different products, a dinuclear complex 7 and a trinuclear complex 6, respectively, which were characterized by X-ray diffraction. Complex 6 exhibits a rare linear Rh-Rh-Rh structure. Utilizing excess of 1 with [Rh(COD)(THF) 2 ][BF 4 ] led to the formation of a new product 8 with no C-H bond activation taking place. Additional C-H activation products of 1, cationic and neutral, in the presence of P i Pr 3 (9a, 9b and 10) are also presented. respectively, using a Bruker AMX-400 NMR spectrometer and at 500, 125 and 202 MHz, respectively, for 1 H, 13 C and 31 P, using a Bruker Avance-500 NMR spectrometer and at 250, 101 and 235, respectively, for 1 H, 31 P and 19 F NMR using a Bruker DPX 250 spectrometer. All spectra were recorded at 23°C unless stated otherwise. NMR measurements were performed in CD 2 Cl 2 , C 6 D 6 , CD 3 CN and acetone-D 6 . 1 H, 13 C { 1 H} NMR chemical shifts are reported in ppm down-field from tetramethylsilane. 1 H NMR chemical shifts are referenced to the residual hydrogen signal of the deuterated solvent (7.15 ppm for benzene, 5.32 ppm for dichloromethane, 1.94 ppm for acetonitrile and 2.04 ppm for acetone). In 13 C{ 1 H} NMR measurements the signals of deuterated benzene 1 H NMR (acetone-d 6 ): 9.53 (d, 3 J H,H = 5.4 Hz, 1H, Ar), 8.66 (d, 3 J H,H = 8.3 Hz, 1H, Ar), 8.01 (d, 3 J H,H = 8.8 Hz, 1H, Ar), 7.93 (d, 3 J H,H = 5.9 Hz, 1H, Ar), 7.90 (m, 2H, Ar), 7.85 (d, 3 J H,H = 7.3 Hz, 1H, Ar), 7.62 (d, 3 J H,H = 7.6 Hz, 1H, Ar), 4.19 (dd, 2 J Rh,H = 10.1 Hz, 2 3 J Rh,C = 2.0 Hz, Ar), 115.04 (s, Ar), 110.11 (d, 2 J Rh,C = 2.40 Hz, Ar), 105.56 (br s, Ar), 97.80 (dd, 3 J Rh,C = 6.9 Hz, 3 J Rh,C = 102.4 Hz, @CH of COD), 90.76 (d, 3 J Rh,C = 3.4 Hz, @CH of COD), 79.30 (dd, 3 J Rh,C = 13.0 Hz, 3 J Rh,C = 84.1 Hz, @CH of COD), 77.34 (dd, 3 J Rh,C = 13.6 Hz, 3 J Rh,C = 183.7 Hz, @CH of COD), 32.05 (s, -CH 2 of COD), 31.18 (s, -CH 2 of COD), 29.49 (s, -CH 2 of COD), 29.0 (d, 3 (CD 2 Cl 2 ): 9.46 (d, 3 J H,H = 3.8 Hz, 1H, Ar), 8.48 (d, 3 J H,H = 7.6 Hz, 1H, Ar), 7.84 (m, 2H, Ar), 7.77 (d, 3 J H,H = 8.9 Hz, 1H, Ar), 7.52 (d, 3 J H,H = 6.4 Hz, 1H, Ar), 7.33 (m, 3 J H,H = 7.6 Hz, 2H, Ar), 2.08 (m, 3 J H,H = 3.8 Hz, 6H, PCH(CH 3 ) 2 ), 1.03 (dist. dd, 3 J H,H = 6.4 Hz, 3 J P,H = 14.0 Hz, 18H, PCH(CH 3 ) 2 ), 0.71 (dist. dd, 3 J H,H = 6.4 Hz, 3 J P,H = 14.0 Hz, 18H, PCH(CH 3 ) 2 ), À12.51 (br s, 1H, Rh-H). 13 C{ 1 H} NMR (CD 2 Cl 2 ): 151.54 (s, Ar), 150.95 (s, Ar), 149.04 (br d, 2