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A mononuclear square-planar Cu II complex of (5-methyl-1 H -pyrazol-3-yl)carbamate, [Cu(C 5 H 6 N 3 O 2 ) 2 ]·4H 2 O, was synthesized using a one-pot reaction from 5-methyl-3-pyrazolamine and copper(II) acetate in water under ambient conditions. The adsorption of carbon dioxide from air was facilitated by the addition of di-ethano-lamine to the reaction mixture. While di-ethano-lamine is not a component of the final product, it plays a pivotal role in the reaction by creating an alkaline environment, thereby enabling the adsorption of atmos-pheric carbon dioxide. The central copper(II) atom is in an (N 2 O 2 ) square-planar coordination environment formed by two N atoms and two O atoms of two equivalent (5-methyl-1 H -pyrazol-3-yl)carbamate ligands. Additionally, there are co-crystallized water mol-ecules within the crystal structure of this compound. These co-crystallized water mol-ecules are linked to the Cu II mononuclear complex by O-H⋯O hydrogen bonds. According to Hirshfeld surface analysis, the most frequently observed weak inter-molecular inter-actions are H⋯O/O⋯H (33.6%), H⋯C/C⋯H (11.3%) and H⋯N/N⋯H (9.0%) contacts., (© Sirenko et al. 2023.)

The crystal structure of the title salt, bis-(3-carb-oxy-1-methyl-pyridinium) octa-bromide, 2C 7 H 8 NO 2 + ·Br 8 2- , consists of 3-carb-oxy-1-methyl-pyridinium ( N -methyl-nicotinic acid) cations, which are stacked between relatively rare [Br 8 ] 2- anions. The polybromide [Br 8 ] 2- anion has point group symmetry and can be described as being composed of two [Br 3 ] - anions connected with a Br 2 mol-ecule in a Z -shaped manner. Contacts between neighboring octa-bromide anions ensure the creation of pseudo-polymeric chains propagating along [111]. The organic cations are located between anionic chains and are connected to each other through O-H⋯O hydrogen bonds and to the [Br 8 ] 2- anions through π⋯Br inter-actions that induce the creation of a supra-molecular tri-periodic network. In addition, the presence of weak C-H⋯Br contacts leads to the creation of layers, which align parallel to (11)., (© Sirenko et al. 2023.)

9-Amino-acridinium chloride N , N -di-methyl-formamide monosolvate, C 13 H 11 N 2 + Cl - ·C 3 H 7 NO, crystallizes in the monoclinic space group P 2 1 / c. The salt was crystallized from N , N -di-methyl-formamide. The asymmetric unit consists of two C 13 H 11 N 2 + Cl - formula units. The 9-amino-acridinium (9-AA) mol-ecules are protonated with the proton on the N atom of the central ring. This N atom is connected to an N , N -di-methyl-formamide mol-ecule by a hydrogen bond. The H atoms of the amino groups create short contacts with two chloride ions. The 9-AA cations in adjacent layers are oriented in an anti-parallel manner. The mol-ecules are linked via a network of multidirectional π-π inter-actions between the 9-AA rings, and the whole lattice is additionally stabilized by electrostatic inter-actions between ions., (© Fritsky et al. 2021.)

In the asymmetric unit of the title coordination compound, {[Cu(CN)(C 4 H 3 OC 2 H 5 N 2 )][Cu(CN)]} n , there are two Cu atoms with different coordination environments. One Cu I ion is coordinated in a triangular coordination geometry by the N atom of the 2-eth-oxy-pyrazine mol-ecule and by two bridging cyanide ligands, equally disordered over two sites exchanging C and N atoms, thus forming polymeric chains parallel to the c axis. The other Cu atom is connected to two bridging cyanide groups disordered over two sites with an occupancy of 0.5 for each C and N atom, and forming an almost linear polymeric chain parallel to the b axis. In the crystal, the two types of chain, which are orthogonal to each other, are connected by cuprophilic Cu⋯Cu inter-actions [2.7958 (13) Å], forming two-dimensional metal-organic coordination layers parallel to the bc plane. The coordination framework is further stabilized by weak long-range (electrostatic type) C-H⋯π inter-actions between cyano groups and 2-eth-oxy-pyrazine rings., (© Partsevska et al. 2019.)