0000000000154075
AUTHOR
Jussi Kivikoski
Synthesis and characterization of vanadyl(IV) complexes of Schiff bases derived from anthranilic acid and salicylaldehyde (or its derivatives) or acetylacetone. Single crystal X-ray structures of the oxidized products
Anhydrous, dimeric vanadyl(IV) complexes of Schiff bases derived from [1+1] condensation of salicylaldehyde (or its derivatives) and anthranilic acid, have been synthesized from CH3CN and were characterized by elemental analysis, FTIR, EPR, absorption, TGA, cyclic voltammetry and room temperature magnetic susceptibility measurements. These complexes were found to be oxidized by air in polar solvents like MeOH and DMF to V-V products. The E(1/2) values were found to be around 660 mV indicating that the carboxylate group favours vanadyl(IV) binding when compared to the alkoxo-bound vanadium complexes. Oxidative instability of these complexes are dependent on the substituent on the salicylalde…
Crystal structures and absolute configurations of dexmedetomidine and its tosyl derivative
Abstract X-ray diffraction data were used to determine the absolute configuration of dexmedetomidine, a new member of a class of drugs with 4-arylalkyl-1H-imidazole structure. When the anomalous effect of the parent compound proved to be too small for determination of the absolute configuration the tosyl derivative, with the same configuration, was synthesised and used as a reference. Stability of the stereogenic center was verified by HPLC technique. The absolute configuration of the compounds is S. Complete crystal structures are reported for both compounds. Co radiation was used for measurements.
Cyclopentadienyl derivatives of octahedral carbonylcarbide hexaruthenium clusters: synthesis, NMR, IR and X-ray characterization
Abstract The reaction of hexanuclear carbonylcarbide cluster Ru6C(CO)17 (1) with pentamethylcyclopentadiene by reflux in heptane leads to a new chelate cluster Ru6C(μ-η1-η5-CH2C5Me4)(CO)14 (2). The compound 2 contains a CH2 group α-bonded to one of the Ru atoms in the Ru6 cluster and a C5Me4-ligand η5-coordinated by the adjacent Ru atom of the Ru6 cluster. Reflux of 1 in hexane with two molecular equivalents of nickelocene, Ni(C5H5)2 NiCp2, used as a source of cyclopentadiene yields the Ru6C(CO)12Cp2 (3) cluster. The compounds 2 and 3 have been characterized by NMR and IR spectroscopy and their crystal structures determined by X-ray diffraction studies.
Crystal structure of lactitol (4-O-beta-D-galactopyranosyl-D-glucitol).
Abstract Lacitol, C 12 H 24 O 11 , is monoclinic, space group P 2 1 with cell dimensions a = 7.614(1), b = 10.757(1), c = 9.370(1) A, β = 108.19(1)°, and V = 729.0(1) A 3 ; Z = 2, D x = 1.57 Mg.m −3 , λ(Cu- K α ) = 1.5406 A, μ = 1.166 mm −1 , F (000) = 368, and T = 23°. The structure was solved by direct methods and refined by least-squares calculations to R = 0.048 for 1510 unique observed reflections. There are one intra- and eight inter-molecular hydrogen bonds in the structure. Bond lengths and angles accord well with the mean values of related structures. The galactopyranosyl ring has a chair conformation.
Crystal structure of lactitol (4-O-beta-D-galactopyranosyl-D-glucitol) dihydrate.
Abstract Lactitol dihydrate, C 12 H 24 O 11 ·2H 2 O, is tetragonal, space group P 4 3 2 1 2 with cell dimensions a and b = 8.762(1), c = 45.500(3) A, and V = 3493.2(3) A 3 ; Z = 8, D x = 1.45 Mg.m −3 , λ(Cu- K α ) = 1.54056 A, μ = 1.108 mm −1 , F (000) = 1632, and T = 23°. The structure was solved by direct methods and refined by least-squares calculations to R = 0.054 for 2037 unique observed reflections. There are three intra- and twelve inter-molecular hydrogen bonds in the structure. Bond lengths and angles accord quite well with the mean values of related structures. The galactopyranosyl ring has a chair of conformation.
Timolol derivatives. I. X-ray, NMR and theoretical studies of the crystallization of (S)-timolol O,O-diacetyl-l-tartaric acid monoester
Abstract The absolute configurations of (S)-timolol hemihydrate and (S)-timolol O,O-diacetyl-(R,R)-tartaric acid monoester were determined by single crystal X-ray diffraction. An NMR analysis based on the temperature dependence of vicinal coupling constants was carried out to characterize the conformational behaviour of the S,R,R- and R,R,R-forms in solution. The same conformation as in crystalline state was also found in solution, although with a rather low preference over some other conformations. Results of theoretical calculations using MNDO and AMBER force field methods are reported. An infinite chain of hydrogen bonds, along with other favourable inter- and intramolecular forces that …