119Sn- and 31P-NMR. Spectroscopy of the 5-coordinate complexes [Rh (SnClnBr(3−n)) (norbornadiene) (tertiary phosphine)2]

The products of the reaction of [RhCl (NBD)]₂ (NBD = norbornadiene), with four equivalents tertiary phosphine and two equivalents of tin (II) bromide have been studied by ¹¹⁹Sn- and ³¹P-NMR. spectroscopy. The solution data suggest that halogen scrambling occurs during the preparation and results in a mixture of complexes containing SnBr₃, SnClBr₂, and SnCl₂Br and SnCl₃ ligands, and this is confirmed by independent synthesis of the SnCl₃ and SnBr₃ complexes. The metalmetal coupling constants, ¹J (¹¹⁹Sn, ¹⁰³Rh), vary from 452 to 580 Hz and are linearly related to: (a) δ(¹¹⁹Sn) in the complexes [Rh (SnCl_nBr_(3-n))NBD (PEtPh₂)₂] and (b) the sum of the Pauling electronegativities for the halogens on tin.     

Kombinierte d-NMR- und LIS-Untersuchungen zum konformativen Verhalten von Formylmethylenthiopyranen

The rotational barriers ΔG ^≠ toE,Z- ands-cis, s-trans-isomerisation in formylmethylenthiopyranes are determined and discussed with regard to their dependence on substituent effects. Preferential conformers are distinguished by lanthanide induced shifts. Best fits between calculated and experimental shifts are obtained forE,s-trans andZ,s-cis isomers. The results indicate a nonbonding interaction between aldehyde oxygen and ring sulphur, favourings-cis conformation in case ofZ configuration.     

Investigation of response of CR-39, PM-355 and PM-500 types of nuclear track detectors to energetic carbon ions

Samples of CR-39, PM-355, and PM-500 plastic detectors were irradiated with carbon ions of energy ranging from 0.9 MeV to 14.7 MeV. After the irradiation the detector samples were etched for a period from 2 hrs to 10 hrs. Dependence of track diameters on the ion energy values for different etching times, and dependence of V_T/V_B as a function of incident carbon-ion energy, are presented.     

Quantification of composition and domain sizes of industrial poly(phthalamide)/poly(dimethylsiloxane) block copolymers using different 1H solid state NMR methods

We have applied several 1H solid state NMR techniques to obtain structural information on industrial silicone copolymers as thermoplastic elastomers that proved difficult to be analysed by conventional techniques. Static measurements were applied to achieve the separation between mobile and rigid parts. To get structural information fast magic angle spinning at 25 kHz in combination with a high field of 700 MHz was used. 1H spin diffusion was applied to determine the domain sizes of the micro phase-separated polymer components.     

A highly efficient titanium-based olefin polymerisation catalyst with a monoanionic iminoimidazolidide pi-donor ancillary ligand

The titanium complex Cp[1,3-(2',6'-Me2C6H3)2(CH2N)2C=N]Ti(CH2Ph)2, with a monoanionic eta 1-iminoimidazolidide ancillary ligand, is shown to be a highly efficient catalyst for olefin polymerisation when activated with the Lewis acid B(C6F5)3.