In a Young’s tube, [{SiNDipp}MgNa]2 (4 , 21.6 mg, 0.02 mmol) was dissolved
in 0.4 mL of d6-benzene before the addition
of benzophenone (7.2 mg, 0.04 mmol) to the bright yellow solution.
The reaction mixture instantaneously turned into a purple solution.
The reaction mixture was then left standing at room temperature overnight,
whereupon the formation of orange precipitates was observed. The purple
supernatant was then carefully decanted and examined by EPR spectroscopy.
The orange solid was collected and redissolved in toluene, and bright
yellow crystals suitable for single-crystal X-ray diffraction were
obtained by storage of the orange solution at −30 °C.
This reaction was then repeated with a modified stoichiometry of substrates:
[{SiNDipp}MgNa]2 (4 , 21.6 mg, 0.02
mmol) was dissolved in 0.4 mL of d6-benzene
before the addition of benzophenone (21.6 mg, 0.12 mmol) to the bright
yellow solution. This entry also provided a purple solution with orange
solids when the reaction mixture was kept at ambient temperature overnight.
The purple supernatant provided a virtually identical EPR spectrum,
and the recrystallization of the orange solids provided compound9 (confirmed by unit-cell screening). Yield 6.9 mg, 19%. Compound 9 can also be prepared by treatment of 2 equiv of benzophenone
(7.2 mg, 0.04 mmol) with [{SiNDipp}Mg] (10.4 mg, 0.02 mmol).33a The reaction was conducted with 0.4 mL of C6D6 inside a J-Young’s tube, providing quantitative
conversion into9 (verified by NMR spectroscopy), and
slow evaporation of the benzene solution provided9 as
bright yellow crystals. Yield 15.2 mg, 86%. No meaningful result was
obtained for elemental analysis after multiple attempts. 1H NMR (500 MHz, 298 K, benzene-d6) δ:
7.19–7.16* (m, 8H, ArH,*overlapping with C6D6), 7.14–7.00 (m, 11H, ArH), 6.95–6.92 (m, 7H, ArH), 4.31 (sept, J = 6.9 Hz, 4H, CHMe2), 1.44
(s, 4H, SiCH2), 1.41 (d, J = 6.9 Hz, 12H, CHMe2), 0.89 (d, J = 6.9 Hz, 12H, CHMe2), 0.38
(s, 12H, SiMe2). 13C NMR (126
MHz, 298 K, Benzene-d6) δ: 151.6
(i-C6H3),
151.3 (i-C6H5 on OCPh2), 145.6 (o-C6H3), 133.5 (o-C6H5 on OCPh2), 131.3 (p-C6H5 on OCPh2),
128.6 (m-C6H5 on OCPh2), 123.5 (m-C6H3), 120.3 (p-C6H3), 114.1 (OCPh2), 27.5 (CHMe2), 25.3 (CHMe2), 24.3 (CHMe2), 13.4 (SiCH2), 1.4 (SiMe2).
in 0.4 mL of d6-benzene before the addition
of benzophenone (7.2 mg, 0.04 mmol) to the bright yellow solution.
The reaction mixture instantaneously turned into a purple solution.
The reaction mixture was then left standing at room temperature overnight,
whereupon the formation of orange precipitates was observed. The purple
supernatant was then carefully decanted and examined by EPR spectroscopy.
The orange solid was collected and redissolved in toluene, and bright
yellow crystals suitable for single-crystal X-ray diffraction were
obtained by storage of the orange solution at −30 °C.
This reaction was then repeated with a modified stoichiometry of substrates:
[{SiNDipp}MgNa]2 (
mmol) was dissolved in 0.4 mL of d6-benzene
before the addition of benzophenone (21.6 mg, 0.12 mmol) to the bright
yellow solution. This entry also provided a purple solution with orange
solids when the reaction mixture was kept at ambient temperature overnight.
The purple supernatant provided a virtually identical EPR spectrum,
and the recrystallization of the orange solids provided compound
(7.2 mg, 0.04 mmol) with [{SiNDipp}Mg] (10.4 mg, 0.02 mmol).33a The reaction was conducted with 0.4 mL of C6D6 inside a J-Young’s tube, providing quantitative
conversion into
slow evaporation of the benzene solution provided
bright yellow crystals. Yield 15.2 mg, 86%. No meaningful result was
obtained for elemental analysis after multiple attempts. 1H NMR (500 MHz, 298 K, benzene-d6) δ:
7.19–7.16* (m, 8H, ArH,*overlapping with C6D6), 7.14–7.00 (m, 11H, ArH), 6.95–6.92 (m, 7H, ArH), 4.31 (sept, J = 6.9 Hz, 4H, CHMe2), 1.44
(s, 4H, SiCH2), 1.41 (d, J = 6.9 Hz, 12H, CHMe2), 0.89 (d, J = 6.9 Hz, 12H, CHMe2), 0.38
(s, 12H, SiMe2). 13C NMR (126
MHz, 298 K, Benzene-d6) δ: 151.6
(i-C6H3),
151.3 (i-C6H5 on OCPh2), 145.6 (o-C6H3), 133.5 (o-C6H5 on OCPh2), 131.3 (p-C6H5 on OCPh2),
128.6 (m-C6H5 on OCPh2), 123.5 (m-C6H3), 120.3 (p-C6H3), 114.1 (OCPh2), 27.5 (CHMe2), 25.3 (CHMe2), 24.3 (CHMe2), 13.4 (SiCH2), 1.4 (SiMe2).
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