Charge-density analysis using multipolar atom and spherical charge models: 2-methyl-1,3-cyclopent­anedione, a compound displaying a resonance-assisted hydrogen bond

The electron density of 2-methyl-1,3-cyclopentanedione was refined versus synchrotron ultra-high-resolution data using a multipolar model and a virtual and real spherical atoms model. The electrostatic properties were analyzed.

The trimorphic structure of N,N′-bis(5-methyl­salicylidene)-4-methyl-1,3-phenylenediamine

Three crystal forms of the new Schiff base ligand, N,N′-bis(5-methylsalicylidene)-4-methyl-1,3-phenylenediamine, have been found in the course of the synthesis of its complexes with rare earth metals. These forms have different numbers of symmetry-independent molecules (Z′ = 1, 3 and 4); only weak intermolecular interactions are involved in the crystal structure as the strong hydrogen bond donors are engaged in relatively strong intramolecular O—H...N bonds.

Isomorphism and solid solution as shown by an accurate high-resolution diffraction experiment

High-resolution crystal structure determination and refinement of 1-(4'-chlorophenyl)-2-methyl-4-nitro-1H-imidazole-5-carbonitrile revealed the presence of 2.5% of its bromine derivative, which would not be found using standard resolution data (ca 0.8 Å), as disorder was visible only at high resolution.