Jouni Pursiainen

X‐ray and NMR Studies on Host–Guest Inclusion Complex Formation between Crown Ethers and Pyridinium Compounds

Aromatic–aromatic, π–π, and cation–π interactions can be exploited in the preparation of molecular complexes between benzene-substituted crown ethers and pyridium cations. These complexes have been studied in the gas phase, in solution, and in the solid state; the structure of one of the complexes is depicted on the right.

Synthesis and characterisation of HRuRh3(CO)12. Crystal structures of HRuRh3(CO)12, HRuRh3(CO)10(PPh3)2 and HRuCo3(CO)10(PPh3)2

Abstract A new ruthenium-rhodium mixed-metal cluster HRuRh 3 (CO) 12 and its derivatives HRuRh 3 (CO) 10 (PPh 3 ) 2 and HRuCo 3 (CO) 10 (PPh 3 ) 2 have been synthesized and characterized. The following crystal and molecular structures are reported: HRuRh 3 (CO) 12 : monoclinic, space group P 2 1 / c , a 9.230(4), b 11.790(5), c 17.124(9) A, β 91.29(4)°, Z = 4; HRuRh 3 (CO) 10 (PPh 3 ) 2 ·C 6 H 14 : triclinic, space group P 1 , a 11.777(2), b 14.079(2), c 17.010(2) A, α 86.99(1), β 76.91(1), γ 72.49(1)°, Z = 2; HRuCo 3 (CO) 10 (PPh 3 ) 2 ·CH 2 Cl 2 : triclinic, space group P 1 , a 11.577(7), b 13.729(7), c 16.777(10) A, α 81.39(4), β 77.84(5), γ 65.56°, Z = 2. The reaction between Rh(CO) 4 − and (Ru(CO) 3 Cl 2 ) 2 tetrahydrofuran followed by acid treatment yields HRuRh 3 (CO) 12 in high yield. Its structural analysis was complicated by a 80–20% packing disorder. More detailed structural data were obtained from the fully ordered structure of HRuRh 3 (CO) 10 (PPh 3 ) 2 , which is closely related to HRuCo 3 (CO) 10 (PPh 3 ) 2 and HFeCo 3 (CO) 10 (PPh 3 ) 2 . The phosphines are axially coordinated.

Complexation of planar, organic, five-membered cations with crown ethers

Complexation of six aromatic, nitrogen-containing cations with various crown ethers has been studied using 1H NMR, mass spectrometric and crystallographic methods. Hydrogen bonding appears to be the most important interaction in complexation, but minor effects such as π-stacking or cation–π interactions have also been observed. The stability constants of five different imidazolium perchlorate ·crown ether complexes and five other similar cation·DB18C6 complexes were determined by 1H NMR titration in acetonitrile solution. The stability of these complexes in solution and in the gas phase is discussed. The crystal structures of seven complexes were determined in order to study complexation in the solid state. Four of these are imidazolium complexes with different crown ethers and three are complexes of dibenzo-18-crown-6 with similar planar cations.

Oxidation and degradation of native wheat starch by acidic bromate in water at room temperature.

Native wheat starch was oxidized by benign acidic bromate in water at room temperature. HPLC-ELSD study indicated that starch degraded in the course of oxidation but it still had a polymeric structure characterized by (1)H, (13)C, HSQC and HMBC NMR measurements. Products were generally water-soluble fragments but the use of a short reaction time and dilute reaction mixture yielded water-insoluble products. Titration of the products showed, that the increase of the starch content and reaction time increased the content of carbonyl and carboxyl groups in the range of 0.5-2.5% and 1.7-17.2%, respectively, in the product fragments. A mechanism for the oxidation reaction was proposed.

Solid-contact ion-selective electrodes for aromatic cations based on π-coordinating soft carriers

Ion-selective electrodes (ISEs) based on pi-coordinating carriers were prepared and investigated as potentiometric sensors for aromatic cations, using N-methylpyridinium as a model aromatic cation. Derivatives of tetraphenylborate were studied as charged carriers in plasticized poly(vinyl chloride) membranes. Furthermore, neutral compounds containing pi-coordinating anthryl groups were studied as neutral carriers. Bis(2-ethylhexyl)sebacate (DOS) and 2-nitrophenyl octyl ether (o-NPOE) were used as non-polar and polar plasticizer, respectively. ISEs were constructed by using poly(3,4-ethylenedioxythiophene) (PEDOT) as solid-contact material. Conventional ISEs with internal filling solution were used for comparison. The potentiometric responses of the ISEs were investigated using N-methylpyridinium as primary ion. The results show that the selectivity of the ISEs is influenced significantly by both the plasticizer and the charged carriers, while the neutral carriers studied have only a minor influence on the selectivity. The role of cation-pi interactions between aromatic cations and the membrane components is discussed.

Trends in the structure and bonding of [MCl2{(C4H3S)ECH3}2] (M=Pd, Pt; E=Te, Se)

Abstract The complex formation of (C 4 H 3 E)E′Me (E=S, O; E′=Te, Se) ( 1 – 4 ) with palladium and platinum has been explored by use of NMR spectroscopy and X-ray diffraction. Whereas the 125 Te-NMR spectra of [PdCl 2 {(C 4 H 3 E)TeMe} 2 ] [E=S ( 5 ), E=O ( 6 )] show the existence of both cis - and trans -isomers in solution the spectroscopic information of [MCl 2 {(C 4 H 3 E)SeMe} 2 ] (M=Pd, Pt, E=S, O; 8 – 10 ) indicates the presence of only one isomer. The crystal structure determinations have shown that 5 and 6 are isomorphous and crystallize as cis -isomers forming dimers with close chalcogen–halogen contacts. In contrast, 8 and 10 have turned out to be trans -isomers and form skewed stacks that are bound together in a helical arrangement by weak hydrogen bonds. The structural data indicate that back donation may weakly contribute to the palladium–tellurium bonding in 5 and 6 . In 8 and 10 the effects of the back bonding are negligible.

Studies on the synergetic effect of group viii transition metal carbonyls on homogeneous catalysis of the water-gas shift reaction

Abstract Homogeneous catalysis of the water-gas shift reaction by Group VIII mixed metal carbonyls and by mixtures of Group VIII metal carbonyls in pyridine solution was examined under mild conditions (T= 100°C, P co = 0.42–0.60 atm). A weak synergetic effect of Group VIII metals was observed between iron and iridium carbonyls. A stronger synergetic behaviour of mixed metal Fe/Ru catalyst precursors (Fe2Ru(CO)12 and FeRu2(CO)12) was noted. The effect of phosphine and phosphite substitution on Fe2Ru(CO)12 and FeRu2(CO)12 was examined. Only monosubstitution on Fe2Ru(CO)12 was found to have an enhancing effect on catalytic activity. Rhodium carbonyls, which were found to produce the most active catalyst solution under homogeneous water-gas shift conditions, did not show a synergetic behaviour with other Group VIII metals.

M(CO)6 (M=Cr, Mo, W) derivatives of (o-anisyl)diphenylphosphine, bis(o-anisyl)phenylphosphine tris(o-anisyl)phosphine and (p-anisyl)bis(o-anisyl)phosphine

Abstract Aromatic tertiary phosphine ligands having ortho -methoxy substituents reacted with Group 6 metal carbonyls to form complexes with monodentate bonding through the phosphorus atom. One tungsten hexacarbonyl derivative with two P-bonded phosphine ligands was also formed. The complexes were characterized by X-ray crystallography, 1 H, 13 C{ 1 H} and 31 P{ 1 H) NMR spectroscopy, IR spectroscopy and elemental analysis. The steric properties of the ligands were studied by molecular modelling methods. Metal–phosphorus bond distances correlate with cone angles of the phosphines.

Organometallic derivatives of multidentate phosphines [o-(methylthio)phenyl]diphenylphosphine and bis(o-(methylthio)phenyl(phenylphosphine: preparation and characterization of group 6 metal carbonyl derivatives

Heterodonor phosphines [ o -(methylthio)phenyl]diphenylphosphine and bis[ o -(methylthio)phenyl]phenylphosphine react with group 6 metal carbonyls to form chelate complexes with bidentate bonding through P and S atoms. Only Cr(CO) 6 forms also monodentate derivative with [ o -(methylthio)phenyl]diphenylphosphine. The complexes are characterized by X-ray crystallography, 1 H-, 13 C-{ 1 H} and 31 P-{ 1 H}-NMR spectroscopy, IR spectroscopy, and elemental analyses.

Ternary complex formation between Al(III)-adenosine-5′-phosphates and carboxylic acid derivatives

Abstract The possibility of ternary complex formation has been studied in the Al(III)-adenosine-5′-phosphate (AMP, ADP, and ATP)-ligand B (oxalic acid, lactic acid, and malic acid) systems by pH-potentiometric and 31 P NMR methods. Formation of ternary complexes AlABH and AlAB is favored in all systems in the acidic pH range. Under physiological conditions at μmolar Al 3+ concentrations and at high ligand excess, Al(III) is bound mainly to the nucleotides: almost exclusively in the presence of the relatively weak bidentate Al(III) binder oxalic acid and lactic acid, and about 30% in the presence of the much stronger tridentate-coordinating molecule, malic acid.