4-tert-Butylpyridinium chloride–4,4′-(propane-2,2-diyl)bis(2,6-dimethylphenol)–toluene (2/2/1)

In the title solvated salt, C9H14N+·Cl−·C19H24O2·0.5C7H7, two molecules of 4,4′-(propane-2,2-diyl)bis(2,6-dimethylphenol) are linkedviaO—H...Cl hydrogen bonds to two chloride ions, each of which is also engaged in N—H...Cl hydrogen bonding to a 4-tert-butylpyridinium cation, giving a cyclic hydrogen-bonded entity centred at 1/2, 1/2, 1/2. The toluene solvent molecule resides in the lattice and resides on an inversion centre; the disorder of the methyl group requires it to have a site-occupancy factor of 0.5. No crystal packing channels are observed.

Bis(dipyridin-2-ylamine-κ2N2,N2′)palladium(II) dinitrate

The asymmetric unit of the title compound, [Pd(C10H9N3)2](NO3)2, contains one half of a cationic PdIIcomplex and one NO3−anion. In the complex, the PdIIion is four-coordinated by four pyridine N atoms derived from the two chelating dipyridin-2-ylamine (dpa) ligands. The PdIIatom is located on an inversion centre, and thus the PdN4unit is exactly planar. The dpa ligand itself is not planar, showing a dihedral angle between the pyridine rings of 39.9 (1)°. The anions are connected to the complex by intermolecular N—H...O hydrogen bonds between the two O atoms of the anion and the N—H group of the cation. Weak intermolecular C—H...O hydrogen bonds additionally link the constituents in the crystal structure. The NO3−anion was found to be disordered over two sites with a site-occupancy factor of 0.55 (10) for the major component.

Determination of site occupancies by the intermeasurement minimization method. I. Anomalous scattering usage for noncentrosymmetric crystals

New methods for the determination of site occupancy factors are described. The methods are based on the analysis of differences between intensities of Friedel reflections in noncentrosymmetric crystals. In the first method (Anomalous-Expert) the site occupancy factor is determined by the condition that it is identical for two data sets: (1) initial data without averaging of Friedel intensities and (2) data that are averaged on Friedel pairs after the reduction of the anomalous scattering contribution. In the second method (anomalous anisotropic intermeasurement minimization method, Anomalous-AniMMM) the site occupancy factor is refined to satisfy the condition that the differences between the intensities of Friedel reflections that are reduced on the anomalous scattering contribution must be minimal. The methods were checked for three samples of RbTi1−xZrxOPO4crystals (A,BandC) with KTiOPO4structure, at 295 and 105 K (five experimental data sets). Microprobe measurements yield compositionsxA,B= 0.034 (5) andxC= 0.022 (4). The corresponding site occupancy factors areQA,B= 0.932 (10) andQC= 0.956 (8). Using Anomalous-AniMMM and three independent refinements for the first and second samples, the initial occupancy factor ofQA,B= 0.963 (15) was improved toQA,B= 0.938 (7). Of the three room-temperature data sets, one was improved toQA,B= 0.934 (2). For the third sample and one data set, the initial occupancy factor ofQC= 1.000 was improved toQC= 0.956 (1). The methods improve the Hirshfeld rigid-bond test. It is discussed how the description of chemical bonding influences the site occupancy factor.