Haruhiko Fukaya

DFT‐GIAO calculations of 19F NMR chemical shifts for perfluoro compounds

The 19F NMR shieldings for 53 kinds of perfluoro compounds were calculated by the B3LYP‐GIAO method using the 6‐31G(d), 6‐31+G(d), 6‐31G(d,p), 6‐31++G(d,p), 6‐311G(d,p), 6‐311++G(d,p), 6‐311G(2d,2p), 6‐311++G(2d,2p), 6‐311++G(2df,2p), 6‐311++G(3d,2p), and 6‐311++G(3df,2p) basis sets. The diffuse functions markedly reduce the difference between the calculated and experimental chemical shifts. The calculations using the 6‐31++G(d,p) basis set give the chemical shifts within 10 ppm deviations from experimental values except for the fluorine nuclei attached to an oxygen atom, a four‐ and a six‐coordinated sulfur atom, and FC(CF3)2 attached to a sulfur atom.

Simons electrochemical fluorination of substituted homopiperazines(hexahydro-1,4-diazepines) and piperazines ☆

Abstract Simons electrochemical fluorination (ECF) of 1,4-dimethyl-1,4-homopiperazine, methyl 4-ethylhomopiperazin-1-ylacetate and 1,4-bis(methoxycarbonylmethyl)-1,4-homopiperazine was studied. For comparison, ECF of three piperazines with a N -(methoxycarbonylmethyl) group(s) was also studied. ECF of 1,4-dimethyl-1,4-homopiperazine gave a low yield of corresponding perfluoro(1,4-dimethyl-1,4-homopiperazine) together with perfluoro(2,6-diaza-2,6-dimethylheptane) as the major product. Corresponding perfluoro(homopiperazines) with mono- and/or di-(fluorocarbonyldifluoromethyl) groups [CF 2 C(O)F] at the 1- and/or 4-position were formed in low yields from methyl 4-ethylhomopiperazin-1-ylacetate and 1,4-bis(methoxycarbonylmethyl)-1,4-homopiperazine, respectively. These new seven-membered perfluoro(1,4-dialkyl-1,4-homopiperazines) were accompanied by the formation of mono- and/or di-basic linear perfluoroacid fluorides resulting from the CC bond scission at the 2- and 3-positions of the ring. From mono- and/or di- N -(methoxycarbonylmethyl)-substituted piperazines, corresponding perfluoropeperazines having the acid fluoride group(s) were formed in low yields.

Solid‐state NMR study of dopant effects on the chemical properties of Mg‐, In‐, and Al‐doped SnP2O7

The effects of doped low‐valence cations on the properties of the SnP2O7 proton conductor at ambient temperature are investigated from changes in solid‐state NMR spectra and nuclear magnetic relaxation times. Although the T1H values increased with decreasing acidity as a result of cation exchange, the 1H chemical shifts moved to lower field in Al‐ and In‐doped materials compared with undoped ones. Furthermore, the shifts changed to higher field in Mg‐doped materials, suggesting the existence of different protonic species in those materials. The bulk phosphate chemical shifts in the 31P dipolar‐decoupling MAS NMR spectra were very similar, regardless of the nature and amount of the doping species. On the other hand, by 1H/31P cross‐polarization MAS NMR, P2O7 signals interacting with an interstitial proton [Q1(proton)] were observed in all the undoped and doped SnP2O7, while acidic P–OH‐type phosphate signals [Q1(acid)] were additionally observed in the Mg‐doped conductor. The different affinity of the proton with the dopants and phosphates caused lower conductivity and larger activation energy in the Mg‐doped materials, compared with those in the In‐ and Al‐doped materials. Copyright