55988-54-0Relevant articles and documents
Crystal structures of chloro(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)Cl2, and dihydroxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OH)2, and two-stage hydrolysis of its homologue dimethoxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp) (OMe)2
Lin, Shwu-Juian,Chen, Yao-Jung,Chen, Jyh-Horung,Liao, Feng-Ling,Wang, Sue-Lein,Wang, Shin-Shin
, p. 2843 - 2850 (1997)
The crystal structures of chloro(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)Cl2, dimethoxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OMe)2, and dihydroxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OH)2, were determined. The coordination sphere of the Ge4+ ion is a distorted octahedron in which the apical sites are occupied by two monodentate Cl- (or OMe-, OH-) groups. The geometry around the germanium centre of the Ge(tpp)Cl2 molecule has Ge(1) - Cl(1) = 2.262(1) and Ge(1) - N(1) = 2.019(2) A. In the structure of Ge(tpp)(OMe)2 the germanium(1)-oxygen distance is 1.826(3), average Ge(1) - N = 2.032(3), and O(1) - C(23) = 1.331(6) A. The structure of Ge(tpp)(OH)2 has Ge(1) - O(1) = 1.809(3) and Ge(1) - N(1) = 2.027(2) A. Two-stage hydrolysis of Ge(tpp)(OMe)2 was studied by 1H and 13C NMR spectroscopy. The use of a limited amount of water in CDCl3 (or CD2Cl2) allowed the hydrolysis intermediate, hydroxomethoxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OMe) (OH), and hydrolysis product, dihydroxo(meso-tetraphenylporphyrinato)germanium(IV), Ge(tpp)(OH)2, to be identified. X-ray diffraction data and solid-state 13C CP/MAS spectra of Ge(tpp)(OMe)2 provide evidence for two monodentate methoxo groups coordinated to the germanium(IV) atom.
C-H bond activation with Ge-oxyl complex generated by photoinduced-electron-transfer of di(hydroxo)porphyrin GeIV complex
Shiragami, Tsutomu,Kuroki, Ayano,Matsumoto, Jin,Yasuda, Masahide
, p. 529 - 534 (2015/05/05)
Visible-light irradiation of MeOH solution containing di(hydroxo)tetraphenylporphyrin atogermanium(IV) complex (tppGe(OH)2; 1a), cumene, and Fe3+ ion (Fe(NO3)3) as an electron acceptor gave cumyl alcohol as an oxidative product along with Fe2+ ion as a reductive product. The quantum yield (Φox) and turn over frequency (TOF) for the formation of cumyl alcohol was 0.033 and 111.1 h-1, respectively. The addition of KOH aqueous solution (1 mM) into reaction solution led to an increase of Φox to 0.047. The free energy change (ΔG) with electron transfer from excited triplet state (31a?) to Fe3+ was estimated as a large negative value (-1.37 eV). Furthermore, in 1a-photosensitized oxidation of MeOH in the presence of K2PtCl6 as an electron acceptor, formaldehyde (HCHO) was formed in Φox = 0.034 and TOF = 120.0 h-1. The isotope effect for the formation of HCHO (Φox(H)/Φox(D) = 5.04) was observed when MeOH-d4 was employed as an substrate. Both formation of cumyl alcohol and formaldehyde was not observed at all in the case of photosensitized reactions by tppGe(OMe)2 (1b) having two axial methoxo ligands. These findings indicate the photosensitized reaction was initiated by photoinduced electron transfer from 31a?to Fe3+ or K2PtCl6 to generate porphyrin radical cation (1a+?), which underwent a proton dissociation of hydroxo axial ligand to give tpp(OH)Ge-O? (Ge-oxyl complex) as key intermediate. The Ge-oxyl complex oxidized substrates through a hydrogen-atom abstraction. It is strongly suggested that 1a can act as a good sensitizer for being able to activate C-H bond of organic compounds.
