M. Hannu-Kuure

An experimental and theoretical study of the isomerization of mononuclear bis(arylselenolato)bis(triphenylphosphine)platinum complexes [Pt(SeR)2(PPh3)2]

Mononuclear bis(thienylselenolato)bis(triphenylphosphine)platinum [Pt(SeTh) 2 (PPh 3 ) 2 ] (Th=2-thienyl, C 4 H 3 S) has been prepared by the treatment of cis -[PtCl 2 (PPh 3 ) 2 ] with NaSeTh. The 31 P-NMR spectroscopic information indicates that cis -[Pt(SeTh) 2 (PPh 3 ) 2 ] is initially formed in the reaction. Upon prolonged standing in solution it isomerizes to trans -[Pt(SeTh) 2 (PPh 3 ) 2 ] . The reaction of cis -[PtCl 2 (PPh 3 ) 2 ] with LiSeFu (Fu=2-furyl, C 4 H 3 O) affords immediately a mixture of cis - and trans -isomers of [Pt(SeFu) 2 (PPh 3 ) 2 ] with the relative amount of the trans -isomer increasing with time. The recrystallization of the two reaction mixtures yielded cis , anti - and trans , syn -isomers of [Pt(SeTh) 2 (PPh 3 ) 2 ] as well as cis,syn - and trans , anti -isomers of [Pt(SeFu) 2 (PPh 3 ) 2 ]. Their structures were compared with those of cis , anti - and trans , anti -isomers of [Pt(SePh) 2 (PPh 3 ) 2 ]. The geometries and relative stabilities of all isomers of [Pt(SeTh) 2 (PH 3 ) 2 ], [Pt(SeFu) 2 (PH 3 ) 2 ] and [Pt(SePh) 2 (PH 3 ) 2 ] were studied by the use of ab initio molecular orbital techniques in order to model the structures and isomerization of the observed mononuclear selenolato complexes.

C4H3SSeCH2CH2OC6H5: synthesis, characterization and reaction with palladium(II) and nickel(II)

Abstract ThSeCH2CH2OPh (Th=2-thienyl, C4H3S-; Ph=phenyl) (2) has been prepared by the reaction of BrCH2CH2OPh (1) and ThSeLi. The compound was characterized by 13C{1H}- and 77Se-NMR spectroscopy and X-ray crystallography. 2 is monoclinic, space group P21/c, a=10.865(2), b=5.152(1), c=41.996(8) A, β=92.20(3)°. All bond lengths and angles are quite normal as exemplified by the respective SeC(alkyl) and SeC(aryl) bonds of 1.957(6)–1.966(6) and 1.901(7)–1.905(7) A. The lattice is composed of discrete molecules that are joined together by weak hydrogen bonds into a three-dimensional network. Upon treating ThSeCH2CH2OPh with [PdCl2(NCPh)2] and [NiCl2(PPh3)2] in benzene, a dinuclear palladium complex [Pd2Cl2(μ-Cl)(μ-SeTh)(PPh3)2] (3) and a mononuclear complex [PdCl2(PPh3)2] (4) were formed together with a precipitation of NiCl2. The X-ray quality crystals were recrystallized in CH2Cl2. 3·2.5CH2Cl2 is monoclinic, space group C2/c, a=32.907(7), b=14.545(3), c=22.433(5) A, β=114.37(3)° and contains a novel asymmetrical arrangement of one bridging chlorido and thienylselenolato ligand. Both palladium atoms show an square-planar coordination. The terminal PdCl bond lengths are 2.388(1) and 2.346(1) A with slightly longer distances of 2.418(1) and 2.450(1) A involving the bridging chlorido ligand. The PdSe distances are 2.4092(9) and 2.4376(7) A.

Ligand chemistry of alkylselenolates: an experimental and DFT study of the formation and structural characterization of [PtCl2−x(SeR)x(PPh3)2] (x = 1, 2; R = tBu, nBu)

cis-[Pt(SeR)2(PPh3)2] [R =  t Bu (1), n Bu (2)] can be synthesized by the reaction of RSeLi with cis-[PtCl2(PPh3)2] in a molar ratio of 2:1. The reaction of equimolar amounts of cis-[PtCl2(PPh3)2] and RSeLi (R =  t Bu, n Bu) produces a mixture containing cis-[Pt(SeR)2(PPh3)2] and [PtCl(SeR)(PPh3)2] [R =  t Bu (3), n Bu (4)] in addition to unreacted cis-[PtCl2(PPh3)2]. The direct reaction of n BuLi with cis-[PtCl2(PPh3)2] affords cis-[Pt( n Bu)2(PPh3)2] (6). The complexes were characterized by 31P{1H}, 195Pt{1H} and 77Se NMR spectroscopy, as well as by single-crystal X-ray crystallography. Unlike the corresponding arylselenolato complexes, 1 and 2 do not isomerize from cis- to trans-isomers upon standing in solution. However, they are not stable. For example, 2 slowly forms dinuclear [Pt2(μ-Se n Bu)2(Se n Bu)2(PPh3)2] (5) due to the condensation of the mononuclear species. In the solid state, 1 and 2 crystallize as cis,anti-isomers. It was furthermore observed that the n-butyl groups can adopt various conf...

and comparative equilibrium study of alkali metal cation hydroxide complexes in aqueous solutions. First numerical value for CsOH formation

Abstract 7 Li , 23 Na , 39 K and 133 Cs NMR spectrometric comparative study of 0.05 M alkali metal chloride hydrolysis in aqueous solutions 3.4 M Me 4 NCl / Me 4 NOH at 25 °C is performed. It is found that chemical shifts of all nuclei involved are sensitive to variations of ionic strength and pH. Stability constants for Li+, Na+, K+ and Cs+ lg K( M + OH ⇔ MOH ) are found to be −0.04 (0.05), −0.93 (0.04), −0.7 (0.2) and −0.8 (0.1), respectively. The stability of CsOH is estimated to be the same as that of NaOH and KOH within an experimental error. No evidence of chloro-complexes formation was found.

Stability constants of cesium complexes with 18-crown-6 in ionic liquids

The stability constants of the complex[Cs(18C6)]+ (18C6 is 18-crown-6 (L)) in N-butylpyridinium methyl sulfate (I) and of the complex [Cs(18C6)2]+ in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (II) were measured by using 133Cs NMR spectroscopy at 23°C. It was found that logK(Cs + L) in solvent I is 1.20±0.13 and logK(CsL + L) in solvent IIis 1.18±0.05. For the complex [Cs(18C6)2]+, the dependence of its stability constant on the temperature in the 23–50°C range was obtained and the enthalpy change in the complexation was determined: ΔH(CsL + L)= −47 kJ/mol. It was demonstrated that the enthalpy change is favorable for the formation of [Cs(18C6)2]+, while the entropy change hinders the complexation.

Stability constant of the sodium complex with 18-crown-6 in the mixed water-ionic liquid solvent

The stability constant of the Na+ complex with dibenzo-18-crown-6, [Na(DB18C6)]+, was measured by the 23Na NMR method in the mixed water-ionic liquid solvent at 23°C. N-Butyl-4-methylpyridinium tetrafluoroborate (BMPTB) was used as room temperature ionic liquid. It was found that for the solvent containing 0.8 mol fraction of water and 0.2 mol fraction of BMPTB, the value log K = 0.77 ± 0.05. The addition of BMPTB to water was found to increase the solubility of the crown ether but to decrease the sodium nitrate solubility.

Complexation of strontium with triisopropyl ester of dichloromethylene-bis(phosphonic acid) in water and ionic liquids

AbstractThe complexation of strontium with triisopropyl ester of dichloromethylene-bis(phosphonic acid) (NaL) is examined using 31P NMR in water and the hydrophilic ionic liquid 1-butyl-3-methylimidazolium dicyanamide ([BMIM][N(CN)2]): The values of stability constants of complex SrL are reported: logK1 = −0.37 ± 0.05 (water, I = 0.07 mol/L, 25°C) and 3.0 ± 0.1 (ionic liquid, 25°C).

Crystal structure of chlorido(phenylselenolato)bis(triphenylphosphine)-platinum(II) - benzene (1:1), Pt(C6H5Se)(C18H15P)2Cl · C6H6

C48H41ClP2PtSe, triclinic, P1 (no. 2), a =1 0.1598(2) A, b =1 3.8660(5) A, c = 14.7308(3) A, = 79.595(1)°, =8 6.006(2)°, =8 7.997(2)°, V = 2035.6 A 3 , Z = 2, Rgt(F) = 0.029, wRref(F 2 ) = 0.070, T =1 50 K.