Crystal structure and Hirshfeld surface analysis of 2-bromo-ethyl-ammonium bromide - a possible side product upon synthesis of hybrid perovskites.

This study presents the synthesis, characterization and Hirshfeld surface analysis of a small organic ammonium salt, C2H7BrN+·Br-. Small cations like the one in the title compound are considered promising components of hybrid perovskites, crucial for optoelectronic and photovoltaic applications. While the incorporation of this organic cation into various hybrid perovskite structures has been explored, its halide salt counterpart remains largely uninvestigated. The obtained structural results are valuable for the synthesis and phase analysis of hybrid perovskites. The title compound crystallizes in the solvent-free form in the centrosymmetric monoclinic space group P21/c, featuring one organic cation and one bromide anion in its asymmetric unit, with a torsion angle of -64.8 (2)° between the ammonium group and the bromine substituent, positioned in a gauche conformation. The crystal packing is predominantly governed by Br⋯H inter-actions, which constitute 62.6% of the overall close atom contacts.

Carbon dioxide capture from air leading to bis-[N-(5-methyl-1H-pyrazol-3-yl-κN2)carbamato-κO]copper(II) tetra-hydrate.

A mononuclear square-planar CuII complex of (5-methyl-1H-pyrazol-3-yl)carbamate, [Cu(C5H6N3O2)2]·4H2O, 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 (N2O2) square-planar coordination environment formed by two N atoms and two O atoms of two equivalent (5-methyl-1H-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 CuII 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.

Crystal structure of bis-(3-carb-oxy-1-methyl-pyrid-inium) octa-bromide.

The crystal structure of the title salt, bis-(3-carb-oxy-1-methyl-pyridinium) octa-bromide, 2C7H8NO2 +·Br8 2-, consists of 3-carb-oxy-1-methyl-pyridinium (N-methyl-nicotinic acid) cations, which are stacked between relatively rare [Br8]2- anions. The polybromide [Br8]2- anion has point group symmetry and can be described as being composed of two [Br3]- anions connected with a Br2 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 [Br8]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).

catena-Poly[[tetra-kis-(3,5-dimethyl-1H-pyrazole-κN 2)copper(II)]-µ2-sulfato-κ2 O:O']: crystal structure and Hirshfeld surface analysis of a CuII coordination polymer.

The title coordination polymer, [Cu(SO4)(C5H8N2)4] n , was synthesized using a one-pot reaction of copper powder, anhydrous copper(II) sulfate and 3,5-dimethyl-1H-pyrazole (Hdmpz) in aceto-nitrile under ambient conditions. The asymmetric unit can be described as a chain consisting of four [Cu(SO4)(Hdmpz)4] formula units that are connected to each other by a µ2-sulfato-bridged ligand. The octa-hedral coordination geometry (O2N4) of all copper atoms is realized by coordination of four pyrazole ligands and two sulfate ligands. Four pyridine-like N atoms of the pyrazole ligands occupy the equatorial positions, while two oxygen atoms of two sulfate ligands are in axial positions. As a result of the sulfate ligand rotation, there is a pairwise alternation of terminal O atoms (which are not involved in coordination to the copper atom) of the SO4 tetra-hedra. The Cu⋯Cu distances within one asymmetric unit are in the range 7.0842 (12)-7.1554 (12) Å. The crystal structure is built up from polymeric chains packed in a parallel manner along the b-axis direction. Hirshfeld surface analysis suggests that the most important contributions to the surface contacts are from H⋯H (74.7%), H⋯O/O⋯H (14.8%) and H⋯C/C⋯H (8.2%) inter-actions.

Spin crossover in iron(II) Hofmann clathrates analogues with 1,2,3-triazole.

Hofmann-like cyanometallic complexes represent one of the biggest and well-known classes of FeII spin-crossover compounds. In this paper, we report on the first FeII Hofmann clathrate analogues with unsubstituted 1,2,3-triazole, which exhibit temperature induced spin transition. Two new coordination polymers with the general formula [FeII(1,2,3-triazole)2MII(CN)4] (M = Pt, Pd) undergo abrupt hysteretic spin crossover in the range of 190-225 K as revealed by magnetic susceptibility measurements. Two compounds are isostructural and are built of infinite cyanometallic layers which are supported by 1,2,3-triazole ligands. The thermal hysteresis loop is very stable at different scan rates from 0.5 to 10 K min-1. The compounds display strong thermochromic effect, changing their colour from pink in the low-spin state to white in the high-spin state. Our findings show that 1,2,3-triazole is suitable for elaboration of spin-crossover Hofmann clathrate analogues, and its use instead of more classical azines can advantageously expand this family of complexes.

Crystal structure of bis-{µ-2-[bis-(2-hy-droxy-eth-yl)amino]-ethano-lato}bis-(µ-3,5-di-methyl-pyrazolato)tricopper(II) dibromide sesquihydrate.

In the title bicyclic trinuclear pyrazolate amino-alcohol complex, [Cu3(C5H7N2)2(C6H14NO3)2]Br2·1.5H2O, the central Cu atom lies on a center of symmetry and is involved in the formation of two five-membered rings. It has a coordination number of 4, is in a distorted tetra-hedral environment and is connected by the bridging oxygen atoms of the deprotonated OH groups of different amino-alcohol groups, and by the N atoms of deprotonated di-methyl-pyrazole ligands. The peripheral Cu atom is in a trigonal-bipyramidal coordination environment formed by the nitro-gen atom of the deprotonated bridging di-methyl-pyrazole unit, the bridging oxygen atom of the deprotonated OH group, two oxygen atoms of the protonated hy-droxy groups and the nitro-gen atom of tri-ethano-lamine. One of the C atoms and the Br- anion were found to be disordered over two positions with occupancy factors of 0.808 (9):0.192 (9) and 0.922 (3):0.078 (3), respectively.

Crystal structure of catena-poly[[[di-aqua-[1,2-bis(pyridin-4-yl)ethene]{4-[2-(pyridin-4-yl)ethen-yl]pyridinium}gold(I)iron(II)]-di-µ-cyanido] bis-[dicyanido-gold(I)] 1,2-bis-(pyridin-4-yl)ethene dihydrate].

In the title compound [Fe(bpe)(Hbpe)Au(CN)2][Au(CN)2]2·bpe·2H2O} n [where bpe = 1,2-bis-(pyridin-4-yl)ethene, C12H10N2], the FeII ion is coordinated in a distorted octa-hedral [FeN4O2] environment by two di-cyano-aurate anions, two water mol-ecules and two partially protonated 1,2-di(4-pyrid-yl)ethyl-ene mol-ecules. Di-cyano-aurate anions bridge the FeII cations, forming infinite chains, which propagate along the a-axis direction. The chains are connected via aurophilic inter-actions with two non-coordinated di-cyano-aurate anions for each FeII ion. The polymeric chains inter-act with each other via π-π stacking between the guest bpe mol-ecules and multiple hydrogen bonds.

Crystal structure of poly[[di-aqua-tetra-µ2-cyanido-iron(II)platinum(II)] acetone disolvate].

In the title polymeric complex, {[FePt(CN)4(H2O)2]·2C3H6O} n , the FeII cation has an octa-hedral [FeN4O2] geometry being coordinated by two water mol-ecules and four cyanide anions. The Pt cation is located on an inversion centre and has a square-planar coordination environment formed by four cyanide groups. The tetra-cyano-platinate anions bridge the FeII cations to form infinite two-dimensional layers that propagate in the bc plane. Two guest mol-ecules of acetone per FeII are located between the layers. These guest acetone mol-ecules inter-act with the coordinated water mol-ecules by O-H⋯O hydrogen bonds.

Crystal structure of a low-spin poly[di-µ3-cyanido-di-µ2-cyanido-bis-(µ2-2-ethyl-pyrazine)-dicopper(I)iron(II)].

In the title metal-organic framework, [Fe(C6H8N2)2{Cu(CN)2}2] n , the low-spin FeII ion lies at an inversion centre and displays an elongated octa-hedral [FeN6] coordination environment. The axial positions are occupied by two symmetry-related bridging 2-ethyl-pyrazine ligands, while the equatorial positions are occupied by four N atoms of two pairs of symmetry-related cyanide groups. The CuI centre is coordinated by three cyanide carbon atoms and one N atom of a bridging 2-ethyl-pyrazine mol-ecule, which form a tetra-hedral coordination environment. Two neighbouring Cu atoms have a short Cu⋯Cu contact [2.4662 (7) Å] and their coordination tetra-hedra are connected through a common edge between two C atoms of cyanide groups. Each Cu2(CN)2 unit, formed by two neighbouring Cu atoms bridged by two carbons from a pair of µ-CN groups, is connected to six FeII centres via two bridging 2-ethyl-pyrazine mol-ecules and four cyanide groups, resulting in the formation of a polymeric three-dimensional metal-organic coordination framework.

Crystal structure of poly[tetra-µ2-cyanido-1:2κ8N:C-bis-(dimethyl sulfoxide-1κO)diargentate(I)iron(II)].

In the title polymeric complex, [Fe{OS(CH3)2}2{Ag(CN)2}2], the FeII cation is located at an inversion centre and is coordinated by four cyanide (CN-) anions and two dimethyl sulfoxide mol-ecules in a slightly compressed N4O2 octa-hedral geometry, the AgI cation is C-coordinated by two CN- anions in a nearly linear geometry. The CN- anions bridge the FeII and AgI cations to form a two-dimensional polymeric structure extending parallel to (102). In the crystal, the nearest Ag⋯Ag distance between polymeric sheets is 3.8122 (12) Å. The crystal studied was a twin with a contribution of 0.2108 (12) for the minor component.