, Cq-Flu), vol.8, pp.103-110

, mL of a 2.5 M solution in hexane, 2.45 mmol), and HfCl 4 (0.380 g, 1.23 mmol). The compound was recovered as an orange-yellow powder (0.520 g, 0.38 mmol, 62%). 1 H NMR (toluene-d 8, Using a protocol similar to that described above for 3a-Zr, compound 3a-Hf was prepared from 1,4-bis(cyclopenta-2,4-dien-1-yl(3,6-di-tert-butyl-fluoren-9-yl)ethyl)benzene (0.500 g, 0.61 mmol)

. ?-c),

. Appi-ms, Anal. calcd for C 62 H 66

, Using a protocol similar to that described above for 3a-Zr, compound 3b-Zr was prepared from 2b (0.660 g, 0.84 mmol), n-BuLi (1.37 mL of a 2.0 M solution in hexane, 3.37 mmol), and ZrCl 4 (0.392 g, 1.68 mmol). The compound was isolated as a red powder

. Mhz, 7.98 (s, 4H, CH-Ph), 7.67 (m, 4H, CH-Flu), vol.7, p.27

, 64 (s, 2H, CH-ansa), 6.36 (dq, 3 J = 2.5, 4H, CH-Cp), 5.84 (dq, 3 J = 2.5, 4H, CH-Cp), 1.47 (d, 36H, CH 3 -t Bu). 13 C NMR (CD 2 Cl 2 , 125 MHz, 25 ? C): ? 150, 120.3 (Cq), 119.6 (CH-Flu), 119.6 (CH-Cp), 119.5 (CH-Cp), vol.6

, Cp)ZrCl, vol.2, p.3

, Using a protocol similar to that described above for 3a-Zr, compound 3c-Zr was prepared from 2c (0.520 g, 0.64 mmol), n-BuLi (1.0 mL of a 2.5 M solution in hexane, 2.55 mmol), and ZrCl 4 (0.300 g, 1.27 mmol). The product was isolated as a red powder

, MHz, 25 ? C): ? 8.43-8.23 (m, 4H, CH-Flu), 8.05 (m, 2H, CH-Flu), 7.70 (dt, J = 7.8, 1.4, 1H, CH-Flu), 7.63-7.25 (m, 6H, CH-Flu + CH-Ph), 7.06-6.90 (m, 2H, CH-Ph), 6.47 (d, J = 9.1, 1H, CH-Ph), 6.28-6.23 (m, 1H, CH-Flu), 6.23-6.15 (m, 1H, CH-Cp), 6.13-6.04 (m, 1H, CH-Cp), 5.90-5.84 (m, 1H, CH-Cp), 5.74 (m, 1H, CH-Cp), 5.67-5.57 (m, 2H, CH-Cp), 5.55-5.36 (m, 1H, CH-Cp), 5.14 (d, J = 2.7, 1H, CH-Cp), 2.55-2.13 (m, 6H, CH 3

, {Ph(Me)C-(3,6-tBu 2 Flu)(Cp)}ZrCl 2 (3a'-Zr), vol.16

, The compound was isolated as a red powder (0.410 g, 0.67 mmol, 76%). 1 H NMR (toluene-d 8 , 500 MHz, 25 ? C): ? 8.07 (ddd, J = 7.0, 1.9, 0.7, 2H, CH-Flu), 7.43 (dt, J = 7.8, 1.7, 1H, CH-Ph), vol.7

, Using a protocol similar to that described above for 3a-Zr, compound 3b'-Zr was prepared from 2b' (0.430 g, 0.99 mmol), n-BuLi (0.81 mL of a 2.5 M solution in hexane, 1.99 mmol), and ZrCl 4 (0.230 g, 0.99 mmol). The product was isolated as a red powder (0.540 g, 0.86 mmol, 87%), vol.8, pp.558-573, 2018.

, CH-Flu), 6.17-6.05 (m, 2H, CH-Flu), 5.80 (s, 1H, CH), 5.48 (t, J = 2.8, 1H, CH-Cp), 5.29 (t, J = 2.8, 1H, CH-Cp), 1.39 (s, 18H, MHz, 25 ? C): ? 8.24 (s, 2H, CH-Flu), 7.55 (d, J = 7.4, 2H, CH-Ph), 7.42 (d, J = 9.0, 1H, CH-Ph), 7.24 (m, 3H, CH-Ph), 6.99 (d, J = 8.8, 1H, CH-Flu), 6.92 (d, J = 9.1, 1H, CH-Flu), 6.51 (d, J = 9, vol.0, p.105

, The product was isolated as an orange powder (0.076 g, 0.86 mmol, 56%). 1 H NMR (C 6 D 6 , 500 MHz, 25 ? C): ? 8.22 (dt, J = 9, Cp)}HfCl 2 (3b'-Hf) This compound was prepared as described above for 3a starting from 2b' (0.090 g, 0.20 mmol), n-BuLi (0.16 mL of a 2.5 M solution in hexane, 0.41 mmol), and HfCl 4 (0.060 g, 0.2 mmol), vol.18

. Appi-ms, , vol.3

. +?-), Anal. calcd. for C 33 H 34 Cl 2 Hf (680.1503): C 58, vol.29

, Ethylene Homopolymerization and Ethylene/1-hexene Copolymerization Polymerization experiments were performed in a 300 mL high-pressure glass reactor equipped with a mechanical stirrer (Pelton turbine) and externally heated with a double mantle with a circulating water bath. The reactor was filled with toluene (100 mL, p.1

, The reactor was thermally equilibrated at the desired temperature for 30 min, the ethylene pressure was decreased to 1 bar, and a solution of the catalyst precursor in toluene (ca. 2 mL) was added by syringe. The ethylene pressure was immediately increased to 5.5 bar (kept constant with a back regulator), and the solution was stirred for the desired time (typically 15 min). The temperature inside the reactor (typically 60 ? C) was monitored using a thermocouple. The polymerization was stopped by venting the vessel and quenching with a 10% HCl solution in methanol (ca. 2 mL). The polymer was precipitated in methanol (ca. 200 mL), and 35% aqueous HCl (ca. 1 mL) was added to dissolve possible catalyst residues. The polymer was collected by filtration, mL of a 30 wt-% solution in toluene) and pressurized at 5.5 bar of ethylene (Air Liquide, 99.99%)

, Crystal Structure Determination of 3a'-Zr Diffraction data were collected at 150 K using a Bruker APEX CCD diffractometer, 2018.

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