Mixed ligand complexes of AEE hexafluoroacetylacetonates with diglyme: Synthesis,crystal structure and thermal behavior

The novel mixed ligand complexes [Ca(hfa)₂(diglyme)(H₂O)] (I), [Sr(hfa)₂(diglyme)(H₂O)] (II) and [Ba(hfa)₂(diglyme)₂] (III) (Hhfa = 1,1,1,5,5,5-hexafluoropentane-2,4-dione, diglyme = 2,5,8-trioxanonane) were synthesized by the reactions of the alkaline earth element (AEE) carbonates in n-hexane with a mixture of Hhfa and diglyme, and they were characterized by elemental analysis, ¹H and ¹³C NMR, and FTIR spectroscopy. The crystal structures of I–III, consisting of mononuclear isolated molecules, have been determined. The thermal behavior and composition of the vapor phase have been studied for I–III by thermal analysis at low pressure and mass spectrometry using a Knudsen cell. The stability of the mixed ligand complexes [M(hfa)₂(diglyme)_n] to the removal of diglyme molecules under heating decreases in the row I > II ≈ III, and only I evaporates as the mixed ligand complex after water removal.     

Copper(II)–lanthanide(III) 15-metallacrown-5 complexes based on pyrazinohydroxamic acid as new multiple-binding pentagonal platforms with Lewis amphoteric nature

Reaction of copper(II) acetate, lanthanium(III) or gadolinium(III) nitrate (1/5 equiv.) with pyrazinohydroxamic acid (H₂Pyzha) in DMF led to a series of new heterobimetallic 15-metallacrown-5 complexes. In a MeOH/H₂O solution the complexes exist as molecular unassociated metallacrowns. In solid state their structures are more complicated as it has been confirmed by X-ray analysis: discrete molecular metallacrowns [Gd(NO₃)₂{Cu(pyzha)}₅(DMF)₄(NO₃)] · 0.5C₆H₆ · H₂O (1), [Gd(NO₃)₂{Cu(pyzha)}₅(DMF)₅](NO₃) · 1.5DMF · 0.5H₂O (2), [La(NO₃)₂{Cu(pyzha)}₅(DMF)₅]NO₃ · 1.5DMF · 2C₆H₆ (3) are solvates, whereas compound [{La(NO₃)₂{Cu(pyzha)}₅(DMF)₅}₂(μ²-NO₃)](NO₃) · 3DMF (4) is a dimer, where μ-bridged nitrate links two copper centres of the adjacent metallamacrocycles. Complex [Gd(NO₃)₂{Cu(pyzha)}₅(DMF)₂(H₂O)(NO₃)] · CH₂Cl₂ · DMF (5) self-associates into a polymer chain by means of one pyrazine moiety and the copper ring atom. Reaction of the molecular metallacrowns with excess of inorganic salts CdBr₂ or Cu(OAc)₂ proceeds as anion methathesis process affording heteroanionic metallacrowns: molecular [Gd(NO₃)₂{Cu(pyzha)}₅(DMF)₅] [Gd(NO₃)₂{Cu(pyzha)}₅(DMF)₄(H₂O)][CdBr₄] · 1.5DMF (6), and 3D hydrogen bonded polymer [La(μ²-OAc)(H₂O)₃{Cu(pyzha)}₅ (H₂O)₄(NO₃)](NO₃) · 4H₂O (7).     

Panel‐based stratified cluster sampling and analysis for photovoltaic outdoor measurements

We study a stratified multisite cluster‐sampling panel time series approach in order to analyse and evaluate the quality and reliability of produced items, motivated by the problem to sample and analyse multisite outdoor measurements from photovoltaic systems. The specific stratified sampling in spatial clusters reduces sampling costs and allows for heterogeneity as well as for the analysis of spatial correlations due to defects and damages that tend to occur in clusters. The analysis is based on weighted least squares using data‐dependent weights. We show that this does not affect consistency and asymptotic normality of the least squares estimator under the proposed sampling design under general conditions. The estimation of the relevant variance–covariance matrices is discussed in detail for various models including nested designs and random effects. The strata corresponding to damages or manufacturers are modelled via a quality feature by means of a threshold approach. The analysis of outdoor electroluminescence images shows that spatial correlations and local clusters may arise in such photovoltaic data. Further, relevant statistics such as the mean pixel intensity cannot be assumed to follow a Gaussian law. We investigate the proposed inferential tools in detail by simulations in order to assess the influence of spatial cluster correlations and serial correlations on the test's size and power. ©2016 The Authors. Applied Stochastic Models in Business and Industry published by John Wiley & Sons, Ltd.     

3-Amino-1,2,4-triazolium salts as NHC-proligands: synthesis and postmodification of a new type of amino-functionalized Pd/NHC complexes

1. Download : Download high-res image (100KB)
2. Download : Download full-size image