Syntheses, crystal structures and magnetic properties of complexes based on [Ni(L-L)3]2+ complex cations with dimethylderivatives of 2, 2'-bipyridine and TCNQ

From the aqueous-methanolic systems Ni(NO3)2 – LiTCNQ – 5, 5'-dmbpy and Ni(NO3)2 – LiTCNQ – 4, 4'-dmbpy three novel complexes [Ni(5, 5'-dmbpy)3](TCNQ)2 (1), [Ni(4, 4'-dmbpy)3](TCNQ)2 (2) and [Ni(4, 4'-dmbpy)3]2(TCNQ-TCNQ)(TCNQ)2·0.60H2O (3), were isolated in single crystal form. The new compounds were identified using chemical analyses and IR spectroscopy. Single crystal studies of all samples corroborated their compositions and have shown that their ionic structures contain the complex cations [Ni(5, 5'-dmbpy)]2+ (1) or [Ni(4, 4'-dmbpy)]2+ (2 and 3). The anionic parts of the respective crystal structures 1–3 are formed by TCNQ·- anion-radicals and in 3 also by a s-dimerized dianion (TCNQ-TCNQ)2- with a C-C distance of 1.663(5) Å. The supramolecular structures are governed by weak hydrogen bonding interactions. The variable-temperature (2–300 K) magnetic studies of 1 and 3 confirmed the presence of magnetically active Ni(II) atoms with S = 1 and TCNQ·- anion-radicals with S = 1/2 while the (TCNQ-TCNQ)2- dianion is magnetically silent. The magnetic behavior was described by a complex magnetic model assuming strong antiferromagnetic interactions between some TCNQ·- anion-radicals

Analiza wyników przedsiębiorstwa i konkurencyjności w celu usprawnienia decyzji zarządczych

The main aim of this article is to analyse the performance development of the selected Slovak company - Košice International Airport by means of modern approaches of financial performance evaluation linked to designing a strategic Balanced ScoreCard (BSC). The empirical analysis of the company’s financial performance development was performed on the basis of the selected financial ratio indicators and selected prediction models which form input data for creating a new Creditworthy Model (CWM) of performance. Finally, the authors have formulated the company’s Balanced ScoreCard containing new strategic goals interconnected with the analysis of financial performance development to streamline strategic managerial decisions on the global market.Głównym celem tego artykułu jest analiza rozwoju wydajności wybranej słowackiej firmy - międzynarodowego lotniska w Koszycach za pomocą nowoczesnych metod oceny wyników finansowych związanych z opracowaniem strategicznej karty wyników (BSC). Empiryczna analiza rozwoju wyników finansowych firmy została przeprowadzona na podstawie wybranych wskaźników finansowych i wybranych modeli predykcyjnych, które tworzą dane wejściowe do tworzenia nowego modelu wiarygodności kredytowej (CWM). Wreszcie, autorzy sformułowali zrównoważoną kartę wyników firmy, zawierającą nowe cele strategiczne połączone z analizą wyników finansowych w celu usprawnienia strategicznych decyzji zarządczych na globalnym rynku

Magnetic specific heat of anion-radical salt [Ni(bipy)₃](TCNQ)₄·(CH₃)₂CO at very low temperatures

Thermodynamic studies of the anion-radical salt system [Ni(bipy)₃](TCNQ)₄·(CH₃)₂CO, where TCNQ is 7,7',8,8'-tetracyano-quinodimethane, are reported. The anion-radical salt systems based on TCNQ belong to a material class in which the arrangement of the anion-radical salt has considerable impact on the charge transfer and magnetic properties. The crystal structure of the studied compound consists of [Ni(bipy)₃]⁺² cations containing Ni⁺² ions and four types of crystallographically independent anion-radicals TCNQ^{·-} (A, B, C and D). These TCNQ^{·-} radicals form two different types of TCNQ^{·-} stacks (AABB and CCDD), where a strong exchange interaction is expected. The temperature dependence of the specific heat of a single crystal was studied in magnetic fields up to 5 T and in the temperature range from 0.4 K to 30 K. The temperature dependence of specific heat displays a broad Schottky-like maximum above 0.4 K. Using a single-ion approximation, the analysis of the temperature dependence of the specific heat below 10 K yields values for the anisotropy parameters, D/k_{B}=-1.95 K and E/k_{B}=0.3 K. These results suggest that the observed maximum in the specific heat originates from Ni⁺² ions while the exchange interaction between the transition metal ions and the TCNQ is negligible

NMR investigation of guest-host complex between chloroform and cryptophane C

International audienceGuest–host complex between cryptophane C, possessing two non-equivalent caps, and chloroform is investigated by NMR spectroscopy. The kinetics of the chloroform exchange between the bound and free sites is determined by 1H exchange spectroscopy. Moreover, the preferential orientation of chloroform molecule with respect to the cryptophane C frame is examined by the NOESY and ROESY experiments. The experimental findings are compared to the results of quantum chemical calculations. Copyright © 2010 John Wiley & Sons, Ltd