Takaaki Sonoda

Magnitude and Origin of the Attraction and Directionality of the Halogen Bonds of the Complexes of C6F5X and C6H5X (X=I, Br, Cl and F) with Pyridine

The geometries and interaction energies of complexes of pyridine with C(6)F(5)X, C(6)H(5)X (X = I, Br, Cl, F and H) and R(F)I (R(F) = CF(3), C(2)F(5) and C(3)F(7)) have been studied by ab initio molecular orbital calculations. The CCSD(T) interaction energies (E(int)) for the C(6)F(5)X-pyridine (X = I, Br, Cl, F and H) complexes at the basis set limit were estimated to be -5.59, -4.06, -2.78, -0.19 and -4.37 kcal  mol(-1) , respectively, whereas the E(int) values for the C(6)H(5)X-pyridine (X = I, Br, Cl and H) complexes were estimated to be -3.27, -2.17, -1.23 and -1.78 kcal  mol(-1), respectively. Electrostatic interactions are the cause of the halogen dependence of the interaction energies and the enhancement of the attraction by the fluorine atoms in C(6)F(5)X. The values of E(int) estimated for the R(F)I-pyridine (R(F) = CF(3), C(2)F(5) and C(3)F(7)) complexes (-5.14, -5.38 and -5.44 kcal  mol(-1), respectively) are close to that for the C(6)F(5)I-pyridine complex. Electrostatic interactions are the major source of the attraction in the strong halogen bond although induction and dispersion interactions also contribute to the attraction. Short-range (charge-transfer) interactions do not contribute significantly to the attraction. The magnitude of the directionality of the halogen bond correlates with the magnitude of the attraction. Electrostatic interactions are mainly responsible for the directionality of the halogen bond. The directionality of halogen bonds involving iodine and bromine is high, whereas that of chlorine is low and that of fluorine is negligible. The directionality of the halogen bonds in the C(6)F(5)I- and C(2)F(5)I-pyridine complexes is higher than that in the hydrogen bonds in the water dimer and water-formaldehyde complex. The calculations suggest that the C-I and C-Br halogen bonds play an important role in controlling the structures of molecular assemblies, that the C-Cl bonds play a less important role and that C-F bonds have a negligible impact.

On the characteristics of electrolytes with new lithium imide salts

Abstract In our continuous study on organic lithium salts, we found that the imide salt (RfSO 2 )(R′fSO 2 )NLi shows high conductivity in organic solvents, and that the modification of the imide salts change the anodic oxidation potential and the dissolution potential of aluminum current collector. Lithium imide with long fluoroalkyl groups such as (C 4 F 9 SO 2 )(CF 3 SO 2 )NLi and the new ester-type imide salts, ((CF 3 ) 2 CHOSO 2 ) 2 NLi do not dissolve the aluminum collector up to 4.8 and 4.3 V, respectively. We also examined the polymer analogue of the ester-type imide salt such as (-CH 2 (CF 2 ) 4 CH 2 OSO 2 N(Li)SO 2 O-) 9–10 .

Characteristics of the electrolyte with fluoro organic lithium salts

Some fluoro organic lithium salts have attractive features as organic electrolyte such as solubility, conductivity, and oxidation potentials. The fluoro organic lithium salts with SO 2 groups show higher conductivities than those with CO groups. Methide (CF 3 SO 2 ) 3 CLi and imide (RfSO 2 ) 2 NLi salts show higher conductivities than oxide salts RfSO 2 OLi with only one RfSO 2 group. The lithium salts with long fluoroalkyl groups and two or more RfSO 2 groups show high oxidation potentials and high aluminum corrosion potentials over 4.3 V. The battery performances of modified imide salts such as (C 2 F 5 SO 2 ) 2 NLi, (C 4 F 9 SO 2 )(CF 3 SO 2 )NLi, and ((CF 3 ) 2 CHOSO 2 ) 2 NLi are satisfactory. The cycle characteristics of the imide salt cells are better than those of the LiPF 6 cell. Especially, the ((CF 3 ) 2 CHOSO 2 ) 2 NLi shows the best cycle characteristics. In XPS analysis the anode surfaces of the imide cells are covered with imide salt components.

Highly effective vinylogous Mukaiyama-Michael reaction catalyzed by silyl methide species generated from 1,1,3,3-tetrakis(trifluoromethanesulfonyl)propane.

Silyl methide species in situ generated from 1,1,3,3-tetrakis(trifluoromethanesulfonyl)propane (Tf(2)CHCH(2)CHTf(2)) performed as an excellent acid catalyst for the vinylogous Mukaiyama-Michael reaction of alpha,beta-unsaturated ketones with 2-silyloxyfurans. Notably, the required loading of Tf(2)CHCH(2)CHTf(2) to obtain the 1,4-adducts in reasonable yield was significantly low (from 0.05 to 1.0 mol %). This carbon acid-mediated VMM reaction provides a powerful synthetic methodology to construct highly substituted gamma-butenolide structure.

A novel synthesis of 1,1-difluoroolefins from 1,1,1-trifluoroethyl p-toluenesulfonate VIA boron ate-complex

Abstract The nucleophilic substitution of gem -difluorovinylic tosyloxy group with alkyl groups is effected by treating 2,2-difluoro-1-tosyloxyvinyllithium with trialkylboranes to afford 1,1-difluoroolefins in good yields.

A facile synthesis of disubstituted 1,1-difluoro-1-alkenes via double transmetalation of 2,2-difluorovinylboranes

Abstract 2,2,2-Trifluoroethyl p-toluenesulfonate is treated with butyllithium and trialkylboranes successively to generate 1-alkyl-2,2-difluorovinylboranes, which couple with aryl iodides in the presence of cuprous iodide and palladium catalyst to afford 1,1-difluoro-1-alkenes in excellent yields.

A one-pot synthesis of 2,2-difluorovinyl carbonyl compounds from 2,2,2-trifluoroethyl p-toluenesulfonate via 2,2-difluorovinylboranes

Abstract 2,2,2-Trifluoroethyl p-toluenesulfonate is treated with butyllithium and trialkylboranes successively to generate 1-alkyl-2,2-difluorovinylboranes, which in turn react with acyl chlorides or chloroformates in the presence of cuprous iodide to afford 2,2-difluorovinyl carbonyl compounds in good yields.

Electronic structures and electrochemical properties of LiPF6-n(CF3)n

We evaluated (1) thermal and electrochemical stability and (2) ion-dissociation ability of PF 6-n (CF 3 ) n anions by computational method. The thermal stability order by ΔΔE (anion) is PF 4 (CF 3 ) - 2 > PF 5 (CF 3 ) > PF 3 (CF 3 ) - 3 > PF - 6 . The ion-dissociation ability order by ΔΔE (Li salts) is LiPF 3 (CF 3 ) 3 > LiPF 4 (CF 3 ) 2 > LiPF 5 (CF 3 ) > LiPF 6 . The conductivity of electrolyte solution with LiPF 4 (CF 3 ) 2 (3.9 mS/cm) was a little lower than that of LiPF 6 (4.4 mS/cm) in 0.1 mol/l Li salt/PC:DME electrolyte, while the oxidation potential of LiPF 4 (CF 3 ) 2 in PC was higher than that of LiPF 6 . The LiPF 4 (CF 3 ) 2 -cell showed better cycle characteristics than LiPF 6 -cell.

A facile in-situ diazo-coupling reactions under two-phase conditions catalyzed by tetrakis[3,5-bis(trifluoromethyl)phenyl]borate ion

In-situ diazo-coupling and N- and C-nitrosations under CH2Cl2-aq.H2SO4 two-phase systems have proved to be catalyzed by TFPB ion.

Reactions of 2,2-difluoroalkenylboranes with halogens in the presence of base. Novel syntheses of symmetrically disubstituted 1,1-difluoro-1-alkenes and 1,1-difluoro-2-iodo-1-alkenes

Abstract Treatment of 2,2-difluoroalkenylboranes with bromine and iodine causes coupling reaction and halogenolysis to afford the title compounds in a reverse manner to nonfluorinated counterpart.