Yingzhong Shen, Yi Pan, H. Gu
2000
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0
Influential Citations
7
Citations
Journal
Main Group Metal Chemistry
Abstract
Reactions of Group 13 metallic alkyls R3M (R = Me, Μ = Al, Ga, In; R = Et, Μ = Al, Ga ) with 2-(N,Ndimethylaminomethyl)-4-methylphenol give five intramolecularly coordinated organometallic complexes in high yields. The compounds obtained have been characterized by elemental analysis, 'H NMR and mass spectroscopy. Single-crystal X-ray analysis has established the molecular structure of dimethylgallium[2(/V,/V-dimethylaminomcthyl)-4-methyl]phenoxide, in which the Ga atom is four coordinate in the structure. Although Group 13 organometallic alkoxides and phenoxides are among the earliest studied Group 13 organometallic compounds [1], they have received a renewed interest recently because of the recognition that these compounds have potential applications as active co-catalysts in polymerization and as precursors in material science [2-5], Simple alkoxides or phenoxides of organoaluminum, gallium or indium have been extensively studied. Intramolecularly coordinated compounds appeared, however, only recently [6-12], Here we report a novel series of intramolecularly coordinated Group 13 organometallic phenoxides with an adjacent amino group as the ancillary coordinative group. A single-crystal structure of dimethylgallium[2-(7V,7Vdimethylaminomethyl)-4-methyl]phenoxide is also described. EXPERIMENTAL All reactions were performed in a glove box under purified nitrogen. The solvents were refluxed with sodium benzophenone and distilled under nitrogen prior to use. 2-(iV,N-Dimethylaminomethyl)-4methylphenol was prepared by Mannich reaction of £>-cresol with formaldehyde and dimethylamine. Trimethylaluminum, triethylaluminum, trimethylgallium, triethylgallium and trimethylindium were provided by the National 863 Program Advanced Material MO Precursors R&D Center of China. 'H NMR data were collected on a Bruker AM-500 NMR spectrometer with TMS as internal standard (in C6D6). Mass spectra were measured on a VG-ZAB-HS spectrometer (electron impact ionization). Elemental analyses were performed on a Perkin-Elmer 240c elemental analyzer. Melting points were observed in sealed capillaries and were uncorrected. Preparation of dimethylaluminum[2-(N,N-dimethylaminomethyl)-4-methyl]phenoxide (1) A solution of 2-(MA'-dimethylaminomethyl)-4-methylphenol (1.65 g, 10 mmol) in 15 ml hexane was added dropwise over a period of 5 min at room temperature with stirring to a solution of Me3Al (0.72 g, 10 mmol) in 10 ml benzene. While methane gas evolved from the mixture, a white precipitate was formed. After the mixture was stirred for an additional 5 min at room temperature, the volatiles were removed in vacuum and the product was recrystallized from a hexane/benzene mixture to afford 1 as colorless crystals (1.88 g, yield: 85%). Melting point: 156 -158°C. 'H NMR: 6.93 [d ( J 5 6 = 8.2 Hz), 1H, Ar Η,], 6.53 [d ( J 6 5 = 8.2 Hz), 1H, ArW6], 6.33 [s, 1H, ArH }] , 3.86 (s, 2H, C//2N), 2.56 (s, 6H, NMe2), 2.3 (s, 3H, ρ -Me) , -0.76 (s, 6H, MMe2). MS data: 42 (51.9%), 57 (56.5%), 73 (24.3%), 78 (19.5%), 101 (12.9%), 115 (11.9%), 129 (19.4%), 131 (21.7%), 161 (100%), 163 (11.2%), 164 (1.9%), 206 (M*26%). Anal, calcd. for CI2H20NOA1: C, 65.13; H, 9.11; N, 6.33. Found: C, 64.97; Η, 9.02; N, 6.08. Preparation of diethylaluminum[2-(N,N-dimethylaminomethyl)-4-methyllphenoxide (2) The preparation was the same as described for 1, using 2-(/V,A'-dimethylaminomethyl)4-methylphenol (1.65 g, 10 mmol) and triethylaluminum (1.14 g, 10 mmol). The crystals were isolated and purified as described for 1, giving 2 (1.96 g) in a yield of 79%. Melting point. 126~128°C. 'H NMR: 6.94 [d (J5,6 = 8.2 Hz), 1H, ArHs], 6.53 [d (J6S = 8.2 Hz), 1H, ArH 6] , 6.33 [s, 1H, ArΉ }], 3.72 (s, 2H, CH2N), 2.37 (s, 6H, NMe2), 2.3 (s, 3H, ρ M e ) , 1.66 [q (J=18, 8Hz), 6H, A1(C//2CH3)2], 1.30 [t (J = 18 Hz), 4H, A1(CH20/3)21. MS data: 56 (10.6%), 58 (100%), 84 (11.4%), 85 (2.8%), 164 (2.4%), 203 (20.0%), 231 (15.9%), 249 (Μ , 4.9%). Anal, calcd. for C,4H24N0A1: C, 67.34; H, 9.71; N, 5.62. Found: C, 66.95; H, 9.34; N, 5.38. Preparation of dimethylgallium/2-(N,N-dimethylaminomethyl)-4-methyl/phenoxide (3) The compound was prepared and purified as described for 1 from 2-(/V,/V-dimethylaminomethyl)4methylphenol (1.65 g, 10 mmol) and trimethylgallium (1.15 g, 10 mmol) and isolated as colorless crystals. Yield 2.32 g (88%). Melting point: 89-91°C. Η NMR: 7.02 [q (J5,6 = 8.6 Hz, J5.3 = 1.6 Hz), 1H, ATH5],