The adduct reaction paths for GaN growth by metal organic chemical vapor deposition (MOCVD) were studied by quantum chemical calculations employing density functional theory (DFT). Five possible adduct reaction paths ...The adduct reaction paths for GaN growth by metal organic chemical vapor deposition (MOCVD) were studied by quantum chemical calculations employing density functional theory (DFT). Five possible adduct reaction paths with or without the ex-cess NH3were proposed and the corresponding potential energy surfaces were calculated. From the calculation results, it is concluded that after the formation of DMGNH2from TMG:NH3, the further decomposition paths have very slim probability because of the high energy barriers; whereas the oligomerization pathway to form oligomers [DMGNH2]x(x=2, 3) is probable,because of zero energy barrier. Since the oligomers tend to further polymerize, the nanoparticles are easily formed through this path. When NH3is in excess, TMG:NH3 tends to combine with the second NH3to form two new complexes: the coordination-bonded compound H3N:TMG:NH3and the hydrogen-bonded compound TMG:NH3 NH3. The formation of hydrogen-bonded compound TMG:NH3 NH3 will be more probable because of the lower energy than H3N:TMG:NH3. By comparing the potential energy surfaces in five adduct reaction paths, we postulate that, under the growth conditions of GaN MOCVD, the formation of hydrogen-bonded compound TMG:NH3 NH3 followed by the reversible decomposition may be the main reaction path for GaN thin film growth; while the adduct oligomerization path to generate oligomers [DMGNH2]2 and [DMGNH2]3might be the main reaction path for nanoparticles formation.展开更多
Aliphatic α-oxo ketene cyclic dithioacetals 1 were reacted with allyl magne- sium bromide to afford the 1,2-addition products 2.Catalyzed by boron trifluoride etherate,the adducts 2 were etherified by methanol to aff...Aliphatic α-oxo ketene cyclic dithioacetals 1 were reacted with allyl magne- sium bromide to afford the 1,2-addition products 2.Catalyzed by boron trifluoride etherate,the adducts 2 were etherified by methanol to afford the corresponding methyl ethers 3.This process provides a new method for the protection of the acid sensitive hydroxyl group in 2 under mild condition.展开更多
The ion-molecule reactions of disubstituted benzenes with the ion system of acetyl chloride under the chemical ionization condition were examined and the fragmentation reactions of the adduct ions formed by the ion-mo...The ion-molecule reactions of disubstituted benzenes with the ion system of acetyl chloride under the chemical ionization condition were examined and the fragmentation reactions of the adduct ions formed by the ion-molecule reactions were studied by using collision-induced dissociation technique. It was found that the electron-releasing groups favored the adduct reactions and the electron-withdrawing groups did not. The position and properties of substituting groups had an effect on the relative abundance of the adduct ions. The fragmentation reaction of the adduct ions formed by ortho-benzene diamine with the acetyl ion was similar to the reductive alkylation reaction of amine in condensed phase.展开更多
The adductive reaction of Ni[S2P(OCH2CH2Ph)2]2 with pyridine was studied by spectrographic method and the equilibrium constants was found to be β1=(1.12±0.09)×102,β2=(2.40±0.41)×104,R1=0.997,R2=0...The adductive reaction of Ni[S2P(OCH2CH2Ph)2]2 with pyridine was studied by spectrographic method and the equilibrium constants was found to be β1=(1.12±0.09)×102,β2=(2.40±0.41)×104,R1=0.997,R2=0.998.The adduct Ni[S2P(OCH2CH2Ph)2]2·2Py was characterized by elemental analysis,IR spectra,single-crystal X-ray diffraction method.The crystal structure belongs to monoclinic system,space group P 21/c with the following crystallographic parameters:a=9.240(3),b=16.124(8),c=14.148(7),α=90.00°,β=92.07(4)°,γ=90.00°.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 61176009)
文摘The adduct reaction paths for GaN growth by metal organic chemical vapor deposition (MOCVD) were studied by quantum chemical calculations employing density functional theory (DFT). Five possible adduct reaction paths with or without the ex-cess NH3were proposed and the corresponding potential energy surfaces were calculated. From the calculation results, it is concluded that after the formation of DMGNH2from TMG:NH3, the further decomposition paths have very slim probability because of the high energy barriers; whereas the oligomerization pathway to form oligomers [DMGNH2]x(x=2, 3) is probable,because of zero energy barrier. Since the oligomers tend to further polymerize, the nanoparticles are easily formed through this path. When NH3is in excess, TMG:NH3 tends to combine with the second NH3to form two new complexes: the coordination-bonded compound H3N:TMG:NH3and the hydrogen-bonded compound TMG:NH3 NH3. The formation of hydrogen-bonded compound TMG:NH3 NH3 will be more probable because of the lower energy than H3N:TMG:NH3. By comparing the potential energy surfaces in five adduct reaction paths, we postulate that, under the growth conditions of GaN MOCVD, the formation of hydrogen-bonded compound TMG:NH3 NH3 followed by the reversible decomposition may be the main reaction path for GaN thin film growth; while the adduct oligomerization path to generate oligomers [DMGNH2]2 and [DMGNH2]3might be the main reaction path for nanoparticles formation.
文摘Aliphatic α-oxo ketene cyclic dithioacetals 1 were reacted with allyl magne- sium bromide to afford the 1,2-addition products 2.Catalyzed by boron trifluoride etherate,the adducts 2 were etherified by methanol to afford the corresponding methyl ethers 3.This process provides a new method for the protection of the acid sensitive hydroxyl group in 2 under mild condition.
文摘The ion-molecule reactions of disubstituted benzenes with the ion system of acetyl chloride under the chemical ionization condition were examined and the fragmentation reactions of the adduct ions formed by the ion-molecule reactions were studied by using collision-induced dissociation technique. It was found that the electron-releasing groups favored the adduct reactions and the electron-withdrawing groups did not. The position and properties of substituting groups had an effect on the relative abundance of the adduct ions. The fragmentation reaction of the adduct ions formed by ortho-benzene diamine with the acetyl ion was similar to the reductive alkylation reaction of amine in condensed phase.
文摘The adductive reaction of Ni[S2P(OCH2CH2Ph)2]2 with pyridine was studied by spectrographic method and the equilibrium constants was found to be β1=(1.12±0.09)×102,β2=(2.40±0.41)×104,R1=0.997,R2=0.998.The adduct Ni[S2P(OCH2CH2Ph)2]2·2Py was characterized by elemental analysis,IR spectra,single-crystal X-ray diffraction method.The crystal structure belongs to monoclinic system,space group P 21/c with the following crystallographic parameters:a=9.240(3),b=16.124(8),c=14.148(7),α=90.00°,β=92.07(4)°,γ=90.00°.
